Phagocyte NADPH oxidase restrains the inflammasome in ANCA-induced GN.
Schreiber Adrian,Luft Friedrich C,Kettritz Ralph
Journal of the American Society of Nephrology : JASN
ANCA-activated phagocytes cause vasculitis and necrotizing crescentic GN (NCGN). ANCA-induced phagocyte NADPH oxidase (Phox) may contribute by generating tissue-damaging reactive oxygen species. We tested an alternative hypothesis, in which Phox restrains inflammation by downregulating caspase-1, thereby reducing IL-1β generation and limiting NCGN. In an antimyeloperoxidase (anti-MPO) antibody-mediated disease model, mice transplanted with either gp91(phox)-deficient or p47(phox)-deficient bone marrow showed accelerated disease with increased crescents, necrosis, glomerular monocytes, and renal IL-1β levels compared with mice transplanted with wild-type bone marrow. IL-1β receptor blockade abrogated aggravated NCGN in gp91(phox)-deficient mice. In vitro, challenge with anti-MPO antibody strongly enhanced caspase-1 activity and IL-1β generation in gp91(phox)-deficient and p47(phox)-deficient monocytes compared with wild-type monocytes. This enhanced IL-1β generation was abrogated when caspase-1 was blocked. ANCA-induced superoxide and IL-1β generation were inversely related in human monocytes. Furthermore, transplantation of gp91(phox)/caspase-1 double-deficient bone marrow rescued the accelerated NCGN phenotype in gp91(phox) bone marrow-deficient mice. These results suggest that Phox-generated reactive oxygen species downregulate caspase-1, thereby keeping the inflammasome in check and limiting ANCA-induced inflammation. IL-1 receptor blockade may provide a promising strategy in NCGN, whereas our data question the benefit of antioxidants.
MAG and OMgp synergize with Nogo-A to restrict axonal growth and neurological recovery after spinal cord trauma.
Cafferty William B J,Duffy Philip,Huebner Eric,Strittmatter Stephen M
The Journal of neuroscience : the official journal of the Society for Neuroscience
Functional recovery after adult CNS damage is limited in part by myelin inhibitors of axonal regrowth. Three molecules, Nogo-A, MAG, and OMgp, are produced by oligodendrocytes and share neuronal receptor mechanisms through NgR1 and PirB. While each has an axon-inhibitory role in vitro, their in vivo interactions and relative potencies have not been defined. Here, we compared mice singly, doubly, or triply mutant for these three myelin inhibitor proteins. The myelin extracted from Nogo-A mutant mice is less inhibitory for axons than is that from wild-type mice, but myelin lacking MAG and OMgp is indistinguishable from control. However, myelin lacking all three inhibitors is less inhibitory than Nogo-A-deficient myelin, uncovering a redundant and synergistic role for all three proteins in axonal growth inhibition. Spinal cord injury studies revealed an identical in vivo hierarchy of these three myelin proteins. Loss of Nogo-A allows corticospinal and raphespinal axon growth above and below the injury, as well as greater behavioral recovery than in wild-type or heterozygous mutant mice. In contrast, deletion of MAG and OMgp stimulates neither axonal growth nor enhanced locomotion. The triple-mutant mice exhibit greater axonal growth and improved locomotion, consistent with a principal role for Nogo-A and synergistic actions for MAG and OMgp, presumably through shared receptors. These data support the hypothesis that targeting all three myelin ligands, as with NgR1 decoy receptor, provides the optimal chance for overcoming myelin inhibition and improving neurological function.
Myelin associated inhibitors: a link between injury-induced and experience-dependent plasticity.
Akbik Feras,Cafferty William B J,Strittmatter Stephen M
In the adult, both neurologic recovery and anatomical growth after a CNS injury are limited. Two classes of growth inhibitors, myelin associated inhibitors (MAIs) and extracellular matrix associated inhibitors, limit both functional recovery and anatomical rearrangements in animal models of spinal cord injury. Here we focus on how MAIs limit a wide spectrum of growth that includes regeneration, sprouting, and plasticity in both the intact and lesioned CNS. Three classic myelin associated inhibitors, Nogo-A, MAG, and OMgp, signal through their common receptors, Nogo-66 Receptor-1 (NgR1) and Paired-Immunoglobulin-like-Receptor-B (PirB), to regulate cytoskeletal dynamics and inhibit growth. Initially described as inhibitors of axonal regeneration, subsequent work has demonstrated that MAIs also limit activity and experience-dependent plasticity in the intact, adult CNS. MAIs therefore represent a point of convergence for plasticity that limits anatomical rearrangements regardless of the inciting stimulus, blurring the distinction between injury studies and more "basic" plasticity studies.
Maintaining stable memory engrams: new roles for Nogo-A in the CNS.
Zagrebelsky M,Korte M
Nogo-A interaction with its different receptors (Nogo receptor 1 (NgR1), S1P receptor 2 (S1PR2), paired immunoglobulin-like receptor B (PirB)) restricts plasticity and growth-dependent processes leading, via the activation of different signaling pathway to the stabilization of the neuronal networks (either developmentally or during processes of memory consolation in the mature nervous system). Taking away these molecular brakes might allow for the induction of extensive structural and functional rearrangements and might promote compensatory growth processes after an injury of the CNS, in cortical structures as well as in the spinal cord. However, it is important to keep in mind that this could as well be a dangerous endeavor, since it might facilitate unwanted and unnecessary (and probably even maladaptive) neuronal connections.
Ameliorative Effects of p75NTR-ED-Fc on Axonal Regeneration and Functional Recovery in Spinal Cord-Injured Rats.
Wang Yong-Tang,Lu Xiu-Min,Zhu Feng,Huang Peng,Yu Ying,Long Zai-Yun,Wu Ya-Min
As a co-receptor of Nogo-66 receptor (NgR) and a critical receptor for paired immunoglobulin-like receptor (PirB), p75 neurotrophin receptor (p75NTR) mediates the inhibitory effects of myelin-associated inhibitors on axonal regeneration after spinal cord injury. Therefore, the p75NTR antagonist, such as recombinant p75NTR protein or its homogenates may block the inhibitory effects of myelin and promote the axonal regeneration and functional recovery. The purposes of this study are to subclone and express the extracellular domain gene of human p75NTR with IgG-Fc (hp75NTR-ED-Fc) in prokaryotic expression system and investigate the effects of the recombinant protein on axonal regeneration and functional recovery in spinal cord-injured rats. The hp75NTR-ED-Fc coding sequence was amplified from pcDNA-hp75NTR-ED-Fc by polymerase chain reaction (PCR) and subcloned into vector pET32a (+), then the effects of the purified recombinant protein on neurite outgrowth of dorsal root ganglion (DRG) neurons cultured with myelin-associated glycoprotein (MAG) were determined, and the effects of the fusion protein on axonal regeneration, functional recovery, and its possible mechanisms in spinal cord-injured rats were further investigated. The results indicated that the purified infusion protein could promote neurite outgrowth of DRG neurons, promote axonal regeneration and functional recovery, and decrease RhoA activation in spinal cord-injured rats. Taken together, the findings revealed that p75NTR still may be a potential and novel target for therapeutic intervention for spinal cord injury and that the hp75NTR-ED-Fc fusion protein treatment enhances functional recovery by limiting tissue loss and stimulating axonal growth in spinal cord-injured rats, which may result from decreasing the activation of RhoA.
Emerging functions of myelin-associated proteins during development, neuronal plasticity, and neurodegeneration.
Llorens Franc,Gil Vanessa,del Río José Antonio
FASEB journal : official publication of the Federation of American Societies for Experimental Biology
Adult mammalian central nervous system (CNS) axons have a limited regrowth capacity following injury. Myelin-associated inhibitors (MAIs) limit axonal outgrowth, and their blockage improves the regeneration of damaged fiber tracts. Three of these proteins, Nogo-A, MAG, and OMgp, share two common neuronal receptors: NgR1, together with its coreceptors [p75(NTR), TROY, and Lingo-1]; and the recently described paired immunoglobulin-like receptor B (PirB). These proteins impair neuronal regeneration by limiting axonal sprouting. Some of the elements involved in the myelin inhibitory pathways may still be unknown, but the discovery that blocking both PirB and NgR1 activities leads to near-complete release from myelin inhibition, sheds light on one of the most competitive and intense fields of neuroregeneration study in recent decades. In parallel with the identification and characterization of the roles and functions of these inhibitory molecules in axonal regeneration, data gathered in the field strongly suggest that most of these proteins have roles other than axonal growth inhibition. The discovery of a new group of interacting partners for myelin-associated receptors and ligands, as well as functional studies within or outside the CNS environment, highlights the potential new physiological roles for these proteins in processes, such as development, neuronal homeostasis, plasticity, and neurodegeneration.
Genomic structure of mouse PIR-A6, an activating member of the paired immunoglobulin-like receptor gene family.
Tun T,Kubagawa Y,Dennis G,Burrows P D,Cooper M D,Kubagawa H
The gene for one of the activating members of the paired Ig-like receptor family, Pira6, was isolated from a genomic library and sequenced. The first of 9 exons in the approximately 8.2 kb Pira6 gene encodes the 5' untranslated region, the translation initiation site, and approximately half of the signal sequence. The second exon encodes the rest of the signal sequence, exons 3-8 each encode a single Ig-like extracellular domain, and exon 9 encodes the transmembrane region, cytoplasmic tail and 3' UTR with four polyadenylation signals and six mRNA instability sequences. A soluble form of PIR-A6 may be generated by alternative splicing. The exonic sequences account for approximately 42% of the Pira6 gene and approximately 34% for the single inhibitory Pirb gene, thus defining Pira and Pirb as genes with relatively short intronic sequences. Extensive sequence homology was found between Pira6 and Pirb from approximately 2 kb upstream of the ATG initiation site to the beginning of intron 8. The Pir genes appear to be distributed in three regions of the proximal end of chromosome 7 based on the present data and an analysis of currently available mouse genomic sequence databases. One region contains a single Pir gene which is almost identical to Pira6, and the other two contain multiple Pir genes in opposite transcriptional orientations. Potential binding sites for hemopoiesis-specific and ubiquitous transcription factors were identified upstream of the Pira6 transcription start sites that reside within the initiator consensus sequence motif. These results provide important clues to the coordinate regulation observed for PIR-A and PIR-B expression during hematopoiesis.
Soluble LILRA3 promotes neurite outgrowth and synapses formation through a high-affinity interaction with Nogo 66.
An Hongyan,Brettle Merryn,Lee Terry,Heng Benjamin,Lim Chai K,Guillemin Gilles J,Lord Megan S,Klotzsch Enrico,Geczy Carolyn L,Bryant Katherine,Fath Thomas,Tedla Nicodemus
Journal of cell science
Inhibitory proteins, particularly Nogo 66, a highly conserved 66-amino-acid loop of Nogo A (an isoform of RTN4), play key roles in limiting the intrinsic capacity of the central nervous system (CNS) to regenerate after injury. Ligation of surface Nogo receptors (NgRs) and/or leukocyte immunoglobulin-like receptor B2 (LILRB2) and its mouse orthologue the paired immunoglobulin-like receptor B (PIRB) by Nogo 66 transduces inhibitory signals that potently inhibit neurite outgrowth. Here, we show that soluble leukocyte immunoglobulin-like receptor A3 (LILRA3) is a high-affinity receptor for Nogo 66, suggesting that LILRA3 might be a competitive antagonist to these cell surface inhibitory receptors. Consistent with this, LILRA3 significantly reversed Nogo-66-mediated inhibition of neurite outgrowth and promoted synapse formation in primary cortical neurons through regulation of the ERK/MEK pathway. LILRA3 represents a new antagonist to Nogo-66-mediated inhibition of neurite outgrowth in the CNS, a function distinct from its immune-regulatory role in leukocytes. This report is also the first to demonstrate that a member of LILR family normally not expressed in rodents exerts functions on mouse neurons through the highly homologous Nogo 66 ligand.
LILRB receptor-mediated regulation of myeloid cell maturation and function.
van der Touw William,Chen Hui-Ming,Pan Ping-Ying,Chen Shu-Hsia
Cancer immunology, immunotherapy : CII
The leukocyte immunoglobulin-like receptor (LILR) family comprises a set of paired immunomodulatory receptors expressed among human myeloid and lymphocyte cell populations. While six members of LILR subfamily A (LILRA) associate with membrane adaptors to signal via immunoreceptor tyrosine-based activating motifs (ITAM), LILR subfamily B (LILRB) members signal via multiple cytoplasmic immunoreceptor tyrosine-based inhibitory motifs (ITIM). Ligand specificity of some LILR family members has been studied in detail, but new perspective into the immunoregulatory aspects of this receptor family in human myeloid cells has been limited. LILRB receptors and the murine ortholog, paired immunoglobulin-like receptor B (PIRB), have been shown to negatively regulate maturation pathways in myeloid cells including mast cells, neutrophils, dendritic cells, as well as B cells. Our laboratory further demonstrated in mouse models that PIRB regulated functional development of myeloid-derived suppressor cell and the formation of a tumor-permissive microenvironment. Based on observations from the literature and our own studies, our laboratory is focusing on how LILRs modulate immune homeostasis of human myeloid cells and how these pathways may be targeted in disease states. Integrity of this pathway in tumor microenvironments, for example, permits a myeloid phenotype that suppresses antitumor adaptive immunity. This review presents the evidence supporting a role of LILRs as myeloid cell regulators and ongoing efforts to understand the functional immunology surrounding this family.
Nogo-A/Pir-B/TrkB Signaling Pathway Activation Inhibits Neuronal Survival and Axonal Regeneration After Experimental Intracerebral Hemorrhage in Rats.
Liu Yinlong,Ma Chao,Li Haiying,Shen Haitao,Li Xiang,Fu Xi'an,Wu Jiang,Chen Gang
Journal of molecular neuroscience : MN
Intracerebral hemorrhage (ICH) leads to widespread pathological lesions in the brain, especially impacting neuronal survival and axonal regeneration. This study aimed to elucidate whether the Nogo-A (a myelin-related protein)/paired immunoglobulin-like receptor B (Pir-B)/tropomyosin receptor kinase B (TrkB) pathway could exert a regulatory effect in ICH. An ICH model was first established in Sprague Dawley rats, followed by different administrations of vehicle, k252a, or NSC 87877. The Morris water maze test was performed to observe ICH-induced cognitive dysfunction in rats. Rats in the ICH + NSC 87877 group showed better cognitive performance compared with those injected with vehicle or k252a. Neurobehavioral scores were identical. By harvesting brain tissues at different time points after ICH, we detected the expression levels of Nogo-A and PirB with western blot and immunofluorescence and found that they were markedly upregulated at 48 h after ICH. TUNEL and Fluoro-Jade B staining showed that NSC 87877 treatment attenuated ICH-induced apoptosis and neuronal death, whereas k252a treatment aggravated these pathological changes. The expression levels of growth-associated protein 43 (GAP43) and neurofilament 200 (NF200) were higher in the ICH + NSC 87877 group compared with the ICH + vehicle group, but were lower in the ICH + k252a group. Finally, we confirmed the protective role of p-TrkB/TrkB in ICH by western blot. To sum up, our study identified the inhibitory role of the Nogo-A/PirB/TrkB pathway in ICH; however, p-TrkB/TrkB may serve as a potential target for secondary brain injury post-ICH.
Establishment of axon regeneration regulatory network and the role of low intensity pulsed ultrasound in the network.
Liu Chunyang,Xu Yanhua,Yang Hong,Zhang Jianhua
Saudi journal of biological sciences
Objective:To establish an axon regeneration regulatory network for optimal selection, and explore the role of low intensity pulsed ultrasound in the network. Methods:The axon regeneration regulatory network involving axon regeneration-related proteins NGF, BDNF and PirB was constructed by using GO and KEGG. The maximum possible pathway acting on axon regeneration was screened by Bayesian network theory. The node of low - intensity pulsed ultrasound in NGF - involved axon regeneration network was complemented by combining literature methods. Results:The NGF, BDNF and PirB-involved axonal regeneration regulatory pathway was successfully constructed. The low intensity pulsed ultrasound played a role in axon regeneration by acting on ERK1/2-CREB pathway and GSK-3β. NGF-TrKA-Rap1-ERK1/2-CREB-Bcl-2 was optimized as optimal pathway by Bayesian theory. Conclusion:The regulatory pathway of axon regeneration involving nerve growth related factors and low intensity pulsed ultrasound was initially established, which provided a theoretical basis for further study of axon regeneration, and also new ideas for action of low intensity pulsed ultrasound on axon regeneration regulatory pathway.
Genetic deletion of paired immunoglobulin-like receptor B does not promote axonal plasticity or functional recovery after traumatic brain injury.
Omoto Shusaku,Ueno Masaki,Mochio Soichiro,Takai Toshiyuki,Yamashita Toshihide
The Journal of neuroscience : the official journal of the Society for Neuroscience
The rewiring of neural networks is a fundamental step in recovering behavioral functions after brain injury. However, there is limited potential for axonal plasticity in the adult CNS. The myelin-associated proteins Nogo, myelin-associated glycoprotein (MAG), and oligodendrocyte myelin glycoprotein (OMgp) are known to inhibit axonal plasticity, and thus targeting the inhibitory pathways they participate in is a potential means of promoting plasticity and functional recovery. Each of Nogo, MAG, and OMgp interacts with both the Nogo receptor (NgR) and paired immunoglobulin-like receptor B (PirB). Here, we determined whether blocking PirB activity enhances axonal reorganization and functional recovery after cortical injury. We found that axons of the contralesional corticospinal tract sprouted into the denervated side of the cervical spinal cord after unilateral injury of the motor cortex. The extent to which this axonal reorganization occurred was far greater in mice lesioned during early postnatal days than in mice lesioned at an age when myelin had begun to form. This suggests that myelin-associated proteins might limit axonal remodeling in vivo. However, the number of sprouting fibers within either the corticospinal or corticorubral tract was not enhanced in PirB(-/-) mice. Blocking PirB signaling also failed to enhance functional recovery with three motor tests. Our results suggest that blocking the function of PirB is not sufficient to promote axonal reorganization or functional recovery after cortical injury.
Altered expression of myelin-associated inhibitors and their receptors after traumatic brain injury in the mouse.
Israelsson Charlotte,Flygt Johanna,Åstrand Elaine,Kiwanuka Olivia,Bengtsson Henrik,Marklund Niklas
Restorative neurology and neuroscience
PURPOSE:When central nervous system axons are injured, regeneration is partly inhibited by myelin-associated inhibitors (MAIs). Following traumatic brain injury (TBI) in the rat, pharmacological neutralisation of the MAIs Nogo-A and myelin-associated glycoprotein (MAG) resulted in improved functional outcome. In contrast, genetic or pharmacological neutralization of the MAI receptors Nogo-66 receptor 1 (NgR1) or paired-immunoglobulin like receptor-B (PirB) showed an unaltered or impaired outcome following TBI in mice. The aim of the present study was thus to evaluate the MAI expression levels following TBI in mice. METHODS:Quantitative reverse transcriptase PCR (qRT-PCR) was used to measure total RNA isolated from brains of young adult male C57BL/6 mice at one, three or seven days following controlled cortical impact TBI or sham injury. Hippocampal and neocortical tissue ipsi- and contralateral to the injury was analyzed for Nogo-A, oligodendrocyte-myelin glycoprotein (OMgp), MAG, and the MAI receptors PirB and NgR1, including its co-receptor Lingo1. RESULTS:Compared to sham-injured controls, PirB neocortical expression was significantly upregulated at one day and NgR1 expression downregulated at seven days post-TBI. In the hippocampus, transcriptional upregulation was observed in Nogo-A (one day post-injury), MAG and PirB at seven days post-injury. In contrast, the hippocampal transcripts of NgR1 and Lingo1 were decreased at seven days post-injury. The expression of OMgp was unaltered at all time points post-injury. CONCLUSION:These results suggest that early dynamic changes in MAI gene expression occur following TBI in the mouse, particularly in the hippocampus, which may play an inhibitory role for post-injury regeneration and plasticity.
Oligodendrocyte-myelin glycoprotein and Nogo negatively regulate activity-dependent synaptic plasticity.
Raiker Stephen J,Lee Hakjoo,Baldwin Katherine T,Duan Yuntao,Shrager Peter,Giger Roman J
The Journal of neuroscience : the official journal of the Society for Neuroscience
In the adult mammalian CNS, the growth inhibitors oligodendrocyte-myelin glycoprotein (OMgp) and the reticulon RTN4 (Nogo) are broadly expressed in oligodendrocytes and neurons. Nogo and OMgp complex with the neuronal cell surface receptors Nogo receptor-1 (NgR1) and paired Ig-like receptor-B (PirB) to regulate neuronal morphology. In the healthy CNS, NgR1 regulates dendritic spine shape and attenuates activity-driven synaptic plasticity at Schaffer collateral-CA1 synapses. Here, we examine whether Nogo and OMgp influence functional synaptic plasticity, the efficacy by which synaptic transmission occurs. In acute hippocampal slices of adult mice, Nogo-66 and OMgp suppress NMDA receptor-dependent long-term potentiation (LTP) when locally applied to Schaffer collateral-CA1 synapses. Neither Nogo-66 nor OMgp influences basal synaptic transmission or paired-pulse facilitation, a form of short-term synaptic plasticity. PirB(-/-) and NgR1(-/-) single mutants and NgR1(-/-);PirB(-/-) double mutants show normal LTP, indistinguishable from wild-type controls. In juvenile mice, LTD in NgR1(-/-), but not PirB(-/-), slices is absent. Mechanistic studies revealed that Nogo-66 and OMgp suppress LTP in an NgR1-dependent manner. OMgp inhibits LTP in part through PirB but independently of p75. This suggests that NgR1 and PirB participate in ligand-dependent inhibition of synaptic plasticity. Loss of NgR1 leads to increased phosphorylation of extracellular signal-regulated kinase 1/2 (ERK1/2), signaling intermediates known to regulate neuronal growth and synaptic function. In primary cortical neurons, BDNF elicited phosphorylation of AKT and p70S6 kinase is attenuated in the presence of myelin inhibitors. Collectively, we provide evidence that mechanisms of neuronal growth inhibition and inhibition of synaptic strength are related. Thus, myelin inhibitors and their receptors may coordinate structural and functional neuronal plasticity in CNS health and disease.
Axon regeneration impediment: the role of paired immunoglobulin-like receptor B.
Liu Jing,Wang Yan,Fu Wei
Neural regeneration research
Regenerative capacity is weak after central nervous system injury because of the absence of an enhancing microenvironment and presence of an inhibitory microenvironment for neuronal and axonal repair. In addition to the Nogo receptor (NgR), the paired immunoglobulin-like receptor B (PirB) is a recently discovered coreceptor of Nogo, myelin-associated glycoprotein, and myelin oligodendrocyte glycoprotein. Concurrent blocking of NgR and PirB almost completely eliminates the inhibitory effect of myelin-associated inhibitory molecules on axonal regeneration. PirB participates in a key pathological process of the nervous system, specifically axonal regeneration inhibition. PirB is an inhibitory receptor similar to NgR, but their effects are not identical. This study summarizes the structure, distribution, relationship with common nervous system diseases, and known mechanisms of PirB, and concludes that PirB is also distributed in cells of the immune and hematopoietic systems. Further investigations are needed to determine if immunomodulation and blood cell migration involve inhibition of axonal regeneration.
TAT-PEP Enhanced Neurobehavioral Functional Recovery by Facilitating Axonal Regeneration and Corticospinal Tract Projection After Stroke.
Deng Bin,Li Liya,Gou Xingchun,Xu Hao,Zhao Zhaohua,Wang Qiang,Xu Lixian
Paired immunoglobulin-like receptor B (PirB) has been identified as a new receptor for myelin-associated inhibitory (MAI) proteins, which may play important role in axonal regeneration and corticospinal tract (CST) projection associated with neurobehavioral function recovery after stroke. Here, we found that the expression of PirB was increased in the cortical penumbra from 1 to 28 days after transient focal cerebral ischemic reperfusion of rats. Then, transactivator of transcription-PirB extracellular peptide (TAT-PEP) was generated that might block the interactions between MAIs and PirB. The results showed that TAT-PEP displayed high affinity for MAIs and ameliorated their inhibitory effect on neurite growth. Furthermore, TAT-PEP can widely distribute in the penumbra after intraperitoneal injection. Then, we found that TAT-PEP enhanced neurite growth and alleviated growth cone collapse after oxygen glucose deprivation (OGD) injury. In addition, TAT-PEP promoted long-term neurobehavioral functional recovery through enhancing axonal regeneration and CST projection. Finally, the observations demonstrated that POSH/RhoA/growth-associated protein 43 (GAP43) as PirB-associated downstream signaling molecules played important role in neurobehavioral functional recovery after stroke. Moreover, the underlying mechanism associated with TAT-PEP-mediated promoting axonal regeneration and CST projection was by intervening in the expression of POSH, RhoA, and GAP43. These studies suggest that TAT-PEP may represent an attractive therapeutic strategy against stroke.
Activation of LILRB2 signal pathway in temporal lobe epilepsy patients and in a pilocarpine induced epilepsy model.
Yue Jiong,Li Wei,Liang Chao,Chen Bing,Chen Xin,Wang Lukang,Zang Zhenle,Yu Sixun,Liu Shiyong,Li Song,Yang Hui
Temporal lobe epilepsy (TLE) is a frequent form of focal intractable epilepsy in adults, but the specific mechanism underlying the epileptogenesis of TLE is still unknown. Human leukocyte immunoglobulin-like receptor B2 (LILRB2) (the murine homolog gene called paired immunoglobulin-like receptor B, or PirB), participates in the process of synaptic plasticity and neurite growth in the central nervous system (CNS), suggesting a potential role of LILRB2 in epilepsy. However, the expression pattern of LILRB2 and the downstream molecular signal in intractable TLE remains poorly understood. In the present study, western blotting and immunohistochemistry results showed that LILRB2 expression was upregulated in the temporal neocortex of patients with TLE. Moreover, protein levels of LILRB2 negatively correlated with the frequency of seizures in TLE patients. In the pilocarpine-induced C57BL/6 mouse model, PirB upregulation in the hippocampus began 12h after status epilepticus (SE), reached a peak at 7days and then maintained a significantly high level until day 60. Similarly, we found a remarkable increase in PirB expression at 1day, 7days and30days post-SE in the temporal cortex. Double-labeled immunofluorescence showed that LILRB2/PirB were highly expressed in neurons and astrocytes but not microglia. In addition, protein levels of POSH, SHROOM3, ROCK1 and ROCK2, the important downstream factors of the LILRB2 pathway, were significantly increased in the epileptic foci of TLE patients and located on the NeuN-positive neurons and GFAP-positive astrocytes. Taken together, our results indicate that LILRB2/PirB may be involved in the process of TLE.
Spatio-temporal expression of paired immunoglobulin-like receptor-B in the adult mouse brain after focal cerebral ischaemia.
Gou Xingchun,Zhang Qiaomei,Xu Ning,Deng Bin,Wang Huiwen,Xu Lixian,Wang Qiang
PRIMARY OBJECTIVE:Paired immunoglobulin-like receptor-B (PirB) is another receptor, except for the Nogo receptor, that is involved in inhibition of axons regeneration after central nervous system injury. However, the expression of PirB in focal cerebral ischaemic brain remains unclear. Herein, this study investigated spatial-temporal expression of PirB in the mouse brain following transient focal cerebral ischaemia. METHODS AND PROCEDURE:Adult male C57BL/6 mice underwent a 60-minute transient occlusion of middle cerebral artery. Mice were killed and brain samples were harvested at 30 minutes, 2 hours, 24 hours, 3 days and 7 days after reperfusion. Expression of PirB in the brain was determined by reverse transcriptase-polymerase chain reaction (RT-PCR), western blot analysis and immunohistochemical staining. MAIN OUTCOMES AND RESULTS:The results showed that PirB was mainly expressed in ischaemic penumbra. PirB mRNA and protein expression began to increase at 2 hours, peaked at 24 hours and lasted for 7 days after reperfusion in the ischaemic penumbra. By using immunofluorescence, PirB signals were co-localized with NeuN-positive neurons. CONCLUSION:PirB expression is up-regulated in ischaemic penumbra following transient focal cerebral ischaemia. PirB expression in neurons may play important pathological roles in the inhibition of axonal regeneration after stroke, suggesting that the inhibition of PirB expression may enhance axonal regeneration and functional recovery after stroke.
[Neuroregeneration of newborn rats with hypoxic-ischemic brain damage following antibody-mediated neutralization of paired-immunoglobulin-like receptor B].
Wang Hua,Mu De-Zhi
Zhongguo dang dai er ke za zhi = Chinese journal of contemporary pediatrics
OBJECTIVE:To study changes in paired-immunoglobulin-like receptor B (PirB) expression after hypoxic-ischemic brain damage (HIBD) as well as the role for targeted inhibition of PirB activity in nerve regeneration in rats. METHODS:Newborn Sprague-Dawleyrats rats were divided into: a sham operation group (n=30), a HIBD group (n=30), and an anti PirB antibody treatment group (n=6). In the HIBD group, HIBD was induced by right carotid artery ligature and subsequent exposure to hypoxia (8% O2) for 3 hours. In the sham operation group, right carotid artery was dissected as in the HIBD group but no ligature and hypoxic exposure was not applied. In the two groups, 6 animals were sacrificed at 0, 6, 12, 24 and 72 hours after the operation and hypoxic exposure. In the antibody treatment group, after carotid artery ligation and hypoxia exposure as in the HIBD group, an anti PirB antibody was injected intracerebrally and animals were sacrificed 72 hours after the injection. Immediately after sacrifice of the animals at designated time points, brain tissue specimens were collected. The presence and content of PirB protein were assessed by immunohistochemistry and Western blot analysis respectively, the abundance of PirB mRNA was determined by RT-PCR, and the Rho kinase (Rock) activity was determined by immunoprecipitation. RESULTS:At 72 hours after operation, PirB mRNA abundance and protein content in the brain were significantly increased as compared with the measurements at 0 hour after operation in the HIBD group (P<0.05); ROCK activity was significantly increased in the HIBD group as compared with the sham operation and anti PirB antibody groups (P<0.05). CONCLUSIONS:PirB might be involved in HIBD through a Rho-ROCK-dependent mechanism and antibody-mediated neutralization of PirB in the brain may offer a novel therapeutic strategy for HIBD.
Distribution of paired immunoglobulin-like receptor B in the nervous system related to regeneration difficulties after unilateral lumbar spinal cord injury.
Peng Wan-Shu,Qi Chao,Zhang Hong,Gao Mei-Ling,Wang Hong,Ren Fei,Li Xia-Qing
Neural regeneration research
Paired immunoglobulin-like receptor B (PirB) is a functional receptor of myelin-associated inhibitors for axonal regeneration and synaptic plasticity in the central nervous system, and thus suppresses nerve regeneration. The regulatory effect of PirB on injured nerves has received a lot of attention. To better understand nerve regeneration inability after spinal cord injury, this study aimed to investigate the distribution of PirB (via immunofluorescence) in the central nervous system and peripheral nervous system 10 days after injury. Immunoreactivity for PirB increased in the dorsal root ganglia, sciatic nerves, and spinal cord segments. In the dorsal root ganglia and sciatic nerves, PirB was mainly distributed along neuronal and axonal membranes. PirB was found to exhibit a diffuse, intricate distribution in the dorsal and ventral regions. Immunoreactivity for PirB was enhanced in some cortical neurons located in the bilateral precentral gyri. Overall, the findings suggest a pattern of PirB immunoreactivity in the nervous system after unilateral spinal transection injury, and also indicate that PirB may suppress repair after injury.
Nucleic Acid Vaccine Targeting Nogo-66 Receptor and Paired Immunoglobulin-Like Receptor B as an Immunotherapy Strategy for Spinal Cord Injury in Rats.
Lu Xiu-Min,Mao Min,Xiao Lan,Yu Ying,He Mei,Zhao Guo-Yan,Tang Jun-Jie,Feng Shuang,Li Sen,He Cheng-Ming,Wang Yong-Tang
Neurotherapeutics : the journal of the American Society for Experimental NeuroTherapeutics
Nogo-66 receptor (NgR) and paired immunoglobulin-like receptor B (PirB) are two common receptors of various myelin-associated inhibitors (MAIs) and, thus, play an important role in MAIs-induced inhibitory signalling of regeneration following spinal cord injury (SCI). Based on the concept of protective autoimmunity, vaccine approaches could induce the production of antibodies against inhibitors in myelin, such as using purified myelin, spinal cord homogenates, or MAIs receptor NgR, in order to block the inhibitory effects and promote functional recovery in SCI models. However, due to the complication of the molecules and the mechanisms involved in MAIs-mediated inhibitory signalling, these immunotherapy strategies have yielded inconsistent outcomes. Therefore, we hypothesized that the choice and modification of self-antigens, and co-regulating multiple targets, may be more effective in repairing the injured spinal cord and improving functional recovery. In this study, NgR and PirB were selected to construct a double-targeted granulocyte-macrophage colony stimulating factor-NgR-PirB (GMCSF-NgR-PirB) nucleic acid vaccine, and investigate the efficacy of this immunotherapy in a spinal cord injury model in rats. The results showed that this vaccination could stimulate the production of antibodies against NgR and PirB, block the inhibitory effects mediated by various MAIs, and promote nerve regeneration and functional recovery after spinal cord injury. These findings suggest that nucleic acid vaccination against NgR and PirB can be a promising therapeutic strategy for SCI and other central nervous system diseases and injuries.
CAMKs support development of acute myeloid leukemia.
Kang Xunlei,Cui Changhao,Wang Chen,Wu Guojin,Chen Heyu,Lu Zhigang,Chen Xiaoli,Wang Li,Huang Jie,Geng Huimin,Zhao Meng,Chen Zhengshan,Müschen Markus,Wang Huan-You,Zhang Cheng Cheng
Journal of hematology & oncology
BACKGROUND:We recently identified the human leukocyte immunoglobulin-like receptor B2 (LILRB2) and its mouse ortholog-paired Ig-like receptor (PirB) as receptors for several angiopoietin-like proteins (Angptls). We also demonstrated that PirB is important for the development of acute myeloid leukemia (AML), but exactly how an inhibitory receptor such as PirB can support cancer development is intriguing. RESULTS:Here, we showed that the activation of Ca (2+)/calmodulin-dependent protein kinases (CAMKs) is coupled with PirB signaling in AML cells. High expression of CAMKs is associated with a poor overall survival probability in patients with AML. Knockdown of CAMKI or CAMKIV decreased human acute leukemia development in vitro and in vivo. Mouse AML cells that are defective in PirB signaling had decreased activation of CAMKs, and the forced expression of CAMK partially rescued the PirB-defective phenotype in the MLL-AF9 AML mouse model. The inhibition of CAMK kinase activity or deletion of CAMKIV significantly slowed AML development and decreased the AML stem cell activity. We also found that CAMKIV acts through the phosphorylation of one of its well-known target (CREB) in AML cells. CONCLUSION:CAMKs are essential for the growth of human and mouse AML. The inhibition of CAMK signaling may become an effective strategy for treating leukemia.
Paired Immunoglobulin-like Receptor B Inhibition in Müller Cells Promotes Neurite Regeneration After Retinal Ganglion Cell Injury in vitro.
Yuan Rongdi,Yang Mei,Fan Wei,Lan Jian,Zhou Yuan-Guo
In the central nervous system (CNS), three types of myelin-associated inhibitors (MAIs) have major inhibitory effects on nerve regeneration. They include Nogo-A, myelin-associated glycoprotein, and oligodendrocyte-myelin glycoprotein. MAIs possess two co-receptors, Nogo receptor (NgR) and paired immunoglobulin-like receptor B (PirB). Previous studies have confirmed that the inhibition of NgR only results in a modest increase in regeneration in the CNS; however, the inhibitory effects of PirB with regard to nerve regeneration after binding to MAIs remain controversial. In this study, we demonstrated that PirB is expressed in primary cultures of retinal ganglion cells (RGCs), and the inhibitory effects of the three MAIs on the growth of RGC neurites are not significantly decreased after direct PirB knockdown using adenovirus PirB shRNA. Interestingly, we found that retinal Müller cells expressed PirB and that its knockdown enhanced the regeneration of co-cultured RGC neurites. PirB knockdown also activated the JAK/Stat3 signaling pathway in Müller cells and upregulated ciliary neurotrophic factor levels. These findings indicate that PirB plays a novel role in retinal Müller cells and that its action in these cells may indirectly affect the growth of RGC neurites. The results also reveal that PirB in Müller cells affects RGC neurite regeneration. Our findings provide a novel basis for the use of PirB as a target molecule to promote nerve regeneration.
PirB is a functional receptor for myelin inhibitors of axonal regeneration.
Atwal Jasvinder K,Pinkston-Gosse Julie,Syken Josh,Stawicki Scott,Wu Yan,Shatz Carla,Tessier-Lavigne Marc
Science (New York, N.Y.)
A major barrier to regenerating axons after injury in the mammalian central nervous system is an unfavorable milieu. Three proteins found in myelin--Nogo, MAG, and OMgp--inhibit axon regeneration in vitro and bind to the glycosylphosphatidylinositol-anchored Nogo receptor (NgR). However, genetic deletion of NgR has only a modest disinhibitory effect, suggesting that other binding receptors for these molecules probably exist. With the use of expression cloning, we have found that paired immunoglobulin-like receptor B (PirB), which has been implicated in nervous system plasticity, is a high-affinity receptor for Nogo, MAG, and OMgp. Interfering with PirB activity, either with antibodies or genetically, partially rescues neurite inhibition by Nogo66, MAG, OMgp, and myelin in cultured neurons. Blocking both PirB and NgR activities leads to near-complete release from myelin inhibition. Our results implicate PirB in mediating regeneration block, identify PirB as a potential target for axon regeneration therapies, and provide an explanation for the similar enhancements of visual system plasticity in PirB and NgR knockout mice.
NogoR1 and PirB signaling stimulates neural stem cell survival and proliferation.
Ramasamy Srinivas,Yu Fenggang,Hong Yu Yuan,Srivats Hariharan,Dawe Gavin Stewart,Ahmed Sohail
Stem cells (Dayton, Ohio)
Neural stem cells (NSCs) and neural progenitors (NPs) in the mammalian neocortex give rise to the main cell types of the nervous system. The biological behavior of these NSCs and NPs is regulated by extracellular niche derived autocrine-paracrine signaling factors on a developmental timeline. Our previous reports [Plos One 2010;5:e15341; J Neurochem 2011;117:565-578] have shown that chondroitin sulfate proteoglycan and ApolipoproteinE are autocrine-paracrine survival factors for NSCs. NogoA, a myelin related protein, is expressed in the cortical ventricular zones where NSCs reside. However, the functional role of Nogo signaling proteins in NSC behavior is not completely understood. In this study, we show that NogoA receptors, NogoR1 and PirB, are expressed in the ventricular zone where NSCs reside between E10.5 and 14.5 but not at E15.5. Nogo ligands stimulate NSC survival and proliferation in a dosage-dependent manner in vitro. NogoR1 and PirB are low and high affinity Nogo receptors, respectively and are responsible for the effects of Nogo ligands on NSC behavior. Inhibition of autocrine-paracrine Nogo signaling blocks NSC survival and proliferation. In NSCs, NogoR1 functions through Rho whereas PirB uses Shp1/2 signaling pathways to control NSC behavior. Taken together, this work suggests that Nogo signaling is an important pathway for survival of NSCs.
Neuroprotection from stroke in the absence of MHCI or PirB.
Adelson Jaimie D,Barreto George E,Xu Lijun,Kim Taeho,Brott Barbara K,Ouyang Yi-Bing,Naserke Thorsten,Djurisic Maja,Xiong Xiaoxing,Shatz Carla J,Giffard Rona G
Recovery from stroke engages mechanisms of neural plasticity. Here we examine a role for MHC class I (MHCI) H2-Kb and H2-Db, as well as PirB receptor. These molecules restrict synaptic plasticity and motor learning in the healthy brain. Stroke elevates neuronal expression not only of H2-Kb and H2-Db, but also of PirB and downstream signaling. KbDb knockout (KO) or PirB KO mice have smaller infarcts and enhanced motor recovery. KO hippocampal organotypic slices, which lack an intact peripheral immune response, have less cell death after in vitro ischemia. In PirB KO mice, corticospinal projections from the motor cortex are enhanced, and the reactive astrocytic response is dampened after MCAO. Thus, molecules that function in the immune system act not only to limit synaptic plasticity in healthy neurons, but also to exacerbate brain injury after ischemia. These results suggest therapies for stroke by targeting MHCI and PirB.
Human LilrB2 is a β-amyloid receptor and its murine homolog PirB regulates synaptic plasticity in an Alzheimer's model.
Kim Taeho,Vidal George S,Djurisic Maja,William Christopher M,Birnbaum Michael E,Garcia K Christopher,Hyman Bradley T,Shatz Carla J
Science (New York, N.Y.)
Soluble β-amyloid (Aβ) oligomers impair synaptic plasticity and cause synaptic loss associated with Alzheimer's disease (AD). We report that murine PirB (paired immunoglobulin-like receptor B) and its human ortholog LilrB2 (leukocyte immunoglobulin-like receptor B2), present in human brain, are receptors for Aβ oligomers, with nanomolar affinity. The first two extracellular immunoglobulin (Ig) domains of PirB and LilrB2 mediate this interaction, leading to enhanced cofilin signaling, also seen in human AD brains. In mice, the deleterious effect of Aβ oligomers on hippocampal long-term potentiation required PirB, and in a transgenic model of AD, PirB not only contributed to memory deficits present in adult mice, but also mediated loss of synaptic plasticity in juvenile visual cortex. These findings imply that LilrB2 contributes to human AD neuropathology and suggest therapeutic uses of blocking LilrB2 function.
PirB is a novel potential therapeutic target for enhancing axonal regeneration and synaptic plasticity following CNS injury in mammals.
Gou Zhaoyu,Mi Yajing,Jiang Fengliang,Deng Bin,Yang Jun,Gou Xingchun
Journal of drug targeting
A major barrier to axonal regeneration in mammals is the unfavorable extracellular environment that develops following injury to the central nervous system (CNS). In particular, three myelin-associated inhibitory proteins (MAIs) - Nogo, myelin-associated glycoprotein (MAG) and oligodendrocyte myelin glycoprotein (OMgp) - are known to inhibit axonal regeneration and functional recovery. These MAIs share a common receptor, glycosylphosphatidylinositol-anchored Nogo receptor (NgR). However, paired immunoglobulin-like receptor B (PirB) - which was originally identified as a receptor for class I major histocompatibility complex (MHCI) in the immune system - is also expressed in neurones and plays a similarly inhibitory role in axonal regeneration and synaptic plasticity following CNS injury through its association with MAIs. Importantly, suppression of PirB activity through antibody antagonism or genetic means can partially relieve the inhibition of neurite outgrowth in vitro and in vivo. In this review, we present the molecular features, expression patterns and known signaling pathways of PirB, and we specifically focus on putative roles for PirB in the CNS and its potential as a target of molecular therapies for enhancing axonal regeneration and synaptic plasticity following CNS injury.
Expression of PirB protein in intact and injured optic nerve and retina of mice.
Cai Xiaofeng,Yuan Rongdi,Hu Zheng,Chen Chunlin,Yu Jun,Zheng Zheng,Ye Jian
The aim of this study was to investigate the expression of PirB protein in intact mice ON (optic nerve) and retina, and to evaluate its change after ON injury. The mouse ON crush model was established. The immunohistochemistry and western blot were used to detect PirB expression. We discovered PirB signals were located as beaded arrangement along the ON long axis in intact ON, disordered in injured ON, and distributed mainly in ganglion cell layer in intact and injured retina. Both PirB expression in injured ON and retina were significantly increased at 1-day post injury (1-dpi), nearly peaked at 7-dpi, but thereafter there was no significant change of them till at least 28-dpi. We concluded the expression of PirB was positive in intact ON and retina, and significantly increased after ON injury. These findings, coupled with previous studies, may imply that PirB is probably a critical molecule in inhibition of axonal regeneration by myelin inhibitors after ON injury.
PirB regulates a structural substrate for cortical plasticity.
Djurisic Maja,Vidal George S,Mann Miriam,Aharon Adam,Kim Taeho,Ferrao Santos Alexandre,Zuo Yi,Hübener Mark,Shatz Carla J
Proceedings of the National Academy of Sciences of the United States of America
Experience-driven circuit changes underlie learning and memory. Monocular deprivation (MD) engages synaptic mechanisms of ocular dominance (OD) plasticity and generates robust increases in dendritic spine density on L5 pyramidal neurons. Here we show that the paired immunoglobulin-like receptor B (PirB) negatively regulates spine density, as well as the threshold for adult OD plasticity. In PirB(-/-) mice, spine density and stability are significantly greater than WT, associated with higher-frequency miniature synaptic currents, larger long-term potentiation, and deficient long-term depression. Although MD generates the expected increase in spine density in WT, in PirB(-/-) this increase is occluded. In adult PirB(-/-), OD plasticity is larger and more rapid than in WT, consistent with the maintenance of elevated spine density. Thus, PirB normally regulates spine and excitatory synapse density and consequently the threshold for new learning throughout life.
MHC Class I Molecules and PirB Shape Neuronal Morphology by Affecting the Dendritic Arborization of Cortical Neurons.
Shen Yuqing,Zhao Huanhuan,Li Ping,Peng Yaqin,Cui Pengfei,Miao Fengqin,Zhang Ying,Zhang Aifeng,Zhang Jianqiong
Neuronal MHC class I proteins have been previously reported to regulate synaptic plasticity. Several reports indicate MHC class I proteins are expressed early during development of the nervous system, suggesting they may also play a role in neuronal development. Using cultured cortical neurons, we show MHC class I proteins aggregate at specific sites in neuronal cell bodies, which overlap with the actin cytoskeleton. Knockout of MHC class I in cultured neurons increases total dendritic length and the number of branch points. These effects are abolished by reintroducing MHC class I expression. Similarly, blocking of MHC class I proteins or PirB by an MHCI antibody or a soluble PirB ectodomain respectively, mimics the knock out phenotype of increased dendritic branching. This effect is correlated with decreased phosphorylation of both LIMK and cofilin, suggesting it may be mediated by an induction of cofilin activity. Finally, layer II and III cortical neurons in the sensorimotor region of an MHC class I deficiency mouse model show increased dendritic growth and branching. Altogether, our results suggest MHC class I plays a role in inhibiting or limiting the degree of dendrite arborization during the development of cortical neurons.
PirB restricts neuronal regeneration in developing rat brain following hypoxia-ischemia.
Wang Hua,Xiong Ying,Mu Dezhi
Molecular medicine reports
The inhibitors of axonal regeneration in the myelin sheath are considered to be major contributors to the lack of regeneration in the central nervous system (CNS) following hypoxic-ischemic (HI) brain damage. As well as the Nogo receptor (NgR), the paired-immunoglobulin-like receptor B (PirB) is a functional receptor for the myelin inhibitors of axonal regeneration. The inhibition of PirB and NgR activities may block most of the inhibitory effects of myelin inhibitors on nerve regeneration. We observed the PirB protein and mRNA expression in HI-damaged rat cortical neurons using immunohistochemistry and reverse transcription-polymerase chain reaction assays. In addition, we treated the HI-damaged rat cortical neurons using PirB antibodies to observe the regeneration of injured neurons. Moreover, the Rock II activity in HI-damaged rat cortical neurons treated with PirB antibodies was observed using western blot analysis. The mRNA and protein levels of PirB increased in newborn rat cortical neurons following HI damage. Treatment with PirB antibodies is able to improve axonal regeneration following HI damage compared with normal axonal growth. Rock II activity also increased in the HI-damaged rat brain. The inhibition of PirB is therefore a potential therapeutic method to promote the regeneration of HI-damaged axons and the inhibitory signal may be transduced through the Rho-ROCK signaling pathway.
The Nogo-B-PirB axis controls macrophage-mediated vascular remodeling.
Kondo Yuka,Jadlowiec Caroline C,Muto Akihito,Yi Tai,Protack Clinton,Collins Michael J,Tellides George,Sessa William C,Dardik Alan
OBJECTIVE:Nogo-B mediates vascular protection and facilitates monocyte- and macrophage-dependent vascular remodeling. PirB is an alternate receptor for Nogo-B, but a role for the Nogo-PirB axis within the vascular system has not been previously reported. We examined whether Nogo-B or PirB play a role in regulating macrophage-mediated vascular remodeling and hypothesized that endothelial Nogo-B regulates vein graft macrophage infiltration via its alternate receptor PirB. METHODS:Vein grafts were performed using Nogo and PirB wild type and knockout mice. Human vein grafts were similarly analyzed. The hindlimb ischemia model was performed in PirB wild type and knockout mice. Accompanying in vitro work included isolation of macrophages from PirB wild type and knockout mice. RESULTS:Increased Nogo-B and PirB mRNA transcripts and protein expression were observed within mouse and human vein grafts. Both Nogo knockout and PirB knockout vein grafts showed increased wall thickness and increased numbers of F4/80-positive macrophages. Macrophages derived from PirB knockout mice had increased adhesion to fibronectin, increased EC-specific binding, and increased numbers of mRNA transcripts of M2 markers as well as MMP3 and MMP9. PirB knockout vein grafts had increased active MMP9 compared to wild type vein grafts. PirB knockout mice had increased recovery from hindlimb ischemia and increased macrophage infiltration compared to wild type mice. CONCLUSIONS:Vein graft adaptation shows increased expression of both Nogo-B and PirB. Loss of PirB, or its endothelial ligand Nogo-B, results in increased inflammatory cell infiltration and vein graft wall thickening. These findings suggest that PirB regulates macrophage activity in vein grafts and that Nogo-B in the vein graft limits macrophage infiltration and vein graft thickening. PirB may play a more general role in regulating macrophage responses to vascular injury. Macrophage inhibition via Nogo-PirB interactions may be an important mechanism regulating vein graft adaptation to the arterial circulation.
TAT-PEP, a novel blocker of PirB, enhances the recovery of cognitive function in mice after transient global cerebral ischemia.
Li Liya,Deng Bin,Li Shuang,Liu Zhaoyu,Jiang Tao,Xiao Zhaoyang,Wang Qiang
Behavioural brain research
Neuronal damage and axonal regeneration inhibition are the main reasons to poor functional recovery after ischemia. Nogo-A signals inhibit axon outgrowth through the PirB receptor after ischemic reperfusion injury in central nervous system. We use TAT-PEP, a novel protein which could pass through the blood brain barrier, to block the function of PirB and identify the long-term neurological and behavioral recovery after bilateral common carotid artery occlusion (BCCAO) in mice. We observed that TAT-PEP promoted neuron survival and inhibited neuronal apoptosis. TAT-PEP increased the expression of Tau, GAP43 and MAP-2 proteins. In addition, the short-term and long-term cognitive functions were also enhanced, indicating that TAT-PEP had a long-term neuroprotective effect, which reduced neurologic injury and neuron loss, promoted neurite outgrowth and enhanced functional recovery after ischemia. These studies reveal the mechanism of PirB on stroke and offer a potential therapeutic method for cerebral ischemia in humans.
Blocking PirB up-regulates spines and functional synapses to unlock visual cortical plasticity and facilitate recovery from amblyopia.
Bochner David N,Sapp Richard W,Adelson Jaimie D,Zhang Siyu,Lee Hanmi,Djurisic Maja,Syken Josh,Dan Yang,Shatz Carla J
Science translational medicine
During critical periods of development, the brain easily changes in response to environmental stimuli, but this neural plasticity declines by adulthood. By acutely disrupting paired immunoglobulin-like receptor B (PirB) function at specific ages, we show that PirB actively represses neural plasticity throughout life. We disrupted PirB function either by genetically introducing a conditional PirB allele into mice or by minipump infusion of a soluble PirB ectodomain (sPirB) into mouse visual cortex. We found that neural plasticity, as measured by depriving mice of vision in one eye and testing ocular dominance, was enhanced by this treatment both during the critical period and when PirB function was disrupted in adulthood. Acute blockade of PirB triggered the formation of new functional synapses, as indicated by increases in miniature excitatory postsynaptic current (mEPSC) frequency and spine density on dendrites of layer 5 pyramidal neurons. In addition, recovery from amblyopia--the decline in visual acuity and spine density resulting from long-term monocular deprivation--was possible after a 1-week infusion of sPirB after the deprivation period. Thus, neural plasticity in adult visual cortex is actively repressed and can be enhanced by blocking PirB function.
PirB regulates asymmetries in hippocampal circuitry.
Ukai Hikari,Kawahara Aiko,Hirayama Keiko,Case Matthew Julian,Aino Shotaro,Miyabe Masahiro,Wakita Ken,Oogi Ryohei,Kasayuki Michiyo,Kawashima Shihomi,Sugimoto Shunichi,Chikamatsu Kanako,Nitta Noritaka,Koga Tsuneyuki,Shigemoto Ryuichi,Takai Toshiyuki,Ito Isao
Left-right asymmetry is a fundamental feature of higher-order brain structure; however, the molecular basis of brain asymmetry remains unclear. We recently identified structural and functional asymmetries in mouse hippocampal circuitry that result from the asymmetrical distribution of two distinct populations of pyramidal cell synapses that differ in the density of the NMDA receptor subunit GluRε2 (also known as NR2B, GRIN2B or GluN2B). By examining the synaptic distribution of ε2 subunits, we previously found that β2-microglobulin-deficient mice, which lack cell surface expression of the vast majority of major histocompatibility complex class I (MHCI) proteins, do not exhibit circuit asymmetry. In the present study, we conducted electrophysiological and anatomical analyses on the hippocampal circuitry of mice with a knockout of the paired immunoglobulin-like receptor B (PirB), an MHCI receptor. As in β2-microglobulin-deficient mice, the PirB-deficient hippocampus lacked circuit asymmetries. This finding that MHCI loss-of-function mice and PirB knockout mice have identical phenotypes suggests that MHCI signals that produce hippocampal asymmetries are transduced through PirB. Our results provide evidence for a critical role of the MHCI/PirB signaling system in the generation of asymmetries in hippocampal circuitry.
Activity-dependent modulation of hippocampal synaptic plasticity via PirB and endocannabinoids.
Djurisic Maja,Brott Barbara K,Saw Nay L,Shamloo Mehrdad,Shatz Carla J
The threshold for Hebbian synaptic plasticity in the CNS is modulated by prior synaptic activity. At adult CA3-CA1 synapses, endocannabinoids play a role in this process, but how activity engages and maintains this retrograde signaling system is not well understood. Here we show that conditional deletion of Paired Immunoglobulin-like receptor B (PirB) from pyramidal neurons in adult mouse hippocampus results in deficient LTD at CA3-CA1 synapses over a range of stimulation frequencies, accompanied by an increase in LTP. This finding can be fully explained by the disengagement of retrograde endocannabinoid signaling selectively at excitatory synapses. In the absence of PirB, the NMDAR-dependent regulation of endocannabinoid signaling is lost, while CB1R-dependent and group I mGluR-dependent regulation are intact. Moreover, mEPSC frequency in mutant CA1 pyramidal cells is elevated, consistent with a higher density of excitatory synapses and altered synapse pruning. Mice lacking PirB also perform better than WT in learning and memory tasks. These observations suggest that PirB is an integral part of an NMDA receptor-mediated synaptic mechanism that maintains bidirectional Hebbian plasticity and learning via activity-dependent endocannabinoid signaling.
PirB inhibits axonal outgrowth via the PI3K/Akt/mTOR signaling pathway.
Bi Yong-Yan,Quan Yong
Molecular medicine reports
Accumulating data strongly suggests that leukocyte immunoglobulin like receptor B1 (PirB) inhibits axonal outgrowth. However, the underlying mechanisms remain unclear. In the present study, cortical neurons of newborn mice were cultured with Nogo‑66 (Nogo‑p4; 4 µmol/l; a PirB ligand) together with NEP1‑40 (Nogo inhibitory peptide) and/or anti‑PirB body (50 mg/ml). PirB mRNA and protein was higher in cultured neurons induced by Nogo‑66 compared with untreated cells. Neurite outgrowth assays demonstrated that the inhibitory effects of Nogo‑66 on axonal outgrowth were reversed by anti‑PirB body. Reverse transcription‑quantitative polymerase chain reaction and western blot assays demonstrated that anti‑PirB treatment led to reduced mRNA and protein expression of phosphoinositide 3‑kinase (PI3K), Akt serine/threonine kinase (Akt), mechanistic target of rapamycin kinase (mTOR), myosin IIA and cofilin, which are involved in axonal outgrowth. Furthermore, blockade of the PI3K/Akt/mTOR pathway using a PI3K inhibitor or an mTOR inhibitor diminished the stimulatory effect of anti‑PirB on axonal outgrowth, and the reduced effect of anti‑PirB on factors that were activation by anti‑PirB. In addition, blockade of PI3K/Akt/mTOR enhanced anti‑PirB‑induced gene and protein expression. These results revealed that PirB functions as a potential suppressor in axonal outgrowth via repressing PI3K/Akt/mTOR signaling pathway, and PirB/PI3K/Akt/mTOR may be a novel target for enhancing axonal outgrowth for developing rational therapeutic strategies.
MHC-I and PirB Upregulation in the Central and Peripheral Nervous System following Sciatic Nerve Injury.
Bombeiro André Luis,Thomé Rodolfo,Oliveira Nunes Sérgio Luiz,Monteiro Moreira Bárbara,Verinaud Liana,Oliveira Alexandre Leite Rodrigues de
Major histocompatibility complex class one (MHC-I) antigen-presenting molecules participate in central nervous system (CNS) synaptic plasticity, as does the paired immunoglobulin-like receptor B (PirB), an MHC-I ligand that can inhibit immune-cells and bind to myelin axon growth inhibitors. Based on the dual roles of both molecules in the immune and nervous systems, we evaluated their expression in the central and peripheral nervous system (PNS) following sciatic nerve injury in mice. Increased PirB and MHC-I protein and gene expression is present in the spinal cord one week after nerve transection, PirB being mostly expressed in the neuropile region. In the crushed nerve, MHC-I protein levels increased 2 weeks after lesion (wal) and progressively decreased over the next eight weeks. The same kinetics were observed for infiltrating cytotoxic T lymphocytes (CTLs) but not for PirB expression, which continuously increased. Both MHC-I and PirB were found in macrophages and Schwann cells but rarely in axons. Interestingly, at 8 wal, PirB was mainly restricted to the myelin sheath. Our findings reinforce the participation of MHC-I and PirB in CNS plasticity events. In contrast, opposing expression levels of these molecules were found in the PNS, so that MHC-I and PirB seem to be mostly implicated in antigen presentation to CTLs and axon myelination, respectively.
Electroacupuncture enhances rehabilitation through miR-181b targeting PirB after ischemic stroke.
Deng Bin,Bai Fuhai,Zhou Heng,Zhou Dandan,Ma Zhi,Xiong Lize,Wang Qiang
Recent studies have demonstrated microRNAs (miRNAs) and proteins are beneficial to axon regeneration, which may be involved in Electroacupuncture (EA) therapy against stroke. In this study, we aimed to determine the pivotal role of PirB in EA-produced rehabilitation against ischemic stroke; and to screen and investigate the potential miRNAs directly regulating PirB expression. The results showed EA treatment enhanced axon regeneration and new projections from the corticospinal tract at 28 d after cerebral ischemic reperfusion injury of rats. Then, we found EA decreased pirb mRNA and PirB protein expression in the penumbra within 28 days after reperfusion. The reduction of PirB expression facilitated neurite outgrowth after oxygen-glucose deprivation injury. The miRNA microarray showed the level of twenty kinds of miRNAs changed in the penumbra after EA administration. The bioinformatics study and luciferase assay verified miR-181b directly regulated pirb mRNA expression. EA increased miR-181b levels in the penumbras, and improved neurobehavioral function rehabilitation through miR-181b direct targeting of pirb mRNA to regulate the expression of PirB, RhoA and GAP43. In conclusion, we provide the first evidence that EA enhances rehabilitation against stroke by regulating epigenetic changes to directly act on its targets, such as the miR-181b/PirB/RhoA/GAP43 axis, which is a novel mechanism of EA therapy.
Cell-Autonomous Regulation of Dendritic Spine Density by PirB.
Vidal George S,Djurisic Maja,Brown Kiana,Sapp Richard W,Shatz Carla J
Synapse density on cortical pyramidal neurons is modulated by experience. This process is highest during developmental critical periods, when mechanisms of synaptic plasticity are fully engaged. In mouse visual cortex, the critical period for ocular dominance (OD) plasticity coincides with the developmental pruning of synapses. At this time, mice lacking paired Ig-like receptor B (PirB) have excess numbers of dendritic spines on L5 neurons; these spines persist and are thought to underlie the juvenile-like OD plasticity observed in adulthood. Here we examine whether PirB is required specifically in excitatory neurons to exert its effect on dendritic spine and synapse density during the critical period. In mice with a conditional allele of PirB (PirB), PirB was deleted only from L2/3 cortical pyramidal neurons by timed electroporation of Cre recombinase. Sparse mosaic expression of Cre produced neurons lacking PirB in a sea of wild-type neurons and glia. These neurons had significantly elevated dendritic spine density, as well as increased frequency of miniature EPSCs, suggesting that they receive a greater number of synaptic inputs relative to Cre neighbors. The effect of cell-specific PirB deletion on dendritic spine density was not accompanied by changes in dendritic branching complexity or axonal bouton density. Together, results imply a neuron-specific, cell-autonomous action of PirB on synaptic density in L2/3 pyramidal cells of visual cortex. Moreover, they are consistent with the idea that PirB functions normally to corepress spine density and synaptic plasticity, thereby maintaining headroom for cells to encode ongoing experience-dependent structural change throughout life.
Structure and flexibility of the extracellular region of the PirB receptor.
Vlieg Hedwich C,Huizinga Eric G,Janssen Bert J C
The Journal of biological chemistry
Murine paired immunoglobulin receptor B (PirB) and its human ortholog leukocyte immunoglobulin-like receptor B2 (LILRB2) are widely expressed inhibitory receptors that interact with a diverse set of extracellular ligands and exert functions ranging from down-regulation of immune responses to inhibition of neuronal growth. However, structural information that could shed light on how PirB interacts with its ligands is lacking. Here, we report crystal structures of the PirB ectodomain; the first full ectodomain structure for a LILR family member, at 3.3-4.5 Å resolution. The structures reveal that PirB's six Ig-like domains are arranged at acute angles, similar to the structures of leukocyte immunoglobulin-like receptor (LILR) and killer-cell immunoglobulin-like receptor (KIR). We observe that this regular arrangement is followed throughout the ectodomain, resulting in an extended zigzag conformation. In two out of the five structures reported here, the repeating zigzag is broken by the first domain that can adopt two alternative orientations. Quantitative binding experiments revealed a 9 μm dissociation constant for PirB-myelin-associated glycoprotein (MAG) ectodomain interactions. Taken together, these structural findings and the observed PirB-MAG interactions are compatible with a model for intercellular signaling in which the PirB extracellular domains, which point away from the cell surface, enable interaction with ligands in .
PirB Overexpression Exacerbates Neuronal Apoptosis by Inhibiting TrkB and mTOR Phosphorylation After Oxygen and Glucose Deprivation Injury.
Zhao Zhao-Hua,Deng Bin,Xu Hao,Zhang Jun-Feng,Mi Ya-Jing,Meng Xiang-Zhong,Gou Xing-Chun,Xu Li-Xian
Cellular and molecular neurobiology
Previous studies have proven that paired immunoglobulin-like receptor B (PirB) plays a crucial suppressant role in neurite outgrowth and neuronal plasticity after central nervous system injury. However, the role of PirB in neuronal survival after cerebral ischemic injury and its mechanisms remains unclear. In the present study, the role of PirB is investigated in the survival and apoptosis of cerebral cortical neurons in cultured primary after oxygen and glucose deprivation (OGD)-induced injury. The results have shown that rebarbative PirB exacerbates early neuron apoptosis and survival. PirB gene silencing remarkably decreases early apoptosis and promotes neuronal survival after OGD. The expression of bcl-2 markedly increased and the expression of bax significantly decreased in PirB RNAi-treated neurons, as compared with the control- and control RNAi-treated ones. Further, phosphorylated TrkB and mTOR levels are significantly downregulated in the damaged neurons. However, the PirB silencing markedly upregulates phosphorylated TrkB and mTOR levels in the neurons after the OGD. Taken together, the overexpression of PirB inhibits the neuronal survival through increased neuron apoptosis. Importantly, the inhibition of the phosphorylation of TrkB and mTOR may be one of its mechanisms.
Inhibition of PirB Activity by TAT-PEP Improves Mouse Motor Ability and Cognitive Behavior.
Mi Ya-Jing,Chen Hai,Guo Na,Sun Meng-Yi,Zhao Zhao-Hua,Gao Xing-Chun,Wang Xiao-Long,Zhang Rui-San,Zhou Jiang-Bing,Gou Xing-Chun
Frontiers in aging neuroscience
Paired immunoglobulin-like receptor B (PirB), a functional receptor for myelin-associated inhibitory proteins, plays an important role in axon regeneration in injured brains. However, its role in normal brain function with age has not been previously investigated. Therefore in this study, we examined the expression level of PirB in the cerebral cortex, hippocampus and cerebellum of mice at 1 month, 3 months and 18 months of age. The results showed that the expression of PirB increased with age. We further demonstrated that overexpression of PirB inhibited neurite outgrowth in PC12 cells, and this inhibitory activity of PirB could be reversed by TAT-PEP, which is a recombinant soluble PirB ectodomain fused with TAT domain for blood-brain barrier penetration. study, intraperitoneal administration of TAT-PEP was capable of enhancing motor capacity and spatial learning and memory in mice, which appeared to be mediated through regulation of brain-derived neurotrophic factor (BDNF) secretion. Our study suggests that PirB is associated with aging and TAT-PEP may be a promising therapeutic agent for modulation of age-related motor and cognitive dysfunctions.