The Effects of Adiponectin and Adiponectin Receptor 1 Levels on Macrovascular Complications Among Patients with Type 2 Diabetes Mellitus.
Su Na,Zhao Nairui,Wang Guangya,Wang Linxia,Zhang Yunna,Li Ruijie,Liu Ying,Yang Xinxin,Li Cuiliu,Hou Mingming
Cellular physiology and biochemistry : international journal of experimental cellular physiology, biochemistry, and pharmacology
BACKGROUND/AIMS:The present study aimed to investigate the serum levels of adiponectin (APN) and adiponectin receptor 1 (AdipoR1) in patients with type 2 diabetes mellitus (T2DM) combined with macrovascular complications (MVC), as well as their correlation with clinical parameters. METHODS:A total of 60 T2DM patients were divided into 2 groups according to the presence of MVC: T2DM + MVC group (n=30) and T2DM group (n=30). Additionally, 30 healthy people were selected as control group (NC group). Clinical data and biological parameters were detected and recorded. T test was performed to compare the differences between two groups, and the results were corrected using Bonferroni method. Meanwhile, the correlation analysis and multiple stepwise regression analysis were used to analyze the association of APN and AdipoR1 with clinical factors. RESULTS:The levels of APN and AdipoR1 were significantly decreased in T2DM group and T2DM + MVC group compared with NC group, with the lowest value in T2DM + MVC group (all P<0.01). Serum APN levels were positively correlated with FINS and TG (r = 0.412, 0.316, respectively; both P<0.05), and negatively correlated with SBP, DBP and LDL-C (r = -0.292, -0.383, -0.334, respectively; all P<0.05). Serum levels of AdipoR1 were positively correlated with APN (r = 0.726, P<0.01), and negatively correlated with BMI, SBP, DBP, FBG, TC and LDL-C (r = -0.440, -0.446, -0.374, -0.444, -0.344, -0.709, respectively; all P<0.01). CONCLUSION:Serum levels of APN and AdipoR1 are significantly lower in T2DM group and T2DM + MVC group, showing lowest value in T2DM + MVC group. APN and AdipoR1 levels may influence glucose and lipid metabolism in T2DM patients.
High molecular weight adiponectin activates AMPK and suppresses cytokine-induced NF-kappaB activation in vascular endothelial cells.
Hattori Yoshiyuki,Nakano Yasuko,Hattori Sachiko,Tomizawa Atsuko,Inukai Kouichi,Kasai Kiuo
Various isoforms of adiponectin circulate in the plasma. We purified high molecular weight (HMW) adiponectin from human plasma. HMW adiponectin was observed to activate AMP-activated protein kinase (AMPK), thereby increasing the phosphorylation of eNOS and NO production in endothelial cells. On the other hand, cells preincubated with HMW adiponectin had reduced TNFalpha-induced NF-kappaB activation. HMW adiponectin by itself was found to modestly activate NF-kappaB, which was significantly enhanced by inhibition of AMPK/eNOS activation. Thus, HMW adiponectin might have dual action, both pro and anti-inflammatory. An initial period of NF-kappaB activation by HMW adiponectin might be proinflammatory, but it could be counteracted by activation of AMPK/eNOS, which lead to a potential reduction in a second activation of NF-kappaB against inflammatory stimuli.
Adiponectin protects endothelial cells from the damages induced by the intermittent high level of glucose.
Xiao Xinhua,Dong Yuanyuan,Zhong Jing,Cao Renxian,Zhao Xiang,Wen Gebo,Liu Jianghua
Globular adiponectin (gAd) has anti-atherogenic effects on the vascular wall. Intermittent hyperglycemia induces endothelial cells (ECs) injury but the physiological factors that may protect against ECs damage are largely unknown. In the present study, we investigated the effect of gAd on ECs dysfunction induced by intermittent high glucose. The gAd significantly attenuated intermittent high glucose-induced apoptosis and oxidative stress in human umbilical vein endothelial cells. This was achieved by decreasing caspase-3 and 3-nitrotyrosine protein expression, increasing nitric oxide (NO) secretion and phosphorylation of Akt, AMPK, and endothelial nitric oxide synthase protein expression. Pretreatment with a phosphatidylinositol 3' kinase (PI3K) inhibitor, LY294002, partly reversed adiponectin's anti-apoptotic effect. Taken together, our results indicate that gAd acts as a critical physiological factor which protects against fluctuating high glucose-induced endothelial damage. It may act via attenuating apoptosis and increasing synthesis of NO through both the PI3K/AKT and AMPK signaling pathway to reduce oxidative stress and cell apoptosis.
Adiponectin protein exists in aortic endothelial cells.
Komura Noriyuki,Maeda Norikazu,Mori Takuya,Kihara Shinji,Nakatsuji Hideaki,Hirata Ayumu,Tochino Yoshihiro,Funahashi Tohru,Shimomura Iichiro
AIMS:Inflammation is closely associated with the development of atherosclerosis and metabolic syndrome. Adiponectin, an adipose-derived secretory protein, possesses an anti-atherosclerotic property. The present study was undertaken to elucidate the presence and significance of adiponectin in vasculature. METHODS AND RESULTS:Immunofluorescence staining was performed in aorta of wild-type (WT) mice and demonstrated that adiponectin was co-stained with CD31. Thoracic aorta was cut through and then aortic intima was carefully shaved from aorta. Western blotting showed the existence of adiponectin protein in aortic intima, while there was no adiponectin mRNA expression. Adiponectin knockout (Adipo-KO) and WT mice were administered with a low-dose and short-term lipopolysaccharide (LPS) (1 mg/kg of LPS for 4 hours). The endothelium vascular adhesion molecule-1 (VCAM-1) and intercellular adhesion molecule-1 (ICAM-1) were highly increased in Adipo-KO mice compared to WT mice after LPS administration. CONCLUSIONS:Adiponectin protein exists in aortic endothelium under steady state and may protect vasculature from the initiation of atherosclerosis.
CTRP9 induces mitochondrial biogenesis and protects high glucose-induced endothelial oxidative damage via AdipoR1 -SIRT1- PGC-1α activation.
Cheng Liang,Li Bin,Chen Xu,Su Jie,Wang Hongbing,Yu Shiqiang,Zheng Qijun
Biochemical and biophysical research communications
Vascular lesions caused by endothelial dysfunction are the most common and serious complication of diabetes. The vasoactive potency of CTRP9 has been reported in our previous study via nitric oxide (NO) production. However, the effect of CTRP9 on vascular endothelial cells remains unknown. This study aimed to investigate the protection role of CTRP9 in the primary aortic vascular endothelial cells and HAECs under high-glucose condition. We found that the aortic vascular endothelial cells isolated from mice fed with a high fat diet generated more ROS production than normal cells, along with decreased mitochondrial biogenesis, which was also found in HAECs treated with high glucose. However, the treatment of CTPR9 significantly reduced ROS production and increased the activities of endogenous antioxidant enzymes, the expression of PGC-1α, NRF1, TFAM, ATP5A1 and SIRT1, and the activity of cytochrome c oxidase, indicating an induction of mitochondrial biogenesis. Furthermore, silencing the expression of SIRT1 in HAECs impeded the effect of CTRP9 on mitochondrial biogenesis, while silencing the expression of AdipoR1 in HAECs reversed the expression of SIRT1 and PGC-1α. Based on these findings, this study showed that CTRP9 might induce mitochondrial biogenesis and protect high glucose-induced endothelial oxidative damage via AdipoR1-SIRT1-PGC-1α signaling pathway.
Adiponectin inhibits vascular endothelial growth factor-induced migration of human coronary artery endothelial cells.
Mahadev Kalyankar,Wu Xiangdong,Donnelly Sylvia,Ouedraogo Raogo,Eckhart Andrea D,Goldstein Barry J
AIMS:Vascular endothelial growth factor (VEGF)-induced endothelial cell migration and angiogenesis are associated with the vascular complications of diabetes mellitus, and adiponectin is an abundant plasma adipokine that exhibits salutary effects on endothelial function. We investigated whether adiponectin suppresses VEGF-induced migration and related signal transduction responses in human coronary artery endothelial cells (HCAECs). METHODS AND RESULTS:Using a modified Boyden chamber technique and a monolayer 'wound-healing' assay, both the recombinant adiponectin globular domain and full-length adiponectin protein potently suppressed the migration of HCAEC induced by VEGF. Adiponectin did not increase endothelial cell apoptosis, as measured by terminal deoxynucleotidyl transferase biotin-dUTP Nick End Labelling assay. Adiponectin also suppressed VEGF-induced reactive oxygen species generation, activation of Akt, the mitogen-activated protein kinase ERK and the RhoGTPase RhoA, and induction of the formation of actin stress fibres and focal cellular adhesions. VEGF-stimulated cell migration was inhibited by activation of adenylyl cyclase with forskolin, and adiponectin treatment increased cellular cyclic adenosine monophosphate (cAMP) levels and protein kinase A (PKA) enzymatic activity. Pharmacological inhibition of either adenylyl cyclase or PKA significantly abrogated the effect of adiponectin globular domain to suppress VEGF-induced cell migration. CONCLUSION:Adiponectin suppresses VEGF-stimulated HCAEC migration via cAMP/PKA-dependent signalling, an important effect with implications for a regulatory role of adiponectin in vascular processes associated with diabetes and atherosclerosis.
Overexpression of adiponectin receptors potentiates the antiinflammatory action of subeffective dose of globular adiponectin in vascular endothelial cells.
Zhang Peng,Wang Ying,Fan Yanbo,Tang Zhihui,Wang Nanping
Arteriosclerosis, thrombosis, and vascular biology
OBJECTIVE:A decreased plasma level of adiponectin is associated with obesity and metabolic syndrome and correlated with endothelial dysfunction. This study aimed to investigate the regulated expression of the newly identified adiponectin receptors (AdipoR1 and 2) and their roles in the endothelial expression of intercellular adhesion molecule-1 (ICAM-1) in response to tumor necrosis factor (TNF)-alpha. METHODS AND RESULTS:Immunohistochemical study and quantitative RT-PCR demonstrated that globular adiponectin suppressed the TNF-alpha-induced ICAM-1 expression in a dose-dependent manner in mouse aorta and human umbilical vein endothelial cells (HUVECs). Adenovirus-mediated overexpression of AdipoR1 and 2 in ECs significantly enhanced the suppressive effect of a subeffective dose of adiponectin on TNF-alpha-induced ICAM-1 expression and NF-kappaB activation. Promoter reporter assays and small interfering RNA revealed that peroxisome proliferator-activated receptor-alpha may function as an important pathway downstream of adiponectin and its receptors. Furthermore, overexpression of AdipoRs in rat carotid arteries markedly decreased the induction of ICAM-1 in vivo. CONCLUSIONS:We provide novel evidence that upregulation of AdipoRs in ECs potentiates the antiinflammatory effect of adiponectin; modulating adiponectin receptors may have potential therapeutic applications for cardiovascular complications associated with metabolic syndrome and diabetes.
Adiponectin ameliorates angiotensin II-induced vascular endothelial damage.
Zhi Zuo,Pengfei Zuo,Xiaoyi Tian,Genshan Ma
Cell stress & chaperones
Adiponectin is an adipocyte-specific adipocytokine that possesses anti-atherogenic and anti-diabetic properties. It has been shown to have a beneficial effect on the cardiovascular system, but it remains to be elucidated whether adiponectin has a therapeutic effect on vascular damage induced by the potential vasoactive substance angiotensin II (Ang II). In this study, the effects of adiponectin on Ang II-induced vascular endothelial damage were investigated. In cultured human umbilical vein endothelium cells, Ang II stimulation increased generation of ROS and 4-hydroxy-2-nonenal, both of which were clearly restored by administration of adiponectin. In addition, administration of adiponectin was found to increase cell viability and prevent apoptosis. Our results also demonstrate that the protective effects of adiponectin against Ang II-induced vascular endothelial damage are dependent on the binding of adiponectin to its cell surface receptor 1. Importantly, we found that adiponectin treatment modulates the apoptotic pathway by reducing the expression of LOX-1, up-regulating both cIAP-1 and the ratio of Bcl-2/Bax. Finally, our data displayed that the protective effects of adiponectin against Ang II cytotoxicity depend on AMPK activation mediated by the endosomal adaptor protein, adaptor protein with phosphotyrosine binding, pleckstrin homology domains, and leucine zipper motif.
Adiponectin limits monocytic microparticle-induced endothelial activation by modulation of the AMPK, Akt and NFκB signaling pathways.
Ehsan Mehroz,Singh Krishna K,Lovren Fina,Pan Yi,Quan Adrian,Mantella Laura-Eve,Sandhu Paul,Teoh Hwee,Al-Omran Mohammed,Verma Subodh
OBJECTIVE:Monocyte-derived microparticles (mono-MPs) are emerging as critical transducers of inflammatory signals, and have been suggested to link cardiovascular risk factors to vascular injury. Since adiponectin has been proposed to exert multiple anti-inflammatory and vasculoprotective effects, we hypothesized that it might serve to limit the production and/or action of mono-MPs. METHODS:Flow cytometry and western blot studies were conducted on THP-1 cells, THP-1-derived MPs, human umbilical vein endothelial cells (HUVECs), peripheral blood CD14+ monocytes and mice to evaluate the effects of adiponectin on mono-MPs. RESULTS:Adiponectin attenuated lipopolysaccharide (LPS)-evoked MP release from THP-1 monocytes (30% difference) and peripheral blood monocytes (both P < 0.05) as well as dampened LPS-induced mono-MP generation in vivo. Furthermore, peritoneal monocytes from Adipoq(-/-) mice generated significantly greater MPs than those from Adipoq(+/+) littermates in the absence (2.3 fold difference, P < 0.05) and presence (1.6 fold difference, P < 0.05) of LPS. LPS-induced MP expression of NLRP3 inflammasome and its key components, namely cleaved ASC, caspase-1 and IL-1β (pro- and cleaved), were markedly attenuated by adiponectin. HUVECs incubated with MPs from LPS-treated THP-1 cells exhibited increased VCAM-1 levels and adhesion to THP-1 cells. Adiponectin abrogated these effects. From a mechanistic standpoint, the effects of adiponectin on MP release and molecular signaling occurred at least in part through the AMPK, Akt and NFκB pathways. CONCLUSION:Adiponectin exerts novel effects to limit the production and action of mono-MPs, underscoring yet another pleiotropic effect of this adipokine.
A novel mechanism of diabetic vascular endothelial dysfunction: Hypoadiponectinemia-induced NLRP3 inflammasome activation.
Zhang Jinglong,Xia Linying,Zhang Fen,Zhu Di,Xin Chao,Wang Helin,Zhang Fuyang,Guo Xian,Lee Yan,Zhang Ling,Wang Shan,Guo Xiong,Huang Chong,Gao Feng,Liu Yi,Tao Ling
Biochimica et biophysica acta. Molecular basis of disease
It has been well documented that hypoadiponectinemia is associated with impaired endothelium-dependent vasodilation. However, the exact molecular mechanism which mediates this process has not been fully described. The current study aimed to investigate the role of hypoadiponectinemia-induced NLRP3 inflammasome activation in diabetic vascular endothelial dysfunction and its molecular mechanism. Male adult adiponectin knockout mice and wild type mice were fed with a high fat diet to establish a type 2 diabetic mellitus model. In addition, human umbilical vein endothelial cells (HUVECs) were cultured and subjected to high glucose/high fat (HG/HF). The NLRP3 inflammasome activation was increased in type 2 diabetic mice and treatment of diabetic aortic segments with MCC950, a potent selective inhibitor of NLRP3 inflammasome ex vivo improved endothelial-dependent vasorelaxation. NLRP3 inflammasome activation and vascular endothelial injury were significantly increased in APN-KO mice compared with WT mice in diabetes and MCC950 decreased diabetic vascular endothelial dysfunction to comparable levels in APN-KO mice and WT mice. Adiponectin could decrease NLRP3 inflammasome activation and attenuate endothelial cell injury, which was abolished by NLRP3 inflammasome overexpression. Inhibition of peroxynitrite formation preferentially attenuated NLRP3 inflammasome activation in APN-KO diabetic mice. The current study demonstrated for the first time that hypoadiponectinemia-induced NLRP3 inflammasome activation was a novel mechanism of diabetic vascular endothelial dysfunction.
Adiponectin suppression of high-glucose-induced reactive oxygen species in vascular endothelial cells: evidence for involvement of a cAMP signaling pathway.
Ouedraogo Raogo,Wu Xiangdong,Xu Shi-Qiong,Fuchsel Lauren,Motoshima Hiroyuki,Mahadev Kalyankar,Hough Kelly,Scalia Rosario,Goldstein Barry J
Adiponectin is an abundant adipocyte-derived plasma protein with antiatherosclerotic effects. Vascular signal transduction by adiponectin is poorly understood and may involve 5'-AMP-activated protein kinase (AMPK), cAMP signaling, and other pathways. Hyperglycemia sharply increases the production of reactive oxygen species (ROS), which play a key role in endothelial dysfunction in diabetes. Because the recombinant globular domain of human adiponectin (gAd) reduces the generation of endothelial ROS induced by oxidized LDL, we sought to determine whether adiponectin could also suppress ROS production induced by high glucose in cultured human umbilical vein endothelial cells. Incubation in 25 mmol/l glucose for 16 h increased ROS production 3.8-fold (P<0.05), using a luminol assay. Treatment with gAd for 16 h suppressed glucose-induced ROS in a dose-dependent manner up to 81% at 300 nmol/l (P<0.05). The AMPK activator 5-aminoimidazole-4-carboxamide-1-beta-D-ribofuranoside (AICAR; 1 mmol/l, 16 h) only partially decreased glucose-induced ROS by 22% (P<0.05). Cell pretreatment with AMPK inhibitors, however, failed to block the effect of gAd to suppress glucose-induced ROS, suggesting that the action of gAd was independent of AMPK. Interestingly, activation of cAMP signaling by treatment with forskolin (2 micromol/l) or dibutyryl-cAMP (0.5 mmol/l) reduced glucose-induced ROS generation by 43 and 67%, respectively (both P<0.05). Incubation with the cAMP-dependent protein kinase (PKA) inhibitor H-89 (1 micromol/l) fully abrogated the effect of gAd, but not that of AICAR, on ROS induced by glucose. gAd also increased cellular cAMP content by 70% in an AMPK-independent manner. Full-length adiponectin purified from a eukaryotic expression system also suppressed ROS induced by high glucose or by treatment of endothelial cells with oxidized LDL. Thus, adiponectin suppresses excess ROS production under high-glucose conditions via a cAMP/PKA-dependent pathway, an effect that has implications for vascular protection in diabetes.
Adiponectin enhances biological functions of vascular endothelial progenitor cells through the mTOR-STAT3 signaling pathway.
Dong Xiaoying,Yan Xia,Zhang Wei,Tang Shengqiu
Adiponectin (APN), an adipose tissue-excreted adipokine, plays protective roles in metabolic and cardiovascular diseases. In this study, the effects and mechanisms of APN on biological functions of rat vascular endothelial progenitor cells (VEPCs) were investigated in vitro. After administrating APN in rat VEPCs, the proliferation was measured by methyl thiazolyl tetrazolium (MTT) method, the apoptotic rate was test by Flow cytometry assay, mRNA expression of B-cell lymphoma-2 (Bcl-2) and vascular endothelial growth factor (VEGF) was determined by real-time reverse transcriptase polymerase chain reaction (RT-PCR), and protein expression of mechanistic target of rapamycin (mTOR), signal transducer and activator of transcription 3 (STAT3) and phospho-STAT3 (pSTAT3) was analyzed by Western blot. It was suggested that APN promoted the optical density (OD) value of VEPCs, enhanced mRNA expression of Bcl-2 and VEGF, and inhibited cell apoptotic rate. Furthermore, protein expression of pSTAT3 was also increased in the presence of APN. Moreover, APN changed-proliferation, apoptosis and VEGF expression of VEPCs were partially suppressed after blocking the mTOR-STAT3 signaling pathway by the mTOR inhibitor XL388. It was indicated that APN promoted biological functions of VEPCs through targeting the mTOR-STAT3 signaling pathway.
Globular adiponectin protects human umbilical vein endothelial cells against apoptosis through adiponectin receptor 1/adenosine monophosphate-activated protein kinase pathway.
Zhao Hong-Yu,Zhao Min,Yi Tong-Ning,Zhang Jin
Chinese medical journal
BACKGROUND:Endothelial dysfunction is a key event in the onset and progression of atherosclerosis in diabetic patients. Apoptosis may lead to endothelial dysfunction and contribute to vascular complications. However, no study has addressed apoptosis in human umbilical vein endothelial cells (HUVECs) induced by an intermittent high-glucose media and its association with adiponectin receptor 1 (adipoR1), adipoR2, or adenosine monophosphate (AMP)-activated protein kinase (AMPK). METHODS:HUVECs were cultured in continuous normal glucose (5.5 mmol/L), continuous high glucose (25 mmol/L), alternating normal and high glucose and mannitol. In the alternating normal and high-glucose media, HUVECs were treated under different conditions. First, cells were transfected with the adipoR1-specific small-interfering RNA (siRNA) and then stimulated with globular adiponectin (gAD). Second, cells were cultured in both gAD and the AMPK activator 5-aminoimidazole-4-carboxamide-1-β-D-ribofuranoside (AICAR). Third, cells were cultured in the AMPK inhibitor adenine-9-β-D-arabino-furanoside (araA), gAD, and in AICAR. RESULTS:HUVEC apoptosis increased more significantly in an intermittent high-glucose medium than in a constant high-glucose medium. HUVEC apoptosis induced by an intermittent high-glucose medium was inhibited when the cells were pretreated with 3 µg/ml gAD, which rapidly activated AMPK and adipoR1 in HUVECs. However, adipoR2 was not activated. CONCLUSIONS:We found that adipoR1, not adipoR2, is involved in mediating intermittent high-concentration glucose-evoked apoptosis in endothelial cells. gAD activated AMPK through adipoR1, leads to the partial inhibition of HUVEC apoptosis. A fluctuating glucose medium is more harmful than a constant high-glucose medium to endothelial cells.
Globular adiponectin counteracts VCAM-1-mediated monocyte adhesion via AdipoR1/NF-κB/COX-2 signaling in human aortic endothelial cells.
Addabbo Francesco,Nacci Carmela,De Benedictis Leonarda,Leo Valentina,Tarquinio Mariela,Quon Michael J,Montagnani Monica
American journal of physiology. Endocrinology and metabolism
Adiponectin (Ad) is an insulin-sensitizing adipocytokine with anti-inflammatory and vasoprotective properties. Cleavage of native full-length Ad (fAd) by elastases from activated monocytes generates globular Ad (gAd). Increased gAd levels are observed in the proximity of atherosclerotic lesions, but the physiological meaning of this proteolytic Ad fragment in the cardiovascular system is controversial. We compared molecular and biological properties of fAd and gAd in human aortic endothelial cells (HAEC). In control HAEC, both fAd and gAd acutely stimulated nitric oxide (NO) production by AMPK-dependent pathways. With respect to fAd, gAd more efficiently increased activation of NF-κB signaling pathways, resulting in cyclooxygenase-2 (COX-2) overexpression and COX-2-dependent prostacyclin 2 (PGI(2)) release. In contrast with fAd, gAd also increased p38 MAPK phosphorylation and VCAM-1 expression, ultimately enhancing adhesion of monocytes to endothelial cells. In HAEC lacking AdipoR1 (by siRNA), both activation of NF-κB as well as COX-2 overexpression by gAd were abrogated. Conversely, gAd-mediated p38MAPK activation and VCAM-1 expression were unaffected, and monocyte adhesion was greatly enhanced. In HAEC lacking COX-2 (by siRNA), reduced levels of PGI(2) further increased gAd-dependent monocyte adhesion. Our findings suggest that biological activities of fAd and gAd in endothelium do not completely overlap, with gAd possessing both AdipoR1-dependent ability to stimulate COX-2 expression and AdipoR1-independent effects related to expression of VCAM-1 and adhesion of monocytes to endothelium.
Protective actions of globular and full-length adiponectin on human endothelial cells: novel insights into adiponectin-induced angiogenesis.
Adya Raghu,Tan Bee K,Chen Jing,Randeva Harpal S
Journal of vascular research
BACKGROUND/AIMS:Adiponectin levels are decreased in diabetes and atherosclerosis. Coexisting hyperglycaemia and systemic inflammation predisposes to dysregulated angiogenesis and vascular disease. We investigated the effect of globular adiponectin (gAd) and full-length adiponectin (fAd) on angiogenesis and pro-angiogenic molecules, i.e. matrix metalloproteinase (MMP)-2, MMP-9 and vascular endothelial growth factor (VEGF), in human microvascular endothelial cells (HMEC-1). METHODS:Angiogenesis was assessed by studying capillary tube formation in HMEC-1 on growth factor-reduced Matrigel. Endothelial cell migration assay was performed in a modified Boyden chamber. RESULTS:Endothelial cell proliferation, in vitro migration and angiogenesis were significantly increased by gAd (mediated by AdipoR1, AMPK-Akt pathways), and gAd significantly increased MMP-2, MMP-9 and VEGF expression levels. The effect of gAd on VEGF appears to be mediated by AdipoR1, whilst the effect of gAd on MMP-2 and MMP-9 appears to be mediated by AdipoR1 and AdipoR2. Only endothelial cell proliferation was significantly increased by fAd in human microvascular endothelial cells and appears to be mediated by AdipoR2. No significant effects on MMP-2, MMP-9 and VEGF were observed. Importantly, gAd decreased glucose and C-reactive protein-induced angiogenesis with a concomitant reduction in MMP-2, MMP-9 and VEGF in HMEC-1 cells. CONCLUSION:We report novel insights into the mechanisms of adiponectin on angiogenesis.
Globular adiponectin induces adhesion molecule expression through the sphingosine kinase pathway in vascular endothelial cells.
Kase Hiroyuki,Hattori Yoshiyuki,Jojima Teruo,Okayasu Toshie,Tomizawa Atsuko,Suzuki Kunihiro,Banba Nobuyuki,Monden Tsuyoshi,Satoh Hiroko,Akimoto Kazumi,Kasai Kikuo
The signaling pathways that couple adiponectin receptors to functional, particularly inflammatory, responses have remained elusive. We report here that globular adiponectin induces endothelial cell activation, as measured by the expression of adhesion proteins such as vascular adhesion molecule-1 (VCAM-1), intracellular adhesion molecule-1 (ICAM-1), E-selectin and MCP-1, through the sphingosine kinase (SKase) signaling pathway. Treatment of human umbilical vein endothelial cells with globular adiponectin resulted in NF-kappaB activation and increased mRNA levels of VCAM-1, ICAM-1, E-selectin and MCP-1. Sphingosine 1-phosphate (S1P), but not ceramide or sphingosine, was a potent stimulator of adhesion protein expression. As S1P is generated from sphingosine by SKase, we treated cells with siRNA for SKase to silence the effects of S1P in the endothelial cells. Treatment with SKase siRNA inhibited globular adiponectin-induced NF-kappaB activation and markedly decreased the globular adiponectin-induced mRNA levels of adhesion protein. Thus, we demonstrated that the SKase pathway, through the generation of S1P, is critically involved in mediating globular adiponectin-induced endothelial cell activation.
Adiponectin induces NF-kappaB activation that leads to suppression of cytokine-induced NF-kappaB activation in vascular endothelial cells: globular adiponectin vs. high molecular weight adiponectin.
Tomizawa Atsuko,Hattori Yoshiyuki,Kasai Kikuo,Nakano Yasuko
Diabetes & vascular disease research
Adiponectin circulates in plasma as various isoforms. However, the biological activity of each isoform has not been firmly established. High molecular weight (HMW) adiponectin may be the active form of adiponectin, while a proteolytic cleavage product of adiponectin, known as globular adiponectin (gAd), has recently been shown to activate vascular endothelial cells. We compared HMW adiponectin with gAd to investigate whether they could activate nuclear factor kappa B (NF-kappaB) and suppress cytokine-induced NF-kappaB activation in vascular endothelial cells. HMW adiponectin was found to activate NF-kB modestly compared to the activation observed with gAd. HMW adiponectin requires a shorter incubation period to demonstrate inhibition against tumour necrosis factor alpha (TNFalpha)-induced NF-kappaB activation, compared with gAd. gAd strongly activates NF-kappaB, thereby inducing the expression of various pro-inflammatory and adhesion molecule genes, and requires a longer incubation period to show inhibition against cytokine-induced NF-kappaB activation. Thus, HMW adiponectin might function to protect against inflammatory stimuli, while cleavage of adiponectin at inflammatory sites might enhance the inflammatory process.
Induction of gene expression in response to globular adiponectin in vascular endothelial cells.
Tomizawa Atsuko,Hattori Yoshiyuki,Kasai Kikuo
AIMS:Adiponectin is an adipocyte-specific protein that plays an important regulatory role in the development or prevention of diabetes and atherosclerosis. MAIN METHODS:In the present study, we examined the effect of a proteolytic cleavage product of adiponectin, known as globular adiponectin (gAd), on induction of gene expression and activation of various signaling pathways in vascular endothelial cells. KEY FINDINGS:We showed that gAd induces the expression of a number of genes using PCR arrays, including MCP-1, VCAM-1, E-selectin, IL-6, and IL-8, all of which have been previously shown to be associated with adiponectin, as well as SOD2, PAI-1, and CSF2, which is a new finding. We also demonstrated that gAd activates AMPK, Akt, and NF-kB, as well as various MAPKs, including ERK1/2, JNK, and p38MAPK. SIGNIFICANCE:Upstream regulation of gene expression might involve two or more activated pathways which interact with one another.
Adiponectin modulates the function of endothelial progenitor cells via AMPK/eNOS signaling pathway.
Wang Shuhong,Miao Jie,Qu Meijie,Yang Guo-Yuan,Shen Linhui
Biochemical and biophysical research communications
Endothelial progenitor cells have been shown to differentiate into endothelial cells and to play a pivotal role in vascular homeostasis. Adiponectin has anti-atherogenic and anti-inflammatory properties via directly acting on vascular cells. The aim of the present study is to explore the effect of adiponectin on major functions involved in survival, migration, and tube formation of endothelial progenitor cells and to explore the underlying mechanism. In this study, we transferred adiponectin gene into endothelial progenitor cells via lentiviral vectors and investigated the proliferation, migration and tube formation of these transfected cells. We found that adiponectin is highly expressed in endothelial progenitor cells and promotes their proliferation, migration and tube formation. Western blot data showed that the former two processes were mediated through the AMPK/Akt/eNOS pathway, the latter via the AMPK/eNOS pathway. Use of the AMPK inhibitor (Compound C) or Akt inhibitor (MK-2206) reduced eNOS phosphorylation and attenuated adiponectin-induced endothelial progenitor cell proliferation, migration and tube formation compared to the controls (p < 0.05). Taken together, these data indicated that adiponectin promotes endothelial progenitor cell proliferation and migration via AMPK/Akt/eNOS signaling pathway and promotes tube formation through AMPK/eNOS, suggesting that adiponectin-transduced endothelial progenitor cell transplantation is a potential therapeutic target for vascular disease.
Adiponectin alleviates NLRP3-inflammasome-mediated pyroptosis of aortic endothelial cells by inhibiting FoxO4 in arteriosclerosis.
Zhang Liwei,Yuan Ming,Zhang Liang,Wu Bin,Sun Xiao
Biochemical and biophysical research communications
Endothelial dysfunctions, such as pyroptosis, are chronic inflammatory processes with important roles in atherosclerosis. Adiponectin (APN), an adipocyte-derived protein that is abundant in circulation, reportedly protects against atherosclerosis. However, the mechanism underlying its antiatherogenic effect on human aortic epithelial cells remains unknown. In this study, oxidized lipopolysaccharide dose-dependently decreased cell viability and increased lactate dehydrogenase release and pyroptosis in human aortic epithelial cells. Western blot and RT-qPCR assays also showed that APN suppressed activation of the NOD-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome, as evidenced by cleavage of caspase-1 and downstream secretion of mature interleukin (IL)-1β and IL-18. Silencing of NLRP3 by small interfering RNA remarkably inhibited lipopolysaccharide-induced pyroptosis. Intriguingly, APN led to decreased expression of FoxO4 in human aortic epithelial cells that were exposed to lipopolysaccharide. Moreover, overexpression of FoxO4 inhibited NLRP3-mediated pyroptosis, reversed APN-induced activation of the NLRP3 inflammasome, and reversed pyroptosis in these cells. Specifically, APN reduced propidium-iodide-positive cells, NLRP3 inflammasomes, apoptosis-related speck-like protein containing caspase recruitment domains, and pro-inflammation factors IL-1β and IL-18, all of which was reversed by overexpression of FoxO4. In conclusion, our study suggests that APN might play an essential role in NLRP3 inflammasome-modulated pyroptosis by regulating FoxO4 in human aortic epithelial cells, providing a novel therapy for atherosclerosis.
Anti-angiogenic effect of adiponectin in human primary microvascular and macrovascular endothelial cells.
Palanisamy Karthikka,Nareshkumar Ragavachetty Nagaraj,Sivagurunathan Suganya,Raman Rajiv,Sulochana Konerirajapuram Natarajan,Chidambaram Subbulakshmi
Neovascularization in retina and choroid involves interplay of many cytokines and growth factors. Vascular endothelial growth factor (VEGF) being a pro-angiogenic molecule has been found to be high in aqueous and vitreous humour of patients with proliferative diabetic retinopathy (PDR). VEGF is also found in the fibroblast and retinal pigment epithelial cells (RPE) of choroidal neovascular (CNV) membranes isolated from patients. Though anti-VEGF agents cause regression of clinically visible new vessels, there is evidence that they increase the occurrence of retinal tractional detachment and other adverse effects in PDR and CNV treatments. Adiponectin (APN) is a cytokine, found to be involved in the pathobiology of PDR. It is unclear whether APN plays a reparative or pathological role in the disease condition. In this study, we explored the effect of APN on tube formation in the primary culture of human umbilical vein macrovascular endothelial cells (HUVEC), human retinal microvascular endothelial cells (hREC) and human choroidal endothelial cells (hCEC). Anti-VEGF agent, bevacizumab (avastin) was used as a control. Full-length pAc-APN transfected in HUVEC, hRECs and hCECs inhibited basal tube formation and migration comparable to bevacizumab (Avastin™). In hRECs, full length pAc-APN reduced VEGF or PDR vitreous mediated migration. In a similar way, rAPN significantly disrupted VEGF and PDR vitreous induced tube formation in HUVEC and hREC. Moreover, rAPN significantly reduced VEGF influenced proliferation and phosphorylation of ERK1/2 in hREC. Altogether, our study suggests that APN may be effective in the treatment of retinal neovascularization.
Adiponectin inhibits proliferation of vascular endothelial cells induced by Ox-LDL by promoting dephosphorylation of Caveolin-1 and depolymerization of eNOS and up-regulating release of NO.
Lu Yan,Gao Xiaoying,Wang Ruihua,Sun Jing,Guo Beibei,Wei Ruipeng,Jia Yongping
Oxidized low density lipoprotein (ox-LDL) can induce the proliferation and differentiation of endothelial cells, which is one of the important mechanisms of ox-LDL atherosclerosis. Adiponectin is an endogenous bioactive polypeptide secreted by adipocytes, it participates in the metabolism of fat and glucose. It has the effect of reducing blood triglyceride and LDL content. Adiponectin also inhibits the abnormal proliferation and migration of endothelial cells, but its molecular mechanism is unclear. In this study, we used cell model of Ox-LDL-induced human aortic endothelial cells (HAECs) proliferation to analyze the molecular mechanism of APN inhibiting HAECs abnormal proliferation. The results showed that APN could inhibit the cell viability and DNA synthesis of HAECs after Ox-LDL treatment, up-regulate the apoptosis level and reduce the proportion of S + G2 phase cells. Further analysis showed that adiponectin could promote the dephosphorylation of Caveolin-1, which could dissociate eNOS and Caveolin-1, promote the phosphorylation of eNOS and enhance the synthesis of NO. NO increased expression levels of cleaved caspase 3 and p21 in the cells and inhibited the abnormal proliferation of HAECs. The regulation of phosphorylation and dephosphorylation of Caveolae-1 plays a key role in this process. Further study of the molecular mechanism of Caveolae-1 in the inhibition of HAECs abnormal proliferation by APN may reveal the potential of APN in the treatment of cardiovascular diseases.