Aggregated neutrophil extracellular traps occlude Meibomian glands during ocular surface inflammation.
Mahajan Aparna,Hasíková Lenka,Hampel Ulrike,Grüneboom Anika,Shan Xiaomei,Herrmann Irmgard,Garreis Fabian,Bock Felix,Knopf Jasmin,Singh Jeeshan,Schauer Christine,Mahajan Siddharth,Leppkes Moritz,Paulsen Friedrich,Schlötzer-Schrehardt Ursula,Krenn Veit,Jünemann Anselm,Hohberger Bettina,Schett Georg,Herrmann Martin,Muñoz Luis E
The ocular surface
PURPOSE:Obstructive Meibomian gland dysfunction (MGD) is one of the leading causes of evaporative dry eye disease. Meibomian glands at the eyelid secrete lipids that prevent evaporation of the aqueous tear film. The pathogenesis of obstructive MGD is incompletely understood to date. Herein, we aim to investigate the pathogenesis of obstructive MGD using murine and human samples with various forms of ocular surface inflammation. METHOD:The presence of Neutrophil extracellular Traps (NETs) was detected with immunofluorescence analysis of ocular surface discharge and biopsy samples from patients with blepharitis. Tear fluid from patients with MGD and blepharitis were evaluated for the presence of inflammatory mediators using bead based immunoassay. Murine model of allergic eye disease (AED) was performed to investigate the role of NETs in MG occlusion. RESULTS:we show that the ocular discharge from patients with blepharitis contains aggregated neutrophil extracellular traps (aggNETs). Furthermore, the ducts of human Meibomian glands affected by blepharitis were largely congested by aggNETs. Tear fluid from patients with MGD showed elevated neutrophil chemoattractants (C5a, IL6, IL8 and IL18). C5a and IL8 correlated with the degree of deficiency of tear fluid. In the murine model of allergic eye disease (AED), aggNETs accumulated in the MG leading to occlusion of their ducts and the retrograde pent-up of the fluid followed by acinar atrophy. Constraining aggNET formation by genetic or pharmacological inhibition of peptidyl arginine deiminase type 4 (PADI4) effectively reduced MG damage. CONCLUSION:We conclude that aggNETs occlude MG causing MGD after ocular surface inflammation.
10.1016/j.jtos.2020.12.005
Organotypic Culture of Mouse Meibomian Gland: A Novel Model to Study Meibomian Gland Dysfunction In Vitro.
Xu Kang-Kang,Huang Yu-Kan,Liu Xin,Zhang Ming-Chang,Xie Hua-Tao
Investigative ophthalmology & visual science
Purpose:Meibomian glands are essential in maintaining the integrity and health of the ocular surface. Meibomian gland dysfunction (MGD), mainly induced by ductal occlusion, is considered as the major cause of dry eye disease. In this study, a novel in vitro model was established for investigating the role of inflammation in the process of MGD. Methods:Mouse tarsal plates were removed from eyelids after dissection and explants were cultured during various time ranging from 24 to 120 hours. Meibomian gland epithelial cells were further enzymatically digested and dissociated from tarsal plates before culturing. Both explants and cells were incubated in different media with or without serum or azithromycin (AZM). Furthermore, explants were treated with IL-1β or vehicle for 48 hours. Analyses for tissue viability, histology, biomarker expression, and lipid accumulation were performed with hematoxylin and eosin (H&E) staining, immunofluorescence staining, and Western blot. Results:Higher viability was preserved when explants were cultured on Matrigel with immediate addition of culture medium. The viability, morphology, biomarker expression, and function of meibomian glands were preserved in explants cultured for up to 72 hours. Lipid accumulation and peroxisome proliferator-activated receptor γ (PPARγ) expression increased in both explants and cells cultured in media containing serum or AZM. Treatment with IL-1β induced overexpression of Keratin (Krt) 1 in meibomian gland ducts. Conclusions:Intervention with pro-inflammatory cytokine IL-1β induces hyperkeratinization in meibomian gland ducts in vitro. This novel organotypic culture model can be used for investigating the mechanism of MGD.
10.1167/iovs.61.4.30
c-Jun NH2-terminal kinase mediates interleukin-1beta-induced inhibition of lacrimal gland secretion.
Zoukhri Driss,Macari Elizabeth,Choi Sun H,Kublin Claire L
Journal of neurochemistry
Sjögren's syndrome, an inflammatory disease affecting the lacrimal and salivary glands, is the leading cause of aqueous tear-deficient type of dry eye. We previously showed that interleukin-1beta (IL-1beta) protein is up regulated in the lacrimal gland of a murine model of Sjögren's syndrome and that exogenous addition of this cytokine inhibits neurotransmitter release and lacrimal gland protein secretion. In the present study we investigated the role of c-Jun NH2-terminal kinase (JNK) in IL-1beta-mediated inhibition of lacrimal gland secretion and tear production. In vitro, IL-1beta induced a time-dependent activation of JNK with a maximum 7.5-fold at 30 min. SP600125, a JNK inhibitor, inhibited, in a concentration-dependent manner, IL-1beta-induced activation of JNK with a maximum of 87% at 10(-4) m. In vivo, IL-1beta stimulated JNK and the expression of the inducible isoform of nitric oxide synthase (iNOS). IL-1beta inhibited high KCl and adrenergic agonist induced protein secretion by 85% and 66%, respectively. SP600125 alleviated the inhibitory effect of IL-1beta on KCl- and agonist-induced protein secretion by 79% and 47%, respectively, and completely blocked the expression of iNOS. Treatment for 7 days with SP600125 increased tear production in a murine model of Sjögren's syndrome dry eye. We conclude that JNK plays a pivotal role in IL-1beta-mediated inhibition of lacrimal gland secretion and subsequent dry eye.
10.1111/j.1471-4159.2005.03529.x
Byakangelicin inhibits IL-1β-induced mouse chondrocyte inflammation in vitro and ameliorates murine osteoarthritis in vivo.
Zhang Tan,He Lei,Yang Wanlei,Wang Yanben,Peng Jiaxuan,Sun Peng,Yang Qichang,Jia Yewei,Zhao Kanxian,Qian Yu
International immunopharmacology
Osteoarthritis (OA) is a chronic musculoskeletal degeneration disease, resulting in severe consequences such as chronic pain and functional disability. Owing to the complex pathology, there are currently available preventative clinical therapies for OA. Several studies have reported the potential anti-inflammatory effects of byakangelicin (BYA), a component of the Angelica dahurica root extract; however, the effects of BYA in OA remain unknown. In this study, we investigated the protective effects of BYA in interleukin (IL)-1β-induced mouse chondrocytes in vitro and on surgical destabilization in a medial meniscus (DMM) mouse OA model in vivo. In vitro, BYA treatment inhibited IL-1β-mediated inducible nitric oxide synthase, cyclooxygenase-2, tumor necrosis factor-alpha, and IL-6 expression. Moreover, BYA promoted the expression of type two collagen and aggrecan but inhibited the expression of thrombospondin motifs 5 and matrix metalloproteinases, leading to degradation of the extracellular matrix. In addition, BYA mechanistically suppressed nuclear factor-kappa B signaling in the IL-1β-induced chondrocytes. The protective effects of BYA in OA development were also observed in vivo using the DMM model. In conclusion, our results highlight BYA as a candidate for OA treatment and prevention.
10.1016/j.intimp.2020.106605