Investigation Of Meibomian Gland Change Induced By Diabetes And Its Mechanism

Purpose:Metabolic disorders caused by long-term hyperglycemia in diabetic patients lead to eye complication.This study aims to explore t:he morphological change of meibomian gland in diabetes as well as the possible mechanism and treatment strategy.Methods:SD rats were intraperitoneally injected with Streptozotocin(STZ)to establish a diabetic animal model.The ocular surface morphology and meibomian gland morphology were observed by slit lamp and stereoscopic microscope at 2 weeks,2 months and 4 months after injection.The histological change and inflammatory cell infiltration of meibomian gland were observed by HE staining and immunohistochemical staining of paraffin sections.Meanwhile,the expression levels of inflammatory cytokines such as IL-la?IL-1? and TNFa,as well as adhesion molecules ELAM1,ICAM1 and VCAM1 were detected.The protein expression levels of pJNK,JNK,IKK,ERK,pERK,NF-kB p65 was detected by Western Blot.TUNEL staining and immunofluorescent staining were applied to observe the change of apoptosis and proliferation of meibomian gland cells.The expression levels of the apoptosis-related factors Caspase3,Caspase8,Caspase9,apoptosis-related protein Bcl2 and apoptosis-inhibiting protein Bax were detected.mRNA and protein expression levels of factors related to oxidative stress such as NOX4,Nrf2,Keap1,SOD2,HO-1 were detected separately by Real-Time PCR and Western Blot.Results:Compared with normal SD rats of the same age,the meibomian gland structure remained intact 2 weeks after STZ injection without inflammatory cell infiltration.After 2 months of STZ injection,meibomian gland showed slight glandular structure disorder and inflammatory cell infiltration,but the expression of inflammatory factors and related signaling pathways did not change significantly.After 4 months of STZ injection,we can easily observe that the palpebral margins of rats were rough and unclear,meibomian gland morphology and structure were disorganized,and a part of gland missed.Obvious infiltration of inflammatory cells,increased expression of inflammatory factors and adhesion molecules,increased expression of pJNK,JNK,IKK,ERK,pERK,and activated JNK-IKK signaling pathway were identified.We could also find that the expression of Nrf25 Keap1,HO-1 and SOD2 decreased with the increase of NOX4 expression.4 months after diabetes mellitus modeling,the expression of Ki67 was lower than the normal group while TUNEL staining was higher.The morphology of meibomian gland was well maintained after Acacetin intervention.Conclusion:Long-term diabetes can lead to the disorder of meibomian gland morphology and structure,infiltration of inflammatory cells and increase of inflammatory factors,and the pathological change develop with the continuous course of diabetes.Oxidative stress,inflammation and apoptosis may involve in the meibomian gland pathological change.The effect of Acacin intervention was significant.