Abstract
Purpose :
Diabetic retinopathy (DR) is a neurodegenerative and microvascular retinal disorder. It is a multifactorial disease involving chronic inflammation and oxidative stress. Prolonged diabetes instigates endogenous myeloid-related danger signals often described as damage-associated molecular patterns (DAMPs) promoting sterile inflammation leading to cellular stress in the retina. Our previous study found that S100A9, a proinflammatory DAMP was associated with the severity of diabetic retinopathy. Here, we explore the mechanistic role of S100A9 in diabetic retinopathy (DR) in vitro in human retinal microvascular endothelial cells (HRMECs).
Methods :
Primary HRMECs were treated with different concentrations of recombinant human S100A9 DAMPs protein for 1-hour, 4-hour, and 24-hour time points. HRMECs were assessed for cellular and morphological evaluation for proliferation, migration, wound healing, and apoptosis. Conditioned media was collected to measure extracellular cytokines and chemokines using ELISA assay. HRMECs were lysed and collected for molecular gene expression analysis using quantitative real-time PCR. Cell-based cellular assays and immunocytochemistry (ICC) were performed for protein expression.
Results :
S100A9 induced a dose- and time-dependent progression of the proinflammatory index in the primary HRMECs. S100A9 prefers TLR4 as its binding partner and activates NLRP3 inflammasome regulating autoinflammatory feedback loop secreting IL-1β and IL-18.
Conclusions :
S100A9 may play a proinflammatory role in instigating early damage to the retinal microvasculature, supporting our hypothesis for its role in DR pathogenesis via activation of TLR4-driven NLRP3 inflammasome.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.