We investigated the expression of the proinflammatory and proangiogenic factor osteoprotegerin (OPG) and its ligands, receptor activator of nuclear factor-κB ligand (RANKL), tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), and the receptor RANK in proliferative diabetic retinopathy (PDR).
We have recently reported that vitreous levels of IL-4, IL-17A, IL-22, IL-31, and TNFα are higher than the respective serum levels in proliferative diabetic retinopathy (PDR) patients, and that vitreous levels of these cytokines are higher in PDR than in other non-inflammatory vitreoretinal diseases or uveitis associated with sarcoidosis.
Similarly, the levels of inflammatory mediators IL-1β (P < 0.0001), IL-6 (P = 0.0005), IL-8 (P < 0.0001), and TNF-α (P < 0.0001) were also higher in eyes with DR. Interestingly, inflammatory cytokine and NT levels, particularly TNF-α (P < 0.05), IL-8 (P < 0.004), NT-3 (P = 0.012), NGF (P = 0.04), GDNF (P = 0.005), and CNTF (P = 0.002), were higher in eyes with nonproliferative diabetic retinopathy (NPDR) than in eyes with active proliferative diabetic retinopathy (PDR).
Inflammasome components NLRP3 and caspase-1, inflammasome-related pro-inflammatory cytokines IL-1β and IL-18, vascular endothelial growth factor (VEGF), acute-phase cytokines TNF-α and IL-6, as well as adaptive immunity-related cytokine interferon gamma (IFN-γ) were measured from the vitreous samples of 15 non-proliferative diabetic retinopathy (non-PDR) and 23 proliferative diabetic retinopathy (PDR) patients using the enzyme-linked immunosorbent assay (ELISA) method.
Tumor necrosis factor-like weak inducer of apoptosis (TWEAK) and its receptor Fn14 have been reported to promote pro-inflammatory cytokines, which are involved in the pathogenesis of proliferative diabetic retinopathy (PDR).
In the present study, we made an attempt to investigate the possible association of the promoter polymorphisms of interleukin 6, tumor necrosis factor α, and interleukin 10 for the pathogenesis of proliferative diabetic retinopathy (PDR).