Enhanced Expression of NLRP3 Inflammasome-Related Inflammation in Diabetic Retinopathy

The aim of this study was to determine the association between nucleotide-binding and oligomerization domain (NOD)-like receptors (NLRs) family, pyrin domain-containing 3 (NLRP3) inflammasome-induced inflammation and disease severity in diabetic retinopathy (DR).

Blood samples were collected from 64 patients with diabetes (DR, 43; without DR, 21) and 25 healthy controls. The protein and mRNA expression levels of NLRP3 inflammasomes in peripheral blood mononuclear cells were determined using western blotting and quantitative real-time reverse transcription-PCR. A total of 82 vitreous samples were obtained from patients with DR (n = 60) and nondiabetic controls (n = 22). All patients were candidates for vitrectomy. Interleukin (IL)-1β and IL-18 in the peripheral blood mononuclear cell culture medium and vitreous fluid were detected by enzyme-linked immunosorbent assay (ELISA). Immunofluorescence staining for apoptosis-associated speck-like protein with a caspase recruitment domain (ASC) and NLRP3 was performed in fibrovascular membranes from 21 proliferative DR patients and 22 controls with idiopathic epiretinal membranes.

We observed increased gene and protein expression of NLRP3, ASC, and caspase-1 in peripheral blood mononuclear cells of adults with DR compared with that in normal controls. Furthermore, the elevated expressions of NLRP3 and ASC were observed in the fibrovascular membranes from 21 adults with proliferative DR when compared with the 22 controls. IL-1β and IL-18 in the peripheral blood mononuclear cells and vitreous fluid were elevated in the DR patients when compared with controls.

These outcomes suggested that NLRP3 inflammasomes are upregulated in adults with DR and may play a key role in the pathogenesis and progression of DR.