Resolvin D1 inhibits inflammatory response in STZ-induced diabetic retinopathy rats: Possible involvement of NLRP3 inflammasome and NF-κB signaling pathway.

PURPOSE: To investigate the effect of resolvin D1 (RvD1) on the Nod-like receptor family pyrin domain-containing (NLRP3) inflammasome and the nuclear factor-kappa beta (NF-κB) pathway in streptozotocin (STZ)-induced diabetic retinopathy in rats.

METHODS: Ninety-six male rats were divided into four groups: control, STZ, RvD1, and vehicle. The rats with diabetic retinopathy induced by STZ in the RvD1 and vehicle groups were given an intravitreal injection of RvD1 (1,000 ng/kg) or the same dosage of vehicle, respectively. All rats were euthanized 7 days following treatment. Hematoxylin and eosin staining was used to observe the pathological changes in the retinal tissues. The location and expression of the NLRP3 inflammasome components, including NLRP3, caspase-associated recruitment domain (ASC), and caspase-1, in the retinas were detected using immunohistochemistry, real-time PCR, and western blot, respectively. Retinal homogenate of rats were collected for the detection of the downstream molecules interleukin 1 beta (IL-1β) and IL-18 of the NLRP3 inflammasome with enzyme-linked immunosorbent assay kits.

RESULTS: The levels of NLRP3, ASC, cleaved caspase-1, IL-1β, and IL-18 were upregulated in the retinas of the STZ-induced diabetic rats; however, these changes were partially inhibited by the RvD1 treatment. Furthermore, the administration of RvD1 suppressed activation of NF-kB, which was upregulated in STZ-induced diabetic retinopathy.

CONCLUSIONS: RvD1 plays a protective role in STZ-induced diabetic retinopathy by inhibiting the level of activation of the NLRP3 inflammasome and associated cytokine production, suggesting targeting of this pathway might be an effective strategy in treatment of diabetic retinopathy.