Maresin 1 activates autophagy through SIRT1/PPAR-γ signaling to mitigate high glucose-induced pyroptosis in human retinal pigment epithelial cells.

Abstract

Accumulating evidence suggests that maresin 1 (MaR1), a docosahexaenoic acid-derived specialized pro-resolving lipid mediator, safeguards ARPE-19 cells against high glucose (HG)-induced ferroptosis, with potential relevance in preventing the onset and progression of diabetic retinopathy (DR). Building upon this observation, the present study aimed to elaborate on the functional role of MaR1 in DR and explore the underlying mechanisms mediating its protective effects. ARPE-19 cells were exposed to HG to mimic DR in vitro and treated with varying doses of MaR1. An MTT assay was conducted to assess cell viability, while ELISA was used to measure the levels of inflammatory factors in the cells. Monodansylcadaverine staining was used to evaluate autophagic flux. Additionally, immunofluorescence and western blot assays were used to detect the expression of proteins associated with pyroptosis, autophagy and the sirtuin 1 (SIRT1)/peroxisome proliferator-activated receptor-γ (PPAR-γ) signaling pathway. To further investigate the mechanism underlying the actions of MaR1, ARPE-19 cells were pretreated with a SIRT1 inhibitor (EX-527) or an autophagy inhibitor (3-MA) before the aforementioned treatments were administered. The findings revealed that MaR1 rescued cell viability and attenuated the expression and secretion of pro-inflammatory cytokine levels (specifically IL-1β and IL-18) in HG-challenged ARPE-19 cells in a dose-dependent manner, while also alleviating the HG-induced reduction in autophagic flux. Pretreatment with MaR1 further reversed the HG-mediated downregulation of beclin 1, LC3-II/I, SIRT1 and PPAR-γ, alongside the HG-triggered upregulation of p62, gasdermin D N-terminal, cleaved caspase-1, NLR family pyrin domain containing 3, apoptosis-associated speck-like protein containing a CARD and IL-18, as demonstrated through immunofluorescence and western blot analyses. Notably, an autophagy inhibitor blunted the regulatory effects of MaR1 on pyroptosis, whereas a SIRT1 inhibitor abrogated the protective actions of MaR1 against inflammation and pyroptosis, as well as its modulation of autophagy, as demonstrated by measuring key molecular markers of pyroptosis, inflammation and autophagy in treated ARPE-19 cells. Overall, the results indicated that MaR1 mitigated HG-induced pyroptosis in human retinal pigment epithelial cells, potentially by upregulating the SIRT1/PPAR-γ signaling pathway to reinstate autophagy, thus ameliorating DR-associated damage.