Long noncoding RNA MIAT regulates primary human retinal pericyte pyroptosis by modulating miR-342-3p targeting of CASP1 in diabetic retinopathy.

Diabetic retinopathy (DR) is the leading cause of visual impairment and acquired blindness among adults worldwide. Retinal microvascular pericyte deficiency is one of the earliest pathological changes associated with DR, and long noncoding RNA myocardial infarction-associated transcript (MIAT) has been implicated as a crucial regulator of microvascular dysfunction in DR. Pyroptosis is a caspase-1-dependent proinflammatory form of cell death, and in the present study, we investigated the potential pyroptosis of primary human retinal pericytes (HRPCs) and the mechanism by which MIAT is involved in this process. We applied advanced glycation end product modified bovine serum albumin (AGE-BSA) to simulate the DR environment. The results suggested that AGE-BSA induced the active cleavage of caspase-1 and gasdermin D, the release of IL-1β, IL-18 and LDH, and reduced cell viability, which was prevented by the inhibition of caspase-1, indicating the occurrence of caspase-1-mediated pyroptosis in HRPCs. Immunofluorescence images revealed the phenotypic characteristics of pyroptosis, including pyknosis, swelling and hyperpermeability in plasmolemma. MIAT and CASP1 expression were substantially increased, while that of miR-342-3p was decreased in AGE-BSA-treated HRPCs. MIAT knockdown inhibited pyroptosis in HRPCs, which was reinforced by cotreatment with miR-342-3p mimic but relieved by cotreatment with miR-342-3p inhibitor. Furthermore, HRPC pyroptosis was inhibited by treatment with the miR-342-3p mimic alone but enhanced by the miR-342-3p inhibitor. Luciferase reporter assay results demonstrated binding between MIAT and miR-342-3p, as well as between miR-342-3p and CASP1. MIAT antagonized the effect of miR-342-3p on the depression of its target CASP1 and promoted AGE-BSA-induced pericyte pyroptosis. These findings may promote a better understanding of retinal pericyte depletion pathogenesis and the development of new therapeutic strategies for the treatment of diabetic retinopathy.