Down-regulation of LCN2 attenuates retinal vascular dysfunction and caspase-1-mediated pyroptosis in diabetes mellitus

BACKGROUND: Diabetic retinopathy (DR) is a diabetic microangiopathy with increasing incidence, which seriously threatens the quality of life of patients. This study investigated the molecular regulation mechanism of lipocalin-2 (LCN2) in DR by targeting the function of human retinal vascular endothelial cells (HRVECs). METHODS: The expression of LCN2 in the retinal tissue of diabetic and high glucose (HG)-induced HRVECs was detected by reverse transcription quantitative polymerase chain reaction (RT-qPCR) analysis and western blotting assay. After intravitreal injection of adeno-associated virus (AAV)-NC or AAV-sh-LCN2, in vivo experiments, hematoxylin and eosin (H&E) staining, and retinal trypsin digestion experiments were performed to analyze the effect of LCN2 silencing on DR retinal tissue. Terminal deoxynucleotidyl transferase biotin-dUTP nick end labeling (TUNEL) staining was used to evaluate apoptosis and immunohistochemical (IHC) staining was performed to detect the expressions of caspase-1. Western blot was used to detect the expressions of pyroptosis-associated proteins. After transfection of sh-NC and sh-LCN2, the function of HRVECs cells induced by HG was evaluated by wound healing assay, Transwell assay, and tube formation assay. RESULTS: The expression of LCN2 was significantly up-regulated in diabetic retinal tissue and HG-induced HRVECs. In vivo experiments showed that LCN2 silencing can significantly reduce diabetic retinal injury. Cell function experiments also revealed that LCN2 silencing inhibited cell migration, invasion, and angiogenesis. Flow cytometry and immunofluorescence staining showed that downregulation of LCN2 could inhibit caspase-1 mediated pyroptosis in HG-induced HRVECs. CONCLUSIONS: Down-regulation of LCN2 can significantly inhibit cell migration, invasion, and angiopoiesis, and pyroptosis regulated by caspase-1, thus attenuating the progression of DR.