Let-7a Targeting TNFAPI3 Promotes Vascular Endothelial Cell Apoptosis of Pediatric Patients with Henoch–Schönlein Purpura via NF-κB Signaling Pathway

OBJECTIVE: We aimed at exploring the role of let-7a in the pathogenesis of pediatric Henoch–Schönlein purpura (HSP) and its related mechanism. METHODS: Fifty-five pediatric HSP patients and 20 paired healthy controls were included. The expressions of let-7a and TNFAIP3 were detected by RT-qPCR or/and western blot. Vessel fibrinoid necrosis was evaluated in skin tissues by PTAH staining. The serum IgA level was measured by ELISA. Cells were transfected with let-7a inhibitor and/or TNFAIP3 siRNA, accompanied by pretreatment with NF-κB inhibitor PDTC or not. After being cultured in HSP serum, the changes in cell viability, cell apoptosis, apoptosis-related proteins, and NF-κB pathway-related proteins were detected by CCK8, flow cytometry, and western blot. RESULTS: The let-7a expression level was positively correlated with the serum IgA level and severity degree of vascular fibrinoid necrosis in HSP patients. Let-7a expression was significantly increased, whereas cell viability and TNFAIP3 expression were obviously decreased 48 h after HUVECs were incubated with HSP serum. Let-7a knockdown upregulated the cell viability, whereas it reduced the apoptotic ratio, apoptosis protein expressions (Bax/Bcl2 ratio, cleaved-caspase 3), and NF-κB pathway activation (reflected by reduced P65 nuclear translocation and p-IκBα expression) in HUVECs (all p < 0.05). The changes induced by let-7a knockdown were obviously reversed by TNFAIP3 siRNA transfection (p < 0.05). Besides, PDTC treatment remarkably diminished the anti-apoptosis effect of let-7a knockdown and pro-apoptosis effect of TNFAIP3 siRNA on HUVECs induced by HSP serum. CONCLUSIONS: Let-7a knockdown significantly suppressed vascular endothelial cell apoptosis induced by HSP serum by targeting TNFAPI3 via NF-κB signaling pathway. Our findings provided a potential therapeutic target for the treatment of HSP.