Circ_0091702 serves as a sponge of miR-545-3p to attenuate sepsis-related acute kidney injury by upregulating THBS2.

Circular RNA (circRNA) has been shown to play an important function in the progression of human diseases, including sepsis with acute kidney injury (AKI). However, the role and mechanism of circ_0091702 in sepsis-induced AKI have yet to be confirmed. Lipopolysaccharide (LPS) was used to induce HK2 cells to construct AKI cell models in vitro. Quantitative real-time PCR was used to measure the expression of circ_0091702, inflammatory cytokines, microRNA (miR)-545-3p and thrombospondin 2 (THBS2). Cell counting kit 8 assay and flow cytometry were used to assess cell viability and apoptosis. Besides, the protein levels of apoptosis markers and THBS2 were evaluated by western blot analysis. In addition, the concentrations of inflammatory cytokines were detected by enzyme-linked immunosorbent assay (ELISA). Cell oxidative stress was determined by detecting the contents of oxidative stress markers. Dual-luciferase reporter assay and RIP assay were used to confirm the relationship between miR-545-3p and circ_0091702 or miR-545-3p and THBS2. Circ_0091702 was downregulated in septic AKI patients and LPS-induced HK2 cells. Circ_0091702 could attenuate LPS-induced HK2 cell injury, while its silencing had an opposite effect. In the terms of mechanism, circ_0091702 could act as a sponge of miR-545-3p, and miR-545-3p could directly target THBS2. Functional experiments revealed that miR-545-3p could reverse the alleviating effect of circ_0091702 on LPS-induced HK2 cell injury, and THBS2 knockdown also could overturn the suppressing effect of miR-545-3p inhibitor on LPS-induced HK2 cell injury. Additionally, we also suggested that circ_0091702 could sponge miR-545-3p to regulate THBS2 expression. In conclusion, our results showed that circ_0091702 could suppress LPS-induced HK2 cell injury via the miR-545-3p/THBS2 axis, indicating that circ_0091702 might be an important biomarker for relieving sepsis-related AKI.