CircC3P1 attenuated pro-inflammatory cytokine production and cell apoptosis in acute lung injury induced by sepsis through modulating miR-21.

Acute lung injury (ALI) induced by sepsis is characterized by an inflammatory process related to the up-regulation of inflammatory cytokines and chemokines. In the present study, we explored the role of circC3P1 in sepsis-induced ALI in vitro and in vivo. The caecal ligation and puncture (CLP)-induced sepsis model was established through CLP surgery. Forty adult male C57BL/6 mice were randomly assigned into sham, CLP, CLP + vector and CLP + circC3P1 (each n = 10). Primary murine pulmonary microvascular endothelial cells (MPVECs) were transfected with circC3P1 or empty vector 24 hours prior to LPS treatment via Lipofectamine 2000. The expressions of circC3P1, tumour necrosis factor-α (TNF-α), interleukin-6 (IL-6) and IL-1ß were evaluated after 6-h LPS treatment. Cell apoptosis was evaluated via flow cytometry. The CLP group demonstrated pulmonary morphological abnormalities, increased concentrations of TNF-α, IL-6 and IL-1ß in the lung tissue, compared with the sham group. MPVECs treated with LPS significantly elevated TNF-α, IL-6 and IL-1ß levels and increased cell apoptosis than that in the control group. The circC3P1 overexpression in sepsis-induced ALI mice attenuated pulmonary injury, inflammation and apoptosis. Besides, circC3P1 revealed anti-inflammatory and anti-apoptotic effect in MPVEC-treated LPS. CircC3P1 overexpression reduced cell apoptosis and pro-inflammatory cytokines levels via down-regulating miR-21. CircC3P1 attenuated pro-inflammatory cytokine production and cell apoptosis in ALI induced by sepsis through modulating miR-21, indicating that circC3P1 is a promising therapeutic biomarker for sepsis-induced ALI.