Thymopentin ameliorates experimental colitis via inhibiting neutrophil extracellular traps

•Thymopentin ameliorates experimental colitis through inhibiting neutrophil extracellular traps (NETs) in TNBS- and DSS-induced mouse models.•Neoseptin 3 activates colonic NETs in vivo and reverses the protective effect of thymopentin on experimental colitis.•Integrated analysis of concomitant transcriptomic changes in the colon tissues of TNBS- and DSS-induced colitis mice reveals potential downstream pathways of thymopentin.•Neoseptin 3 might serve as a specific agonist of NETs in studying their pathological roles in the future. The long-term prognosis of Crohn’s disease (CD) remains unsatisfactory. Therefore, we assessed the therapeutic effect of thymopentin (TP5) in a mouse model of 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced colitis, which mimics CD, and analyzed its impact on neutrophil extracellular traps (NETs). NET markers, including myeloperoxidase (MPO), neutrophil elastase (NE), citrullinated histone H3 (CitH3), peptidyl arginine deiminase IV (PAD4), and double-stranded DNA (dsDNA) were assessed by immunostaining and enzyme-linked immunosorbent assay. NET formation was evaluated in vitro. Neoseptin 3, a specific NET agonist, was used to reverse the effect of TP5 on TNBS-induced colitis. The action mechanism of TP5 was investigated using RNA-seq. TP5 ameliorated weight loss (P