Thymopentin ameliorates experimental colitis via inhibiting neutrophil extracellular traps

Background: 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).Methods: 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.Results: TP5 ameliorated weight loss (P < 0.001), disease activity index (DAI) (P = 0.05), colon shrinkage (P = 0.04), and elevated levels of tumor necrosis factor-alpha (TNF-alpha), interleukin (IL)-1 beta, IL-6, and neutrophils in the TNBS group. The TNBS group exhibited increased MPO, NE, CitH3, PAD4, dsDNA and MPO-DNA levels (all P < 0.001), which decreased after TP5 administration (P = 0.01, P < 0.001, P < 0.001, P < 0.001, P = 0.02, and P = 0.02 respectively). Tissue CitH3 levels were positively correlated with DAI and TNF-alpha levels (P < 0.05). Furthermore, phorbol 12-myristate 13-acetate-stimulated NET formation increased by 1.8-, 2.8-, and 2.3-fold in vitro in the control, TNBS + saline, and TNBS + TP5 groups, respectively. Neoseptin 3 significantly reversed the effect of TP5. RNA-seq revealed potential pathways underlying the effect of TP5.Conclusion: TP5 effectively ameliorated colitis by suppressing NETs in the experimental CD model.

Automated summary

This study found that thymopentin (TP5) has therapeutic effects in a mouse model of colitis that mimics Crohn's disease (CD), improving colitis by suppressing neutrophil extracellular traps (NETs).