Inflammatory bowel diseases (IBD) are chronic health problems of difficult management and treatment. Epidemiological studies indicate an inverse association between helminth infections and IBD, and experimental data confirm that helminth infections modulate the severity of experimental acute colitis in mice. However, the effects of helminth infections on chronic colitis, which is clinically more relevant, have been poorly explored. Herein, we investigated whether Strongyloides venezuelensis infection in BALB/c mice can ameliorate chronic colitis induced by the ingestion of water containing 2.5% Dextran Sodium Sulfate (DSS) over three seven-day treatment cycles, with an interval of fourteen days between cycles. Infected-only, DSS-exposed-only, and non-exposed/uninfected experimental groups served as controls for comparing the severity of colitis and intestinal inflammation among different groups. Our data showed that S. venezuelensis infection in mice with DSS-induced chronic colitis reduced clinical signs, attenuated colon shortening and inflammation, and prevented mucus ablation. The modulatory effect was accompanied by a low concentration of IFN-γ, high concentrations of TGF-β, IL-22, and IL-33 in the colon, and a significant increase of the percentage of CD4⁺CD25⁺Foxp3⁺ Treg cells in the mesenteric lymph node (MLN). In conclusion, S. venezuelensis infection can reduce the severity of DSS-induced chronic colitis in mice possibly through the stimulation of Treg cells and modulatory cytokines, and induction of mucosal repair mechanisms.

炎症性肠病（IBD）是难以管理和治疗的慢性健康问题。流行病学研究表明，蠕虫感染与 IBD 之间呈负相关，实验数据证实，蠕虫感染可调节小鼠实验性急性结肠炎的严重程度。然而，蠕虫感染对慢性结肠炎的影响（在临床上更相关）却很少被探索。在此，我们研究了 BALB/c 小鼠的委内瑞拉类圆线虫感染是否可以改善因在三个 7 天的治疗周期（周期间隔为 14 天）中摄入含有 2.5% 右旋糖酐硫酸钠 (DSS) 的水而引起的慢性结肠炎。仅感染、仅暴露 DSS 和未暴露/未感染的实验组作为对照，比较不同组之间结肠炎和肠道炎症的严重程度。我们的数据表明，患有 DSS 诱导的慢性结肠炎的小鼠中，委内瑞拉链球菌感染可减轻临床症状，减轻结肠缩短和炎症，并防止粘液消融。调节作用伴随着结肠中低浓度的 IFN-γ、高浓度的 TGF-β、IL-22 和 IL-33，以及结肠中 CD4 ⁺ CD25 ⁺ Foxp3 ⁺ Treg 细胞百分比的显着增加。肠系膜淋巴结（MLN）。总之，委内瑞拉链球菌感染可能通过刺激 Treg 细胞和调节性细胞因子以及诱导粘膜修复机制来减轻 DSS 诱导的小鼠慢性结肠炎的严重程度。