To evaluate the clinical efficacy of Lianyang Decoction enema in the treatment of mild to moderate ulcerative colitis (UC), and to explore its mechanism of promoting mucosal healing based on the interleukin-37b/nuclear factor κB (IL-37b/NF-κB) axis.

A prospective, randomized, double-blind, placebo-controlled trial was conducted in this study. A total of 204 patients with mild to moderate UC admitted to Tongde Hospital of Zhejiang Province from March 2021 to December 2024 were selected as the research subjects and randomly divided into a control group of 102 cases (oral mesalazine+placebo enema) and an observation group of 102 cases (oral mesalazine+Lianyang Decoction enema), with a treatment course of 30 days. The following clinical indicators such as UC endoscopic severity index (UCEIS) score, TCM syndrome score, modified Mayo score for disease activity, fecal calprotectin (FC), intestinal mucosal barrier function [endotoxin (ET), D-lactic acid, diamine oxidase (DAO)] of the two groups of patients before and after treatment were observed and compared. Meanwhile, the levels of serum inflammatory factors [tumor necrosis factor-α (TNF-α), interleukin (IL)-6, IL-1β] and the levels of IL-37b and NF-κB p65 were detected by ELISA method, and the adverse reactions during the treatment were recorded.

After treatment, the UCEIS score, TCM syndrome score, modified Mayo score and FC level of both groups of patients were significantly decreased, and the reduction was significantly greater in the observation group than that in the control group (P<0.05). Meanwhile, the observation group was also superior to the control group in improving intestinal mucosal barrier function indicators (ET, D-lactic acid, DAO) and down-regulating serum inflammatory factors (TNF-α, IL-6, IL-1β) (P<0.05). In addition, after treatment, compared with the control group, the serum IL-37b level in the observation group was significantly upregulated, and the NF-κB p65 level was significantly downregulated (P<0.05). In terms of safety, there was no significant difference in the incidence of adverse reactions between the two groups (9.80% vs. 17.65%, P>0.05).

Enema with Lianyang Decoction combined with mesalazine can effectively promote intestinal mucosal healing in patients with mild to moderate ulcerative colitis. Its mechanism of action may be related to upregulating IL-37b and inhibiting the activity of the NF-κB signaling pathway, thereby reducing intestinal inflammatory responses and improving intestinal mucosal barrier function, and it has good safety.