Linderae Radix extract attenuates ulcerative colitis by inhibiting the JAK/STAT signaling pathway.

BACKGROUND

Linderae Radix (LR), the dried root of Lindera aggregata (Sims) Kosterm., is a traditional Chinese herbal medicine that has been used for thousands of years for promoting Qi circulation, soothing the liver, and treating diarrhea and dysentery. Previous studies have found that ethanol extract of LR plays an anti-ulcerative colitis (UC) role by regulating Th17/ Treg balance. Water extract is the classic clinical application form of LR, but the effect of water extract of LR (LRWE) on UC and its underlying mechanism is still unclear.

PURPOSE

Purpose: UC is a gastrointestinal disease characterized by intestinal inflammation, mucosal injury, and fibrosis, and it is one of the high-risk factors for colon cancer. However, there is still a lack of remedies with satisfactory effects. This study aimed to investigate the efficacy and the potential mechanism of LRWE against UC.

METHODS

LRWE samples were prepared using a reflux extraction method. Colitis in mice was induced by administering 2.5 % DSS water solution to evaluate the therapeutic effect of LRWE by assessing disease activity score, colon length, and fecal morphology. H&E staining, TEM, Masson staining, and AB-PAS staining were applied to observe histopathological changes in the colon tissues. Differentially expressed genes in colon tissues were analyzed by transcriptomics. Cell apoptosis was detected by TUNEL staining. The expression of inflammatory factors such as IL-6 and IL-1β, as well as the expression of p-STAT1, p-JAK2, p-STAT3, Bax, and Bcl-2, were detected by immunofluorescence and immunohistochemistry. The expression of occludin, Bcl-2, Bax, and JAK/STAT signaling pathway-related vital proteins were quantified by Western blot (WB).

RESULTS

LRWE alleviated body weight loss, colon shortening, DAI scores, pathological changes, and ultrastructural features of colon tissue in mice with colitis. It also inhibited the increase of pro-inflammatory cytokines (such as TNF-α, IL-6, and IL-1β) and increased IL-10 levels. Additionally, it protected the intestinal barrier by upregulating the expression of Occludin and Mucin-2. Mechanistically, LRWE could inhibit the activation of JAK-STAT signaling pathway by reducing the protein expression of p-JAK2, p-STAT3, p-STAT1, Bcl2, and Bax, thus reducing the inflammatory responses and inhibiting cell apoptosis.

CONCLUSION

LRWE has a protective effect on DSS-induced UC. This effect is related to the inhibition of the JAK-STAT signaling pathway, the improvement of intestinal inflammation, and the reduction of intestinal epithelial cell apoptosis.