Introduction
Ulcerative colitis (UC) is a difficult-to-treat gastrointestinal disease, but its etiology and pathogenesis have not been clarified. An increasing number of studies have shown that the development and recurrence of UC are closely related to immune memory dysfunction. Our team's previous clinical and animal experiments have suggested that the treatment of UC with the Qingchang Wenzhong Decoction (QCWZD) is effective and can regulate intestinal mucosal immunity, but the exact mechanism is not yet clear. In this study, tissue-resident memory CD4+T cells (CD4+TRM cells) were used as the entry point to further investigate the immunological mechanism of the QCWZD for the treatment of UC.
Aims & Methods
To explore the regulatory effect of QCWZD on CD4+TRM cells in mice with DSS-induced colitis. This study aims to provide a new theoretical basis for the treatment of UC. Female C57BL/6 mice were randomly divided into control group, model group, QCWZD low-dose group, QCWZD medium-dose group, QCWZD high-dose group. Mice in control group were fed and watered freely throughout the whole process. Model group and doses group of QCWZD were used to replicate the UC model by freely drinking 2.5 % dextran sulfate sodium (DSS) (w/v) solution for 7 days. At the same time, model group was given deionized water gavage, and each dose group of QCWZD were given the corresponding concentration of QCWZD intervention for 1 week (Fig1 A). During this period, the mice were observed daily for general condition, weight measurement, detection of fecal occult blood, recording of fecal properties. The proportion of CD4+TRM cells was performed with flow cytometry and the expression levels of proteins in related signaling pathways was assessed.
Results
Our findings demonstrated that DSS intervention resulted in colon inflammation with clinical changes, while QCWZD appreciably reversed these phenomenon, as evidenced by retarded body weight loss, recovery of rectal bleeding and diarrhea, decreased disease activity index scores (Fig1 B-C). Moreover, the proportion of CD4+TRM cells in the lamina propria of mice in the DSS group were significantly higher than those in the Control group, while the CD4+TRM cells proportion was significantly reduced after the intervention with the QCWZD (Fig1 D-E). Mechanistically, the results from RT-qPCR analysis of the colonic tissue showed that QCWZD could significantly reduce the expression of glucose transporter protein Glut1/2/4 mRNA (Fig2 F-H), as well as the levels of key enzyme genes of glycolytic pathway (HK2, PKM2, G6PC, LDHA mRNA) (Fig2 I-J), suggesting that QCWZD had an inhibitory effect on glycolytic metabolism in colitis mice. We further found that the mRNA expressions of colon LepR and HIF-1α mRNA were significantly downregulated in QCWZD-treated mice (Fig2 M-N). These results demonstrated that QCWZD regulated the glycolytic metabolism of CD4+TRM cells by inhibiting the activity of LepR/HIF-1α signaling axis.
Conclusion
The results from our current study demonstrated that orally administrated QCWZD regulates CD4+TRM cells immune homeostasis through the modulation of glycolytic metabolism, and hold the therapeutic potential for immunology-targeted strategy in the treatment of UC.
References
[1] Zaiatz Bittencourt V, Jones F, Doherty G, et al. Targeting Immune Cell Metabolism in the Treatment of Inflammatory Bowel Disease. Inflamm Bowel Dis. 2021, 27(10):1684-1693.
[2] Gonzalez-Vivo M, Lund Tiirikainen MK, Andreu M, et al. Memory T Cell Subpopulations as Early Predictors of Remission to Vedolizumab in Ulcerative Colitis. Front Med (Lausanne). 2022, 9:837294.