Mechanism of the Oxidative Stress Pathway Mediated by the Gut Microbiota Metabolite TMAO in the Pathogenesis of Diarrhea

doi:10.13560/j.cnki.biotech.bull.1985.2026-0149

Abstract

Abstract:

Objective To investigate the role of the gut microbiota-derived metabolite trimethylamine N-oxide (TMAO) in modulating oxidative stress pathways during diarrhea. Method Forty mice were randomly divided into a normal group, a model group, a TMAO inhibitor group, and a TMAO inhibitor + model group. The general status and fecal condition of the mice were evaluated, and histopathological changes in the colon and kidney tissues were observed. The choline trimethylamine-lyase (CutC), trimethylamine (TMA) and TMAO, sirtuin 3 (SIRT3) and superoxide dismutase 2 (SOD2), SOD, and reactive oxygen species (ROS) were measured. Additionally, changes in the cecal microbiota were analyzed. Result Compared with the normal group, the model group showed an extremely significant increase in fecal moisture content (P<0.001), the fecal moisture content in the TMAO inhibitor + model group mice was significantly reduced compared to the model group (P<0.05). Compared with the normal group, TMAO levels in the colon, kidney tissue, and serum were significantly elevated in the model group. In addition, compared with the normal group, both the model group and the TMAO inhibitor + model group exhibited decreased expression of SIRT3 and SOD2 and reduced SOD activity in the colon and kidney tissues. However, the expression of SIRT3 and SOD2 in the colon of the TMAO inhibitor + model group was significantly higher than that in the model group (P<0.05), and their expression in the kidney was also significantly increased compared with the model group (P<0.01). ROS levels in the colon tissue of the model group and the TMAO inhibitor + model group were significantly increased (P<0.01), while ROS levels in the kidney tissue were extremely significantly increased in the model group (P<0.001) and significantly increased in the TMAO inhibitor + model group (P<0.01). TMAO inhibitor treatment increased the species richness and diversity of the gut microbiota in model mice and remodeled the microbial community structure. Correlation analysis showed that TMAO was positively correlated with ROS and negatively correlated with SOD. In the model group, the characteristic genus Streptococcus was positively correlated with TMAO and ROS and negatively correlated with SOD, whereas in the TMAO inhibitor + model group, the characteristic genus Bilophila was negatively correlated with TMAO and ROS. Conclusion TMAO participates in the occurrence and development of diarrhea by inhibiting the expression of SIRT3 and SOD2, promoting ROS accumulation, and exacerbating oxidative stress.

Key words: diarrhea, gut microbiota, trimethylamine N-oxide, oxidative stress

FANG Le-yao, PENG Mai-jiao, HUI Hua-ying, TAN Zhou-jin. Mechanism of the Oxidative Stress Pathway Mediated by the Gut Microbiota Metabolite TMAO in the Pathogenesis of Diarrhea[J]. Biotechnology Bulletin, 2026, 42(11): 328-339.

Figures/Tables 7

Fig. 1 General characteristics of mice in each groupA: Fecal morphology and perianal condition. B: Body weight change rate. C: Fecal moisture content. D: Rectal temperature. Data are presented as mean ± standard deviation. CC: Control group; CM: Model group; CY: TMAO inhibitor group; CMY: TMAO inhibitor + model group, the same below

Fig. 2 Hematoxylin and eosin staining of colon and kidney tissuesA: Representative images of HE-stained colon sections (×200, ×400). B: Representative images of HE-stained kidney sections (×100, ×400)

Fig. 3 Changes in TMAO-related parameters in mice from different groupsA: CutC activity in colonic contents. B: CutC activity in cecal contents. C: Serum TMA level. D: TMAO content in the colon. E: TMAO content in the kidney. F: Serum TMAO level

Fig. 5 Changes in SOD activity and ROS levels in colon and kidney tissuesA: SOD activity in the colon. B: SOD activity in the kidney. C: ROS level in the colon. D: ROS level in the kidney

Fig. 6 Analysis of gut microbiota diversity in miceA: Chao1. B: Shannon. C: Observed species. D: Anosim analysis. E: PCoA analysis. F: NMDS analysis

Fig. 7 Random forest and receiver operating characteristic analysesA: Random forest plot at the genus level. B: ROC curve (CC vs CM). C: ROC curve (CC vs CMY). D: ROC curve (CM vs CMY)

Fig. 8 Correlation analysis between TMAO, oxidative stress-related indicators, and characteristic bacterial generaA: Heatmap of correlations between TMAO and oxidative stress indicators. B: Heatmap of correlations between colonic TMAO and oxidative stress indicators as well as characteristic bacterial genera. C: Heatmap of correlations between renal TMAO and oxidative stress indicators as well as characteristic bacterial genera. Red indicates positive correlation, blue indicates negative correlation, and the color gradient represents the strength of the correlation. *P<0.05, **P<0.01, ***P<0.001. Solid lines indicate significant correlation (P<0.05), dashed lines indicate non-significant correlation (P>0.05). The thickness of the lines represents the strength of the correlation

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