Effects of Cd8a Gene Knockout on Gut Microbiota and Liver Metabolism

Evaluate the effects of CD8⁺ T cell defects caused by Cd8a gene knockout on gut microbiota and hepatic metabolism, and preliminarily explore the underlying mechanisms.

The Cd8a gene was knocked out in mice to generate Cd8a knockout mice. Genotypes were identified using polymerase chain reaction (PCR) and agarose gel electrophoresis. Mice were divided into three groups: normal control, CD8⁺ T cell-deficient, and CD8⁺ T cell reinfusion, with six mice per group. CD8⁺ T cells from normal control mice were isolated via magnetic bead sorting and reinfused into CD8⁺ T cell-deficient mice via tail vein injection. Reinfusions were performed four times at 3-day intervals. Four weeks after the final reinfusion, fecal samples were collected, and DNA extracted for 16S rRNA gene sequencing analysis. Mouse livers were collected and analyzed using non-targeted metabolomics via liquid chromatography-tandem mass spectrometry (LC-MS/MS).

We found that CD8⁺ T cell deficiency-induced alterations in gut microbiota primarily affected the phyla Firmicutes, Bacteroidetes, Proteobacteria, and Actinobacteriota. Following CD8⁺ T cell depletion, the abundance of bacteria such as Catabacter, Vicinamibacter, Mesorhizobium, Catellatospora, and Stomatobaculum increased (p < 0.05); after CD8⁺ T cell reinfusion, the abundance of these bacteria showed a decreasing trend (p < 0.05). We also identified five major metabolic pathways in mouse liver that showed significant correlations with CD8⁺ T cell status.

CD8⁺ T cells exert a significant influence on hepatic metabolic responses and gut microbial community diversity.