TL1A regulates TCRγδ+ intraepithelial lymphocytes and gut microbial composition

Area of Science:

• Immunology
• Microbiology
• Gastroenterology

Background:

• Tumor necrosis factor-like ligand 1A (TL1A) is a proinflammatory cytokine found in the gut.
• Elevated TL1A levels are observed in inflammatory bowel disease (IBD) patients and models.
• The function of TL1A under normal physiological conditions remains largely unexplored.

Purpose of the Study:

• To investigate the impact of TL1A deficiency on the intestinal immune system and gut microbiota in a mouse model.
• To elucidate the role of TL1A in maintaining gut homeostasis and its potential involvement in metabolic processes.

Main Methods:

• Utilized TL1A knockout (KO) mice for comparative analysis with wild-type counterparts.
• Assessed intestinal immune cell populations, including TCRγδ(+) and CD8(+) T cells, and NKG2D expression.
• Analyzed gut microbial composition in caecum and ileum, alongside body weight and adipose tissue measurements.

Main Results:

• TL1A KO mice exhibited decreased intraepithelial TCRγδ(+) and CD8(+) T cells, and reduced NKG2D expression.
• Significant reductions in body weight, visceral adipose tissue, leptin, and CXCL1 were observed in TL1A KO mice.
• Gut microbiota analysis revealed diminished Clostridial cluster IV, altered Firmicutes/Bacteroidetes ratio, and reduced Lactobacillus spp. in TL1A KO mice.

Conclusions:

• TL1A deficiency profoundly affects gut microbial composition and the mucosal immune system, particularly TCRγδ(+) T cells.
• TL1A plays a role in the development of adipose tissue and metabolic regulation.
• These findings enhance understanding of TL1A's multifaceted roles, relevant to its therapeutic potential in IBD.