Kruppel-like factor 2+ CD4 T cells avert microbiota-induced intestinal inflammation

Area of Science:

• Immunology
• Microbiology
• Molecular Biology

Background:

• Commensal microbiota colonization requires robust peripheral immune tolerance.
• CD4 T cells play a critical role in maintaining gut homeostasis and preventing inflammation.

Purpose of the Study:

• To investigate the role of the transcriptional regulator Kruppel-like factor 2 (KLF2) in CD4 T cell function related to immune tolerance.
• To determine the necessity of KLF2+ CD4 cells in preventing microbiota-driven intestinal inflammation.

Main Methods:

• Analysis of KLF2 expression in CD4 T cells from lymphoid and intestinal tissues.
• Generation of mice with conditional KLF2 deficiency in T cells.
• Assessment of intestinal inflammation and rectal prolapse in KLF2-deficient mice.
• In vitro and in vivo functional assays of KLF2+ CD4 cells and IL-10 production.
• Evaluation of KLF2+ CD4 cell accumulation in Crohn's disease patients.

Main Results:

• CD4 T cells specific for commensal microbes are enriched for KLF2 expression.
• Conditional KLF2 deficiency in T cells leads to spontaneous intestinal inflammation and rectal prolapse.
• These inflammatory phenotypes are reversed by microbiota elimination or reconstitution with KLF2+ cells.
• Activated KLF2+ cells produce IL-10, which is essential for their suppressive function and protection against inflammation.
• Reduced KLF2+ CD4 cell numbers are observed in Crohn's disease patients.

Conclusions:

• KLF2 is essential for a specific subpopulation of CD4 T cells, identified as T regulatory type 1 (Tr1) cells, to maintain tolerance to commensal microbiota.
• KLF2+ CD4 T cells, through IL-10 production, are critical for preventing intestinal inflammation.
• Dysregulation of KLF2+ CD4 T cells may contribute to inflammatory conditions like Crohn's disease.