Obesity Modulates Intestinal Intraepithelial T Cell Persistence, CD103 and CCR9 Expression, and Outcome in Dextran...

Area of Science:

• Immunology
• Gastroenterology
• Obesity Research

Background:

• Obesity affects over 30% of the US population, leading to serious health issues.
• A compromised intestinal barrier is linked to type 2 diabetes and bacterial infections.
• Intraepithelial lymphocytes (IELs) are vital for maintaining intestinal health and immunity.

Purpose of the Study:

• To investigate the impact of obesity on the persistence and function of intestinal intraepithelial lymphocytes (IELs).
• To understand how obesity affects intestinal homeostasis and repair mechanisms.
• To explore the potential for weight loss to reverse obesity-induced immune dysfunction in the gut.

Main Methods:

• Mice were fed a high-fat diet to induce obesity.
• Changes in αβ and γδ IEL populations, their proliferation, and expression of CD103 and CCR9 were analyzed.
• Mice were subjected to dextran sulfate sodium-induced colitis to assess disease susceptibility.
• The effects of diet-induced weight loss on IELs and colitis outcome were evaluated.

Main Results:

• Obesity significantly reduced the persistence of both αβ and γδ IELs through distinct mechanisms.
• Obese mice showed decreased homeostatic proliferation of CD4+ and CD4+CD8+ αβ IELs.
• Both αβ and γδ IELs downregulated CD103 and CCR9 expression in obese mice.
• Obesity led to increased susceptibility to colitis, which was reversed by weight loss.
• Early-life obesity (post-weaning) had the most pronounced negative effects on IEL seeding.

Conclusions:

• Obesity profoundly impacts intestinal immunity by reducing IEL numbers and function, compromising the intestinal barrier.
• These immunomodulatory effects of obesity increase susceptibility to gut inflammation and disease.
• Diet-induced weight loss can restore IEL populations and improve intestinal health, highlighting the reversibility of obesity-related gut dysfunction.