Capsaicin Reduces Obesity by Reducing Chronic Low-Grade Inflammation

Area of Science:

• Metabolism and Metabolic Diseases
• Immunology
• Gastroenterology

Background:

• Chronic low-grade inflammation (CLGI) is a key mechanism in obesity pathogenesis.
• Lipopolysaccharide (LPS) from Gram-negative bacteria drives CLGI.
• Capsaicin has shown potential in reducing LPS-producing bacteria.

Purpose of the Study:

• To investigate capsaicin's effect on CLGI and obesity using TRPV1-knockout mice and Caco-2 cells.
• To elucidate the mechanism by which capsaicin mediates weight loss.
• To assess capsaicin's impact on intestinal barrier function and inflammation.

Main Methods:

• Utilized TRPV1-knockout (TRPV1-/-) C57BL/6J mice and Caco-2 intestinal epithelial cells.
• Administered capsaicin intragastrically to mice on a high-fat diet.
• Measured body weight, food intake, blood lipids, blood glucose, LPS levels, TLR4, TNF-α, IL-6, and tight junction proteins (ZO-1, occludin).

Main Results:

• Capsaicin significantly reduced body weight, food intake, blood lipids, and glucose in high-fat diet-fed mice.
• Capsaicin decreased intestinal LPS levels by altering bacterial abundance and reduced TLR4, TNF-α, and IL-6 expression.
• Capsaicin upregulated ZO-1 and occludin, enhancing tight junction integrity, trans-endothelial electrical resistance, and restoring intestinal barrier function.

Conclusions:

• Capsaicin exhibits anti-obesity effects by mitigating CLGI through LPS reduction and improved intestinal barrier function.
• The mechanism involves downregulating TLR4-mediated inflammation and upregulating tight junction proteins ZO-1 and occludin.
• Capsaicin's ability to repair the intestinal barrier function presents a novel therapeutic avenue for obesity and related inflammatory conditions.