Macrophage beta3 integrin suppresses hyperlipidemia-induced inflammation by modulating TNFalpha expression

Area of Science:

• Immunology
• Cardiovascular Biology
• Integrin Biology

Background:

• High-fat diets and hyperlipidemia are linked to chronic inflammatory diseases such as atherosclerosis.
• Integrins mediate inflammatory cell recruitment but are not typically considered diet-affected.
• Beta3 integrin deficiency in hyperlipidemic mice and beta3 integrin inhibitor use in humans are associated with increased mortality.

Purpose of the Study:

• To investigate the mechanisms underlying beta3 integrin-associated mortality and inflammation in hyperlipidemic conditions.
• To determine the role of diet, hyperlipidemia, and beta3 integrin in inflammatory processes.

Main Methods:

• Utilized apoE-null and LDL receptor-null hyperlipidemic mouse models.
• Conducted bone marrow transplantation experiments using beta3 integrin-deficient and replete cells.
• Analyzed TNFalpha expression in macrophages and assessed the effects of anti-TNFalpha antibody treatment.

Main Results:

• Diet-induced death in beta3 integrin-deficient mice was TNFalpha-dependent and mediated by bone marrow-derived cells.
• Transplantation of beta3-deficient marrow into beta3-replete recipients led to death on high-fat diets, while the reverse rescued mice.
• Beta3 integrin deficiency increased atherosclerosis and TNFalpha expression in macrophages, which was normalized by restoring beta3 integrin expression.

Conclusions:

• Macrophage beta3 integrin, via TNFalpha, suppresses inflammation associated with hyperlipidemia induced by high-fat feeding.
• These findings highlight a novel role for beta3 integrin in modulating diet-induced inflammatory responses and mortality.