Leukocyte RhoA exchange factor Arhgef1 mediates vascular inflammation and atherosclerosis

Area of Science:

• Cardiovascular Biology
• Molecular Mechanisms of Disease
• Inflammation and Immunology

Background:

• The renin-angiotensin-aldosterone system is implicated in hypertension and atherosclerosis.
• Angiotensin II (Ang II) is a potential link between hypertension and atherosclerosis, acting as a vasoconstrictor and proinflammatory mediator.
• The precise role and molecular pathways of Ang II-induced inflammation in atherosclerosis remain unclear.

Purpose of the Study:

• To investigate the role of the RhoA GEF Arhgef1 in Ang II-induced inflammation.
• To elucidate the molecular mechanisms linking Ang II to atherosclerosis.
• To evaluate Arhgef1 as a potential therapeutic target for atherosclerosis.

Main Methods:

• Utilized a murine model to study the effects of Arhgef1 deletion on Ang II-induced inflammation and leukocyte recruitment.
• Employed mouse models lacking LDL receptor (LDLR) and Arhgef1 to assess atherosclerosis development on a high-fat diet.
• Performed bone marrow reconstitution experiments to confirm the role of Arhgef1 in leukocytes.

Main Results:

• Arhgef1 deletion prevented Ang II-induced integrin activation and leukocyte recruitment to the endothelium.
• Mice lacking both LDLR and Arhgef1 were protected from high-fat diet-induced atherosclerosis.
• Arhgef1 deficiency in bone marrow-derived cells conferred protection against atherosclerosis, while wild-type Arhgef1 exacerbated it.

Conclusions:

• Arhgef1 is essential for Ang II-induced inflammation and leukocyte recruitment, contributing to atherosclerosis development.
• Arhgef1 activation in leukocytes plays a causal role in atherosclerosis.
• Targeting Arhgef1 presents a promising therapeutic strategy for cardiovascular disease, particularly atherosclerosis.