Lack of alpha CGRP exacerbates the development of atherosclerosis in ApoE-knockout mice

The effects of calcitonin gene-related peptide (CGRP) on atherosclerosis remain unclear. We used apolipoprotein E-deficient (ApoE^-/-) mice to generate double-knockout ApoE^-/-:CGRP^-/- mice lacking alpha CGRP. ApoE^-/-:CGRP^-/- mice exhibited larger atherosclerotic plaque areas, peritoneal macrophages with enhanced migration functions, and elevated levels of the inflammatory cytokine tumor necrosis factor (TNF)-⍺. Thus, we also explored whether inhibiting TNF-⍺ could improve atherosclerosis in ApoE^-/-:CGRP^-/- mice by administering etanercept intraperitoneally once a week (5 mg/kg) alongside a high-fat diet for 2 weeks. This treatment led to significant reductions in aortic root lesion size, atherosclerotic plaque area and macrophage migration in ApoE^-/-:CGRP^-/- mice compared with mice treated with human IgG (5 mg/kg). We further examined whether results observed in ApoE^-/-:CGRP^-/- mice could similarly be obtained by administering a humanized monoclonal CGRP antibody, galcanezumab, to ApoE^-/- mice. ApoE^-/- mice were subcutaneously administered galcanezumab at an initial dose of 50 mg/kg, followed by a dose of 30 mg/kg in the second week. Galcanezumab administration did not affect systolic blood pressure, serum lipid levels, or macrophage migration but led to a significant increase in lipid deposition at the aortic root. These findings suggest that alpha CGRP plays a critical role in inhibiting the progression of atherosclerosis.