Summary
There is a significant recruitment of leucocytes into aortas during atherogenesis.
L-selectin regulates leucocyte migration into secondary lymphoid and peripheral tissues
and was proposed to play a role in leucocyte homing into aortas. Here, we determine
the role of L-selectin in atherosclerosis. L-selectin-deficient Apoe
-/- (Sell
-/-
Apoe
-/-) mice had a 74% increase in plaque burden compared to Apoe
-/- mice fed a chow diet for 50 weeks. Elevated atherosclerosis was accompanied by increased
aortic leucocyte content, but a 50% reduction in aortic B cells despite elevated B
cell counts in the blood. Follicular B cells represented 65%, whereas B1a and regulatory
B cells (Breg) comprised 5% of aortic B cells. B1a and Breg cell subsets were reduced
in Sell
-/-
Apoe
-/- aortas with accompanied two-fold decrease in aortic T15 antibody and 1.2-fold decrease
of interleukin-10 (IL-10) levels. L-selectin was required for B1 cell homing to the
atherosclerotic aorta, as demonstrated by a 1.5-fold decrease in the migration of
Sell
-/-
Apoe
-/- vs Apoe
-/- cells. Notably, we found a 1.6-fold increase in CD68hi macrophages in Sell
-/-
Apoe
-/- compared to Apoe
-/- aortas, despite comparable blood monocyte numbers and L-selectin-dependent aortic
homing. L-selectin had no effect on neutrophil migration into aorta, but led to elevated
blood neutrophil numbers, suggesting a potential involvement of neutrophils in atherogenesis
of Sell
-/-
Apoe
-/- mice. Thus, L-selectin deficiency increases peripheral blood neutrophil and lymphocyte
numbers, decreases aortic B1a and Breg populations, T15 antibody and IL-10 levels,
and increases aortic macrophage content of Sell
-/-
Apoe
-/- mice. Altogether, these data provide evidence for an overall atheroprotective role
of L-selectin.
Keywords
Atherosclerosis - L-selectin - B cell subsets