Abstract 16712: Inhibition of Four-and-a-Half LIM Domain Protein-2 Attenuates Atherogenesis in ApoE-/- Mice: Role of Immune T-Cells
Four-and-a-half LIM domain protein-2 (FHL2) is expressed in vascular cells. FHL2 negatively regulates endothelial cell survival and migration, but its role in atherogenesis is unknown.
Methods and results: We crossed FHL2 knockout (FHL2-/-) with apolipoprotein E-deficient (ApoE-/-) mice, and fed them a high-cholesterol, high-fat diet for 7 weeks. FHL2-/-ApoE-/- mice showed significantly higher plasma HDL-cholesterol levels. FHL2-/-ApoE-/- mice displayed significantly less atherosclerotic plaque formation, as assessed by oil red O staining, in the aortic sinus (0.14±0.02 vs. 0.29±0.04 mm2) and aorta (6.9±0.9 vs 10.3±1%) compared with ApoE-/- mice. This was associated with enhanced collagen (16±2 vs 8.6±3%) and smooth muscle cell (4.5±0.8 vs 1.8±0.5%) contents within the plaques of FHL2-/-ApoE-/- mice, as determined by Sirius red and alpha-actin staining. Decreased plaque formation in FHL2-/-ApoE-/- mice was associated with significantly reduced aortic ICAM-1 mRNA and VCAM-1 expression levels in the atherosclerotic plaques. Relative monocyte/macrophage content within the plaques, as determined by MOMA-2 immunostaining, and in spleens, as determined by FACS analysis, was equivalent in both animals groups. FACS analysis of T cells in spleens showed a significant increase in CD4+CD25+Foxp3+ regulatory T cell numbers in FHL2-/-ApoE-/- compared with ApoE-/- mice (19.5±1.6 vs. 16.2±2% of CD3+CD4+ cells, respectively). CD3+ T cell number was significantly higher within the atherosclerotic plaques of FHL2-/-ApoE-/- mice. In addition, ApoE-/- or FHL2-/-ApoE-/- mice were lethally irradiated and transplanted with bone marrow (BM) of ApoE-/- or FHL2-/-ApoE-/- mice. After 7 weeks of high-cholesterol diet, both chimeric mice groups showed an intermediate phenotype in terms of atherosclerotic plaque formation compared with ApoE-/- or FHL2-/-ApoE-/- mice. These results suggest that FHL2 deficiency both in the BM and in vascular cells is involved in the observed effects on atherogenesis.
Conclusion: Our findings suggest that FHL2 in BM-derived and vascular cells may play an important role in atherogenesis by promoting plaque formation, involving upregulation of adhesion molecule expression and suppression of regulatory T cells.
- © 2013 by American Heart Association, Inc.