Neointimal thickening results from inflammation in association with vascular smooth muscle cell (VSMC) proliferation. We studied the role of perivascular adipose tissue (PVAT) on VSMC proliferation and intima-media thickening (IMT) in a rodent model of chronic inflammation.Methods:
The abdominal aorta and surrounding PVAT of tumour necrosis factor (TNF)-α-injected mice were examined 28 days after administration. Plasma and PVAT cytokines were measured with Milliplex™ assays. Inflammatory cells were examined with immunofluorescence. Expression of transforming growth factor (TGF)-β1, matrix metalloproteinase (MMP)-2, MMP-9 and MMP-12 was examined with immunohistochemistry, immunoblotting and zymography. IMT was determined. Cell proliferation and TGF-β1 mRNA levels were examined after treating VSMC with PVAT homogenates ± MMP-2 inhibitors (batimastat, ARP 100 or TIMP-2) and SB-431542, a selective inhibitor of the TGF-β-type 1 receptor.Results:
Significant increases in CD3, CD68, neutrophils, vascular cell adhesion molecule-1 and MMP-2 in PVAT, and TGF-β1 and IMT of the aorta of TNF-α-injected mice were observed. PVAT of TNF-α-injected mice significantly up-regulated TGF-β1 and increased cell proliferation in a dose-dependent manner and was attenuated by SB-431542, batimastat, ARP 100 and TIMP-2.Conclusions:
Our study shows that chronic PVAT inflammation leads to MMP-mediated increase in TGF-β1 and hence VSMC proliferation.