Role of nicotinamide phosphoribosyltransferase in delaying smooth muscle cell senescence and protecting abdominal aortic aneurysm

Abstract

To investigate the protective effect of nicotinamide phosphoribosyltransferase (NAMPT) on abdominal aortic aneurysm by delaying the senescence of aortic vascular smooth muscle cells (VSMC). The primary VSMC cells from normal and patients with abdominal aortic aneurysm were cultured by tissue adherence method. Cells were divided into normal human-derived VSMC group (Ctrl-VSMC group), abdominal aortic aneurysm patient-derived VSMC group (AAA-VSMC group), and angiotensin II (Ang II) in vitro abdominal aortic aneurysm model group (Ang II-VSMC group, 100 nmol/L Ang II treated normal human-derived VSMC for 48 hours), Ang II + P7C3 group and AAA + P7C3 group after NAMPT agonist P7C3 intervention (adding 5 μmol/L P7C3 on the basis of Ang II-VSMC group and AAA-VSMC group, respectively). Immunofluorescence staining was used to identify VSMC; cell proliferation-associated antigen Ki67 staining was used to detect cell proliferation; senescence associated β-galactosidase (SA-β-gal) staining was used to detect cell senescence in each group; Western blotting was used to detect the protein expression levels of senescence-related proteins p21, p16 and NAMPT in each group. Compared with the Ctrl-VSMC group, the positive rate of SA-β-gal staining and the expression levels of senescence-related proteins p21 and p16 in the AAA-VSMC group and Ang II-VSMC group were significantly increased [SA-β-gal staining positive rate: (74.1±4.4)%, (68.6±5.5)% vs. (36.8±10.3)%, p21/GAPDH: 0.61±0.07, 0.51±0.03 vs. 0.31±0.03, p16/GAPDH: 0.77±0.03, 0.72±0.06 vs. 0.33±0.26, all P < 0.01]. However, the expression of NAMPT was significantly decreased (NAMPT/GAPDH: 0.88±0.07, 0.79±0.14 vs. 1.29±0.02, both P < 0.01). Compared with the Ang II-VSMC group, the positive rate of SA-β-gal staining and the expressions levels of senescence-related proteins p21 and p16 in the Ang II + P7C3 group were significantly lower [SA-β-gal staining positive rate: (49.1±3.2)% vs. (68.6±5.5)%, p21/GAPDH: 0.35±0.06 vs. 0.51±0.03, p16/GAPDH: 0.47±0.08 vs. 0.72±0.06, all P < 0.05], while the expression of NAMPT was significantly increased (NAMPT/GAPDH: 1.15±0.06 vs. 0.79±0.14, P < 0.01). Compared with the AAA-VSMC group, the positive rate of SA-β-gal staining and the expression levels of senescence-related proteins p21 and p16 in the AAA+P7C3 group were significantly lower [SA-β-gal staining positive rate: (54.1±6.0)% vs. (74.1±4.4)%, p21/GAPDH: 0.38±0.02 vs. 0.61±0.07, p16/GAPDH: 0.50±0.13 vs. 0.77±0.03, all P < 0.05], but the expression of NAMPT was significantly increased (NAMPT/GAPDH: 1.25±0.28 vs. 0.88±0.07, P < 0.01). NAMPT agonist P7C3 can delay the senescence of VSMC and play a protective role in abdominal aortic aneurysm.