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

ABSTRACT

OBJECTIVE: To investigate the protective effect of nicotinamide phosphoribosyltransferase (NAMPT) on abdominal aortic aneurysm by delaying the senescence of aortic vascular smooth muscle cells (VSMC). METHODS: 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 ß-galactosidase (SA-ß-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. RESULTS: Compared with the Ctrl-VSMC group, the positive rate of SA-ß-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-ß-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-ß-gal staining and the expressions levels of senescence-related proteins p21 and p16 in the Ang II + P7C3 group were significantly lower [SA-ß-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-ß-gal staining and the expression levels of senescence-related proteins p21 and p16 in the AAA+P7C3 group were significantly lower [SA-ß-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). CONCLUSIONS: NAMPT agonist P7C3 can delay the senescence of VSMC and play a protective role in abdominal aortic aneurysm.