Vascular damage effect of circulating microparticles in patients with ACS is aggravated by type 2 diabetes

Abstract

As a common factor of both type 2 diabetes mellitus (T2DM) and acute coronary syndrome (ACS), circulating microparticles (MPs) may provide a link between these two diseases. The present study compared the content and function of MPs from patients with ACS with or without T2DM. MPs from healthy subjects (n=20), patients with ACS (n=24), patients with T2DM (n=20) and patients with combined ACS and T2DM (n=24) were obtained. After incubating rat thoracic tissue with MPs, the effect of MPs on endothelial‑dependent vasodilatation, expression of caveolin‑1 and endothelial nitric oxide synthase (eNOS), phosphorylation of eNOS at the S1177 and T495 sites and its association with heat shock protein 90 (Hsp90), and the generation of NO and superoxide anion (O_2˙‑) were determined. MP concentrations were higher in patients with T2DM and patients with ACS with or without T2DM than in healthy subjects. Moreover, MPs from patients with T2DM or ACS led to impairment in endothelial‑dependent vasodilatation, decreased expression of NO, as well as eNOS and its phosphorylation at Ser1177 and association with Hsp90, but increased eNOS phosphorylation at T495, caveolin‑1 expression and O_2˙‑ generation. These effects were strengthened by MPs from patients with ACS combined with T2DM. T2DM not only increased MP content but also resulted in greater vascular impairment effects in ACS. These results may provide novel insight into the treatment of patients with ACS and T2DM.

Keywords: acute coronary syndrome; circulating microparticles; endothelial dysfunction; vascular injury.

Figure 1.

MP levels are increased in patients with ACS with or without T2DM. MPs were increased in patients with ACS (4.63±0.86 mg/ml; n=24) and T2DM (4.21±0.77 mg/ml; n=20) compared with the Control (2.84±0.69 mg/ml; n=20). MP content was further increased in patients with both ACS and T2DM (5.54±0.73 mg/ml, n=24). Data are presented as the mean ± SD. *P<0.05 vs. Control; ^#P<0.05 vs. ACS+T2DM. MP, microparticle; ACS, acute coronary syndrome; T2DM, type 2 diabetes mellitus.

Figure 2.

MP origin detection. Compared with the Control (A and B), both EMPs [CD31(+)/CD41(−); yellow; 20.2±4.3%] and PMPs [(CD31(+)/CD41(+); green; 22.0±6.2%] increased in patients with ACS (C and D); EMPs 32.9±7.3%; PMPs 28.8±6.4%, n=24) and patients with T2DM (E and F); EMPs 33.9±4.2%; PMPs 29.9±5.1%, n=24); the EMP and PMP content was further increased in patients with ACS concurrent with T2DM (G and H); EMPs 37.8±5.8%; PMPs 37.0±3.6%; n=20). *P<0.05 vs. EMPs and PMPs; ^#P<0.05 vs. EMPs. MP, microparticle; EMP, endothelial-derived MP; PMP, platelet-derived MP; ACS, acute coronary syndrome; T2DM, type 2 diabetes mellitus.

Figure 3.

Effects of MPs from patients with ACS concurrent with T2DM on endothelium-dependent and -independent dilatation. (A) Compared with the Control, MPs (3 mg/ml) from patients with ACS or T2DM impaired endothelium-dependent dilatation stimulated by acetylcholine. MPs from patients with ACS concurrent with T2DM further decreased endothelium-dependent dilatation. (B) There were no differences in endothelium-independent vasodilator responses to sodium nitroprusside between MPs from Controls and patients with ACS and/or T2DM. Data are presented as the mean ± SD. *P<0.05 vs. the Control; ^#P<0.05 vs. ACS, T2DM. MP, microparticle; ACS, acute coronary syndrome; T2DM, type 2 diabetes mellitus.

Figure 4.

Effects of MPs from patients with ACS concurrent with T2DM on O₂˙- generation. (A) MPs from patients with ACS or T2DM increased O₂˙- production; this was enhanced by MPs from patients with ACS concurrent with T2DM but partly blocked by L-NAME (n=6). Magnification, ×200. (B) Relative fluorescence intensity. *P<0.05 vs. Blank and Control; ^#P<0.05 vs. ACS + T2DM. MP, microparticle; ACS, acute coronary syndrome; T2DM, type 2 diabetes mellitus; L-NAME, NG-nitro-L-arginine methyl ester.

Figure 5.

Effects of MPs from patients with ACS concurrent with T2DM on NO generation. (A) MPs from patients with ACS and/or T2DM decreased NO production. Magnification, ×200. (B) Relative fluorescence intensity. *P<0.05 vs. Blank, Control; ^#P<0.05 vs. ACS, T2DM. MP, microparticle; ACS, acute coronary syndrome; T2DM, type 2 diabetes mellitus.

Figure 6.

Effects of MPs from patients with ACS concurrent with T2DM on eNOS in the rat thoracic aorta. MPs from patients with ACS and/or T2DM (A) decreased eNOS and its phosphorylation at the Ser1177 site and (B) upregulated eNOS phosphorylation at T495 in the rat thoracic aorta. *P<0.05 vs. Blank and Control; ^#P<0.05 vs. ACS and T2DM. MP, microparticle; ACS, acute coronary syndrome; T2DM, type 2 diabetes mellitus; eNOS, endothelial nitric oxide synthase.

Figure 7.

Effects of MPs from patients with ACS concurrent with T2DM on caveolin-1 expression and the association of eNOS with Hsp90 in rat thoracic aorta. Compared with the Control, MPs from patients with ACS and/or T2DM (A) significantly increased caveolin-1 expression and (B) decreased the association between eNOS and Hsp90. *P<0.05 vs. Blank and Control; ^#P<0.05 vs. ACS and T2DM. MP, microparticle; ACS, acute coronary syndrome; T2DM, type 2 diabetes mellitus; eNOS, endothelial nitric oxide synthase; Hsp90, heat shock protein 90.