Effects of nitric oxide on cholesterol metabolism in macrophages

The Inflamm-Aging Model Identifies Key Risk Factors in Atherosclerosis

Background: Atherosclerosis, one of the main threats to human life and health, is driven by abnormal inflammation (i.e., chronic inflammation or oxidative stress) during accelerated aging. Many studies have shown that inflamm-aging exerts a significant impact on the occurrence of atherosclerosis, particularly by inducing an immune homeostasis imbalance. However, the potential mechanism by which inflamm-aging induces atherosclerosis needs to be studied more thoroughly, and there is currently a lack of powerful prediction models.

Methods: First, an improved inflamm-aging prediction model was constructed by integrating aging, inflammation, and disease markers with the help of machine learning methods; then, inflamm-aging scores were calculated. In addition, the causal relationship between aging and disease was identified using Mendelian randomization. A series of risk factors were also identified by causal analysis, sensitivity analysis, and network analysis.

Results: Our results revealed an accelerated inflamm-aging pattern in atherosclerosis and suggested a causal relationship between inflamm-aging and atherosclerosis. Mechanisms involving inflammation, nutritional balance, vascular homeostasis, and oxidative stress were found to be driving factors of atherosclerosis in the context of inflamm-aging.

Conclusion: In summary, we developed a model integrating crucial risk factors in inflamm-aging and atherosclerosis. Our computation pipeline could be used to explore potential mechanisms of related diseases.

Inhibition of nitric oxide synthesis in human epicardial coronary arteries and stenoses in relation to serum lipid level

Administration of N(G)-monomethyl-L-arginine (LNMMA), an inhibitor of nitric oxide synthase, causes a reduction in epicardial coronary artery and stenosis diameter in patients with coronary artery disease, indicating that these diseased vessels produce nitric oxide. Elevations of low density lipoprotein cholesterol impair human endothelium-dependent relaxation. The relationship between serum lipid level and nitric oxide production by normal and atheromatous human epicardial coronary arteries in vivo is unknown. The effects of an intracoronary infusion of LNMMA (8 and 16 micromol/min) followed by intracoronary administration of 250 mcg nitroglycerin on non-stenotic proximal and distal coronary segments and coronary stenoses were studied in 11 patients with coronary artery disease and in 19 patients with 'normal arteriograms'. Coronary luminal diameter was measured by computerized quantitative angiography. In patients with cholesterol level> or = 220 mg/dl, no significant response to LNMMA was observed in the proximal segments in either those with 'normal angiograms' or those with coronary disease. In patients with cholesterol <220 mg/dl significant constriction (P<0.01) was observed in the proximal segments of patients with 'normal coronary angiograms' at both 8 and 16 micromol doses, but occurred only at the 16 micromol/min dose (P<0.01) in those with coronary disease. In conclusion the difference in vasomotor response to LNMMA in relation to cholesterol level is localised to the proximal coronary segments, and the response does not correlate with cholesterol or triglyceride level. This is therefore more likely to be an indirect effect of elevated cholesterol, e.g. undetected atheroma, than a direct effect on nitric oxide synthesis.