Total sulfane sulfur bioavailability reflects ethnic and gender disparities in cardiovascular disease

Abstract

Hydrogen sulfide (H₂S) has emerged as an important physiological and pathophysiological signaling molecule in the cardiovascular system influencing vascular tone, cytoprotective responses, redox reactions, vascular adaptation, and mitochondrial respiration. However, bioavailable levels of H₂S in its various biochemical metabolite forms during clinical cardiovascular disease remain poorly understood. We performed a case-controlled study to quantify and compare the bioavailability of various biochemical forms of H₂S in patients with and without cardiovascular disease (CVD). In our study, we used the reverse-phase high performance liquid chromatography monobromobimane assay to analytically measure bioavailable pools of H₂S. Single nucleotide polymorphisms (SNPs) were also identified using DNA Pyrosequencing. We found that plasma acid labile sulfide levels were significantly reduced in Caucasian females with CVD compared with those without the disease. Conversely, plasma bound sulfane sulfur levels were significantly reduced in Caucasian males with CVD compared with those without the disease. Surprisingly, gender differences of H₂S bioavailability were not observed in African Americans, although H₂S bioavailability was significantly lower overall in this ethnic group compared to Caucasians. We also performed SNP analysis of H₂S synthesizing enzymes and found a significant increase in cystathionine gamma-lyase (CTH) 1364 G-T allele frequency in patients with CVD compared to controls. Lastly, plasma H₂S bioavailability was found to be predictive for cardiovascular disease in Caucasian subjects as determined by receiver operator characteristic analysis. These findings reveal that plasma H₂S bioavailability could be considered a biomarker for CVD in an ethnic and gender manner. Cystathionine gamma-lyase 1346 G-T SNP might also contribute to the risk of cardiovascular disease development.

Keywords: Coronary artery disease; HPLC; Hydrogen sulfide; Monobromobimane; Peripheral artery disease.

Fig. 1

Study organization flow chart. A total of 324 patients were used for analysis, including 209 males and 115 females. This subject population was subsequently diagnosed with or without CAD or PAD after cardiac catheterization. CAD indicates coronary artery disease; PAD, peripheral artery disease.

Fig. 2

Plasma sulfide bioavailability by ethnicity. Total sulfide, acid labile pools, and bound sulfide in total subject populations (combined), Caucasian and African American subjects respectively with any form of CVD. CVD indicates cardiovascular disease. Control Caucasian vs African Americans ### p=0.0001; #p=0.0028; ##p=0.0326.

Fig. 3

Plasma sulfide pools in Women by ethnicity. Total sulfide, acid labile pools, and bound sulfide levels of Plasma have been displayed in female subjects with and without any CVD. CVD indicates cardiovascular disease. Control Caucasian vs African Americans ###p=0.0031; #p=0.06555.

Fig. 4

Plasma sulfide pools in Men by ethnicity. Total sulfide, acid labile pools, and bound sulfide levels of Plasma have been displayed in male subjects with and without any CVD. CVD indicates cardiovascular disease. Control Caucasian vs African Americans ###p=0.0338; #p=0.03085.p = .0338; #p = .03085.

Fig. 5

Sulfide bioavailability in CAD and PAD subjects. Plasma total, acid labile and bound sulfane sulfide pools in a combined or total subject population, Caucasian and African American subjects with either CAD or PAD. CAD indicates Coronary arterial disease; PAD, Peripheral arterial disease. Control Caucasian vs African Americans ###p=0.0001; #p=0.0028; ##p=0.0326.

Fig. 6

Receiver-operating characteristic analysis (ROC) in subjects with CVD. ROC curves with area under the curve of Caucasian population A. total sulfide levels in females B. total sulfide levels in males C. Acid labile pools in females D. Bound sulfane sulfur in males and E. total sulfide. F. Total sulfide levels in African American CVD patients. CVD indicates cardiovascular disease.