Circulating levels of linoleic acid and HDL-cholesterol are major determinants of 4-hydroxynonenal protein adducts in patients with heart failure

Abstract

Objective: Measurements of oxidative stress biomarkers in patients with heart failure (HF) have yielded controversial results. This study aimed at testing the hypothesis that circulating levels of the lipid peroxidation product 4-hydroxynonenal bound to thiol proteins (4HNE-P) are strongly associated with those of its potential precursors, namely n-6 polyunsaturated fatty acids (PUFA).

Methods and results: Circulating levels of 4HNE-P were evaluated by gas chromatography-mass spectrometry in 71 control subjects and 61 ambulatory symptomatic HF patients along with various other clinically- and biochemically-relevant parameters, including other oxidative stress markers, and total levels of fatty acids from all classes, which reflect both free and bound to cholesterol, phospholipids and triglycerides. All HF patients had severe systolic functional impairment despite receiving optimal evidence-based therapies. Compared to controls, HF patients displayed markedly lower circulating levels of HDL- and LDL-cholesterol, which are major PUFA carriers, as well as of PUFA of the n-6 series, specifically linoleic acid (LA; P=0.001). Circulating 4HNE-P in HF patients was similar to controls, albeit multiple regression analysis revealed that LA was the only factor that was significantly associated with circulating 4HNE-P in the entire population (R (2)=0.086; P=0.02). In HF patients only, 4HNE-P was even more strongly associated with LA (P=0.003) and HDL-cholesterol (p<0.0002). Our results demonstrate that 4HNE-P levels, expressed relative to HDL-cholesterol, increase as HDL-cholesterol plasma levels decrease in the HF group only.

Conclusion: Results from this study emphasize the importance of considering changes in lipids and lipoproteins in the interpretation of measurements of lipid peroxidation products. Further studies appear warranted to explore the possibility that HDL-cholesterol particles may be a carrier of 4HNE adducts.

Keywords: 4-Hydroxynnonenal; 4HNE, 4-hydroxynonenal; 4HNE-P, 4-hydroxynonenal bound to circulating thiol proteins; AA, arachidonic acid; CRP, C-reactive protein; DHA, docosahexanaenoic acid; EPA, eicosapentaenoic acid; GSH, reduced glutathione; GSSG, oxidized glutathione; HF, heart failure; HFC-MHI, heart failure clinic of the Montreal Heart Institute; HOMA-IR, homeostatic model assessment of insulin resistance; Heart failure patients; LA, linoleic acid; Linoleic acid; Lipid peroxidation; MDA, malondialdehyde; MPO, myeloperoxidase; NT-pro-BNP, N-terminal proB-type natriuretic peptide; NYHA, New York Heart Association; Oxidative stress; PUFA, polyunsaturated fatty acids; Polyunsaturated fatty acids; RAS, renin-angiotensin system; TBARS, thiobarbituric acid-reactive substances; TNF, tumor necrosis factor; eGFR, estimated glomerular filtration rate.

Graphical abstract

Fig. 1

Relationship between circulating levels of 4-hydroxynonenal bound to circulating thiol proteins (4HNE-P) and its precursor the n-6 polyunsaturated fatty acid linoleic acid in control and heart failure (HF) subjects. The dotted lines show the linear regression lines with 95% confidence intervals for all subjects in the control (C) and HF group. Control: Linoleic acid=1.2×4HNE-P+3691, P=0.38 (NS), HF: Linoleic acid=6.5×4HNE-P+2207, P=0.004.

Fig. 2

Relationship between circulating levels of linoleic acid and cholesterol fractions in the entire population. (A) Correlation between levels of linoleic acid (LA) and total cholesterol, LDL- and LDL-cholesterol in the entire population. The dotted lines show the regression lines: (i) total cholesterol: R²=0.595, P<0.0001, total cholesterol=0.79×LA+1.52; (ii) LDL-cholesterol: R²=0.455, P<0.0001, LDL-cholesterol=0.567×LA+0.583; and (iii) HDL: R²=0.076, P=0.001, HDL-cholesterol=0.120×LA+0.726. (B) Circulating levels of LA adjusted for age, gender and lipoproteins variables assessed by ANCOVA. Values are means±SD.

Fig. 3

Relationship between 4HNE-P and HDL-cholesterol expressed in absolute values or relative to HDL-cholesterol in heart failure (HF) and control (C) subjects. The lines in Fig. 2A show the linear regression lines for each group: (i) HF: R²=0.086, P=0.016, regression equation: HDL-cholesterol=0.0014×4HNE-P+0.651, and (ii) controls: R²=0.0149, P=0.768, regression equation: HDL-cholesterol=−0.00022×4HNE-P+1.51.