Omega-3 fatty acid prevents the development of heart failure by changing fatty acid composition in the heart

Abstract

Some clinical trials showed that omega-3 fatty acid (FA) reduced cardiovascular events, but it remains unknown whether omega-3 FA supplementation changes the composition of FAs and their metabolites in the heart and how the changes, if any, exert beneficial effects on cardiac structure and function. To clarify these issues, we supplied omega-3 FA to mice exposed to pressure overload, and examined cardiac structure and function by echocardiography and a proportion of FAs and their metabolites by gas chromatography and liquid chromatography-tandem mass spectrometry, respectively. Pressure overload induced cardiac hypertrophy and dysfunction, and reduced concentration of all FAs' components and increased free form arachidonic acid and its metabolites, precursors of pro-inflammatory mediators in the heart. Omega-3 FA supplementation increased both total and free form of eicosapentaenoic acid, a precursor of pro-resolution mediators and reduced free form arachidonic acid in the heart. Omega-3 FA supplementation suppressed expressions of pro-inflammatory cytokines and the infiltration of inflammatory cells into the heart and ameliorated cardiac dysfunction and fibrosis. These results suggest that omega-3 FA-induced changes of FAs composition in the heart have beneficial effects on cardiac function via regulating inflammation.

Figure 1

Omega-3 FA ameliorates cardiac dysfunction induced by pressure overload. Echocardiogram was performed to check cardiac morphology and function until 4 weeks (wks) after TAC operation. n = 6–12. *p < 0.05 compared between vehicle and Omega-3 EE groups. ^#p < 0.05 compared with vehicle group before TAC, ^†p < 0.05 compared with Omega-3 EE group before TAC. LVDd, left ventricular dimension at diastole. LVDs, left ventricular dimension at systole. Pwd, left ventricular posterior wall thickness at diastole. LVFS, left ventricular fractional shortening.

Figure 2

Omega-3 FA ameliorates cardiac hypertrophy induced by pressure overload. (a) Body weight (BW), heart weight (HW) and HW to BW ratio before and 4 weeks (wks) after TAC surgery with or without Omega-3 EE. n = 11–18. *p < 0.05. (b) Cardiomyocyte surface area (CSA) was evaluated by wheat germ agglutinin stain. n = 5–12. * p < 0.05. (c) Percent fibrosis in the heart at 4 weeks after operation was evaluated by Elastica van Gieson stain. n = 4–9. *p < 0.05.

Figure 3

Pressure overload and Omega-3 FA supplementation change the proportion of FAs in blood and heart. (a,b) Gas chromatography revealed FA concentration in blood (a) and heart (b) before (0), and 1 and 2 weeks (wks) after TAC surgery. n = 4–6. * p < 0.05 compared between vehicle and Omega-3 EE groups. ^#p < 0.05 compared with vehicle group before TAC, ^†p < 0.05 compared with Omega-3 EE group before TAC. PLA, Palmitic acid. STA, Stearic acid. POA, Palmitoleic acid. OLA, Oleic acid. LLA, Linoleic acid. ARA, Arachidonic acid. LNA, Linolenic acid. EPA, Eicosapentaenoic acid. DPA, Docosapentaenoic acid. DHA, Docosahexaenoic acid. SFA, saturated fatty acid. MUFA, mono-unsaturated fatty acid. PUFA, poly-unsaturated fatty acid.

Figure 4

ARA-, DHA- and EPA-derived metabolites in the heart treated with Omega-3 EE. Arachidonic acid (ARA) (a), docosahexaenoic acid (DHA) (b), and eicosapentaenoic acid (EPA) (c) -related metabolites in heart were examined before (0), and 1 and 2 weeks (wks) after TAC surgery using liquid chromatography-tandem mass spectrometry. n = 3–6. *p < 0.05 compared between vehicle and Omega-3 EE groups. ^#p < 0.05 compared with vehicle group before TAC, ^†p < 0.05 compared with Omega-3 EE group before TAC. PG, Prostaglandin. HETE, Hydroxyeicosatetraenoic acid. TX, Thromboxane. HDoHE, Hydroxydocosahexaenoic acid. PD, Protectin D. Rv, Resolvin. HEPE, Hydroxyeicosapentaenoic acid. (d) MDA concentration in the heart was evaluated using TBARS assay. n = 4–7.

Figure 5

Omega-3 EE decreases the number of inflammatory cells with reduction of cytokine expressions in the heart. (a–d) Heart sections were stained with anti-CD45 (a), anti-F4/80 (b), anti-iNOS (c), and anti-CD163 (d) antibodies and the number of each antibody-positive cells was evaluated before (0) and after TAC surgery. * p < 0.05. (e) The ratio of anti-CD163 positive cells to anti-iNOS positive cells was evaluated. * p < 0.05. (f) Quantitative RT-PCR showed expression levels of TNFα, MCP-1 and MIP-1α in the heart. n = 5–10. *p < 0.05. (g) Concentrations of TNFα and MIP-1α in blood were evaluated by ELISA. n = 4–7.