Elucidation of the Molecular Actions of 1,25 Dihydroxyvitamin D3 and Docosahexaenoic Acid that may Mediate Cardiovascular Health

Abstract

Omega 3 polyunsaturated fatty acids (PUFAs), composed of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), have been demonstrated to be beneficial in primary and secondary cardiovascular disease (CVD) prevention. The mechanism of action of PUFAs is not yet fully understood. Vitamin D, via its active form, 1,25-dihydroxyvitamin D3 (1,25 D3), functions through the vitamin D receptor (VDR), regulating serum calcium and phosphorus, and ultimately bone health. There is now evidence that 1,25 D3 may be cardioprotective as well, but the mechanism is also not fully understood. Evidence supports DHA as a weak VDR agonist, therefore there may be crosstalk between the two ligands and their known and yet to be discovered receptors. In the present research, we probed six genes as potential VDR targets, identified both through literature searches as well as their logical association with proposed 1,25 D3 and DHA cardioprotective mechanisms. Treating human embryonic kidney cells (HEK293) with 1,25 D3 and DHA independently, and in combination, we demonstrate changes of expression of three genes through quantitative real time polymerase chain reaction analysis (qRT-PCR). Nitric oxide synthase (NOS2), involved in the immune system nitric oxide burst, was significantly repressed by 1,25 D3 (fold effect 0.84, p value 0.04), DHA (fold effect 0.85, p value <0.01), with the greatest repression in the 1,25 D3 and DHA combination (fold effect 0.74, p value 0.01). Serpin peptidase inhibitor (SERPINE1), for which expression results in increased thrombus formation through tissue plasminogen activator inhibition, was repressed in the 1,25 D3 treatment group (fold effect 0.78, p value <0.01). Thrombomodulin (THBD), which indirectly activates protein C and increases thrombolysis, was repressed in the DHA (fold effect 0.69, p value <0.01) and combination 1,25 D3 and DHA groups (fold effect 0.75, p value 0.04). SERPINE1 and NOS2 repression is consistent with cardioprotective decreases in thrombus formation and immunomodulation, but THBD repression is not consistent with this hypothesis.