An Association between MicroRNA-21 Expression and Vitamin D Deficiency in Coronary Artery Disease

Background: Atherosclerosis-related cardiovascular disease and osteoporosis (OP) occur concurrently and may share a common pathogenesis. Aberrant expression of miR-21 and vitamin D deficiency have been independently linked to the pathogenesis of atherosclerosis and OP. Objectives: To examine the relationship between miR-21 expression and vitamin D in aorta and bone in atherosclerotic disease. Methods: Aorta, internal mammary artery (IMA) and sternal bone samples were collected from patients undergoing coronary artery bypass graft (CABG) surgery. Bone density was measured by dual x-ray absorbtiometry (DXA). MiR-21 was quantified using a two-step reverse transcription-polymerase chain reaction. Results: Ten patients were included for analysis; 5 were vitamin D deficient (<25nmol/L). MiR-21 was expressed at a greater level in aorta compared with the IMA (p = 0.003), and sternal bone (p = 0.002). Expression of miR-21 between the IMA and bone was similar (p = 0.7). A positive correlation between the magnitude of difference (fold-difference) of miR-21 expression between aorta and IMA and CRP (correlation coefficient 0.9, p = 0.009) was found. Vitamin D deficient patients had greater expression of miR-21 in aorta compared with non-deficient patients (p = 0.03). Increasing CRP and vitamin D deficiency were independent predictors of miR-21 expression in aorta. The lower the difference in miR-21 expression between aorta and bone, the lower the bone density. Conclusion: In atherosclerosis, miR-21 is increased in the aorta and associated with vitamin D deficiency. Vitamin D deficiency may influence aberrant miR-21 expression in vasculature and bone contributing to the concurrent development of atherosclerosis and osteoporosis.