Vascular calcification is a frequent cause of morbidity and mortality in patients with CKD and the general population. The common association between vascular calcification and osteoporosis suggests a link between bone and vascular disorders. Because microRNAs (miRs) are involved in the transdifferentiation of vascular smooth muscle cells into osteoblast-like cells, we investigated whether miRs implicated in osteoblast differentiation and bone formation are involved in vascular calcification. Different levels of uremia, hyperphosphatemia, and aortic calcification were induced by feeding nephrectomized rats a normal or high-phosphorus diet for 12 or 20 weeks, at which times the levels of eight miRs (miR-29b, miR-125, miR-133b, miR-135, miR-141, miR-200a, miR-204, and miR-211) in the aorta were analyzed. Compared with controls and uremic rats fed a normal diet, uremic rats fed a high-phosphorous diet had lower levels of miR-133b and miR-211 and higher levels of miR-29b that correlated respectively with greater expression of osteogenic RUNX2 and with lower expression of several inhibitors of osteoblastic differentiation. Uremia per se mildly reduced miR-133b levels only. Similar results were obtained in two in vitro models of vascular calcification (uremic serum and high–calcium and –phosphorus medium), and experiments using antagomirs and mimics to modify miR-29b, miR-133b, and miR-211 expression levels in these models confirmed that these miRs regulate the calcification process. We conclude that miR-29b, miR-133b, and miR-211 have direct roles in the vascular smooth muscle calcification induced by high phosphorus and may be new therapeutic targets in the management of vascular calcification.

Left ventricular hypertrophy (LVH), a common complication in chronic kidney disease (CKD), is associated with high cardiovascular mortality. The aim of this experimental study was to analyze the effect of different vitamin D receptor activators (VDRAs) on both LVH and myocardial fibrosis in chronic renal failure (CRF). Male Wistar rats with CRF, carried out by 7/8 nephrectomy, were treated intraperitoneally with equivalent doses of VDRAs (calcitriol, paricalcitol and alfacalcidol, 5 days per week) during 4 weeks. A placebo group (CRF + vehicle) and a Sham group with normal renal function served as controls. Biochemical, morphological, functional and molecular parameters associated with LVH were evaluated, as well as cardiac fibrosis, collagen I, transforming growth factor β1 (TGFβ1) and matrix metalloproteinase-1 (MMP1) expression. All VDRAs treatment prevented LVH, with values of cardiomyocyte size, LV wall and septum thickness and heart–body weight ratio similar to those observed in the Sham group. At molecular levels, all VDRAs attenuated atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) expression compared with CRF + vehicle. The phosphorylation of ERK1/2, a signal for activating growth, was stimulated in the CRF + vehicle group; VDRAs use prevented this activation. Paricalcitol was the only VDRA used that maintained in the normal range all parameters associated with myocardial fibrosis (total collagen, collagen I, TGFβ1 and MMP1). Our findings demonstrated that the three VDRAs used induced similar changes in bone metabolic parameters and LVH. In addition, paricalcitol was the only VDRA which showed a relevant beneficial effect in the reduction of myocardial fibrosis, a key factor in the myocardial dysfunction in CKD patients.

The main objective of this research was to define the association between common mitochondrial DNA (mtDNA) polymorphisms and mitochondrial transcription A gene (TFAM) variants and myocardial infarction (MI) in patients with atherosclerotic diseased vessels. Ten mitochondrial polymorphisms that defined the nine common European haplogroups were genotyped in 500 male patients with early onset MI (<55 years) and at least one atherosclerotic coronary vessel (angiographically confirmed), and 500 healthy controls. In addition, we searched for DNA variants in the coding region of the TFAM gene and compared patients and controls for the allele and genotype frequencies. Early onset MI was strongly associated with male gender and tobacco smoking in our population. MtDNA haplogroup H (defined by allele 7028 °C) was significantly more frequent in a first group of patients (n = 250) compared to controls (n = 300), and the association was confirmed in a second group of only smokers (250 patients and 200 controls). For total patients and controls, we obtained a p = 0.002 (OR = 1.50; 95% CI = 1.17-1.92) for H vs. the other haplogroups. We found four common TFAM polymorphisms, with allele/genotype frequencies that did not differ between patients and controls. In conclusion, mitochondrial haplogroup H was associated with early onset MI in male smokers. Our work supported a role for the mtDNA variation in the risk for atherosclerosis and ischemic associated events, likely due to differences in mitochondrial function and reactive oxygen production between the different haplogroups.