Coadministration of VDR and RXR agonists synergistically alleviates atherosclerosis through inhibition of oxidative stress: An in vivo and in vitro study

BACKGROUND AND AIMS

Diabetes contributes to atherosclerosis partially through induction of oxidative stress. Both vitamin D receptor (VDR) and retinoid X receptor (RXR) agonists exhibit anti-atherogenic effects.

METHODS

We explored the effects of combination treatment with VDR and RXR agonists (represented by calcitriol and bexarotene, respectively) on atherosclerosis progression and the mechanisms involved, using a diabetes model of mice. The animals were intragastrically fed calcitriol (200 ng/kg, twice-a-week), bexarotene (10 mg/kg, once-daily) either alone or in combination for 12 weeks.

RESULTS

VDR and RXR agonists delayed atherosclerosis progression independent of serum lipid and glucose levels, and significantly reduced the protein expression of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase subunit gp91phox and nuclear factor-kappa B (NF-κB) subunit p65, as well as plasma biomarkers of oxidative stress and inflammation. Combination therapy alleviated atherosclerosis and inhibited indexes of oxidative stress and inflammation to a greater extent than either monotherapy. In the in vitro study, naturally occurring VDR ligand 1α,25-dihydroxyvitamin D3 (1,25[OH]2D3) and RXR ligand 9-cis retinoic acid (9-cis-RA), both significantly inhibited high-glucose-induced endothelial cell apoptosis. Co-administration of VDR and RXR ligands produced synergistic protection against endothelial apoptosis by antagonizing the protein kinase C /NADPH oxidase/reactive oxygen species pathway. The inhibitory effects of 9-cis-RA on oxidative stress was attenuated when VDR was downregulated by VDR siRNA; however, downregulation of RXR by RXR siRNA imposed no influence on the effects of 1,25(OH)2D3.

CONCLUSIONS

Combination treatment with VDR and RXR agonists synergistically alleviated diabetic atherosclerosis through inhibition of oxidative stress, and the preventive effects of RXR agonist may partially depend on VDR activation.

Analysis on Serum Trace Element Levels of Echinococciasis Patients in Garze Tibetan Autonomous Prefecture in Sichuan, China, 2011

In Garze Tibetan autonomous prefecture in Sichuan province, China, 41 echinococciasis patients who had received surgical treatment were recruited in the study, and 82 health persons who had lived in Garze for at least 10 years were selected as controls. The serum levels of Zn, Se and Cu of the cases and controls were detected. The results showed that most echinococciasis cases were distributed in Shiqu county (17.1%, 7/41), and only 1 case was distributed in Yajiang county (2.4%). The male to female ratio of the cases was 1:1.56. The echinococciasis patients were mainly aged 30-39 years (36.59%, 15/41). And, the cases aged 20-49 years accounted for 68.29% (28/41). Compared with health controls, the serum levels of Zn and Se of the cases significantly declined. However, the serum level of Cu of the cases had no significantly change. It was confirmed that the serum levels of Zn and Se were interrelated with the prevalence of echinococciasis.