Effects of vitamin D3 on glucose metabolism in patients with severe osteoarthritis: A randomized double-blind trial comparing daily 2000 with 800 IU vitamin D3

Sirt1 protects against intervertebral disc degeneration induced by 1,25-dihydroxyvitamin D insufficiency in mice by inhibiting the NF-κB inflammatory pathway

Background

It has been demonstrated that vitamin D deficiency is associated with an increased risk of patients developing lumbar disc herniation. However, intervertebral disc degeneration caused by active vitamin D deficiency has not been reported. Thus, the purpose of this study was to e investigate the role and mechanism of 1,25-dihydroxyvitamin D (1,25(OH)₂D) insufficiency in promoting intervertebral disc degeneration.

Methods

The phenotypes of intervertebral discs were compared in wild-type mice and mice with heterozygous deletion of 1α-hydroxylase [1α(OH)ase^+/-] at 8 mouths of age using iconography, histology and molecular biology. A mouse model that overexpressed Sirt1 in mesenchymal stem cells on a 1α(OH)ase^+/- background (Sirt1^Tg/1α(OH)ase^+/-) was generated by crossing Prx1-Sirt1 transgenic mice with 1α(OH)ase^+/- mice and comparing their intervertebral disc phenotypes with those of Sirt1^Tg, 1α(OH)ase^+/- and wild-type littermates at 8 months of age. A vitamin D receptor (VDR)-deficient cellular model was generated by knock-down of endogenous VDR using Ad-siVDR transfection into nucleus pulposus cells; VDR-deficient nucleus pulposus cells were then treated with or without resveratrol. The interactions between Sirt1 and acetylated p65, and p65 nuclear localization, were examined using co-immunoprecipitation, Western blots and immunofluorescence staining. VDR-deficient nucleus pulposus cells were also treated with 1,25(OH)₂D₃, or resveratrol or 1,25(OH)₂D₃ plus Ex527 (an inhibitor of Sirt1). Effects on Sirt1 expression, cell proliferation, cell senescence, extracellular matrix protein synthesis and degradation, nuclear factor-κB (NF-κB), and expression of inflammatory molecules, were examined, using immunofluorescence staining, Western blots and real-time RT-PCR.

Results

1,25(OH)₂D insufficiency accelerated intervertebral disc degeneration by reducing extracellular matrix protein synthesis and enhancing extracellular matrix protein degradation with reduced Sirt1 expression in nucleus pulposus tissues. Overexpression of Sirt1 in MSCs protected against 1,25(OH)₂D deficiency-induced intervertebral disc degeneration by decreasing acetylation and phosphorylation of p65 and inhibiting the NF-κB inflammatory pathway. VDR or resveratrol activated Sirt1 to deacetylate p65 and inhibit its nuclear translocation into nucleus pulposus cells. Knockdown of VDR decreased VDR expression and significantly reduced the proliferation and extracellular matrix protein synthesis of nucleus pulposus cells, significantly increased the senescence of nucleus pulposus cells and significantly downregulated Sirt1 expression, and upregulated matrix metallopeptidase 13 (MMP13), tumor necrosis factor-α (TNF-α) and interleukin 1β (IL-1β) expression; the ratios of acetylated and phosphorylated p65/p65 in nucleus pulposus cells were also increased. Treatment of nucleus pulposus cells with VDR reduction using 1,25(OH)₂D₃ or resveratrol partially rescued the degeneration phenotypes, by up-regulating Sirt1 expression and inhibiting NF-κB inflammatory pathway; these effects in nucleus pulposus cells were blocked by inhibition of Sirt1.

Conclusion

Results from this study indicate that the 1,25(OH)₂D/VDR pathway can prevent the degeneration of nucleus pulposus cells by inhibiting the NF-κB inflammatory pathway mediated by Sirt1.The Translational Potential of This Article: This study provides new insights into the use of 1,25(OH)₂D₃ to prevent and treat intervertebral disc degeneration caused by vitamin D deficiency.

The effect of vitamin D supplementation on glycemic status of elderly people with prediabetes: a 12-month open-label, randomized-controlled study

BACKGROUND

Data on the efficacy of vitamin D in improving the glycemic status of elderly people with prediabetes are scarce. This open-label, randomized-controlled trial investigated the effect of vitamin D supplementation on glycemic markers of Greek people with prediabetes aged 60 years or above, over 12 months.

RESEARCH DESIGN AND METHODS

Participants were randomized to a weekly vitamin D₃ dose of 25,000 IU (n = 45) or nothing (n = 45), on top of lifestyle measures. Anthropometric and glycemic markers were assessed at baseline, 3, 6, and 12 months.

RESULTS

Supplemented participants demonstrated a significant increase in 25(OH)D concentrations at 3,      6,      and 12 months     compared to baseline    . In the intervention group, fasting glucose was decreased at 6 months compared to baseline (96.12 ± 5.51 vs 103.40 ± 12.05 mg/dl, p < 0.01) and glycated hemoglobin was significantly lower at 6 and 12 months compared to baseline [5.82 ± 0.21% vs 5.87 ± 0.21%, p = 0.004 and 5.80 ± 0.23% vs 5.87 ± 0.21%, p < 0.001, respectively].

CONCLUSIONS

Vitamin D could be complementary to lifestyle change strategy for the management of prediabetes in the elderly.

CLINICAL TRIAL REGISTRATION

ISRCTN51643592.

Association of Gut Microbiome and Vitamin D Deficiency in Knee Osteoarthritis Patients: A Pilot Study

BACKGROUND

Few preclinical studies have shown that Knee osteoarthritis (KOA) is linked to gut microbiome dysbiosis and chronic inflammation. This pilot study was designed to look at the gut microbiome composition in KOA patients and normal individuals with or without vitamin D deficiency (VDD, serum vitamin D <30 ng/mL).

METHODS

This pilot study was conducted prospectively in 24 participants. The faecal samples of all the participants were taken for DNA extraction. The V3-V4 region of 16s rRNA was amplified, and the library was prepared and sequenced on the Illumina Miseq platform.

RESULTS

The mean (±SD) age was 45.5 (±10.2) years with no defined comorbidities. Of 447 total Operational Taxonomic Units (OTUs), a differential abundance of 16 nominally significant OTUs between the groups was observed. Linear discriminate analysis (LEfSe) revealed a significant difference in bacteria among the study groups. Pseudobutyrivibrio and Odoribacter were specific for VDD, while Parabacteroides, Butyricimonas and Gordonibacter were abundant in the KOA_VDD group, and Peptococcus, Intestimonas, Delftia and Oribacterium were abundant in the KOA group. About 80% of bacterial species were common among different groups and hence labelled as core bacterial species. However, the core microbiome of KOA and VDD groups were not seen in the KOA_VDD group, suggesting that these bacterial groups were affected by the interaction of the KOA and VDD factors.

CONCLUSION

Parabacteroides, Butyricimonas, Pseudobutyrivibrio, Odoribacter and Gordonibacter are the predominant bacteria in vitamin D deficient patients with or without KOA. Together these results indicate an association between the gut microbiome, vitamin D and knee osteoarthritis.