Vitamin D3 as adjuvant in the treatment of type 2 diabetes mellitus: modulation of genomic and biochemical instability

Measuring DNA modifications with the comet assay: a compendium of protocols

The comet assay is a versatile method to detect nuclear DNA damage in individual eukaryotic cells, from yeast to human. The types of damage detected encompass DNA strand breaks and alkali-labile sites (e.g., apurinic/apyrimidinic sites), alkylated and oxidized nucleobases, DNA-DNA crosslinks, UV-induced cyclobutane pyrimidine dimers and some chemically induced DNA adducts. Depending on the specimen type, there are important modifications to the comet assay protocol to avoid the formation of additional DNA damage during the processing of samples and to ensure sufficient sensitivity to detect differences in damage levels between sample groups. Various applications of the comet assay have been validated by research groups in academia, industry and regulatory agencies, and its strengths are highlighted by the adoption of the comet assay as an in vivo test for genotoxicity in animal organs by the Organisation for Economic Co-operation and Development. The present document includes a series of consensus protocols that describe the application of the comet assay to a wide variety of cell types, species and types of DNA damage, thereby demonstrating its versatility.

Protective role of vitamin D3 in a rat model of hyperthyroid-induced cardiomyopathy

Background and aim

Several studies have reported the cardioprotective effect of vitamin D. Thus, this study aimed to investigate the possible cardioprotective effect of vitamin D3 in hyperthyroid-induced cardiomyopathy rat model.

Experimental procedure

Rats were divided into 3 groups: control group; hyperthyroid group, rats were administrated l-thyroxine sodium daily for 4 weeks; and hyperthyroid + vitamin D3 treated group, rats were treated with l-thyroxine sodium for 4 weeks daily, and received the vitamin D3 for the same duration. After 4 weeks, electrocardiogram (ECG) was recorded. Then, blood samples were collected for biochemical analysis. After that, the final body weight was measured, and the rats were sacrificed. Finally, the hearts were excised, weighed and were prepared for histological examination by hematoxylin and eosin, and immunohistochemistry assessment of caspase-3 and proliferating cell nuclear antigen (PCNA).

Results

Hyperthyroid rats showed significant ECG changes, increased serum levels of cardiac biomarkers, fibroblast growth factor-23 (FGF23), malondialdehyde, antioxidant enzymes, tumor necrosis factor-alpha (TNF-α) and relative heart weight compared with the control rats. Vitamin D3 coadministration with l-thyroxine resulted in significant improvement in thyroid profile, ECG parameters, significant decrease of cardiac biomarkers, FGF23, malondialdehyde, TNF-α and relative heart weight, and significant decrease of the antioxidant enzymes compared with the hyperthyroid rats. The histological study was consistent with the biochemical results. Hyperthyroid rats showed upregulation of caspase-3 and PCNA in the myocardium compared with control group. Vitamin D3 treated rats showed downregulation of caspase-3 and PCNA.

Conclusion

Vitamin D3 provides cardioprotective effects in hyperthyroid rats.

The association between vitamin D3 and diabetes in both hyperuricemia and non-hyperuricemia populations

BACKGROUND

Previous studies have shown that hyperuricemia is involved in diabetes, obesity, hypertension, chronic kidney disease, and other diseases. At the same time, studies have shown that vitamin D3 levels in the body are linked to the onset of diabetes. However, there is currently no sufficient evidence to prove whether this connection is affected by the uric acid level. Therefore, we attempted to investigate the association between vitamin D3 content and the occurrence of diabetes in populations with different uric acid levels though the data of NHANES database from 2009 to 2018.

METHOD

Using the NHANES database, we performed a cross-sectional analysis. The participants were chosen based on stringent inclusion and exclusion requirements. This study finally included a total number of 16,735 individuals. Multivariate logistic regression analysis was used to investigate the association between vitamin D3 and diabetes mellitus in hyperuricemia and non-hyperuricemia patients after complete adjustment, and multivariate linear regression analysis was used to illustrate the association between vitamin D3 and uric acid.

RESULT

The results showed that the association between vitamin D3 and diabetes was weakened in hyperuricemia patients (OR 0.95 (0.92,0.98)). An independent association was discovered between vitamin D3 and uric acid (β -0.12 (-0.16, -0.07)) in all groups of population.

CONCLUSIONS

This study shows that vitamin D3 content is associated with the incidence of diabetes in people with high level of uric acid. This study offers a fresh perspective on the elements that influence the etiology of diabetes in hyperuricemia patients.

Vitamin D Deficiency in Elderly With Diabetes Mellitus Type 2: A Review

Diabetes mellitus type 2 (T2DM) is an emerging public health issue with high prevalence among older adults (>60 years old). Taking into consideration the great increase in the elderly population (approximately 7.5 billion worldwide), we can easily understand the impact of this chronic disease and its complications. On the other hand, vitamin D deficiency (VDD) is also a serious public health problem with significant impacts and multiple health effects. The correlation between DM and VDD has been suggested and established from many observational studies, reviews, and meta-analyses.

The literature in PubMed and Google Scholar was searched for relevant articles published up to October 2020. The keywords used were the following: vitamin D deficiency, elderly, and diabetes mellitus type 2. Among the 556 articles retrieved, 90 full texts were eligible and only 34 studies (12 retrospective studies, two prospective cohorts, three meta-analyses, seven cross-sectional studies, nine randomized control trials (RCTs), and one observational study) met the inclusion criteria for the review. The author's name, year of publication, country, type of study, and the number of patients were reported.

According to this review there is adequate evidence to support the correlation between VDD and T2DM in the elderly. The results from the RCTs are more conflicting and more studies are needed to confirm the impact of vitamin D deficiency (VD) supplementation on metabolic and lipid profile, oxidative stress, and the complications of T2DM in older patients. VDD is clearly related with severe retinopathy, diabetic peripheral neuropathy, and poor cognition performance, while there is consensus about the beneficial effect of VD on peripheral artery disease, foot ulceration prevention, and wound healing. On the other hand, there is controversy about the effect of VD supplementation on cardiovascular adverse events, endothelial function, and estimated glomerular filtration rate (eGFR). Finally, the association of VDD with fragility fractures and depression in the elderly with T2DM is currently insufficiently studied and remains controversial.

Modulating effect of vitamin D3 on the mutagenicity and carcinogenicity of doxorubicin in Drosophila melanogaster and in silico studies

Vitamin D3 (VD3) deficiency increases DNA damage, while supplementation may exert a pro-oxidant activity, prevent viral infections and formation of tumors. The aim of this study was to investigate the mutagenicity and carcinogenicity of VD3 alone or in combination with doxorubicin (DXR) using the Somatic Mutation and Recombination Test and the Epithelial Tumor Test, both in Drosophila melanogaster. For better understanding of the molecular interactions of VD3 and receptors, in silico analysis were performed with molecular docking associated with molecular dynamics. Findings revealed that VD3 alone did not increase the frequency of mutant spots, but reduced the frequency of mutant spots when co-administered with DXR. In addition, VD3 did not alter the recombinogenic effect of DXR in both ST and HB crosses. VD3 alone did not increase the total frequency of tumor, but significantly reduced the total frequency of tumor when co-administered with DXR. Molecular modeling and molecular dynamics between calcitriol and Ecdysone Receptor (EcR) showed a stable interaction, indicating the possibility of signal transduction between VD3 and EcR. In conclusion, under these experimental conditions, VD3 has modulatory effects on the mutagenicity and carcinogenicity induced by DXR in somatic cells of D. melanogaster and exhibited satisfactory interactions with the EcR.

Brazil nut prevents oxidative DNA damage in type 2 diabetes patients

The Brazil nut (Bertholletia excelsa, H.B.K.) originating from the Amazon region is one of the richest known sources of selenium (Se), a micronutrient that is essential and required for optimal physiological functioning. This mineral presents several health benefits, including improvement of the redox cellular status and maintenance of genomic stability. Knowing that type 2 diabetes mellitus (T2D) is strongly linked to oxidative stress and consequently DNA damage, the aim of this study was to assess the ex vivo antioxidative effects of Se through Brazil nut consumption and its potential in preventing oxidative DNA damage induced by H₂O₂. In order to accomplish this, the Comet assay (single-cell gel electrophoresis) was used to measure DNA damage in peripheral blood cells harvested before and after supplementation with Brazil nut. Comet assay was also applied ex vivo to measure the potential of Se to prevent oxidative damage to DNA induced by H₂O₂ in blood of type 2 diabetes patients collected before and after six months of supplementation with Brazil nut. We found that supplementation with Brazil nuts significantly increased serum Se levels. Furthermore, we observed a significant increase in fasting blood glucose after six months of consuming Brazil nuts; however, no significant effect was observed on the levels of glycated hemoglobin. Finally, we noticed that the cells were more resistant to H₂O₂-induced DNA damage after six months of supplementation with Brazil nut. Thus, consumption of Brazil nuts could decrease oxidative DNA damage in T2D patients, probably through the antioxidative effects of Se.

The effect of intramuscular megadose of vitamin D injections on E-selectin, CRP and biochemical parameters in vitamin D-deficient patients with type-2 diabetes mellitus: A randomized controlled trial

BACKGROUND AND AIMS

Inflammatory processes has been shown to be associated with the development of type 2 diabetes mellitus (T2DM) in which vitamin D supplementation might exert beneficial outcomes. We examined the effects of vitamin D supplement on inflammatory and cell adhesion molecule in patients with T2DM.

METHODS

This study consisted of 50 patients with T2DM who had vitamin D deficiency. Participants were randomized into two groups of 25 in which the intervention group received two intramuscular injections of a 200000-IU vitamin D supplement, one at week 0 and another at week 4. The concentrations of fasting blood glucose (FBG), lipid profiles, liver enzymes, E-selectin, C-reactive protein (CRP), calcium, phosphorus, serum 25-hydroxyvitamin D [25(OH)D] and anthropometric indices were obtained before and after 8 weeks.

RESULTS

Vitamin D resulted in significant reductions in CRP(P = 0.01) and gamma glutamyl transferase (GGT) levels(P = 0.03) and significant increases in 25(OH)D concentrations(P = 0.01) in the intervention group compared with the control. Within-group comparisons showed that FBG decreased significantly in the intervention group(P = 0.04). No significant changes were observed regarding within- and between-group comparisons of the other markers.

CONCLUSION

Vitamin D had beneficial effects on the levels of CRP, serum 25(OH)D and GGT among vitamin D deficient patients with T2DM. (http://www.irct.ir: IRCT2017100336539N1).