Catalase but not vitamin D receptor gene polymorphisms are associated with nonsegmental vitiligo in Northwestern Mexicans

Vitamin D receptor gene polymorphisms role in COVID-19 severity: Results of a Mexican patients' cohort

Vitamin D status has been involved with coronavirus disease 19 (COVID-19) severity. This may be mediated by vitamin D metabolism regulatory genes. Of interest is the vitamin D receptor (VDR) gene, which has been previously associated with other inflammatory and respiratory diseases. In order to investigate the role of VDR gene polymorphisms in COVID-19 severity and outcome, a total of 292 COVID-19 patients were classified according to severity in moderate (n = 56), severe (n = 89) and critical (n = 147) and, according to outcome in survivor (n = 163) and deceased (n = 129), and analysed for FokI and TaqI VDR gene polymorphisms by polymerase chain reaction-based restriction enzyme digestion. The FokI and TaqI single nucleotide polymorphisms (SNPs) were not associated with COVID-19 severity or mortality individually but when analysed by haplotype, TC was associated with an increased risk of presenting critical COVID-19. Additionally, FokI CT genotype was more frequent in COVID-19 patients with hypertension, and T allele carriers presented higher aspartate aminotransferase levels. Our results suggest a relationship between VDR FokI and TaqI SNPs and COVID-19 severity in Mexican population. Although there are some previous reports of VDR polymorphisms in COVID-19, this represents the first report in Latin American population. Further studies on other populations are encouraged.

Vitamin D Receptor Gene Polymorphisms and Association with Vitiligo in Indonesian Population

Introduction

Vitiligo is an acquired depigmenting skin disorder due to the loss of melanocyte function in the epidermis and hair follicles. The pathogenesis of vitiligo is multifactorial, with genetics being a predisposing factor. Previous studies had varying results regarding whether or not polymorphisms of vitamin D receptor (VDR) gene are associated with the risk of vitiligo in specific populations. This study investigated the association between three frequently analyzed VDR gene polymorphisms (ApaI, BsmI, TaqI) and susceptibility to vitiligo in Indonesian population.

Methods

Thirty-four vitiligo patients and 34 age- and sex-matched healthy subjects aged ≥18 years old were recruited in the Dermatology and Venereology Outpatient Clinic of Dr. Hasan Sadikin General Hospital, Bandung, Indonesia. Genomic deoxyribonucleic acid (DNA) was extracted from the peripheral blood using a DNA isolation kit. VDR gene polymorphisms (ApaI, BsmI, and TaqI) were investigated using the polymerase chain reaction-restriction-fragment length polymorphism method. The differences of genotype distributions and allele frequencies were statistically compared between case and control groups using Chi-square test.

Results

VDR gene polymorphisms were identified in 68 participants, consisting of Aa (n = 14), aa (n = 20), Bb (n = 15), bb (n = 19), and TT (n = 34) genotypes in the case group. In the control group, Aa (n = 6), aa (n = 28), Bb (n = 17), bb (n = 17), and TT (n = 34) genotypes were identified. However, only subjects with ApaI Aa genotype polymorphism had a 3.267-fold increased risk of developing vitiligo.

Conclusion

This study showed that ApaI Aa genotype polymorphism of the VDR gene increases the risk of vitiligo in Indonesian population.

Evaluation of CAT Variants A-89T, C389T, and C419T in Patients with Vitiligo in the Saudi Population

Background and Objectives: Vitiligo is a chronic autoimmune and depigmentation disorder in humans that manifests as whitening lesions. Reactive oxygen species (ROS) are involved in cell damage. Catalase (CAT) is a well-known oxidative stress regulator and is primarily responsible for the catalytic decomposition of hydrogen peroxide into water and oxygen. Based on previous case-control and meta-analysis studies, we assessed the prevalence of three single-nucleotide polymorphisms (SNPs) of the CAT genes A-89T (rs7943316), C389T (rs769217) and C419T (rs11032709) in participants with vitiligo and healthy controls in the Saudi population. Materials and Methods: We recruited 152 participants with vitiligo and 159 healthy controls for A-89T, C389T, and C419T SNP genotyping studies using PCR and RFLP analysis. Additionally, we performed linkage disequilibrium and haplotype analyses between vitiligo cases and controls. Results: The rs7943316 and rs11032709 SNPs of the CAT genes showed a positive association with vitiligo for both heterozygous genotypes and dominant genetic models (TT + AT vs. AA in A-89T and TT + CT vs. CC in C389T), in the CAT gene. Linkage disequilibrium analysis revealed a moderate linkage between rs7943316 and rs11032709 SNPs in vitiligo cases and controls. Haplotype frequency estimation revealed a significant association (p = 0.003) among the three SNP alleles. Conclusions: The rs7943316 and rs11032709 SNPs of the CAT genes were strongly associated with susceptibility to vitiligo.

Association of rs4711998 of IL-17A, rs2275913 of IL-17A and rs763780 IL-17F gene polymorphisms with non-segmental vitiligo in a Mexican population

Vitiligo is the most common depigmenting disease characterized by achromic macules due to selective loss of melanocytes. The pathogenesis remains poorly elucidated, and multiple hypotheses exist regarding its pathogenesis. Evidence suggests that stress on melanocytes can result in activation of the immune system, and involvement of both activated cluster of differentiation (CD8+) cytotoxic and CD4+ T cells in the dysfunction, depigmentation, and apoptosis of melanocytes. Recent studies show that the interleukin 17 (IL-17) axis plays a central role in the pathogenesis of the disease. IL-17 is an important regulatory effector cytokine in this pathway. The aim of this study was to evaluate the association of IL-17A rs4711998 (-832A/G), IL-17A rs2275913 (-197G/A), and IL-17F rs763780 (7488A/G) with vitiligo in a Northeastern Mexican population. This was a case-control study and included 116 patients with vitiligo and 116 control subjects. Genotype characterization of IL-17A rs4711998 (-832A/G), IL-17A rs2275913 (-197G/A), and IL-17F rs763780 (7488A/G) was performed using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. A p ≤ 0.05 was considered significant. It was observed that the combination of the genotypes GG/GA for IL-17F rs763780 (7488A/G) was associated with an increased risk for the development of vitiligo (OR 2.0943, 95% Cl 1.2375-3.5445, p = 0.0056). Regarding IL-17A rs4711998 (-832A/G) and IL-17A rs2275913 (-197G/A) genotyping, no association with vitiligo development was found. In conclusion, the SNP rs763780 in the IL-17F gene appears to be a risk factor for vitiligo development in this Mexican population and it may be useful in future studies, especially for the development of new therapies.

Association between vitamin D receptor polymorphisms and vitiligo susceptibility: An updated meta-analysis

BACKGROUND

Vitamin D receptor (VDR) polymorphisms may play an important role in the vitiligo susceptibility. There have been many studies looking at the associations between VDR polymorphisms and vitiligo risk, but the conclusions are still up for debate.

AIM

This study aimed to determine whether polymorphisms in the VDR are associated to the susceptibility to vitiligo.

METHODS

Vitamin D receptor polymorphisms in vitiligo patients and controls were identified using PubMed/Medline and Embase databases. The relationships between the VDR ApaI, TaqI, BsmI, and TaqI polymorphisms and vitiligo were investigated using meta-analyses of all participants and Asian, Arab, European, and Latin American groups.

RESULTS

This meta-analysis included 13 papers with 2034 patients and 2771 controls. In all individuals, there was no link between vitiligo and the VDR ApaI A allele (OR = 0.889, 95% CI = 0.713-1.109, p = 0.298). However, in Asians (OR = 0.721, 95% CI = 0.553-0.940, p = 0.016) but not in Europeans or Arabs, there was a link between the VDR ApaI A allele and vitiligo. Utilizing recessive, dominant, and homozygote contrast models, a link between vitiligo and the VDR ApaI polymorphism was discovered in Asians. Meta-analysis of the VDR BsmI polymorphism showed a significant association between vitiligo and the B allele (OR = 0.812, 95% CI = 0.686-0.961, p = 0.015). In contrast, no connection between vitiligo and VDR polymorphisms was identified for TaqI and FokI polymorphisms.

CONCLUSION

In the Asian population, ApaI and BsmI polymorphisms in VDR have been correlated to vitiligo susceptibility. However, TaqI and FokI polymorphisms in VDR are not associated with vitiligo susceptibility in European, Asian, Arab, and Latin American populations.

Analysis of the heat shock protein 70 (HSP70) genetic variants in nonsegmental vitiligo patients

BACKGROUND

Vitiligo is an autoimmune disease that courses with skin depigmentation because of the destruction of melanocytes. Vitiliginous melanocyte is prone to damage because of oxidative stress which activates cellular stress response and the release of heat shock proteins such as HSP70 promoting immune activation against the melanocyte. Variants in HSP70 genes (HSPA) might alter their expression and thus modulate vitiligo susceptibility. Therefore, we sought to evaluate the role of the 5' untranslated region HSPA1A G/C (rs1043618) and the exonic HSPA1B A/G (rs1061581) and HSPA1L T/C (rs2227956) gene variants in nonsegmental vitiligo.

METHODS

A total of 200 nonsegmental vitiligo patients and 208 age/gender-matched healthy subjects were genotyped for rs1043618, rs1061581, and rs2227956 variants by PCR-RFLP.

RESULTS

Variants rs1043618 and rs1061581 were not associated with vitiligo susceptibility. On the other hand, the rs2227956 C allele and TC genotype were associated with protection against vitiligo. A similar effect was observed for the GAC haplotype. Any of the aforementioned HSP70 gene variants were associated with the clinical characteristics of vitiligo.

CONCLUSION

Our findings suggest that the HSPA1L rs2227956 gene variant might influence the susceptibility to vitiligo. Being the first study of HSP70 gene variants in vitiligo, further research is encouraged to corroborate these results.

Clinical Significance of Serum Oxidative Stress Markers to Assess Disease Activity and Severity in Patients With Non-Segmental Vitiligo

Non-segmental vitiligo (NSV) is a chronic autoimmune disease characterized by progressive depigmentation of the skin. Oxidative stress (OS) has been proposed as one among the main principal causes in the development and establishment of a sustained autoimmune state in patients with NSV. However, the disease-associated OS biomarkers in clinical practice are not well studied. In this study, we found significantly reduced antioxidant enzymes [catalase (CAT) and superoxide dismutase (SOD)], total antioxidant capacity (TAC), and increased levels of lipid oxidation product malondialdehyde (MDA) and oxidative DNA damage byproduct [8-hydroxy-2-deoxyguanosine (8-OHdG)] in serum of NSV patients compared with healthy controls (HC). Serum TAC, MDA, and 8-OHdG levels were correlated with disease activity in all patients with NSV and much lower in patients receiving conventional treatment in the past 1 year compared to that without treatment. In addition, both serum MDA and 8-OHdG levels were significantly correlated with CXCL10 expression in patients with NSV. And the serum TAC, MDA, and 8-OHdG levels were also correlated with affected body surface area and Vitiligo Area Scoring Index score in patients with NSV. This study demonstrates dysregulated OS status in patients with NSV and provides the evidence that the serum TAC, MDA, and 8-OHdG have a capacity to indicate the activity and severity in patients with NSV.

Decreased circulatory levels of Vitamin D in Vitiligo: a meta-analysis

BACKGROUND

The serum Vitamin D status in patients with vitiligo is ambiguous when compared to controls. A systematic review and updated meta-analysis were conducted to evaluate the association between Vitamin D and vitiligo.

METHODS

Relevant studies were identified by searching PubMed and other databases. The random effects model was used to obtain standardized mean differences and pooled correlation coefficients. Meta-regression and sub-group analyses were conducted to explore heterogeneity. The presence of publication bias and the study robustness were tested using funnel plot and sensitivity analyses, respectively.

RESULTS

This meta-analysis finally included 31 studies. Compared with controls, vitiligo patients showed significantly decreased serum Vitamin D levels (standardized mean difference = -1.03; p < 0.0001). The sub-group analysis showed that vitiligo patients with indoor/urban work had a significantly lower Vitamin D level when compared to their outdoor/rural counterparts (standardized mean differences = -0.45; p = 0.03). The sensitivity analysis indicated that no single study had a significant influence on the overall outcome, suggesting the robustness of this meta-analysis.

STUDY LIMITATIONS

Varied sample sizes and heterogeneous study populations from different countries are the limitations of this study. However, the between-study heterogeneity has been addressed by the random-effects model with meta-regression and sensitivity analyses.

CONCLUSIONS

This meta-analysis showed significantly decreased Vitamin D level in vitiligo, and its association with indoor/outdoor type of work of vitiligo patients. This study highlights the need to assess Vitamin D status for improving its level in vitiligo.

Skin Pigmentation Abnormalities and Their Possible Relationship with Skin Aging

Skin disorders showing abnormal pigmentation are often difficult to manage because of their uncertain etiology or pathogenesis. Abnormal pigmentation is a common symptom accompanying aging skin. The association between skin aging and skin pigmentation abnormalities can be attributed to certain inherited disorders characterized by premature aging and abnormal pigmentation in the skin and some therapeutic modalities effective for both. Several molecular mechanisms, including oxidative stress, mitochondrial DNA mutations, DNA damage, telomere shortening, hormonal changes, and autophagy impairment, have been identified as involved in skin aging. Although each of these skin aging-related mechanisms are interconnected, this review examined the role of each mechanism in skin hyperpigmentation or hypopigmentation to propose the possible association between skin aging and pigmentation abnormalities.

Impact of vitamin D receptor gene polymorphisms on vitiligo susceptibility and clinical features in a Southeastern European Caucasian population

An association of vitamin D receptor (VDR) polymorphisms and vitiligo has been suggested. However, previous studies have reported contradictory results while including limited data among Caucasians. The aim of this single-center study was to evaluate the effect of three common VDR gene polymorphisms (FokI, TaqI and BsmI) on suscep-tibility and clinical aspects of vitiligo in a Southeastern European Caucasian population. A total of 110 unrelated vitiligo cases and 509 general population controls were enrolled from October 2018 to November 2019. Genomic DNA was extracted from whole blood after de-identification and anonymization of the samples and genotyped for the selected VDR polymorphisms by the qPCR (melting curve analysis). Subgroup analysis by clinical features among subsets of patients indicated that, compared to subjects with the FokI TT genotype or T allele, carriers of the FokI CC genotype or C allele exhibited significantly decreased risk of developing vitiligo before the age of 30 [TT vs. CC: odds ratio (OR)=0.286, 95% confidence interval (CI): 0.083-0.984, P=0.041; T vs. C: OR=0.545, 95% CI: 0.313-0.948, P=0.031]. Intra-patient analysis also revealed that, compared to T allele, the presence of TaqI C allele was adversely associated with the incidence of concurrent leukotrichia (T vs. C: OR=1.874, 95% CI: 1.018-3.451, P=0.042). Comparisons between the case and control groups showed no evidence to support an association between susceptibility to vitiligo and the VDR BsmI, TaqI, and FokI polymorphisms in this cohort. Thus, the studied VDR polymorphisms might indirectly impact the clinical course and treatment decision-making despite their lack of association with vitiligo per se. Further research with larger sample sizes, especially across Caucasian individuals, should be performed to confirm these findings.