Polymorphisms of vitamin D receptor gene in Japanese patients with psoriasis vulgaris

Genetic Influence on Treatment Response in Psoriasis: New Insights into Personalized Medicine

Psoriasis is a chronic inflammatory disease with an established genetic background. The HLA-Cw*06 allele and different polymorphisms in genes involved in inflammatory responses and keratinocyte proliferation have been associated with the development of the disease. Despite the effectiveness and safety of psoriasis treatment, a significant percentage of patients still do not achieve adequate disease control. Pharmacogenetic and pharmacogenomic studies on how genetic variations affect drug efficacy and toxicity could provide important clues in this respect. This comprehensive review assessed the available evidence for the role that those different genetic variations may play in the response to psoriasis treatment. One hundred fourteen articles were included in this qualitative synthesis. VDR gene polymorphisms may influence the response to topical vitamin D analogs and phototherapy. Variations affecting the ABC transporter seem to play a role in methotrexate and cyclosporine outcomes. Several single-nucleotide polymorphisms affecting different genes are involved with anti-TNF-α response modulation (TNF-α, TNFRSF1A, TNFRSF1B, TNFAIP3, FCGR2A, FCGR3A, IL-17F, IL-17R, and IL-23R, among others) with conflicting results. HLA-Cw*06 has been the most extensively studied allele, although it has only been robustly related to the response to ustekinumab. However, further research is needed to firmly establish the usefulness of these genetic biomarkers in clinical practice.

Vitamin D Receptor Gene Polymorphism ApaI as a Predisposing Factor for Psoriasis and Its Relation With Serum Vitamin D Levels and Psoriasis Severity

BACKGROUND AND AIM

Psoriasis is a chronic, relapsing and inflammatory multisystemic disease with both genetic predisposition and autoimmune pathogenic traits. Several types of vitamin D receptor (VDR) polymorphisms have been investigated as a predisposing factor for psoriasis susceptibility with controversial results. However, the exact pathophysiological effect of the VDR gene on psoriasis susceptibility remains poorly understood. We aimed to determine whether VDR gene polymorphisms, specifically rs7975232 (ApaI), afford psoriasis susceptibility in a given community in Saudi Arabia. Also, to assess its possible relation with disease severity.

SUBJECTS AND METHODS

In a comparative case-control study comprising 53 psoriatic patients and 41 matched healthy controls, we measured serum ApaI levels, and the PCR-RFLEP technique detected ApaI genetic polymorphism (rs7975232) for both groups. Serum vitamin D level was measured in both groups.

RESULT

Our results revealed that A/A genotype of ApaI was significantly more predominant in patients than controls, while A/a genotype was more common in healthy subjects. Furthermore, A allele was significantly over-represented in the patients' group compared to the controls (P≤0.001). Serum vitamin D levels were significantly higher in mild psoriatic patients than in those with moderate and severe types (P=0.002). Mild psoriatic patients with a/a genotypes have higher vitamin D levels than severe patients with A/A genotypes and A/a moderate patients (P≤0.001).

CONCLUSION

Our data indicated clearly that VDR gene polymorphism, namely ApaI, is associated with psoriasis susceptibility. Furthermore, serum vitamin D level in psoriatic patients varies among different ApaI genotypes, where it is lowest in AA genotype.

Association of rs1544410 and rs7975232 Polymorphisms and Serum Vitamin D Levels with Psoriasis Susceptibility and Severity: A Case-Control Study in Egyptian Patients

Background

Vitamin D is a regulatory factor for skin immune functions through vitamin D receptor, which is expressed on many immune cells. Vitamin D receptor is located on chromosome 12q 13.11 and has many single nucleotide polymorphisms. Some of them were hypothesized to be associated with psoriasis. Psoriasis is a genetic disease that is greatly affected by environmental factors.

Methods

A total of 135 psoriasis patients and 114 healthy controls were recruited. Both had a measurement of serum vitamin D and two vitamin D receptor variants:, rs1544410: G > A (HGVS:NC_000012.12:g.47846052) and rs7975232: C > A (HGVS: NC_000012.12:g.47845054). We assessed the relationship between vitamin deficiency as well as the two gene polymorphisms with psoriasis susceptibility and severity.

Results

Serum vitamin D levels were not significantly different between cases and controls. However, a significant association between vitamin D levels and severity was observed. We attributed this to our finding that rs7975232 was more significantly polymorphic among cases than controls, while rs1544410 polymorphism did not show a significant difference among the 2 groups.

Conclusion

We did not find a significant difference in serum vitamin D levels between cases and controls. Yet, psoriasis severity was significantly associated with serum vitamin D levels. We attributed this to other findings that the vitamin D receptor rs7975232 gene is polymorphic in psoriasis patients. At the same time, rs1544410 was not significantly more polymorphic in psoriasis patients. Both genes’ polymorphisms were associated with severe psoriasis.

Nutrition and hair

Healthy hair results from a combination of good generalized health and mindful health care practices. Many nutritional deficiencies lead to poor hair health and include changes to hair structure, texture, and viability. Although the mechanisms by which individual nutrients contribute to hair growth and maintenance have yet to be fully resolved, there are a variety of risk factors that predispose an individual to a nutritional deficiency; age, malnutrition, malabsorption, and medication use are among the most common. A thorough history should be taken in a patient with a hair disturbance to identify risk factors for a nutritional deficiency, which will then guide directed laboratory testing and treatment.

Vitamin D receptor gene polymorphisms are associated with psoriasis susceptibility and the clinical response to calcipotriol in psoriatic patients

Psoriasis is a common genetic disease characterized by hyperproliferation and disordered maturation of keratinocytes. To date, many association studies between psoriasis and VDR gene have been conducted, but the results are controversial. Furthermore, vitamin D₃ analogue has anti-psoriatic activity; however, the clinical response is variable. This study was conducted to explore whether VDR gene polymorphisms are associated with psoriasis susceptibility and clinical response to calcipotriol in psoriatic patients. A total of 110 patients and 183 controls were genotyped for VDR gene polymorphisms rs2228570, rs731236, rs1544410 and rs7975232 by LDR method. SNP-based and haplotype-based association analyses were subsequently performed. Patients with PASI < 3 were treated with calcipotriol ointment monotherapy. After 6 weeks of therapy, the correlations between efficacy and the genotypes of each polymorphism were evaluated. The results showed that for rs7975232, allele A was significantly over-represented in psoriasis patients relative to controls (39.09% vs. 27.05%, OR (95% CI) = 1.731 (1.213-2.471)), and compared with the reference CC genotype, the following ORs were observed: AA genotype OR = 2.404 (95% CI: 1.085-5.328; P = .034) and GA genotype OR = 2.143 (95% CI: 1.283-3.579; P = .005). Haplotype analyses showed that the rs2228570/rs731236/rs1544410/rs7975232 CTGA was significantly over-represented in psoriasis patients compared with controls (OR (95% CI)=1.907 (1.132-3.214); P = .020). Among the patients with PASI < 3, the response rates to calcipotriol were significantly higher in patients with rs7975232 CC genotypes than in those with other genotypes (x²  = 9.172, P = .010). These data suggest that VDR polymorphisms are associated with psoriasis susceptibility and clinical response to calcipotriol in psoriatic patients.

Pooling analysis regarding the impact of human vitamin D receptor variants on the odds of psoriasis

BACKGROUND

The study aims at scientifically investigating the genetic effect of four polymorphisms (rs7975232, rs1544410, rs2228570, and rs731236) within the human Vitamin D Receptor (VDR) gene on the odds of psoriasis through an updated meta-analysis.

METHODS

We searched eight databases and screened the studies for pooling. Finally, a total of eighteen eligible case-control studies were included. BH (Benjamini & Hochberg) adjusted P-values of association (P_association) and odd ratios (ORs) with the corresponding 95% confidence intervals (CIs) were calculated under the allele, homozygote, heterozygote, dominant, recessive, and carrier models.

RESULTS

Compared with the negative controls, no statistically significant difference in the odds of psoriasis was detected for the cases under any genetic models (BH adjusted P_association > 0.05). We also performed subgroup meta-analyses by the source of controls, ethnicity, country, Hardy-Weinberg equilibrium, and genotyping method. Similar results were observed in most subgroup meta-analyses (BH adjusted P_association > 0.05). Besides, data of Begg's and Egger's tests excluded the significant publication bias; while the sensitivity analysis data further indicated the statistical reliability of our pooling results.

CONCLUSION

The currently available data fails to support a robust association between VDR rs7975232, rs1544410, rs2228570 and rs731236 polymorphisms and psoriasis susceptibility, which still required the support of more case-control studies.

Vitamin D receptor ApaI, TaqI, BsmI, and FokI polymorphisms and psoriasis susceptibility: an updated meta-analysis

BACKGROUND

Vitamin D is considered a regulator of the immune system, and its polymorphisms have been associated with psoriasis in some but not all reports.

AIM

To explore whether vitamin D receptor (VDR) polymorphisms are associated with susceptibility to psoriasis.

METHODS

Meta-analyses were conducted to determine the associations between psoriasis and the VDR ApaI, TaqI, BsmI and FokI polymorphisms in all participants, and stratified by ethnic group.

RESULTS

In total, 16 studies on VDR polymorphisms and psoriasis were included in this meta-analysis, which involved 2086 patients and 2182 controls. The meta-analysis indicated an association between psoriasis and the VDR TaqI TT genotype in Caucasian (OR = 1.29, 95% CI = 1.00-1.66, P < 0.05), but not in Asian (OR = 1.32, 95% CI = 0.89-1.96, P = 0.16) populations. However, no association was found between psoriasis and the VDR TaqI polymorphism using dominant, allele contrast or homozygous contrast models. No association was found between psoriasis and either the VDR ApaI, BsmI or FokI polymorphisms by meta-analyses of the allele contrast, recessive, or dominant models or homozygous contrast models in the overall, Caucasian or Asian populations.

CONCLUSION

This meta-analysis showed that polymorphisms in VDR ApaI, BsmI and FokI are not associated with psoriasis susceptibility in overall, Caucasian or Asian populations. However, the VDR TaqI polymorphism is associated with psoriasis susceptibility in Caucasian populations.

Challenge and perspective: the relevance of ultraviolet (UV) radiation and the vitamin D endocrine system (VDES) for psoriasis and other inflammatory skin diseases

During evolution, the ability of many organisms to synthesize vitamin D photochemically represented, and still represents, a major driving factor for the development of life on earth. In humans because not more than 10-20% of the requirement of vitamin D can be satisfied by the diet (under most living conditions in the US and Europe), the remaining 80-90% need to be photochemically synthesized in the skin through the action of solar or artificial ultraviolet-B (UV-B) radiation. The skin is a key organ of the human body's vitamin D endocrine system (VDES), representing both the site of vitamin D synthesis and a target tissue for biologically active vitamin D metabolites. Human keratinocytes contain the enzymatic machinery (CYP27B1) for the synthesis of the biologically most active natural vitamin D metabolite 1,25-dihydroxyvitamin D₃ (1,25(OH)₂D₃), representing an autonomous vitamin D₃ pathway. Cutaneous production of 1,25(OH)₂D₃ may mediate intracrine, autocrine and paracrine effects on keratinocytes and on neighboring cells. Many skin cells (including keratinocytes, sebocytes, fibroblasts, melanocytes, macrophages and other skin immune cells) express the vitamin D receptor (VDR), an absolute pre-requisite for exerting genomic effects of 1,25(OH)₂D₃ and analogs. The VDR is a member of the superfamily of trans-acting transcriptional regulatory factors, which also contains the steroid and thyroid hormone receptors as well as the retinoid-X receptors (RXR) and retinoic acid receptors (RAR). A large body of evidence, including cDNA microarray analyses of mRNAs, indicates that as many as 500-1000 genes may be controlled by VDR ligands that regulate a broad variety of cellular functions including growth, differentiation, and apoptosis. Clinical and laboratory investigations, including the observation that 1,25(OH)₂D₃ is very effective in inducing the terminal differentiation and in inhibiting the proliferation of cultured human keratinocytes have resulted in the use of 1,25(OH)₂D₃ and analogs for the treatment of psoriasis. Focussing on the UV-induced cutaneous synthesis of vitamin D, this review gives an update on the relevance of the VDES and of UV radiation for the management of psoriasis and other inflammatory skin diseases.

Oral vitamin D3 supplementation for chronic plaque psoriasis: a randomized, double-blind, placebo-controlled trial

PURPOSE

The management of psoriasis remains a challenge for dermatologist and patient. This study aimed to determine whether vitamin D₃ supplementation improves psoriasis compared to placebo.

MATERIALS AND METHODS

In a randomized, doubled-blind, placebo-controlled trial, 101 participants ≥18 years with psoriasis were grouped by severity and allocated to 100,000 International Units (IU) vitamin D₃/month for 12 months (200,000 IU at baseline; n = 67) or an identical placebo (n = 34). Psoriasis Area and Severity Index (PASI) and serum 25(OH)D concentrations were assessed at 3-monthly intervals. The primary outcome was the difference in PASI between groups over time. The relationship between 25(OH)D and PASI across the sample was also considered in a post hoc analysis.

RESULTS

PASI did not differ between groups at any time (group F(1, 104) = 0.48, p = .49; group*time F(4, 384) = 0.26, p = .90). However, 25(OH)D increased in both groups, rendering these findings inconclusive. A significant inverse relationship existed between PASI and 25(OH)D, with elevation of 25(OH)D by up to 125 nmol/L associated with mild decreases in PASI (estimated range of decrease 0-2.6; p = .002).

CONCLUSIONS

A direct benefit of vitamin D₃ supplementation for psoriasis could not be determined. However, these findings suggest a relationship between 25(OH)D and psoriasis severity, at least in some subgroups. Australian New Zealand Clinical Trials Registry #12611000648921.

The Role of Micronutrients in Alopecia Areata: A Review

Alopecia areata (AA) is a common, non-scarring form of hair loss caused by immune-mediated attack of the hair follicle. As with other immune-mediated diseases, a complex interplay between environment and genetics is thought to lead to the development of AA. Deficiency of micronutrients such as vitamins and minerals may represent a modifiable risk factor associated with development of AA. Given the role of these micronutrients in normal hair follicle development and in immune cell function, a growing number of investigations have sought to determine whether serum levels of these nutrients might differ in AA patients, and whether supplementation of these nutrients might represent a therapeutic option for AA. While current treatment often relies on invasive steroid injections or immunomodulating agents with potentially harmful side effects, therapy by micronutrient supplementation, whether as a primary modality or as adjunctive treatment, could offer a promising low-risk alternative. However, our review highlights a need for further research in this area, given that the current body of literature largely consists of small case-control studies and case reports, which preclude any definite conclusions for a role of micronutrients in AA. In this comprehensive review of the current literature, we found that serum vitamin D, zinc, and folate levels tend to be lower in patients with AA as compared to controls. Evidence is conflicting or insufficient to suggest differences in levels of iron, vitamin B12, copper, magnesium, or selenium. A small number of studies suggest that vitamin A levels may modify the disease. Though understanding of the role for micronutrients in AA is growing, definitive clinical recommendations such as routine serum level testing or therapeutic supplementation call for additional studies in larger populations and with a prospective design.

Estimated serum vitamin D status, vitamin D intake, and risk of incident alopecia areata among US women

Studies have identified increased prevalence of vitamin D deficiency in patients with alopecia areata (AA), an autoimmune disease characterized by hair loss, but none have prospectively examined vitamin D status and incident AA. In 55,929 women in the Nurses' Health Study (NHS), we prospectively evaluated the association between estimated vitamin D status, derived from a prediction model incorporating lifestyle determinants of serum vitamin D, and self-reported incident AA. We evaluated dietary, supplemental, and total vitamin D intake as additional exposures. Using Cox proportional hazards models, we calculated age-adjusted and multivariate hazard ratios (HR) to evaluate risk of AA. We identified 133 cases of AA over a follow-up of 12 years. The age-adjusted HR between top vs. bottom quartiles for serum vitamin D score was 0.94 (95 % CI 0.60-1.48) and the corresponding multivariate HR was 1.08 (95 % CI 0.68-1.73). There was no significant association between dietary, supplemental, or total vitamin D intake and incident AA. This study does not support a preventive role for vitamin D in the risk of developing AA.

Targeting the vitamin D endocrine system (VDES) for the management of inflammatory and malignant skin diseases: An historical view and outlook

Vitamin D represents one of the major driving factors for the development of life on earth and for human evolution. While up to 10-20 % of the human organism's requirements in vitamin D can be obtained by the diet (under most living conditions in the USA and Europe), approximately 90 % of all needed vitamin D has to be photosynthesized in the skin through the action of the sun (ultraviolet-B (UV-B)). The skin represents a key organ of the human body's vitamin D endocrine system (VDES), being both the site of vitamin D synthesis and a target tissue for biologically active vitamin D metabolites. It was shown that human keratinocytes possess the enzymatic machinery (CYP27B1) for the synthesis of the biologically most active natural vitamin D metabolite 1,25-dihydroxyvitamin D₃ (1,25(OH)₂D₃), representing an autonomous vitamin D₃ pathway. Cutaneous production of 1,25(OH)₂D₃ may exert intracrine, autocrine, and paracrine effects on keratinocytes and on neighboring cells. Many skin cells (including keratinocytes, sebocytes, fibroblasts, melanocytes, and skin immune cells) express the vitamin D receptor (VDR), an absolute pre-requisite for the mediation of genomic effects of 1,25(OH)₂D₃ and analogs. VDR belongs to the superfamily of trans-acting transcriptional regulatory factors, which includes the steroid and thyroid hormone receptors as well as the retinoid X receptors (RXR) and retinoic acid receptors (RAR). Numerous studies, including cDNA microarray analyses of messenger RNAs (mRNAs), indicate that as many as 500-1000 genes may be regulated by VDR ligands that control various cellular functions including growth, differentiation, and apoptosis. The observation that 1,25(OH)₂D₃ is extremely effective in inducing the terminal differentiation and in inhibiting the proliferation of cultured human keratinocytes has resulted in the use of vitamin D analogs for the treatment of psoriasis. This review gives an historical view and summarizes our present knowledge about the relevance of the VDES for the management of inflammatory and malignant skin diseases.

Vitamin D receptor polymorphism FokI is associated with spontaneous idiopathic preterm birth in an Israeli population

OBJECTIVE

The active form of vitamin D (1,25[OH]2D3) has been established to have potent anti-proliferative, immuno-modulatory, and anti-microbial action in addition to its effects on bone. The nuclear vitamin D receptor (VDR) is expressed in the placenta-decidua, regulating genes associated with implantation and implantation immuno-tolerance. If VDR polymorphisms regulate VDR functionality at the placenta-decidua interface, VDR genotypes may be involved in idiopathic preterm birth (PTB).

STUDY DESIGN

Maternal and fetal (umbilical cord) blood samples from 33 Jewish and Arab mothers with PTB of a singleton neonate were compared to 98 samples from Jewish and Arab maternal and fetal blood samples from full-term, uncomplicated singleton births. Maternal age and ethnicity were comparable between groups. PCR amplification/digestion identified the VDR SNPs: FokI, ApaI, TaqI, and BsmI.

RESULTS

Allele frequency for the FokI VDR in maternal blood samples from preterm births (but not umbilical cord samples) was significantly different (p=0.01) from that in maternal and umbilical cord blood samples from full-term singleton births, with an odds ratio for FokI carriers of 3.317 (95% CI, 1.143, 9.627) for preterm birth. The FokI VDR variant may therefore be a maternal risk trait for PTB among these women.

CONCLUSION

This study may support a future platform for the study of vitamin D during pregnancy and treatment of selective target populations with vitamin D and/or VDR "tissue-specific therapeutic intervention" for prevention of PTB.

A-1012G promoter polymorphism of vitamin D receptor gene is associated with psoriasis risk and lower allele-specific expression

Psoriasis is caused by a combination of genetic, immunologic, and environmental factors. The vitamin D receptor (VDR) is involved in antiproliferative and prodifferentiation pathways in keratinocytes and exerts immunosuppressive effects. We aimed to investigate possible associations between VDR polymorphisms and psoriasis susceptibility and to evaluate functional effects of potential psoriasis-associated polymorphisms. We genotyped 108 patients with psoriasis and 268 healthy controls at 5 VDR polymorphisms (A-1012G, FokI, BsmI, ApaI, and TaqI) by TaqMan allelic-discrimination real-time polymerase chain reaction. We found a significant increased overall risk of psoriasis for the VDR A-1012G promoter polymorphism (odds ratio [OR]=2.43, 95% confidence interval [CI]: 1.15-5.13; p=0.05). A significant higher frequency (p=0.035) of the A allele was found in psoriatic cases compared with controls. In a case-case analysis, a statistically significant association between A-1012G and family history emerged (p=0.033). Furthermore, a significant association of A-1012G risk genotypes with a lower expression of VDR mRNA emerged (p=0.0028). Our data show that VDR promoter A-1012G polymorphism is associated with psoriasis risk and suggest that this polymorphism may modulate psoriasis risk by affecting VDR expression.

Meta-analysis of vitamin D receptor polymorphisms and psoriasis risk

BACKGROUND

Vitamin D receptor (VDR) gene polymorphisms have been studied as candidate variants that affect psoriasis risk. However, results have been conflicting.

METHODS

We reviewed studies on VDR polymorphisms and psoriasis risk published to October 1, 2011, and quantitatively summarized associations of the most widely studied variants (FokI, TaqI, ApaI, BsmI) using meta-analysis. Associations were measured using random-effect odds ratios (ORs) combined with 95% confidence intervals (CIs).

RESULTS

Eleven eligible studies, encompassing 1106 cases and 1209 controls, were retrieved from electronic databases and included in this review. The results were heterogeneous, which may be partly explained by small sample bias, the phenomenon of winner's curse, and differences among populations. For FokI and ApaI polymorphisms, we did not find any evidence of association. A borderline allelic association was found for the BsmI B variant after exclusion of the earliest significant report (OR = 0.81, 95% CI 0.68-0.98; P = 0.04, inconsistency index [I2] = 12.7%). Among Caucasian subjects, the TaqI t allele was nominally associated with psoriasis risk (OR = 0.77, 95% CI 0.64-0.97; P = 0.012, I (2) = 0), with homozygous carriers (tt vs. TT, OR = 0.59, 95% CI 0.39-0.90; P = 0.01, I2 = 0) and recessive model (tt vs. Tt + TT, OR = 0.66, 95% CI 0.44-0.98; P = 0.04, I2 = 0) as protective factors. None of these associations persisted after adjustment for multiple comparisons. No publication bias was detected in this meta-analysis.

CONCLUSIONS

No genetic variant examined in the VDR gene showed a robust and reproducible association with risk for psoriasis. Any association that may exist is likely to be weak and potentially restricted to specific populations.

Vitamin D receptor ApaI, TaqI, BsmI, and FokI polymorphisms and psoriasis susceptibility: a meta-analysis

The aim of this study was to explore whether vitamin D receptor (VDR) polymorphisms confer susceptibility to psoriasis. Meta-analyses were conducted on the associations between the VDR ApaI, TaqI, BsmI, and FokI polymorphisms and psoriasis. Nine relevant studies on VDR polymorphisms and psoriasis were included in this meta-analysis, which involved 742 psoriasis patients and 715 controls. Meta-analysis indicated an association between the VDR ApaI A allele and psoriasis in Turkish studies (OR = 0.684, 95% CI = 0.475–0.985, p = 0.041). Meta-analysis indicated an association between the BsmI B allele and psoriasis in Asians (OR = 0.636, 95% CI = 0.411–0.984, p = 0.041), and showed a significant association between the FF and ff genotypes of the FokI polymorphism and psoriasis in all study subjects and in Turkish studies (OR = 2.028, 95% CI = 1.194–3.446, p = 0.009; OR = 3.582, 95% CI = 1.602–8.009, p = 0.002). This meta-analysis suggests that the VDR ApaI polymorphism confers susceptibility to psoriasis in the Turkish population. In addition, associations were found between the BsmI polymorphism and susceptibility to psoriasis in Asians and between the Fok I polymorphism and psoriasis in the Turkish population.

ApaI, BsmI, FokI and TaqI polymorphisms in the vitamin D receptor (VDR) gene and the risk of psoriasis: a meta-analysis

OBJECTIVES

To determine whether ApaI, BsmI, FokI or TaqI polymorphisms in vitamin D receptor (VDR) gene confer susceptibility to psoriasis. Methods All related association studies published before January 2012 were retrieved and eligible ones were included in our meta-analysis. For each of the four polymorphisms, we explored the significance of the associations for the allele contrast as well as the recessive and dominant models in overall samples, Caucasians and East Asians. Heterogeneity was identified by sensitivity analysis and publication bias was examined by funnel plot and Egger's test.

RESULTS

12 studies that met our selection criteria were included. For ApaI polymorphism, the dominant model for allele a in Caucasians produced a significant result [heterogeneity χ(2) = 3.46, P = 0.177, I(2) = 42.2%; OR(fixed-effect model) = 1.398 (1.011-1.934), z = 2.03, P = 0.043]. While in East Asians, pooling analysis under any genetic model acquired no-significant result. Significant heterogeneity was identified among East Asian studies and a Korean study accounted mostly for the heterogeneity detected. The heterogeneities were no longer statistically significant after removing this study, and the results of re-analyses in remaining studies have not been affected. Regarding TaqI polymorphism, the allele contrast discovered significant association between allele T and psoriasis susceptibility in Caucasians [heterogeneity χ(2) = 4.35, P = 0.226, I(2) = 31.1%; OR(fixed-effect model) = 1.287 (1.067-1.551), z = 2.64, P = 0.008]. As for the BsmI and FokI polymorphisms, allele contrast, recessive and dominant models produced non-significant results in either Caucasians or East Asians. The funnel plots and Egger's tests found no publication bias presenting in the studies analyzed.

CONCLUSIONS

This meta-analysis showed that ApaI, TaqI polymorphisms in VDR gene correlate with psoriasis in Caucasians.

Vitamin D analogs in the treatment of psoriasis: Where are we standing and where will we be going?

Vitamin D and analogs exert in the skin and other tissues potent effects on cellular differentiation and proliferation. Moreover, these compounds regulate apoptosis and exert immunomodulatory effects. During the last decades, it has convincingly been shown that vitamin D compounds are effective and safe in the topical treatment of psoriasis, where they nowadays represent a standard therapy. This review summarizes laboratory and clinical investigations related to the treatment of psoriasis with calcitriol or analogs. Additionally, promising concepts for the development of new vitamin D analogs are discussed. As a matter of fact, the final goal to create strong antiproliferative or antiinflammatory acting vitamin D analogs that exert only minor calcemic activity has not been reached until today. New agents that may activate selective vitamin D signalling pathways but may exert only negligible calcemic activity would declare a new era in dermatologic therapy and may also be effective in the topical or systemic treatment of various inflammatory skin diseases including atopic dermatitis and in various cutaneous malignancies, including lymphomas, squamous cell carcinoma or basal cell carcinoma.

How genetic variation affects patient response and outcome to therapy for psoriasis

Psoriasis is a prevalent chronic inflammatory condition that affects the skin. There are many treatments available for psoriasis but they are not universally effective and some have associated toxicities. Pharmacogenetics and pharmacogenomics explore the relationship between individual genetic variation and drug effect to allow targeted 'personalized' therapy for patients. There has been very limited pharmacogenetic research regarding psoriasis, with most limited to small retrospective case-control studies looking at single-nucleotide polymorphisms in candidate genes involved in drug pharmacokinetics. We review the pharmacogenetic investigation of treatments for psoriasis to date, including emerging pharmacogenomic studies. In addition, we discuss how such genetic data could be incorporated into routine clinical practice and future areas for development in this field.

Pharmacogenetics of psoriasis

Psoriasis is an inflammatory hyperproliferative skin disorder with a strong genetic predisposition. While many effective modalities are currently available for treating psoriasis, response to therapy is quite variable among patients. The genetic component underlying the response to pharmacotherapy in psoriasis is slowly beginning to emerge and represents a specialized field of genetics referred to as pharmacogenetics. The identification of genetic variants has the potential to improve the management of patient care by identifying which patients should avoid a specific drug and which patients should be administered a modified dose. A suitable approach in implementing such a strategy could potentially reduce medical costs and improve success of drug therapy. This article summarizes the clinical aspects of psoriasis, its genetic susceptibility and highlights the current landscape of genetic targets for psoriasis pharmacotherapy.

Toll-like receptors and antimicrobial peptides expressions of psoriasis: correlation with serum vitamin D level

To evaluate the association of Toll-like receptors (TLRs), antimicrobial peptides (AMPs) and vitamin D receptors (VDRs) in psoriasis, lesional (PP) and perilesional skin (PN) from psoriasis, atopic dermatitis (AD) patients and healthy controls (NN) were studied by immunohistochemistry. Compared with PN, AD and NN skin, dysregulated expression of TLRs, AMPs and VDR was detected in PP skin. Noteworthy, our results showed altered correlation between TLR2 and VDR expression in PP and PN skin. Human beta defensin 2 (HBD2) and cathelicidin (LL-37) expressions in the PP skin were higher in serum vitamin D sufficient (VDS) groups than serum vitamin D deficient (VDD) groups. Negative correlation was found between TLR2 and VDR expression in the PP skin of VDD groups. However, positive correlation was noted in the PP skin of VDS groups. Based on the present results, therapies targeting the activity of TLRs, AMPs and vitamin D, including modulation of the TLR-VDR pathways, might provide new therapeutic approaches to the psoriasis and other inflammatory skin diseases.

Vitamin D receptor gene polymorphisms are not associated with alopecia areata

BACKGROUND

It has been demonstrated that the vitamin D receptor (VDR) is strongly expressed in key structures of hair follicles, and a lack of VDR leads to alopecia. We investigated whether there was any association between VDR gene polymorphisms (BsmI, ApaI, and TaqI) and alopecia areata (AA).

METHODS

Thirty-two patients with AA and 27 healthy control subjects were genotyped using polymerase chain reaction and restriction fragment length polymorphism analysis.

RESULTS

In the patient group, the B and b allele frequencies were 53.1% and 46.9%, A and a allele frequencies were 70.3% and 29.7%, and T and t allele frequencies were 62.5% and 37.5%, respectively. In the control group, the corresponding values were 51.9% and 48.1%, 63.0% and 37.0%, and 77.8% and 22.2%, respectively. In the patient group, the BB, Bb, and bb genotype frequencies were 25.0%, 56.2%, and 18.8%, AA, Aa, and aa genotype frequencies were 43.8%, 53.1%, and 3.1%, and TT, Tt, and tt genotype frequencies were 37.5%, 50.0%, and 12.5%, respectively. In the control group, the corresponding values were 11.1%, 81.5%, and 7.4%, 29.6%, 66.7%, and 3.7%, and 63.0%, 29.6%, and 7.4%, respectively. None of the allele or genotype frequencies showed statistically significant differences between the patient and control groups.

CONCLUSION

These findings suggest that there is no relationship between VDR gene polymorphisms and AA.

Polymorphisms of vitamin D receptor gene in Turkish familial psoriasis patients

Psoriasis is characterized by hyperproliferation and abnormal differentiation of keratinocytes, and inflammation. 1,25-Dihydroxyvitamin D3, which is used for the treatment of psoriasis, binds to vitamin D receptor (VDR) and modulates gene transcription. We analyzed VDR gene FokI, ApaI and TaqI polymorphisms in 51 Turkish familial psoriasis patients (psoriasis vulgaris and psoriatic arthritis) and 100 healthy subjects, and evaluated the correlation between VDR genotypes and calcipotriol response. We found that the TT genotype was significantly more frequent in the patients than in the controls (51 vs. 35%: P < or = 0.05). The frequency of the T allele in patients was also significantly higher than that in the controls (73.5 vs. 59.5%: P < or = 0.025). In psoriatic arthritis patients, T allele frequency was even higher (91.7%: P < or = 0.05). With regard to response to calcipotriol treatment, in nonresponsive patients TT genotype and T allele frequencies were higher than they were in the controls (63.6 vs. 35%: P < or = 0.025, 81.8 vs. 59.5%: P < or = 0.01, respectively). In conclusion, we show that VDR gene TaqI polymorphism is associated with familial psoriasis in the Turkish population. We also demonstrate that VDR gene polymorphisms may play a role in partial resistance to calcipotriol therapy.

The vitamin D receptor gene FokI polymorphism: functional impact on the immune system

1Alpha,25-dihydroxyvitamin D3 (1,25(OH)2D3) has important effects on the growth and function of multiple cell types. These pleiotropic effects of 1,25(OH)2D3 are mediated through binding to the vitamin D receptor (VDR). Several polymorphisms of the human VDR gene have been identified, with the FokI polymorphism resulting in VDR proteins with different structures, a long f-VDR or a shorter F-VDR. The aim of this study was to investigate the functional consequences of the FokI polymorphism in immune cells. In transfection experiments, the presence of the shorter F-VDR resulted in higher NF-kappaB- and NFAT-driven transcription as well as higher IL-12p40 promoter-driven transcription. Marginal differences were observed for AP-1-driven transcription, and no differential effects were observed for transactivation of a classical vitamin D-responsive element. Concordantly, in human monocytes and dendritic cells with a homozygous short FF VDR genotype, expression of IL-12 (mRNA and protein) was higher than in cells with a long ff VDR genotype. Additionally, lymphocytes with a short FF VDR genotype proliferated more strongly in response to phytohemagglutinin. Together, these data provide the first evidence that the VDR FokI polymorphism affects immune cell behavior, with a more active immune system for the short F-VDR, thus possibly playing a role in immune-mediated diseases.

Vitamin D receptor gene polymorphisms, particularly the novel A-1012G promoter polymorphism, are associated with vitamin D3 responsiveness and non-familial susceptibility in psoriasis

Psoriasis is a genetically determined disease characterized by hyperproliferation and disordered maturation of the epidermis. Th1 lymphocytes are implicated in its pathogenesis. The vitamin D receptor (VDR) is a candidate modifying gene, having immunosuppressive effects and being involved in anti-proliferative and pro-differentiation pathways in keratinocytes. There is suggestive evidence that the A allele of the A-1012G polymorphism is associated with down-regulation of the Th1 response, via GATA-3. The F and T alleles of Fok1 and Taq1 have been associated with increased VDR activity. The present study aimed to test the hypothesis that the A allele of A-1012G is protective for occurrence and severity of psoriasis and enhances therapeutic response to vitamin D analogues and that these effects would be additive to those of Fok1 and Taq1. The study group comprised 206 psoriasis patients who had received topical calcipotriol treatment and 80 controls. There was no significant linkage disequilibrium between any pair of the three polymorphic sites (P=0.3-0.8). The A, F and T alleles were positively associated with calcipotriol response: AA genotype (compared to AG/GG), odds ratio (OR)=2.18 (P=0.04); TT, OR=1.97 (P=0.03); AAFF genotype combination, OR=4.11 (P=0.03); AATT, OR=5.64 (P=0.005); and FFTT, OR=3.22 (P=0.01). Comparing patients without, to patients with, a family history of psoriasis, the A allele was under represented (P=0.01) and the AAFF genotype combination even more so (compared to residual genotypes) (OR=0.24; P=0.005). AAFF was also under-represented in patients without a family history compared to controls (OR=0.31; P=0.04). There were no associations of family history with Fok1 and Taq1. There were no associations of severity of psoriasis with any polymorphism. In conclusion, the A-1012G, Fok1 and Taq1 VDR polymorphisms were associated with response to calcipotriol. A-1012G and Fok1 were associated with susceptibility to non-familial psoriasis.

Lack of association of the vitamin D receptor gene with Graves' disease in UK Caucasians

OBJECTIVE

Vitamin D modulates the immune system by suppressing the proliferation of activated T cells, with its actions being directed through the vitamin D receptor (VDR). A number of single nucleotide polymorphisms (SNPs) have been identified in the VDR gene, of which several have been associated with autoimmune diseases, including type 1 diabetes and Graves' disease (GD) in Japanese females. The aim of this study was to test for association of polymorphisms of the VDR gene in the genetic susceptibility to GD in UK Caucasians.

DESIGN

Target DNA for five previously published SNPs, four novel SNPs and one microsatellite marker was amplified by the polymerase chain reaction (PCR). Subsequent genotyping was performed using restriction fragment length polymorphism (RFLP) or microsatellite genotyping analysis, according to the type of VDR polymorphism.

PATIENTS

We obtained DNA from a case-control dataset consisting of 768 patients with GD and 864 control subjects. All patients and control subjects were Caucasians born in the UK, and all gave informed, written consent.

MEASUREMENTS

Frequencies of the alleles and genotypes of the ten VDR gene polymorphisms were compared between patients and control subjects using the chi2 test. Odds ratios were calculated using Woolf's method with Haldane's modification for small numbers and D prime (D') was calculated to assess the level of linkage disequilibrium (LD) between the ten polymorphisms.

RESULTS

No differences in allele or genotype frequencies were observed between GD cases and control subjects for any of the nine SNPs studied. The S allele of the PolyA microsatellite marker was slightly more frequent in GD cases when compared with control subjects (chi2= 4.364, P = 0.04). Strongest LD between markers was observed towards the 3' end of the VDR gene but there was no evidence of association with disease.

CONCLUSION

This is the largest and most comprehensive study of the VDR gene in GD to date and these data suggest that these polymorphisms of the VDR gene do not contribute to GD susceptibility in the UK.