Vitamin D analogs in the treatment of psoriasis

Role of Anti-Inflammatory Diet and Fecal Microbiota Transplant in Psoriatic Arthritis

PURPOSE

Psoriatic arthritis (PsA) is a chronic inflammatory condition with complex and heterogenous manifestations. Although a myriad of treatment options including biologic medications are available to alleviate symptoms and slow disease progression, there is currently no cure for this condition. There has been a recent emergence of understanding about the relationship between the gut microbiome and immune-mediated inflammatory diseases. This has generated interest in the potential role of dietary interventions, particularly anti-inflammatory diets, and fecal microbiota transplant (FMT) as novel therapeutic approaches. The purpose of this narrative review is to examine the role of an anti-inflammatory diet and FMT in turn and whether their combination may offer alternate approaches for the management of PsA.

METHODS

Our non-systematic narrative review was informed by a literature search using PubMed and Google Scholar using the terms anti-inflammatory diet, FMT, nutrition supplements, and PsA. Preclinical studies and non-English language articles were excluded when synthesizing the narrative review.

FINDINGS

Current randomized controlled trials (RCTs) and observational evidence suggest that a hypocaloric diet or Mediterranean diet can help achieve weight loss among PsA patients who are overweight or obese, which in turn reduces inflammation and improves disease activity. However, there is no strong data to support the beneficial effects of intermittent fasting, vitamin supplements, turmeric supplements, probiotics, or omega-3 fatty acid supplements in PsA. Current evidence on the use of FMT in PsA is limited as only one small RCT has been conducted which did not demonstrate efficacy for improving clinical symptoms.

IMPLICATIONS

Clinicians can consider recommending hypocaloric or Mediterranean diets as an adjunct to standard management of PsA, possibly under the guidance of a dietician. Further research is needed to explore the beneficial effects of the synergistic role of combining an anti-inflammatory diet with FMT in PsA.

From Traditional Medicine to Advanced Therapeutics: The Renaissance of Phyto-nano Interventions in Psoriasis

Psoriasis is an autoimmune systemic chronic inflammatory disease that exhibits characteristic detrimental effects on the skin, often leading to infections or comorbid conditions. The multifaceted nature of psoriasis has made it very challenging to treat, especially with current chemotherapy options. Therefore, it is essential to consider phytoconstituents as novel alternatives. However, despite demonstrating higher anti-inflammatory, anti-psoriasis, and immunomodulatory potential, their clinical usage is hindered due to their poor physicochemical properties. To address these drawbacks, nanoparticulate drug delivery systems have been developed, helping to achieve better permeation of phytoconstituents through topical administration. This has breathed new life into traditional systems of medicine, particularly in the context of treating psoriasis. In this current review, we present a detailed, comprehensive, and up-to-date analysis of the literature, which will contribute to affirming the clinical role of phyto-nano interventions against psoriasis.

Efficacy and safety of vitamin D supplementation on psoriasis: A systematic review and meta-analysis

OBJECTIVES

Our aim was to analyze the results of published randomized controlled trials (RCTs) on vitamin D supplementation for psoriasis in order to explore its effectiveness and safety.

PATIENTS AND METHODS

As of July 7 2023, we conducted a systematic literature search in PubMed, Cochrane, Embase, and Web of Science Core Collection databases. The study outcomes included change values in Psoriasis Area and Severity Index (PASI) (at 3 months, 6 months, and end of follow-up)/Dermatology Life Quality Index (DLQI)/Psoriasis disability index (PDI)/C-reactive protein (CRP), and adverse events.

RESULTS

333 patients from 4 studies were evaluated. Pooled analyses showed no significant effect of DLQI/PDI/CRP change value (P > 0.05) or PASI change value (3 months, end of follow-up; P > 0.05). Sensitivity analyses and statistical tests did not support the results of the PASI change values (6 months, P = 0.05). However, the results of subgroup analyses should not be ignored(supplementation with vitamin D2 or Asia would be more effective; P = 0.03). There were no serious adverse effects, and only a few individuals experienced nausea.

CONCLUSIONS

The efficacy and safety of vitamin D supplementation in the treatment of psoriasis remains unremarkable. The search for a new prognostic index that combines clinical and laboratory factors is needed to compensate for the shortcomings of existing measures and provide stronger evidence of validity.

A comprehensive investigation of novel and traditional inflammatory and metabolic markers as predictive indicators in psoriasis

BACKGROUND

Psoriasis is a chronic inflammatory and papulosquamous dermatological disorder. While previous studies have discussed certain inflammatory markers for diagnosing and monitoring psoriasis, there is an absence of comprehensive research encompassing both novel and traditional inflammatory markers, as well as metabolic markers, in relation to psoriasis.

METHODS

A total of 209 individuals participated, including 54 psoriasis patients and 155 controls. Psoriasis Area Severity Index (PASI) was calculated for the patient group. Potential predictive markers for psoriasis were identified: Uric acid/HDL ratio (UHR), D-dimer/albumin ratio (DAR), fibrinogen/albumin ratio (FAR), erythrocyte sedimentation rate, CRP, WBC, HOMA-IR, and vitamin D levels. Differences between groups and correlations with PASI and each other were analyzed using the Mann-Whitney U test and Spearman correlation coefficient.

RESULTS

The results indicate that the patient group exhibited statistically significantly higher levels of UHR, FAR, CRP, WBC, and HOMA-IR. Upon analyzing the correlations between PASI and the identified markers, statistically significant positive correlation with WBC and negative correlation with vitamin D were observed. The correlations of PASI with other markers did not reach statistical significance. It should be underlined that our study was conducted in a predominantly mild-to-moderate patient population.

CONCLUSIONS

The absence of specificity of these markers for psoriasis limits their practical application. However, the development of new objective measures by using them in combination with specific data such as PASI will provide significant benefits in terms of disease diagnosis, follow-up, and treatment.

Using a Topical Formulation of Vitamin D for the Treatment of Vitiligo: A Systematic Review

Vitamin D is one significant prohormone substance in human organ systems. It is a steroidal hormone produced in the skin upon exposure to UVB rays. This paper presents a systematic review of the utilization of topical vitamin D, specifically cholecalciferol, calcipotriol, and tacalcitol, in the treatment of vitiligo. It considers the role of vitamin D in stimulating the synthesis of melanin and melanogenesis, which can help with the process of repigmentation. The inclusion of calcipotriol or tacalcitol in Narrowband Ultraviolet Phototherapy (NB-UVB) has shown the potential to enhance therapeutic outcomes for vitiligo. However, their effectiveness in combination with Psoralens Long Wave Ultraviolet Radiation (PUVA) and Monochromatic Excimer Light (MEL) treatment for vitiligo is limited. In contrast, combining topical corticosteroids with vitamin D analogues has demonstrated superior efficacy in treating vitiligo compared to using vitamin D analogues alone, while also providing the added benefit of reducing corticosteroid-related adverse effects. In addition, treating stable vitiligo with topical cholecalciferol and microneedling has shown success. Future studies are needed to ascertain an efficient method of administering vitamin D topically as an anti-vitiligo agent.

Microneedles as a momentous platform for psoriasis therapy and diagnosis: A state-of-the-art review

Psoriasis is a chronic, autoimmune, and non-communicable skin disease with a worldwide prevalence rate of 2-3%, creating an economic burden on global health. Some significant risk factors associated with psoriasis include genetic predisposition, pathogens, stress, medications, etc. In addition, most patients with psoriasis should also deal with comorbidities such as psoriatic arthritis, inflammatory bowel diseases, cardiovascular diseases, and psychological conditions, including suicidal thoughts. Based on its severity, the treatment approach for psoriasis is categorised into three types, i.e., topical therapy, systemic therapy, and phototherapy. Topical therapy for mild-to-moderate psoriasis faces several issues, such as poor skin permeability, low skin retention of drug formulation, greasy texture of topical vehicle, lack of controlled release, and so on. On the other arrow, systemic therapy via an oral or parenteral route of drug administration involves numerous drawbacks, including first-pass hepatic metabolism, hepatotoxicity, gastrointestinal disturbances, needle pain and phobia, and requirement of healthcare professional to administer the drug. To overcome these limitations, researchers devised a microneedle-based drug delivery system for treating mild-to-moderate and moderate-to-severe psoriasis. A single microneedle system can deliver the anti-psoriatic drugs either locally (topical) or systemically (transdermal) by adjusting the needle height without involving any pain. In this contemplate, the current review provides concise information on the pathophysiology, risk factors, and comorbidities of psoriasis, followed by their current treatment approaches and limitations. Further, it meticulously discusses the potential of microneedles in psoriasis therapy and diagnosis, along with descriptions of their patents and clinical trials.

Vitamin D: sources, physiological role, biokinetics, deficiency, therapeutic use, toxicity, and overview of analytical methods for detection of vitamin D and its metabolites

Vitamin D has a well-known role in the calcium homeostasis associated with the maintenance of healthy bones. It increases the efficiency of the intestinal absorption of dietary calcium, reduces calcium losses in urine, and mobilizes calcium stored in the skeleton. However, vitamin D receptors are present ubiquitously in the human body and indeed, vitamin D has a plethora of non-calcemic functions. In contrast to most vitamins, sufficient vitamin D can be synthesized in human skin. However, its production can be markedly decreased due to factors such as clothing, sunscreens, intentional avoidance of the direct sunlight, or the high latitude of the residence. Indeed, more than one billion people worldwide are vitamin D deficient, and the deficiency is frequently undiagnosed. The chronic deficiency is not only associated with rickets/osteomalacia/osteoporosis but it is also linked to a higher risk of hypertension, type 1 diabetes, multiple sclerosis, or cancer. Supplementation of vitamin D may be hence beneficial, but the intake of vitamin D should be under the supervision of health professionals because overdosing leads to intoxication with severe health consequences. For monitoring vitamin D, several analytical methods are employed, and their advantages and disadvantages are discussed in detail in this review.

Effect of Melatonin on Psoriatic Phenotype in Human Reconstructed Skin Model

Psoriasis is an inflammatory and auto-immune skin-disease characterized by uncontrolled keratinocyte proliferation. Its pathogenesis is not still fully understood; however, an aberrant and excessive inflammatory and immune response can contribute to its progression. Recently, more attention has been given to the anti-inflammatory and immunomodulators effects of melatonin in inflammatory diseases. The aim of this paper was to investigate the effect of melatonin on psoriatic phenotype and also in S. aureus infection-associated psoriasis, with an in vitro model using Skinethic Reconstructed Human Epidermis (RHE). An in vitro model was constructed using the RHE, a three-dimensional-model obtained from human primary-keratinocytes. RHE-cells were exposed to a mix of pro-inflammatory cytokines, to induce a psoriatic phenotype; cells were also infected with S. aureus to aggravate psoriasis disease, and then were treated with melatonin at the concentrations of 1 nM, 10 nM, and 50 nM. Our results demonstrated that melatonin at higher concentrations significantly reduced histological damage, compared to the cytokine and S. aureus groups. Additionally, the treatment with melatonin restored tight-junction expression and reduced pro-inflammatory cytokine levels, such as interleukin-1β and interleukin-12. Our results suggest that melatonin could be considered a promising strategy for psoriasis-like skin inflammation, as well as complications of psoriasis, such as S. aureus infection.

A novel chemo-phenotypic method identifies mixtures of salpn, vitamin D3, and pesticides involved in the development of colorectal and pancreatic cancer

Environmental chemical (EC) exposures and our interactions with them has significantly increased in the recent decades. Toxicity associated biological characterization of these chemicals is challenging and inefficient, even with available high-throughput technologies. In this report, we describe a novel computational method for characterizing toxicity, associated biological perturbations and disease outcome, called the Chemo-Phenotypic Based Toxicity Measurement (CPTM). CPTM is used to quantify the EC "toxicity score" (Z_ts), which serves as a holistic metric of potential toxicity and disease outcome. CPTM quantitative toxicity is the measure of chemical features, biological phenotypic effects, and toxicokinetic properties of the ECs. For proof-of-concept, we subject ECs obtained from the Environmental Protection Agency's (EPA) database to the CPTM. We validated the CPTM toxicity predictions by correlating 'Z_ts' scores with known toxicity effects. We also confirmed the CPTM predictions with in-vitro, and in-vivo experiments. In in-vitro and zebrafish models, we showed that, mixtures of the motor oil and food additive 'Salpn' with endogenous nuclear receptor ligands such as Vitamin D3, dysregulated the nuclear receptors and key transcription pathways involved in Colorectal Cancer. Further, in a human patient derived cell organoid model, we found that a mixture of the widely used pesticides 'Tetramethrin' and 'Fenpropathrin' significantly impacts the population of patient derived pancreatic cancer cells and 3D organoid models to support rapid PDAC disease progression. The CPTM method is, to our knowledge, the first comprehensive toxico-physicochemical, and phenotypic bionetwork-based platform for efficient high-throughput screening of environmental chemical toxicity, mechanisms of action, and connection to disease outcomes.

Polymorphism of VDR Gene and the Sensitivity of Human Leukemia and Lymphoma Cells to Active Forms of Vitamin D

Simple Summary

Developing new therapeutic strategies is necessary for leukemias and lymphomas treatment. Therefore, the study aimed to determine the use of an active form of vitamin D₃ calcitriol and its analog tacalcitol as an anticancer drug. Most of all, selecting the molecular factor responsible for the cell’s sensitivity to the tested agents. A biomarker that could be use in the future to select patients for therapy and improve survival outcomes. We examined nine cell lines and evaluated the proteins involved in the biological activity of calcitriol and tacalcitol: the classical vitamin D receptor and 1,25D₃-MARRS, as well as polymorphism in the VDR gene receptor. Results showed that VDR polymorphism may predispose to response to calcitriol and tacalcitol anticancer therapy.

Abstract

The active forms of vitamin D₃ (calcitriol and tacalcitol) coupled to the vitamin D receptor (VDR) are known to exhibit anti-cancer properties. However, not all cancer cells are sensitive to the active forms of vitamin D₃ and its analogs. The study aimed to determine whether polymorphism of VDR is responsible for the sensitivity of human leukemia and lymphoma cells to calcitriol and tacalcitol. The impact of calcitriol and tacalcitol on the proliferation and morphology of nine different leukemia and lymphoma cell lines was determined. Only MV-4-11, Thp-1, and HL-60 cell lines sensitive to proliferation inhibition by calcitriol and tacalcitol showed morphology changes. Subsequently, the levels of the VDR and 1,25D₃-MARRS proteins of calcitriol and tacalcitol binding receptors and the VDR receptor polymorphism in human leukemia and lymphoma cells were ascertained. Contrary to the current understanding, higher levels of VDR are not responsible for the greater sensitivity of cells to calcitriol and tacalcitol. Importantly, we first showed that sensitivity to calcitriol and tacalcitol in leukemias and lymphomas could be determined by the VDR polymorphism. The FokI polymorphism and the presence of the “bat” haplotype were observed only in the sensitive cells.

An LC-MS/MS Method for Analysis of Vitamin D Metabolites and C3 Epimers in Mice Serum: Oral Supplementation Compared to UV Irradiation

INTRODUCTION

The most common forms of vitamin D in human and mouse serum are vitamin D3 and vitamin D2 and their metabolites. The aim of this study is to determine whether diet and sunlight directly affect the circulating concentrations of vitamin D metabolites in a mouse model. We investigated the serum concentrations of eight vitamin D metabolites-vitamin D (vitamin D3 + vitamin D2), 25OHD (25OHD3 + 25OHD2), 1α25(OH)2D (1α25(OH)2D2, and 1α25(OH)2D3)-including their epimer, 3-epi-25OHD (3-epi-25OHD3 and 3-epi-25OHD2), and a bile acid precursor 7alpha-hydroxy-4-cholesten-3-one (7αC4), which is known to cause interference in liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis.

METHOD

The LC-MS/MS method was validated according to FDA-US guidelines. The validated method was used for the analysis of mouse serum samples. Forty blood samples from mice were collected and divided into three groups. The first group, the DDD mice, were fed a vitamin D-deficient diet (25 IU VD3/kg of diet) and kept in the dark; the second group, the SDD mice, were maintained on a standard-vitamin D diet (1000 IU VD3) and kept in the dark; and the third group, SDL, were fed a standard-vitamin D diet (1000 IU VD3) but kept on a normal light/dark cycle. LC-MS/MS was used for the efficient separation and quantitation of all the analytes.

RESULTS

The validated method showed good linearity and specificity. The intraday and interday precision were both <16%, and the accuracy across the assay range was within 100 ± 15%. The recoveries ranged between 75 and 95%. The stability results showed that vitamin D metabolites are not very stable when exposed to continuous freeze-thaw cycles; the variations in concentrations of vitamin D metabolites ranged between 15 and 60%. The overlapping peaks of vitamin D, its epimers, and its isobar (7αC4) were resolved using chromatographic separation. There were significant differences in the concentrations of all metabolites of vitamin D between the DDD and SDL mice. Between the groups SDD (control) and SDL, a significant difference in the concentrations of 3-epi-25OHD was noted, where C3 epimer was about 30% higher in SDL group while no significant differences were noted in the concentrations of vitamin D, 25OHD, 1α25(OH)2D, and 7αC4 between SDD and SDL group.

CONCLUSIONS

A validated method, combined with a simple extraction technique, for the sensitive LC-MS/MS determination of vitamin D metabolites is described here. The method can eliminate the interferences in LC-MS/MS analysis caused by the overlapping epimer and isobar due to them having the same molecular weights as 25OHD. The validated method was applied to mouse serum samples. It was concluded that a standard-vitamin D diet causes an increase in the proportion of all the vitamin D metabolites and C3 epimers and isobar, while UV light has no pronounced effect on the concentrations of the majority of the vitamin D metabolites except 3-epi-25OHD. Further studies are required to confirm this observation in humans and to investigate the biochemical pathways related to vitamin D's metabolites and their epimers.

Nanoemulsions: A Review on the Conceptualization of Treatment for Psoriasis Using a 'Green' Surfactant with Low-Energy Emulsification Method

Psoriasis is a skin disease that is not lethal and does not spread through bodily contact. However, this seemingly harmless condition can lead to a loss of confidence and social stigmatization due to a persons' flawed appearance. The conventional methods of psoriasis treatment include taking in systemic drugs to inhibit immunoresponses within the body or applying topical drugs onto the surface of the skin to inhibit cell proliferation. Topical methods are favored as they pose lesser side effects compared to the systemic methods. However, the side effects from systemic drugs and low bioavailability of topical drugs are the limitations to the treatment. The use of nanotechnology in this field has enhanced drug loading capacity and reduced dosage size. In this review, biosurfactants were introduced as a 'greener' alternative to their synthetic counterparts. Glycolipid biosurfactants are specifically suited for anti-psoriatic application due to their characteristic skin-enhancing qualities. The selection of a suitable oil phase can also contribute to the anti-psoriatic effect as some oils have skin-healing properties. The review covers the pathogenic pathway of psoriasis, conventional treatments, and prospective ingredients to be used as components in the nanoemulsion formulation. Furthermore, an insight into the state-of-the-art methods used in formulating nanoemulsions and their progression to low-energy methods are also elaborated in detail.

Vitamin D3-elicited CD14+ human skin dendritic cells promote thymic stromal lymphopoietin-independent type 2 T-helper responses

BACKGROUND

Immune modulation by vitamin D3 through dendritic cells (DCs) remains controversial. Human DCs exposed in vitro counteract type-1 T-helper (Th1) differentiation and induce regulatory T cells. However, cutaneous application on mice promotes Th2-driven inflammation resembling atopic dermatitis and relying on thymic stromal lymphopoietin (TSLP) from keratinocytes and T-cell orientation by TSLP-stimulated skin DCs. We studied the effects of vitamin D3 in human skin, focusing on TSLP production and the role of skin DCs in T-cell differentiation.

METHODS

Human healthy skin explants were exposed in vitro to vitamin D3 analogs. Migrating DCs were analyzed and TSLP quantified in the supernatant. Allogeneic naïve CD4+ T cells were cocultured with DCs to assess their proliferation and cytokine production.

RESULTS

Vitamin D3 induced skin DCs to differentiate Th2 cells producing IL-4 and IL-13. Vitamin D3 triggered TSLP release in ~30% of skin explants, correlating with IL-13 detection in Th2 cells. In these donors, blocking TSLP receptor during skin explant cultures abrogated IL-13 production, yet IL-4+ Th2 cells were unaffected. Among skin DCs emerged CD14+ cells that had responded directly to vitamin D3 and differed from classical CD14+ dermal emigrants. Vitamin D3-elicited CD14+ DCs sufficed to promote IL-4+ Th2 cells in a TSLP-independent manner.

CONCLUSION

Vitamin D3, despite inducing TSLP in some donors, had a direct influence on skin DCs, affecting their phenotype and ability to drive Th2 responses independently of TSLP. Our findings pave the way toward in vitro systems that accurately model human cutaneous Th2 responses, notably involved in atopic dermatitis.

Oral Vitamin D Therapy in Patients with Psoriasis

Vitamin D treatment is effective when applied topically to the skin for plaque-type psoriasis. Oral vitamin D supplementation might be effective as an adjuvant treatment option in psoriasis. This umbrella review aimed to highlight the current knowledge regarding the use of oral vitamin D for treatment of patients with psoriasis. We performed a literature search and identified 107 eligible full-text articles that were relevant to the research interest. Among these, 10 review articles were selected, and data were extracted. A data synthesis showed that only a few studies monitored oral vitamin D efficacy in patients with psoriasis. No studies investigated the optimal dose of systemic vitamin D in psoriasis. However, most studies did not observe side effects for doses within a relatively narrow range (0.25 to 2 μg/day). These results suggest that more large-scale studies are needed to determine the efficacy, optimal dose, and adverse effects of vitamin D administration in patients with psoriasis.

Controversies in Vitamin D: A Statement From the Third International Conference

The Third International Conference on Controversies in Vitamin D was held in Gubbio, Italy, September 10–13, 2019. The conference was held as a follow‐up to previous meetings held in 2017 and 2018 to address topics of controversy in vitamin D research. The specific topics were selected by the steering committee of the conference and based upon areas that remain controversial from the preceding conferences. Other topics were selected anew that reflect specific topics that have surfaced since the last international conference. Consensus was achieved after formal presentations and open discussions among experts. As will be detailed in this article, consensus was achieved with regard to the following: the importance and prevalence of nutritional rickets, amounts of vitamin D that are typically generated by sun exposure, worldwide prevalence of vitamin D deficiency, the importance of circulating concentrations of 25OHD as the best index of vitamin D stores, definitions and thresholds of vitamin D deficiency, and efficacy of vitamin D analogues in the treatment of psoriasis. Areas of uncertainly and controversy include the following: daily doses of vitamin D needed to maintain a normal level of 25OHD in the general population, recommendations for supplementation in patients with metabolic bone diseases, cutaneous production of vitamin D by UVB exposure, hepatic regulation of 25OHD metabolites, definition of vitamin D excess, vitamin D deficiency in acute illness, vitamin D requirements during reproduction, potential for a broad spectrum of cellular and organ activities under the influence of the vitamin D receptor, and potential links between vitamin D and major human diseases. With specific regard to the latter area, the proceedings of the conference led to recommendations for areas in need of further investigation through appropriately designed intervention trials. © 2020 The Authors. JBMR Plus published by Wiley Periodicals LLC. on behalf of American Society for Bone and Mineral Research.

Vitamin D and psoriasis: an update for dermatologists and nutritionists

Psoriasis is a common chronic immune-mediated inflammatory skin disease, now considered a systemic inflammatory process with several comorbidities. The skin produces vitamin D by the action of ultraviolet light. Vitamin D performs various immunomodulatory, anti-inflammatory, antioxidant and antifibrotic actions. The immunomodulatory effects of vitamin D offer opportunities to improve the treatment of several autoimmune diseases, such as psoriasis. In the literature, several significant associations are reported between low levels of vitamin D and psoriasis. Today, topical vitamin D represents an important therapeutic option due to its action on the proliferation and maturation of keratinocytes. The situation is different regarding the oral intake and integration of vitamin D in psoriasis patients. The use of vitamin D supplementation as an adjunctive treatment option in these patients is still discussed. This work aims to analyze the association between psoriasis and vitamin D levels according to dermatologists and nutritionists.

Safety of calcipotriene and betamethasone dipropionate foam for the treatment of psoriasis

Introduction: Psoriasis vulgaris is a chronic inflammatory skin disease characterized by well-demarcated red and scaly plaques. Most patients have mild disease that is usually controlled with topical treatment. Calcipotriene 0.05% and betamethasone dipropionate 0.064% (Cal/BD) in aerosol foam (Enstilar®) is a novel formulation, which has shown promising results in terms of efficacy and safety.Areas covered: This review evaluates the safety profile of Cal/BD aerosol foam and also the key points regarding its efficacy. A literature search was performed in PubMed in November 2019 from the start of records. Additional references were searched and retrieved manually.Expert opnion: Cal/BD aerosol foam has proven its efficacy, safety, and tolerability in several clinical trials and real clinical practice. It has also demonstrated higher efficacy than the ointment and gel formulations of the fixed combination. It has a low incidence of adverse events; nasopharyngitis and site application pain were the most frequently reported. Moreover, it is devoid of changes in calcium homeostasis and hypothalamic-pituitary-adrenal axis. As a result of its unique formulation, it is easily spread, is rapidly absorbed, and has a rapid onset of action. These features upgrade patient's satisfaction and they may increase adherence to topical therapy.

Repurposing the psoriasis drug Oxarol to an ointment adjuvant for the influenza vaccine

Aluminum precipitates have long been used as adjuvants for human vaccines, but there is a clear need for safer and more effective adjuvants. Here we report in a mouse model that the psoriasis drug Oxarol ointment is a highly effective vaccine adjuvant. By applying Oxarol ointment onto skin, humoral responses and germinal center (GC) reactions were augmented, and the treated mice were protected from death caused by influenza virus infection. Keratinocyte-specific vitamin D3 receptor (Vdr) gene expression was required for these responses through induction of the thymic stromal lymphopoietin (Tslp) gene. Experiments involving administration of recombinant TSLP or, conversely, anti-TSLP antibody demonstrated that TSLP plays a key role in the GC reactions. Furthermore, cell-type-specific Tslpr gene deletion or diphtheria toxin-mediated deletion of specific cell types revealed that CD11c+ cells excluding Langerhans cells were responsible for the Oxarol-mediated GC reactions. These results indicate that active vitamin D3 is able to enhance the humoral response via Tslp induction in the skin and serves as a new vaccine adjuvant.

Pathophysiology of Atopic Dermatitis and Psoriasis: Implications for Management in Children

Atopic dermatitis (AD) and psoriasis are chronic inflammatory skin diseases associated with a significant cutaneous and systemic burden of disease as well as a poor health-related quality of life. Here, we review the complex pathophysiology of both AD and psoriasis and discuss the implications for treatment with current state-of-the-art and emerging topical and systemic therapies. Both AD and psoriasis are caused by a complex combination of immune dysregulation, skin-barrier disruption, genetic factors, and environmental influences. Previous treatments for both diseases were limited to anti-inflammatory agents that broadly suppress inflammation. Emerging insights into relevant pathways, including recognition of the role of T-helper type 2 driven inflammation in AD and T-helper 1 and 17 driven inflammation in psoriasis, have led to a therapeutic revolution. There are a number of novel treatment options available for AD and psoriasis with many more currently under investigation.

Differential response of lung cancer cell lines to vitamin D derivatives depending on EGFR, KRAS, p53 mutation status and VDR polymorphism

Vitamin D reveals antiproliferative activity against many types of cancer cells. Calcitriol (1,25D3), the most active form of vitamin D3, acts mainly through the vitamin D receptor, regulating the expression of target genes. Cells with reasonable expression of VDR are considered to be sensitive to antiproliferative activity of 1,25D3. However, a few alleles of the VDR gene are correlated with higher or lower response to 1,25D3 treatment. The goal of our study was to establish if cells differing in EGFR, KRAS, p53 mutation status and VDR polymorphism were sensitive to antiproliferative activity of selected vitamin D derivatives (VDDs). In our search for the lead VDD against human lung cancer cells, we selected, for this study, low calcemic analogs of active forms of vitamin D2 and D3 that had previously shown anticancer potential. The selected cell lines revealed differential response to VDDs. The highest proliferation inhibition was observed for EGFR mutant cells while a weaker response was observed for KRAS and/or p53 mutant cells. 24,24-Dihomo-1,25D3 (PRI-1890) showed the highest activity on the VDD-sensitive cell lines (A549, HCC827, NCI-H1299, and NCI-H1703). Therefore, PRI-1890 was selected as the lead VDD for further structure optimization. None of the VDDs used in this study showed antiproliferative activity against A-427 and Calu-3. VDR polymorphisms correlated inversely with sensitivity to the antiproliferative activity of VDDs since we observed less transcriptionally active form of VDR in HCC827 cells sensitive to VDD, while more transcriptionally active form was observed in NCI-H358 cells that were stimulated by VDDs to proliferate. Lack of KRAS and p53 mutations in HCC827 cells may be, therefore, responsible for the higher antiproliferative activity of VDDs, while the presence of KRAS and/or p53 mutations in other cell lines might prevent antiproliferative activity even though the VDDs were transcriptionally active as assessed on increased CYP24A1 expression. VDR gene polymorphism is not directly responsible for the sensitivity of tested cells to VDDs.

Skeletal and Extraskeletal Actions of Vitamin D: Current Evidence and Outstanding Questions

The etiology of endemic rickets was discovered a century ago. Vitamin D is the precursor of 25-hydroxyvitamin D and other metabolites, including 1,25(OH)2D, the ligand for the vitamin D receptor (VDR). The effects of the vitamin D endocrine system on bone and its growth plate are primarily indirect and mediated by its effect on intestinal calcium transport and serum calcium and phosphate homeostasis. Rickets and osteomalacia can be prevented by daily supplements of 400 IU of vitamin D. Vitamin D deficiency (serum 25-hydroxyvitamin D <50 nmol/L) accelerates bone turnover, bone loss, and osteoporotic fractures. These risks can be reduced by 800 IU of vitamin D together with an appropriate calcium intake, given to institutionalized or vitamin D-deficient elderly subjects. VDR and vitamin D metabolic enzymes are widely expressed. Numerous genetic, molecular, cellular, and animal studies strongly suggest that vitamin D signaling has many extraskeletal effects. These include regulation of cell proliferation, immune and muscle function, skin differentiation, and reproduction, as well as vascular and metabolic properties. From observational studies in human subjects, poor vitamin D status is associated with nearly all diseases predicted by these extraskeletal actions. Results of randomized controlled trials and Mendelian randomization studies are supportive of vitamin D supplementation in reducing the incidence of some diseases, but, globally, conclusions are mixed. These findings point to a need for continued ongoing and future basic and clinical studies to better define whether vitamin D status can be optimized to improve many aspects of human health. Vitamin D deficiency enhances the risk of osteoporotic fractures and is associated with many diseases. We review what is established and what is plausible regarding the health effects of vitamin D.

Unraveling the ECM-Immune Cell Crosstalk in Skin Diseases

The extracellular matrix (ECM) is a complex network of proteins and proteoglycans secreted by keratinocytes, fibroblasts and immune cells. The function of the skin ECM has expanded from being a scaffold that provides structural integrity, to a more dynamic entity that is constantly remodeled to maintain tissue homeostasis. The ECM functions as ligands for cell surface receptors such as integrins, dystroglycans, and toll-like receptors (TLRs) and regulate cellular signaling and immune cell dynamics. The ECM also acts as a sink for growth factors and cytokines, providing critical cues during epithelial morphogenesis. Dysregulation in the organization and deposition of ECMs lead to a plethora of pathophysiological conditions that are exacerbated by aberrant ECM-immune cell interactions. In this review, we focus on the interplay between ECM and immune cells in the context of skin diseases and also discuss state of the art therapies that target the key molecular players involved.

Imaging of vitamin D in psoriatic skin using time-of-flight secondary ion mass spectrometry (ToF-SIMS): A pilot case study

Recently it has been recognized that there is a need of investigating in detail the vitamin D synthesis and metabolism directly in the skin with respect to its possible autocrine and paracrine actions. The potential effects the active metabolite of vitamin D exerts in pathological skin conditions like psoriasis needs to be clarified. Under ultraviolet B (UVB) irradiation skin can autonomously synthesize, activate and degrade vitamin D. In this pilot case study, we used for the first time Time-of-flight secondary ion mass spectrometry (ToF-SIMS) in the analysis of skin biopsies from a patient with psoriasis before and after UVB phototherapy. We were able to visualize vitamin D₃ and its metabolites in the skin and subcutaneous tissue. At the same time information about their localization at subcellular level and morphology of the skin was received. This study proves that ToF-SIMS is a promising powerful tool to be used when investigating vitamin D´s role in dermatological diseases through skin biopsies.

Use of active metabolites of vitamin D orally for the treatment of psoriasis

OBJECTIVE

The objective of this study was to analyse the existing bibliographic production on clinical trials related to the use of vitamin D for oral treatment of psoriasis.

METHOD

A literature review of clinical trials related to the use of vitamin D for oral treatment of psoriasis, published in the LILACS, Scielo, Medline, PubMed and Cochrane Library from 1986 to 2013. The search included the following terms: "Psoriasis and oral Vitamin D"; "psoríase e vitamina D oral".

RESULTS

After analysing the titles and summaries, 10 articles met the eligibility criteria.

DISCUSSION

According to the literature, most tests were made in moderate psoriasis with doses ranging from 0.25 to 2μg, demonstrating improvement with this treatment modality. Some studies suggest the use of high doses, but the biggest concern is hypercalciuria as a side effect.

CONCLUSION

The use of active metabolites of vitamin D orally for the treatment of psoriasis showed efficacy and safety.

Disrupting the IL-36 and IL-23/IL-17 loop underlies the efficacy of calcipotriol and corticosteroid therapy for psoriasis

Psoriasis is one of the most common skin inflammatory diseases worldwide. The vitamin D3 analog calcipotriol has been used alone or in combination with corticosteroids in treating plaque psoriasis, but how it suppresses psoriatic inflammation has not been fully understood. Using an experimental mouse psoriasis model, we show that topical calcipotriol inhibited the pivotal IL-23/IL-17 axis and neutrophil infiltration in psoriatic skin, and interestingly, such effects were mediated through the vitamin D receptor (VDR) in keratinocytes (KCs). We further reveal that IL-36α and IL-36γ, which have recently emerged as key players in psoriasis pathogenesis, were effectively repressed by calcipotriol via direct VDR signaling in mouse KCs. Accordingly, calcipotriol treatment suppressed IL-36α/γ expression in lesional skin from patients with plaque psoriasis, which was accompanied by a reduced IL-23/IL-17 expression. In contrast, dexamethasone indirectly reduced IL-36α/γ expression in mouse psoriatic skin through immune cells. Furthermore, we demonstrate that calcipotriol and dexamethasone, in combination, synergistically suppressed the expression of IL-36α/γ, IL-23, and IL-17 in the established mouse psoriasis. Our findings indicate that the combination of calcipotriol and corticosteroid efficiently disrupts the IL-36 and IL-23/IL-17 positive feedback loop, thus revealing a mechanism underlying the superior efficacy of calcipotriol and corticosteroid combination therapy for psoriasis.

Association between psoriasis and vitamin D: Duration of disease correlates with decreased vitamin D serum levels: An observational case-control study

Recent literature has focused on the association of psoriasis with lower than normal or highly deficient vitamin D blood levels.To investigate the controversial association between psoriasis and vitamin D levels.From 2012 to 2014, 561 subjects were assessed, of which 170 had psoriasis, 51 had an autoimmune bullous, and 340 were healthy patients. Anagraphical data, 25(OH)D blood levels, and seasons of vitamin D levels assessments were recorded for each group.Vitamin D levels were significantly different among the 3 groups (K = 151.284; P = .0001). Psoriatic patients had significantly lower serum levels of 25(OH)D (21.8 ng/mL) than healthy controls (34.3 ng/mL) (chi-square = 11.5; P = .0007). Patients with bullous diseases showed the lowest vitamin D mean values (18.2 ng/mL). The linear multiple regression model showed 25(OH)D levels to be influenced by age, season of blood vitamin D levels assessment, and psoriasis duration.These results confirm the reduced vitamin D levels in psoriatic patients when compared to healthy controls, and provide new evidence regarding the association of vitamin D levels and psoriasis duration. The limits of our study include its observational nature and the small number of patients undergoing biological immunosuppressive therapies.

The skin microbiome and immune system: Potential target for chemoprevention?

There has been increasing interest in understanding the role of the human microbiome in skin diseases. Microbiome studies are being utilized in skin cancer research in numerous ways. Commensal bacteria are being studied as a potential tool to judge the biggest environmental risk of skin cancer, ultraviolet (UV) radiation. Owing to the recognized link of skin microbes in the process of inflammation, there have been theories linking commensal bacteria to skin cancer. Viral metagenomics has also provided insight into virus linked forms of skin cancers. Speculations can be drawn for skin microbiome that in a manner similar to gut microbiome, they can be involved in chemoprevention of skin cancer. Nonetheless, there are definitely huge gaps in our knowledge of the relationship of microbiome and skin cancers, especially in relation to chemoprevention. The utilization of microbiome in skin cancer research seems to be a promising field and may help yield novel skin cancer prevention and treatment options. This review focuses on recent utilization of the microbiome in skin cancer research, and it explores the potential of utilizing the microbiome in prevention, earlier diagnosis, and treatment of skin cancers.

Differential activity of 2-methylene-19-nor vitamin D analogs on growth factor gene expression in rhino mouse skin and comparison to all-trans retinoic acid

While all 2-methylene-19-nor analogs of 1α,25-dihydroxyvitamin D₃ (1α,25(OH)₂D₃) tested produce an increase in epidermal thickness in the rhino mouse, only a subset reduce utricle size (comedolysis). All-trans retinoic acid (atRA) also causes epidermal thickening and a reduction in utricle size in the rhino mouse. We now report that 2-methylene-19-nor-(20S)-1α-hydroxybishomopregnacalciferol (2MbisP), a comedolytic analog, increases epidermal thickening more rapidly than does atRA, while both reduce utricle area at an equal rate. Whereas unlike atRA, 2MbisP does not alter the epidermal growth factor receptor ligand, heparin-binding epidermal growth factor-like growth factor, it does increase the expression of both amphiregulin and epigen mRNA, even after a single dose. In situ hybridization reveals an increase in these transcripts throughout the closing utricle as well as in the interfollicular epidermis. The mRNAs for other EGFR ligands including betacellulin and transforming growth factor-α, as well as the epidermal growth factor receptor are largely unaffected by 2MbisP. Another analog, 2-methylene-19-nor-(20S)-26,27-dimethylene-1α,25-dihydroxyvitamin D3 (CAGE-3), produces epidermal thickening but fails to reduce utricle size or increase AREG mRNA levels. CAGE-3 modestly increases epigen mRNA levels, but only after 5 days of dosing. Thus, 2-MbisP produces unique changes in epidermal growth factor receptor ligand mRNAs that may be responsible for both epidermal proliferation and a reduction in utricle size.

Modulation of inflammatory and immune responses by vitamin D

Vitamin D (VitD) is a prohormone most noted for the regulation of calcium and phosphate levels in circulation, and thus of bone metabolism. Inflammatory and immune cells not only convert inactive VitD metabolites into calcitriol, the active form of VitD, but also express the nuclear receptor of VitD that modulates differentiation, activation and proliferation of these cells. In vitro, calcitriol upregulates different anti-inflammatory pathways and downregulates molecules that activate immune and inflammatory cells. Administration of VitD has beneficial effects in a number of experimental models of autoimmune disease. Epidemiologic studies have indicated that VitD insufficiency is frequently associated with immune disorders and infectious diseases, exacerbated by increasing evidence of suboptimal VitD status in populations worldwide. To date, however, most interventional studies in human inflammatory and immune diseases with VitD supplementation have proven to be inconclusive. One of the reasons could be that the main VitD metabolite measured in these studies was the 25-hydroxyVitD (25OHD) rather than its active form calcitriol. Although our knowledge of calcitriol as modulator of immune and inflammatory reactions has dramatically increased in the past decades, further in vivo and clinical studies are needed to confirm the potential benefits of VitD in the control of immune and inflammatory conditions.

Vitamin D and its role in psoriasis: An overview of the dermatologist and nutritionist

Psoriasis is a chronic immune-mediated inflammatory skin disease. Psoriasis lesions are characterized by hyper-proliferation of epidermal keratinocytes associated with inflammatory cellular infiltrate in both dermis and epidermis. The epidermis is the natural source of vitamin D synthesis by sunlight action. Recently, a role for vitamin D in the pathogenesis of different skin diseases, including psoriasis, has been reported. Indeed, significant associations between low vitamin D status and psoriasis have been systematically observed. Due to its role in proliferation and maturation of keratinocytes, vitamin D has become an important local therapeutic option in the treatment of psoriasis. To date, the successful treatment based on adequate dietary intake of vitamin D or oral vitamin D supplementation in psoriasis represent an unmet clinical need and the evidence of its beneficial effects remains still controversial. This information is important either for Dermatologists and Nutritionists to increases the knowledge on the possible bi-directional relationships between low vitamin D status and psoriasis and on the potential usefulness of vitamin D in psoriasis with the aim not only to reduce its clinical severity, but also for delineating the risk profile for co-morbidities cardiac risk factors that may result from psoriasis. In the current review, we analyzed the possible bi-directional links between psoriatic disease and vitamin D.

Tolerability of Crisaborole Ointment for Application on Sensitive Skin Areas: A Randomized, Double-Blind, Vehicle-Controlled Study in Healthy Volunteers

Background

Inflammatory skin diseases such as atopic dermatitis (AD) and psoriasis often present in sensitive and thin-skinned areas that are at higher risk for topical treatment-related skin irritation (e.g., burning, stinging).

Objectives

Our objective was to address the need for topical treatments that can be safely applied to these areas. We assessed the local tolerability of crisaborole topical ointment when applied to sensitive and thin-skinned areas of healthy volunteers.

Methods

In this phase I, randomized, double-blind, vehicle-controlled, single-center study, 32 subjects were randomized 3:1 to twice-daily application of crisaborole topical ointment, 2 %, (n = 24) or vehicle ointment (n = 8) for 21 days to 13 anatomic skin areas, including the face/hairline, genitals, extensor, and intertriginous areas. The primary endpoint was assessment of the frequency and severity of local tolerability symptoms (burning/stinging, erythema, and pruritus) using the Local Tolerability Scale.

Results

Overall, 98.8 % of all tolerability assessments had a grade of 0 (no signs/symptoms of irritation) and 0.1 % had a grade >1 (mild); no differences were observed in the frequency of local tolerability scores between treatment groups. The total frequency of local tolerability assessments graded >0 (none) was lower across all application sites with crisaborole ointment (0.0–2.2 %) than with vehicle ointment (2.4–7.1 %). Local tolerability did not change over time, and was comparable between sensitive and nonsensitive skin areas.

Conclusions

Crisaborole ointment application to sensitive skin areas was well tolerated in healthy volunteers, supporting its potential role as a topical treatment alternative for patients with AD or psoriasis.

Advances in psoriasis physiopathology and treatments: Up to date of mechanistic insights and perspectives of novel therapies based on innovative skin drug delivery systems (ISDDS)

Psoriasis is a chronic inflammatory disease affecting mainly the skin but which can be complicated by psoriatic arthritis (PsA).This autoimmune skin disorder concerns 2-5% of the world population. To date, the physiopathology of psoriasis is not still completely elucidated but many researches are ongoing which have led for example to the discovery of the Th17/Th22 pathway. The conventional therapeutic approaches (local or systemic route) appeal to various classes of drugs with complex mechanisms of action and non-negligible side effects. Although there is no therapy capable to cure psoriasis, the current goal is to relieve symptoms as longer as possible with a good benefit/risk ratio. That is one of the principal limits of conventional antipsoriatic drugs. New formulations based on nanoencapsulation are a promising opportunity to answer to this limit by offering an optimization of the conventional antipsoriatic drug use (higher activity, lower side effects and frequency of application, etc.). Herein, we tried to put in perspective the mechanistic insights (histological and immunological views) proposed into scientific literature these last years in order to have a better comprehension of psoriasis physiopathology resulting in skin lesions and PsA. The therapeutic armamentarium and the different strategies in the management of psoriasis are discussed in greater details. To finish, the field of encapsulation in nanoparticles is broached in order to put forward recent advances in innovative skin drug delivery systems (ISDDSs) of antipsoriatic active agents for a better efficacy, safety and compliance.

Vitamin D: Metabolism, Molecular Mechanism of Action, and Pleiotropic Effects

1,25-Dihydroxvitamin D3 [1,25(OH)2D3] is the hormonally active form of vitamin D. The genomic mechanism of 1,25(OH)2D3 action involves the direct binding of the 1,25(OH)2D3 activated vitamin D receptor/retinoic X receptor (VDR/RXR) heterodimeric complex to specific DNA sequences. Numerous VDR co-regulatory proteins have been identified, and genome-wide studies have shown that the actions of 1,25(OH)2D3 involve regulation of gene activity at a range of locations many kilobases from the transcription start site. The structure of the liganded VDR/RXR complex was recently characterized using cryoelectron microscopy, X-ray scattering, and hydrogen deuterium exchange. These recent technological advances will result in a more complete understanding of VDR coactivator interactions, thus facilitating cell and gene specific clinical applications. Although the identification of mechanisms mediating VDR-regulated transcription has been one focus of recent research in the field, other topics of fundamental importance include the identification and functional significance of proteins involved in the metabolism of vitamin D. CYP2R1 has been identified as the most important 25-hydroxylase, and a critical role for CYP24A1 in humans was noted in studies showing that inactivating mutations in CYP24A1 are a probable cause of idiopathic infantile hypercalcemia. In addition, studies using knockout and transgenic mice have provided new insight on the physiological role of vitamin D in classical target tissues as well as evidence of extraskeletal effects of 1,25(OH)2D3 including inhibition of cancer progression, effects on the cardiovascular system, and immunomodulatory effects in certain autoimmune diseases. Some of the mechanistic findings in mouse models have also been observed in humans. The identification of similar pathways in humans could lead to the development of new therapies to prevent and treat disease.

Vitamin D3 levels and bone mineral density in patients with psoriasis and/or psoriatic arthritis

Limited data are available on the vitamin D3 status and bone mineral density (BMD) of patients with psoriasis or with psoriatic arthritis. Our study intended to explore possible correlations between vitamin D status and BMD, as well as among these parameters and the features of the underlying disorder. Seventy-two patients with psoriasis/or psoriatic arthritis (female : male ratio, 40:32; mean age, 58.5 ± 11.6 years; mean duration of follow up, 142.7 ± 147.7 months) participated in the study. We evaluated the characteristic clinical features of the underlying disease, performed bone densitometry of the lumbar spine and the hip region, measured the serum vitamin 25(OH)D3 levels of the patients, and undertook the statistical analysis of the relationships between the clinical and the laboratory parameters. The proportion of patients with a low BMD value did not exceed that seen in the general population. We found an inverse correlation between the serum level of vitamin 25(OH)D3 and body mass index, as well as between the former and the severity of skin involvement. Furthermore, the activity of psoriatic arthritis was significantly higher in patients with inadequate vitamin D3 status. In patients with psoriatic arthritis, BMD significantly exceeded the values measured in patients suffering from psoriatic skin lesions only. Our findings suggest the importance of evaluating the vitamin D3 status and screening for comorbid conditions in patients with psoriasis or psoriatic arthritis. This appears justified, in particular, due to the possible role of hypovitaminosis D3 in provoking the development of skin lesions and joint symptoms.

The role of vitamin D in psoriasis: a review

BACKGROUND AND OBJECTIVE

Psoriasis is a common, chronic autoimmune inflammatory skin disorder, which has potential systemic complications and is clinically defined by sharply demarcated, erythematous patches and plaques covered by a characteristic silvery white scale. Topical corticosteroids have widely been regarded as the mainstay first line of treatment. Recently, topical vitamin D analogs have been added to the first-line treatment repertoire as well, either as monotherapy or in combination with topical steroids due to synergistic, complementary effectiveness. In this paper, we review the role of vitamin D in the pathophysiology and treatment of psoriasis.

METHODS

A comprehensive search of the Cochrane Library, MEDLINE, and PUBMED databases were performed to identify relevant basic science and clinical trial literature investigating the role of vitamin D in psoriasis. Primary endpoints in clinical trials were largely based on clinical improvement as assessed by the psoriasis area severity index score or physician's global assessment.

RESULTS AND CONCLUSION

The role of vitamin D in psoriasis is complex and extensive. Oral and topical vitamin D therapies provide comparable efficacies to corticosteroids when used as monotherapy and may be superior when used in combination with a potent topical steroid. Additionally topical vitamin D analogs demonstrate a favorable safety profile with "steroid-sparing" effects. Thus, topical vitamin D derivatives should be considered an indispensable component of the current physician's arsenal in the treatment of psoriasis.

Pharmacological effects of vitamin D and its analogs: recent developments

Calcitriol, the hormonally active form of vitamin D, is well known for its diverse pharmacological activities, including modulation of cell growth, neuromuscular and immune function and reduction of inflammation. Calcitriol and its analogs exert potent effects on cellular differentiation and proliferation, regulate apoptosis and produce immunomodulatory effects. The purpose of this review is to provide information on various physiological and pharmacological activities of calcitriol and its newly discovered analogs. Special emphasis is given to skin diseases, cancer, diabetes and multiple sclerosis. A discussion is raised on the mechanisms of action of calcitriol and its analogs in various diseases, as well as on possible methods of delivery and targeting.

Vitamin D controls murine and human plasmacytoid dendritic cell function

Topical application of the vitamin D (VitD) analog calcipotriol is a highly effective standard treatment modality of psoriatic skin lesions. However, the immune modulatory effects of the treatment are incompletely understood. VitD is well known to induce tolerogenic responses in conventional dendritic cells (cDCs). Plasmacytoid DCs (pDCs) comprise a specialized, naturally occurring DC subset known to be important in autoimmune diseases including psoriasis. pDCs from the blood rapidly infiltrate psoriatic skin and are key to the initiation of the immune-mediated pathogenesis of the disease. We now demonstrate that pDCs express various proteins of the VitD receptor (VDR) pathway, including the VitD-metabolizing enzymes Cyp27B1 and Cyp24A1, and that VDR is transcriptionally active in pDCs. Moreover, VitD impairs the capacity of murine and human pDCs to induce T-cell proliferation and secretion of the T-helper 1 cytokine IFNγ. The inhibitory effect of VitD is dependent on the expression of the VDR in the DCs. This study demonstrates that VitD signaling can act as a natural inhibitory mechanism on both cDCs and pDCs, which may instigate the development of VitD-based therapeutic applications for psoriasis and other inflammatory skin diseases.