Potent inhibition of dendritic cell differentiation and maturation by vitamin D analogs

Vitamin D efficacy in type 1 and type 2 diabetes

It is well known that vitamin D has a profound effect on calcium and bone metabolism, but its influence on other organs (extraskeletal effect) has been proposed. Consistently, vitamin D deficiency is associated with an increased incidence of various diseases, including type 1 and type 2 diabetes, as reported by many observational studies. However, there has been no consensus on whether vitamin D deficiency is a causative factor in the incidence of diabetes mellitus. There have been no randomized controlled trials (RCTs) aimed at preventing the onset of type 1 diabetes with vitamin D intake. In addition, the results of RCTs evaluating the preventive effect of vitamin D supplementation on type 2 diabetes development have been inconsistent. The recent observational studies, randomized controlled trials, and meta-analyses are confirming that vitamin D or active vitamin D administration is effective in preventing the incident of type 1 and type 2 diabetes.

Two lineages of immune cells that differentially express the vitamin D receptor

Since 1983 it has been known that monocytes and activated T and B cells expressed the vitamin D receptor (VDR) and are therefore vitamin D targets. New data identified two lineages of immune cells that can be differentiated by the expression of the VDR. Monocytes, macrophages, neutrophils, and hematopoietic stem cells were mostly from VDR positive lineages. T cells, ILC1 and ILC3 were also largely VDR positive, which is consistent with the known effects of vitamin D as regulators of type-1 and type-3 immunity. Activation of the VDR negative T cells did not induce the expression of the VDR reporter, suggesting that perhaps only a subset of the T cells in the periphery express the VDR. When activated, the VDR negative T cells responded as if they were VDR knockout T cells in that they made more IFN-γ and proliferated faster than the VDR positive T cells. The ability of vitamin D to regulate immune function will depend on which cells express the VDR and a better understanding of the signals that regulate VDR expression in immune cells.

The Role of Microbiota-Derived Vitamins in Immune Homeostasis and Enhancing Cancer Immunotherapy

Not all cancer patients who receive immunotherapy respond positively and emerging evidence suggests that the gut microbiota may be linked to treatment efficacy. Though mechanisms of microbial contributions to the immune response have been postulated, one likely function is the supply of basic co-factors to the host including selected vitamins. Bacteria, fungi, and plants can produce their own vitamins, whereas humans primarily obtain vitamins from exogenous sources, yet despite the significance of microbial-derived vitamins as crucial immune system modulators, the microbiota is an overlooked source of these nutrients in humans. Microbial-derived vitamins are often shared by gut bacteria, stabilizing bioenergetic pathways amongst microbial communities. Compositional changes in gut microbiota can affect metabolic pathways that alter immune function. Similarly, the immune system plays a pivotal role in maintaining the gut microbiota, which parenthetically affects vitamin biosynthesis. Here we elucidate the immune-interactive mechanisms underlying the effects of these microbially derived vitamins and how they can potentially enhance the activity of immunotherapies in cancer.

The effects of 1,25(OH)2D3 treatment on metabolic reprogramming and maturation in bone marrow-derived dendritic cells from control and diabetic mice

Activated dendritic cells (DCs) undergo significant metabolic reprogramming, which is characterized by an increase in aerobic glycolysis and a concurrent progressive loss of oxidative phosphorylation. The modulation of metabolic reprogramming is believed to be closely related to the function of DCs. Vitamin D has been reported to inhibit the maturation of DCs. DC dysfunction has been reported in diabetic patients, and hyperglycemia is associated with impaired glycolytic metabolism in immune cells. Therefore, vitamin D and diabetes may affect intracellular metabolism, thereby regulating the activity of DCs. We investigated the effect of in vitro treatment of 1,25-dihydroxyvitamin D₃ (1,25(OH)₂D₃) on metabolic reprogramming and maturation of bone marrow-derived dendritic cells (BMDCs) from diabetic mouse. Six-week-old male C57BLKS/J-m⁺/m⁺ mice (CON) and C57BLKS/J-db/db mice (db/db) were fed with a 10% kcal fat diet for seven weeks. BMDCs were generated by culturing bone marrow cells from the mice with rmGM-CSF (20 ng/mL) in the absence or presence of 10 nM 1,25(OH)₂D₃. The maturation of BMDCs was induced via lipopolysaccharide (LPS, 50 ng/mL) stimulation for 24 h. LPS stimulation induced iNOS protein expression and decreased the mitochondrial respiration, while increased lactate production and the expression of glycolytic pathway-related genes (Glut1 and Pfkfb3) in BMDCs from both CON and db/db groups. In LPS-stimulated mature BMDCs, 1,25(OH)₂D₃ treatment decreased the expression of surface markers related to immunostimulatory functions (MHC class II, CD80, CD86, and CD40) and production of IL-12p70 in both CON and db/db groups. While the mRNA level of the gene related to glucose uptake (Glut1) was increased in both groups, lactate production was decreased by 1,25(OH)₂D₃ treatment. mTORC1 activity was suppressed following 1,25(OH)₂D₃ treatment. Collectively, our findings confirmed that metabolic reprogramming occurred in BMDCs following LPS stimulation. In vitro 1,25(OH)₂D₃ treatment induced tolerogenic phenotypes by reducing the expression of surface markers, as well as cytokine production. However, no significant difference was observed regarding the effects of 1,25(OH)₂D₃ treatment on metabolic conversion and maturation of BMDCs between the control and diabetic mice. Additionally, the decreased aerobic glycolysis induced by the 1,25(OH)₂D₃ treatment appeared to be associated with the diminished maturation of BMDCs, and mTORC1 appears to play a key role in the 1,25(OH)₂D₃-mediated regulation of glycolysis.

Vitamin D and the Kidney: Two Players, One Console

Vitamin D belongs to the group of liposoluble steroids mainly involved in bone metabolism by modulating calcium and phosphorus absorption or reabsorption at various levels, as well as parathyroid hormone production. Recent evidence has shown the extra-bone effects of vitamin D, including glucose homeostasis, cardiovascular protection, and anti-inflammatory and antiproliferative effects. This narrative review provides an overall view of vitamin D’s role in different settings, with a special focus on chronic kidney disease and kidney transplant.

Vitamin D and colorectal cancer - A practical review of the literature

Colorectal cancer (CRC) is the third leading cause of cancer-related mortality in the United States and the second cause worldwide. Its incidence rates have been decreasing in the overall population in the US in the past few decades, but with increasing rates in the population younger than 50 years old. Environmental factors are supposed to be involved in the development of the disease, with strong evidence favoring an influence of the diet and lifestyle. A diet high in red meat and calories, and low in fiber, fruits and vegetables increases the risk of CRC, as well as physical inactivity. The influence of low calcium intake and low levels of vitamin D on the risk of the disease and on the clinical outcomes of CRC patients has also been investigated. Hypovitaminosis D has been highly prevalent worldwide and associated with several chronic diseases, including malignancies. Vitamin D is a steroid hormone with the main function of regulating bone metabolism, but with many other physiological functions, such as anti-inflammatory, immunomodulatory, and antiangiogenic effects, potentially acting as a carcinogenesis inhibitor. In this review, we aim to describe the relation of vitamin D with malignant diseases, mainly CRC, as well as to highlight the results of the studies which addressed the potential role of vitamin D in the development and progression of the disease. In addition, we will present the results of the pivotal randomized clinical trials that evaluated the impact of vitamin D supplementation on the clinical outcomes of patients with CRC.

The Impact of Exosomes/Microvesicles Derived from Myeloid Dendritic Cells Cultured in the Presence of Calcitriol and Tacalcitol on Acute B-Cell Precursor Cell Lines with MLL Fusion Gene

Vitamin D analogs (VDAs) may directly inhibit the growth of normal and malignant (derived from acute lymphoblastic leukemia (ALL)) B cells, as both types of cells express vitamin D receptor (VDR). We performed anti-proliferative, morphology tests and phenotyping to evaluate the sensitivity of monocytes and iDCs (immature myeloid-derived dendritic cells) on calcitriol and tacalcitol treatment, phenotyping, morphology, and size distribution measurement to determine the characteristics of microvesicles (MVs) and exosomes (EXs) derived from them and, finally, phenotyping and Elisa test to determine the effects of VDAs on modulation of the phenotype of B cells through extracellular vesicles (EVs) released by iDCs. Our results confirmed that both SC cells and iDCs were sensitive to the VDAs and showed altered surface expression of markers associated with monocyte differentiation, which was resulting in the phenotypic changes in EVs derived from them. We also showed that obtained EVs could change the morphology and phenotype of ALL-B-derived precursor cells in a different way, depending on their origin. The differential effect of VDAs on ALL-B cells, which was associated with increased or decreased expression of CD27, CD24, CD38, and CD23 expression, was observed. Hence, further studies to explain the modulation in the composition of EVs by VDAs are required.

Autoimmune disease and interconnections with vitamin D

Vitamin D has well-documented effects on calcium homeostasis and bone metabolism but recent studies suggest a much broader role for this secosteroid in human health. Key components of the vitamin D system, notably the vitamin D receptor (VDR) and the vitamin D-activating enzyme (1α-hydroxylase), are present in a wide array of tissues, notably macrophages, dendritic cells and T lymphocytes (T cells) from the immune system. Thus, serum 25-hydroxyvitamin D (25D) can be converted to hormonal 1,25-dihydroxyvitamin D (1,25D) within immune cells, and then interact with VDR and promote transcriptional and epigenomic responses in the same or neighbouring cells. These intracrine and paracrine effects of 1,25D have been shown to drive antibacterial or antiviral innate responses, as well as to attenuate inflammatory T cell adaptive immunity. Beyond these mechanistic observations, association studies have reported the correlation between low serum 25D levels and the risk and severity of human immune disorders including autoimmune diseases such as inflammatory bowel disease, multiple sclerosis, type 1 diabetes and rheumatoid arthritis. The proposed explanation for this is that decreased availability of 25D compromises immune cell synthesis of 1,25D leading to impaired innate immunity and over-exuberant inflammatory adaptive immunity. The aim of the current review is to explore the mechanistic basis for immunomodulatory effects of 25D and 1,25D in greater detail with specific emphasis on how vitamin D-deficiency (low serum levels of 25D) may lead to dysregulation of macrophage, dendritic cell and T cell function and increase the risk of inflammatory autoimmune disease.

The Immunologic Profile of Vitamin D and Its Role in Different Immune-Mediated Diseases: An Expert Opinion

Historically, vitamin D is recognized as an essential component for the maintenance of the musculoskeletal system. The immunomodulatory role of vitamin D in health and disease has gained much interest in recent years due to the many pathologies that share underlying immunological features where vitamin D has been shown to exert a potential role. Evidence from pre-clinical studies show that vitamin D elicits biological effects on both the innate and adaptive immune systems. Furthermore, in vivo studies have shown that administration of vitamin D can lead to changes in or the development of a range of immune-related diseases. This encourages the hypothesis that data derived from clinical and epidemiological studies connect vitamin D with the incidence and severity of many immune-mediated disorders such as rheumatoid arthritis, diabetes, and infectious diseases. Since some other immune-mediated diseases share similar features to that of viral infection such as COVID-19, in this review, we examined these other areas and the role of vitamin D in these diseases.

The Effects of 1,25(OH)2D3 treatment on Immune Responses and Intracellular Metabolic Pathways of Bone Marrow-Derived Dendritic Cells from Lean and Obese Mice

Vitamin D affects differentiation, maturation, and activation of dendritic cells (DCs). Obesity-related immune dysfunction is associated with metabolic changes in immune cells. Objectives of the study are to investigate the effects of vitamin D and obesity on immune responses and markers related to immunometabolism of bone marrow-derived dendritic cells (BMDCs). Bone marrow cells (BMCs) were isolated from lean and obese mice, and BMDCs were generated by culturing BMCs with rmGM-CSF. BMDCs were treated with 1 or 10 nM of 1,25-dihydroxyvitamin D3 (1,25(OH)2D3), and maturation was induced by LPS (50 ng/mL) stimulation for 24 h. Cell phenotypes, cytokine productions, and expression of proteins and genes involved in Akt/mTOR signaling pathway and glycolytic pathway were determined. 1,25(OH)2D3 treatment inhibited differentiation of BMDCs (CD11c⁺ %), expression of phenotypes related with DC function (MHC class II and CD86) and production of IL-12p70 in both lean and obese mice. The expression of PD-L1 and the ratio of IL-10/IL-12p70 were increased by 1,25(OH)2D3. With 1,25(OH)2D3 treatment, Akt/mTOR signaling pathway was suppressed, and expression of genes related to glycolysis (Glut1, Pfkfb4, Hif1A) was increased. The upregulation of glycolysis-related genes observed with 1,25(OH)2D3 treatment seems to be associated with the induction of tolerogenic features of BMDCs from lean and obese mice, and Hif1A seems to have a potential role in conveying the effect of 1,25(OH)2D3 on glycolysis. This article is protected by copyright. All rights reserved.

Seasonal Variations in the Diagnosis of Testicular Germ Cell Tumors: A National Cancer Registry Study in Austria

Simple Summary

Seasonal variations in cancer diagnosis could already be demonstrated in prostate and breast cancer. The reasons for this observed seasonal pattern are still unclear. The health care system or other determinants such as the protective function of vitamin D3 in carcinogenesis could be assumed as one explanation. Testicular germ cell tumors are the most common developed malignancy among young men. The aim of our study was to investigate, for the first time, the seasonal variations in the clinical diagnosis of testicular germ cell tumors. We have been able to confirm that the frequency of monthly newly diagnosed cases of testicular cell tumors in Austria has a strong seasonality, with a significant reduction in the tumor incidence during the summer months and an increase during the winter months.

Abstract

We conducted a retrospective National Cancer Registry study in Austria to assess a possible seasonal variation in the clinical diagnosis of testicular germ cell tumors (TGCT). In total, 3615 testicular cancer diagnoses were identified during an 11-year period from 2008 to 2018. Rate ratios for the monthly number of TGCT diagnoses, as well as of seasons and half-years, were assessed using a quasi-Poisson model. We identified, for the first time, a statistically significant seasonal trend (p < 0.001) in the frequency of monthly newly diagnosed cases of TGCT. In detail, clear seasonal variations with a reduction in the tumor incidence during the summer months (Apr–Sep) and an increase during the winter months (Oct–Mar) were observed (p < 0.001). Focusing on seasonality, the incidence during the months of Oct–Dec (p = 0.008) and Jan–Mar (p < 0.001) was significantly higher compared to the months of Jul–Sep, respectively. Regarding histopathological features, there is a predominating incidence in the winter months compared to summer months, mainly concerning pure seminomas (p < 0.001), but not the non-seminoma or mixed TGCT groups. In conclusion, the incidence of TGCT diagnoses in Austria has a strong seasonal pattern, with the highest rate during the winter months. These findings may be explained by a delay of self-referral during the summer months. However, the hypothetical influence of vitamin D3 in testicular carcinogenesis underlying seasonal changes in TGCT diagnosis should be the focus of further research.

Pharmacological Modulation of Immune Responses by Nutritional Components

The incidence of noncommunicable diseases (NCDs) has increased over the last few decades, and one of the major contributors to this is lifestyle, especially diet. High intake of saturated fatty acids and low intake of dietary fiber is linked to an increase in NCDs. Conversely, a low intake of saturated fatty acids and a high intake of dietary fiber seem to have a protective effect on general health. Several mechanisms have been identified that underlie this phenomenon. In this review, we focus on pharmacological receptors, including the aryl hydrocarbon receptor, binding partners of the retinoid X receptor, G-coupled protein receptors, and toll-like receptors, which can be activated by nutritional components and their metabolites. Depending on the nutritional component and the receptors involved, both proinflammatory and anti-inflammatory effects occur, leading to an altered immune response. These insights may provide opportunities for the prevention and treatment of NCDs and their inherent (sub)chronic inflammation. SIGNIFICANCE STATEMENT: This review summarizes the reported effects of nutritional components and their metabolites on the immune system through manipulation of specific (pharmacological) receptors, including the aryl hydrocarbon receptor, binding partners of the retinoid X receptor, G-coupled protein receptors, and toll-like receptors. Nutritional components, such as vitamins, fibers, and unsaturated fatty acids are able to resolve inflammation, whereas saturated fatty acids tend to exhibit proinflammatory effects. This may aid decision makers and scientists in developing strategies to decrease the incidence of noncommunicable diseases.

Metabolic reprogramming of myeloid-derived suppressor cells: An innovative approach confronting challenges

Immune cells such as T cells, macrophages, dendritic cells, and other immunoregulatory cells undergo metabolic reprogramming in cancer and inflammation-derived microenvironment to meet specific physiologic and functional demands. Myeloid-derived suppressor cells (MDSCs) are a heterogeneous population of immature myeloid cells that are characterized by immunosuppressive activity, which plays a key role in host immune homeostasis. In this review, we have discussed the core metabolic pathways, including glycolysis, lipid and fatty acid biosynthesis, and amino acid metabolism in the MDSCs under various pathologic situations. Metabolic reprogramming is a determinant of the phenotype and functions of MDSCs, and is therefore a novel therapeutic possibility in various diseases.

Reviewing the Significance of Vitamin D Substitution in Monoclonal Gammopathies

Vitamin D is a steroid hormone that is essential for bone mineral metabolism and it has several other effects in the body, including anti-cancer actions. Vitamin D causes a reduction in cell growth by interrupting the cell cycle. Moreover, the active form of vitamin D, i.e., 1,25-dihydroxyvitamin D, exerts various effects via its interaction with the vitamin D receptor on the innate and adaptive immune system, which could be relevant in the onset of tumors. Multiple myeloma is a treatable but incurable malignancy characterized by the growth of clonal plasma cells in protective niches in the bone marrow. In patients affected by multiple myeloma, vitamin D deficiency is commonly correlated with an advanced stage of the disease, greater risk of progression, the development of pathological fractures, and a worse prognosis. Changes in the vitamin D receptor often contribute to the occurrence and progress of deficiencies, which can be overcome by supplementation with vitamin D or analogues. However, in spite of the findings available in the literature, there is no clear standard of care and clinical practice varies. Further research is needed to better understand how vitamin D influences outcomes in patients with monoclonal gammopathies.

The dark side of daylight: photoaging and the tumor microenvironment in melanoma progression

Continued thinning of the atmospheric ozone, which protects the earth from damaging ultraviolet radiation (UVR), will result in elevated levels of UVR reaching the earth's surface, leading to a drastic increase in the incidence of skin cancer. In addition to promoting carcinogenesis in skin cells, UVR is a potent extrinsic driver of age-related changes in the skin known as "photoaging." We are in the preliminary stages of understanding of the role of intrinsic aging in melanoma, and the tumor-permissive effects of photoaging on the skin microenvironment remain largely unexplored. In this Review, we provide an overview of the impact of UVR on the skin microenvironment, addressing changes that converge or diverge with those observed in intrinsic aging. Intrinsic and extrinsic aging promote phenotypic changes to skin cell populations that alter fundamental processes such as melanogenesis, extracellular matrix deposition, inflammation, and immune response. Given the relevance of these processes in cancer, we discuss how photoaging might render the skin microenvironment permissive to melanoma progression.

Monocytic Cytokines in Autoimmune Polyglandular Syndrome Type 2 Are Modulated by Vitamin D and HLA-DQ

Context

Autoimmune polyglandular syndrome (APS-2: autoimmune Addison’s disease or type 1 diabetes) is conferred by predisposing HLA molecules, vitamin D deficiency, and heritable susceptibility. Organ destruction is accompanied by cytokine alterations. We addressed the monocytic cytokines of two distinct APS-2 cohorts, effects of vitamin D and HLA DQ risk.

Methods

APS-2 patients (n = 30) and healthy controls (n = 30) were genotyped for HLA DQA1/DQB1 and their CD14+ monocytes stimulated with IL1β and/or 1,25(OH)₂D₃ for 24 h. Immune regulatory molecules (IL-6, IL-10, IL-23A, IL-15, CCL-2, PD-L1), vitamin D pathway gene transcripts (CYP24A1, CYP27B1, VDR), and CD14 were analyzed by enzyme-linked immunosorbent assay and RTqPCR.

Results

Pro-inflammatory CCL-2 was higher in APS-2 patients than in controls (p = 0.001), whereas IL-6 showed a trend – (p = 0.1). In vitro treatment with 1,25(OH)₂D₃ reduced proinflammatory cytokines (IL-6, CCL-2, IL-23A, IL-15) whereas anti-inflammatory cytokines (IL-10 and PD-L1) rose both in APS-type 1 diabetes and APS-Addison´s disease. Patients with adrenal autoimmunity showed a stronger response to vitamin D. Expression of IL-23A and vitamin D pathway genes VDR and CYP27B1 varied by HLA genotype and was lower in healthy individuals with high-risk HLA (p = 0.0025; p = 0.04), while healthy controls with low-risk HLA showed a stronger IL-10 and CD14 expression (p = 0.01; p = 0.03).

Conclusion

1,25(OH)₂D₃ regulates the monocytic response in APS-2 disorders type 1 diabetes or Addison´s disease. The monocytic cytokine profile of individuals carrying HLA high-risk alleles is proinflammatory, enhances polyglandular autoimmunity and can be targeted by vitamin D.

Evaluation of immunomodulatory effects of Boswellia sacra essential oil on T-cells and dendritic cells

BACKGROUND

Boswellia sacra resin has been commonly used as analgesic, antimicrobial, and anti-inflammatory properties, which reflect its immunomodulatory activity. Dendritic cells (DCs) are specialized antigen-presenting cells (APCs) and sentinel cells that regulate the immune response. This study aims at investigating whether crude essential oil extracted from Boswellia sacra resin (BSEO), has a potential effect on the phenotype and functions of human monocyte-derived DCs.

METHODS

Oil extract from the resin of Boswellia sacra was prepared by hydrodistillation using a custom made hydrodistiller. BSEO-mediated cell viability has been initially studied on human skin dermis cells (HSD) and DC precursors using quantitative and qualitative assays before applying on DCs. Human DCs were generated from differentiated peripheral blood monocytes cultured in media containing both GM-CSF and IL-4. DCs were exposed to 5 μg/mL or 10 μg/mL of BSEO in vitro. Morphological, phonotypical, and functional properties studied with microscopy, flow cytometry, and ELISA.

RESULTS

Crude BSEO was found to interfere with the maturation and differentiation of DCs from precursor cells in the presence or absence of lipopolysaccharide (LPS). BSEO-treated DCs, cultured in the presence of LPS, reduced the ability of allogeneic T cells to proliferate compared to that co-cultured with LPS-stimulated DCs only. In addition, the endocytic capacity and secretion of IL-10 by DCs treated with BSEO was enhanced in comparison to LPS treated cells. Analysis of the chemical composition of BESO using GC-MS (Clarus 500 GC/MS, PerkinElmer, Shelton, CT) revealed the presence of compounds with several biological activities including antibacterial, antioxidant, and anti-inflammatory properties.

CONCLUSION

Results indicated that BSEO deviates the differentiation of monocytes into immature DCs. Furthermore, stimulation of immature DCs with BSEO was unable to generate full DC maturation. However, these findings may potentially be employed to generate DCs with tolerogenic properties that are able to induce tolerance in diseases with hypersensitivity, autoimmunity as well as transplantation.

Vitamin D3 receptor polymorphisms regulate T cells and T cell-dependent inflammatory diseases

It has proven difficult to identify the underlying genes in complex autoimmune diseases. Here, we use forward genetics to identify polymorphisms in the vitamin D receptor gene (Vdr) promoter, controlling Vdr expression and T cell activation. We isolated these polymorphisms in a congenic mouse line, allowing us to study the immunomodulatory properties of VDR in a physiological context. Congenic mice overexpressed VDR selectively in T cells, and thus did not suffer from calcemic effects. VDR overexpression resulted in an enhanced antigen-specific T cell response and more severe autoimmune phenotypes. In contrast, vitamin D3-deficiency inhibited T cell responses and protected mice from developing autoimmune arthritis. Our observations are likely translatable to humans, as Vdr is overexpressed in rheumatic joints. Genetic control of VDR availability codetermines the proinflammatory behavior of T cells, suggesting that increased presence of VDR at the site of inflammation might limit the antiinflammatory properties of its ligand.

The effects of 1,25-dihydroxyvitamin D3 on markers related to the differentiation and maturation of bone marrow-derived dendritic cells from control and obese mice

Vitamin D has been reported to regulate the maturation and function of dendritic cells (DCs). Obesity was shown to be associated with the dysregulation of vitamin D metabolism and malfunction of DCs. We investigated the effects of in vitro 1,25(OH)₂D₃ treatment (0, 1, or 10 nM) on phenotype and expression of genes related to function of bone marrow-derived DCs (BMDCs) from control and obese mice. C57BL/6 N mice were fed a control or high-fat (10% or 45% kcal fat: CON or HFD) diets for 15 weeks. Differentiation toward DCs was induced with GM-CSF (20 ng/ml) and maturation was induced by LPS (50 ng/ml); 10 nM 1,25(OH)₂D₃ treatment inhibited BMDC differentiation (CD11c⁺) and decreased the percentage of mature DCs (MHCII^highCD11c⁺ and CD86^highCD11c⁺) in both CON and HFD groups. The Il10 expression in stimulated BMDCs from the CON group increased with the 10 nM 1,25(OH)₂D₃ treatment, but not in those from the HFD group. The Il12b mRNA levels in stimulated BMDCs were lower in the HFD group than in the CON group. In conclusion, lower levels of Cd 40, Cd83 and Il12 mRNA in LPS-stimulated BMDCs from obese mice suggest malfunction of DCs as antigen presenting cells. 1,25(OH)₂D₃ treatment inhibited the differentiation and maturation of BMDCs in both control and obese mice. Differential effects of 1,25(OH)₂D₃ on the expression of Il10 between control and obese mice suggest that regulation of immune response by vitamin D could be influenced by obesity.

Immunomodulatory Effects of Vitamin D in Thyroid Diseases

Vitamin D is a secosteroid with a pleiotropic role in multiple physiological processes. Besides the well-known activity on bone homeostasis, recent studies suggested a peculiar role of vitamin D in different non-skeletal pathways, including a key role in the modulation of immune responses. Recent evidences demonstrated that vitamin D acts on innate and adaptative immunity and seems to exert an immunomodulating action on autoimmune diseases and cancers. Several studies demonstrated a relationship between vitamin D deficiency, autoimmune thyroid disorders, and thyroid cancer. This review aims to summarize the evidences on the immunomodulatory effect of vitamin D on thyroid diseases.

Pathophysiological Role and Therapeutic Implications of Vitamin D in Autoimmunity: Focus on Chronic Autoimmune Diseases

Vitamin D is a pleiotropic secosteroid yielding multiple actions in human physiology. Besides the canonical regulatory activity on bone metabolism, several non-classical actions have been described and the ability of vitamin D to partake in the regulation of the immune system is particularly interesting, though far stronger and convincing evidence has been collected in in vitro as compared to in vivo studies. Whether vitamin D is able to regulate at physiological concentrations the human immune system remains unproven to date. Consequently, it is not established if vitamin D status is a factor involved in the pathogenesis of immune-mediated diseases and if cholecalciferol supplementation acts as an adjuvant for autoimmune diseases. The development of autoimmunity is a heterogeneous process, which may involve different organs and systems with a wide range of clinical implications. In the present paper, we reviewed the current evidences regarding vitamin D role in the pathogenesis and management of different autoimmune diseases.

Recent discoveries in dendritic cell tolerance-inducing pharmacological molecules

Dendritic cells (DCs) represent one of the most important biological tools for cellular immunotherapy purposes. There are an increasing number of phase I and II studies, where regulatory or tolerogenic DCs (TolDCs) are utilized as negative vaccines, with the aim of inducing tolerogenic outcomes in patients with various autoimmune or chronic-inflammatory diseases, as well as in transplant settings. The induction of tolerogenic properties in DCs can be achieved by altering their activation state toward expression of immunosuppressive elements and/or by achieving resistance to maturation, which leads to insufficient co-stimulatory signal delivery and inability to efficiently present antigens. In the past, one of the most efficient ways to induce DC tolerance has been the application of selected pharmacological agents which actively induce a tolerogenic transcription program or inhibit major pro-inflammatory transcription factors such as Nf-κB. Important examples include immunosuppressants such as different corticosteroids, vitamin D₃, rapamycin and others. The quality of TolDCs induced by different approaches is becoming a vital issue and recent evidence suggests substantial heterogeneity between variously-generated TolDCs as evidenced by their transcriptomic profile and function. The possibility of various "flavors" of TolDCs encourages future research in discovery of Tol-DC inducing agents to enrich various ways of DC manipulation. This would enable a broader range of tools to manipulate DC toward specific characteristics desirable in different disease settings. In recent years, several novel small molecules have been identified with the capacity to promote DC tolerogenic characteristics. In this review, we will present and discuss these novel findings and also highlight novel understandings of tolerogenic mechanisms by which DC tolerogenicity is induced by already established agents.

Calcitriol suppresses lipopolysaccharide-induced alveolar bone damage in rats by regulating T helper cell subset polarization

BACKGROUND

Although the immunomodulatory properties of calcitriol in bone metabolism have been documented for decades, its therapeutic role in the management of periodontitis remains largely unexplored. In this study, we hypothesized that calcitriol suppresses lipopolysaccharide (LPS)-induced alveolar bone loss by regulating T helper (Th) cell subset polarization.

METHODS

To test this hypothesis, we determined the effect of calcitriol intervention on the development of LPS-induced periodontitis in rats in terms of bone loss (micro-CT analysis), local inflammatory infiltration levels, the number of osteoclasts (hematoxylin and eosin staining) and the level of osteoclastogenesis (tartrate-resistant acid phosphatase method). Furthermore, immunohistochemistry was used to assess the expression levels of the receptor activator of NF-κB ligand (RANKL) and osteoprotegerin (OPG) as well as the cytokine levels of interferon-γ (IFN-γ), interleukin-4 (IL-4), IL-17, and IL-10 throughout the LPS-injected region. Finally, the polarization potential of Th cells in peripheral blood was analyzed using flow cytometry.

RESULTS

Calcitriol intervention decreased alveolar bone loss in response to LPS injection and inflammatory cell infiltration. Analysis of osteoclast number and RANKL and OPG expression showed that bone resorption activity was largely suppressed in response to calcitriol administration, along with decreased IL-17 levels but increased IL-4 and IL-10 levels in periodontal tissues (the LPS-injected region). Similarly, the percentages of Th2 and Treg cells in peripheral blood increased, but the percentages of Th1 and Th17 cells decreased in rats receiving calcitriol.

CONCLUSION

Our findings suggest that calcitriol can be used to inhibit bone loss in experimental periodontitis, likely via the regulation of local and systemic Th cell polarization.

Immunomodulatory Effects of Vitamin D in Pregnancy and Beyond

In addition to its role in calcium homeostasis and bone formation, a modulatory role of the active form of vitamin D on cells of the immune system, particularly T lymphocytes, has been described. The effects of vitamin D on the production and action of several cytokines has been intensively investigated in recent years. In this connection, deficiency of vitamin D has been associated with several autoimmune diseases, including rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), antiphospholipid syndrome (APS), Hashimoto Thyroiditis (HT), and multiple sclerosis (MS). In a successful pregnancy, the maternal immune response needs to adapt to accommodate the semiallogeneic fetus. Disturbances in maternal tolerance are implicated in infertility and pregnancy complications such as miscarriages (RM) and preeclampsia (PE). It is well-known that a subset of T lymphocytes, regulatory T cells (Tregs) exhibit potent suppressive activity, and have a crucial role in curtailing the destructive response of the immune system during pregnancy, and preventing autoimmune diseases. Interestingly, vitamin D deficiency is common in pregnant women, despite the widespread use of prenatal vitamins, and adverse pregnancy outcomes such as RM, PE, intrauterine growth restriction have been linked to hypovitaminosis D during pregnancy. Research has shown that autoimmune diseases have a significant prevalence within the female population, and women with autoimmune disorders are at higher risk for adverse pregnancy outcomes. Provocatively, dysregulation of T cells plays a crucial role in the pathogenesis of autoimmunity, and adverse pregnancy outcomes where these pathologies are also associated with vitamin D deficiency. This article reviews the immunomodulatory role of vitamin D in autoimmune diseases and pregnancy. In particular, we will describe the role of vitamin D from conception until delivery, including the health of the offspring. This review highlights an observational study where hypovitaminosis D was correlated with decreased fertility, increased disease activity, placental insufficiency, and preeclampsia in women with APS.

Antimicrobial and Immune-Modulatory Effects of Vitamin D Provide Promising Antibiotics-Independent Approaches to Tackle Bacterial Infections - Lessons Learnt from a Literature Survey

Antimicrobial multidrug-resistance (MDR) constitutes an emerging threat to global health and makes the effective prevention and treatment of many, particularly severe infections challenging, if not impossible. Many antibiotic classes have lost antimicrobial efficacy against a plethora of infectious agents including bacterial species due to microbial acquisition of distinct resistance genes. Hence, the development of novel anti-infectious intervention strategies including antibiotic-independent approaches is urgently needed. Vitamins such as vitamin D and vitamin D derivates might be such promising molecular candidates to combat infections caused by bacteria including MDR strains. Using the Pubmed database, we therefore performed an in-depth literature survey, searching for publications on the antimicrobial effect of vitamin D directed against bacteria including MDR strains. In vitro and clinical studies between 2009 and 2019 revealed that vitamin D does, in fact, possess antimicrobial properties against both Gram-positive and Gram-negative bacterial species, whereas conflicting results could be obtained from in vivo studies. Taken together, the potential anti-infectious effects for the antibiotic-independent application of vitamin D and/or an adjunct therapy in combination with antibiotic compounds directed against infectious diseases such as tuberculosis, H. pylori infections, or skin diseases, for instance, should be considered and further investigated in more detail.

Effect of single-dose injection of vitamin D on immune cytokines in ulcerative colitis patients: a randomized placebo-controlled trial

Ulcerative colitis (UC) is a chronic recurrent inflammation of the colon. It has been proposed that the UC pathogenesis may be related to vitamin D deficiency and/or vitamin D administration in UC patients may have an ameliorating effect on the intestinal inflammation. The aim of this study was to assess the effect of vitamin D on the serum levels of immune cytokines in UC patients. In this double-blind randomized controlled trial, 90 mild-to-moderate UC patients were assigned to get either a single muscular injection of 7.5 mg vitamin D3 or 1 mL normal saline as placebo. Three months later serum levels of IL-4, IL-10, IL-12p70, IFN-γ, and TNF-α were measured. Two group variables were compared using independent t-test and analysis of covariance (ANCOVA). There was a significant increase in vitamin D only in the vitamin D group. Compared to placebo, vitamin D had significant decreasing effects on serum TNF-α, IFN-γ, and IL12p70 levels, but it had no significant effect on serum levels of IL4 and IL10. Vitamin D seems to inhibit Th1 immune responses and have no effect on Th2 responses. The findings of this study support several in vitro studies, which suggest a therapeutic immunomodulatory potential of vitamin D.

Metabolic Regulation of Dendritic Cell Differentiation

Dendritic cells (DCs) are important antigen-presenting cells (APCs) that play essential roles in bridging innate and adaptive immune responses. Differentiation stages of DC subsets from bone marrow progenitor cells have been well-defined during the past decades. Features that distinguish DC progenitor cells from each differentiation stages, related signaling pathways and transcription factors that are crucial for DC lineage commitment have been well-elucidated in numerous studies. Recently, growing evidence are showing that cellular metabolism, as one of the most fundamental process of cells, has essential role in the modulation of immune system. There have been multiple reports and reviews that focus on the metabolic modulations on DC functions, however little attention had been paid to the metabolic regulation of DC development and differentiation. In recent years, increasing evidence suggests that metabolic regulations also exert significant impact on DC differentiation, as well as on the homeostasis of tissue resident DCs. The focus of this review is to summarize the findings from recent studies on the metabolic regulation of DC differentiation and to discuss the impacts of the three major aspects of metabolism on the processes of DC development and differentiation, namely the changes in metabolic pathways, the molecular signaling pathways that modulate cell metabolism, and the effects of metabolites and nutrients. The aim of this review is to draw attentions to this important and exciting research field where the effects of metabolic process and their regulation in DC differentiation need to be further explored.

New Insights on Low Vitamin D Plasma Concentration as a Potential Cardiovascular Risk Factor

The role of Vitamin D hormone in human health and disease is still debated. Recently, growing attention has been paid to its putative role in cardiovascular system homeostasis with several studies that suggested a correlation between low vitamin D levels and increased cardiovascular risk. Several mechanisms are involved in the development of cardiovascular diseases: systemic inflammation, endothelial dysfunction, arterial hypertension and insulin resistance. In the present paper, we have revised the current literature supporting a role for vitamin D in the development of these pathogenetic processes. Finally, we have evaluated the current evidence linking vitamin D to atherosclerosis and its natural consequence, cardiovascular diseases.

Vitamin D: Effect on Haematopoiesis and Immune System and Clinical Applications

Vitamin D is a steroid-like hormone which acts by binding to vitamin D receptor (VDR). It plays a main role in the calcium homeostasis and metabolism. In addition, vitamin D display other important effects called “non-classical actions.” Among them, vitamin D regulates immune cells function and hematopoietic cells differentiation and proliferation. Based on these effects, it is currently being evaluated for the treatment of hematologic malignancies. In addition, vitamin D levels have been correlated with patients’ outcome after allogeneic stem cell transplantation, where it might regulate immune response and, accordingly, might influence the risk of graft-versus-host disease. Here, we present recent advances regarding its clinical applications both in the treatment of hematologic malignancies and in the transplant setting.

The vitamin D3 analog, maxacalcitol, reduces psoriasiform skin inflammation by inducing regulatory T cells and downregulating IL-23 and IL-17 production

BACKGROUND

Psoriasis is a Th1/Th17-mediated inflammatory dermatosis treated with topical corticosteroids and vitamin D₃ analogs (VD3 As).

OBJECTIVE

To compare the effects of a VD3 A maxacalcitol and betamethasone valerate (BV) steroid lotion on topical imiquimod (IMQ)-induced psoriasiform skin inflammation.

METHODS

Female BALB/c mice were treated with vehicle, maxacalcitol or BV lotion on the skin for 3 days, and IMQ cream for 6 days. q-PCR, H&E, immunohistochemistry and immunofluorescence studies were performed on skin samples. Additionally, mice were treated with vehicle, maxacalcitol or BV lotion for 3 days and CD4⁺CD25⁺ regulatory T cells (Tregs) and CD4⁺CD25^- cells from each group were isolated from lymph nodes. Adoptive transfer of the cells was performed on recipient mice which were treated with IMQ cream for 6 days, and skin samples were obtained for q-PCR and H&E staining.

RESULTS

Maxacalcitol and BV were comparable in regards clinical improvement, although maxacalcitol reduced the MHC Class II⁺ inflammatory cell infiltration more than BV in IMQ skin. While both treatments downregulated IL-17 A, IL-17 F, IL-22, IL-12p40, TNF-α and IL-6 mRNA expression levels, only maxacalcitol downregulated IL-23p19 expression. Significantly increased Foxp3⁺ cell infiltrations and IL-10 expression were noted in maxacalcitol-treated IMQ skin. Adoptive transfer of Treg cells from maxacalcitol-treated donor mice improved IMQ-induced inflammation clinically and histopathologically more than the recipients of Treg cells from BV-treated donor groups, showing reduced levels of inflammatory cytokines and increased IL-10 expression.

CONCLUSION

These results indicate that maxacalcitol reduces psoriasiform skin inflammation by inducing Treg cells as well as downregulating IL-23 and IL-17 production.

Association between Sun Exposure, Vitamin D Intake, Serum Vitamin D Level, and Immunoglobulin G Level in Patients with Neuromyelitis Optica Spectrum Disorder

Background:

Neuromyelitis optica spectrum disorder (NMOSD) is a central nervous system inflammatory disorder in which immunoglobulin G (IgG) autoantibodies possibly play a pathogenic role against the aquaporin-4 water channel protein. Vitamin D may modulate B-cell function and decrease the IgG synthesis and may play a role in NMOSD as a crucial factor. The aim of this study was to investigate the relation between Vitamin D intakes from food, Vitamin D intake from sunlight exposure, blood Vitamin D levels, and IgG-neuromyelitis optica (NMO) level in serum of patients with NMOSD and NMO.

Method:

In this cross-sectional study, food Frequency Questionnaires (FFQ) and Sun Exposure Questionnaire (SEQ) were completed to evaluate of vitamin D intakes from food and sun light exposure. Moreover, serum levels of 25(OH) vitamin D3 and IgG-NMO were assessed in patients with NMOSD and NMO.

Results:

We assessed IgG-NMO levels in 29 patients with NMOSD that nine patients (n = 31%) were positive and for the rest it was negative. Sunlight exposure scale (P = 0.01) and 25(OH) D3 (P = 0.04) in IgG-NMO-negative patients were significantly more than patients with positive IgG-NMO. Age, gender, and latitude were not confounder variables. A positive significant correlation was observed between the sun exposure scale and serum levels of 25(OH) D3 in all participants (r = 0.747, P ≤ 0.001).

Conclusions:

Physiological variation in Vitamin D may apply a significant effect on IgG-NMO synthesis in patients with NMO. Vitamin D may have significant role in pathogenesis of NMOSD and NMO.

Role of Vitamin D Beyond the Skeletal Function: A Review of the Molecular and Clinical Studies

The classical function of Vitamin D, which involves mineral balance and skeletal maintenance, has been known for many years. With the discovery of vitamin D receptors in various tissues, several other biological functions of vitamin D are increasingly recognized and its role in many human diseases like cancer, diabetes, hypertension, cardiovascular, and autoimmune and dermatological diseases is being extensively explored. The non-classical function of vitamin D involves regulation of cellular proliferation, differentiation, apoptosis, and innate and adaptive immunity. In this review, we discuss and summarize the latest findings on the non-classical functions of vitamin D at the cellular/molecular level and its role in complex human diseases.

Vitamin D and tuberculosis: where next?

Tuberculosis (TB) has troubled mankind for millennia, but current treatment strategies are long and complicated and the disease remains a major global health problem. The risk of Mycobacterium tuberculosis (Mtb) infection or progression of active TB disease is elevated in individuals with vitamin D deficiency. High-dose vitamin D was used to treat TB in the preantibiotic era, and in vitro experimental data show that vitamin D supports innate immune responses that restrict growth of Mtb. Several randomized controlled trials have tested whether adjunctive vitamin D supplementation enhances the clinical and microbiological response to standard antimicrobial chemotherapy for pulmonary TB. The effects have been modest at best, and attention is turning to the question of whether vitamin D supplementation might have a role in preventing acquisition or reactivation of latent Mtb infection. In this article, we describe the effects of vitamin D on host immune responses to Mtb in vitro and in vivo and review the results of clinical trials in the field. We also reflect on the findings of clinical trials of vitamin D supplementation for the prevention of acute respiratory tract infections, and discuss how these findings might influence the design of future trials to evaluate the role of vitamin D in the prevention and treatment of TB.

Comparison of 25-hidroksi Vitamin D serum concentrations in patients with psoriasis and psoriatic arthritis

BACKGROUND AND OBJECTIVE

Rheumatoid arthritis (RA), insulin-dependent diabetes mellitus (IDDM), inflammatory bowel disease, systemic lupus erythematosus (SLE) and multiple sclerosis (MS) are some of the autoimmune diseases related to the decreases in Vitamin D levels. The same immunological properties as psoriasis, such as Th1/Th2 dysregulation, are seen in all of them. This study aims to compare 25-hidroksi Vitamin D (25-OHD) serum concentrations in patients with psoriasis and psoriatic arthritis.

METHODS

This study includes 91 outpatients; 48 of these patients were chosen randomly among the psoriasis (PS) patients from the dermatology department of the researchers' hospital. Forty-three of them were chosen among the psoriatic arthritis (PsA) patients matching the age and gender criteria from the rheumatology department of the researchers' hospital. In this study, 25-OHD serum concentrations among the psoriasis and psoriatic arthritis patients were compared.

RESULT

There are more patients in the PsA group with 25-OHD levels lower than 20 ng/ml; however, this finding is insufficient to obtain statistical significance (p= 0.09). PsA and psoriasis groups had similar numbers of patients with 25-OHD levels ranging from 20 to 30 mg/mL and those higher than 30 mg/mL (p> 0.05).

CONCLUSION

The literature does not show significant differences between the PS and PsA groups in terms of serum 25-OHD levels and a prevalence of Vitamin D deficiency. Besides, PASI scores were higher in the PS group. CRP values in the PsA group were higher than in the PS group. There was a poor negative correlation between CRP and serum 25-OHD levels in the PsA group. This correlation was not found in the PS group.

The Role of Toll-Like Receptors and Vitamin D in Cardiovascular Diseases-A Review

Cardiovascular diseases are the leading cause of mortality worldwide. Therefore, a better understanding of their pathomechanisms and the subsequent implementation of optimal prophylactic and therapeutic strategies are of utmost importance. A growing body of evidence states that low-grade inflammation is a common feature for most of the cardiovascular diseases in which the contributing factors are the activation of toll-like receptors (TLRs) and vitamin D deficiency. In this article, available data concerning the association of cardiovascular diseases with TLRs and vitamin D status are reviewed, followed by a discussion of new possible approaches to cardiovascular disease management.

Immunometabolism, pregnancy, and nutrition

The emerging field of immunometabolism has substantially progressed over the last years and provided pivotal insights into distinct metabolic regulators and reprogramming pathways of immune cell populations in various immunological settings. However, insights into immunometabolic reprogramming in the context of reproduction are still enigmatic. During pregnancy, the maternal immune system needs to actively adapt to the presence of the fetal antigens, i.e., by functional modifications of distinct innate immune cell subsets, the generation of regulatory T cells, and the suppression of an anti-fetal effector T cell response. Considering that metabolic pathways have been shown to affect the functional role of such immune cells in a number of settings, we here review the potential role of immunometabolism with regard to the molecular and cellular mechanisms necessary for successful reproduction. Since immunometabolism holds the potential for a therapeutic approach to alter the course of immune diseases, we further highlight how a targeted metabolic reprogramming of immune cells may be triggered by maternal anthropometric or nutritional aspects.

Inhibition of IL-17-committed T cells in a murine psoriasis model by a vitamin D analogue

BACKGROUND

A better understanding of the means by which topical vitamin D analogues exert their therapeutic effect on psoriasis is of theoretical and practical importance.

OBJECTIVE

We sought to clarify whether and how the topical vitamin D analogue calcipotriol (CAL) controls the IL-17A-mediated pathogenesis of murine psoriasis-like dermatitis in vivo.

METHODS

Psoriasis-like dermatitis was induced by the topical application of an imiquimod (IMQ)-containing cream on the murine ear for 4 to 6 consecutive days. For topical CAL treatment, mice were treated daily with CAL solution on the ear before IMQ application.

RESULTS

Mice treated topically with CAL exhibited much milder IMQ-induced psoriasis-like dermatitis compared with vehicle-treated mice, with impaired accumulation of IL-17A-committed T (T17) cells in the lesional skin. The IMQ-induced upregulation of Il12b and Il23a was marked in the epidermis and was abrogated by CAL application, suggesting CAL-mediated suppression of IL-23 expression. CAL inhibited Il12b and Il23a expression by Langerhans cells ex vivo stimulated with IMQ and CD40 cross-linking. Topical CAL also inhibited T17 cell expansion in the draining lymph nodes of IMQ-treated skin, implying a possible effect on T17 cell-mediated dermatitis at distant sites. In fact, topical CAL application on the IMQ-treated left ear resulted in amelioration of T17 cell accumulation and psoriasis-like dermatitis in the right ear subsequently treated with IMQ.

CONCLUSION

Topical CAL can exert its antipsoriatic effect on CAL-treated lesions and, concomitantly, distant lesions by attenuating the T17 cell accumulation in both CAL-treated lesions and draining lymph nodes.

Does vitamin D play a role in autoimmune endocrine disorders? A proof of concept

In the last few years, more attention has been given to the "non-calcemic" effect of vitamin D. Several observational studies and meta-analyses demonstrated an association between circulating levels of vitamin D and outcome of many common diseases, including endocrine diseases, chronic diseases, cancer progression, and autoimmune diseases. In particular, cells of the immune system (B cells, T cells, and antigen presenting cells), due to the expression of 1α-hydroxylase (CYP27B1), are able to synthesize the active metabolite of vitamin D, which shows immunomodulatory properties. Moreover, the expression of the vitamin D receptor (VDR) in these cells suggests a local action of vitamin D in the immune response. These findings are supported by the correlation between the polymorphisms of the VDR or the CYP27B1 gene and the pathogenesis of several autoimmune diseases. Currently, the optimal plasma 25-hydroxyvitamin D concentration that is necessary to prevent or treat autoimmune diseases is still under debate. However, experimental studies in humans have suggested beneficial effects of vitamin D supplementation in reducing the severity of disease activity. In this review, we summarize the evidence regarding the role of vitamin D in the pathogenesis of autoimmune endocrine diseases, including type 1 diabetes mellitus, Addison's disease, Hashimoto's thyroiditis, Graves' disease and autoimmune polyendocrine syndromes. Furthermore, we discuss the supplementation with vitamin D to prevent or treat autoimmune diseases.

Interferon alpha gene expression and serum level association with low vitamin D levels in Egyptian female patients with systemic lupus erythematosus

Background Patients with systemic lupus erythematosus (SLE) are prone to develop vitamin D (25(OH) D3) deficiency, due to several factors and there is an association between lower vitamin D levels and higher SLE disease activity. The aim of this research was to assess the prevalence of vitamin D deficiency in Egyptian female patients with SLE. Furthermore, we analyzed the potential relationship between this deficiency and SLE manifestations, disease activity, and its effect on interferon alpha (IFN-α) gene expression and serum level. Methods We evaluated the serum levels of vitamin D 25(OH)D3 and IFN-α by enzyme-linked immunosorbent assay (ELISA). IFN-α gene expression was measured by real-time polymerase chain reaction (PCR) assay in 123 Egyptian female patients with SLE and in 100 females as a healthy control group. Results Vitamin D deficiency was prevalent in 20.30%, while insufficiency was prevalent in 42.40% of the total group of patients. Serum levels of 25(OH)D3 were significantly decreased in the group of severe disease, and in the group of patients with lupus nephritis. 25(OH)D3 showed highly significant negative correlation with the SLE Disease Activity Index (SLEDAI) in the high activity group and lupus nephritis group. There was a significant negative correlation between 25(OH)D3 and IFN-α serum level and gene expression in all patients; more significant in the group with lupus nephritis. Conclusions The deficiency of 25(OH)D3 has a direct relationship with increase disease activity and nephritis in Egyptian SLE patients, suggesting the need for vitamin D supplementation in these patients. Also, it is directly correlated with increased secretion and gene expression of IFN-α, suggesting its role in pathogenesis of lupus nephritis, to be confirmed by further longitudinal observational studies.

1,25-Dihydroxyvitamin D3 suppressed experimental autoimmune encephalomyelitis through both immunomodulation and oligodendrocyte maturation

1,25-Dihydroxyvitamin D3 (1,25(OH)2D3) has recently been found to have the anti-inflammatory potential to suppress experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis; however, its direct effect on neural cells is not clear. In the current study we show that 1,25(OH)2D3 treatment effectively suppressed clinical signs of ongoing EAE and reduced inflammation and demyelination scores in the central nervous system (CNS). The treatment significantly decreased production/expression of pro-inflammatory cytokines IFN-γ, GM-CSF and IL-17A, while it increased anti-inflammatory cytokines IL-4 and IL-10. Further, 1,25(OH)2D3 treatment effectively elevated the numbers of neural stem cells, oligodendrocyte precursor cells, as well as oligodendrocytes in disease lesions in the CNS. These results, together with its in vitro effect of inducing oligodendrocyte differentiation as shown in our previous findings, demonstrate that 1,25(OH)2D3 suppressed EAE not only by its immunomodulatory capacity, but also by its effect on oligodendrocyte differentiation and maturation, and thus has potential for remyelination and neural repair.

Vitamin D and plasma cell dyscrasias: reviewing the significance

Monoclonal gammopathy of undetermined significance (MGUS) is a clonal plasma cell disorder and precursor disease to multiple myeloma and other related cancers. While MGUS is considered a benign disorder, with a low risk of disease progression, patients have altered bone microarchitecture and an increased risk of bone fracture. In addition, alterations in immune function are regularly found to correlate with disease activity. Vitamin D, an important hormone for bone and immune health, is commonly deficient in multiple myeloma patients. However, vitamin D deficiency is also prevalent in the general population. The purpose of this review is to highlight the current understanding of vitamin D in health and disease and to parallel this with a review of the abnormalities found in plasma cell dyscrasias. While some consensus statements have advocated for vitamin D testing and routine supplementation in MGUS, there is no clear standard of care approach and clinical practice patterns vary. Further research is needed to better understand how vitamin D influences outcomes in MGUS patients.

IL-36 Signaling Facilitates Activation of the NLRP3 Inflammasome and IL-23/IL-17 Axis in Renal Inflammation and Fibrosis

IL-36 cytokines are proinflammatory and have an important role in innate and adaptive immunity, but the role of IL-36 signaling in renal tubulointerstitial lesions (TILs), a major prognostic feature of renal inflammation and fibrosis, remains undetermined. In this study, increased IL-36α expression detected in renal biopsy specimens and urine samples from patients with renal TILs correlated with renal function impairment. We confirmed the increased expression of IL-36α in the renal tubular epithelial cells of a mouse model of unilateral ureteral obstruction (UUO) and related cell models using mechanically induced pressure, oxidative stress, or high mobility group box 1. In contrast, the kidneys of IL-36 receptor (IL-36R) knockout mice exhibit attenuated TILs after UUO. Compared with UUO-treated wild-type mice, UUO-treated IL-36 knockout mice exhibited markedly reduced NLRP3 inflammasome activation and macrophage/T cell infiltration in the kidney and T cell activation in the renal draining lymph nodes. In vitro, recombinant IL-36α facilitated NLRP3 inflammasome activation in renal tubular epithelial cells, macrophages, and dendritic cells and enhanced dendritic cell-induced T cell proliferation and Th17 differentiation. Furthermore, deficiency of IL-23, which was diminished in IL-36R knockout UUO mice, also reduced renal TIL formation in UUO mice. In wild-type mice, administration of an IL-36R antagonist after UUO reproduced the results obtained in UUO-treated IL-36R knockout mice. We propose that IL-36 signaling contributes to the pathogenesis of renal TILs through the activation of the NLRP3 inflammasome and IL-23/IL-17 axis.

Role of Vitamin D in Rheumatoid Arthritis

Vitamin D is a fat soluble hormone, with a well described role in bone health and calcium/phosphate metabolism. Recent evidences have related vitamin D to other physiological functions and pathological conditions. Specifically, vitamin D has widely proven activities on immune system and evidences suggest that it may be implicated in the pathogenesis of rheumatoid arthritis (RA). The relationship between vitamin D and RA is complex, also because a deficitary vitamin D status, which is very common in RA patients, can contribute to the increased risk of osteoporosis typical of RA. In this chapter, will be described and discussed the main aspects of the relationship between RA and vitamin D.

Metabolites: deciphering the molecular language between DCs and their environment

Dendritic cells (DCs) determine the outcome of the immune response based on signals they receive from the environment. Presentation of antigen under various contexts can lead to activation and differentiation of T cells for immunity or dampening of immune responses by establishing tolerance, primarily through the priming of regulatory T cells. Infections, inflammation and normal cellular interactions shape DC responses through direct contact or via cytokine signaling. Although it is widely accepted that DCs sense microbial components through pattern recognition receptors (PRRs), increasing evidence advocates for the existence of a set of signals that can profoundly shape DC function via PRR-independent pathways. This diverse group of host- or commensal-derived metabolites represents a newly appreciated code from which DCs can interpret environmental cues. In this review, we discuss the existing information on the effect of some of the most studied metabolites on DC function, together with the implications this may have in immune-mediated diseases.

Mesenchymal Stem Cells Upregulate the Expression of PD-L1 But Not VDR in Dendritic Cells

OBJECTIVE

Mesenchymal stem cells (MSCs) show immunomodulatory functions. But the exact mechanism underlying these activities of MSCs is still not completely understood. There have been a few studies which have assessed the effects of these cells on dendritic cells (DCs) function. Given the importance of programmed cell death receptor-1 (PD-L1) and vitamin D receptor (VDR) expression in induction of tolerance in DCs, we were encouraged to investigate if one of the immunomodulatory functions of MSCs could be inducing upregulation of PD-L1 and VDR on DCs or not.

METHODS

DCs were co-cultured with MSCs or treated with them in transwell plates in the presence or absence of Lipopolysaccharide (LPS). Expression of PD-L1 and VDR mRNA and proteins in treated DCs were assessed by Real-time PCR and Western blot techniques. Furthermore, treated DCs were co-cultured with allogeneic T-cells, and T-cell proliferation and cytokine secretions in co-culture supernatants were assessed.

RESULTS

The results showed that PD-L1 but not VDR expression is significantly upregulated in the DCs co-cultured with MSCs. Furthermore, cell-to-cell contact and also presence of maturation inducers like LPS is necessary for this function. Moreover, our results indicated that MSCs could induce tolerogenic DCs (TolDCs) which could decrease the secretion of IL-2 by T-cells and inhibit T-cell proliferation as well as increase secretion of IL-10.

CONCLUSIONS

Overall, our results show that MSCs may have several suppressive effects on immune responses by induction of TolDCs expressing more PD-L1 immunomodulatory molecule and change the cytokines profile of DCs and T-cells.

Decidual soluble factors, through modulation of dendritic cells functions, determine the immune response patterns at the feto-maternal interface

Dendritic cells (DCs) can acquire immunogenic or tolerogenic properties depending on intrinsic and tissue environmental factors. We aimed to determine the immunomodulatory effects of decidual soluble factors from abortion- and non-abortion-prone mice on DC functions. The decidual cell supernatants (DS) were obtained from abortion-prone and non-abortion-prone mice. Splenic DCs were treated with DS and conalbumin (as an antigen) and injected into the palms of the mice. After five days, regional lymph node cells were collected and cultured in the presence and absence of conalbumin. The proliferation of lymphocyte cells, the frequency of regulatory T cells (Tregs), and the production of IL-4 and IFN-γ were measured by [(3)H]thymidine incorporation, flow cytometry, and ELISA respectively. Our results indicated that DS from both abortion- and non-abortion-prone mice decreased the ability of DCs to induce lymphocyte proliferation and IFN-γ production, while enhanced their capacity to induce Tregs compared with non-treated DCs. Another important finding was that the immunosuppressive effects of DS from abortion-prone mice on DCs for inducing proliferative responses, developing Tregs, and producing IFN-γ by primed lymphocytes was less than DS from non-abortion-prone mice. We also found that only DS from non-abortion-prone mice could enhance the capacity of DCs to induce IL-4 production by primed lymphocytes. It can be concluded that decidua-secreted factors, by altering DC functions, can determine the pattern of immune responses at the fetomaternal interface and, subsequently, pregnancy outcome.

Seasonal Variation in Flares of Intestinal Behçet's Disease

BACKGROUND

There have been numerous investigations into the seasonality of several autoimmune diseases and inflammatory bowel disease in an effort to better understand the epidemiology and pathogenesis of these conditions. However, the relationship between the season and disease activity of intestinal Behçet's disease has not been investigated.

AIMS

This study aimed to evaluate the seasonal pattern of exacerbations of intestinal Behçet's disease.

METHODS

We evaluated 268 consecutive patients with intestinal Behçet's disease who were diagnosed and treated between November 1990 and March 2010 at Severance Hospital, Yonsei University, Seoul, Korea. Patient demographics, onset of symptoms, total number of relapses, and the month of each relapse were recorded. The relationship between the season and flares of intestinal Behçet's disease was analyzed.

RESULTS

A total of 339 relapses occurred in 142 patients (53 %). The median age at diagnosis was 39 (10-73) years; the median follow-up duration was 74 (7-372) months. The peak seasons for relapse were spring and autumn, especially the months of May and September (p value <0.001). Compared with winter, spring and autumn had higher rates of flares (HR 1.92 and 1.91, respectively, p value <0.001).

CONCLUSIONS

In this study, intestinal Behçet's disease demonstrated a biphasic pattern (peaks in spring and autumn) in exacerbations of disease, suggesting that seasonal or exogenous factors may be involved in the flares of intestinal Behçet's disease.

Vitamin D and autoimmune thyroid diseases: facts and unresolved questions

Vitamin D deficiency (levels lower than 20 ng/ml) is becoming a global health problem, since it is increasingly represented even among healthy subjects. Vitamin D, as an environmental factor, is involved in many biological processes, like perception of chronic pain and response to infections. In recent years, evidence has emerged pointing to an involvement of vitamin D in the development of many autoimmune diseases, and a severe vitamin D deficiency has been especially demonstrated in patients affected with autoimmune thyroid disease (AITD). Low levels of vitamin D were found associated with antithyroid antibody presence, abnormal thyroid function, increased thyroid volume, increased TSH levels, and adverse pregnancy outcome in women with AITD. Vitamin D mediates its effect through binding to vitamin D receptor (VDR), which is harbored on many human immune cells, and in this way is able to modulate immune cells activity, triggering both innate and adaptive immune responses. As VDR gene polymorphisms were found to associate with AITD, the evidence links vitamin D deficiency to AITD either through gene polymorphism or by environmental factors (lack of dietary uptake and sun exposure). Vitamin D supplementation may be offered to AITD patients, but further research is needed to define whether it should be introduced in clinical practice.