1 alpha,25-dihydroxyvitamin D3 suppresses proliferation and immunoglobulin production by normal human peripheral blood mononuclear cells

Vitamin D and systemic lupus erythematosus: Causality and association with disease activity and therapeutics

The major role of bioactive vitamin 1,25-dihydroxyvitamin D3 (1,25(OH)2D or calcitriol) is to maintain the levels of calcium and phosphorus to achieve bone and mineral homeostasis. Dietary intake and adequate natural light exposure are the main contributors to normal vitamin D status. In addition to regulating metabolism, vitamin D exerts various immunomodulatory effects that regulate innate and adaptive immunity through immune effector cells such as monocytes, macrophages, T and B lymphocytes, and natural killer cells and nonimmune cells that express vitamin D receptors. Systemic lupus erythematosus (SLE) is an autoimmune disease with an unknown etiology, and the association between vitamin D and SLE remains incompletely understood. Given that the current treatment for SLE relies heavily on corticosteroids and that SLE patients tend to have low vitamin D status, vitamin D supplementation may help to reduce the dosage of corticosteroids and/or attenuate disease severity. In this review, we address the associations between vitamin D and several clinical aspects of SLE. In addition, the underlying immunomodulatory mechanisms accounting for the potential vitamin D-mediated therapeutic effects are discussed. Finally, several confounding factors in data interpretation and the execution of clinical trials and perspectives targeting vitamin D supplementation in patients with SLE are also addressed.

Plasma vitamin D levels are correlated with the pathogenesis of human T-cell leukemia virus type 1-associated diseases

The active form of vitamin D (VD) exerts hormonal effects by regulating the expression of genes involved in T-cell activity, cell differentiation, and proliferation. Human T-cell leukemia virus type 1 (HTLV-1) is a causative agent of life-threatening diseases, adult T-cell leukemia (ATL) and HTLV-1-associated myelopathy (HAM). Among ATL patients, hypercalcemia is one of the most serious complications due to bone resorption. In this study, wild-type mice administered UV-irradiated HTLV-1-infected cells showed up to 47% decrease of plasma VD level compared with untreated mice. To clarify the effect of HTLV-1 on plasma VD level, 315 samples registered in nationwide cohort study on ATL onset were measured. The VD level in HAM (14.98 ± 8.5 ng/mL) was significantly lower than those in asymptomatic carriers and ATL (p < 0.05). Upon comparing the VD levels in ATL stratified by disease subtypes, acute ATL showed a lower level (15.81 ± 12.0 ng/mL) than chronic and smoldering types (p < 0.05). In the longitudinal observation, VD levels were significantly higher in untreated spontaneous remission cases than in ATL progression cases, in which the VD levels decreased approximately 40% after onset. In cases of relapse after transplantation, the plasma VD level dropped to 38.7% of the pre-relapse level, while in cases of complete remission, the VD level increased with improvement of the performance status. Taken together, these results suggest that plasma VD level is a potential indicator for the onset and relapse of HTLV-1-associated diseases.

Modulation of T-Cell-Dependent Humoral Immune Response to Influenza Vaccine by Multiple Antioxidant/Immunomodulatory Micronutrient Supplementation

Notwithstanding prevalence gaps in micronutrients supporting immune functions, the significance of their deficits/supplementation for the efficacy of vaccines is underinvestigated. Thus, the influence of supplementation combining vitamins C and D, zinc, selenium, manganese, and N-acetyl cysteine on immune correlates/surrogates of protection conferred by a quadrivalent influenza vaccine (QIV) in mice was investigated. The supplementation starting 5 days before the first of two QIV injections given 28 days apart increased the serum titres of total and neutralizing IgG against each of four influenza strains from QIV. Accordingly, the frequencies of germinal center B cells, follicular CD4+ T helper (Th) cells, and IL-21-producing Th cells increased in secondary lymphoid organs (SLOs). Additionally, the supplementation improved already increased IgG response to the second QIV injection by augmenting not only neutralizing antibody production, but also IgG2a response, which is important for virus clearance, through favoring Th1 differentiation as indicated by Th1 (IFN-γ)/Th2 (IL-4) signature cytokine level ratio upon QIV restimulation in SLO cell cultures. This most likely partly reflected antioxidant action of the supplement as indicated by splenic redox status analyses. Thus, the study provides a solid scientific background for further research aimed at repurposing the use of this safe and inexpensive micronutrient combination to improve response to the influenza vaccine.

Dietary vitamin D3 supplementation enhances splenic NK cell activity in healthy and diabetic male mice

Type 2 diabetes mellitus negatively affects the immune system, resulting in reduced natural killer (NK) cell activity. Vitamin D has been shown to regulate innate and adaptive immune cells. However, the effects of vitamin D on NK cells remain inconclusive, especially in the context of diabetes. We hypothesized that dietary vitamin D3 supplementation can enhance NK cell activity in diabetic mice. Therefore, we investigated the effects of dietary vitamin D3 on NK cell activity in control and diabetic mice and explored the mechanisms of NK cell activity modulation by vitamin D3. Control (CON) and diabetic mice (db/db) were randomly divided into 2 groups, then fed either a control diet (948 IU vitamin D3/kg diet, vDC) or a diet supplemented with vitamin D3 (9,477 IU vitamin D3/kg diet, vDS) for 8 weeks. Diabetic mice exhibited lower NK cell activity than control mice. The vDS group had significantly higher NK cell activity than the vDC group in both control and diabetic mice. The vDS group had a higher percentage of CD11b single-positive NK cells than the vDC group (CON-vDS 34%; db/db-vDS 30%; CON-vDC 27%; db/db-vDC 22%). The intracellular expression of splenic TGF-β was significantly higher in the db/db group than in the CON group. Overall, vDS group had higher Bcl2 and Tbx21 mRNA expressions than the vDC group. In conclusion, the present study shows that NK cell activity is impaired under diabetic conditions, possibly due to the reduced percentage of mature NK cells. Moreover, NK activity is enhanced by dietary supplementation in both control and diabetic mice that may be associated with changes in the proportion of mature NK cells.

The association between circulating 25-hydroxyvitamin D and pancreatic cancer: a systematic review and meta-analysis of observational studies

PURPOSE

The relationship between circulating 25-hydroxyvitamin D [25(OH)D] and pancreatic cancer has been well studied but remains unclear. The purpose of this study was to elucidate the association between circulating 25(OH)D and pancreatic cancer by using a meta-analytic approach.

METHODS

PubMed, Embase, and Wed of Science databases were searched through October 15, 2022. A random or fixed-effects model was used to estimate the pooled odds ratio (OR), risk ratio (RR), hazard ratio (HR) and their 95% confidence intervals (CIs).

RESULTS

A total of 16 studies including 529,917 participants met the inclusion criteria, of which 10 reported incidence and 6 reported mortality. For the highest versus lowest categories of circulating 25(OH)D, the pooled OR of pancreatic cancer incidence in case-control studies was 0.98 (95% CI 0.69-1.27), and the pooled HRs of pancreatic cancer mortality in cohort and case-control studies were 0.64 (95% CI 0.45-0.82) and 0.78 (95% CI 0.62-0.95), respectively. The leave-one-out sensitivity analyses found no outliers and Galbraith plots indicated no substantial heterogeneity.

CONCLUSION

Evidence from this meta-analysis suggested that high circulating 25(OH)D levels may be associated with decreased mortality but not incidence of pancreatic cancer. Our findings may provide some clues for the treatment of pancreatic cancer and remind us to be cautious about widespread vitamin D supplementation for the prevention of pancreatic cancer.

Update on vitamin D role in severe infections and sepsis

Severe infections frequently require admission to the intensive care unit and cause life-threatening complications in critically ill patients. In this setting, severe infections are acknowledged as prerequisites for the development of sepsis, whose pathophysiology implies a dysregulated host response to pathogens, leading to disability and mortality worldwide.Vitamin D is a secosteroid hormone that plays a pivotal role to maintain immune system homeostasis, which is of paramount importance to resolve infection and modulate the burden of sepsis. Specifically, vitamin D deficiency has been widely reported in critically ill patients and represents a risk factor for the development of severe infections, sepsis and worse clinical outcomes. Several studies have demonstrated the feasibility, safety and effectiveness of vitamin D supplementation strategies to improve vitamin D body content, but conflictual results support its benefit in general populations of critically ill patients. In contrast, small randomised clinical trials reported that vitamin D supplementation may improve host-defence to pathogen invasion via the production of cathelicidin and specific cytokines. Nonetheless, no large scale investigations have been designed to specifically assess the impact of vitamin D supplementation on the outcome of critically ill septic patients admitted to the intensive care unit.

What is known about the effects of vitamin D in neuropsychiatric lupus?

Systemic lupus erythematosus (SLE) is an autoimmune disease that can affect several organs and systems. The central and/or peripheral nervous system can suffer from complications known as neuropsychiatric lupus (NPSLE). Studies have associated the manifestations of SLE or NPSLE with vitamin D deficiency. It has been shown that hypovitaminosis D can lead to cognition deficits and cerebral hypoperfusion in patients with NPSLE. In this review article, we will address the main features related to vitamin D supplementation or serum vitamin D levels with neuropsychiatric manifestations, either in patients or in animal models of NPSLE.

Ethanol-induced changes to the gut microbiome compromise the intestinal homeostasis: a review

The intestine is the largest organ in terms of surface area in the human body. It is responsible not only for absorbing nutrients but also for protection against the external world. The gut microbiota is essential in maintaining a properly functioning intestinal barrier, primarily through producing its metabolites: short-chain fatty acids, bile acids, and tryptophan derivatives. Ethanol overconsumption poses a significant threat to intestinal health. Not only does it damage the intestinal epithelium, but, maybe foremostly, it changes the gut microbiome. Those ethanol-driven changes shift its metabolome, depriving the host of the protective effect the physiological gut microbiota has. This literature review discusses the impact of ethanol consumption on the gut, the gut microbiota, and its metabolome, providing a comprehensive overview of the mechanisms through which ethanol disrupts intestinal homeostasis and discussing potential avenues for new therapeutic intervention.

Mechanistic Insight into the role of Vitamin D and Zinc in Modulating Immunity Against COVID-19: A View from an Immunological Standpoint

The pathophysiology of coronavirus disease-19 (COVID-19) is characterized by worsened inflammation because of weakened immunity, causing the infiltration of immune cells, followed by necrosis. Consequently, these pathophysiological changes may lead to a life-threatening decline in perfusion due to hyperplasia of the lungs, instigating severe pneumonia, and causing fatalities. Additionally, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection can cause mortality due to viral septic shock, resulting from unrestrained and backfiring immune reactions to the pathogen. Sepsis can cause premature organ failure in COVID-19 patients, as well. Notably, vitamin D and its derivatives and minerals, such as zinc and magnesium, have been reported to improve the immune system against respiratory illnesses. This comprehensive review aims to provide updated mechanistic details of vitamin D and zinc as immunomodulators. Additionally, this review also focuses on their role in respiratory illnesses, while specifically delineating the plausibility of employing them as a preventive and therapeutic agent against current and future pandemics from an immunological perspective. Furthermore, this comprehensive review will attract the attention of health professionals, nutritionists, pharmaceuticals, and scientific communities, as it encourages the use of such micronutrients for therapeutic purposes, as well as promoting their health benefits for a healthy lifestyle and wellbeing.

Modifiable risk factors linked to the development of rheumatoid arthritis: evidence, immunological mechanisms and prevention

Rheumatoid Arthritis (RA) is a common autoimmune disease that targets the synovial joints leading to arthritis. Although the etiology of RA remains largely unknown, it is clear that numerous modifiable risk factors confer increased risk to developing RA. Of these risk factors, cigarette smoking, nutrition, obesity, occupational exposures and periodontal disease all incrementally increase RA risk. However, the precise immunological mechanisms by which these risk factors lead to RA are not well understood. Basic and translational studies have provided key insights into the relationship between inflammation, antibody production and the influence in other key cellular events such as T cell polarization in RA risk. Improving our general understanding of the mechanisms which lead to RA will help identify targets for prevention trials, which are underway in at-risk populations. Herein, we review the modifiable risk factors that are linked to RA development and describe immune mechanisms that may be involved. We highlight the few studies that have sought to understand if modification of these risk factors reduces RA risk. Finally, we speculate that modification of risk factors may be an appealing avenue for prevention for some at-risk individuals, specifically those who prefer lifestyle interventions due to safety and economic reasons.

Significance of 25(OH) D3 in Early Dental Implant Failure (EDIF) during osseointegration-A systematic review

Bone metabolism is a key factor for successful osseointegration, and low vitamin D levels may negatively impact the process of osseointegration after implant placement. The study was aimed at evaluating the relation of vitamin D levels with dental implant osseointegration and subsequently the success or failure of the implant. The focused questions were-What is the effect of vitamin D levels on successful dental implant osseointegration and what is the effect of vitamin D supplementation on successful implant osseointegration? A search was conducted on PubMed and Google Scholar using the terms "vitamin D," "cholecalciferol," "1,25(OH) D," "dental implant," "osseointegration," and "bone implant contact" for a period of 10 years from 2011 to 2020. Clinical trials, cross-sectional studies, case series, and case reports were included. A total of ten studies were included after the screening process. Five of these studies evaluated the effect of vitamin D supplementation on osseointegration, whereas five only evaluated the effect of vitamin D deficiency on dental implant osseointegration. Only five of these studies reported dental implant failure varying from 7% to 13% in vitamin D deficient/insufficient groups. Positive relationship exists between serum vitamin D levels and dental implant osseointegration; however, few studies failed to report any relation. More prospective clinical research studies as well as randomized controlled trials are needed to show a significant correlation between decreased serum levels of vitamin D and increased risk of dental implant failure in perspective of vitamin D supplementation which can promote the osseointegration of dental implants.

A review of the critical role of vitamin D axis on the immune system

In recent years, the physiological and molecular functions of vitamin D (Vit-D) have been deeply investigated. At first, Vit-D was considered a regulator of mineral and skeletal homeostasis. However, due to the extensive-expression pattern of Vit-D receptor (VDR) in almost every non-skeletal cell, Vit-D is considered mainly a multifunctional agent with broad effects on various tissues, notably the immune system. The expression of VDR in immune cells such as dendritic cells, monocyte/macrophage, neutrophils, B cells and T cells has been well demonstrated. Besides, such immune cells are capable of metabolizing the active form of Vit-D which means that it can module the immune system in both paracrine and autocrine manners. Vit-D binding protein (DBP), that regulates the levels and homeostasis of Vit-D, is another key molecule capable of modulating the immune system. Recent studies indicate that dysregulation of Vit-D axis, variations in the DBP and VDR genes, and Vit-D levels might be risk factors for the development of autoimmune disease. Here, the current evidence regarding the role of Vit-D axis on the immune system, as well as its role in the development of autoimmune disease will be clarified. Further insight will be given to those studies that investigated the association between single nucleotide polymorphisms of DBP and VDR genes with autoimmune disease susceptibility.

Differential impact of environmental factors on systemic and localized autoimmunity

The influence of environmental factors on the development of autoimmune disease is being broadly investigated to better understand the multifactorial nature of autoimmune pathogenesis and to identify potential areas of intervention. Areas of particular interest include the influence of lifestyle, nutrition, and vitamin deficiencies on autoimmunity and chronic inflammation. In this review, we discuss how particular lifestyles and dietary patterns may contribute to or modulate autoimmunity. We explored this concept through a spectrum of several autoimmune diseases including Multiple Sclerosis (MS), Systemic Lupus Erythematosus (SLE) and Alopecia Areata (AA) affecting the central nervous system, whole body, and the hair follicles, respectively. A clear commonality between the autoimmune conditions of interest here is low Vitamin D, a well-researched hormone in the context of autoimmunity with pleiotropic immunomodulatory and anti-inflammatory effects. While low levels are often correlated with disease activity and progression in MS and AA, the relationship is less clear in SLE. Despite strong associations with autoimmunity, we lack conclusive evidence which elucidates its role in contributing to pathogenesis or simply as a result of chronic inflammation. In a similar vein, other vitamins impacting the development and course of these diseases are explored in this review, and overall diet and lifestyle. Recent work exploring the effects of dietary interventions on MS showed that a balanced diet was linked to improvement in clinical parameters, comorbid conditions, and overall quality of life for patients. In patients with MS, SLE and AA, certain diets and supplements are linked to lower incidence and improved symptoms. Conversely, obesity during adolescence was linked with higher incidence of MS while in SLE it was associated with organ damage. Autoimmunity is thought to emerge from the complex interplay between environmental factors and genetic background. Although the scope of this review focuses on environmental factors, it is imperative to elaborate the interaction between genetic susceptibility and environment due to the multifactorial origin of these disease. Here, we offer a comprehensive review about the influence of recent environmental and lifestyle factors on these autoimmune diseases and potential translation into therapeutic interventions.

Gut microbiota derived bile acid metabolites maintain the homeostasis of gut and systemic immunity

Bile acids (BAs) as cholesterol-derived molecules play an essential role in some physiological processes such as nutrient absorption, glucose homeostasis and regulation of energy expenditure. They are synthesized in the liver as primary BAs such as cholic acid (CA), chenodeoxycholic acid (CDCA) and conjugated forms. A variety of secondary BAs such as deoxycholic acid (DCA) and lithocholic acid (LCA) and their derivatives is synthesized in the intestine through the involvement of various microorganisms. In addition to essential physiological functions, BAs and their metabolites are also involved in the differentiation and functions of innate and adaptive immune cells such as macrophages (Macs), dendritic cells (DCs), myeloid derived suppressive cells (MDSCs), regulatory T cells (Treg), Breg cells, T helper (Th)17 cells, CD4 Th1 and Th2 cells, CD8 cells, B cells and NKT cells. Dysregulation of the BAs and their metabolites also affects development of some diseases such as inflammatory bowel diseases. We here summarize recent advances in how BAs and their metabolites maintain gut and systemic homeostasis, including the metabolism of the BAs and their derivatives, the role of BAs and their metabolites in the differentiation and function of immune cells, and the effects of BAs and their metabolites on immune-associated disorders.

Vitamin D and Autoimmune Rheumatic Diseases

Vitamin D is a steroid hormone with potent immune-modulating properties. It has been shown to stimulate innate immunity and induce immune tolerance. Extensive research efforts have shown that vitamin D deficiency may be related to the development of autoimmune diseases. Vitamin D deficiency has been observed in patients with rheumatoid arthritis (RA) and has been shown to be inversely related to disease activity. Moreover, vitamin D deficiency may be implicated in the pathogenesis of the disease. Vitamin D deficiency has also been observed in patients with systemic lupus erythematosus (SLE). It has been found to be inversely related to disease activity and renal involvement. In addition, vitamin D receptor polymorphisms have been studied in SLE. Vitamin D levels have been studied in patients with Sjogren's syndrome, and vitamin D deficiency may be related to neuropathy and the development of lymphoma in the context of Sjogren's syndrome. Vitamin D deficiency has been observed in ankylosing spondylitis, psoriatic arthritis (PsA), and idiopathic inflammatory myopathies. Vitamin D deficiency has also been observed in systemic sclerosis. Vitamin D deficiency may be implicated in the pathogenesis of autoimmunity, and it may be administered to prevent autoimmune disease and reduce pain in the context of autoimmune rheumatic disorders.

Gut-Microbiota-Derived Metabolites Maintain Gut and Systemic Immune Homeostasis

The gut microbiota, including bacteria, archaea, fungi, viruses and phages, inhabits the gastrointestinal tract. This commensal microbiota can contribute to the regulation of host immune response and homeostasis. Alterations of the gut microbiota have been found in many immune-related diseases. The metabolites generated by specific microorganisms in the gut microbiota, such as short-chain fatty acids (SCFAs), tryptophan (Trp) and bile acid (BA) metabolites, not only affect genetic and epigenetic regulation but also impact metabolism in the immune cells, including immunosuppressive and inflammatory cells. The immunosuppressive cells (such as tolerogenic macrophages (tMacs), tolerogenic dendritic cells (tDCs), myeloid-derived suppressive cells (MDSCs), regulatory T cells (Tregs), regulatory B cells (Breg) and innate lymphocytes (ILCs)) and inflammatory cells (such as inflammatory Macs (iMacs), DCs, CD4 T helper (Th)1, CD4Th2, Th17, natural killer (NK) T cells, NK cells and neutrophils) can express different receptors for SCFAs, Trp and BA metabolites from different microorganisms. Activation of these receptors not only promotes the differentiation and function of immunosuppressive cells but also inhibits inflammatory cells, causing the reprogramming of the local and systemic immune system to maintain the homeostasis of the individuals. We here will summarize the recent advances in understanding the metabolism of SCFAs, Trp and BA in the gut microbiota and the effects of SCFAs, Trp and BA metabolites on gut and systemic immune homeostasis, especially on the differentiation and functions of the 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.

Pre-transplantation vitamin D deficiency increases acute graft-versus-host disease after hematopoietic stem cell transplantation in thalassemia major patients

BACKGROUND

Although there are many studies on the role of vitamin D deficiency (VDD) in hematopoetic stem cell transplantation (HSCT), outcomes have often reported conflicting results because of the heterogeneity of the patients in the studies.

METHODS

We investigated the association between VDD prior to HSCT and outcomes after HSCT in a relatively homogenous group of patients with thalassemia major (TM) who received identical treatment for TM before transplantation, and the same conditioning regimen and GVHD prophylaxis during and after transplantation. All patients, including the patients with normal vitamin D₃ levels received 400 to 800 IU per day of vitamin D for the first 6 months after HSCT.

RESULTS

Pre-HSCT VDD increased the frequency of aGVHD after transplantation, particularly in HSCTs performed with PBSC for the stem cell source. Pre-transplant low vitamin D₃ levels had no association with transplant outcomes such as engraftment, viral infections, alloimmunization, chronic GvHD, total days of hospitalization, and success in terms of transfusion independence.

CONCLUSIONS

Low vitamin D₃ levels before HSCT carry a significant risk for aGVHD. All patients with TM should be screened for VDD before HSCT, and every effort should be made to supplement vitamin D before the transplant in VDD patients.

Vitamin D in patients with COVID-19: is there a room for it?

Vitamin-D receptors are found in a variety of cells with the potential to regulate many cellular functions. Higher COVID-19 severity has been reported in individuals, which are known to have lower vitamin-D levels. The relation between vitamin-D and COVID-19 has been analysed with a number of studies but only few met high standards. Studies revealed discordant findings. There is no data from interventional trials clearly indicating that vitamin-D supplementation may prevent against COVID-19. An increasing number of observational studies put forward the preventive feature of adequate vitamin-D status for COVID-19 mortality. Yet, there are again conflicting findings. This narrative review summarizes the current evidence and provides a practical advice to lessen the impact of COVID-19 by ensuring recommended vitamin-D intakes. This approach would not be harmful, but potentially useful. Vitamin-D is safe especially if it does not exceed the upper-tolerable-limit. Daily doses are recommended over the weekly or monthly higher doses. Mega-doses are not recommended because of its potential to lead adverse events. The target level of vitamin-D is proposed above 30 ng/mL in majority of the studies. Nonetheless, one should consider that the benefit is foreseen to be small, and some time (months) may be needed for such effect.

Protective Effect of Vitamin D Supplementation on COVID-19-Related Intensive Care Hospitalization and Mortality: Definitive Evidence from Meta-Analysis and Trial Sequential Analysis

BACKGROUND

The COVID-19 pandemic represents one of the world's most important challenges for global public healthcare. Various studies have found an association between severe vitamin D deficiency and COVID-19-related outcomes. Vitamin D plays a crucial role in immune function and inflammation. Recent data have suggested a protective role of vitamin D in COVID-19-related health outcomes. The purpose of this meta-analysis and trial sequential analysis (TSA) was to better explain the strength of the association between the protective role of vitamin D supplementation and the risk of mortality and admission to intensive care units (ICUs) in patients with COVID-19.

METHODS

We searched four databases on 20 September 2022. Two reviewers screened the randomized clinical trials (RCTs) and assessed the risk of bias, independently and in duplicate. The pre-specified outcomes of interest were mortality and ICU admission.

RESULTS

We identified 78 bibliographic citations. After the reviewers' screening, only five RCTs were found to be suitable for our analysis. We performed meta-analyses and then TSAs. Vitamin D administration results in a decreased risk of death and ICU admission (standardized mean difference (95% CI): 0.49 (0.34-0.72) and 0.28 (0.20-0.39), respectively). The TSA of the protective role of vitamin D and ICU admission showed that, since the pooling of the studies reached a definite sample size, the positive association is conclusive. The TSA of the protective role of vitamin D in mortality risk showed that the z-curve was inside the alpha boundaries, indicating that the positive results need further studies.

DISCUSSION

The results of the meta-analyses and respective TSAs suggest a definitive association between the protective role of vitamin D and ICU hospitalization.

The Contrasting Seasonality Patterns of Some Cancer-Types and Herpes Zoster Can Be Explained by a Binary Classification of Immunological Reactions

A binary classification of the pathogenic immune reactions as anti-inflammatory high-Treg reactions or pro-inflammatory low-Treg reactions explains both the relatively low incidence rate of several types of cancer, and the relatively high incidence rate of herpes zoster cases diagnosed in the summer compared to cases diagnosed in the winter (in regions with temperate climate). This binary model also elucidates the longer survival of cancer patients diagnosed during the summer compared to these diagnosed in the winter. The three key elements of this explanation are: (a) the effect of sunlight on Treg production; (b) the evolvement of cancer from a low-Treg condition at early stage, to a high-Treg condition at advanced stage, and (c) the evolvement of herpes zoster from a high-Treg condition at pre-exudative stage to a low-Treg condition at acute exudative stage. A significant proportion of indolent tumors at the time of diagnosis (>20%) is a prerequisite for a beneficial effect of sunlight on cancer incidence rate and prognosis. This prerequisite restricts the beneficial effect of diagnosis during summer to certain types of cancer. Clinical implication: the prognosis of early stage tumors may be improved by a course of corticosteroid (or other immunosuppressant) treatment.

Brief communication: Vitamin D serum levels in American tegumentary leishmaniasis from an endemic area in Northeast Brazil

INTRODUCTION

The pathogenesis of cutaneous and mucosal leishmaniasis is associated with different immune responses. Vitamin D may modulate the immune system. Here we evaluate the association of vitamin D levels with the severity of the clinical forms of cutaneous and mucosal leishmaniasis.

METHODS

We conducted an observational study evaluating the association between vitamin D levels, disease severity and therapeutic response in patients with cutaneous and mucosal leishmaniasis. Additionally, we conducted a cross-sectional study to compare vitamin D levels in patients with leishmaniasis and healthy subjects. Hypovitaminosis D was defined as a serum level of 25 (OH) D < 30 ng/mL.

RESULTS

In patients with leishmaniasis, vitamin D serum levels were 38.5 ± 11.54 ng/mL, and 37.5 ± 10.43 ng/mL in healthy subjects The prevalence of hypovitaminosis D was 23.3% and 20.0%, respectively (p = 0.72). There was no correlation between vitamin D serum levels, disease severity, and healing time in the mucosal leishmaniasis group.

CONCLUSION

Vitamin D levels are not associated with neither susceptibility nor severity of tegumentary leishmaniasis.

Impact of dietary vitamin D on immunoregulation and disease pathology in lupus-prone NZB/W F1 mice

Vitamin D (VD) deficiency is a highly prevalent worldwide phenomenon and is extensively discussed as a risk factor for the development of systemic lupus erythematosus (SLE) and other immune-mediated diseases. In addition, it is now appreciated that VD possesses multiple immunomodulatory effects. This study aims to explore the impact of dietary VD intake on lupus manifestation and pathology in lupus-prone NZB/W F1 mice and identify the underlying immunological mechanisms modulated by VD. Here, we show that low VD intake accelerates lupus progression, reflected in reduced overall survival and an earlier onset of proteinuria, as well higher concentrations of anti-double-stranded DNA autoantibodies. This unfavorable effect gained statistical significance with additional low maternal VD intake during the prenatal period. Among examined immunological effects, we found that low VD intake consistently hampered the adoption of a regulatory phenotype in lymphocytes, significantly reducing both IL-10-expressing and regulatory CD4+ T cells. This goes along with a mildly decreased frequency of IL-10-expressing B cells. We did not observe consistent effects on the phenotype and function of innate immune cells, including cytokine production, costimulatory molecule expression, and phagocytic capacity. Hence, our study reveals that low VD intake promotes lupus pathology, likely via the deviation of adaptive immunity, and suggests that the correction of VD deficiency might not only exert beneficial functions by preventing osteoporosis but also serve as an important module in prophylaxis and as an add-on in the treatment of lupus and possibly other immune-mediated diseases. Further research is required to determine the most appropriate dosage, as too-high VD serum levels may also induce adverse effects, possibly also on lupus pathology.

Nutrition, Immunosenescence, and Infectious Disease: An Overview of the Scientific Evidence on Micronutrients and on Modulation of the Gut Microbiota

The immune system is key to host defense against pathogenic organisms. Aging is associated with changes in the immune system, with a decline in protective components (immunosenescence), increasing susceptibility to infectious disease, and a chronic elevation in low-grade inflammation (inflammaging), increasing the risk of multiple noncommunicable diseases. Nutrition is a determinant of immune cell function and of the gut microbiota. In turn, the gut microbiota shapes and controls the immune and inflammatory responses. Many older people show changes in the gut microbiota. Age-related changes in immune competence, low-grade inflammation, and gut dysbiosis may be interlinked and may relate, at least in part, to age-related changes in nutrition. A number of micronutrients (vitamins C, D, and E and zinc and selenium) play roles in supporting the function of many immune cell types. Some trials report that providing these micronutrients as individual supplements can reverse immune deficits in older people and/or in those with insufficient intakes. There is inconsistent evidence that this will reduce the risk or severity of infections including respiratory infections. Probiotic, prebiotic, or synbiotic strategies that modulate the gut microbiota, especially by promoting the colonization of lactobacilli and bifidobacteria, have been demonstrated to modulate some immune and inflammatory biomarkers in older people and, in some cases, to reduce the risk and severity of gastrointestinal and respiratory infections, although, again, the evidence is inconsistent. Further research with well-designed and well-powered trials in at-risk older populations is required to be more certain about the role of micronutrients and of strategies that modify the gut microbiota-host relationship in protecting against infection, especially respiratory infection.

Immunoceuticals: Harnessing Their Immunomodulatory Potential to Promote Health and Wellness

Knowledge that certain nutraceuticals can modulate the immune system is not new. These naturally occurring compounds are known as immunoceuticals, which is a novel term that refers to products and systems that naturally improve an individual's immuno-competence. Examples of immunoceuticals include vitamin D3, mushroom glycans, flavonols, quercetin, omega-3 fatty acids, carotenoids, and micronutrients (e.g., zinc and selenium), to name a few. The immune system is a complex and highly intricate system comprising molecules, cells, tissues, and organs that are regulated by many different genetic and environmental factors. There are instances, such as pathological conditions, in which a normal immune response is suboptimal or inappropriate and thus augmentation or tuning of the immune response by immunoceuticals may be desired. With infectious diseases, cancers, autoimmune disorders, inflammatory conditions, and allergies on the rise in both humans and animals, the importance of the use of immunoceuticals to prevent, treat, or augment the treatment of these conditions is becoming more evident as a natural and often economical approach to support wellness. The global nutraceuticals market, which includes immunoceuticals, is a multi-billion-dollar industry, with a market size value of USD 454.55 billion in 2021, which is expected to reach USD 991.09 billion by 2030. This review will provide an overview of the immune system, the importance of immunomodulation, and defining and testing for immunocompetence, followed by a discussion of several key immunoceuticals with clinically proven and evidence-based immunomodulatory properties.

Vitamin D in Systemic Sclerosis: A Review

(1) Background: In the present paper we aimed to review the evidence about the potential implication of vitamin D in the pathogenesis and management of systemic sclerosis (SSc); (2) Methods: we performed a review of the literature looking for studies evaluating the potential role of vitamin D and its analogs in SSc. We searched the PubMed, Medline, Embase, and Cochrane libraries using the following strings: (vitamin D OR cholecalciferol) AND (systemic sclerosis OR scleroderma). We included cohort studies, case-control studies, randomized controlled trials, and observational studies. (3) Results: we identified nine pre-clinical and 21 clinical studies. Pre-clinical data suggest that vitamin D and its analogs may suppress fibrogenesis. Clinical data are concordant in reporting a high prevalence of hypovitaminosis D and osteoporosis in SSc patients; data about the association with clinical manifestations and phenotypes of SSc are, conversely, far less consistent; (4) Conclusions: in vitro data suggest that vitamin D may play an antifibrotic role in SSc, but clinical data confirming this finding are currently lacking. Hypovitaminosis D is common among SSc patients and should be treated to reduce the risk of osteoporosis.

An Update on the Effects of Vitamin D on the Immune System and Autoimmune Diseases

Vitamin D intervenes in calcium and phosphate metabolism and bone homeostasis. Experimental studies have shown that 1,25-dihydroxyvitamin D (calcitriol) generates immunologic activities on the innate and adaptive immune system and endothelial membrane stability. Low levels of serum 25-hydroxyvitamin D (25(OH)D) are associated with an increased risk of developing immune-related diseases such as psoriasis, type 1 diabetes, multiple sclerosis, and autoimmune diseases. Various clinical trials describe the efficacy of supplementation of vitamin D and its metabolites for treating these diseases that result in variable outcomes. Different disease outcomes are observed in treatment with vitamin D as high inter-individual difference is present with complex gene expression in human peripheral blood mononuclear cells. However, it is still not fully known what level of serum 25(OH)D is needed. The current recommendation is to increase vitamin D intake and have enough sunlight exposure to have serum 25(OH)D at a level of 30 ng/mL (75 nmol/L) and better at 40–60 ng/mL (100–150 nmol/L) to obtain the optimal health benefits of vitamin D.

Bile Acid-Related Regulation of Mucosal Inflammation and Intestinal Motility: From Pathogenesis to Therapeutic Application in IBD and Microscopic Colitis

Inflammatory bowel diseases (IBD) and microscopic colitis are chronic immune-mediated inflammatory disorders that affect the gastroenterological tract and arise from a complex interaction between the host’s genetic risk factors, environmental factors, and gut microbiota dysbiosis. The precise mechanistic pathways interlinking the intestinal mucosa homeostasis, the immunological tolerance, and the gut microbiota are still crucial topics for research. We decided to deeply analyze the role of bile acids in these complex interactions and their metabolism in the modulation of gut microbiota, and thus intestinal mucosa inflammation. Recent metabolomics studies revealed a significant defect in bile acid metabolism in IBD patients, with an increase in primary bile acids and a reduction in secondary bile acids. In this review, we explore the evidence linking bile acid metabolites with the immunological pathways involved in IBD pathogenesis, including apoptosis and inflammasome activation. Furthermore, we summarize the principal etiopathogenetic mechanisms of different types of bile acid-induced diarrhea (BAD) and its main novel diagnostic approaches. Finally, we discuss the role of bile acid in current and possible future state-of-the-art therapeutic strategies for both IBD and BAD.

Association of vitamin D status with COVID-19 and its severity : Vitamin D and COVID-19: a narrative review

Vitamin D is associated with biological activities of the innate and adaptive immune systems, as well as inflammation. In observational studies, an inverse relationship has been found between serum 25-hydroxyvitamin D (25(OH)D) concentrations and the risk or severity of coronavirus disease 2019 (COVID-19). Several mechanisms have been proposed for the role of vitamin D in COVID-19, including modulation of immune and inflammatory responses, regulation of the renin-angiotensin-aldosterone system, and involvement in glucose metabolism and cardiovascular system. Low 25(OH)D concentrations might predispose patients with COVID-19 to severe outcomes not only via the associated hyperinflammatory syndrome but also by worsening preexisting impaired glucose metabolism and cardiovascular diseases. Some randomized controlled trials have shown that vitamin D supplementation is beneficial for reducing severe acute respiratory syndrome coronavirus 2 RNA positivity but not for reducing intensive care unit admission or all-cause mortality in patients with moderate-to-severe COVID-19. Current evidence suggests that taking a vitamin D supplement to maintain a serum concentration of 25(OH)D of at least 30 ng/mL (preferred range 40-60 ng/mL), can help reduce the risk of COVID-19 and its severe outcomes, including mortality. Although further well designed studies are warranted, it is prudent to recommend vitamin D supplements to people with vitamin D deficiency/insufficiency during the COVID-19 pandemic according to international guidelines.

Effect of Vitamin D on Graft-versus-Host Disease

The different cell subsets of the immune system express the vitamin D receptor (VDR). Through the VDR, vitamin D exerts different functions that influence immune responses, as previously shown in different preclinical models. Based on this background, retrospective studies explored the impacts of vitamin D levels on the outcomes of patients undergoing allogeneic hematopoietic stem-cell transplantation, showing that vitamin D deficiency is related to an increased risk of complications, especially graft-versus-host disease. These results were confirmed in a prospective cohort trial, although further studies are required to confirm this data. In addition, the role of vitamin D on the treatment of hematologic malignancies was also explored. Considering this dual effect on both the immune systems and tumor cells of patients with hematologic malignancies, vitamin D might be useful in this setting to decrease both graft-versus-host disease and relapse rates.

An Overview of Systematic Reviews of the Role of Vitamin D on Inflammation in Patients with Diabetes and the Potentiality of Its Application on Diabetic Patients with COVID-19

Almost two years have passed since the outbreak reported for the first time in Wuhan of coronavirus disease 2019 (COVID-19), due to severe acute respiratory syndrome (SARS)-CoV-2 coronavirus, rapidly evolved into a pandemic. This infectious disease has stressed global health care systems. The mortality rate is higher, particularly in elderly population and in patients with comorbidities such as hypertension, diabetes mellitus, cardiovascular disease, chronic lung disease, chronic renal disease, and malignancy. Among them, subjects with diabetes have a high risk of developing severe form of COVID-19 and show increased mortality. How diabetes contributes to COVID-19 severity remains unclear. It has been hypothesized that it may be correlated with the effects of hyperglycemia on systemic inflammatory responses and immune system dysfunction. Vitamin D (VD) is a modulator of immune-response. Data from literature showed that vitamin D deficiency in COVID-19 patients increases COVID-19 severity, likely because of its negative impact on immune and inflammatory responses. Therefore, the use of vitamin D might play a role in some aspects of the infection, particularly the inflammatory state and the immune system function of patients. Moreover, a piece of evidence highlighted a link among vitamin D deficiency, obesity and diabetes, all factors associated with COVID-19 severity. Given this background, we performed an overview of the systematic reviews to assess the association between vitamin D supplementation and inflammatory markers in patients with diabetes; furthermore, vitamin D’s possible role in COVID-19 patients was assessed as well. Three databases, namely MEDLINE, PubMed Central and the Cochrane Library of Systematic Reviews, were reviewed to retrieve the pertinent data. The aim of this review is to provide insight into the recent advances about the molecular basis of the relationship between vitamin D, immune response, inflammation, diabetes and COVID-19.

The Immunomodulatory Properties of Vitamin D

Since its discovery, vitamin D was shown to have both immunostimulatory and immunomodulatory effects on the immune system. A growing body of evidence so far linked vitamin D deficiency with the development and severity of several systemic and organ specific autoimmune/inflammatory diseases, such as systemic lupus erythematosus, rheumatoid arthritis, inflammatory bowel disease, and multiple sclerosis. In the present report, the multiple and diverse effects of vitamin D on the immune system are reviewed.

Polymorphisms CYP2R1 rs10766197 and CYP27B1 rs10877012 in Multiple Sclerosis: A Case-Control Study

BACKGROUND

Multiple sclerosis (MS) is a chronic autoimmune inflammatory disease. Low vitamin D levels have been reported to be a risk factor for MS, and genetic variances could be implicated. The aim of this study was to evaluate the association of MS with rs10766197 polymorphism of CYP2R1 gene and rs10877012 polymorphism of CYP27B1 gene. The second aim was to analyse whether these polymorphisms are associated with the severity of the progression of MS. Material and Methods. In a case-control study, we included 116 MS patients and 226 controls, all of whom were Mexican Mestizo. MS was diagnosed by McDonald criteria (2017). A complete neurological evaluation was performed to evaluate the severity of disease progression. Serum 25-hydroxyvitamin D [25(OH) vitamin D] levels were measured by ELISA. Single nucleotide polymorphisms rs10766197 of CYP2R1 gene and rs10877012 SNP of CYP27B1 gene were genotyped by real-time PCR.

RESULTS

Serum 25(OH) vitamin D levels were lower in MS patients than in controls (p = 0.009). No differences were observed between serum 25(OH) vitamin D levels of MS patients with severe progression compared to low progression (p = 0.88). A higher frequency of the A allele of CYP2R1 rs10766197 was observed between MS patients and controls (p = 0.05). No differences were observed in the frequency of T allele of CYP27B1 rs10877012 (p = 0.65). In subanalysis, patients with GA + AA genotypes of CYP2R1 rs10766197 had an increased risk of MS compared to controls (p = 0.03). No increased risk was observed in GT + TT genotypes of CYP27B1 rs10877012 (p = 0.63). No differences were observed in allele frequencies of either polymorphism between patients with severe vs. low disease progression.

CONCLUSION

Lower serum 25(OH) vitamin D levels were observed in MS patients than in controls, although these levels were not associated with disease progression. Carriers of GA + AA genotypes of CYP2R1 rs10766197 had an increased risk of MS. None of these polymorphisms was associated with severe progression of MS.

Vitamin D Endocrine System and COVID-19

Preclinical data strongly suggest that the vitamin D endocrine system (VDES) may have extraskeletal effects. Cells of the immune and cardiovascular systems and lungs can express the vitamin D receptor, and overall these cells respond in a coherent fashion when exposed to 1,25-dihydroxyvitamin D, the main metabolite of the VDES. Supplementation of vitamin D-deficient subjects may decrease the risk of upper respiratory infections. The VDES also has broad anti-inflammatory and anti-thrombotic effects, and other mechanisms argue for a potential beneficial effect of a good vitamin D status on acute respiratory distress syndrome, a major complication of this SARS-2/COVID-19 infection. Activation of the VDES may thus have beneficial effects on the severity of COVID-19. Meta-analysis of observational data show that a better vitamin D status decreased the requirement of intensive care treatment or decreased mortality. A pilot study in Cordoba indicated that admission to intensive care was drastically reduced by administration of a high dose of calcifediol early after hospital admission for COVID-19. A large observational study in Barcelona confirmed that such therapy significantly decreased the odds ratio (OR) of mortality (OR = 0.52). This was also the conclusion of a retrospective study in five hospitals of Southern Spain. A retrospective study on all Andalusian patients hospitalized because of COVID-19, based on real-world data from the health care system, concluded that prescription of calcifediol (hazard ratio [HR] = 0.67) or vitamin D (HR = 0.75), 15 days before hospital admission decreased mortality within the first month. In conclusion, a good vitamin D status may have beneficial effects on the course of COVID-19. This needs to be confirmed by large, randomized trials, but in the meantime, we recommend (rapid) correction of 25 hydroxyvitamin D (25OHD) deficiency in subjects exposed to this coronavirus. © 2021 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

The proteomics analysis of the effects of Zhishi Rhubarb soup on ischaemic stroke

BACKGROUND

Stroke has always been a major threat worldwide but is most severe in China, with 2.5 million new stroke cases each year and 7.5 million stroke survivors, placing a heavy burden on the social and national health care systems. Zhishi Rhubarb Soup (ZRS) is a traditional Chinese medicine (TCM) that has been used clinically for many years in China. To explore the potential mechanism of ZRS in the treatment of stroke, liquid chromatography with mass spectrometry (LC-MS) was performed.

METHODS

In this study, a quantitative proteomic method with LC-MS was used to analyse the proteomic differences between MACO samples treated with ZRS and those without ZRS treatment.

RESULTS

Liquid chromatography with mass spectrometry (LC-MS) analysis led to the identification of 35,006 peptides, with 5160.0 proteins identified and 4094.0 quantified. Significantly differentially expressed proteins were identified through data analysis, and the difference was found to be more than 1.2 times (P < 0.05). The Gene Ontology (GO) analysis provided a summary of the dysregulated protein expression in the biological process (BP), cell component (CC), and molecular function (MF) categories. Proteins related to brain repair, including BDNF, IL-10, IL-6, and TGF-β, were found to change significantly, partially demonstrating the effectiveness of ZRS to attenuate tissue injury.

CONCLUSION

In this study, LC-MS/MS was performed to assess the effects of ZRS on differentially expressed proteins in rats with cerebral infarction. These promising results could help to improve the understanding of the effects of drugs on stroke.

ε2 , ε3 , and ε4 variants of ApoE; rs2228570 (VDR), rs4588 and rs7041 (VDBP) polymorphisms in patients with multiple sclerosis: A case-control study in Turkish population

AIM OF THE STUDY

Multiple sclerosis (MS) is a degenerative disease characterized by autoimmune demyelination in the central nervous system. Yet, underlined genetics or environmental markers are still controversial. The impact of vitamin D and cholesterol on disease activity has been phrased by many studies; however, the data available for the Turkish population are very limited. This study aimed to investigate the effect of vitamin D-related polymorphisms (VDBP and VDR) and cholesterol-related variants of ApoE on Turkish MS patients.

MATERIALS AND METHODS

Total DNAs were extracted from peripheral blood samples of 51 MS patients and 50 healthy volunteers. rs4588 and rs7041 polymorphisms of VDBP, rs2228570 of VDR, as well as ε2, ε3, and ε4 variants of ApoE, were investigated by RT-PCR. Biochemical parameters which thought to be associated with MS were also measured. Results were evaluated statistically.

RESULTS

Homozygous mutant genotype and G allele of rs2228570 in VDR, as well as heterozygous genotype of rs4588 in VDBP, were found statistically high in patients. Total cholesterol, triglyceride, and LDL-C levels were found significantly high, whereas HDL-C and vitamin D levels were low in patients. An association was found between rs4588 variation and high triglyceride levels. Similar correlations were found between ε2 genotype and low LDL-C level; ε3 genotype and higher LDL-C. Gender, triglyceride, HDL-C, and AA genotype in rs4588 had a significant effect on MS progression.

CONCLUSION

The variations of rs2228570 and rs4588, vitamin D deficiency, and biological parameters related to cholesterol metabolism may be associated with MS risk.

Vitamin D and Rheumatic Diseases: A Review of Clinical Evidence

Vitamin D plays an important role in maintaining a healthy mineralized skeleton. It is also considered an immunomodulatory agent that regulates innate and adaptive immune systems. The aim of this narrative review is to provide general concepts of vitamin D for the skeletal and immune health, and to summarize the mechanistic, epidemiological, and clinical evidence on the relationship between vitamin D and rheumatic diseases. Multiple observational studies have demonstrated the association between a low level of serum 25-hydroxyvitamin D [25(OH)D] and the presence and severity of several rheumatic diseases, such as rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), spondyloarthropathies, and osteoarthritis (OA). Nevertheless, the specific benefits of vitamin D supplements for the treatment and prevention of rheumatic diseases are less accepted as the results from randomized clinical trials are inconsistent, although some conceivable benefits of vitamin D for the improvement of disease activity of RA, SLE, and OA have been demonstrated in meta-analyses. It is also possible that some individuals might benefit from vitamin D differently than others, as inter-individual difference in responsiveness to vitamin D supplementation has been observed in genomic studies. Although the optimal level of serum 25(OH)D is still debatable, it is advisable it is advisable that patients with rheumatic diseases should maintain a serum 25(OH)D level of at least 30 ng/mL (75 nmol/L) to prevent osteomalacia, secondary osteoporosis, and fracture, and possibly 40–60 ng/mL (100–150 nmol/L) to achieve maximal benefit from vitamin D for immune health and overall health.

Vitamin D and COVID-19: An Overview of Recent Evidence

The novel coronavirus severe acute respiratory syndrome (SARS-CoV-2) has progressed rapidly from an outbreak to a global pandemic, with new variants rapidly emerging. Coronavirus disease 2019 (COVID-19), the disease resulting from SARS-CoV-2 infection, can lead to multiorgan damage. Due to the extremely contagious and fatal nature of the virus, it has been a priority of medical research to find effective means of treatment. Amid this search, the role of vitamin D in modulating various aspects of the innate and adaptive immune system has been discussed. This review aims to consolidate the research surrounding the role of vitamin D in the treatment and prevention of COVID-19. While there are some conflicting results reported, the consensus is that vitamin D has a host of immunomodulatory effects which may be beneficial in the context of COVID-19 and that low levels of vitamin D can result in dysfunction of crucial antimicrobial effects, potentially contributing to poor prognosis. Studies also show that the effects of low vitamin D can be mitigated via supplementation, although the benefits of vitamin D supplementation in the treatment of COVID-19 remain controversial.

The Relationship Between Vitamin D and Infections Including COVID-19: Any Hopes?

Vitamin D is proposed to have a potential role in the pathogenicity, clinical presentation, prognosis, complications, and treatment of several diseases. In addition to its well-known role in calcium metabolism, vitamin D regulates both innate and adaptive immunity, and subsequently modulates the antiviral and antibacterial inflammatory immune responses. In view of the emerging coronavirus disease 2019 (COVID-19) pandemic, searching for potential therapeutic and protective strategies is of urgent interest, and vitamin D is one of the promising agents in this field. In this review, we present data from literature that supports the promising role of vitamin D in treatment and/or prevention of several infections including severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). This review summarizes vitamin D metabolism and its role in inflammation, thrombosis and immune regulation. It also reviews, in short, the role of vitamin D and the impact of its deficiency in several infections namely tuberculosis, influenza, human immunodeficiency virus (HIV), and SARS-CoV-2. Considering the roles of vitamin D on immune modulation, controlling of thrombosis, and attacking several microorganisms, the current review will elaborate on the association between these salient roles of vitamin D and the pathogenicity of various infectious agents including COVID-19. Consequently, the comprehensive finding of the current review shows a possible significant impact of vitamin D supplement as a hope in preventing, treating, and/or improving the progression of certain infections, specifically during the worldwide attempts to fight against the COVID-19 pandemic and minimize the severity of health complications encountered accordingly. In addition, avoiding a status of vitamin D deficiency to obtain its positive effects on the immune system and its protective mechanism during infections will be a general benefit overall.

A Case of Double Standard: Sex Differences in Multiple Sclerosis Risk Factors

Multiple sclerosis is a complex, multifactorial, dysimmune disease prevalent in women. Its etiopathogenesis is extremely intricate, since each risk factor behaves as a variable that is interconnected with others. In order to understand these interactions, sex must be considered as a determining element, either in a protective or pathological sense, and not as one of many variables. In particular, sex seems to highly influence immune response at chromosomal, epigenetic, and hormonal levels. Environmental and genetic risk factors cannot be considered without sex, since sex-based immunological differences deeply affect disease onset, course, and prognosis. Understanding the mechanisms underlying sex-based differences is necessary in order to develop a more effective and personalized therapeutic approach.

Non-Musculoskeletal Benefits of Vitamin D beyond the Musculoskeletal System

Vitamin D, a fat-soluble prohormone, is endogenously synthesized in response to sunlight or taken from dietary supplements. Since vitamin D receptors are present in most tissues and cells in the body, the mounting understanding of the role of vitamin D in humans indicates that it does not only play an important role in the musculoskeletal system, but has beneficial effects elsewhere as well. This review summarizes the metabolism of vitamin D, the research regarding the possible risk factors leading to vitamin D deficiency, and the relationships between vitamin D deficiency and numerous illnesses, including rickets, osteoporosis and osteomalacia, muscle weakness and falls, autoimmune disorders, infectious diseases, cardiovascular diseases (CVDs), cancers, and neurological disorders. The system-wide effects of vitamin D and the mechanisms of the diseases are also discussed. Although accumulating evidence supports associations of vitamin D deficiency with physical and mental disorders and beneficial effects of vitamin D with health maintenance and disease prevention, there continue to be controversies over the beneficial effects of vitamin D. Thus, more well-designed and statistically powered trials are required to enable the assessment of vitamin D’s role in optimizing health and preventing disease.

The role of vitamin D in autoimmune diseases: could sex make the difference?

Over the last decades, a central role for vitamin D in immune modulation has been well established. The active form of vitamin D, i.e., 1,25-dihydroxyvitamin D, through the interaction with vitamin D receptor, exerts different activities on the innate and adaptive immune system, among which suppression of inflammation and promotion of tolerogenic responses. Vitamin D insufficiency has been linked to autoimmune disorders that commonly display significant differences between females and males due to genetic, epigenetic, hormonal, and environmental factors. Notably, a number of studies recently showed a cross-talk between vitamin D and the sex hormone estrogen. Estrogen-mediated effects on immune response may favor a Th1 profile or a Th2 profile, depending on hormone concentration. Thus, estrogen-mediated effects appear to be variable on autoimmunity depending on its concentration but also on the pathogenic mechanisms underlying the different autoimmune diseases (i.e., Th1- or Th2-mediated diseases). Notably, estrogen has been demonstrated to enhance vitamin D function favoring its accumulation, and increasing the expression of vitamin D receptor, thus resulting in a more potent anti-inflammatory response in females than males. On the other hand, vitamin D has been shown to downregulate in immune cells the expression of aromatase, which converts testosterone to estrogen, leading to a decrease in estrogen level. Overall, available data allow us to hypothesize a higher protective effect of vitamin D-based therapeutic approaches in women, at least in fertile age, than in men. Future studies are needed to expand current knowledge on the immunomodulatory role of vitamin D in a sex and gender perspective, paving the way to a more personalized therapeutic approach in autoimmune diseases.

Bile Acid Signaling in Inflammatory Bowel Diseases

Bile acids are a group of chemically different steroids generated at the host/microbial interface. Indeed, while primary bile acids are the end-product of cholesterol breakdown in the host liver, secondary bile acids are the products of microbial metabolism. Primary and secondary bile acids along with their oxo derivatives have been identified as signaling molecules acting on a family of cell membrane and nuclear receptors collectively known as "bile acid-activated receptors." Members of this group of receptors are highly expressed throughout the gastrointestinal tract and mediate the bilateral communications of the intestinal microbiota with the host immune system. The expression and function of bile acid-activated receptors FXR, GPBAR1, PXR, VDR, and RORγt are highly dependent on the structure of the intestinal microbiota and negatively regulated by intestinal inflammation. Studies from gene ablated mice have demonstrated that FXR and GPBAR1 are essential to maintain a tolerogenic phenotype in the intestine, and their ablation promotes the polarization of intestinal T cells and macrophages toward a pro-inflammatory phenotype. RORγt inhibition by oxo-bile acids is essential to constrain Th17 polarization of intestinal lymphocytes. Gene-wide association studies and functional characterizations suggest a potential role for impaired bile acid signaling in development inflammatory bowel diseases (IBD). In this review, we will focus on how bile acids and their receptors mediate communications of intestinal microbiota with the intestinal immune system, describing dynamic changes of bile acid metabolism in IBD and the potential therapeutic application of targeting bile acid signaling in these disorders.

The roles of vitamin D and cathelicidin in type 1 diabetes susceptibility

Type 1 diabetes has an increasingly greater incidence and prevalence with no cure available. Vitamin D supplementation is well documented to reduce the risk of developing type 1 diabetes. Being involved in the modulation of cathelicidin expression, the question whether cathelicidin may be one of the underlying cause arises. Cathelicidin has been implicated in both the development and the protection against type 1 diabetes by mediating the interplay between the gut microbiome, the immune system and β cell function. While its potential on type 1 diabetes treatment seems high, the understanding of its effects is still limited. This review aims to contribute to a more comprehensive understanding of the potential of vitamin D and cathelicidin as adjuvants in type 1 diabetes therapy.

9-cis Retinoic acid and 1.25-dihydroxyvitamin D3 drive differentiation into IgA+ secreting plasmablasts in human naïve B cells

Calcitriol and 9-cis retinoic acid (9cRA) play a fundamental role in shaping the adaptive immune response by altering the Ig profile and the differentiation of B cells, controlled by their corresponding nuclear receptors, VDR and RAR. Herein, after the establishment of a plasmablast differentiation culture, we investigated how both ligands modulate human naïve B cell differentiation and to which extent VDR/RXR and RAR/RXR signaling interferes. Calcitriol and 9cRA mediated activation of purified naïve B cells resulted in a strong differentiation of CD27⁺ CD38⁺ plasmablasts and antibody secretion. The significant IgA response was preceded by a strong induction of α-germline transcription (GLT). Induction of αGLT and consecutively IgA secretion driven by calcitriol is a novel observation and we show by magnetic chromatin IP that this was mediated by recruitment of the VDR to the TGF-β promoter thus inducing TGF-β expression. Finally, as revealed by transcriptomic profiling calcitriol and 9cRA modulate several signals required for differentiation and isotype switching in a noncompeting but rather additive manner. Calcitriol and 9cRA participate in the control of the IgA response in human activated naïve B cells. The balance between both ligands may be an important factor in channeling humoral immune responses toward a protective direction.

The effects of vitamin D on acute viral respiratory infections: A rapid review

BRIEF OVERVIEW

Current evidence suggests vitamin D replacement may reduce risk for acute respiratory tract infections (ARTI) in people with deficiency or insufficiency, although the effects of supplementation on incidence and severity of ARTI in the general population remain unknown. Oral vitamin D supplemzentation taken at routine doses appears to be generally safe and well tolerated.

VERDICT

Current experimental evidence remains inconclusive regarding the effects of vitamin D supplementation in the general population for the prevention and treatment of acute respiratory tract infections (ARTI). There is also insufficient evidence to draw conclusions regarding the impact of vitamin D supplementation on the severity or duration of ARTI, nor on outcomes related to lung injury or hospitalization from ARTI. Based on this rapid review, sources of significant heterogeneity in published clinical trials include: differences study populations, inconsistent assessment of serum status at baseline, dosing variability, varying routes of administration, and/or inconsistent definitions of outcome measures. Experimental evidence and observations in large cohorts are generally consistent that vitamin D deficiency (<50 nmol/L [<20 ng/mL]) and insufficiency (<75 nmol/L [<30 ng/mL]) of serum 25-hydroxycholecalciferol (25-OHD) concentration is associated with increased risk of ARTI, and supplementation for those with deficiency/insufficiency may lead to clinically meaningful reductions in the incidence of ARTI. In this rapid review, vitamin D was primarily administered as oral supplementation, and findings suggested significant differences in daily oral dosing compared to periodic bolus dosing. Based on the available experimental evidence, vitamin D supplementation appears to have a high margin of safety with very few adverse events reported in children or adults from a variety of dosing strategies. Future clinical trials on vitamin D should consider the sources of heterogeneity in the existing experimental research and design trials that account for baseline status, evaluate the potential for prevention and treatment in at risk populations, standardize dosing strategies, assess product quality, assess outcomes according to gold standard definitions/diagnostic methods, and delineate viral ARTI from other causes when possible. The available mechanistic evidence related to immunological requirements for adequate vitamin D, the availability of observational and experimental evidence suggestive of clinically meaningful benefits (especially in deficient/insufficient participants), and the high margin of safety, should make vitamin D a high priority for additional clinical research during the current COVID-19 pandemic.