Oral vitamin D3 supplementation reduces monocyte-derived dendritic cell maturation and cytokine production in Crohn's disease patients. Inflammopharmacology. 2014;22:95-103. [PMID: 24374976 DOI: 10.1007/s10787-013-0197-1]

Synergistic Benefits of Dietary Strategies in the Management of IBD

PURPOSE OF REVIEW

Inflammatory bowel disease (IBD) patients commonly inquire about the role of diet in the onset and management of their disease process. This review sought to assess the impact of the inflammatory bowel diseases on the nutritional state of patients and evaluate the evidence supporting nutritional interventions as therapy.

RECENT FINDINGS

The role of nutrition has evolved from one of deficient nutrient and calorie replacement alone into a proactive therapeutic for treating active inflammatory disease symptoms. The realization that initiating total parenteral nutrition (TPN) in place of oral take could improve disease symptoms provided the first indication that food intake played a causative role in the IBD. The evolution of TPN to enteral nutrition improved tolerance and reduced side effects but clouded the role of oral intake in the pathophysiology of IBD. Advanced understanding of the role of the microbiota in IBD combined with recognition of the influence of nutrients on microbial composition have ushered in a new era of food as therapy. The role of nutrition in IBD has evolved significantly over the past 30-40 years. From complete elimination of oral intake to the carefully curated menu intended to mold the intestinal microbiota to a non-inflammatory milieu has revolutionized the approach to dietary intervention. Additional studies are warranted to optimize dietary intervention strategies.

The use of vitamin D for patients with inflammatory bowel diseases

As vitamin D (VD) plays an essential role in inflammatory bowel diseases (IBD), this systematic review aimed to update the participation of this vitamin in the prevention or remission of these diseases. This review has included studies in MEDLINE-PubMed, EMBASE, and Cochrane databases. The authors have followed PRISMA (Preferred Reporting Items for a Systematic Review and Meta-analysis) guidelines. According to the inclusion and exclusion criteria, twenty-two randomized clinical trials were selected. In total, 1,209 patients were included in this systematic review: 1034 received only VD and 175 received VD in combination with calcium. The average doses of VD supplementation were from oral 400 IU daily to 10,000 IU per kilogram of body weight. Single injection of 300,000 IU of VD was also used. Several studies have shown the crucial role that VD plays in the therapeutic approach of IBD due to its effects on the immune system. It effectively decreased inflammatory cytokines such as TNF-α and IFN-γ (p<0.05) and provided a reduction in disease activity assessed through different scores such as Crohn's Disease Activity Index (CDAI) (p<0.05) and Ulcerative Colitis Disease Activity Index (UCDAI) (p<0.05). Unfortunately, the available clinical trials are not standardized for of doses and routes of administration. Existing meta-analyses are biased because they compare studies using different doses or treatments in combination with different drugs or supplements such as calcium. Even though VD has crucial effects on inflammatory processes, there is still a need for standardized studies to establish how the supplementation should be performed and the doses to be administered.

Dendritic cells: the yin and yang in disease progression

Dendritic cells (DCs) are antigen presenting cells that link innate and adaptive immunity. DCs have been historically considered as the most effective and potent cell population to capture, process and present antigens to activate naïve T cells and originate favorable immune responses in many diseases, such as cancer. However, in the last decades, it has been observed that DCs not only promote beneficial responses, but also drive the initiation and progression of some pathologies, including inflammatory bowel disease (IBD). In line with those notions, different therapeutic approaches have been tested to enhance or impair the concentration and role of the different DC subsets. The blockade of inhibitory pathways to promote DCs or DC-based vaccines have been successfully assessed in cancer, whereas the targeting of DCs to inhibit their functionality has proved to be favorable in IBD. In this review, we (a) described the general role of DCs, (b) explained the DC subsets and their role in immunogenicity, (c) analyzed the role of DCs in cancer and therapeutic approaches to promote immunogenic DCs and (d) analyzed the role of DCs in IBD and therapeutic approaches to reduced DC-induced inflammation. Therefore, we aimed to highlight the "yin-yang" role of DCs to improve the understand of this type of cells in disease progression.

Genotype Prevalence of Lactose Deficiency, Vitamin D Deficiency, and the Vitamin D Receptor in a Chilean Inflammatory Bowel Disease Cohort: Insights from an Observational Study

Lactose intolerance (LI) and vitamin D deficiency (VDD) have been linked to inflammatory bowel disease (IBD). We conducted an observational study in 192 Chilean IBD patients to investigate the prevalence of a specific gene variant (LCT-13910 CC genotype) associated with LI and the prevalence of VDD/Vitamin D Receptor (VDR) gene variants. Blood samples were analyzed using Illumina's Infinium Global Screening Array. The LCT-13910 CC genotype was found in 61% of IBD patients, similar to Chilean Hispanic controls and lower than Chilean Amerindian controls. The frequency of the LCT-13910-C allele in Chilean IBD patients (0.79) was comparable to the general population and higher than Europeans (0.49). Regarding VDR and VDD variants, in our study, the rs12785878-GG variant was associated with an increased risk of IBD (OR = 2.64, CI = 1.61-4.32; p-value = 0.001). Sixty-one percent of the Chilean IBD cohort have a genetic predisposition to lactose malabsorption, and a significant proportion exhibit genetic variants associated with VDD/VDR. Screening for LI and VDD is crucial in this Latin American IBD population.

A Clinical Study to Evaluate the Role of Vitamin D3 in Allergic Rhinitis

Allergic rhinitis is a common and chronic immunoglobulin E-mediated inflammation of nasal mucosa induced after allergen exposure. Allergic rhinitis is a global health problem that causes major illness and affects patient's social life, sleep, school and work performance. Various studies have implicated the association between low serum vitamin D levels and allergic diseases. Active form of Vitamin D3 has been shown to have immunoregulatory effect on both innate and adaptive immunity, which can significantly affect the outcome of allergic responses in allergic rhinitis. The study aims to evaluate effectiveness of Oral Vitamin D3 supplementation as an adjunct to standard therapy, in the management of allergic rhinitis. The present study is a prospective study in which 80 subjects were recruited and were randomly divided into two groups. The study group received oral vitamin D3 (60,000 IU) along with intranasal steroid spray while control group received only intranasal steroid spray for 4 weeks. The response in both the groups was compared by evaluating total nasal symptom score (TNSS). Subjects of allergic rhinitis showed deficiency in vitamin D indicated by mean serum vitamin D levels of 15 ± 2.42 ng/ml in the study group and 14.72 ± 2.64 ng/ml in the control group. The pre treatment mean TNSS score was 10.45 ± 3.1 in the study group and 11.43 ± 2.35 in the control group. The post treatment mean TNSS score was 2.1 ± 0.21 in the study group and 3.85 ± 0.76 in the control group. A significant reduction in symptoms score was observed after 4 weeks of oral vitamin D3 supplementation. The difference between two groups was found to be statistically significant (p value < 0.05).

Title: Understanding a Low Vitamin D State in the Context of COVID-19

While a low vitamin D state has been associated with an increased risk of infection by SARS-CoV-2 in addition to an increased severity of COVID-19 disease, a causal role is not yet established. Here, we review the evidence relating to i) vitamin D and its role in SARS-CoV-2 infection and COVID-19 disease ii) the vitamin D status in the Irish adult population iii) the use of supplemental vitamin D to treat a deficient status and iv) the application of the Bradford-Hill causation criteria. We conclude that reverse causality probably makes a minimal contribution to the presence of low vitamin D states in the setting of COVID-19. Applying the Bradford-Hill criteria, however, the collective literature supports a causal association between low vitamin D status, SARS-CoV-2 infection, and severe COVID-19 (respiratory failure, requirement for ventilation and mortality). A biologically plausible rationale exists for these findings, given vitamin D's role in immune regulation. The thresholds which define low, deficient, and replete vitamin D states vary according to the disease studied, underscoring the complexities for determining the goals for supplementation. All are currently unknown in the setting of COVID-19. The design of vitamin D randomised controlled trials is notoriously problematic and these trials commonly fail for a number of behavioural and methodological reasons. In Ireland, as in most other countries, low vitamin D status is common in older adults, adults in institutions, and with obesity, dark skin, low UVB exposure, diabetes and low socio-economic status. Physiological vitamin D levels for optimal immune function are considerably higher than those that can be achieved from food and sunlight exposure alone in Ireland. A window exists in which a significant number of adults could benefit from vitamin D supplementation, not least because of recent data demonstrating an association between vitamin D status and COVID-19. During the COVID pandemic, we believe that supplementation with 20-25ug (800-1000 IU)/day or more may be required for adults with apparently normal immune systems to improve immunity against SARS-CoV-2. We expect that higher monitored doses of 37.5-50 ug (1,500-2,000)/day may be needed for vulnerable groups (e.g., those with obesity, darker skin, diabetes mellitus and older adults). Such doses are within the safe daily intakes cited by international advisory agencies.

Vitamin D in Inflammatory Bowel Diseases. Mechanisms of Action and Therapeutic Implications

(1) Background: Vitamin D is an immunoregulatory factor influencing intestinal homeostasis. Recent evidence supports a central role of this micronutrient in the course of Inflammatory Bowel Diseases (IBD). This narrative review aims to provide a general overview of the possible biological mechanisms of action of vitamin D and its therapeutic implications in IBD. (2) Methods: A systematic electronic search of the English literature up to October 2021 was performed using Medline and the Cochrane Library. Only papers written in English that analyzed the role of vitamin D in IBD were included. (3) Results: In vitro and animal studies reported that vitamin D signaling improves epithelial barrier integrity regulating the expression of several junctional proteins, defensins, and mucins, modulates the inflammatory response, and affects gut microbiome composition. Recent studies also suggest that vitamin D deficiency is highly prevalent among IBD patients and that low serum levels correlate with disease activity and, less clearly, with disease course. (4) Conclusions: An increasing body of evidence suggests some role of vitamin D in the pathophysiology of IBD, nonetheless the underlying mechanisms have been so far only partially elucidated. A strong correlation with disease activity has been reported but its implication in the treatment is still undefined. Thus, studies focused on this issue, the definition of vitamin D levels responsible for clinical effects, and the potential role of vitamin D as a therapeutic agent are strongly encouraged.

Vitamin D Therapy in Adults With Inflammatory Bowel Disease: A Systematic Review and Meta-Analysis

BACKGROUND

Vitamin D deficiency has been implicated in the pathogenesis of inflammatory bowel disease. Emerging literature suggests that optimization of vitamin D levels may be associated with improvements in disease activity and quality of life. We conducted a meta-analysis exploring the effect of vitamin D on serum 25-hydroxyvitamin D (s-25[OH]D) levels, clinical improvement, and biomarkers.

METHODS

MEDLINE, EMBASE, the Cochrane Library, and sources for grey literature were searched from inception until September 2019. The primary outcome was s-25(OH)D mean differences. Heterogeneity was assessed using the χ 2 test and the I2 statistic. Review Manager software v. 5.3 was used.

RESULTS

Twelve randomized controlled trials (n = 611) and 4 observational studies (n = 359) were included in the meta-analysis. On average, in the randomized controlled trials, vitamin D supplementation increased s-25(OH)D levels by 15.50 ng/mL (95% confidence interval [CI], 11.08-19.92, P ≤ 0.00001, I2 = 90%) and in observational studies they increased by 18.39 ng/mL (95% CI, 8.91-27.88, P = 0.0001, I2 = 82%). Subgroup analyses between vitamin D and placebo groups revealed that vitamin D increased s-25(OH)D by 14.85 ng/mL (95% CI, 9.96-19.73, P ≤ 0.00001, I2 = 90%) and when high doses of vitamin D were compared with low doses, high doses increased s-25(OH)D by 18.27 ng/mL (95% CI, 5.44-31.10, P = 0.005, I2 = 90%). The Harvey Bradshaw Index improved by -1.47 points (95% CI, -2.47 to -0.47, P = 0.004, I2 = 0%) and the high-sensitivity C-reactive protein decreased by -1.58 mg/L (95% CI, -2.95 to -0.21, P = 0.02, I2 = 0%).

CONCLUSIONS

Vitamin D supplementation in patients with IBD and vitamin D deficiency is effective at correcting vitamin D levels and is associated with improvement in clinical and biochemical disease activity scores.

The role of vitamin D in inflammatory bowel disease: a guide for clinical practice

INTRODUCTION

Inflammatory bowel disease (IBD) is a chronic inflammatory condition of the gastrointestinal tract that carries significant morbidity and mortality. Given the need to identify modifiable risk factors to prevent IBD development and to mitigate disease severity, vitamin D has become a major candidate of interest.

AREAS COVERED

In this review, we discuss the regulatory role played by vitamin D in intestinal immune homeostasis, updates in the recent literature exploring its role in de novo IBD pathogenesis and established IBD activity. We also discuss societal recommendations on its therapeutic role in maintaining bone health and future directions for studying its role in regulating disease activity.

EXPERT OPINION

In contrast to findings from earlier studies suggesting a causal role in IBD, recent findings indicate that vitamin D deficiency may be a sequela rather than a cause of IBD. Additionally, clinical trials exploring vitamin D therapy in reducing disease activity remain inconclusive thus far, with the current evidence best supporting a therapeutic role of vitamin D in bone health. Future studies are needed to clarify the role of vitamin D in IBD development and disease activity and to determine its therapeutic potential for IBD disease activity.

Vitamin D in Acute Campylobacteriosis-Results From an Intervention Study Applying a Clinical Campylobacter jejuni Induced Enterocolitis Model

Human Campylobacter infections are progressively rising and of high socioeconomic impact. In the present preclinical intervention study we investigated anti-pathogenic, immuno-modulatory, and intestinal epithelial barrier preserving properties of vitamin D applying an acute campylobacteriosis model. Therefore, secondary abiotic IL-10^−/− mice were perorally treated with synthetic 25-OH-cholecalciferol starting 4 days before peroral Campylobacter jejuni infection. Whereas, 25-OH-cholecalciferol application did not affect gastrointestinal pathogen loads, 25-OH-cholecalciferol treated mice suffered less frequently from diarrhea in the midst of infection as compared to placebo control mice. Moreover, 25-OH-cholecalciferol application dampened C. jejuni induced apoptotic cell responses in colonic epithelia and promoted cell-regenerative measures. At day 6 post-infection, 25-OH-cholecalciferol treated mice displayed lower numbers of colonic innate and adaptive immune cell populations as compared to placebo controls that were accompanied by lower intestinal concentrations of pro-inflammatory mediators including IL-6, MCP1, and IFN-γ. Remarkably, as compared to placebo application synthetic 25-OH-cholecalciferol treatment of C. jejuni infected mice resulted in lower cumulative translocation rates of viable pathogens from the inflamed intestines to extra-intestinal including systemic compartments such as the kidneys and spleen, respectively, which was accompanied by less compromised colonic epithelial barrier function in the 25-OH-cholecalciferol as compared to the placebo cohort. In conclusion, our preclinical intervention study provides evidence that peroral synthetic 25-OH-cholecalciferol application exerts inflammation-dampening effects during acute campylobacteriosis.

Serum leptin levels correlate negatively with the capacity of vitamin D to modulate the in vitro cytokines production by CD4+ T cells in asthmatic patients

Both obesity and low vitamin D levels have been associated with allergic asthma (AA) severity. In the present study, severity of AA was associated with obesity but to the in vitro IgE production. In those patients, higher levels of IL-5, IL-6 and IL-17 were quantified in CD4⁺ T-cell cultures as compared with patients with mild and moderate AA. In addition, the lowest IL-10 levels were detected in the cell cultures from patients with a worse prognosis. Interestingly, the occurrence of AA elevates the plasma levels of leptin, and this adipokine was positively correlated with the release of IL-5, IL-6 and IL-17, but inversely correlated with IL-10 production, by CD4⁺ T-cells from patients. In AA-derived CD4⁺ T-cell cultures, 1,25(OH)2D3 was less efficient at inhibiting IL-5, IL-6 and IL-17 production, and up regulating IL-10 release, as those from healthy subjects. Interestingly, the in vitro immunomodulatory effects of vitamin D were inversely correlated with serum leptin levels. In summary, our findings suggested that obesity, probably due to the overproduction of leptin, negatively impacts AA as it favors imbalance between Th2/Th17 and regulatory phenotypes. The deleterious effects of leptin may also be due to its ability to counter-regulate the immunosuppressive effects of vitamin D.

The Role of Vitamin D in Inflammatory Bowel Disease - Assessing Therapeutic and Preventive Potential of Supplementation and Food Fortification

Inflammatory bowel diseases are a group of chronic inflammatory conditions that affect gastrointestinal tract due to inapt and continuous immune activation in response to a myriad of predisposing factors (most notably genetics, environmental impact and gut microbiota composition). It has been shown that vitamin D status can also play a role in the disease pathogenesis, as its deficiency is commonly observed in two major forms of inflammatory bowel diseases - Crohn's disease and ulcerative colitis. Mounting evidence supports the concept of intricate relationship between gut dysbiosis and vitamin D metabolism, while suboptimal levels of this vitamin have been linked to increased clinical disease relapse rates, inadequate response to drugs, as well as decreased quality of life in patients with Crohn's disease and ulcerative colitis. Consequently, the pertinent question is whether increased vitamin D supplementation and (on a population level) food fortification may bring significant benefit to the affected individuals. In this short review we discuss the synthesis, functions, status and food sources of vitamin D, appraise biotechnological facets of vitamin D status analysis and food fortification, and concentrate on novel developments in the field that describe its influence on intestinal microbiota and inflammatory bowel disease.

Vitamin D in Inflammatory Bowel Disease: Biological, Clinical and Therapeutic Aspects

BACKGROUND

Vitamin D has an immunoregulatory action in Inflammatory Bowel Disease (IBD) as well as other immune-mediated disorders. Its influence on intestinal permeability, innate and adaptive immunity, and the composition and diversity of the microbiota contribute to the maintenance of intestinal homeostasis. Patients with IBD have a greater prevalence of vitamin D deficiency than the general population, and a possible association between this deficit and a worse course of the disease. However, intervention studies in patients with IBD have proved inconclusive.

OBJECTIVE

To review all the evidence concerning the role of vitamin D as an important factor in the pathophysiology of IBD, review the associations found between its deficiency and the prognosis of the disease, and draw conclusions for the practical application from the main intervention studies undertaken.

METHODS

Structured search and review of basic, epidemiological, clinical and intervention studies evaluating the influence of vitamin D in IBD, following the basic principles of scientific data.

RESULTS

Vitamin D deficiency is associated with disease activity, quality of life, the consumption of social and healthcare resources, and the durability of anti-TNFα biological treatment. Determination of new metabolites of vitamin D, measurement of its absorption capacity and questionnaires about sun exposure could help identify groups of IBD patients with a special risk of vitamin D deficiency.

CONCLUSION

Well-designed intervention studies are needed in IBD, with probably higher objective plasma doses of vitamin D to establish its efficacy as a therapeutic agent with immunomodulatory properties. Meanwhile, vitamin D deficiency should be screened for and corrected in affected patients in order to achieve adequate bone and phosphocalcic metabolism.

Efficacy of vitamin D in treatment of inflammatory bowel disease: A meta-analysis

BACKGROUND

Vitamin D (VitD) deficiency is prevalent in patient with inflammatory bowel disease (IBD). Recent studies have found that VitD can induce and maintain IBD remission through antibiosis, anti-inflammatory, and repair of intestinal mucosal barriers, thus improving the patient's disease activity and quality-of-life. The purpose of this meta-analysis is to evaluate the therapeutic effect and safety of VitD in the treatment of IBD.

METHODS

Published randomized controlled trials (RCTs) were included from electronic databases (PubMed, Embase, Cochrane library, Web of Science, and so forth). Cochrane handbook was applied to evaluate the methodological quality. The levels of 25(OH)D3, relapse rate, inflammation index, and adverse events were compared between the experimental group and the control group (placebo group). All statistical analyses were directed by Revman 5.3 software and statistical significance was defined as P < .05.

RESULTS

Eighteen RCTs involved 908 patients were included. Meta-analysis showed that VitD improved the 25(OH)D3 levels more significantly than the control group (ng/mL, weighted mean deviation [WMD] = 7.85, 95% CI (5.52, 10.18), P < .000001), and compared with lower doses, there were significant differences increasing 25(OH)D3 levels (WMD = 11.19, 95% CI [4.73, 17.65], P = .0007) in high-dose VitD treatment while there was no significant difference in the adverse events between 2 groups (WMD = 1.56, 95% CI [0.74, 3.29], P = .24). VitD reduced the relapse rate more significantly than the control group, but there were no significant differences between the low-dose and high-dose vitamin D treatment. The erythrocyte sedimentation rate (ESR) and high-sensitivity C-reactive protein (hsCRP) of the VitD and the control group showed no statistically significant difference (ESR [mm/h]: WMD = -0.22, 95% CI [-5.73, 5.29], P = .94; hsCRP (mg/dL): WMD = -0.53, 95% CI [-1.68, 0.62], P = .37).

CONCLUSIONS

The treatment of VitD in patients with IBD can improve the level of 25(OH)D3 and control the relapse rate of the disease, whose clinical curative effect is more accurate. Thus VitD should be recommended for the treatment of IBD, at least as an adjunctive treatment.

Role of Vitamin D in the Natural History of Inflammatory Bowel Disease

Inflammatory bowel disease [IBD], including ulcerative colitis and Crohn's disease, is a chronic and unpredictable condition characterised by alternating periods of remission interspersed with relapses. In recent years, accumulating support for an immunomodulating effect of vitamin D on both the innate and the adaptive immune systems has been presented. Through the vitamin D receptor, the active form of vitamin D, 1,25[OH]2D, induces antimicrobial peptide secretion, decreases dendritic cell activity, and promotes Th2 and regulatory T cell development and activity. In addition, vitamin D promotes an increased ratio of anti-inflammatory cytokines to pro-inflammatory cytokines. Studies in IBD point to a role for vitamin D in ameliorating disease outcome. Suboptimal circulating levels of 25-hydroxyvitamin D are common in IBD and appear to be associated with an increased risk of flares, IBD-related hospitalisations and surgeries, an inadequate response to tumour necrosis factor [TNF] inhibitors, a deterioration in quality of life, and low bone mineral density. With only few available randomised double-blind, placebo-controlled studies investigating therapeutic effects of vitamin D related to IBD, further research is necessary to determine the true therapeutic potential of vitamin D, as well as to define its optimal range in serum to achieve and maintain quiescence of disease. This review aims to summarise the latest knowledge on the extraskeletal effects of vitamin D in IBD, and outlines the potential deleterious consequences of vitamin D deficiency in this patient cohort.

Current, experimental, and future treatments in inflammatory bowel disease: a clinical review

Inflammatory bowel diseases (IBDs) may result from dysregulated mucosal immune responses directed toward the resident intestinal microbiota. This review describes the hallmark immunobiology of Crohn's disease and ulcerative colitis as well as therapeutic targets and mechanisms of action for current, experimental, and future treatments in IBD. Conventional therapies include 5-aminosalicylic acid, glucocorticosteroids, thiopurines, and methotrexate. Since 1997, monoclonal antibodies have gained widespread use. These consist of antibodies directed against pro-inflammatory cytokines such as tumor necrosis factor α, interleukin (IL)-12, and IL-23, or anti-homing antibodies directed against α4β7 integrin. Emerging oral therapies include modulators of intracellular signal transduction such as Janus kinase inhibitors. Vitamin D may help to regulate innate and adaptive immune responses. Modulation of the intestinal microbiota, using live microorganisms (probiotics), substrates for the colonic microbiota (prebiotics), or fecal microbiota transplantation (FMT), is in development. Dietary supplements are in widespread use, but providing evidence for their benefit is challenging. Stem cell treatment and nervous stimulation are promising future treatments.

Vitamin D administration leads to a shift of the intestinal bacterial composition in Crohn's disease patients, but not in healthy controls

OBJECTIVE

Dysbiosis is a common feature in the pathogenesis of inflammatory bowel diseases (IBD). Environmental factors, such as vitamin D deficiency, seem to play a role in the intestinal inflammation of IBD. The aim of this study was to investigate whether vitamin D administration has an impact on the bacterial composition in Crohn's disease (CD) compared to healthy controls (HC).

METHODS

A prospective, longitudinal, controlled interventional analysis was conducted in seven patients with CD in clinical remission and 10 HC to investigate the effect of orally administrated vitamin D on the intestinal bacterial composition using 16S ribosomal RNA gene amplicon sequencing. Clinical parameters were assessed.

RESULTS

In contrast to HC, microbial communities of CD patients changed significantly during early vitamin D administration. However, a further increase in vitamin D level was associated with a reversal of this effect and additionally with a decrease in the bacterial richness in the CD microbiome. Specific species with a high abundancy were found during vitamin D administration in CD, but not in HC; the abundancy of Alistipes, Barnesiella, unclassified Porphyromonadaceae (both Actinobacteria), Roseburia, Anaerotruncus, Subdoligranulum and an unclassified Ruminococaceae (all Firmicutes) increased significantly after 1-week vitamin D administration in CD.

CONCLUSIONS

Vitamin D has a specific influence on the bacterial communities in CD, but not in HC. Administration of vitamin D may have a positive effect in CD by modulating the intestinal bacterial composition and also by increasing the abundance of potential beneficial bacterial strains.

High-dose vitamin D3 supplementation decreases the number of colonic CD103+ dendritic cells in healthy subjects

PURPOSE

Vitamin D may induce tolerance in the intestinal immune system and has been shown to regulate the phenotype of tolerogenic intestinal dendritic cells (DCs) in vitro. It is unknown whether vitamin D supplementation affects human intestinal DCs in vivo, and we aimed to investigate the tolerability and effect on intestinal CD103⁺DCs of high-dose vitamin D₃ treatment in healthy subjects.

METHODS

Ten healthy subjects received a total of 480,000 IU oral vitamin D₃ over 15 days and colonic biopsies were obtained before and after intervention by endoscopy. Lamina propria mononuclear cells (LPMCs) were isolated from the biopsies, stained with DC surface markers and analysed with flow cytometry. Snap-frozen biopsies were analysed with qPCR for DC and regulatory T cell-related genes.

RESULTS

No hypercalcemia or other adverse events occurred in the test subjects. Vitamin D decreased the number of CD103⁺ DCs among LPMCs (p = 0.006). Furthermore, vitamin D induced mRNA expression of TGF-β (p = 0.048), TNF-α (p = 0.006) and PD-L1 (p = 0.02) and tended to induce IL-10 expression (p = 0.06). Multivariate factor analysis discriminated between pre- and post-vitamin D supplementation with a combined increased qPCR expression of PD1, PD-L1, TGF-β, IL-10, CD80, CD86, FOXP3, NFATc2 and cathelicidin.

CONCLUSION

High-dose vitamin D supplementation is well tolerated by healthy subjects and has a direct effect on the CD103⁺ DCs, local cytokine and surface marker mRNA expression in the colonic mucosa, suggestive of a shift towards a more tolerogenic milieu.

Important effect of micronutrient deficiency in inflammatory bowel disease

As is known to all, deficiencies of protein and other nutrients are common symptoms of inflammatory bowel disease (IBD). Nutrient deficiency is not only a manifestation of complicated diseases but also a cause of morbidity. Micronutrient is also the essential material for human health. However, there are few articles elaborating the influence of micronutrient deficiency. At present, choosing available food to keep healthy and to treat diseases is very popular, which is also suitable for IBD patients. Recent studies show that micronutrient deficiencies occur in more than half of patients with IBD, and deficiencies are more common in Crohn's disease than in ulcerative colitis, and in active disease than in disease in remission. Micronutrient deficiencies are associated with prolonged and complicated course of disease. The present review summarizes the effect of micronutrient deficiencies in IBD with regard to the definition of micronutrient, the deficiency status of micronutrient in IBD, the reasons for the lack of micronutrient and the role of micronutrient in the treatment of IBD.

Vitamin D modulates different IL-17-secreting T cell subsets in multiple sclerosis patients

Vitamin D deficiency is an environmental risk factor for MS, a Th17 cell-mediated autoimmune disease that results in demyelination in the CNS. Therefore, we aimed to evaluate the ability of in vitro 1,25(OH)2D in modulating different Th17 cell subsets in MS patients in remission phase. In the present study, the production of Th17-related cytokines (IL-1β, IL-6, IL-17, IL-22), as well as GM-CSF, was significantly higher in cell cultures from MS patients than in healthy subjects (HS). The 1,25(OH)2D reduced all pro-inflammatory cytokines essayed, mainly those released from HS cell cultures. The proportion of both IL-17⁺IFN-γ⁺ (CD4⁺ and CD8⁺) T cells and IL-17⁺IFN-γ^-CD8⁺ T cells was positively related with neurological disorders, determined by EDSS score. The addition of 1,25(OH)2D reduced not only these pathogenic T cell subsets but elevated the percentage of IL-10-secreting conventional (FoxP3⁺CD25⁺CD127^-CD4⁺) and non-conventional (IL-17⁺) regulatory-like T cells. Taken together, the results indicate that the active form of vitamin D should benefit MS patients by attenuating the percentage of pathogenic T cells. This effect could be direct and/or indirect, by enhancing classical and non-classical regulatory T cells.

Novel CD8+ T-Cell Subsets Demonstrating Plasticity in Patients with Inflammatory Bowel Disease

BACKGROUND

Distinct CD8+ T-cell subsets such as interleukin-17-expressing Tc17 and Foxp3-expressing Tcreg are functionally similar to CD4+ T cells. Though CD4+ T cells are dysregulated in patients with inflammatory bowel disease (IBD), CD8+ T cells are not well investigated. Vitamin D is an environmental factor which influences T-cell subsets. We assessed the prevalence of CD8+ T-cell subsets among peripheral blood mononuclear cells (PBMC) and lamina propria mononuclear cells (LPMC) of patients with Crohn's disease, patients with ulcerative colitis, and healthy controls. We then tested the effect of 1α,25-dihydroxyvitamin D3 on CD8+ T-cell subsets.

METHODS

A total of 73 patients with Crohn's disease, 49 patients with ulcerative colitis, and 47 healthy controls were studied. LPMC or PBMC were isolated and flow cytometry was performed. CD3+ T cells, isolated from PBMC, were cultured with or without 1α,25-dihydroxyvitamin D3, before flow cytometry.

RESULTS

In LPMC, the prevalence of Tcreg was higher in patients with IBD (P < 0.05), whereas Tc17 were higher in patients with ulcerative colitis compared with patients with Crohn's disease and healthy controls (P < 0.05). In PBMC, both Tcreg and Tc17 were higher in patients with IBD (P < 0.01). Double-expressing interferon-γ+ interleukin-17+ and Foxp3+ interleukin-17+ CD8+ T cells were also identified indicating possible CD8+ plasticity. 1α,25-dihydroxyvitamin D3 decreased interferon-γ-expressing Tc1 (P < 0.05), but had no effect on Tc17 or Tcreg.

CONCLUSIONS

The prevalence of novel CD8+ T-cell subsets is altered in patients with IBD. Double-expressing cells indicate plasticity and were identified in patients with IBD. Vitamin D may have a limited effect on CD8+ T cells by decreasing interferon-γ expression.

Vitamin D status in relation to Crohn's disease: Meta-analysis of observational studies

OBJECTIVES

Inconsistent findings have been published regarding vitamin D status among patients with Crohn's disease (CD) and the association with disease severity. We aimed to perform a meta-analysis evaluating serum 25-hydroxy vitamin D and 1,25 dehydroxyvitamin D among CD patients compared with healthy and non-healthy controls, the prevalence of vitamin D deficiency, and the association with disease.

METHODS

We searched MEDLINE, SCOPUS, EMBASE, and Google Scholar up to March 2015 for observational studies assessing serum vitamin D levels in CD patients. A total of 63 studies were included in the following four meta-analyses: 1) a meta-analysis on the mean difference of 25(OH)D levels in CD patients compared with healthy (number of studies = 27) and non-healthy (n = 25) controls; 2) a meta-analysis on the mean difference of 1,25(OH)2 D3 levels in CD patients compared with healthy (n = 7) and non-healthy (n = 8) controls; 3) a meta-analysis on the prevalence of vitamin D deficiency (n = 34); 4) a meta-analysis on the correlation coefficients between vitamin D status severity of CD (n = 6). Subgroup analysis and meta-regression were used to discover possible sources of between-study heterogeneity.

RESULTS

It was found that CD patients had lower levels of 25(OH)D compared with healthy (-3.99 ng/mL; 95% confidence interval [CI]: -5.91 to -2.08) but not non-healthy controls (-1.07 ng/mL; 95% CI: -2.84 to 0.70). There was also no significant mean difference for 1,25(OH)2 D3 for both healthy and non-healthy controls. Meta-analysis on the prevalence of vitamin D deficiency showed an overall prevalence of 57.7% (95% CI: 0.502-0.649). An inverse association was observed between serum vitamin D and severity of CD (-0.36; 95% CI: -0.48 to -0.24). Meta-regression showed that mean levels of 25(OH)D were decreased 0.09 for each unit change of latitude among CD patients compared with healthy controls (B = -0.09, P = 0.004, I(2) residual = 86.08%).

CONCLUSIONS

We found that patients with Crohn's disease had lower serum 25(OH)D concentrations compared with their healthy counterparts, and more than half of them have hypovitaminosis D. Moreover, there was an inverse correlation between circulating 25(OH)D concentrations and severity of Crohn's disease.

Micronutrient deficiencies in inflammatory bowel disease

PURPOSE OF REVIEW

Malnutrition, protein-energy, and micronutrient deficiencies are common among patients with inflammatory bowel disease (IBD). The deficiencies are a manifestation of the complicated disease and a cause of morbidity. The present review summarizes recent advances and evidence-based knowledge regarding micronutrients in relation to patients with IBD.

RECENT FINDINGS

Micronutrient deficiencies occur in more than half of patients with IBD. Most common are deficiencies of iron, B12, vitamin D, vitamin K, folic acid, selenium, zinc, vitamin B6, and vitamin B1. Deficiencies are more common in Crohn's disease than in ulcerative colitis, and more in active disease than at times of remission. Micronutrient deficiency is associated with prolonged and complicated course of disease. Iron deficiency is the most common cause for anemia. Definite diagnosis of B12 deficiency cannot be established by serum levels alone. Vitamin D and vitamin K deficiencies are thought to be associated with heightened inflammatory state. The relationship of these deficiencies with bone disease is controversial. The present review focuses on the significance, epidemiology, treatment options, and recommendations regarding micronutrient deficiencies in IBD.

SUMMARY

Micronutrient deficiencies are common and have clinical significance. High suspicion for micronutrient deficiencies is advocated so that treatable causes of morbidity are treated appropriately and late and irreversible sequlae are prevented.

Effects of high doses of vitamin D3 on mucosa-associated gut microbiome vary between regions of the human gastrointestinal tract

PURPOSE

Vitamin D is well known for its effects on bone mineralisation but has also been attributed immunomodulatory properties. It positively influences human health, but in vivo data describing vitamin D effects on the human gut microbiome are missing. We aimed to investigate the effects of oral vitamin D3 supplementation on the human mucosa-associated and stool microbiome as well as CD8(+) T cells in healthy volunteers.

METHODS

This was an interventional, open-label, pilot study. Sixteen healthy volunteers (7 females, 9 males) were endoscopically examined to access a total of 7 sites. We sampled stomach, small bowel, colon, and stools before and after 8 weeks of vitamin D3 supplementation. Bacterial composition was assessed by pyrosequencing the 16S rRNA gene (V1-2), and CD8(+) T cell counts were determined by flow cytometry.

RESULTS

Vitamin D3 supplementation changed the gut microbiome in the upper GI tract (gastric corpus, antrum, and duodenum). We found a decreased relative abundance of Gammaproteobacteria including Pseudomonas spp. and Escherichia/Shigella spp. and increased bacterial richness. No major changes occurred in the terminal ileum, appendiceal orifice, ascending colon, and sigmoid colon or in stools, but the CD8(+) T cell fraction was significantly increased in the terminal ileum.

CONCLUSION

Vitamin D3 modulates the gut microbiome of the upper GI tract which might explain its positive influence on gastrointestinal diseases, such as inflammatory bowel disease or bacterial infections. The local effects of vitamin D demonstrate pronounced regional differences in the response of the GI microbiome to external factors, which should be considered in future studies investigating the human microbiome.

Flow cytometry detection of vitamin D receptor changes during vitamin D treatment in Crohn's disease

Crohn's disease (CD) is a chronic inflammatory disease associated with a dysregulated T cell response towards intestinal microflora. Vitamin D has immune modulatory effects on T cells through the nuclear vitamin D receptor (VDR) in vitro. It is unclear how oral vitamin D treatment affects VDR expression. The aim of this study was to establish a flow cytometry protocol, including nuclear and cytoplasmic VDR expression, and to investigate the effects of vitamin D treatment on T cell VDR expression in CD patients. The flow cytometry protocol for VDR staining was developed using the human acute monocytic leukaemia cell line (THP-1). The protocol was evaluated in anti-CD3/CD28-stimulated peripheral blood mononuclear cells (PBMCs) from vitamin D3- (n = 9) and placebo-treated (n = 9) CD patients. Anti-VDR-stained PBMCs were examined by flow cytometry, and their cytokine production was determined by cytokine bead array. VDR, CYP27B1 and RXRα mRNA expression levels in CD4(+) T cells were measured by quantitative reverse transcriptase polymerase chain reaction. The flow cytometry protocol enabled detection of cytoplasmic and nuclear VDR expression. The results were confirmed by confocal microscopy and supported by correlation with VDR mRNA expression. VDR expression in CD4(+) T cells increased following stimulation. This VDR up-regulation was inhibited with 30% by vitamin D treatment compared to placebo in CD patients (P = 0027). VDR expression was correlated with in-vitro interferon-γ production in stimulated PBMCs (P = 0.01). Flow cytometry is a useful method with which to measure intracellular VDR expression. Vitamin D treatment in CD patients reduces T cell receptor-mediated VDR up-regulation.

Vitamin D and inflammatory bowel disease

Vitamin D deficiency has been recognized as an environmental risk factor for Crohn's disease since the early 80s. Initially, this finding was correlated with metabolic bone disease. Low serum 25-hydroxyvitamin D levels have been repeatedly reported in inflammatory bowel diseases together with a relationship between vitamin D status and disease activity. Subsequently, low serum vitamin D levels have been reported in various immune-related diseases pointing to an immunoregulatory role. Indeed, vitamin D and its receptor (VDR) are known to interact with different players of the immune homeostasis by controlling cell proliferation, antigen receptor signalling, and intestinal barrier function. Moreover, 1,25-dihydroxyvitamin D is implicated in NOD2-mediated expression of defensin-β2, the latter known to play a crucial role in the pathogenesis of Crohn's disease (IBD1 gene), and several genetic variants of the vitamin D receptor have been identified as Crohn's disease candidate susceptibility genes. From animal models we have learned that deletion of the VDR gene was associated with a more severe disease. There is a growing body of evidence concerning the therapeutic role of vitamin D/synthetic vitamin D receptor agonists in clinical and experimental models of inflammatory bowel disease far beyond the role of calcium homeostasis and bone metabolism.

Synovial fluid myeloid dendritic cells display important differences compared to monocyte-derived dendritic cells prepared in vitro

The object of this study was to characterise synovial fluid dendritic cells (SFDCs) with regard to morphology, phenotype and responses to 1,25hydroxy-cholecalciferol (1,25D) and lipopolysaccharide (LPS), and to compare these characteristics with those of peripheral blood (PB) monocyte-derived DCs (MDDCs). SF was aspirated from knees with inflammatory effusions. PB samples were obtained contemporaneously. SFDCs were separated by flow cytometry. Morphology was determined on cytosmears. Expression of accessory molecules, cytokines and prostaglandin synthases mRNA was quantified by reverse transcription PCR. Analyses were performed on freshly prepared DCs and after incubation with 1,25D and LPS, separately and in combination. SFDCs and MDDCs displayed broadly similar morphology. Expression of accessory molecules, cytokines, cyclooxygenase-2 (COX-2) and prostaglandin E-synthase (PGES) was similar. SFDCs, but not MDDCs, expressed prostaglandin D-synthase (PGDS). PGDS was lost on incubation with SFDCs, but was induced by 1,25D in MDDCs. LPS in the presence or absence of 1,25D, induced interleukin 23 (IL23), IL1β and tumour necrosis factor-α in SFDCs and MDDCs, with SFDC showing stronger expression of these cytokines. 1,25D in combination with LPS induced PGES and enhanced LPS induction of IL6 in SFDCs and MDDCs. LPS reduced 1,25D-induced expression of PGDS in MDDCs. SFDCs and MDDCs display similar basal characteristics but differ in PGDS expression and responsiveness to LPS and 1,25D. MDDCs have limitations as a model of SFDCs which have differentiated in vivo.