The vitamin D analog TX527 ameliorates disease symptoms in a chemically induced model of inflammatory bowel disease

Characterization of Bovine Intraepithelial T Lymphocytes in the Gut

Intraepithelial T lymphocytes (T-IELs), which constitute over 50% of the total T lymphocytes in the animal, patrol the mucosal epithelial lining to defend against pathogen invasion while maintaining gut homeostasis. In addition to expressing T cell markers such as CD4 and CD8, T-IELs display T cell receptors (TCR), including either TCRαβ or TCRγδ. Both humans and mice share similar T-IEL subsets: TCRγδ+, TCRαβ+CD8αα+, TCRαβ+CD4+, and TCRαβ+CD8αβ+. Among these subsets, human T-IELs are predominantly TCRαβ+ (over 80%), whereas those in mice are mostly TCRγδ+ (~60%). Of note, the majority of the TCRγδ+ subset expresses CD8αα in both species. Although T-IELs have been extensively studied in humans and mice, their profiles in cattle have not been well examined. Our study is the first to characterize bovine T-IELs using flow cytometry, where we identified several distinct features. The percentage of TCRγδ+ was comparable to that of TCRαβ+ T-IELs (both ~50% of CD3+), and the majority of bovine TCRγδ+ T-IELs did not express CD8 (CD8-) (above 60%). Furthermore, about 20% of TCRαβ+ T-IELs were CD4+CD8αβ+, and the remaining TCRαβ+ T-IELs were evenly distributed between CD4+ and CD8αβ+ (~40% of TCRαβ+ T-IELs each) with no TCRαβ+CD8αα+ identified. Despite these unique properties, bovine T-IELs, similar to those in humans and mice, expressed a high level of CD69, an activation and tissue-retention marker, and a low level of CD62L, a lymphoid adhesion marker. Moreover, bovine T-IELs produced low levels of inflammatory cytokines such as IFNγ and IL17A, and secreted small amounts of the immune regulatory cytokine TGFβ1. Hence, bovine T-IELs' composition largely differs from that of human and mouse, with the dominance of the CD8- population among TCRγδ+ T-IELs, the substantial presence of TCRαβ+CD4+CD8αβ+ cells, and the absence of TCRαβ+CD8αα+ T-IELs. These results provide the groundwork for conducting future studies to examine how bovine T-IELs respond to intestinal pathogens and maintain the integrity of the gut epithelial barrier in animals.

Close homolog of L1-deficient ameliorates inflammatory bowel disease by regulating the balance of Th17/Treg

OBJECTIVE

The aim of this study is to investigate the role of close homolog of L1 (CHL1) on inflammatory bowel disease (IBD), and the correlation with the balance of Th17/Treg.

METHODS

Dextran sodium sulfate (DSS)-induced IBD mice model was established. CHL1 knockout (KO) mice and CHL1 wild-type (WT) mice were subjected to DSS. CHL1 expression was detected using qRT-PCR. Weight was recorded daily, and disease activity index (DAI) score was assessed. The colon length and histological changes were measured. The number of neutrophils, macrophages and T cells was observed by immunohistochemistry. The expression of inflammatory cytokines and the proportion of Th17/Treg cells were detected by qRT-PCR and flow cytometry. The expression of RORγt, STAT3 and Foxp3 was detected by using immunohistochemistry and Western blot.

RESULTS

CHL1 expression was upregulated in DSS-induced IBD mice. DSS-CHLl-KO mice exhibited less weight loss than the DSS-CHLl-WT mice. The DAI score and histological score were decreased in DSS-CHLl-KO mice compared with DSS-CHLl-WT mice, while colon length was increased. Number of neutrophils, macrophages and T cells, and expression of TNF-α, IL-6, IL-17A, IL-21 and IL-23 were decreased in DSS-CHLl-KO mice, while IL-10 expression was increased. Moreover, CHL1-deficient inhibited Th17 cells differentiation and promoted Treg cells differentiation in IBD mice. CHL1-deficient also inhibited the expression of RORγt and STAT3, and promoted the expression of Foxp3 in IBD mice.

CONCLUSION

CHL1-deficient reduces the inflammatory response by regulating the balance of Th17/Treg in mice with IBD. CHL1 is expected to be a new target for the treatment of IBD.

Vitamin D Signaling in Inflammation and Cancer: Molecular Mechanisms and Therapeutic Implications

Vitamin D and its active metabolites are important nutrients for human skeletal health. UV irradiation of skin converts 7-dehydrocholesterol into vitamin D3, which metabolized in the liver and kidneys into its active form, 1α,25-dihydroxyvitamin D3. Apart from its classical role in calcium and phosphate regulation, scientists have shown that the vitamin D receptor is expressed in almost all tissues of the body, hence it has numerous biological effects. These includes fetal and adult homeostatic functions in development and differentiation of metabolic, epidermal, endocrine, neurological and immunological systems of the body. Moreover, the expression of vitamin D receptor in the majority of immune cells and the ability of these cells to actively metabolize 25(OH)D3 into its active form 1,25(OH)₂D3 reinforces the important role of vitamin D signaling in maintaining a healthy immune system. In addition, several studies have showed that vitamin D has important regulatory roles of mechanisms controlling proliferation, differentiation and growth. The administration of vitamin D analogues or the active metabolite of vitamin D activates apoptotic pathways, has antiproliferative effects and inhibits angiogenesis. This review aims to provide an up-to-date overview on the effects of vitamin D and its receptor (VDR) in regulating inflammation, different cell death modalities and cancer. It also aims to investigate the possible therapeutic benefits of vitamin D and its analogues as anticancer agents.

Effects of Vitamin D Supplementation on Inflammation, Colonic Cell Kinetics, and Microbiota in Colitis: A Review

Vitamin D is widely known to regulate bone health, but there is increasing evidence that it may also ameliorate colitis through inflammation, cell proliferation and apoptosis, and the microbiota. The purpose of this review is to systematically examine the mechanisms by which vitamin D reduces colitis. PubMed and Web of Science were searched for articles published between 2008 and 2019 using key words such as "vitamin D," "colitis," "inflammatory bowel disease," "inflammation," "apoptosis," "cell proliferation," and "gut bacteria". Retrieved articles were further narrowed and it was determined whether their title and abstracts contained terminology pertaining to vitamin D in relation to colitis in human clinical trials, animal studies, and cell culture/biopsy studies, as well as selecting the best match sorting option in relation to the research question. In total, 30 studies met the established criteria. Studies consistently reported results showing that vitamin D supplementation can downregulate inflammatory pathways of COX-2, TNF-α, NF-κB, and MAPK, modify cell kinetics, and alter gut microbiome, all of which contribute to an improved state of colitis. Although vitamin D and vitamin D analogs have demonstrated positive effects against colitis, more randomized, controlled human clinical trials are needed to determine the value of vitamin D as a therapeutic agent in the treatment of colitis.

Oral Nano Vitamin D Supplementation Reduces Disease Activity in Ulcerative Colitis: A Double-Blind Randomized Parallel Group Placebo-controlled Trial

INTRODUCTION

Vitamin D possesses anti-inflammatory properties and could be beneficial in ulcerative colitis (UC).

METHODS

We studied the effect of oral nano vitamin D3 supplementation on disease activity in active UC [ulcerative colitis disease activity index (UCDAI)≥3]. Patients with active UC and vitamin D <40 ng/mL were randomized to receive either oral nano vitamin D (60,000 IU/d×8 d) or placebo. They were evaluated for disease activity (UCDAI scores, C-reactive protein, erythrocyte sedimentation rate, and fecal calprotectin) at baseline and reassessed at 4 weeks. The response was defined as a 3-point reduction in UCDAI score at 4 weeks and reduction in inflammatory markers.

RESULTS

The median vitamin D levels increased from 15.4 to 40.83 mg/dL in vitamin D group (P≤0.001) and marginally from 13.45 to 18.85 mg/dL (P=0.027) in controls. The 3-point reduction in UCDAI was seen more often in vitamin D group as compared with the control (53% vs. 13%; P=0.001). Increase in vitamin D levels correlated with reduction in UCDAI score (P≤0.001; ρ=-0.713), C-reactive protein (P≤0.001; ρ=-0.603), and calprotectin (P=0.004; ρ=-0.368). Patients who achieved target vitamin D of >40 ng/mL (n=17) more often had a 3-point reduction in UCDAI (80% vs. 20%; P≤0.001) and reduction in grade of severity from 60% to 35% (P=0.038). Vitamin D administration (odds ratio, 9.17; 95% confidence interval, 2.02-41.67) and baseline histologic activity (odds ratio, 1.92; 95% confidence intervals, 1.2-3.08) independently predicted response.

CONCLUSIONS

Oral nano vitamin D supplementation in active UC is associated with a reduction in disease activity and severity grade and is seen more often in those who achieved a target vitamin D level of 40 ng/mL.

Vitamin D in prostate cancer

Signaling through the vitamin D receptor has been shown to be biologically active and important in a number of preclinical studies in prostate and other cancers. Epidemiologic data also indicate that vitamin D signaling may be important in the cause and prognosis of prostate and other cancers. These data indicate that perturbation of vitamin D signaling may be a target for the prevention and treatment of prostate cancer. Large studies of vitamin D supplementation will be required to determine whether these observations can be translated into prevention strategies. This paper reviews the available data in the use of vitamin D compounds in the treatment of prostate cancer. Clinical data are limited which support the use of vitamin D compounds in the management of men with prostate cancer. However, clinical trials guided by existing preclinical data are limited.

1,25(OH)2D3 deficiency-induced gut microbial dysbiosis degrades the colonic mucus barrier in Cyp27b1 knockout mouse model

Background

The relationship between disturbances of the gut microbiota and 1,25(OH)₂D₃ deficiency has been established both in humans and animal models with a vitamin D poor diet or a lack of sun exposure. Our prior study has demonstrated that Cyp27b1^−/− (Cyp27b1 knockout) mice that could not produce 1,25(OH)₂D₃ had significant colon inflammation phenotypes. However, whether and how 1,25(OH)₂D₃ deficiency due to the genetic deletion controls the gut homeostasis and modulates the composition of the gut microbiota remains to be explored.

Results

1,25(OH)₂D₃ deficiency impair the composition of the gut microbiota and metabolite in Cyp27b1^−/− mice, including Akkermansia muciniphila, Solitalea Canadensis, Bacteroides-acidifaciens, Bacteroides plebeius and SCFA production. 1,25(OH)₂D₃ deficiency cause the thinner colonic mucus layer and increase the translocation of the bacteria to the mesenteric lymph nodes. We also found 1,25(OH)₂D₃ supplement significantly decreased Akkermansia muciniphila abundance in fecal samples of Cyp27b1^−/− mice.

Conclusion

Deficiency in 1,25(OH)₂D₃ impairs the composition of gut microbiota leading to disruption of intestinal epithelial barrier homeostasis and induction of colonic inflammation. This study highlights the association between 1,25(OH)₂D₃ status, the gut microbiota and the colonic mucus barrier that is regarded as a primary defense against enteric pathogens.

Calcitriol and cancer therapy: A missed opportunity

The vitamin D receptor is expressed in most tissues of the body - and the cancers that arise from those tissues. The vitamin D signaling pathway is active in those tissues and cancers. This is at least consistent with the hypothesis that perturbing this signaling may have a favorable effect on the genesis and growth of cancers. Epidemiologic data indicate that vitamin D signaling may be important in the initiation and outcome of a number of types of cancer. Many studies have shown that calcitriol (1,25 dihydroxycholecalciferol) and other vitamin D compounds have antiproliferative, pro-apoptotic, anti-cell migration and antiangiogenic activity in a number of preclinical studies in many different cancer types. Unfortunately, the assessment of the activity of calcitriol or other vitamin D analogues in the treatment of cancer, as single agents or in combination with other anticancer agents has been stymied by the failure to adhere to commonly accepted principles of drug development and clinical trials conduct.

Vitamin D Receptor Expression in Dogs

Background

There is growing evidence linking low blood vitamin D concentration to numerous diseases in people and in dogs. Vitamin D influences cellular function by signaling through the vitamin D receptor (VDR). Little is known about which non‐skeletal tissues express the VDR or how inflammation influences its expression in the dog.

Objectives

To define which non‐skeletal canine tissues express the VDR and to investigate expression in inflamed small intestine.

Animals

Thirteen non‐skeletal tissues were collected prospectively from 6 control dogs. Thirty‐five dogs diagnosed with a chronic enteropathy (CE) and 24 control dogs were prospectively enrolled and duodenal biopsies were evaluated for VDR expression.

Methods

Prospective; blinded assessment of canine intestinal VDR. Dogs with CE were included once other identifiable causes of intestinal disease were excluded. Age matched controls were included with no intestinal clinical signs. VDR expression was assessed immunohistochemically in all samples, using a Rat IgG VDR monoclonal antibody. Quantitative real‐time polymerase chain reaction (qPCR) was also used for duodenal biopsies.

Results

VDR expression as assessed by immunohistochemistry (IHC) was highest in the kidney, duodenum, skin, ileum and spleen, and weak in the colon, heart, lymph node, liver, lung, and ovary. Gastric and testicular tissue did not express the VDR. There was no statistical difference in duodenal VDR expression between the 24 healthy dogs and 34 dogs with CE when quantified by either qPCR (P = 0.87) or IHC (P = 0.099).

Conclusions and Clinical Importance

The lack of down regulation of VDR expression in inflamed intestine contrasts with previous studies in humans. Our findings support future studies to investigate whether vitamin D and its analogues can be used to modulate intestinal inflammation in the dog.

Vitamin D Axis in Inflammatory Bowel Diseases: Role, Current Uses and Future Perspectives

Increasing evidence supports the concept that the vitamin D axis possesses immunoregulatory functions, with vitamin D receptor (VDR) status representing the major determinant of vitamin D’s pleiotropic effects. Vitamin D promotes the production of anti-microbial peptides, including β-defensins and cathelicidins, the shift towards Th2 immune responses, and regulates autophagy and epithelial barrier integrity. Impairment of vitamin D-mediated pathways are associated with chronic inflammatory conditions, including inflammatory bowel diseases (IBD). Interestingly, inhibition of vitamin D pathways results in dysbiosis of the gut microbiome, which has mechanistically been implicated in the development of IBD. Herein, we explore the role of the vitamin D axis in immune-mediated diseases, with particular emphasis on its interplay with the gut microbiome in the pathogenesis of IBD. The potential clinical implications and therapeutic relevance of this interaction will also be discussed, including optimizing VDR function, both with vitamin D analogues and probiotics, which may represent a complementary approach to current IBD treatments.

Nutritional Adequacy of the Specific Carbohydrate Diet in Pediatric Inflammatory Bowel Disease

INTRODUCTION

The specific carbohydrate diet (SCD) is an exclusion diet used as a therapy in inflammatory bowel disease. The aim of this study was to evaluate the nutritional adequacy of the SCD.

METHODS

Prospective dietary data for 12 weeks were analyzed for pediatric patients on the SCD. Intake of 20 key nutrients was compared to dietary recommended intake levels and nutrient intake data from similarly aged children from The National Health and Nutrition Examination Survey National Youth Fitness Survey in 2012.

RESULTS

Nine patients enrolled, with 8 patients completing the study. Six of 8 individuals completing the study had gained weight, 1 individual had weight loss, and 1 had no change in weight. Energy intake was significantly greater than 100% of the recommended daily allowance (RDA)/adequate intake for 64% of daily intakes completed for this study. The majority of participants' daily intakes met or exceeded the RDA for vitamins B2, B3, B5, B6, B7, B12, C, A, and E. One hundred percent of participants' intakes were below the RDA for vitamin D. Seventy-five percent of daily intakes were less than the RDA for calcium. The upper limit was met or exceeded for magnesium in 42% of daily intakes. Average vitamin A intake was significantly greater than the upper limit (P = 0.01).

CONCLUSIONS

Nutrient intake of pediatric inflammatory bowel disease patients on the SCD was adequate when compared with a healthy peer reference population, but adequacy was variable when compared with the dietary recommended intakes. Close monitoring with a multidisciplinary team for patients using the SCD as an alternative or adjunct therapy is recommend to ensure positive outcomes for overall patient health.

Immunoregulation of Inflammatory and Inhibitory Cytokines by Vitamin D3 in Patients with Inflammatory Bowel Diseases

Inflammatory bowel disease (IBD) is a group of idiopathic, chronic and relapsing inflammatory conditions of the gastrointestinal tract, caused by an aberrant and exaggerated immunological response in the gut. Supplementation of vitamin D3 in patients with IBD exerts both direct and indirect regulatory roles on the naïve T cells, thereby maintaining a balance between inflammatory and inhibitory cytokines. The direct actions of vitamin D3 on naïve T cells result in the proliferation of more regulatory T cells and inhibitory cytokines such as IL-4, IL-10 and IL-5. The binding of vitamin D to dendritic cells (DCs) through vitamin D receptors inhibits the action of IL-12 on DCs, resulting in the downregulation of Th1 and Th17. On the other hand, this interaction favours Th2 and Treg upregulation and facilitates the maintenance of immune homoeostasis between inflammatory and inhibitory cytokines which is essentially significant in the management of patients with IBD. The aim of this review was to explore the current and mounting scientific evidence on the roles of vitamin D3 in immunoregulation of inflammatory and inhibitory cytokines in patients with IBDs. An extensive literature search was conducted using keywords such as Vitamin D3*, IBD*, inflammatory cytokines*, inhibitory cytokines*, naïve-T-cells* and antigen presenting cells* through PubMed, SCOPUS and MEDLINE search engines. The results of the accumulated bodies of research that have been conducted demonstrate that vitamin D3 plays a major role not only in the immunoregulation of cytokines involved in the pathogenesis of IBDs but also in many other inflammatory disorders.

Vitamin D in Autoimmunity: Molecular Mechanisms and Therapeutic Potential

Over the last three decades, it has become clear that the role of vitamin D goes beyond the regulation of calcium homeostasis and bone health. An important extraskeletal effect of vitamin D is the modulation of the immune system. In the context of autoimmune diseases, this is illustrated by correlations of vitamin D status and genetic polymorphisms in the vitamin D receptor with the incidence and severity of the disease. These correlations warrant investigation into the potential use of vitamin D in the treatment of patients with autoimmune diseases. In recent years, several clinical trials have been performed to investigate the therapeutic value of vitamin D in multiple sclerosis, rheumatoid arthritis, Crohn’s disease, type I diabetes, and systemic lupus erythematosus. Additionally, a second angle of investigation has focused on unraveling the molecular pathways used by vitamin D in order to find new potential therapeutic targets. This review will not only provide an overview of the clinical trials that have been performed but also discuss the current knowledge about the molecular mechanisms underlying the immunomodulatory effects of vitamin D and how these advances can be used in the treatment of autoimmune diseases.

Health Care Maintenance for the Pediatric Patient With Inflammatory Bowel Disease

Nearly one-quarter of patients with inflammatory bowel disease (IBD) are younger than 20 years of age at diagnosis. Furthermore, the incidence of IBD in children continues to increase. Nevertheless, variation in management exists within the care of patients with IBD with regards to disease screening and preventive care. A multidisciplinary approach that involves the general practitioner and pediatric gastroenterologist is needed to routinely monitor growth, bone health, vitamin and mineral deficiencies, vaccination status, and endoscopic surveillance. It is also important to monitor for extraintestinal manifestations of IBD that may affect the liver, joints, skin, and eyes. The purpose of this article is to provide an updated overview of comprehensive care for pediatric patients with IBD.

Perinatal vitamin D levels are not associated with later risk of developing pediatric-onset inflammatory bowel disease: a Danish case-cohort study

Objective Basic and epidemiologic studies on inflammatory bowel disease (IBD) have suggested an association between vitamin D and IBD risk. Though, the literature on IBD - especially pediatric-onset IBD - and vitamin D is still in its cradle. We therefore wanted to examine if levels of 25(OH)D at birth were associated with increased risk of developing pediatric-onset IBD. Material and methods A case-cohort study composed of cases diagnosed with Crohn's disease, ulcerative colitis or indeterminate/unclassified colitis and healthy controls. Cases and controls were matched on date of birth and were born in the period 1981-2004. Cases were diagnosed before the age of 18 years. The concentration of 25(OH)D was assessed from neonatal dried blood spots using a highly sensitive liquid chromatography tandem mass spectrometry. Odds ratios (OR) were calculated using conditional logistic regression and two-way ANOVA were used to test for season and birth year 25(OH)D variations. A total of 384 matched pairs were included in the statistical analyses. Results No significant association were found between levels of 25(OH)D and IBD risk in the adjusted model (OR [95% CI] (per 25 nmol/L increase), 1.12 [0.88; 1.42], p = 0.35). 25(OH)D levels were found to fluctuate significantly with season (p < 0.001) and year (p < 0.001). Median/Q1-Q3 values for 25(OH)D were 27.1/16.5-39.5 nmol/L for cases and 25.7/16.1-39.4 nmol/L for controls. Conclusion Our study do not suggest that a window of vulnerability exist around time of birth in regards to 25(OH)D levels and later pediatric-onset IBD risk.

Association of vitamin D receptor gene polymorphisms and serum 25-hydroxyvitamin D levels with Crohn's disease in Chinese patients

BACKGROUND AND AIM

The vitamin D receptor (VDR) regulates immune responses and inflammation through binding with 1,25-dihydroxyvitamin D, the active form of vitamin D. The serum 25-hydroxyvitamin D (25(OH)D) level clinically reflects vitamin D status in the human body. We investigated the association of VDR polymorphisms and 25(OH)D levels in Chinese patients with Crohn's disease (CD).

METHODS

Vitamin D receptor polymorphisms (FokI, BsmI, ApaI, and TaqI) were genotyped by SNaPshot. Serum 25(OH)D levels were measured by electro-chemiluminescence immunoassay.

RESULTS

A total of 297 patients with CD and 446 controls were recruited. Compared with controls, mutant alleles and genotypes of BsmI and TaqI were less prevalent in patients with CD (all P < 0.05/4 = 0.0125). The AAC haplotype formed by BsmI, ApaI, and TaqI was also less prevalent in patients with CD (P = 0.004). Furthermore, 124 patients and 188 controls were randomly selected for measurements of 25(OH)D levels. Average 25(OH)D level was lower in patients with CD than in controls (15.46 ± 8.11 vs 21.64 ± 9.45 ng/mL, P < 0.001) and negatively linked to CD activity index (β = -0.829, P < 0.001), platelet count (β = -0.253, P < 0.001) and neutrophil percentage (β = -0.136, P = 0.005) in patients with CD. The ApaI mutant genotype and vitamin D deficiency (<20 ng/mL) were independently associated with CD (P = 0.009, P < 0.001, respectively). In patients with CD, vitamin D deficiency interacted with FokI, ApaI, and TaqI mutant genotypes (P = 0.027, P = 0.024, and P = 0.040, respectively).

CONCLUSIONS

Vitamin D receptor (BsmI, ApaI, and TaqI) mutations and lower 25(OH)D levels are associated with CD in Chinese patients. Moreover, VDR (FokI, ApaI, and TaqI) mutations and vitamin D deficiency may have a combined impact on CD.

The Role of Vitamin D in Inflammatory Bowel Disease

Vitamin D is known to be vital in maintaining bone health, mineralisation and for fracture prevention. It has also been implicated in a number of autoimmune diseases and has therefore been studied for its potential role in Inflammatory Bowel Disease (IBD). This review looks at the current literature on the role of vitamin D and its potential role as an immunomodulator, disease modifier and bone health in IBD patients. There is substantial supporting evidence of an important role from epidemiological, genetic and immunological studies, but there is also conflicting evidence and nothing proving to be definitive from clinical studies. There are also a number of confounders with IBD patients, as their lifestyles and medications may affect vitamin D levels. Murine studies have added vast amounts to our knowledge of vitamin D and its antimicrobial role, as well as its effect on immune cell proliferation other inflammatory molecules, such as Tumour Necrosis Factor-α (TNFα). It is clear that larger trials investigating the effects of oral supplementation of vitamin D in IBD patients are necessary.

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.

Vitamin D therapy in inflammatory bowel diseases: who, in what form, and how much?

BACKGROUND

The north–south geographical gradient of inflammatory bowel disease (IBD) prevalence, its epidemiology, the genetic association of vitamin D receptor polymorphisms, and results in animal models suggest that vitamin D plays an important role in the pathogenesis of IBD.

AIMS

The purpose of this review was to critically appraise the effectiveness and safety of vitamin D therapy in patients with IBD.

METHODS

MEDLINE, Scopus and Google Scholar were searched from inception to May 20, 2014 using the terms ‘Crohn’s disease’, ‘ulcerative colitis’ and ‘vitamin D’. Results: Vitamin D deficiency is common in patients with IBD. Limited clinical data suggest an association between low vitamin D concentration and increased disease activity in both ulcerative colitis (UC) and Crohn’s disease (CD). To date, only two small open label trials and one randomized controlled trial have shown a positive effect of vitamin D supplementation on disease activity in patients with CD; no effect has been shown for UC. An optimal vitamin D supplementation protocol for patients with IBD remains undetermined, but targeting serum 25-hydroxy vitamin D [25(OH)D] levels between 30 and 50 ng/mL appears safe and may have benefits for IBD disease activity. Depending on baseline vitamin D serum concentration, ileal involvement in CD, body mass index, and perhaps smoking status, daily vitamin D doses between 1800–10,000 international units/day are probably necessary.

CONCLUSION

Increasing preclinical and clinical evidence suggests a role for vitamin D deficiency in the development and severity of IBD. The possible therapeutic role of vitamin D in patients with IBD merits continued investigation.

Cell cycle arrest and apoptosis induced by 1α,25(OH)2D3 and TX 527 in Kaposi sarcoma is VDR dependent

We have previously shown that 1α,25(OH)2-Vitamin D3 [1α,25(OH)2D3] and its less calcemic analog TX 527 inhibit the proliferation of endothelial cells transformed by the viral G protein-coupled receptor associated to Kaposi sarcoma (vGPCR) and this could be partially explained by the inhibition of the NF-κB pathway. In this work, we further explored the mechanism of action of both vitamin D compounds in Kaposi sarcoma. We investigated whether the cell cycle arrest and subsequent apoptosis of endothelial cells (SVEC) and SVEC transformed by vGPCR (SVEC-vGPCR) elicited by 1α,25(OH)2D3 and TX 527 were mediated by the vitamin D receptor (VDR). Cell cycle analysis of SVEC and SVEC-vGPCR treated with 1α,25(OH)2D3 (10nM, 48h) revealed that 1α,25(OH)2D3 increased the percentage of cells in the G0/G1 phase and diminished the percentage of cells in the S phase of the cell cycle. Moreover, the number of cells in the S phase was higher in SVEC-vGPCR than in SVEC due to vGPCR expression. TX 527 exerted similar effects on growth arrest in SVEC-vGPCR cells. The cell cycle changes were suppressed when the expression of the VDR was blocked by a stable transfection of shRNA against VDR. Annexin V-PI staining demonstrated apoptosis in both SVEC and SVEC-vGPCR after 1α,25(OH)2D3 and TX 527 treatment (10nM, 24h). Cleavage of caspase-3 detected by Western blot analysis was increased to a greater extent in SVEC than in SVEC-vGPCR cells, and this effect was also blocked in VDR knockdown cells. Altogether, these results suggest that 1α,25(OH)2D3 and TX 527 inhibit the proliferation of SVEC and SVEC-vGPCR and induce apoptosis by a mechanism that involves the VDR.

Maintenance of optimal vitamin D status in children and adolescents with inflammatory bowel disease: a randomized clinical trial comparing two regimens

CONTEXT

Vitamin D promotes bone health and regulates the immune system, both important actions for pediatric patients with inflammatory bowel disease (IBD). The supplementation dose that would maintain optimal serum 25-hydroxyvitamin D concentration (25OHD ≥ 32 ng/mL) is unknown.

OBJECTIVE

The objective of the study was to compare two supplementation regimens' efficacy and safety in maintaining optimal 25OHD in children with IBD.

DESIGN

This was a randomized, not blinded, controlled trial.

SETTING

The trial was conducted in the Boston Children's Hospital Clinical and Translational Study Unit.

PARTICIPANTS

Sixty-three patients, aged 8-18 years with IBD and baseline 25OHD greater than 20 ng/mL were enrolled; 48 completed the study, and one withdrew for adverse events.

INTERVENTION

Arm A received 400 IU of oral vitamin D2 daily (n = 32). Arm B received 1000 IU daily in the summer/fall and 2000 IU in the winter/spring (n = 31).

MAIN OUTCOME

The main outcome was the probability of maintaining 25OHD of 32 ng/mL or greater in all trimonthly visits for 12 months.

RESULTS

Three participants in arm A (9.4%) and three in arm B (9.7%) achieved the primary outcome (P = .97). The incidence of adverse events, all minor, did not differ. More participants in arm A developed C-reactive protein level of 1 mg/dL or greater (31% vs 10%, P = .04) and IL-6 greater than 3 pg/mL (54% vs 27%, P = .05).

CONCLUSIONS

Daily oral vitamin D2 doses up to 2000 IU were inadequate to maintain optimal 25OHD but were well tolerated. The finding of lower incidence of elevated inflammatory markers and cytokines among participants receiving higher vitamin D2 doses merits further study.

Serum amino acids profile and the beneficial effects of L-arginine or L-glutamine supplementation in dextran sulfate sodium colitis

This study was conducted to investigate serum amino acids profile in dextran sulfate sodium (DSS)-induced colitis, and impacts of graded dose of arginine or glutamine supplementation on the colitis. Using DSS-induced colitis model, which is similar to human ulcerative colitis, we determined serum profile of amino acids at day 3, 7, 10 and 12 (5 days post DSS treatment). Meanwhile, effects of graded dose of arginine (0.4%, 0.8%, and 1.5%) or glutamine (0.5%, 1.0% and 2.0%) supplementation on clinical parameters, serum amino acids, colonic tight junction proteins, colonic anti-oxidative indicators [catalase, total superoxide dismutase (T-SOD), glutathione peroxidase (GSH-Px)], colonic pro-inflammatory cytokines [interleukin-1 beta (IL-1β), IL-6, IL-17 and tumor necrosis factor alpha (TNF-α)] in DSS-induced colitis were fully analyzed at day 7 and 12. Additionally, the activation of signal transduction pathways, including nuclear factor kappa B (NF-κB), mitogen-activated protein kinases (MAPK), phosphoinositide-3-kinases (PI3K)/PI3K-protein kinase B (Akt), and myosin light chain kinase (MLCK)- myosin light chain (MLC20), were analyzed using immunoblotting. Serum amino acids analysis showed that DSS treatment changed the serum contents of amino acids, such as Trp, Glu, and Gln (P<0.05). Dietary arginine or glutamine supplementation had significant (P<0.05) influence on the clinical and biochemical parameters (T-SOD, IL-17 and TNF-α) in colitis model. These results were associated with colonic NF-κB, PI3K-Akt and MLCK signaling pathways. In conclusion, arginine or glutamine could be a potential therapy for intestinal inflammatory diseases.

Review article: vitamin D and inflammatory bowel diseases

BACKGROUND

Vitamin D is traditionally associated with bone metabolism. The immunological effects of vitamin D have increasingly come into focus.

AIM

To review the evidence supporting a role of vitamin D in inflammatory bowel diseases.

METHODS

A comprehensive search was performed on PubMed using the terms 'crohn's disease' 'ulcerative colitis' and 'vitamin D'.

RESULTS

Vitamin D deficiency is common in patients with inflammatory bowel diseases (IBD) (16-95%) including those with recently diagnosed disease. Evidence supports immunological role of vitamin D in IBD. In animal models, deficiency of vitamin D increases susceptibility to dextran sodium sulphate colitis, while 1,25(OH)2 D3 ameliorates such colitis. One prospective cohort study found low predicted vitamin D levels to be associated with an increased risk of Crohn's disease (CD). Limited data also suggest an association between low vitamin D levels and increased disease activity, particularly in CD. In a large cohort, vitamin D deficiency (<20 ng/mL) was associated with increased risk of surgery (OR 1.8, 95% CI 1.2-2.5) in CD and hospitalisations in both CD (OR 2.1, 95% CI 1.6-2.7) and UC (OR 2.3, 95% CI 1.7-3.1). A single randomised controlled trial demonstrated that vitamin D supplementation may be associated with reduced frequency of relapses in patients with CD compared with placebo (13% vs. 29%, P = 0.06).

CONCLUSIONS

There is growing epidemiological evidence to suggest a role for vitamin D deficiency in the development of IBD and also its influence on disease severity. The possible therapeutic role of vitamin D in patients with IBD merits continued investigation.

Vitamin D receptor agonists target CXCL10: new therapeutic tools for resolution of inflammation

Understanding the many biological extraskeletal actions of vitamin D has increased in the past decades. Indeed, vitamin D and analogue molecules, besides the classical actions on bone metabolism, exert several beneficial effects on metabolic homeostasis, heart-cardiovascular, brain, and muscle physiological functions, throughout the interaction with the specific vitamin D receptor (VDR). In particular, VDR agonists powerfully control innate and adaptive immune system with favorable effects on human health. VDR ligands act as immunomodulators that are potent enough to retain anti-inflammatory effects, even though the mechanism underlying those effects is not yet fully elucidated. VDR agonists exert a significant suppression of inflammatory processes switching the immune response from T helper 1 (Th1) to T helper 2 (Th2) dominance and counteracting the self-enhancing inflammatory loop between immune and resident cells, especially by cytokine release impairment. Those molecules are able, indeed, to reduce the release of the interferon (IFN)γ-induced 10 kDa protein IP-10/CXCL10, a powerful chemokine driving Th1-mediated inflammation. Based on their features, VDR ligands show the potentiality to be included in immunosuppressive regimens, aimed to control auto- and alloimmune Th1-driven overreactivity, occurring, for example, in autoimmune disease or graft rejection.