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

Fecal Supernatants from Patients with Crohn's Disease Induce Inflammatory Alterations in M2 Macrophages and Fibroblasts

Intestinal macrophages and fibroblasts act as microenvironmental sentinels mediating inflammation and disease progression in Crohn's disease (CD). We aimed to establish the effects of fecal supernatants (FSs) from patients with CD on macrophage and fibroblast phenotype and function. FS were obtained by ultracentrifugation, and the metabolites were analyzed. Monocyte-derived M2 macrophages and fibroblasts were conditioned with FS, and secreted proteins, surface proteins and gene expression were analyzed. M2 macrophage efferocytosis was evaluated. Patients with CD (n = 15) had a skewed fecal metabolite profile compared to healthy subjects (HS, n = 10). FS from CD patients (CD-FS) induced an anti-inflammatory response in M2 macrophages with higher expression of IL-10, IL1RA and CD206 as compared to healthy FS (HS-FS) while the efferocytotic capacity was unaltered. CD-FS did not affect extracellular matrix production from fibroblasts, but increased expression of the pro-inflammatory proteins IL-6 and MCP-1. Conditioned media from M2 macrophages treated with CD-FS modulated gene expression in fibroblasts for TGFβ superfamily members and reduced IL-4 expression compared to HS-FS. We show that M2 macrophages and fibroblasts react abnormally to the fecal microenvironment of CD patients, resulting in altered protein expression related to inflammation but not fibrosis. This implies that the gut microbiota and its metabolites have an important role in the generation and/or perpetuation of inflammation in CD.

Characteristics of Graft-Versus-Host Disease (GvHD) After Post-Transplantation Cyclophosphamide Versus Conventional GvHD Prophylaxis

Post-transplantation cyclophosphamide (PTCy) has been shown to effectively control graft-versus-host disease (GvHD) in haploidentical (Haplo) transplantations. In this retrospective registry study, we compared GvHD organ distribution, severity, and outcomes in patients with GvHD occurring after Haplo transplantation with PTCy GvHD prophylaxis (Haplo/PTCy) versus HLA-matched unrelated donor transplantation with conventional prophylaxis (MUD/conventional). We evaluated 2 cohorts: patients with grade 2 to 4 acute GvHD (aGvHD) including 264 and 1163 recipients of Haplo and MUD transplants; and patients with any chronic GvHD (cGvHD) including 206 and 1018 recipients of Haplo and MUD transplants, respectively. In comparison with MUD/conventional transplantation ± antithymocyte globulin (ATG), grade 3-4 aGvHD (28% versus 39%, P = .001), stage 3-4 lower gastrointestinal (GI) tract aGvHD (14% versus 21%, P = .01), and chronic GI GvHD (21% versus 31%, P = .006) were less common after Haplo/PTCy transplantation. In patients with grade 2-4 aGvHD, cGvHD rate after Haplo/PTCY was also lower (hazard ratio [HR] = .4, P < .001) in comparison with MUD/conventional transplantation without ATG in the nonmyeloablative conditioning setting. Irrespective of the use of ATG, non-relapse mortality rate was lower (HR = .6, P = .01) after Haplo/PTCy transplantation, except for transplants that were from a female donor into a male recipient. In patients with cGvHD, irrespective of ATG use, Haplo/PTCy transplantation had lower non-relapse mortality rates (HR = .6, P = .04). Mortality rate was higher (HR = 1.6, P = .03) during, but not after (HR = .9, P = .6) the first 6 months after cGvHD diagnosis. Our results suggest that PTCy-based GvHD prophylaxis mitigates the development of GI GvHD and may translate into lower GvHD-related non-relapse mortality rate.

The Role of Vitamin D in Immune System and Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is a nonspecific inflammatory disease that includes ulcerative colitis (UC) and Crohn's disease (CD). The pathogenesis of IBD is not fully understood but is most reported associated with immune dysregulation, dysbacteriosis, genetic susceptibility, and environmental risk factors. Vitamin D is an essential nutrient for the human body, and it not only regulates bone metabolism but also the immune system, the intestinal microbiota and barrier. Vitamin D insufficiency is common in IBD patients, and the abnormal low levels of vitamin D are highly correlated with disease activity, treatment response, and risk of relapse of IBD. Accumulating evidence supports the protective role of vitamin D in IBD through regulating the adaptive and innate immunity, maintaining the intestinal barrier and balancing the gut microbiota. This report aims to provide a broad overview of the role vitamin D in the immune system, especially in the pathogenesis and treatment of IBD, and its possible role in predicting relapse.

Allergic diseases in infancy II-oral tolerance and its failure

Objective

The early window of opportunity describes the timeframe after birth in which essential interactions of the immune system and the newly developing microbiota take place. The infant's immune system has to be reactive to invading pathogens and at the same time tolerant to dietary antigens. If the mechanisms of defense and tolerance induction are disturbed, the risk of infections or allergies is increased.

Method

This is a narrative review of the recently published information on the topic of neonatal intestinal development and mechanisms of oral tolerance and summarizes the discussions and conclusions from the 8^th Human Milk Workshop.

Results

The early postnatal period sets the stage for life-long host-microbiome interaction. In this early phase, specific developmental mechanisms ensure physiologic interaction with the developing microbiota. Innate and adaptive immune cells interact in a concerted way to induce and uphold oral tolerance. Factors in human milk can support this induction of tolerance and simultaneously protect against infection and allergy development.

Conclusion

Understanding the developmental mechanisms in this early phase of immune system development is the first step to develop strategies of pathology prevention. As human milk protects the infant from infections, and aids to develop a tolerogenic immune response, further knowledge on the protective factors in human milk and their effect on the immune system is required.

Decrease in Mucosal IL17A, IFNγ and IL10 Expressions in Active Crohn's Disease Patients Treated with High-Dose Vitamin Alone or Combined with Infliximab

Background: Vitamin D treatment may reduce Crohn’s disease (CD) activity by modulating the mucosal immune function. We investigated if high-dose vitamin D +/− infliximab modulated the mucosal cytokine expression in active CD. Methods: Forty CD patients were randomized into: infliximab + vitamin D; infliximab + placebo-vitamin D; placebo-infliximab + vitamin D or placebo-infliximab + placebo-vitamin D. Infliximab (5 mg/kg) and placebo-infliximab were administered at weeks 0, 2 and 6. Oral vitamin D was administered as bolus 200,000 international units (IU) per week 0 followed by 20,000 IU/day for 7 weeks or placebo. Endoscopy with biopsies was performed at weeks 0 and 7 where endoscopic activity was measured and mucosal mRNA cytokine expression was examined. C-reactive protein (CRP), fecal calprotectin and Harvey-Bradshaw Index (HBI) were measured at weeks 0, 2 and 6. Results: High-dose vitamin D treatment alone and combined with infliximab decreased the IL17A, IFNγ and IL10 expression. High-dose vitamin D alone did not significantly decrease the disease activity, CRP or calprotectin. Combined infliximab and vitamin D treatment was not clinically significantly superior to monotherapy with infliximab. Conclusions: High-dose vitamin D as monotherapy and combined with infliximab decreases IL17A, IFNγ and IL-10 expression in mucosa within treatment groups. This did not induce a statistically significant decreased disease activity. EudraCT no.2013-000971-34.

Immunoregulatory effects and therapeutic potential of vitamin D in multiple sclerosis

Initially recognised as an important factor for bone health, vitamin D is now known to have a range of effects on the immune system. Vitamin D deficiency is associated with an increased risk of multiple sclerosis (MS), a chronic immune-mediated demyelinating disease of the CNS. In this review, we explore the links between vitamin D deficiency, MS risk, and disease activity. We also discuss the known immune effects of vitamin D supplementation and the relevance of these observations to the immunopathology of MS. Finally, we review the existing evidence for vitamin D supplementation as an MS therapy, highlighting several recent clinical studies and trials.

Elevated Levels of 1,25-Dihydroxyvitamin D in Plasma as a Missing Risk Factor for Celiac Disease

The prevalence of celiac disease (CD) has increased significantly in some developed countries in recent decades. Potential risk factors that have been considered in the literature do not appear to provide a convincing explanation for this increase. This has led some researchers to hypothesize that there is a "missing environmental factor" that increases the risk of CD. Based on evidence from the literature, the author proposes that elevation in plasma levels of 1,25-dihydroxyvitamin D [1,25(OH)₂D] is a missing risk factor for CD, and relatedly that significant oral vitamin D exposure is a "missing environmental factor" for CD. First, elevated plasma levels of 1,25(OH)₂D are common in CD, especially in the newly diagnosed. Second, nine distinct conditions that increase plasma levels of 1,25(OH)₂D are either associated with CD or have indications of such an association in the literature. Third, a retrospective study shows that sustained oral vitamin D supplementation in infancy is associated with increased CD risk, and other studies on comorbid conditions support this association. Fourth, large doses of oral vitamin D upregulate many of the same cytokines, chemokines, and toll-like receptors that are upregulated in CD. Fifth, epidemiological evidence, such as the timing of the inception of a CD "epidemic" in Sweden, the increased prevalence of CD in Finland and the United States in recent decades, the unusually low prevalence of CD in Germany, and the differential in prevalence between Finnish Karelians and Russian Karelians, may all be explained by oral vitamin D exposure increasing CD risk. The same is true of some seemingly contradictory results in the literature on the effects of breastfeeding on CD risk. If future research validates this hypothesis, adjustments to oral vitamin D consumption among those who have genetic susceptibility may decrease the risk of CD in these individuals.

Role of dendritic cells in peanut allergy

INTRODUCTION

The prevalence of peanut allergy (PA) has increased, affecting approximately 1.1% of children in Western countries. PA causes life-threatening anaphylaxis and frequently persists for life. There are no standardized curative therapies for PA, and avoidance of peanuts remains the main therapeutic option. A better understanding of the pathogenesis of PA is essential to identify new treatment strategies. Intestinal dendritic cells (DCs) are essential in the induction and maintenance of food tolerance because they present dietary allergens to T cells, thereby directing subsequent immune responses. Areas covered: In this review, we discuss the factors related to the acquisition of oral tolerance to peanut proteins. We focus on intestinal DC-related aspects, including the latest advances in the biology of intestinal DC subtypes, effect of tolerance-inducing factors on DCs, effect of dietary components on oral tolerance, and role of DCs in peanut sensitization. Expert commentary: Given the increasing prevalence of PA, difficulty of avoiding peanut products, and the potentially serious accidental reactions, the development of novel therapies for PA is needed. The ability of DCs to trigger tolerance or immunity makes them an interesting target for new treatment strategies against PA.