Judith R. Kelsen

Clinical trial: vitamin D3 treatment in Crohn’s disease – a randomized double-blind placebo-controlled study

Aliment Pharmacol Ther 2010; 32: 377–383

Immune tolerance. Group 3 innate lymphoid cells mediate intestinal selection of commensal bacteria-specific CD4⁺ T cells.

Innate lymphoid cells keep gut T cells in check Trillions of bacteria inhabit our guts. So do many types of immune cells, including T cells, which might be expected to attack these bacteria. How, then, do our bodies manage to keep the peace? Working in mice, Hepworth et al. report one such mechanism. A population of immune cells, called innate lymphoid cells, directly killed CD4+ T cells that react to commensal gut microbes. Some of the specifics of this process parallel how the immune system keeps developing self-reactive T cells in check in the thymus. Furthermore, this peacekeeping process may be disrupted in children with inflammatory bowel disease. Science, this issue p. 1031 Innate lymphoid cells delete commensal bacteria–specific CD4+ T cells from the intestine in mice. Inflammatory CD4+ T cell responses to self or commensal bacteria underlie the pathogenesis of autoimmunity and inflammatory bowel disease (IBD), respectively. Although selection of self-specific T cells in the thymus limits responses to mammalian tissue antigens, the mechanisms that control selection of commensal bacteria–specific T cells remain poorly understood. Here, we demonstrate that group 3 innate lymphoid cell (ILC3)–intrinsic expression of major histocompatibility complex class II (MHCII) is regulated similarly to thymic epithelial cells and that MHCII+ ILC3s directly induce cell death of activated commensal bacteria–specific T cells. Further, MHCII on colonic ILC3s was reduced in pediatric IBD patients. Collectively, these results define a selection pathway for commensal bacteria–specific CD4+ T cells in the intestine and suggest that this process is dysregulated in human IBD.

Inflammatory bowel disease: The difference between children and adults

Inflammatory bowel disease (IBD) is a group of diseases that include Crohn’s disease (CD) and ulcerative colitis (UC). Presenting symptoms and therapeutic options are similar in adult and pediatric patients. However, there are significant differences in the 2 populations that require separate approaches to treatment and management of the disease in children. IBD is now being recognized with increased frequency in both adults and in children of all ages. In CD, 25%–30% of patients with CD and 20% of patients with (UC) present before the age of 20. Although the peak age of onset is still in late adolescence, 4% of pediatric IBD are diagnosed in early childhood (less than 5 years of age).1 Children with IBD are at particular risk for extraintestinal manifestations of the disease. These symptoms often have a more damaging impact in pediatric patients and can include growth failure, weight loss, anemia, joint symptoms, and delayed puberty. Therapy itself can adversely impact normal growth and development. Other issues that are unique to the pediatric patient are the lack of controlled clinical trials and the psychological issues that occur in children and adolescents with IBD.

Recurrence rate of clostridium difficile infection in hospitalized pediatric patients with inflammatory bowel disease

Background: The incidence and associated morbidity of Clostridium difficile (CD) infection has been increasing at an alarming rate in North America. Clostridium difficile‐associated diarrhea (CDAD) is the leading cause of nosocomial diarrhea in the USA. Patients with CDAD have longer average hospital admissions and additional hospital costs. Evidence has demonstrated that patients with inflammatory bowel disease (IBD) have a higher incidence of CD in comparison to the general population. The aim of this study was to compare the rate of recurrence of CD in hospitalized pediatric patients with IBD compared to hospitalized controls. The secondary aim was to evaluate whether infection with CD resulted in a more severe disease course of IBD. Methods: This was a nested case control retrospective study of hospitalized pediatric patients. Diagnosis of CD was confirmed with stool Toxin A and B analysis. The following data were obtained from the medical records: demographic information, classification of IBD including location of disease, IBD therapy, and prior surgeries. In addition, prior hospital admissions within 1 year and antibiotic exposure were recorded. The same information was recorded following CD infection. Cases were patients with IBD and CD; two control populations were also studied: patients with CD but without IBD, and patients with IBD but without CD. Results: For aim 1, a total of 111 eligible patients with IBD and CD infection and 77 eligible control patients with CD infection were included. The rate of recurrence of CD in the IBD population was 34% compared to 7.5% in the control population (P < 0.0001). In evaluating the effect of CD infection on IBD disease severity, we compared the 111 IBD patients with CD to a second control population of 127 IBD patients without CD. 57% of IBD‐CD patients were readmitted with an exacerbation of disease within 6 months of infection with CD and 67% required escalation of therapy following CD infection, compared to 30% of IBD patients without CD (P < 0.001). Of the patients with IBD and CD, 44% of the cases were new‐onset IBD, 63% were on immunosuppression therapy, and 33% were on gastric acid suppression prior to infection. In comparing the IBD‐CD and control CD populations, there was no significant difference in antibiotic exposure: 33% of IBD patients and 26% of control patients were on antibiotics (P < 0.2). With regard to prior hospitalization, 10% of patients with IBD were hospitalized in the 30 days prior to infection in comparison to 27% of the control CD patients (P < 0.002). Conclusions: CD infection in patients with IBD results in a higher rate of recurrence and is associated with higher morbidity than the general population. Patients with IBD often required hospitalization and escalation of therapy following infection with CD, suggesting that CD resulted in increased severity of IBD disease. In addition, IBD patients were more likely develop community‐acquired CD, while the control patients developed nosocomial infections, indicating a higher susceptibility to CD infection in patients with IBD. (Inflamm Bowel Dis 2011;)

Transient inhibition of ROR-[gamma]t therapeutically limits intestinal inflammation by reducing TH17 cells and preserving group 3 innate lymphoid cells

RAR-related orphan receptor-γt (ROR-γt) directs differentiation of proinflammatory T helper 17 (TH17) cells and is a potential therapeutic target in chronic autoimmune and inflammatory diseases. However, ROR-γt–dependent group 3 innate lymphoid cells ILC3s provide essential immunity and tissue protection in the intestine, suggesting that targeting ROR-γt could also result in impaired host defense after infection or enhanced tissue damage. Here, we demonstrate that transient chemical inhibition of ROR-γt in mice selectively reduces cytokine production from TH17 but not ILCs in the context of intestinal infection with Citrobacter rodentium, resulting in preserved innate immunity. Temporal deletion of Rorc (encoding ROR-γt) in mature ILCs also did not impair cytokine response in the steady state or during infection. Finally, pharmacologic inhibition of ROR-γt provided therapeutic benefit in mouse models of intestinal inflammation and reduced the frequency of TH17 cells but not ILCs isolated from primary intestinal samples of individuals with inflammatory bowel disease (IBD). Collectively, these results reveal differential requirements for ROR-γt in the maintenance of TH17 cell and ILC3 responses and suggest that transient inhibition of ROR-γt is a safe and effective therapeutic approach during intestinal inflammation.

Life-threatening NLRC4-associated hyperinflammation successfully treated with IL-18 inhibition

NLRC4-inflammasome hyperactivity causes infantile-onset Macrophage Activation Syndrome and enterocolitis with extraordinary serum IL-18 elevation (NLRC4-MAS). Herein, we report a critically ill infant with severe, refractory NLRC4-MAS who showed sustained response to treatment with experimental IL-18 inhibition.

Optimizing methods and dodging pitfalls in microbiome research

Research on the human microbiome has yielded numerous insights into health and disease, but also has resulted in a wealth of experimental artifacts. Here, we present suggestions for optimizing experimental design and avoiding known pitfalls, organized in the typical order in which studies are carried out. We first review best practices in experimental design and introduce common confounders such as age, diet, antibiotic use, pet ownership, longitudinal instability, and microbial sharing during cohousing in animal studies. Typically, samples will need to be stored, so we provide data on best practices for several sample types. We then discuss design and analysis of positive and negative controls, which should always be run with experimental samples. We introduce a convenient set of non-biological DNA sequences that can be useful as positive controls for high-volume analysis. Careful analysis of negative and positive controls is particularly important in studies of samples with low microbial biomass, where contamination can comprise most or all of a sample. Lastly, we summarize approaches to enhancing experimental robustness by careful control of multiple comparisons and to comparing discovery and validation cohorts. We hope the experimental tactics summarized here will help researchers in this exciting field advance their studies efficiently while avoiding errors.

The gut microbiota, environment and diseases of modern society.

The human gut microbiota is a complex community that provides important metabolic functions to the host. Consequently, alterations in the gut microbiota have been associated with the pathogenesis of several human diseases associated with a disturbance in metabolism, particularly those that have been increasing in incidence over the last several decades including obesity, diabetes and atherosclerosis. In this review, we explore how advances in deep DNA sequencing technology have provided us a greater understanding of the factors that influence that composition of the gut microbiota and its possible links to the pathogenesis of these diseases.

A novel enteral nutrition protocol for the treatment of pediatric Crohn's disease.

Background:Enteral nutritional therapy (EN) is an effective modality for inducing and maintaining remission in pediatric patients with Crohn’s disease (CD). The standard protocol for EN provides patients with 100% of their caloric needs for induction of remission. The aim of this study was to determine the efficacy of delivering 80% to 90% of patient’s caloric needs through EN, to induce remission in pediatric patients with CD. This approach allows patients to consume remaining calories from a normal diet. Methods:A retrospective review of charts from 1998 to 2010 was conducted at The Children’s Hospital of Philadelphia. Remission (Pediatric Crohn’s Disease Activity Index <10) and response (decrease in Pediatric Crohn’s Disease Activity Index score of ≥12.5 points) were calculated before and after treatment with EN. Weight z scores and laboratory parameters were evaluated in all participants. Results:Forty-three charts were evaluated. Mean age of participants was 12.8 years (5.1–17.4), 67% were male and 33% female patients. Remission and response were evaluated in a group of 23 participants, with no missing data. There were reductions in erythrocyte sedimentation rate (P < 0.0001) and C-reactive protein (P < 0.02), and increases in albumin (P < 0.03). Mean Pediatric Crohn’s Disease Activity Index score at baseline was 26.9 and was reduced to a score of 10.2 at follow-up (P < 0.0001). Induction of remission was achieved in 65% and response in 87% at a mean follow-up of 2 months (1–4 months). Conclusions:This novel EN protocol seems to be effective for the induction of remission in pediatric patients with CD and contributes to increasing weight and improving laboratory markers. This protocol may result in improved EN acceptance and compliance and will be evaluated prospectively.

Phase I trial of sargramostim in pediatric Crohn's disease

Background: Improving granulocyte function may represent an effective therapy for Crohns disease (CD). We performed a Phase I‐2 trial of sargramostim (SRG) in children with CD. Methods: This was multicenter, open‐label study in 6–16‐year‐old patients with moderate to severely active CD. Patients received either 4 or 6 &mgr;g/kg SRG subcutaneously daily for 8 weeks, with and without concomitant corticosteroids (CS). The primary endpoint was identification of a safe and tolerable dose in children. The secondary endpoint was establishment of the pharmacokinetics (PK). Efficacy, a tertiary endpoint, was measured by the Pediatric CD Activity Index (PCDAI). Response was defined as a decrease from baseline of ≥12.5 points and remission as absolute PCDAI of ≤10. Results: In all, 22 patients were enrolled: 12 and 10 received 4 and 6 mg/kg, respectively; 19 completed the course. Both doses were found to be safe and well tolerated. Mild injection‐site reactions occurred in 90% of patients. Three patients required dose reductions due to elevated absolute neutrophil counts. Following 4 &mgr;g/kg the mean area under the curve (AUC) was 2.64 and 2.80 ngh/mL for the 6–11‐ and 12–16‐year‐old groups, respectively. The mean half‐life (t1/2) was 1.22 and 1.59 hours, respectively. Following 6 &mgr;g/kg, the mean AUC was 5.01 ngh/mL for the 12–16‐year‐old group, a 1.8‐fold increase. A total of 16/18 patients (88%) achieved remission or response. Conclusions: Sargramostim at both 4 and 6 mg/kg was well tolerated. PK analysis suggested dose proportionality unaffected by CS exposure. Remission and response data are encouraging, but further trials are needed to assess efficacy. (Inflamm Bowel Dis 2010)