Deanna D. Nguyen

Interleukin-10 receptor signaling in innate immune cells regulates mucosal immune tolerance and anti-inflammatory macrophage function

Intact interleukin-10 receptor (IL-10R) signaling on effector and T regulatory (Treg) cells are each independently required to maintain immune tolerance. Here we show that IL-10 sensing by innate immune cells, independent of its effects on T cells, was critical for regulating mucosal homeostasis. Following wild-type (WT) CD4(+) T cell transfer, Rag2(-/-)Il10rb(-/-) mice developed severe colitis in association with profound defects in generation and function of Treg cells. Moreover, loss of IL-10R signaling impaired the generation and function of anti-inflammatory intestinal and bone-marrow-derived macrophages and their ability to secrete IL-10. Importantly, transfer of WT but not Il10rb(-/-) anti-inflammatory macrophages ameliorated colitis induction by WT CD4(+) T cells in Rag2(-/-)Il10rb(-/-) mice. Similar alterations in the generation and function of anti-inflammatory macrophages were observed in IL-10R-deficient patients with very early onset inflammatory bowel disease. Collectively, our studies define innate immune IL-10R signaling as a key factor regulating mucosal immune homeostasis in mice and humans.

The Wiskott-Aldrich syndrome protein is required for the function of CD4+CD25+Foxp3+ regulatory T cells

The Wiskott-Aldrich syndrome, a primary human immunodeficiency, results from defective expression of the hematopoietic-specific cytoskeletal regulator Wiskott-Aldrich syndrome protein (WASP). Because CD4+CD25+Foxp3+ naturally occurring regulatory T (nTreg) cells control autoimmunity, we asked whether colitis in WASP knockout (WKO) mice is associated with aberrant development/function of nTreg cells. We show that WKO mice have decreased numbers of CD4+CD25+Foxp3+ nTreg cells in both the thymus and peripheral lymphoid organs. Moreover, we demonstrate that WKO nTreg cells are markedly defective in both their ability to ameliorate the colitis induced by the transfer of CD45RBhi T cells and in functional suppression assays in vitro. Compared with wild-type (WT) nTreg cells, WKO nTreg cells show significantly impaired homing to both mucosal (mesenteric) and peripheral sites upon adoptive transfer into WT recipient mice. Suppression defects may be independent of antigen receptor–mediated actin rearrangement because both WT and WKO nTreg cells remodeled their actin cytoskeleton inefficiently upon T cell receptor stimulation. Preincubation of WKO nTreg cells with exogenous interleukin (IL)-2, combined with antigen receptor–mediated activation, substantially rescues the suppression defects. WKO nTreg cells are also defective in the secretion of the immunomodulatory cytokine IL-10. Overall, our data reveal a critical role for WASP in nTreg cell function and implicate nTreg cell dysfunction in the autoimmunity associated with WASP deficiency.

Efficacy of Vedolizumab as Induction Therapy in Refractory IBD Patients: A Multicenter Cohort.

Background:Vedolizumab (VDZ) demonstrated efficacy in Crohns disease (CD) and ulcerative colitis (UC) in the GEMINI trials. Our aim was to evaluate the efficacy of VDZ at week 14 in inflammatory bowel disease in a multicenter cohort of patients. Methods:Patients at Massachusetts General Hospital and Brigham and Womens Hospital were considered for inclusion. VDZ (300 mg) was administered at weeks 0, 2, 6, and 14. Efficacy was assessed using the Harvey–Bradshaw index for CD, the simple clinical colitis activity index for UC and physician assessment, along with C-reactive protein and decrease of corticosteroid therapy. Clinical response was defined as decrease in Harvey–Bradshaw index ≥3 and simple clinical colitis activity index ≥3 and remission as Harvey–Bradshaw index ⩽4, simple clinical colitis activity index ⩽2 and physician assessment of response and remission. Results:Our study included 172 patients (107 CD, 59 UC, 6 inflammatory bowel disease-unclassified, men 48.3%, mean age 40 years and disease duration 14 years). Fourteen patients had ostomy and 9 ileoanal pouch, and only 35.5% fulfilled eligibility for the GEMINI trials. Previous treatment failures with ≥ 2 anti-TNFs occurred in 70.9%, one-third were on an immunomodulator and 46% systemic steroids at baseline. In CD, 48.9% and 23.9% and in UC, 53.9% and 29.3% had clinical response and clinical remission at week 14, respectively. Adverse events occurred in 10.5%. Conclusions:VDZ is safe and well tolerated in refractory inflammatory bowel disease patients in a clinical practice with efficacy in UC and CD with responses similar to what was seen in clinical trials.

Older age is associated with higher rate of discontinuation of anti‐TNF therapy in patients with inflammatory bowel disease

Background:In increasingly aging populations, awareness of outcomes of older patients treated with biologics is becoming more important. However, few studies to date have investigated the safety and durability of anti-tumor necrosis factor (TNF) therapy in this subgroup. Methods:This was a retrospective single-center study with cases comprising all IBD patients who began anti-TNF treatment at age >60 years. Cases of Crohns disease (CD) and ulcerative colitis (UC) were identified from medical record review. Our controls consisted of patients younger than age 60 years on anti-TNF treatment and patients >60 years on treatment with immunomodulators. Kaplan–Meier survival estimates were used to calculate the probability of remaining on anti-TNF therapy. Results:We identified a total of 54 IBD patients who initiated anti-TNF therapy over the age of 60 years (mean 73, range 61–97 years). Among these, a total of 38 patients (70%) discontinued anti-TNF therapy after a mean of 24.1 months. At 12 months after initiation, 75% of patients older than age 60 years were still on anti-TNF agents compared to 93% among younger users and 82% among older AZA users (P < 0.05). Compared to older AZA users, older anti-TNF users remained more likely to require early therapy cessation (hazard ratio 2.21, 95% confidence interval 1.29–3.78). Conclusions:The IBD population older than age 60 at the time of initiation of anti-TNF therapy is at higher risk for discontinuation of therapy. They may also be particularly vulnerable to infectious complications requiring hospitalization, suggesting the need for careful monitoring during therapy.

MyD88-dependent TLR1/2 signals educate dendritic cells with gut-specific imprinting properties

Gut-associated dendritic cells (DC) synthesize all-trans retinoic acid, which is required for inducing gut-tropic lymphocytes. Gut-associated DC from MyD88−/− mice, which lack most TLR signals, expressed low levels of retinal dehydrogenases (critical enzymes for all-trans retinoic acid biosynthesis) and were significantly impaired in their ability to induce gut-homing T cells. Pretreatment of extraintestinal DC with a TLR1/2 agonist was sufficient to induce retinal dehydrogenases and to confer these DC with the capacity to induce gut-homing lymphocytes via a mechanism dependent on MyD88 and JNK/MAPK. Moreover, gut-associated DC from TLR2−/− mice, or from mice in which JNK was pharmacologically blocked, were impaired in their education to imprint gut-homing T cells, which correlated with a decreased induction of gut-tropic T cells in TLR2−/− mice upon immunization. Thus, MyD88-dependent TLR2 signals are necessary and sufficient to educate DC with gut-specific imprinting properties and contribute in vivo to the generation of gut-tropic T cells.

Intestinal Alkaline Phosphatase Has Beneficial Effects in Mouse Models of Chronic Colitis

Background: The brush border enzyme intestinal alkaline phosphatase (IAP) functions as a gut mucosal defense factor and is protective against dextran sulfate sodium (DSS)‐induced acute injury in rats. The present study evaluated the potential therapeutic role for orally administered calf IAP (cIAP) in two independent mouse models of chronic colitis: 1) DSS‐induced chronic colitis, and 2) chronic spontaneous colitis in Wiskott‐Aldrich Syndrome protein (WASP)‐deficient (knockout) mice that is accelerated by irradiation. Methods: The wildtype (WT) and IAP knockout (IAP‐KO) mice received four cycles of 2% DSS ad libitum for 7 days. Each cycle was followed by a 7‐day DSS‐free interval during which mice received either cIAP or vehicle in the drinking water. The WASP‐KO mice received either vehicle or cIAP for 6 weeks beginning on the day of irradiation. Results: Microscopic colitis scores of DSS‐treated IAP‐KO mice were higher than DSS‐treated WT mice (52 ± 3.8 versus 28.8 ± 6.6, respectively, P < 0.0001). cIAP treatment attenuated the disease in both groups (KO = 30.7 ± 6.01, WT = 18.7 ± 5.0, P < 0.05). In irradiated WASP‐KO mice cIAP also attenuated colitis compared to control groups (3.3 ± 0.52 versus 6.2 ± 0.34, respectively, P < 0.001). Tissue myeloperoxidase activity and proinflammatory cytokines were significantly decreased by cIAP treatment. Conclusions: Endogenous IAP appears to play a role in protecting the host against chronic colitis. Orally administered cIAP exerts a protective effect in two independent mouse models of chronic colitis and may represent a novel therapy for human IBD. (Inflamm Bowel Dis 2011)

Differential Effect of Genetic Burden on Disease Phenotypes in Crohn's Disease and Ulcerative Colitis: Analysis of a North American Cohort

OBJECTIVES:Crohns disease (CD) and ulcerative colitis (UC) are chronic immunologically mediated diseases with a progressive relapsing remitting course. There is considerable heterogeneity in disease course and accurate prediction of natural history has been challenging. The phenotypic implication of increasing genetic predisposition to CD or UC is unknown.METHODS:The data source for our study was a prospective cohort of CD and UC patients recruited from a tertiary referral center. All patients underwent genotyping on the Illumina Immunochip. A genetic risk score (GRS) incorporating strength of association (log odds ratio) and allele dose for each of the 163 inflammatory bowel disease (IBD) risk loci was calculated and phenotypic associations examined across GRS quartiles.RESULTS:Our study cohort included 1,105 patients (697 CD, 408 UC). Increasing genetic burden was associated with earlier age of diagnosis of CD (Ptrend=0.008). Patients in the highest GRS quartile were likely to develop disease 5 years earlier than those in the lowest quartile. Increasing genetic burden was also associated with ileal involvement in CD (Ptrend <0.0001). The effect of genetic burden was independent of the NOD2 locus and was stronger among those with no NOD2 variants, and in never smokers. UC patients with an involved first-degree relative had a higher genetic burden, but GRS was not associated with disease phenotype in UC.CONCLUSIONS:Increasing genetic burden is associated with early age of diagnosis in CD, but not UC. The expanded panel of IBD risk loci explains only a fraction of variance of disease phenotype, suggesting limited clinical utility of genetics in predicting natural history.

Toll-like receptor 4-mediated regulation of spontaneous Helicobacter-dependent colitis in IL-10 deficient mice

BACKGROUND & AIMS The commensal microbiota is believed to have an important role in regulating immune responsiveness and preventing intestinal inflammation. Intestinal microbes produce signals that regulate inflammation via Toll-like receptor (TLR) signaling, but the mechanisms of this process are poorly understood. We investigated the role of the anti-inflammatory cytokine interleukin (IL)-10 in this signaling pathway using a mouse model of colitis. METHODS Clinical, histopathologic, and functional parameters of intestinal inflammation were evaluated in TLR4(-/-), IL-10(-/-), and TLR4(-/-) x IL-10(-/-) mice that were free of specific pathogens and in TLR4(-/-) x IL-10(-/-) mice following eradication and reintroduction of Helicobacter hepaticus. Regulatory T-cell (Treg) function was evaluated by crossing each of the lines with transgenic mice that express green fluorescent protein under control of the endogenous regulatory elements of Foxp3. Apoptotic cells in the colonic lamina propria were detected by a TUNEL assay. RESULTS TLR4-mediated signals have 2 interrelated roles in promoting inflammation in TLR4(-/-) x IL-10(-/-) mice. In the absence of TLR4-mediated signals, secretion of proinflammatory and immunoregulatory cytokines is dysregulated. Tregs (Foxp3(+)) that secrete interferon-gamma and IL-17 accumulate in the colonic lamina propria of TLR4(-/-) x IL-10(-/-) mice and do not prevent inflammation. Aberrant control of epithelial cell turnover results in the persistence of antigen-presenting cells that contain apoptotic epithelial fragments in the colonic lamina propria of Helicobacter-infected TLR4(-/-) mice. CONCLUSIONS In mice that lack both IL-10- and TLR4-mediated signals, aberrant regulatory T-cell function and dysregulated control of epithelial homeostasis combine to exacerbate intestinal inflammation.

Pretreatment 25-Hydroxyvitamin D Levels and Durability of Anti–Tumor Necrosis Factor–α Therapy in Inflammatory Bowel Diseases

INTRODUCTION Emerging evidence supports an immunologic role for 25-hydroxyvitamin D (25(OH)D) in inflammatory bowel disease (IBD). Here we examined if pretreatment vitamin D status influences durability of anti-tumor necrosis factor (TNF)-α therapy in patients with Crohns disease (CD) or ulcerative colitis (UC). METHODS All IBD patients who had plasma 25(OH)D level checked <3 months prior to initiating anti-TNF-α therapy were included in this retrospective single-center cohort study. Our main predictor variable was insufficient plasma 25(OH)D (<30 ng/mL). Cox proportional hazards model adjusting for potential confounders was used to identify the independent effect of pretreatment vitamin D on biologic treatment cessation. RESULTS Our study included 101 IBD patients (74 CD; median disease duration 9 years). The median index 25(OH)D level was 27 ng/mL (interquartile range, 20-33 ng/mL). One-third of the patients had prior exposure to anti-TNF-α therapy. On multivariate analysis, patients with insufficient vitamin D demonstrated earlier cessation of anti-TNF-α therapy (hazard ratio [HR], 2.13; 95% confidence interval [CI], 1.03-4.39; P = .04). This effect was significant in patients who stopped treatment for loss of response (HR, 3.49; 95% CI, 1.34-9.09) and stronger for CD (HR, 2.38; 95% CI, 0.95-5.99) than UC (P = NS). CONCLUSIONS Our findings suggest that vitamin D levels may influence durability of anti-TNF-α induction and maintenance therapy. Larger cohort studies and clinical trials of supplemental vitamin D use with disease activity as an end point may be warranted.

Genetic risk factors for Clostridium difficile infection in ulcerative colitis.

Patients with inflammatory bowel disease (IBD) are at higher risk for Clostridium difficile infection (CDI). Disruption of gut microbiome and interaction with the intestinal immune system are essential mechanisms for pathogenesis of both CDI and IBD. Whether genetic polymorphisms associated with susceptibility to IBD are also associated with risk of CDI is unknown.