Ileal Paneth Cell Phenotype is a Cellular Biomarker for Pouch Complications in Ulcerative Colitis.

BACKGROUND & AIMS: Biomarkers that integrate genetic and environmental factors and predict outcome in complex immune diseases such as inflammatory bowel disease (IBD; including Crohn's disease [CD] and ulcerative colitis [UC]) are needed. We showed that morphologic patterns of ileal Paneth cells (Paneth cell phenotype [PCP]; a surrogate for PC function) is one such cellular biomarker for CD. Given the shared features between CD and UC, we hypothesized that PCP is also associated with molecular/genetic features and outcome in UC. Because PC density is highest in the ileum, we further hypothesized that PCP predicts outcome in UC subjects who underwent total colectomy and ileal pouch-anal anastomosis (IPAA). METHODS: Uninflamed ileal resection margins from UC subjects with colectomy and IPAA were used for PCP and transcriptomic analyses. PCP was defined using defensin 5 immunofluorescence. Genotyping was performed using Immunochip. UC transcriptomic and genotype associations of PCP were incorporated with data from CD subjects to identify common IBD-related pathways and genes that regulate PCP. RESULTS: The prevalence of abnormal ileal PCP was 27%, comparable to that seen in CD. Combined analysis of UC and CD subjects showed that abnormal PCP was associated with transcriptomic pathways of secretory granule maturation and polymorphisms in innate immunity genes. Abnormal ileal PCP at the time of colectomy was also associated with pouch complications including de novo CD in the pouch and time to first episode of pouchitis. CONCLUSIONS: Ileal PCP is biologically and clinically relevant in UC and can be used as a biomarker in IBD.

Western diet reduces small intestinal intraepithelial lymphocytes via FXR-Interferon pathway.

The prevalence of obesity in the United States has continued to increase over the past several decades. Understanding how diet-induced obesity modulates mucosal immunity is of clinical relevance. We previously showed that consumption of a high fat, high sugar "Western" diet (WD) reduces the density and function of small intestinal Paneth cells, a small intestinal epithelial cell type with innate immune function. We hypothesized that obesity could also result in repressed gut adaptive immunity. Using small intestinal intraepithelial lymphocytes (IEL) as a readout, we found that in non-inflammatory bowel disease (IBD) subjects, high body mass index correlated with reduced IEL density. We recapitulated this in wild type (WT) mice fed with WD. A 4-week WD consumption was able to reduce IEL but not splenic, blood, or bone marrow lymphocytes, and the effect was reversible after another 2 weeks of standard diet (SD) washout. Importantly, WD-associated IEL reduction was not dependent on the presence of gut microbiota, as WD-fed germ-free mice also showed IEL reduction. We further found that WD-mediated Farnesoid X Receptor (FXR) activation in the gut triggered IEL reduction, and this was partially mediated by intestinal phagocytes. Activated FXR signaling stimulated phagocytes to secrete type I IFN, and inhibition of either FXR or type I IFN signaling within the phagocytes prevented WD-mediated IEL loss. Therefore, WD consumption represses both innate and adaptive immunity in the gut. These findings have significant clinical implications in the understanding of how diet modulates mucosal immunity.

Diet-omics in the Study of Urban and Rural Crohn disease Evolution (SOURCE) cohort.

Crohn disease (CD) burden has increased with globalization/urbanization, and the rapid rise is attributed to environmental changes rather than genetic drift. The Study Of Urban and Rural CD Evolution (SOURCE, n = 380) has considered diet-omics domains simultaneously to detect complex interactions and identify potential beneficial and pathogenic factors linked with rural-urban transition and CD. We characterize exposures, diet, ileal transcriptomics, metabolomics, and microbiome in newly diagnosed CD patients and controls in rural and urban China and Israel. We show that time spent by rural residents in urban environments is linked with changes in gut microbial composition and metabolomics, which mirror those seen in CD. Ileal transcriptomics highlights personal metabolic and immune gene expression modules, that are directly linked to potential protective dietary exposures (coffee, manganese, vitamin D), fecal metabolites, and the microbiome. Bacteria-associated metabolites are primarily linked with host immune modules, whereas diet-linked metabolites are associated with host epithelial metabolic functions.

Noninvasive Markers of Inflammation and Protein Loss Augment Diagnosis of Pediatric Celiac Disease.

INTRODUCTION: Circulating tissue transglutaminase immunoglobulin A concentration is a sensitive and specific indicator of celiac disease, but discrepancies between serologic and histologic findings occur. We hypothesized that fecal markers of inflammation and protein loss would be greater in patients with untreated celiac disease than in healthy controls. Our study aims to evaluate multiple fecal and plasma markers in celiac disease and correlate these findings with serologic and histologic findings as noninvasive means of evaluating disease activity. METHODS: Participants with positive celiac serologies and controls with negative celiac serologies were prospectively enrolled before upper endoscopy. Blood, stool, and duodenal biopsies were collected. Concentrations of fecal lipocalin-2, calprotectin, and alpha-1-antitrypsin and plasma lipocalin-2 were determined. Biopsies underwent modified Marsh scoring. Significance was tested between cases and controls, modified Marsh score and tissue transglutaminase immunoglobulin A concentration. RESULTS: Lipocalin-2 was significantly elevated in the stool ( P = 0.006) but not the plasma of participants with positive celiac serologies. There was no significant difference in fecal calprotectin or alpha-1 antitrypsin between participants with positive celiac serologies and controls. Fecal alpha-1 antitrypsin >100 mg/dL was specific, but not sensitive for biopsy-proven celiac disease. DISCUSSION: Lipocalin-2 is elevated in the stool but not the plasma of patients with celiac disease suggesting a role of local inflammatory response. Calprotectin was not a useful marker in the diagnosis of celiac disease. While random fecal alpha-1 antitrypsin was not significantly elevated in cases compared with controls, an elevation of greater than 100 mg/dL was 90% specific for biopsy-proven celiac disease.

NAD+ precursors and bile acid sequestration treat preclinical refractory environmental enteric dysfunction.

Environmental enteric dysfunction (EED) is a diffuse small bowel disorder associated with poor growth, inadequate responses to oral vaccines, and nutrient malabsorption in millions of children worldwide. We identify loss of the small intestinal Paneth and goblet cells that are critical for innate immunity, reduced villous height, increased bile acids, and dysregulated nicotinamide adenine dinucleotide (NAD+) synthesis signaling as potential mechanisms underlying EED and which also correlated with diminished length-for-age z score. Isocaloric low-protein diet (LPD) consumption in mice recapitulated EED histopathology and transcriptomic changes in a microbiota-independent manner, as well as increases in serum and fecal bile acids. Children with refractory EED harbor single-nucleotide polymorphisms in key enzymes involved in NAD+ synthesis. In mice, deletion of Nampt, the gene encoding the rate-limiting enzyme in the NAD+ salvage pathway, from intestinal epithelium also reduced Paneth cell function, a deficiency that was further aggravated by LPD. Separate supplementation with NAD+ precursors or bile acid sequestrant partially restored LPD-associated Paneth cell defects and, when combined, fully restored all histopathology defects in LPD-fed mice. Therapeutic regimens that increase protein and NAD+ contents while reducing excessive bile acids may benefit children with refractory EED.

HOIL1 Regulates Group 3 Innate Lymphoid Cells in the Colon and Protects against Systemic Dissemination, Colonic Ulceration, and Lethality from Citrobacter rodentium Infection.

Heme-oxidized IRP2 ubiquitin ligase-1 (HOIL1)-deficient patients experience chronic intestinal inflammation and diarrhea as well as increased susceptibility to bacterial infections. HOIL1 is a component of the linear ubiquitin chain assembly complex that regulates immune signaling pathways, including NF-κB-activating pathways. We have shown previously that HOIL1 is essential for survival following Citrobacter rodentium gastrointestinal infection of mice, but the mechanism of protection by HOIL1 was not examined. C. rodentium is an important murine model for human attaching and effacing pathogens, enteropathogenic and enterohemorrhagic Escherichia coli that cause diarrhea and foodborne illnesses and lead to severe disease in children and immunocompromised individuals. In this study, we found that C. rodentium infection resulted in severe colitis and dissemination of C. rodentium to systemic organs in HOIL1-deficient mice. HOIL1 was important in the innate immune response to limit early replication and dissemination of C. rodentium. Using bone marrow chimeras and cell type-specific knockout mice, we found that HOIL1 functioned in radiation-resistant cells and partly in radiation-sensitive cells and in myeloid cells to limit disease, but it was dispensable in intestinal epithelial cells. HOIL1 deficiency significantly impaired the expansion of group 3 innate lymphoid cells and their production of IL-22 during C. rodentium infection. Understanding the role HOIL1 plays in type 3 inflammation and in limiting the pathogenesis of attaching and effacing lesion-forming bacteria will provide further insight into the innate immune response to gastrointestinal pathogens and inflammatory disorders.

A type 2 immune circuit in the stomach controls mammalian adaptation to dietary chitin.

Dietary fiber improves metabolic health, but host-encoded mechanisms for digesting fibrous polysaccharides are unclear. In this work, we describe a mammalian adaptation to dietary chitin that is coordinated by gastric innate immune activation and acidic mammalian chitinase (AMCase). Chitin consumption causes gastric distension and cytokine production by stomach tuft cells and group 2 innate lymphoid cells (ILC2s) in mice, which drives the expansion of AMCase-expressing zymogenic chief cells that facilitate chitin digestion. Although chitin influences gut microbial composition, ILC2-mediated tissue adaptation and gastrointestinal responses are preserved in germ-free mice. In the absence of AMCase, sustained chitin intake leads to heightened basal type 2 immunity, reduced adiposity, and resistance to obesity. These data define an endogenous metabolic circuit that enables nutrient extraction from an insoluble dietary constituent by enhancing digestive function.

Genetic variation in environmental enteropathy and stunting in Zambian children: A pilot genome wide association study using the H3Africa chip.

PURPOSE: Stunting is known to be heavily influenced by environmental factors, so the genetic contribution has received little attention. Here we report an exploration of genetic influences in stunted Zambian children with environmental enteropathy. METHOD: Children with stunting (LAZ < -2) were enrolled and given nutritional therapy. Those that were non-responsive to therapy were designated as cases, and children with good growth (LAZ > -1) from the same community as controls. Blood and stool samples were taken to measure biomarkers of intestinal inflammation, epithelial damage, and microbial translocation. Single nucleotide polymorphism array genotyping was carried out on saliva samples using the H3Africa consortium array. RESULTS: Genome wide associations were analysed in 117 cases and 41 controls. While no significant associations with stunting were observed at P<5x10-8, likely due to the small sample size, interesting associations were observed at lower thresholds. SNPs associated with stunting were in genomic regions known to modulate neuronal differentiation and fatty acid biosynthesis. SNPs associated with increased microbial translocation were associated with non-integrin membrane ECM interactions, tight junctions, hemostasis, and G-alpha signalling events. SNPs associated with increased inflammation were associated with, ECM interactions, purine metabolism, axon guidance, and cell motility. SNPs negatively associated with inflammation overlapped genes involved in semaphoring interactions. We explored the existing coeliac disease risk HLA genotypes and found present: DQ2.5 (7.5%), DQ8 (3.5%) and DQ2.2 (3.8%); however, no children were positive for coeliac antibodies. We detected HLA-DRB:1301 and HLA-C:1802 with high odds ratios and P<0.05 in stunted children compared to controls. CONCLUSION: Genetic variations associated with stunting and the enteropathy underlying it, include variants associated with multiple pathways relating to gene expression, glycosylation, nerve signalling, and sensing of the nutritional and microbiological milieu.

Infection and inflammation stimulate expansion of a CD74+ Paneth cell subset to regulate disease progression.

Paneth cells (PCs), a specialized secretory cell type in the small intestine, are increasingly recognized as having an essential role in host responses to microbiome and environmental stresses. Whether and how commensal and pathogenic microbes modify PC composition to modulate inflammation remain unclear. Using newly developed PC-reporter mice under conventional and gnotobiotic conditions, we determined PC transcriptomic heterogeneity in response to commensal and invasive microbes at single cell level. Infection expands the pool of CD74+ PCs, whose number correlates with auto or allogeneic inflammatory disease progressions in mice. Similar correlation was found in human inflammatory disease tissues. Infection-stimulated cytokines increase production of reactive oxygen species (ROS) and expression of a PC-specific mucosal pentraxin (Mptx2) in activated PCs. A PC-specific ablation of MyD88 reduced CD74+ PC population, thus ameliorating pathogen-induced systemic disease. A similar phenotype was also observed in mice lacking Mptx2. Thus, infection stimulates expansion of a PC subset that influences disease progression.

Non-Invasive markers of inflammation and protein loss augment diagnosis of celiac disease.

Background: Circulating tissue transglutaminase IgA (TTG IgA) concentrations are sensitive and specific indicators of celiac disease, but discrepancies between serologic and histologic findings still occur. We hypothesized that fecal markers of inflammation and protein loss would be greater in patients with untreated celiac disease than in healthy controls. Our study aims to evaluate multiple fecal and plasma markers in celiac disease and correlate these findings with serologic and histologic findings as non-invasive means of evaluating disease activity. Methods: Participants with positive celiac serologies and controls with negative celiac serologies were enrolled at the time of upper endoscopy. Blood, stool and duodenal biopsies were collected. Concentrations of fecal lipocalin-2, calprotectin and alpha-1-antitrypsin and plasma lipcalin-2 were determined. Biopsies underwent modified Marsh scoring. Significance was tested between cases and controls, modified Marsh score and TTG IgA concentration. Results: Lipocalin-2 was significantly elevated in the stool ( p =0.007) but not the plasma of participants with positive celiac serologies compared to controls. There was no significant difference in fecal calprotectin or alpha-1 antitrypsin between participants with positive celiac serologies and controls. Fecal alpha-1 antitrypsin >100mg/dL was specific, but not sensitive for biopsy proven celiac disease. Conclusions: Lipocalin-2 is elevated in the stool but not the plasma of patients with celiac disease suggesting a role in the local inflammatory response. Calprotectin was not a useful marker in the diagnosis of celiac disease and did not correlate with degree of histologic changes on biopsy. While random fecal alpha-1 antitrypsin was not significantly elevated in cases compared to controls, an elevation of greater than 100mg/dL was 90% specific for biopsy proven celiac disease.

RBM47 regulates intestinal injury and tumorigenesis by modifying proliferation, oxidative response, and inflammatory pathways.

RNA-binding protein 47 (RBM47) is required for embryonic endoderm development, but a role in adult intestine is unknown. We studied intestine-specific Rbm47-knockout mice (Rbm47-IKO) following intestinal injury and made crosses into ApcMin/+ mice to examine alterations in intestinal proliferation, response to injury, and tumorigenesis. We also interrogated human colorectal polyps and colon carcinoma tissue. Rbm47-IKO mice exhibited increased proliferation and abnormal villus morphology and cellularity, with corresponding changes in Rbm47-IKO organoids. Rbm47-IKO mice adapted to radiation injury and were protected against chemical-induced colitis, with Rbm47-IKO intestine showing upregulation of antioxidant and Wnt signaling pathways as well as stem cell and developmental genes. Furthermore, Rbm47-IKO mice were protected against colitis-associated cancer. By contrast, aged Rbm47-IKO mice developed spontaneous polyposis, and Rbm47-IKO ApcMin/+ mice manifested an increased intestinal polyp burden. RBM47 mRNA was decreased in human colorectal cancer versus paired normal tissue, along with alternative splicing of tight junction protein 1 mRNA. Public databases revealed stage-specific reduction in RBM47 expression in colorectal cancer associated independently with decreased overall survival. These findings implicate RBM47 as a cell-intrinsic modifier of intestinal growth, inflammatory, and tumorigenic pathways.

SOX9 Expression Is Superior to Other Stem Cell Markers K19 and EpCAM in Predicting Prognosis in Hepatocellular Carcinoma.

Various stem cell markers (eg, epithelial cell adhesion molecule [EpCAM], cytokeratin 19 [K19]) have been reported as predictors of poor prognosis in hepatocellular carcinoma (HCC). However, the data remain limited, particularly in Western populations, and are often contradictory. In this study, the prognostic value of positive SOX9 immunohistochemistry was compared with that of more established markers EpCAM and K19 in a large cohort (n=216) of North American patients. The independent HCC cohort in The Cancer Gene Atlas (n=360) was utilized to validate our findings. Finally, molecular signatures associated with SOX9 -high HCC were determined. We found that the expression of SOX9, but not EpCAM or K19, was associated with worse overall survival and disease-free survival (DFS) and was an independent prognostic factor for DFS in our North American cohort, in which hepatitis C infection was the most common underlying etiology. High SOX9 mRNA level, but not increased expression of EpCAM mRNA or K19 mRNA, was also associated with worse DFS and was an independent prognostic factor for DFS in The Cancer Gene Atlas cohort. This group had underlying causes, including an increased incidence of hepatitis B, significantly different from our initial cohort. High SOX9 mRNA level is associated with molecular pathways important in HCC pathogenesis. Increased SOX9 expression is clinically and biologically relevant for HCC arising in patients with a variety of underlying etiologies. Immunohistochemistry for SOX9 is a reliable proxy for increased SOX9 mRNA and can be used to predict prognosis in HCC cases.

HOIL1 regulates group 2 innate lymphoid cell numbers and type 2 inflammation in the small intestine.

Patients with mutations in HOIL1 experience a complex immune disorder including intestinal inflammation. To investigate the role of HOIL1 in regulating intestinal inflammation, we employed a mouse model of partial HOIL1 deficiency. The ileum of HOIL1-deficient mice displayed features of type 2 inflammation including tuft cell and goblet cell hyperplasia, and elevated expression of Il13, Il5 and Il25 mRNA. Inflammation persisted in the absence of T and B cells, and bone marrow chimeric mice revealed a requirement for HOIL1 expression in radiation-resistant cells to regulate inflammation. Although disruption of IL-4 receptor alpha (IL4Rα) signaling on intestinal epithelial cells ameliorated tuft and goblet cell hyperplasia, expression of Il5 and Il13 mRNA remained elevated. KLRG1hi CD90lo group 2 innate lymphoid cells were increased independent of IL4Rα signaling, tuft cell hyperplasia and IL-25 induction. Antibiotic treatment dampened intestinal inflammation indicating commensal microbes as a contributing factor. We have identified a key role for HOIL1, a component of the Linear Ubiquitin Chain Assembly Complex, in regulating type 2 inflammation in the small intestine. Understanding the mechanism by which HOIL1 regulates type 2 inflammation will advance our understanding of intestinal homeostasis and inflammatory disorders and may lead to the identification of new targets for treatment.

Rhamnose Is Superior to Mannitol as a Monosaccharide in the Dual Sugar Absorption Test: A Prospective Randomized Study in Children With Treatment-Naïve Celiac Disease.

Background and Aim: We sought to correlate two different measures of gut permeability [lactulose:mannitol (L:M) and lactulose:rhamnose (L:R)] to the severity of duodenal histopathology in children with and without elevated antibodies to tissue transglutaminase (tTG). A secondary objective was to correlate gut permeability with celiac disease (CD) serology and indices of inflammation and bacterial product translocation. Methods: We prospectively randomized children undergoing endoscopy with abnormal (n = 54) and normal (n = 10) concentrations of circulating antibodies to tTG, to either L:M or L:R. Biopsies underwent modified Marsh scoring to measure mucosal injury. Circulating anticore Escherichia coli lipopolysaccharide (LPS) IgG, α-1 acid glycoprotein, LPS-binding protein, and C-reactive protein concentrations were measured by enzyme immunoassays. Results: Of the 54 cases with positive celiac serology, 31 and 69% had modified Marsh 0/1 scores or ≥3a, respectively. Circulating tTG IgA correlated with the modified Marsh score (p = 0.03). L:R, but not L:M or percent L excreted, differed according to modified Marsh scores (p = 0.01). There was no significant association between any systemic marker of inflammation or gut injury, and modified Marsh scores. Concerningly, most participants had evidence of urinary M before the challenge sugar was administered. Conclusions: L:R, but not L:M, is associated with modified Marsh scores in children undergoing small bowel biopsy for suspected CD. Despite increased intestinal permeability, we see scant evidence of systemic exposure to gut microbes in these children. Gut permeability testing with L:R may predict which patients with abnormal celiac serology will have biopsy evidence for celiac disease and reduce the proportion of such patients undergoing endoscopy whose Marsh scores are ≤1. M should not be used as a monosaccharide for permeability testing in children.

Non-functional pancreatic neuroendocrine tumours: ATRX/DAXX and alternative lengthening of telomeres (ALT) are prognostically independent from ARX/PDX1 expression and tumour size.

OBJECTIVE: Recent studies have found aristaless-related homeobox gene (ARX)/pancreatic and duodenal homeobox 1 (PDX1), alpha-thalassemia/mental retardation X-linked (ATRX)/death domain-associated protein (DAXX) and alternative lengthening of telomeres (ALT) to be promising prognostic biomarkers for non-functional pancreatic neuroendocrine tumours (NF-PanNETs). However, they have not been comprehensively evaluated, especially among small NF-PanNETs (≤2.0 cm). Moreover, their status in neuroendocrine tumours (NETs) from other sites remains unknown. DESIGN: An international cohort of 1322 NETs was evaluated by immunolabelling for ARX/PDX1 and ATRX/DAXX, and telomere-specific fluorescence in situ hybridisation for ALT. This cohort included 561 primary NF-PanNETs, 107 NF-PanNET metastases and 654 primary, non-pancreatic non-functional NETs and NET metastases. The results were correlated with numerous clinicopathological features including relapse-free survival (RFS). RESULTS: ATRX/DAXX loss and ALT were associated with several adverse prognostic findings and distant metastasis/recurrence (p<0.001). The 5-year RFS rates for patients with ATRX/DAXX-negative and ALT-positive NF-PanNETs were 40% and 42% as compared with 85% and 86% for wild-type NF-PanNETs (p<0.001 and p<0.001). Shorter 5-year RFS rates for ≤2.0 cm NF-PanNETs patients were also seen with ATRX/DAXX loss (65% vs 92%, p=0.003) and ALT (60% vs 93%, p<0.001). By multivariate analysis, ATRX/DAXX and ALT status were independent prognostic factors for RFS. Conversely, classifying NF-PanNETs by ARX/PDX1 expression did not independently correlate with RFS. Except for 4% of pulmonary carcinoids, ATRX/DAXX loss and ALT were only identified in primary (25% and 29%) and NF-PanNET metastases (62% and 71%). CONCLUSIONS: ATRX/DAXX and ALT should be considered in the prognostic evaluation of NF-PanNETs including ≤2.0 cm tumours, and are highly specific for pancreatic origin among NET metastases of unknown primary.

Reverse translation approach generates a signature of penetrating fibrosis in Crohn's disease that is associated with anti-TNF response.

OBJECTIVE: Fibrosis is a common feature of Crohn's disease (CD) which can involve the mesenteric fat. However, the molecular signature of this process remains unclear. Our goal was to define the transcriptional signature of mesenteric fibrosis in CD subjects and to model mesenteric fibrosis in mice to improve our understanding of CD pathogenesis. DESIGN: We performed histological and transcriptional analysis of fibrosis in CD samples. We modelled a CD-like fibrosis phenotype by performing repeated colonic biopsies in mice and analysed the model by histology, type I collagen-targeted positron emission tomography (PET) and global gene expression. We generated a gene set list of essential features of mesenteric fibrosis and compared it to mucosal biopsy datasets from inflammatory bowel disease patients to identify a refined gene set that correlated with clinical outcomes. RESULTS: Mesenteric fibrosis in CD was interconnected to areas of fibrosis in all layers of the intestine, defined as penetrating fibrosis. We found a transcriptional signature of differentially expressed genes enriched in areas of the mesenteric fat of CD subjects with high levels of fibrosis. Mice subjected to repeated colonic biopsies showed penetrating fibrosis as shown by histology, PET imaging and transcriptional analysis. Finally, we composed a composite 24-gene set list that was linked to inflammatory fibroblasts and correlated with treatment response. CONCLUSION: We linked histopathological and molecular features of CD penetrating fibrosis to a mouse model of repeated biopsy injuries. This experimental system provides an innovative approach for functional investigations of underlying profibrotic mechanisms and therapeutic concepts in CD.

Minimally Invasive Postmortem Intestinal Tissue Sampling in Malnourished and Acutely Ill Children Is Feasible and Informative.

BACKGROUND: Intestinal disorders such as environmental enteric dysfunction (EED) are prevalent in low- and middle-income countries (LMICs) and important contributors to childhood undernutrition and mortality. Autopsies are rarely performed in LMICs but minimally invasive tissue sampling is increasingly deployed as a more feasible and acceptable procedure, although protocols have been devoid of intestinal sampling to date. We sought to determine (1) the feasibility of postmortem intestinal sampling, (2) whether autolysis precludes enteric biopsies' utility, and (3) histopathologic features among children who died during hospitalization with acute illness or undernutrition. METHODS: Transabdominal needle and endoscopic forceps upper and lower intestinal sampling were conducted among children aged 1 week to 59 months who died while hospitalized in Blantyre, Malawi. Autolysis ratings were determined for each hematoxylin and eosin slide, and upper and lower intestinal scoring systems were adapted to assess histopathologic features and their severity. RESULTS: Endoscopic and transabdominal sampling procedures were attempted in 28 and 14 cases, respectively, with >90% success obtaining targeted tissue. Varying degrees of autolysis were present in all samples and precluded histopathologic scoring of 6% of 122 biopsies. Greater autolysis in duodenal samples was seen with longer postmortem interval (Beta = 0.06, 95% confidence interval, 0.02-0.11). Histopathologic features identified included duodenal Paneth and goblet cell depletion. Acute inflammation was absent but chronic inflammation was prevalent in both upper and lower enteric samples. Severe chronic rectal inflammation was identified in children as young as 5.5 weeks. CONCLUSIONS: Minimally invasive postmortem intestinal sampling is feasible and identifies histopathology that can inform mortality contributors.

Western diet induces Paneth cell defects through microbiome alterations and farnesoid X receptor and type I interferon activation.

Intestinal Paneth cells modulate innate immunity and infection. In Crohn's disease, genetic mutations together with environmental triggers can disable Paneth cell function. Here, we find that a western diet (WD) similarly leads to Paneth cell dysfunction through mechanisms dependent on the microbiome and farnesoid X receptor (FXR) and type I interferon (IFN) signaling. Analysis of multiple human cohorts suggests that obesity is associated with Paneth cell dysfunction. In mouse models, consumption of a WD for as little as 4 weeks led to Paneth cell dysfunction. WD consumption in conjunction with Clostridium spp. increased the secondary bile acid deoxycholic acid levels in the ileum, which in turn inhibited Paneth cell function. The process required excess signaling of both FXR and IFN within intestinal epithelial cells. Our findings provide a mechanistic link between poor diet and inhibition of gut innate immunity and uncover an effect of FXR activation in gut inflammation.

Crohn's disease-associated ATG16L1 T300A genotype is associated with improved survival in gastric cancer.

BACKGROUND: A non-synonymous single nucleotide polymorphism of the ATG16L1 gene, T300A, is a major Crohn's disease (CD) susceptibility allele, and is known to be associated with increased apoptosis induction in the small intestinal crypt base in CD subjects and mouse models. We hypothesized that ATG16L1 T300A genotype also correlates with increased tumor apoptosis and therefore could lead to superior clinical outcome in cancer subjects. METHODS: T300A genotyping by Taqman assay was performed for gastric carcinoma subjects who underwent resection from two academic medical centers. Transcriptomic analysis was performed by RNA-seq on formalin-fixed paraffin-embedded cancerous tissue. Tumor apoptosis and autophagy were determined by cleaved caspase-3 and p62 immunohistochemistry, respectively. The subjects' genotypes were correlated with demographics, various histopathologic features, transcriptome, and clinical outcome. FINDINGS: Of the 220 genotyped subjects, 163 (74%) subjects carried the T300A allele(s), including 55 (25%) homozygous and 108 (49%) heterozygous subjects. The T300A/T300A subjects had superior overall survival than the other groups. Their tumors were associated with increased CD-like lymphoid aggregates and increased tumor apoptosis without concurrent increase in tumor mitosis or defective autophagy. Transcriptomic analysis showed upregulation of WNT/ß-catenin signaling and downregulation of PPAR, EGFR, and inflammatory chemokine pathways in tumors of T300A/T300A subjects. INTERPRETATION: Gastric carcinoma of subjects with the T300A/T300A genotype is associated with repressed EGFR and PPAR pathways, increased tumor apoptosis, and improved overall survival. Genotyping gastric cancer subjects may provide additional insight for clinical stratification.

Debaryomyces is enriched in Crohn's disease intestinal tissue and impairs healing in mice.

Alterations of the mycobiota composition associated with Crohn's disease (CD) are challenging to link to defining elements of pathophysiology, such as poor injury repair. Using culture-dependent and -independent methods, we discovered that Debaryomyces hansenii preferentially localized to and was abundant within incompletely healed intestinal wounds of mice and inflamed mucosal tissues of CD human subjects. D. hansenii cultures from injured mice and inflamed CD tissues impaired colonic healing when introduced into injured conventionally raised or gnotobiotic mice. We reisolated D. hansenii from injured areas of these mice, fulfilling Koch's postulates. Mechanistically, D. hansenii impaired mucosal healing through the myeloid cell-specific type 1 interferon-CCL5 axis. Taken together, we have identified a fungus that inhabits inflamed CD tissue and can lead to dysregulated mucosal healing.