Microbiota-derived metabolite promotes HDAC3 activity in the gut.

The coevolution of mammalian hosts and their beneficial commensal microbes has led to development of symbiotic host-microbiota relationships1. Epigenetic machinery permits mammalian cells to integrate environmental signals2; however, how these pathways are fine-tuned by diverse cues from commensal bacteria is not well understood. Here we reveal a highly selective pathway through which microbiota-derived inositol phosphate regulates histone deacetylase 3 (HDAC3) activity in the intestine. Despite the abundant presence of HDAC inhibitors such as butyrate in the intestine, we found that HDAC3 activity was sharply increased in intestinal epithelial cells of microbiota-replete mice compared with germ-free mice. This divergence was reconciled by the finding that commensal bacteria, including Escherichia coli, stimulated HDAC activity through metabolism of phytate and production of inositol-1,4,5-trisphosphate (InsP3). Both intestinal exposure to InsP3 and phytate ingestion promoted recovery following intestinal damage. Of note, InsP3 also induced growth of intestinal organoids derived from human tissue, stimulated HDAC3-dependent proliferation and countered butyrate inhibition of colonic growth. Collectively, these results show that InsP3 is a microbiota-derived metabolite that activates a mammalian histone deacetylase to promote epithelial repair. Thus, HDAC3 represents a convergent epigenetic sensor of distinct metabolites that calibrates host responses to diverse microbial signals.

pH regulates hematopoietic stem cell potential via polyamines.

Upon ex vivo culture, hematopoietic stem cells (HSCs) quickly lose potential and differentiate into progenitors. The identification of culture conditions that maintain the potential of HSCs ex vivo is therefore of high clinical interest. Here, we demonstrate that the potential of murine and human HSCs is maintained when cultivated for 2 days ex vivo at a pH of 6.9, in contrast to cultivation at the commonly used pH of 7.4. When cultivated at a pH of 6.9, HSCs remain smaller, less metabolically active, less proliferative and show enhanced reconstitution ability upon transplantation compared to HSC cultivated at pH 7.4. HSCs kept at pH 6.9 show an attenuated polyamine pathway. Pharmacological inhibition of the polyamine pathway in HSCs cultivated at pH 7.4 with DFMO mimics phenotypes and potential of HSCs cultivated at pH 6.9. Ex vivo exposure to a pH of 6.9 is therefore a positive regulator of HSC function by reducing polyamines. These findings might improve HSC short-term cultivation protocols for transplantation and gene therapy interventions.

Stratification of risk of progression to colectomy in ulcerative colitis via measured and predicted gene expression.

An important goal of clinical genomics is to be able to estimate the risk of adverse disease outcomes. Between 5% and 10% of individuals with ulcerative colitis (UC) require colectomy within 5 years of diagnosis, but polygenic risk scores (PRSs) utilizing findings from genome-wide association studies (GWASs) are unable to provide meaningful prediction of this adverse status. By contrast, in Crohn disease, gene expression profiling of GWAS-significant genes does provide some stratification of risk of progression to complicated disease in the form of a transcriptional risk score (TRS). Here, we demonstrate that a measured TRS based on bulk rectal gene expression in the PROTECT inception cohort study has a positive predictive value approaching 50% for colectomy. Single-cell profiling demonstrates that the genes are active in multiple diverse cell types from both the epithelial and immune compartments. Expression quantitative trait locus (QTL) analysis identifies genes with differential effects at baseline and week 52 follow-up, but for the most part, differential expression associated with colectomy risk is independent of local genetic regulation. Nevertheless, a predicted polygenic transcriptional risk score (PPTRS) derived by summation of transcriptome-wide association study (TWAS) effects identifies UC-affected individuals at 5-fold elevated risk of colectomy with data from the UK Biobank population cohort studies, independently replicated in an NIDDK-IBDGC dataset. Prediction of gene expression from relatively small transcriptome datasets can thus be used in conjunction with TWASs for stratification of risk of disease complications.

The Role of Pancreatitis Risk Genes in Endocrine Insufficiency Development After Acute Pancreatitis in Children.

BACKGROUND & AIMS: Acute pancreatitis (AP) is increasingly recognized as a risk factor for diabetes mellitus (DM). We aimed to study the association of pancreatitis genes with pancreatic endocrine insufficiency (pre-DM and DM) development post-AP in children. METHODS: This was an observational cohort study that enrolled subjects ≤21 years with their first episode of AP and followed them for 12 months for the development of pancreatic endocrine insufficiency. Pancreatitis risk genes (CASR, CEL, CFTR, CLDN2, CPA1, CTRC, PRSS1, SBDS, SPINK1, and UBR1) were sequenced. A genetic risk score was derived from all genes with univariable P < .15. RESULTS: A total 120 subjects with AP were genotyped. Sixty-three subjects (52.5%) had at least 1 reportable variant identified. For modeling the development of pancreatic endocrine insufficiency at 1 year, 6 were excluded (2 with DM at baseline, 3 with total pancreatectomy, and 1 death). From this group of 114, 95 remained normoglycemic and 19 (17%) developed endocrine insufficiency (4 DM, 15 pre-DM). Severe AP (58% vs 20%; P = .001) and at least 1 gene affected (79% vs 47%; P = .01) were enriched among the endocrine-insufficient group. Those with versus without endocrine insufficiency were similar in age, sex, race, ethnicity, body mass index, and AP recurrence. A model for pre-DM/DM development included AP severity (odds ratio, 5.17 [1.66-16.15]; P = .005) and genetic risk score (odds ratio, 4.89 [1.83-13.08]; P = .002) and had an area under the curve of 0.74. CONCLUSIONS: In this cohort of children with AP, pancreatitis risk genes and AP disease severity were associated with pre-DM or DM development post-AP.

EZH2 is a key component of hepatoblastoma tumor cell growth.

BACKGROUND: Enhancer of zeste homolog 2 (EZH2) catalyzes the trimethylation of histone H3 at lysine 27 via the polycomb recessive complex 2 (PRC2) and plays a time-specific role in normal fetal liver development. EZH2 is overexpressed in hepatoblastoma (HB), an embryonal tumor. EZH2 can also promote tumorigenesis via a noncanonical, PRC2-independent mechanism via proto-oncogenic, direct protein interaction, including ß-catenin. We hypothesize that the pathological activation of EZH2 contributes to HB propagation in a PRC2-independent manner. METHODS AND RESULTS: We demonstrate that EZH2 promotes proliferation in HB tumor-derived cell lines through interaction with ß-catenin. Although aberrant EZH2 expression occurs, we determine that both canonical and noncanonical EZH2 signaling occurs based on specific gene-expression patterns and interaction with SUZ12, a PRC2 component, and ß-catenin. Silencing and inhibition of EZH2 reduce primary HB cell proliferation. CONCLUSIONS: EZH2 overexpression promotes HB cell proliferation, with both canonical and noncanonical function detected. However, because EZH2 directly interacts with ß-catenin in human tumors and EZH2 overexpression is not equal to SUZ12, it seems that a noncanonical mechanism is contributing to HB pathogenesis. Further mechanistic studies are necessary to elucidate potential pathogenic downstream mechanisms and translational potential of EZH2 inhibitors for the treatment of HB.

Association Between MR Elastography Liver Stiffness and Histologic Liver Fibrosis in Children and Young Adults With Autoimmune Liver Disease.

BACKGROUND. Liver fibrosis is an important clinical endpoint of the progression of autoimmune liver disease (AILD); its monitoring would benefit from noninvasive imaging tools. OBJECTIVE. The purpose of this study was to assess the relationship between MR elastography (MRE) liver stiffness measurements and histologic liver fibrosis, as well as to evaluate the performance of MRE and biochemical-based clinical markers for stratifying histologic liver fibrosis severity, in children and young adults with AILD. METHODS. This retrospective study used an existing institutional registry of children and young adults diagnosed with AILD (primary sclerosing cholangitis [PSC], autoimmune sclerosing cholangitis [ASC], or autoimmune hepatitis [AIH]). The registry was searched to identify patients who underwent both a research abdominal 1.5-T MRI examination that included liver MRE (performed for registry enrollment) and a clinically indicated liver biopsy within 6 months of that examination. MRE used a 2D gradient-recalled echo sequence. One analyst measured mean liver shear stiffness (in kilopascals) for each examination. Laboratory markers of liver fibrosis (aspartate aminotransferase-to-platelet ratio index [APRI] and fibrosis-4 [FIB-4] score) were recorded. For investigational purposes, one pathologist, blinded to clinical and MRI data, determined histologic Metavir liver fibrosis stage. The Spearman rank order correlation coefficient was calculated between MRE liver stiffness and Metavir liver fibrosis stage. ROC analysis was used to evaluate diagnostic performance for identifying advanced fibrosis (i.e., differentiating Metavir F0-F1 from F2-F4 fibrosis), and sensitivity and specificity were calculated using the Youden index. RESULTS. The study included 46 patients (median age, 16.6 years [IQR, 13.7-17.8 years]; 20 female patients, 26 male patients); 12 had PSC, 10 had ASC, and 24 had AIH. Median MRE liver stiffness was 2.9 kPa (IQR, 2.2-4.0 kPa). MRE liver stiffness and Meta-vir fibrosis stage showed strong positive correlation (ρ = 0.68). For identifying advanced liver fibrosis, MRE liver stiffness had an AUC of 0.81, with sensitivity of 65.4% and specificity of 90.0%; APRI had an AUC of 0.72, with sensitivity of 64.0% and specificity of 80.0%; and FIB-4 score had an AUC of 0.71, with sensitivity of 60.0% and specificity of 85.0%. CONCLUSION. MRE liver stiffness measurements were associated with histologic liver fibrosis severity. CLINICAL IMPACT. The findings support a role for MRE in noninvasive monitoring of liver stiffness, a surrogate for fibrosis, in children and young adults with AILD. TRIAL REGISTRATION. ClinicalTrials.gov NCT03175471.

De novo formation of the biliary system by TGFß-mediated hepatocyte transdifferentiation.

Transdifferentiation is a complete and stable change in cell identity that serves as an alternative to stem-cell-mediated organ regeneration. In adult mammals, findings of transdifferentiation have been limited to the replenishment of cells lost from preexisting structures, in the presence of a fully developed scaffold and niche1. Here we show that transdifferentiation of hepatocytes in the mouse liver can build a structure that failed to form in development-the biliary system in a mouse model that mimics the hepatic phenotype of human Alagille syndrome (ALGS)2. In these mice, hepatocytes convert into mature cholangiocytes and form bile ducts that are effective in draining bile and persist after the cholestatic liver injury is reversed, consistent with transdifferentiation. These findings redefine hepatocyte plasticity, which appeared to be limited to metaplasia, that is, incomplete and transient biliary differentiation as an adaptation to cell injury, based on previous studies in mice with a fully developed biliary system3-6. In contrast to bile duct development7-9, we show that de novo bile duct formation by hepatocyte transdifferentiation is independent of NOTCH signalling. We identify TGFß signalling as the driver of this compensatory mechanism and show that it is active in some patients with ALGS. Furthermore, we show that TGFß signalling can be targeted to enhance the formation of the biliary system from hepatocytes, and that the transdifferentiation-inducing signals and remodelling capacity of the bile-duct-deficient liver can be harnessed with transplanted hepatocytes. Our results define the regenerative potential of mammalian transdifferentiation and reveal opportunities for the treatment of ALGS and other cholestatic liver diseases.

Multicenter Cohort Study of Infliximab Pharmacokinetics and Therapy Response in Pediatric Acute Severe Ulcerative Colitis.

BACKGROUND & AIMS: We aimed to model infliximab (IFX) pharmacokinetics (PK) in pediatric acute severe ulcerative colitis (ASUC) and assess the association between PK parameters, including drug exposure, and clinical response. METHODS: We studied a multicenter prospective cohort of hospitalized children initiating IFX for ASUC or IBD-unclassified. Serial IFX serum concentrations over 26 weeks were used to develop a PK model. We tested the association of PK parameter estimates with day 7 clinical response, week 8 clinical remission, week 26 corticosteroid-free clinical remission (CSF-CR) (using the Pediatric Ulcerative Colitis Activity Index), and colectomy-free survival. RESULTS: Thirty-eight participants received IFX (median initial dose, 9.9 mg/kg). Day 7 clinical response, week 8 clinical remission, and week 26 CSF-CR occurred in 71%, 55%, and 43%, respectively. Albumin, C-reactive protein, white blood cell count, platelets, weight, and antibodies to IFX were significant covariates incorporated into a PK model. Week 26 non-remitters exhibited faster IFX clearance than remitters (P = .013). However, cumulative IFX exposure did not differ between clinical response groups. One (2.7%) and 4 (10.8%) participants underwent colectomy by week 26 and 2 years, respectively. Day 3 IFX clearance >0.02 L/h was associated with colectomy (hazard ratio, 58.2; 95% confidence interval, 6.0-568.6; P < .001). CONCLUSIONS: At median higher-than-label IFX dosing for pediatric ASUC, baseline faster IFX CL was associated with colectomy and at week 26 with lack of CSF-CR. IFX exposure was not predictive of clinical outcomes. Higher IFX dosing may sufficiently optimize early outcomes in pediatric ASUC. Larger studies are warranted to determine whether sustained intensification can overcome rapid clearance and improve later outcomes. CLINICALTRIALS: gov identifier: NCT02799615.

Transcriptome analysis in acute gastrointestinal graft-versus host disease reveals a unique signature in children and shared biology with pediatric inflammatory bowel disease.

We performed transcriptomic analyses on freshly frozen (n=21) and paraffin-embedded (n=35) gastrointestinal (GI) biopsies from children with and without acute acute GI graft-versus-host disease (GvHD) to study differential gene expressions. We identified 164 significant genes, 141 upregulated and 23 downregulated, in acute GvHD from freshy frozen biopsies. CHI3L1 was the top differentially expressed gene in acute GvHD, involved in macrophage recruitment and bacterial adhesion. Mitochondrial genes were among the top downregulated genes. Immune deconvolution identified a macrophage cellular signature. Weighted gene co-expression network analysis showed enrichment of genes in the ERK1/2 cascade. Transcriptome data from 206 ulcerative colitis (UC) patients were included to uncover genes and pathways shared between GvHD and UC. Comparison with the UC transcriptome showed both shared and distinct pathways. Both UC and GvHD transcriptomes shared an innate antimicrobial signature and FCγ1RA/CD64 was upregulated in both acute GvHD (log-fold increase 1.7, P=0.001) and UC. Upregulation of the ERK1/2 cascade pathway was specific to GvHD. We performed additional experiments to confirm transcriptomics. Firstly, we examined phosphorylation of ERK (pERK) by immunohistochemistry on GI biopsies (acute GvHD n=10, no GvHD n=10). pERK staining was increased in acute GvHD biopsies compared to biopsies without acute GvHD (P=0.001). Secondly, plasma CD64, measured by enzyme-linked immunsorbant assay (n=85) was elevated in acute GI GvHD (P<0.001) compared with those without and was elevated in GVHD compared with inflammatory bowel disease (n=47) (P<0.001), confirming the upregulated expression seen in the transcriptome.

Therapeutic Targeting of the GSK3ß-CUGBP1 Pathway in Myotonic Dystrophy.

Myotonic Dystrophy type 1 (DM1) is a neuromuscular disease associated with toxic RNA containing expanded CUG repeats. The developing therapeutic approaches to DM1 target mutant RNA or correct early toxic events downstream of the mutant RNA. We have previously described the benefits of the correction of the GSK3ß-CUGBP1 pathway in DM1 mice (HSALR model) expressing 250 CUG repeats using the GSK3 inhibitor tideglusib (TG). Here, we show that TG treatments corrected the expression of ~17% of genes misregulated in DM1 mice, including genes involved in cell transport, development and differentiation. The expression of chloride channel 1 (Clcn1), the key trigger of myotonia in DM1, was also corrected by TG. We found that correction of the GSK3ß-CUGBP1 pathway in mice expressing long CUG repeats (DMSXL model) is beneficial not only at the prenatal and postnatal stages, but also during adulthood. Using a mouse model with dysregulated CUGBP1, which mimics alterations in DM1, we showed that the dysregulated CUGBP1 contributes to the toxicity of expanded CUG repeats by changing gene expression and causing CNS abnormalities. These data show the critical role of the GSK3ß-CUGBP1 pathway in DM1 muscle and in CNS pathologies, suggesting the benefits of GSK3 inhibitors in patients with different forms of DM1.

DHA Supplementation Attenuates Inflammation-Associated Gene Expression in the Mammary Gland of Lactating Mothers Who Deliver Preterm.

BACKGROUND: In a randomized trial of DHA supplementation to lactating mothers who delivered preterm, there were significant increases in DHA status in the mother and her infant. OBJECTIVES: Our objective here was to characterize the mammary gland transcriptomes from the above study. We hypothesized that proinflammatory gene expression would be attenuated in the increased DHA group compared with the standard DHA group. METHODS: In the original trial, mothers delivering at <29 wk gestation at the University of Cincinnati Medical Center and intending to express their milk were randomly assigned to supplementation with 200 mg/d DHA (standard group: STD) or 1000 mg/d DHA (experimental group: EXP) within 7 d of delivery. Here, we conducted RNA-seq transcriptome analysis of n = 5 EXP and n = 4 STD extracellular mammary mRNA samples extracted from the fat layer of milk samples obtained 4 wk postenrollment. Transcripts were assessed for differential expression (false discovery rate adjusted P value <0.05) and clustering between EXP compared with STD groups. Ontological analysis of all differentially expressed genes (DEGs) was performed with Toppcluster. RESULTS: There were 409 DEGs. We observed 5 main groups of biological processes that were upregulated, including those associated with improved immune regulation and management of oxidative stress; and 3 main groups of biological processes that were downregulated, including 1 associated with immune dysregulation. For example, we observed upregulation of inflammation-inhibiting genes including NFKB inhibitor alpha (NFKBIA; fold-change (FC), adjusted P value: FC = 1.70, P = 0.007) and interleukin-18 binding protein (IL18BP: FC = 2.2, adjusted P = 0.02); and downregulation of proinflammatory genes including interleukin 7 receptor (IL7R: FC = -1.9, adjusted P = 0.02) and interleukin 1 receptor like 1 (IL1RL1: FC = -13.0, adjusted P = 0.02). CONCLUSIONS: Increased DHA supplementation during lactation can modulate the expression of inflammation-related genes within the mammary gland. This might translate to milk composition with a more optimal inflammasome profile. Future research with a larger clinical trial and greater interrogation of clinical outcomes is warranted.

Clinical and biological predictors of response to standardised paediatric colitis therapy (PROTECT): a multicentre inception cohort study.

BACKGROUND: Lack of evidence-based outcomes data leads to uncertainty in developing treatment regimens in children who are newly diagnosed with ulcerative colitis. We hypothesised that pretreatment clinical, transcriptomic, and microbial factors predict disease course. METHODS: In this inception cohort study, we recruited paediatric patients aged 4-17 years with newly diagnosed ulcerative colitis from 29 centres in the USA and Canada. Patients initially received standardised mesalazine or corticosteroids, with pre-established criteria for escalation to immunomodulators (ie, thiopurines) or anti-tumor necrosis factor-α (TNFα) therapy. We used RNA sequencing to define rectal gene expression before treatment, and 16S sequencing to characterise rectal and faecal microbiota. The primary outcome was week 52 corticosteroid-free remission with no therapy beyond mesalazine. We assessed factors associated with the primary outcome using logistic regression models of the per-protocol population. This study is registered with ClinicalTrials.gov, number NCT01536535. FINDINGS: Between July 10, 2012, and April 21, 2015, of 467 patients recruited, 428 started medical therapy, of whom 400 (93%) were evaluable at 52 weeks and 386 (90%) completed the study period with no protocol violations. 150 (38%) of 400 participants achieved week 52 corticosteroid-free remission, of whom 147 (98%) were taking mesalazine and three (2%) were taking no medication. 74 (19%) of 400 were escalated to immunomodulators alone, 123 (31%) anti-TNFα therapy, and 25 (6%) colectomy. Low baseline clinical severity, high baseline haemoglobin, and week 4 clinical remission were associated with achieving week 52 corticosteroid-free remission (n=386, logistic model area under the curve [AUC] 0·70, 95% CI 0·65-0·75; specificity 77%, 95% CI 71-82). Baseline severity and remission by week 4 were validated in an independent cohort of 274 paediatric patients with newly diagnosed ulcerative colitis. After adjusting for clinical predictors, an antimicrobial peptide gene signature (odds ratio [OR] 0·57, 95% CI 0·39-0·81; p=0·002) and abundance of Ruminococcaceae (OR 1·43, 1·02-2·00; p=0·04), and Sutterella (OR 0·81, 0·65-1·00; p=0·05) were independently associated with week 52 corticosteroid-free remission. INTERPRETATION: Our findings support the utility of initial clinical activity and treatment response by 4 weeks to predict week 52 corticosteroid-free remission with mesalazine alone in children who are newly diagnosed with ulcerative colitis. The development of personalised clinical and biological signatures holds the promise of informing ulcerative colitis therapeutic decisions. FUNDING: US National Institutes of Health.

Augmenter of liver regeneration protein deficiency promotes hepatic steatosis by inducing oxidative stress and microRNA-540 expression.

Levels of augmenter of liver regeneration (ALR), a multifunctional protein, are reduced in steatohepatitis. ALR depletion from ALR flox/flox/Alb-Cre [ALR-L-knockout (KO)] mouse causes robust steatosis and apoptosis of hepatocytes, and pericellular fibrosis between 1 and 2 wk postbirth. Steatosis regresses by 4 wk upon reappearance of ALR-expressing hepatocytes. We investigated mechanisms of ALR depletion-induced steatosis. ALR-L-KO mice (1-, 2-, and 4 wk old) and Adeno-Cre-transfected ALR flox/flox hepatocytes were used for in vivo and in vitro studies. ALR depletion from hepatocytes in vivo downregulated peroxisome proliferator-activated receptor (PPAR)-α, carnitine palmitoyl transferase I (CPT1)a, peroxisomal membrane protein 70 (PMP70) (modest down-regulation), and acyl-CoA oxidase 1 (ACOX1). The markedly up-regulated (20X) novel microRNA-540 (miR-540) was identified to target PPARα, PMP70, ACOX1, and CPT1a. ALR depletion from primary hepatocytes increased oxidative stress, miR-540 expression, and steatosis and down-regulated PPARα, ACOX1, PMP70, and CPT1a expression. Anti-miR-540 mitigated ALR depletion-induced steatosis and prevented loss of PPARα, ACOX1, PMP70, and CPT1a expression. Antioxidant N-acetylcysteine and recombinant ALR (rALR) both inhibited ALR depletion-induced miR-540 expression and lipid accumulation in hepatocytes. Finally, treatment of ALR-L-KO mice with rALR between 1 and 2 wk prevented miR-540 expression, and arrested steatosis and fibrosis. We conclude that ALR deficiency-mediated oxidative stress induces generation of miR-540, which promotes steatosis by dysregulating peroxisomal and mitochondrial lipid homeostasis.-Kumar, S., Rani, R., Karns, R., Gandhi, C. R. Augmenter of liver regeneration protein deficiency promotes hepatic steatosis by inducing oxidative stress and microRNA-540 expression.

A Novel Pkhd1 Mutation Interacts with the Nonobese Diabetic Genetic Background To Cause Autoimmune Cholangitis.

We previously reported that NOD.c3c4 mice develop spontaneous autoimmune biliary disease (ABD) with anti-mitochondrial Abs, histopathological lesions, and autoimmune T lymphocytes similar to human primary biliary cholangitis. In this article, we demonstrate that ABD in NOD.c3c4 and related NOD ABD strains is caused by a chromosome 1 region that includes a novel mutation in polycystic kidney and hepatic disease 1 (Pkhd1). We show that a long terminal repeat element inserted into intron 35 exposes an alternative polyadenylation site, resulting in a truncated Pkhd1 transcript. A novel NOD congenic mouse expressing aberrant Pkhd1, but lacking the c3 and c4 chromosomal regions (NOD.Abd3), reproduces the immunopathological features of NOD ABD. RNA sequencing of NOD.Abd3 common bile duct early in disease demonstrates upregulation of genes involved in cholangiocyte injury/morphology and downregulation of immunoregulatory genes. Consistent with this, bone marrow chimera studies show that aberrant Pkhd1 must be expressed in the target tissue (cholangiocytes) and the immune system (bone marrow). Mutations of Pkhd1 produce biliary abnormalities in mice but have not been previously associated with autoimmunity. In this study, we eliminate clinical biliary disease by backcrossing this Pkhd1 mutation onto the C57BL/6 genetic background; thus, the NOD genetic background (which promotes autoimmunity) is essential for disease. We propose that loss of functional Pkhd1 on the NOD background produces early bile duct abnormalities, initiating a break in tolerance that leads to autoimmune cholangitis in NOD.Abd3 congenic mice. This model is important for understanding loss of tolerance to cholangiocytes and is relevant to the pathogenesis of several human cholangiopathies.

FXR is a molecular target for the effects of vertical sleeve gastrectomy.

Bariatric surgical procedures, such as vertical sleeve gastrectomy (VSG), are at present the most effective therapy for the treatment of obesity, and are associated with considerable improvements in co-morbidities, including type-2 diabetes mellitus. The underlying molecular mechanisms contributing to these benefits remain largely undetermined, despite offering the potential to reveal new targets for therapeutic intervention. Substantial changes in circulating total bile acids are known to occur after VSG. Moreover, bile acids are known to regulate metabolism by binding to the nuclear receptor FXR (farsenoid-X receptor, also known as NR1H4). We therefore examined the results of VSG surgery applied to mice with diet-induced obesity and targeted genetic disruption of FXR. Here we demonstrate that the therapeutic value of VSG does not result from mechanical restriction imposed by a smaller stomach. Rather, VSG is associated with increased circulating bile acids, and associated changes to gut microbial communities. Moreover, in the absence of FXR, the ability of VSG to reduce body weight and improve glucose tolerance is substantially reduced. These results point to bile acids and FXR signalling as an important molecular underpinning for the beneficial effects of this weight-loss surgery.

17ß-Estradiol protects the esophageal epithelium from IL-13-induced barrier dysfunction and remodeling.

BACKGROUND: The incidence of eosinophilic esophagitis (EoE) is greater in male than female subjects, and the underlying molecular basis for this sex bias remains unclear. OBJECTIVE: We sought to delineate the contribution of the sex hormone estrogen to the EoE phenotype and esophageal epithelial barrier function and remodeling. METHODS: We performed demographic and incidence analyses of EoE in male and female subjects from a single-center pediatric cohort. Estrogen-responsive gene expression analyses and estrogen receptor (ESR) immunofluorescence staining of esophageal biopsy specimens from patients with EoE and control subjects were performed. The effect of 17ß-estradiol (E2) on IL-13-induced signaling pathways, gene expression, and esophageal epithelial architecture and barrier function in a primary human esophageal keratinocyte cell (EPC2) culture system (EPC2-air-liquid interface) was examined. RESULTS: We observed a male predominance in patients with EoE. Analyses of RNA sequencing data sets revealed a significant dysregulation of the estrogen-responsive gene network and expression of ESR1 and ESR2 in esophageal biopsy specimens from patients with EoE compared with control subjects. IL-13 stimulation of EPC2-air-liquid interface cells led to altered cellular architecture with induced dilation of intercellular spaces and barrier dysfunction. Pretreatment of EPC2s with E2 prior to IL-13 exposure abrogated IL-13-induced architectural changes and esophageal barrier dysfunction. Mechanistically, E2-protective effects were dependent on ESR2 and associated with diminishing of IL-13-induced tyrosine kinase 2 and signal transducer and activator of transcription 6 phosphorylation and EoE-dysregulated gene expression. CONCLUSIONS: Estrogen-responsive genes are modified in patients with EoE compared with control subjects. E2 attenuated IL-13-induced architectural changes and esophageal epithelial barrier dysfunction through inhibition of the IL-13/tyrosine kinase 2/signal transducer and activator of transcription 6 pathway via ESR2-dependent process. Estrogen hormone signaling may protect against development of EoE in female subjects.

Clinical and Genomic Correlates of Neutrophil Reactive Oxygen Species Production in Pediatric Patients With Crohn's Disease.

BACKGROUND & AIMS: Individuals with monogenic disorders of phagocyte function develop chronic colitis that resembles Crohn's disease (CD). We tested for associations between mutations in genes encoding reduced nicotinamide adenine dinucleotide phosphate (NADPH) oxidases, neutrophil function, and phenotypes of CD in pediatric patients. METHODS: We performed whole-exome sequence analysis to identify mutations in genes encoding NADPH oxidases (such as CYBA, CYBB, NCF1, NCF2, NCF4, RAC1, and RAC2) using DNA from 543 pediatric patients with inflammatory bowel diseases. Blood samples were collected from an additional 129 pediatric patients with CD and 26 children without IBD (controls); we performed assays for neutrophil activation, reactive oxygen species (ROS) production, and bacteria uptake and killing. Whole-exome sequence analysis was performed using DNA from 46 of the children with CD to examine associations with NADPH gene mutations; RNA sequence analyses were performed using blood cells from 46 children with CD to test for variations in neutrophil gene expression associated with ROS production. RESULTS: We identified 26 missense mutations in CYBA, CYBB, NCF1, NCF2, and NCF4. Patients with CD who carried mutations in these genes were 3-fold more likely to have perianal disease (P = .0008) and stricturing complications (P = .002) than children with CD without these mutations. Among patients with CD with none of these mutations, 9% had undergone abdominal surgery; among patients with mutations in these NADPH oxidase genes, 31% had undergone abdominal surgery (P = .0004). A higher proportion of neutrophils from children with CD had low ROS production (47%) than from controls (15%) among the 129 patients tested for ROS (P = .002). Minor alleles of the NADPH genes were detected in 7% of children with CD whose neutrophils produced normal levels of ROS vs 38% of children whose neutrophils produced low levels of ROS (P = .009). Neutrophils that produced low levels of ROS had specific alterations in genes that regulate glucose metabolism and antimicrobial responses. CONCLUSIONS: We identified missense mutations in genes that encode NADPH oxidases in children with CD; these were associated with a more aggressive disease course and reduced ROS production by neutrophils from the patients.

Interleukin 2 Promotes Hepatic Regulatory T Cell Responses and Protects From Biliary Fibrosis in Murine Sclerosing Cholangitis.

In the multidrug resistance protein 2 (Mdr2)-/- mouse model, low phospholipid bile instigates biliary epithelial injury, sterile inflammation, and fibrosis, thereby recapitulating disease mechanisms implicated in biliary atresia (BA) and primary sclerosing cholangitis. We hypothesize that T lymphocytes contribute to the biliary injury and fibrosis in murine sclerosing cholangitis (SC) and that they are susceptible to suppression by regulatory T cells (Tregs). In juvenile Mdr2-/- mice, intrahepatic CD8+ lymphocytes were expanded, and contraction of intrahepatic Tregs coincided with rising serum alanine transferase and alkaline phosphatase (ALP) levels between days 14-30 of life. Antibody-mediated depletion of intrahepatic CD8+ lymphocytes during that time reduced ALP levels and the expression of osteopontin (Opn), a pro-fibrogenic cytokine. Depletion of intrahepatic Tregs with anti-CD25 antibody between days 7-30 increased intrahepatic CD8+ T cells, Opn expression, and fibrosis. Conversely, expansion of intrahepatic Tregs with interleukin 2/anti-interleukin 2 immune complexes (IL-2c) downregulated hepatic expression of Opn and Tnf, reduced frequency of intrahepatic CD8+ lymphocytes, and diminished biliary injury and fibrosis. Treatment with IL-2c upregulated hepatic Treg expression of CD39, an ectonucleotidase capable of hydrolyzing pro-inflammatory adenosine triphosphate. In vitro, Tregs expressing CD39 suppressed the proliferation of hepatic CD8+ lymphocytes from Mdr2-/- mice more efficiently than those lacking CD39. In infants with BA, infiltration of interlobular bile ducts with CD8+ cells was associated with biliary expression of Opn and its transcription was negatively correlated with mRNA expression of Treg-associated genes. Conclusion: Hepatic CD8+ T lymphocytes drive biliary injury and fibrosis in murine SC. Their proliferation is controlled by hepatic Tregs through the purinergic pathway, which is responsive to IL-2c, suggesting that Treg-directed low-dose Il-2 treatment may be considered as therapy for SC.

Correction of GSK3ß at young age prevents muscle pathology in mice with myotonic dystrophy type 1.

Myotonic dystrophy type 1 (DM1) is a progressive neuromuscular disease caused by expanded CUG repeats, which misregulate RNA metabolism through several RNA-binding proteins, including CUG-binding protein/CUGBP1 elav-like factor 1 (CUGBP1/CELF1) and muscleblind 1 protein. Mutant CUG repeats elevate CUGBP1 and alter CUGBP1 activity via a glycogen synthase kinase 3ß (GSK3ß)-cyclin D3-cyclin D-dependent kinase 4 (CDK4) signaling pathway. Inhibition of GSK3ß corrects abnormal activity of CUGBP1 in DM1 mice [human skeletal actin mRNA, containing long repeats ( HSALR) model]. Here, we show that the inhibition of GSK3ß in young HSALR mice prevents development of DM1 muscle pathology. Skeletal muscle in 1-yr-old HSALR mice, treated at 1.5 mo for 6 wk with the inhibitors of GSK3, exhibits high fiber density, corrected atrophy, normal fiber size, with reduced central nuclei and normalized grip strength. Because CUG-GSK3ß-cyclin D3-CDK4 converts the active form of CUGBP1 into a form of translational repressor, we examined the contribution of CUGBP1 in myogenesis using Celf1 knockout mice. We found that a loss of CUGBP1 disrupts myogenesis, affecting genes that regulate differentiation and the extracellular matrix. Proteins of those pathways are also misregulated in young HSALR mice and in muscle biopsies of patients with congenital DM1. These findings suggest that the correction of GSK3ß-CUGBP1 pathway in young HSALR mice might have a positive effect on the myogenesis over time.-Wei, C., Stock, L., Valanejad, L., Zalewski, Z. A., Karns, R., Puymirat, J., Nelson, D., Witte, D., Woodgett, J., Timchenko, N. A., Timchenko, L. Correction of GSK3ß at young age prevents muscle pathology in mice with myotonic dystrophy type 1.

Mucosal Expression of Type 2 and Type 17 Immune Response Genes Distinguishes Ulcerative Colitis From Colon-Only Crohn's Disease in Treatment-Naive Pediatric Patients.

BACKGROUND & AIMS: There is controversy regarding the role of the type 2 immune response in the pathogenesis of ulcerative colitis (UC)-few data are available from treatment-naive patients. We investigated whether genes associated with a type 2 immune response in the intestinal mucosa are up-regulated in treatment-naive pediatric patients with UC compared with patients with Crohn's disease (CD)-associated colitis or without inflammatory bowel disease (IBD), and whether expression levels are associated with clinical outcomes. METHODS: We used a real-time reverse-transcription quantitative polymerase chain reaction array to analyze messenger RNA (mRNA) expression patterns in rectal mucosal samples from 138 treatment-naive pediatric patients with IBD and macroscopic rectal disease, as well as those from 49 children without IBD (controls), enrolled in a multicenter prospective observational study from 2008 to 2012. Results were validated in real-time reverse-transcription quantitative polymerase chain reaction analyses of rectal RNA from an independent cohort of 34 pediatric patients with IBD and macroscopic rectal disease and 17 controls from Cincinnati Children's Hospital Medical Center. RESULTS: We measured significant increases in mRNAs associated with a type 2 immune response (interleukin [IL]5 gene, IL13, and IL13RA2) and a type 17 immune response (IL17A and IL23) in mucosal samples from patients with UC compared with patients with colon-only CD. In a regression model, increased expression of IL5 and IL17A mRNAs distinguished patients with UC from patients with colon-only CD (P = .001; area under the receiver operating characteristic curve, 0.72). We identified a gene expression pattern in rectal tissues of patients with UC, characterized by detection of IL13 mRNA, that predicted clinical response to therapy after 6 months (odds ratio [OR], 6.469; 95% confidence interval [CI], 1.553-26.94), clinical response after 12 months (OR, 6.125; 95% CI, 1.330-28.22), and remission after 12 months (OR, 5.333; 95% CI, 1.132-25.12). CONCLUSIONS: In an analysis of rectal tissues from treatment-naive pediatric patients with IBD, we observed activation of a type 2 immune response during the early course of UC. We were able to distinguish patients with UC from those with colon-only CD based on increased mucosal expression of genes that mediate type 2 and type 17 immune responses. Increased expression at diagnosis of genes that mediate a type 2 immune response is associated with response to therapy and remission in pediatric patients with UC.