Gene expression alterations in ulcerative colitis patients after restorative proctocolectomy extend to the small bowel proximal to the pouch

Targeting glutamate carboxypeptidase II in IBD

Over the past decade, the zinc metalloenzyme glutamate carboxypeptidase (GCPII) has emerged as a novel therapeutic target for IBD. This enzyme is minimally expressed in healthy ileum or colon, but is profoundly upregulated in multiple IBD subtypes including: adult and pediatric Crohn's disease (CD), adult and pediatric ulcerative colitis (UC), and UC pouchitis. Encouragingly, small molecule GCPII inhibitors display promising efficacy in chemical and genetic preclinical colitis models. In this chapter we will: (1) review GCPII biology, (2) present the data confirming its upregulation in IBD patients at gene and protein levels, (3) discuss foundational pre-clinical studies that established the anti-colitis efficacy of small molecule GCPII inhibitors, and (4) introduce the rationale and development of a novel class of GCPII inhibitors, including lead compound (S)-IBD3540, which hold therapeutic promise for IBD.

Pouchitis: pathophysiology and management

Pouchitis is an acute or chronic inflammatory disease of the ileal reservoir. It is common after restorative proctocolectomy with ileal pouch-anal anastomosis, and treatment of chronic antibiotic-refractory pouchitis has proven challenging. Most cases of acute pouchitis evolve into chronic pouchitis. The aetiology of acute pouchitis is likely to be partly related to the gut microbiota, whereas the pathophysiology of chronic pouchitis involves abnormal interactions between genetic disposition, faecal stasis, the gut microbiota, dysregulated host immunity, surgical techniques, ischaemia and mesentery-related factors. Pouchoscopy with biopsy is the most valuable modality for diagnosis, disease monitoring, assessment of treatment response, dysplasia surveillance and delivery of endoscopic therapy. Triggering or risk factors, such as Clostridioides difficile infection and use of non-steroidal anti-inflammatory drugs, should be modified or eradicated. In terms of treatment, acute pouchitis usually responds to oral antibiotics, whereas chronic antibiotic-refractory pouchitis often requires induction and maintenance therapy with integrin, interleukin or tumour necrosis factor inhibitors. Chronic pouchitis with ischaemic features, fistulae or abscesses can be treated with hyperbaric oxygen therapy.

Identifying Macrophage-Related Genes in Ulcerative Colitis Using Weighted Coexpression Network Analysis and Machine Learning

Ulcerative colitis (UC) is an inflammatory bowel disease of unknown cause that typically affects the colon and rectum. Innate intestinal immunity, including macrophages, plays a significant role in the pathological development of UC. Using the CIBERSORT algorithm, we observed elevated levels of 22 types of immune cell infiltrates, as well as increased M1 and decreased M2 macrophages in UC compared to normal colonic mucosa. Weighted gene coexpression network analysis (WGCNA) was used to identify modules associated with macrophages and UC, resulting in the identification of 52 macrophage-related genes (MRGs) that were enriched in macrophages at single-cell resolution. Consensus clustering based on these 52 MRGs divided the integrated UC cohorts into three subtypes. Machine learning algorithms were used to identify ectonucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1), sodium- and chloride-dependent neutral and basic amino acid transporter B(0+) (SLC6A14), and 3-hydroxy-3-methylglutaryl-CoA synthase 2 (HMGCS2) in the training set, and their diagnostic value was validated in independent validation sets. Gene set enrichment analysis (GSEA) and gene set variation analysis (GSVA) revealed the main biological effects, and that interleukin-17 was one of several signaling pathways enriched by the three genes. We also constructed a competitive endogenous RNA (CeRNA) network reflecting a potential posttranscriptional regulatory mechanism. Expression of diagnostic markers was validated in vivo and in biospecimens, and our immunohistochemistry (IHC) results confirmed that HMGCS2 gradually decreased during the transformation of UC to colorectal cancer. In conclusion, ENPP1, SLC6A14, and HMGCS2 are associated with macrophages and the progression of UC pathogenesis and have good diagnostic value for patients with UC.

A gut-restricted glutamate carboxypeptidase II inhibitor reduces monocytic inflammation and improves preclinical colitis

There is an urgent need to develop therapeutics for inflammatory bowel disease (IBD) because up to 40% of patients with moderate-to-severe IBD are not adequately controlled with existing drugs. Glutamate carboxypeptidase II (GCPII) has emerged as a promising therapeutic target. This enzyme is minimally expressed in normal ileum and colon, but it is markedly up-regulated in biopsies from patients with IBD and preclinical colitis models. Here, we generated a class of GCPII inhibitors designed to be gut-restricted for oral administration, and we interrogated efficacy and mechanism using in vitro and in vivo models. The lead inhibitor, (S)-IBD3540, was potent (half maximal inhibitory concentration = 4 nanomolar), selective, gut-restricted (AUCcolon/plasma > 50 in mice with colitis), and efficacious in acute and chronic rodent colitis models. In dextran sulfate sodium-induced colitis, oral (S)-IBD3540 inhibited >75% of colon GCPII activity, dose-dependently improved gross and histologic disease, and markedly attenuated monocytic inflammation. In spontaneous colitis in interleukin-10 (IL-10) knockout mice, once-daily oral (S)-IBD3540 initiated after disease onset improved disease, normalized colon histology, and attenuated inflammation as evidenced by reduced fecal lipocalin 2 and colon pro-inflammatory cytokines/chemokines, including tumor necrosis factor-α and IL-17. Using primary human colon epithelial air-liquid interface monolayers to interrogate the mechanism, we further found that (S)-IBD3540 protected against submersion-induced oxidative stress injury by decreasing barrier permeability, normalizing tight junction protein expression, and reducing procaspase-3 activation. Together, this work demonstrated that local inhibition of dysregulated gastrointestinal GCPII using the gut-restricted, orally active, small-molecule (S)-IBD3540 is a promising approach for IBD treatment.

Medical management of chronic pouch inflammation

Image 1.

Early Pouchitis Is Associated With Crohn's Disease-like Pouch Inflammation in Patients With Ulcerative Colitis

BACKGROUND

Despite the initial diagnosis of ulcerative colitis (UC), approximately 10% to 20% of patients develop Crohn's disease-like pouch inflammation (CDLPI) after restorative proctocolectomy (RPC) with ileal pouch anal anastomosis (IPAA). The aim of this study was to evaluate whether early pouchitis, defined as pouchitis within the first year after IPAA, is a predictor of CDLPI.

METHODS

This was a retrospective cohort analysis of patients with UC or IBD unclassified (IBDU) who underwent RPC with IPAA at Mount Sinai Hospital between January 2008 and December 2017. The primary outcome was development of CDLPI. Predictors of CDLPI were analyzed via univariable and multivariable Cox regression models.

RESULTS

The analytic cohort comprised 412 patients who underwent at least 1 pouchoscopy procedure between 2009 and 2018. Crohn's disease-like pouch inflammation developed in 57 (13.8%) patients a median interval of 2.1 (interquartile range, 1.1-4.3) years after surgery. On univariable analysis, older age at colectomy (hazard ratio [HR], 0.97; 95% CI, 0.95-0.99) was associated with a reduced risk of CDLPI; although early pouchitis (HR, 2.43; 95% CI, 1.32-4.45) and a greater number of pouchitis episodes (HR, 1.38; 95% CI, 1.17-1.63) were associated with an increased risk. On multivariable analysis, early pouchitis (HR, 2.35; 95% CI, 1.27-4.34) was significantly associated with CDLPI. Time to CDLPI was significantly less in patients who developed early pouchitis compared with those who did not (P = .003).

CONCLUSION

Early pouchitis is significantly associated with subsequent CDLPI development and may be the first indication of enhanced mucosal immune activation in the pouch.

Multiple 'omics'-analysis reveals the role of prostaglandin E2 in Hirschsprung's disease

The etiology and pathogenesis of Hirschsprung's disease (HSCR) remain largely unknown. We examined colon tissues from three independent populations with a combined analysis of metabolomics, transcriptomics and proteomics to understand HSCR pathogenesis, according to which mouse model was used to examine prostaglandin E2 (PGE2) induced clinical presentation of HSCR. SH-SY5Y and SK-N-BE(2) cell lines were studied for PGE2 inhibited cell migration through EP2. Our integrated multiple 'omics'-analysis suggests that the levels of PGE2, the expression of the gene encoding PGE2 receptor (EP2), and PGE2 synthesis enzyme genes (PTGS1 and PTGES) increased in HSCR colon tissues, together with a decreased synthesis of PGE2-related byproducts. In vivo, the pregnant mice treated with PGE2 gave birth to offspring with the decrease of ganglion cells in their colon and gut function. In in vitro study, when EP2 was blocked, the PGE2-inhibited cell migration was recovered. Our study identified a novel pathway highlighting the link between expression of PTGS1 and PTGES, levels of PGE2, expression of PTGER2, and neural crest cell migration in HSCR, providing a novel strategy for future diagnosis and prevention of HSCR.

Transport of L-Arginine Related Cardiovascular Risk Markers

L-arginine and its derivatives, asymmetric and symmetric dimethylarginine (ADMA and SDMA) and L-homoarginine, have emerged as cardiovascular biomarkers linked to cardiovascular outcomes and various metabolic and functional pathways such as NO-mediated endothelial function. Cellular uptake and efflux of L-arginine and its derivatives are facilitated by transport proteins. In this respect the cationic amino acid transporters CAT1 and CAT2 (SLC7A1 and SLC7A2) and the system y⁺L amino acid transporters (SLC7A6 and SLC7A7) have been most extensively investigated, so far, but the number of transporters shown to mediate the transport of L-arginine and its derivatives is constantly increasing. In the present review we assess the growing body of evidence regarding the function, expression, and clinical relevance of these transporters and their possible relation to cardiovascular diseases.

Role of the microbiota in ileitis of a mouse model of inflammatory bowel disease-Glutathione peroxide isoenzymes 1 and 2-double knockout mice on a C57BL background

C57Bl6 (B6) mice devoid of glutathione peroxidases 1 and 2 (Gpx1/2-DKO) develop ileitis after weaning. We previously showed germ-free Gpx1/2-DKO mice of mixed B6.129 background did not develop ileocolitis. Here, we examine the composition of the ileitis provoking microbiota in B6 Gpx1/2-DKO mice. DNA was isolated from the ileum fecal stream and subjected to high-throughput sequencing of the V3 and V4 regions of the 16S rRNA gene to determine the abundance of operational taxonomic units (OTUs). We analyzed the role of bacteria by comparing the microbiomes of the DKO and pathology-free non-DKO mice. Mice were treated with metronidazole, streptomycin, and vancomycin to alter pathology and correlate the OTU abundances with pathology levels. Principal component analysis based on Jaccard distance of abundance showed 3 distinct outcomes relative to the source Gpx1/2-DKO microbiome. Association analyses of pathology and abundance of OTUs served to rule out 7-11 of 24 OTUs for involvement in the ileitis. Collections of OTUs were identified that appeared to be linked to ileitis in this animal model and would be classified as commensals. In Gpx1/2-DKO mice, host oxidant generation from NOX1 and DUOX2 in response to commensals may compromise the ileum epithelial barrier, a role generally ascribed to oxidants generated from mitochondria, NOX2 and endoplasmic reticulum stress in response to presumptive pathogens in IBD. Elevated oxidant levels may contribute to epithelial cell shedding, which is strongly associated with progress toward inflammation in Gpx1/2-DKO mice and predictive of relapse in IBD by allowing leakage of microbial components into the submucosa.

Update on SLC6A14 in lung and gastrointestinal physiology and physiopathology: focus on cystic fibrosis

The solute carrier family 6 member 14 (SLC6A14) protein imports and concentrates all neutral amino acids as well as the two cationic acids lysine and arginine into the cytoplasm of different cell types. Primarily described as involved in several cancer and colonic diseases physiopathological mechanisms, the SLC6A14 gene has been more recently identified as a genetic modifier of cystic fibrosis (CF) disease severity. It was indeed shown to have a pleiotropic effect, modulating meconium ileus occurrence, lung disease severity, and precocity of P. aeruginosa airway infection. The biological mechanisms explaining the impact of SLC6A14 on intestinal and lung phenotypes of CF patients are starting to be elucidated. This review focuses on SLC6A14 in lung and gastrointestinal physiology and physiopathology, especially its involvement in the pathophysiology of CF disease.

Symbioflor2® Escherichia coli Genotypes Enhance Ileal and Colonic Gene Expression Associated with Mucosal Defense in Gnotobiotic Mice

Symbioflor2^® is a probiotic product composed of six Escherichia coli genotypes, which has a beneficial effect on irritable bowel syndrome. Our objective was to understand the individual impact of each of the six genotypes on the host, together with the combined impact of the six in the compound Symbioflor2^®. Gnotobiotic mice were mono-associated with one of the six genotypes or associated with the compound product. Ileal and colonic gene expression profiling was carried out, and data were compared between the different groups of gnotobiotic mice, along with that obtained from conventional (CV) mice and mice colonized with the probiotic E. coli Nissle 1917. We show that Symbioflor2^® genotypes induce intestinal transcriptional responses involved in defense and immune mechanisms. Using mice associated with Symbioflor2^®, we reveal that the product elicits a balanced response from the host without any predominance of a single genotype. The Nissle strain and the six bacterial genotypes have different effects on the intestinal gene expression, suggesting that the impacts of these probiotics are not redundant. Our data show the effect of the Symbioflor2^® genotypes at the molecular level in the digestive tract, which further highlights their beneficial action on several aspects of intestinal physiology.

Genotype-Serotype Interactions Shed Light on Genetic Components of Inflammatory Bowel Diseases

BACKGROUND

We evaluated the impact of variations in ATG16L1 and NOD2 and genes on serologic responses in patients with inflammatory bowel disease (IBD).

METHODS

We recruited 308 IBD patients: 130 with Crohn's disease (CD), 67 with ulcerative colitis (UC), 111 with UC and an ileal pouch (UC-pouch), and 74 healthy controls. NOD2 variants (1007fs, G908R, R702W) and the ATG16L1 A300T variant were analyzed. The antiglycan antibodies anti-Saccharomyces cerevisiae (ASCA), antilaminaribioside (ALCA), antichitobioside (ACCA), and antimannobioside carbohydrate (AMCA) were analyzed by enzyme-linked immunosorbent assay.

RESULTS

Antichitobioside was positive in 28% of patients with CD carrying the ATG16L1 A300T variant (either heterozygote or homozygote) compared with only 3% in those without the variant (P < 0.001). Anti-Saccharomyces cerevisiae was positive in 86% of patients with CD carrying the NOD2 1007fs variant compared with 36% in those without the variant (P < 0.001). UC-pouch patients with the NOD2 1007fs variant had elevated ASCA and ALCA levels compared with those without the variant (50% vs 7%, P = 0.004, and 50% vs 8%, P = 0.006, respectively). Importantly, ATG16L1 A300T and NOD2 variants were not associated with serologic responses in healthy controls and unoperated UC patients. Multivariate analysis demonstrated that these genetic variants are the main factors associated with specific antiglycan antibody levels in CD and pouch patients.

CONCLUSIONS

Genetic variants may have disease-specific phenotypic (serotypic) effects. This implies that genetic risk factors may also be disease modifiers.

Increase in Processing Factors Is Involved in Skewed MicroRNA Expression in Patients with Ulcerative Colitis Who Develop Small Intestine Inflammation after Pouch Surgery

BACKGROUND

A large-scale increase in microRNA (miRNA) expression was observed in patients with ulcerative colitis who underwent pouch surgery and developed inflammation of the pouch (pouchitis). In this study, we assessed miRNA expression in these patients and investigated how regulation of its expression changes in the setting of pouchitis.

METHODS

Autologous samples that included mucosal biopsies, peripheral blood cells, and plasma were collected from the patients. Candidate primary and mature miRNA expressions were analyzed by quantitative polymerase chain reaction. A human intestinal epithelial cell line was used to test DICER activity, and the expression of key miRNA processing factors was analyzed by Western blot. miRNA-424 and its potential target serotonin reuptake transporter (SERT) expressions were examined by quantitative reverse transcription polymerase chain reaction and Western blot in human pouch tissues and in a human intestinal epithelial cell line stimulated with inflammatory cytokines TNF-α, IL-1β, and INF-γ.

RESULTS

Candidate miRNA expression and protein expression of DICER-1, EXPORTIN-5, and AGO-2 were increased in association with pouch inflammation. Similarly, inflammatory cytokines increased protein expression of DICER-1, EXPORTIN-5, and AGO-2 and DICER activity in the epithelial cell line. The miRNA-424 expression increased whereas SERT expression decreased in the patients' mucosa. Similarly, incubation of the epithelial cell line with inflammatory cytokines resulted in increased miRNA-424 and decreased SERT mRNA and protein expression.

CONCLUSIONS

The miRNA expression and processing are augmented in the inflamed intestinal mucosa of patients with pouchitis. These alterations are accompanied by increased expression of proteins involved in miRNA processing, suggesting that pouch inflammation contributes to miRNA processing and expression.

The outcome of ulcerative colitis patients undergoing pouch surgery is determined by pre-surgical factors

BACKGROUND

Pouch surgery, a common intervention for ulcerative colitis (UC) complications, is often associated with the development of pouchitis.

AIM

To identify predictors of pouch outcome in a cohort of patients with UC.

METHODS

We conducted a retrospective unmatched case-cohort study in a tertiary IBD referral centre. Adult patients with UC were classified into the worst phenotype throughout follow-up: normal pouch, a form of chronic pouchitis (either chronic pouchitis or Crohn's like disease of pouch [CLDP]), or episodic recurrent acute pouchitis (RAP). Risk factors for pouchitis (chronic forms) were detected using statistical models.

RESULTS

Two hundred and fifty-three pouch patients were followed up for 13.1±7.3 years. Only 71 patients (28.1%) maintained a favourable outcome of a sustained normal pouch. These patients were older at UC diagnosis (27.8±12.5 vs 23.0±11.4 years), had longer UC duration until surgery (13.4±9.5 vs 8.2±7.9 years), and had higher rates of referral to surgery due to nonrefractory (dysplasia/neoplasia) complications (42.3% vs 16.2%) compared with pouchitis patients. Median survival for sustained normal pouch was 10.8 years (95% CI 8.9-12.7 years), and it was longer in the nonrefractory group (20.3 vs 9.4 years for the refractory group, HR=2.37, 95% CI 1.25-3.52, P=.004).

CONCLUSIONS

Most patients with UC undergoing pouch surgery will develop pouchitis. Patients operated for nonrefractory indications have a more favourable outcome. These results may contribute to pre- and post-surgical decision-making. The findings imply that the processes determining UC severity may be similar to that causing pouchitis.

MicroRNAs Expression in the Ileal Pouch of Patients with Ulcerative Colitis Is Robustly Up-Regulated and Correlates with Disease Phenotypes

Background

Gene expression alterations are associated with disease behavior in inflammatory bowel disease (IBD). microRNAs (miRNAs) are dominant in the regulation of gene expression, and may affect IBD phenotype. Our aim was to assess mucosal miRNA expression in IBD and the correlation with intestinal inflammation.

Methods

We performed a large-scale analysis of ileal mucosal miRNA. Biopsies were retrieved from patients with ileal Crohn’s disease (CD), unoperated ulcerative colitis (UC) patients, UC patients after pouch surgery, and normal controls (NC). Pouch UC patients were classified as having a normal pouch (NP), chronic pouchitis (CP), and Crohn’s-like disease of the pouch (CLDP). miRNA expression was analyzed by parallel massive (next-generation) sequencing (NGS). Bioinformatics tools were applied for clustering and the detection of potential targets.

Results

Sixty-one subjects were recruited. The ileum of unoperated UC patients was comparable with NC. There were significant miRNA expression alterations (fold change ≥2, corrected P ≤.05) in NP (n = 6), CP (n = 40) and CLDP (n = 139), but only two expression alterations were noted in CD. More than 90% of the altered miRNAs were up-regulated, and many were predicted to be associated with significantly decreased transcripts. miRNAs alterations were generally clustered with disease phenotypes.

Conclusions

Ileal inflammation causes increased miRNA expression. miRNA alterations correlate with IBD phenotype, apparently by controlling the down-regulation of specific mRNAs.

Gene expression alterations in inflamed and unaffected colon mucosa from patients with mild inflammatory bowel disease

An endoscopic examination is currently the most reliable method for monitoring disease activity in patients with inflammatory bowel disease (IBD). However, endoscopic evaluations are unable to detect mucosal inflammation at the earliest stages. The present study aimed to evaluate the molecular profiles of inflamed and unaffected colon mucosa from patients with mild Crohn's disease (CD) and ulcerative colitis (UC), in order to identify a more sensitive method for monitoring mucosal impairment. Patients were recruited and colon biopsies from the inflamed and the normal‑appearing mucosa of patients with mild IBD were obtained by colonoscopy. Gene expression analysis was performed using microarrays, after which Gene Ontology and clustering were performed using bioinformatics. In addition, the levels of inflammatory cytokines were analyzed by reverse transcription‑quantitative polymerase chain reaction. A total of 620 genes in the inflamed and 210 genes in the unaffected colon mucosa with at least a 3‑fold change, as compared with healthy controls, were detected in patients with mild CD, and 339 genes in the inflamed and 483 genes in the unaffected colon mucosa were detected in patients with mild UC. Heat mapping demonstrated a similarity in the gene alteration patterns, and altered transcripts overlapped, between the inflamed and unaffected colon mucosa. Interferon‑γ and interleukin‑17 mRNA levels were comparably elevated in the inflamed and unaffected colon mucosa from patients with IBD. Marked gene expression alterations were detected in the inflamed and unaffected colon mucosa from patients with mild IBD, and these showed marked similarity and overlap between the two groups. The results of the present study suggested that inflammation was not limited to the endoscopic lesions and that gene expression profiling may be considered a sensitive tool for monitoring mucosal inflammation, predicting relapses and optimizing therapeutic strategies for patients with IBD.

Glutamine transporters in mammalian cells and their functions in physiology and cancer

The SLC (solute carrier)-type transporters (~400 in number) in mammalian cells consist of 52 distinct gene families, grouped solely based on the amino acid sequence (primary structure) of the transporter proteins and not on their transport function. Among them are the transporters for amino acids. Fourteen of them, capable of transporting glutamine across the plasma membrane, are found in four families: SLC1, SLC6, SLC7, and SLC38. However, it is generally thought that the members of the SLC38 family are the principal transporters for glutamine. Some of the glutamine transporters are obligatory exchangers whereas some function as active transporters in one direction. While most glutamine transporters mediate the influx of the amino acid into cells, some actually mediate the efflux of the amino acid out of the cells. Glutamine transporters play important roles in a variety of tissues, including the liver, brain, kidney, and placenta, as clearly evident from the biological and biochemical phenotypes resulting from the deletion of specific glutamine transporters in mice. Owing to the obligatory role of glutamine in growth and proliferation of tumor cells, there is increasing attention on glutamine transporters in cancer biology as potential drug targets for cancer treatment. Selective blockers of certain glutamine transporters might be effective in preventing the entry of glutamine and other important amino acids into tumor cells, thus essentially starving these cells to death. This could represent the beginning of a new era in the discovery of novel anticancer drugs with a previously unexplored mode of action. This article is part of a Special Issue entitled: Mitochondrial Channels edited by Pierre Sonveaux, Pierre Maechler and Jean-Claude Martinou.

Increased Expression of DUOX2 Is an Epithelial Response to Mucosal Dysbiosis Required for Immune Homeostasis in Mouse Intestine

BACKGROUND & AIMS

Dual oxidase 2 (DUOX2), a hydrogen-peroxide generator at the apical membrane of gastrointestinal epithelia, is up-regulated in patients with inflammatory bowel disease (IBD) before the onset of inflammation, but little is known about its effects. We investigated the role of DUOX2 in maintaining mucosal immune homeostasis in mice.

METHODS

We analyzed the regulation of DUOX2 in intestinal tissues of germ-free vs conventional mice, mice given antibiotics or colonized with only segmented filamentous bacteria, mice associated with human microbiota, and mice with deficiencies in interleukin (IL) 23 and IL22 signaling. We performed 16S ribosomal RNA gene quantitative polymerase chain reaction of intestinal mucosa and mesenteric lymph nodes of Duoxa(-/-) mice that lack functional DUOX enzymes. Genes differentially expressed in Duoxa(-/-) mice compared with co-housed wild-type littermates were correlated with gene expression changes in early-stage IBD using gene set enrichment analysis.

RESULTS

Colonization of mice with segmented filamentous bacteria up-regulated intestinal expression of DUOX2. DUOX2 regulated redox signaling within mucosa-associated microbes and restricted bacterial access to lymphatic tissues of the mice, thereby reducing microbiota-induced immune responses. Induction of Duox2 transcription by microbial colonization did not require the mucosal cytokines IL17 or IL22, although IL22 increased expression of Duox2. Dysbiotic, but not healthy human microbiota, activated a DUOX2 response in recipient germ-free mice that corresponded to abnormal colonization of the mucosa with distinct populations of microbes. In Duoxa(-/-) mice, abnormalities in ileal mucosal gene expression at homeostasis recapitulated those in patients with mucosal dysbiosis.

CONCLUSIONS

DUOX2 regulates interactions between the intestinal microbiota and the mucosa to maintain immune homeostasis in mice. Mucosal dysbiosis leads to increased expression of DUOX2, which might be a marker of perturbed mucosal homeostasis in patients with early-stage IBD.

Use of Biologics in Pouchitis: A Systematic Review

Data about the effectiveness of biologics, including anti-tumor necrosis factor (TNF) therapy and anti-integrin strategies, in antibiotic refractory pouchitis or Crohn's disease-associated pouch complications are sparse. We performed a systematic review of the literature in Medline and Web of Science. All English language publications and meeting abstracts describing patients with pouchitis treated with anti-TNF or anti-integrin therapies were included. We identified a total of 17 papers and 2 abstracts, most of these retrospective case series, including a total of 192 patients treated either with infliximab (n=140) or adalimumab (n=52). No reports were found for anti-integrin therapies or other anti-TNF agents such as certolizumab pegol or golimumab. Because of the heterogeneity of the studies, small numbers of patients, differing cotreatments, and subjective outcome definitions, the exact efficacy of these biological therapies cannot be assessed in a combined fashion. Overall infliximab appears to have good clinical effectiveness in selected patients achieving up to 80% short-term and around 50% long-term response, whereas the few data available for adalimumab are not sufficient to draw valid conclusions. Larger prospectively collected multicenter data with clearly defined inclusion criteria and outcomes are necessary to better define the clinical value of anti-TNF therapy in patients with antibiotic refractory pouchitis or Crohn's-like complications of the pouch.