Polymorphic KIR3DL3 expression modulates tissue-resident and innate-like T cells.

Most human killer cell immunoglobulin-like receptors (KIR) are expressed by natural killer (NK) cells and recognize HLA class I molecules as ligands. KIR3DL3 is a conserved but polymorphic inhibitory KIR recognizing a B7 family ligand, HHLA2, and is implicated for immune checkpoint targeting. The expression profile and biological function of KIR3DL3 have been somewhat elusive, so we searched extensively for KIR3DL3 transcripts, revealing highly enriched expression in γδ and CD8+ T cells rather than NK cells. These KIR3DL3-expressing cells are rare in the blood and thymus but more common in the lungs and digestive tract. High-resolution flow cytometry and single-cell transcriptomics showed that peripheral blood KIR3DL3+ T cells have an activated transitional memory phenotype and are hypofunctional. The T cell receptor (TCR) usage is biased toward genes from early rearranged TCR-α variable segments or Vδ1 chains. In addition, we show that TCR-mediated stimulation can be inhibited through KIR3DL3 ligation. Whereas we detected no impact of KIR3DL3 polymorphism on ligand binding, variants in the proximal promoter and at residue 86 can reduce expression. Together, we demonstrate that KIR3DL3 is up-regulated alongside unconventional T cell stimulation and that individuals may vary in their ability to express KIR3DL3. These results have implications for the personalized targeting of KIR3DL3/HHLA2 checkpoint inhibition.

Prospective Cohort Study to Investigate the Safety of Preoperative Tumor Necrosis Factor Inhibitor Exposure in Patients With Inflammatory Bowel Disease Undergoing Intra-abdominal Surgery.

BACKGROUND & AIMS: Whether preoperative treatment of inflammatory bowel disease (IBD) with tumor necrosis factor inhibitors (TNFis) increases the risk of postoperative infectious complications remains controversial. The primary aim of this study was to determine whether preoperative exposure to TNFis is an independent risk factor for postoperative infectious complications within 30 days of surgery. METHODS: We conducted a multicenter prospective observational study of patients with IBD undergoing intra-abdominal surgery across 17 sites from the Crohn's & Colitis Foundation Clinical Research Alliance. Infectious complications were categorized as surgical site infections (SSIs) or non-SSIs. Current TNFi exposure was defined as use within 12 weeks of surgery, and serum was collected for drug-level analyses. Multivariable models for occurrence of the primary outcome, any infection, or SSI were adjusted by predefined covariates (age, sex, preoperative steroid use, and disease type), baseline variables significantly associated (P < .05) with any infection or SSI separately, and TNFi exposure status. Exploratory models used TNFi exposure based on serum drug concentration. RESULTS: A total of 947 patients were enrolled from September 2014 through June 2017. Current TNFi exposure was reported by 382 patients. Any infection (18.1% vs 20.2%, P = .469) and SSI (12.0% vs 12.6%, P = .889) rates were similar in patients currently exposed to TNFis and those unexposed. In multivariable analysis, current TNFi exposure was not associated with any infection (odds ratio, 1.050; 95% confidence interval, 0.716-1.535) or SSI (odds ratio, 1.249; 95% confidence interval, 0.793-1.960). Detectable TNFi drug concentration was not associated with any infection or SSI. CONCLUSIONS: Preoperative TNFi exposure was not associated with postoperative infectious complications in a large prospective multicenter cohort.

A Novel Approach toward Less Invasive Multiomics Gut Analyses: a Pilot Study.

Newer 'omics approaches, such as metatranscriptomics and metabolomics, allow functional assessments of the interaction(s) between the gut microbiome and the human host. However, in order to generate meaningful data with these approaches, the method of sample collection is critical. Prior studies have relied on expensive and invasive means toward sample acquisition, such as intestinal biopsy, while other studies have relied on easier methods of collection, such as fecal samples that do not necessarily represent those microbes in contact with the host. In this pilot study, we attempt to characterize a novel, minimally invasive method toward sampling the human microbiome using mucosal cytology brush sampling compared to intestinal gut biopsy samples on 5 healthy participants undergoing routine screening colonoscopy. We compared metatranscriptomic analyses between the two collection methods and identified increased taxonomic evenness and beta diversity in the cytology brush samples and similar community transcriptional profiles between the two methods. Metabolomics assessment demonstrated striking differences between the two methods, implying a difference in bacterial-derived versus human-absorbed metabolites. Put together, this study supports the use of microbiome sampling with cytology brushes, but caution must be exercised when performing metabolomics assessment, as this represents differential metabolite production but not absorption by the host. IMPORTANCE In order to generate meaningful metabolomic and microbiome data, the method of sample collection is critical. This study utilizes and compares two methods for intestinal tissue collection for evaluation of metabolites and microbiomes, finding that using a brush to sample the microbiome provides valuable data. However, for metabolomics assessment, biopsy samples may still be required.

Delays Related to Prior Authorization in Inflammatory Bowel Disease.

BACKGROUND: Delays in advancing to biologic therapies are associated with adverse outcomes in inflammatory bowel disease (IBD). Insurer-mandated prior authorizations have been linked to prolonged medication initiation times. We hypothesized that prior authorizations are associated with prolonged biologic initiation time and increased IBD-related healthcare utilization among children with IBD. METHODS: We performed a retrospective cohort study of 190 pediatric patients with IBD initiating biologics at a tertiary care hospital to measure the association between prior authorization, biologic initiation time (physician recommendation to first dose), and healthcare utilization (hospitalization, surgery, or emergency department visit). Demographic, insurance, and disease severity-related covariables were collected. Multivariable linear regression was used to measure the association between prior authorization and biologic initiation time. Propensity score methods were used to measure the associations between prior authorization and IBD-related healthcare utilization within 180 days and corticosteroid dependence at 90 days, with adjustment for insurance type, demographics, and disease severity-related characteristics. RESULTS: Median biologic initiation time was 21 days. Prior authorization and complicated prior authorizations (requiring appeal, step therapy, or peer-to-peer review) were associated with 10.2-day (95% confidence interval [CI] 8.2 to 12.3) and 24.6-day (95% CI 16.4 to 32.8) increases in biologic initiation time, respectively. Prior authorizations increased the likelihood of IBD-related healthcare utilization within 180 days by 12.9% (95% CI 2.5 to 23.4) and corticosteroid dependence at 90 days by 14.1% (95% CI 3.3 to 24.8). CONCLUSIONS: Prior authorizations are associated with prolonged biologic initiation time and increased IBD-related healthcare utilization. Minimizing prior authorization-related delays may expedite biologic delivery and reduce the risk of IBD-related healthcare utilization.

Mucosal acidosis elicits a unique molecular signature in epithelia and intestinal tissue mediated by GPR31-induced CREB phosphorylation.

Metabolic changes associated with tissue inflammation result in significant extracellular acidosis (EA). Within mucosal tissues, intestinal epithelial cells (IEC) have evolved adaptive strategies to cope with EA through the up-regulation of SLC26A3 to promote pH homeostasis. We hypothesized that EA significantly alters IEC gene expression as an adaptive mechanism to counteract inflammation. Using an unbiased RNA sequencing approach, we defined the impact of EA on IEC gene expression to define molecular mechanisms by which IEC respond to EA. This approach identified a unique gene signature enriched in cyclic AMP response element-binding protein (CREB)-regulated gene targets. Utilizing loss- and gain-of-function approaches in cultured epithelia and murine colonoids, we demonstrate that EA elicits prominent CREB phosphorylation through cyclic AMP-independent mechanisms that requires elements of the mitogen-activated protein kinase signaling pathway. Further analysis revealed that EA signals through the G protein-coupled receptor GPR31 to promote induction of FosB, NR4A1, and DUSP1. These studies were extended to an in vivo murine model in conjunction with colonization of a pH reporter Escherichia coli strain that demonstrated significant mucosal acidification in the TNFΔARE model of murine ileitis. Herein, we observed a strong correlation between the expression of acidosis-associated genes with bacterial reporter sfGFP intensity in the distal ileum. Finally, the expression of this unique EA-associated gene signature was increased during active inflammation in patients with Crohn's disease but not in the patient control samples. These findings establish a mechanism for EA-induced signals during inflammation-associated acidosis in both murine and human ileitis.

Circulating mature granzyme B+ T cells distinguish Crohn's disease-associated axial spondyloarthritis from axial spondyloarthritis and Crohn's disease.

BACKGROUND: Axial spondyloarthritis (axSpA) has strong connections with intestinal inflammation as occurs in Crohn's disease (CD). However, the immunologic mechanisms that distinguish axSpA, CD, and those with features of both diseases (CD-axSpA) are unknown. This study aimed to address this question by initial unbiased single cell RNA-sequencing (scRNAseq) on a pilot cohort followed by validating findings using flow cytometry and ELISA in a larger cohort. METHODS: Two individuals each with CD, axSpA, CD-axSpA, and healthy controls (HC) were recruited for a pilot discovery scRNAseq cohort, and the validation cohort consisted of 18 axSpA, 24 CD, 13 CD-axSpA, and 17 HC that was evaluated by flow cytometry on PBMCs and ELISAs for plasma cytokines. RESULTS: Uniquely, PBMCs from subjects with CD-axSpA demonstrated a significant increase in granzyme B+ T cells of both CD4+ and CD8+ lineages by both scRNAseq and flow cytometry. T cell maturation was also greater in those with CD-axSpA, particularly the CD4+ granzyme B+ population. Pathway analysis suggested increased interferon response genes in all immune cell populations within CD-axSpA. Although IFN-γ was elevated in the plasma of a subset of subjects with CD-axSpA, IL-6 was also significantly elevated. CONCLUSIONS: Our findings support the presence of a chronic interferonopathy in subjects with CD-axSpA characterized by interferon signaling by pathway analysis and an expansion of mature, cytotoxic T cells. These data indicate fundamental immunological differences between CD-axSpA and both of the putative "parent" conditions, suggesting that it is a distinct disease with unique natural history and treatment needs.

Multi 'Omics Analysis of Intestinal Tissue in Ankylosing Spondylitis Identifies Alterations in the Tryptophan Metabolism Pathway.

Intestinal microbial dysbiosis, intestinal inflammation, and Th17 immunity are all linked to the pathophysiology of spondyloarthritis (SpA); however, the mechanisms linking them remain unknown. One potential hypothesis suggests that the dysbiotic gut microbiome as a whole produces metabolites that influence human immune cells. To identify potential disease-relevant, microbiome-produced metabolites, we performed metabolomics screening and shotgun metagenomics on paired colon biopsies and fecal samples, respectively, from subjects with axial SpA (axSpA, N=21), Crohn's disease (CD, N=27), and Crohn's-axSpA overlap (CD-axSpA, N=12), as well as controls (HC, N=24). Using LC-MS based metabolomics of 4 non-inflamed pinch biopsies of the distal colon from subjects, we identified significant alterations in tryptophan pathway metabolites, including an expansion of indole-3-acetate (IAA) in axSpA and CD-axSpA compared to HC and CD and indole-3-acetaldehyde (I3Ald) in axSpA and CD-axSpA but not CD compared to HC, suggesting possible specificity to the development of axSpA. We then performed shotgun metagenomics of fecal samples to characterize gut microbial dysbiosis across these disease states. In spite of no significant differences in alpha-diversity among the 4 groups, our results confirmed differences in gene abundances of numerous enzymes involved in tryptophan metabolism. Specifically, gene abundance of indolepyruvate decarboxylase, which generates IAA and I3Ald, was significantly elevated in individuals with axSpA while gene abundances in HC demonstrated a propensity towards tryptophan synthesis. Such genetic changes were not observed in CD, again suggesting disease specificity for axSpA. Given the emerging role of tryptophan and its metabolites in immune function, altogether these data indicate that tryptophan metabolism into I3Ald and then IAA is one mechanism by which the gut microbiome potentially influences the development of axSpA.

Identification of the Most Effective Position for Ustekinumab in Treatment Algorithms for Crohn's Disease.

BACKGROUND & AIMS: Ustekinumab is a monoclonal antibody against interleukin 12 and interleukin 23 that has been approved by the Food and Drug Administration for treatment of Crohn's disease (CD). We sought to identify the ideal position for ustekinumab in treatment algorithms for CD. METHODS: We constructed a Markov model to identify an optimal treatment sequence for CD that included ustekinumab for 1 year or more. The base case was a 35-year old male with moderate to severe CD who had not previously received biologic or immunomodulator therapy. The standard of care treatment algorithm was defined as initial therapy with infliximab and azathioprine, followed by adalimumab and azathioprine, vedolizumab, and lastly surgical resection. The model assessed positions for ustekinumab before standard of care, ustekinumab after infliximab and azathioprine but before the remaining treatments, after infliximab, azathioprine, and adalimumab but before vedolizumab and surgery, or after the other biologics but before surgery. We derived transition probabilities and quality adjusted life years (QALYs) from relevant trials, observational studies, and time trade-off analyses. Primary analyses consisted of first order Monte Carlo simulation of 100 trials of cohorts of 100,000 individuals. RESULTS: Ustekinumab as first-line therapy yielded the greatest QALYs (incremental effectiveness, 0.016-0.020 QALYs), resulting in 10% more patients in remission or response, and 2% fewer surgeries at 1 year, compared with other algorithms. The model was not sensitive to 25% variation in transition probabilities. CONCLUSIONS: In a simulation based on a 35-year old male patient with moderate to severe CD, we found that ustekinumab as the first-line biologic therapy yields greater QALYs at the end of 1 year than compared with use later in the CD treatment algorithm.

Muc5ac Expression Protects the Colonic Barrier in Experimental Colitis.

BACKGROUND: The mucus gel layer (MGL) lining the colon is integral to exclusion of bacteria and maintaining intestinal homeostasis in health and disease. Some MGL defects allowing bacteria to directly contact the colonic surface are commonly observed in ulcerative colitis (UC). The major macromolecular component of the colonic MGL is the secreted gel-forming mucin MUC2, whose expression is essential for homeostasis in health. In UC, another gel-forming mucin, MUC5AC, is induced. In mice, Muc5ac is protective during intestinal helminth infection. Here we tested the expression and functional role of MUC5AC/Muc5ac in UC biopsies and murine colitis. METHODS: We measured MUC5AC/Muc5ac expression in UC biopsies and in dextran sulfate sodium (DSS) colitis. We performed DSS colitis in mice deficient in Muc5ac (Muc5ac-/-) to model the potential functional role of Muc5ac in colitis. To assess MGL integrity, we quantified bacterial-epithelial interaction and translocation to mesenteric lymph nodes. Antibiotic treatment and 16S rRNA gene sequencing were performed to directly investigate the role of bacteria in murine colitis. RESULTS: Colonic MUC5AC/Muc5ac mRNA expression increased significantly in active UC and murine colitis. Muc5ac-/- mice experienced worsened injury and inflammation in DSS colitis compared with control mice. This result was associated with increased bacterial-epithelial contact and translocation to the mesenteric lymph nodes. However, no change in microbial abundance or community composition was noted. Antibiotic treatment normalized colitis severity in Muc5ac-/- mice to that of antibiotic-treated control mice. CONCLUSIONS: MUC5AC/Muc5ac induction in the acutely inflamed colon controls injury by reducing bacterial breach of the MGL.

Creatine Transporter, Reduced in Colon Tissues From Patients With Inflammatory Bowel Diseases, Regulates Energy Balance in Intestinal Epithelial Cells, Epithelial Integrity, and Barrier Function.

BACKGROUND & AIMS: Patients with inflammatory bowel diseases (IBDs) have intestinal barrier dysfunction. Creatine regulates energy distribution within cells and reduces the severity of colitis in mice. We studied the functions of the creatine transporter solute carrier family 6 member 8 (SLC6A8, also called CRT) in intestinal epithelial cells (IECs) and mice, and we measured levels in mucosal biopsies from patients with IBD. METHODS: Colon biopsy specimens from patients with IBD (30 with Crohn's disease and 27 with ulcerative colitis) and 30 patients without IBD (control individuals) and colon tissues from mice (with and without disruption of Crt) were analyzed by immunofluorescence, immunoblots, and/or quantitative reverse-transcription polymerase chain reaction (qRT-PCR). CRT was knocked down or overexpressed in T84 cells, which were analyzed by immunofluorescence, immunoblots, high-performance liquid chromatography (to measure creatine levels), qRT-PCR, transepithelial electrical resistance, barrier function, actin localization, wound healing, mitochondrial oxygen consumption, and glycolysis extracellular acidification rate assays. Organoids from colon cells of CRT-knockout mice and control mice were analyzed by qRT-PCR, immunoblot, and transepithelial electrical resistance. RESULTS: CRT localized around tight junctions (TJs) of T84 IECs. In analyses of IECs with CRT knockdown or overexpression, we found that CRT regulates intracellular creatine, barrier formation, and wound healing. CRT-knockout organoids also had diminished barrier formation. In the absence of adequate creatine, IECs transition toward a stressed, glycolysis-predominant form of metabolism; this resulted in leaky TJs and mislocalization of actin and TJ proteins. Colon tissues from patients with IBD had reduced levels of CRT messenger RNA compared with those from control individuals. CONCLUSIONS: In an analysis of IEC cell lines and colonoids derived from CRT-knockout mice, we found that CRT regulates energy balance in IECs and thereby epithelial integrity and barrier function. Mucosal biopsy specimens from patients with ulcerative colitis and inactive Crohn's disease have lower levels of CRT, which might contribute to the reduced barrier function observed in patients with IBD.

Markers of Hypoxia Correlate with Histologic and Endoscopic Severity of Colitis in Inflammatory Bowel Disease.

BACKGROUND: Inflammation results in significant shifts in tissue metabolism. Recent studies indicate that inflammation and hypoxia occur concomitantly. We examined whether circulating and tissue markers of hypoxia could serve as surrogate indicators of disease severity in adult and pediatric patients with inflammatory bowel disease (IBD). METHODS: Serum and colonic biopsies were obtained from pediatric subjects with active IBD colitis and adult subjects with active and inactive ulcerative colitis, along with healthy non-colitis controls of all ages. Disease activity was evaluated by endoscopy and histopathology. Levels of serum hypoxia markers (macrophage inflammatory protein-3α [MIP-3α], vascular endothelial growth factor [VEGF], and erythropoietin [EPO]) were measured. RESULTS: Children with active IBD colitis had higher levels of serum MIP-3α and VEGF compared to non-colitis controls (p<0.01 and p<0.05, respectively). In adult subjects with endoscopically active ulcerative colitis, serum MIP-3α and EPO were significantly elevated compared to non-colitis controls (both p<0.01). In parallel, analysis of colon tissue MIP-3α mRNA and protein in pediatric subjects revealed increased expression in those with IBD colitis compared to controls (p<0.05 and p<0.01 for mRNA and protein, respectively). Serum MIP-3α and VEGF significantly increased with histology grade. CONCLUSION: Peripheral blood hypoxia markers may be useful indicators of disease activity for pediatric and adult IBD patients.

Identification of the Most Cost-effective Position of Vedolizumab Among the Available Biologic Drugs for the Treatment of Ulcerative Colitis.

BACKGROUND AND AIMS: There are limited data on the most cost-effective sequencing of biologics for ulcerative colitis [UC]. METHODS: We used Markov modelling to identify the most cost-effective position for vedolizumab among biologics for steroid-dependent UC, with a base-case of a 35-year-old male. We assessed three treatment algorithms, with vedolizumab use: prior to an initial anti-tumour necrosis factor alpha [anti-TNFα] and azathioprine [Algorithm 1]; prior to a second anti-TNF and azathioprine [Algorithm 2]; and prior to colectomy [Algorithm 3]. The initial anti-TNF could be either infliximab or adalimumab. Transition probabilities, costs, and quality-adjusted life-year estimates were derived from published estimates, Medicare, and the Nationwide Inpatient Sample. Primary analyses included 100 trials of 100 000 individuals over 1 year, with a willingness-to-pay threshold of US$100,000. Multiple sensitivity analyses were conducted to assess our findings. RESULTS: From a population perspective, when both infliximab and adalimumab are available, vedolizumab was preferred as the first biologic if ≥14% of initial anti-TNF use was adalimumab. If infliximab is the primary biologic, vedolizumab use after infliximab [Algorithm 2] and prior to adalimumab was the most cost-effective strategy. All models were sensitive to biologic pricing. CONCLUSIONS: This simulation demonstrated that the most cost-effective strategy in UC depends on the proportion of patients using adalimumab as the initial anti-TNF. If adalimumab was ≥14%, vedolizumab was preferred as the first biologic. When only infliximab was available for first-line therapy, the most cost-effective position of vedolizumab was prior to cycling to adalimumab.

Adaptation to inflammatory acidity through neutrophil-derived adenosine regulation of SLC26A3.

Acute intestinal inflammation includes the early accumulation of neutrophils (PMN). Based on recent evidence that PMN infiltration "imprints" changes in the local tissue environment through local oxygen depletion and the release of adenine nucleotides, we hypothesized that the interaction between transmigrating PMN and intestinal epithelial cells (IECs) results in inflammatory acidification of the tissue. Using newly developed tools, we revealed that active PMN transepithelial migration (TEM) significantly acidifies the local microenvironment, a decrease of nearly 2 pH units. Using unbiased approaches, we sought to define acid-adaptive pathways elicited by PMN TEM. Given the significant amount of adenosine (Ado) generated during PMN TEM, we profiled the influence of Ado on IECs gene expression by microarray and identified the induction of SLC26A3, the major apical Cl-/HCO3- exchanger in IECs. Utilizing loss- and gain-of-function approaches, as well as murine and human colonoids, we demonstrate that Ado-induced SLC26A3 promotes an adaptive IECs phenotype that buffers local pH during active inflammation. Extending these studies, chronic murine colitis models were used to demonstrate that SLC26A3 expression rebounds during chronic DSS-induced inflammation. In conclusion, Ado signaling during PMN TEM induces an adaptive tissue response to inflammatory acidification through the induction of SLC26A3 expression, thereby promoting pH homeostasis.

Microfluidics contrasted to thrombelastography: perplexities in defining hypercoagulability.

BACKGROUND: Elevated clot strength (maximum amplitude [MA]) measured by thrombelastography (TEG) is associated with thrombotic complications. However, it remains unclear how MA translates to thrombotic risks, as this measurement is independent of time, blood flow, and clot degradation. We hypothesize that under flow conditions, increased clot strength correlates to time-dependent measurements of coagulation and resistance to fibrinolysis. MATERIALS AND METHODS: Surgical patients at high risk of thrombotic complications were analyzed with TEG and total thrombus-formation analysis system (T-TAS). TEG hypercoagulability was defined as an r <10.2 min, angle >59, MA >66 or LY30 <0.2% (based off of healthy control data, n = 141). The T-TAS AR and PL chips were used to measure clotting at arterial shear rates. T-TAS measurements include occlusion start time, occlusion time (OT), occlusion speed (OSp), and total clot generation (area under the curve). These measurements were correlated to TEG indices (R time, angle, MA, and LY30). Both T-TAS and TEG assays were challenged with tissue plasminogen activator (t-PA) to assess clot resistance to fibrinolysis. RESULTS: Thirty subjects were analyzed, including five controls. TEG-defined hypercoagulability by MA was detected in 52% of the inflammatory bowel disease/cancer patients; 0% was detected in the controls. There were no TEG measurements that significantly correlated with T-TAS AR and PL chip. However, in the presence of t-PA, T-TAS AR determined OSp to have an inverse relationship with TEG angle (-0.477, P = 0.012) and LY30 (-0.449, P = 0.019), and a positive correlation with R time (0.441 P = 0.021). In hypercoagulability determined by TEG MA, T-TAS PL had a significantly reduced OT (4:07 versus 6:27 min, P = 0.043). In hypercoagulability defined by TEG LY30, T-TAS PL had discordant findings, with a significantly prolonged OT (6:36 versus 4:30 min, P = 0.044) and a slower OSp (10.5 versus 19.0 kPa/min, P = 0.030). CONCLUSIONS: Microfluidic coagulation assessment with T-TAS has an overall poor correlation with most TEG measurements in a predominantly hypercoagulable patient population, except in the presence of t-PA. The one anticipated finding was an elevated MA having a shorter time to platelet-mediated microfluidic occlusion, supporting the role of platelets and hypercoagulability. However, hypercoagulability defined by LY30 had opposing results in which a low LY30 was associated with a longer PL time to occlusion and slower OSp. These discordant findings warrant ongoing investigation into the relationship between clot strength and fibrinolysis under different flow conditions.

Functional intraepithelial lymphocyte changes in inflammatory bowel disease and spondyloarthritis have disease specific correlations with intestinal microbiota.

BACKGROUND: Dysbiosis occurs in spondyloarthritis (SpA) and inflammatory bowel disease (IBD), which is subdivided into Crohn's disease (CD) and ulcerative colitis (UC). The immunologic consequences of alterations in microbiota, however, have not been defined. Intraepithelial lymphocytes (IELs) are T cells within the intestinal epithelium that are in close contact with bacteria and are likely to be modulated by changes in microbiota. We examined differences in human gut-associated bacteria and tested correlation with functional changes in IELs in patients with axial SpA (axSpA), CD, or UC, and in controls. METHODS: We conducted a case-control study to evaluate IELs from pinch biopsies of grossly normal colonic tissue from subjects with biopsy-proven CD or UC, axSpA fulfilling Assessment of SpondyloArthritis International Society (ASAS) criteria and from controls during endoscopy. IELs were harvested and characterized by flow cytometry for cell surface markers. Secreted cytokines were measured by ELISA. Microbiome analysis was by 16S rRNA gene sequencing from rectal swabs. Statistical analyses were performed with the Kruskal-Wallis and Spearman's rank tests. RESULTS: The total number of IELs was significantly decreased in subjects with axSpA compared to those with IBD and controls, likely due to a decrease in TCRß+ IELs. We found strong, significant negative correlation between peripheral lymphocyte count and IEL number. IELs secreted significantly increased IL-1ß in patients with UC, significantly increased IL-17A and IFN-γ in patients with CD, and significantly increased TNF-α in patients with CD and axSpA as compared to other cohorts. For each disease subtype, IELs and IEL-produced cytokines were positively and negatively correlated with the relative abundance of multiple bacterial taxa. CONCLUSIONS: Our data indicate differences in IEL function among subjects with axSpA, CD, and UC compared to healthy controls. We propose that the observed correlation between altered microbiota and IEL function in these populations are relevant to the pathogenesis of axSpA and IBD, and discuss possible mechanisms. TRIAL REGISTRATION: ClinicalTrials.gov, NCT02389075 . Registered on 17 March 2015.

Microbiota-Derived Indole Metabolites Promote Human and Murine Intestinal Homeostasis through Regulation of Interleukin-10 Receptor.

Interactions between the gut microbiota and the host are important for health, where dysbiosis has emerged as a likely component of mucosal disease. The specific constituents of the microbiota that contribute to mucosal disease are not well defined. The authors sought to define microbial components that regulate homeostasis within the intestinal mucosa. Using an unbiased, metabolomic profiling approach, a selective depletion of indole and indole-derived metabolites was identified in murine and human colitis. Indole-3-propionic acid (IPA) was selectively diminished in circulating serum from human subjects with active colitis, and IPA served as a biomarker of disease remission. Administration of indole metabolites showed prominent induction of IL-10R1 on cultured intestinal epithelia that was explained by activation of the aryl hydrocarbon receptor. Colonization of germ-free mice with wild-type Escherichia coli, but not E. coli mutants unable to generate indole, induced colonic epithelial IL-10R1. Moreover, oral administration of IPA significantly ameliorated disease in a chemically induced murine colitis model. This work defines a novel role of indole metabolites in anti-inflammatory pathways mediated by epithelial IL-10 signaling and identifies possible avenues for utilizing indoles as novel therapeutics in mucosal disease.

Myeloid-derived miR-223 regulates intestinal inflammation via repression of the NLRP3 inflammasome.

MicroRNA (miRNA)-mediated RNA interference regulates many immune processes, but how miRNA circuits orchestrate aberrant intestinal inflammation during inflammatory bowel disease (IBD) is poorly defined. Here, we report that miR-223 limits intestinal inflammation by constraining the nlrp3 inflammasome. miR-223 was increased in intestinal biopsies from patients with active IBD and in preclinical models of intestinal inflammation. miR-223-/y mice presented with exacerbated myeloid-driven experimental colitis with heightened clinical, histopathological, and cytokine readouts. Mechanistically, enhanced NLRP3 inflammasome expression with elevated IL-1ß was a predominant feature during the initiation of colitis with miR-223 deficiency. Depletion of CCR2+ inflammatory monocytes and pharmacologic blockade of IL-1ß or NLRP3 abrogated this phenotype. Generation of a novel mouse line, with deletion of the miR-223 binding site in the NLRP3 3' untranslated region, phenocopied the characteristics of miR-223-/y mice. Finally, nanoparticle-mediated overexpression of miR-223 attenuated experimental colitis, NLRP3 levels, and IL-1ß release. Collectively, our data reveal a previously unappreciated role for miR-223 in regulating the innate immune response during intestinal inflammation.

Manipulation of the Endocannabinoid System in Colitis: A Comprehensive Review.

BACKGROUND: Inflammatory bowel disease (IBD) is a lifelong disease of the gastrointestinal tract whose annual incidence and prevalence is on the rise. Current immunosuppressive therapies available for treatment of IBD offer limited benefits and lose effectiveness, exposing a significant need for the development of novel therapies. In the clinical setting, cannabis has been shown to provide patients with IBD symptomatic relief, although the underlying mechanisms of their anti-inflammatory effects remain unclear. METHODS: This review reflects our current understanding of how targeting the endocannabinoid system, including cannabinoid receptors 1 and 2, endogenous cannabinoids anandamide and 2-arachidonoylglycerol, atypical cannabinoids, and degrading enzymes including fatty acid amide hydrolase and monoacylglycerol lipase, impacts murine colitis. In addition, the impact of cannabinoids on the human immune system is summarized. RESULTS: Cannabinoid receptors 1 and 2, endogenous cannabinoids, and atypical cannabinoids are upregulated in inflammation, and their presence and stimulation attenuate murine colitis, whereas cannabinoid receptor antagonism and cannabinoid receptor deficient models reverse these anti-inflammatory effects. In addition, inhibition of endocannabinoid degradation through monoacylglycerol lipase and fatty acid amide hydrolase blockade can also attenuate colitis development, and is closely linked to cannabinoid receptor expression. CONCLUSIONS: Although manipulation of the endocannabinoid system in murine colitis has proven to be largely beneficial in attenuating inflammation, there is a paucity of human study data. Further research is essential to clearly elucidate the specific mechanisms driving this anti-inflammatory effect for the development of therapeutics to target inflammatory disease such as IBD.

Fecal microbiota transplant in patients with Clostridium difficile infection: A systematic review.

BACKGROUND: Fecal microbiota transplantation (FMT) restores a diverse bacterial profile to the gastrointestinal tract and may effectively treat patients with Clostridium difficile infection (CDI). The objective of this systematic review was to evaluate the effectiveness of FMT in the treatment of CDI. METHODS: Ovid MEDLINE, EMBASE, Web of Science, and Cochrane database were used. The authors searched studies with 10 or more patients examining the resolution of symptoms after FMT in patients with CDI. Reviews, letters to the editors, and abstracts were excluded. Participants were patients with CDI. Intervention used was FMT. Quality assessment was performed using the Cochrane risk of bias assessment tool. Results were synthesized using a narrative approach. RESULTS: Retrospective and uncontrolled prospective cohort studies suggest that FMT is a highly effective therapy for recurrent/refractory CDI, with clinical success rates ranging from 83% to 100%, which is similar to rates published by two randomized controlled trials. Fecal microbiota transplantation may be effectively administered via antegrade (upper gastrointestinal) or retrograde (lower gastrointestinal) routes of delivery. Fecal microbiota transplantation rarely results in major adverse events. However, diarrhea, cramping, and bloating commonly occur and are typically self-limited. Most studies were uncontrolled retrospective studies. CONCLUSION: Fecal microbiota transplantation should be considered in patients with recurrent episodes of mild to moderate CDI who have failed conventional antimicrobial therapy. There is insufficient evidence to recommend FMT for the treatment of severe CDI. LEVEL OF EVIDENCE: Systematic review, level III.