Increased ACE2 Levels and Mortality Risk of Patients With COVID-19 on Proton Pump Inhibitor Therapy.

INTRODUCTION: Proton pump inhibitor (PPI) use was recently reported to be associated with increased severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and worse clinical outcomes. The underlying mechanism(s) for this association are unclear. METHODS: We performed a prospective study of hospitalized coronavirus disease 2019 (COVID-19) patients and COVID-negative controls to understand how PPI use may affect angiotensin-converting enzyme 2 (ACE2) expression and stool SARS-CoV-2 RNA. Analysis of a retrospective cohort of hospitalized patients with COVID-19 from March 15, 2020 to August 15, 2020 in 6 hospitals was performed to evaluate the association of PPI use and mortality. Covariates with clinical relevance to COVID-19 outcomes were included to determine predictors of in-hospital mortality. RESULTS: Control PPI users had higher salivary ACE2 mRNA levels than nonusers, 2.39 ± 1.15 vs 1.22 ± 0.92 (P = 0.02), respectively. Salivary ACE2 levels and stool SARS-CoV-2 RNA detection rates were comparable between users and nonusers of PPI. In 694 hospitalized patients with COVID-19 (age = 58 years, 46% men, and 65% black), mortality rate in PPI users and nonusers was 30% (68/227) vs 12.1% (53/439), respectively. Predictors of mortality by logistic regression were PPI use (adjusted odds ratio [aOR] = 2.72, P < 0.001), age (aOR = 1.66 per decade, P < 0.001), race (aOR = 3.03, P = 0.002), cancer (aOR = 2.22, P = 0.008), and diabetes (aOR = 1.95, P = 0.003). The PPI-associated mortality risk was higher in black patients (aOR = 4.16, 95% confidence interval: 2.28-7.59) than others (aOR = 1.62, 95% confidence interval: 0.82-3.19, P = 0.04 for interaction). DISCUSSION: COVID-negative PPI users had higher salivary ACE2 expression. PPI use was associated with increased mortality risk in patients with COVID-19, particularly African Americans.

Evidence of Duodenal Epithelial Barrier Impairment and Increased Pyroptosis in Patients With Functional Dyspepsia on Confocal Laser Endomicroscopy and "Ex Vivo" Mucosa Analysis.

INTRODUCTION: Duodenal epithelial barrier impairment and immune activation may play a role in the pathogenesis of functional dyspepsia (FD). This study was aimed to evaluate the duodenal epithelium of patients with FD and healthy individuals for detectable microscopic structural abnormalities. METHODS: This is a prospective study using esophagogastroduodenoscopy enhanced with duodenal confocal laser endomicroscopy (CLE) and mucosal biopsies in patients with FD (n = 16) and healthy controls (n = 18). Blinded CLE images analysis evaluated the density of epithelial gaps (cell extrusion zones), a validated endoscopic measure of the intestinal barrier status. Analyses of the biopsied duodenal mucosa included standard histology, quantification of mucosal immune cells/cytokines, and immunohistochemistry for inflammatory epithelial cell death called pyroptosis. Transepithelial electrical resistance (TEER) was measured using Ussing chambers. Epithelial cell-to-cell adhesion proteins expression was assessed by real-time polymerase chain reaction. RESULTS: Patients with FD had significantly higher epithelial gap density on CLE in the distal duodenum than that of controls (P = 0.002). These mucosal abnormalities corresponded to significant changes in the duodenal biopsy samples of patients with FD, compared with controls, including impaired mucosal integrity by TEER (P = 0.009) and increased number of epithelial cells undergoing pyroptosis (P = 0.04). Reduced TEER inversely correlated with the severity of certain dyspeptic symptoms. Furthermore, patients with FD demonstrated altered duodenal expression of claudin-1 and interleukin-6. No differences in standard histology were found between the groups. DISCUSSION: This is the first report of duodenal CLE abnormalities in patients with FD, corroborated by biopsy findings of epithelial barrier impairment and increased cell death, implicating that duodenal barrier disruption is a pathogenesis factor in FD and introducing CLE a potential diagnostic biomarker in FD.

Personalized Inflammatory Bowel Disease Care Reduced Hospitalizations.

BACKGROUND AND AIMS: IBD patients with inadequately treated disease often relapse and require hospitalizations for further management. The purpose of this practice review was to determine whether personalized IBD care improved patient outcomes as measured by IBD-related hospitalizations. METHODS: A dedicated IBD clinic was created for personalized patient care in a tertiary veterans health care center in 2014. In the first year, the care program consisted of patient-centered medical home (PCMH). In the second year, personalized biologic therapy was incorporated into the program, based on the severity of mucosal barrier dysfunction measured by probe-based confocal laser endomicroscopy (pCLE) analysis of the terminal ileum during colonoscopy. IBD-related hospitalizations during these 2 years were compared to the year before the care program. RESULTS: The IBD-related admissions at baseline, year 1 and 2 of the program were: total number of admissions of 25, 24, 8 (P = 0.03) per year, total number of hospital days of 177, 144, 31 days per year (P < 0.01), median length of stay 7, 4, and 2 days per visit (P = 0.013), respectively. Patients had significant increases in serum hemoglobin (11.5 ± 2.7, 11.9 ± 2.6, 14.0 ± 1.4 g/dl; P = 0.035), albumin (2.7 ± 0.7, 3.0 ± 0.6 g/dl 3.7 ± 0.8 g/dl; P = 0.031) and body mass index (26.6 ± 2.9, 28.1 ± 5.9; 34.0 ± 10.8; P = 0.047). CONCLUSIONS: Personalized IBD care incorporating a PCMH model and tailored biologic therapy based on pCLE findings of mucosal barrier dysfunction significantly reduced IBD-related hospitalizations.

Impact and outcomes of research sponsored by the American Society for Gastrointestinal Endoscopy.

BACKGROUND AND AIMS: Since 1985, the American Society for Gastrointestinal Endoscopy (ASGE) has awarded grants for endoscopic-related research. The goals of this study were to examine trends in ASGE grant funding and to assess productivity of previous recipients of the ASGE grant awards. METHODS: This was a retrospective cohort analysis of all research grants awarded by the ASGE through 2009. Measures of academic productivity and self-assessment of the ASGE awards' impact on the recipients' careers were defined by using publicly available resources (eg, National Library of Medicine-PubMed) and administration of an electronic survey to award recipients. RESULTS: The ASGE awarded 304 grants totaling $12.5 million to 214 unique awardees. Funding increased 7.5-fold between 1985 and 1989 (mean $102,000/year) and between 2005 and 2009 (mean $771,000/year). The majority of awardees were men (83%), were at or below the level of assistant professor (82%), with a median of 3 years of postfellowship experience at the time of the award, and derived from a broad spectrum of institutions as measured by National Institutes of Health funding rank (median 26, interquartile range [IQR] 12-64). Nineteen percent had a master's degree in a research-related field. Awardees' median publications per year increased from 3.5 (IQR 1.2-9.0) before funding to 5.7 (IQR 1.8-9.5) since funding; P = .04, and median h-index scores increased from 3 (IQR 1-8) to 17 (IQR 8-26); P < .001. Multivariate analysis found that the presence of a second advanced degree (eg, masters or doctorate) was independently predictive of high productivity (odds ratio [OR] 2.92; 95% confidence interval [CI], 1.09-7.81). Among 212 unique grant recipients, 82 (40%) completed the online survey. Of the respondents, median peer-reviewed publications per year increased from 3.4 (IQR 1.9-5.5) to 4.5 (IQR 2.0-9.5); P = .17. Ninety-one percent reported that the ASGE grant had a positive or very positive impact on their careers, and 85% of respondents are currently practicing in an academic environment. Most of the grants resulted in at least 1 peer-reviewed publication (67% per Internet-based search and 81% per survey). CONCLUSIONS: The ASGE research program has grown considerably since 1985, with the majority of grants resulting in at least 1 grant-related publication. Overall academic productivity increased after the award, and the majority of awardees report a positive or very positive impact of the award on their careers. Medical professional societies are an important sponsor of clinical research.

A Pilot Study of Confocal Laser Endomicroscopy to Predict Barrier Dysfunction and Relapse in Pediatric Inflammatory Bowel Disease.

OBJECTIVES: Probe-based confocal laser endomicroscopy (pCLE) is a novel imaging modality that enables virtual optical biopsy in vivo. Loss of barrier function of the small bowel observed via pCLE as increased density of epithelial gaps (extrusion zones left in the intestinal lining after cells are shed) is predictive of relapse in adult patients with inflammatory bowel disease (IBD). This study aims to determine whether such observations on pCLE are similarly predictive of disease relapse in pediatric patients with IBD. METHODS: Pediatric patients with biopsy-proven IBD underwent pCLE during colonoscopy and subsequent clinical follow-up every 6 months. Relapse was defined as moderate to severe flare with endoscopic evidence of inflammation during the follow-up period. The relations between epithelial gap density, disease relapse, and imaging parameters were determined using Cox models. RESULTS: Twenty-four patients with IBD (13 with Crohn disease, 11 with ulcerative colitis) with a median age of 14 years (range 10-21) were studied for a median of 13 (4-33) months. The median duration of disease was 2.9 years (range 0-9). Increased epithelial gap density in the terminal ileum on pCLE of normal endoscopic appearing terminal ileum mucosa (N = 19) was predictive of disease relapse when 3 or more areas were imaged (N = 6, log-rank P = 0.02, C-statistic = 0.94). CONCLUSIONS: In pediatric patients with IBD, barrier dysfunction observed on pCLE imaging of the small bowel was predictive of disease relapse.

Epithelial Cell Extrusion Zones Observed on Confocal Laser Endomicroscopy Correlates with Immunohistochemical Staining of Mucosal Biopsy Samples.

BACKGROUND AND AIMS: The density of epithelial cell extrusion zones in the intestinal lining, also known as gap density (number of gaps/1000 epithelial cells counted), can be quantitated using probe-based confocal laser endomicroscopy (pCLE). Gap density has been reported to be higher than normal in both inflammatory bowel disease (IBD) and irritable bowel syndrome (IBS) patients. Epithelial cells destined for extrusion from the intestinal surface would stain positive for either activated caspase-1 or caspase-3 on mucosal biopsy samples. The aim of this study was to determine whether epithelial gap density on pCLE correlates with quantitative analysis of activated caspase staining of mucosal biopsy samples from patients. METHODS: We obtained pCLE images and biopsy samples of the terminal ileum during colonoscopies of healthy controls and patients with either IBD or IBS. The pCLE images and biopsy samples were blindly analyzed for gap density and for cells staining positive for activated caspases, respectively. The degree of correlation was determined using nonparametric statistical tests. RESULTS: The median results were 10 gaps/1000 cells counted for controls versus 33 gaps/1000 cells counted for chronic intestinal disorder patients (p = 0.02). Activated caspase staining showed 13 positive cells/1000 epithelial cells counted versus 26 positive cells/1000 epithelial cells counted, respectively (p = 0.02), thus showing a strong correlation with a Spearman's coefficient ρ of 0.61 (strong correlation for ρ = 0.4-0.75, p = 0.01). CONCLUSIONS: Intestinal epithelial gap density via pCLE correlated strongly with quantitative analysis of immunohistochemical staining of mucosal biopsy samples.

Racial and Ethnic Disparities in Health-Related Outcomes in Crohn's Disease: Results From the National Health and Wellness Survey.

Background: Crohn's disease (CD) is a chronic inflammatory condition affecting the entire gastrointestinal tract that is associated with significant humanistic, clinical, and economic burdens. Few studies have assessed the association between CD severity and patient-reported outcomes (PROs), healthcare resource utilization (HCRU), and medical costs; even fewer have examined differences in disease outcomes among patients of various racial/ethnic groups. Methods: In this cross-sectional study, sociodemographic data, PROs, and economic outcomes for participants with self-reported CD were collected from the National Health and Wellness Survey (2018-2020). Multivariable analyses were used to assess the association of CD severity and race/ethnicity with health-related quality of life (HRQoL), work productivity and activity impairment (WPAI), HCRU, and medical costs. Results: Analyses included 1077 participants with CD (818 non-Hispanic White, 109 non-Hispanic Black, and 150 Hispanic). Participants with self-reported moderate/severe CD reported significantly worse HRQoL and WPAI, greater HCRU, and higher medical costs than those with self-reported mild CD. Non-Hispanic Black participants reported better HRQoL and fewer healthcare provider visits than non-Hispanic White participants. There were no significant differences in PROs between non-Hispanic White and Hispanic groups. Interactions between race/ethnicity and CD severity emerged for some, but not all groups: Specifically, non-Hispanic Black participants with moderate/severe CD reported greater absenteeism and more gastroenterologist visits than non-Hispanic Black participants with mild CD. Conclusions: Participants with moderate/severe CD reported worse PROs, greater HCRU, and higher medical costs than those with mild CD. Additionally, racial/ethnic differences were found across several HCRU and economic outcomes. Further research is needed to better understand factors contributing to burden among patients with varying CD severity across racial/ethnic groups.

Breaks in the wall: increased gaps in the intestinal epithelium of irritable bowel syndrome patients identified by confocal laser endomicroscopy (with videos).

BACKGROUND: Altered intestinal permeability and mucosal inflammation have been reported in irritable bowel syndrome (IBS) patients. Increased cell extrusion in the epithelium as measured by epithelial gaps may be associated with barrier dysfunction and may lead to mucosal inflammation. Confocal laser endomicroscopy can be used to identify and quantitate epithelial gaps in the small intestine. OBJECTIVE: To determine the epithelial gap density in IBS and healthy control patients. DESIGN: Prospective, controlled cohort study. SETTING: A tertiary referral center. PATIENTS: In IBS and control patients undergoing routine colonoscopy, probe-based confocal laser endomicroscopy was used to image the terminal ileum. MAIN OUTCOME MEASUREMENTS: The primary outcome was the density of epithelial gaps (gaps/cells counted) in adequately imaged villi using pCLE. Images were reviewed by 2 blinded reviewers. RESULTS: We recruited 18 healthy controls and 16 IBS patients. The median epithelial gap densities for control and IBS patients were 6 and 32 gaps per 1000 cells, respectively (P < .001). There was a trend toward higher gap density in female (P = .07) and younger (ρ = -0.43, P = .07) patients. Using 3% (90% of the control population) as the cutoff for abnormal gap density, we found the diagnostic accuracy for IBS to be as follows: 62% sensitivity, 89% specificity, 83% positive predictive value, and 73% negative predictive value. LIMITATIONS: A single-center study, small number of patients. CONCLUSIONS: IBS patients have significantly more epithelial gaps in their small intestine compared with healthy controls, which suggests that increased epithelial cell extrusion may be a cause of altered intestinal permeability observed in IBS.

The Current State of Care for Black and Hispanic Inflammatory Bowel Disease Patients.

Research on the care of inflammatory bowel disease (IBD) patients has been primarily in populations of European ancestry. However, the incidence of IBD, which comprises Crohn's disease and ulcerative colitis, is increasing in different populations around the world. In this comprehensive review, we examine the epidemiology, clinical presentations, disease phenotypes, treatment outcomes, social determinants of health, and genetic and environmental factors in the pathogenesis of IBD in Black and Hispanic patients in the United States. To improve health equity of underserved minorities with IBD, we identified the following priority areas: access to care, accurate assessment of treatment outcomes, incorporation of Black and Hispanic patients in therapeutic clinical trials, and investigation of environmental factors that lead to the increase in disease incidence.

In this comprehensive review, we examine the epidemiology, clinical presentations, disease phenotypes, treatment outcomes, social determinants of health, and genetic and environment factors in the pathogenesis of IBD in Black and Hispanic patients in the United States.

Increased epithelial gaps in the small intestines of patients with inflammatory bowel disease: density matters.

BACKGROUND: Epithelial gaps created by shedding of epithelial cells in the small intestine can be visualized by using confocal laser endomicroscopy (CLE). The density of epithelial gaps in the small bowels of patients with inflammatory bowel disease (IBD) and controls without IBD is unknown. OBJECTIVE: To determine whether the epithelial gap density in patients with IBD is different from that in controls. DESIGN: Prospective, controlled, cohort study. SETTING: A tertiary-care referral center. PATIENTS: This study involved patients with IBD and control patients without IBD undergoing colonoscopy. INTERVENTION: Probe-based CLE (pCLE) was used to image the terminal ileum. MAIN OUTCOME MEASUREMENTS: The primary outcome of the study was gap density, defined as the total number of gaps per 1000 cells counted in adequately imaged villi by using pCLE. The pCLE images were blindly reviewed, and the number of epithelial gaps and cells were manually counted. The secondary outcomes were correlation of gap density with disease activity, location, and severity of clinical disease. RESULTS: There were 30 controls and 28 patients with IBD. Of the patients with IBD, 16 had Crohn's disease, and 12 had ulcerative colitis. The median epithelial gap densities for controls and patients with IBD were 18 and 61 gaps/1000 cells, respectively (P < .001). Gap density did not correlate with disease activity. Patients with ulcerative pan-colitis tended toward gap densities lower than those of patients with limited colitis (32 versus 97 gaps/1000 cells, P = .06). Patients with IBD with severe clinical disease also had lower median gap densities (37 vs 90 gaps/1000 cells, P = .04). LIMITATIONS: A single-center study. CONCLUSION: The epithelial gap density was significantly increased in patients with IBD compared with controls. ( CLINICAL TRIAL REGISTRATION NUMBER: NCT00988273.).

Mind the gaps: confocal endomicroscopy showed increased density of small bowel epithelial gaps in inflammatory bowel disease.

OBJECTIVES: Confocal endomicroscopy can be used to image intestinal mucosa. Epithelial gaps resulting from shedding of epithelial cells have been reported in patients. We hypothesize that the rate of epithelial cell shedding increases in patients with Crohn's disease, leading to more epithelial gaps and barrier dysfunction. In this study, we used probe-based confocal laser endomicroscopy to quantify epithelial cells and gaps in patients with Crohn's disease compared with controls. We also determined the density of epithelial gaps in a mouse model of inflammatory bowel disease-interleukin-10-deficient (IL-10) mice, versus the background strain using rigid probe confocal endomicroscopy. METHODS: Probe-based confocal laser endomicroscopy of the terminal ileum of both patients with Crohn's disease and controls was performed by a single endoscopist during colonoscopy. In mice, sections of the small intestine were imaged using a rigid confocal probe. Gap density was defined as the number of epithelial gaps per 1000 cells counted. RESULTS: In this study, we examined 6 controls (2 male and 4 female; median age 59 y) and 8 patients with Crohn's disease (5 male and 3 female; median age 42 y). The mean gap densities (±standard error) observed for the 2 groups were 17.7±5.6 and 117±33 gaps per 1000 cells, respectively (P<0.01). For control and IL-10 mice, the gap densities were 10.5±2.2 and 17.8±1.4 gaps per 1000 cells, respectively (P<0.01). CONCLUSIONS: The epithelial gap density was significantly higher in patients with Crohn's disease than controls. Gap density was also elevated in the mouse model of inflammatory bowel disease.

Epithelial Cell Biomarkers Are Predictive of Response to Biologic Agents in Crohn's Disease.

BACKGROUND: Therapeutic efficacy of biologics has remained at about 50% for 2 decades. In Crohn's disease (CD) patients, we examined the predictive value of an epithelial cell biomarker, ileal microvillar length (MVL), for clinical response to ustekinumab (UST) and vedolizumab (VDZ) and its relationship to another biomarker, intestinal epithelial cell (IEC) pyroptosis, with respect to response to VDZ. METHOD: Ileal biopsies from the UNITI-2 randomized controlled trial were analyzed for MVL as a predictor of clinical response to UST. In a 5-center academic retrospective cohort of CD patients, ileal MVL was analyzed to determine its predictive value for response to VDZ. Correlation between ileal MVL and IEC pyroptosis was determined, and the discriminant ability of the combination of 2 biomarkers to VDZ was examined. RESULTS: Clinical response in UST was significantly higher than placebo (65% vs 39%; P = 0.03), with patients with normal MVL (>1.7 µm) having the greatest therapeutic effect: 85% vs 20% (P = 0.02). For VDZ, clinical response with MVL of 1.35 to 1.55 µm was 82% vs 44% (<1.35 µm) and 40% (>1.55 µm; P = 0.038). There was no correlation between ileal MVL and IEC pyroptosis. The combination criteria of ileal pyroptosis <14 positive cells/1000 IECs or MVL of 1.35 to 1.55 µm could identify 84% of responders and 67% of nonresponders (P = 0.001). CONCLUSION: Ileal MVL was predictive of response to UST and VDZ in prospective and retrospective CD cohorts. It was independent of ileal IEC pyroptosis, and combination of the 2 biomarkers enhanced the discriminate ability of responders from nonresponders to VDZ.

Determination of optimal monopolar coagulation settings for upper GI bleeding in a pig model.

BACKGROUND: Monopolar electrocautery has had a limited role in the endoscopic therapy of nonvariceal upper GI bleeding because of the lack of specifically designed endoscopic instruments and limited data on how to use this technology for endoscopic applications. OBJECTIVE: To determine the optimal power settings and durations of endoscopic monopolar electrocautery for nonvariceal gastric bleeding. DESIGN: Twelve pigs underwent creation of cautery lesions by using a novel monopolar electrocautery device designed for endoscopic hemostasis control. The efficacy as measured by the depth of cautery and safety of monopolar electrocoagulation were evaluated in acute and survival phases. INTERVENTIONS: Monopolar electrocautery was applied to the stomach with power settings of 25, 50, and 75 W for durations of 2 to 5 seconds. MAIN OUTCOME MEASUREMENT: The extent of cautery injury was assessed histologically by a blinded pathologist. RESULTS: An optimal cautery effect was achieved with 50 W of power and durations of cautery of 2 and 3 seconds. For 25 W, durations of cautery of 4 and 5 seconds resulted in good but often superficial cautery effect. For 75 W, durations of cautery of 2 and 3 seconds resulted in good cautery effect, but with marginal safety. The visual diameter of monopolar cautery lesions correlated with the histological depth of the cautery lesions. No adverse effects were observed. LIMITATIONS: Study conducted in a nonbleeding pig stomach model; thus, results may not apply to control of GI bleeding in patients. CONCLUSIONS: Based on a nonbleeding pig model, we suggest that the initial settings for monopolar soft coagulation in clinical use should be 50 W for 2 to 3 seconds.

Mucosal Biomarker of Innate Immune Activation Predicts Response to Vedolizumab in Crohn's Disease.

OBJECTIVE: Mucosal barrier dysfunction plays a crucial role in intestinal inflammation in Crohn's disease (CD). Intestinal epithelial cell (IEC) death resulting from innate immune activation, termed pyroptosis, was recently found to be a cause of this barrier defect. The aim of this study was to determine the predictive value of pretreatment ileal biopsy pyroptosis as a biomarker for clinical response to vedolizumab in CD. DESIGN: Crohn's disease patients ranging 18 to 80 years old from 5 IBD centers with pre-vedolizumab ileal biopsies during colonoscopy were enrolled. Biopsies were stained for activated caspases, and levels of ileal IEC pyroptosis levels were quantified. The primary outcome was clinical response 6 months after therapy, defined as a reduction of Harvey-Bradshaw Index (HBI) of ≥5 points from baseline. Secondary outcomes included clinical remission, defined as HBI <5, and endoscopic improvement, as measured by the Simple Endoscopic Score for Crohn's Disease (SES-CD). RESULTS: One hundred CD patients (45 male, 55 female), median age 47 (19, 78) years, were included; clinical response rate was 60%, and clinical remission was 36%. The response rate in patients with ileal pyroptosis <14 positive cells per 1000 IECs was significantly higher than those above the threshold: 89% (25 of 28) vs 49% (35 of 72), odds ratio (OR) 8.8 (95% CI, 2.3-48.6; P < 0.001). Corresponding remission rates were 54% (15 of 28) vs 29% (21 of 72; OR 2.8 [1.03-7.59; P = 0.036]). For endoscopic improvement, ileal pyroptosis of 22 positive cells per 1000 IECs was the optimal threshold that determines the magnitude SES-CD change. CONCLUSIONS: Ileal biopsy IEC pyroptosis was predictive of clinical response and endoscopic improvement to vedolizmab in CD patients.

Cholangiocyte bile salt transporters in cholesterol gallstone-susceptible and resistant inbred mouse strains.

BACKGROUND AND AIM: We investigated the dietary and gender influences on the expression and functionality of cholangiocyte bile salt transporters and development of biliary hyperplasia in cholesterol gallstone-susceptible C57L/J and resistant AKR/J mice. METHODS: C57L and AKR mice were fed chow, a lithogenic diet, or a cholic acid-containing diet for 14 days. Expression of cholangiocyte bile salt transporter proteins ASBT (SLC10A2), ILBP (FABP6), and MRP3 (ABCC3) were studied by Western blot analysis. Taurocholate uptake studies were performed using microperfusion of isolated bile duct units. The pre- and post-perfusion taurocholate concentrations were analyzed by high performance liquid chromatography. Biliary proliferation in liver sections was scored. RESULTS: The lithogenic diet induced ductular proliferation in C57L mice. On chow, SLC10A2 and ABCC3 were overexpressed in male and female C57L compared to AKR mice. A lithogenic diet reduced the expressions of FABP6 in both male and female C57L mice, SLC10A2 in female C57L mice, and ABCC3 in male C57L mice. These alterations in transporter expressions were not associated with changes in taurocholate uptake. The lithogenic diet induced biliary hyperplasia and reduced bile salt transporter expressions in C57L mice. CONCLUSIONS: Although bile salt uptake was not increased in the bile duct unit, we speculate that the biliary hyperplasia on the lithogenic diet may lead to an increase in intrahepatic bile salt recycling during cholesterol cholelithogenesis.

A balanced IL-1ß activity is required for host response to Citrobacter rodentium infection.

Microbial sensing plays essential roles in the innate immune response to pathogens. In particular, NLRP3 forms a multiprotein inflammasome complex responsible for the maturation of interleukin (IL)-1ß. Our aim was to delineate the role of the NLRP3 inflammasome in macrophages, and the contribution of IL-1ß to the host defense against Citrobacter rodentium acute infection in mice. Nlrp3(-/-) and background C57BL/6 (WT) mice were infected by orogastric gavage, received IL-1ß (0.5 µg/mouse; ip) on 0, 2, and 4 days post-infection (DPI), and assessed on 6 and 10 DPI. Infected Nlrp3(-/-) mice developed severe colitis; IL-1ß treatments reduced colonization, abrogated dissemination of bacteria to mesenteric lymph nodes, and protected epithelial integrity of infected Nlrp3(-/-) mice. In contrast, IL-1ß treatments of WT mice had an opposite effect with increased penetration of bacteria and barrier disruption. Microscopy showed reduced damage in Nlrp3(-/-) mice, and increased severity of disease in WT mice with IL-1ß treatments, in particular on 10 DPI. Secretion of some pro-inflammatory plasma cytokines was dissipated in Nlrp3(-/-) compared to WT mice. IL-1ß treatments elevated macrophage infiltration into infected crypts in Nlrp3(-/-) mice, suggesting that IL-1ß may improve macrophage function, as exogenous administration of IL-1ß increased phagocytosis of C. rodentium by peritoneal Nlrp3(-/-) macrophages in vitro. As well, the exogenous administration of IL-1ß to WT peritoneal macrophages damaged the epithelial barrier of C. rodentium-infected polarized CMT-93 cells. Treatment of Nlrp3(-/-) mice with IL-1ß seems to confer protection against C. rodentium infection by reducing colonization, protecting epithelial integrity, and improving macrophage activity, while extraneous IL-1ß appeared to be detrimental to WT mice. Together, these findings highlight the importance of balanced cytokine responses as IL-1ß improved bacterial clearance in Nlrp3(-/-) mice but increased tissue damage when given to WT mice.

Epithelial cell extrusion leads to breaches in the intestinal epithelium.

BACKGROUND: Two distinct forms of intestinal epithelial cell (IEC) extrusion are described: 1 with preserved epithelial integrity and 1 that introduced breaches in the epithelial lining. In this study, we sought to determine the mechanism underlying the IEC extrusion that alters the permeability of the gut epithelium. METHODS: IEC extrusions in polarized T84 monolayer were induced with nigericin. Epithelial permeability was assessed with transepithelial electrical resistance and movements of latex microspheres and green fluorescent protein-transfected Escherichia coli across the monolayer. In vivo IEC extrusion was modulated in wild-type and a colitic (interleukin-10 knock-out) mouse model with caspase-1 activation and inhibition. Luminal aspirates and mucosal biopsies from control patients and patients with inflammatory bowel disease were analyzed for caspase-1 and caspase-3&7 activation. RESULTS: Caspase-1-induced IEC extrusion in T84 monolayers resulted in dose-dependent and time-dependent barrier dysfunction, reversible with caspase-1 inhibition. Moreover, the movements of microspheres and microbes across the treated epithelial monolayers were observed. Increased caspase-1-mediated IEC extrusion in interleukin-10 knock-out mice corresponded to enhanced permeation of dextran, microspheres, and translocation of E. coli compared with wild type. Caspase-1 inhibition in interleukin-10 knock-out mice resulted in a time-dependent reduction in cell extrusion and normalization of permeability to microspheres. Increased IEC extrusion in wild-type mice was induced with caspase-1 activation. In human luminal aspirates, the ratio of positively stained caspase-1 to caspase-3&7 cells were 1:1 and 2:1 in control patients and patients with inflammatory bowel disease, respectively; these observations were confirmed by cytochemical analysis of mucosal biopsies. CONCLUSIONS: IEC extrusion mediated by caspase-1 activation contributes to altered intestinal permeability in vitro and in vivo.