Pentacyclic triterpenes modulate farnesoid X receptor expression in colonic epithelial cells: Implications for colonic secretory function.

The nuclear bile acid receptor, farnesoid X receptor (FXR), is an important regulator of intestinal and metabolic function. Previous studies suggest that pentacyclic triterpenes (PCTs), a class of plant-derived bioactive phytochemical, can modulate FXR activity and may therefore offer therapeutic benefits. Here, we investigated the effects of a prototypical PCT, hederagenin (HG), on FXR expression, activity, and antisecretory actions in colonic epithelial cells. T84 cells and murine enteroid-derived monolayers were employed to assess HG effects on FXR expression and activity in colonic epithelia. We measured mRNA levels by qRT-PCR and protein by ELISA and immunoblotting. Transepithelial Cl- secretion was assessed as changes in short circuit current in Ussing chambers. We determined HG treatment (5-10 µM) alone did not induce FXR activation but significantly increased expression of the receptor, both in T84 cells and murine enteroid-derived monolayers. This effect was accompanied by enhanced FXR activity, as assessed by FGF-15/19 induction in response to the synthetic, GW4064, or natural FXR agonist, chenodeoxycholic acid. Effects of HG on FXR expression and activity were mimicked by another PCT, oleanolic acid. Furthermore, we found FXR-induced downregulation of cystic fibrosis transmembrane conductance regulator Cl- channels and inhibition of transepithelial Cl- secretion were enhanced in HG-treated cells. These data demonstrate that dietary PCTs have the capacity to modulate FXR expression, activity, and antisecretory actions in colonic epithelial cells. Based on these data, we propose that plants rich in PCTs, or extracts thereof, have excellent potential for development as a new class of "FXR-targeted nutraceuticals".

Role of the microbiota-gut-brain axis in postacute COVID syndrome.

The COVID-19 pandemic has resulted in the infection of hundreds of millions of individuals over the past 3 years, coupled with millions of deaths. Along with these more acute impacts of infection, a large subset of patients has developed symptoms that collectively comprise "postacute sequelae of COVID-19" (PASC, also known as long COVID), which can persist for months and maybe even years. In this review, we outline the current knowledge on the role of impaired microbiota-gut-brain (MGB) axis signaling in the development of PASC and the potential mechanisms involved, which may lead to a better understanding of disease progression and treatment options in the future.

Susceptibility antibiotic screening reveals high rates of multidrug resistance of Salmonella, Shigella and Campylobacter in HIV infected and uninfected patients from Mozambique.

BACKGROUND: Antibacterial resistance is a growing concern worldwide, including in Mozambique. Diarrhea is an important cause of mortality in Mozambique, yet few local studies have reported on the resistance of bacterial pathogens in this context. Therefore, this study aims to characterize antibiotic susceptibility patterns of Salmonella, Shigella and Campylobacter spp. among patients with diarrhea, including those who are HIV-infected and-uninfected. METHODS: We conducted antibiotic susceptibility testing on 157 stool isolates recovered from 129 patients aged between 0 and 80 years with diarrhea, including HIV infected (n = 68) and-uninfected individuals (n = 61), assisted at two health centers in Maputo city. The isolates comprised of 99 Salmonella, 45 Shigella and 13 Campylobacter strains. The Kirby-Bauer disk diffusion method was used on Mueller-Hinton II agar for Salmonella and Shigella spp., while Mueller-Hinton II agar with 5% defibrinated sheep blood was used for Campylobacter spp. We tested six antibiotics listed on the national essential medicines list, including ciprofloxacin, erythromycin, azithromycin, trimethoprim-sulfamethoxazole, gentamicin, and tetracycline. RESULTS: All isolates were resistant to at least one antibiotic. A high percentage of Salmonella spp. isolates were found to be resistant to trimethoprim-sulfamethoxazole (89.9%, n = 89), erythromycin (88.9%, n = 88) and tetracycline (76.8%, n = 76). In addition, 86.6% (n = 39) and 68.9% (n = 31) of Shigella isolates were resistant to trimethoprim-sulfamethoxazole and tetracycline, respectively. The majority of Campylobacter isolates (92.3%, n = 12) were resistant to erythromycin, azithromycin and tetracycline. Multidrug resistance (MDR) was observed in 79.8% of Salmonella spp., 76.9% of Campylobacter spp., and 57.8% of Shigella spp. Drug susceptibility profiles for Salmonella spp. and Campylobacter were similar in both HIV-1 infected and uninfected patients. However, Shigella spp. isolates obtained from patients without HIV infection were significantly more likely to be resistant to erythromycin, azithromycin or to exhibit multidrug resistance than those obtained from patients with HIV-1 infection (p < 0.05). All Shigella spp. and Campylobacter spp. isolates were susceptible to gentamicin. CONCLUSION: Our study highlights concerning rates of antibiotic resistance and MDR among diarrheal bacterial pathogens in Mozambique. Further research is needed to understand the impact of HIV, ART therapy and immunosuppression on antibiotic resistance. Urgent interventions are essential to prevent the spread of resistant strains.

Potentially probiotic Limosilactobacillus reuteri from human milk strengthens the gut barrier in T84 cells and a murine enteroid model.

AIMS: At conception, the infant gut barrier is immature, gradually developing with regular intake of maternal milk. This study addressed whether the barrier-strengthening effect of breast feeding might be attributable, at least in part, to autochthonous beneficial human milk bacteria. METHODS AND RESULTS: Twelve bacterial strains from the breast milk of Pakistani mothers who underwent cesarean delivery (NPL-88, NPL-157, NPL-179, NPL-181, NPL-388 (Limosilactobacillus reuteri), NPL-76, NPL-495, NPL-504 (Limosilactobacillus fermentum), NPL-415 (Lactobacillus pentosus), NPL-412, NPL-416 (Lactiplantibacilllus plantarum) and NPL-374 (Bifidobacterium longum) were shortlisted based on their tolerance to acidic pH (2.8-4.2) and bile (0.1-0.3%). The effect of these bacteria on gut barrier function in the presence and absence of pathogens was assessed as changes in transepithelial electrical resistance (TEER) in the human T84 colonic epithelial cell line and in murine enteroid-derived monolayers (EDMs). The TEER of T84 cells monolayers rose in the presence of most of the human milk strains, being most pronounced in case of L. reuteri NPL-88 (34% within five h), exceeding the effect of the well-known probiotic L. acidophilus (20%). qRT-PCR, western blot and immunofluorescent staining associated the increase in TEER with enhanced expression of tight junction proteins. Pretreatment of murine EDMs with NPL-88 also largely prevented the ability of the pathogen, Salmonella, to decrease TEER (87 ± 1.50%; P < 0.0001, n = 4). CONCLUSIONS: Human milk lactic acid bacteria are potential probiotics that can strengthen gut barrier function and protect breastfed neonates against enteric infections.

Diarrhoeal pathogenesis in Salmonella infection may result from an imbalance in intestinal epithelial differentiation through reduced Notch signalling.

Infections with non-typhoidal Salmonella spp. represent the most burdensome foodborne illnesses worldwide, yet despite their prevalence, the mechanism through which Salmonella elicits diarrhoea is not entirely known. Intestinal ion transporters play important roles in fluid and electrolyte homeostasis in the intestine. We have previously shown that infection with Salmonella caused decreased colonic expression of the chloride/bicarbonate exchanger SLC26A3 (down-regulated in adenoma; DRA) in a mouse model. In this study, we focused on the mechanism of DRA downregulation during Salmonella infection, by using murine epithelial enteroid-derived monolayers (EDMs). The decrease in DRA expression caused by infection was recapitulated in EDMs and accompanied by increased expression of Atonal Homolog 1 (ATOH1), the goblet cell marker Muc2 and the enteroendocrine cell marker ChgA. This suggested biased epithelial differentiation towards the secretory, rather than absorptive phenotype. In addition, the downstream Notch effector, Notch intracellular domain (NICD) and Hes1 were decreased following Salmonella infection. The relevance of Notch signalling was further investigated using a γ-secretase inhibitor, which recapitulated the downregulation in Hes1 and DRA as well as upregulation in ATOH1 and Muc2 seen following infection. Our findings suggest that Salmonella infection may result in a shift from absorptive to secretory cell types through Notch inhibition, which explains why there is a decreased capacity for absorption and ultimately the accumulation of diarrhoeal fluid. Our work also shows the value of EDMs as a model to investigate mechanisms that might be targeted for therapy of diarrhoea caused by Salmonella infection. KEY POINTS: Salmonella is a leading foodborne pathogen known to cause high-chloride-content diarrhoea. Salmonella infection of murine enteroid-derived monolayers decreased DRA expression. Salmonella infection resulted in upregulation of the secretory epithelial marker ATOH1, the goblet cell marker Muc2 and the enteroendocrine cell marker ChgA. Downregulation of DRA may result from infection-induced Notch inhibition, as reflected by decreased expression of Notch intracellular domain and Hes1, as well as from decreased HNF1α signalling. The imbalance in intestinal epithelial differentiation favouring secretory over absorptive cell types is a possible mechanism by which Salmonella elicits diarrhoea and may be relevant therapeutically.

Intestinal secretory mechanisms and diarrhea.

One of the primary functions of the intestinal epithelium is to transport fluid and electrolytes to and from the luminal contents. Under normal circumstances, absorptive and secretory processes are tightly regulated such that absorption predominates, thereby enabling conservation of the large volumes of water that pass through the intestine each day. However, in conditions of secretory diarrhea, this balance becomes dysregulated, so that fluid secretion, driven primarily by Cl- secretion, overwhelms absorptive capacity, leading to increased loss of water in the stool. Secretory diarrheas are common and include those induced by pathogenic bacteria and viruses, allergens, and disruptions to bile acid homeostasis, or as a side effect of many drugs. Here, we review the cellular and molecular mechanisms by which Cl- and fluid secretion in the intestine are regulated, how these mechanisms become dysregulated in conditions of secretory diarrhea, currently available and emerging therapeutic approaches, and how new strategies to exploit intestinal secretory mechanisms are successfully being used in the treatment of constipation.

Gastrointestinal jabberwocky to bioengineering design: using function diagrams to teach physiology.

Function diagrams put the focus on physiology and physiological concepts rather than the associated anatomy. Function diagrams could potentially serve as an elaboration tool and memory aid (mnemonic) to improve learning and recall. The function diagram prototype of the gastrointestinal system can aid in the instruction of difficult gastrointestinal physiology topics using a sequential focus on fundamental gastrointestinal functions.

Epithelial transport in digestive diseases: mice, monolayers, and mechanisms.

The transport of electrolytes and fluid by the intestinal epithelium is critical in health to maintain appropriate levels of fluidity of the intestinal contents. The transport mechanisms that underlie this physiological process are also subject to derangement in various digestive disease states, such as diarrheal illnesses. This article summarizes the 2019 Hans Ussing Lecture of the Epithelial Transport Group of the American Physiological Society and discusses some pathways by which intestinal transport is dysregulated, particularly in the setting of infection with the diarrheal pathogen, Salmonella, and in patients treated with small-molecule inhibitors of the tyrosine kinase activity of the epidermal growth factor receptor (EGFr-TKI). The burdensome diarrhea in patients infected with Salmonella may be attributable to decreased expression of the chloride-bicarbonate exchanger downregulated in adenoma (DRA) that participates in electroneutral NaCl absorption. This outcome is possibly secondary to increased epithelial proliferation and/or decreased epithelial differentiation that occurs following infection. Conversely, the diarrheal side effects of cancer treatment with EGFr-TKI may be related to the known ability of EGFr-associated signaling to reduce calcium-dependent chloride secretion. Overall, the findings described may suggest targets for therapeutic intervention in a variety of diarrheal disease states.

Human evolutionary loss of epithelial Neu5Gc expression and species-specific susceptibility to cholera.

While infectious agents have typical host preferences, the noninvasive enteric bacterium Vibrio cholerae is remarkable for its ability to survive in many environments, yet cause diarrheal disease (cholera) only in humans. One key V. cholerae virulence factor is its neuraminidase (VcN), which releases host intestinal epithelial sialic acids as a nutrition source and simultaneously remodels intestinal polysialylated gangliosides into monosialoganglioside GM1. GM1 is the optimal binding target for the B subunit of a second virulence factor, the AB5 cholera toxin (Ctx). This coordinated process delivers the CtxA subunit into host epithelia, triggering fluid loss via cAMP-mediated activation of anion secretion and inhibition of electroneutral NaCl absorption. We hypothesized that human-specific and human-universal evolutionary loss of the sialic acid N-glycolylneuraminic acid (Neu5Gc) and the consequent excess of N-acetylneuraminic acid (Neu5Ac) contributes to specificity at one or more steps in pathogenesis. Indeed, VcN was less efficient in releasing Neu5Gc than Neu5Ac. We show enhanced binding of Ctx to sections of small intestine and isolated polysialogangliosides from human-like Neu5Gc-deficient Cmah-/- mice compared to wild-type, suggesting that Neu5Gc impeded generation of the GM1 target. Human epithelial cells artificially expressing Neu5Gc were also less susceptible to Ctx binding and CtxA intoxication following VcN treatment. Finally, we found increased fluid secretion into loops of Cmah-/- mouse small intestine injected with Ctx, indicating an additional direct effect on ion transport. Thus, V. cholerae evolved into a human-specific pathogen partly by adapting to the human evolutionary loss of Neu5Gc, optimizing multiple steps in cholera pathogenesis.

Nod-like receptors are critical for gut-brain axis signalling in mice.

KEY POINTS: •Nucleotide binding oligomerization domain (Nod)-like receptors regulate cognition, anxiety and hypothalamic-pituitary-adrenal axis activation. •Nod-like receptors regulate central and peripheral serotonergic biology. •Nod-like receptors are important for maintenance of gastrointestinal physiology. •Intestinal epithelial cell expression of Nod1 receptors regulate behaviour. ABSTRACT: Gut-brain axis signalling is critical for maintaining health and homeostasis. Stressful life events can impact gut-brain signalling, leading to altered mood, cognition and intestinal dysfunction. In the present study, we identified nucleotide binding oligomerization domain (Nod)-like receptors (NLR), Nod1 and Nod2, as novel regulators for gut-brain signalling. NLR are innate immune pattern recognition receptors expressed in the gut and brain, and are important in the regulation of gastrointestinal physiology. We found that mice deficient in both Nod1 and Nod2 (NodDKO) demonstrate signs of stress-induced anxiety, cognitive impairment and depression in the context of a hyperactive hypothalamic-pituitary-adrenal axis. These deficits were coupled with impairments in the serotonergic pathway in the brain, decreased hippocampal cell proliferation and immature neurons, as well as reduced neural activation. In addition, NodDKO mice had increased gastrointestinal permeability and altered serotonin signalling in the gut following exposure to acute stress. Administration of the selective serotonin reuptake inhibitor, fluoxetine, abrogated behavioural impairments and restored serotonin signalling. We also identified that intestinal epithelial cell-specific deletion of Nod1 (VilCre+ Nod1f/f ), but not Nod2, increased susceptibility to stress-induced anxiety-like behaviour and cognitive impairment following exposure to stress. Together, these data suggest that intestinal epithelial NLR are novel modulators of gut-brain communication and may serve as potential novel therapeutic targets for the treatment of gut-brain disorders.

Enteroids expressing a disease-associated mutant of EpCAM are a model for congenital tufting enteropathy.

Congenital tufting enteropathy (CTE) is an autosomal recessive disease characterized by severe intestinal failure in infancy and mutations in the epithelial cell adhesion molecule (EPCAM) gene. Previous studies of CTE in mice expressing mutant EpCAM show neonatal lethality. Hence, to study the cellular, molecular, and physiological alterations that result from EpCAM mutation, a tamoxifen-inducible mutant EpCAM enteroid model has been generated. The presence of mutant EpCAM in the model was confirmed at both mRNA and protein levels. Immunofluorescence microscopy demonstrated the reduced expression of mutant EpCAM. Mutant enteroids had reduced budding potential as well as significantly decreased mRNA expression for epithelial lineage markers (Mucin 2, lysozyme, sucrase-isomaltase), proliferation marker Ki67, and secretory pathway transcription factors (Atoh1, Hnf1b). Significantly decreased numbers of Paneth and goblet cells were confirmed by staining. These findings were correlated with intestinal tissue from CTE patients and the mutant mice model that had significantly fewer Paneth and goblet cells than in healthy counterparts. FITC-dextran studies demonstrated significantly impaired barrier function in monolayers derived from mutant enteroids compared with control monolayers. In conclusion, we have established an ex vivo CTE model. The role of EpCAM in the budding potential, differentiation, and barrier function of enteroids is noted. Our study establishes new facets of EpCAM biology that will aid in understanding the pathophysiology of CTE and role of EpCAM in health and disease.NEW & NOTEWORTHY Here, we develop a novel ex vivo enteroid model for congenital tufting enteropathy (CTE) based on epithelial cell adhesion molecule (EPCAM) gene mutations found in patients. With this model we demonstrate the role of EpCAM in maintaining the functional homeostasis of the intestinal epithelium, including differentiation, proliferation, and barrier integrity. This study further establishes a new direction in EpCAM biology that will help in understanding the detailed pathophysiology of CTE and role of EpCAM.

Should We Divide Crohn's Disease Into Ileum-Dominant and Isolated Colonic Diseases?

Crohn's disease (CD) is an inflammatory bowel disease that can involve any region of the gastrointestinal tract. First described in 1932 as terminal ileitis or regional enteritis, it predominately involves the ileum with or without colonic involvement. Isolated colonic CD was first described in 1960 and since then the phenotypic classification of CD has evolved to stratify patients into isolated ileal, ileocolonic, or isolated colonic involvement. In the current review we evaluate the published literature regarding differences in epidemiology, natural history, pathogenesis, response to therapy, and disease monitoring, when stratified by disease location. Based on the available evidence consideration could be given to a new classification for CD, which splits it into ileum dominant (isolated ileal and ileocolonic) and isolated colonic disease. This may allow for a more optimized approach to clinical care and scientific research for CD.

Interleukin 9 Alters Epithelial Barrier and E-cadherin in Eosinophilic Esophagitis.

BACKGROUND: Eosinophilic esophagitis (EoE) is a chronic TH2-assocated inflammatory condition accompanied by substantial impairments in epithelial barrier function and increased numbers of interleukin 9 (IL-9) expressing inflammatory cells. While IL-9 is known to affect barrier function in the intestine, the functional effects of IL-9 on the esophagus are unclear. Herein we aimed to understand the expression of the IL-9 receptor and effects of IL-9 on the epithelium in EoE. METHODS: We used esophageal biopsies from pediatric EoE patients with active and inactive disease to analyze the expression of the IL-9 receptor, the adherens junction protein E-cadherin and the tight junction protein claudin-1. We treated primary human esophageal epithelial cells with IL-9 to understand its effects on E-cadherin expression and function. RESULTS: Active EoE subjects had increased epithelial expression of IL-9 receptor mRNA and protein (P < 0.05) and decreased membrane bound E-cadherin (P < 0.01) and claudin-1 (P < 0.05) expression. IL-9 receptor expression and mislocalized claudin-1 positively correlated and while membrane bound E-cadherin expression negatively correlated with the degree of histologic epithelial remodeling (P < 0.05). IL-9 decreased epithelial resistance in stratified primary human esophageal epithelial cells (P < 0.01) and membrane bound E-cadherin in epithelial cell monolayers (P < 0.01). CONCLUSIONS: These data suggest that IL-9, its receptor, and its effects on E-cadherin may be important mechanisms for epithelial barrier disruption in EoE.

Pathophysiology, Evaluation, and Management of Chronic Watery Diarrhea.

Chronic watery diarrhea poses a diagnostic and therapeutic challenge and is often a disabling condition for patients. Although acute diarrhea is likely to be caused by infection, the causes of chronic diarrhea (>4 weeks in duration) are more elusive. We review the pathophysiology, diagnosis, and treatment of chronic diarrhea. Drawing on recent insights into the molecular mechanisms of intestinal epithelial transport and barrier function, we discuss how diarrhea can result from a decrease in luminal solute absorption, an increase in secretion, or both, as well as derangements in barrier properties. We also describe the various extraepithelial factors that activate diarrheal mechanisms. Finally, clinical evaluation and tests used in the assessment of patients presenting with chronic diarrhea are reviewed, and an algorithm guiding therapeutic decisions and pharmacotherapy is presented.

Endogenous and exogenous control of gastrointestinal epithelial function: building on the legacy of Bayliss and Starling.

Transport of fluid and electrolytes in the intestine allows for appropriate adjustments in luminal fluidity while reclaiming water used in digesting and absorbing a meal, and is closely regulated. This article discusses various endogenous and exogenous mechanisms whereby transport is controlled in the gut, placing these in the context of the ideas about the neurohumoral control of alimentary physiology that were promulgated by William Bayliss and Ernest Starling. The article considers three themes. First, mechanisms that intrinsically regulate chloride secretion, centred on the epidermal growth factor receptor (EGFr), are discussed. These may be important in ensuring that excessive chloride secretion, with the accompanying loss of fluid, is not normally stimulated by intestinal distension as the meal passes through the gastrointestinal tract. Second, mechanisms whereby probiotic microorganisms can impart beneficial effects on the gut are described, with a focus on targets at the level of the epithelium. These findings imply that the commensal microbiota exert important influences on the epithelium in health and disease. Finally, mechanisms that lead to diarrhoea in patients infected with an invasive pathogen, Salmonella, are considered, based on recent studies in a novel mouse model. Diarrhoea is most likely attributable to reduced expression of absorptive transporters and may not require the influx of neutrophils that accompanies infection. Overall, the goal of the article is to highlight the many ways in which critical functions of the intestinal epithelium are regulated under physiological and pathophysiological conditions, and to suggest possible targets for new therapies for digestive disease states.

Hypercapnia Suppresses the HIF-dependent Adaptive Response to Hypoxia.

Molecular oxygen and carbon dioxide are the primary gaseous substrate and product of oxidative metabolism, respectively. Hypoxia (low oxygen) and hypercapnia (high carbon dioxide) are co-incidental features of the tissue microenvironment in a range of pathophysiologic states, including acute and chronic respiratory diseases. The hypoxia-inducible factor (HIF) is the master regulator of the transcriptional response to hypoxia; however, little is known about the impact of hypercapnia on gene transcription. Because of the relationship between hypoxia and hypercapnia, we investigated the effect of hypercapnia on the HIF pathway. Hypercapnia suppressed HIF-α protein stability and HIF target gene expression both in mice and cultured cells in a manner that was at least in part independent of the canonical O2-dependent HIF degradation pathway. The suppressive effects of hypercapnia on HIF-α protein stability could be mimicked by reducing intracellular pH at a constant level of partial pressure of CO2 Bafilomycin A1, a specific inhibitor of vacuolar-type H(+)-ATPase that blocks lysosomal degradation, prevented the hypercapnic suppression of HIF-α protein. Based on these results, we hypothesize that hypercapnia counter-regulates activation of the HIF pathway by reducing intracellular pH and promoting lysosomal degradation of HIF-α subunits. Therefore, hypercapnia may play a key role in the pathophysiology of diseases where HIF is implicated.

Modulation of the microbiota-gut-brain axis by probiotics in a murine model of inflammatory bowel disease.

UNLABELLED: Anxiety, depression, and altered memory are associated with intestinal diseases, including inflammatory bowel disease (IBD). Understanding the link between these behavioral changes and IBD is important clinically since concomitant mood disorders often increase a patient's risk of requiring surgery and developing secondary functional gastrointestinal diseases. Anxiety-like behavior (light/dark box test) and recognition memory (novel object recognition task) were determined at the peak and during resolution of inflammation in the dextran sodium sulfate (DSS) mouse model of acute colitis. DSS (5 days) was administered via drinking water followed by 3 or 9 days of normal drinking water to assess behavior during active or resolving inflammation, respectively. Disease (weight, colon length, and histology) was assessed and the composition of the gut microbiota was characterized by using qPCR on fecal pellet DNA. In a subset of mice, pretreatment with probiotics was started 1 wk prior to commencing DSS. During active inflammation (8 days), mice demonstrated impaired recognition memory and exhibited anxiety-like behavior vs. CONTROLS: These behavioral defects were normalized by 14 days post-DSS. Shifts in the composition of the gut microbiota were evident during active inflammation, notably as decreases in lactobacilli and segmented filamentous bacteria, which were also reversed once the disease had resolved. Administration of probiotics could prevent the behavioral defects seen in acute DSS. Taken together, our findings indicate that changes in mood and behavior are present during acute inflammation in murine IBD and associated with dysbiosis and that these outcomes can be prevented by the administration of probiotics.

Hydroxylase inhibition regulates inflammation-induced intestinal fibrosis through the suppression of ERK-mediated TGF-ß1 signaling. [corrected].

Fibrosis is a complication of chronic inflammatory disorders such as inflammatory bowel disease, a condition which has limited therapeutic options and often requires surgical intervention. Pharmacologic inhibition of oxygen-sensing prolyl hydroxylases, which confer oxygen sensitivity upon the hypoxia-inducible factor pathway, has recently been shown to have therapeutic potential in colitis, although the mechanisms involved remain unclear. Here, we investigated the impact of hydroxylase inhibition on inflammation-driven fibrosis in a murine colitis model. Mice exposed to dextran sodium sulfate, followed by a period of recovery, developed intestinal fibrosis characterized by alterations in the pattern of collagen deposition and infiltration of activated fibroblasts. Treatment with the hydroxylase inhibitor dimethyloxalylglycine ameliorated fibrosis. TGF-ß1 is a key regulator of fibrosis that acts through the activation of fibroblasts. Hydroxylase inhibition reduced TGF-ß1-induced expression of fibrotic markers in cultured fibroblasts, suggesting a direct role for hydroxylases in TGF-ß1 signaling. This was at least in part due to inhibition of noncanonical activation of extracellular signal-regulated kinase (ERK) signaling. In summary, pharmacologic hydroxylase inhibition ameliorates intestinal fibrosis through suppression of TGF-ß1-dependent ERK activation in fibroblasts. We hypothesize that in addition to previously reported immunosupressive effects, hydroxylase inhibitors independently suppress profibrotic pathways.