Intestinal epithelial cells (IECs) are exposed to profound fluctuations in oxygen tension and have evolved adaptive transcriptional responses to a low-oxygen environment. These adaptations are ...mediated primarily through the hypoxia-inducible factor (HIF) complex. Given the central role of the IEC in barrier function, we sought to determine whether HIF influenced epithelial tight junction (TJ) structure and function. Initial studies revealed that short hairpin RNA-mediated depletion of the HIF1β in T84 cells resulted in profound defects in barrier and nonuniform, undulating TJ morphology. Global HIF1α chromatin immunoprecipitation (ChIP) analysis identified claudin-1 (CLDN1) as a prominent HIF target gene. Analysis of HIF1β-deficient IEC revealed significantly reduced levels of CLDN1. Overexpression of CLDN1 in HIF1β-deficient cells resulted in resolution of morphological abnormalities and restoration of barrier function. ChIP and site-directed mutagenesis revealed prominent hypoxia response elements in the CLDN1 promoter region. Subsequent in vivo analysis revealed the importance of HIF-mediated CLDN1 expression during experimental colitis. These results identify a critical link between HIF and specific tight junction function, providing important insight into mechanisms of HIF-regulated epithelial homeostasis.
Chemokine signaling through CCR3 is a key regulatory pathway for eosinophil recruitment into tissues associated with allergic inflammation and asthma. To date, none of the CCR3 antagonists have shown ...efficacy in clinical trials. One reason might be their unbiased mode of inhibition that prevents receptor internalization, leading to drug tolerance.
We sought to develop a novel peptide nanoparticle CCR3 inhibitor (R321) with a biased mode of inhibition that would block G protein signaling but enable or promote receptor internalization.
Self-assembly of R321 peptide into nanoparticles and peptide binding to CCR3 were analyzed by means of dynamic light scattering and nuclear magnetic resonance. Inhibitory activity on CCR3 signaling was assessed in vitro by using flow cytometry, confocal microscopy, and Western blot analysis in a CCR3+ eosinophil cell line and blood eosinophils. In vivo effects of R321 were assessed by using a triple-allergen mouse asthma model.
R321 self-assembles into nanoparticles and binds directly to CCR3, altering receptor function. Half-maximal inhibitory concentration values for eotaxin-induced chemotaxis of blood eosinophils are in the low nanomolar range. R321 inhibits only the early phase of extracellular signal-regulated kinase 1/2 activation and not the late phase generally associated with β-arrestin recruitment and receptor endocytosis, promoting CCR3 internalization and degradation. In vivo R321 effectively blocks eosinophil recruitment into the blood, lungs, and airways and prevents airway hyperresponsiveness in a mouse eosinophilic asthma model.
R321 is a potent and selective antagonist of the CCR3 signaling cascade. Inhibition through a biased mode of antagonism might hold significant therapeutic promise by eluding the formation of drug tolerance.
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Despite effective dietary treatments, physicians prefer medications for eosinophilic esophagitis (EoE).
We conducted a web-based survey of providers to assess the perceived effectiveness, practice ...patterns, and barriers to EoE dietary therapy.
Providers view diet as the least effective treatment. The greatest barrier was the belief that patients are disinterested and unlikely to adhere (58%). With less access to dietitians (56%), nonacademic providers often manage diets without dietitian guidance (41%).
Given high patient acceptance for diets and multiple treatment options for EoE, clinicians need evidence-based knowledge on EoE diets, access to dietitians, and awareness of patient preferences.
Background & Aims: A number of recent studies have implicated tissue hypoxia in both acute and chronic inflammatory diseases, particularly as they relate to mucosal surfaces lined by epithelial ...cells. In this context, a protective role for the transcriptional regulator hypoxia-inducible factor (HIF) was shown through conditional deletion of epithelial HIF-1α in a murine model of colitis. Here, we hypothesized that pharmacologic activation of HIF would similarly provide a protective adaptation to murine colitic disease. Methods: For these purposes, we used a novel prolyl hydroxylase (PHD) inhibitor (FG-4497) that readily stabilizes HIF-1α and subsequently drives the expression downstream of HIF target genes (eg, erythropoietin). Results: Our results show that the FG-4497–mediated induction of HIF-1α provides an overall beneficial influence on clinical symptoms weight loss, colon length, tissue tumor necrosis factor-α (TNFα) in murine trinitrobenzene sulfonic acid (TNBS) colitis, most likely because of their barrier protective function and wound healing during severe tissue hypoxia at the site of inflammation. Conclusions: Taken together these findings emphasize the role of epithelial HIF-1α during inflammatory diseases in the colon and may provide the basis for a therapeutic use of PHD inhibitors in inflammatory mucosal disease.
The pathophysiology of dysphagia in patients with eosinophilic esophagitis (EoE) is unknown but may be related to abnormal esophageal motor function. Symptoms rarely occur during stationary ...esophageal manometry, so it has been difficult to establish an association between symptoms and motor events. Our aim was to evaluate esophageal motor function in children with EoE with the use of stationary manometry and ambulatory prolonged esophageal manometry and pH-metry (PEMP).
PEMP was performed in children with EoE and compared with controls and children with gastroesophageal reflux disease (GERD). Peristalsis was considered effective when the esophageal contractions had a normal amplitude and propagation. Results are expressed as mean+/-s.e.
Seventeen patients with EoE, 13 with GERD, and 11 controls were studied. Values are expressed as mean+/-s.e. Stationary manometry identified abnormal peristalsis in 41% of children with EoE. During PEMP, children with EoE had an increased number of isolated (16.7+/-3.8 vs. 9.5+/-1.6 vs. 6.5+/-1.1; P<0.03) and high-amplitude contractions (4.1+/-1.2 vs. 1.8+/-0.8 vs. 0.1+/-0.1; P<0.03), and higher percentage ineffective peristalsis both during fasting (70.5%+/-2.5 vs. 57.8%+/-3.0 vs. 53.8%+/-1.9; P<0.05) and during meals (68.4+/-3.4 vs. 55.3+/-2.8 vs. 48.1+/-2.8; P<0.05) when compared with children with GERD and controls. Thirteen patients with EoE experienced 21 episodes of dysphagia, and all correlated with simultaneous abnormal motor function.
PEMP allowed the detection of ineffective peristalsis in children with EoE. Symptoms observed in children with EoE may be related to esophageal motor dysfunction.
Although swallowed topical steroids are effective in inducing histological remission in eosinophilic esophagitis (EoE), their efficacy is limited by treatment nonadherence. In this study, we ...objectively measured adherence rates to swallowed topical steroids in adolescents with EoE over the course of 8 weeks and analyzed the association between adherence rate, disease and demographic features, symptom severity, and medication-taking habit strength. We found that approximately 20% of adolescents with EoE were over-dosing on their medications. After excluding these patients, mean adherence rate was 67.0% (±19.4%) and median adherence rate was 63% (interquartile range 53%-88%). Adherence was not associated with demographic features, disease history, symptom severity, or quality of life but was associated with habit strength (Pearson r = 0.48, P = 0.04). These findings suggest that habit strength may serve as a potential target for interventions aimed at improving adherence in adolescents with EoE.
In contrast to peptic strictures, clinically significant strictures in patients with eosinophilic esophagitis (EoE) may be subtle and go unrecognized at the time of endoscopy. We aimed to identify ...how often stricture was identified by endoscopy as compared with contrast esophagram.
We retrospectively reviewed esophagram and endoscopy examinations of all of the patients with EoE with esophageal stricture seen at a tertiary care pediatric hospital over a 6-year period who had both procedures completed within a 3-month time frame. Medical charts were reviewed for clinicopathologic information including age, duration of symptoms, histology, and treatment.
Twenty-two children with EoE-associated stricture completed both esophagram and endoscopic assessments. Esophageal strictures were identified by esophagram, and not endoscopy, in 55% of these children. Patients with stricture identified at esophagram alone had a shorter duration of symptoms (2.1 years duration vs 5.4 years duration, P = 0.03) than the group identified by endoscopy. Preoperative radiographic identification of a stricture was associated with dilation more often being performed.
Esophagram is a valuable test to assess esophageal anatomy in children with complicated EoE. Esophagram may be able to detect subtle fibrostenosis earlier in the natural history of the disease than endoscopy.
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