14 research outputs found
Inhibition of Tumor Angiogenesis by Tumstatin: Insights into Signaling Mechanisms and Implications in Cancer Regression
201 Claudin-7 Dysregulation in Pediatric Eosinophilic Esophagitis: A Role for TGF-β in Esophageal Epithelial Barrier Dysfunction
Ultrastructural features of eosinophilic oesophagitis: impact of treatment on desmosomes
Aims—A growing body of evidence suggests a role for altered epithelial barrier function in the
pathophysiology of eosinophilic oesophagitis (EoE), but few have described the epithelial
structure during inflammation. The purpose of this study was to define ultrastructural features of
active, inactive EoE and control subject’s oesophageal epithelia.
Methods—We prospectively enrolled patients undergoing diagnostic upper endoscopy for
evaluation of EoE. Mucosal pinch biopsies were obtained from the distal oesophagus and
processed for routine histology and electron microscopic assessment. Clinical features of enrolled
subjects were analysed and subjects were divided into four groups: normal, gastroesophageal
reflux disease (GERD), inactive EoE and active EoE. Representative photomicrographs of the
basal and superficial epithelia were reviewed for abnormalities. Desmosomes were quantified on
the surface of epithelia three to four prickle-cell layers above the basal layer. Results—Twenty-nine paediatric cases (ages 2–18 years) were enrolled in the study. We
observed a significant decrease in the number of desmosomes per cell (DPC) of subjects with
active EoE compared with inactive EoE, GERD and normal epithelia. With respect to DPC, no
significant differences were found between inactive EoE compared with GERD or normal
subjects. Additional ultrastructural features observed included epithelial microplicae and evidence
of eosinophil transmigration, degranulation, and sombrero formation.
Conclusions—Consistent with clinical and molecular findings, our ultrastructural data provide
support for an altered oesophageal barrier in paediatric cases with active EoE, which may improve
following treatmen
Clinical Implications of Pediatric Colonic Eosinophilia
Objective: Pediatric colonic eosinophilia represents a confounding finding with a wide differential. It is often difficult to determine which children may progress to inflammatory bowel disease (IBD), which have an eosinophilic colitis (EC), and which may have no underlying pathology. There is little guidance for the practitioner on the approach to these patients. To define the clinical presentations of colonic eosinophilia and identify factors which may aid in diagnosis we reviewed patients with colonic eosinophilia and the clinicopathologic factors associated with their diagnoses.
Mehtods: An 8-year retrospective chart review of children whose histopathology identified colonic eosinophilia (N = 72) compared to controls with normal biopsies (N = 35).
Results: Patients with colonic eosinophilia had increased eosinophils/high-power field compared to controls (P 1 colonoscopy and 68% of these had change from initial diagnoses.
Conclusions: There are 3 main phenotypes of children with colonic eosinophilia. Signs of chronic systemic inflammation raise suspicion for IBD. Peripheral eosinophilia and male sex are associated with EC. A significant percent of children with colonic eosinophilia do not have colonic disease. Eosinophils/high-power field is not reliable to differentiate etiologies. Repeat colonoscopies may be required to reach final diagnoses
TGF-β1 alters esophageal epithelial barrier function by attenuation of claudin-7 in eosinophilic esophagitis
Barrier dysfunction has been implicated in the pathophysiology of eosinophilic esophagitis (EoE). TGF-β1, a potent pleiotropic molecule, is increased in EoE, however, no study has evaluated its influence on esophageal epithelial barrier. We hypothesized that TGF-β1 regulates barrier dysfunction in EoE. We aimed to determine the role of TGF-β1 in epithelial barrier in models of EoE. To examine the impact of TGF-β1 on esophageal barrier, immortalized human esophageal epithelial (EPC2-hTERT) cells were exposed to TGF-β1 during the 3-dimensional air liquid interface (3D-ALI) model in vitro. TGF-β1 exposure diminished EPC2-hTERT barrier function as measured by transepithelial electrical resistance (TEER) and 3kDa FITC dextran paracellular flux (FITC Flux) and H&E assessment revealed prominent cellular separation. In analysis of epithelial barrier molecules, TGF-β1 led to the specific reduction in expression of the tight-junction molecule, claudin-7 and this was prevented by TGF-β receptor I inhibitor. shRNA mediated claudin-7 knockdown diminished epithelial barrier function, while claudin-7 overexpression resulted in protection from TGF-β1-mediated barrier dysfunction. In analysis of pediatric EoE biopsies claudin-7 expression was decreased, altered localization was observed by immunofluorescence analysis and the TGF-β1 downstream transcription factor phosphorylated SMAD2/3 (pSMAD2/3) was increased. Our data suggest that TGF-β1 participates in esophageal epithelial barrier dysfunction through claudin-7 dysregulation
Eosinophil-mediated signalling attenuates inflammatory responses in experimental colitis
Objective Eosinophils reside in the colonic mucosa
and increase significantly during disease. Although a
number of studies have suggested that eosinophils
contribute to the pathogenesis of GI inflammation, the
expanding scope of eosinophil-mediated activities
indicate that they also regulate local immune responses
and modulate tissue inflammation. We sought to define
the impact of eosinophils that respond to acute phases
of colitis in mice.
Design Acute colitis was induced in mice by
administration of dextran sulfate sodium, 2,4,6-
trinitrobenzenesulfonic acid or oxazolone to C57BL/6J
(control) or eosinophil deficient (PHIL) mice. Eosinophils
were also depleted from mice using antibodies against
interleukin (IL)-5 or by grafting bone marrow from PHIL
mice into control mice. Colon tissues were collected and
analysed by immunohistochemistry, flow cytometry and
reverse transcription PCR; lipids were analysed by mass
spectroscopy.
Results Eosinophil-deficient mice developed
significantly more severe colitis, and their colon tissues
contained a greater number of neutrophils, than
controls. This compensatory increase in neutrophils was
accompanied by increased levels of the chemokines
CXCL1 and CXCL2, which attract neutrophils. Lipidomic
analyses of colonic tissue from eosinophil-deficient mice
identified a deficiency in the docosahexaenoic acidderived anti-inflammatory mediator 10, 17-
dihydroxydocosahexaenoic acid (diHDoHE), namely
protectin D1 (PD1). Administration of an exogenous
PD1-isomer (10S, 17S-DiHDoHE) reduced the severity of
colitis in eosinophil-deficient mice. The PD1-isomer also
attenuated neutrophil infiltration and reduced levels of
tumour necrosis factor-α, IL-1β, IL-6 and inducible NOsynthase in colons of mice. Finally, in vitro assays
identified a direct inhibitory effect of PD1-isomer on
neutrophil transepithelial migration.
Conclusions Eosinophils exert a protective effect in
acute mouse colitis, via production of anti-inflammatory
lipid mediators
Ultrastructural features of eosinophilic oesophagitis: impact of treatment on desmosomes
AIMS: A growing body of evidence suggests a role for altered epithelial barrier function in the pathophysiology of eosinophilic oesophagitis (EoE), but few have described the epithelial structure during inflammation. The purpose of this study was to define ultrastructural features of active, inactive EoE and control subject’s oesophageal epithelia. METHODS: We prospectively enrolled patients undergoing diagnostic upper endoscopy for evaluation of EoE. Mucosal pinch biopsies were obtained from the distal oesophagus and processed for routine histology and electron microscopic assessment. Clinical features of enrolled subjects were analysed and subjects were divided into four groups: normal, gastroesophageal reflux disease (GERD), inactive EoE and active EoE. Representative photomicrographs of the basal and superficial epithelia were reviewed for abnormalities. Desmosomes were quantified on the surface of epithelia three to four prickle-cell layers above the basal layer. RESULTS: Twenty-nine paediatric cases (ages 2–18 years) were enrolled in the study. We observed a significant decrease in the number of desmosomes per cell (DPC) of subjects with active EoE compared with inactive EoE, GERD and normal epithelia. With respect to DPC, no significant differences were found between inactive EoE compared with GERD or normal subjects. Additional ultrastructural features observed included epithelial microplicae and evidence of eosinophil transmigration, degranulation, and sombrero formation. CONCLUSIONS: Consistent with clinical and molecular findings, our ultrastructural data provide support for an altered oesophageal barrier in paediatric cases with active EoE, which may improve following treatment
Autophagy mediates epithelial cytoprotection in Eosinophilic Oesophagitis
Objective—The influence of eosinophilic oesophagitis (EoE)-associated inflammation upon oesophageal epithelial biology remains poorly understood. We investigated the functional role of autophagy in oesophageal epithelial cells (keratinocytes) exposed to the inflammatory EoE milieu.
Design—Functional consequences of genetic or pharmacological autophagy inhibition were assessed in endoscopic oesophageal biopsies, human oesophageal keratinocytes, single cell-derived ex vivo murine oesophageal organoids as well as a murine model recapitulating EoE-like inflammation and basal cell hyperplasia. Gene expression, morphological and functional characterization of autophagy and oxidative stress were performed by transmission electron microscopy, immunostaining, immunoblotting, live cell imaging and flow cytometry.
Results—EoE-relevant inflammatory conditions promoted autophagy and basal cell hyperplasia in three independent murine EoE models and oesophageal organoids. Inhibition of autophagic flux via chloroquine treatment augmented basal cell hyperplasia in these model systems. Oesophageal keratinocytes stimulated with EoE-relevant cytokines, including tumor necrosis factor-α and interleukin-13 exhibited activation of autophagic flux in a reactive oxygen species-dependent manner. Autophagy inhibition via chloroquine treatment or depletion of Beclin-1 or ATG-7, augmented oxidative stress induced by EoE-relevant stimuli in murine EoE, oesophageal organoids and human oesophageal keratinocytes. Oesophageal epithelia of pediatric EoE patients with active inflammation displayed increased autophagic vesicle content compared to normal and EoE remission subjects. Functional flow cytometric analysis revealed autophagic flux in human oesophageal biopsies.Conclusions—Our findings reveal for the first time that autophagy may function as a cytoprotective mechanism to maintain epithelial redox balance and homeostasis under EoE inflammation-associated stress, providing mechanistic insights into the role of autophagy in EoE pathogenesis
Epithelial HIF-1α/claudin-1 axis regulates barrier dysfunction in eosinophilic esophagitis
Epithelial barrier dysfunction is a significant factor in many allergic diseases, including eosinophilic esophagitis (EoE).
Infiltrating leukocytes and tissue adaptations increase metabolic demands and decrease oxygen availability at barrier
surfaces. Understanding of how these processes impact barrier is limited, particularly in allergy. Here, we identified a
regulatory axis whereby the oxygen-sensing transcription factor HIF-1α orchestrated epithelial barrier integrity, selectively
controlling tight junction CLDN1 (claudin-1). Prolonged experimental hypoxia or HIF1A knockdown suppressed HIF-1α–
dependent claudin-1 expression and epithelial barrier function, as documented in 3D organotypic epithelial cultures. L2-IL5OXA
mice with EoE-relevant allergic inflammation displayed localized eosinophil oxygen metabolism, tissue hypoxia, and impaired
claudin-1 barrier via repression of HIF-1α/claudin-1 signaling, which was restored by transgenic expression of esophageal
epithelial-targeted stabilized HIF-1α. EoE patient biopsy analysis identified a repressed HIF-1α/claudin-1 axis, which was
restored via pharmacologic HIF-1α stabilization ex vivo. Collectively, these studies reveal HIF-1α’s critical role in maintaining
barrier and highlight the HIF-1α/claudin-1 axis as a potential therapeutic target for EoE
Epithelial HIF-1α/claudin-1 axis regulates barrier dysfunction in eosinophilic esophagitis
Epithelial barrier dysfunction is a significant factor in many allergic diseases, including eosinophilic esophagitis (EoE).
Infiltrating leukocytes and tissue adaptations increase metabolic demands and decrease oxygen availability at barrier
surfaces. Understanding of how these processes impact barrier is limited, particularly in allergy. Here, we identified a
regulatory axis whereby the oxygen-sensing transcription factor HIF-1α orchestrated epithelial barrier integrity, selectively
controlling tight junction CLDN1 (claudin-1). Prolonged experimental hypoxia or HIF1A knockdown suppressed HIF-1α–
dependent claudin-1 expression and epithelial barrier function, as documented in 3D organotypic epithelial cultures. L2-IL5OXA
mice with EoE-relevant allergic inflammation displayed localized eosinophil oxygen metabolism, tissue hypoxia, and impaired
claudin-1 barrier via repression of HIF-1α/claudin-1 signaling, which was restored by transgenic expression of esophageal
epithelial-targeted stabilized HIF-1α. EoE patient biopsy analysis identified a repressed HIF-1α/claudin-1 axis, which was
restored via pharmacologic HIF-1α stabilization ex vivo. Collectively, these studies reveal HIF-1α’s critical role in maintaining
barrier and highlight the HIF-1α/claudin-1 axis as a potential therapeutic target for EoE