Mucosal integrity and sensitivity to acid in the proximal esophagus in patients with gastroesophageal reflux disease.

Acid reflux episodes that extend to the proximal esophagus are more likely to be perceived. This suggests that the proximal esophagus is more sensitive to acid than the distal esophagus, which could be caused by impaired mucosal integrity in the proximal esophagus. Our aim was to explore sensitivity to acid and mucosal integrity in different segments of the esophagus. We used a prospective observational study, including 12 patients with gastroesophageal reflux disease (GERD). After stopping acid secretion-inhibiting medication, two procedures were performed: an acid perfusion test and an upper endoscopy with electrical tissue impedance spectroscopy and esophageal biopsies. Proximal and distal sensitivity to acid and tissue impedance were measured in vivo, and mucosal permeability and epithelial intercellular spaces at different esophageal levels were measured in vitro. Mean lag time to heartburn perception was much shorter after proximal acid perfusion (0.8 min) than after distal acid perfusion (3.9 min) (P = 0.02). Median in vivo tissue impedance was significantly lower in the distal esophagus (4,563 Ω·m) compared with the proximal esophagus (8,170 Ω·m) (P = 0.002). Transepithelial permeability, as measured by the median fluorescein flux was significantly higher in the distal (2,051 nmol·cm(-2)·h(-1)) than in the proximal segment (368 nmol·cm(-2)·h(-1)) (P = 0.033). Intercellular space ratio and maximum heartburn intensity were not significantly different between the proximal and distal esophagus. In GERD patients off acid secretion-inhibiting medication, acid exposure in the proximal segment of the esophagus provokes symptoms earlier than acid exposure in the distal esophagus, whereas mucosal integrity is impaired more in the distal esophagus. These findings indicate that the enhanced sensitivity to proximal reflux episodes is not explained by increased mucosal permeability.

Histological Response to Fluticasone Propionate in Patients With Eosinophilic Esophagitis Is Associated With Improved Functional Esophageal Mucosal Integrity.

OBJECTIVES: The esophageal mucosal integrity is impaired in patients with eosinophilic esophagitis (EoE). We aimed to evaluate the effect of fluticasone propionate on inflammation and functional and structural markers of esophageal mucosal barrier integrity in adult patients with EoE. METHODS: In this prospective study, we included 15 EoE patients (median age (IQR), 43 (30-45) years). Patients underwent upper endoscopy before and after an 8-week course of swallowed fluticasone propionate 500 µg BID. Several parameters of esophageal mucosal barrier integrity were evaluated: esophageal electrical tissue impedance in vivo during endoscopy, transepithelial electrical resistance (TER) and transepithelial molecule flux in Ussing chambers using esophageal biopsy specimens, and intercellular spaces as a structural marker of permeability using electron microscopy. Esophageal eosinophils and mast cells were counted, and expression of inflammatory cytokines and barrier integrity proteins was investigated using qPCR. Esophageal symptoms and signs were also assessed. RESULTS: Peak eosinophil and mast cell counts decreased significantly after fluticasone propionate treatment. The esophageal mucosal integrity increased substantially during treatment, as shown by increased extracellular impedance and TER (both P<0.01) and decreased transepithelial molecule flux in Ussing chambers (P<0.05). Whereas expression of genes encoding for inflammatory cytokines (IL5, IL13, eotaxin-3, periostin, TSLP) decreased after treatment, expression of genes encoding for barrier integrity proteins (filaggrin and desmoglein-1) increased. CONCLUSIONS: Fluticasone propionate treatment decreases eosinophilic inflammation and improves the esophageal mucosal barrier integrity in adult EoE patients. Improvement of the mucosal barrier integrity correlates with normalization of expression of desmoglein-1 and filaggrin marker genes.

Proton pump inhibitors partially restore mucosal integrity in patients with proton pump inhibitor-responsive esophageal eosinophilia but not eosinophilic esophagitis.

BACKGROUND & AIMS: Histologic analysis is used to distinguish patients with proton pump inhibitor-responsive eosinophilia (PPI-REE) from those with eosinophilic esophagitis (EoE). It is not clear whether these entities have different etiologies. Exposure to acid reflux can impair the integrity of the esophageal mucosal. We proposed that patients with EoE and PPI-REE might have reflux-induced esophageal mucosal damage that promotes transepithelial flux of allergens. We therefore assessed the integrity of the esophageal mucosal in these patients at baseline and after PPI. METHODS: We performed a prospective study of 16 patients with suspected EoE and 11 controls. Patients had dysphagia, endoscopic signs of EoE, and esophageal eosinophilia (>15 eosinophils/high-power field [eos/hpf]). All subjects underwent endoscopy at baseline; endoscopy was performed again on patients after 8 weeks of treatment with high-dose esomeprazole. After PPI treatment, patients were diagnosed with EoE (>10 eos/hpf; n = 8) or PPI-REE (≤10 eos/hpf; n = 8). We evaluated the structure (intercellular spaces) and function (electrical tissue impedance, transepithelial electrical resistance, transepithelial molecule flux) of the esophageal mucosal barrier. RESULTS: Compared with controls, electrical tissue impedance and transepithelial electrical resistance were reduced in patients with EoE (P < .001 and P < .001, respectively) and PPI-REE (P = .01 and P = .06, respectively), enabling transepithelial small-molecule flux. PPI therapy partially restored these changes in integrity and inflammation in patients with PPI-REE, but not in those with EoE. CONCLUSIONS: The integrity of the esophageal mucosa is impaired in patients with EoE and PPI-REE, allowing transepithelial transport of small molecules. PPI therapy partially restores mucosal integrity in patients with PPI-REE, but not in those with EoE. Acid reflux might contribute to transepithelial allergen flux in patients with PPI-REE. Trialregister.nl number: NTR3480.

The dopaminergic system in patients with functional dyspepsia analysed by single photon emission computed tomography (SPECT) and an alpha-methyl-para-tyrosine (AMPT) challenge test.

PURPOSE: Functional dyspepsia (FD) is a chronic condition characterized by upper abdominal symptoms without an identifiable cause. While the serotonergic system is thought to play a key role in the regulation of gut physiology, the role of the dopaminergic system, which is important in the regulation of visceral pain and stress, is under-studied. Therefore, this study investigated the dopaminergic system and its relationship with drinking capacity and symptoms in FD patients. METHODS: In FD patients and healthy volunteers (HV) the dopaminergic system was investigated by in-vivo assessment of central dopamine D2 receptors (D2Rs) with [(123)I]IBZM SPECT and by an acute, but reversible, dopamine depletion alpha-methyl-para-tyrosine (AMPT) challenge test. A nutrient drink test was performed to investigate the association between maximal ingested volume, evoked symptoms, and D2Rs. RESULTS: The HV subjects comprised 12 women and 8 men (mean age 31 ± 3 years), and the FD patients comprised 5 women and 3 men (mean age 39 ± 5 years). The FD patients had a lower left plus right average striatal binding potential (BP(NP)) for the caudate nucleus (p = 0.02), but not for putamen (p = 0.15), which in the FD patients was correlated with maximal ingested volume (r = 0.756, p = 0.03). The D2R BP(NP) in the putamen was correlated with nausea (r = 0.857, p = 0.01). The acute dopamine depletion test, however, failed to reveal differences in prolactin release between the FD patients and the HV subjects. CONCLUSION: These preliminary data suggest that chronic rather than acute alterations in the dopaminergic system may be involved in the pathogenesis of FD. Further studies are required to reproduce our novel findings and to evaluate to what extent the dopaminergic changes may be secondary to abnormalities in serotonergic pathways.

Autoimmune aspects of depigmentation in vitiligo.

Autoimmune depigmentation of the skin, vitiligo, afflicts a considerable number of people, yet no effective therapeutic modalities have been developed to treat it. In part, this can be attributed to the obscure etiology of the disease, which has begun to reveal itself only recently. It is known that pigment is lost as a function of reduced melanocyte numbers in the epidermis, and that depigmentation is accompanied by T cell influx to the skin in the vast majority of patients. Characterizing such infiltrating T cells as type 1 proinflammatory cytokine-secreting cells reactive with melanocyte-specific antigen is a major step toward effective therapy. Melanoma research has shown that differentiation antigens, also expressed by normal melanocytes, can be immunogenic when expressed in the melanosomal compartment of the cell. Similar reactivity to melanosomal antigens is apparent for T cells infiltrating vitiligo skin. It may eventually be possible to treat patients with decoy antigens that anergize such Tcells, or to prevent recruitment of the T cells to the skin altogether. In this respect, it is important that T cells are recruited to the skin as a function of dendritic cell activation and that dendritic cells are likely activated at sites of epidermal trauma as a consequence of stress proteins that spill over into the microenvironment. Stress proteins chaperoning antigens representative of the cells from which they were derived are then processed by dendritic cells and contribute to their activation. Activated dendritic cells not only migrate to draining lymph nodes to recruit T cells but may execute cytotoxic effector functions as well. The contribution of the effector functions to actual depigmentation of the skin remains to be investigated.

Immunopolarization of CD4+ and CD8+ T cells to Type-1-like is associated with melanocyte loss in human vitiligo.

Vitiligo is an autoimmune condition characterized by loss of epidermal melanocytes. High frequencies of melanocyte-reactive cytotoxic T cells in the peripheral blood of vitiligo patients and the observed correlation between perilesional T-cell infiltration and melanocyte loss in situ suggest the important role of cellular autoimmunity in the pathogenesis of this disease. We isolated T cells from both perilesional and nonlesional skin biopsies obtained from five vitiligo patients, then cloned and analyzed their profile of cytokine production after short-term, nonspecific expansion in vitro. Perilesional T-cell clones (TCC) derived from patients with vitiligo exhibited a predominant Type-1-like cytokine secretion profile, whereas the degree of Type-1 polarization in uninvolved skin-derived TCC correlated with the process of microscopically observed melanocyte destruction in situ. Detailed analysis of broad spectrum of cytokines produced by perilesional- and nonlesional-derived CD4+ and CD8+ TCC confirmed polarization toward Type-1-like in both CD4 and CD8 compartments, which paralleled depigmentation process observed locally in the skin. Furthermore, CD8+ TCC derived from two patients also were analyzed for reactivity against autologous melanocytes. The antimelanocyte cytotoxic reactivity was observed among CD8+ TCC isolated from perilesional biopsies of two patients with vitiligo. Finally, in two of five patients, tetramer analysis revealed presence of high frequencies of Mart-1-specific CD8 T cells in T-cell lines derived from perilesional skin. Altogether our data support the role of cellular mechanisms playing a significant part in the destruction of melanocytes in human autoimmune vitiligo.