Pseudomonas aeruginosa-derived flagellin stimulates IL-6 and IL-8 production in human bronchial epithelial cells: A potential mechanism for progression and exacerbation of COPD.

Background and purpose of the study:Pseudomonas aeruginosa commonly colonizes the airway of patients with chronic obstructive pulmonary disease (COPD) and exacerbates their symptoms. P. aeruginosa carries flagellin that stimulates toll-like receptor (TLR)-5; however, the role of flagellin in the pathogenesis of COPD remains unclear. The aim of the study was to evaluate the mechanisms of the flagellin-induced innate immune response in bronchial epithelial cells, and to assess the effects of anti-inflammatory agents for treatment. Materials and methods: We stimulated BEAS-2B cells with P. aeruginosa-derived flagellin, and assessed mRNA expression and protein secretion of interleukin (IL)-6 and IL-8. We also used mitogen-activated protein kinases (MAPK) inhibitors to assess the signaling pathways involved in flagellin stimulation, and investigated the effect of clinically available anti-inflammatory agents against flagellin-induced inflammation. Results: Flagellin promoted protein and mRNA expression of IL-6 and IL-8 in BEAS-2B cells and induced phosphorylation of p38, ERK, and JNK; p38 phosphorylation-induced IL-6 production, while IL-8 production resulted from p38 and ERK phosphorylation. Fluticasone propionate (FP) and dexamethasone (DEX) suppressed IL-6 and IL-8 production in BEAS-2B cells, but clarithromycin (CAM) failed to do so. Conclusions:P. aeruginosa-derived flagellin-induced IL-6 and IL-8 production in bronchial epithelial cells, which partially explains the mechanisms of progression and exacerbation of COPD. Corticosteroids are the most effective treatment for the suppression of flagellin-induced IL-6 and IL-8 production in the bronchial epithelial cells.

Bronchial epithelial cells produce CXCL1 in response to LPS and TNFα: A potential role in the pathogenesis of COPD.

RATIONALE: Neutrophilic airway inflammation plays a central role in chronic obstructive pulmonary disease (COPD). CXC chemokine ligand (CXCL)1 is a neutrophil chemokine involved in the pathogenesis of COPD. However, its clinical significance in COPD patients is poorly understood. AIM OF THE STUDY: To assess the production of CXCL1 by bronchial epithelial cells in response to lipopolysaccharide (LPS) and tumor necrosis factor (TNF)α. MATERIALS AND METHODS: We measured sputum CXCL1 and CXCL8 levels in patients with COPD, asthma, and asthma-COPD overlap (ACO), and compared them to those of patients with interstitial pneumonia (IP). Using primary human bronchial epithelial cells and BEAS-2B cells, CXCL1 protein release and mRNA expression were measured after LPS or TNFα stimulation. We evaluated signal transduction mechanisms for CXCL1 production using nuclear factor-κ B (NF-kB) and mitogen-activated protein kinase (MAPK) inhibitors, and examined the effects of anti-inflammatory agents on CXCL1 production in BEAS-2B cells. RESULTS: Sputum CXCL1 levels in COPD and ACO patients were higher than in IP patients, whereas sputum CXCL8 levels were not. Sputum CXCL1 levels were not affected by inhaled corticosteroid usage, whereas sputum CXCL8 levels tended to be affected. LPS and TNFα stimulated CXCL1 production and mRNA expression in bronchial epithelial cells. NF-kB and MAPK p38 were involved in LPS-induced CXCL1 production. Therapeutic anti-inflammatory agents minimally attenuated CXCL1 production and considerably inhibited CXCL8 production in BEAS-2B cells. CONCLUSIONS: Sputum CXCL1 levels is a potentially better diagnostic marker for COPD than sputum CXCL8 levels, which is explained by that CXCL1 production in bronchial epithelial cells is less affected by therapeutic anti-inflammatory agents than CXCL8 production.

IL-17A synergistically stimulates TNF-α-induced IL-8 production in human airway epithelial cells: A potential role in amplifying airway inflammation.

BACKGROUND: Recent reports have suggested an involvement of neutrophilic inflammation driven by interleukin (IL)-17 from Th17 cells, especially in severe, refractory asthma. It remains unknown about the possible interactions of this cytokine and other proinflammatory cytokines to direct neutrophilic airway inflammation. MATERIALS AND METHODS: We evaluated the effects of IL-17A, IL-17E, and IL-17F in combination with other stimuli such as tumor necrosis factor (TNF) -α on the production and expression of IL-8 in human bronchial epithelial cells. We also studied their effects on other cytokine production. The possible role of mitogen-activated protein kinase (MAPK) and nuclear factor-kappa B (NF-κB) signaling pathways was evaluated by specific inhibitors. We examined the effects of anti-asthma drugs, such as steroids or salmeterol. RESULTS: IL-17A alone induced only a minimal effect on IL-8 expression. IL-17A, but not IL-17E or IL-17F, in combination with TNF-α showed a synergistic effect on IL-8 expression. Similar findings were found when combination with IL-1ß and IL-17A were used, but such was not the case with lipopolysaccharide (LPS). In addition, we further found such synergy on GM-CSF production. The synergy with TNF-α and IL-17A was significantly inhibited by MAPKs inhibitors. Corticosteroids such as fluticasone propionate and dexamethasone, but not salmeterol, partially suppressed the IL-17A and TNF-α-induced IL-8 production. CONCLUSIONS: IL-17A in the combination with TNF-α or IL-1ß showed a synergistic augmenting effect on IL-8 and GM-CSF production in human airway epithelial cells.

Clarithromycin ameliorates pulmonary inflammation induced by short term cigarette smoke exposure in mice.

BACKGROUND: Cigarette smoking is considered to be one of major causes of acute worsening of asthma as well as chronic obstructive pulmonary disease (COPD). Macrolide antibiotics have been reported to reduce the risk of exacerbations of COPD, and possibly neutrophilic asthma. However, the effect of clarithromycin (CAM) on pulmonary inflammation caused by short term exposure to cigarette smoke still remains to be investigated. METHODS: C57BL/6J female mice were daily exposed to tobacco smoke using a tobacco smoke exposure system, or clean air for 8 days, while simultaneously treated with either oral CAM or vehicles. Twenty four hours after the last exposure, mice were anaesthetized and sacrificed, and bronchoalveolar lavage (BAL) fluids were collected. Cellular responses in BAL fluids were evaluated. Levels of cytokine mRNA in the lung tissues were measured by quantitative RT-PCR. Paraffin-embedded lung tissues were evaluated to quantitate degree of neutrophil infiltration. RESULTS: The numbers of total cells, macrophages and neutrophils in the BAL fluid of smoke-exposed mice were significantly increased as compared to clean air group. These changes were significantly ameliorated in CAM-treated mice. The lung morphological analysis confirmed decrease of neutrophils by CAM treatment. Studies by quantitative PCR demonstrated CAM treatment significantly reduced lung expression levels of IL-17A, keratinocyte-derived chemokine (KC), granulocyte-macrophage colony stimulating factor (GM-CSF) and MMP-9 induced by cigarette smoke. CONCLUSION: We demonstrate that CAM administration resolves enhanced pulmonary inflammation induced by short term cigarette smoke exposure in mice.

Interleukin-10 modulates pulmonary neutrophilic inflammation induced by cigarette smoke exposure.

AIM OF THE STUDY: Interleukin (IL)-10 is an anti-inflammatory cytokine, but its role in cigarette smoke (CS)-induced inflammation and chronic obstructive pulmonary disease (COPD) has not been fully elucidated. The purpose of this study was to investigate the effect of IL-10 deficiency on CS-induced pulmonary inflammation in mice in vivo and in vitro. MATERIALS AND METHODS: IL-10-deficient and wild-type control mice with a C57BL6/J genetic background were exposed to CS, and inflammatory cells in bronchoalveolar lavage fluid (BALF) and mRNA of cytokines in lung were evaluated with enzyme-linked immunosorbent assay (ELISA) and reverse transcription polymerase chain reaction (RT-PCR). RESULTS: During 12 days of daily CS exposure to wild-type mice, neutrophil counts in BAL fluid and tumor necrosis factor (TNF)-α mRNA expression were increased, peaked at day 8, and then declined on day 12 when the level of IL-10 reached its peak. In IL-10-deficient mice, neutrophil recruitment and TNF-α mRNA levels induced by CS exposure were significantly greater than those in wild-type mice. Keratinocyte-derived chemokine (KC; murine ortholog of human CXCL8) and granulocyte macrophage colony-stimulating factor (GM-CSF) mRNA levels or matrix metalloproteinase(MMP)-9 protein levels were not correlated with neutrophil count. CONCLUSIONS: IL-10 had a modulatory effect on CS-induced pulmonary neutrophilic inflammation and TNF-α expression in mice in vivo and therefore appears to be an important endogenous suppressor of airway neutrophilic inflammation.

Serial quantification of procalcitonin (PCT) predicts clinical outcome and prognosis in patients with community-acquired pneumonia (CAP).

Procalcitonin (PCT), a calcitonin precursor, is commonly measured in the setting of community-acquired pneumonia (CAP). However, the clinical significance of serial PCT changes has not been established. We conducted a prospective observational study of 122 patients with CAP. Thirty-day mortality was the primary endpoint. Secondary endpoints included: (1) initial treatment failure, (2) 30-day mortality and/or initial treatment failure, and (3) intensive care unit (ICU) admission. In subgroup analysis, we classified patients into pneumococcal pneumonia and non-pneumococcal pneumonia groups. The baseline frequency of 30-day mortality was 10.7%. Increases in serum PCT levels from admission to Day 3 were observed with statistically higher frequency in patients with 30-day mortality (P = 0.002). For secondary endpoints, only the 30-day mortality and/or initial treatment failure group was statistically significant (P = 0.007). Subgroup analysis revealed statistically significant changes in the non-pneumococcal pneumonia group (N = 85) across several endpoints, including 30-day mortality (P = 0.001), initial treatment failure (P = 0.013), and 30-day mortality and/or initial treatment failure (P < 0.001). No significant changes in endpoint measurements were found in the pneumococcal pneumonia group (N = 28). Interestingly, serum PCT levels at the time of diagnosis were higher in patients with pneumococcal pneumonia than those with non-pneumococcal pneumonia (P = 0.006), and this positively correlated with disease severity scores for all patients (PCT vs. PSI: R = 0.380, P < 0.001; PCT vs. A-DROP: R = 0.422, P < 0.001) and for non-pneumococcal pneumonia (PCT vs. PSI: R = 0.468, P < 0.001; PCT vs. A-DROP: R = 0.448, P < 0.001), but not for pneumococcal pneumonia. In conclusion, serial quantification of PCT can predict clinical outcomes for patients with CAP.

Kinetics of c-reactive protein (CRP) and serum amyloid A protein (SAA) in patients with community-acquired pneumonia (CAP), as presented with biologic half-life times.

Context: In management of community-acquired pneumonia (CAP), excellent biomarkers for inflammation would be helpful in our practice. Objectives: Kinetics of c-reactive protein (CRP) and serum amyloid A (SAA) was characterized, using their biologic half-life times. Materials and methods: Time course of CRP and SAA levels in the successfully treated 36 CAP patients were investigated and their half-life times were determined and compared. Results & Discussions: SAA and CRP declined in an exponential mean and the biologic half-life times of SAA levels was 34.9 ± 28.7 h, significantly shorter than that of CRP, 46.4 ± 21.7 h (p = 0.0014). Conclusion: The kinetic evidence, presented as biologic half-life times of CRP and SAA, helps us make a clinical assessment of CAP patients.

Ruxolitinib inhibits poly(I:C) and type 2 cytokines-induced CCL5 production in bronchial epithelial cells: A potential therapeutic agent for severe eosinophilic asthma.

RATIONALE: Severe eosinophilic asthma is characterized by airway eosinophilia and corticosteroid-resistance, commonly overlapping with type 2 inflammation. It has been reported that chemokine (C-C motif) ligand 5 (CCL5) is involved in the exacerbation of asthma by RNA virus infections. Indeed, treatment with a virus-associated ligand and a T helper type 2 cell (Th2) cytokine can synergistically stimulate CCL5 production in bronchial epithelial cells. We aimed to evaluate the mechanisms underlying CCL5 production in this in vitro model and to assess the potential of Janus kinase 1 (JAK1) as a novel therapeutic target via the use of ruxolitinib. METHODS: We stimulated primary normal human bronchial epithelial (NHBE) cells and BEAS-2B cells with poly(I:C) along with interleukin-13 (IL-13) or IL-4, and assessed CCL5 production. We also evaluated the signals involved in virus- and Th2-cytokine-induced CCL5 production and explored a therapeutic agent that attenuates the CCL5 production. RESULTS: Poly(I:C) stimulated NHBE and BEAS-2B cells to produce CCL5. Poly(I:C) and IL-13 increased CCL5 production. Poly(I:C)-induced CCL5 production occurred via the TLR3-IRF3 and IFNAR/JAK1-phosphoinositide 3-kinase (PI3K) pathways, but not the IFNAR/JAK1-STATs pathway. In addition, IL-13 did not augment poly(I:C)-induced CCL5 production via the canonical IL-13R/IL-4R/JAK1-STAT6 pathway but likely via subsequent TLR3-IRF3-IFNAR/JAK1-PI3K pathways. JAK1 was identified to be a potential therapeutic target for severe eosinophilic asthma. The JAK1/2 inhibitor, ruxolitinib, was demonstrated to more effectively decrease CCL5 production in BEAS-2B cells than fluticasone propionate. CONCLUSION: We have demonstrated that JAK1 is a possible therapeutic target for severe corticosteroid-resistant asthma with airway eosinophilia and persistent Th2-type inflammation, and that ruxolitinib has potential as an alternative pharmacotherapy.

Dual interleukin-17A/F deficiency protects against acute and chronic response to cigarette smoke exposure in mice.

IL-17A and IL-17F are both involved in the pathogenesis of neutrophilic inflammation observed in COPD and severe asthma. To explore this, mice deficient in both Il17a and Il17f and wild type (WT) mice were exposed to cigarette smoke or environmental air for 5 to 28 days and changes in inflammatory cells in bronchoalveolar lavage (BAL) fluid were determined. We also measured the mRNA expression of keratinocyte derived chemokine (Kc), macrophage inflammatory protein-2 (Mip2), granulocyte-macrophage colony stimulating factor (Gmcsf) and matrix metalloproteinase-9 (Mmp9 ) in lung tissue after 8 days, and lung morphometric changes after 24 weeks of exposure to cigarette smoke compared to air-exposed control animals. Macrophage counts in BAL fluid initially peaked at day 8 and again on day 28, while neutrophil counts peaked between day 8 and 12 in WT mice. Mice dual deficient with Il17a and 1l17f showed similar kinetics with macrophages and neutrophils, but cell numbers at day 8 and mRNA expression of Kc, Gmcsf and Mmp9 were significantly reduced. Furthermore, airspaces in WT mice became larger after cigarette smoke exposure for 24 weeks, whereas this was not seen dual Il17a and 1l17f deficient mice. Combined Il17a and Il17f deficiency resulted in significant attenuation of neutrophilic inflammatory response and protection against structural lung changes after long term cigarette smoke exposure compared with WT mice. Dual IL-17A/F signalling plays an important role in pro-inflammatory responses associated with histological changes induced by cigarette smoke exposure.

Acid-suppressive effects of rabeprazole, omeprazole, and lansoprazole at reduced and standard doses: a crossover comparative study in homozygous extensive metabolizers of cytochrome P450 2C19.

BACKGROUND AND OBJECTIVES: To improve clinical outcomes of the initial therapy for gastroesophageal reflux disease, intragastric pH should be above 4.0 for more than 20 hours a day (83.3%) and nocturnal gastric acid breakthrough, defined as 60 continuous minutes of intragastric pH below 4.0 at night, should be inhibited. A "step-down" therapy sometimes fails because of insufficient acid suppression. Therefore we compared the acid-suppressive effects of proton pump inhibitors. METHODS: This was a prospective, randomized, open-label, 8-way crossover study. In 9 healthy Helicobacter pylori-negative cytochrome P450 (CYP) 2C19 homozygous extensive metabolizers, intragastric pH was measured for 24 hours on day 7 of treatment with rabeprazole, omeprazole, and lansoprazole orally administered once daily at reduced and standard doses. RESULTS: Compared with baseline data (7% [range, 5%-20%]), the median values of the 24-hour percent of time that intragastric pH was above 4.0 significantly increased but did not exceed 83.3% under any of the 7 regimens, which were as follows: 10 mg rabeprazole (51% [range, 28%-78%], P < .01), 20 mg rabeprazole (59% [range, 36%-83%], P < .01), 10 mg omeprazole (26% [range, 4%-33%], P < .05), 20 mg omeprazole (48% [range, 31%-73%], P < .01), 40 mg omeprazole (62% [range, 47%-87%], P < .01), 15 mg lansoprazole (34% [range, 5%-51%], P < .05), and 30 mg lansoprazole (56% [range, 20%-76%], P < .05). Significant differences were observed among 10, 20, and 40 mg omeprazole (10 mg versus 20 mg, P < .01; 10 mg versus 40 mg, P < .01; and 20 mg versus 40 mg, P < .05) and between 15 and 30 mg lansoprazole (P < .01), whereas no significant difference was observed between 10 and 20 mg rabeprazole. Nocturnal gastric acid breakthrough was observed under all regimens. CONCLUSIONS: Rabeprazole, omeprazole, and lansoprazole, given once daily at standard doses, cannot be expected to achieve ideal acid suppression for the initial therapy for gastroesophageal reflux disease in Helicobacter-negative CYP2C19 homozygous extensive metabolizers. Rabeprazole 10 mg may be appropriate for step-down therapy.

Serum Reactive Oxygen Metabolite Levels Predict Severe Exacerbations of Asthma.

BACKGROUND AND PURPOSE: Bronchial asthma (BA) is a chronic airway disease characterized by airway hyperresponsiveness and remodeling, which are intimately linked to chronic airway inflammation. Reactive oxygen species (ROS) such as hydrogen peroxide are generated by inflammatory cells that are involved in the pathogenesis of BA. However, the role of ROS in the management of BA patients is not yet clear. We attempted to determine the role of ROS as a biomarker in the clinical setting of BA. SUBJECTS AND METHODS: We enrolled patients with BA from 2013 through 2015 and studied the degrees of asthma control, anti-asthma treatment, pulmonary function test results, fractional exhaled nitric oxide (FeNO), serum reactive oxygen metabolite (ROM) levels, and serum levels of interleukin (IL)-6 and IL-8. RESULTS: We recruited 110 patients with BA. Serum ROM levels correlated with white blood cell (WBC) count (rs = 0.273, p = 0.004), neutrophil count (rs = 0.235, p = 0.014), CRP (rs = 0.403, p < 0.001), and IL-6 (rs = 0.339, p < 0.001). Serum ROM levels and IL-8 and CRP levels negatively correlated with %FEV1 (rs = -0.240, p = 0.012, rs = -0.362, p < 0.001, rs = -0.197, p = 0.039, respectively). Serum ROM levels were significantly higher in patients who experienced severe exacerbation within 3 months than in patients who did not (339 [302-381] vs. 376 [352-414] CARR U, p < 0.025). Receiver-operating characteristics analysis showed that ROM levels correlated significantly with the occurrence of severe exacerbation (area under the curve: 0.699, 95% CI: 0.597-0.801, p = 0.025). CONCLUSIONS: Serum levels of ROM were significantly associated with the degrees of airway obstruction, WBC counts, neutrophil counts, IL-6, and severe exacerbations. This biomarker may be useful in predicting severe exacerbations of BA.

Soluble ST2 as a prognostic marker in community-acquired pneumonia.

OBJECTIVES: Community-acquired pneumonia (CAP) is associated with high mortality when initial treatment fails. Early identification of these patients allows physicians to modify treatments earlier, increasing survival. METHODS: Ninety-one hospitalized patients with CAP were studied. Serum soluble ST2 levels were measured at diagnosis and at 3, 7, and 14 days (days 0, 3, 7, and 14) after the initiation of antimicrobial treatment. The predictive value of all-cause in-hospital mortality and the additive effect of soluble ST2 on the pneumonia severity index (PSI) were evaluated. RESULTS: In univariate analysis, high serum levels of soluble ST2 at days 0, 3, 7, and 14 were predictive of death (hazard ratios: 3.1, 10.0, 12.0, and 22.6, respectively). In multivariate analysis, a combination of soluble ST2 at day 3 (above 2700 pg/ml) and PSI were predictive of death with higher accuracy than PSI alone (net reclassification improvement, 0.44; integrated discrimination improvement, 0.17; P = 0.001 for both). Specifically, simultaneous presence of high soluble ST2 (day 3) and a PSI of 5 was suggestive of higher mortality risk than a PSI of 5 alone (mortality 78% vs. 39%, respectively). CONCLUSIONS: Soluble ST2 is prognostic indicator of CAP and can add to the predictive value of the PSI.

Anacardic acid, a histone acetyltransferase inhibitor, modulates LPS-induced IL-8 expression in a human alveolar epithelial cell line A549.

OBJECTIVE AND DESIGN: The histone acetylation processes, which are believed to play a critical role in the regulation of many inflammatory genes, are reversible and regulated by histone acetyltransferases (HATs), which promote acetylation, and histone deacetylases (HDACs), which promote deacetylation. We studied the effects of lipopolysaccharide (LPS) on histone acetylation and its role in the regulation of interleukin (IL)-8 expression.  MATERIAL: A human alveolar epithelial cell line A549 was used in vitro. METHODS: Histone H4 acetylation at the IL-8 promoter region was assessed by a chromatin immunoprecipitation (ChIP) assay. The expression and production of IL-8 were evaluated by quantitative polymerase chain reaction and specific immunoassay. Effects of a HDAC inhibitor, trichostatin A (TSA), and a HAT inhibitor, anacardic acid, were assessed.  RESULTS: Escherichia coli-derived LPS showed a dose- and time-dependent stimulatory effect on IL-8 protein production and mRNA expression in A549 cells in vitro. LPS showed a significant stimulatory effect on histone H4 acetylation at the IL-8 promoter region by ChIP assay. Pretreatment with TSA showed a dose-dependent stimulatory effect on IL-8 release from A549 cells as compared to LPS alone. Conversely, pretreatment with anacardic acid inhibited IL-8 production and expression in A549 cells.  CONCLUSION: These data suggest that LPS-mediated proinflammatory responses in the lungs might be modulated via changing chromatin remodeling by HAT inhibition.

Guillain-Barré syndrome in two patients with respiratory failure and a review of the Japanese literature.

We described two patients with Guillain-Barré syndrome and respiratory failure with or without mechanical ventilation. Case 1 was a 44-year-old man who treated as pneumonia under mechanical ventilation for a month and transferred to our hospital with unsuccessful weaning trials because of phrenic nerve palsy. Case 2 was a 74-year-old man who presented with aspiration pneumonia because of bulbar palsy. The present two cases with review of the Japanese literature showed that antecedent infection with initial symptoms within the most recent 5 to 46 days is a clinical clue to the diagnosis even in patients with Guillain-Barré syndrome accompanied by respiratory failure.

Lafutidine, a newly developed antiulcer drug, elevates postprandial intragastric pH and increases plasma calcitonin gene-related peptide and somatostatin concentrations in humans: comparisons with famotidine.

Lafutidine, a newly developed histamine H(2)-receptor antagonist, inhibits daytime (i.e., postprandial) as well as nighttime gastric acid secretion in clinical studies. It also has gastroprotective activity that particularly affects mucosal blood flow in rats. This study focused on the efficacy of lafutidine on plasma concentrations of gastrointestinal peptides in humans. Six healthy male volunteers aged 23-32 years without Helicobacter pylori infection were orally administered either 10 mg lafutidine, 20 mg famotidine, or water only (control) 30 min after a standard meal (650 kcal). Plasma concentrations of lafutidine and famotidine were highest from 90 to 150 min after administration. Intragastric pH was elevated after both lafutidine and famotidine compared with the control. Plasma concentrations of calcitonin gene-related peptide (CGRP) and somatostatin were significantly increased after lafutidine at 60 and 90 min. We concluded that lafutidine increases plasma concentrations of CGRP and somatostatin in humans, which may result in inhibition of postprandial acid secretion and gastroprotective activity.

Acid-suppressive efficacy of a reduced dosage of rabeprazole: comparison of 10 mg twice daily rabeprazole with 20 mg twice daily rabeprazole, 30 mg twice daily lansoprazole, and 20 mg twice daily omeprazole by 24-hr intragastric pH-metry.

Rabeprazole achieves more potent acid suppression than other proton pump inhibitors. Therefore it is administered at reduced as well as high dosages in eradication therapy for Helicobacter pylori; however, there is incomplete assessment of the efficacy of a reduced dosage of rabeprazole as might be employed in therapy. In this study, we evaluated acid-suppressive efficacy of a reduced dosage of rabeprazole on day 7 by 24-hr pH-metry in 10 healthy male cytochrome P-450 2C19 extensive metabolizers without Helicobacterpylori infection and compared the results with those of high dosages of rabeprazole, lansoprazole, and omeprazole. Median intragastric pH value, pH >3 holding time ratio (pH>3HT), pH>4HT, pH>5HT, pH>6HT, and pH>7HT for 24 hr with rabeprazole, 10 mg twice daily, were not significantly different from those of rabeprazole, 20 mg twice daily, lansoprazole, 30 mg twice daily, and omeprazole, 20 mg twice daily. In conclusion, for acid-suppressive efficacy, a reduced dosage of rabeprazole is comparable to high dosages of rabeprazole, lansoprazole, and omeprazole.

Gastric acid normosecretion is not essential in the pathogenesis of mild erosive gastroesophageal reflux disease in relation to Helicobacter pylori status.

In the pathogenesis of gastroesophageal reflux disease (GERD), gastric acid is considered to be one of the most important factors, but little is known about the degree of gastric acid secretion in GERD patients. In this study, we evaluated it in GERD patients and control subjects by 24-h intragastric pH, and serological and histological investigations, in relation to Helicobacter pylori (H. pylori) status. In H. pylori-negative GERD patients gastric acid secretion was similar to that in H. pylori-negative control subjects. In H. pylori-positive GERD patients, in particular, mild GERD patients, it decreased significantly compared to that in H. pylori-negative control subjects, but the degree of decrease was smaller than in H. pylori-positive control subjects. Results of serological and histological evaluation were supportive. In conclusion, in some GERD patients, gastric acid secretion was significantly decreased. Increased or maintained gastric acid secretion was not essential in the pathogenesis of mild GERD.