A new mechanism for anti-inflammatory actions of proton pump inhibitors--inhibitory effects on neutrophil-endothelial cell interactions

Potential anti-inflammatory effects of proton pump inhibitors: a review and discussion of the clinical implications

Proton pump inhibitors (PPIs) are potent blockers of gastric acid secretion, and are widely regarded as the agents of choice for the treatment of acid-peptic disorders. For patients with upper gastrointestinal symptoms of uncertain etiology, improvement with PPI therapy is considered prima facie evidence of a pathogenetic role for acid-peptic disease. In addition to anti-secretory effects, however, PPIs have been found to have anti-oxidant properties and direct effects on neutrophils, monocytes, endothelial, and epithelial cells that might prevent inflammation. Those anti-inflammatory effects of the PPIs might influence a variety of inflammatory disorders, both peptic and non-peptic, within and outside of the gastrointestinal tract. The purpose of this report is to review the mechanisms whereby PPIs might exert anti-inflammatory effects exclusive of gastric acid inhibition, to discuss the clinical implications of those effects, and to emphasize that a clinical response to PPIs should not be construed as proof for an underlying acid-peptic disorder.

Prevention of NSAID-Induced Small Intestinal Mucosal Injury: Prophylactic Potential of Lansoprazole

Non-steroidal anti-inflammatory drugs (NSAIDs), which are used for the treatment of several inflammatory disorders including rheumatoid arthritis, are well known to cause gastroduodenal mucosal lesions as an adverse effect. Recently, the serious problem of NSAID-induced small intestinal damage has become a topic of great interest to gastroenterologists, since capsule endoscopy and double-balloon enteroscopy are available for the detection of small intestinal lesions. Such lesions have been of great concern in clinical settings, and their treatment and prevention must be devised as soon as possible. Proton pump inhibitors (PPI), such as lansoprazole and omeprazole, show a potent anti-secretory effect. PPIs also have a gastroprotective effect, independent of their anti-secretory actions, which is probably mediated by inhibition of neutrophil functions as well as antioxidant actions. Administration of lansoprazole reduced the severity of the intestinal lesions in a dose-dependent manner, but omeprazole had no effect. The amount of heme oxygenase-1 (HO-1) protein in the intestinal mucosa was significantly increased by lansoprazole, but not by omeprazole. These results suggest that lansoprazole, but not omeprazole, ameliorates indomethacin-induced small intestinal ulceration through upregulation of HO-1/carbon monoxide. Therefore, lansoprazole may be useful for preventing the adverse effects of NSAIDs not only in the stomach but also in the small intestine.

Effects of Lansoprazole on the Lipopolysaccharide-Stimulated Toll-Like Receptor 4 Signal Transduction Systems: A Study Using the 293hTLR4/MD2-CD14 Cells

The present study was undertaken to evaluate the effects of lansoprazole (LPZ) on lipopolysaccharide (LPS)-stimulated toll-like receptor 4 (TLR4) signal transduction systems using the 293hTLR4/MD2-CD14 cells. The cells were incubated and then divided into the following groups: (a) untreated group, (b) non-LPZ treated (1h) group, (c) LPZ-treated (1h) plus non LPS-stimulated (1h) group, (d) LPZ-treated (1h) plus non LPS-stimulated (6h) group, (e) LPZ-treated (1h) plus LPS-stimulated (1h) group, (f) LPZ-treated (1h) plus LPS-stimulated (6h) group, (g) non LPZ-treated (1h) plus LPS-stimulated (1h) group and (h) non LPZ-treated (1h) plus LPS-stimulated (6h) group. Samples from each group were subjected to western blotting for analysis of IkB phosphorylation, intranuclear transfer of NF-kB, phosphorylation of MAP kinase (MAPK), intranuclear transfer of interferon regulatory factor 5 (IRF5), and expression of suppressor of cytokine signaling-1 (SOCS1). In the LPZ-treated groups, neither phosphorylation of MAPK nor intranuclear transfer of IRF5 was suppressed under stimulation with LPS, and enhanced intranuclear transfer of NF-kB and increased expression of SOCS1 were noted by comparison with the group treated with LPS alone. These results suggest that LPZ stimulates the expression of SOCS1 and regulates protein phosphorylation through its activity on TLR4 signal transduction under LPS stimulation.

Lansoprazole, a proton pump inhibitor, mediates anti-inflammatory effect in gastric mucosal cells through the induction of heme oxygenase-1 via activation of NF-E2-related factor 2 and oxidation of kelch-like ECH-associating protein 1

Induction of heme oxygenase-1 (HO-1) expression has been associated with cytoprotective and anti-inflammatory actions of lansoprazole, a proton pump inhibitor, but the underlying molecular mechanisms remain largely unresolved. In this study, we investigate the role of transcriptional NF-E2-related factor 2 (Nrf2), its phosphorylation/activation, and oxidation of Kelch-like ECH-associating protein 1 (Keap1) in lansoprazole-induced HO-1 up-regulation using cultured gastric epithelial cells (rat gastric mucosal cell line, RGM-1). HO-1 expression of RGM-1 cells was markedly enhanced in a time- and dose-dependent manner by the treatment with lansoprazole, and this up-regulation of HO-1 contributed to the inhibition of chemokine production from stimulated RGM-1 cells. Transfection of Nrf2-siRNA suppressed the lansoprazole-induced HO-1. An electrophoretic mobility shift assay showed increases in the nuclear translocation and stress-response elements (StRE) binding activity of Nrf2 proteins in RGM-1 cells treated with lansoprazole. Furthermore, in RGM-1 cells transfected with HO-1 enhancer luciferase reporter plasmid containing mutant StRE, lansoprazole-induced HO-1 reporter gene activity was diminished. Lansoprazole promoted the phosphorylation of extracellular signal-regulated kinase (ERK), and lansoprazole-induced HO-1 up-regulation was suppressed by U0126, an ERK-specific inhibitor. Phosphorylated Nrf2 protein was detected in the phosphoprotein fraction purified by a Pro-Q Diamond Phosphoprotein Enrichment kit. Finally, an oxidative form of the Keap1 protein was detected in lansoprazole-treated RGM-1 cells by analyzing S-oxidized proteins using biotinylated cysteine as a molecular probe. These results indicate that lansoprazole up-regulates HO-1 expression in rat gastric epithelial cells, and the up-regulated HO-1 contributes to the anti-inflammatory effects of the drug. Phosphorylation of ERK and Nrf2, activation and nuclear translocation of Nrf2, and oxidation of Keap1 are all involved in the lansoprazole-induced HO-1 up-regulation.

Transmucosal gastric leak induced by proton pump inhibitors

Despite their remarkable safety profile and lack of clinical side effects, proton pump inhibitors (PPIs) induce a transmucosal gastric leak to non-electrolyte probes of various sizes. The ex vivo addition of PPIs to isolated rat gastric corpus increases transmucosal permeability in a dose-dependent manner, which corresponds with PPIs' dose-dependent inhibition of acid secretion. Upon the addition of omeprazole, lansoprazole, or esomeprazole, a small decrease in transepithelial resistance and the concomitant stimulation of short circuit current was observed. Additionally, transepithelial flux of (14)C-[D]-mannitol (MW 182.17) across the gastric mucosa increased by a mean of 68% immediately following the addition of 200 microM omeprazole. This flux increase was bidirectional. Omeprazole also increased the paracellular permeability to larger radiolabeled probes, including (14)C-sucrose (MW 342.3) and (14)C-polyethylene glycol (MW 4,000) by 118% and 350%, respectively. However, the flux of still larger probes, 10,000 and 70,000 MW dextrans, was not increased. Because PPIs are so widely used and are assumed to be innocuous, this transmucosal gastric leak must be further investigated, as it may carry considerable biomedical implications.

Lansoprazole, a Proton Pump Inhibitor, Suppresses Production of Tumor Necrosis Factor-alpha and Interleukin-1beta Induced by Lipopolysaccharide and Helicobacter Pylori Bacterial Components in Human Monocytic Cells via Inhibition of Activation of Nuclear Factor-kappaB and Extracellular Signal-Regulated Kinase

Pathogenic bacterial components play critical roles in initiation of gastrointestinal inflammation via activation of intracellular signaling pathways which induce proinflammatory cytokines such as tumor necrosis factor (TNF)-α and interleukin (IL)-1β. Lansoprazole (LANSO), a proton pump inhibitor, has been widely used for the treatment of peptic ulcers and reflux esophagitis due to its potent acid-suppressive effect. It has also been reported to have anti-inflammatory effects. In this study we investigated the effects of LANSO on the production of TNF-α and IL-1β induced by lipopolysaccharide (LPS) and Helicobacter pylori water-soluble extract (HpWE) in the human monocytic cell line (THP-1). LANSO (100 µM) significantly reduced mRNA expression and production of TNF-α and IL-1β by THP-1 cells stimulated by LPS and HpWE. LANSO inhibited phosphorylation and degradation of inhibitory factor κB-α (IκB-α) and phosphorylation of extracellular signal-regulated kinase (ERK) induced by LPS and HpWE in THP-1 cells. These findings suggest that LANSO exerts anti-inflammatory effects by suppressing induction of TNF-α and IL-1β via inhibition of nuclear factor (NF)-κB and ERK activation.

The expression of heme oxygenase-1 induced by lansoprazole

Our previous studies have demonstrated that lansoprazole inhibits acute inflammatory reactions as well as intestinal mucosal injuries induced by ischemia-reperfusion or indomethacin administration in rats. Thus, proton pump inhibitors such as lansoprazole have been demonstrated to prevent gastrointestinal mucosal injury by mechanisms independent of acid inhibition. In our in vitro study, lansoprazole induced the expression of heme oxygenase-1 (HO-1) on rat gastric epithelial cells (RGM-1 cells), and exerted anti-inflammatory effect on the dependent of HO-1 expression. Furthermore, NF-E2-related factor-2 (Nrf2) played an important role in HO-1 expression induced by lansoprazole. In this review, we focused on lansoprazole-induced HO-1 expression, its anti-inflammatory action, and the role of Nrf2 in its expression.

Proton pump inhibitors exert anti-allergic effects by reducing TCTP secretion

BACKGROUND

Extracellular translationally controlled tumor protein (TCTP) is known to play a role in human allergic responses. TCTP has been identified outside of macrophages, in activated mononuclear cells, and in biological fluids from allergic patients. Even TCTP devoid of signal sequences, is secreted to extracellular environment by an yet undefined mechanism. This study is aimed at understanding the mechanism of TCTP release and its regulation. A secondary goal is to see if inhibitors of TCTP release can serve as potential anti-allergic asthmatic drugs.

METHODOLOGY/PRINCIPAL FINDINGS

Using Western blotting assay in HEK293 and U937 cells, we found that TCTP secretion is reduced by omeprazole and pantoprazole, both of which are proton pump inhibitors. We then transfected HEK293 cells with proton pump expression vectors to search for the effects of exogeneously overexpressed H(+)/K(+)-ATPase on the TCTP secretion. Based on these in vitro data we checked the in vivo effects of pantoprazole in a murine model of ovalbumin-induced allergy. Omeprazole and pantoprazole reduced TCTP secretion from HEK293 and U937 cells in a concentration-dependent fashion and the secretion of TCTP from HEK293 cells increased when they over-expressed H(+)/K(+)-ATPase. In a murine model of ovalbumin-induced allergy, pretreatment with pantoprazole reduced infiltration of inflammatory cells, increased goblet cells, and increased TCTP secretion induced by OVA challenge.

CONCLUSION

Since Omeprazole and pantoprazole decrease the secretion of TCTP which is associated with the development of allergic reaction, they may have the potential to serve as anti-allergic (asthmatic) drugs.

Association of proton pump inhibitor therapy with spontaneous bacterial peritonitis in cirrhotic patients with ascites

OBJECTIVES

Spontaneous bacterial peritonitis (SBP) is a frequent complication of cirrhosis. Bacterial contamination of ascites fluid leading to SBP is caused by bacterial translocation with subsequent bacteremia. Proton pump inhibitors (PPIs) suppress gastric acid secretion, allowing bacterial colonization of the upper gastrointestinal tract, and may predispose to bacterial overgrowth and translocation. The aim of this study was to determine whether PPI use in cirrhotics with ascites is associated with SBP.

METHODS

A retrospective case-control study was performed. Seventy cirrhotics admitted with paracentesis-proven SBP between 2002 and 2007 were matched 1:1 (for age and Child's class) with comparable cirrhotics with ascites who were admitted for conditions other than SBP. We excluded patients on chronic antibiotic prophylaxis or with antecedent gastrointestinal bleeding. Outpatient PPI use at the time of admission was compared between groups, and the effect of covariates was analyzed.

RESULTS

Patients with SBP had a significantly higher rate of prehospital PPI use (69%) compared with ascitic cirrhotics hospitalized without SBP (31%, P = 0.0001). There was no significant difference in demographics, diabetes, etiology, or survival between groups. On multivariate analysis, PPI use was independently associated with SBP (odds ratio (OR) 4.31, confidence interval (CI) 1.34-11.7), and ascitic fluid protein was protective (OR 0.1, CI 0.03-0.25). In total, 47% of cirrhotic patients receiving PPI in this study had no documented indication for PPI treatment.

CONCLUSIONS

PPI therapy is associated with SBP in patients with advanced cirrhosis. Prospective studies are needed to determine whether PPI avoidance can reduce the incidence of SBP and improve outcomes.

Proton pump inhibitor use and enteric infections

Proton pump inhibitors (PPIs) and H2 receptor antagonists (H2RAs) are very commonly prescribed drugs and are routinely used in the chronic management of gastro-esophageal reflux disease. Concerns have been raised about the possible association of PPIs with enteric infections. This article reviews the studies that have examined the associations of proton pump inhibitors in particular, and enteric infections.

Lansoprazole promotes gastric mucosal cell proliferation and migration by activating p44/p42 mitogen-activated protein kinase

Cell proliferation and migration are important repair mechanisms in cell defect type mucosal injuries, such as peptic ulcers. To evaluate the level of cell restitution in vitro, we established a normalized assay system for analyzing the area of a tissue defect created in the center of a cultured cell layer. Although proton pump inhibitors are known to be potently effective in the treatment of peptic ulcers by inducing acid suppression, they are also effective in low-acid conditions, such as in gastric ulcers associated with severe atrophic gastritis of the corpus. The present study was designed to examine the pH-independent effect of lansoprazole (LPZ) on cell restitution in vitro. The mouse gastric mucosal cell line, GSM06, was cultured to confluence. A 4-fluoric ethylene-tipped aluminum stick was then used to produce a cell-free area in the center of the culture well. After measuring the area of the cell defect using a digital analyzer equipped with an inverted microscope, LPZ was added to each well; the area of the residual cell defect was then measured 6 and 24 hours after LPZ administration. To investigate the involvement of the p44/p42 mitogen-activated protein kinase (MAPK) and p38 MAPK in this process, PD98059 (a MEK inhibitor) or FR167653 (a p38 MAPK inhibitor) was added to the cell cultures. In a separate experiment, GSM06 cells were cultured to the subconfluent level, each test agent was added, and the cell number in each well was measured using an MTT assay 16 hours after the administration of the agents. Six hours after the addition of LPZ, a slight but significant increase in the cell restitution rate was observed in the LPZ-treated groups compared with that in the control group. After 24 hours, a further significant increase in the cell restitution rate was observed in the LPZ groups compared with that in the control group. While the addition of PD98059 significantly attenuated the cell restitution rate in the LPZ groups, the addition of FR167653 had no such effect. The total cell number in the subconfluent cell cultures was significantly increased in the LPZ-treated groups compared with that in the control group. In conclusion, LPZ promotes the healing of injured gastric mucosal cells following injury by enhancing cell proliferation and migration. Furthermore, the mechanism by which cell proliferation and migration is promoted by LPZ may involve the activation of p44/p42 MAPK.

A succinct review of the general and immunological pharmacologic effects of proton pump inhibitors

Proton pump inhibitors (PPI) are a group of anti-ulcer agents. PPI have selective anti-cancer effects via apoptosis of tumour, sensitization of cancer cell to chemotherapy and radiotherapy. Also PPI have anti-malarial and anti-leishmanial activity. Rising of endosomal (P)H inhibits the presentation of antigens that enter cell through endocytosis. PPI can affect transmigration of leucocytes from vessels to inflammatory sites and also can mitigate neutrophile adherence to endothelial cell. PPI increase the intralysosomal (P)H and decrease the expression of intracellular adhesion molecules. Therefore PPI can exert immunomodulation in immunological diseases through hampering antigen processing, antigen presentation, and leucocytes transmigration.

Increased esophageal mucosal/submucosal blood flow in patients with gastroesophageal reflux disease: normalization by treatment with a proton pump inhibitor

BACKGROUND AND AIM

Mucosal injury caused by gastroesophageal reflux may result in changes in esophageal mucosal blood flow. Little is known about esophageal mucosal blood flow in patients with gastroesophageal reflux disease (GERD). Here we examined esophageal mucosal blood flow and the effects of treatment in patients with GERD.

METHODS

The subjects included 41 cases (21 males and 20 females, mean age 64.2 years) in whom endoscopy was warranted in patients complaining of heartburn and/or regurgitation. We also studied six normal control subjects. Patients underwent endoscopy, laser Doppler flow meter measurements, and endoscopic ultrasonography before and after treatment.

RESULTS

Esophageal mucosal/submucosal blood flow was increased in patients with GERD compared with the control patients. The thickness of the whole esophageal wall and that of the mucosal and submucosal layers of the esophagus correlated significantly with esophageal mucosal/submucosal blood flow. The increased esophageal mucosal/submucosal blood flow significantly decreased after 4 weeks' treatment with lansoprazole, a proton pump inhibitor.

CONCLUSION

Our results indicated that the pathophysiology or underlying mechanisms of GERD includes increased esophageal mucosal/submucosal blood flow, which correlates with the thickness of the esophageal wall, but is reversible and responds to treatment with lansoprazole. This suggests that proton pump inhibitors can effectively treat GERD and promote histological normalization of the mucosa and submucosa in the lower esophagus.

Association between proton pump inhibitor use and spontaneous bacterial peritonitis

Proton pump inhibitors (PPIs) increase enteric bacterial colonization, overgrowth, and translocation, all effects which might predispose to spontaneous bacterial peritonitis. We investigated whether PPI usage is associated with spontaneous bacterial peritonitis. Our retrospective case-control study included 116 consecutive cirrhotic patients with ascites who underwent diagnostic paracentesis upon hospital admission (2002-2005). Spontaneous bacterial peritonitis was defined as paracentesis yielding >or=250 polymorphonuclear leukocytes/ml. We performed logistic regression to determine the risk of spontaneous bacterial peritonitis by PPI usage. Of the 116 subjects, 32 had spontaneous bacterial peritonitis. Patient characteristics were similar between groups with and without infection, with the exception of the Model for End-Stage Liver Disease score (median: 23 and 18, respectively; P = 0.002). Crude and adjusted odds ratios for the development of spontaneous bacterial peritonitis by exposure to PPIs were 1.22 (95% confidence interval: 0.52-2.87) and 1.05 (0.43-2.57), respectively. In conclusion, we did not find a positive association between PPI use and spontaneous bacterial peritonitis.

Omeprazole inhibits natural killer cell functions

This study was designed to determine the possible effects of omeprazole on human natural killer cells. Peripheral venous blood samples were taken from 20 peptic ulcer patients before and at the 14th and the 28th days of omeprazole treatment. Mononuclear cells were removed from blood and their capability of making conjugation with K562 target cells and lysing K562 target cells was evaluated. A significant decrease was found (P < 0.001) in the 14th and the 28th days compared with the basal value of the capability of the mononuclear cells to conjugate with the K562 target cells and to lyse them. This study demonstrated that omeprazole significantly reduces natural killer cell functions. This finding suggests that omeprazole may also have some effects on the other systems in addition to parietal cell acid secretion.

Effects of a one-week treatment with acid gastric inhibitors on Helicobacter pylori-infected mice

OBJECTIVE

Antiacid drugs, including omeprazole and ranitidine, were prescribed to Helicobacter pylori-infected subjects in combination with antibiotics during eradication treatment. Several reports suggest that these drugs have additional pharmacological properties, such as antineutrophil, antiapoptotic and antioxidant characteristics. The aim of this work was to study the effects of acid suppressive medication treatment in the H. pylori infection experimental model, focusing on possible additional pharmacological properties.

MATERIAL AND METHODS

The ability of gastric acid suppression was assessed in pylorus-ligated animals. Gastric H. pylori colonization levels, myeloperoxidase (MPO) acitivity, macroscopic damage, Bax and Bcl-2 expression and DNA damage levels were assessed in C57BL/6-infected mice after treatment for one week with omeprazole (100 mg kg(-1)) or ranitidine (100 mg kg(-1)).

RESULTS

Omeprazole treatment increased bacteria colonization and MPO activity in mice stomachs. Both antiacid drugs efficiently improved macroscopic damage, although only omeprazole restored the expression of the antiapoptotic Bcl-2 protein in gastric mucosa of infected animals.

CONCLUSIONS

Some additional omeprazole-related properties, such as antineutrophil properties, were not observed in H. pylori-infected mice after one week of treatment, suggesting that this property is restricted to in vitro approaches. However, the antiapoptotic activity of omeprazole could be attributed to an ability to modify the protein expression of Bcl-2, decreased by H. pylori infection.

Use of acid-suppressing drugs and the risk of bacterial gastroenteritis

BACKGROUND & AIMS

Gastric acid is a defense mechanism against gastrointestinal infections caused by ingested bacteria. Studies have suggested that the use of acid-suppressing drugs may increase the risk of gastroenteritis (GE).

METHODS

Patients aged 20-74 years with an episode of acute bacterial GE (n = 6414) were identified. A control group from the same study population without a diagnosis of GE (n = 50,000) was frequency-matched by age, sex, and calendar year to the case group. Unconditional logistic regression was used to calculate the adjusted relative risk (RR) of GE in patients using proton pump inhibitors (PPIs) or histamine-2 receptor antagonists (H2RAs).

RESULTS

Current use of PPIs was associated with an increased risk of bacterial GE compared with nonuse, regardless of the treatment duration (RR, 2.9; 95% confidence interval [CI], 2.5-3.5), whereas no association was observed with H2RA use (RR, 1.1; 95% CI, 0.9-1.4). Doubling the PPI dose further increased the risk of developing bacterial GE (RR, 5.0; 95% CI, 2.7-9.3). The effect of PPI use did not vary significantly with regard to treatment indication. The increased risk associated with PPI use was similar for both omeprazole (RR, 3.0; 95% CI, 2.5-3.7) and lansoprazole (RR, 2.1; 95% CI, 1.4-3.0), whereas neither cimetidine nor ranitidine showed any increased risk. Campylobacter (n = 4124) and Salmonella (n = 1885) were the 2 species most frequently responsible for GE episodes in the case group. When analyzed separately, both species reproduced the increased risk associated with PPI use and not H2RA use. Clostridium GE cases were rare (n = 31).

CONCLUSIONS

This study suggests that gastric acid suppression induced by PPIs but not H2RAs is associated with an increased risk of Campylobacter and Salmonella GE.

Gastric antisecretory drugs induce leukocyte-endothelial cell interactions through gastrin release and activation of CCK-2 receptors

Antisecretory drugs are effective antiulcer agents, but its chronic use generates hypergastrinemia and accelerates the development of atrophic gastritis in Helicobacter pylori-positive patients. We have recently shown that gastrin exerts a proinflammatory effect in rats through CCK-2 receptor activation that contributes to the inflammation induced by H. pylori. The present study was designed to examine whether gastrin hypersecretion in response to treatment with antisecretory drugs induces an inflammatory response that could promote mucosal atrophy. The effects of omeprazole or famotidine on leukocyte/endothelial cell interactions in vivo were analyzed in rat mesenteric venules using intravital microscopy. Administration of a single dose of omeprazole or famotidine acutely increased gastrinemia and leukocyte rolling and adhesion, but not emigration into the interstitium. Daily treatment with omeprazole for a short period (3 days) induced a similar response, but when this treatment was extended to 14 days and a steady hyper-gastrinemic state was established, increased leukocyte rolling, adhesion, and emigration was observed. Pretreatment with the CCK-2 receptor antagonist proglumide prevented these inflammatory events in all cases. Leukocytes from rats treated with omeprazole showed increased expression of CD11b/CD18 initially in granulocytes (3-day protocol) and later in monocytes and lymphocytes (14-day protocol). These changes were not observed in animals pretreated with proglumide, and they were not reproduced by incubation of leukocytes from untreated animals in vitro with gastrin. Thus, hypergastrinemia induced by chronic treatment with antisecretory drugs may promote inflammation, which could partly explain their worsening effect in corpus gastritis observed in H. pylori-infected patients.

Protective effects of proton pump inhibitors against indomethacin-induced lesions in the rat small intestine

Proton pump inhibitors (PPIs) have been shown to be effective in preventing gastric and duodenal ulcers in high-risk patients taking nonsteroidal anti-inflammatory drugs (NSAIDs); by contrast, scarce information is available concerning the effects of PPIs on intestinal damage induced by NSAIDs in humans or in experimental animals. We examined the effects of lansoprazole and omeprazole on the intestinal injury induced by indomethacin in the conscious rat. PPIs were administered by the intragastric route at 30, 60 and 90 micromol/kg, 12 h and 30 min before and 6 h after indomethacin treatment. The effects of omeprazole and lansoprazole were evaluated on: (1) macroscopic and histologic damage; (2) mucosal polymorphonuclear cell infiltration; (3) oxidative tissue damage and (4) bacterial translocation from lumen into the intestinal mucosa. Lansoprazole and omeprazole (at 90 micromol/kg) significantly decreased (P<0.01) the macroscopic and histologic damage induced by indomethacin in the rat small intestine. Furthermore, both drugs greatly reduced (P<0.01) the associated increases in myeloperoxidase levels and lipid peroxidation induced by indomethacin, whereas they only moderately affected (P<0.05) the translocation of enterobacteria from lumen into the intestinal mucosa. These data demonstrate that omeprazole and lansoprazole can protect the small intestine from the damage induced by indomethacin in the conscious rat. The intestinal protection, possibly related to antioxidant and anti-inflammatory properties of these drugs, may suggest new therapeutic uses of PPIs in intestinal inflammatory diseases.

Suppression of proinflammatory cytokine production in macrophages by lansoprazole

Macrophages (MPs) produce increased levels of proinflammatory cytokines in Crohn's disease; these cytokines are thought to play a central role in the occurrence of the disease. Biologics are currently available for anti-cytokine therapy, but treating intestinal inflammation through direct suppression of proinflammatory cytokine production could be more effective. P-ATPase inhibitors have been reported to be anti-inflammatory, and these inhibitors might suppress the production of MP proinflammatory cytokines. In this study, we examined the effect of two types of ATPase inhibitors on the expression patterns of typical proinflammatory cytokines. Peritoneal MPs from 6- to 8-week-old mice were cultured for 48 h in the presence of lansoprazole (P-ATPase inhibitor), bafilomycin A(1) (V-ATPase inhibitor), or the control solvent dimethylsulfoxide. The MPs were then examined for cytokine expression by quantitative real-time polymerase chain reaction (PCR), and culture supernatants were examined for cytokine production with a multiplex assay in a suspension array system. The possible existence of P-ATPase mRNA in MPs was explored using reverse-transcriptase PCR. P-ATPase mRNA was not detected in MP cells. However, all examined proinflammatory cytokines decreased significantly in their mRNA and protein expression in the lansoprazole-treated group. Conversely, bafilomycin A(1) increased the levels of these cytokines. Lansoprazole might be useful for the treatment of inflammatory bowel diseases (IBDs), including Crohn's disease, as it suppresses the production of relevant MP proinflammatory cytokines. However, because P-ATPase was not detected in MPs, the mechanism is unclear and remains to be studied further in an IBD animal model.

Beyond gastric acid reduction: Proton pump inhibitors induce heme oxygenase-1 in gastric and endothelial cells

Proton pump inhibitors (PPIs) have been demonstrated to prevent gastric mucosal injury by mechanisms independent of acid inhibition. Here we demonstrate that both omeprazole and lansoprazole protect human gastric epithelial and endothelial cells against oxidative stress. This effect was abrogated in the presence of the heme oxygenase-1 (HO-1) inhibitor ZnBG. Exposure to either PPI resulted in a strong induction of HO-1 expression on mRNA and protein level, and led to an increased activity of this enzyme. Expression of cyclooxygenase isoforms 1 and 2 remained unaffected, and COX-inhibitors did not antagonize HO-1 induction by PPIs. Our results suggest that the antioxidant defense protein HO-1 is a target of PPIs in both endothelial and gastric epithelial cells. HO-1 induction might account for the gastroprotective effects of PPIs independently of acid inhibition, especially in NSAID gastropathy. Moreover, our findings provide additional perspectives for a possible but yet unexplored use of PPIs in vasoprotection.

Effect of pantoprazole administered subcutaneously on the healing of sutured gastric incisions in rats

BACKGROUND

The properties of proton pump inhibitors most investigated are related to peptic diseases and upper gastrointestinal bleeding, but their influence on the healing of sutured gastric incisions has not been assessed. In the present study we evaluated the effect of subcutaneously administered pantoprazole on the healing of sutured gastric incisions in rats.

METHODS

Sixty rats were divided into a pantoprazole group and a control group. All rats were submitted to gastric suture in the gastric body and in the gastric fundus and had their gastric pH measured. The pantoprazole group received 20 mg/kg pantoprazole and the control group received 0.9% isotonic NaCl, both subcutaneously t.i.d. Healing analysis was carried out using collagen picrosirius red F3BA staining, and breaking strength was measured on the 4th and 7th postoperative days in all groups.

RESULTS

Gastric pH was higher in the pantoprazole group. In the fundus, the pantoprazole group had a higher measurement of breaking strength and a higher proportion of type-I over type-III collagen on the 7th postoperative day. In the body, the pantoprazole group had a higher proportion of type-I over type-III collagen on the 4th and 7th postoperative days.

CONCLUSIONS

Pantoprazole given subcutaneously promoted a reduction in gastric acid secretion and was associated with improved healing of the sutured gastric incision in the fundus (squamous epithelium) of rats. These findings suggest that pantoprazole has healing properties in sutured gastric incisions with potential benefits in gastric surgery.

Dysphagia associated with gastroesophageal reflux disease is improved by proton pump inhibitor

This study aimed to determine whether dysphagia associated with gastroesophageal reflux disease was effectively treated with rabeprazole, a proton pump inhibitor. Sixty-eight outpatients with gastroesophageal reflux-associated dysphagia were enrolled in this study. Endoscopic esophagitis was confirmed in 52 of 68 subjects. The proton pump inhibitor rabeprazole was administered at 20 mg daily for 8 weeks. Rabeprazole was administered for a further 6 months to 16 subjects whose dysphagia was improved (10 mg/day) and 5 of these underwent 24-hr esophageal pH monitoring before and after treatment. Dysphagia was completely resolved in 40 of 68 subjects, which were categorized in Group I. Dysphagia improved partially in 20 subjects and was unchanged in 8 subjects. These 28 subjects were categorized into Group II. Comparison was made between Group I and Group II and multivariate analysis demonstrated that the only factor that correlated with the effect of rabeprazole on dysphagia was "improvement in heartburn symptoms." There were no relapses of symptoms during the 6-month follow-up period, and pH monitoring showed sustained suppression of acid secretion. The results indicate that rabeprazole is effective in the treatment of dysphagia associated with gastroesophageal reflux disease. We were, however, unable to elicit any factors that could predict the therapeutic effect of rabeprazole before commencing treatment.

Management of symptoms in step-down therapy of gastroesophageal reflux disease

OBJECTIVE

Majority of studies on gastroesophageal reflux disease (GERD) that include patients with or without erosive disease have documented the efficacy of proton pump inhibitors (PPIs) as well as their superiority to H(2)-receptor antagonist (H(2)-RA). The purpose of this study was to clarify the difference in quality of GERD treatment with PPIs and H(2)-RA in step-down protocol using lansoprazole.

METHODS

Forty-three patients with reflux esophagitis were randomly divided into three groups and assessed by severity score; group 1 received 30 mg lansoprazole initially and maintenance therapy with a standard dose H(2)-RA; group 2 received 30 mg of lansoprazole initially and maintenance therapy of 15 mg lansoprazole; and group 3 received 15 mg of lansoprazole once daily for 16 weeks. If the patients experienced symptomatic recurrence while on H(2)-RA, they were switched to PPI maintenance.

RESULTS

Heartburn, regurgitation and dysphagia were hardly found in any group at 8 weeks after 15 mg or 30 mg lansoprazole treatment. After 8 weeks, however, heartburn and regurgitation recurred at 50% and 78.6%, respectively, in the stepped down to famotidine group, and quality of life (QOL) was significantly impaired. Endoscopic ultrasonography (EUS) analysis showed reduction of the submucosal layer without any change in the mucosal surface in the stepped down to famotidine group.

CONCLUSIONS

Step-down lansoprazole therapy is considered very effective in terms of rapid effect, long-term effect and high quality GERD treatment.

Haplotype analysis of the CD11 gene cluster in patients with chronic Helicobacter pylori infection and gastric ulcer disease

Helicobacter pylori infection leads to a broad spectrum of disease manifestations such as gastritis, ulcer disease, and even gastric carcinoma. The genetically determined immune response and subsequent inflammation influence the degree of mucosal damage. Adhesion molecules of the CD11 cluster play an important role in adherence of neutrophils to endothelial cells in inflammation. We conducted a haplotype-based analysis of the CD11 cluster in a sample of 315 patients with H. pylori infection and investigated associations with gastric erosions and ulcer disease. Twelve single nucleotide polymorphisms (SNPs) covering the genes CD11a, CD11b, and CD11c were genotyped by Taqman technology. Linkage disequilibrium (LD) was assessed within the CD11 cluster and haplotype case-control analysis was conducted. Sliding window haplotype analysis identified a haplotype consisting of the markers CD11c exon 15 and intron 31 associated with gastric ulcer disease. Patients carrying the haplotype GA bear a 2.4-fold increased risk. No significant associations of single markers with disease outcome were found. High-density LD mapping and mutation detection of CD11c in larger samples will be necessary to confirm our findings and identify the causative variant. Thus, we conclude that genetic variants in the CD11 cluster may play a role in the development of gastric ulcer in chronic H. pylori infection presumably by influencing leukocyte adhesion. The biological effect of genetic variants of CD11c in gastric inflammation needs further clarification.

Lansoprazole ameliorates intestinal mucosal damage induced by ischemia-reperfusion in rats

AIM: To investigate the protective effect of lansoprazole on ischemia and reperfusion (I/R)-induced rat intestinal mucosal injury in vivo.

METHODS: Intestinal damage was induced by clamping both the superior mesenteric artery and the celiac trunk for 30 min followed by reperfusion in male Sprague-Dawley rats. Lansoprazole was given to rats intraperitoneally 1 h before vascular clamping.

RESULTS: Both the intraluminal hemoglobin and protein levels, as indices of mucosal damage, significantly increased in I/R-groups comparion with those of sham-operation groups. These increases in intraluminal hemoglobin and protein levels were significantly inhibited by the treatment with lansoprazole at a dose of 1 mg/kg. Small intestine exposed to I/R resulted in mucosal inflammation that was characterized by significant increases in thiobarbituric acid-reactive substances (TBARS), tissue-associated myeloperoxidase activity (MPO), and mucosal content of rat cytokine-induced neutrophil chemoattractant-1 (CINC-1). These increases in TBARS, MPO activities and CINC-1 content in the intestinal mucosa after I/R were all inhibited by pretreatment with lansoprazole at a dose of 1 mg/kg. Furthermore, the CINC-1 mRNA expression was increased during intestinal I/R, and this increase in mRNA expression was inhibited by treatment with lansoprazole.

CONCLUSION: Lansoprazole inhibits lipid peroxidation and reduces development of intestinal mucosal inflammation induced by I/R in rats, suggesting that lansoprazole may have a therapeutic potential for I/R injury.

Interleukin-8 expression in the esophageal mucosa of patients with gastroesophageal reflux disease

BACKGROUND

It has been reported that inflammatory cell infiltration can be detected in patients with endoscopically negative gastroesophageal reflux disease (GERD) as well as those with erosive reflux esophagitis. In this study, we examined the expression of mRNA for interleukin (IL)-8, a potent chemokine for neutrophils, in the esophageal mucosa of patients with GERD and compared the results with their endoscopic findings and symptoms.

METHODS

Biopsy samples were obtained from 80 patients. Endoscopic diagnosis was performed according to the Los Angeles classification. Patients with typical symptoms such as heartburn despite normal endoscopic findings were classified as the non-erosive GERD group. Total cellular RNA was extracted from the biopsy samples and IL-8 mRNA was quantified by real-time polymerase chain reaction (PCR). Localization of IL-8 protein in the esophageal mucosa was done by immunostaining.

RESULTS

Expression of IL-8 mRNA was correlated with the endoscopic grade of esophagitis or with inflammatory cell infiltration, but not with the symptoms of the patients. Expression of IL-8 mRNA was also detected in all patients with non-erosive GERD. The level of IL-8 expression in non-erosive GERD was low compared with that in erosive GERD, but was higher than that in normal controls. IL-8 immunostaining was found in the basal layers of the esophageal mucosa. Administration of lansoprazole, a proton-pump inhibitor, decreased both IL-8 mRNA and protein levels in the esophageal mucosa.

CONCLUSION

These results suggest that IL-8 in the esophageal mucosa may be involved in the pathogenesis of esophageal inflammation, including non-erosive GERD.

Pantoprazole treatment does not invoke anti-inflammatory properties in vivo

BACKGROUND AND AIMS

Proton pump inhibitors (PPIs) are antiulcer agents that have gastric antisecretory and mucosal protective actions. The antisecretory effect of these agents derives from the inhibition of gastric parietal cell proton pump H+/K+ ATPase. The exact mechanism of PPI-induced gastric mucosal protection is not known though. It has been suggested that PPI may accumulate, modulating the functions of neutrophils and, thus, may be useful in reducing the gastric mucosal injury caused by these cells. However, these same mechanisms may not be desirable when PPIs are prescribed in prophylaxis and pre-operatively for ill or immunodepressed patients. The present study was designed to examine a possible anti-neutrophil activity of pantoprazole in vivo. A short study with omeprazole and lanzoprazole was also performed.

METHODS

Dosages of PPIs able to inhibit basal acid secretion (10 and 100 mg kg(-1)) were administered intraperitoneally (i.p.) to rats for 7 or 28 days. Cimetidine (100 mg kg(-1)) and dexamethasone (0.75 mg kg(-1)) were used as controls for antisecretory and anti-inflammatory activity, respectively. Air pouches were then developed in these animals, and Helicobacter pylori suspension or carrageenan was used as inflammatory stimulus. Exudate formation and leukocyte migration to air pouches were assessed.

RESULTS

Neither short nor long treatment with pantoprazole modified the ability of neutrophils to migrate in response to carrageenan or H. pylori. The same results were obtained when omeprazole or lanzoprazole was used. Dexamethasone, alone, a potent anti-inflammatory drug, was able to reduce polymorphonuclear and mononuclear cell migration.

CONCLUSION

Based on these observations, pantoprazole and other PPIs seem to have no anti-inflammatory properties in vivo.

Inhibitory effects of catechins on neutrophil-dependent gastric inflammation

The inhibitory effects of tea against carcinogenesis have been attributed to the biological activity of the polyphenol fraction of tea. However, the molecular mechanisms of these effects are not completely understood. Chronic inflammation induced by Helicobacterpylori has been proposed to be a causative pathway in the carcinogenesis of stomach cancer. Therefore, an agent possessing anti-inflammatory properties may be chemopreventative against stomach cancer. In the present study, we have investigated the anti-inflammatory effects of tea catechins. After addition of IL-1beta to MKN45 cells, a gastric cancer cell line, or human umbilical vein endothelial cells (HUVECs), IL-8 production was detected in supernatants. This IL-8 production was inhibited by catechins. Incubation of HUVECs or polymorphonuclear leukocytes (PMNs) with IL-1beta or IL-8, respectively, resulted in an increased surface expression of adhesion molecules. Catechins also inhibited this expression of adhesion molecules on HUVECs and PMNs. Of these major effects, the strongest effect of catechins was to reduce expression of the adhesion molecules CD1lb and CD18 on PMNs. These results suggest that tea may inhibit carcinogenesis partly through the anti-inflammatory effects of tea catechins on PMN-dependent gastric mucosal inflammation.

Rabeprazole treatment attenuated Helicobacter pylori-associated gastric mucosal lesion formation in Mongolian gerbils

BACKGROUND AND AIM

Although rabeprazole (RPZ), a proton pump inhibitor, has been reported to have a bactericidal effect on Helicobacter pylori (H. pylori), no studies have been conducted regarding the effect of RPZ on gastric mucosal lesion formation caused by this bacterium. In the present study, we investigated the effect of RPZ on H. pylori-associated gastric mucosal lesion formation.

METHODS

Sixty-two male Mongolian gerbils were inoculated with H. pylori (ATCC43504) (Hp group) and 60 gerbils with the culture media alone (control group). Some gerbils in the Hp group and in the control group were injected with RPZ (1 mg/kg/day, for 7 days) at the 5th week. Gerbils were evaluated at the 12th, 24th and 48th weeks.

RESULTS

In the Hp group, all gerbils were persistently infected for 24 weeks, but 36% became negative for H. pylori at the 48th week. In the Hp + RPZ group, 18% of gerbils at the 12th week, 40% at the 24th week, and 80% at the 48th week, became negative for H. pylori. The level of neutrophil infiltration was significantly decreased in the Hp + RPZ group in comparison to the Hp group, possibly through the effects of RPZ on initial bacterial colonization and resultant inflammation. Even in the gerbils that became H. pylori-negative, the level of neutrophil infiltration was lower in the Hp + RPZ group than in the Hp group. RPZ treatment significantly increased the level of the reduced form of glutathione (GSH) at the 48th week. The elevated levels of the reduced form of GSH may have been reduced by an antioxidation process in the H. pylori-positive Hp + RPZ group.

CONCLUSION

Administration of RPZ not only inhibited gastric H. pylori colonization, but also reduced gastric mucosal inflammation in gerbils, possibly through its antibacterial action as well as pharmacological recruitment of the reduced form of GSH.

Hepatic lysosomal enzymes activity and liver morphology after short-time omeprazole administration

The aim of the study was to establish the influence of short-time omeprazole administration on liver function and morphology. Omeprazole was administered intraperitoneally, twice daily, for 3 days to male Wistar rats in two doses: 0.571 mg/kg and 5.71 mg/kg. Control animals were treated with physiological saline. Half of the animals were sacrificed 12 hours after the last injection. The remaining rats were raised for another 6 weeks, without any xenobiotics, and sacrificed on the 47th day of the experiment. The activity of free and bound fractions of hepatic acid phosphatase, beta-galactosidase, beta-N-acetyl-glucosaminidase, cathepsin B, D and L, lipase, and sulphatase were determined spectrophotometrically in homogenates of the liver. The liver sections were examined by light microscopy with hematoxylin-eosin, azan, and periodic acid-Schiff stains. Marginally significant (p < 0.1) differences in activity of free sulphatase fraction, and free and bound fractions of beta-galactosidase were found in animals exposed to the higher dose of omeprazole and sacrificed 12 hours after the last injection. Enzymatic profiles were normalised during the next 6 weeks. Histological evaluation revealed small degenerative and adaptive changes in all examined groups. It could be concluded that observed differences of hepatic lysosomal enzyme activities were the result of accompanied chemical-induced peritonitis as previously reported, and not a direct drug-toxic effect.

Gastroduodenal mucosal defense: coordination by a network of messengers and mediators

Gastroduodenal mucosal defense is composed of structural features of the mucosa, cellular monitors of pending or actual injury, and a web of effector cells that protect the mucosa from damage and govern its recovery from injury. By virtue of these systems, the gastroduodenal mucosa can cope with the harmful ingredients of ingested food and the potentially deleterious effects of gastric acid and pepsin. It is increasingly appreciated that a network of chemical messengers coordinates the alarm, defensive, and healing mechanisms. This article highlights some of the advances from the past year that have furthered our understanding of the regulatory systems that govern gastroduodenal mucosal homeostasis. Particular emphasis is given to control of the mucous and epithelial phospholipid barriers, the mucosal microcirculation, and the epithelial, neural, immune, and inflammatory mediators of the mucosal repair mechanisms.