Acid pump antagonist-provoked HSP27 dephosphorylation and accentuation rescues stomach from indomethacin-induced damages

Revaprazan prevented indomethacin-induced intestinal damages by enhancing tight junction related mechanisms

Non-steroidal anti-inflammatory drugs (NSAIDs) are the most commonly prescribed medications for alleviating pain and inflammation but may cause gastrointestinal tract damage. Proton pump inhibitors (PPI) prevent NSAID-induced gastric damage but may aggravate intestinal damage via dysbiosis and intestinal permeability alteration. Currently, there is growing interest regarding the influence of potassium competitive acid blockers (PCAB) on NSAID-induced enteropathy. Here, we investigated the relative changes in indomethacin-induced enteropathy by combining indomethacin with pantoprazole (as PPI) or revaprazan (as PCAB). We examined intestinal permeability-related molecular changes in in vitro Caco-2 cell models and in an in vivo indomethacin-induced enteropathy rat model. Indomethacin alone or in combination with pantoprazole significantly increased relative lucifer yellow dye flux and decreased relative trans-epithelial electrical resistance and tight junction protein (TJP) expression compare to normal cells. In contrast, indomethacin combined with revaprazan significantly preserved TJPs compare to indomethacin-treated cells. MLC phosphorylation, Rho activation, and ERK activation responsible for TJP were significantly increased by indomethacin alone or a combination of indomethacin and pantoprazole but not by a combination of indomethacin and revaprazan. Intestinal damage scores significantly increased with indomethacin and pantoprazole combination but not with indomethacin and revaprazan combination. Indomethacin and pantoprazole combination significantly activated Rho-GTPase, p-MLC, and p-ERK but significantly decreased TJP expression. However, indomethacin and revaprazan combination significantly preserved TJPs and inactivated Rho-GTPase, MLC, and ERK. Hence, revaprazan rather than PPIs should be co-administered with NSAIDs to mitigate NSAID-induced intestinal damage.

Molecular mechanisms elucidating why old stomach is more vulnerable to indomethacin-induced damage than young stomach

BACKGROUND/AIMS

Detailed underlying changes have never been explored to explain how old stomach is more susceptible to non-steroidal anti-inflammatory drugs (NSAIDs)-induced gastric damage than young stomach, although presumptively speculated as weakened mucosal defense system as well as attenuated regenerating capacity in old stomach.

METHODS

In order to investigate molecular mechanisms relevant to NSAID-induced gastric damage, we administered indomethacin to 6-week-old and 60-week-old rats.

RESULTS

In spite of the same oral administration of indomethacin (0.1 mg indomethacin dissolved in 1 ml carboxyl methylcellulose) irrespective of body weights of rat, gastric mucosal damages were significantly increased in the older rats compared to the younger rats (p < 0.05). Before indomethacin administration, inflammatory mediators including cytokines, chemokines, proteases, and adhesion molecules were significantly increased in old stomach and these differences were further increased after indomethacin administration (p < 0.05). Furthermore, the levels of total oxidants and apoptotic executors were significantly increased in old stomach, whereas lipoxin A4 and anti-apoptotic proteins such as survivin and Bcl-2 were significantly decreased. Increased NF-κB-DNA binding activity as well as the activation of JNK and p38 was responsible for the increased expressions of inflammatory mediators as well as oxidants.

CONCLUSIONS

A preventive strategy to reduce either redox activation or pro-inflammatory mediators should be considered in older patients taking long-standing NSAID administration.

Chronic gastric ulceration causes matrix metalloproteinases-9 and -3 augmentation: alleviation by melatonin

Matrix metalloproteinases (MMPs) are a family of zinc-dependent enzymes capable of degradation of extracellular matrix (ECM) and key player in various inflammatory diseases. We investigated the regulation of MMPs in chronic gastric ulceration in mice. We generated chronic gastric ulcers in mice by indomethacin and examined the activity and expression of MMP-9 and -3 in stomach. Melatonin (N-acetyl-5-methoxytryptamine) treatment has also been applied to mice to characterize the changes in expression and activities of MMPs in gastric tissues. We observed significant upregulation of MMP-9 and -3 expressions and activities in stomach with increasing doses and duration of indomethacin that corroborated with increased activity of activator protein (AP)-1. Substantial damage in gastric epithelial layer was found during chronic ulceration. Melatonin suppressed MMP-9 and -3 expressions and activities during prevention and healing of chronic gastric ulcers. It also suppressed protein oxidation, lipid peroxidation and antioxidant enzymes. Additionally, expression of tumor necrosis factor (TNF)-α, interleukin (IL)-1β and IL-8 was significantly high in ulcerated stomachs while melatonin treatment blocked them to control level. We found elevated phosphorylation of extracellular-regulated kinase (ERK)1/2 and c-Jun N-terminal kinase (JNK) during chronic gastric ulceration, which were significantly reversed by melatonin. Moreover, expression of NF-κB, c-fos and c-jun were inhibited by melatonin resulting down regulation of MMP-9 and -3 expressions. In summary, oxidative stress is preceded by chronic inflammation that enhances the expression of MMP-9 and -3, while melatonin arrests both of them via reduction of AP-1 activity during protection of ulcer.

Revaprazan, a novel acid pump antagonist, exerts anti-inflammatory action against Helicobacter pylori-induced COX-2 expression by inactivating Akt signaling

Chronic gastric inflammation developing after Helicobacter pylori (H. pylori) infection is responsible for either dyspeptic symptom relevant to gastritis/peptic ulcer or gastric tumorigenesis, in which acid suppressants, especially proton pump inhibitors (PPIs), play role in relieving dyspepsia as well as the eradication regimen. Among several mediators engaged in propagating gastric inflammation after H. pylori infection, cyclooxygenase-2 (COX-2) might be the principal one, and several prescriptions have been made for decreasing the COX-2 levels. Multiple line of evidence are available for anti-inflammatory action of PPIs beyond acid suppression, but revaprazan, a novel acid pump antagonist launched in clinic, has also been suggested to exert significant anti-inflammatory actions as much as PPI. In the current study, we hypothesized that revaprazan could regulate H. pylori-driven COX-2 expression as one of its anti-inflammatory pharmacological actions. The changes of gastric COX-2 expression as well as responsible transcription factors were measured after H. pylori infection in the presence or absence of revaprazan. Infection of AGS cells with H. pylori induced significant up-regulation of COX-2 in time- and concentration-dependent manners, which was mediated by Akt phosphorylation. Revaprazan treatment significantly inhibited IkappaB-alpha degradation as well as Akt inactivation, resulting in attenuation of H. pylori-induced COX-2 expression. Additional rescuing action of revaprazan against H. pylori-induced cytotoxicity was noted. In conclusion, revaprazan imposed significant anti-inflammatory actions on H. pylori infection beyond acid suppression.

Toxicoproteomic analysis of a mouse model of nonsteroidal anti-inflammatory drug-induced gastric ulcers

Nonsteroidal anti-inflammatory drugs (NSAIDs) are valuable agents; however, their use has been limited by their association with mucosal damage in the upper gastrointestinal tract. NSAIDs inhibit cyclooxygenase and consequently block the synthesis of prostaglandins, which have cytoprotective effects in gastric mucosa; these effects on prostaglandins have been thought to be major cause of NSAID-induced ulceration. However, studies indicate that additional NSAID-related mechanisms are involved in formation of gastric lesions. Here, we used a toxicoproteomic approach to understand cellular processes that are affected by NSAIDs in mouse stomach tissue during ulcer formation. We used fluorogenic derivatization-liquid chromatography-tandem mass spectrometry (FD-LC-MS/MS)-which consists of fluorogenic derivatization, separation and fluorescence detection by LC, and identification by LC-tandem mass spectrometry-in this proteomic analysis of pyrolic stomach from control and diclofenac (Dic)-treated mice. FD-LC-MS/MS results were highly sensitive; 10 differentially expressed proteins were identified, and all 10 were more highly expressed in Dic-treated mice than in control mice. Specifically, expression levels of 78 kDa glucose-regulated protein (GRP78), heat shock protein beta-1 (HSP27), and gastrin were more than 3-fold higher in Dic-treated mice than in control mice. This study represents a first step to ascertain the precise actors of early NSAID-induced ulceration.

Mitigating endoplasmic reticulum stress with revaprazan ameliorates stress-related mucosal disease

BACKGROUND AND AIM

The term "stress-related mucosal disease" (SRMD) represents conditions ranging from superficial mucosal damage to focal deep mucosal damage in the stomach, of which pathogenesis is deduced to be violent mucosal ischemia or excess oxidative stress, but not fully clarified yet. Under the hypothesis that mucosal cell apoptosis subsequent to endoplasmic reticulum (ER) stress might play a crucial role, we evaluated the efficacy and mechanism that novel acid pump antagonist (APA), revaprazan, alleviated water immersion restraint stress (WIRS) induced SRMD in rats.

METHODS

In order to define whether WIRS-induced SRMD is associated with ER stress, we checked the alteration in the expression of ER stress markers including GRP78, CHOP, XBP-1, BiP as well as apoptosis in WIRS-induced SRMD. The efficacy of revaprazan on either alleviating ER stress or attenuating SRMD was compared with proton pump inhibitor (PPI) and gastroprotectant.

RESULTS

Ten hours of WIRS induced a severe degree of SRMD, in which ER stress markers including CHOP, XBP1, and BiP were significantly overexpressed in the gastric tissues. However, these markers of ER stress were significantly decreased in the group pretreated with revaprazan compared to PPI or gastroprotectant, accompanied with a significant reduction in apoptotic index. In addition to ER stress, revaprazan imposed anti-inflammatory benefit to limit SRMD based on significant levels of inflammatory cell apoptosis.

CONCLUSION

Endoplasmic reticulum stress accompanied with drastic apoptosis was implicated in the development of SRMD, but revaprazan could rescue the stomach from SRMD through alleviating ER stress in epithelial cells much better than either PPI or gastroprotectant.