Role of the posterior mucosal defense barrier in portal hypertensive gastropathy

Molecular mechanism of portal hypertensive gastropathy: An update

Portal hypertensive gastropathy (PHG) is a serious complication and the most common gastric mucosal injury amongst patients afflicted with cirrhotic or non-cirrhotic portal hypertension (PHT). The pathogenesis of PHG is not completely understood and is likely to be complex. The roles of portal hypertension pressure, parenchymal liver disease, Child-Pugh classification, variceal pressure and Helicobacter pylori infection in the development of PHG are controversial. Splanchnic blood flow, the distribution of mucosal blood, vascular ectasia, local disturbances, inflammatory cell infiltration and increased cytokine production have also been examined to elucidate the underlying mechanisms of PHG. Moreover, various other elements, including prostaglandin E2 (PGE2), endothelin-1 (ET-1), tumour necrosis factor-α (TNF-α), Fas ligand (FasL)/Fas, nitric oxide (NO), oxygen free radicals and vascular endothelial growth factor (VEGF), have also been revealed to participate in the pathogenesis of PHG. This review provides an overview of the risk factors, classification and potential molecular processes involved in PHG, followed by a concise summary of our and other studies. This review aims to integrate information to deepen our understanding of the interplay between different signalling pathways involved the pathogenesis of PHG and provides insights into how these signalling pathways are regulated to control the development of PHG.

Pharmacological targeting of gastric mucosal barrier with traditional Chinese medications for repairing gastric mucosal injury

Introduction: The gastric mucosa (GM) is the first barrier and vital interface in the stomach that protects the host from hydrochloric acid in gastric juice and defends against exogenous insults to gastric tissues. The use of traditional Chinese medications (TCMs) for the treatment of gastric mucosal injury (GMI) has long-standing history and a good curative effect. Whereas there are poor overall reports on the intrinsic mechanisms of these TCM preparations that pharmacology uses to protect body from GMI, which is crucial to treating this disease. These existing reviews have deficiencies that limit the clinical application and development of both customary prescriptions and new drugs. Methods: Further basic and translational studies must be done to elucidate the intrinsic mechanisms of influence of these TCM preparations. Moreover, well-designed and well-conducted experiences and clinical trials are necessary to ascertain the efficacy and mechanisms of these agents. Therefore, this paper presents a focused overview of currently published literature to assess how TCMs action that facilitates the cures for GMI. It offers a whole train of current state of pharmacological evidence, identifies the pharmacological mechanisms of TCMs on GM, and highlights that remarkable capacity of TCMs to restore GM after damage. Results: These TCMs preparations promote the repair of multicomponent targets such as the gastric mucus, epithelial layer, blood flow (GMBF) and lamina propria barrier. Summary: Overall, this study has summarized the essential regulatory mechanisms and pharmacological efficacy of TCMs on new and productive therapeutic targets. Discussion: This review provides an avenue for studying various drugs with potentially promising effects on mucosal integrity, as well as subsequent pharmacological studies, clinical applications, and new drug development.

p53 upregulated by HIF-1α promotes gastric mucosal epithelial cells apoptosis in portal hypertensive gastropathy

BACKGROUND

Portal hypertensive gastropathy (PHG) is a serious complication of liver cirrhosis and a potential cause of gastrointestinal bleeding. Mucosal apoptosis is an essential pathological feature of PHG. However, whether HIF-1α and p53 are involved in mucosal apoptosis and whether HIF-1α induces PHG by mediating p53 remains unclear.

METHODS

Gastric mucosal injury and apoptosis were examined in PHG patients and animal models. The mechanisms of HIF-1α- and p53-mediated apoptosis were analyzed. The GES-1 cell line was used to elucidate the underlying mechanisms using siRNA knockdown of HIF-1α and p53 in a hypoxic environment in vitro.

RESULTS

Epithelial apoptosis, HIF-1α, and p53 were markedly induced in the gastric mucosa of PHG. Apoptosis was attenuated in mice with HIF-1α- and p53-specific inhibitors. Apoptotic signaling factors were markedly induced in the gastric mucosa of PHG. Inhibition of p53 demonstrably attenuated the mucosal apoptosis; however, it did not affect HIF-1α expression. Conversely, targeted deletion of HIF-1α significantly inhibited p53 expression and attenuated the injury and p53-mediated apoptosis. Bax and Bcl-2 expression can be upregulated and downregulated by p53, respectively, to increasecleaved caspase-3 expression, which can be regulated by HIF-1α.

CONCLUSIONS

These results indicate that HIF-1α regulates the p53-induced mucosal epithelial apoptotic signaling pathway and that HIF-1α and p53 are potential therapeutic targets for PHG.