Defective mitogen-activated protein kinase (ERK2) signaling in gastric mucosa of portal hypertensive rats: potential therapeutic implications

Helicobacter pylori Infection in Cirrhotic Patients With Portal Hypertensive Gastropathy: A New Enigma?

The relationship between Helicobacter pylori (H. pylori) infection and Portal hypertensive gastropathy (PHG) is still a debatable matter. The aim of this study is to find out how common H. pylori infection is in cirrhotic patients with PHG and to see if there’s a link between H. pylori infection and PHG severity. Out of 340 cirrhotic patients who had upper Gastrointestinal Tract (GIT) endoscopy for early varices screening, 160 cirrhotic patients were selected and divided into 2 groups; 80 cirrhotic patients with PHG (cases) and 80 cirrhotic patients without PHG (controls). Gastric biopsies were taken from all enrolled patients for histological evaluation for the presence or absence of H. pylori infection. H. pylori was found in 44 cirrhotic patients (55%) who had PHG (cases), compared to 22 cirrhotic patients (27.5%) who did not have PHG (controls). The prevalence of H. pylori infection was significantly higher in patients with PHG (p < 0.001). The severity of PHG was associated with H. pylori infection (p < 0.001). The response to eradication therapy of H. pylori infection was must better in patients without PHG (p = 0.045). By multi-variant analysis, H. pylori infection, splenic diameter, and portal vein diameter were independent predictors for PHG presence. After treating H. pylori infection in patients who tested positive for H. pylori, there was a significant reduction in PHG severity (p < 0.001). Patients with PHG have a greater prevalence of H. pylori infection. PHG is more severe in patients infected with H. pylori. To improve PHG severity, cirrhotic patients must have their H. pylori infection eradicated.

The relationship between portal hypertension and portal hypertensive gastropathy

BACKGROUND AND AIM

Portal hypertensive gastropathy (PHG) most commonly occurs in the setting of increased portal pressure in patients with cirrhosis. Here, we aimed to understand the correlation between hepatic venous pressure gradient (HVPG) and the presence and severity of PHG in patients with cirrhosis.

METHODS

We examined patients with cirrhosis who underwent HVPG measurement at the Medical University of South Carolina between 2014 and 2020. Extensive demographic, clinical, laboratory, procedural (including precise grading of PHG severity using standard definitions), and outcome data were abstracted at the time of HVPG measurement.

RESULTS

Three hundred and ten patients with HVPG measurements and cirrhosis were identified. Seventy-three patients having endoscopy within 6 months of HVPG measurement were included (mean age 54 ± 11, 44% female). The most common causes of cirrhosis were alcohol (41%) and non-alcoholic steatohepatitis (32%). The average HVPG was 15 mmHg (±6) and 62 patients had clinically significant portal hypertension (CSPH) (HVPG ≥ 10 mmHg). Of the 73 patients with HVPG measured, 45 (62%) had PHG, including 40 (89%) of whom had CSPH. Out of the 45 patients with PHG, 41 and four had mild or severe PHG, respectively. MELD scores were similar in patients with and without PHG [15 ± 9 (SD) and 17 ± 9, respectively; p = .37]. HVPG was higher in patients with PHG (17 ± 7 mmHg) than those without PHG (13 ± 4 mmHg) (p = .01) but did not differ between mild and severe PHG.

CONCLUSION

A weak correlation exists between HVPG level and the presence of PHG.

Role of the posterior mucosal defense barrier in portal hypertensive gastropathy

Portal hypertensive gastropathy (PHG) is a complication of cirrhotic or noncirrhotic portal hypertension. PHG is very important in the clinic because it can cause acute or even massive blood loss, and its treatment efficacy and prognosis are poor. Currently, the incidence of PHG in patients with cirrhosis is 20-80%, but its pathogenesis is complicated and poorly understood. Studies have shown that portal hypertension can cause changes in gastric mucosal microcirculation hemodynamics, leading to changes in gastric mucosal histology and function and thereby weakening the mucosal defense barrier. However, no specific drug treatment plans are currently available. This article reviews the current literature to further our understanding of the mechanism underlying PHG and the relationship between PHG and the posterior mucosal defense barrier and to explore new therapeutic targets.

Portal hypertensive vasculopathy - An entity worth remembering with non-neoplastic gastrointestinal lesions

Portal hypertensive vasculopathy (PHV) represents an increase in the pressure in the portal circulation. This increased pressure leads to changes in the mucosa that can be appreciated endoscopically as well as histopathologically. Lesions can be observed in the entire gastrointestinal tract (GIT) including stomach, duodenum, jejunum and colon. The histological changes are appreciated mainly in the mucosal and submucosal blood vessels. A knowledge of these lesions as well as the changes helps in separating them from other close differentials with specific treatment to be instituted. The pathogenesis of the hemodynamic changes is not well-understood. The underlying factor is increased portal pressure. Studies indicate, that besides increased portal pressure other factors in combination led to the observed changes. Portal hypertensive gastropathy (PHG) is seen in the gastric body and fundus, while varices are noted in the cardia and fundus. Changes may be seen in the small intestine and throughout the colon with anorectal varices. Histopathological changes include dilated, congested and ectatic capillaries and edema in the lamina propria besides a large spectrum of other histopathological changes. Mucosal capillaries with thick irregular wall show absence of red blood cells in the lumen. Thickening of the vessel wall serves as a better marker than the vascular diameter when portal hypertension (PHT) is considered. Long standing cases may show fibrosis in lamina propria. At times, these changes may lead to occult gastrointestinal bleeding. Important differentials need to be ruled out in all the cases as the treatment and the outcome of all differs. Endoscopically or histopathologically if the mucosal changes are observed they should not be overlooked and a detailed work-up must be carried out.

Transjugular intrahepatic portosystemic shunt in cirrhosis: An exhaustive critical update

More than five decades after it was originally conceptualized as rescue therapy for patients with intractable variceal bleeding, the transjugular intrahepatic portosystemic shunt (TIPS) procedure continues to remain a focus of intense clinical and biomedical research. By the impressive reduction in portal pressure achieved by this intervention, coupled with its minimally invasive nature, TIPS has gained increasing acceptance in the treatment of complications of portal hypertension. The early years of TIPS were plagued by poor long-term patency of the stents and increased incidence of hepatic encephalopathy. Moreover, the diversion of portal flow after placement of TIPS often resulted in derangement of hepatic functions, which was occasionally severe. While the incidence of shunt dysfunction has markedly reduced with the advent of covered stents, hepatic encephalopathy and instances of early liver failure continue to remain a significant issue after TIPS. It has emerged over the years that careful selection of patients and diligent post-procedural care is of paramount importance to optimize the outcome after TIPS. The past twenty years have seen multiple studies redefining the role of TIPS in the management of variceal bleeding and refractory ascites while exploring its application in other complications of cirrhosis like hepatic hydrothorax, portal hypertensive gastropathy, ectopic varices, hepatorenal and hepatopulmonary syndromes, non-tumoral portal vein thrombosis and chylous ascites. It has also been utilized to good effect before extrahepatic abdominal surgery to reduce perioperative morbidity and mortality. The current article aims to review the updated literature on the status of TIPS in the management of patients with liver cirrhosis.

An Update: Portal Hypertensive Gastropathy and Colopathy

Complications of portal hypertension include portal hypertensive gastropathy and colopathy. These disorders may cause chronic or acute gastrointestinal bleeding. The diagnosis is made endoscopically; therefore, there is great variability in their assessment. Portal hypertensive gastropathy can range from a mosaic-like pattern resembling snakeskin mucosa to frankly bleeding petechial lesions. Portal hypertensive colopathy has been less well-described and is variably characterized (erythema, vascular lesions, petechiae). Treatment is challenging and results are inconsistent. Currently, available evidence does not support the use of beta-blockers for primary prevention. Further investigation of the pathogenesis, natural history, and treatment of these disorders is needed.

Comparison of Efficacy of Laparoscopic and Open Splenectomy Combined With Selective and Nonselective Pericardial Devascularization in Portal Hypertension Patients

BACKGROUND

Recent advances in laparoscopic techniques have demonstrated that laparoscopy is superior for managing portal hypertension. This study aimed to compare the efficacy of laparoscopic splenectomy plus selective pericardial devascularization (LSSD) and open splenectomy and nonselective pericardial devascularization (OSD) in patients with portal hypertension.

METHODS

A total of 127 patients with portal hypertension underwent either LSSD or OSD at Jingzhou Central Hospital from January 2014 to December 2016. A total of, 55 patients received LSSD, including 29 male and 26 female individuals (age, 56.0±11.6 y); 72 patients received OSD, including 45 male and 27 female individuals (age, 53.4±10.9 y). The parameters of operation and outcomes were measured and compared.

RESULTS

Intraoperative blood loss, postoperative complications, and hospital stay were significantly lower in LSSD group but operation time was significantly lower in OSD group. Postoperative Child-Pugh score was significantly lower in LSSD group than in OSD group.

CONCLUSIONS

LSSD is a safe and effective treatment for liver cirrhosis patients with portal hypertension.

Portal hypertensive gastropathy: A systematic review of the pathophysiology, clinical presentation, natural history and therapy

AIM

To describe the pathophysiology, clinical presentation, natural history, and therapy of portal hypertensive gastropathy (PHG) based on a systematic literature review.

METHODS

Computerized search of the literature was performed via PubMed using the following medical subject headings or keywords: "portal" and "gastropathy"; or "portal" and "hypertensive"; or "congestive" and "gastropathy"; or "congestive" and "gastroenteropathy". The following criteria were applied for study inclusion: Publication in peer-reviewed journals, and publication since 1980. Articles were independently evaluated by each author and selected for inclusion by consensus after discussion based on the following criteria: Well-designed, prospective trials; recent studies; large study populations; and study emphasis on PHG.

RESULTS

PHG is diagnosed by characteristic endoscopic findings of small polygonal areas of variable erythema surrounded by a pale, reticular border in a mosaic pattern in the gastric fundus/body in a patient with cirrhotic or non-cirrhotic portal hypertension. Histologic findings include capillary and venule dilatation, congestion, and tortuosity, without vascular fibrin thrombi or inflammatory cells in gastric submucosa. PHG is differentiated from gastric antral vascular ectasia by a different endoscopic appearance. The etiology of PHG is inadequately understood. Portal hypertension is necessary but insufficient to develop PHG because many patients have portal hypertension without PHG. PHG increases in frequency with more severe portal hypertension, advanced liver disease, longer liver disease duration, presence of esophageal varices, and endoscopic variceal obliteration. PHG pathogenesis is related to a hyperdynamic circulation, induced by portal hypertension, characterized by increased intrahepatic resistance to flow, increased splanchnic flow, increased total gastric flow, and most likely decreased gastric mucosal flow. Gastric mucosa in PHG shows increased susceptibility to gastrotoxic chemicals and poor wound healing. Nitrous oxide, free radicals, tumor necrosis factor-alpha, and glucagon may contribute to PHG development. Acute and chronic gastrointestinal bleeding are the only clinical complications. Bleeding is typically mild-to-moderate. Endoscopic therapy is rarely useful because the bleeding is typically diffuse. Acute bleeding is primarily treated with octreotide, often with concomitant proton pump inhibitor therapy, or secondarily treated with vasopressin or terlipressin. Nonselective β-adrenergic receptor antagonists, particularly propranolol, are used to prevent bleeding after an acute episode or for chronic bleeding. Iron deficiency anemia from chronic bleeding may require iron replacement therapy. Transjugular-intrahepatic-portosystemic-shunt and liver transplantation are highly successful ultimate therapies because they reduce the underlying portal hypertension.

CONCLUSION

PHG is important to recognize in patients with cirrhotic or non-cirrhotic portal hypertension because it can cause acute or chronic GI bleeding that often requires pharmacologic therapy.

Portal hypertensive gastropathy and colopathy

Portal hypertensive gastropathy (PHG) and colopathy (PHC) are considered complications of portal hypertension. Both entities are clinically relevant because they may cause insidious blood loss or even acute massive gastrointestinal hemorrhage. Endoscopic evaluation is necessary for the diagnosis of PHG and PHC. The existence of different endoscopic criteria for PHG and PHC makes consensus difficult and results in a broad range of reported prevalence. Therapy targeted at reduction of portal pressure and mucosal blood flow has been used to treat acute bleeding; nonselective β-blockers are the most frequently used agents. Further studies are needed to clarify the natural history, pathogenesis, and treatment of PHG and PHC.

Increased oxidative stress may lead to impaired adaptive cytoprotection in the gastric mucosa of portal hypertensive rat

BACKGROUND AND AIMS

In the gastric mucosa of portal hypertensive rats, adaptive cytoprotection against ethanol-induced damage is impaired. The aim of this study was to determine relation between impaired adaptive cytoprotection and oxidative stress.

METHODS

Portal hypertension was produced in male Sprague-Dawley rats by inducing staged portal vein occlusion. Oxidative stress levels were evaluated by measuring malondialdehyde and nitrotyrosine levels in the rat gastric mucosa with or without 10% ethanol pretreatment. Inhibition of oxidative stress by an anti-oxidant agent was estimated, and glutathione levels were also measured. Adaptive cytoprotection to 70% ethanol treatment was evaluated by measuring the gastric mucosal injury index in the presence or absence of the anti-oxidant.

RESULTS

The portal hypertensive gastric mucosa pretreated with 10% ethanol had significantly higher oxidative stress levels than the mucosa not pretreated with 10% ethanol. However, the sham-operated gastric mucosa pretreated with 10% ethanol had significantly lower oxidative stress levels than the mucosa not pretreated with 10% ethanol. Pretreatment with 10% ethanol increased glutathione levels in the sham-operated but not in the portal hypertensive gastric mucosa. Administration of the anti-oxidant agent prior to 10% ethanol pretreatment significantly reduced oxidative stress levels, increased glutathione levels, and decreased the injury index in response to 70% ethanol in the portal hypertensive gastric mucosa.

CONCLUSION

Increased oxidative stress may lead to impaired adaptive cytoprotection in the gastric mucosa of portal hypertensive rats, probably through damage to the system of endogenous anti-oxidant production.

Loss of parietal cell superoxide dismutase leads to gastric oxidative stress and increased injury susceptibility in mice

Mitochondrial superoxide dismutase (SOD2) prevents accumulation of the superoxide that arises as a consequence of oxidative phosphorylation. However, SOD2 is a target of oxidative/nitrosative inactivation, and reduced SOD2 activity has been demonstrated to contribute to portal hypertensive gastropathy. We investigated the consequences of gastric parietal cell-specific SOD2 deficiency on mitochondrial function and gastric injury susceptibility. Mice expressing Cre recombinase under control of the parietal cell Atpase4b gene promoter were crossed with mice harboring loxP sequences flanking the sod2 gene (SOD2 floxed mice). Cre-positive mice and Cre-negative littermates (controls) were used in studies of SOD2 expression, parietal cell function (ATP synthesis, acid secretion, and mitochondrial enzymatic activity), increased oxidative/nitrosative stress, and gastric susceptibility to acute injury. Parietal cell SOD2 deficiency was accompanied by a 20% (P < 0.05) reduction in total gastric SOD activity and a 93% (P < 0.001) reduction in gastric SOD2 activity. In SOD2-deficient mice, mitochondrial aconitase and ATP synthase activities were impaired by 36% (P < 0.0001) and 44% (P < 0.005), respectively. Gastric tissue ATP content was reduced by 34% (P < 0.002). Basal acid secretion and peak secretagogue (histamine)-induced acid secretion were reduced by 43% (P < 0.0001) and 40% (P < 0.0005), respectively. There was a fourfold (P < 0.02) increase in gastric mucosal apoptosis and 41% (P < 0.001) greater alcohol-induced gastric damage in the parietal cell SOD2-deficient mice. Our findings indicate that loss of parietal cell SOD2 leads to mitochondrial dysfunction, resulting in perturbed energy metabolism, impaired parietal cell function, and increased gastric mucosal oxidative stress. These alterations render the gastric mucosa significantly more susceptible to acute injury.

The management of portal hypertensive gastropathy and gastric antral vascular ectasia

Portal hypertensive gastropathy and gastric antral vascular ectasia are gastric mucosal lesions that can cause chronic gastrointestinal haemorrhage and, consequently, chronic anaemia, in patients with cirrhosis. Although chronic anaemia is the most common clinical manifestation, these entities may also lead to acute gastrointestinal bleeding. Despite similar clinical manifestations, their pathophysiology and management are entirely different. Their diagnosis is endoscopic and although generally each of them has a characteristic endoscopic appearance and distribution, there are cases in which the differential is difficult and must rely on histology. This review focuses on the management of both entities. The mainstay of management of portal hypertensive gastropathy is based on portal-hypotensive pharmacological treatment whilst gastric antral vascular ectasia benefits from endoscopic therapy. More invasive options should be reserved for refractory cases.

Management of gastropathy and gastric vascular ectasia in portal hypertension

Portal hypertensive gastropathy and gastric antral vascular ectasia may cause gastrointestinal hemorrhage in patients with portal hypertension. Whereas the former presents exclusively in patients with portal hypertension, gastric antral vascular ectasia can also be observed in patients with other conditions. Diagnosis is established with upper gastrointestinal endoscopy, although some cases may require a biopsy to confirm the diagnosis. The most frequent manifestation is ferropenic anemia, which may become transfusion dependent. Treatment in portal hypertensive gastropathy is focused on portal pressure reducing drugs, mainly nonselective beta-blockers, whereas in gastric antral vascular ectasia treatment is based on endoscopic ablation. More invasive options can be used if first-line therapies fail, although these should be evaluated on a case-by-case basis.

Effect of laparoscopic splenectomy on portal hypertensive gastropathy in cirrhotic patients with portal hypertension

AIM

This study investigated the relationship between portal hypertensive gastropathy (PHG) and splenomegaly, and the effect of laparoscopic splenectomy on PHG in cirrhotic patients with portal hypertension.

METHODS

Seventy patients with liver cirrhosis and portal hypertension were prospectively studied. Indication for laparoscopic splenectomy was bleeding tendency in 10 patients, induction of interferon in 45, treatment of hepatocellular carcinoma in seven, and treatment for endoscopic injection sclerotherapy-resistant esophagogastric varices in eight. The severity of PHG was classified into none, mild, or severe according to the classification by McCormack et al. The severity of liver disease was classified using the Child-Pugh score. All patients underwent upper gastrointestinal endoscopy before and 1 month after the operation.

RESULTS

The prevalence of PHG was significantly correlated with the severity of liver disease using the Child-Pugh score. The severity of PHG was significantly correlated with the resected spleen volume. One month after the operation, PHG was improved in 16 of 17 patients with severe PHG and in 12 of 32 with mild PHG. The Child-Pugh score showed a significant improvement (6.8 +/- 1.4 to 6.2 +/- 1.2) at 3 months after laparoscopic splenectomy (P < 0.0001).

CONCLUSIONS

PHG may be associated with splenomegaly, and laparoscopic splenectomy may have a beneficial effect on PHG, at least for a short time.

Activation of MEK 1/2 and p42/44 MAPK by angiotensin II in hepatocyte nucleus and their potentiation by ethanol

Hepato-subcellular effect of angiotensin II (Ang II) and ethanol on the p42/44 mitogen-activated protein kinase (MAPK) and MAPK kinase (MEK 1/2) was investigated in the nucleus of rat hepatocytes. Hepatocytes were treated with ethanol (100 mM) for 24h and stimulated with Ang II (100 nM, 5 min). The levels of p42/44 MAPK and MEK 1/2 were monitored in the nuclear fraction using antibodies. Ang II itself caused significant accumulation of phosphorylated p42/44 MAPK (phospho-p42/44 MAPK) in the nucleus without any significant translocation of p42/44 MAPK protein thereby suggesting activation of p42/44 MAPK in the nucleus. Ang II caused marked accumulation of phosphorylated MEK 1/2 (phospho-MEK 1/2) in the nucleus without any significant accumulation of MEK 1/2 protein. Ratio of phospho-MEK 1/2 to MEK 1/2 protein in the nucleus after Ang II treatment was 2.4 times greater than control suggesting phosphorylation of MEK 1/2 inside the nucleus. Ethanol had no effect on the protein level or the activation of p42/44 MAPK in the nucleus. Ethanol treatment potentiated nuclear activation of p42/44 MAPK by Ang II but not translocation of p42/44 MAPK protein. This was accompanied by potentiation of Ang II-stimulated accumulation of phospho-MEK 1/2 in the nucleus by ethanol. MEK 1/2 inhibitor, U-0126 inhibited Ang II response and its potentiation by ethanol. These results suggest that Ang II-mediated accumulation of phospho-p42/44 MAPK in the hepatocyte nucleus involves MEK 1/2-dependent activation and this effect is potentiated by ethanol.

Significance of ERK nitration in portal hypertensive gastropathy and its therapeutic implications

Portal hypertensive (PHT) gastric mucosa increases susceptibility to injury and delayed mucosal healing. It is possible that nitration of ERK by peroxynitrite might alter MAPK (ERK) signaling in PHT gastric mucosa, leading to delayed mucosal healing, since excessive nitric oxide production is implicated in PHT gastric mucosa and MAPK (ERK) signaling induces cell proliferation and leads to gastric mucosal healing in response to injury. Portal hypertension was produced by staged portal vein ligation, and sham-operation (SO) rats served as controls. Lipid peroxide (LPO) and nitrotyrosine increased significantly in PHT gastric mucosa compared with SO rats. ERK activation was impaired in PHT gastric mucosa in response to ethanol injury, whereas no significant difference in the phosphorylation of MEK, an upstream molecule of ERK, was seen between the two groups. The nitration of ERK by peroxynitrite, as detected by the coimmunoprecipitation of ERK and nitrotyrosine, was significantly enhanced in PHT gastric mucosa. Administration of rebamipide, a gastroprotective drug that acts as an oxygen-derived free radical scavenger, significantly decreased LPO and nitrotyrosine as well as the nitration of ERK by peroxynitrite in PHT gastric mucosa, therefore normalizing ERK activation and restoring the gastric mucosal healing response to ethanol injury. Enhanced nitration of ERK by peroxynitrite is involved in the impaired MAPK (ERK) signaling in PHT gastric mucosa. These findings demonstrate a new molecular mechanism in which PHT gastric mucosa is predisposed to injury and impaired healing.

Zinc L-carnosine protects against mucosal injury in portal hypertensive gastropathy through induction of heat shock protein 72

BACKGROUND AND AIMS

Increased susceptibility to gastric mucosal injury is observed in portal hypertensive gastropathy (PHG). In this study, the effects of zinc L-carnosine, an anti-ulcer drug, were evaluated on expression of heat shock protein (hsp) 72 and cytoprotection in gastric mucosa in a rat model of PHG.

METHODS

Portal hypertensive gastropathy with liver cirrhosis was induced by bile duct ligation for 4 weeks in male Sprague-Dawley rats. Expression of gastric mucosal hsp72 was evaluated by Western blotting at 6 h after intragastric administration of L-carnosine, zinc sulfate, or zinc L-carnosine. Blood was also collected for determination of serum zinc level. Mucosal protective abilities against hydrochloric acid (HCl) (0.6N) followed by pretreatment with L-carnosine, zinc sulfate or zinc L-carnosine were also studied.

RESULTS

L-carnosine, zinc sulfate, and zinc L-carnosine induced hsp72 in gastric mucosa of rats with bile duct ligation. Zinc sulfate and zinc L-carnosine suppressed HCl-induced mucosal injury. However, L-carnosine could not suppress HCl-induced mucosal injury. Serum zinc levels were significantly elevated after zinc L-carnosine administration. Furthermore, pretreatment with zinc L-carnosine (30-300 mg/kg) increased the expression of hsp72 in gastric mucosa and prevented HCl-induced mucosal injury in rats with bile duct ligation in a dose-dependent manner.

CONCLUSIONS

Zinc derivatives, especially zinc L-carnosine, protected portal hypertensive gastric mucosa with increased hsp72 expression in cirrhotic rats. It is postulated that zinc L-carnosine may be beneficial to the mucosal protection in PHG as a 'chaperone inducer'.

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Quercetin prevents oxidative stress and NF-kappaB activation in gastric mucosa of portal hypertensive rats

The present study was designed to investigate the effects of quercetin on oxidative stress and activation of nuclear factor kappa B (NF-kappaB) in an experimental model of portal hypertensive gastropathy induced by partial portal vein ligation (PPVL). Portal pressure was significantly elevated in PPVL rats. Transaminase and alkaline phosphatase activities were not significantly modified, indicating absence of liver injury. Histological analysis of gastric sections showed a lost of normal architecture, with edema and vasodilatation. The cytosolic concentration of thiobarbituric acid reactive substances and the lipoperoxidation measurement by chemiluminiscence were significantly increased. Superoxide dismutase activity in gastric mucosa was significantly reduced. Portal hypertensive gastropathy induced a marked activation of NF-kappaB, accompanied by a decrease in IkappaB protein levels and a significant induction of nitric oxide synthase (iNOS) protein. Administration of quercetin markedly alleviated histological abnormalities and inhibited oxidative stress and NF-kappaB activation. IkappaB decrease and induction of iNOS protein were partially prevented by quercetin. Quercetin treatment, by abolishing the NF-kappaB signal transduction pathway, may block the production of noxious mediators involved in the pathogenesis of portal hypertensive gastropathy.

Role of acute elevation of portal venous pressure by exogenous glucagon on gastric mucosal injury in rats with portal hypertension

Time-course studies revealed the increased susceptibility of the gastric mucosa to noxious injury in portal hypertension correlates with the level of elevated portal venous pressure and hyperglucagonemia. Whether acute elevation of portal venous pressure by exogenous glucagon aggravates such injury is not known. We tested the hypothesis that glucagon in a dose sufficient to acutely elevate portal venous pressure aggravates noxious injury of the gastric mucosa in rats with portal hypertension. Infusion of a portal hypotensive dose of somatostatin should reverse these changes. In anesthetized rats with portal vein ligation, glucagon, somatostatin or the combination was administered intravenously in a randomized, coded fashion. Acidified ethanol-induced gastric mucosal injury was determined. Portal venous pressure and gastric mucosal perfusion and oxygenation (reflectance spectrophotometry) were monitored to confirm the effects of the respective intravenous treatments. Exogenous glucagon exacerbated acidified ethanol-induced gastric mucosal injury. The exacerbation was attenuated by somatostatin. These changes paralleled the portal hypertensive and hypotensive effects of glucagon and somatostatin, respectively. Our data suggest that a unique mechanism is triggered with the onset of portal hypertension. In an antagonistic manner, glucagon and somatostatin modulate this novel mechanism that controls portal venous pressure and susceptibility of the gastric mucosa to noxious injury.

Portal Hypertensive gastropathy

Portal hypertensive gastropathy (PHG), a term used to describe the endoscopic appearance of gastric mucosa with a characteristic mosaic-like pattern with or without red spots, is a common finding in patients with portal hypertension. Current classification systems that describe the severity of PHG have many limitations, but it appears that simple grading systems have better inter- and intraobserver agreement. The wide variation in the reported prevalence of PHG is probably related to selection bias, absence of uniform criteria and classification, and more importantly, the differences in inter- and intraobserver variation. Pathogenesis of PHG is not clearly defined, but there is a very close relationship between portal hypertension and development of PHG. GAVE is a separate entity from PHG, but patients with severe PHG may have a GAVE-like appearance in the gastric antrum. Acute bleeding from PHG, seen usually in the presence of severe PHG, is often mild and self-limiting. Currently, the only treatment that could be recommended for prophylaxis of bleeding from PHG is nonselective B-blockers.