The role of nitric oxide in the inhibition of gastric epithelial proliferation in portal hypertensive rats

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.

Effect of iNOS inhibitor on portal hypertensive gastropathy in cirrhotic rats

AIM: To investigate the effect and mechanism of aminoguanidine (AG) on the portal hypertensive gastropathy in cirrhotic rats.

METHODS: Thirty male SD rats were randomly divided into three groups: control group (n = 10), model group (n = 10) and AG treatment group (n = 10) (AG group). The model group was induced through subcutaneous injection of CCl₄ for 12 weeks, AG group was given subcutaneous injection of CCl₄ together with oral administration of AG. The morphological and histological changes in gastric mucosa were evaluated. The expression of iNOS in gastric mucosa was detected by SABC immunohistochemical methods. And the ulcer-index (UI) of gastric mucosa, and portal pressure were measured in each group.

RESULTS: Histological changes of gastric mucosa was milder and ulcer index of gastric mucosa was significantly lower in AG group than in model group (3.00 ± 2.31 vs 10.60 ± 3.47, P < 0.01). The expression of iNOS (optical density and area density) in gastric mucosa was significantly higher in model group than in control group (0.64 ± 0.04 vs 0.25 ± 0.03; 0.344 ± 0.068 vs 0.017 ± 0.008, both P < 0.01). Optical density and area density were significantly lower in AG group than in model group (0.46 ± 0.09 vs 0.64 ± 0.04; 0.159 ± 0.021 vs 0.344 ± 0.068, both P < 0.01), and the portal pressure were lower in AG group than in model group.

CONCLUSION: Aminoguanidine may ameliorate the development of portal hypertensive gastropathy through significantly inhibiting the expression of iNOS in gastric mucosa.

A case of severe recurrent hepatitis with common variable immunodeficiency

Severe hepatitis with an indistinct etiology manifested in a 16-year-old boy who had no particular history. The histological features of the liver and clinical course of the patient were similar to those of patients with autoimmune hepatitis characterized by interface hepatitis and severe lobular inflammation of the liver and recurrent exacerbations of hepatitis. We administered intravenous glycyrrhizin preparation daily or three times a week combined with the oral administration of ursodeoxycholic acid daily throughout the term after the initial onset of disease for the control of disease activity. The normalization of the concentration of alanine aminotransferase in serum was achieved in response to the therapy during the course. The serum concentration of immunoglobulins of the patient gradually decreased from the onset of the disease to an unacceptable level without globulin preparation during the following period of 17 months. Immunological tests revealed impairment of immunoglobulin production bythe B cell population of the patient, which led to the diagnosis of the patient as common variable immunodeficiency (CVID). The patient, with improved liver histology after 27 months from the onset of disease, benefited from the current combination therapy without severe infection through the avoidance of overimmunosuppression. CVID is defined as a heterogeneous syndrome characterized by various degrees of hypogammaglobulinemia without any specific predisposing causes, frequently associated with autoimmunity. Diagnostic criteria and therapeutic options of persistent hepatitis with CVID are to be established, as discussed in the current report.

Rating of CCl(4)-induced rat liver fibrosis by blood serum glycomics

BACKGROUND

Non-invasive staging of human liver fibrosis is a desirable objective that remains under extensive evaluation. Animal model systems are often used for studying human liver disease and screening antifibrotic compounds. The aim of the present study was to investigate the potential use of serum N-glycan profiles to evaluate liver fibrosis in a rat model.

METHODS

Liver fibrosis and cirrhosis were induced in rats by oral administration of CCl(4). Liver injury was assessed biochemically (alanine aminotransferase [ALT] activity, aspartate aminotransferase [AST] activity and total bilirubin) and histologically. The N-glycan profile (GlycoTest) was performed using DNA sequencer-assisted-fluorophore-assisted carbohydrate electrophoresis technology. In parallel, the effect of cotreatment with antifibrotic interferon-gamma (IFN-gamma) was studied.

RESULTS

The biopsy scoring system showed that CCl(4) induced early fibrosis (F < 1-2) in rats after 3 weeks of treatment, and cirrhosis (F4) after 12 weeks. Significant increases in ALT activity, AST activity and total bilirubin levels were detected only after 12 weeks of CCl(4) treatment. GlycoTest showed three glycans were significantly altered in the CCl(4)-goup. Peak 3 started at week 6, at an early stage in fibrosis development (F < 1-2), whereas peaks 4 and 5 occurred at week 9, at which time mild liver fibrosis (F = 1-2) had developed. The changes in the CCl(4)-IFN-gamma group were intermediate between the CCl(4)- and the control groups.

CONCLUSION

The GlycoTest is much more sensitive than biochemical tests for evaluating liver fibrosis/cirrhosis in the rat model. The test can also be used as a non-invasive marker for screening and monitoring the antifibrotic activity of potential therapeutic compounds.

Antifibrotic effects of tetrandrine on hepatic stellate cells and rats with liver fibrosis

BACKGROUND

Anti-inflammation strategies are one of the proposed therapeutic approaches to hepatic fibrosis. Tetrandrine (C(38)H(42)O(8)N(2), molecular weight: 622; Tet), an alkaloid isolated from the Chinese medicinal herb Stephania tetrandra, has been shown to exert anti-inflammatory activity in pulmonary diseases. The purpose of the present study was to investigate the in vitro and in vivo effects of Tet on hepatic fibrosis.

METHODS

A cell line of rat hepatic stellate cells (HSC-T6) was stimulated with transforming growth factor-beta1 (TGF-beta1) or tumor necrosis factor-alpha (TNF-alpha). The inhibitory effects of Tet on the nuclear factor kappaB (NFkappaB) signaling cascade and molecular markers including intercellular adhesion molecule-1 (ICAM-1) and alpha-smooth muscle actin (alpha-SMA) secretion were assessed. Fibrosis was induced by dimethylnitrosamine (DMN) administration in rats for 4 weeks. Fibrotic rats were randomly assigned to one of the four groups: vehicle (0.7% carboxyl methyl cellulose, CMC), Tet (1 mg/kg), Tet (5 mg/kg), or silymarin (50 mg/kg), each given by gavage twice daily for 3 weeks starting after 1 week of DMN administration. At the end of the study, liver tissues were scored for fibrosis and analyzed for molecular markers of fibrosis.

RESULTS

Tetrandrine (0.5-5.0 micromol/L) concentration-dependently inhibited NFkappaB transcriptional activity induced by TNF-alpha, including IkappaBalpha phosphorylation and mRNA expressions of ICAM-1 in HSC-T6 cells. In addition, Tet also inhibited TGF-beta1-induced alpha-SMA secretion and collagen deposition in HSC-T6 cells. Fibrosis scores of livers from DMN-treated rats with high-dose Tet (1.3 +/- 0.3) were significantly reduced in comparison with DMN-treated rats receiving saline (2.0 +/- 0.2). Hepatic collagen content of DMN rats was significantly reduced by either Tet or silymarin treatment. Double-staining results showed that alpha-SMA- and NFkappaB-positive cells were decreased in the fibrotic livers by Tet and silymarin treatment. In addition, mRNA expression of ICAM-1, alpha-SMA, and TGF-beta1 was attenuated by Tet treatment. Moreover, levels of plasma aspartate aminotransferase and alanine aminotransferase activities were reduced by Tet and silymarin treatment.

CONCLUSION

Tetrandrine exerts antifibrotic effects in both HSC-T6 cells and in rats with DMN-induced fibrosis.

Inhibitory effects of Ligusticum chuanxiong on the proliferation of rat hepatic stellate cells

BACKGROUND AND AIMS

Platelet-derived growth factor (PDGF) is a very potent mitogen for hepatic stellate cells (HSC) in hepatic fibrogenesis. Ligusticum chuanxiong Hort. (LC), a traditional Chinese herb used for cerebrovascular diseases, has been shown to exert anti-inflammatory and free radical scavenging effects. The aims of the present study were to investigate the effects of LC extract on the proliferation-related biomarkers in a rat HSC cell line (HSC-T6) stimulated with PDGF.

METHODS

DNA synthesis via bromodeoxyuridine (BrdU) incorporation, cell cycle related proteins and apoptosis markers were determined to evaluate the inhibitory effects of LC.

RESULTS

The results revealed that LC extract (25-100 microg/mL) concentration-dependently decreased the PDGF-induced cell proliferation as well as alpha-smooth muscle actin expression in HSC. The inhibitory activity of LC on HSC was associated with: (i) inhibition of BrdU incorporation; (ii) induction of apoptosis with the activation of caspase-3, up-regulation of cell cycle inhibitory proteins p21 and p27, and down-regulation of cell cycle stimulatory proteins cyclins D1 and D2; and (iii) increased phosphorylation of mitogen-activated protein kinases (JNK). LC at the studied concentrations showed no direct cytotoxicity on primary hepatocytes.

CONCLUSION

The results suggest that LC significantly inhibited PDGF-activated HSC proliferation, possibly through apoptotic mechanisms and the potential of LC as an antifibrotic agent warrants further investigation.

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.

Utilization of hepatoprotectants within the National Health Insurance in Taiwan

BACKGROUND

Although the hepatoprotectants of Western medicine have centuries of history, their utilization patterns have been seldom documented. Because the National Health Insurance program in Taiwan reimburses hepatoprotectant use, we could estimate the age- and sex-specific prevalence and utilization patterns of hepatoprotectants in Western medicine within the health insurance system in Taiwan.

METHODS

We analyzed the outpatient prescription data of 50000 randomly sampled insured patients in 2000. Only patients using drugs indicated for liver diseases and diagnostic codes related to liver diseases on the same visit were considered to be receiving hepatoprotectants. Drugs involved in Chinese medicine were not included.

RESULTS

Among the valid cohort of 46614 people, 783 (1.7%) were identified as patients with liver disease and receiving hepatoprotectants. Highest prevalence of hepatoprotectant use was 4.9% in the 60-69 years age group. Silymarin, multivitamins, methionine, ursodeoxycholic acid, and liver hydrolysate accounted for 88.8% of the 3215 prescribed items of hepatoprotectants. Patients receiving hepatoprotectants had, on average, visited the clinics more frequently than those not using hepatoprotectants (30 vs 14 times in a year, P < 0.001), and used more insurance benefits (US dollars 1352 vs US dollars 456, P < 0.001).

CONCLUSIONS

The frequency of use of major hepatoprotectants in Taiwan corresponded to the current modalities of treatment under discussion worldwide.

Medicinal herbs for hepatitis C virus infection: a Cochrane hepatobiliary systematic review of randomized trials

OBJECTIVE

The aim of this study was to assess beneficial and harmful effects of medicinal herbs for hepatitis C virus (HCV) infection.

METHODS

The databases of the Cochrane Collaboration, MEDLINE, EMBASE, and BIOSIS were searched combined with manual searches of five Chinese and one Japanese journals. We included randomized trials comparing medicinal herbs with placebo, no intervention, nonspecific treatment, other herbs, or interferon and/or ribavirin. Trials of herbs with or without other drug(s) were included. Methodological quality of the trials was evaluated by randomization, double blinding, and the Jadad scale.

RESULTS

Thirteen randomized trials (n = 818) evaluated 14 medicinal herbs. Four trials had adequate methodology. Compared with placebo, none of the herbs showed effects on HCV RNA or liver enzyme, except for silybin, which showed a significant reduction of serum AST and gamma-glutamyltranspeptidase levels in one trial. Oxymatrine showed effects on clearance of HCV RNA (relative risk = 9.20, 95% CI = 1.26-67.35) compared with vitamins. The herbal mixture Bing Gan Tang plus interferon-alpha showed better effects on clearance of HCV RNA (relative risk = 2.54, 95% CI = 1.43-4.49) and on normalization of serum ALT (relative risk = 2.54, 95% CI = 1.43-4.49) than interferon-alpha alone. The herbal mixture Yi Zhu decoction showed better effects on clearance of HCV RNA and normalization of ALT compared with glycyrrhizin plus ribavirin. Yi Er Gan Tang showed effects on normalizing serum ALT compared with silymarin plus glucurolactone. The herbs were associated with adverse events.

CONCLUSIONS

There is no firm evidence supporting medicinal herbs for HCV infection, and further randomized trials are justified.

Gastroduodenal mucosal defense

The gastroduodenal mucosa is a model system of defense with several structural levels and biologic strategies that are closely interrelated with each other to cope with the harmful ingredients of ingested food and the potentially deleterious effects of gastric acid and pepsin. Experimental and clinical research carried out during the review period added to the understanding of each component of the multiple mechanisms of gastroduodenal mucosal protection. In the first place, mucosal integrity is defended by the mucus gel barrier, the epithelial cell barrier, and the immune barrier. The properties of these barriers are maintained by adequate regulation of mucus production, bicarbonate secretion, mucosal microcirculation, and motor activity. These regulatory systems are alarmed by nociceptive neurons and the mucosal immune system which includes chemokine-secreting epithelial cells. The ultimate defense system is rapid repair of the injured mucosa under the control of several growth factors. Progressing insight into the network of mucosal defense not only will improve existing therapies of inflammation and ulceration but also will provide new leads for the management of functional diseases in the gastroduodenal region.

Herbal hepatotoxicity: an expanding but poorly defined problem

Alternative therapies, including herbal remedies, are popular in the general population and even more so among patients with liver disease. The use of such products is now well established in western society and is no longer confined to traditional medicine practitioners in Asia, Africa and the Middle-East. Their perceived benefits remain generally unproven and concern about adverse effects is leading to closer scrutiny of these products. Herbal hepatotoxicity has been recognized for many years, but new agents are constantly being identified. The varied manifestations of liver injury include steatosis, acute and chronic hepatitis, hepatic fibrosis, zonal or diffuse hepatic necrosis, bile duct injury, veno-occlusive disease, acute liver failure requiring liver transplantation and carcinogenesis. Potential interactions between herbal medicines and conventional drugs may interfere with patient management. Concurrent use of such products is not often disclosed unless specifically sought after and can lead to perpetuation of the liver injury. The present review focuses on emerging herbal hepatotoxins, newer patterns of liver injury among the older agents and provides an updated tabulation of the adverse effects of major herbal hepatotoxins. Key issues of diagnosis and prevention of this growing problem are addressed. Continued public education, physician awareness and more stringent licensing are required to tackle this growing problem.