The effect of the angiotensin II receptor, type 1 receptor antagonists, losartan and telmisartan, on thioacetamide-induced liver fibrosis in rats

It has been reported previously that the density of angiotensin II receptors is increased in the rat liver in experimentally-induced fibrosis. We hypothesized that pharmacological blockade of angiotensin receptors may produce beneficial effects in models of liver fibrosis. In this study, we used the widely used thioacetamide (TAA)-induced model of liver fibrosis (300 mg/L TAA ad libitum for 12 weeks). Rats received daily injections (i.p), lasting 4 weeks of the angiotensin II type 1 receptor antagonists, losartan 30 mg/kg (TAA + L) or telmisartan 10 mg/kg (TAA + T) and were compared to rat that received TAA alone. Chronic treatment with losartan and telmisartan was associated with a significant reduction in the activity of alkaline phosphatase, and decreased concentrations of tumor necrosis factor-alpha and transforming growth factor beta-1 compared to controls. We also found a significant reduction interleukin-6 in rats receiving telmisartan (P < 0.05) but not losartan. Both treatments increased the concentration of liver glutathione along with a concomitant decrease of GSSG compared to controls. In addition, increased paraoxonase 1 activity was observed in the serum of rats receiving telmisartan group compared to the TAA alone controls. Finally, histological evaluation of liver sections revealed losartan and telmisartan treatment was associated with reduced inflammation and liver fibrosis. Taken together, these results indicate that both telmisartan and losartan have anti-inflammatory and anti-oxidative properties in the TAA model of liver fibrosis. These finding add support to a growing body of literature indicating a potentially important role for the angiotensin system in liver fibrosis and indicate angiotensin antagonists may be useful agents for fibrosis treatment.

Effects of renin-angiotensin system inhibitors on fibrosis in patients with alcoholic chronic pancreatitis

Chronic pancreatitis (CP) results in impairment of exocrine as well as endocrine functions and progressive fibrosis. Previous studies, have demonstrated the presence of renin-angiotensin system receptors within different pancreatic cells. The aim of the present study was to assess the effects of renin-angiotensin system (RAS) inhibitors on serum levels of fibrosis biomarkers (matrix metalloproteinase 2 and 9 (MMP-2, MMP-9), tissue inhibitor of MMP (TIMP- 1, TIMP-2), hyaluronic acid (HA)) and fasting glucose levels in patients with alcoholic CP. Seventy seven outpatients (mean age 43 years, 62 males) with diagnosed alcoholic CP were randomly enrolled into 5 study groups depending on the RAS inhibitors administered and their doses (2.5 or 5 mg and 12.5 or 25 mg for ramipril or losartan, respectively). Venous blood was sampled monthly for a period of one year to monitor serum drug levels. MMP-2, -9, TIMP-1, TIMP-2 and HA were measured with ELISA method on the onset and at the end of the study. Only forty five patients regularly participated in follow-up visits and completed the study. The fluctuations in serum HA levels observed among patients from the remaining groups also did not reach statistical significance. Serum MMP-2 levels (P = 0.06) and MMP-2/TIMP-1 ratio (P = 0.06) showed increasing tendency in the losartan 25 mg group. High doses of ramipril and losartan statistically significantly reduced fasting glucose levels. High doses of losartan can increase the MMP-2 activity in serum of alcoholic CP patients, which potentially is likely to affect turnover of extracellular matrix proteins within the pancreas. Moreover, high doses of both RAS inhibitors decrease the fasting glucose level.

Protective effects of melatonin against thioacetamide-induced liver fibrosis in rats

The aim of this study was to determine the effect of melatonin on thioacetamide (TAA) induced liver fibrosis in rats. The antifibrotic effects of melatonin were assessed by determining activity indirect markers of fibrosis: aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (AP), and proinflammatory cytokines: interleukin 6 (IL-6), interleukin-1beta (IL-1β), tumour necrosis factor alpha (TNF-α), transforming growth factor-beta (TGF-β) and platelet-derived growth factor (PDGF). Parameters of oxidative stress: oxidised glutathione (GSSG), reduced glutathione (GSH) and presaged activity of paraoxonase 1 (PON-1), an antioxidative enzyme were determined. Inflammatory changes and fibrosis extent were evaluated histologically. Experiments were carried out in Wistar rats. Animals were divided into 4 groups: I - controls, water ad libitum for 12 weeks, group II - TAA, 300 mg/L ad libitum for 12 weeks, III - melatonin, 10 mg/kg b.w. intraperitoneally (i.p.) daily for 4 weeks, IV - TAA, 300 mg/L ad libitum for 12 weeks followed by melatonin, 10 mg/kg/b.w. i.p. daily for 4 weeks. Results of serum determinations demonstrated significantly lower activity of AST, ALT and AP in the group receiving TAA followed by melatonin compared to the group receiving only TAA. Immunoenzymatic findings on effect of melatonin on concentration of proinflammatory cytokines confirmed these data. Biochemical examinations in liver homogenates revealed statistically significant improvement (concentration of GSH increases and concentration of GSSG decreases) in animals with TAA-induced liver damage receiving melatonin. Moreover, the activity of PON-1 toward phenyl acetate and paraoxon was increased in liver homogenates and serum in the group receiving TAA followed by melatonin compared to the TAA group without melatonin treatment. Microscopic evaluation disclosed inhibitory effects of melatonin on inflammatory changes and extent of liver fibrosis.

Effects of treatment with melatonin and tryptophan on liver enzymes, parameters of fat metabolism and plasma levels of cytokines in patients with non-alcoholic fatty liver disease--14 months follow up

Non-alcoholic fatty liver disease (NAFLD), most common chronic hepatic pathology, that occurs in the developed countries is estimated at 1/3 of the population. Amongst the numerous pathogenetic factors, oxidative stress and apoptosis of hepatocytes initiate many inflammatory processes and are involved in the progression of disease, particularly in transformation of non-alcoholic steatohepatitis (NASH) to cirrhosis. The aim of our study was to determine the effects of tryptophan and melatonin on the selected biochemical parameters in patients with NAFLD, and additionally, to evaluate the effects of tryptophan and melatonin in improvement of liver tissue in selected NAFLD patients. Seventy four patients with NAFLD confirmed by histopathological examination of liver biopsy samples, were admitted to the study. They were randomly assigned to three groups. Group I received the preparation Essentiale forte in the dose of 3 x 1 tablet per day and tryptophan 2 x 500 mg/day over the period of 14 months, group II received Essentiale forte and melatonin 2 x 5 mg/day over 14 months and group III received only Essentiale over the period of 14 months. In nine patients of groups I, II, and III, the liver biopsy was performed after 14-months of treatment period. Out of nine patients whom biopsy was performed, three of them were from group I, four from group II and two of them were from group III, respectively. After the 14-month treatment period, gamma-glutamyl transferase (GGPT) activity and levels of triglycerides and LDL-cholesterol were found to be significantly reduced in group I and II. The level of melatonin after the therapy was significantly elevated in group I and II and did not change in group III. Statistically significantly lower levels of IL-1, IL-6 and TNF-α were observed in patients receiving melatonin and tryptophan, comparing with group III treated with Essentiale forte only. These study findings demonstrate that melatonin and tryptophan substantially reduce the levels of pro-inflammatory cytokines and improve some parameters of fat metabolism in patients with NAFLD. In few patients with NASH melatonin and tryptophan reduced the inflammation in liver. We conclude that melatonin is worth considering for the therapy of NAFLD, particularly in patients with impaired fat metabolism accompanied by hypertriglyceridemia and hyper-LDL cholesterolemia.

Comparison of anti-inflammatory properties of peroxisome proliferator-activated receptor gamma agonists rosiglitazone and troglitazone in prophylactic treatment of experimental colitis

Non-specific inflammatory bowel disease (IBD), including ulcerative colitis and Crohn`s disease, is a chronic noninfectious inflammatory disease whose incidence is increasingly high, especially in the developed countries. Effective methods of its treatment and prevention of recurrences are still under investigation. Amongst the options to control effectively the inflammatory processes of the gastrointestinal tract are thiazolidinediones - peroxisome proliferator-activated receptors gamma (PPAR-γ) agonists, whose beneficial effects on macroscopic and histopathological features of colitis have been confirmed in numerous studies. In the present study, possible effects of PPAR-γ agonists rosiglitazone and troglitazone enhancing the resistance of colonic tissues to the damaging factor were examined and compared. Rats received the food with 0.01% rosiglitazone or troglitazone for 4 weeks; during the final 2 weeks, colitis-inducing 1.5% DSS (dextran sodium sulfate) was additionally administered in the drinking water. The large intestine specimens were microscopically evaluated and the levels of Th1- (IL-2, INF) and Th2-dependent (IL-4, IL-10) cytokines were determined in the serum and intestinal homogenates. Prophylactic treatment with rosiglitazone and troglitazone ameliorated colitis substantially down-regulating the microscopic inflammatory parameters. Rosiglitazone and troglitazone administered before the induction of colitis exerted comparable effects on colitis. Both substances significantly reduced the levels of pro-inflammatory cytokines and increased the levels of inflammation-limiting cytokines. We conclude that thiazolidinedione drugs are likely to be successfully used for therapy and prevention of non-specific bowel diseases.

Comparison of the anti-inflammatory and therapeutic actions of PPAR-gamma agonists rosiglitazone and troglitazone in experimental colitis

Non-specific inflammatory bowel diseases, including ulcerative colitis and Crohn`s disease, are chronic non-infectious diseases that showed an increase in prevalence in recent years, particularly in the developed countries. The effective methods of their treatment and prevention of recurrences are currently under investigation. One type of therapy that can prevent the inflammatory recurrence in the gastrointestinal tract is the PPAR-γ agonists thiazolidinediones. Numerous studies available in literature have confirmed the beneficial effects of thiazolidinediones (glitazones), namely rosiglitazone and troglitazone in the gut. The objective of the present study was to compare the possible effects of rosiglitazone 10 mg/kg b.w. or 30 mg/kg b.w. and troglitazone 30 mg/kg b.w. on experimental colitis induced by administration of 1.5% dextran sodium sulphate (DSS) administered in drinking water to rats. Specimens collected from the large intestine were microscopically evaluated, and concentrations of Th1- dependent (IL-2, INF) and Th2-dependent (IL-4, IL-10) cytokines were determined in the serum and intestinal homogenates. Both rosiglitazone and troglitazone have demonstrated significant anti-inflammatory properties. This observation was confirmed by histopathological and immunoenzymatic tests. The therapeutic efficacy of rosiglitazone was dose-dependent. Troglitazone resulted in significantly stronger enhancement of anti-inflammatory cytokine expression than rosiglitazone and comparable downregulation of pro-inflammatory cytokine expression compared to rosiglitazone used in a higher dose.

Effects of melatonin and tryptophan on healing of gastric and duodenal ulcers with Helicobacter pylori infection in humans

Melatonin (MT) and its precursor L-tryptophan (TRP) are implicated in the protection of gastric mucosa against aspirin-induced lesions and in the acceleration of healing of idiopathic gastro-duodenal ulcers, but no information is available whether these agents are also effective in healing of gastroduodenal ulcers accompanied by Helicobacter pylori (H. pylori) infection. In this study three groups A, B and C, each including 7 H. pylori-positive patients with gastric ulcers and 7 H. pylori-positive patients with duodenal ulcers, aging 28-50 years, were randomly assigned for the treatment with omeprazole 20 mg twice daily combined with placebo (group A), MT administered in a dose of 5 mg twice daily (group B) or TRP applied in a dose of 250 mg twice daily (group C). All patients underwent routine endoscopy at day 0 during which the gastric mucosa was evaluated and gastric biopsies were taken for the presence of H. pylori and histopathological evaluation. The rate of ulcer healing was determined by gastroduodenoscopy at day 0, 7, 14 and 21 after the initiation of the therapy. Plasma MT, gastrin, ghrelin and leptin were measured by specific RIA. At day 21, all ulcers were healed in patients of groups B and C but only 3 out of 7 in group A of gastric ulcers and 3 out of 7 in duodenal ulcers. Initial plasma MT showed similar low levels in all three groups but it increased several folds above initial values in ulcer patients at day 7, 14 and 21. Plasma gastrin and leptin levels showed a significant rise over initial values in patients treated with omeprazole and placebo, MT or TRP while plasma ghrelin levels were not significantly affected by these treatments. We conclude that MT or TRP added to omeprazole treatment, significantly accelerates healing rate of H. pylori infected chronic gastroduodenal ulcers over that obtained with omeprazole alone and this likely depends upon the significant rise in plasma MT and possibly also in leptin levels, both hormones involved in the mechanism of gastroprotection and ulcer healing.

Effects of peroxisome proliferator-activated receptors-gamma ligands on dextran sodium sulphate-induced colitis in rats

Recent studies indicate the involvement of peroxisone proliferator-activated receptor-γ (PPAR-γ) in the inflammatory reaction. The exact mechanism of PPAR-γ action has not been elucidated. It is supposed that PPAR-γ regulates transcription of genes responsible for encoding cytokines involved in the inflammatory response. The latest studies, carried out to explain the pathogenesis of non-specific colitis, confirm beneficial effects of PPAR-γ agonists on attenuation of colon inflammation. The aim of the present study was to assess the effects of nuclear PPAR-γ activity on the course of experimental acute colitis induced by intragastric administration of dextran sodium sulphate (DSS) using the PPAR-γ agonist rosiglitazone and the antagonist BADGE in rats. Colitis in Wistar rats was induced by 1.5% DSS administered in drinking water for 8 days. Animals with induced colitis received rosiglitazone, bisphenol A diglycidyl ether (BADGE) or both substances. After decapitation, colons were macroscopically and histopathologically evaluated. Levels of interleukin-1β (IL-1β), interleukin-6 (IL-6), interleukin-10 (IL-10), tumor necrosis factor-α (TNF-α) and myeloperoxidase (MPO) were determined in serum and colon homogenates using ELISA. In rats with experimentally induced colitis receiving rosiglitazone, the inflammatory reaction was found to be markedly limited; ulceration, oedema and infiltration activity were reduced. The activated PPAR-γ inhibit the expression of proinflammatory factors, such as IL-6, TNF-α, and neutrophil chemotaxis, which was evidenced by MPO reduction in serum and colon homogenates mediated by rosiglitazone. The positive effects of rosiglitazone on expression of IL-10 were also demonstrated. During the short period of observation, BADGE did not increase histopathological inflammatory markers.

Influence of the peroxisome proliferator-activated receptor gamma (PPAR-γ) agonist, rosiglitazone and antagonist, biphenol-A-diglicydyl ether (BADGE) on the course of inflammation in the experimental model of colitis in rats

PPAR-γ plays a role in the development of immune response, particularly in inflammation. The inflammatory reaction may be stimulated or suppressed by the presence of PPAR ligands. Some researchers suggest positive influence of the PPAR-γ agonist on suppression of the intestinal inflammatory process, yet there has not been much evidence showing that the antagonist of PPAR-γ can affect the inflammatory process. The aim of the present study was to define the mechanism by which PPAR-γ ligands affect the course of experimentally induced colitis in rats. Colitis was induced in rats by rectal administration of TNBS (trinitrobenzene sulfonate). Rosiglitazone was administrated to animals at the dose of 8 mg/kg four times via an intra-gastric probe. Biphenol-A-diglicydyl ether (BADGE) was administrated intraperitoneally at the dose of 120 mg/kg, three times every second day. One group of animals received rosiglitazone together with BADGE before the induction of inflammation. Histological and ELISA examinations of large intestine samples were performed. Levels of IL-1β, IL-6, TNF-α cytokines were determined in serum and homogenates. Rats exposed to rosiglitazone had higher body weight yet lower large intestine weight. Histological findings showed less ulceration, lower expression of crypts' loss and smaller oedema. Animals, which did not receive rosiglitazone, and those receiving it together with BADGE, developed more severe inflammatory changes. Rosiglitazone decreased the expression of inflammatory cytokines, such as IL-6 and TNF-α, both in serum and in intestinal homogenates. BADGE used with TNBS did not increase the expression of inflammatory cytokines; however, applied together with rosiglitazone, it caused inflammation similar to that observed among rats with experimentally induced colitis. Rosiglitazone reduces inflammation by decreasing the expression of IL-6 and TNF-α. BADGE administered with rosiglitazone blocks the activity of PPAR-γ and abolishes the protective effects of PPAR-γ agonist.

The effects of L-tryptophan and melatonin on selected biochemical parameters in patients with steatohepatitis

Nonalcoholic fatty liver disease is the most common chronic liver disease and nonalcocholic steatohepatitis (NASH) is its advanced form. Oxidative stress and hepatocyte apoptosis may be involved in pathogenesis of NASH and particularly in progress of NASH to liver fibrosis and cirrhosis, which are initiated by the inflammation and which promote the progress of the disease. The aim of this study was to evaluate the effects of melatonin and L-tryptophan on selected biochemical parameters of blood in patients with NASH. Forty five patients with NASH, confirmed by histopathological examination of liver biopsy samples, were admitted to the study. They were divided into three groups (I, II and III). The first group (group I, n=15) received preparation Essentiale forte 3 times a day and tryptophan 500 mg twice daily for 4 weeks. In the second group (group II, n=15), Essentiale forte three times a day was administered with melatonin 5 mg applied twice a day for 4 weeks. The third group (group III, n=15) received only Essentiale forte with placebo three times a day for 4 weeks. After four-week treatment we found statistically significant reduction in GGTP, triglycerides and proinflammatory cytokine levels in the melatonin-treated (group I) and the L-tryptophan-treated patients (group II). Plasma level of melatonin was significantly elevated in groups treated with tryptophan (group I) and melatonin (group II), but remained unchanged in placebo-treated group (group III). Among patients from the third group (treated with placebo) no statistically significant differences in the measured biochemical parameters were observed. The present study suggests that melatonin and tryptophan have the significant impact on the reduction in plasma levels of proinflammatory cytokines and may be useful in the treatment of patients with NASH.

Role of melatonin in mucosal gastroprotection against aspirin-induced gastric lesions in humans

Melatonin and its precursor, l-tryptophan, have been shown to exert gastroprotective effects in animals, but their influence on the gastric damage by aspirin (ASA) in humans has been sparingly investigated. In this study, we designed to determine the effects of melatonin and l-tryptophan on ASA-induced gastric mucosal damage, gastric microbleeding, mucosal generation of prostaglandin E(2), and plasma melatonin, and gastrin levels. Three groups of healthy male volunteers (n = 30) with intact gastric mucosa received daily for 11 days either ASA alone or that combined with melatonin or tryptophan. Gastric blood loss and mucosal damage were evaluated at 3rd, 7th, and 11th days of ASA administration by endoscopy using Lanza score. ASA alone caused a marked rise of gastric damage and gastric blood loss, mainly at day 3rd and 7th, but they were significantly reduced at 11th day. Pretreatment with melatonin or tryptophan remarkably reduced ASA induced gastric lesions and microbleeding. Gastric mucosal generation of PGE(2) was suppressed by about 90% in all subjects treated with ASA alone without or with addition of melatonin or tryptophan. Plasma melatonin was markedly increased after treatment with melatonin or tryptophan plus ASA, but it was also raised significantly after application of ASA alone. Plasma gastrin levels were raised in subjects given melatonin or tryptophan plus ASA, but not in those with ASA alone. We conclude that melatonin and its precursor tryptophan given orally significantly reduce gastric lesions induced by ASA possibly due to (a) direct gastroprotective action of exogenous melatonin or that generated from tryptophan and (b) gastrin released from the gastric mucosa by melatonin or tryptophan.

Overexpression of the fragile histidine triad (FHIT) gene in inflammatory bowel disease

OBJECTIVE

FHIT gene encodes human diadenosine triphosphate hydrolase involved in the regulation of cell cycle and nucleotide metabolism and is a candidate tumor suppressor gene.

AIM

To investigate expression of FHIT gene at the mRNA and protein levels in sporadic inflammatory bowel disease (IBD).

MATERIALS AND METHODS

FHIT mRNA was quantified by the validated real-time PCR (QPCR) and FHIT protein was detected by immunohistochemistry (IHC) in mucosal biopsies of 139 ulcerative colitis (UC), 19 Crohn's disease (CD) and 37 control patients.

RESULTS

Significant FHIT gene overexpression was found in 78% of active UC but not in CD. IHC showed comparable results to QPCR.

CONCLUSION

The local up-regulation of FHIT gene and protein expression in active UC may represent an adequate response against inflammatory challenge of epithelial cell homeostasis and protect against DNA damage and cell cycle disturbances.

Altered basal and postprandial plasma melatonin, gastrin, ghrelin, leptin and insulin in patients with liver cirrhosis and portal hypertension without and with oral administration of melatonin or tryptophan

This investigation was designed to assess the effects of oral administration of melatonin (10 mg) and tryptophan (Trp) (500 mg) on fasting and postprandial plasma levels of melatonin, gastrin, ghrelin, leptin and insulin in 10 healthy controls and in age-matched patients with liver cirrhosis (LC) and portal hypertension. Fasting plasma melatonin levels in LC patients were about five times higher (102 +/- 15 pg/mL) than in healthy controls (22 +/- 3 pg/mL). These levels significantly increased postprandially in LC patients, but significantly less so in controls. Treatment with melatonin or L-Trp resulted in a further significant rise in plasma melatonin, both under fasting and postprandial conditions, particularly in LC patients. Moreover, plasma gastrin, ghrelin, leptin and insulin levels under fasting and postprandial conditions were significantly higher in LC subjects than in healthy controls and they further rose significantly after oral application of melatonin or Trp. This study shows that: (a) patients with LC and portal hypertension exhibit significantly higher fasting and postprandial plasma melatonin levels than healthy subjects; (b) plasma ghrelin, both in LC and healthy controls reach the highest values under fasting conditions, but decline postprandially, especially after oral application of melatonin or Trp; and (c) plasma melatonin, gastrin, ghrelin and insulin levels are altered significantly in LC patients with portal hypertension compared with that in healthy controls possibly due to their portal systemic shunting and decreased liver degradation.

Melatonin and its precursor L-tryptophan prevent acute gastric mucosal damage induced by aspirin in humans

Melatonin (MT) and its precursor L-tryptophan (Trp) are implicated in the protection of gastric mucosa against noxious agents. However, the role of MT and Trp on the gastric mucosal injury induced by aspirin (ASA) in human has not been investigated. Studies in animals showed that both MT and Trp given intragastrically prevents the formation of gastric mucosal lesions induced by ASA. The aim of the present study was to determine the influence of MT and Trp given orally to healthy humans on gastric mucosal lesions induced by ASA. The present study included 21 healthy, Hp-negative male volunteers with intact gastro-duodenal mucosa aging 20-50 yr. They were divided in 3 groups; group 1: 7 volunteers receiving daily 2 x 1g ASA (Polfa, Rzeszow) during 11 days; group 2: 7 healthy volunteers receiving 2x1 g ASA and MT (Lekam, Zakroczyn) (5 mg 30 min prior to ASA) during 11 days and group 3: 7 healthy volunteers receiving 2x1 g ASA and Trp (Ardeytropin, Germany) (0.5 g 30 min prior to ASA) during 11 days. Mucosal damage was evaluated at 3(rd), 7(th) and 11(th) days of ASA administration by endoscopy using Lanza score. Plasma melatonin was measured using RIA and gastric mucosal generation of PGE(2) was assessed also by RIA. ASA caused marked mucosal injury at all days of its administration except day 11(th) when only moderate lesions were evident. Pretreatment with MT or Trp alone was accompanied by a significant decrease in gastric mucosal lesion score. Gastric mucosal generation of PGE(2) was suppressed by about 90% in subjects treated with ASA without or with MT or Trp. We concluded that: MT and its precursor Trp significantly attenuate gastric mucosal lesions induced by aspirin. The action of Trp may be be mediated by MT produced in gastrointestinal tract from Trp. The gastroprotective action of MT and Trp is independent on gastric mucosal PGE2 generation.