Angiotensin II AT1 receptor blockade prevents gastric ulcers during cold-restraint stress

Early Guideline-Directed Medical Therapy and in-Hospital Major Bleeding Risk in ST-Elevation Myocardial Infarction Patients Treated with Percutaneous Coronary Intervention: Findings from the CCC-ACS Project

PURPOSE

Previous reports demonstrated a bleeding avoidance potential of angiotensin converting enzyme inhibitor (ACEI)/angiotensin receptor blocker (ARB) and β-blocker. It remains unclear whether early guideline-directed medical therapy [GDMT, i.e., the combined use of β-blocker, angiotensin converting enzyme inhibitor (ACEI)/angiotensin receptor blocker (ARB) and statin] confers protection against bleeding in the setting of high-intensity antithrombotic therapy.

METHODS

We assessed associations between the use of early (within the first 24 h) GDMT and in-hospital major bleeds, ischemic events and mortality among ST-elevation myocardial infarction (STEMI) patients treated with percutaneous coronary intervention (PCI) in the Improving Care for Cardiovascular Disease in China-Acute Coronary Syndrome project.

RESULTS

Among 34,538 STEMI patients without contra-indications to GDMT and eligible for analysis, 35.5% received early GDMT. In a 1-to-2 propensity-score matched cohort, compared with non-early GDMT, early GDMT was associated with a 25% reduction in major bleeds [odds ratio (OR) 0.75, 95% confidence interval (CI) 0.60-0.94], with parallel reductions in ischemic events (OR 0.60, 95%CI 0.45-0.78) and in-hospital mortality (OR 0.43, 95%CI 0.31-0.61). Early GDMT-associated reduction in major bleeds was generally consistently observed across different major bleeding definitions and in sensitivity analyses. Additionally, no significant interaction was observed in subgroup analyses.

CONCLUSION

In a large nationwide registry, early initiation of GDMT was associated with reduced risk for in-hospital major bleeds in STEMI patients treated with PCI. To improve the outcome of STEMI, further effort should be made to reinforce the early use of GDMT in this patient population.

Gastroprotective Effect of Azilsartan Through Ameliorating Oxidative Stress, Inflammation, and Restoring Hydroxyproline, and Gastrin Levels in Ethanol-Induced Gastric Ulcer

Objective

The present study was designed to evaluate the possible gastroprotective effects of different doses of azilsartan in ethanol-induced gastric ulcers in rats.

Methodology

Forty-eight male adult Wistar rats were used and allocated randomly into four groups: negative control treated with distilled water, positive control treated with ethanol, lansoprazole treated group, and azilsartan (1mg, 5mg, and 10mg/kg) treated group. The treatment protocol was for 15 days, and all the groups except for the negative control group received 1mL of ethanol on the last day 1hr before scarification. Gastric content was collected for measuring the volume, free acidity, and pH. The stomach was used for measuring the gastric lesion area and ulcer index. Blood samples were collected for measuring serum hydroxyproline, gastrin, CRP, TNF-α, MDA, and TAOC. Gastric tissues were sent for histopathological examinations.

Results

Ethanol administration significantly increased gastric lesion, gastric ulcer index, and gastric acidity. Ethanol also decreased serum levels of hydroxyproline and TAOC and increased serum gastrin, CRP, TNF-α, and MDA. Azilsartan 10mg/kg was able to decrease the lesion by 43.6% and increase gastric pH and significantly decreased MDA level. Both 5mg/kg and 10mg/kg azilsartan have successfully restored the level of hydroxyproline, gastrin, and TNF-α. The histopathological finding showed gastroprotection by azilsartan in a dose-dependent manner.

Conclusion

The study revealed that azilsartan possesses a gastroprotective effect. The proposed mechanisms could be increased blood flow to the stomach, antioxidant capacity, and anti-inflammatory activity along with restoring hydroxyproline and gastrin levels. These findings suggest azilsartan as a promising candidate to be tested in a clinical setting.

The AT-1 Angiotensin Receptor is Involved in the Autonomic and Neuroendocrine Responses to Acute Restraint Stress in Male Rats

The renin-angiotensin system (RAS) is involved in cardiovascular and hydroelectrolytic control, being associated with the development of hypertension. The restraint stress (RS) model is an aversive situation, which promotes a sustained increase in blood pressure and heart rate, and stimulation of the hypothalamic-pituitary-adrenal axis. Stress leads to an increase of angiotensin-II contents both in the circulation and the central nervous system (CNS), as well as an increased expression of AT-1 receptors in CNS structures related to stress. Stressful stimuli are associated with the modulation of autonomic nervous system, as well as baroreflex; changes in this adjustment mechanism are related to cardiovascular diseases. We hypothesized that RAS is involved in the modulation of autonomic, neuroendocrine, and functional RS-caused alterations. The intravenous (i.v) pretreatment of rats with lisinopril, an angiotensin-converting-enzyme inhibitor, reduced the RS-evoked pressor response. The doses of 0.1 and 0.3 mg/kg also reduced the RS-evoked tachycardia, while in the dose of 1 mg/kg of lisinopril potentiated the tachycardic one. Additionally, i.v. pretreatment with losartan, a selective AT-1 receptor antagonist, reduced the pressor and the tachycardic responses caused by RS. Pretreatment with lisinopril 0.3 mg/kg increased the power of the low frequency (LF) band of the systolic BP spectrum after the treatment without affecting this parameter during RS. The pretreatment with losartan 1 mg/kg increased the power of the high frequency (HF) band and reduced the LF (n.u.) and the LF/HF ratio of the pulse interval spectrum in the first hour of RS. Concerning baroreflex sensitiveness (SBR), pretreatments with losartan or lisinopril did not affect the gain of the baroreflex sequences. However, the pretreatment with losartan reduced the baroreflex effectiveness index of the total sequences in the third hour of the RS. These results indicate that Ang-II, via the AT-1 receptor, plays a facilitating influence on the cardiovascular response caused by RS; facilitates sympathetic activation and reduces parasympathetic activity related to RS; facilitates the baroreflex activation during RS and favors corticosterone release under this stress model. The impairment of Ang-II synthesis, as well as the blockade of AT-1 receptors, may constitute an important pharmacological strategy to treat cardiovascular consequences caused by stress.

Gastrointestinal bleeding in patients with renal failure under hemodialysis treatment: a single-center experience

PURPOSE

Gastrointestinal bleeding remains the leading cause of morbidity and mortality for patients who need hemodialysis treatment. Our aim was to evaluate patients who needed hemodialysis and presented with bleeding during their hospital stay (uremic bleeding patients). Factors that increased the risk of bleeding and death were evaluated. Additionally, uremic bleeding patients were compared to non-uremic bleeding patients regarding gastrointestinal findings.

PATIENTS AND METHODS

Fifty-one uremic bleeding patients were compared to two control groups which included uremic (hemodialysis dependent and non-bleeding) and non-uremic (no renal insufficiency and bleeding) patients.

RESULTS

NSAIDs and anti-ulcer drug usage were more common in uremic bleeding and in uremic non-bleeding groups, respectively. Dialysis vintage was longer in uremic bleeding group. Comparison of uremic bleeding and non-bleeding uremic patients regarding the usage of ACEI or ARB drugs yielded non-significant results. Acute kidney injury, lower plasma albumin level and high CRP level were significantly increased the risk of mortality in uremic bleeding patients. Hospital stay more than 1 week was the only strong factor for mortality when multivariate analysis was performed. Gastroduodenal and duodenal ulcers were significantly detected in uremic bleeding and non-uremic bleeding patients; respectively.

CONCLUSIONS

Hemodialysis patients presenting with gastrointestinal bleeding should be evaluated regarding use of prescriptions and efforts should be done in order to shorten their hospital stay and decrease their mortality. Effect of ACEI or ARB drugs should also be evaluated in future studies.

Sodium and Potassium Relating to Parkinson's Disease and Traumatic Brain Injury

Alkali metals, especially sodium and potassium, are plentiful and vital in biological systems. They take on important roles in health and disease. Such roles include the regulation of homeostasis, osmosis, blood pressure, electrolytic equilibria, and electric current. However, there is a limit to our present understanding; the ions have a great ability and capacity for action in health and disease, much greater than our current understanding. For the regulation of physiological homeostasis, there is a crucial regulator (renin-angiotensin system, RAS), found at both peripheral and central levels. Misregulation of the Na(+)-K(+) pump, and sodium channels in RAS are important for the understanding of disease progression, hypertension, diabetes, and neurodegenerative diseases, etc. In particular, RAS displays direct or indirect interaction important to Parkinson's disease (PD). In this chapter, the relationship between the regulation of sodium/potassium concentration and PD was sought. In addition, some recent biochemical and clinical findings are also discussed that help describe sodium and potassium in the context of traumatic brain injury (TBI). TBI is caused from the heavy striking of the head; this strongly affects ion flux in the affected tissue (brain) and damages cellular regulation systems. Thus, inappropriate concentrations of ions (hyper- and hyponatremia, and hyper- and hypokalemia) will perturb homeostasis giving rise to important and far reaching effects. These changes also impact osmotic pressure and the concentration of other metal ions, such as the calcium(II) ion.

Angiotensin II receptor blocker prevents upper gastrointestinal bleeding in hypertensive patients with chronic kidney disease not on dialysis

AIMS

Investigate if angiotensin II receptor blocker (ARB) decreases risk of upper gastrointestinal bleeding (UGIB) in hypertensive patients with chronic kidney disease (CKD) not on dialysis.

METHODS

All hypertensive patients with CKD not on dialysis in outpatient department of China Medical University Hospital from 2003 to May 2013 were enrolled. The risk of UGIB was analysed using Cox proportional hazard regression.

RESULTS

A total of 2744 hypertensive CKD patients including 1515 male and 1229 female, aged 64.9 ± 13.8 years old in a median of 1.9 (0.9-3.9) years were analysed. The incidence of UGIB was 4.5 per 100 patient-years. ARB was associated with a decreased risk of UGIB (p < 0.001) with an adjusted hazard ratio (HR) of 0.533 [95% confidence interval (CI) 0.404-0.703]. A history of UGIB, Helicobacter pylori infection, diabetes, lower estimated glomerular filtration rate, elevated blood urea nitrogen and decreased serum albumin were independently associated with an increased risk of UGIB.

CONCLUSIONS

Angiotensin II receptor blocker is associated with a decreased risk of UGIB in hypertensive CKD patients not on dialysis, independent of their renal function, history of gastrointestinal bleeding and nutrition status.

AGT A-20C (rs5050) gene polymorphism and ulcer occurrence in patients treated with low-dose aspirin: a case-control study / Polimorfismul AGT A-20C și ulcerele gastro-duodenale la pacienții sub tratament cu aspirină în doze antiagregante: studiu caz-control

Genetic factors may play a role in prediction of gastrointestinal side effects of aspirin, one of the most used drugs worldwide. We aim to determine a possible correlation between AGT A-20C (rs5050) gene polymorphism and gastro-duodenal ulcer in patients taking low-dose aspirin, adjusted for clinical and histological characteristics.

Results. We enrolled 211 patients stratified according to AGT A-20C genotype: 122 AA, 83 AC and 6 CC patients. There were no significant differences regarding demographical and clinical parameters, except for the frequency of ulcers (4%, 8.4% respective 50%, p=0.03), endoscopic bleeding signs (12.3%, 14.5% respective 50%, p=0.0001) and the frequency of gastritis in biopsy (63.9%, 54.2% respective 16.7%, p=0.03) in genotype groups. When we compared ulcer and non-ulcer group, variant homozygous CC genotype carried an increased risk for ulcer (OR:9.66, 95% CI: 1.46-63.7, p=0.04) than AA group, as well as variant C allele compared with normal A allele (OR: 2.12, 95% CI: 1.07-4.63, p=0.04). On multivariate analysis, variant homozygous CC genotype AGT A-20C showed an OR: 12.32 (95% CI:1.40 -108.13, p=0.02) for ulcer, while H. pylori infection (OR:2.40, 95% CI:1.18 -6.54, p=0.04) and concurrent use of non-steroidal anti-inflammatory drugs (NSAIDs) (OR:1.31, 95% CI:1.07 - 2.27, p=0.05) remained predictors for ulcer in aspirin consumers.

Conclusions. Variant C allele and variant homozygous CC genotype AGT A-20C, infection with H. pylori and NSAIDs co-treatment are risk factors for gastro-duodenal ulcer in low-dose aspirin consumers. The variant homozygous CC genotype AGT A-20C patients treated with LDA are more prone to have reactive gastropathy and bleeding ulcers in a population with a high prevalence of H. pylori infection

Role of renin-angiotensin system and metabolites of angiotensin in the mechanism of gastric mucosal protection

Angiotensin II, the main effector of the renin-angiotensin system (RAS), is generated from the precursor angiotensinogen by the actions of renin, angiotensin-converting enzyme, chymase and various peptidases. RAS is essential in the control of blood pressure and body fluid homeostasis but their involvement in the mechanism of the protection of gastric mucosa has not been extensively studied. On the other hand, angiotensin-(1-7) which acts on the Mas receptor, exhibits a potent vasodilatory activity and attenuates the gastric lesions induced by various ulcerogens. In this review, the mechanism of RAS, the antagonists of angiotensin AT1 and AT2 receptors and angiotensin-(1-7) in formation of gastric damage is discussed with possible translating relevance to treatment modalities in the protection against gastric mucosal injury.

Role of angiotensin-(1-7) in gastroprotection against stress-induced ulcerogenesis. The involvement of mas receptor, nitric oxide, prostaglandins, and sensory neuropeptides

Angiotensin-(1-7) [Ang-(1-7)] is a major vasoactive metabolite of angiotensin I (Ang I), both being important components of the renin-angiotensin system (RAS). Ang-(1-7) acting via Mas receptor was documented in kidneys, heart, brain, and gastrointestinal (GI)-tract. We studied the gastroprotective activity of exogenous Ang-(1-7) in rats exposed to water immersion and restraint stress (WRS) without or with A-779 [d-Ala7-Ang-(1-7), an antagonist of Ang-(1-7) Mas receptors], AVE 0991 (5-formyl-4-methoxy-2-phenyl-1[[4-[2-(ethylaminocarbonylsulfonamido)-5-isobutyl-3-thienyl]-phenyl]-methyl]-imidazole), the agonist of Ang-(1-7) receptor, as well as the inhibition of nitric-oxide (NO) synthase, the suppression of cyclo-oxygenase (COX)-1 (indomethacin, SC-560 [5-(4-chloro-phenyl)-1-(4-methoxyphenyl)-3-trifluoromethyl-pyrazole]), the activity COX-2 (rofecoxib), and denervation with capsaicin. The mRNA expression of constitutively expressed nitric-oxide synthase (cNOS), inducible nitric-oxide synthase (iNOS), interleukin (IL)-1β, and tumor necrosis factor (TNF)-α was analyzed by reverse transcription polymerase chain reaction. The WRS lesions were dose-dependently reduced by pretreatment with Ang-(1-7), which also caused an increase in gastric blood flow (GBF) and luminal content of NO. COX-1 and COX-2 inhibitors or L-NNA (N5-[imino(nitroamino)methyl]-L-ornithine) reversed the reduction in lesion number and the rise in GBF evoked by Ang-(1-7). Ang II augmented the WRS lesions, decreased GBF and increased the plasma IL-1β and TNF-α levels. Capsaicin denervation attenuated the reduction of Ang-(1-7)-induced gastric lesions and the rise in GBF; these effects were restored by supplementation with calcitonin gene-related peptide (CGRP). The cNOS mRNA was upregulated while iNOS, IL-1β and TNF-α mRNAs were downregulated in Ang-(1-7)-pretreated rats. We conclude that Ang-(1-7), in contrast to Ang II, which worsened WRS ulcerogenesis, affords potent gastroprotection against WRS ulcerogenesis via an increase in GBF mediated by NO, endogenous prostaglandins, sensory neuropeptides, and anti-inflammatory action involving the inhibition of proinflammatory markers iNOS, IL-1β, and TNF-α.

Risk and preventive factors of low-dose aspirin-induced gastroduodenal injuries: a comprehensive review

The risk of peptic ulcer complications, particularly bleeding, is increased in association with the use of low-dose aspirin (LDA). Risk factors for upper gastrointestinal (GI) ulcer or bleeding among LDA users include a history of prior GI events, older age, chronic renal failure, combined antithrombotic therapy and nonsteroidal anti-inflammatory drugs (NSAIDs). Helicobacter pylori and aspirin seem to be independent risk factors for peptic ulcer and bleeding. The studies report conflicting findings about the effect of H. pylori infection on NSAID-related ulcers, and proton-pump inhibitors (PPIs) seem to be superior to eradication only to prevent recurrent ulcer bleeding with LDA. Previous studies indicate that hypoacidity related to corpus atrophy, as well as taking PPIs and co-treatment with angiotensin type 1 receptor blockers (ARBs) and statins seem to reduce peptic ulcer among LDA users. In addition, the interleukin-1β (IL-1β)-511 T allele and angiotensinogen (AGT)-20 CC, which work as the high-producer allele of IL-1β and AGT, are significantly associated with ulcer or ulcer bleeding. The SLCO1B1*1b haplotype, which has the highest transport activity, may diminish the preventive effect of statins or ARBs. The data are still lacking and further prospective studies are needed to identify the specific risk or protective factors for upper GI ulcer and its complications associated with LDA.

Expression of angiotensin II type 1 and type 2 receptor mRNAs in the gastric mucosa of Helicobacter pylori-infected Mongolian gerbils

BACKGROUND

The renin-angiotensin system (RAS) plays an important role in normal homeostasis, carcinogenesis-related angiogenesis, and cell proliferation. Helicobacter pylori infection causes infiltration of inflammatory cells into the gastric mucosa and is considered the major cause of gastric cancer. Whether RAS plays a role in H. pylori infection-related gastric diseases remains unclear. We investigated the changes in gastric mucosal angiotensin II type 1 receptor (AT1R) and type 2 receptor (AT2R) mRNA levels throughout the time course of H. pylori infection in Mongolian gerbils.

METHODS

Mongolian gerbils were infected with wild-type H. pylori (for 12 months) or with its isogenic oipA mutant (for 3 months). Gastric mucosal AT1R and AT2R mRNA levels were assessed using real-time reverse transcription-polymerase chain reaction.

RESULTS

The gastric mucosal AT1R mRNA level was significantly associated with the severity of inflammatory cell infiltration into the gastric mucosa that reached maximal levels at 12 months after infection in both the antrum and body. Inflammatory cell infiltration scores and AT1R and AT2R mRNA levels were significantly lower in oipA mutant than wild-type infections. Mucosal AT1R and AT2R mRNA expressions in wild-type H. pylori-infected gerbils with gastric ulcers were significantly higher than in those without ulcers (P < 0.01).

CONCLUSIONS

Gastric mucosal ATR expression gradually increases during the course of H. pylori infection. Up-regulation of the RAS in association with progressive gastric inflammation suggests a potential role of the RAS in gastric carcinogenesis. OipA appears to play a role in AT1R and AT2R expression and the resulting inflammation.

Renin-angiotensin system associated with risk of upper GI mucosal injury induced by low dose aspirin: renin angiotensin system genes' polymorphism

BACKGROUND

We have previously shown that co-treatment of angiotensin type 1 receptor (AT1R) blocker (ARB) or angiotensin converting enzyme (ACE) inhibitor seem to reduce peptic ulcer among patients taking low dose aspirin. It is reported that a series of renin-angiotensin system (RAS) gene polymorphisms significantly influence the rate of the gene transcription.

AIM

The aim of this study was to examine the genotypes of RAS genes related to the risk of peptic ulcer and ulcer bleeding among patients taking low dose aspirin.

METHODS

Patients taking 100 mg of aspirin who were planning to undergo endoscopy for surveillance or who had history of recent upper GI ulcer bleeding were included. ACE (Ins/Del), angiotensinogen (AGT; G-217A, A-20C, A-6G, T174 M, M235T), and AT1R (T-713G, C-521T, A1166C) genotypes were determined by PCR or PCR-RFLP.

RESULTS

Four hundred twenty-five patients were enrolled including 68 patients with peptic ulcer and 20 patients with ulcer bleeding. Co-treatment of ARB was significantly associated with peptic ulcer and ulcer bleeding. AGT-20 CC (adjusted OR 4.94, 95% CI 1.21-20.2) was significantly associated with ulcer bleeding. The CC genotype of AT1R-521 was significantly associated with peptic ulcer only in the subgroup taking neither ACE inhibitor nor ARB.

CONCLUSIONS

Co-treatment of ARB reduces peptic ulcer and bleeding among patients taking low dose aspirin. RAS may play an important role in the development of upper GI mucosal injury induced by low dose aspirin.

Angiotensin-converting enzyme inhibition changes the metabolic response to neuroglucopenic stress

Neuroglucopenia induced by 2-deoxy-D-glucose (2DG) activates hypothalamic glucoreceptors leading to increased hepatic glucose production and insulin inhibition. This response is similar to what is observed with intravenous injection of angiotensin II (Ang II). However, the involvement of an angiotensin-converting enzyme inhibitor on neuroglucopenia has not been investigated. The aim of this study was to determine the effects of chronic enalapril treatment on plasma glucose, insulin and lipid levels in response to neuroglucopenia. Male Holtzman rats (120-170 g) were chronically treated with enalapril (10 mg/kg per day) in the drinking water for two weeks. On the day of experiment the animals received an i.v. enalapril final dose one hour before the neuroglucopenic stress by 2DG infusion (500 mg/kg), and blood samples were drawn before and 5, 10, 20, 30 and 60 minutes following infusion. The hyperglycaemic response to 2DG was not significantly changed by enalapril treatment. The enalapril-treated group exhibited a peak of plasma insulin higher than controls. Plasma triglyceride showed a significant increase only in the enalapril group after neuroglucopenic stress (p < 0.05).These data show that chronic enalapril treatment changes insulin and triglyceride responses to neuroglucopenia, suggesting an effect on glucose-induced insulin secretion and the storage of triglycerides.

Excitatory regulation of angiotensin II on gastric motility and its mechanism in guinea pig

In the present study, we investigated the effect of Ang II on gastric smooth muscle motility and its mechanism using intracellular recording and whole-cell patch clamp techniques. Ang II dose-dependently increased the tonic contraction and the frequency of spontaneous contraction in the gastric antral circular smooth muscles of guinea pig. ZD7155, an Ang II type 1 receptor (AT(1)R) blocker, completely blocked the effect of Ang II on the spontaneous contraction of gastric smooth muscle. In contrast, TTX, a sodium channel blocker, failed to block the effect. Furthermore, nicardipine, a voltage-gated Ca(2+)-channel antagonist, did not block the effect of Ang II on the tonic contraction of gastric smooth muscle, but external free-calcium almost completely blocked this effect. Both ryanodine, an inhibitor of calcium-induced Ca(2+) release (CICR) from ryanodine-sensitive calcium stores, and thapsigargin, which depletes calcium in calcium stores, almost completely blocked the effect of Ang II on tonic contraction. However, 2-APB, an inositol trisphosphate (IP(3)) receptor blocker, significantly, but not completely, blocked the Ang II effect on tonic contraction. We also determined that Ang II depolarized membrane potential and increased slow wave frequency in a dose-dependent manner. It also inhibited delayed rectifying potassium currents in a dose-dependent manner, but did not affect L-type calcium currents or calcium-activated potassium currents. These results suggest that Ang II plays an excitatory regulation in gastric motility via AT(1)R-IP(3) and the CICR signaling pathway. The Ang II-induced inhibition of delayed rectifying potassium currents that depolarize membrane potential is also involved in the potentiation of tonic contraction and the frequency of spontaneous contraction in the gastric smooth muscle of guinea pig.

Ameliorative effects of telmisartan in diabetic rats with indomethacin-induced gastric ulceration

The protective effects of telmisartan, the angiotensin II-receptor antagonist, were investigated in rats with type 2 diabetes mellitus exposed to acute gastric ulceration. Following successful induction of diabetes, telmisartan treatment (1 mg/kg/day, orally) was started and continued for 8 weeks, after which acute gastric ulceration was induced by indomethacin. Telmisartan significantly attenuated the hyperglycemia and hypoinsulinemia in diabetic rats. Also, telmisartan significantly reduced the elevations of total gastric acid output, pepsin activity, gastric ulcer index and gastric mucosal tumor necrosis factor-alpha, nitric oxide, malondialdehyde and caspase-3 activity, and restored the depleted antioxidant defenses (reduced glutathione level, and superoxide dismutase and catalase activities) caused by indomethacin administration in diabetic rats. Histopathological gastric tissue damage induced by indomethacin in diabetic rats was ameliorated by telmisartan treatment. Immunohistochemical analysis revealed that telmisartan markedly attenuated the reduction in insulin content of pancreatic islet beta-cells, and prevented the indomethacin-induced overexpression of inducible nitric oxide synthase and nuclear factor-kappaB in gastric mucosa of diabetic rats. It was concluded that telmisartan represents a potential therapeutic option to reduce the risk of gastric ulceration induced by nonsteroidal anti-inflammatory drugs in type 2 diabetic patients.

Angiotensin II-generating enzymes, angiotensin-converting enzyme (ACE) and mast cell chymase (CMA1), in gastric inflammation may be regulated by H. pylori and associated cytokines

BACKGROUND

The local angiotensin II system (LAS) has numerous functions, including the regulation of growth and differentiation in the gastrointestinal tract. Angiotensin II (AngII) may be generated by angiotensin-I-converting enzyme (ACE) or mast cell chymase (CMA1) and plays an important role in inflammatory processes, although opinions differ as to which AngII-generating enzyme is primarily associated with AngII-mediated effects. ACE inhibitors have been shown to have a protective or healing effect on gastric ulcers and colitis in animal models, which could be related to the local expression of ACE.

METHODS

The localisation of ACE and CMA1 was examined immunohistochemically in Helicobacter pylori gastritis, non-H. pylori gastritis, gastric ulcers and non-lesional gastric tissues. Using real-time qRT-PCR, ACE- and CMA1-mRNA expression in gastric cell lines were examined and changes in ACE levels after exposure to H. pylori or cytokines (IL-1beta, IL-6, IL-8, TNF, TGFbeta1) were quantified.

RESULTS

ACE and CMA1 were not expressed in the non-lesional foveolar epithelium. Cytoplasmic staining for ACE in fundic chief cells, and apical membranous expression of ACE in the mucin-secreting cells of the antral and pyloric region was observed. ACE was found in endothelial cells of the gastric ulcer granulation tissue and CMA1 was strongly expressed in mast cells. ACE but not CMA1 was expressed in the MKN28, N87 and MKN45 gastric cell lines, and ACE mRNA expression was regulated by both H. pylori and the cytokines.

CONCLUSIONS

ACE in the gastric mucosa and the microvasculature of granulation tissue may represent a novel therapeutic target for the promotion of healing processes in gastritis and ulceration using ACE inhibitors or AT1R antagonists.

Upper gastrointestinal ulcer in Japanese patients taking low-dose aspirin

BACKGROUND

There are few studies on the association of the risks of upper gastrointestinal (GI) ulcer induced by aspirin combined with other medicines. We investigated the association between peptic ulcer and clinical parameters, including Helicobacter pylori infection and combinations of medicines.

METHODS

Patients taking 100 mg aspirin for cardiovascular diseases who were planning to undergo endoscopy were enrolled. Serum H. pylori IgG antibody was measured.

RESULTS

A total of 305 patients were enrolled, and 38 patients (12.4%) had ulcer lesions. Sex, smoking, drinking, body mass index, endoscopic findings for gastric atrophy (open type), or presence of H. pylori were not significantly associated with ulcer lesions. Cotreatment with anticoagulants [ticlopidine, 34.2% vs. 21.3%; adjusted odds ratio (OR), 3.1; 95% confidence interval (CI), 1.4-7.1; ticlopidine plus warfarin, 13.2% vs. 3.7%; adjusted OR, 4.4; 95% CI, 1.3-15], proton pump inhibitor (PPI 5.3% vs. 34.8%; adjusted OR, 0.10; 95% CI, 0.02-0.43), and antihypertensive medicine were significantly associated with peptic ulcer. Among antihypertensive medicines, AT1 receptor blocker and angiotensin-converting enzyme (ACE) inhibitor tended to be associated with upper GI ulcer.

CONCLUSIONS

PPI was superior to H2-receptor antagonist for prevention of peptic ulcer, and cotreatment with AT1 receptor blocker or ACE inhibitor seemed to reduce peptic ulcer among patients taking low-dose aspirin.

Role of angiotensin Ⅱ antagonist in the formation of stress ulcer in rats

AIM: To investigate the role of angiotensins Ⅱ antagonist in the occurrence and development of stress ulcer in rats.

METHODS: The ulcer index (UI) was observed after water immersion-restaint stress (WRS), and the levels of thromboxane B₂ (TXB₂) and 6-ketoprostaglandin F₁ alpha (6-K) were measured by radioimmunoassay. The gastric mucosal pH value was detected and histopathological changes were observed.

RESULTS: In comparison with those in the negative controls, the gastric mucosal pH value and 6-K level were significantly increased in the antagonist group (4.82 ± 0.31 vs 4.53 ± 0.11, P = 0.026; 974.95 ± 109.11 ng/L vs 654.50 ± 221.31 ng/L, P < 0.01), but the TXB₂ level and UI were significant decreased (48.53 ± 8.26 ng/L vs 98.18 ± 39.24 ng/L, P < 0.01; 36.13 ± 6.49vs 69.00 ± 33.27, P < 0.01). Meanwhile, thrombosis was also decreased in the antagonist group. The level of 6-K was significantly different between the antagonist and positive control group (974.95 ± 109.11 ng/L vs 737.61 ± 96.10 ng/L, P < 0.05), but the pH value, UI and TXB₂ level had no marked difference between the two groups.

CONCLUSION: Pretreatment of angiotensins Ⅱ antagonists can protect gastric mucosa by dilatation of blood vessel and increase of blood flow, and the mechanism may be associated with the inhibition of corticosterone production and prostaglandin E₂ secretion.

CV-11974, angiotensin II type I receptor antagonist, protects against ischemia–reperfusion injury of the small intestine in rats

BACKGROUND

Angiotensin II has been implicated in the pathogenesis of vascular inflammation in various organs. The aim of the present study was to examine the effect of angiotensin II type I receptor antagonist, CV-11974, on reperfusion-induced small intestinal injury in rats.

METHODS

Intestinal damage was induced by clamping both the superior mesenteric artery and the celiac trunk for 30 min followed by reperfusion for 60 min in male Wistar rats. CV-11974 was given to the rats by intravenous injection 1 h before the vascular clamping. The intestinal mucosal injury and inflammation were evaluated by biochemical markers and histological findings. Thiobarbituric acid reactive substances and tissue-associated myeloperoxidase (MPO) activity were measured in the gastric mucosa as indices of lipid peroxidation and neutrophil infiltration. The expressions of pro-inflammatory cytokines (CINC-1) in intestinal mucosa were measured by enzyme-linked immunosorbent assay (ELISA) and reverse transcription-PCR (RT-PCR). In additional experiments with an in vitro flow system, human neutrophils were perfused on human umbilical vein endothelial cells (HUVEC) pretreated with anoxia-reoxygenation with or without CV-11974 and then the adhesive neutrophils were counted.

RESULTS

Reperfusion after ischemia resulted in an increase in luminal protein concentrations, hemoglobin concentrations, thiobarbituric acid reactive substances, and MPO activity. Pretreatment with CV-11974 significantly inhibited the increases in these parameters. CV-11974 also inhibited increases in intestinal CINC-1 protein and mRNA expression induced by ischemia-reperfusion. Moreover, in an in vitro study, CV-11974 significantly inhibited the adherence of neutrophils to HUVEC exposed to reoxygenation after anoxia.

CONCLUSIONS

These results suggest that the blockade of angiotensin II type I receptor by treatment with CV-11974 remarkably reduced the reperfusion-induced intestinal injury.

Protective Effects of Angiotensin II Interruption: Evidence for Antiinflammatory Actions

Angiotensin II, the major effector molecule produced from the renin-angiotensin-aldosterone axis, is a vasoconstrictor contributing to hypertension. Evidence indicates, however, that angiotensin II also is a potent proinflammatory mediator with growth and remodeling effects. In vitro and in vivo studies have shown that angiotensin II blockade significantly reduces concentrations of proinflammatory mediators and oxidative stress products in numerous inflammatory models. Interruption of angiotensin II activity with angiotensin-converting enzyme inhibitors and angiotensin II receptor blockers has been beneficial for patients with inflammatory diseases. Much of this benefit occurs independent of the antihypertensive effect of angiotensin II interruption, suggesting a distinctive protective mechanism. Angiotensin II receptor blockers may represent a novel class of antiinflammatory drugs with indications far beyond cardiovascular diseases.