Attenuation of Gastric Mucosal Inflammation Induced by Aspirin Through Inhibition of Selective Type III Phospshodiesterase in Rats

Cilostazol, a selective type III phosphodiesterase inhibitor, is widely used for treatment of ischemic symptoms of peripheral vascular disease. Recent studies have reported that the mechanism of cilostazol is related to suppression of pro-inflammatory cytokine production and improvement of local microcirculation disturbances. The activation of inflammatory cells and pro-inflammatory cytokine production play critical roles in the pathogenesis of aspirin-induced gastric irritation. The aim of the present study was to determine whether cilostazol can ameliorate aspirin-induced gastric mucosal lesions in rats, reduce neutrophil accumulation, and reduce the production of pro-inflammatory cytokines. Gastric lesions were produced by oral gavage of aspirin (200 mg/kg) and HCl (0.15 N, 8.0 ml/kg). Cilostazol (1–10 mg/kg, IP) was injected 30 min before aspirin administration. Also, we measured the gastric mucosal concentrations of myeloperoxidase and interleukin-1 β, tumor necrosis factor-α, and cytokine-induced neutrophil chemoattractants-1, as an index of neutrophil accumulation, and the pro-inflammatory cytokines. Cilostazol ameliorated the gastric mucosal lesions induced by aspirin administration (P < 0.01). The gastric contents of myeloperoxidase and pro-inflammatory cytokines were all increased after aspirin administration and significantly reduced by cilostazol treatment. In this study, we demonstrated that a selective type III phosphodiesterase inhibitor, cilostazol, reduced aspirin-induced gastric inflammation and damage via suppression of the production of proinflammatory cytokines. Cilostazol may be useful for preventing gastric mucosal lesions induced by aspirin. ^*These authors contributed equally to this work.     

Selective adenosine A receptor agonist, ATL-146e, attenuates stress-induced gastric lesions in rats

BACKGROUND: Activation of adenosine A(2A) receptors reduces the production of various pro-inflammatory cytokines and suppresses neutrophil activation. Water-immersion restraint is well known to cause gastric mucosal lesions due to stress. The pathogenesis of stress-induced gastric mucosal lesions is characterized by activation of inflammatory cells and production of inflammatory cytokines. Agonists of adenosine A(2A) receptors are known to be anti-inflammatory, but the effects of these compounds on the development of gastric mucosal lesions has not been reported. In the present study, the effect of a potent and selective adenosine A(2A) receptor agonist, ATL-146e, on water-immersion stress-induced gastric mucosal lesions was studied. METHODS: Rats were subjected to water-immersion stress with or without pretreatment with a single intraperitoneal injection of a potent and selective agonist of the adenosine A(2A) receptor. The gastric concentrations of myeloperoxidase (MPO), as an index of neutrophil accumulation, and the pro-inflammatory cytokines, tumor necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta), were measured. RESULTS: The total length of gastric erosions (ulcer index) in control rats was 21.6 +/- 3.23 mm and was reduced by 86% to 3.1 +/- 0.83 mm by pretreatment with 5.0 microg/kg ATL146e (P < 0.001). The gastric content of MPO, TNF-alpha and IL-1beta were all increased after water-immersion stress and reduced to near normal levels by ATL-146e. CONCLUSION: A specific adenosine A(2A) agonist inhibits stress-induced gastric inflammation and damage. A(2A) agonist compounds may be useful for preventing ulcers and appear to act by blocking gastric inflammation.     

Indomethacin-induced small intestinal injury is ameliorated by cilostazol, a specific PDE-3 inhibitor

Abstract Background. Neutrophil migration, one of the major factors predisposing to nonsteroidal anti-inflammatory drugs (NSAIDs)-induced intestinal lesions, consists of several steps, including interaction with P-selectin from platelets. Cilostazol, a specific phosphodiesterase (PDE)-3 inhibitor, suppresses the expression of P-selectin from platelets and reduces interaction between platelets and leukocytes, leading to inflammatory amelioration in several disease models. We tried to clarify the therapeutic effectiveness of cilostazol for NSAID-induced small intestinal lesions. Subjects and methods. 1) Anti-PSGL-1 antibody (2 mg/kg) or cilostazol (100 mg/kg) was administered to mice one hour before Indomethacin (IND, 2.5 mg/kg) administration for 4 days to evaluate small intestinal lesions. 2) IND-induced migratory behaviors of neutrophils and platelets were evaluated in intestinal vessels by an intravital microscopy. Results. i) IND induced small intestinal lesions with an increase in MPO activity. Anti-PSGL-1 antibody and cilostazol ameliorated intestinal lesions along with suppression of MPO activity. ii) Intravital microscopy revealed that administration of IND increased migration of platelet-bearing neutrophils. Cilostazol treatment ameliorated neutrophil migration by blocking interaction between platelets and neutrophils. Conclusion. Our results suggest that enhanced platelets-bearing neutrophil migration is critically involved in the pathogenesis of IND-induced small intestinal lesions and suggest a potential application of cilostazol for prevention of NSAID-induced small intestinal lesions.     

Rolipram, a Specific Type IV Phosphodiesterase Inhibitor, Ameliorates Aspirin-Induced Gastric Mucosal Injury in Rats

Inhibition of type IV phosphodiesterase (PDE IV) activity reduces the production of various proinflammatory cytokine and suppresses neutrophil activation. Nonsteroidal anti-inflammatory drugs such as aspirin induce gastric mucosal lesions. In the pathogenesis of aspirin-induced gastric mucosal lesion, the contributions, of activated inflammatory cells and proinflammatory cytokine production are critical. The specific PDE IV inhibitor rolipram is known to be a potent inhibitor of inflammation by increasing intracellular cyclic AMP in leukocytes. The aim of the present study was to determine whether rolipram can ameliorate aspirin-induced gastric mucosal lesions in rats and whether the agent can inhibit the inrease in neutrophil accumulation and the production of proinflammatory cytokines. Gastric lesions were produced by administration of aspirin (200 mg/kg) and HCl (0.15 N; 8.0 ml/kg). Rolipram was injected 30 min before aspirin administration. The tissue myeloperoxidase concentration in gastric mucosa was measured as an indicat or of neutrophil infiltration. The gastric mucosal concentrations of tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) were determined by ELISA. The intragastric administration of aspirin induced multiple hemorrhagic erosions in rat gastric mucosa. Gastric mucosal lesions induced by aspirin were significantly inhibited by treatment with rolipram. The mucosal myeloperoxidase concentration was also suppressed by rolipram. Increases in the gastric content of TNF-α and IL-1β after aspirin administration were inhibited by pretreatment with rolipram. We demonstrated that the specific type IV PDE inhibitor, rolipram, could have a potent antiulcer effect, presumably mediated by its anti-inflammatory properties.     

Mitigation of Stress-Induced Gastric Mucosal Lesions by a Specific Type IV Phosphodiesterase Inhibitor

Inhibition of type IV phosphodiesterase (PDE4) activity is beneficial in various inflammations. However, the effect of phosphodiesterase inhibitors on the development of stress-induced gastric mucosal lesions has not been reported. In the present study, we examined the effect of a specific PDE4 inhibitor (rolipram) on stress-induced gastric mucosal lesions. Rats were exposed to water-immersion stress with or without pretreatment with rolipram. Ulcer index and myeloperoxidase activity of the gastric mucosa were evaluated. Gastric mucosal lesions and mucosal myeloperoxidase activity were suppressed by treatment with rolipram without acid suppression. The effect of intraperitoneal administration of 2.5 mg/kg rolipram on suppression of mucosal lesions was almost equal to that of treatment with 200 mg/kg cimetidine. We demonstrated that a specific PDE4 inhibitor has a potent anti-ulcer effect presumably mediated by an increment in intracellular cAMP in inflammatory cells, in which this enzyme is abundantly and specifically expressed.     

Inhibition of Neutrophil Activation by Lafutidine,an H<Subscript>2</Subscript>-receptor Antagonist,Through Enhancement of Sensory Neuron Activation Contributes to the Reduction of Stress-Induced Gastric Mucosal Injury in Rats

Sensory neuron activation reduces water-immersion restraint stress (WIR)-induced gastric mucosal injury by inhibiting neutrophil activation through increase in endothelial production of prostacyclin. This study was designed to examine whether lafutidine, which is an H₂-receptor antagonist and activates sensory neurons, inhibits neutrophil activation, thereby reducing WIR-induced gastric mucosal injury. Lafutidine enhanced WIR-induced increases in gastric tissue levels of calcitonin gene-related peptide (CGRP) and 6-keto-PGF_1α, a stable metabolite of prostacyclin, whereas famotidine, another H₂-receptor antagonist, did not. Such lafutidine-induced increases in gastric tissue levels of 6-keto-PGF_1α were reversed by pretreatment with capsazepine, an inhibitor of sensory neuron activation, CGRP(8–37), a CGRP antagonist, and indomethacin. Lafutidine inhibited acid-induced exacerbation of gastric mucosal injury in animals subjected to WIR by inhibiting neutrophil activation, whereas famotidine did not. Lafutidine synergistically increased CGRP release from isolated rat dorsal root ganglion neurons in the presence of anandamide, but famotidine did not. These observations suggest that lafutidine might reduce WIR-induced gastric mucosal injury not only by inhibiting acid secretion but also by inhibiting neutrophil activation through enhancement of sensory neuron activation.     

Indomethacin-induced small intestinal injury is ameliorated by cilostazol,a specific PDE-3 inhibitor

Abstract

Background. Neutrophil migration, one of the major factors predisposing to nonsteroidal anti-inflammatory drugs (NSAIDs)-induced intestinal lesions, consists of several steps, including interaction with P-selectin from platelets. Cilostazol, a specific phosphodiesterase (PDE)-3 inhibitor, suppresses the expression of P-selectin from platelets and reduces interaction between platelets and leukocytes, leading to inflammatory amelioration in several disease models. We tried to clarify the therapeutic effectiveness of cilostazol for NSAID-induced small intestinal lesions. Subjects and methods. 1) Anti-PSGL-1 antibody (2 mg/kg) or cilostazol (100 mg/kg) was administered to mice one hour before Indomethacin (IND, 2.5 mg/kg) administration for 4 days to evaluate small intestinal lesions. 2) IND-induced migratory behaviors of neutrophils and platelets were evaluated in intestinal vessels by an intravital microscopy. Results. i) IND induced small intestinal lesions with an increase in MPO activity. Anti-PSGL-1 antibody and cilostazol ameliorated intestinal lesions along with suppression of MPO activity. ii) Intravital microscopy revealed that administration of IND increased migration of platelet-bearing neutrophils. Cilostazol treatment ameliorated neutrophil migration by blocking interaction between platelets and neutrophils. Conclusion. Our results suggest that enhanced platelets-bearing neutrophil migration is critically involved in the pathogenesis of IND-induced small intestinal lesions and suggest a potential application of cilostazol for prevention of NSAID-induced small intestinal lesions.     

Specific type IV phosphodiesterase inhibitor ameliorates thioacetamide-induced liver injury in rats

Background and Aims:  Rolipram is a specific type IV phosphodiesterase inhibitor that suppresses the activity of immune cells and the production of pro-inflammatory cytokines. In this study, we assessed the effect of rolipram on acute liver injury using thioacetamide (TAA)-induced liver injury in rats as a model.
Methods:  Rats were treated with rolipram (0.5–5 mg/kg, intraperitoneally) or vehicle and injected 30 min later with TAA (100 mg/kg, subcutaneously). Serum transaminase concentrations and tumor necrosis factor-α (TNF-α), interleukin 1β (IL-1β) and growth related oncogene/cytokine-induced neutrophil chemoattractant-1 (GRO/CINC-1) levels were measured and livers were examined for microscopic changes. Dose-dependent protection against TAA liver injury was based on transaminase levels and inflammatory cytokine production, and was measured 9 h after TAA when the peak release of cytokines occurred.
Result:  Rolipram suppressed liver injury based on serum aspartate transaminase (AST), alanine transaminase (ALT) and histology and reduced TNF-α, IL-1β and GRO/CINC-1 levels. Rolipram, at doses of 0.5–5 mg/kg, suppressed serum transaminase and TNF-α production in a dose-dependent manner, and these effects were significant at doses of 2.5 and 5 mg/kg.
Conclusion:  In our rodent model of acute liver injury, rolipram clearly reduced liver damage and inhibited pro-inflammatory cytokine production. These results suggest that specific type IV phosphodiesterase inhibitors, such as rolipram, have potent hepatoprotective effects that are associated with suppressing inflammatory cytokine production.     

Influence of Helicobacter pylori infection on development of stress-induced gastric mucosal injury

Immediately after the Great Hanshin Earthquake in Kobe in 1995, the recurrence rate of peptic ulcer in patients infected with Helicobacter pylori was higher than that in patients in whom H. pylori had been eradicated. We evaluated the influence of H. pylori infection on stress-induced gastric mucosal injury in Mongolian gerbils and C57BL/6 mice. These animals were immersed in water for 30, 120, and 720 min 12 weeks after inoculation with H. pylori, and then killed to assess gastric mucosal damage, and to measure cytokine production (interleukin [IL]-1β, IL-4, IL-6, and IL-10; interferon [IFN]-γ; and tumor necrosis factor [TNF]-α) in the gastric tissue of the mice. The stress treatment for 30 min resulted in a significantly higher bleeding rate and bleeding index among infected gerbils and mice compared with results in uninfected animals. Conversely, the bleeding and ulcer indexes were significantly higher in uninfected gerbils after 720 min of the stress treatment than in infected gerbils. Prior to the stress treatment, gastric IL-1β and IFN-γ production was significantly higher in the infected group than in the uninfected group. After 120 min of the stress treatment, TNF-α production was increased in the infected group, and IL-1β and IL-10 production was increased in the uninfected group. However, the production of these cytokines showed no change at 30 min of the stress treatment. These results suggest that H. pylori infection influences the development of gastric mucosal injury in the early phase of stress exposure; cytokines do not play a major role in this process. Received: March 29, 1999 / Accepted: November 26, 1999     

NF-κB Activation Precedes Increases in mRNA Encoding Neurokinin-1 Receptor,Proinflammatory Cytokines,and Adhesion Molecules in Dextran Sulfate Sodium–Induced Colitis in Rats

Nuclear factor kappa B (NF-κ B) plays a key role in initiating inflammation associated with colitis. A systematic study was conducted in the rat DSS colitis model to determine the temporal relationship between NF-κ B activation and expression of substance P (SP), neurokinin-1 receptor (NK-1R), proinflammatory cytokines, and adhesion molecules. Rats were given 5% DSS in their water and sacrificed daily for 6 days. Colon tissue was collected for assessment of histological changes, NF-κ B activation, myeloperoxidase (MPO) activity, and expression of NK-1R, SP, TNFα, IL-1β, VCAM-1, ICAM-1, E-selectin, CINC-1, MIP-1α, and iNOS. NF-κ B activation increased, biphasically, on Day 1 and again on Days 4–6. The mRNA levels for ICAM-1, CINC-1, IL-1β, TNFα, VCAM-1, and NK-1R rose significantly (P< 0.05) by 2–4 days. Increased iNOS mRNA levels, MPO activity, and mucosal damage occurred on Day 6. These data demonstrate that NF-κ B activation substantially precedes the onset of physical disease signs and active inflammation.     

Activated Neutrophils Impair Gastric Cytoprotection: Role of Neutrophil Elastase

Neutrophil elastase decreases production of PGI₂ by cultured endothelial cells. Thus, neutrophil elastase may play an important role in gastric mucosal injury by decreasing the tissue level of PGI₂, an important gastric cytoprotective substance. We examined whether activated neutrophils inhibit gastric PGI₂ production in rats subjected to water-immersion restraint stress. Gastric 6-keto-PGF₁ levels were determined by enzyme immunoassay. Gastric mucosal blood flow was determined by laser–Doppler flowmeter. Gastric microvascular permeability was determined by Evans blue leakage. Gastric levels of 6-keto-PGF₁ were transiently increased 0.5 hr after the stress, followed by a decrease to below baseline at 6 hr, when mucosal blood flow fell to 60% of baseline. Gastric levels of 6-keto-PGF₁ were significantly higher in animals with nitrogen mustard-induced leukocytopenia than in controls 1 and 6 hr after the stress. In leukocytopenic animals, levels 6 hr after stress were not lower than those preceding stress. Leukocytopenia markedly limited both the decrease in mucosal blood flow and the increase in gastric microvascular permeability. The level of gastric mucosal injury observed 6 hr after the stress was markedly attenuated by leukocytopenia. Pretreatment with neutrophil elastase inhibitors (ONO-5046 and Eglin C) or an anti-P-selectin monoclonal antibody produced effects similar to leukocytopenia. Neutrophil elastase is involved in the stress-induced gastric mucosal injury by decreasing gastric production of PGI₂. Thus, pharmacologic inhibition of neutrophil elastase should help to prevent stress-induced gastric mucosal injury.     

The inhibition in tumor necrosis factor-α-induced attenuation in endothelial thrombomodulin expression by carvedilol is mediated by nuclear factor-κB and reactive oxygen species

Carvedilol, a nonselective β-adrenoceptor antagonist, has been shown to possess antioxidant effects and reduce the risk of hospitalization and death in patients with severe congestive heart failure, which is featured by the activation of pro-inflammatory cytokines, including tumor necrosis factor-α (TNF-α), and leads to thrombotic complications. Thrombomodulin (TM) plays protective roles against thrombosis. Treatment of ECs with TNF-α resulted in a down-regulation in the TM expression in a time-dependent manner. Pre-treatment of ECs with carvedilol (1 and 10 μM) for 1 h significantly up-regulated the TM expression in ECs in response to TNF-α. When ECs were pre-treated with a nuclear factor-κB (NF-κB) inhibitor, i.e., parthenolide, their TNF-α-mediated down-regulation of TM expression was inhibited. Pre-treatment of ECs with carvedilol inhibited the NF-κB-DNA binding activity in ECs induced by TNF-α. Our findings provide insights into the mechanisms by which carvedilol exerts anti-thrombotic effects by inducing TM expression in ECs in response to pro-inflammatory stimulation.     

Insulin-like growth factor-I reduces stress-induced gastric mucosal injury by inhibiting neutrophil activation in mice

ObjectiveWe previously reported that activated neutrophils are critically involved in the development of stress-induced gastric mucosal injury in mice. Caspase activation plays an important role in the pathogenesis of tissue injury by activating neutrophils through an increase in the expression of endothelial monocyte-activating polypeptide-II (EMAP-II), a chemoattractant for neutrophils. Since insulin-like growth factor-I (IGF-I) inhibits caspase activation, it is possible that IGF-I reduces gastric mucosal injury by inhibiting neutrophil activation. In the present study, we examined this possibility in mice subjected to water-immersion restraint stress (WIR).DesignMice were intraperitoneally administered with IGF-I or vehicle before being subjected to WIR. Gastric mucosal injury, gastric myeloperoxidase (MPO) activity, the immunofluorescence intensity of MPO, caspase-3 activity, number of apoptotic cells, EMAP-II expression and activation of Akt and glycogen synthase kinase-3β (GSK-3β) in gastric mucosa were determined in mice subjected to WIR. Neutropenia was induced by administration of methotrexate (MTX).ResultsAdministration of IGF-I at dosages higher than 200 μg/kg significantly reduced gastric mucosal injury and inhibited increases in gastric MPO activities after 8 h of WIR. Administration of MTX also reduced the gastric mucosal injury as well as inhibiting increases in both gastric mucosal MPO activities and circulating neutrophil number. IGF-I (500 μg/kg) inhibited the increases in both gastric MPO activity and the immunofluorescence intensity of MPO observed in the gastric mucosa, but had no effect on the increase in circulating neutrophil number after 8 h of WIR. It also markedly blunted WIR-induced increases in caspase-3 activities and the number of apoptotic cells in the gastric mucosa after 8 h of WIR. Gastric expression of EMAP-II was markedly increased at 8 h after starting WIR and this increase was inhibited by IGF-I administration. Administration of IGF-I enhanced WIR-induced phosphorylation of Akt and GSK-3β in the gastric mucosa.ConclusionThese observations indicate that IGF-I reduces stress-induced gastric mucosal injury by inhibiting gastric accumulation of neutrophils through inhibition of caspase-3-mediated EMAP-II activation. Furthermore, IGF-I might inhibit caspase-3 activation through Akt/GSK-3β signaling.     

Hyperbaric Oxygenation Ameliorates Indomethacin-Induced Enteropathy in Rats by Modulating TNF-α and IL-1β Production

The effect of hyperbaric oxygenation (HBO₂) was investigated in a rat model of indomethacin-induced enteropathy. Enteropathy was induced by two subcutaneous injections of indomethacin (7.5 mg/kg) 24 hr apart. Six groups of rats (n=8) were treated with and without HBO₂ (100% oxygen at 2.3 atm absolute) for 1 hr once or twice a day for 2 or 5 days. Disease activity index (DAI) and total ulcer length were measured. Other rats were randomized into two groups (n=16) with and without HBO₂ (1 hr once a day) and four rats were killed in each group at 12, 24, 48, and 72 hr after the final injection of indomethacin. Serum and intestinal mucosal TNF-α, IL-1β, myeloperoxidase (MPO), and iNOS expression was measured. HBO₂ treatment significantly attenuated indomethacin -induced intestinal ulceration and improved DAI. Indomethacin increased MPO activity and iNOS expression, and these were reduced by HBO₂ treatment, with a concomitant reduction in TNF-α and IL-1β. Our data suggest that HBO₂ treatment has a beneficial effect on indomethacin-induced enteropathy and this effect is possibly mediated by decreased production of TNF-α and IL-1β.     

Proinflammatory cytokines,IL-1β and TNF-α, induce expression of interleukin-34 mRNA via JNK- and p44/42 MAPK-NF-κB pathway but not p38 pathway in osteoblasts

The aim of this study is to investigate the induction of interleukin-34 (IL-34) and macrophage colony-stimulating factor (M-CSF) mRNA by inflammatory cytokines and the involvement of mitogen-activated protein kinases (MAPKs) in this signaling pathway in human osteoblasts as both IL-34 and M-CSF bind to the same receptor c-FMS. Among four inflammatory cytokines [(IL-1β, IL-6, IL-17, and tumor necrosis factor-α (TNF-α)], IL-34 mRNA expression level was dramatically induced by IL-1β (17-fold) and TNF-α (74-fold). IL-1β and TNF-α activated the intracellular mitogen-activated protein kinases (MAPKs): p44/42 MAPK, p38, and c-Jun N-terminal kinase (JNK) as well as nuclear factor-κB (NF-κB) in osteoblasts. IL-1β- and TNF-α-mediated induction of IL-34 mRNA expression was decreased by JNK inhibitor. Interestingly, although treatment of MEK-1/2 inhibitor showed no reduction in the increase of IL-34 mRNA expression by cytokines, combination of MEK-1/2 inhibitor and JNK inhibitor significantly inhibited IL-1β- and TNF-α-mediated IL-34 mRNA expression level compared to those by each inhibitor alone. On the other hand, M-CSF mRNA expression level was significantly induced by both IL-1β and TNF-α by up to 7- and 11-fold, respectively. IL-1β- and TNF-α-mediated induction of M-CSF mRNA was not affected by p38, JNK, and MEK-1/2 inhibitors. However, NF-κB inhibitor completely inhibited the elevation of M-CSF mRNA expression by these cytokines. These results showed that proinflammatory cytokines, IL-1β and TNF-α, induced the expression of IL-34 mRNA via JNK and p44/42 MAPK but not p38 in human osteoblasts while p38, JNK, and p44/42 MAPK were not involved in the induction of M-CSF mRNA expression by these cytokines.     

Increased expression of cytokines in liver and serum in patients with extrahepatic diseases

To determine whether the liver plays an immunological role in certain extrahepatic disorders, we investigated the expression of interleukin (IL)-1β, IL-6, interferon (IFN)-γ, and tumor necrosis factor (TNF)-α in 11 patients who had recovered from cholecystolithiasis, 12 patients with gastric cancer, 20 patients with chronic hepatitis, and 6 healthy controls. Cytokine mRNAs in the liver were detected by semiquantitative reverse transcribed-polynerase chain reaction. Serum cytokines and soluble IL-2 receptor (sIL-2R) were investigated by enzyme-linked immunosorbent assays. Increases in TNF-α, IL-6, IL-1β, and IFN-γ mRNAs were found in the livers of patients with extrahepatic diseases. TNF-α and IL-6 peptides were increased in the sera of patients with gastric cancer. TNF-α in the sera and TNF-α mRNA in the liver were correlated in gastric cancer patients. Surprisingly, sIL-2R in the serum of gastric cancer patients was significantly higher than the level in healthy controls. Our findings suggest that the liver produces cytokines in reaction to extrahepatic lesions. Further, the increase in sIL-2R in gastric cancer patients indicates that malignancy may affect the immune network in vivo.     

Differential effect of IL-1β and TNF-α on the production of IL-6, IL-8 and PGE2 in fibroblast-like synoviocytes and THP-1 macrophages

Inflammation in the joint of rheumatoid arthritis is a complex immune reaction facilitated by various factors, such as cytokines, cells and hypoxia. Thus, we evaluated their relative capacity to produce proinflammatory mediators in response to IL-1β, TNF-α or IL-17 under hypoxia or normoxia in fibroblast-like synoviocytes (FLSs) and macrophages. The level of IL-6 expression was strongly increased in both FLSs and THP-1 macrophages in response to IL-1β and TNF-α, but the level by TNF-α was less than that by IL-1β. In contrast, the expression of IL-8 in both cell types was strongly stimulated by both IL-1β and TNF-α. In FLSs, PGE₂ production increased only in response to IL-1β; and no effect was observed in THP-1 cells and TNF-α-stimulated FLSs. In addition, the production by IL-17 was extremely low when compared with those induced by IL-1β or TNF-α in FLSs and THP-1 cells. Hypoxia (2% O₂) decreased IL-1β-stimulated production of PGE₂, even though it increased the expression of mRNA and protein of COX-2. These results suggest that IL-1β and TNF-α differentially regulate gene expression in FLSs and macrophages under hypoxia or normoxia.     

Cilostazol, a selective type III phosphodiesterase inhibitor, decreases triglyceride and increases HDL cholesterol levels by increasing lipoprotein lipase activity in rats

Cilostazol, a selective type III phosphodiesterase inhibitor, has antiplatelet and vasodilating effects. In this study, the effects of cilostazol on lipid metabolism and lipoprotein lipase (LPL) activity were studied in rats. Cilostazol was administered orally at doses of 30 or 100 mg/kg twice a day for 1-2 weeks to rats. Cilostazol decreased the serum triglyceride level in normolipidemic rats. The serum triglyceride level was reduced and HDL cholesterol level was increased by cilostazol in streptozotocin (STZ)-induced diabetic rats. The disappearance of exogenous triglyceride was accelerated by cilostazol in normolipidemic rats. Cilostazol increased post-heparin plasma LPL activity but had no effect on hepatic triglyceride lipase activity in STZ-induced diabetic rats. Cilostazol also increased LPL activity in the heart in STZ-induced diabetic rats. These findings suggest that an increase in LPL activity is responsible for the serum triglyceride lowering and HDL cholesterol elevating effects of cilostazol in rats.     

Attenuation of gastric mucosal inflammation induced by aspirin through activation of A2A adenosine receptor in rats

AIM:To determine whether a specific adenosine A_(2A) re-ceptor agonist(ATL-146e)can ameliorate aspirin-inducedgastric mucosal lesions in rats,and reduce neutrophil ac-cumulation and production of pro-inflammatory cytokines.METHODS:Gastric lesions were produced by oralgarage of aspirin(200 mg/kg)and HCl(0.15 mol/L,8.0 mL/kg).4-{3-[6-Amino-9-(5-ethylcarbamoyl-3,4-dihydroxy-tetrahydro-furan-2-yl)-9H-purin-2-yl]-prop-2-ynyl}-cyclohexanecarboxylic acid methyl ester(ATL-146e,2.5-5 μg/kg,IP)was injected 30 min before the admin-istration of aspirin.Tissue myeloperoxidase(MPO)con-centration in gastric mucosa was measured as an indexof neutrophil infiltration.Gastric mucosal concentrationsof tumor necrosis factor-α(TNF-α)and interleukin-1β(IL-1β)were determined by ELISA.Also,we examinedthe effect of ATL-146e on tissue prostaglandin E2(PGE2)production and gastric secretion.RESULTS:Intragastric administration of aspirin inducedmultiple hemorrhagic erosions in rat gastric mucosa.Thetotal length of gastric erosions(ulcer index)in controlrats was 29.8±7.75 mm and was reduced to 3.8±1.42mm after pretreatment with 5.0 g/kg ATL-146e(P<0.01).The gastric contents of MPO and pro-inflammatory cy-tokines were all increased after the administration ofaspirin and reduced to nearly normal levels by ATL-146e.Gastric mucosal PGE2 concentration was not affected byintraperitoneal injection of ATL-146e.CONCLUSION:The specific adenosine A_(2A) receptor ago-nist,ATL-146e,has potent anti-ulcer effects presumablymediated by its anti-inflammatory properties.     

Molecular and histological evaluation of tumor necrosis factor-alpha expression in <Emphasis Type="Italic">Helicobacter pylori</Emphasis>-mediated gastric carcinogenesis

Purpose  

Helicobacter pylori (H. pylori) is considered to be a major factor contributing to gastric mucosal damage by stimulating mucosal macrophage production of inflammatory cytokines, including tumor necrosis factor-alpha (TNF-α), but the inflammatory responses within the gastric mucosa in vivo are not well known. Therefore, this study was designed to investigate the expression of TNF-α induced by H. pylori infection which is involved in the tumor initiation and promotion of gastric carcinogenesis.