A gastrointestinalis nyálkahártya mikrokeringési változásai oxido-redukciós stressz állapotokban = Gastrointestinal microcirculatory changes during oxido-reductive stress conditions

Kimutattuk, hogy elektrofil metil gyököket tartalmazó biomolekulákból (pl. foszfatidilkolin -PC) metán képződhet reduktív körülmények között és bizonyítottuk, hogy a reakció in vivo körülmények között is lejátszódhat: igazoltuk a metángáz megjelenését élő mitokondriumokat tartalmazó reakcióközegben hipoxia alatt. Megvizsgáltuk a gasztrointesztinális nyálkahártya reakcióját és a PC kezelés hatásait reduktív/oxidatív stressz állapotokban, meghatároztuk a helyi vagy általános oxigénhiányt kísérő intramurális mikrokeringési reakciókat számos állatkísérletes modellben (vérzés, szepszis, a nitrogén monoxid szintézis gátlása, az artériás keringés elzáródása) in vivo körülmények között. Új módszert dolgoztunk ki a mikrokeringési zavarok objektív leírására, mellyel sikerült a térben és időben egyaránt változó perfúziós mintázatok összehasonlítása; s így az egyes kezelések hatékonyságát objektívan megítélhettük. Jellemeztük a nyelőcső, a gyomor és a vékonybél nyálkahártya intramurális mikrokeringését élettani és kóros körülmények között is, és kimutattuk, hogy a PC kezelés rendkívül hatékonyan csökkenti a mucosa mikrokeringési zavarát, a helyi gyulladásos reakciót és jelentősen mérsékli a szövetek strukturális károsodását is. Eredményeink bizonyítják a PC molekula jelentős gyulladáscsökkentő hatását; s ennek a felismerésnek klinikai-terápiás konzekvenciái lehetnek az oxido-reduktív stressz és a következményes gyulladásos reakciók befolyásolása terén. | Our first goal was to explore the mechanistic details of an intracellular system which may operate by capture of electrons and the consequent irreversible evolution of methane gas. Possible intracellular candidates for this reaction were phosphatidylcholine (PC) and some other compounds with electrophylic methyl moieties. Supporting this finding, the formation of methane in isolated rat liver mitochondria has been observed. Our second goal was to develop strategies to preserve the structural and functional integrity of the gastrointestinal tract in clinical conditions with oxido-reductive stress. The microcirculation was monitored by means of intravital videomicroscopy in several in vivo animal models. We applied a novel mathematical approach to quantify the time-wise and spatial heterogeneity of tissue microcirculation during systemic (hemorrhagic shock, endotoxemia, and nitric oxide synthesis inhibition) and local (ischemia-reperfusion) circulatory disorders. We observed and characterized distinct intramural microcirculatory changes in the oesophagus, stomach and small intestine in normal and stress conditions. The results show that PC treatment regimens effectively modulate the outcome of an oxido-reductive stress-induced inflammatory reaction

Dietary phosphatidylcholine supplementation attenuates inflammatory mucosal damage in a rat model of experimental colitis

This study was designed to follow the time course of inflammatory activation in a rodent model of 2,4,6-trinitrobenzenesulfonic acid (TNBS)-induced colitis. We hypothesized that oral phosphatidylcholine (PC) pretreatment regimens may influence leukocyte-mediated microcirculatory reactions in this condition. In series I, Wistar rats were monitored 1 day after colitis induction (n = 24), and in series II (n = 24) on day 6 following a TNBS enema. The PC-pretreated animals received a 2% PC-enriched diet for 6 days before the TNBS enema (series I), or for 3 days before and 3 days after TNBS treatment (series II). The macrohemodynamics, serosal microcirculation (visualized by intravital videomicroscopy), colonic xanthine oxidoreductase, myeloperoxidase and nitric oxide end products, and changes in proinflammatory cytokine levels in plasma were measured. The mucosal structural injury was monitored in vivo by means of confocal laser scanning endomicroscopy. The TNBS enema induced a systemic hyperdynamic circulatory reaction with increased serosal capillary blood flow and significantly elevated colonic inflammatory enzyme activities, levels of nitric oxide production, and cytokine concentrations. Acute colitis caused disruption of the capillary network, whereas the morphologic damage was less severe in series II. The PC pretreatment protocols led to significant decreases in the serosal hyperemic reaction, the cytokine levels, and the inflammatory enzyme activities. The objective signs of tissue damage were reduced in both series, and the number of mucus-producing goblet cells in the resolving phase of colitis was increased. Dietary PC efficiently decreases the cytokine-mediated progression of inflammatory events and preserves the microvascular structure in the large intestine. © 2012 by the Shock Society

Inhibition of anaphylactic shock by gadolinium chloride-induced Kupffer cell blockade.

Data in the literature concerning the role of macrophages in anaphylaxis are contradictory. In the present study, the effect of macrophage blockade induced by gadolinium chloride (GdCl3) on anaphylactic shock is investigated. Our observations show that GdCl3 prevents lethal anaphylactic shock in mice sensitized to ovalbumin. Gadolinium chloride given i.v. in a dose of 1 mg/100 g body weight 24 or 48 h before the elicitation of anaphylactic shock resulted in 80% survival, compared with the 43% survival in the control group. The same dose of this rare-earth metal salt also greatly reduced the mortality in mice sensitized with ovalbumin containing Bordetella pertussis vaccine, and similarly abrogated the symptoms of anaphylaxis, including the accumulation of serotonin and histamine in the liver. The results suggest that macrophages play an important role in mouse anaphylaxis

Foszfolipidek szerepe a gyulladásban és a szeptikus szövődmények kialakulásában = Modulatory role of phospholipid metabolites in the inflammatory response and septic complications

A membránalkotó foszfatidilkolin (PC) és származékai gyulladáscsökkentő hatását bizonyítottuk számos szerv, köztük a pleura, a térdízület és a gasztrointesztinális nyálkahártya mikrokeringés funkcionális és strukturális károsodásával járó gyulladásos kórfolyamataiban. Elsőként közöltünk adatokat a központi idegrendszerben neuroprotektív hatású NMDA receptor antagonisták terápiás hatékonyságáról az enterális idegrendszerben akut és krónikus colitis modellekben. A mikrokeringési gyulladásos reakció jellemzésére standardizálható intravitális mikroszkópos eljárásokat dolgoztunk ki; karakterizáltuk a nyálkahártya károsodás jellegzetes paramétereit in vivo körülmények között, valamint a fokozott PC bevitel hatását: a mucin termelő kehelysejtek számának fokozódását. A PC előkezelés mérsékelte az endotoxin által kiváltott perifériás gyulladás miatt bekövetkező neurogenezis csökkenést a központi idegrendszerben is. Igazoltuk, hogy az ischaemia-reperfúziót kísérő antigén-független gyulladásos reakció alatt fokozódik az endogén metánképződés, és hogy PC-t tartalmazó speciális táppal befolyásolható. Meghatároztuk a PC deacilált származék GPC hatását a kémiai hipoxia által kiváltott szisztémás gyulladásos reakció fontosabb elemeire. A krónikus Na-azid kezelés is szignifikáns metán felszabadulást okoz, a metanogén bélflórától függetlenül. Mivel normoxiás metán inhaláció mérsékli a nyálkahártya strukturális károsodását, a képződő metán hozzájárulhat a mucosa homeosztázis normalizálásához. | We have characterized the anti-inflammatory action of a phosphatidylcholine (PC) and its metabolites in animal models of pleurisy, arthritis and gastrointestinal inflammatory damage. The microcirculatory consequences were evaluated by novel methods developed for direct intravital microscopic observations, and we have shown that the therapeutic potential of PC could be linked to the reduction of neutrophil leukocyte-mediated reactions. Dietary PC efficiently preserved the microvascular structure and the number of mucus-producing goblet cells in the large intestine. We have shown protective effects for the PC-enriched diet in endotoxin-induced experimental neuroinflammation in the central nervous system as well. We demonstrated that blockade of peripheral NMDA-sensitive glutamate receptors also provides therapeutic option to influence intestinal hypermotility, microcirculatory changes and inflammatory activation simultaneously. Further, we have provided evidence that exogenous PC modulated ischaemia-reperfusion-induced methane generation. Sodium azide-induced chemical hypoxia also increased endogenous methane production independently of the methanogenic flora. The inflammatory activities were reduced by treatment with GPC, a deacylated PC derivative. Since exogenous, normoxic methane inhalation was found to be protective against structural damage and inflammatory consequences, the results suggest that endogenous methane may normalize mucosal homeostasis after hypoxic events

Complement C5a inhibition improves late hemodynamic and inflammatory changes in a rat model of nonocclusive mesenteric ischemia

BACKGROUND: Nonocclusive mesenteric ischemia (NOMI) can evolve in a variety of low-flow states. Although the mechanisms leading to NOMI-related intestinal necrosis are largely unknown, circumstantial evidence suggests that excessive vasoconstriction and complement activation both play important roles in this process. Because targeting of the circulatory malfunction of the splanchnic area could be of therapeutic relevance, we set out to investigate the long-term effects of treatment with a complement C5a antagonist in a rat model of partial aortic occlusion (PAO)-induced transient mesenteric hypoperfusion. METHODS: The mean arterial pressure of the splanchnic area was kept between 30 and 40 mm Hg by 60 minutes of PAO in anesthetized male Sprague-Dawley rats. C5a inhibitor acetyl-peptide-A (AcPepA; 4 mg kg-1 intravenously) or vehicle administration was initiated at the 45th minute of PAO. After 24 hours, the animals were reanesthetized to record the macrohemodynamics and ileal microcirculation, and plasma and tissue samples were taken for determination of high-mobility group box protein-1 (HMGB-1), endothelin-1, tumor necrosis factor (TNF)-alpha levels, and small intestinal leukocyte infiltration. Epithelial structural changes were visualized by in vivo confocal laser scanning endomicroscopy. RESULTS: At 24 hours after PAO, mean arterial pressure, heart rate, and cardiac output were significantly greater, the intestinal intramural microcirculation was significantly impaired, and plasma HMGB-1, endothelin-1, TNF-alpha levels, the degree of epithelial damage and leukocyte infiltration was increased. The AcPepA treatment moderated the hemodynamic and microcirculatory changes, and decreased inflammatory activation and histologic signs of mucosal damage. CONCLUSION: C5a inhibition ameliorated the potentially harmful local mesenteric hypoperfusion and global long-term inflammatory consequences of PAO. This approach is of promise for use in NOMI-associated situations

Terápiás lehetőségek a gyulladásos bélbetegség állatkísérletes modelljében – összehasonlító vizsgálat [Comparative study of novel therapeutic possibilities in animal experimental model of inflammatory bowel disease]

Introduction: The consequence of inflammatory bowel diseases (IBD) is cytokine-mediated severe local tissue damage. Our aim was to determine the extent of inflammatory response and to influence the morphologic changes during the subacute phase of trinitro-benzene sulfonic acid (TNBS)-induced experimental colitis by oral phosphatidylcholine (PC) and N-methyl-D-aspartate (NMDA) receptor antagonist kynurenic acid therapy. Methods: Sprague-Dawley rats were randomized to control, untreated colitis (ic TNBS), colitis fed with 2% PC-containing diet (3 days pre-treatment +3 days treatment after TNBS induction), colitis with kynurenic acid treatment (on day 6, n = 7) groups. The colitis was characterized by tissue myeloperoxidase and plasma TNF-alpha levels, the extent of tissue damage, structural changes in microvasculature (FITC-dextran staining) and mucosal injury (acridine orange staining) were determined by in vivo confocal laser scanning endomicroscopy (Optiscan Five1, Australia) and conventional histology (hematoxyilin-eosin staining). Results: Significant elevation in myeloperoxidase and TNF-alpha levels with remarkable damage in epithelial structure was detected in the colitis group. Both treatment regimens significantly decreased the level of inflammatory activation but only PC pretreatment could preserve the number of goblet cells and the epithelial structure. Treatment with kynurenic acid did not alter the morphology changes. Conclusion: Oral PC pretreatment is a promising possibility in the therapy of IBDs through decreasing inflammatory reaction and increasing the number of goblet cells

Effect of melatonin on the severity of l-arginine-induced experimental acute pancreatitis in rats

AIM: To determine the effect of melatonin pre- and post-treatment on the severity of L-arginine (L-Arg) -induced experimental pancreatitis in rats. METHODS: Male Wistar rats (25) were divided into five groups. Those in group A received two injections of 3.2g/kg body weight L-Arg i.p. at an interval of 1h. In group MA, the rats were treated with 50 mg/kg body weight melatonin i.p. 30 min prior to L-Arg administration. In group AM, the rats received the same dose of melatonin 1h after L-Arg was given. In group M, a single dose of melatonin was administered as described previously. In group C the control animals received physiological saline injections i.p. All rats were exsanguinated 24 h after the second L-Arg injection. RESULTS: L-Arg administration caused severe necrotizing pancreatitis confirmed by the significant elevations in the serum amylase level, the pancreatic weight/body weight ratio (pw/bw), the pancreatic IL-6 content and the myeloperoxidase activity, relative to the control values. Elevation of the serum amylase level was significantly reduced in rats given melatonin following L-Arg compared to rats injected with L-Arg only. The activities of the pancreatic antioxidant enzymes (Cu/Zn-superoxide dismutase (Cu/Zn-SOD) and catalase (CAT)) were significantly increased 24 h after pancreatitis induction. Melatonin given in advance of L-Arg significantly reduced the pancreatic CAT activity relative to that in the rats treated with L-Arg alone. In the liver, L-Arg significantly increased the lipid peroxidation level, and the glutathione peroxidase and Cu/Zn-SOD activities, whereas the Mn-SOD activity was reduced as compared to the control rats. Melatonin pre-treatment prevented these changes. CONCLUSION: Melatonin is an antioxidant that is able to counteract some of the L-Arg-induced changes during acute pancreatitis, and may therefore be helpful in the supportive therapy of patients with acute necrotizing pancreatitis