169 research outputs found
A gátló működés útjainak- és mechanizmusainak vizsgálata a pankreász vezeték sejtekben = Inhibitory pathways and mechanisms of the pancreatic ductal epithelium.
A 4 Ă©ves pályázatunkban cĂ©lĂşl tűztĂĽk ki, hogy azonosĂtsuk az intracelluláris szignalizáciĂłs mechanizmusokat, gátlĂł utakat, melyek szerepet játszanak az SP szekrĂ©ciĂłt gátlĂł hatásának kifejtĂ©sĂ©ben. Vizsgálataink alapján megállapĂthatjuk, hogy a PDBu gátolta a basal HCO3- szekrĂ©ciĂłt, ezáltal mimikálja az SP hatását. MásrĂ©szrĹ‘l a PDBu blokkolta a secretin által stimulált szekrĂ©ciĂłt is. KontrollkĂ©nt megvizsgáltuk a PDBu inaktĂv formáját a PDD-t. Tekintettel arra, hogy az inaktĂv forma hatástalan volt megállapĂthatjuk, hogy a PKC aktiváciĂł utánozza az SP hatását, Ăgy valĂłszĂnűsĂthetĹ‘ a PKC szerepe az SP gátlĂł hatásának kifejtĂ©sĂ©ben. MásrĂ©szrĹ‘l, nagy dĂłzisĂş PKC inhibitor (BIS) alkalmazásával csökkent az SP gátlĂł hatása. Korábbi felvetĂ©seinket folytatva immunhisztokĂ©miai vizsgálattal igazoltuk, hogy a pancreas ductalis sejtjei körĂĽl találhatĂł idegvĂ©gzĹ‘dĂ©sekben találhatĂł SP. A luminális perfĂşziĂł során azt is igazoltuk, hogy a SP direktben gátolja a luminalis oldalon elhelyezkedĹ‘ Cl-HCO3- exchanger működĂ©sĂ©t. Az Ă©lettani jellegű kĂsĂ©rleteink mellett szintĂ©n vizsgáljuk a HCO3- szekrĂ©ciĂłt kĂłros körĂĽlmĂ©nyek (pancreatitisben) között. Ezek elĹ‘kĂsĂ©rleteit már elvĂ©geztĂĽk, megállapĂtottuk, hogy pancreatitisben kb. 4-5x-es hypersecretio van, mely valĂłszĂnűleg ductalis eredetű (alacsony proteintartalmĂş a szekrĂ©tum). A pályázat során több rangos nemzetközi folyĂłiratban is publikáltuk eredmĂ©nyeinket, összessĂ©gĂ©ben minden szempontbĂłl teljesĂtettĂĽk a pályázatban foglalt cĂ©lkitűzĂ©seket. | In this 4-year project our aim was to characterize the inhibitory pathways of pancreatic ductal bicarbonate secretion. Here we show that SP is present in periductal nerves within the guinea-pig pancreas; that protein kinase C (PKC) mediates the effect of SP, and that SP inhibits an anion exchanger on the luminal membrane of the duct cell. Secretin (10 nM) stimulated HCO3- secretion by sealed, non-perfused, ducts about 3 fold and this effect was totally inhibited by SP (20 nM). Phorbol 12, 13-dibutyrate (100 nM), an activator of PKC, reduced basal HCO3- secretion by about 40%, and totally blocked secretin-stimulated secretion. In addition, bisindolylmaleimide I (1 nM to 1 ?M), an inhibitor of PKC, relieved the inhibitory effect of SP on secretin-stimulated HCO3- secretion and also reversed the inhibitory effect of PDBu. In microperfused ducts, luminal H2DIDS (0.5 mM) caused intracellular pH to alkalinise and, like SP, inhibited basal and secretin-stimulated HCO3- secretion. SP did not inhibit secretion further when H2DIDS was present in the lumen, suggesting that SP and H2DIDS both inhibit the activity of an anion exchanger on the luminal membrane of the duct cell
Pancreatic Ductal Bicarbonate Secretion: Challenge of the Acinar Acid Load
Acinar and ductal cells of the exocrine pancreas form a close functional unit. Although most studies contain data either on acinar or ductal cells, an increasing number of evidence highlights the importance of the pancreatic acinar-ductal functional unit. One of the best examples for this functional unit is the regulation of luminal pH by both cell types. Protons co-released during exocytosis from acini cause significant acidosis, whereas, bicarbonate secreted by ductal cells cause alkalization in the lumen. This suggests that the first and probably one of the most important role of bicarbonate secretion by pancreatic ductal cells is not only to neutralize the acid chyme entering into the duodenum from the stomach, but to neutralize acidic content secreted by acinar cells. To accomplish this role, it is more than likely that ductal cells have physiological sensing mechanisms which would allow them to regulate luminal pH. To date, four different classes of acid-sensing ion channels have been identified in the gastrointestinal tract (transient receptor potential ion channels, two-pore domain potassium channel, ionotropic purinoceptor and acid-sensing ion channel), however, none of these have been studied in pancreatic ductal cells. In this mini-review, we summarize our current knowledge of these channels and urge scientists to characterize ductal acid-sensing mechanisms and also to investigate the challenge of the acinar acid load on ductal cells
Intracelluláris vĂ©dekezĹ‘ mechanizmusok akut pancreatitisben: kĂsĂ©rletes Ă©s klinikai vizsgálatok = Intracellular protective mechanisms in acute pancreatitis: experimental and clinical investigations
● Arginin (Arg)-indukálta kĂsĂ©rletes pancreatitis során az Arg specifikus Ă©s dĂłzis-fĂĽggĹ‘ NF-kB aktiváciĂłt okoz. ● Pyrrolidin dithiocarbamáttal Ă©s steroidokkal vĂ©gzett elĹ‘kezelĂ©s blokkolja az NF-kB aktiváciĂłt, Ă©s csökkenti a pancreatitis intenzitását. A steroid receptor antagonista RU-38486 fokozta a pancreatitis indukálta gyulladásos jeleket. ● Szintetikus NF-kB gátlĂł peptidet (PN50) ill. azt a sejtbe transzportálĂł penetratin analĂłgot állĂtottunk elĹ‘, melyek alkalmazásával az elĹ‘- Ă©s utĂłkezelĂ©s egyaránt jelentĹ‘sen csökkentette a cholecystokinin (CCK)-indukálta kĂsĂ©rletes pancreatitis sĂşlyosságát. ● A szintetikus proteoszĂłma inhibitor MG132 tripeptid jelentĹ‘sen gátolta az IkB degradáciĂłt Ă©s a következmĂ©nyes NF-kB aktiváciĂłt. Ez a magyarázata annak, hogy az MG132-vel vĂ©gzett elĹ‘- Ă©s utĂłkezelĂ©s egyaránt jelentĹ‘sen csökkentette a CCK-indukálta kĂsĂ©rletes pancreatitis sĂşlyosságát. ● Ischemia-reperfĂşziĂłval kiváltott nekrotizálĂł pancreatitis kialakulásában igazoltuk a gyulladásos cytokinek, Ă©s a nitrogĂ©n monoxid szerepĂ©t, Ă©s azt, hogy az apoptosis fokozásával mĂ©rsĂ©kelhetĹ‘ a necrosis mĂ©rtĂ©ke. ● Genetikai eredmĂ©nyeink arra utalnak, hogy a humán acut pancreatitis sĂşlyosságát a CD14 LPS receptor polymorfizmusa nem befolyásolja. A HSP70-2G Ă©s a TNF-?-308 allĂ©lek elĹ‘fordulása azonban jelentĹ‘sen gyakoribb volt a sĂşlyos nekrotizálĂł formákban. | ● Arginine (Arg) induces a dose-dependent activation of NF-kB in Arg-induced pancreatitis. ● Both pyrrolidin dithiocarbamate (PDTC) and steroid pretreatment blocked the activation of NF-kB with simultaneous decrease in the intensity of the inflammation. The steroid receptor antagonist RU-38486 had an opposite effect. ● Both the synthetic inhibitory peptide (PN50) of NF-kB and the cell transporter penetratin significantly decreased the severity of CCK-induced experimental pancreatitis. As sign of cyto-protection, PN50 increased the proportion of apoptosis versus necrosis of acinar cells. ● The synthetic proteasome inhibitor MG132 tripeptide (Z-Leu-Leu-Leu-aldehyd) significantly inhibited the degradation of IkB and the activation of NF-kB. ● Melatonin and resveratrol diminished severity and mortality of pancreatitis. ● In human studies we have demonstrated that high frequencies of the HSP70-2 G and the TNF-?-308 alleles were associated with risk of severe acute pancreatitis. Genotype assessments with determination of the polymorphisms of these genes may be important prognostic tools to predict disease severity and the course of acute pancreatitis. ● Pancreatic ductal epithelium derived from guinea pig was infected with genetically modified (non-virulent) pseudorabies virus. These results may open the possibility for gene transfer and gene therapy of the pancreas
Az apikális anion transzporterek/csatornák szerepe a pancreas duktális sejtek szekréciójában = The role of apical anion transporters/channels in secretion by pancreatic duct cells
Kutatásaink során összessĂ©gĂ©ben fontos Ă©lettani Ă©s kĂłrĂ©lettani informáciĂłkat szereztĂĽnk a cisztás fibrĂłzis transzmembrán konduktancia regulátor (CFTR), az SCL26A6 (PAT-1 – putatĂv anion transzporter 1) Ă©s a Na+/H+ cserĂ©lĹ‘ regulátor faktor 1 (NHERF-1) hasnyálmirigy duktális epitĂ©l sejtek bikarbonát Ă©s folyadĂ©k szekrĂ©ciĂłjában betöltött szerepĂ©rĹ‘l egĂ©r pankreászban. A CFTR, PAT-1 Ă©s NHERF-1 csökkent expressziĂłja a pankreász vezetĂ©ksejtek bikarbonát- Ă©s folyadĂ©k szekrĂ©ciĂłjának a csökkenĂ©sĂ©hez vezet. A NHERF-1 központi szerepet játszik a CFTR apikális membránba valĂł kijutásában, Ă©s biztosĂtja a CFTR apikális membránban valĂł lokalizáciĂłját. Kimutattuk azt is, hogy a NHERF-1 gĂ©nkiĂĽtött egerekben az akut hasnyálmirigygyulladás (fĹ‘leg az acinus sejtek károsodása) kĂ©t modellben (ceruleines Ă©s taurokĂłlsavas) is sĂşlyosabb volt a vad-tĂpusĂş állatokhoz kĂ©pest. Az in vivo adatok alátámasztják, hogy a pankreász duktális sejteknek fontos szerepĂĽk van az akut pankreatitisz patogenezisĂ©ben. VĂ©gsĹ‘ soron eredmĂ©nyeink utat nyithatnak egy Ăşj terápiás lehetĹ‘sĂ©g felĂ© (duktális szekrĂ©ciĂł fokozása) a pankeász gyulladásos megbetegedĂ©seinek kezelĂ©sĂ©ben, amik eddig fĹ‘leg az acinus sejtekre fĂłkuszáltak. | Overall, the project provided important information on the roles of cystic fibrosis transmembrane conductance regulator (CFTR), putative anion transporter 1 (PAT-1) and Na+/H+ exchanger regulatory factor-1 (NHERF-1) in the pancreatic ductal bicarbonate and fluid secretion in mice. NHERF-1 plays a critical role in regulating the apical trafficking/retention of CFTR in mouse pancreatic duct cells. The decrease in CFTR, PAT-1 and NHERF-1 expression resulted in greatly reduced pancreatic ductal secretion. Moreover, NHERF-1 expression also influenced the development of acute necrotizing pancreatitis. In fact, acute pancreatitis severity (especially acinar necrosis) was higher in NHERF-1 knock-out vs. wild-type mice. Importantly, we provide in vivo data that suggest the involvement of pancreatic ducts in the pathogenesis of acute pancreatitis. The results obtained from this study may eventually open up new therapeutic possibilities (targeting ductal secretion) in the treatment of pancreatic inflammation which have mainly focused on acinar cells
Mechanisms linking hypertriglyceridemia to acute pancreatitis
Hypertriglyceridemia (HTG) is a metabolic disorder, defined when serum or plasma triglyceride concentration (seTG) is >1.7 mM. HTG can be categorized as mild to very severe groups based on the seTG value. The risk of acute pancreatitis (AP), a serious disease with high mortality and without specific therapy, increases with the degree of HTG. Furthermore, even mild or moderate HTG aggravates AP initiated by other important etiological factors, including alcohol or bile stone. This review briefly summarizes the pathophysiology of HTG, the epidemiology of HTG-induced AP and the clinically observed effects of HTG on the outcomes of AP. Our main focus is to discuss the pathophysiological mechanisms linking HTG to AP. HTG is accompanied by an increased serum fatty acid (FA) concentration, and experimental results have demonstrated that these FAs have the most prominent role in causing the consequences of HTG during AP. FAs inhibit mitochondrial complexes in pancreatic acinar cells, induce pathological elevation of intracellular Ca2+ concentration, cytokine release and tissue injury, and reduce the function of pancreatic ducts. Furthermore, high FA concentrations can induce respiratory, kidney, and cardiovascular failure in AP. All these effects may contribute to the observed increased AP severity and frequent organ failure in patients. Importantly, experimental results suggest that the reduction of FA production by lipase inhibitors can open up new therapeutic options of AP. Overall, investigating the pathophysiology of HTG-induced AP or AP in the presence of HTG and determining possible treatments are needed
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