Rufina Schuligoi - Academia.edu (original) (raw)

Papers by Rufina Schuligoi

Gastroenterology, 2000

Epidermal growth factor (EGF) induces gastric epithelial cell migration, re-epithelialization, an... more Epidermal growth factor (EGF) induces gastric epithelial cell migration, re-epithelialization, and thus is essential for gastric erosion and ulcer healing. The key events regulating cell motility and proliferation include polymerization of actin, formation of stress fibers and focal adhesions. Tensin crosslinks and caps actin filaments, and forms complexes with FAK and PI-3K in focal adhesions. The molecular mechanisms regulating reepithelialization, especially the roles of tensin, and focal adhesion kinase (FAK) remain unexplored. In this study, we investigated in wounded gastric epithelial monolayers, the effect of EGF on cell cytoskeletal architecture, EGF-receptor (EGF-R) phosphorylation and the rate of re-epithelialization. Methods: In confluent monolayers of rat gastric epithelial (RGMI) cells, standard excisional wounds were made and cultures incubated with medium only or medium containing EGF (10 nglmI) for 24 and 48 hours. Studies: 1) wound re-epithelialization with video image system, 2) actin stress fiber formation by phalloidin labeling, 3) EGF-R phosphorylation, 4) tensin and FAK distribution by immunostaining, and 5) tensin and FAK phosphorylation. Results: EGF significantly accelerated wound re-epithelialization by 2-fold within 24 hrs (p<O.OO1), increased lamelipodia and stress fiber formation (28% ± 3% increase; p<O.OI), EGF-R phosphorylation (231%±19% increase p<0.02), FAK and tensin expression (96%±8% and 58%±6% increase respectively; both p<O.OI) and their phosphorylation (all p<0.05). Conclusion: EGF-accelerated wound re-epithelialization in gastric epithelial monolayers involves EGF-R phosphorylation, cytoskeletal reorganization including increased stress fibers and lamelipodia formation and increased phosphorylation of FAK and tensin proteins. ). We examined the interaction of salicylate with selective COX-2 inhibitors using 2 models of gastric damage. Methods: Male Wistar rats were used. 1) Gastric ischaemia-reperfusion: Rats were anaesthetized with pentobarbital. The pylorus was ligated and 1 mI of 0.1 N HCl instilled p.o. The celiac artery was occluded for 15 min followed by 30 min reperfusion. Then gastric damage was assessed using a lesion index (LI). Groups of rats were pretreated with the selective COX-2 inhibitors DFU (2 mglkg, s.c., 30 min) or NS-398 (4 mglkg, s.c., 30 min) or the nitric oxide (NO) synthase inhibitor L-NAME (10 mglkg, i.v., 10 min). Further rats received sodium salicylate (0.01-0.05 mglkg, s.c.) 30 min before DFU and NS-398 or 50 min before L-NAME. 2) Mild irritant-induced gastroprotection: Conscious rats received 1 mI of 20% ethanol p.o. followed by 1 mI of 70% ethanol 30 min later. After further 5 min, mucosal damage was assessed. Groups of rats received DFU (0.2 mglkg, p.o., 30 min), NS-398 (1 mglkg, p.o., 30 min) or L-NAME (10 mglkg, i.v., 10 min) before 20% ethanol. Further groups ofrats received salicylate (0.01-0.05 mglkg, p.o.) 30 min before DFU, NS-398 or L-NAME. Results: Mucosal damage was minor after ischaemia-reperfusion alone (LI 4 ± 1) but was significantly (p<O.OOI) aggravated by pretreatment with DFU (LI 34±2), NS-398 (LI 39±2) or L-NAME (LI 42±2). Salicylate (0.05 mglkg) reversed (p<O.OO1) the effects of DFU (LI 1O± 1) and NS-398 (LI 1O± 1) but not L-NAME (LI 38±3). The salicylate effect was dose-dependent (1050 against NS-398: 0.02 mglkg). Instillation of 20% ethanol prevented damage caused by 70% ethanol (LI 4± 1 vs. 32± 1, p<O.OOI). The protection was inhibited (p<O.OOI) by DFU (LI 33±I), NS (LI 29±2) or L-NAME (LI 43±2). Salicylate (0.05 mglkg) given alone did not protect against damage caused by 70% ethanol (LI 29±3) but abolished (p<O.OOI) the inhibition of mild irritant-induced protection evoked by DFU (LI 1O±3) and NS-398 (LI 4±I) but not L-NAME (LI 4I±3). The salicylate effect was dose-dependent (1050 against NS-398: 0.02 mglkg). Conclusions: Salicylate at very low doses inhibits the effects of selective COX-2 inhibitors on rat gastric mucosal integrity. It remains to be investigated whether this drug interaction occurs at the level of COX-2 or is a prostanoidindependent phenomenon.

Inflamm Research, 1999

Recent observations have demonstrated a central role of the &amp;quot;inducible&a... more Recent observations have demonstrated a central role of the &amp;quot;inducible&amp;quot; isoform of the cyclooxygenase (COX), COX-2, in the rat lung. Therefore, the reported capacity of selective COX-2 inhibitors to potentiate the formation of leukotriene (LT) B4 may raise concern about pro-inflammatory side effects of such drugs in the respiratory system. The present study was aimed at determining the effects of the COX-2 inhibitor NS-398 on the release of COX and 5-lipoxygenase (LOX) metabolites of arachidonic acid in isolated perfused lungs obtained from endotoxin-treated rats before and after stimulation with the leukocyte secretagogue N-formyl-methionyl-leucyl-phenylalanine (FMLP). Two hours after rats had received endotoxin i.v., the lung was dissected and perfused via the pulmonary artery with physiological salt solution. After an equilibration period of 20 min the outflow was collected (5-min fractions). In the respective treatment groups, indomethacin, NS-398, or the 5-LOX inhibitor MK886 were present throughout the experiment, while FMLP was added to the perfusate during a single 5-min period. The concentration of eicosanoids in the outflow was determined by radioimmunoassay. Endotoxin treatment of rats resulted in increased expression of COX-2 mRNA in lung tissue, and an elevated basal release of the prostaglandin (PG)I2 metabolite 6-keto PGF1alpha, without a detectable increase of leukotriene (LT) formation. In-vitro exposure to FMLP stimulated LT and prostanoid release, which was significantly enhanced in endotoxin-primed lungs, and was suppressed by the 5-LOX inhibitor MK-886 (3 microM) and the COX-inhibitor indomethacin (5 microM), respectively. Either compound showed selective inhibition of the respective pathway of arachidonic acid metabolism. In endotoxin-primed lungs, the COX-2 inhibitor NS-398 (0.3-1.0 microM) depressed basal as well as FMLP-stimulated release of 6-keto PGF1alpha, but did not cause a significant increase of LTB4 or cysteinyl-LT release. These results suggest that FMLP, presumably acting on inflammatory cells trapped in the pulmonary circulation of endotoxin treated rats, induced prostanoid formation mainly via the COX-2 pathway, and that its inhibition by NS-398 had no detectable potentiating effect on LTB4 or cysteinyl-LT biosynthesis.

Scientific Reports, 2016

Plasma advanced oxidation protein products (AOPPs), a class of pro-inflammatory pathogenic mediat... more Plasma advanced oxidation protein products (AOPPs), a class of pro-inflammatory pathogenic mediators, accumulate in subjects with chronic kidney disease. Whether AOPPs contribute to coagulation abnormalities, which are frequently seen in uremic patients, is unknown. Here we report that AOPPs activate platelets via a CD36-mediated signaling pathway. Activation of signaling pathways by AOPP-platelet interaction resulted in the expression of several platelet activation markers and rapidly induced the expression of CD40 ligand, triggering platelet adhesion to endothelial cells and promoting endothelial tissue factor expression. AOPPs and serum tissue factor levels were considerably increased in end stage renal disease patients on hemodialysis and a significant correlation of AOPPs and serum tissue factor was found. Interestingly, serum levels of AOPPs and tissue factor were substantially lower in stable kidney transplant patients when compared with hemodialysis patients. Given that CD36 is known to transduce the effects of oxidized lipids into platelet hyperactivity, our findings reveal previously unknown pro-thrombotic activities of oxidized plasma albumin via a CD36 dependent pathway.

International Immunopharmacology, Feb 29, 2008

Perfluorooctanoic acid (PFOA) and agonists of peroxisome proliferator-activated receptors (PPAR) ... more Perfluorooctanoic acid (PFOA) and agonists of peroxisome proliferator-activated receptors (PPAR) alpha and gamma were investigated for potential anti-inflammatory effects in cerulein-induced acute pancreatitis in rats. PFOA significantly reduced both leukocyte accumulation and prostanoid synthesis. The PPAR-alpha agonist clofibrate had no effect on leukocyte activation but significantly inhibited prostanoid synthesis whereas the PPAR-gamma agonist rosiglitazone significantly reduced leukocyte activation but did not affect synthesis of prostaglandins in the pancreas. Neither PFOA, nor clofibrate or rosiglitazone had an effect on the formation of the inflammatory edema or elevated levels of lipase activity in the blood serum. In summary, PFOA attenuates the accumulation of activated leukocytes and reduces the synthesis of prostanoids in the pancreas during cerulein-induced acute pancreatitis. An activation of PPAR-alpha causes inhibition of prostanoid synthesis while activation of PPAR-gamma inhibits leukocyte activation.

The Journal of Pharmacology and Experimental Therapeutics, Jun 1, 2001

The mechanisms of diarrhea in Asiatic cholera have been studied extensively. Cyclic AMP, 5-hydrox... more The mechanisms of diarrhea in Asiatic cholera have been studied extensively. Cyclic AMP, 5-hydroxytryptamine, prostaglandins, and the function of neuronal structures have been implicated in the pathogenesis of cholera. To elucidate the role of the different isoforms (COX-1 and COX-2) of cyclooxygenase in cholera toxin (CT)-induced fluid secretion and intraluminal prostaglandin E 2 (PGE 2 ) release in the rat jejunum in vivo, the effects of the COX-2 inhibitors NS-398 ([N-(2-cyclohexaloxy-4nitrophenyl)methanesulfonamide]) and DFU [5,5-dimethyl-3-(3fluorophenyl)-4-(4-methylsulfonyl)phenyl-2(5H)-furanone], and of the COX-1 inhibitor SC-560, were studied. Net fluid transport was measured gravimetrically and PGE 2 by radioimmunoassay. COX-1 and COX-2 mRNA expression were determined by reverse transcription-polymerase chain reaction (RT-PCR) and COX-2 protein by Western blot analysis in mucosal scrapings. CT caused profuse net fluid secretion in all control rats. The COX-2 inhibitors NS-398 and DFU, but not the COX-1 inhibitor SC-560 or dexamethasone, dose-dependently inhibited CTinduced fluid secretion and PGE 2 release. RT-PCR showed expression of COX-1 and of COX-2 mRNA in control rats. CT did not induce an increase and dexamethasone did not reduce COX-2 mRNA, whereas lipopolysaccharide caused a marked induction of COX-2 mRNA, which was inhibited by dexamethasone. A weak band of COX-2 protein was observed in controls; however, CT enhanced COX-2 levels, which remained unaffected by dexamethasone. It can be assumed that posttranscriptional modulation is responsible for CT-induced increase in COX-2 protein. COX-1 does not seem to be involved. Therefore, PGE 2 produced by COX-2 seems to be responsible for the profuse fluid secretion induced by CT, and COX-2 appears to be a specific target for the treatment of Asiatic cholera.

Journal of Allergy and Clinical Immunology, 2016

Prostaglandin (PG) D2 is an early-phase mediator in inflammation, but its action and the roles of... more Prostaglandin (PG) D2 is an early-phase mediator in inflammation, but its action and the roles of the 2 D-type prostanoid receptors (DPs) DP1 and DP2 (also called chemoattractant receptor-homologous molecule expressed on TH2 cells) in regulating macrophages have not been elucidated to date. We investigated the role of PGD2 receptors on primary human macrophages, as well as primary murine lung macrophages, and their ability to influence neutrophil action in vitro and in vivo. In vitro studies, including migration, Ca(2+) flux, and cytokine secretion, were conducted with primary human monocyte-derived macrophages and neutrophils and freshly isolated murine alveolar and pulmonary interstitial macrophages. In vivo pulmonary inflammation was assessed in male BALB/c mice. Activation of DP1, DP2, or both receptors on human macrophages induced strong intracellular Ca(2+) flux, cytokine release, and migration of macrophages. In a murine model of LPS-induced pulmonary inflammation, activation of each PGD2 receptor resulted in aggravated airway neutrophilia, tissue myeloperoxidase activity, cytokine contents, and decreased lung compliance. Selective depletion of alveolar macrophages abolished the PGD2-enhanced inflammatory response. Activation of PGD2 receptors on human macrophages enhanced the migratory capacity and prolonged the survival of neutrophils in vitro. In human lung tissue specimens both DP1 and DP2 receptors were located on alveolar macrophages along with hematopoietic PGD synthase, the rate-limiting enzyme of PGD2 synthesis. For the first time, our results show that PGD2 markedly augments disease activity through its ability to enhance the proinflammatory actions of macrophages and subsequent neutrophil activation.

Naunyn Schmiedeberg S Archives of Pharmacology, 1989

The influence of capsaicin-sensitive afferent neurones on the regulation of blood pressure by ... more 1) The influence of capsaicin-sensitive afferent neurones on the regulation of blood pressure by reflex noradrenergic responses and by activation of the reninangiotensin system was investigated in the rat anaesthetized with pentobarbital. (2) Lowering the pressure in the carotid sinus through unilateral carotid occlusion caused a reflex rise in mean systemic blood pressure which was less marked in capsaicin-pretreated rats than in controls, although an equal drop in mean pressure in the carotid sinus region was observed in both groups. Occlusion of the second carotid artery caused an additional increase in mean systemic blood pressure which was identical in the two groups. (3) Pharmacological blockade of the renin-angiotensin-system with captopril induced a more pronounced hypotonia in capsaicin-pretreated than in control rats. Yet, this difference was based on the impaired noradrenergic counterregulation in capsaicin-pretreated rats, because both groups showed identical responses to captopril following guanethidine-induced adrenergic blockade. (4) Plasma renin activity was increased by a factor of 2 following guanethidine treatment of awake animals, it reached levels 5-7 times higher than those observed in awake animals during pentobarbital anaesthesia. This anaesthesia-induced increase in plasma renin activity was not altered by guanethidine pretreatment. There was no difference in plasma renin activity between controls and capsaicin-pretreated rats under all the conditions tested. (5) These results show that the immediate reflex adjustment of blood pressure is impaired in the capsaicin-pretreated rat, possibly because of an impairment of sensors for low perfusion pressure in the carotid sinus. On the other hand, the renin-angiotension-system remains unimpaired after neonatal capsaicin-pretreatment.

Applied immunohistochemistry & molecular morphology: AIMM / official publication of the Society for Applied Immunohistochemistry

Pharmacology, 2014

Prostaglandin (PG) E2 has been implicated in the pathogenesis of aspirin-exacerbated respiratory ... more Prostaglandin (PG) E2 has been implicated in the pathogenesis of aspirin-exacerbated respiratory disease (AERD). E-type prostanoid (EP) receptor 4 is known to confer inhibitory signals to eosinophils and monocytes, amongst others. In this study, we investigated whether the responsiveness of eosinophils and monocytes to PGE2 and EP4 receptor activation is altered in AERD patients. While the expression of the EP4 receptor in eosinophils was unaltered in AERD patients, inhibition of eosinophil chemotaxis by PGE2 or the EP4 agonist CAY10598 was less pronounced in AERD patients as compared to healthy control subjects. In monocytes, we found no changes in basal or lipopolysaccharide (LPS)-stimulated PGE2 synthesis, but the response to EP4 receptor activation with respect to inhibition of LPS-induced tumor necrosis factor-α release was reduced in AERD patients, especially in the presence of aspirin (acetylsalicylic acid). Our data point towards a decreased sensitivity of inhibitory EP4 rec...

Pharmacology & Therapeutics, 2013

The large variety of biological functions governed by prostaglandin (PG) E 2 is mediated by signa... more The large variety of biological functions governed by prostaglandin (PG) E 2 is mediated by signaling through four distinct E-type prostanoid (EP) receptors. The availability of mouse strains with genetic ablation of each EP receptor subtype and the development of selective EP agonists and antagonists have tremendously advanced our understanding of PGE 2 as a physiologically and clinically relevant mediator. Moreover, studies using disease models revealed numerous conditions in which distinct EP receptors might be exploited therapeutically. In this context, the EP4 receptor is currently emerging as most versatile and promising among PGE 2 receptors. Anti-inflammatory, anti-thrombotic and vasoprotective effects have been proposed for the EP4 receptor, along with its recently described unfavorable tumor-promoting and pro-angiogenic roles. A possible explanation for the diverse biological functions of EP4 might be the multiple signaling pathways switched on upon EP4 activation. The present review attempts to summarize the EP4 receptor-triggered signaling modules and the possible therapeutic applications of EP4-selective agonists and antagonists.

Regulatory Peptides, 2000

The biological inactivation of enkephalins by neutral endopeptidase (enkephalinase, NEP, EC3.4.24... more The biological inactivation of enkephalins by neutral endopeptidase (enkephalinase, NEP, EC3.4.24.11) represents a major mechanism for the termination of enkephalinergic signalling in brain. A pharmacological blockade of NEP-activity enhances extracellular enkephalin concentrations and induces opioid-dependent analgesia. Recently, knockout mice lacking the enzyme NEP have been developed [Lu et al., J. Exp. Med. 1995;181:2271-2275. The present study investigates the functional consequences and biochemical compensatory strategies of a systemic elimination of NEP activity in these knockout mice. Using biochemical and behavioural tests we found that the lack of NEP activity in brain is not compensated by enhanced activities of alternative enkephalin-degrading enzymes. Also no change in enkephalin biosynthesis was detectable by in situ methods quantifying striatal proenkephalin-mRNA levels in NEP-deficient mice compared with wildtype. Only a 21% reduction of m receptor density in crude brain homogenates of NEP knockout mice was observed, while dand k-opioid receptor densities were unchanged. This receptor downregulation was also confirmed functionally in the hot-plate paradigm. NEP knockouts developed normally, but showed enhanced aggressive behaviour in the resident-intruder paradigm, and altered locomotor activity as assessed in the photobeam system. Thus, although NEP plays a substantial role in enkephalinergic neurotransmission, the biochemical adaptations within the opioid system of NEP-deficient mice are of only modest nature.

Regulatory Peptides, 1992

The capsaicin-evoked release of calcitonin gene-related peptide (CGRP) from rat superfused dorsal... more The capsaicin-evoked release of calcitonin gene-related peptide (CGRP) from rat superfused dorsal spinal cord slices was investigated during sustained capsaicin exposure thought to represent equilibrium conditions. The dose-effect relationship for total peptide release evoked by single capsaicin doses (26 min exposure) was very steep with a threshold at 0.06 microM and a maximum at 0.3 microM capsaicin. With concentrations of capsaicin within this range the slow decline of the peptide release in the presence of capsaicin was not a consequence of exhaustion of an available peptide pool nor of neuronal impairment because potassium depolarization was still able to release CGRP. In contrast, with concentrations of capsaicin at 1.5 microM and above, there was a much faster decay of the release after the peak, most probably due to a loss of the secretion capacity caused by neuronal inactivation. When cumulative dose regimens for capsaicin were employed, release of CGRP could be stimulated only up to a dose of 1-1.5 microM capsaicin; further increase in capsaicin concentration was ineffective. This was also most probably due to a loss of the secretion capacity caused by neuronal inactivation and not caused by depletion of a releaseable peptide pool. Release of CGRP evoked by capsaicin concentrations in the range of 0.1-0.3 microM in either dosage protocol was reduced in the presence of Ruthenium Red (RR, 2.5 microM). RR did not reduce neuropeptide release evoked by capsaicin concentrations at or above 1-1.5 microM, nor did it affect the inactivation of the release process at such high capsaicin concentrations. The results demonstrate that, upon sustained exposure to capsaicin, different ranges of concentration can be established at which either only stimulatory or a mixture of stimulatory and inhibitory effects determine the amount of neuropeptides released.

Regulatory Peptides, 2001

. Noxious challenge of the rat gastric mucosa by hydrochloric acid HCl is signalled via vagal aff... more . Noxious challenge of the rat gastric mucosa by hydrochloric acid HCl is signalled via vagal afferent neurons to several brain nuclei in which tachykinins and tachykinin receptors are present. Therefore, we tested whether tachykinin receptor antagonists would modify the central transmission of input from the acid-threatened stomach. Neuronal excitation was visualized by in situ hybridization autoradiog-Ž . Ž . Ž . Ž . raphy ISH of c-fos messenger ribonucleic acid mRNA 45 min after intragastric IG administration of HCl 0.5 M; 10 mlrkg . This Ž . Ž . stimulus has previously been shown to cause neurons in the nucleus tractus solitarii NTS , lateral parabrachial nucleus LPB , Ž . Ž . Ž . Ž . Ž . paraventricular Pa nuclei, supraoptic SO nucleus, central amygdala CeA , area postrema AP , subfornical organ SFO and habenula Ž . Ž . Ž . Hb to express c-fos mRNA. Intraperitoneal IP pretreatment with the NK receptor antagonist GR-205,171 3 mgrkg attenuated the 1 Ž . acid-induced transcription of c-fos mRNA in NTS and augmented it in SFO. The NK receptor antagonist SR-144,190 0.1 mgrkg, IP 2 Ž

PLoS ONE, 2012

The use of the lipid lowering agent niacin is hampered by a frequent flush response which is larg... more The use of the lipid lowering agent niacin is hampered by a frequent flush response which is largely mediated by prostaglandin (PG) D 2 . Therefore, concomitant administration of the D-type prostanoid (DP) receptor antagonist laropiprant has been proposed to be a useful approach in preventing niacin-induced flush. However, antagonizing PGD 2 , which is a potent inhibitor of platelet aggregation, might pose the risk of atherothrombotic events in cardiovascular disease. In fact, we found that in vitro treatment of platelets with laropiprant prevented the inhibitory effects of PGD 2 on platelet function, i.e. platelet aggregation, Ca 2+ flux, P-selectin expression, activation of glycoprotein IIb/IIIa and thrombus formation. In contrast, laropiprant did not prevent the inhibitory effects of acetylsalicylic acid or niacin on thrombus formation. At higher concentrations, laropiprant by itself attenuated platelet activation induced by thromboxane (TP) and E-type prostanoid (EP)-3 receptor stimulation, as demonstrated in assays of platelet aggregation, Ca 2+ flux, P-selectin expression, and activation of glycoprotein IIb/IIIa. Inhibition of platelet function exerted by EP4 or I-type prostanoid (IP) receptors was not affected by laropiprant. These in vitro data suggest that niacin/laropiprant for the treatment of dyslipidemias might have a beneficial profile with respect to platelet function and thrombotic events in vascular disease. Citation: Philipose S, Konya V, Lazarevic M, Pasterk LM, Marsche G, et al. (2012) Laropiprant Attenuates EP3 and TP Prostanoid Receptor-Mediated Thrombus Formation. PLoS ONE 7(8): e40222.

Pharmacology, 2002

Injection of carrageenan (1 mg) into the rat hind paw caused a time-dependent increase in paw vol... more Injection of carrageenan (1 mg) into the rat hind paw caused a time-dependent increase in paw volume that was maximal 3 h after injection. At this time, the concentration of nerve growth factor (NGF) in the skin of the inflamed paw was more than twofold higher than in the contralateral, non-inflamed paw. Treatment of rats with indomethacin reduced inflammatory oedema by 57%, morphine treatment attenuated oedema by 62%. While indomethacin had no statistically significant effect on the concentration of NGF in the skin of inflamed paws, morphine attenuated the NGF response by 24.2% in a naloxone reversible manner. These data suggest that drug-induced inhibition of inflammatory oedema is not predictive of its effect on an inflammation-induced rise in tissue NGF. Furthermore, our results confirm and extend previous observations suggesting an anti-inflammatory activity of morphine.