Biomedical subjects

A Slomiany

Publications and source records attributed to A Slomiany.

At least 19 recordsLinked to original sources

PubMed2006

Porphyromonas gingivalis lipopolysaccharide-induced cytosolic phospholipase A2 activation interferes with salivary mucin synthesis via platelet activating factor generation.

Liberation of arachidonate from membrane phospholipids by cytosolic phospholipase A2 (cPLA2) upon cell activation is considered the key step in generation of platelet-activating factor (PAF), a potent lipid messenger recognized as the most proximal mediator of inflammatory events triggered by bacterial infection. Here, we report on the role of cPLA2 in the disturbances in salivary mucin synthesis evoked by the lipopolysaccharide (LPS) of a periodontopathic bacterium, P. gingivalis. Using mucous cells of sublingual gland, we show that P. gingivalis LPS detrimental effect on salivary mucin synthesis, associated with up-regulation in PAF and endothelin-1 (ET-1) generation, was subject to suppression by a specific inhibitor of cPLA2, MAFP. Moreover, the LPS-induced changes in mucin synthesis and ET-1 generation were countered by PAF receptor antagonist, BN52020. The inhibition by PAF antagonist of the LPS-induced reduction in mucin synthesis was countered by wortmannin, an inhibitor of PI3K, as well as by ERK inhibitor, PD98059. The blockade of ERK caused also inhibition of the LPS-induced cPLA2 activation and amplification in the impedance capacity of PAF antagonist on the LPS-induced ET-1 generation, while the inhibitor of PI3K had no effect. The findings are the first to demonstrate that P. gingivalis LPS detrimental effect on salivary mucin synthesis involves ERK-dependent cPLA2 activation that leads to up-regulation in PAF production and ET-1 generation. We also show that PAF receptor activation is a critical prerequisite for the LPS-induced ET-1 production.

Animals↗

PubMed2006

Leptin modulates the detrimental effect of Porphyromonas gingivalis lipopolysaccharide-induced cytosolic phospholipase A2 activation on salivary mucin synthesis via ERK-signal transduction.

Activation of cytosolic phospholipase A2 (cPLA2) by bacterial LPS is considered a key step in the generation of proinflammatory lipid messengers, including platelet-activating factor (PAF), recognized as the most proximal mediator of inflammatory events triggered by bacterial infection. In this study, we report on the role of leptin in modulation of the detrimental consequences of cPLA2 activation in salivary gland acinar cells by the LPS of a periodontopathic bacterium, P. gingivalis. Employing mucous cells of rat sublingual gland, we show that the LPS-induced cPLA2 activation is associated with up-regulation in PAF generation and the impairment in mucin synthesis, and was subject to suppression by leptin. A potentiation in the countering capacity of leptin on the LPS-induced arachidonic acid release and PAF generation was attained in the presence of ERK inhibitor, PD98059, while the PI3K inhibitor, wortmannin had no effect. However, the prevention by leptin of the LPS detrimental effect on mucin synthesis was subject to suppression by the inhibitors of both PI3K and ERK. Moreover, amplification in the effect of leptin on the LPS-induced decrease in mucin synthesis was attained with cPLA2 inhibitor, MAFP as well as PAF receptor antagonist, BN52020, while the reversal of the leptin effect occurred in the presence of exogenous PAF. These findings demonstrate the involvement of leptin in countering the pathological consequences of cPLA2 activation by P. gingivalis LPS on salivary mucin synthesis through the involvement in MAPK/ERK and PI3K signaling events.

Animals↗

PubMed2005

Role of endothelin-1-dependent up-regulation of leptin in oral mucosal repair.

Leptin, a multifunctional hormone that regulates food intake and energy expenditure, has emerged recently as an important modulator of inflammatory cascades associated with wound healing. In this study, we applied the animal model of buccal mucosal ulcer to investigate the role of endothelin-1 (ET-1) and leptin in soft oral tissue repair. Using groups of rats with experimentally induced buccal mucosal ulcers we show that ulcer onset was characterized by a marked increase in the mucosal level of ET-1 and leptin. However, while the ET-1 level gradually declined with healing, the mucosal level of leptin increased reaching maximum expression on the 4th day of healing. Therapeutic administration of phosphoramidon, an inhibitor of ECE-1 activity, not only led to a 53.2% drop in the ET-1, but also produced a dose-dependent reduction (up to 50.9%) in the mucosal level of leptin and up to 42.3% decline in the rate of ulcer healing. A marked drop (54.2%) in the mucosal level of leptin and the reduction (46.8%) in the rate of ulcer healing was also attained in the presence of ETA receptor antagonist BQ610 administration, but not the ETB receptor antagonist BQ788. Moreover, administration of ERK inhibitor, PD98059 in the presence of ETB receptor antagonist, but not the ETA receptor antagonist, caused the reduction the mucosal leptin level as well as a decline in the rate of ulcer healing. Our findings are the first to implicate the requirement for both ET-1 and leptin in orderly progression of the events of soft oral tissue repair. We also show that ET-1 is a key factor in up-regulation of leptin production associated with oral mucosal ulcer healing , and that the effect of ET-1 on leptin production is a consequence of ETA receptor activation and subsequent signaling through MAPK/ERK.

Acetic Acid↗

PubMed2004

Platelet-activating factor mediates Porphyromonas gingivalis lipopolysaccharide interference with salivary mucin synthesis via phosphatidylinositol 3-kinase-dependent constitutive nitric-oxide synthase activation.

Platelet -activating factor (PAF), a phospholipid-derived messenger molecule, is now recognized as the most proximal mediator of cellular events triggered by bacterial lipopolysaccharide (LPS) stimulation. In this study, we assessed the role of PAF in the disturbances in salivary mucin synthesis evoked by LPS of periodontopathic bacterium, P. gingivalis. Using primary culture of mucous acinar cells of sublingual salivary gland, we show that a specific PAF antagonist, BN52020, prevents in a dose-dependent fashion (up to 83.7%) the LPS-induced reduction in mucin synthesis, and the effect is reflected in a marked decrease in the LPS-induced apoptosis (74.8%), NO generation (82.6%), and the expression of TNF-alpha (76.1%). The impedance by BN52020 of the LPS inhibitory effect on mucin synthesis was blocked by wortmannin, an inhibitor of phosphatidylinositol 3-kinase (PI3K), which also obviated the inhibitory effect of BN52020 on the LPS-induced upregulation in apoptosis, TNF-alpha, and NO. A potentiation in the impedance by BN52020 of the LPS detrimental effect on mucin synthesis was however attained with NOS-2 inhibitor, 1400W, while cNOS inhibitor, L-NNA caused a reduction in the impedance effect of BN52020. However, while 1400W and BN52020 countered the potentiating effect of wortmannin on the LPS-induced decrease in mucin synthesis, a further exacerbation of the effect of wortmannin occurred in the presence of L-NNA. The findings implicate PAF as a pivotal factor affecting the extent of pathological consequences of P. gingivalis infection on salivary glands capacity for mucin production, and suggest that its release in response to the LPS serves as a negative regulator of PI3K controlling the pathway of cNOS activation.

Amidines↗

PubMed2004

Secretion of gastric mucus phospholipids in response to beta-adrenergic G protein-coupled receptor activation is mediated by SRC kinase-dependent epidermal growth factor receptor transactivation.

Recent advances in understanding the nature of cellular responses mediated by G protein-coupled receptor (GPCR) activation indicate that integration of the converging regulatory signals into functional cellular pathways requires epidermal growth factor receptor (EGFR) transactivation. In this study, we report that G protein-coupled beta-adrenergic receptor activation leading to stimulation in gastric mucus phospholipid secretion occurs with the involvement of EGFR. Using [14C]choline-labeled gastric mucosal cells in culture, we show that stimulatory effect of beta-adrenergic agonist, isoproterenol, on phospholipid release was subject to a dose-dependent suppression by EGFR kinase inhibitor, PD153035, as well as wortmannin, a specific inhibitor of PI3K. Both inhibitors, moreover, caused the reduction in the gastric mucosal cell phospholipid secretory responses to beta-adrenergic agonist-generated second messenger, cAMP as well as adenyl cyclase activator, forskolin. The gastric mucosal phospholipid secretory responses to isoproterenol, furthermore, were inhibited by PP2, a selective inhibitor of tyrosine kinase Src responsible for ligand-independent EGFR phosphorylation, but not by ERK inhibitor, PD98059. The inhibition of ERK, moreover, did not cause attenuation in phospholipid secretory responses to cAMP and forskolin. The findings underline the central role of EGFR in mediation of gastric mucosal secretory processes, and demonstrate the requirement for Src kinase-dependent EGFR transactivation in regulation of gastric mucosal phospholipid secretion in response to beta-adrenergic GPCR activation.

Adrenergic beta-Agonists↗

PubMed2004

Gastric mucosal cell homeostatic physiome. Critical role of ER-initiated membranes restitution in the fidelity of cell function renewal.

Homeostatic cell physiology is preserved through the fidelity of the cell membranes restitution. The task is accomplished through the assembly of the precisely duplicated segments of the cell membranes, and transport to the site of their function. Here we examined the mechanism that initiates and directs the restitution of the intra- and extracellular membranes of gastric mucosal cell. The homeostatic restitution of gastrointestinal epithelial cell membrane components was investigated by studying the lipidomic processes in endoplasmic reticulum (ER) and Golgi. The biomembrane lipid synthesis during the formation of transport vesicles in the systems containing isolated organelle and the cell-specific cytosol (Cyt) from rat gastric mucosal epithelial cells was assessed. The results revealed that lipids of ER transport vesicle and the transmembrane and intravesicular cargo are delivered en bloc to the point of destination. En bloc delivery of proteins, incorporated into predetermined in ER lipid environment, ensures fidelity of the membrane modification in Golgi and the restitution of the lipid and protein elements that are consistent with the organelle and the cell function. The mechanism that maintains apical membrane restitution is mediated through the synthesis of membrane segments containing ceramide (Cer). The Cer-containing membranes and protein cargo are further specialized in Golgi. The portion of the vesicles destined for apical membrane renewal contains glycosphingolipids and phosphatidylinositol 3-phosphate. The vesicles containing phosphatidylinositol 4-phosphate are directed to endosomes. Our findings revealed that the preservation of the physiological equilibrium in cell structure and function is attributed to (1) a complete membrane segment synthesis in ER, (2) its transport in the form of ER-transport vesicle to Golgi, (3) the membrane components-defined maturation of lipids and proteins in Golgi, and (4) en bloc transfer of the new segment of the membrane to the cell apical membrane or intracellular organelle.

Animals↗

PubMed2003

Peroxisome proliferator-activated receptor gamma activation counters the detrimental effect of Helicobacter pylori lipopolysaccharide on gastric mucin synthesis.

Peroxisome proliferator-activated receptor-gamma (PPARgamma), a member of the subfamily of ligand-dependent nuclear transcription factors, plays a key role in the regulation of the expression of genes associated with inflammation. In this study, using gastric mucosal cells in culture, we assess the role of PPARgamma in the disturbances in gastric mucin synthesis and apoptotic processes evoked by Helicobacter pylori lipopolysaccharide (LPS). Exposure of gastric mucosal cells to the LPS led to a concentration-dependent decrease (up to 59.5%) in mucin synthesis, and this effect of the LPS was accompanied by a 6.5-fold increase in apoptosis, induction of COX-2 and NOS-2 protein expression, and the enhancement in PGE(2) generation (18.6-fold) and NOS-2 activity (24.1-fold). However, the expression of COX-1 protein was not affected. Activation of PPARgamma with a specific synthetic agonist, ciglitazone, countered (up to 90.2%) the LPS-induced reduction in mucin synthesis in a concentration-dependent manner, and this effect of the agent was reflected in a marked decrease in COX-2 and NOS-2 protein expression, reduction (up to 72.4%) in apoptosis and a decline (up to 84.1%) in PGE(2) generation and NOS-2 activity (up to 90%). A pronounced prevention (88.2%) in the LPS-induced PGE(2) release and the diminished COX-2 protein expression was also attained with the COX-2-selective inhibitor NS-398, but the effect was not associated with the impedance of the LPS inhibitory effect on mucin synthesis. Our findings thus demonstrate that the detrimental influence of H. pylori LPS on gastric mucin synthesis is closely linked to the increase in proapoptotic processes triggered by NOS-2 upregulation, and that PPARgamma activation obviates this detrimental effect. Hence, pharmacological manipulation of PPARgamma activation may provide therapeutic benefits in countering the disruptive effects of H. pylori on gastric mucosal mucus coat continuity.

Journal Article↗

PubMed2003

Differential role of platelet-activating factor in gastric mucosal ulcer healing.

Platelet-activating factor (PAF) is a potent phospholipid-derived messenger involved in a number of diverse pathological conditions, including mediation of inflammatory cascades associated with wound healing. In this study, we investigated the effect of a specific PAF antagonist, BN52020, on the course of experimentally induced gastric mucosal ulcer healing by analyzing apoptotic processes and the mucosal expression of TNF-alpha, COX-2, and the activity of inducible nitric oxide synthase (NOS-2). Groups of rats were intragstrically pretreated with BN52020 either 24 and 4 h before acetic acid injury (prophylactic) or 24 and 44 h after the injury (therapeutic) and their mucosal tissue subjected to assessment of ulcer healing rate and biochemical measurements. Compared with the controls, the prophylactic administration of BN52020 produced dose-dependent acceleration in ulcer healing, accompanied by an increase in COX-2 expression and a marked reduction in the extent of mucosal apoptosis, TNF-alpha and NOS-2 activity. A delay in ulcer healing, however, occurred with BN52020 administered therapeutically, and this effect of the agent was reflected in a decreased COX-2 protein expression and a significant increase in the rate of epithelial cell apoptosis, TNF-alpha, and the mucosal NOS-2 activity. Thus, PAF antagonist, BN52020, when administered prophylactically exerts anti-inflammatory effects that accelerate gastric ulcer healing, while given therapeutically interferes with COX-2 enzyme expression that leads to a protracted inflammatory responses that delay ulcer healing.

Journal Article↗

PubMed2003

Activation of peroxisome proliferator-activated receptor gamma impedes Porphyromonas gingivalis lipopolysaccharide interference with salivary mucin synthesis through phosphatidylinositol 3-kinase/erk pathway.

Peroxisome proliferator-activated receptor gamma (PPARgamma), a member of the superfamily of nuclear receptor transcription factors, plays a critical role in the regulation of the expression of genes associated with inflammation. Using mucous acinar cells of sublingual salivary gland, we investigated the effect of PPARgamma activation on the disturbances in salivary mucin synthesis evoked by lipopolysaccharide (LPS) of periodontopathic bacterium, P. gingivalis. Exposure of the acinar cells to the LPS led to a dose-dependent decrease (up to 58.4%) in mucin synthesis, accompanied by a massive enhancement in apoptosis and NO production, and an induction in inducible nitric oxide synthase (NOS-2) activity. Activation of PPARgamma with a specific synthetic agonist, ciglitazone, prevented in a dose-dependent fashion the LPS-induced reduction in mucin synthesis, and the effect was reflected in a marked decrease in apoptosis, NO generation, and the expression of NOS-2 activity. The impedance by ciglitazone of the LPS-induced changes in mucin synthesis was blocked by PD98059, an inhibitor of extracellular signal regulated kinase (ERK), as well as wortmannin, an inhibitor of phosphatidylinositol 3-kinase (PI3K). Moreover, both agents caused further enhancement in the LPS-induced nitric oxide generation and countered the inhibitory effect of ciglitazone on the LPS-induced upregulation in NOS-2. The findings suggest that the impedance of P. gingivalis LPS inhibition of salivary, mucin synthesis by PPARgamma agonist, ciglitazone, involves activation of ERK pathway by PI3K.

Animals↗

PubMed2003

Lipidomic processes in homeostatic and LPS-modified cell renewal cycle. Role of phosphatidylinositol 3-kinase pathway in biomembrane synthesis and restitution of apical epithelial membrane.

BACKGROUND: Nuclear transcriptome initiates specific proteome that facilitates metabolic events culminating in restitution of cell components and reproduction of the discrete cellular function, but the magnitude of various genes induction and following proteomic, lipidomic, and glycomic processes provide distinctness to the final product and its function. In homeostasis, the challenged cell responds to stimuli in defined and predictable mode but in the disease such as ulcerative erosions the ablation of cell survival signals and cell apoptosis is enhanced. Therefore, to uncover the discreteness and dissimilarity of the pathological processes induced by elicobacter pylori (H. pylori) lipopolysaccharide (LPS), not only measurement of the genomic events is crucial, but a complete cycle of events reproducing the cell specific proteins, lipids, and cell-specific environment created in situ require thorough investigation. METHODS: An impact of H. pylori LPS-induced processes on posttranslational lipidomic activity in endoplasmic reticulum (ER), Golgi and apical membrane was evaluated in the in vitro paradigm assembled with components of the rat gastric mucosal epithelial cells. RESULTS: In ER, the signals commanding synthesis of biomembrane in the presence of control, the LPS-derived or LPS-admixed cytosol was identical. The assembled vesicles contained the same amount of apoprotein and had the same lipid composition. Their biomembrane contained the same amount of sphingolipids in form of ceramide, which is determining factor of the ER-transport vesicle completion. The transport of apoprotein in ER vesicles to Golgi was also not changed. In Golgi, LPS-derived cytosol affected two distinct and concurrent with assembly of Golgi transport vesicles processes. The LPS-derived cytosol affected formation of Golgi transport vesicles destined to apical membrane and the incorporation (fusion) of Golgi vesicles with apical epithelial membrane. The LPS-derived cytosol decreased the production of Golgi vesicles by 15% and their fusion with the apical epithelial membrane by 83%. In contrast with wortmannin, the LPS-derived cytosol had no impact on Golgi transport vesicles association with the epithelial membrane. CONCLUSIONS: We concluded that LPS interferes with MAPK-dependent activation of cytosolic PLA(2) since MAPKs immunoprecipitate added to the LPS-cytosol restored activation of cytosolic PLA(2)-specific fusion of the Golgi transport vesicles with apical mucosal cell membrane. On the other hand, wortmannin that inhibited the association of Golgi transport vesicles with apical membrane, interferes with cytosolic activity that controls association of PI3K-containing Golgi vesicles with the apical membrane. Together, our studies present evidence that allow to conclude that LPS affects MAPK-specific phosphorylation and PLA(2)-assisted membranes' fusion, whereas wortmannin affects association of PI3K- and PI3P-containing Golgi-derived transport vesicles with the membrane. In the final outcome, both actions result in a diminished or inhibited restitution of apical membrane.

Androstadienes↗

PubMed2002

Screening and modulation of extracellular signals by mucous barrier. Serum glycosylphosphatidylinositol phospholipase D (GPI-PLD) releases protective mucous barrier from oral mucosa.

BACKGROUND: Performance of mucosal epithelial barrier is modified by numerous agents that exert effects on mucin- Mucin Binding Protein (MBP) complex. The aim ofthe studies described was to determine the nature of the damage or modification of oral mucous barrier by the short-term exposure to ethanol. METHODS: Culture of rat buccal mucosa in the presence of ethanol and [3H]-labeled proline and palmitate revealed substantial decrease in MBP synthesis and the release of MBPto the medium. The radioscanning of the samples prepared from the culture medium and the apical epithelial membranes subjected to SDS-PAGE and western blotting disclosed that the released, water soluble 97kDa MBP glycopeptide was labeled with proline and palmitate. When the experiments were conducted in the presence of 5mM EDTA, the GPI-PLD inhibitor, the majority of radiolabeled MBP remained in the membrane-bound form and was extractable with Triton X- 114. The results on the purified GPI-linked MBP degradation by serum enzyme, by the saliva containing serum transudate, and the suppression of the process by inclusion of GPI-PLD-specific inhibitor support our contention that membrane MBP is released to medium by GPI-PLD-like activity. RESULTS: The release of MBP from apical epithelial surfaces was induced by depletion of mucin and the presence of serum-derived GPI-PLD in the tissue homogenate. Strong likelihood exists that under in situ conditions ethanol-induced transudation of serum to saliva provides the vehicle for the transfer of GPI-PLD activity to salivary contents. Defacement of the oral surfaces from mucous barrier signals prospect of lumenal agent influence on the unprotected epithelial exterior, and allows ingression of microbes and untoward acting substances into the organism.

Animals↗

PubMed2002

Activation of peroxisome proliferator-activated receptor gamma suppresses inducible cyclooxygenase and nitric oxide synthase during oral mucosal ulcer healing.

BACKGROUND: Peroxisome proliferator-activated receptor-gamma (PPARgamma) is a ligand-dependent transcription factor, belonging to the steroid hormone receptor family, known to play a pivotal role in the resolution of inflammation. In this study, we investigated the effect of a specific PPARgamma ligand, ciglitazone, on the course of buccal mucosal ulcer healing by analyzing mucosal activity of inducible nitric oxide synthase (NOS-2) and the expression cyclooxygenases (COX-1 and COX-2) responsible for prostaglandin (PG) generation. METHODS: Groups of rats with experimentally induced buccal mucosal ulcers were administered twice daily for up to 10 days with ciglitazone at 5, 10, and 15 mg/kg or the vehicle, and their mucosal tissue subjected to assessment of ulcer healing rate and biochemical measurements. RESULTS: The ulcer onset, characterized by up-regulation of NOS-2 and COX-2 protein expression, was reflected in a marked increase in the mucosal PGE2 generation and NOS-2 activity, whereas healing was accompanied by a drop in PGE2 and NOS-2 activity, and a decrease in COX-2 and NOS-2 protein expression. The mucosal expression of COX-1 protein, however, remained unchanged. Administration of ciglitazone led to a significant dose-dependent acceleration in the mucosal reduction of PGE2 generation and NOS-2 activity, and produced a marked decline in COX-2 and NOS-2 protein expression, but the rate of ulcer healing and the expression of COX-1 protein remained unaffected. CONCLUSIONS: Our findings thus suggest that the products of induced NOS-2 and COX-2 enzymes, associated with mucosal inflammatory responses to injury, do not play a significant role in oral mucosal ulcer healing.

Animals↗

PubMed2002

Nitric oxide interferes with salivary mucin synthesis: involvement of ERK and p38 mitogen-activated protein kinase.

BACKGROUND: Nitric oxide (NO), a pluripotent molecule, is an important biological messenger that plays a role in the regulation of tissue homeostasis and pathophysiological processes. METHODS: Using sublingual salivary gland acinar cells in culture, we investigated the effect of NO on mucus glycoprotein synthesis, apoptotic processes, and the involvement of extracellular signal-regulated kinase (ERK) and p38 mitogen activated protein kinase (MAPK). RESULTS: Exposure of the acinar cells to NO donor led to a dose-dependent decrease (up to 42.8%) in mucus glycoprotein synthesis, and this effect of NO was accompanied by a marked increase in caspase-3 activity and apoptosis. Inhibition of ERK with PD98059 accelerated (up to 35.4%) the NO-induced decrease in the glycoprotein synthesis, and cause further enhancement in caspase-3 (up to 27.2%) activity and apoptosis (64.9%). On the other hand, blockade of p38 kinase with SB203580 produced a dose-dependent reversal (up to 42%) in the NO-induced reduction in the glycoprotein synthesis, and substantially countered the NO-induced increases in caspase-3 activity (by 62.8%) and apoptosis (by 57.6%). Moreover, caspase-3 inhibitor, Ac-DEVD-CHO, not only blocked the NO-induced increase in caspase-3 activity but also produced an increase in the glycoprotein synthesis. CONCLUSIONS: Together, our data indicate that the modulatory influence of NO on salivary mucin synthesis is closely linked to ERK and p38 protein kinase activation, in conjunction with caspase-3 activation and apoptosis.

Animals↗

PubMed2001

Role of ERK and p38 mitogen-activated protein kinase cascades in gastric mucosal inflammatory responses to Helicobacter pylori lipopolysaccharide.

The animal model of H. pylori lipopolysaccharide (LPS)-induced gastritis was used to study the role of extracellular signal-regulated kinase (ERK) and p38 mitogen-activated protein kinase (MAPK) in the mucosal release of tumor necrosis factor-alpha (TNF-alpha) and endothelin-1 (ET-1) in response to H. pylori infection. Rats, pretreated with specific inhibitors of p38 and ERK pathways, SB203580 and PD98059, were submitted to intragastric application of H. pylori LPS and maintained on the daily regimen of the inhibitors for 4 days. In the absence of inhibitors, the LPS elicited a pattern of mucosal inflammatory responses resembling that of acute gastritis, and reflected in a massive increase in the mucosal level of ET-1 and TNF-alpha. Administration of SB203580 led to a 63.4% reduction in the extent of inflammatory involvement, the level of ET-1 fell by a 42% and TNF-alpha declined by a 52.3%, whereas PD98059 elicited a 21.2% reduction in the extent of inflammatory involvement and a 22.7% decrease in TNF-alpha, but had no effect on the LPS-induced increase in ET-1. A combination of both inhibitors, while exerting additive effect on TNF-alpha, produced no additional reduction in ET-1 and the extent of inflammatory involvement achieved with SB203580 alone. The findings suggest that the p38 MAPK signaling pathway plays a key role in the mediation of gastric mucosal inflammatory reaction to H. pylori infection.

Animals↗

PubMed2001

Nonsteroidal anti-inflammatory drugs impair oral mucosal repair by eliciting disturbances in endothelin-converting enzyme-1 and constitutive nitric oxide synthase.

Although the use of nonsteroidal anti-inflammatory drugs (NSAIDs) is known to cause the impairment in mucosal defenses that are well recognized and clinically emphasized with respect to the gastrointestinal tract, less apparent is the extent of their interference with the repair of soft oral tissue. As the disturbances in nitric oxide generation and the release of endothelin-1 (ET-1) are the early signs of injury by NSAIDs, we investigated oral mucosal ulcer healing in the presence of NSAID administration by analyzing the expression of endothelin-converting enzyme-1(ECE-1), responsible for ET-1 generation, and the mucosal activity of inducible (NOS-2) and constitutive (cNOS) nitric oxide synthase responsible for nitric oxide production. Groups of rats with acetic-induced buccal mucosal ulcers were subjected twice daily for up to 10 days to intragastric administration of either indomethacin (5 mg/kg), aspirin (20 mg/kg), or the vehicle and their mucosal tissue subjected to macroacopic assessment of ulcer healing rate and biochemical measurements. While in the control group the ulcer healed by the tenth day, only a 57.2% reduction in the ulcer crater area was attained in the animals subjected to indomethacin and a 54.8% reduction in ulcer occurred in the presence of aspirin administration. Futhermore, by the tenth day, the delay in healing in the presence of indomethacin was manifested by a 4.9-fold higher rate of apoptosis, a 2.7-fold higher expression of ECE-1 activity, a 3.9-fold higher expression of NOS-2 activity and a 2.2-fold decline in cNOS activity, while the interference in ulcer healing by aspirin was characterized by a 5.6-fold higher rate of apoptosis, a 2.8-fold expressiom of ECE-1 activity, a 3.7-fold higher expression of NOS-2 activity and a 2.3-fold lower expression of cNOS activity. Our findings demonstrate that NSAIDs not only pose a well-known risk of gastrointestinal injury, but also interfere with soft oral tissue repair. The impairment in buccal mucosal ulcer healing by NSAID ingestion is manifested in up-regulation in the expression of ECE-1 responsible for ET-1 generation, suppression in cNOS, and amplification of apoptotic events that delay the healing process.

Animals↗

PubMed2001

Delay in oral mucosal ulcer healing by aspirin is linked to the disturbances in p38 mitogen-activated protein kinase activation.

BACKGROUND: Among the early manifestations of oral mucosal impairment by nonsteroidal anti-inflammatory drugs is the delay in soft oral tissue repair brought about by the amplification of apoptotic events. In this study, we investigated the effect of a specific inhibitor of p38 mitogen-activated protein kinase (p38 MAPK), SB 203580, on the rate of buccal mucosal ulcer healing and the apoptotic processes in rats subjected to intragastric administration of aspirin. METHODS: Groups of rats with experimentally induced buccal mucosal ulcers were administered twice daily for 10 days with SB 203580 (5, 10, and 20 mg/kg) or vehicle followed 30 min later by concomitant administration (twice daily for 10 days) of aspirin at 20 mg/kg. The animals were killed at different periods of treatment and their mucosal tissue subjected to macroscopic assessment of ulcer healing rate, measurement of soluble tumor necrosis factor-alpha (TNF-alpha), and the assay of epithelial cell apoptosis. RESULTS: In the control group the ulcer healed by the tenth day and the rate of healing was not affected by SB 203580 administration, whereas a 54.8% reduction in the ulcer area was attained in the presence of aspirin administration. Moreover, by the tenth day, the delay in ulcer healing caused by aspirin was manifested in a 5.6-fold higher rate of apoptosis and a 5.2-fold higher level of soluble TNF-alpha. Treatment with SB 203580 produced dose-dependent reduction (59.5-74.8%) in aspirin-induced increase in the mucosal level of soluble TNF-alpha, evoked 53.2-69.7% decrease in the rate of epithelial cell apoptosis, and led to a marked reversal (51.8-73.9%) in aspirin-induced delay in ulcer healing. CONCLUSIONS: The results of our findings link the delay in buccal mucosal ulcer healing caused by aspirin ingestion to the disturbances in the p38 MAPK activation.

Animals↗

PubMed2001

Essential components of antimicrobial gastrointestinal epithelial barrier: specific interaction of mucin with an integral apical membrane protein of gastric mucosa.

BACKGROUND: The gastric mucosal protective barrier consists of two essential elements: mucus glycoprotein, mucin, secreted by gastric mucosal cells, and the mucin binding protein (MBP), an integral component of the apical epithelial membrane. The studies described here provide evidence on the structure of MBP, its interaction with mucin, and the susceptibility to phospholipase C (PLC) and Helicobacter pylori protease. MATERIAL AND METHODS: The rat gastric mucosa was used to isolate mucin and the apical epithelial membranes. A buffered saline extract of the mucosal cells was used for the isolation of mucin and the 1% Triton X-100-insoluble gastric apical membranes for the preparation of MBP. RESULTS: The studies on MBP, the mucosal mucin receptor revealed that the protein is anchored in apical membrane through glycosylphosphatidylinositol (GPI). The deamination of MBP with nitrous acid afforded phosphatidylinositols (PIs) and a water soluble, 97 kDa glycosylated protein. The in situ studies with untreated rat gastric mucosa and the mucosa depleted of mucin showed that MBP without mucin was susceptible to the proteolytic degradation with pepsin and H. pylori proteases, but was not released from the apical membrane by the treatment with bacterial PLC. CONCLUSION: The study of carbohydrate ligands for MBP revealed binding of octa- and decasaccharides of gastric mucin. The severe impairment in mucin adhesion to MBP, induced by the diet containing ethanol, supports the conclusion that specific carbohydrate determinants participate in mucin attachment to MBP and epigenetic control of the processes that coordinates its interaction with apical mucosal epithelium in the formation of innate protective barrier.

Animals↗

PubMed2001

Up-regulation of gastric mucosal inflammatory responses to Helicobacter pylori lipopolysaccharide by aspirin but not indomethacin.

Infection with Helicobacter pylori and the use of non-steroidal anti-inflammatory drugs (NSAIDs) are recognized as the two primary factors in the etiology of gastric disease. In this study, we applied the animal model of H. pylori-induced gastritis to assess the influence of NSAIDs on the course of mucosal inflammatory responses to H. pylori. Two days following intragastric application of H. pylori lipopolysaccharide, rats were divided into groups and administered daily for up to 8 days either indomethacin, aspirin or the vehicle, and their gastric mucosal tissue subjected to histological and biochemical assessment. H. pylori lipopolysaccharide elicited within 2 days a pattern of acute mucosal inflammatory responses accompanied by a massive epithelial cell apoptosis, and a marked increase in the expression of membrane-bound and soluble forms of TNF-alpha. The extent of mucosal inflammatory involvement reached a maximum by the 4th day and showed a decline by the 10th day; this was reflected in a 38.1% reduction in apoptosis, a 53.2% decline in membrane-bound TNF-alpha and a 63.8% decrease in soluble TNF-alpha. Compared to the vehicle controls, aspirin caused a 36.2% increase in the severity of the mucosal inflammatory involvement by the second day of administration and a 25.9% increase in the inflammatory involvement occurred by the 8th day; this effect of aspirin was accompanied by a significant (54.5%) induction in apoptosis, a 58.2% decline in membrane-bound TNF-alpha and a 61% increase in soluble TNF-alpha. In contrast, administration of indomethacin evoked only a marginal increase (5-7%) in apoptosis, and caused no discernible changes in the severity of gastric mucosal involvement and the expression of TNF-alpha forms elicited by H. pylori lipopolysaccharide. The findings indicate that aspirin, but not indomethacin, increases the severity of gastric mucosal inflammatory responses to H. pylori. This detrimental influence of aspirin appears to result from up-regulation in the mucosal expression of soluble form of TNF-alpha, which leads to the amplification of apoptotic events that potentiate gastric mucosal inflammatory reaction to H. pylori.

Animals↗