Participation of the intestinal microbiota in the mechanism of beneficial effect of treatment with synbiotic Syngut on experimental colitis under stress conditions.

Gut-brain axis plays a central role in the regulation of stress related diseases such as irritable bowel syndrome (IBS) or inflammatory bowel disease (IBD). It is increasingly recognized that stress modulates gut microbiota community structure and activity and represents an important causal factor in dysbiosis. This study was designed to determine the effect of daily treatment with synbiotic (Syngut) containing inulin, Lactobacillus acidophilus, Bifidobacterium lactis W51, Lactobacillus plantarum W21 and Lactococcus lactis applied i.g. at a dose of 50 mg/kg i.g. on the colonic damage and colonic mucosal blood flow in rats with experimentally induced TNBS-colitis that were additionally exposed or not to acute stress (episodes of cold restraint stress every other day before colitis induction). Control rats received daily treatment with vehicle (saline, i.g.) or mesalazine (50 mg/kg-d i.g.), the standard drug recommended in therapy of IBD. At the termination of TNBS colitis, the histologic evaluation of colonic mucosa, mucosal malonyldialdehyde (MDA) level and plasma concentrations of proinflammatory cytokines (TNF-α, IL-1ß) and adipokine adiponectin were assessed. the samples of colonic mucosa not involving colonic lesions and surrounding the flared mucosa were excised for the determination of mRNA expression for proinflammatory biomarkers TNF-α, IL-1ß, IL-10 and COX-2 as well as antioxidazing factors SOD-1 and SOD-2. Finally, the gut microbial profiles were analyzed by 16S rRNA sequencing at phylum, family and genus level. Episodes of cold stress significantly aggravated the course of TNBS colitis, and significantly increased the release of proinflammatory cytokines as well as the significant increase in the MDA concentration has been observed as compared with non-stressed TNBS rats. These changes were followed by the significant fall in the CBF and plasma adiponectin levels and by the overexpression of mRNA of proinflammatory biomarkers. Synbiotic treatment with Syngut significantly reduced the area of colonic lesions observed macroscopically and microscopically in rats with TNBS colitis with or without exposure to cold stress, significantly increased the CBF, normalized plasma adiponectin levels and significantly attenuated the release and colonic expression of proinflammatory cytokines and biomarkers. the analysis of the gut microbiota showed a significant reduction of microbial diversity (Shannon index) in rats with TNBS colitis with or without exposure to stress. The therapy with Syngut failed to significantly affect the alpha diversity. At the phylum level, the significant rise in Proteobacteria has been observed in stressed rats with TNBS colitis and this effects was attenuated by treatment with Syngut. At family level, TNBS colitis alone or in combination with stress led to a significant decrease of SCFA producing bacterial taxa such as Ruminococaceae and Lachnospiraceae and Syngut counteracted this effect. We conclude that: 1) cold stress exacerbates the gastrointestinal inflammation in experimental colitis; 2) the synbiotic therapy with Syngut ameliorates the gut inflammation in rats with TNBS colitis combined with cold stress; 3) the beneficial effect of Syngut is accompanied by increase of anti-inflammatory taxa such as Ruminococaceae and Lachnospiraceae, and 4) the modulation of gut microbiota with Syngut alleviates stress-related intestinal inflammation suggesting a potential usefulness of synbiotic therapy in intestinal disorders accompanied by stress in patients with IBD.

Involvement of epithelial-mesenchymal transition-inducing transcription factors in the mechanism of Helicobacter pylori-induced fibroblasts activation.

Gastric cancer (GC) originating from the lining of the stomach is one of the most frequent malignancies in humans. The most efficient method giving hope of full recovery from GC is gastric resection combined with adjuvant chemotherapy and radiotherapy. However, over 50% of patients after treatment suffer from recurrence and peritoneal metastasis. The bacteria Helicobacter pylori (Hp) is nowadays considered as the major pathogen capable of colonizing gastric mucosa. This bug causes deregulation of multiple signaling pathways including the activation of nuclear factor kappaB (NFκB) and Janus kinase/signal transducers and activators of transcription (JAK/STAT) responsible for inflammation and development of carcinogenic cascade. The pathomechanism of these changes remains little understood, but the Hp virulence factors affecting mainly gastric epithelium have been postulated. Nevertheless, the changes associated with inflammation progressing to cancer are not only limited to epithelial cells. The cells surrounding the tumor, mainly activated fibroblasts (CAFs - cancer-associated fibroblasts) create molecular microenvironment promoting tumorigenesis and cancer invasion. The downstream targets of STAT3, epithelial-mesenchymal transition-inducing transcription factors (EMT-TFs) are expressed in activated fibroblasts providing them with additional properties. Thus, our aim was to determine if the Hp strain expressing CagA and VacA cytotoxins may result in the activation/differentiation of rat gastric fibroblasts resulting in NFκB and STAT3 signaling, which could lead to EMT-TFs expression and secretome responsible for inflammatory and EMT inducing microenvironment. In this study, gastric samples were harvested from 8-week-old Spraque-Dowley rats and the primary and secondary fibroblast cultures were established. The 70% confluent secondary fibroblast cultures were infected with 1 x 109 of live Hp expressing cytotoxins CagA VacA per dish and incubated in humidified atmosphere for 3, 24, 48 and 72 hours, before the conditioned media or the cells were used for endpoint experiments. As the control, fibroblast culture in DMEM with 10% FBS and antibiotics, free from Hp infection was used. The expression of mRNA for 18S (control), toll-like receptors: TLR2 and TLR4, STAT3, NFκB p65/Rel A, inhibitor of NF-κB (Iκß), Snail and Twist was determined by RT-PCR. The protein expression of Snail and Twist was assessed by Western blot technique. The fibroblast supernatant was collected at 72 hours from non-infected and Hp (cagA+ vacA+)-infected culture and the concentrations of interleukin 8 (IL-8), hepatocyte growth factor (HGF) and stromal derived factor-1 (SDF-1) were measured by ELISA. In fibroblasts infected with Hp (cagA+ vacA+), the significant increase of mRNA expression for both, TLR2 and TLR4, as well as STAT3, NFκB/RelA subunit was observed already after 3 hours of fibroblasts infection with Hp strain compared with control non-infected fibroblasts. Simultaneously, the significant decrease of Iκß mRNA has been noticed starting from 48 hours after the Hp infection of fibroblasts was carried out. The strong increase in the expression of Snail1 and Twist mRNA was recorded already at 3 hours in Hp-infected fibroblasts comparing to control non-infected fibroblasts and this increase persisted at 24 and 48 hours being the most pronounced at 72 hours post incubation with Hp. The expression of Snail1 protein was observed after 3 hours post Hp infection and this increase persisted throughout entire time periods upon Hp infection. In contrast, no detectable level of Twist protein expression was observed up to 72 hours post-infection neither in control conditions nor in fibroblasts co-infected with Hp. These changes in fibroblasts were accompanied by a significant increase in the release of HGF, SDF-1 and IL-8 determined in cell supernatants collected from Hp-infected fibroblasts. These data indicate that the activation/differentiation of rat gastric fibroblasts can occur directly by Hp releasing CagA and indirectly through TLR2 and TLR4 and these effects can be mediated by transcription factors NFκB and STAT3 signaling leading to rapid Snail1 protein expression. We conclude that NFκB and STAT3 signaling together with Snail1 protein expression may activate the secretome responsible for fibroblasts inflammatory and EMT-inducing microenvironment likely serving as prerequisite for GC development.

Esophagoprotective activity of angiotensin-(1-7) in experimental model of acute reflux esophagitis. Evidence for the role of nitric oxide, sensory nerves, hypoxia-inducible factor-1alpha and proinflammatory cytokines.

Gastroesophageal reflux disease (GERD) is a global disease rapidly increasing among world population. The pathogenesis of reflux esophagitis which is considered as the early stage of GERD is complex, resulting from an imbalance between aggressive factors damaging the esophagus and a number of the natural defense mechanisms. The esophageal mucosa is in a state of continuous exposure to potentially damaging endogenous and exogenous factors. Important aggressive components of gastric refluxate include acid and pepsin and also pancreatic enzymes and bile. Among aggressive factors of exogenous origin, cigarette smoking, non-steroidal anti-inflammatory drugs (NSAID), and steroids are of the utmost importance. The basic level of esophageal defense against acid-pepsin damage consists of the anti-reflux mechanisms such as the luminal acid clearance and removal of the esophageal contents and neutralization of luminal acidity. In addition the esophageal mucosal protection includes the presence of pre-epithelial, epithelial and post-epithelial cellular and functional components. Recently, the progress have been made in the understanding of role of the heptapeptide member of the renin-angiotensin system (RAS), angiotensin-(1-7) (Ang-(1-7)) in the control of gastrointestinal functions. It has been shown that all components of local RAS including Ang-(1-7) are detectable in the gastrointestinal wall including not only the stomach but also the esophagus. Previous studies revealed that Ang-(1-7), which is an important component of the RAS, exerts vasodilatory, anti-inflammatory and antioxidant activities in the stomach. Ang-(1-7) was recently implicated in gastroprotection, but its effects on esophageal mucosa in a rodent model of reflux esophagitis and in human subjects presenting GERD symptoms have not been explored. The present study was aimed to evaluate the possible protective effects of Ang-(1-7) and Mas-receptors upon esophageal mucosal damage in acute reflux esophagitis (RE) induced in anesthetized rats by ligating the pylorus and the limiting ridge (a transitional region between the forestomach and the corpus of stomach). Consequently, the total gastric reservoir to store gastric juice was greatly diminished, resulting in the reflux of this juice into the esophagus. Because Mas receptors are functionally linked to nitric oxide (NO) formation, we also studied involvement of endogenous NO in the mediation of protective and circulatory effects of exogenous Ang-(1-7). Moreover, an attempt was made to assess the possible role of sensory neurons in the modulation of the protective effects exerted by Ang-(1-7)/Mas receptor system. Six series of rats were pretreated 30 min before induction of RE with 1) vehicle (saline), 2) Ang-(1-7) (5-50 µg/kg i.p.), 3) A779 (50 µg/kg i.p.), the selective Mas receptor antagonist applied alone, 4) Ang-(1-7) (50 µg/kg i.p.) combined with A779, 5) L-NNA (20 mg/kg i.p.) administered alone, and 6) Ang-(1-7) (50 µg/kg i.p.) combined with L-NNA. In separate group of rats, capsaicin (total dosage of 125 mg/kg within three days) was administered s.c. 2 weeks before the induction of RE to induce functional ablation of sensory nerves. Rats with intact sensory nerves and those with capsaicin-induced sensory denervation received vehicle (saline) or Ang-(1-7) (50 µg/kg i.p.) to determine whether this vasoactive metabolite of angiotensin I could be also effective in rats with capsaicin-induced impairment of the synthesis and release of sensory neuropeptides such as CGRP. Four hours after induction of RE, the mucosal damage was graded with mucosal lesion index (LI) from 0 to 6, the esophageal microcirculatory blood flow (EBF) was determined by H2-gas clearance technique and plasma level of pro-inflammatory cytokines interleukin-1b (IL-1ß), and tumor necrosis factor-α (TNF-α) was determined by ELISA. The expression of proinflammatory factors including COX-2, cytokine IL-1ß and hypoxia inducible factor 1alpha (Hif1α) was analyzed in the esophageal mucosal biopsies. In rats with RE, the esophageal LI was significantly elevated comparing its value observed in intact rats, and the EBF was significantly decreased as compared with intact mucosa. Pretreatment with Ang-(1-7) of control rats without esophagitis induced increase in EBF by about 25% without any macroscopic changes in the esophageal mucosa or in the plasma level of cytokines. In animals with RE, pretreatment with Ang-(1-7) significantly reduced gross and histological esophageal mucosal injury and significantly increased EBF in comparison to vehicle-pretreated animals. The observed gross and histologic esophagoprotective effect of Ang-(1-7) was totally abolished by A779 so in rats with combined treatment of A779 with Ang-(1-7), the LI was identical with this observed in control RE and the EBF was decreased in these animals by about 39%. Inhibition of NO synthase by L-NNA significantly reduced the LI and the rise in EBF caused by Ang-(1-7). Similarly, the capsaicin denervation also significantly attenuated the vasodilatory and the esophagoprotective effects of Ang-(1-7). The expression of proinflammatory factors COX-2, Hif1α and IL-1ß which was negligible in intact esophageal mucosa, was upregulated in esophageal mucosa of rats with RE. In contrast, the administration of Ang-(1-7) resulted in a downregulation of mRNA for COX-2, Hif1 and IL-1ß in esophageal mucosa an this effect was abolished in A779-dependent manner. The Ang-(1-7) significantly decreased the RE-induced elevation of plasma levels of IL-1ß and TNF-α, and this effect was also reversed by pretreatment with A779, and significantly attenuated by pretreatment with L-NNA and capsaicin-induced sensory denervation. The present study indicates that the protective effect of Ang-(1-7) observed in the esophageal mucosa during early acute stage of gastroesophageal reflux depends upon the enhancement of esophageal microcirculatory blood flow via the activation of Mas receptor possibly due to NO synthase/NO system activation, stimulation of sensory nerves, the inhibition of expression of pro-inflammatory factors including COX-2, Hif1α and IL-1ß and release of proinflammatory cytokines IL-1ß and TNF-α.

Molecular alterations in fibroblasts exposed to Helicobacter pylori: a missing link in bacterial inflammation progressing into gastric carcinogenesis?

Major human pathogen Helicobacter pylori (Hp) can colonize the gastric mucosa causing inflammation and being of potential risk for gastric cancer development but the contribution of fibroblasts to the pathogenesis of Hp in the stomach has been little studied. Normal stroma contains few fibroblasts, especially myofibroblasts, but their number rapidly increases in the reactive stroma surrounding inflammatory region and neoplastic tissue. We determined the effect of coincubation of cultured rat gastric fibroblasts with alive Hp on the transdifferentiation of fibroblasts into myofibroblasts associated with Hp-induced inflammation and neoplasia. Gastric mucosal samples were harvested from 8-week-old Spraque-Dowley rats and cultured to obtain the sub-confluent fibroblasts. The isolated fibroblasts were infected with 1 x 10(9) of live Hp (ATCC 700824, cagA+, vacA+) per dish and incubated in humidified atmosphere for 3, 24 and 48 hours. At respective times, fibroblasts were harvested and the expression of mRNA for α-smooth muscle actin (SMA), hypoxia inducible factor (HIF)-1α, collagen I, heat shock protein (HSP)-70, heme oxygenase (HO)-1, Bax and Ki67 transcripts was determined by RT-PCR with specific primers. Hp increased the transdifferentiation of fibroblasts into myofibroblasts as reflected by the time-dependent overexpression of mRNA for α-SMA. The increased expression of HIF-1α and collagen I was observed in fibroblasts co-cultured with Hp. The expression of HSP70 which was negligible in isolated fibroblasts incubated with vehicle (saline) showed time-dependent 2-3 fold increase in those incubated with Hp. The HO-1 mRNA was strongly expressed in rat gastric fibroblasts without or with the co-incubation with Hp. The mRNA for Bax was progressively downregulated within the time of incubation while no significant changes in expression of proliferation marker Ki67 were recorded. We conclude that Hp-induced transdifferentiation of fibroblasts into myofibroblasts involves an increased expression of the early carcinogenic marker HIF-1α, and inhibition of proapoptotic Bax expression, and 2) the overexpression of HSP70 and the unchanged expression HO-1 and Ki67 probably represent the enhanced protective activity of Hp-infected fibroblasts to maintain their own integrity under inflammatory action of this bacteria and its cytotoxins.

Expression and release of leptin and proinflammatory cytokines in patients with ulcerative colitis and infectious diarrhea.

Leptin plays not only an important role in regulation of food intake, but also in the mechanism of inflammation. The universal presence of leptin in the cells of immune system and its secretion by these cells caused increasing interest in the role of this hormone in ulcerative colitis (UC). We determined the role of leptin in 80 patients, aged from 18 to 69 years, including 50 patients with active UC and 30 patients with infectious diarrhea. The tests were performed within 48 hours of the first symptoms, in the period of remission of UC and 8 weeks after resolution of infectious diarrhea. Endoscopy was performed in each patient, and the biopsy samples were taken for the assessments of expression of mRNA for leptin, IL-1ß, IL-6 and TNF-α by RT-PCR and Western blot. Blood tests included concentrations of leptin, IL-1ß, IL-6 and TNF-α. In addition, the plasma levels of leptin, IL-1ß, IL-6 and TNF-α were assessed by ELISA. Serum concentrations of leptin was significantly increased in patients with exacerbation of UC over that in patients with UC in remission. The serum leptin concentration was significantly higher in patients with infectious diarrhea, than the patients that recovered from infectious diarrhea. The leptin protein was overexpressed in the biopsy samples of the mucosa of large intestine compared to those with exacerbation of UC, and in patients after successful recovery from infectious diarrhea. The leptin mRNA was overexpressed in patients with infectious diarrhea compared with that in the group of patients after successful recovery from this condition. Serum concentrations of leptin failed to correlate with severity of exacerbation of UC and with extent of intestinal inflammatory lesions in patients with UC. However, the correlation was observed between serum concentrations of leptin in patients with exacerbation of UC and serum concentrations of proinflammatory cytokines IL-1ß and TNF-α. We conclude that 1) the increased leptin in exacerbated UC is related to the increased serum proinflammatory cytokines IL-1ß, TNF-α and IL-6 levels; 2) In patients with infectious diarrhea, the concentrations of leptin in intestinal mucosa correlates with serum concentrations of cytokines IL-1ß, IL-6 and TNF-α and with an increased expression of leptin mRNA in intestinal mucosa but not with alterations in serum levels of this hormone; 3) leptin may serve as useful predictive marker of inflammation in inflammatory bowel disease (IBD).

Asymmetric dimethylarginine, an endogenous inhibitor of nitric oxide synthase, interacts with gastric oxidative metabolism and enhances stress-induced gastric lesions.

Asymmetric dimethylarginine (ADMA) is an endogenous competitive inhibitor of nitric oxide (NO) synthase known to exert vasoconstriction of vascular bed. The elevation of ADMA has been considered as the cardiovascular risk factor associated with hyperlipidemia, hypercholesterolemia and metabolic syndrome. ADMA is produced by the action of dimethylarginine dimethylaminohydrolase (DDAH), which hydrolyzes ADMA to L-citrulline and dimethylamine. Previous studies have shown that endogenous NO plays an important role in the mechanism of gastric mucosal defense, but the role of ADMA in the pathogenesis of serious clinical entity, such as the acute gastric mucosal injury induced by stress has been little studied. In present study, we determined the effect of intragastric (i.g.) pretreatment with ADMA applied in graded doses ranging from 0.1 up to 20 mg/kg on gastric mucosal lesions induced by 3.5 h of water immersion and restraint stress (WRS). The number of gastric lesions was determined by planimetry and the gastric blood flow (GBF) was assessed by laser Doppler technique. The malondialdehyde and 4-hydroxynonenal (MDA+4-HNE) concentration, as an index of oxygen radical-lipid peroxidation was assessed in the gastric mucosa in rats exposed to WRS with or without ADMA administration. Proinflammatory cytokines IL-1ß, TNF-α, superoxide dismutase (SOD) and glutathione peroxidase (GPx) mRNAs in the gastric mucosa and plasma levels of ADMA, IL-1ß and TNF-α were analyzed by RT-PCR and ELISA, respectively. The exposure of rats to WRS for 3.5 h produced acute gastric lesions accompanied by a significant rise in the plasma ADMA levels and a significant fall in the GBF, an increase in MDA+4-HNE concentrations and the significant increase in the expression and release of IL-1ß and TNF-α. The pretreatment with ADMA, applied i.g. 30 min before WRS dose-dependently, aggravated WRS damage and this effect was accompanied by a further significant fall in the GBF. The ADMA induced exacerbation of WRS lesions and the accompanying rise in the plasma ADMA levels and the fall in GBF were significantly attenuated by concurrent treatment with glyceryl trinitrate (GTN) (10 mg/kg i.g.) in the presence of ADMA. Administration of ADMA resulted in a significant decrease in the expression of SOD and GPx mRNAs and the up-regulation of mRNA for IL-1ß and TNF-α followed by an increase in these plasma cytokine levels as compared to respective values observed in vehicle-pretreated animals. We conclude that 1) ADMA could be implicated in the mechanism of WRS-induced ulcerogenesis, 2) ADMA exacerbates WRS-induced gastric lesions due to enhancement in neutrophil dependent lipid peroxidation and overexpression and release of proinflammatory cytokines IL-1ß and TNF-α and a potent depletion of antioxidative enzymes SOD and GPx expression and activity.

Novel concept in the mechanism of injury and protection of gastric mucosa: role of renin-angiotensin system and active metabolites of angiotensin.

The term cytoprotection pioneered by Robert and colleagues has been introduced to describe the remarkable ability of endogenous and exogenous prostaglandins (PGs) to prevent acute gastric hemorrhagic lesions induced by noxious stimuli such as ethanol, bile acids, hiperosmolar solutions and nonsteroidal anti-inflammatory agents such as aspirin. Since that time many factors were implicated to possess gastroprotective properties such as growth factors including epidermal growth factor (EGF) and transforming factor alpha (TGFα), vasodilatory mediators such as nitric oxide (NO) and calcitonin gene related peptide (CGRP) as well as appetite gut hormones including gastrin and cholecystokinin (CCK), leptin and recently ghrelin. This protective action of gut peptides has been attributed to the release of PG but question remains whether another peptide angiotensin, the classic component of the systemic and local renin-angiotensin system (RAS) could be involved in the mechanism of gastric integrity and gastroprotection. After renin stimulation, the circulating angiotensin I is converted to angiotensin II (ANG II) by the activity of the Angiotensin Converting Enzyme (ACE). The ANG II acting via its binding to two major receptor subtypes the ANG type 1 (AT1) and type 2 (AT2) has been shown be activated during stress and to contribute to the pathogenesis of cold stress- and ischemia-reperfusion-induced gastric lesions. All bioactive angiotensin peptides can be generated not only in systemic circulation, but also locally in several tissues and organs. Recently the new functional components of RAS, such as Ang-(1-7), Ang IV, Ang-(1-12) and novel pathways ACE2 have been described suggesting the gastroprotective role for the novel ANG II metabolite, Ang-(1-7). The fact that Ang-(1-7) is produced in excessive amounts in the gastric mucosa of rodents and that pretreatment by Ang-(1-7) exhibits a potent gastroprotective activity against the gastric lesions induced by cold-restraint stress suggests that this and possibly other vasoactive metabolites of ANG II pathway could be involved in the mechanism of gastric integrity and gastroprotection. This review summarizes the novel gastroprotective factors and mechanisms associated with metabolic fate of systemic and local RAS activation with major focus to recent advancement in the angiotensin pathways in the gut integrity.

Antibiotic treatment with ampicillin accelerates the healing of colonic damage impaired by aspirin and coxib in the experimental colitis. Importance of intestinal bacteria, colonic microcirculation and proinflammatory cytokines.

Non-steroidal anti-inflammatory drugs (NSAIDs) are widely used for their anti-inflammatory, analgesic and antipyretic effects, however their use is associated with the broad spectrum of side effects observed in human as well as the experimental animals. Despite damaging activity of NSAIDs in upper gastrointestinal (GI) tract, these drugs exert deleterious influence in lower GI tract, including colon. The role of GI microflora in the pathogenesis of NSAIDs-induced experimental colonic damage is not completely understood. The aim of this study was 1) to evaluate the relative importance of the GI microflora on the experimental colonic damage in the presence of caused by NSAID, and 2) to assess the efficacy of antibiotic treatment with ampicillin on the process of healing of colitis. We compared the effect of vehicle, ASA applied 40 mg/kg intragastrically (i.g.) or the selective cyclooxygenase (COX)-2 inhibitor, celecoxib (25 mg/kg i.g.) without or with ampicillin treatment (800 mg/kg i.g.) administered throughout the period of 10 days, on the intensity of TNBS-induced colitis in rats. The severity of colonic damage, the alterations in the colonic blood flow (CBF) and myeloperoxidase (MPO) activity, the mucosal expression of TNF-α, IL-1ß, COX-2, VEGF and iNOS and the plasma concentration of TNF-α and IL-1ß were assessed. In all rats, the faeces samples as well as those from the colonic mucosa, blood, liver and spleen underwent microbiological evaluation for intestinal bacterial species including Escherichia coli and Enterococcus spp. The administration of TNBS resulted in macroscopic and microscopic lesions accompanied by the significant fall in the CBF, an increase in tissue weight and 4-5-fold rise in the MPO activity and a significant increase in the plasma IL-1ß and TNF-α levels. ASA or celecoxib significantly increased the area of colonic lesions, enhanced MPO activity and caused the marked increase in colonic tissue weight and plasma IL-1ß and TNF-α levels, as well as an overexpression of mRNA for IL-1ß and TNF-α, COX-2, VEGF and iNOS in the colonic tissue. ASA and coxib also resulted also in a significant increase of E. coli counts in the stool at day 3 and day 10 day of the observation compared with the intact rats. Moreover, E. coli translocation from the colon to the blood and extraintestinal organs such as liver and spleen in the group of rats treated without or with ASA and coxib. E. coli was the most common bacteria isolated from these organs. Treatment with ampicillin significantly attenuated the ASA- or celecoxib-induced increase in plasma levels of IL-1ß and TNF-α and suppressed the mucosal mRNA expression for IL-1ß and TNF-ß, COX-2, iNOS and VEGF in the colonic mucosa. Ampicillin administration caused a significant fall in the number of E. coli in the faeces at day 3 and day 10 of observation in ASA- and coxib-treated rats with colitis. Antibiotic therapy markedly reduced bacterial translocation to the colonic tissue and the extraintestinal organs such as the liver and spleen. We conclude that administration of ASA and to lesser extent of celecoxib, delays the healing of experimental colitis and enhances the alterations in colonic blood flow, proinflammatory markers such as IL-1ß, TNF-α, COX-2, iNOS and VEGF and increased intestinal mucosal permeability resulting in the intestinal bacterial translocation to the blood, spleen and liver. Antibiotic treatment with ampicillin is effective in the diminishing of the severity of colonic damage, counteracts both the NSAID-induced fall in colonic microcirculation and bacterial E.coli translocation to the extraintestinal organs.

Transcriptional upregulation of gastrin in response to peroxisome proliferator-activated receptor gamma agonist triggers cell survival pathways.

Peroxisome proliferator-activated receptor gamma (PPAR gamma) are members of the largest nuclear hormone receptor family of transcription factors (1). PPAR gamma (PPARgamma) plays an important role in adipogenesis, control of sensitivity to insulin, inflammation and atherosclerosis but recent studies also suggest that PPARgamma is involved in cell cycle withdrawal. PPARgamma can promote cell differentiation, exert an antiproliferative action and inhibit angiogenesis (2, 3). However, there are studies showing that activation of PPARgamma promotes the development of colon cancer (4). These data are in sharp contrast with studies that attribute anticancer effects to PPARgamma in gastrointestinal malignancies. Probably, the action of PPARgamma on cell cycle and proliferation depends on the cell type and presence of other stimuli that predispose cells to cancer development. Amidated and non-amidated gastrins may play an important role in the proliferation and carcinogenesis of GI cancers. It is known that gastrin peptides activate phosphorylation of Protein Kinase B (PKB/Akt) and anti-apoptotic signalling but there is little known about the link between gastrins and PPARgamma receptors in relation to apoptosis.