Pepsin Inhibitors Prevent Inflammation and Loss of Laryngeal Barrier Function in Mice with Gastroesophageal Reflux.

OBJECTIVE: This study aimed to evaluate the role of pepsin inhibitors in the inflammatory response and their effects on laryngeal mucosal integrity during gastroesophageal reflux (GERD) under in vivo conditions. METHODS: A surgical model of GERD was used, in which mice were treated with pepstatin (0.3 mg/kg) or darunavir (8.6 mg/kg) for 3 days. On the third day after the experimental protocol, the laryngeal samples were collected to assess the severity of inflammation (wet weight and myeloperoxidase activity) and mucosal integrity (transepithelial electrical resistance and paracellular epithelial permeability to fluorescein). RESULTS: The surgical GERD model was reproduced. It showed features of inflammation and loss of barrier function in the laryngeal mucosa. Pepstatin and darunavir administration suppressed laryngeal inflammation and preserved laryngeal mucosal integrity. CONCLUSION: Pepsin inhibition by the administration of pepstatin and darunavir improved inflammation and protected the laryngeal mucosa in a mouse experimental model of GERD. LEVEL OF EVIDENCE: NA Laryngoscope, 134:3080-3085, 2024.

P2X7 receptor blockade decreases inflammation, apoptosis, and enteric neuron loss during Clostridioides difficile toxin A-induced ileitis in mice.

BACKGROUND: Clostridioides difficile (C. difficile) is the most common pathogen causing health care-associated infections. C. difficile TcdA and TcdB have been shown to activate enteric neurons; however, what population of these cells is more profoundly influenced and the mechanism underlying these effects remain unknown. AIM: To characterize a specific population of TcdA-affected myenteric neurons and investigate the role of the P2X7 receptor in TcdA-induced ileal inflammation, cell death, and the changes in the enteric nervous system in mice. METHODS: Swiss mice were used to model TcdA-induced ileitis in ileal loops exposed to TcdA (50 µg/Loop) for 4 h. To investigate the role of the P2X7 receptor, Brilliant Blue G (50 mg/kg, i.p.), which is a nonspecific P2X7 receptor antagonist, or A438079 (0.7 µg/mouse, i.p.), which is a competitive P2X7 receptor antagonist, were injected one hour prior to TcdA challenge. Ileal samples were collected to analyze the expression of the P2X7 receptor (by quantitative real-time polymerase chain reaction and immunohistochemistry), the population of myenteric enteric neurons (immunofluorescence), histological damage, intestinal inflammation, cell death (terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labeling), neuronal loss, and S100B synthesis (immunohistochemistry). RESULTS: TcdA upregulated (P < 0.05) the expression of the P2X7 receptor gene in the ileal tissues, increasing the level of this receptor in myenteric neurons compared to that in control mice. Comparison with the control mice indicated that TcdA promoted (P < 0.05) the loss of myenteric calretinin+ (Calr) and choline acetyltransferase+ neurons and increased the number of nitrergic+ and Calr+ neurons expressing the P2X7 receptor. Blockade of the P2X7 receptor decreased TcdA-induced intestinal damage, cytokine release [interleukin (IL)-1ß, IL-6, IL-8, and tumor necrosis factor-α], cell death, enteric neuron loss, and S100B synthesis in the mouse ileum. CONCLUSION: Our findings demonstrated that TcdA induced the upregulation of the P2X7 receptor, which promoted enteric neuron loss, S100B synthesis, tissue damage, inflammation, and cell death in the mouse ileum. These findings contribute to the future directions in understanding the mechanism involved in intestinal dysfunction reported in patients after C. difficile infection.

Bifidobacterium longum subsp. longum 51A attenuates intestinal injury against irinotecan-induced mucositis in mice.

Intestinal mucositis (IM) is a critical side-effect associated with antineoplastic therapy. Treatment available is only palliative and often not effective. However, alternative therapeutic strategies, such as probiotics, have attracted significant attention due to their immune-modulatory action in several diseases. Thus, the present study aims to elucidate the therapeutic potential of the probiotic strain Bifidobacterium longum 51A in a murine model of mucositis induced by irinotecan. Due to the scarcity of studies on dose-response and viability (probiotic vs paraprobiotic), we first evaluated which dose and cell viability would be most effective in treating mucositis. In this study, the oral pretreatment with viable B. longum 51A at a concentration of 1 × 109 CFU/mL reduced the daily disease activity index (p < 0.01), protected the intestinal architecture, preserved the length of the intestine (p < 0.05), and reduced intestinal permeability (p < 0.01), inflammation, and oxidative damage (p < 0.01) induced by irinotecan. Also, treatment with B. longum 51A increased the production of secretory immunoglobulin A (p < 0.05) in the intestinal fluid of mice with mucositis. Furthermore, B. longum 51A reversed the mucositis-induced increase in Enterobacteriaceae bacterial group in the gut (p < 0.01). In conclusion, these results showed that oral administration of B. longum 51A protects mice against intestinal damage caused by irinotecan, suggesting its use as a potential probiotic in therapy during mucositis.

Phosphatidylinositol 3-kinase gamma participates in nimesulide-induced hepatic damage.

OBJECTIVE: To evaluate the participation of the phosphatidylinositol 3-kinase pathway in the liver damage caused by nimesulide. METHODS: Liver damage been induced by nimesulide. Mice were treated with either 2% dimethyl sulfoxide or AS605240, a phosphatidylinositol 3-kinase gamma pathway antagonist. Blood samples were collected for function assays of liver. The liver was removed for analysis of liver weight/animal weight ratio, histopathological parameters, oxidative and nitrous stress, cytokine levels, and the immunostaining for cyclooxygenase 2 and nuclear factor kappa B. KEY FINDINGS: Liver injured by nimesulide and treated with phosphatidylinositol 3-kinase gamma inhibitor significantly reversed (P < 0.05) the damage; it decreased the liver weight/animal weight ratio, histopathological scores, and neutrophil infiltration, consequently reducing oxidative stress. In addition, we show that phosphatidylinositol 3-kinase gamma is associated with hepatic damage induced by nimesulide, because it altered liver function and increased the protein immunostaining of cyclooxygenase 2 and nuclear factor kappa B in the liver tissue of nimesulide-treated animals. CONCLUSIONS: The findings from the present study allows us to infer that nimesulide causes liver damage through the phosphatidylinositol 3-kinase gamma pathway.

The Alpha-Lipoic Acid Improves Survival and Prevents Irinotecan-Induced Inflammation and Intestinal Dysmotility in Mice.

Irinotecan, an anticancer drug, induces diarrhea and intestinal inflammation, resulting in an increase in the cost of care and in treatment delays. In this study, we investigated whether alpha-lipoic acid (α-LA) could improve irinotecan-mediated intestinal inflammation, diarrhea and dysmotility. Intestinal mucositis was induced by irinotecan injection (75 mg/kg, i.p., for 4 days) in Swiss mice. α-LA (50, 100 or 200 mg/kg, gavage) was administered daily 1 h before the injection of irinotecan. Duodenum tissues were obtained for inflammation and proliferation analysis. The outcomes: diarrhea, intestinal dysmotility, weight body loss and survival were evaluated. Compared with the control condition, irinotecan diminished (p < 0.05) intestinal villus height, caused a loss of crypt integrity and intense inflammatory cell infiltration, increased myeloperoxidase (MPO), IL-6 and IL-1ß levels and decreased reduced glutathione (GSH) levels in duodenum segments and increased gastric retention and decreased liquid retention in the medial intestinal segment, resulting in increased intestinal transit, severe diarrhea and reduced survival (approximately 72%). Furthermore, α-LA (200 mg/kg) pretreatment ameliorated (p < 0.05) these irinotecan-induced effects. Our findings show that α-LA reduced irinotecan-induced inflammation, intestinal dysmotility and diarrhea, resulting in improved survival. α-LA may be a useful therapeutic agent for the treatment of gut dysmotility in patients with intestinal mucositis associated with irinotecan treatment.

Modulation of 5-fluorouracil activation of toll-like/MyD88/NF-κB/MAPK pathway by Saccharomyces boulardii CNCM I-745 probiotic.

BACKGROUND AND AIM: Chemotherapy drugs that act via Toll-like receptors (TLRs) can exacerbate mucosal injury through the production of cytokines. Intestinal mucositis can activate TLR2 and TLR4, resulting in the activation of NF-κB. Intestinal mucositis characterized by intense inflammation is the main side effect associated with 5-fluorouracil (5-FU) treatment. Saccharomyces boulardii CNCM I-745 (S.b) is a probiotic yeast used in the treatment of gastrointestinal disorders. The main objective of the study was to evaluate the effect of S.b treatment on the Toll-like/MyD88/NF-κB/MAPK pathway activated during intestinal mucositis and in Caco-2 cells treated with 5-FU. METHODS: The mice were divided into three groups: saline (control), saline + 5-FU, and 5-FU + S.b (1.6 × 1010 colony forming units/kg). After 3 days of S.b administration by gavage, the mice were euthanized and the jejunum and ileum were removed. In vitro, Caco2 cells were treated with 5-FU (1 mM) alone or in the presence of lipopolysaccharide (1 ng/ml). When indicated, cells were exposed to S.b. The jejunum/ileum samples and Caco2 cells were examined for the expression or concentration of the inflammatory components. RESULTS: Treatment with S.b modulated the expressions of TLR2, TLR4, MyD88, NF-κB, ERK1/2, phospho-p38, phospho-JNK, TNF-α, IL-1ß, and CXCL-1 in the jejunum/ileum and Caco2 cells following treatment with 5-FU. CONCLUSION: Toll-like/MyD88/NF-κB/MAPK pathway are activated during intestinal mucositis and their modulation by S.b suggests a novel and valuable therapeutic strategy for intestinal inflammation.

Cashew gum, a biopolymer, topically protects oesophageal mucosa in non erosive reflux disease: A promising translational study.

This study aimed to investigate a standardized biopolymer, cashew gum (CG), in human oesophageal mucosa and mice with experimentally-induced non-erosive reflux disease (NERD). Human oesophageal biopsies from NERD patients were collected to evaluate the mucosal protection of CG through transepithelial electrical resistance (TER), mucosal permeability, and mucoadhesiveness tests. A surgical model of NERD in mice was induced, and barrier functions followed by suggestive oesophageal inflammatory hallmarks were evaluated. Pre-coating of CG was effective in human oesophageal mucosa by attenuating drop of TER and mucosal permeability. Labelled-CG adheres to human oesophageal mucosa for up to 1 h. In animal studies, CG improved parameters of barrier function (TER and mucosal permeability) in distal oesophagus mucosa. CG also promoted sequential support by reducing inflammatory hallmarks of oesophageal damage. CG confers topical oesophageal mucosal protection due to its mucoadhesiveness and anti-inflammatory profile. Long-duration mucoprotective products can be further explored as first-line/adjuvant NERD therapy.

Topical protection of mice laryngeal mucosa using the natural product cashew gum.

OBJECTIVES/HYPOTHESIS: Evaluate the effect of in vitro exposure of mice laryngeal mucosa to solutions that simulated human gastric juice and to assess the topical protective effect of cashew gum on mice laryngeal mucosal integrity in vitro. STUDY DESIGN: Animal study. METHODS: Murine (Swiss) laryngeal samples were mounted in Ussing chambers. The luminal side of biopsies was exposed to solutions of different acidity with or without pepsin and/or taurodeoxycholic acid (TDC). Transepithelial electrical resistance (TER) was continuously recorded. The topical protective effect of cashew gum solution was evaluated by precoating the biopsies before the exposure with a solution at pH 5 containing 5 mM TDC. Changes in TER and mucosal permeability to fluorescein were measured. RESULTS: Exposure of laryngeal mucosa to acidic solutions containing pepsin and TDC provoked a pH-dependent drop in TER with the maximal effect at pH 1, but still present at pH 5 (weakly acidic). The exposure of the laryngeal mucosa to a solution of pH 5 with TDC, but not with pepsin, produced a dose-dependent decrease in TER. Precoating the mucosa with cashew gum prevented the reduction of TER and increased transepithelial permeability by exposure to a solution at pH5 containing TDC. CONCLUSIONS: Weakly acidic solutions containing bile acids can produce impairment of laryngeal epithelial barrier, which may be protected by topical treatment with cashew gum. LEVEL OF EVIDENCE: NA. Laryngoscope, 128:1157-1162, 2018.

Morinda citrifolia lipid transfer protein 1 exhibits anti-inflammatory activity by modulation of pro- and anti-inflammatory cytokines.

Previous reports have demonstrated that a thermostable lipid transfer protein isolated from noni seeds (McLTP1; 9.4kDa) displays anti-nociceptive and anti-inflammatory activities. This work aimed to investigate the underlying mechanisms of the anti-inflammatory activity of McLTP1 in mice. The protein was solubilised in sterile saline (0.9% NaCl) immediately before the treatment of mice by oral or intraperitoneal routes at doses of 8mg/kg. Given orally or intraperitoneally, McLTP1 significantly inhibited (p<0.05) cell migration in experimental models of carrageenan-induced peritonitis and the formation of paw oedema induced by carrageenan and dextran. Additionally, McLTP1 demonstrated the ability to significantly inhibit the production of the cytokines IL-1ß, IL-6, and TNF-α (p<0.05) and to promote an increase in the production of the anti-inflammatory cytokine IL-10. The treatment of mice with McLTP1 by the oral or i.p route reduced pancreatic injury and activities of amylase, lipase, and pancreatitis-associated lung injury. This study suggested that the observed anti-inflammatory effects of McLTP1 can be related to modulation of pro- and anti-inflammatory cytokine levels.

A novel murine model of esophageal nonerosive reflux disease: from inflammation to impairment in mucosal integrity.

Nonerosive reflux disease (NERD) is a highly prevalent phenotype of the gastroesophageal reflux disease. In this study, we developed a novel murine model of NERD in mice with microscopic inflammation and impairment in the epithelial esophageal barrier. Female Swiss mice were subjected to the following surgical procedure: the transitional region between the forestomach and the glandular portion of the stomach was ligated, and a nontoxic ring was placed around the duodenum near the pylorus. The control group underwent sham surgery. The animals were euthanized at 1, 3, 7, and 14 days after surgery. Survival and body weight were monitored daily. Esophageal wet weight, macroscopic lesion, histopathological alterations, myeloperoxidase (MPO) activity, cytokine levels, transepithelial electrical resistance (TEER), and mucosal permeability were evaluated. The survival rate was 78% at 14 days, with mild loss in body weight. Surgery did not induce erosive esophagitis but instead induced microscopic inflammation and increased esophageal wet weight, IL-6, keratinocyte-derived cytokine (KC) levels, and MPO activity with maximal peak between 3 and 7 days and resolution at 14 days postsurgery. Epithelial esophageal barrier was evaluated in operated mice at 7 and 14 days postsurgery; a decrease in TEER and increase in the esophageal epithelial permeability were observed compared with the sham-operated group. In addition, the inhibition of acid secretion with omeprazole significantly prevented the esophageal inflammation and impairment of barrier function at 7 days postsurgery. Thus we established a novel experimental model of NERD in mice, which can contribute to understanding the pathophysiological events associated with NERD.NEW & NOTEWORTHY In this study, we standardized an experimental model of nonerosive reflux disease (NERD) in mice. This model involves an acute inflammatory response followed by impaired esophageal mucosal integrity, even in the absence of inflammation. Thus this model can serve for evaluation of pathophysiological aspects of NERD and open new perspectives for therapeutic strategies for patients with this disorder.

Sulfated polysaccharide fraction from marine algae Solieria filiformis: Structural characterization, gastroprotective and antioxidant effects.

A sulfated polysaccharide (SFP) fraction from the marine alga Solieria filiformis was extracted and submitted to microanalysis, molar mass estimation and spectroscopic analysis. We evaluated its gastroprotective potential in vivo in an ethanol-induced gastric damage model and its in vitro antioxidant properties (DPPH, chelating ferrous ability and total antioxidant capacity). Its chemical composition revealed to be essentially an iota-carrageenan with a molar mass of 210.9kDa and high degree of substitution for sulfate groups (1.08). In vivo, SFP significantly (P<0.05) reduced, in a dose dependent manner, the ethanol-induced gastric damage. SFP prevents glutathione consume and increase of malondialdehyde and hemoglobin levels. SFP presented an IC50 of 1.77mg/mL in scavenging DPPH. The chelating ferrous ability was 38.98%, and the total antioxidant capacity was 2.01mg/mL. Thus, SFP prevents the development of ethanol-induced gastric damage by reducing oxidative stress in vivo and possesses relevant antioxidant activity in vitro.

Sulfated polysaccharide from the marine algae Hypnea musciformis inhibits TNBS-induced intestinal damage in rats.

Sulfated polysaccharides extracted from seaweed have important pharmacological properties. Thus, the aim of this study was to characterize the sulfated polysaccharide (PLS) from the algae Hypnea musciformis and evaluate its protective effect in colitis induced by trinitrobenzene sulfonic acid in rats. The sulfated polysaccharide possess a high molecular mass (1.24×10(5)gmol(-1)) and is composed of a κ-carrageenan, as depicted by FT-IR and NMR spectroscopic data. PLS was administered orally (10, 30, and 60mg/kg, p.o.) for three days, starting before TNBS (trinitrobenzene sulfonic acid) instillation (day 1). The rats were killed on day three, the portion of distal colon (5cm) was excised and evaluated macroscopic scores and wet weight. Then, samples of the intestinal were used for histological evaluation and quantification of glutathione, malonyldialdehyde acid, myeloperoxidase, nitrate/nitrite and cytokines. Our results demonstrate that PLS reduced the colitis and all analyzed biochemical parameters. Thus, we concluded that the PLS extracted from the marine algae H. musciformis reduced the colitis in animal model and may have an important promising application in the inflammatory bowel diseases.

Protective Effects of Simvastatin Against Alendronate-Induced Gastric Mucosal Injury in Rats.

BACKGROUND: It has been reported that simvastatin, a statin commonly prescribed for its anti-inflammatory and antioxidant effects, has gastroprotective effects in indomethacin and ethanol-induced gastric ulcers. However, the effects of simvastatin on alendronate-induced gastric mucosal injury remain unexplored. AIM: This study investigated the use of simvastatin for the treatment of alendronate-induced gastric ulcers in rats. METHODS: Female rats were pretreated with vehicle or simvastatin (20 and 60 mg/kg p.o.). After 1 h, the rats received alendronate (50 mg/kg p.o.). Simvastatin was administered once daily for 7 days, and from the fourth day of simvastatin treatment, alendronate was administered once daily for 4 days. On the final day of treatment, 4 h after alendronate administration, animals were euthanized, their stomachs were removed, and gastric damage was measured. Samples of the stomach were fixed in 10 % formalin immediately after their removal for subsequent histopathological assessment. Unfixed samples were weighed, frozen at -80 °C until assayed for glutathione (GSH), malondialdehyde (MDA), and cytokine levels and myeloperoxidase (MPO) activity. A third group was used to measure mucus and gastric secretion. RESULTS: Pretreatment with simvastatin prevented alendronate-induced macroscopic gastric damage and reduced the levels of MDA and GSH, TNF-α and IL-1ß, MPO activity, and mucus levels, in the stomach. CONCLUSIONS: This study demonstrates the protective effects of simvastatin against alendronate-induced gastric ulceration. Maintenance of mucosal integrity, inhibition of neutrophil activity, and reduced oxidative stress associated with decreased gastric acidity may explain the gastroprotective effects of simvastatin.

Evaluation of mucositis induced by irinotecan after microbial colonization in germ-free mice.

Mucositis is one of the most debilitating side effects of chemotherapy and some previous studies suggest a role for indigenous microbiota in the course of this pathology. Therefore, the aim of our study was to evaluate the differences in phenotype between germ-free (GF) and conventional (CV) mice, and the role of ß-glucuronidase-producing bacteria in the development of irinotecan treatment in a murine model. After mucositis induction, CV mice showed a significant increase in all inflammatory parameters when compared to GF mice. CV animals also showed more lesions of the intestinal epithelium, coherent with their higher intestinal permeability. The conventionalization of GF animals reversed their phenotype to that found in CV mice. In addition, gnotobiotic mice monoassociated with an Escherichia coli strain producing ß-glucuronidase showed an increased permeability when compared to gnotobiotic mice monoassociated with an E. coli strain deleted for the gene encoding ß-glucuronidase, but these did not show any differences in the influx of neutrophils, eosinophils or histological characteristics. Our data confirmed that components of the gut microbiota are involved in the signs of mucositis. Nevertheless, other mechanisms than this enzyme are involved in the irinotecan treatment, since the monoassociation was not able to restore the entire phenotype observed in the CV animals with irinotecan treatment in our murine model.

The nitric oxide donor cis-[Ru(bpy)2(SO3)NO](PF6) increases gastric mucosa protection in mice--involvement of the soluble guanylate cyclase/K(ATP) pathway.

Here, we have evaluated the protective effect of the NO donor cis-[Ru(bpy)2(SO3)NO](PF6) (FOR0810) in experimental models of gastric damage induced by naproxen or ethanol in mice, and the involvement of soluble guanylate cyclase (sGC) and ATP-sensitive K(+) channels (KATP) in these events. Swiss mice were pre-treated with saline, ODQ (a soluble guanylate cyclase inhibitor; 10 mg kg(-1)) or glibenclamide (a KATP channels blocker; 10 mg kg(-1)). After either 30 min or 1 h, FOR0810 (3 mg kg(-1)) was administered. At the end of 30 min, the animals received naproxen (300 mg kg(-1)) by gavage. After 6 h, the animals were sacrificed and gastric damage, myeloperoxidase (MPO) activity, and TNF-α and IL-1ß gastric concentrations were evaluated. In addition, the effects of FOR0810 on naproxen-induced mesenteric leukocyte adherence were determined by intravital microscopy. Other groups, were pre-treated with saline, ODQ or glibenclamide. After either 30 min or 1 h, FOR0810 was administered. At the end of 30 min, the animals received 50% ethanol by gavage. After 1 h, the animals were sacrificed, and gastric damage, gastric reduced glutathione (GSH) concentration and malondialdehyde (MDA) levels were determined. In naproxen-induced gastric damage, FOR0810 prevented gastric injury, decreased gastric MPO activity and leukocyte adherence, associated with a decrease in TNFα and IL-1ß gastric concentrations. FOR0810 also prevented ethanol-induced gastric damage by increase in GSH levels and decrease in MDA levels. ODQ and glibenclamide completely reversed FOR0810's ability to prevent gastric damage by either naproxen or ethanol. We infer that FOR0810 prevented gastric damage through the activation of both sGC and KATP channels, which triggered a decrease in both free radical and cytokine production via the blocking of neutrophil adhesion and infiltration.

Alendronate induces gastric damage by reducing nitric oxide synthase expression and NO/cGMP/K(ATP) signaling pathway.

Chronic use of alendronate has been linked to gastrointestinal tract problems. Our objective was to evaluate the role of the NO/cGMP/KATP signaling pathway and nitric oxide synthase expression in alendronate-induced gastric damage. Rats were either treated with the NO donor, sodium nitroprusside (SNP; 1, 3, and 10 mg/kg), or the NO synthase (NOS) substrate, L-arginine (L-Arg; 50, 100, and 200 mg/kg). Some rats were pretreated with either ODQ (a guanylate cyclase inhibitor; 10 mg/kg) or glibenclamide (KATP channels blocker; 10 mg/kg). In other experiments, rats were pretreated with L-NAME (non-selective NOS inhibitor; 10 mg/kg), 1400 W (selective inducible NOS [iNOS] inhibitor; 10 mg/kg), or L-NIO (a selective endothelial NOS [eNOS] inhibitor; 30 mg/kg). After 1 h, the rats were treated with alendronate (30 mg/kg) by gavage for 4 days. SNP and L-Arg prevented alendronate-induced gastric damage in a dose-dependent manner. Alendronate reduced nitrite/nitrate levels, an effect that was reversed with SNP or L-Arg treatment. Pretreatment with ODQ or glibenclamide reversed the protective effects of SNP and L-Arg. L-NAME, 1400 W, or L-NIO aggravated the severity of alendronate-induced lesions. In addition, alendronate reduced the expression of iNOS and eNOS in the gastric mucosa. Gastric ulcerogenic responses induced by alendronate were mediated by a decrease in NO derived from both eNOS and iNOS. In addition, our findings support the hypothesis that activation of the NO/cGMP/KATP pathway is of primary importance for protection against alendronate-induced gastric damage.

Sulfated-polysaccharide fraction extracted from red algae Gracilaria birdiae ameliorates trinitrobenzenesulfonic acid-induced colitis in rats.

OBJECTIVES: The aim of this study was to evaluate the protective effect of the sulfated-polysaccharide (PLS) fraction extracted from the seaweed Gracilaria birdiae in rats with trinitrobenzenesulfonic acid (TNBS)-induced colitis. METHODS: In the experiments involving TNBS-induced colitis, rats were pretreated with polysaccharide extracted from G. birdiae (PLS: 30, 60 and 90 mg/kg, 500 µL p.o.) or dexamethasone (control group: 1 mg/kg) once daily for 3 days starting before TNBS instillation (day 1). The rats were killed on the third day, the portion of distal colon was excised and washed with 0.9% saline and pinned onto a wax block for the evaluation of macroscopic scores. Samples of the intestinal tissue were used for histological evaluation and assays for glutathione (GSH) levels, malonyldialdehyde (MDA) concentration, myeloperoxidase (MPO) activity, nitrate and nitrite (NO3 /NO2 ) concentration and cytokines levels. KEY FINDINGS: PLS treatment reduced the macroscopic and microscopic TNBS-induced intestinal damage. Additionally, it avoided the consumption of GSH, decreased pro-inflammatory cytokine levels, MDA and NO3 /NO2 concentrations and diminished the MPO activity. CONCLUSIONS: Our results suggest that the PLS fraction has a protective effect against intestinal damage through mechanisms that involve the inhibition of inflammatory cell infiltration, cytokine releasing and lipid peroxidation.

Treatment with Saccharomyces boulardii reduces the inflammation and dysfunction of the gastrointestinal tract in 5-fluorouracil-induced intestinal mucositis in mice.

Intestinal mucositis is an important toxic side effect of 5-fluorouracil (5-FU) treatment. Saccharomyces boulardii is known to protect from intestinal injury via an effect on the gastrointestinal microbiota. The objective of the present study was to evaluate the effect of S. boulardii on intestinal mucositis induced by 5-FU in a murine model. Mice were divided into saline, saline (control)+5-FU or 5-FU+S. boulardii (16 × 109 colony-forming units/kg) treatment groups, and the jejunum and ileum were removed after killing of mice for the evaluation of histopathology, myeloperoxidase (MPO) activity, and non-protein sulfhydryl group (mainly reduced glutathione; GSH), nitrite and cytokine concentrations. To determine gastric emptying, phenol red was administered orally, mice were killed 20 min after administration, and the absorbance of samples collected from the mice was measured by spectrophotometry. Intestinal permeability was measured by the urinary excretion rate of lactulose and mannitol following oral administration. S. boulardii significantly reversed the histopathological changes in intestinal mucositis induced by 5-FU and reduced the inflammatory parameters: neutrophil infiltration (control 1·73 (SEM 0·37) ultrastructural MPO (UMPO)/mg, 5-FU 7·37 (SEM 1·77) UMPO/mg and 5-FU+S. boulardii 4·15 (SEM 0·73) UMPO/mg); nitrite concentration (control 37·00 (SEM 2·39) µm, 5-FU 59·04 (SEM 11·41) µm and 5-FU+S. boulardii 37·90 (SEM 5·78) µm); GSH concentration (control 477·60 (SEM 25·25) µg/mg, 5-FU 270·90 (SEM 38·50) µg/mg and 5-FU+S. boulardii 514·00 (SEM 38·64) µg/mg). Treatment with S. Boulardii significantly reduced the concentrations of TNF-α and IL-1ß by 48·92 and 32·21 % in the jejunum and 38·92 and 61·79 % in the ileum. In addition, S. boulardii decreased the concentrations of chemokine (C-X-C motif) ligand 1 by 5-fold in the jejunum and 3-fold in the ileum. Interestingly, S. boulardii reduced the delay in gastric emptying (control 25·21 (SEM 2·55) %, 5-FU 54·91 (SEM 3·43) % and 5-FU+S. boulardii 31·38 (SEM 2·80) %) and induced the recovery of intestinal permeability (lactulose:mannitol ratio: control 0·52 (SEM 0·03), 5-FU 1·38 (SEM 0·24) and 5-FU+S. boulardii 0·62 (SEM 0·03)). In conclusion, S. boulardii reduces the inflammation and dysfunction of the gastrointestinal tract in intestinal mucositis induced by 5-FU.

Protective effects of fucoidan, a P- and L-selectin inhibitor, in murine acute pancreatitis.

OBJECTIVE: The objective of this study was to investigate the potential protective effects of fucoidan, an L- and P-selectin modulator, in 2 murine models of acute pancreatitis. METHODS: Acute pancreatitis was induced in mice either by the retrograde infusion of taurolithocholic acid sulfate into the pancreatic duct or by intraperitoneal injections of cerulein (50 µg/kg per hour). The experimental groups received fucoidan (25 mg/kg, intravenously) before pancreatitis induction, whereas control groups received only saline. After 24 hours, serum amylase, lipase, interleukin 1ß (IL-1ß), tumor necrosis factor α (TNF-α), and nitrite were measured. In addition, myeloperoxidase (MPO) activity (lung and pancreas) and histological assessment (pancreas) were determined. RESULTS: Serum amylase, lipase, nitrite, TNF-α, and IL-1ß, and pancreatic and lung MPO were increased in both taurolithocholic acid sulfate and cerulein acute pancreatitis compared with the respective control groups. Fucoidan significantly decreased the augmented levels of amylase, lipase, pancreatic and lung MPO, TNF-α, IL-1ß, and nitrite in both models. Pancreas histological changes observed in both acute pancreatitis models were significantly attenuated by fucoidan. CONCLUSIONS: Fucoidan reduced the severity of acute pancreatitis in mice by decreasing neutrophil infiltration and systemic inflammation, suggesting that modulation of selectins may constitute a promising therapeutic approach.

Role of soluble guanylate cyclase activation in the gastroprotective effect of the HO-1/CO pathway against alendronate-induced gastric damage in rats.

Our objective was to evaluate the role of soluble guanylate cyclase (sGC) activation in the gastroprotective effect of the HO-1/CO pathway against alendronate-induced gastric damage in rats. Rats were pretreated, once daily for 4 days, with saline, hemin (HO-1 inducer), or dimanganese decacarbonyl (DMDC, CO donor). Another group received zinc protoporphyrin IX (ZnPP IX, HO-1 antagonist) 1 h before hemin treatment or sGC inhibitor (ODQ) 30 min before hemin and DMDC treatment. After 30 min, gastric damage was induced by alendronate (30 mg/kg) by gavage. On the last day of treatment, 4 h after alendronate administration, the animals were killed. Gastric lesions were measured using a computer planimetry program, and gastric corpus pieces were assayed for malondialdehyde (MDA), glutathione (GSH), pro-inflammatory cytokines (tumor necrosis factor [TNF]-α and interleukin [IL]-1ß), myeloperoxidase (MPO), or bilirubin. Another group was used to measure gastric mucus. HO-1 expression was determined after saline or alendronate administration by immunohistochemistry. Alendronate induced gastric damage, produced neutrophil accumulation, increased MDA levels and MPO activity, and reduced GSH and mucus in the gastric tissue. Alendronate also increased HO-1 immunoreactivity and the level of bilirubin in gastric mucosa. Pretreatment with hemin or DMDC reduced neutrophil infiltration and TNF-α, IL-1ß, and MDA formation, and increased the levels of GSH and mucus in the gastric tissue. ODQ completely abolished the gastroprotective effect of hemin and DMDC and increased alendronate gastric damage. Our results suggest that the HO-1/CO pathway plays a protective role against alendronate-induced gastric damage through mechanisms that can be dependent on sGC activation.