The involvement of mast cells in the irinotecan-induced enteric neurons loss and reactive gliosis.

BACKGROUND: The irinotecan (CPT-11) causes intestinal mucositis and diarrhea that may be related to changes in the enteric nervous system (ENS). In inflammatory condition, mast cells release a variety of pro-inflammatory mediators that can interact with the ENS cells. It has not been explored whether CPT-11 is able to alter the enteric glial and neuronal cell, and the role of mast cells in this effect. Therefore, this study was conducted to investigate the effect of CPT-11 on the enteric glial and neuronal cells, as well as to study the role of mast cells in the CPT-11-induced intestinal mucositis. METHODS: Intestinal mucositis was induced in Swiss mice by the injection of CPT-11 (60 mg/kg, i.p.) once a day for 4 days following by euthanasia on the fifth day. To investigate the role of mast cells, the mice were pretreated with compound 48/80 for 4 days (first day, 0.6 mg/kg; second day, 1.0 mg/kg; third day, 1.2 mg/kg; fourth day, 2.4 mg/kg) to induce mast cell degranulation before the CPT-11 treatment. RESULTS: Here, we show that CPT-11 increased glial fibrillary acidic protein (GFAP) and S100ß gene and S100ß protein expressions and decreased HuC/D protein expression in the small intestine segments. Concomitantly, CPT-11 enhanced tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) levels and inducible nitric oxide synthase (iNOS) gene expression, associated with an increase in the total number macrophages (positive cells for ionized calcium-binding adapter molecule, Iba-1) and degranulated mast cells in the small intestine segments and caused significant weight loss. The pretreatment with compound 48/80, an inductor of mast cells degranulation, significantly prevented these CPT-11-induced effects. CONCLUSIONS: Our data suggests the participation of mast cells on the CPT-11-induced intestinal mucositis, macrophages activation, enteric reactive gliosis, and neuron loss.

Role of inducible nitric oxide synthase pathway on methotrexate-induced intestinal mucositis in rodents.

BACKGROUND: Methotrexate treatment has been associated to intestinal epithelial damage. Studies have suggested an important role of nitric oxide in such injury. The aim of this study was to investigate the role of nitric oxide (NO), specifically iNOS on the pathogenesis of methotrexate (MTX)-induced intestinal mucositis. METHODS: Intestinal mucositis was carried out by three subcutaneous MTX injections (2.5 mg/kg) in Wistar rats and in inducible nitric oxide synthase knock-out (iNOS-/-) and wild-type (iNOS+/+) mice. Rats were treated intraperitoneally with the NOS inhibitors aminoguanidine (AG; 10 mg/Kg) or L-NAME (20 mg/Kg), one hour before MTX injection and daily until sacrifice, on the fifth day. The jejunum was harvested to investigate the expression of Ki67, iNOS and nitrotyrosine by immunohistochemistry and cell death by TUNEL. The neutrophil activity by myeloperoxidase (MPO) assay was performed in the three small intestine segments. RESULTS: AG and L-NAME significantly reduced villus and crypt damages, inflammatory alterations, cell death, MPO activity, and nitrotyrosine immunostaining due to MTX challenge. The treatment with AG, but not L-NAME, prevented the inhibitory effect of MTX on cell proliferation. MTX induced increased expression of iNOS detected by immunohistochemistry. MTX did not cause significant inflammation in the iNOS-/- mice. CONCLUSION: These results suggest an important role of NO, via activation of iNOS, in the pathogenesis of intestinal mucositis.

Hydrogen sulfide prevents ethanol-induced gastric damage in mice: role of ATP-sensitive potassium channels and capsaicin-sensitive primary afferent neurons.

The aim of this study was to evaluate the protective effect of hydrogen sulfide (H(2)S) on ethanol-induced gastric lesions in mice and the influence of ATP-sensitive potassium (K(ATP)) channels, capsaicin-sensitive sensory afferent neurons, and transient receptor potential vanilloid (TRPV) 1 receptors on such an effect. Saline and L-cysteine alone or with propargylglycine, sodium hydrogen sulfide (NaHS), or Lawesson's reagent were administrated for testing purposes. For other experiments, mice were pretreated with glibenclamide, neurotoxic doses of capsaicin, or capsazepine. Afterward, mice received L-cysteine, NaHS, or Lawesson's reagent. After 30 min, 50% ethanol was administrated by gavage. After 1 h, mice were sacrificed, and gastric damage was evaluated by macroscopic and microscopic analyses. L-cysteine, NaHS, and Lawesson's reagent treatment prevented ethanol-induced macroscopic and microscopic gastric damage in a dose-dependent manner. Administration of propargylglycine, an inhibitor of endogenous H(2)S synthesis, reversed gastric protection induced by L-cysteine. Glibenclamide reversed L-cysteine, NaHS, or Lawesson's reagent gastroprotective effects against ethanol-induced macroscopic damage in a dose-dependent manner. Chemical ablation of sensory afferent neurons by capsaicin reversed gastroprotective effects of L-cysteine or H(2)S donors (NaHS or Lawesson's reagent) in ethanol-induced macroscopic gastric damage. Likewise, in the presence of the TRPV1 antagonist capsazepine, the gastroprotective effects of L-cysteine, NaHS, or Lawesson's reagent were also abolished. Our results suggest that H(2)S prevents ethanol-induced gastric damage. Although there are many mechanisms through which this effect can occur, our data support the hypothesis that the activation of K(ATP) channels and afferent neurons/TRPV1 receptors is of primary importance.

LPS from Escherichia coli protects against indomethacin-induced gastropathy in rats--role of ATP-sensitive potassium channels.

The effect of lipopolysaccharide (LPS) in gastric protection has not been elucidated, but ATP-sensitive potassium (K(ATP)) channels are known to be involved in gastric defense. We evaluated the effect of LPS administration on indomethacin-induced gastropathy, and the role of K(ATP) channels in this event. Rats received intravenous (i.v.) LPS administration. After 1/2, 6, 24 or 48 h, indomethacin was injected. 3H later, gastric damage and myeloperoxidase activity were determined. Another group received LPS and 5 h later, glibenclamide, diazoxide or glibenclamide plus diazoxide. After 1 h, the rats received indomethacin and 3 h later, gastric damage and myeloperoxidase activity were evaluated. LPS reduced dose dependently gastric damage and myeloperoxidase activity induced by indomethacin. Glibenclamide reversed this LPS effect on indomethacin-induced gastropathy. Glibenclamide plus diazoxide administration did not change this LPS effect. Thus LPS has a protective effect against indomethacin-induced gastropathy, probably through activation of K(ATP) channels.

Sildenafil prevents indomethacin-induced gastropathy in rats: role of leukocyte adherence and gastric blood flow.

Nitric oxide (NO) is an important mediator of gastric mucosal defense. Sildenafil (SILD), a cyclic GMP-specific phosphodiesterase inhibitor, promotes an increase in cGMP concentrations in the gastrointestinal tract. cGMP mediates many of the biological actions of NO. We tested the hypothesis that SILD could increase mucosal defense against indomethacin-induced gastropathy in rats. SILD (1, 4 or 10 mg kg(-1), p.o.) pretreatment significantly reduced (P < 0.01) the gastric damage and the increase in gastric myeloperoxidase (MPO) activity elicited by indomethacin (20 mg kg(-1) p.o.), with the maximal effect at the dose of 10 mg kg(-1). L-NAME (3, 10 or 20 mg kg(-1), i.p.) dose dependently reversed the protective effects of SILD, an effect not seen when L-arginine (L-ARG) (200 mg kg(-1), i.p.) was co-administered with L-NAME. Indomethacin-induced leukocyte adhesion, assessed by intravital microscopy, was decreased (P < 0.01) by SILD, and this effect was reversed by L-NAME cotreatment. Indomethacin elicited a decrease in gastric blood flow and in gastric PGE2 levels. SILD was able to prevent the decrease in gastric blood flow (P < 0.01), without diminishing the inhibitory effect of indomethacin on prostaglandin synthesis. These results indicate that SILD, acting via NO-dependent mechanisms, prevents indomethacin-induced gastropathy, possibly through a reduction of leukocyte adhesion and maintenance of gastric blood flow.

A novel chitin-binding protein from Moringa oleifera seed with potential for plant disease control.

A thermostable chitin-binding protein (14.3 kDa) with antifungal activity was isolated from Moringa oleifera seeds by affinity chromatography on chitin followed by ion exchange chromatography. NH(2-) CPAIQRCCQQLRNIQPPCRCCQ (Mo-CBP3) is a glycoprotein with 2.5% sugar, pI 10.8, without hemagglutination, chitinase or beta-glucanase activities. Mo-CBP3 possesses in vitro antifungal activity against the phytopathogenicfungi Fusarium solani, F. oxysporum, Colletotrichum musae and C. gloesporioides. Contrarily, Mo-CBP3 did not affect Pythium oligandrum, an oomycete. At 0.05 mg/ml, Mo-CBP3 showed to be fungistatic against F. solani, but at 0.1 mg/ml Mo-CBP3 behaved as a potent fungicidal agent as it inhibited both the spore germination and mycelial growth of F. solani. Surprisingly, the effect of Mo-CBP3 against spore germination was observed even when the protein was heated at 100 degrees C for 1 h or pretreated with 0.15M N-acetyl-D-glucosamine. Mo-CBP3 inhibited the glucose-stimulated acidification of the incubation medium by F. solani. This is apparently caused by structural plasma membrane disarrangement induced by Mo-CBP3. Altogether, these results suggest that Mo-CBP3 might be involved in plant defense mechanisms and could be used as potential antifungal agent for controlling fungal pathogens in plants.

Inhaled 1,8-cineole reduces inflammatory parameters in airways of ovalbumin-challenged Guinea pigs.

Eucalyptol, also known as 1,8-cineole, is a monoterpene traditionally used to treat respiratory disorders due to its secretolytic properties. In addition to its myorelaxant effects, it also has anti-inflammatory actions in vitro. In this study, we aimed to evaluate the efficacy of acute treatment with 1,8-cineole on reducing airway inflammatory parameters. Ovalbumin (OVA)-sensitized guinea pigs were submitted to antigenic challenge (OVA) with or without pre-treatment with a single dose of 1,8-cineole administered by inhalation. Airway inflammatory parameters were reduced or absent in 1,8-cineole-treated animals as compared with untreated guinea pigs. Acute treatment with 1,8-cineole impaired the development of airway hyperresponsiveness to carbachol in isolated tracheal rings. Levels of the pro-inflammatory cytokines TNFα and IL-1ß was lower in bronchoalveolar lavage fluid (BALF) of 1,8-cineol-treated guinea pigs than in untreated animals. 1,8-Cineole impaired the OVA-induced increase of the myeloperoxidase activity in BALF. 1,8-Cineole also prevented the reduction of the mucociliary clearance induced by the antigen presentation. The present investigation provides evidence that inhaled 1,8-cineole prevents hyperresponsiveness and inhibits inflammation in airways of ovalbumin-challenged guinea pigs.

Gastroprotective effect of heme-oxygenase 1/biliverdin/CO pathway in ethanol-induced gastric damage in mice.

Our objective was to evaluate the role of heme-oxygenase 1 (HO-1)/biliverdin/CO pathway in gastric defense against ethanol-induced gastric damage in mice. Mice were pre-treated with saline, hemin (HO-1 inducer), biliverdin (HO-1 product), dimanganese decacarbonyl (DMDC, CO donor) or zinc protoporphyrin IX (ZnPP IX, HO-1 antagonist). Another group received soluble guanylate cyclase (sGC) inhibitor (ODQ) 30 min before hemin, biliverdin or DMDC. After 30 min, gastric damage was induced by ethanol. After one hour, rats were sacrificed. Gastric lesions were measured using a computer planimetry program, and gastric corpus pieces were assayed for malonylaldehyde (MDA), glutathione (GSH) or bilirubin. HO-1 expression was determined after saline or ethanol administration by polymerase chain reaction (PCR) or immunohistochemistry. Ethanol (25% or 50%) induced gastric damage, increased MDA levels and reduced GSH in the gastric tissue. Ethanol 50% increased HO-1 mRNA transcripts, HO-1 immunoreactivity, and bilirubin concentration in gastric mucosa. Pre-treatment with hemin reduced gastric damage and MDA formation and increased GSH concentration in the gastric mucosa. ZnPP IX amplified the ethanol-induced gastric lesion, increased MDA formation and decreased GSH concentration in gastric mucosa. Biliverdin and DMDC reduced gastric damage and MDA formation and increased GSH concentration in the gastric tissue. ODQ completely abolished the DMDC protective gastric effect. However, effects of hemin or biliverdin did not change with ODQ treatment. Our results suggest that HO-1/biliverdin/CO pathway plays a protective role against ethanol-induced gastric damage through mechanisms that can be dependent (CO) or independent (biliverdin) of sGC activation.

Gastrointestinal dysmotility in 5-fluorouracil-induced intestinal mucositis outlasts inflammatory process resolution.

AIM: To evaluate gastrointestinal motility during 5-fluorouracil (5-FU)-induced intestinal mucositis. MATERIALS AND METHODS: Wistar rats received 5-FU (150 mg kg(-1), i.p.) or saline. After the 1st, 3rd, 5th, 15th and 30th day, sections of duodenum, jejunum and ileum were removed for assessment of epithelial damage, apoptotic and mitotic indexes, MPO activity and GSH concentration. In order to study gastrointestinal motility, on the 3rd or 15th day after 5-FU treatment, gastric emptying in vivo was measured by scintilographic method, and stomach or duodenal smooth muscle contractions induced by CCh were evaluated in vitro. RESULTS: On the third day of treatment, 5-FU induced a significant villi shortening, an increase in crypt depth and intestinal MPO activity and a decrease in villus/crypt ratio and GSH concentration. On the first day after 5-FU there was an increase in the apoptosis index and a decrease in the mitosis index in all intestinal segments. After the 15th day of 5-FU treatment, a complete reversion of all these parameters was observed. There was a delay in gastric emptying in vivo and a significant increase in gastric fundus and duodenum smooth muscle contraction, after both the 3rd and 15th day. CONCLUSION: 5-FU-induced gastrointestinal dysmotility outlasts intestinal mucositis.