Renata Ferreira de Carvalho Leitão

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

BackgroundMethotrexate 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.MethodsIntestinal 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.ResultsAG 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.ConclusionThese results suggest an important role of NO, via activation of iNOS, in the pathogenesis of intestinal mucositis.

S-nitrosoglutathione decreases inflammation and bone resorption in experimental periodontitis in rats.

BACKGROUND S-nitrosoglutathione (GSNO) is a nitric oxide donor that may exert antioxidant, anti-inflammatory, and microbicidal actions and is thus a potential drug for the topical treatment of periodontitis. In this study, the effect of intragingival injections of GSNO-containing polyvinylpyrrolidone (PVP) formulations is evaluated in a rat model of periodontitis. METHODS Periodontal disease was induced by placing a sterilized nylon (000) thread ligature around the cervix of the second left upper molar of the animals, which received intragingival injections of PVP; saline; or PVP/GSNO solutions which corresponded to GSNO doses of 25, 100, and 500 nmol; 1 hour before periodontitis induction, and thereafter, daily for 11 days. RESULTS PVP/GSNO formulations at doses of 25 and/or 100, but not 500 nmol caused significant inhibition of alveolar bone loss, increase of bone alkaline phosphatase, decrease of myeloperoxidase activity, as well as significant reduction of inflammatory and oxidative stress markers when compared to saline and PVP groups. These effects were also associated with a decrease of matrix metalloproteinases 1 and 8, inducible nitric oxide synthase, and nuclear factor-κB immunostaining in the periodontium. CONCLUSION Local intragingival injections of GSNO reduces inflammation and bone loss in experimental periodontal disease.

Carvedilol Improves Inflammatory Response, Oxidative Stress and Fibrosis in the Alcohol-Induced Liver Injury in Rats by Regulating Kuppfer Cells and Hepatic Stellate Cells

Aim To evaluate the anti-inflammatory, anti-oxidant and antifibrotic effects of carvedilol (CARV) in rats with ethanol-induced liver injury. Methods Liver injury was induced by gavage administration of alcohol (7 g/kg) for 28 consecutive days. Eighty Wistar rats were pretreated with oral CARV at 1, 3, or 5 mg/kg or with saline 1 h before exposure to alcohol. Liver homogenates were assayed for interleukin (IL)-1β, IL-10, and tumor necrosis factor (TNF)-α level as well as for myeloperoxidase (MPO) activity and malonyldialdehyde (MDA) and glutathione (GSH) levels. Serum aspartate aminotransferase (AST) activity and liver triglyceride (TG) levels were also assayed. Immunohistochemical analyses of cyclooxygenase 2 (COX-2), receptor activator of nuclear factor kappa-B/ligand (RANK/RANKL), suppressor of cytokine signalling (SOCS1), the Kupffer cell marker IBA-1 (ionized calcium-binding adaptor molecule 1), intercellular adhesion molecule 1 (ICAM-1), superoxide dismutase (SOD-1), and glutathione peroxidase (GPx-1) expression were performed. Confocal microscopy analysis of IL-1β and NF-κB expression and real-time quantitative PCR analysis for TNFα, PCI, PCIII, and NF-κB were performed. Results CARV treatment (5 mg/kg) during the alcohol exposure protocol was associated with reduced steatosis, hepatic cord degeneration, fibrosis and necrosis, as well as reduced levels of AST (p < 0.01), ALT (p < 0.01), TG (p < 0.001), MPO (p < 0.001), MDA (p < 0.05), and proinflammatory cytokines (IL-1β and TNF-α, both p < 0.05), and increased levels of the anti-inflammatory cytokine IL-10 (p < 0.001) and GSH (p < 0.05), compared to the alcohol-only group. Treatment with CARV 5 mg/kg also reduced expression levels of COX-2, RANK, RANKL, IBA-1, and ICAM-1 (all p < 0.05), while increasing expression of SOCS1, SOD-1, and GPx-1 (all p < 0.05) and decreasing expression of IL-1β and NF-κB (both, p < 0.05). Real-time quantitative PCR analysis showed that mRNA production of TNF-α, procollagen type I (PCI), procollagen type III (PCIII), and NF-κB were decreased in the alcohol-CARV 5 mg/kg group relative to the alcohol-only group. Conclusions CARV can reduce the stress oxidative, inflammatory response and fibrosis in ethanol-induced liver injury in a rat model by downregulating signalling of Kuppfer cells and hepatic stellate cells (HSCs) through suppression of inflammatory cytokines.

The role of apoptosis in cisplatin-induced ototoxicity in rats

UNLABELLED Cisplatin is a chemotherapy agent frequently used to treat different types of neoplasia. Ototoxicity is one of the side-effects which cause significant morbidity and limits its use. This study aimed at assessing the role of apoptosis in cisplatin-induced ototoxicity. DESIGN experimental study. MATERIALS AND METHODS male Wistar rats were treated with intraperitoneal cisplatin, in the doses of 24 and 16 mg/kg. The animals were assessed by means of distortion product evoked otoacoustic emissions (DPEOAE) or brainstem evoked auditory potentials (BEAP) in the third (D3) and fourth (D4) days after drug infusion onset. Following that, their cochleas were removed for immunohistochemical studies of apoptosis - TUNEL method. RESULTS the group treated with 24 mg/kg showed a significant reduction in DPEOAE amplitude, and such fact was not seen with the 16 mg/kg. Both doses caused an increase in BEAP electrophysiological threshold in D3 and D4. Apoptosis was the injury mechanism responsible for the cisplatin-induced ototoxicity - 16 mg/kg dose, when the animals were assessed on D3. CONCLUSION apoptosis may be involved in the cisplatin-induced ototoxicity, depending on the dose and time of injury assessment.

S-Nitrosoglutathione Accelerates Recovery from 5-Fluorouracil-Induced Oral Mucositis

Introduction Mucositis induced by anti-neoplastic drugs is an important, dose-limiting and costly side-effect of cancer therapy. Aim To evaluate the effect of the topical application of S-nitrosoglutathione (GSNO), a nitric oxide donor, on 5-fluorouracil (5-FU)-induced oral mucositis in hamsters. Materials and Methods Oral mucositis was induced in male hamsters by two intraperitoneal administrations of 5-FU on the first and second days of the experiment (60 and 40 mg/kg, respectively) followed by mechanical trauma on the fourth day. Animals received saline, HPMC or HPMC/GSNO (0.1, 0.5 or 2.0 mM) 1 h prior to the 5-FU injection and twice a day for 10 or 14 days. Samples of cheek pouches were harvested for: histopathological analysis, TNF-α and IL-1β levels, immunohistochemical staining for iNOS, TNF-α, IL-1β, Ki67 and TGF-β RII and a TUNEL assay. The presence and levels of 39 bacterial taxa were analyzed using the Checkerboard DNA-DNA hybridization method. The profiles of NO released from the HPMC/GSNO formulations were characterized using chemiluminescence. Results The HPMC/GSNO formulations were found to provide sustained release of NO for more than 4 h at concentration-dependent rates of 14 to 80 nmol/mL/h. Treatment with HPMC/GSNO (0.5 mM) significantly reduced mucosal damage, inflammatory alterations and cell death associated with 5-FU-induced oral mucositis on day 14 but not on day 10. HPMC/GSNO administration also reversed the inhibitory effect of 5-FU on cell proliferation on day 14. In addition, we observed that the chemotherapy significantly increased the levels and/or prevalence of several bacterial species. Conclusion Topical HPMC/GSNO accelerates mucosal recovery, reduces inflammatory parameters, speeds up re-epithelization and decreases levels of periodontopathic species in mucosal ulcers.

Effects of metformin on inflammation, oxidative stress, and bone loss in a rat model of periodontitis

Aim To evaluate the effects of metformin (Met) on inflammation, oxidative stress, and bone loss in a rat model of ligature-induced periodontitis. Materials & methods Male albino Wistar rats were divided randomly into five groups of twenty-one rats each, and given the following treatments for 10 days: (1) no ligature + water, (2) ligature + water, (3) ligature + 50 mg/kg Met, (4) ligature + 100 mg/kg Met, and (5) ligature + 200 mg/kg Met. Water or Met was administered orally. Maxillae were fixed and scanned using Micro-computed Tomography (μCT) to quantitate linear and bone volume/tissue volume (BV/TV) volumetric bone loss. Histopathological characteristics were assessed through immunohistochemical staining for MMP-9, COX-2, the RANKL/RANK/OPG pathway, SOD-1, and GPx-1. Additionally, confocal microscopy was used to analyze osteocalcin fluorescence. UV-VIS analysis was used to examine the levels of malondialdehyde, glutathione, IL-1β and TNF-α from gingival tissues. Quantitative RT-PCR reaction was used to gene expression of AMPK, NF-κB (p65), and Hmgb1 from gingival tissues. Significance among groups were analysed using a one-way ANOVA. A p-value of p<0.05 indicated a significant difference. Results Treatment with 50 mg/kg Met significantly reduced concentrations of malondialdehyde, IL-1β, and TNF-α (p < 0.05). Additionally, weak staining was observed for COX-2, MMP-9, RANK, RANKL, SOD-1, and GPx-1 after 50 mg/kg Met. OPG and Osteocalcin showed strong staining in the same group. Radiographically, linear measurements showed a statistically significant reduction in bone loss after 50 mg/kg Met compared to the ligature and Met 200 mg/kg groups. The same pattern was observed volumetrically in BV/TV and decreased osteoclast number (p<0.05). RT-PCR showed increased AMPK expression and decreased expression of NF-κB (p65) and HMGB1 after 50 mg/kg Met. Conclusions Metformin, at a concentration of 50 mg/kg, decreases the inflammatory response, oxidative stress and bone loss in ligature-induced periodontitis in rats.

Protective effects of alanyl-glutamine supplementation against nelfinavir-induced epithelial impairment in IEC-6 cells and in mouse intestinal mucosa.

Purpose: Human Immunodefiency Virus (HIV) protease inhibitors (PI) remain a crucial component of highly active therapy (HAART) and recently have been demonstrated to have potent antitumor effect on a wide variety of tumor cell lines. However, discontinuation of therapy is an important issue, which may be related to various side-effects, especially diarrhea. The aim of this study was to evaluate the effects of nelfinavir (NFV), an HIV PI, and of alanyl-glutamine (AQ) supplementation, on intestinal cell migration, proliferation, apoptosis and necrosis, using IEC-6 cells and on intestinal crypt depth, villus length, villus area, mitotic index and apoptosis in Swiss mice. Methods: Migration was evaluated at 12 and 24 h after injury using a wound healing assay. Cellular proliferation was measured indirectly at 24 and 48 h using tetrazolium salt WST-1. Apoptosis and necrosis were measured by flow cytometry using the Annexin V assay. Intestinal morphometry and mitotic index in vivo were assessed following a seven-day treatment with 100 mg/kg of NFV, given orally. In vivo proliferation and apoptosis were evaluated by intestinal crypt mitotic index and immunohistochemistry, respectively. Results: In vitro, AQ supplementation enhanced IEC-6 cell migration and proliferation, following challenge with NFV. In vivo, AQ increased intestinal villus length, villus area, crypt depth and cell proliferation and cell migration, following treatment with NFV. AQ did not decrease cell death induced by NFV both in vivo and in vitro. Conclusions: AQ supplementation is potentially beneficial in preventing the effects of PIs, such as NFV, in the intestinal tract.

Topical HPMC/S-Nitrosoglutathione Solution Decreases Inflammation and Bone Resorption in Experimental Periodontal Disease in Rats

S-nitrosoglutathione (GSNO) is a nitric oxide (NO) donor, which exerts antioxidant, anti-inflammatory, and microbicidal actions. Intragingival application of GSNO was already shown to decrease alveolar bone loss, inflammation and oxidative stress in an experimental periodontal disease (EPD) model. In the present study, we evaluated the potential therapeutic effect of topical applications of hydroxypropylmethylcellulose (HPMC)/GSNO solutions on EPD in Wistar rats. EPD was induced by placing a sterilized nylon (3.0) thread ligature around the cervix of the second left upper molar of the animals, which received topical applications of a HPMC solutions containing GSNO 2 or 10 mM or vehicle (HPMC solution), 1 h prior to the placement of the ligature and then twice daily until sacrifice on day 11. Treatment with HPMC/GSNO 10 mM solution significantly reduced alveolar bone loss, oxidative stress and TNF-α e IL-1β levels in the surrounding gingival tissue, and led to a decreased transcription of RANK and TNF-α genes and elevated bone alkaline phosphatase, compared to the HPMC group. In conclusion, topical application of HPMC/GSNO solution is a potential treatment to reduce inflammation and bone loss in periodontal disease.

Papel da apoptose na ototoxicidade por cisplatina em ratos

isplatina e um agente quimioterapico frequentemente usado para o tratamento de varias linhagens de neoplasias. A ototoxicidade e um dos efeitos colaterais causadores de significativa morbidade e que limita sua utilizacao. Este estudo teve por objetivo avaliar o papel da apoptose na ototoxicidade por cisplatina.

TGF-β1/SMADs signaling pathway activation protects intestinal epithelium from Clostridium difficile toxin A-induced damage

ABSTRACT Clostridium difficile, the main cause of diarrhea in hospitalized patients, produces toxins A (TcdA) and B (TcdB), which affect intestinal epithelial cell survival, proliferation, and migration and induce an intense inflammatory response. Transforming growth factor β (TGF-β) is a pleiotropic cytokine affecting enterocyte and immune/inflammatory responses. However, it has been shown that exposure of intestinal epithelium to a low concentration of TcdA induces the release of TGF-β1, which has a protective effect on epithelial resistance and a TcdA/TGF-β signaling pathway interaction. The activation of this pathway in vivo has not been elucidated. The aim of this study was to investigate the role of the TGF-β1 pathway in TcdA-induced damage in a rat intestinal epithelial cell line (IEC-6) and in a mouse model of an ileal loop. TcdA increased the expression of TGF-β1 and its receptor, TβRII, in vitro and in vivo. TcdA induced nuclear translocation of the transcription factors SMAD2/3, a hallmark of TGF-β1 pathway activation, both in IEC cells and in mouse ileal tissue. The addition of recombinant TGF-β1 (rTGF-β) prevented TcdA-induced apoptosis/necrosis and restored proliferation and repair activity in IEC-6 cells in the presence of TcdA. Together, these data show that TcdA induces TGF-β1 signaling pathway activation and suggest that this pathway might play a protective role against the effect of C. difficile-toxin.