SARS-CoV-2 Spike protein triggers gut impairment since mucosal barrier to innermost layers: From basic science to clinical relevance.

Studies have reported the occurrence of gastrointestinal (GI) symptoms, primarily diarrhea, in COVID-19. However, the pathobiology regarding COVID-19 in the GI tract remains limited. This work aimed to evaluate SARS-CoV-2 Spike protein interaction with gut lumen in different experimental approaches. Here, we present a novel experimental model with the inoculation of viral protein in the murine jejunal lumen, in vitro approach with human enterocytes, and molecular docking analysis. Spike protein led to increased intestinal fluid accompanied by Cl- secretion, followed by intestinal edema, leukocyte infiltration, reduced glutathione levels, and increased cytokine levels [interleukin (IL)-6, tumor necrosis factor-α, IL-1ß, IL-10], indicating inflammation. Additionally, the viral epitope caused disruption in the mucosal histoarchitecture with impairment in Paneth and goblet cells, including decreased lysozyme and mucin, respectively. Upregulation of toll-like receptor 2 and toll-like receptor 4 gene expression suggested potential activation of local innate immunity. Moreover, this experimental model exhibited reduced contractile responses in jejunal smooth muscle. In barrier function, there was a decrease in transepithelial electrical resistance and alterations in the expression of tight junction proteins in the murine jejunal epithelium. Additionally, paracellular intestinal permeability increased in human enterocytes. Finally, in silico data revealed that the Spike protein interacts with cystic fibrosis transmembrane conductance regulator (CFTR) and calcium-activated chloride conductance (CaCC), inferring its role in the secretory effect. Taken together, all the events observed point to gut impairment, affecting the mucosal barrier to the innermost layers, establishing a successful experimental model for studying COVID-19 in the GI context.

Electronic von Frey as an objective assessment tool for oxaliplatin-induced peripheral neuropathy: A prospective longitudinal study.

OBJECTIVE: There is wide discrepancy on how to perform clinical assessment of oxaliplatin-induced peripheral neuropathy. In this scenario, the Electronic von Frey (EVF), which evaluates pain objectively based upon mechanical pain thresholds (MPTs), may be a valuable tool. The present study aims to quantify hyperalgesia in the hands and feet of patients treated with oxaliplatin and to propose a novel method to classify the degree of neurotoxicity using EVF-derived measures as cut-off points. METHODS: This is a prospective cohort study including 46 patients treated for colorectal cancer with the FLOX regimen. Before each oxaliplatin administration, patients were evaluated with the Acute and Chronic Neuropathy Questionnaire, Oxaliplatin-Specific Neurotoxicity Scale and National Cancer Institute Common Terminology Criteria for Adverse Events scale. Also, objective pain assessment with the EVF was performed. RESULTS: For both upper and lower extremities, EVF was shown to correlate well with patients' symptoms and functional impairment, as assessed by subjective scales. Also, when cut-off MPT variations were determined for diagnosis of neurotoxicity grade 2 or 3, the method showed good sensitivity and specificity. CONCLUSION: Electronic von Frey is a noninvasive and easy-to-perform objective method with potential to supplement the current assessment tools for oxaliplatin-induced peripheral neuropathy, which are mostly subjective.

What would Sérgio Ferreira say to your physician in this war against COVID-19: How about kallikrein/kinin system?

Coronavirus disease 2019 (COVID-19) is an infectious disease with fast spreading all over the world caused by the SARS-CoV-2 virus which can culminate in a severe acute respiratory syndrome by the injury caused in the lungs. However, other organs can be also damaged. SARS-CoV-2 enter into the host cells using the angiotensin-converting enzyme 2 (ACE2) as receptor, like its ancestor SARS-CoV. ACE2 is then downregulated in lung tissues with augmented serum levels of ACE2 in SARS-CoV-2 patients. Interestingly, ACE2+ organs reveal the symptomatic repercussions, which are signals of the infection such as dry cough, shortness of breath, heart failure, liver and kidney damage, anosmia or hyposmia, and diarrhea. ACE2 exerts a chief role in the renin-angiotensin system (RAS) by converting angiotensin II to angiotensin-(1-7) that activates Mas receptor, inhibits ACE1, and modulates bradykinin (BK) receptor sensitivity, especially the BK type 2 receptor (BKB2R). ACE2 also hydrolizes des-Arg9-bradykinin (DABK), an active BK metabolite, agonist at BK type 1 receptors (BKB1R), which is upregulated by inflammation. In this opinion article, we conjecture a dialogue by the figure of Sérgio Ferreira which brought together basic science of classical pharmacology and clinical repercussions in COVID-19, then we propose that in the course of SARS-CoV-2 infection: i) downregulation of ACE2 impairs the angiotensin II and DABK inactivation; ii) BK and its metabolite DABK seems to be in elevated levels in tissues by interferences in kallikrein/kinin system; iii) BK1 receptor contributes to the outbreak and maintenance of the inflammatory response; iv) kallikrein/kinin system crosstalks to RAS and coagulation system, linking inflammation to thrombosis and organ injury. We hypothesize that targeting the kallikrein/kinin system and BKB1R pathway may be beneficial in SARS-CoV-2 infection, especially on early stages. This route of inference should be experimentally verified by SARS-CoV-2 infected mice.

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.

Development and validation of the experimental wound assessment tool (EWAT) for pressure ulcer in laboratory animals.

INTRODUCTION: In studies with experimental models of pressure ulcer, until date, there is no validated instrument to assess the various visual aspects of the healing process. Measure of wound area is the most used method for this purpose. Thus, we aimed to develop and validate a visual assessment tool for the evaluation of healing in experimental models of pressure ulcer. METHODS: The Experimental Wound Assessment Tool (EWAT) was developed based on tools used in clinical practice. The tool was validated using 50 photographs of wound induced by a noninvasive pressure ulcer model in Swiss mice. Five judges performed the Content Validity and 3 raters evaluated the photos by EWAT. Items with the Content Validity Index score lower than 0.8 were modified in accordance to the suggestions of the judges. RESULTS: The EWAT showed moderate to high reliability, whilst the Concurrent Validity Test obtained good to high results, demonstrating a significantly strong positive correlation between the analyses of the raters. Moreover, it was shown to have high correlation with the clinical Photographic Wound Assessment Tool. DISCUSSION: EWAT showed good/excellent results in all the validation tests, showing it to be a good tool to evaluate wound healing process in animal models of pressure ulcer and being recommended for assessment of wound healing in small experimental animals.

Gabapentin attenuates neuropathic pain and improves nerve myelination after chronic sciatic constriction in rats.

Gabapentin (GBP) is an anti-convulsive drug often used as analgesic to control neuropathic pain. This study aimed at evaluating oral GBP treatment (30, 60, 120 mg/kg, 60 min prior to chronic constriction of the sciatic nerve (CCSN) along 15-day treatment post-injury, 12 h/12 h) by monitoring spontaneous and induced-pain behaviors in Wistar rats on 5th and 15th days post-injury during early neuropathic events. CCSN animals receiving saline were used as controls. Another aim of this study was to evaluate GBP effects on myelin basic protein (MBP) on the 5th and 15th days post-injury and nerve morphology by transmission electron microscopy to address nerve regeneration. On the 5th and 15th days, GBP (60 mg/kg) reduced neuropathic pain behaviors (scratching and biting) in the ipsilateral paw and alleviated mechanical allodynia in comparison with the neuropathic saline group. GBP significantly increased climbing and rearing behaviors in CCSN and CCSN-free animals suggesting increased motor activity rather than sedation. We found three-fold significant increase in MBP expression by western blots on the 15th day when compared to controls. In addition, GPB (60 mg/kg) improved nerve axonal, fiber and myelin area 15 days post-surgery. In conclusion, GBP alleviated mechanical and thermal allodynia and spontaneous pain-related behaviors and improved later nerve morphology. Our findings suggest that GBP improve nerve remyelination after chronic constriction of the sciatic nerve.

Effects of electroacupuncture on experimental periodontitis in rats.

BACKGROUND: Acupuncture has shown the capability of modulating the immuno-inflammatory response of the host. This study aims to evaluate the effects of electroacupuncture (EA) on ligature-induced periodontitis in rats. METHODS: Thirty-two animals were divided into four groups: 1) control; 2) experimental periodontitis (EP); 3) sham-treated (EP/EA-sham); and 4) treated with EA (EP/EA). For the EP groups, a ligature was placed around the right mandibular first molars at day 1. Sessions of EA or EA-sham were assigned every other day. For EA treatment, large intestine meridian points LI4 and LI11 and stomach meridian points ST36 and ST44 were used. EA-sham was performed in off-meridian points. Animals were euthanized at day 11. Histomorphometric and microtomographic analyses were performed. Immunolabeling patterns for the receptor activator of nuclear factor κB ligand (RANKL), osteoprotegerin (OPG), and tartrate-resistant acid phosphatase (TRAP) were assessed. Expressions of interleukin (IL)-1ß, matrix metalloproteinase (MMP)-8, IL-6, and cyclooxygenase (COX)-2 messenger RNAs (mRNAs) were evaluated by quantitative reverse transcription-polymerase chain reaction. Data were analyzed statistically (P <0.05, analysis of variance). RESULTS: Histomorphometric and microtomographic analyses demonstrated that group EP/EA presented reduced alveolar bone loss when compared to group EP (P <0.05). Reduced RANKL immunolabeling and fewer TRAP-positive multinucleated cells were observed in the EA-treated group in relation to group EP. No differences were observed in OPG expression among groups. EA treatment decreased the genic expression of IL-1ß and MMP-8 (P <0.05), increased the mRNA expression of IL-6 (P <0.05), and did not modify the genic expression of COX-2 in animals with EP (P >0.05). CONCLUSION: It can be concluded that EA reduced periodontal tissue breakdown and the expression of some proinflammatory mediators and a proresorptive factor in EP in rats.

Role of NMDA receptors in the trigeminal pathway, and the modulatory effect of magnesium in a model of rat temporomandibular joint arthritis.

Temporomandibular joint (TMJ) arthritis is a common cause of orofacial pain. In the present study, the modulatory effects of N-methyl-d-aspartate receptors (NMDA-Rs) and magnesium were investigated in TMJ arthritis hypernociception. Male Wistar rats received an intra-articular injection of carrageenan (Cg) in the TMJ, and mechanical hypernociception was measured. The NMDA-R antagonist, MK-801, and magnesium chloride (MgCl2 ) were administered before arthritis induction. Magnesium deficiency was promoted by feeding rats a synthetic magnesium-free diet for 9 d before injection of Cg. The Cg induced mechanical hypernociception that lasted for 120 h. MK-801 inhibited this hypernociceptive state. MgCl2 pretreatment prevented Cg-induced hypernociception and altered the nociceptive threshold in the absence of Cg. Magnesium deficiency increased hypernociception and induced spontaneous hypernociceptive behavior. TMJ arthritis increased the expression of mRNA for all NMDA-R subunits and immunostaining of phosphorylated NR1 (phospho-NR1). MgCl2 inhibited expression of NR2B mRNA and phospho-NR1 immunostaining and increased expression of NR3 mRNA. Magnesium deficiency increased expression of both NR1 and NR3 mRNAs and phospho-NR1 immunostaining in the trigeminal subnucleus caudalis. We found that magnesium modulates nociceptive behavior and induces NMDA-R subunit rearrangement in the subnucleus caudalis. The present results may lead to a better understanding of central processing in the nociceptive trigeminal pathway and the development of new approaches to treat orofacial pain with a TMJ origin.

Oral gabapentin treatment accentuates nerve and peripheral inflammatory responses following experimental nerve constriction in Wistar rats.

Gabapentin (GBP) is an anti-convulsive drug often used as analgesic to control neuropathic pain. This study aimed at evaluating whether oral GBP treatment could improve nerve inflammation response after sciatic nerve constriction in association with selected pain and motor spontaneous behavior assessments in Wistar rats. We evaluated nerve myeloperoxidase (MPO) and inflammatory cytokines on the 5th day post-injury, time in which nerve inflammation is ongoing. In addition, the role of GBP on carrageenan-induced paw edema and peritoneal cell migration was analyzed. GBP was given by gavage at doses of 30, 60 and 120mg/kg, 60min prior to chronic constriction of the sciatic nerve (CCSN) and during 5 days post-injury, 12/12h. CCSN animals treated with saline were used as controls and for behavioral and inflammation assessments untreated sham-operated rats were also used. On the 5th day, GBP (60 and 120mg/kg) alleviated heat-induced hyperalgesia and significantly increased delta walking scores in CCSN animals, the latter suggesting excitatory effects rather than sedation. GBP (60mg/kg) significantly increased nerve MPO, TNF-α, and IL-1ß levels, comparing with the saline group. GBP (120mg/kg) reduced the anti-inflammatory cytokine IL-10 nerve levels compared with the CCSN saline group. Furthermore, GBP (60 and 120mg/kg) increased carrageenan-induced paw edema and peritoneal macrophage migration compared with the CCSN saline group. Altogether our findings suggest that GBP accentuates nerve and peripheral inflammatory response, however confirmed its analgesic effect likely due to an independent CNS-mediated mechanism, and raise some concerns about potential GBP inflammatory side effects in widespread clinical use.

Protective mechanisms of simvastatin in experimental periodontal disease.

BACKGROUND: Simvastatin is a cholesterol-lowering drug whose pleiotropic effects may have a therapeutic impact on bone. This study evaluates the effect of simvastatin on rats subjected to experimental periodontal disease. METHODS: Periodontitis was induced by ligature placement around the maxillary left second molar of rats for 11 days. Groups of six animals received oral saline or simvastatin (3, 10, and 30 mg/kg/day) until sacrifice on day 11. Alveolar bone loss was determined by macroscopic and histologic examination. The serum levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), and total alkaline phosphatase (TAP) were evaluated. Gingival myeloperoxidase activity and gingival levels of interleukin-1ß (IL-1ß), tumor necrosis factor-α, IL-10, reduced glutathione, malonaldehyde, and nitrate/nitrite were analyzed to investigate oxidative stress and inflammation. Expression of inducible nitric oxide synthase (iNOS), matrix metalloproteinases 1 and 8 (MMP-1 and -8), bone morphogenetic protein-2 (BMP-2), receptor activator of nuclear factor κB (RANK), RANK ligand (RANKL), and osteoprotegerin (OPG) were also investigated by immunohistochemistry to assess bone turnover and metabolism. Immunofluorescence microscopy was used to confirm the expression of RANKL in rats' maxillae. RESULTS: Treatment with simvastatin improved alveolar bone loss within all of the parameters studied, thus demonstrating anti-inflammatory and antioxidant activity. Simvastatin reduced expression of iNOS, MMP-1 and -8, RANK, and RANKL and increased BMP-2 and OPG levels in the periodontal tissue. Simvastatin (30 mg/kg) increased TAP activity on day 11 compared with the saline group. No differences were found in the levels of AST and ALT in any of the groups studied. CONCLUSION: The present data suggest that simvastatin prevents inflammatory bone resorption in experimental periodontitis, which may be mediated by its anti-inflammatory and antioxidant properties.

Proinflammatory activity of an alginate isolated from Sargassum vulgare.

Alginates are unbranched polymers of polysaccharide presented as the structural components of marine brown algae. The proinflammatory activity of SVHV, an alginate isolated from Sargassum vulgare, was investigated using models of paw edema, mast cells degranulation and neutrophil migration in vivo. SVHV induced a dose dependent paw edema, with a peak at 2 h, associated with an increased myeloperoxidase activity and production of TNF-α and IL-1ß. Pharmacological modulators, remarkably dexamethasone and indomethacin, inhibited the edema. SVHV (1.0 mg) also led to a significant induction of neutrophil migration in the peritoneal cavity of rats. This neutrophil migration was significantly reduced by peritoneal resident macrophages depletion, but was not affected by the depletion of mast cells. Our data suggest that SVHV has proinflammatory activity dependent of the activation of resident cells, being the macrophages the main cells involved.

Protein fraction of Calotropis procera latex protects against 5-fluorouracil-induced oral mucositis associated with downregulation of pivotal pro-inflammatory mediators.

Oral mucositis is an important dose-limiting and costly side effect of cancer chemotherapy. Soluble proteins obtained of the latex of Calotropis procera have been extensively characterized as anti-inflammatory in different experimentally induced inflammatory conditions, including arthritis and sepsis. In this study, the phytomodulatory laticifer proteins (LP) were challenged to regress the inflammatory events associated with 5-fluorouracil-induced oral mucositis. We also evaluated the expression of pro-inflammatory cytokines and inducible enzymes, such as cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS). Oral mucositis was induced in hamsters by two injections of 5-fluorouracil (5-FU; 60 and 40 mg/kg, i.p., on experimental days 1 and 2, respectively). LP (5 mg/kg, i.p.) was injected 24 h before and 24 h after mechanical trauma of the cheek pouches. A normal control group received only saline. On day 10, the animals were sacrificed, and the cheek pouches were excised for macroscopic and histopathological analysis, myeloperoxidase activity measurement, and immunohistochemical assessment of tumor necrosis factor-α (TNF-α), interleukin-1ß (IL-1ß), iNOS, and COX-2. LP significantly inhibited macroscopic histopathological scores and myeloperoxidase activity compared with the 5-FU control group. 5-Fluorouracil also induced marked immunostaining of TNF-α, IL-1ß, iNOS, and COX-2 on inflamed conjunctive and epithelial tissue compared with the normal control group. Such damage was significantly inhibited (p < 0.05) by LP treatment compared with the 5-FU group. These findings demonstrate an anti-inflammatory effect of LP on 5-FU-induced oral mucositis. The protective mechanism appears to involve inhibition of the expression of iNOS, COX-2, TNF-α, and IL-1ß.

Involvement of nitric oxide on the pathogenesis of irinotecan-induced intestinal mucositis: role of cytokines on inducible nitric oxide synthase activation.

PURPOSE: Intestinal mucositis and the closely associated diarrhea are common costly side effects of irinotecan. Cytokine modulators, such as thalidomide and pentoxifylline, are found capable of attenuating intestinal mucositis progression. Nitric oxide (NO) seems to be a key mediator of the antineoplastic drug toxicity. The aim of this study was to investigate the role of NO on the pathogenesis of intestinal mucositis, as well as the participation of cytokines upon inducible nitric oxide synthase (iNOS) expression in irinotecan-induced intestinal mucositis. METHODS: iNOS-knockout (iNOS(-/-)) and C57BL/6 (WT, wild type) animals (n = 5-6) were given either saline or irinotecan (60 mg/kg i.p for 4 days), with or without pretreatment with aminoguanidine (50 mg/kg s.c.), thalidomide (60 mg/kg s.c), infliximab (5 mg/kg i.v.), or pentoxifylline (1.7 mg/kg s.c). On day 5, diarrhea was assessed, and following euthanasia, proximal intestinal samples were obtained for myeloperoxidase (MPO) and iNOS activity, morphometric analysis, western blot and immunohistochemistry to iNOS, cytokine dosage, and for in vitro evaluation of gut contractility. RESULTS: Irinotecan induced severe diarrhea and intestinal smooth muscle over-contractility, accompanied with histopathological changes. Additionally, increased MPO and iNOS activity and iNOS immunoexpression were found in WT animals treated with irinotecan. The rise in MPO, smooth muscle over-contractility, and diarrhea were abrogated in aminoguanidine-treated and iNOS(-/-) mice. Moreover, through western blot, we verified that infliximab and pentoxifylline significantly inhibited irinotecan-induced iNOS expression. In addition, cytokine concentration was found only partially decreased in irinotecan-treated iNOS(-/-) mice when compared with wild-type animals that were given irinotecan. CONCLUSIONS: This study suggests a role of nitric oxide in the pathogenesis of irinotecan-induced intestinal mucositis and also provides evidence for the participation of cytokines on iNOS induction.

Interleukin-4 modulates the inflammatory response in ifosfamide-induced hemorrhagic cystitis.

We investigated whether interleukin-4 (IL-4) is present and capable of reducing inflammatory changes seen in ifosfamide-induced hemorrhagic cystitis. Male Swiss mice were treated with saline or ifosfamide alone or ifosfamide with the classical protocol with mesna and analyzed by changes in bladder wet weight (BWW), macroscopic and microscopic parameters, exudate, and hemoglobin quantification. In other groups, IL-4 was administered intraperitoneally 1 h before ifosfamide. In other experimental groups, C57BL/6 WT (wild type) and C57BL/6 WT IL-4 (-/-) knockout animals were treated with ifosfamide and analyzed for changes in BWW. Quantification of bladder IL-4 protein by ELISA in control, ifosfamide-, and mesna-treated groups was performed. Immunohistochemistry to tumor necrosis factor-alpha (TNF-α) and interleukin-1 beta (IL-1ß) as well as protein identification by Western blot assay for inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) was carried out on ifosfamide- and IL-4-treated animals. In other experimental groups, antiserum against IL-4 was given 30 min before ifosfamide. In IL-4-treated animals, the severity of hemorrhagic cystitis was significantly milder than in animals treated with ifosfamide only, an effect that was reverted with serum anti-IL-4. Moreover, knockout animals for IL-4 (-/-) exhibit a worse degree of inflammation when compared to C57BL/6 wild type. Exogenous IL-4 also attenuated TNF-α, IL-1ß, iNOS, and COX-2 expressions in ifosfamide-treated bladders. IL-4, an anti-inflammatory cytokine, attenuates the inflammation seen in ifosfamide-induced hemorrhagic cystitis.

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.

Characterization and pharmacological evaluation of febrile response on zymosan-induced arthritis in rats.

The present study investigated the febrile response in zymosan-induced arthritis, as well as the increase in PGE(2) concentration in the cerebrospinal fluid (CSF), along with the effects of antipyretic drugs on these responses in rats. Zymosan intra-articularly injected at the dose of 0.5 mg did not affect the body core temperature (Tc) compared with saline (control), whereas at doses of 1 and 2 mg, zymosan promoted a flattened increase in Tc and declined thereafter. The dose of 4 mg of zymosan was selected for further experiments because it elicited a marked and long-lasting Tc elevation starting at 3 1/2 h, peaking at 5 1/2 h, and remaining until 10 h. This temperature increase was preceded by a decrease in the tail skin temperature, as well as hyperalgesia and edema in the knee joint. No febrile response was observed in the following days. In addition, zymosan-induced fever was not modified by the sciatic nerve excision. Zymosan increased PGE(2) concentration in the CSF but not in the plasma. Oral pretreatment with ibuprofen (5-20 mg/kg), celecoxib (1-10 mg/kg), dipyrone (60-240 mg/kg), and paracetamol (100-200 mg/kg) or subcutaneous injection of dexamethasone (0.25-1.0 mg/kg) dose-dependently reduced or prevented the fever during the zymosan-induced arthritis. Celecoxib (5 mg/kg), paracetamol (150 mg/kg), and dipyrone (120 mg/kg) decreased CSF PGE(2) concentration and fever during zymosan-induced arthritis, suggesting the involvement of PGE(2) in this response.

Role of cytokines (TNF-alpha, IL-1beta and KC) in the pathogenesis of CPT-11-induced intestinal mucositis in mice: effect of pentoxifylline and thalidomide.

INTRODUCTION: Irinotecan (CPT-11) is an inhibitor of DNA topoisomerase I and is clinically effective against several cancers. A major toxic effect of CPT-11 is delayed diarrhea; however, the exact mechanism by which the drug induces diarrhea has not been established. PURPOSE: Elucidate the mechanisms of induction of delayed diarrhea and determine the effects of the cytokine production inhibitor pentoxifylline (PTX) and thalidomide (TLD) in the experimental model of intestinal mucositis, induced by CPT-11. MATERIALS AND METHODS: Intestinal mucositis was induced in male Swiss mice by intraperitoneal administration of CPT-11 (75 mg/kg) daily for 4 days. Animals received subcutaneous PTX (1.7, 5 and 15 mg/kg) or TLD (15, 30, 60 mg/kg) or 0.5 ml of saline daily for 5 and 7 days, starting 1 day before the first CPT-11 injection. The incidence of delayed diarrhea was monitored by scores and the animals were sacrificed on the 5th and 7th experimental day for histological analysis, immunohistochemistry for TNF-alpha and assay of myeloperoxidase (MPO) activity, tumor necrosis factor-alpha (TNF-alpha), interleukin-1beta (IL-1beta) and KC ELISA. RESULTS: CPT-11 caused significant diarrhea, histopathological alterations (inflammatory cell infiltration, loss of crypt architecture and villus shortening) and increased intestinal tissue MPO activity, TNF-alpha, IL-1beta and KC level and TNF-alpha immuno-staining. PTX inhibited delayed diarrhea of mice submitted to intestinal mucositis and reduced histopathological damage, intestinal MPO activity, tissue level of TNF-alpha, IL-1beta and KC and TNF-alpha immuno-staining. TLD significantly reduced the lesions induced by CPT-11 in intestinal mucosa, decreased MPO activity, TNF-alpha tissue level and TNF-alpha immuno-staining, but did not reduce the severity of diarrhea. CONCLUSION: These results suggest an important role of TNF-alpha, IL-1beta and KC in the pathogenesis of intestinal mucositis induced by CPT-11.

Peripheral antinociceptive effect of pertussis toxin: activation of the arginine/NO/cGMP/PKG/ ATP-sensitive K channel pathway.

The aim of the present study was to determine the effect of pertussis toxin (PTX) on inflammatory hypernociception measured by the rat paw pressure test and to elucidate the mechanism involved in this effect. In this test, prostaglandin E(2) (PGE(2)) administered subcutaneously induces hypernociception via a mechanism associated with neuronal cAMP increase. Local intraplantar pre-treatment (30 min before), and post-treatment (5 min after) with PTX (600 ng/paw1, in 100 microL) reduced hypernociception induced by prostaglandin E(2) (100 ng/paw, in 100 microL, intraplantar). Furthermore, local intraplantar pre-treatment (30 min before) with PTX (600 ng/paw, in 100 microL) reduced hypernociception induced by DbcAMP, a stable analogue of cAMP (100 microg/paw, in 100 microL, intraplantar), which indicates that PTX may have an effect other than just G(i)/G(0) inhibition. PTX-induced analgesia was blocked by selective inhibitors of nitric oxide synthase (L-NMMA), guanylyl cyclase (ODQ), protein kinase G (KT5823) and ATP-sensitive K(+) channel (Kir6) blockers (glybenclamide and tolbutamide). In addition, PTX was shown to induce nitric oxide (NO) production in cultured neurons of the dorsal root ganglia. In conclusion, this study shows a peripheral antinociceptive effect of pertussis toxin, resulting from the activation of the arginine/NO/cGMP/PKG/ATP-sensitive K(+) channel pathway.

Anti-nociceptive effect of thalidomide on zymosan-induced experimental articular incapacitation.

The anti-nociceptive effect of thalidomide on zymosan-induced articular knee joint incapacitation in rats was investigated. Thalidomide (5-45 mg/kg), given 30 min before but not 2 h after the intra-articular injection of zymosan, inhibited the nociceptive response in a dose-dependent manner. Furthermore, thalidomide pretreatment significantly reduced the concentration of tumor necrosis factor-alpha (TNF-alpha, -68.4%) in the exudate of zymosan-injected joints, but not those of interleukin-1beta, interleukin-6, CINC-1 or interleukin-10. The expression of TNF-alpha, determined by immunohistochemical staining, in synovial tissues obtained from articular joints injected with zymosan was also inhibited by thalidomide pretreatment. The anti-nociceptive effect of thalidomide was not reversed by the co-administration of an opioid receptor antagonist, naloxone, suggesting that endogenous opioids do not mediate the anti-nociceptive effect of thalidomide in this model. In conclusion, the anti-nociceptive activity of thalidomide in zymosan-induced articular incapacitation is associated with the inhibition of TNF-alpha by resident synovial cells.