Riboflavin did not provide anti-inflammatory or antioxidant effects in an experimental model of sepsis

We aimed to evaluate whether the administration of riboflavin to septic animals reduces inflammation, oxidative stress, organ dysfunction, and mortality. C57BL/6 mice, 6-8 weeks old, were allocated to the study group (polymicrobial sepsis induced by cecal ligation and puncture (CLP) + antibiotic + iv riboflavin), control (CLP + antibiotic + iv saline), or naïve (non-operated controls). Serum concentrations of alanine aminotransferase (ALT), creatine kinase-MB (CK-MB), urea, and creatinine, and markers of inflammation [interleukin (IL)-6, tumor necrosis factor (TNF)-α, keratinocyte-derived chemokine (KC), and macrophage inflammatory protein (MIP)-2)], and oxidative stress (malondialdehyde (MDA) were measured 12 h after the experiment. Animal survival rates were calculated after 7 days. Means between groups were compared using linear regression models adjusted under the Bayesian approach. No significant difference was observed between control and study groups in serum concentrations of IL-6 (95% credible interval) (-0.35 to 0.44), TNF-α (-15.7 to 99.1), KC (-0.13 to 0.05), MIP-2 (-0.84 to 0.06), MDA (-1.25 to 2.53), or ALT (-6.6 to 11.5). Serum concentrations of CK-MB (-145.1 to -30.1), urea (-114.7 to -15.1), and creatinine (-1.14 to -0.01) were higher in the study group. Survival was similar in both groups (P=0.8). Therefore, the use of riboflavin in mice undergoing sepsis induced by CLP did not reduce inflammation, oxidative stress, organ dysfunction, or mortality compared with placebo.

The signal transducer and activator of transcription 6 (STAT-6) mediates Th2 inflammation and tissue damage in a murine model of peanut-induced food allergy

Introduction: Food allergies are inflammatory conditions mediated by Th2 and probably STAT-6 dependent immune responses. Objective and design: Here we investigated the role of Signal Transducer and Activator of Transcription 6 (STAT-6) in development of inflammation in peanut allergy. Methods: To induce food allergy, wild-type (WT) and mice deficient for STAT-6 (Stat6-/-) were sensitized with peanut proteins and challenged with peanut seeds. Results: WT animals lost weight and refused the peanut diet, in contrast to Stat6-/- mice, which had a better maintenance of body weight and more regular seeds' consumption. The augmented peanut-specific IgG, IgG1 and IgE in the allergic WT was abolished in Stat6-/- animals that also presented increased IgG2a. There was an overall reduction in the gut mediators in the absence of STAT-6, including those related to inflammatory and Th2 responses, in contrast to a rising counter regulatory and Th1 reaction in Stat-6-/- mice. These animals had IFN-γ and IL-10 similar to WT after the four-week challenge. Most interestingly, Stat-6-/- mice had no intestinal damage, in contrast to WT animals, which had inflammatory infiltrate, tissue destruction, epithelial exulceration, edema, congestion and loss of villous architecture in the small gut segments. Conclusions: STAT-6 plays an important role in the establishment of the Th2 inflammatory responses and intestinal damage in peanut allergy

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An interleukin-33/ST2 signaling deficiency reduces overt pain-like behaviors in mice

Interleukin (IL)-33, the most recent member of the IL family of cytokines, signals through the ST2 receptor. IL-33/ST2 signaling mediates antigen challenge-induced mechanical hyperalgesia in the joints and cutaneous tissues of immunized mice. The present study asked whether IL-33/ST2 signaling is relevant to overt pain-like behaviors in mice. Acetic acid and phenyl-p-benzoquinone induced significant writhing responses in wild-type (WT) mice; this overt nociceptive behavior was reduced in ST2-deficient mice. In an antigen-challenge model, ST2-deficient immunized mice had reduced induced flinch and licking overt pain-like behaviors. In the formalin test, ST2-deficient mice also presented reduced flinch and licking responses, compared with WT mice. Naive WT and ST2-deficient mice presented similar responses in the rota-rod, hot plate, and electronic von Frey tests, indicating no impairment of motor function or alteration in basal nociceptive responses. The results demonstrate that IL-33/ST2 signaling is important in the development of overt pain-like behaviors.

The role of PKA and PKCepsilon pathways in prostaglandin E2-mediated hypernociception.

BACKGROUND AND PURPOSE: Protein kinase (PK) A and the epsilon isoform of PKC (PKCepsilon) are involved in the development of hypernociception (increased sensitivity to noxious or innocuous stimuli) in several animal models of acute and persistent inflammatory pain. The present study evaluated the contribution of PKA and PKCepsilon to the development of prostaglandin E(2) (PGE(2))-induced mechanical hypernociception. EXPERIMENTAL APPROACH: Prostaglandin E(2)-induced mechanical hypernociception was assessed by constant pressure rat paw test. The activation of PKA or PKCepsilon was evaluated by radioactive enzymic assay in the dorsal root ganglia (DRG) of sensory neurons from the hind paws. KEY RESULTS: Hypernociception induced by PGE(2) (100 ng) by intraplantar (i.pl.) injection, was reduced by i.pl. treatment with inhibitors of PKA [A-kinase-anchoring protein St-Ht31 inhibitor peptide (AKAPI)], PKCepsilon (PKCepsilonI) or adenylyl cyclase. PKA activity was essential in the early phase of the induction of hypernociception, whereas PKC activity was involved in the maintenance of the later phase of hypernociception. In the DRG (L4-L5), activity of PKA increased at 30 min after injection of PGE(2) but PKC activity increased only after 180 min. Moreover, i.pl. injection of the catalytic subunit of PKA induced hypernociception which was markedly reduced by pretreatment with an inhibitor of PKCepsilon, while the hypernociception induced by paw injection of PKCepsilon agonist was not affected by an inhibitor of PKA (AKAPI). CONCLUSIONS AND IMPLICATIONS: Taken together, these findings are consistent with the suggestion that PKA activates PKCepsilon, which is a novel mechanism of interaction between these kinases during the development of PGE(2)-induced mechanical hypernociception.

Desenvolvimento de modelo de peritonite bacteriana para avaliação do tratamento mediante acesso laparotômico e video-laparoscópico

Introduction: The use of videolaparoscopy in the treatment of digestive diseases, associated with generalized peritonitis, is controverted. Objective: To develop a model of bacterial peritonitis for the evaluation of the treatments through laparotomy and through videolaparoscopy. Methods: Male Wistar rats were submitted to occlusion of the ceacum (CLP) on a rigid mold of 3mm diameter, followed by 14 punctures of the ceacum with a 15 x 10 needle. Six hours after the induction of peritonitis, the animals were treated by laparotomy or videolaparoscopy, while analysing blood cultures and the mortality rates. The treatment involved typhlectomy followed or no by peritoneal lavage with saline solution. Results: The mortality rate in one week, after CLP without treatment, was 90%. The blood cultures were positive in 80 to 100% of the animals after 3 hours, and in 60 to 80% after 24 hours, in the animals when treated with laparotomy without peritoneal lavage and in the animals treated through videolaparoscopy with or without peritoneal lavage. The mortality rate after laparotomy was 20%, whereas after videolaparoscopy it was 80%. Conclusion: The experimental model induced severe peritonitis, and the bactereamia associated with videolaparoscopy has a high mortality rate.

Introdução: O emprego do acesso videolaparoscópico no tratamento das afecções digestivas que cursam com peritonite generalizada é motivo de controvérsia. Objetivo: Desenvolver um modelo de peritonite bacteriana para avaliação do tratamento mediante acesso laparotômico e videolaparoscópico. Métodos: Ratos machos Wistar foram submetidos à ligadura de ceco (CLP) sob molde rígido de 3mm de diâmetro; na seqüência foram feitas 14 punções no ceco com agulha 15X10. Após 6 horas de indução da peritonite, os animais foram tratados mediante laparotomia ou videolaparoscopia e avaliados com base nas hemoculturas e na taxa de mortalidade. O tratamento consistiu de tiflectomia seguida ou não de lavagem da cavidade peritoneal com solução fisiológica. Resultado: A mortalidade após CLP sem tratamento foi de 90% em uma semana. As hemoculturas positivas para bactérias após 3 horas variaram de 80 a 100% e após 24 horas de 60 a 80%, nos animais tratados com laparotomia sem lavagem do peritôneo e com videolaparoscopia seguida ou não de lavagem peritoneal. Todavia, a mortalidade após laparotomia foi de 20% e após videolaparoscopia foi de 80%. Conclusão: O modelo experimental desenvolvido induz a peritonite grave, e a bacteremia associada ao tratamento videolaparoscópico tem alta letalidade.