Present understanding of mediators and experimental models of sepsis

The author presents a reviewed description about the inflammatory response during sepsis, viewing the mainly mediators in this process, as cytokines and nitric oxide, and the role of these mediators in the evolution of this disease. This aspect is not so linear and simple, because the importance of each mediators depend on experimental model, animal species and sepsis stage. Furthermore, it will be reviewed the principal experimental models used for the study of sepsis, discussing the advantage of each one and their contribution for the comprehension of the disease. It has no doubt about the importance of all experimental model of sepsis and septic shock, however it is crucial to distinguish the good and bad features about each model, in order to concern successful results for clinic trials.A autora apresenta uma revisão sobre a resposta inflamatória durante a sepse, abordando os principais mediadores envolvidos no processo, tais como citocinas e óxido nítrico, bem como o papel desses mediadores na evolução da doença. Esse aspecto abordado não é tão simples e pontual, pois a relevância desses mediadores inflamatórios, na sepse, varia de acordo com muitos fatores, entre eles, com o modelo experimental utilizado, a espécie animal e o estágio da doença. Ainda, serão revisados os modelos experimentais mais utilizados para o estudo da sepse, discutindo-se as vantagens de cada modelo e a sua contribuição para a compreensão da doença. Não há dúvida que os modelos experimentais, utilizados hoje em dia, contribuem bastante para o entendimento de sepse e choque séptico. Entretanto, é importante saber discernir os pontos fortes e fracos do modelo, possibilitando uma real extensão dos resultados experimentais para testes clínicos

Pleiotropic antifibrotic actions of aspirin-triggered resolvin D1 in the lungs

Introduction: Pulmonary fibrosis is a destructive, progressive disease that dramatically reduces life quality of patients, ultimately leading to death. Therapeutic regimens for pulmonary fibrosis have shown limited benefits, hence justifying the efforts to evaluate the outcome of alternative treatments. Methods: Using a mouse model of bleomycin (BLM)-induced lung fibrosis, in the current work we asked whether treatment with pro-resolution molecules, such as pro-resolving lipid mediators (SPMs) could ameliorate pulmonary fibrosis. To this end, we injected aspirin-triggered resolvin D1 (7S,8R,17R-trihydroxy-4Z,9E,11E,13Z,15E19Z-docosahexaenoic acid; ATRvD1; i.v.) 7 and 10 days after BLM (intratracheal) challenge and samples were two weeks later. Results and discussion: Assessment of outcome in the lung tissues revealed that ATRvD1 partially restored lung architecture, reduced leukocyte infiltration, and inhibited formation of interstitial edema. In addition, lung tissues from BLM-induced mice treated with ATRvD1 displayed reduced levels of TNF-α, MCP-1, IL-1-β, and TGF-β. Of further interest, ATRvD1 decreased lung tissue expression of MMP-9, without affecting TIMP-1. Highlighting the beneficial effects of ATRvD1, we found reduced deposition of collagen and fibronectin in the lung tissues. Congruent with the anti-fibrotic effects that ATRvD1 exerted in lung tissues, α-SMA expression was decreased, suggesting that myofibroblast differentiation was inhibited by ATRvD1. Turning to culture systems, we next showed that ATRvD1 impaired TGF-β-induced fibroblast differentiation into myofibroblast. After showing that ATRvD1 hampered extracellular vesicles (EVs) release in the supernatants from TGF-β-stimulated cultures of mouse macrophages, we verified that ATRvD1 also inhibited the release of EVs in the bronco-alveolar lavage (BAL) fluid of BLM-induced mice. Motivated by studies showing that BLM-induced lung fibrosis is linked to angiogenesis, we asked whether ATRvD1 could blunt BLM-induced angiogenesis in the hamster cheek pouch model (HCP). Indeed, our intravital microscopy studies confirmed that ATRvD1 abrogates BLM-induced angiogenesis. Collectively, our findings suggest that treatment of pulmonary fibrosis patients with ATRvD1 deserves to be explored as a therapeutic option in the clinical setting.Fil: Guilherme, Rafael F.. Universidade Federal do Rio de Janeiro; BrasilFil: Silva, José Bruno N.F.. Universidade Federal do Rio de Janeiro; Brasil. Universidade Federal do Tocantins; BrasilFil: Waclawiack, Ingrid. Universidade Federal do Rio de Janeiro; BrasilFil: Fraga Junior, Vanderlei S.. Universidade Federal do Rio de Janeiro; BrasilFil: Nogueira, Thaís O.. Universidade Federal do Rio de Janeiro; BrasilFil: Pecli, Cyntia. Universidade Federal do Rio de Janeiro; BrasilFil: Araújo Silva, Carlla A.. Universidade Federal do Rio de Janeiro; BrasilFil: Magalhães, Nathalia S.. Ministerio de Salud de Brasil. Fundación Oswaldo Cruz. Instituto Oswaldo Cruz;Fil: Lemos, Felipe S.. Ministerio de Salud de Brasil. Fundación Oswaldo Cruz. Instituto Oswaldo Cruz;Fil: Bulant, Carlos Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil; ArgentinaFil: Blanco, Pablo Javier. Laboratório Nacional para Computação Científica; BrasilFil: Serra, Rafaela. Universidade Federal do Rio de Janeiro; BrasilFil: Svensjö, Erik. Universidade Federal do Rio de Janeiro; BrasilFil: Scharfstein, Júlio. Universidade Federal do Rio de Janeiro; BrasilFil: Moraes, João A.. Universidade Federal do Rio de Janeiro; BrasilFil: Canetti, Claudio. Universidade Federal do Rio de Janeiro; BrasilFil: Benjamim, Claudia F.. Universidade Federal do Rio de Janeiro; Brasi

Purinergic P2Y12 Receptor Activation in Eosinophils and the Schistosomal Host Response

Identifying new target molecules through which eosinophils secrete their stored proteins may reveal new therapeutic approaches for the control of eosinophilic disorders such as host immune responses to parasites. We have recently reported the expression of the purinergic P2Y12 receptor (P2Y12R) in human eosinophils; however, its functional role in this cell type and its involvement in eosinophilic inflammation remain unknown. Here, we investigated functional roles of P2Y12R in isolated human eosinophils and in a murine model of eosinophilic inflammation induced by Schistosoma mansoni (S. mansoni) infection. We found that adenosine 5’-diphosphate (ADP) induced human eosinophils to secrete eosinophil peroxidase (EPO) in a P2Y12R dependent manner. However, ADP did not interfere with human eosinophil apoptosis or chemotaxis in vitro. In vivo, C57Bl/6 mice were infected with cercariae of the Belo Horizonte strain of S. mansoni. Analyses performed 55 days post infection revealed that P2Y12R blockade reduced the granulomatous hepatic area and the eosinophilic infiltrate, collagen deposition and IL-13/IL-4 production in the liver without affecting the parasite oviposition. As found for humans, murine eosinophils also express the P2Y12R. P2Y12R inhibition increased blood eosinophilia, whereas it decreased the bone marrow eosinophil count. Our results suggest that P2Y12R has an important role in eosinophil EPO secretion and in establishing the inflammatory response in the course of a S. mansoni infection

Emerging Role of HMGB1 in the Pathogenesis of Schistosomiasis Liver Fibrosis

In chronic schistosomiasis, liver fibrosis is linked to portal hypertension, which is a condition associated with high mortality and morbidity. High mobility group box 1 (HMGB1) was originally described as a nuclear protein that functions as a structural co-factor in transcriptional regulation. However, HMGB1 can also be secreted into the extracellular milieu under appropriate signal stimulation. Extracellular HMGB1 acts as a multifunctional cytokine that contributes to infection, injury, inflammation, and immune responses by binding to specific cell-surface receptors. HMGB1 is involved in fibrotic diseases. From a clinical perspective, HMGB1 inhibition may represent a promising therapeutic approach for treating tissue fibrosis. In this study, we demonstrate elevated levels of HMGB1 in the sera in experimental mice or in patients with schistosomiasis. Using immunohistochemistry, we demonstrated that HMGB1 trafficking in the hepatocytes of mice suffering from acute schistosomiasis was inhibited by Glycyrrhizin, a well-known HMGB1 direct inhibitor, as well as by DIC, a novel and potential anti-HMGB1 compound. HMGB1 inhibition led to significant downregulation of IL-6, IL4, IL-5, IL-13, IL-17A, which are involved in the exacerbation of the immune response and liver fibrogenesis. Importantly, infected mice that were treated with DIC or GZR to inhibit HMGB1 pro-inflammatory activity showed a significant increase in survival and a reduction of over 50% in the area of liver fibrosis. Taken together, our findings indicate that HMGB1 is a key mediator of schistosomotic granuloma formation and liver fibrosis and may represent an outstanding target for the treatment of schistosomiasis