One of the striking observations in the IL-17/IL-22 axis in

our experimental model of DENV-2 infection is the fact that infected IL-22−/− mice presented increased production of IL-17A in the spleen and liver, and neutralization of IL-17A in these mice reverted the worsened phenotype observed in mice lacking IL-22. Other studies have addressed the cross-talk between IL-17A and IL-22 production. Besnard et al.[132] showed that IL-22 may regulate the expression and pro-inflammatory properties of IL-17A in allergic lung inflammation. Sonnenberg et al.[112] described that IL-17A could suppress IL-22 expression in Th17 cells after bleomycin-induced lung inflammation and fibrosis. Although a selleck reciprocal regulation RG7204 supplier of IL-17A and IL-22 is observed in vivo, the underlying cellular and molecular mechanisms that may affect the functional properties of these cytokines in distinct peripheral tissues are yet to be described. Therefore, IL-22 seems to counterbalance the

production of IL-17A in experimental severe dengue infection. Pro-inflammatory mediators produced by epithelial cells in response to IL-17A are neutrophil- and granulocyte-attracting chemokines (i.e. CXCL1, CXCL2), IL-6 and several growth factors.[13-15] Neutrophil accumulation and activation are increased in DENV infection, so this could be an important function for IL-17A in this disease. In addition, IL-17A expression is markedly reduced in the spleens of iNKT-cell-deficient mice (Jα18−/−) during infection (R. Guabiraba, J. Renneson, and F. Trottein, unpublished data). The close association of iNKT Histone demethylase cells and the production of IL-17 or IL-22 in experimental DENV infection might require further investigation. Although thrombocytopenia is observed

in mild and severe forms of DENV infection, the role of platelet activation in dengue pathogenesis has not been fully elucidated. Hottz et al.[133] hypothesize that platelets have major roles in inflammatory amplification and increased vascular permeability during severe forms of dengue. They reported an increased expression of IL-1β in platelets and platelet-derived microparticles from patients with dengue or after platelet exposure to dengue virus in vitro. Further, DENV infection led to microparticle release through mechanisms dependent on NLRP3 inflammasome activation and caspase-1-dependent IL-1β secretion by platelets. Inflammasome activation and platelet shedding of IL-1β-rich microparticles correlated with signs of increased vascular permeability. Moreover, microparticles from DENV-stimulated platelets induced enhanced permeability in vitro in an IL-1-dependent manner.