Disseminated infection results in high morbidity and mortality despite treatment with

Disseminated infection results in high morbidity and mortality despite treatment with existing antifungal drugs. in this enhanced resistance. Subcutaneous air flow pouch and systemic candidiasis models exhibited that endogenous thrombospondin-1 enhances the early innate immune response against and promotes activation of inflammatory macrophages (inducible nitric oxide synthase+ IL-6high TNF-αhigh IL-10low) release of the chemokines MIP-2 JE MIP-1α and RANTES and CXCR2-driven polymorphonuclear leukocytes recruitment. However thrombospondin-1 inhibited the phagocytic capacity of inflammatory leukocytes and and hepatitis C computer virus infections and contribute to pathogenesis by promoting cellular invasion [10] and TGF-β1-mediated liver fibrosis [11] respectively. In addition TSP1 modulates expression of IL-6 and IL-10 by monocytes [12] and activation of latent TGF-β [13]. TSP1 binds to human neutrophils [14] and enhances cytokine- IFNG chemoattractant n-fMLP- and PMA-mediated respiratory burst in human neutrophils and macrophages through its N-terminal domain name [15]-[17]. Only a few species of are considered opportunistic fungal pathogens [18]. Together these represent the fourth most common cause of nosocomial bloodstream infections in the United States [19]. is the main aetiological species of human candidiasis [20]. Despite the availability of new antifungal drugs and adjunctive immunotherapies the morbidity and mortality of systemic candidiasis remain high [21]. The manifestations and severity of the contamination are determined by the nature and extent of the host immune response against disseminated candidiasis [22] which requires the coordinated actions of innate and adaptive immunity. studies have established that polymorphonuclear leukocytes (PMN) [23] and mononuclear phagocytes [24] are essential components of the early innate resistance against disseminated candidiasis that obvious in the blood and deep in infected tissues. Phagocytes kill intracellularly (yeast form) and extracellularly (filamentous form) by both oxidative and non-oxidative mechanisms [18]. Impairment in these immune mechanisms can lead to candidemia [25]. PMN play unique functions at different stages of contamination. Products secreted by PMN promote the recruitment of inflammatory monocytes which results in an enhanced inflammatory response [26]. PMN-derived cytokines are required early in systemic contamination for a sufficient host Th1 response. However neutrophil depletion studies have shown SB-3CT that neutrophil-mediated amplification of the innate immune response to SB-3CT also contributes to pathogenesis late in the course of an overwhelming contamination [20]. Here we use the standard murine model of disseminated candidiasis which reproduces many aspects of a human systemic contamination [20] and demonstrate that endogenous TSP1 enhances the early renal innate immune response but contributes to host mortality by impairing phagocytic clearance of a disseminated contamination. Results Endogenous Thrombospondin-1 Enhances Susceptibility of Mice to Disseminated Contamination To specifically address the role of TSP1 in systemic candidiasis C57BL/6 mice and their wt littermates were infected intravenously with an inoculum of 1×106 yeast cells in 100 μl of sterile saline. At day 2 to 4 post-infection animals were euthanized for tissue harvest and histology. Kidneys are the major site of colonization for disseminated infections in humans and mice [20]. Histological examination of the tissues harvested showed a significant colonization in the kidneys and a moderate colonization of the brain (data not shown). Notably at day 2 hematoxylin & eosin (H&E) staining of the tissues revealed approximately 40% less infiltrated PMN in the kidneys of infected mice than in wt mice (Physique 1A). As shown in Physique S1A TSP1 mRNA expression was comparable in infected and un-infected kidneys of wt mice. However at day 4 post-infection immunohistochemical staining revealed high levels of TSP1 associated with inflammatory infiltrates in infected kidneys (Physique S1B). SB-3CT Physique 1 Endogenous TSP1 contributes to the pathogenesis of disseminated contamination. The reduced recruitment of neutrophils in infected mice was associated with lower serum levels of the pro-inflammatory cytokine IL-6 (data not shown). Kidneys and brain were evaluated for fungal burden at day 2 to 4 post-infection using SB-3CT Periodic acid-Schiff (PAS) and Gomori’s methenamine silver (GMS) staining (Physique S2) and colony-forming models (c.f.u.) (Physique 1B) respectively. Surprisingly despite the enhanced inflammatory response in wt mice burdens were higher in the.