The results are expressed as the number of neutrophils per cavity

The results are expressed as the number of neutrophils per cavity. Cytokine and chemokine quantification Cytokines and chemokines were measured in the peritoneal lavage, plasma and lung tissue according to the procedures supplied by the manufacturer (R&D Systems, Minneapolis, MN). of either mAb in combination with antibiotics resulted in additive protection. Conclusion Although attempts to translate preclinical findings to clinical sepsis have failed so far, our preclinical experiments strongly suggest that there is a sufficient therapeutic window within which patients with ongoing sepsis could benefit from combined antibiotic plus anti-TLR2 or anti-TLR4 mAb treatment. Introduction Sepsis, including severe sepsis and septic shock, is the end result of complex interactions between infecting organisms and host NVP-BGJ398 phosphate responses that is associated with high mortality rates in intensive care units. Although some novel therapeutic agents have recently been introduced in the field of sepsis [1C3], their clinical efficacy remain controversial [1, 4], as the mortality rate remains unacceptably high and they are associated with significant side effects [5C7]. Hence, further investigation into the mechanisms involved in the transition from infection to multiple organ damage and failure are required if effective future therapies are to be developed. Toll-like receptors (TLRs) play an important role in the recognition of exogenous and endogenous danger signals [6]. TLR engagement gives rise to rapid activation of signaling pathways, such as those involving MAPK, NF- and/or IFN responsive factors [8], thereby leading to the secretion of pro-inflammatory cytokines, reactive oxygen species, antimicrobial peptides and acute-phase proteins. Although signaling through TLRs is an important Mouse monoclonal to HER-2 element of host defense, a growing body of evidence indicates that dysregulation of these receptors may also play a role in the pathogenesis of sepsis [7, 9, 10]. The massive release of inflammatory mediators into the bloodstream following TLR activation is suspected to be associated with sepsis, culminating in multiple organ failure. Studies using genetically mutant or modified mice have demonstrated the detrimental effect of TLR signaling in sepsis-associated inflammatory responses [11C13]. Our group and others have shown that blockade of TLR2 or TLR4 was successful in decreasing disease severity NVP-BGJ398 phosphate in sepsis models of Gram-negative and-positive bacteria, respectively [10, 14, 15]. An anti-TLR4/MD2 monoclonal antibody (mAb) was also shown to decrease lethality in a model of polymicrobial sepsis caused by implantation of a stent in the cecum of mice (15). In this latter study, mechanisms of protection from death after polymicrobial sepsis were not investigated. However, these findings have raised the possibility that pharmacological modulation of TLR activation or downstream signaling pathways could become a useful approach in the control of overwhelming inflammatory responses of infectious origin after specific or polymicrobial bacterial infections. Indeed, it has been argued that certain aspects of the inflammatory response against infection may be amenable to therapeutic intervention without altering the ability of the host to deal with infection [16]. In the present study, we have investigated the effects of preventive and NVP-BGJ398 phosphate therapeutic administration of anti-TLR2 and anti-TLR4 mAbs, either alone or in combination, and in conjunction with antibiotic treatment in a model of polymicrobial sepsis caused by cecal ligation and puncture (CLP). Induction of sepsis by CLP is a standard and accepted model of polymicrobial sepsis that mimics several parameters observed in septic patients [17, 18]. Although pre clinical studies have failed to translate biological findings into effective clinical therapies, pre-clinical experiments may suggest novel therapies to be evaluated in patients and try to provide explanations for failures of clinical trials, such as the phase 3 clinical trial with eritoran tetrasodium, a MD2-TLR4 antagonist [19]. Our results demonstrate that blockade of either TLR2 or TLR4 significantly decrease systemic inflammatory responses and lethality especially when used in combination with antibiotics, representing a specific preclinical setting at which blockers of TLR may be useful in patients with sepsis. Materials and Methods Mice Eight- to twelve-week-old male C57BL/6 background mice were housed under standard conditions in a temperature-controlled room (23 1C) on an automatic 12-h light/dark cycle and had free access to commercial chow and water. The Local Ethics Committee on Animal Experimentation, (Comit de tica em Experimenta??o AnimalCFederal University of Minas Gerais), approved all procedures described in this study. Sepsis induction Mice (6C10 animals/groupCspecific groups are given.