Nonetheless, mice showed only discreetly attenuated lung pathology at 6 hours after infection with without alterations in neutrophil recruitment or protein leak

Nonetheless, mice showed only discreetly attenuated lung pathology at 6 hours after infection with without alterations in neutrophil recruitment or protein leak. receptor 4 (TLR4) and the receptor for advanced glycation end products (RAGE), in the injurious host response to pneumonia. Methods Pneumonia was induced in wild type (Wt), TLR4 deficient (Mice were sacrificed at 6, 24, 48 or 72 hours after infection for harvesting of blood and organs. Results pneumonia was associated with HMGB1 release in the bronchoalveolar compartment peaking after 24 hours. Anti-HMGB1 attenuated lung pathology and protein leak and reduced interleukin-1 release 6?hours after Sitafloxacin infection, but not at later time points. RAGE deficiency more modestly attenuated lung pathology without influencing protein leak, while TLR4 deficiency did not impact on lung injury. Conclusion These data suggest that HMGB1 and RAGE, but not TLR4, contribute to lung injury accompanying the early phase of pneumoniais a frequent colonizer of the human body, and when the opportunity arises, is able to cause a wide array of clinical syndromes [1]. Infections caused by this pathogen impose a high burden on healthcare, largely due to the increasing incidence of antibiotic resistance [2]. Over the past few years, highly virulent methicillin-resistant strains, in particular USA300, have become prevalent in the community as well [2] and have emerged as an important cause of (necrotizing) pneumonia [3]. Pneumonia caused by these strains have a fulminant onset determined by staphylococcal virulence factors and the nature of the immune response [3,4]. More insight into pathogenic mechanisms that influence the outcome of lower airway infection by could help in Sitafloxacin the development of new (immunomodulating) therapies. Staphylococcal pneumonia is associated with a massive influx of neutrophils and release of cytotoxic granular proteins [5-7]. Together with invasive infection, intense host defense mechanisms likely contribute to lung tissue damage and release of damage-associated molecular patterns (DAMPs) [4,7,8]. Pattern-recognition Sitafloxacin receptors that engage with these self-derived proteins may contribute to the severity of pneumonia as they perpetuate (excessive) inflammation. High-mobility group box 1 (HMGB1) is a DAMP that may be of particular interest as it is associated with delayed and sustained release during infection [9]. HMGB1 Rabbit Polyclonal to WEE1 (phospho-Ser642) is a highly conserved non-histone nuclear protein, which is either released passively during cell injury or secreted actively upon inflammatory stimuli [9]. Depending on specific posttranslational redox modifications HMGB1 can act as a cytokine via receptors such as the receptor for advanced glycation end products (RAGE) and toll-like receptor (TLR)4 or as a chemotactic Sitafloxacin factor by forming a heterocomplex with the chemokine CXCL12 via the chemokine receptor CXCR4 [10]. In this study we investigated the role of HMGB1 in experimentally induced pneumonia. This newly developed mouse model of pneumonia is associated with severe pulmonary inflammation and massive influx of neutrophils. In order to study the role of HMGB1 in the pathogenesis of lung infection we inoculated wild-type Sitafloxacin (Wt) mice with a USA300 strain of and treated animals with a control or an anti-HMGB1 antibody. In addition, we investigated Wt mice and mice deficient for TLR4 or RAGE, the receptors implicated in mediating the proinflammatory effects of HMGB1, after induction of pneumonia. Methods Ethics statement Experiments were carried out in accordance with the Dutch Experiment on Animals Act and approved by the Animal Care and Use Committee of the University of Amsterdam (Permit number: DIX100121). Mice C57Bl/6 Wt mice were purchased from Charles River Laboratories Inc. (Maastricht, the Netherlands). RAGE-deficient (mice [12], backcrossed 10 times to a C57BL/6 background were generated as described and bred in the animal facility of the Academic Medical Center (Amsterdam, the Netherlands). Design Wt, and mice were lightly anesthesized by inhalation of isoflurane (Abbot Laboratories, Queensborough, Kent, UK) and intranasally inoculated with a sub-lethal dose of 1 1??107?USA300 (BK 11540) in a 5-l saline solution (n?=?7 to 8 per strain). This sub-lethal dose was determined in a pilot study: mice that were intranasally inoculated with 1??108?died.