
Abstract Background Bacterial meningitis is still a cause of severe neurological disability. The brain is protected from penetrating pathogens by the blood-brain barrier and the innate immune system. The invading pathogens are recognized by pattern recognition receptors including the G-protein-coupled formyl peptide receptors (FPRs), which are expressed by immune cells of the central nervous system. FPRs show a broad spectrum of ligands, including pro- and anti-inflammatory ones. Here, we investigated the effects of the annexin A1 mimetic peptide Ac2-26 in a mouse model of pneumococcal meningitis. Methods Wildtype (WT) and Fpr1 - and Fpr2 -deficient mice were intrathecally infected with Streptococcus pneumoniae D39 (type 2). Subsequently, the different mice groups were treated by intraperitoneal injections of Ac2-26 (1 mg/kg body weight) 2, 8, and 24 h post-infection. The extent of inflammation was analyzed in various brain regions by means of immunohistochemistry and real-time reverse transcription polymerase chain reaction (RT-PCR) 30 h post-infection. Results Ac2-26-treated WT mice showed less severe neutrophil infiltration, paralleled by a reduced induction of pro-inflammatory glial cell responses in the hippocampal formation and cortex. While meningitis was ameliorated in Ac2-26-treated Fpr1 -deficient mice, this protective effect was not observed in Fpr2 -deficient mice. Irrespective of Ac2-26 treatment, inflammation was more severe in Fpr2 -deficient compared to Fpr1 -deficient mice. Conclusions In summary, this study demonstrates anti-inflammatory properties of Ac2-26 in a model of bacterial meningitis, which are mediated via FPR2, but not FPR1. Ac2-26 and other FPR2 modulators might be promising targets for the development of novel therapies for Streptococcus pneumoniae -induced meningitis.
Neutrophils, Bacterial meningitis, Anti-Inflammatory Agents, Hippocampus, ; Bacterial meningitis ; Annexin A1/pharmacology [MeSH] ; Receptors, Formyl Peptide/genetics [MeSH] ; Treatment Outcome [MeSH] ; Glial cell ; Encephalitis/drug therapy [MeSH] ; Neutrophils/drug effects [MeSH] ; Animals [MeSH] ; Meningitis, Pneumococcal/drug therapy [MeSH] ; Neutrophil Infiltration/drug effects [MeSH] ; Mice, Knockout [MeSH] ; Formyl peptide receptor ; Mice [MeSH] ; Anti-Inflammatory Agents/pharmacology [MeSH] ; Innate immunity ; Research ; Anti-Inflammatory Agents/therapeutic use [MeSH] ; Peptides/pharmacology [MeSH] ; Annexin A1/therapeutic use [MeSH] ; Hippocampus/drug effects [MeSH] ; Peptides/therapeutic use [MeSH] ; Annexin A1, Mice, Formyl peptide receptor, Animals, RC346-429, Annexin A1, Innate immunity, Mice, Knockout, Meningitis, Pneumococcal, Research, Receptors, Formyl Peptide, Glial cell, Streptococcus pneumoniae, Treatment Outcome, Neutrophil Infiltration, Encephalitis, Neurology. Diseases of the nervous system, Peptides
Neutrophils, Bacterial meningitis, Anti-Inflammatory Agents, Hippocampus, ; Bacterial meningitis ; Annexin A1/pharmacology [MeSH] ; Receptors, Formyl Peptide/genetics [MeSH] ; Treatment Outcome [MeSH] ; Glial cell ; Encephalitis/drug therapy [MeSH] ; Neutrophils/drug effects [MeSH] ; Animals [MeSH] ; Meningitis, Pneumococcal/drug therapy [MeSH] ; Neutrophil Infiltration/drug effects [MeSH] ; Mice, Knockout [MeSH] ; Formyl peptide receptor ; Mice [MeSH] ; Anti-Inflammatory Agents/pharmacology [MeSH] ; Innate immunity ; Research ; Anti-Inflammatory Agents/therapeutic use [MeSH] ; Peptides/pharmacology [MeSH] ; Annexin A1/therapeutic use [MeSH] ; Hippocampus/drug effects [MeSH] ; Peptides/therapeutic use [MeSH] ; Annexin A1, Mice, Formyl peptide receptor, Animals, RC346-429, Annexin A1, Innate immunity, Mice, Knockout, Meningitis, Pneumococcal, Research, Receptors, Formyl Peptide, Glial cell, Streptococcus pneumoniae, Treatment Outcome, Neutrophil Infiltration, Encephalitis, Neurology. Diseases of the nervous system, Peptides
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