TY - JOUR AB - Airway infection by the Gram-positive pathogen Streptococcus pneumoniae (Sp) leads to recruitment of neutrophils but limited bacterial killing by these cells. Co-colonization by Sp and a Gram-negative species, Haemophilus influenzae (Hi), provides sufficient stimulus to induce neutrophil and complement-mediated clearance of Sp from the mucosal surface in a murine model. Products from Hi, but not Sp, also promote killing of Sp by ex vivo neutrophil-enriched peritoneal exudate cells. Here we identify the stimulus from Hi as its peptidoglycan. Enhancement of opsonophagocytic killing was facilitated by signaling through nucleotide-binding oligomerization domain-1 (Nod1), which is involved in recognition of gamma-D-glutamyl-meso-diaminopimelic acid (meso-DAP) contained in cell walls of Hi but not Sp. Neutrophils from mice treated with Hi or compounds containing meso-DAP, including synthetic peptidoglycan fragments, showed increased Sp killing in a Nod1-dependent manner. Moreover, Nod1(-/-) mice showed reduced Hi-induced clearance of Sp during co-colonization. These observations offer insight into mechanisms of microbial competition and demonstrate the importance of Nod1 in neutrophil-mediated clearance of bacteria in vivo. AU - Lysenko,ES AU - Clarke,TB AU - Shchepetov,M AU - Ratner,AJ AU - Roper,DI AU - Dowson,CG AU - Weiser,JN DO - 10.1371/journal.ppat.0030118 PY - 2007/// TI - Nod1 signaling overcomes resistance of S. pneumoniae to opsonophagocytic killing. T2 - PLoS Pathog UR - http://dx.doi.org/10.1371/journal.ppat.0030118 UR - https://www.ncbi.nlm.nih.gov/pubmed/17722978 VL - 3 ER -