Neutrophil infiltration in co-housed littermates plays a key role in nasal transmission of Streptococcus pneumoniae in an infant mouse model

Nucleic acid sensing Toll-like receptors 3 and 9 play complementary roles in the development of bacteremia after nasal colonization associated with influenza co-infection

“…The killing of bacteria by immune cells and the epithelial barrier at the nasal cavity are the first line of defense and the ability of bacteria to translocate from the extracellular matrix through the endothelium is affected by the presence of the innate immune system members, such as TLRs [ 32 , 33 , 34 ]. We focused on neutrophils and macrophages those have been reported to be critical for clearance of pneumococcal colonization from the nasal cavity [ 35 , 36 ]. Our results that the mice inhibited TLR3 signaling (TLR3 KO mouse and Unc93b1 KO mouse) showed impaired influx of neutrophils and macrophages by co-infection with flu, a strong agonist of TLR3, are consistent, partially reflecting the prognosis of pneumococcal systemic infection.…”

“…All studies were conducted according to the guidelines outlined by the National Science Foundation Animal Welfare Requirements and the Wakayama Medical University Animal Care and Use Committee. The study was approved by the Institutional Animal Care and Use Committee at Wakayama Medical University (permission number [28][29][30][31][32][33][34][35][36][37][38][39][40][41][42].…”