title: Collectin Kidney 1 Plays an Important Role in Innate Immunity against Streptococcus pneumoniae Infection.
abstract: Collectins are C-type lectins that are involved in innate immunity as pattern recognition molecules. Recently, collectin kidney 1 (CL-K1) has been discovered, and in vitro studies have shown that CL-K1 binds to microbes and activates the lectin complement pathway. However, in vivo functions of CL-K1 against microbes have not been elucidated. To investigate the biological functions of CL-K1, we generated CL-K1 knockout (CL-K1-/-) mice and then performed a Streptococcus pneumoniae infection analysis. First, we found that recombinant human CL-K1 bound to S. pneumoniae in a calcium-dependent manner, and induced complement activation. CL-K1-/- mice sera formed less C3 deposition on S. pneumoniae. Furthermore, immunofluorescence analysis in the wild-type (WT) mice demonstrated that CL-K1 and C3 were localized on S. pneumoniae in infected lungs. CL-K1-/- mice revealed decreased phagocytosis of S. pneumoniae. Consequently, less S. pneumoniae clearance was observed in their lungs. CL-K1-/- mice showed severe pulmonary inflammation and weight loss in comparison with WT mice. Finally, the decreased clearance and severe pulmonary inflammation caused by S. pneumoniae infection might cause higher CL-K1-/- mice lethality. Our results suggest that CL-K1 might play an important role in host protection against S. pneumoniae infection through the activation of the lectin complement pathway.
authors.affiliation: Department of Microbiology and Immunochemistry, Asahikawa Medical University, Asahikawa, Japan.
authors.forename: Insu
authors.initials: I
authors.lastname: Hwang
authors.forename: Kenichiro
authors.initials: K
authors.lastname: Mori
authors.forename: Katsuki
authors.initials: K
authors.lastname: Ohtani
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Matsuda
authors.forename: Nitai
authors.initials: N
authors.lastname: Roy
authors.forename: YounUck
authors.initials: Y
authors.lastname: Kim
authors.forename: Yasuhiko
authors.initials: Y
authors.lastname: Suzuki
authors.forename: Nobutaka
authors.initials: N
authors.lastname: Wakamiya
mesh_terms: D000818:Animals; D058491:Bacterial Load; D037222:Collectins / Q000235:genetics / Q000378:metabolism*; D003176:Complement C3 / Q000378:metabolism*; D037582:Complement Pathway, Mannose-Binding Lectin / Q000235:genetics; D006801:Humans; D007113:Immunity, Innate; D008168:Lung / Q000276:immunology* / Q000382:microbiology; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D010587:Phagocytosis; D011008:Pneumococcal Infections / Q000276:immunology*; D011014:Pneumonia / Q000276:immunology*; D051192:Receptors, Pattern Recognition / Q000235:genetics / Q000378:metabolism*; D013296:Streptococcus pneumoniae / Q000502:physiology*; D019076:Transgenes / Q000235:genetics
chemical_list: C518521:Colec11 protein, human; D037222:Collectins; D003176:Complement C3; D051192:Receptors, Pattern Recognition