title: Collectin CL-P1 utilizes C-reactive protein for complement activation.
abstract: BACKGROUND
  C-reactive protein (CRP) is a plasma pentraxin family protein that is massively induced as part of the innate immune response to infection and tissue injury. CRP and other pentraxin proteins can activate a complement pathway through C1q, collectins, or on microbe surfaces. It has been found that a lectin-like oxidized LDL receptor 1 (LOX-1), which is an endothelial scavenger receptor (SR) having a C-type lectin-like domain, interacts with CRP to activate the complement pathway using C1q. However it remains elusive whether other lectins or SRs are involved in CRP-mediated complement activation and the downstream effect of the complement activation is also unknown.
  
  
  METHODS
  We prepared CHO/ldlA7 cells expressing collectin placenta-1 (CL-P1) and studied the interaction of CRP with cells. We further used ELISA for testing binding between proteins. We tested for C3 fragment deposition and terminal complement complex (TCC) formation on HEK293 cells expressing CL-P1.
  
  
  RESULTS
  Here, we demonstrated that CL-P1 bound CRP in a charge dependent manner and the interaction of CRP with CL-P1 mediated a classical complement activation pathway through C1q and additionally drove an amplification pathway using properdin. However, CRP also recruits complement factor H (CFH) on CL-P1 expressing cell surfaces, to inhibit the formation of a terminal complement complex in normal complement serum conditions.
  
  
  CONCLUSIONS
  The interaction of collectin CL-P1 with CFH might be key for preventing attack on "self" as a result of complement activation induced by the CL-P1 and CRP interaction.
authors.affiliation: Department of Microbiology & Immunochemistry, Asahikawa Medical University, Asahikawa 078-8510, Japan.
authors.forename: Nitai
authors.initials: N
authors.lastname: Roy
authors.affiliation: Department of Microbiology & Immunochemistry, Asahikawa Medical University, Asahikawa 078-8510, Japan.
authors.forename: Katsuki
authors.initials: K
authors.lastname: Ohtani
authors.affiliation: Department of Microbiology & Immunochemistry, Asahikawa Medical University, Asahikawa 078-8510, Japan.
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Matsuda
authors.affiliation: Department of Microbiology & Immunochemistry, Asahikawa Medical University, Asahikawa 078-8510, Japan.
authors.forename: Kenichiro
authors.initials: K
authors.lastname: Mori
authors.affiliation: Department of Microbiology & Immunochemistry, Asahikawa Medical University, Asahikawa 078-8510, Japan.
authors.forename: Insu
authors.initials: I
authors.lastname: Hwang
authors.affiliation: Department of Bioresources, Research Center for Zoonosis Control, Hokkaido University, Sapporo 001-0020, Japan.
authors.forename: Yasuhiko
authors.initials: Y
authors.lastname: Suzuki
authors.affiliation: Department of Tumor Immunology, Research Institute, Osaka Medical Center for Cancer and Cardiovascular Diseases, Osaka 537-8511, Japan.
authors.forename: Norimitsu
authors.initials: N
authors.lastname: Inoue
authors.affiliation: Department of Microbiology & Immunochemistry, Asahikawa Medical University, Asahikawa 078-8510, Japan. Electronic address: wakamiya@asahikawa-med.ac.jp.
authors.forename: Nobutaka
authors.initials: N
authors.lastname: Wakamiya
mesh_terms: D000818:Animals; D002097:C-Reactive Protein / Q000737:chemistry* / Q000502:physiology; D016466:CHO Cells; D037222:Collectins / Q000737:chemistry* / Q000502:physiology; D003167:Complement Activation; D017242:Complement Factor H / Q000737:chemistry; D003412:Cricetulus; D057809:HEK293 Cells; D006801:Humans; D051116:Receptors, Scavenger / Q000737:chemistry* / Q000502:physiology
chemical_list: C422442:COLEC12 protein, human; D037222:Collectins; D051116:Receptors, Scavenger; D017242:Complement Factor H; D002097:C-Reactive Protein
keywords: Classical pathway; Collectin; Complement; Pentraxin; Scavenger receptor