Evidence for a functional role of the second C5a receptor C5L2.
During experimental sepsis in rodents after cecal ligation and puncture (CLP), excessive C5a is generated, leading to interactions with C5aR, loss of innate immune functions of neutrophils, and lethality. In the current study, we have analyzed the expression of the second C5a receptor C5L2, the putative "default" or nonsignaling receptor for C5a. Rat C5L2 was cloned, and antibody was developed to C5L2 protein. After CLP, blood neutrophils showed a reduction in C5aR followed by its restoration, while C5L2 levels gradually increased, accompanied by the appearance of mRNA for C5L2. mRNA for C5L2 increased in lung and liver during CLP. Substantially increased C5L2 protein (defined by binding of 125I-anti-C5L2 IgG) occurred in lung, liver, heart, and kidney after CLP. With the use of serum IL-6 as a marker for sepsis, infusion of anti-C5aR dramatically reduced serum IL-6 levels, while anti-C5L2 caused a nearly fourfold increase in IL-6 when compared with CLP controls treated with normal IgG. When normal blood neutrophils were stimulated in vitro with LPS and C5a, the antibodies had similar effects on release of IL-6. These data provide the first evidence for a role for C5L2 in balancing the biological responses to C5a.
Gao
Hongwei
H
Department of Pathology, University of Michigan Medical School, Ann Arbor, Michigan 48109-0602, USA.
Neff
Thomas A
TA
Guo
Ren-Feng
RF
Speyer
Cecilia L
CL
Sarma
J Vidya
JV
Tomlins
Scott
S
Man
Yunfang
Y
Riedemann
Niels C
NC
Hoesel
L Marco
LM
Younkin
Ellen
E
Zetoune
Firas S
FS
Ward
Peter A
PA
D000595:Amino Acid Sequence; D000818:Animals; D000906:Antibodies / Q000494:pharmacology; D002432:Cecum / Q000601:surgery; D002460:Cell Line; D003001:Cloning, Molecular; D015936:Complement C5a / Q000235:genetics / Q000502:physiology*; D018076:DNA, Complementary / Q000235:genetics; D015870:Gene Expression; D006801:Humans; D015850:Interleukin-6 / Q000097:blood; D007668:Kidney / Q000737:chemistry; D008026:Ligation; D008099:Liver / Q000737:chemistry; D008168:Lung / Q000737:chemistry; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008969:Molecular Sequence Data; D009206:Myocardium / Q000737:chemistry; D009504:Neutrophils / Q000737:chemistry / Q000502:physiology; D011677:Punctures; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D020318:Rats, Long-Evans; D044087:Receptor, Anaphylatoxin C5a / Q000032:analysis / Q000235:genetics / Q000276:immunology / Q000502:physiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D018805:Sepsis / Q000209:etiology / Q000276:immunology / Q000378:metabolism; D014162:Transfection
D000906:Antibodies; C496868:C5ar2 protein, rat; D018076:DNA, Complementary; D015850:Interleukin-6; D012333:RNA, Messenger; D044087:Receptor, Anaphylatoxin C5a; D015936:Complement C5a