Cloning and characterization of rhesus IL-18 binding protein, a natural antagonist to IL-18.
IL-18 is a proinflammatory cytokine that is important for host defense, but is also involved in the pathogenesis of a number of disease processes, ranging from autoimmune disorders to atherosclerosis. IL-18 binding protein (IL-18BP) is a constitutively expressed glycoprotein that specifically neutralizes the effects of IL-18, resulting in decreased production of IFN-gamma and reduction in Th1 immune responses. In this study we cloned and sequenced a full-length cDNA of the rhesus IL-18BP (RhIL-18BP) from the spleen of rhesus macaques (Macaca mulatta) and compared its nucleotide and amino acid sequences to the functional murine and human IL-18BP orthologues. In addition, we fused RhIL-18BP to the Fc portion of human IgG1 to make recombinant RhIL-18BP x Fcgamma1 in order to facilitate its detection by Western blot analysis and determined the approximate molecular weight of RhIL-18BP x Fcgamma1 to be 66 kD. With this fusion protein, we showed that RhIL-18BP was functional and could significantly reduce murine IL-18 and LPS-induced IFN-gamma production by murine splenocytes. Furthermore, we demonstrated the expression of IL-18BP in atherosclerotic lesions in a rhesus model of atherosclerosis, underscoring the need to fully understand the role of this protein as a primary negative regulator of IL-18 in multiple disease processes.
Yellayi
Srikanth
S
Division of Comparative Pathology, New England Primate Research Center, Harvard Medical School, Southborough, MA 01772, USA.
Braun
Steve
S
Domingues
Heber G
HG
Kityatana
Nadya
N
Murali
Ramachandran
R
Johnson
R Paul
RP
Mansfield
Keith
K
Westmoreland
Susan V
SV
O'Neil
Shawn P
SP
D000595:Amino Acid Sequence; D000818:Animals; D050197:Atherosclerosis / Q000378:metabolism; D001483:Base Sequence; D003001:Cloning, Molecular; D006801:Humans; D007074:Immunoglobulin G / Q000378:metabolism; D007150:Immunohistochemistry; D036341:Intercellular Signaling Peptides and Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D007371:Interferon-gamma / Q000096:biosynthesis; D020382:Interleukin-18 / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D008070:Lipopolysaccharides / Q000494:pharmacology; D008253:Macaca mulatta / Q000235:genetics*; D051379:Mice; D008969:Molecular Sequence Data; D008970:Molecular Weight; D021381:Protein Transport / Q000187:drug effects; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D020539:Sequence Analysis, Protein; D013154:Spleen / Q000166:cytology / Q000187:drug effects / Q000378:metabolism
D007074:Immunoglobulin G; D036341:Intercellular Signaling Peptides and Proteins; D020382:Interleukin-18; D008070:Lipopolysaccharides; D011993:Recombinant Fusion Proteins; C118370:interleukin-18 binding protein; D007371:Interferon-gamma