Cloning and characterization of rhesus IL-18 binding protein, a natural antagonist to IL-18

• Published in: Cytokine (Philadelphia, Pa.) Pa.), 2010-09, Vol.51 (3), p.232-239
• Main Authors: Yellayi, Srikanth, Braun, Steve, Domingues, Heber G., Kityatana, Nadya, Murali, Ramachandran, Johnson, R. Paul, Mansfield, Keith, Westmoreland, Susan V., O’Neil, Shawn P.
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Animals; Atherosclerosis; Atherosclerosis - metabolism; Base Sequence; Cloning, Molecular; Humans; IL-18; IL-18 binding protein; IL-18BP; Immunoglobulin G - metabolism; Immunohistochemistry; Intercellular Signaling Peptides and Proteins - chemistry; Intercellular Signaling Peptides and Proteins - genetics; Intercellular Signaling Peptides and Proteins - metabolism; Interferon-gamma - biosynthesis; Interleukin-18 - antagonists & inhibitors; Interleukin-18 - pharmacology; Lipopolysaccharides - pharmacology; Macaca mulatta; Macaca mulatta - genetics; Macaque; Mice; Molecular Sequence Data; Molecular Weight; Protein Transport - drug effects; Recombinant Fusion Proteins - metabolism; Sequence Analysis, Protein; Spleen - cytology; Spleen - drug effects; Spleen - metabolism
• ISSN: 1043-4666; 1096-0023
• DOI: 10.1016/j.cyto.2010.05.010

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-γ 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·Fcγ1 in order to facilitate its detection by Western blot analysis and determined the approximate molecular weight of RhIL-18BP·Fcγ1 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-γ 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.