Proteolytic Activation of Alternative CCR1 Ligands in Inflammation

• Published in: The Journal of immunology (1950) Vol. 174; no. 11; pp. 7341 - 7351
• Main Authors: Berahovich, Robert D, Miao, Zhenhua, Wang, Yu, Premack, Brett, Howard, Maureen C, Schall, Thomas J
• Format: Journal Article
• Language: English
• Published: United States Am Assoc Immnol 01.06.2005
• Subjects: Amino Acid Sequence; Animals; Arthritis, Rheumatoid - immunology; Arthritis, Rheumatoid - metabolism; Arthritis, Rheumatoid - pathology; Cathepsin G; Cathepsins - metabolism; Cell Line, Tumor; Cells, Cultured; Chemokines, CC - biosynthesis; Chemokines, CC - metabolism; Chymases; Humans; Hydrolysis; Inflammation Mediators - metabolism; Ligands; Macrophage Inflammatory Proteins - metabolism; Mice; Molecular Sequence Data; Monokines - biosynthesis; Monokines - metabolism; Pancreatic Elastase - metabolism; Protein Structure, Tertiary; Receptors, CCR1; Receptors, Chemokine - metabolism; Receptors, Chemokine - physiology; Recombinant Proteins - metabolism; Recombinant Proteins - pharmacology; Serine Endopeptidases - metabolism; Synovial Fluid - enzymology; Synovial Fluid - immunology
• ISSN: 0022-1767; 1550-6606
• DOI: 10.4049/jimmunol.174.11.7341

Although chemokines CCL3/MIP-1alpha and CCL5/RANTES are considered to be primary CCR1 ligands in inflammatory responses, alternative CCR1 ligands have also been described. Indeed, four such chemokines, CCL6/C10/MIP-related protein-1, CCL9/MIP-1gamma/MIP-related protein-2, CCL15/MIP-1delta/hemofiltrate CC chemokine-2/leukotactin-1, and CCL23/CKbeta8/myeloid progenitor inhibitory factor-1, are unique in possessing a separately encoded N-terminal domain of 16-20 residues and two additional precisely positioned cysteines that form a third disulfide bridge. In vitro, these four chemokines are weak CCR1 agonists, but potency can be increased up to 1000-fold by engineered or expression-associated N-terminal truncations. We examined the ability of proinflammatory proteases, human cell supernatants, or physiological fluids to perform N-terminal truncations of these chemokines and thereby activate their functions. Remarkably, most of the proteases and fluids removed the N-terminal domains from all four chemokines, but were relatively unable to cleave the truncated forms further. The truncated chemokines exhibited up to 1000-fold increases in CCR1-mediated signaling and chemotaxis assays in vitro. In addition, N-terminally truncated CCL15/MIP-1delta and CCL23/CKbeta8, but not CCL3/MIP-1alpha or CCL5/RANTES, were detected at relatively high levels in synovial fluids from rheumatoid arthritis patients. These data suggest that alternative CCR1 ligands are converted into potent chemoattractants by proteases released during inflammatory responses in vivo.