The role of an epithelial neutrophil-activating peptide-78-like protein inrat adjuvant-induced arthritis

The chemokine, epithelial neutrophil-activating peptide-78 (ENA-78), is a p otent neutrophil chemotaxin whose expression is increased in inflamed synov ial tissue and fluid in human rheumatoid arthritis: compared with :osteoart hritis. Since ENA-78 has been implicated in the pathogenesis of RA, we exam ined the expression of an ENA-78-like protein during the development df rat adjuvant-induced arthritis (AIA), Using an ELISA assay, we found increased , levels of antigenic ENA-78-like protein in the sera of AIA animals compar ed with control normal animals by day 7 postadjuvant injection. ENA-78-like protein levels continued to increase as ALA developed. ENA-78-like protein levels in joint homogenates were increased in AIA animals later in the dev elopment- of the disease, by day 18 during maximal, arthritis, compared wit h control animals, Expression of ENA-78-1ike protein in both the AIA serum and joint correlated with the progression of inflammation of the joints. An ti-human ENA-78 administered before disease onset modified the severity of AIA, while administration of anti-ENA-78 after clinical onset of AIA did no t modify the disease, These data support a,role for an ENA-78-1ike protein as an important chemokine in the progression and maintenance of AIA.