MMP-9 mRNA as a Therapeutic Marker in Acute and Chronic Stages of Arthritis Induced by Type II Collagen Antibody

Background/PurposeAntibodies against type II collagen (anti-CII) are arthritogenic and central to the initiation of the disease. An animal model of collagen type II-specific monoclonal antibody-induced arthritis (CAIA) has been used for the evaluation of various therapeutic effects in rheumatoid arthritis (RA). We aimed to measure the expression of matrix metalloproteinase (MMP)-9 (gelatinase B), tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) in the acute and chronic stages of the CAIA model for application as a therapeutic marker.MethodsA commercially available antibody cocktail containing four monoclonal anti-type II collagen antibodies were injected into 6-8-week-old male BALB/c mice (n = 20) and 50 μL lipopolysaccharide was injected 3 days later. The clinical manifestations of RA were recorded and scored at 10 days (acute stage) and 21 days (chronic stage). Then the mice were sacrificed for histologic analysis of the inflamed footpad and gene expression of IL-1β, TNF-α and MMP-9 by ELISA and quantitative polymerase chain reaction amplification.ResultsMarked inflammation was found in the limb joints of mice at 10 days. Both IL-1β and MMP-9 expression played a central role in the inflammatory reaction in the acute stage. The expression level of MMP-9 mRNA remained high in the chronic stage of CAIA, but that of IL-1β mRNA was unexpectedly negligible; the serum level of TNF-α in CAIA was undetectable in the acute stage. The expression level of TNF-α mRNA was also lower than IL-1β and MMP-9 in the acute inflammatory stage.ConclusionThe CAIA model is a fast and highly replicable model of RA. MMP-9 and IL-1β were highly expressed in the acute stage of CAIA. It is suggested the MMP-9 mRNA level is a suitable marker for both acute and chronic stage, whereas IL-1β is a marker only for the acute stage of the CAIA murine model.