To investigate the expression level of serum matrix metalloproteinase 3 (MMP3) in early rheumatoid arthritis (ERA) patients with normal C-reaction protein (CRP) or erythrocyte sedimentation rate (ESR), and the significance in disease assessment.
In the study, 133 cases of early RA patients, 25 osteoarthritis (OA) patients and 60 healthy controls in Peking University People's Hospital from 2011 to 2015 were included. The RA patients were further divided into 4 groups according to levels of CRP and ESR: 88 patients with increased CRP and increased ESR, 15 patients with normal CRP and normal ESR, 17 patients with normal CRP but increased ESR, and 13 patients with increased CRP but normal ESR. All the clinical information of the patients was collected, and the serum MMP3 levels of both patients and healthy controls were detected by enzyme-linked immune sorbent assay (ELISA).
The serum MMP3 level of RA patients with normal CRP and/or normal ESR [(72.89±6.34) μg/L] was obviously higher than that of OA patients [(42.87±4.14) μg/L] (P=0.002) and healthy controls [(31.62±2.88) μg/L] (P<0.001). The serum MMP3 levels of the patients with normal CRP and normal ESR [(47.04±9.64) μg/L] were higher than those of the healthy controls, and there was statistical significance between the two groups (P<0.05). The serum MMP3 levels of the patients with increased CRP but normal ESR [(94.18±9.11) μg/L] and the patients with normal CRP but increased ESR [(79.42±10.60) μg/L] were both higher than those of the OA patients and healthy controls, and there was obvious statistical difference (P<0.05). In the early RA patients with normal CRP and/or normal ESR, the serum MMP3 level was positively correlated with the CRP level (r=0.336, P=0.024). The positive rate of MMP3 in the patients with normal CRP and/or normal ESR was 44.44%, higher than the positive rate of CRP (28.89%) and the positive rate of ESR (37.78%). In these early RA patients, the positive rate was 52.94% in the patients with normal CRP but increased ESR and 53.85% in the patients with increased CRP but normal ESR.
The detection of the serum MMP3 level was significant in the assessment of early RA patients within 2-year duration who had normal CRP or ESR value.