To determine IL-1 beta, TNF alpha, IL-6, IL-4, IL-10, MMP-1, MMP-3 and MMP-13 expression by freshly isolated peripheral blood (PBMC) and synovial fluid mononuclear cells (SFMC) in early, never-treated (ENT-RA) and non-acute, treated rheumatoid arthritis (NAT-RA) patients. To elucidate whether excessive or inadequate interleukin (IL) and metalloprotease (MMP) expression is influenced by the disease duration.
Fourteen RA patients, 7 with early RA (< 1 year of evolution) never treated with corticosteroids or disease-modifying antirheumatic drugs, and 7 patients with non-acute RA (> 2 years of evolution) treated with disease-modifying antirheumatic drugs, were studied by ELISA and quantitative and semiquantitative RT-PCR. A group of 14 healthy subjects matched for sex and age was included.
No statistically significant difference in the protein or transcript levels for the cytokines of interest was found between the ENT-RA and NAT-RA groups. The cytokine mRNA expression by freshly isolated PBMC and SFMC in both groups was as follows: IL-1 beta > TNF alpha > IL-10 > IL-6, with no mRNA IL-4 expression. In contrast, cytokine serum levels in ENT-RA and NAT-RA patients were detected in inverse order as follows: IL-6 > IL-10, while IL-1 beta, TNF alpha and IL-4 were undetectable. MMP-3 mRNA expression by the PBMC of NAT-RA patients was statistically different to that in ENT-RA patients. Similar levels of mRNA expression of MMP-1, MMP-3 and MMP-13 by the PBMC and SFMC in both RA groups were observed.
A close equilibrium between MMP and pro/anti-inflammatory cytokine production is observed in ENT-RA and NAT-RA patients. This balance is apparently not influenced by the length of the disease. Highly sensitive methods such as quantitative RT-PCR and ELISA, and even studying freshly isolated MC, showed sustained cytokine secretion at the local level (synovial fluid/SFMC) and scarce translation at the peripheral level (serum/PBMC). Expression of MMP mRNA needs to be further evaluated in order to know whether their peripheral expression reflects their local activity in RA patients.