OBJECTIVE: To quantify interleukin-1 receptor antagonist (IL-1ra) and IL-1 production and gene expression by rheumatoid arthritis (RA) synovial tissue (ST) cells. METHODS: IL-1 alpha, IL-1 beta, and IL-1ra protein levels were measured by enzyme-linked immunosorbent assay in fresh and cultured ST cells, purified synovial macrophages, and fibroblast-like synoviocytes (FLS). The relative expression of the secreted form of IL-1ra (sIL-1ra) and the alternatively spliced intracellular form (icIL-1ra) was determined by reverse transcription polymerase chain reaction (RT-PCR) techniques. RESULTS: IL-1 alpha, IL-1 beta, and IL-1ra were present in fresh and cultured ST cell samples of synovium from RA and osteoarthritis patients. IL-1ra:IL-1 ratios ranged from 1.2 to 3.6, which is below the 10-100-fold excess of IL-1ra needed to inhibit IL-1 bioactivity. Isolated CD14+ synovial macrophages secreted IL-1ra, but the amount was much less than that of alveolar or in vitro-derived macrophages. Cultured FLS contained intracellular IL-1ra but secreted little IL-1ra into the culture supernatants. RT-PCR showed that icIL-1ra mRNA was more abundant than sIL-1ra mRNA in FLS and unfractionated ST cells. CONCLUSION: IL-1ra production by RA ST cells is deficient relative to total production of IL-1.
OBJECTIVE: To quantify interleukin-1 receptor antagonist (IL-1ra) and IL-1 production and gene expression by rheumatoid arthritis (RA) synovial tissue (ST) cells. METHODS:IL-1 alpha, IL-1 beta, and IL-1ra protein levels were measured by enzyme-linked immunosorbent assay in fresh and cultured ST cells, purified synovial macrophages, and fibroblast-like synoviocytes (FLS). The relative expression of the secreted form of IL-1ra (sIL-1ra) and the alternatively spliced intracellular form (icIL-1ra) was determined by reverse transcription polymerase chain reaction (RT-PCR) techniques. RESULTS:IL-1 alpha, IL-1 beta, and IL-1ra were present in fresh and cultured ST cell samples of synovium from RA and osteoarthritispatients. IL-1ra:IL-1 ratios ranged from 1.2 to 3.6, which is below the 10-100-fold excess of IL-1ra needed to inhibit IL-1 bioactivity. Isolated CD14+ synovial macrophages secreted IL-1ra, but the amount was much less than that of alveolar or in vitro-derived macrophages. Cultured FLS contained intracellular IL-1ra but secreted little IL-1ra into the culture supernatants. RT-PCR showed that icIL-1ra mRNA was more abundant than sIL-1ra mRNA in FLS and unfractionated ST cells. CONCLUSION:IL-1ra production by RA ST cells is deficient relative to total production of IL-1.
Authors: T R D J Radstake; P L E M van Lent; G J Pesman; A B Blom; F G J Sweep; J Rönnelid; G J Adema; P Barrera; W B van den Berg Journal: Ann Rheum Dis Date: 2004-06 Impact factor: 19.103