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Cytokine‐induced expression of mRNAs for chemotactic factors in human synovial cells and fibroblasts

In response to interleukin 1 or tumor necrosis factor, human synovial cells and fibroblasts expressed several genes encoding known chemotactic factors or related proteins. Transcripts for interleukin 8 (IL‐8), gro/MGSA, pAT 464, IP‐10, pAT 744 and Monocyte Chemotactic and Activating Factor (MCAF) accumulated rapidly in IL‐1 and TNF‐treated cells. The inhibition of protein synthesis led to the superinduction of IL‐8 and gro/MGSA mRNAs in IL‐1, but not in TNF‐treated cells. Thus, IL‐1 and TNF are likely to regulate the expression of these mRNAs by different mechanisms. Important cell‐specific differences in mRNA accumulation characterized the expression of chemotactic factor genes. Moreover, only a subset of the same genes was activated in quiescent cells stimulated by serum. Therefore, genes encoding closely related proteins each had a distinct pattern of expression. Continuous stimulation of fibroblasts and synovial cells with IL‐1 resulted in high and prolonged expression of IL‐8 and gro/MGSA mRNAs. These results extend the list of chemotactic factor genes expressed by mesenchymal cells in vitro and suggest a pivotal role for these cells in processes such as chronic inflammation. © 1993 Wiley‐Liss, Inc.