Interleukin‐4 stimulates rheumatoid synovial fibroblasts to express matrix metalloproteinase‐1 (tissue collagenase) and histamine H1 receptor mRNA

In the present study, we investigated the effect of interleukin‐4 (IL‐4) on metalloproteinase 1 (MMP‐1/tissue collagenase) production in human rheumatoid synovial fibroblasts. Northern blot analysis revealed that addition of IL‐4 with or without histamine stimulated the cells to increase the amount of proMMP‐1 mRNA, and the IL‐4 with histamine addition resulted in a 3.3‐fold increase compared with histamine only. Furthermore, IL‐4 itself stimulated the expression of histamine H1 receptor mRNA. These results suggest that IL‐4 may play an important role in joint destruction in RA.