TIMP-1/MMP-9 imbalance in an EBV-immortalized B lymphocyte cellular model:evidence for TIMP-1 multifunctional properties

Tissue inhibitors of metalloproteinases (TIMPs) were initially described as agents controlling metalloproteinase activity. The purpose of this study w as to investigate the expression and the roles of TIMP-1 secreted by Epstei n-Barr-virus (EBV)-immortalized B lymphocytes. TIMP-1 was isolated from con ditioned medium of interleukin (IL)-1 beta stimulated EBV-B lymphocytes; pu rified TIMP-1 was identified by mass spectrometry and immunochemistry. TIMP -1-free MMP-9 was quantified after purification by zymography and enzyme-li nked immunosorbent assay. EBV-B lymphocyte-secreted TIMP-1 inhibited MMP-9 gelatinolytic activity resulting in decreased B-cell transmigration as meas ured in vitro. The release of huge amounts of TIMP-1 in proportion to MMP-9 from B lymphocytes after EBV transformation was shown to be correlated wit h secretion of IL-10 and dependent on culture time. In contrast, there was little TIMP-1 and almost no IL-10 released from native B cells, suggesting a possible IL-10 mediated autocrine regulation mechanism of TIMP-1 synthesi s. The MMP-9/ TIMP-1 imbalance observed in the culture medium of EBV-B lymp hocytes (TIMP-1 > MMP-9) and of native B cells (MMP-9 > TIMP-1) is suggesti ve of a new function for TIMP-1. We propose that TIMP-1 acts as a survival factor controlling B-cell growth and apoptosis through an autocrine regulat ion process involving IL-10 secreted by EBV-B lymphocytes. (C) 2000 Elsevie r Science B.V. All rights reserved.