Endometriosis is a benign gynecological pathology in which immune system deregulation may play a role in its initiation and progression. in endometriotic lesions, intercellular adhesion molecule-1 (ICAM1) is released from the cell membrane by proteolytic cleavage of its extracellular domain, a process that coincides with increased expression and proteolytic activity of metalloproteinases such as MMP1 and MMP9. The objective of our study was to investigate the association between MMP1 and MMP9 activities and ICAM1 cleavage mediated by tumor necrosis factor (TNF) in eutopic endometrial stromal cells from women with and without (control) endometriosis during culture. The RNA was evaluated by RT-PCR, and the protein was determined by western blot (ICAM1, MMP1), casein or gelatin zymographies (secreted active MMPI or MMP9 respectively), ELISA (soluble ICAM1 (sICAM1)), and fluorescence assay (secreted active MMP1). Under basal conditions, proMMP9 dimer and MMP9 were higher in endometriosis cell cultures. In stromal cultures derived from control women and those with endometriosis, TNF augmented the intracellular proMMP1 (1.2-fold in control stromal cells) and ICAM1 (1.4- and 1.9-fold), greatly increased MMP1 and proMMP9 levels, and the sICAM1 concentration (2.3- and 4.3-fold) in their media compared with basal levels. The combination of TNF and MMP9 increased the sICAM1 concentration 14-fold in the endometriosis cell media, whereas GM6001 inhibited the stimulatory effect of TNF in both cell cultures. The deregulation of MMP9, and the TNF participation in the MMP1 and proMMP9 secretions, in the MMP9 expression and in the expression and cleavage of ICAM1 may contribute to the pathophysiology of this disease. Reproduction (2009) 138 837-847