Expression and cellular localization of TGF-beta 1 and its co-factors in human endometrium and endometriosis

Objective: Endometriosis represents a challenge because its mostly unknown etiology and pathogenesis causes difficulties in diagnostic assessment as w ell as in choosing the appropriate therapy. In eutopic endometrium, TGF-bet a1 seems to play a crucial part in tissue growth and differentiation by par a- and autocrine mechanisms. So far, little is known about the molecular me chanisms leading to invasive and destructive growth in endometriosis. Methods: Therefore we examined the expression and cellular localization of TGF-beta1 including its inactive precursor LAP, its binding protein LTBP-1 and the expression of TGF-beta -R-I in vitro and in vivo in eutopic and ect opic human endometrium (endometriosis). Results: Both in eutopic and ectopic endometrium, all four proteins were fo und to be synthesized predominantly in the epithelium whereas the mRNA of T GF-beta1, TGF-beta -R-1 and LTBP-1 was expressed at equal amounts in stroma l and epithelial fractions. LTBP-1 protein expression was found to be signi ficantly higher in endometriosis compared with eutopic endometrium. Conclusion: The increased synthesis of LTBP-1 in endometriosis compared to eutopic endometrium, that results in a higher secretion of TGF-beta1, can p ossibly explain the elevated adhesive and invasive activity of endometrioti c lesions.