Context: The role of estrogens in the pathogenesis of lymphangioleiomyomatosis (LAM), an aggressive and destructive, eventually fatal lung disease of women is poorly understood.

Objective: The study was conducted to test the hypothesis that the lung disease in LAM is estrogen-mediated and to determine if estrogens contribute to the invasiveness of LAM.

Design: In vitro cell culture of spindle-shaped "LAM cells" (LAMD-SM) isolated and propagated from affected lungs. ER and receptor analyses by RT-PCR. ER and , TIMP-2, and MMP-2 western blot analysis for protein assessment. Activity assays were performed for MT1-MMP, MMP-2 and TIMP-2. Assessment of MMP-2 promoter function via transfection assays. Cell invasion chambers used to determine and quantitate cell invasiveness.

Setting: Academic medical center

Patients: Tissue and cells were obtained as outlined in approved IRB protocol 97/007

Intervention: LAMD-SM were treated with a specific MMP-2 antibody or a non-specific inhibitor, doxycycline.

Main outcome measures: Activity of MMP-2 and invasiveness of LAMD cells.

Results: LAMD-SM cells express functional estrogen receptors (ER and ER) which undergo rapid intracellular turnover in their unbound state. 17-estradiol (E₂) enhances the transcriptional ER activity. E₂-induced ER activation increases synthesis and activity of matrix metalloproteinase-2 (MMP-2) through post-transcriptional mechanisms in LAMD-SM. The E₂/ER-mediatedincrease of MMP-2 promotes LAMD-SM invasiveness, in assays in vitro, which can be inhibited by specific antibodies against MMP-2 or doxycycline, an inhibitor of MMPs.

Conclusion: The invasion and destruction of lung parenchyma in LAM is, at least partially, an estrogen-MMP-driven process, which has major implications for therapeutic interventions.