Adenosine triphosphate binding cassette transporter G2 expression in endometriosis and in endometrium from patients with and without endometriosis

Capsule:
ABCG2 was strongly expressed in endothelial cells of microvessels of eutopic endometrium, and the density of ABCG2+ microvessels was reduced in ectopic endometrium except in cases of deep infiltrating endometriosis.

Authors:
Sachiko Matsuzaki, M.D. and Claude Darcha, M.D.

Volume 98, Issue 6, Pages 1512-1520.e3, December 2012

Abstract:

Objective:
To investigate adenosine triphosphate (ATP)-binding cassette transporter G2 (ABCG2) expression in endometriosis and in samples of endometrium from patients with and without endometriosis.

Design:
Prospective study.

Setting:
University hospital.

Patient(s):
Patients with and without endometriosis.

Intervention(s):
Endometrial and endometriotic tissues obtained throughout the menstrual cycle.

Main Outcome Measure(s):
Density of ABCG2+ microvessels, density of CD31+ microvessels.

Result(s):
No statistically significant differences in the density of ABCG2+ microvessels were observed between endometrium of patients with and without endometriosis in the proliferative phase and early, middle, and late secretory phases. The density of ABCG2+ microvessels was statistically significantly higher in the menstrual endometrium of patients with endometriosis compared with patients without endometriosis. The density of ABCG2+ microvessels was reduced in the ectopic endometrium compared with matched eutopic endometrium except in cases of deep infiltrating endometriosis. The density of ABCG2+ microvessels was statistically significantly higher in deep infiltrating endometriosis compared with ovarian endometriosis and red and black peritoneal lesions throughout the menstrual cycle.

Conclusion(s):
ABCG2 is strongly expressed in the endothelial cells of microvessels of eutopic endometrium, and the density of ABCG2+ microvessels is reduced in ectopic endometrium except in cases of deep infiltrating endometriosis. ABCG2+ microvessels may represent an integral part of the pathophysiology of deep infiltrating endometriosis.

  • Raul Gomez, PhD, IUIVI

    Congrats to the authors for such an interesting paper. With such an attractive starting
    hypothesis and interesting morphologic findings I feel that we all have missed
    the inclusion of some functional experiments by the authors in this paper. In
    fact the authors themselves mention that such functional experiments will be required
    in the future to support their so smartly discussed morphological findings. For
    such reasons I wonder, how do the authors envision that such functional
    experiments have to be designed/performed to support their hypothesis? Are they
    planning to perform them in the future?

    Aside of that I have a methodological issue. The authors employed paraffin sections to perform double immunofluorescence. It is known that paraffin provides autofluorescence background signaling. Looking at figure number 1 one wonders on whether the authors had to struggle with auto fluorescence or not, if so how did they manage to correct
    it? If not, how did they manage to establish threshold to segregate background
    from real signaling? Might the authors be a more detailed at this point? We
    have had this problem in the past and no longer employ paraffin sections but
    cryosections for immunofluorescence, if the authors have overcome such limitations we would gladly like to know how we can do so.

    Raul PhD IUIVI

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