HISTOLOGY AND HISTOPATHOLOGY

Cellular and Molecular Biology

 

Matrix metalloproteinase 2 (MMP-2) and tissue transglutaminase (TG 2) are expressed in periglandular fibrosis in horse mares with endometrosis

I. Walter1, J. Handler2, I. Miller3 and C. Aurich4

1Department of Pathobiology, Institute of Histology and Embryology, 2Department of Animal Breeding and Reproduction, Clinic for Obstretrics, Gynecology and Andrology, 3Department of Natural Sciences, Institute of Medical Chemistry, 4Department of Animal Breeding and Reproduction, Centre for Artificial Insemination and Embryo Transfer, University of Veterinary Medicine, Vienna, Austria

Offprint requests to: Dr. Ingrid Walter, Institute of Histology and Embryology, University of Veterinary Medicine, Veterinärplatz 1, A 1210 Vienna, Austria. email: Ingrid.Walter@vu-wien.ac.at


Summary. Periglandular arrangement of myofibroblasts, associated with the deposition of extracellular matrix (ECM), is a cardinal feature of endometrosis in mares. We hypothesized that a disturbance in the expression of matrix degrading enzymes such as matrix metalloproteinases (MMP’s) and matrix cross-linking proteins might lead to an imbalance in deposition and degradation of extracellular matrix components and thereby accentuate degeneration. Therefore, distributions of MMP-2, capable of collagen IV and laminin degradation, and tissue transglutaminase (TG2), a cross-linker of extracellular matrix proteins, were investigated by means of immunohistochemistry on uterine biopsies of healthy mares and animals with endometrosis. It was illustrated that both proteins were present in fibrotic regions of affected endometria, and that they were in most cases colocalized. Periglandular MMP-2 expression was significantly associated with dilated and fibrotic uterine glands. Furthermore, MMP-2 and TG 2 were demonstrated in the stratum compactum of healthy and endometrotic endometria. Gelatin zymography proved that active and inactive pro-form of MMP-2 were present in all examined samples with significantly higher amounts of total and active MMP-2 in affected endometria. TG 2-activity, determined by an in situ assay, was found in cases of severe periglandular fibrosis. We suggest that both enzymes play a major role in changes that occur in ECM homeostasis in endometrial fibrotic regions. Histol Histopathol 20, 1105-1113 (2005)

Key words: Endometrium, Endometrosis, MMP’s, Transglutaminase, Horse

DOI: 10.14670/HH-20.1105