Inhibition of Hyaluronic Acid Synthesis Suppresses Angiogenesis in Developing Endometriotic Lesions.

BACKGROUND: The development and long-term survival of endometriotic lesions is crucially dependent on an adequate vascularization. Hyaluronic acid (HA) through its receptor CD44 has been described to be involved in the process of angiogenesis. OBJECTIVE: To study the effect of HA synthesis inhibition using non-toxic doses of 4-methylumbelliferone (4-MU) on endometriosis-related angiogenesis. MATERIALS AND METHODS: The cytotoxicity of different in vitro doses of 4-MU on endothelial cells was firstly tested by means of a lactate dehydrogenase assay. The anti-angiogenic action of non-cytotoxic doses of 4-MU was then assessed by a rat aortic ring assay. In addition, endometriotic lesions were induced in dorsal skinfold chambers of female BALB/c mice, which were daily treated with an intraperitoneal injection of 0.9% NaCl (vehicle group; n = 6), 20 mg/kg 4-MU (n = 8) or 80 mg/kg 4-MU (n = 7) throughout an observation period of 14 days. The effect of 4-MU on their vascularization, survival and growth were studied by intravital fluorescence microscopy, histology and immunohistochemistry. MAIN RESULTS: Non-cytotoxic doses of 4-MU effectively inhibited vascular sprout formation in the rat aortic ring assay. Endometriotic lesions in dorsal skinfold chambers of 4-MU-treated mice dose-dependently exhibited a significantly smaller vascularized area and lower functional microvessel density when compared to vehicle-treated controls. Histological analyses revealed a downregulation of HA expression in 4-MU-treated lesions. This was associated with a reduced density of CD31-positive microvessels within the lesions. In contrast, numbers of PCNA-positive proliferating and cleaved caspase-3-positive apoptotic cells did not differ between 4-MU-treated and control lesions. CONCLUSIONS: The present study demonstrates for the first time that targeting the synthesis of HA suppresses angiogenesis in developing endometriotic lesions. Further studies have to clarify now whether in the future this anti-angiogenic effect can be used beneficially for the treatment of endometriosis.

Targeting galectin-1-induced angiogenesis mitigates the severity of endometriosis.

Endometriosis is characterized by the presence of endometrial tissue outside the uterus that causes severe pelvic pain and infertility in women of reproductive age. Although not completely understood, the pathophysiology of the disease involves chronic dysregulation of inflammatory and vascular signalling. In the quest for novel therapeutic targets, we investigated the involvement of galectin-1 (Gal-1), an endogenous glycan-binding protein endowed with both immunosuppressive and pro-angiogenic activities, in the pathophysiology of endometriotic lesions. Here we show that Gal-1 is selectively expressed in stromal and endothelial cells of human endometriotic lesions. Using an experimental endometriosis model induced in wild-type and Gal-1-deficient (Lgals1(-/-) ) mice, we showed that this lectin orchestrates the formation of vascular networks in endometriotic lesions in vivo, facilitating their ectopic growth independently of vascular endothelial growth factor (VEGF) and the keratinocyte-derived CXC-motif (CXC-KC) chemokine. Targeting Gal-1 using a specific neutralizing mAb reduced the size and vascularized area of endometriotic lesions within the peritoneal compartment. These results underline the essential role of Gal-1 during endometriosis and validate this lectin as a possible target for the treatment of disease.

Anastrozole and celecoxib for endometriosis treatment, good to keep them apart?

Endometriosis is a benign gynecological disease. Cyclooxygenase-2 (COX-2) and aromatase proteins have been shown to be overexpressed in eutopic endometrium from women suffering from this disease compared to disease-free women. Furthermore, inhibition of these molecules individually was demonstrated to have antiproliferative and proapoptotic effects both in vitro and in vivo in several models. In this study, the effect of combining celecoxib, a selective COX-2 inhibitor, and anastrozole, an aromatase inhibitor, on the implantation and growth of endometriotic like lesions in a murine model of endometriosis was evaluated. Endometriosis was surgically induced in female BALB/c mice. After 28 days of treatment with celecoxib, anastrozole, or their combination, animals were killed and lesions were counted, measured, excised, and fixed. Immunohistochemistry for proliferating cell nuclear antigen and CD34 was performed for assessment of cell proliferation and vascularization. TUNEL technique was performed for apoptosis evaluation. Celecoxib was the only treatment to significantly reduce the number of lesions established per mouse, their size and vascularized area. In addition, cell proliferation was significantly diminished and apoptosis was significantly enhanced by both individual treatments. When the therapies were combined, they reversed their effects. These results confirm that celecoxib and anastrozole separately decrease endometriotic growth, but when combined they might have antagonizing effects.