Dysregulation of Lysyl Oxidase Expression in Lesions and Endometrium of Women With Endometriosis

Lysyl oxidases (LOXs) are enzymes involved in collagen deposition, extracellular membrane remodeling, and invasive/metastatic potential. Previous studies reveal an association of LOXs and endometriosis. We aimed to identify the mechanisms activated by upregulation of lysyl oxidases (LOX) in endometriotic cells and tissues. We hypothesized that LOX plays a role in endometriosis by promoting invasiveness and epithelial to mesenchymal transition (EMT).

METHODS

The LOX protein expression levels were measured by immunohistochemistry in lesions and endometrium on a tissue microarray (TMA) and in endometrial biopsies from patients and controls during the window of implantation (WOI). Estradiol regulation of LOX expression was determined by quantitative polymerase chain reaction (qPCR). Proliferation, invasion, and migration assays were performed in epithelial (endometrial epithelial cell), endometrial (human endometrial stromal cell), and endometriotic cell lines (ECL and 12Z). Pathway-focused multiplex qPCR was used to determine transcriptome changes due to LOX overexpression.

RESULTS

LOX protein was differentially expressed in ovarian versus peritoneal lesions. During WOI, LOX levels were higher in luminal epithelium of patients with endometriosis-associated infertility compared to controls. Invasive epithelial cell lines expressed higher levels of LOX than noninvasive ones. Transfection of LOX into noninvasive epithelial cells increased their migration in an LOX inhibitor-sensitive manner. Overexpression of LOX did not fully induce EMT but the expression of genes related to fibrosis and extracellular matrix remodeling were dysregulated.

CONCLUSIONS

This study documents that expression of LOX is differentially regulated in endometriotic lesions and endometrium. A role for LOX in mediating proliferation, migration, and invasion of endometrial and endometriotic cells was observed, which may be implicated in the establishment and progression of endometriotic lesions.

Protective effects of preconditioning in cultured rat endothelial cells: effects on neutrophil adhesion and expression of ICAM-1 after anoxia and reoxygenation

BACKGROUND

Preconditioning with brief periods of ischemia protects the coronary endothelium against acute and chronic reperfusion injury, but the mechanisms of this endothelial protection remain unknown. We hypothesized that preconditioning protects endothelial cells through a decreased production of endothelial adhesion molecules such as intercellular adhesion molecule-1 (ICAM-1), leading to a lesser adhesion of neutrophils to the endothelium.

METHODS AND RESULTS

Cultured rat aortic endothelial cells were subjected to 6-hour anoxia followed by various durations of reoxygenation. Preconditioning was induced by 1-hour anoxia and 1-hour reoxygenation. ICAM-1 gene expression was measured by polymerase chain reaction, and the percentage of cells expressing ICAM-1 was assessed by confocal laser fluorescence microscopy. Anoxia/reoxygenation increased expression of ICAM-1, with a peak occurring after 6 hours of reoxygenation for mRNA and 9 hours for protein. Preconditioning prevented the increase in ICAM-1. Similar reductions were observed with the free radical scavenger N-2 mercaptopropionyl glycine (MPG). The inhibitory effect of preconditioning on ICAM-1 expression was abolished by an inhibitor of protein kinase C, an inhibitor of nitric oxide synthesis, and by MPG but was not affected by an adenosine receptor antagonist. Finally, both preconditioning and MPG partially prevented the increased adhesion of human neutrophils to reoxygenated endothelial cells.

CONCLUSIONS

Preconditioning prevented reoxygenation-induced, free radical-mediated expression of ICAM-1 by a mechanism involving activation of protein kinase C and production of nitric oxide and free radicals, and this is associated with a lesser adhesion of neutrophils to endothelial cells. Such prevention of neutrophil adhesion may contribute to the protective effect of preconditioning against reperfusion-induced endothelial injury.

[A study of the tensile strength of cruciate ligaments with regard to the possibilities of prosthetic replacement (author's transl)]

Recent clinical and experimental results in the prosthetic replacement of the anterior cruciate ligament are minimal and this fact has incited us to search for additional fundamental characteristics of natural and synthetic ligaments. The dissection of over 30 human knees (5 fresh and 27 embalmed specimens), of 50 dog knees and of 20 cat knees showed that the posterior cruciate ligament was longer and of bigger size than the anterior cruciate ligament. In dogs, the anatomo-radiological study showed a lenghtening of 14,4 p. 100 for the anterior cruciate and of 10,5 p. 1u0 for the posterior cruciate ligament in the various goniometric positions. Traction with the Instron apparatus using whole knee with preserved bony attachments revealed an elastic resistance (yield point) of the ligament of about 50 kg, 60 kg and 30 kg (for human, dog and cat respectively) with elastic elongation (at the yield stress) of 25 p. 100, 35 p. 100 and 45 p. 100 (respectively). Trials on the polyethylene prosthetic ligament used at the present time for replacement of cruciate ligaments in humans showed an elastic resistance of only 16 kg with an elasticity of only 1,4 p. 100. The major differences between the physical properties of the artificial and natural ligaments that we have studied in experimental conditions incite our serious doubt as to the value for the practical use of such a prosthesis and provoque strongly the necessity of search for alternative synthetic or other material more suitable for the task in question.

Prosthetic replacement of the anterior cruciate ligament in dogs

Prosthetic cruciate ligaments are now used clinically. Long-term results are not yet available and for that reason an attempt has been made to reproduce the clnical situation in dogs. Post-traumatic osteoarthritis was inevitably noted following simple excision of the anterior cruciate ligament in a control group of 10 animals. Different prosthetic materials were used and their breaking point was compared with that of normal anterior cruciate ligaments. The longest follow-up period was 6 months. Although some animals had no clinically demonstrable instability, at autopsy all prosthetic ligaments were noted to have failed. The degree of post-traumatic osteoarthritis was directly related to the duration of follow-up. The causes of failure of the prosthetic ligament do not appear to be related to the method of anchorage to bone but rather to the type of prosthetic material used. Although the tensile strength may occasionally have been sufficient, the materials did not have the required elastic characteristics to meet the physiologic demands of a normal cruciate ligament.