Study Of Lysyl Oxidase In The Pelvic Floor Of Women With Stress Urinary Incontinence

Objective Stress unrinary incontinence(SUI)is one of the most common disease of gynecology and urology.As the population aging,SUI is becoming a large social and healthy problem day by day.However,the pathogenesis of the SUI is still unknown.Recently,the basic study in the SUI etiology has focused on the collagen in the pelvic floor connective tissue.Lysyl oxidase(LOX)is a copper-dependent amine oxidase that plays a critical role in the biogenesis of connective tissue matrix by crosslinking the extracellular matrix proteins,collagen and elastin.These cross-links are essential for the tensile strength of collagens that are necessary for the structural integrity and function of connective tissue.LOX is the key enzyme for the maturation of amnion,and copper is its essential active cofactor.In the present study the contents of copper in the serum and LOX in the pelvic floor ligaments were detected from SUI group and control group. Meanwhile,we observed the histological structure of the collagen fiber in the pelvic tissue to find the relationship between abnormal in LOX and collagen fiber, and to investigate the significance of LOX in the SUI pathogenesis.Methods The serum of 30 patients with SUI was collected before the operation.We measured the contents of serum copper by the atomic absorption spectrum method.Meanwhile,30 cases with benign disorder of gynecology at similar age were selected as control.Biopsies were obtained from the vesicocervical ligament in SUI group and non-SUI control group during the operation.The uterine cardinal-sacral ligaments were also obtained from 16 cases of the SUI group who were performed other transvaginal operation at the same time.The histological structure of pelvic collagen fibers were examined with routine HE staining and Van Gieson(VG)staining.Immunohistochemistry was used to determine the location of LOX.Protein relative expression of the LOX in pelvic tissue was analyzed by Western blotting.Results In the HE and VG staining sections,collagen fiber density of pelvic tissue in SUI group was decreased and fibers were arranged in disorder. Immunohistochemistry showed the LOX mainly expressed in the cytoplasm of fibroblast.The number of positive cells in pelvic tissue of SUI group was less than the control group,and the positive signal of SUI group was weaker than the control group.There was no statistical difference in serum copper contents between SUI group and the control group(0.929±0.179μg/ml,0.961±0.192μg/ml, P＞0.05).The gray degree values of SUI group both in the vesicocervical ligament and the uterine cardinal-sacral ligament were obviously lower than the control group(6.16±1.682,8.214±1.66,P＜0.01;6.443±1.097,8.459±1.166,P＜0.01)in Western blot.Conclusion The decreased LOX in pelvic floor tissue may play an important role in the development of SUI.The decreasing of LOX expression in the pelvic connective tissue may reduced the formation of cross-linking among collagen fibers and interupt the maturity of the collagen.Finally the pelvic floor became weaker and induced the SUI.