Immunolocalization of Advanced Glycation End Products, Mitogen Activated Protein Kinases, and Transforming Growth Factor-β/Smads in Pelvic Organ Prolapse

Abstract

Collagen and matrix metalloproteinases (MMP) play a pivotal role in the pathophysiology of Pelvic Organ Prolapse (POP) as a switch between type I and III collagen together with a simultaneous activation of MMPs have been observed in the vaginal wall. The aim of this study was to evaluate the Advanced Glycation End (AGE) products, ERK1/2 and transforming growth factor (TGF)-β/Smad pathway expression in muscularis propria in women with POP compared with control patients. We examined 20 patients with POP and 10 control patients treated for uterine fibromatosis. Immunohistochemical analysis using AGE, RAGE, ERK1/2, Smads-2/3, Smad-7, MMP-3, and collagen I-III, TIMP, and α-SMA were performed. Smad-2/3, Smad-7, AGE, ERK1/2, p-ERK, and p-Smad3 were also evaluated using Western-blot analysis. POP samples from the anterior vaginal wall showed disorganization of the normal muscularis architecture. In POP samples, AGE, ERK1/2, Smad-2/3, MMP-3, and collagen III were upregulated in muscularis whereas in controls, Smad-7 and collagen I were increased. The receptor for AGEs (RAGE) was mild or absent both in controls and prolapse. We demonstrated the involvement of these markers in women with POP but further studies are required to elucidate if the overexpression of these molecules could play a crucial role in the pathophysiology of POP disease.

Neurovascular alterations of muscularis propria in the human anterior vaginal wall in pelvic organ prolapse

“…A hallmark of POP is a disorganisation of the muscularis propria, which is increased in thickness and is characterised by a disorganisation of the normal architecture. Muscular fibres appeared disrupted and surrounded by abundant type III collagen that seems to be derived from a phenotype switch of SMCs to myofibroblasts, making it able to produce an extracellular matrix that eventually compromises the Vetuschi et al 2016Vetuschi et al , 2018.…”

“…After that, proteins were transferred to a nitrocellulose membrane and blotted for the specific antibodies of interest in accordance with the protocol mentioned in our previous work (Vetuschi et al. ).…”

“…In particular, the protein lysate was run through a sodium dodecyl sulphatepolyacrylamide gel electrophoresis in denaturant conditions. After that, proteins were transferred to a nitrocellulose membrane and blotted for the specific antibodies of interest in accordance with the protocol mentioned in our previous work (Vetuschi et al 2018).…”

“…Therefore, the switch from type I to type III occurring in POP entails a greater distensibility, but at the same time fragility, of the wall itself (Tremollieres, 2010;Kannan et al 2011;Kerkhof et al 2013). Recent studies (Meijerink et al 2013;Chen et al 2015Chen et al , 2017Vetuschi et al 2018) have suggested that advanced glycation end-products (AGEs) are able to stimulate, through the interaction between AGE and its receptor RAGE, connective remodelling by directly interacting with metalloproteinase 1 (MMP1), tissue inhibitor metalloproteinase (TIMP) and mitogen-activated protein kinase (MAPK) to promote the physiopathology and progression of POP. By using protein kinases such as extracellular signalregulated kinase 1/2 (ERK1/2), AGEs are able to also interact with the transforming growth factor (TGF)-b/Smads pathway, which is known to affect collagen synthesis and deposition (Meijerink et al 2013).…”

“…Changes in muscularis propria in POP also include a reduction in the concentration of elastic fibres and an imbalance in the extracellular matrix turnover, due to the overexpression of MMPs and a simultaneous reduction in their inhibitors (Budatha et al 2013;Shynlova et al 2013;Yucel et al 2013;De Landsheere et al 2014;Vetuschi et al 2018).…”