Possible involvement of HtrA1 serine protease in the onset of osteoporotic bone extracellular matrix changes.

High-temperature requirement A1 (HtrA1), a multidomain serine protease acting on Extracellular matrix (ECM) rearrangement, is also secreted by osteoblasts and osteoclasts. Recent and conflicting literature highlights HtrA1's role as a controller of bone remodeling, proposing it as a possible target for pathologies with unbalanced bone resorption, like Osteoporosis (OP). To add knowledge on this molecule function in bone physiopathology, here we compared HtrA1 distribution in the ECM of healthy (H) and OP bone tissue, also examining its localization in the sites of new bone formation. HtrA1 was homogeneously expressed in the mature bone ECM of H tissue showing a 55.6 ± 16.4% of the stained area, with a significant (p=0.0001) decrease in OP percentage stained area (21.1 ± 13.1). Moreover, HtrA1 was present in the endosteum and cells involved in osteogenesis, mainly in those "entrapped" in woven bone, whereas osteocytes in mature lamellar bone were negative. Based on our previous observation in OP tissue of a significantly increased expression of Decorin and Osteocalcin, both involved in bone mineralization and remodeling and equally substrates for HtrA1, we speculate that HtrA1 by controlling the proper amount of Decorin and Osteocalcin favors normal bone maturation and mineralization. Besides, we suggest that late-osteoblasts and pre-osteocytes secrete HtrA1 in the adjacent matrix whilst proceeding with their maturation and that HtrA1 expression is further modified during the remodeling from woven to the lamellar bone. Overall, our data suggest HtrA1 as a positive regulator of bone matrix formation and maturation: its reduced expression in mature OP bone, affecting protein content and distribution, could hamper correct bone remodeling and mineralization.

High temperature requirement A1 and fibronectin: two possible players in placental tissue remodelling.

High temperature requirement A1 (HtrA1) is a secreted protease involved in placental development. Fibronectin (FN) is involved in important process such as wound healing, cell adhesion and spreading, growth, migration, and differentiation. The purpose of this study was to analyse the expression patterns of HtrA1 in relationship to FN and to the key growth zones of placenta such as mesenchymal villi as well as cell islands and cell columns. We demonstrated that FN and HtrA1 are localized in the placental key growth zones suggesting a pivotal role in maintaining the balance among the molecules involved in the placental development and differentiation.

High temperature requirement A1, transforming growth factor beta1, phosphoSmad2 and Ki67 in eutopic and ectopic endometrium of women with endometriosis.

Increasing evidence supports the hypothesis that TGFb1 signalling may be mediated by high temperature requirement A1 (HtrA1) serine protease, acting on important regulatory mechanisms such as cell proliferation and mobility. Evidence is now accumulating to suggest that HtrA1 is involved in the development and progression of several pathologies. The aim of this study was to evaluate: i) if HtrA1 and TGFb1 expressions differ in eutopic and ectopic endometrium in women with endometriosis; ii) if HtrA1 correlates to TGFb1, pSmad and Ki67. This study was carried out including 10 women with ovarian endometriosis (cases) and 10 women with non endometriotic diseases (controls). Endometrial tissue underwent immunohistochemical H-score analysis for HtrA1, TGFb1, pSmad and Ki67 molecules. Data evaluation was performed by a nonparametric Kruskal-Wallis test and Spearman correlation was applied to evaluate the relationship among the molecules investigated in the epithelial and in the stromal compartment. The HtrA1 was significant decreased in ectopic and eutopic endometrium of women with endometriosis when compared with control endometrium in epithelial compartment. TGFb1was significantly increased in eutopic endometrium and decreased in ectopic endometrium in epithelial and stromal compartment. In addition, Ki67 was significant increased and an increase, but not significant, was detected for pSMAd2 in eutopic and ectopic endometrium compared to control one.  In summary, the significant direct correlation between TGFb1 and pSmad2 as well as between HtrA1 and TGFb1 and the very significant increase of Ki67 in stromal compartment of eutopic endometrium suggest a possible involvement of HtrA1 in the pathogenesis of endometriosis.

IL-1ß and TGF-ß weaken the placental barrier through destruction of tight junctions: an in vivo and in vitro study.

INTRODUCTION: Chorioamnionitis is a gestational pathological condition characterized by acute inflammation of the amniochorionic membranes and placentas leading to high concentrations of IL-1ß, Il-6, Il-8 and TGF-ß in the amniotic fluid. In normal conditions, the permeability of foeto-maternal barrier is due to the assembly and maintenance of different cellular junctional domains. METHODS: In the present study, first we aimed to evaluate the protein expression (by immunohistochemistry and western blotting) and mRNA (by real time PCR) levels of the molecular components of tight junctions (Zonula occludens-1 and occludin), and of adherent junctions (VE-cadherin and ß-catenin) in placentas from chorioamnionitis compared to that in normal pregnancies. RESULTS: Western blotting results showed a significant down-regulation of occludin in placentas affected with chorioamnionitis. No differences were detected for the other proteins analysed. We evaluated whether occludin expression was regulated by IL-1ß, IL-6, IL-8 and TGF-ß by means of in vitro studies using HUVEC cultures and demonstrated a key role of IL-1ß and TGF-ß in the disappearance of occludin at cellular border. CONCLUSIONS: We conclude by suggesting a pivotal role of these two cytokines in facilitating intra-placental infection via para-cellular way due to the disassembly of tight junctions at trophoblastic and endothelial cells in placental tissues.