Matrix Metalloproteinase-1 and -9 in Human Placenta during Spontaneous Vaginal Delivery and Caesarean Sectioning in Preterm Pregnancy

Preterm birth is a major public health problem in terms of loss of life, long-term and short term disabilities worldwide. The process of parturition (both term and preterm) involves intensive remodelling of the extracellular matrix (ECM) in the placenta and fetal membranes by matrix metalloproteinases (MMPs). Our previous studies show reduced docosahexaenoic acid (DHA) in women delivering preterm. Further omega 3 fatty acids are reported to regulate MMP levels. This study was undertaken to examine the placental levels of MMPs and their association with placental DHA levels in women delivering preterm. The levels of MMP-1 and MMP-9 in 74 women delivering preterm (52 by spontaneous vaginal delivery and 22 by caesarean sectioning) and 75 women delivering at term (59 by spontaneous vaginal delivery and 16 by caesarean sectioning) were determined by enzyme-linked immunosorbent assay (ELISA) and their association with placental DHA was studied. Placental MMP-1 levels were higher (p<0.05) in women delivering preterm (both by spontaneous vaginal delivery and caesarean sectioning) as compared to those delivering at term. In contrast, placental MMP-9 levels in preterm pregnancies was higher (p<0.05) in women with spontaneous vaginal delivery while lower (p<0.05) in women delivering by caesarean sectioning. Low placental DHA was associated with higher placental MMP-9 levels. Our study suggests a differential effect of mode of delivery on the levels of MMPs from placenta. Further this study suggests a negative association of DHA and the levels of MMP-9 in human placenta although the mechanisms need further study

Expression of "relaxed" conformation of pai-2 and lrp in human term gestational tissues

The relaxed conformation of plasminogen activator inhibitor-2 (PAI2r) occurs after interaction of active PAI-2 with bovine thrombin, the plasminogen activators (uPA, tPA) or insertion of a P, M reactive site loop peptide |Aundei1 a II- wbinilied]. The presence of PAI-2r in tissues, determined using a MAb specific for PAl-2r (2H5), may be taken as indicative of in situ inhibition of serine protease-mediated proteolysis by PAI-2. In addition, it is known that relaxed serpins function as ligands for the clearance receptor, low density lipoprotein receptor-related protein (LRP), promoting the intemalisation of uPA-PAI complexes from the cell surface. Internalisation of receptor-bound proteases may be an important criterion determining the invasive cell phenotype. This study characterises the immunohistochemical localisation of PAI2r in human term gestauonal tissues (amnion, choriodecidua and placenta) and establishes its expression with other components of the uPA cascade. The results obtained indicate that PAI-2r immunoreactivity was exclusively localised to amnion epithelial cells, with only minimal staining in the underlying chorion. Although PAI-2 antigen is present (using ADI "3750), no PAI-2r immunoreactivity was detectable in any of the trophoblastic tissues examined (villous and extravillous). Immunoreactive LRP was confined to trophoblasts of the chorion, villous and extravillous tissue, whereas staining in the amnion was absent. For the first time, localisation of PAI-2r at the tissue level has been identified. In addition, the data obtained are consistent with the hypothesis that cells of invasive phenotype, although expressing all components of the uPA cascade, do not accumulate immunoreactive PAI-2r, since it is rapidly internalised from the cell surface. Conversely, cells of non-invasive phenotype may only accumulate PAI-2r immunoreactivity in the absence of LRP expression. We propose, therefore, that the presence of PAI-2r combined with the absence of LRP at the cell surface are putative markers of non-invasive phenotypes in cells that express pAl-2[Tsatas et al J. Histochem Cytochem., in press]

Tissue-specific expression of the relaxed conformation of plasminogen activator inhibitor-2 and low-density lipoprotein receptor-related protein in human term gestational tissues

The relaxed conformation of plasminogen activator inhibitor-2 (PAIr) is formed during inactivation of the matrix-degrading enzyme urokinase plasminogen activator (uPA). The presence of PAIr in tissues, therefore, indicates the in situ inhibition of uPA-mediated proteolysis. In addition, PAIr functions as a ligand for the clearance receptor low-density lipoprotein receptor-related protein (LRP), thereby promoting internalization of receptor-bound uPA-PAIr complexes from the cell surface. The rapid internalization of receptor-bound, inactivated uPA has been suggested to be characteristic of invasive cell phenotypes. The aims of this study were to characterize the immunohistochemical localization of PAir in human term gestational tissues (amnion, choriodecidua, and placenta) and to establish its co-expression with other components of the uPA cascade. The results obtained indicate that PAIr immunoreactivity was exclusively localized to amnion epithelial cells, with only minimal staining in the underlying chorion. PAir immunoreactivity was not detectable in any of the trophoblastic tissues examined (villous and extravillous). The tissue-specific expression of PAIr immunoreactivity was not significantly altered in association with labor onset. uPA and PAI-2 staining was localized predominantly to amnion epithelial cells, underlying chorion, and trophoblast cells of villous and extravillous tissue. Amnion and trophoblasts of extravillous and chorionic tissue showed uPAR immunoreactivity, whereas staining in placenta was absent. Immunoreactive LRP was confined to trophoblasts of the chorion, and the villous and extravillous tissue. For the first time, localization of PAIr at the tissue level has been identified. The data obtained are consistent with the hypothesis that cells of invasive phenotype, although expressing all components of the uPA cascade, do not accumulate immunoreactive PAIr, because it is rapidly internalized from the cell surface. Conversely, cells of noninvasive phenotype will accumulate PAIr immunoreactivity only in the absence of LRP expression. We propose that the presence of PAIr and the absence of LRP at the cell surface are putative markers of noninvasive phenotypes

Gene expression of plasminogen activation cascade components in human term gestational tissues with labour onset

The plasminogen activation cascade is thought to play a critical role in labour-associated remodelling events, such as fetal membrane rupture and placental separation. The aim of this study was to quantify, by Northern analysis, the gene expression of urokinase plasminogen activator (UPA), urokinase receptor (UPAR) and plasminogen activator inhibitor type-2 (PAI-2) in human gestational tissues. Amnion, choriodecidua and placenta were collected from women before, during and after spontaneous-onset labour at term. The expression of UPAR mRNA was significantly (P < 0.05) increased in amnion tissue during and after labour and delivery, compared with the before-labour group. In contrast, UPAR gene expression in choriodecidua and placenta was not significantly altered in association with labour onset. PAI-2 mRNA expression was also significantly (P < 0.05) increased in amnion after labour. No statistically significant differences were observed in choriodecidua or placenta PAI-2 mRNA with labour onset. Neither was any significant effect of labour status on UPA mRNA identified in any of the tissues examined. This study is the first to describe a significant increase in UPAR and PAI-2 gene expression in human amnion tissue with labour. These data are consistent with the hypothesis that, during labour, up-regulation of UPAR expression in amnion serves to localize active UPA at the cell surface, thereby increasing proteolytic activity in fetal membranes. Increased PAI-2 in amnion after labour may provide a regulatory 'switch' to cease further proteolysis in this tissue type. In conclusion, the data obtained support the proposal that the plasminogen activation cascade contributes to the rupture of fetal membranes during active labour

Biomimetic doxorubicin loaded polymersomes from hyaluronan-block-poly(gamma-benzyl glutamate) copolymers

Using "click chemistry" as an easy and versatile synthetic strategy to combine hyaluronan and polyglutamate blocks, we have prepared nanovesicles (polymersomes) that present a controlled size, excellent colloidal stability, and a high loading capacity for hydrophilic and hydrophobic drugs. The unique feature of our concept is the use of hyaluronan, a polysaccharide with known capacity for targeting cancer-related protein receptors, as the hydrophilic portion of a block copolymer system. The cytotoxicity and internalization mechanism of doxorubicin-loaded polymersomes have been evaluated in C6 glioma tumor cell lines. The dual purpose served by hyaluronan, as both a hydrophilic block critical to vesicle formation and as a binding agent for biological targets, breaks new ground in terms of multifunctional nanomaterial design for drug delivery