Huilaja L, Hurskainen T, Autio-Harmainen H, Hofmann SC, Sormunen R, Rasanen J et al.Pemphigoid gestationis autoantigen, transmembrane collagen XVII, promotes the migration of cytotrophoblastic cells of placenta and is a structural component of fetal membranes. Matrix Biol 27:190-200
In pemphigoid gestationis (PG), autoantibodies target collagen XVII, a hemidesmosomal transmembrane protein, which is an important element in cutaneous epithelial adhesion and signalling. We report that collagen XVII is expressed in the first trimester and term syncytial and cytotrophoblastic cells of normal placenta and in epithelial cells of amniotic membrane. Immunoelectron microscopy confirmed the localization of collagen XVII to the hemidesmosomes of amniotic epithelium. Examination of three PG placentas showed mild villitis, but there were no differences between collagen XVII expression levels or immunostaining signals as compared to normal placenta. Collagen XVII expression was also detected in cultured extravillous trophoblast HTR-8/SVneo cells, where collagen XVII expression was upregulated by PMA and TGF-beta1. Interestingly, the presence of Col15, the cell migration domain of collagen XVII, induced the migration of HTR-8/SVneo cells in transmigration assay. Analysis of amniotic fluid samples at different gestational weeks revealed that a large quantity of collagen XVII ectodomain was shed into amniotic fluid throughout pregnancy. Biochemical and immunoblotting analysis indicated that the ectodomain in amniotic fluid is structurally very similar to the ectodomain produced by cultured keratinocytes. Cultured cells from amniotic fluid samples also expressed collagen XVII. Our results suggest that collagen XVII may contribute to the invasion of extravillous trophoblasts during placental development and is also required for the integrity of amniotic basement membrane. Although the exact pathomechanism of PG is still largely unknown, the clinical symptoms of PG are initiated after the expression of collagen XVII in placenta during the first trimester of pregnancy.
"Controls were prepared by carrying out the labelling procedure without the primary antibody (data not shown). For transmission electron microscopy (TEM), specimens from mouse kidneys were processed and analysed as previously described (Huilaja et al. 2008). For scanning electron microscopy (SEM), mouse kidney samples were fixed in 2% glutaraldehyde in 0.1 M phosphate buffer. "
[Show abstract][Hide abstract] ABSTRACT: The kidney filtration barrier consists of the capillary endothelium, the glomerular basement membrane and the slit diaphragm localized between foot processes of neighbouring podocytes. We report that collagen XVII, a transmembrane molecule known to be required for epithelial adhesion, is expressed in podocytes of normal human and mouse kidneys and in endothelial cells of the glomerular filtration barrier. Immunoelectron microscopy has revealed that collagen XVII is localized in foot processes of podocytes and in the glomerular basement membrane. Its role in kidney has been analysed in knockout mice, which survive to birth but have high neonatal mortality and skin blistering and structural abnormalities in their glomeruli. Morphometric analysis has shown increases in glomerular volume fraction and surface densities of knockout kidneys, indicating an increased glomerular amount in the cortex. Collagen XVII deficiency causes effacement of podocyte foot processes; however, major slit diaphragm disruptions have not been detected. The glomerular basement membrane is split in areas in which glomerular and endothelial basement membranes meet. Differences in the expression of collagen IV, integrins α3 or β1, laminin α5 and nephrin have not been observed in mutant mice compared with controls. We propose that collagen XVII has a function in the attachment of podocyte foot processes to the glomerular basement membrane. It probably contributes to podocyte maturation and might have a role in glomerular filtration.
Cell and Tissue Research 03/2012; 348(3):579-88. DOI:10.1007/s00441-012-1368-x · 3.57 Impact Factor
"The target of the PG autoantibodies is BP180 (type XVII collagen) (Giudice et al., 1993), a cell attachment protein expressed in a variety of cells, including placental CTBs, epidermal keratinocytes and epithelial cells of the amniotic membrane (Fairley et al., 1995; Huilaja et al., 2008). Both IgG and IgE-class autoantibodies specific for BP180 have been observed in patients with PG (Chapman et al., 2007; Giudice et al., 1993). "
[Show abstract][Hide abstract] ABSTRACT: BP180 (type XVII collagen) is a transmembrane protein expressed in a variety of cell types. It is also the target of autoantibodies in cutaneous autoimmune disease including bullous pemphigoid and pemphigoid gestationis, a disease unique to pregnancy. The purpose of this study was to determine the prevalence and specificity of cutaneous autoantibodies in a cohort of pregnant women. De-identified sera were collected from pregnant women (n=299) and from non-pregnant controls (n=134). Sera were analyzed by ELISA for the presence of IgG and IgE autoantibodies directed against several cutaneous autoantigens. IgE antibodies against the NC16A domain of BP180 were detected in 7.7% of pregnant women, compared to 2.2% of healthy controls (p=0.01). No increase in total or cutaneous autoantigen specific IgG was seen. Total serum IgE was within the normal range. Full-length BP180 was detected by western immunoblot in epidermal, keratinocyte, placental and cytotrophoblast (CTB) cell lysates. Furthermore, flow cytometry and indirect immunofluorescence confirmed the expression of BP180 on the surface of cultured CTBs. Finally, it was demonstrated that IgE antibodies in the pregnancy sera labeled not only cultured CTBs, but also the placental amnion and cutaneous basement membrane zone using indirect immunofluorescence. We conclude that some pregnant women develop antibodies specific for BP180, and that these autoantibodies are capable of binding both CTB and the placental amnion, potentially affecting placental function.
Data provided are for informational purposes only. Although carefully collected, accuracy cannot be guaranteed. The impact factor represents a rough estimation of the journal's impact factor and does not reflect the actual current impact factor. Publisher conditions are provided by RoMEO. Differing provisions from the publisher's actual policy or licence agreement may be applicable.