Molecular diagnosis in autoimmune skin blistering conditions

Blister formation in skin and mucous membranes results from a loss of cell-cell or cell-matrix adhesion and is a common outcome of pathological events in a variety of conditions, including autoimmune and genetic diseases, viral and bacterial infections, or injury by physical and chemical factors. Autoantibodies against structural components maintaining cell-cell and cell-matrix adhesion induce tissue damage in autoimmune blistering diseases. Detection of these autoantibodies either tissue-bound or circulating in serum is essential to diagnose the autoimmune nature of disease. Various immunofluorescence methods as well as molecular immunoassays, including enzyme-linked immunosorbent assay and immunoblotting, belong to the modern diagnostic algorithms for these disorders. There is still a considerable need to increase awareness of the rare autoimmune blistering diseases, which often show a severe, chronic-relapsing course, among physicians and the public. This review article describes the immunopathological features of autoimmune bullous diseases and the molecular immunoassays currently available for their diagnosis and monitoring.

145. WINGLESS (WNT) 3A INDUCES TROPHOBLAST MIGRATION AND MATRIX METALLOPROTEINASE-2 SECRETION THROUGH CANONICAL WNT SIGNALLING AND PROTEIN KINASE B/AKT ACTIVATION

Human placenta and trophoblasts express WNT ligands and WNT receptors suggesting a role for WNT-signalling in placental development. Indeed, a recombinant WNT ligand was recently shown to promote trophoblast migration/invasion, however, the involved signalling cascades and their target genes have not been elucidated. The aim was to investigate signal transduction via canonical WNT-signalling or phosphatidylinositide 3-kinase (PI3K)/AKT-signalling, their cross-talk as well as trophoblast-specific protease expression in trophoblastic SGHPL-5 cells and primary 1st trimester extravillous trophoblasts (EVT). WNT3A-dependent activation/phosphorylation of AKT (pAKT) and the down-stream kinaseglycogen synthase kinase (GSK)-3β were determined by Western blotting (WB). WNT3A-induced canonical WNT-signalling was analysed by luciferase reporter assay (TOPFlash) and nuclear recruitment of β-catenin. Trophoblast migration was studied using transwell assays and villous explant cultures. MMP2 expression/activation was investigated by qRT-PCR and WB/gelatine-zymography of supernatants. All experiments were performed +/– inhibitors of AKT-signalling or canonical WNT-signalling using LY294002 (PI3K inhibitor) or recombinant Dickkopf-1 (DKK1). WNT3A induced pAKT, luciferase expression of the canonical WNT reporter (P < 0.05) as well as accumulation of nuclear β-catenin. Inhibition of PI3K abolished WNT-dependent pAKT, pGSK-3β and cell migration, but did not affect TOPFlash activity or appearance of nuclear β-catenin. Inhibition through DKK1 did not influence pAKT and pGSK-3β, but decreased WNT reporter activity, nuclear β-catenin and cell migration. Both inhibitors decreased WNT3A-induced MMP2 expression in SGHPL-5 cells and pure EVTs (P < 0.05). WNT3A activates PI3K/AKT as well as canonical WNT-signalling through distinct receptors in invasive trophoblasts, since DKK1 did not activate the particular kinase. Although cross-talk between PI3K/AKT and canonical WNT-signalling has been observed in some cell types, these pathways seem to act independently in trophoblasts. However, both pathways promote Wnt-dependent migration and expression of MMP2. This is the 1st study identifying MMP2 as a novel target gene of canonical WNT-signalling in trophoblast.

Thyrotoxic myopathy in mice: accentuation by a creatine transport inhibitor

To demonstrate the importance of creatine and phosphocreatine in skeletal muscle during periods of metabolic stress, thyrotoxicosis was induced in mice fed the creatine transport inhibitor, beta-guanidinopropionic acid (beta-GPA). Adding 2% of beta-GPA to the diet of normal mice inhibited weight gain and caused a 75% reduction of creatine and phosphocreatine concentrations in skeletal muscle. Addition of 0.25% or 2% of thyroid powder to the diet of normal mice was associated with hyperactivity, cardiomegaly, and a high mortality rate. Superimposing thyrotoxicosis on mice already depleted of creatine and phosphocreatine resulted in degeneration of muscle fibers. These results indicate that high concentrations of creatine and phosphocreatine are essential for the maintenance of muscle integrity during periods of metabolic stress.