Search for: All records

Abstract Pemphigus vulgaris (PV) is a blistering autoimmune disease that affects the skin and mucous membranes. The mechanisms by which PV antibodies induce loss of cohesion in keratinocytes are not fully understood. It is accepted that the process starts with antibody binding to desmosomal targets, which leads to its disassembly and subsequent structural changes to cell–cell adhesions. In vitro imaging of desmosome molecules has been used to characterize this initial phase. However, there remains an untapped potential of image analysis in providing us with more in-depth knowledge regarding biophysical changes after antibody binding. Currently, there is no quantitative framework from immunofluorescence images in PV pathology. Here, we seek to establish a correlation of biophysical changes with antibody pathogenicity by examining the effects of PV antibodies on adhesion molecules and the cytoskeletal network. Specifically, we introduced a data-driven approach to quantitatively evaluate perturbations in adhesion molecules following antibody treatment. We identify distinct imaging signatures that mark the impact of antibody binding on the remodeling of adhesion molecules and introduce a pathogenicity score to compare the relative effects of different antibodies. From this analysis, we showed that the biophysical response of keratinocytes to distinct PV antibodies is highly specific, allowing for accurate prediction of their pathogenicity. For instance, the high pathogenicity scores of the PVIgG and AK23 antibodies show strong agreement with their reported PV pathology. Our data-driven approach offers a detailed framework for the action of antibodies in pemphigus and paves the way for the development of effective diagnostic and therapeutic strategies. 

Binding of autoantibodies to keratinocyte surface antigens, primarily desmoglein 3 (Dsg3) of the desmosomal complex, leads to the dissociation of cell-cell adhesion in the blistering disorder pemphigus vulgaris (PV). After the initial disassembly of desmosomes, cell-cell adhesions actively remodel in association with the cytoskeleton and focal adhesions. Growing evidence highlights the role of adhesion mechanics and mechanotransduction at cell-cell adhesions in this remodeling process, as their active participation may direct autoimmune pathogenicity. However, a large part of the biophysical transformations after antibody binding remains underexplored. Specifically, it is unclear how tension in desmosomes and cell-cell adhesions changes in response to antibodies, and how the altered tensional states translate to cellular responses. Here, we showed a tension loss at Dsg3 using fluorescence resonance energy transfer (FRET)-based tension sensors, a tension loss at the entire cell-cell adhesion, and a potentially compensatory increase in junctional traction force at cell-extracellular matrix adhesions after PV antibody binding. Further, our data indicate that this tension loss is mediated by the inhibition of RhoA at cell-cell contacts, and the extent of RhoA inhibition may be crucial in determining the severity of pathogenicity among different PV antibodies. More importantly, this tension loss can be partially restored by altering actomyosin based cell contractility. Collectively, these findings provide previously unattainable details in our understanding of the mechanisms that govern cell-cell interactions under physiological and autoimmune conditions, which may open the window to entirely new therapeutics aimed at restoring physiological balance to tension dynamics that regulates the maintenance of cell-cell adhesion. 

Abstract It is becoming increasingly clear that mechanical stress in adhesive junctions plays a significant role in dictating the fate of cell–cell attachment under physiological conditions. Targeted disruption of cell–cell junctions leads to multiple pathological conditions, among them the life‐threatening autoimmune blistering disease pemphigus vulgaris (PV). The dissociation of cell–cell junctions by autoantibodies is the hallmark of PV, however, the detailed mechanisms that result in tissue destruction remain unclear. Thus far, research and therapy in PV have focused primarily on immune mechanisms upstream of autoantibody binding, while the biophysical aspects of the cell–cell dissociation process leading to acantholysis are less well studied. In work aimed at illuminating the cellular consequences of autoantibody attachment, it is reported that externally applied mechanical stress mitigates antibody‐induced monolayer fragmentation and inhibits p38 MAPK phosphorylation activated by anti‐Dsg3 antibody. Further, it is demonstrated that mechanical stress applied externally to cell monolayers enhances cell contractility via RhoA activation and promotes the strengthening of cortical actin, which ultimately mitigates antibody‐induced cell–cell dissociation. The study elevates understanding of the mechanism of acantholysis in PV and shifts the paradigm of PV disease development from a focus solely on immune pathways to highlight the key role of physical transformations at the target cell.