An adult heart injured by an ischemic episode has a limited capacity to regenerate. We administered three types of adult guinea pig cells [cardiomyocytes (CMs), cardiac fibroblasts (CFs), and skeletal myoblasts (Mbs)] to compare their suitability for repair of acute myocardial infarction. We used confocal fluorescent microscopy and a variety of specific immunomarkers and echocardiography to provide anatomic evidence for the viability of such cells and their possible functional beneficial effects. All cells were transfected with adenovirus-containing beta-galactosidase gene so that migration from the injection sites could be traced. Both freshly isolated CMs as well as CFs were found concentrated in the infarcted zone; these cells survived for at least 2 wk posttransplantation. Transplanted CMs were regularly striated and grew long projections that could form gap junctions with native CMs, which was evidenced by connexin43 labeling. In addition, CM transplantation resulted in increased angiogenesis in the infarcted areas. In contrast, transplanted CFs did not appear to make any gap junctional contacts with native CMs nor did they enhance local angiogenesis. Mbs cultured for 7 days and transfected Mbs were identified 7 days posttransplantation in the infarcted area. During that time and thereafter, Mbs proliferated and differentiated into myotubes that formed new, regularly striated myofibers that occupied most (50-70%) of the infarcted area by 2-3 wk. These newly formed myofibers maintained their Mb skeletal muscle origin as evidenced by their capacity to express myogenin and fast skeletal myosin. This skeletal phenotype appeared to downregulate with time, and Mbs partially transdifferentiated into a cardiac phenotype as indicated by labeling for cardiac-specific troponin T and cardiac myosin heavy chain. By the third week posttransplantation, new myofibers formed apparent contacts with the native CMs via putative gap junctions that expressed connexin43. Myocardial performance of animals that were successfully transplanted with Mbs was improved.
Current therapeutic options for atopic dermatitis (AD) consist of either broad or targeted immunosuppressive agents. However, the natural course of AD can hardly be modified, as the disease invariably returns after cessation of treatment. Tissue-resident memory T-cells are hypothesized to be relevant players in mediating disease-specific 'immune memory', but their exact immunopathological phenotype is so far unknown. By using a multi-omics approach involving single-cell RNA sequencing combined with multiplex proteomics of skin samples, we studied AD patients undergoing short (16 weeks) and long-term (one year) treatment with the IL-4Ra blocker dupilumab. IL-4Ra blockade resulted in clearance of disease, decrease in skin immune cell counts, and normalization of transcriptomic dysregulation of keratinocytes. Interestingly, we found distinct populations of dendritic cells (DC) and memory T-cells that were largely absent in healthy control skin to persist in AD up to one year of treatment. These included LAMP3+ CCL22+ mature DC, CRTH2+ CD161+ Th2A cells, and CRTAM+ cytotoxic T-cells, expressing peak levels of CCL17 (DC) and IL13 (T-cells). Th2A cells showed a specific receptor constellation of IL17RB, IL1RL1 (ST2) and CRLF2, possibly rendering them key responders to the AD-typical epidermal alarmins IL25, IL33 and TSLP. We thus identified persisting mature DC and T-cells that maintained an inflammatory phenotype up to one year of treatment,equipped with all receptors to facilitate a keratinocyte-DC-Th2-mediated inflammatory response. These cell populations emerge as central players of a skin-intrinsic disease memory that leads to disease recurrences, and might therefore be promising targets to achieve a more sustained therapeutic response.
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