Robson, Simon Christopher

SUMMARY Tuberculosis induces diverse lesions, such as necrotic pneumonia, contributing to disease progression and transmission. Despite advances in understanding the role of ATP-gated P2RX7 ion channels in developing severe forms of tuberculosis, the regulation of this important signaling pathway remains unclear. Herein, we show that the ectonucleotidase CD39 plays an essential regulatory role in TB progression by preventing lung tissue damage, bacterial dissemination, and excessive inflammatory responses. Mechanistically, through its enzymatic activity on the cellular surface, CD39 protects infected macrophages from undergoing necrotic death mediated by P2RX7 activation. We proposed that by protecting macrophages from P2RX7-mediated cell death and bacterial dissemination, CD39 prevents the development of necrotic lesions. Altogether, these findings uncover a significant role for CD39 as an essential component of the molecular regulation underlying the development of severe tuberculosis. GRAPHICAL ABSTRACT Brief In tuberculosis, necrotic granuloma-like structures release extracellular ATP (eATP), which triggers P2RX7-mediated immune cell death. CD39 degrades eATP, preventing P2RX7 activation and promoting macrophage survival, thereby limiting inflammation, tissue damage, and bacterial dissemination.

Abstract Background Scientists working in the field of xenotransplantation do not employ a uniform method to measure and report natural and induced antibody responses to non‐ G alα(1,3) G al (non‐ G al) epitopes. Such humoral responses are thought to be particularly pathogenic after transplantation of vascularized Gal TKO pig organs and having a more uniform assay and reporting format would greatly facilitate comparisons between laboratories. Methods Flow cytometry allows examination of antibody reactivity to intact antigens in their natural location and conformation on cell membranes. We have established a simple and reproducible flow cytometric assay to detect antibodies specific for non‐ G al pig antigens using primary porcine aortic endothelial cells ( pAEC s) and cell culture‐adapted pAEC cell lines generated from wild type and α1,3galactosyl transferase knockout (Gal TKO ) swine. Results The consensus protocol we propose here is based on procedures routinely used in four xenotransplantation centers and was independently evaluated at three sites using shared cells and serum samples. Our observation support use of the cell culture‐adapted Gal TKO pAEC KO :15502 cells as a routine method to determine the reactivity of anti‐non‐ G al antibodies in human and baboon serum. Conclusions We have developed an assay that allows the detection of natural and induced non‐Gal xenoreactive antibodies present in human or baboon serum in a reliable and consistent manner. This consensus assay and format for reporting the data should be accessible to laboratories and will be useful for assessing experimental results between multiple research centers. Adopting this assay and format for reporting the data should facilitate the detection, monitoring, and detailed characterization of non‐ G al antibody responses.

AbstractThe histopathology of cardiac xenograft rejection has evolved over the last 20 yr with the development of new modalities for limiting antibody‐mediated injury, advancing regimens for immune suppression, and an ever‐widening variety of new donor genetics. These new technologies have helped us progress from what was once an overwhelming anti‐Gal‐mediated hyperacute rejection to a more protracted anti‐Gal‐mediated vascular rejection to what is now a more complex manifestation of non‐Gal humoral rejection and coagulation dysregulation. This review summarizes the changing histopathology of Gal‐ and non‐Gal‐mediated cardiac xenograft rejection and discusses the contributions of immune‐mediated injury, species‐specific immune‐independent factors, transplant and therapeutic procedures, and donor genetics to the overall mechanism(s) of cardiac xenograft rejection.