Immunosuppression continues to be a necessary component of transplantation, despite its association with a multitude of adverse effects. Numerous efforts have been made to circumvent the need for immunosuppression by using various techniques to achieve donor hyporesponsiveness. In this issue of the JCI, Morath et al. take this endeavor forward. Prior to transplantation, the researchers infused recipients with donor-modified immune cells and achieved immunologic hyporesponsiveness. This successful phase I trial also provides a possible avenue for achieving transplantation without the requisite immunosuppression.
Sam Kant, Daniel C. Brennan
Infection with the Gram-negative bacterium Helicobacter pylori remains the most important modifiable risk factor for the development of gastric cancer, a leading cause of cancer-related deaths worldwide. How the interactions between H. pylori and its host shape the gastric environment during chronic infection warrants further investigation. In this issue of the JCI, Palrasu et al. used human cell lines and mouse models to provide mechanistic insight into H. pylori’s ability to delay apoptosis in gastric epithelial cells by actively driving the degradation of a proapoptotic factor, SIVA1. Their findings suggest that promoting the survival of gastric epithelial cells has implications not only for H. pylori pathogenesis but for host tumorigenesis.
José B. Sáenz, Jason C. Mills
Facioscapulohumeral muscular dystrophy (FSHD) results from expression of the full-length double homeobox 4 (DUX4-FL) retrogene in skeletal muscle. However, even in cases of severe FSHD the presence of DUX4 is barely detectable. In this issue of the JCI, Bosnakovski et al. used an inducible, muscle-specific human DUX4 to reproduce the low-level, sporadic DUX4 expression of human FSHD muscle as well the myopathology seen in human FSHD disease. Notably, dysregulated fibroadipogenic progenitors accumulated in affected muscles, thus providing a mechanism for the replacement of muscle by fibrosis and fat.
Carlo Serra, Kathryn R. Wagner
The pandemic coronavirus infectious disease (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is rapidly spreading across the globe. In this issue of the JCI, Chen and colleagues compared the clinical and immunologic characteristics between moderate versus severe COVID-19. The authors found that respiratory distress on admission is associated with unfavorable outcomes. Increased cytokine levels (IL-6, IL-10 and TNFα), lymphopenia (in CD4+ and CD8+ T cells), and decreased IFNγ expression in CD4+ T cells are associated with severe COVID-19. Overall, this study characterized the cytokine storm in severe COVID-19 and provides insights into immune therapeutics and vaccine design.
Savannah F. Pedersen, Ya-Chi Ho
Brown and beige adipose tissues contain thermogenic fat cells that can be activated by β3-adrenergic receptor agonists. In rodents, such drugs both diminish obesity and improve glucose homeostasis. In this issue of the JCI, O’Mara et al. and Finlin and Memetimin et al. report that chronic administration of the approved β3 agonist mirabegron to human subjects was without effect on body weight or fat mass, but improved several measures of glucose homeostasis. Though the mechanisms mediating these metabolic effects are uncertain, the data suggest that β3 agonists could have therapeutic utility in disorders of glucose homeostasis.
Jeffrey S. Flier
The physical integrity of endothelial cells (ECs) lining the blood vessels regulates the inflammatory response. Both innate immunity and inflammatory disorders hinge on the EC-neutrophil interaction. Neutrophil binding, rolling, and migrating along and between ECs is associated with vascular permeability. In this issue of the JCI, Owen-Woods et al. tracked neutrophils in vivo in venules of mouse striated muscle and revealed how endothelial permeability can affect neutrophil trafficking. Strikingly, many neutrophils that migrated between EC junctions were able to rejoin the blood circulation. Further, the chemokine and neutrophil chemoattractant, CXCL1, drove this reverse transendothelial migration (rTEM). This paradigm-shifting study provides a mechanism for distal organ damage as well as an explanation for sepsis-associated acute respiratory distress syndrome.
Alex Marki, Klaus Ley
Cystic fibrosis (CF) is a multisystem disorder, but progressive inflammatory lung disease causes the greatest burden of morbidity and death. Recent translational and mechanistic studies of samples from patients, and observations in animal models, indicate that platelets may drive lung injury and contribute to dysregulated host defense in CF lung disease. In this issue of the JCI, Ortiz-Muñoz and Yu et al. explored the role that the cystic fibrosis transmembrane conductance regulator (CFTR) plays in platelet-related inflammation. The authors used mouse and human model systems to show that CFTR dysfunction in platelets increased calcium entry though the transient receptor potential cation channel 6 (TRPC6), causing hyperactivation and consequent experimental lung inflammation. The study persuasively suggests that platelets are critical thromboinflammatory effector cells in CF lung disease. In the context of platelet-related organ injury seen in a variety of other diseases and syndromes, platelets may also contribute to nonpulmonary manifestations and comorbidities of CF.
Guy A. Zimmerman
Tumor-associated macrophages (TAMs) represent the most abundant hematopoietic cell type in the solid tumor microenvironment. TAMs drive T cell inhibition, promote angiogenesis, and produce tumor growth factors. Although they can paradoxically exert antitumor activity and prime protective immunity, the pathways driving this phenotype remain unclear. In this issue of the JCI, Liu and colleagues identified the c-Maf transcription factor as a master regulator of protumoral TAM polarization. The authors found that c-Maf promoted TAMs’ immunosuppressive activity, governed their metabolic programming, and drove expression of the macrophage differentiation protein, CSF1R. Further, inhibiting c-Maf in myeloid progenitors, and consequent myeloid-lineage cells, including TAMs, delayed tumor growth. Importantly, β-glucan treatment reduced c-MAF expression in macrophages and monocytes from patients with non–small cell lung cancer (NSCLC) where c-MAF is overexpressed. These results reveal mechanisms whereby myeloid cells drive human cancer progression by thwarting protective immunity and could lead to immunotherapy for most solid malignancies.
Jose R. Conejo-Garcia, Paulo C. Rodriguez
β-amyloid aggregates found in brain plaques are viewed as triggers of cytotoxicity and neuroinflammation in Alzheimer disease (AD). However, the main β-amyloid (Aβ) species and what imbues the aggregates with such toxic potential are still not yet understood. In this issue of the JCI, Roy et al. show that Aβ complexed with nucleic acids triggers an antiviral type I interferon response in neuroglia, resulting in complement-mediated synapse elimination in AD models. These findings identify a putative endogenous immune signaling axis that drives neurodegeneration in AD and has strong implications for the development of precise therapeutic strategies.
Stefano Pluchino, Cory Willis
Chronic graft-versus-host disease (GVHD) is a major complication of allogeneic hematopoietic cell transplantation that resembles autoimmunity, with unclear pathogenesis and few effective therapeutic options. In this issue of the JCI, Dertschnig et al. used mouse models to investigate the basis of T cell autoreactivity following GVHD. Notably, GVHD caused irreversible damage to a population of tolerogenic stromal cells that display peripheral tissue–restricted antigens in lymph nodes, which impaired their capacity to purge and suppress autoreactive T cells. Together with damage to central tolerance mechanisms in the thymus, these findings outline a critical one-two punch injury that profoundly disrupts immune tolerance in this devastating disease.
Léolène J. Carrington, Ivan Maillard
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