Daniel Kreisel

Vascular smooth muscle cell (VSMC) diversification drives atherosclerotic coronary artery disease (CAD), but the mechanisms governing these cell state transitions remain unclear. We applied multiomic single-cell profiling, epitope mapping, and spatial transcriptomics across 27 human coronary arteries, identifying fibroblast activation protein (FAP) as a marker of modulated VSMCs. Lineage tracing in mice indicated that FAP ⁺ cells originate from Myh11 ⁺ VSMCs, and FAP positron emission tomography imaging in CAD patients showed plaque uptake. FAP ⁺ cell states resided in the macrophage-rich neo-intima. Therapeutically, we developed an anti-FAP bispecific T cell engager, which reduced plaque burden and remodeled the stromal–immune microenvironment through T cell clonal expansion. Our study delivers a single-cell and spatial atlas of human CAD, establishes FAP as a marker of modulated VSMCs, and highlights immunotherapy for lipid-independent targets.

The consequence of lymphatic disruption during transplantation of solid organs remains unknown. Long-term survival after organ transplantation is limited by chronic rejection, a poorly understood process involving fibrotic remodeling and functional decline of the graft. Here, we found that transplanted human lungs and hearts with chronic rejection exhibited fibrosis distributed along dysmorphic lymphatics in areas densely concentrated with hyaluronan, an interstitial glycosaminoglycan that depends on lymphatic drainage for clearance. We illustrated similar findings in transplanted mouse lungs and hearts, which were accompanied by lymphographic findings of graft lymphedema. Using unsupervised clustering, we found a subset of stromal cells present in fibrotic syngeneic mouse lung grafts and human lung and heart grafts with chronic rejection that coexpressed hyaluronan synthase 1 and interleukin-1 receptor 1. Shortly after reperfusion of syngeneic mouse lung grafts, we identified neutrophilic expression of interleukin-1 β ( Il1b ) as a driver of hyaluronan synthase 1 up-regulation. We found interleukin-1–mediated hyaluronan accumulation as a mechanism driving fibrosis that occurred independent of alloimmunity in the setting of lymphatic disruption after transplantation. Development of fibrotic remodeling in transplanted mouse lungs was inhibited by preventing hyaluronan synthesis through the administration of 4-methylumbilliferone, accelerating lymphangiogenesis with pharmacologic activation of VEGF (vascular endothelial growth factor) receptor-3, or inhibiting interleukin-1 receptor 1 signaling in the graft. These therapeutic interventions lay the foundation for future clinical strategies to prevent chronic rejection.

TGF-β-activating integrins promote solid-organ fibrosis, suggesting their use as a molecular marker of disease. Chronic lung allograft dysfunction (CLAD), a progressive fibrotic complication that limits lung transplant survival, is driven by intragraft TGF-β activation. However, the expression patterns of TGF-β-activating integrins remain undefined in lung transplants. Single-cell RNA sequencing in a mouse CLAD model revealed high levels of the TGF-β-activating integrin αvβ6, which was mainly localized to fibrosis-associated Krt8+ transitional alveolar cells (AT1/2), while tolerant transplants lacked both αvβ6 expression and Krt8+AT1/2 cells. Molecular imaging with a newly developed positron emission tomography radiotracer specific for αvβ6, [64Cu]Cu-DOTA-A20-K16R, showed significantly higher uptake in CLAD versus tolerant transplants. In contrast, [64Cu]Cu-DOTA-A20-K16R allograft uptake was reduced by treatments that lowered αvβ6 expression and CLAD severity. Finally, [64Cu]Cu-DOTA-A20-K16R autoradiographic analysis on human explanted lungs with CLAD showed elevated activity that correlated with αvβ6 expression. Collectively, these findings demonstrate the potential utility of αvβ6 molecular imaging to detect CLAD pathogenesis.

Heart failure and ischemic heart disease represent prevalent causes of death among cancer survivors. Despite extensive use of conventional chemotherapies, a limited understanding of how these agents affect the cardiac immune landscape exists. Using mouse models, we show that DNA-damaging agents selectively deplete cardiac-resident macrophages through activation of p53 signaling and resultant necroptosis and apoptosis. Genetic lineage tracing, transcriptomic profiling, and functional studies revealed that recruited monocytes progressively reconstitute the cardiac-resident macrophage compartment, were transcriptionally distinct from embryonic-derived cardiac-resident macrophages, and conferred protection from subsequent hypertensive and ischemic cardiac injury in mice. Monocyte-derived resident-like cardiac macrophages suppressed inflammation and attenuated adverse myocardial remodeling through a type I interferon–dependent mechanism. Collectively, these findings highlight unrecognized effects of DNA-damaging chemotherapies on the cardiac immune landscape and shed light on our understanding of monocyte plasticity and resident macrophage dynamics.