Roberts, K. S. | Search bioRxiv

bioRxiv2026

Fisetin-mediated MYC restoration improves age-associated decline in macrophage function

Immune decline in older adults is associated with increased susceptibility to infection and chronic inflammatory diseases. Macrophages are critical innate immune cells that show reduced capacity for phagocytosis and migration with age. Our previous work shows that reduced levels of MYC and USF1 transcription factors are drivers of macrophage age-related functional decline. Here we show that macrophage-specific Myc overexpression improves macrophage migration and, more importantly, is able to improve physical performance at older age in Drosophila, while lifespan remains unaffected. Treatment of human primary macrophages from older individuals with the geroprotective supplement fisetin reverses the decline in MYC expression and improves phagocytosis of pathogens and cell migration functions towards levels seen in younger individuals. Mechanistically, fisetin acts via MYC, by restoring expression levels of MYC targets in human macrophages that are altered with age. Finally, fisetin feeding in older mice improves motor activity and reduces frailty, as well as restoring primary macrophage function and Myc expression in vitro. These findings reveal that restoration of MYC in macrophage ageing is responsible, at least in part, for improvement in physical performance with age and identify this pathway as a rational target to reverse age-related immune decline. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=185 SRC="FIGDIR/small/731325v1_ufig1.gif" ALT="Figure 1"> View larger version (49K): org.highwire.dtl.DTLVardef@1ab6731org.highwire.dtl.DTLVardef@3d85dorg.highwire.dtl.DTLVardef@71c2b3org.highwire.dtl.DTLVardef@a59bf3_HPS_FORMAT_FIGEXP M_FIG C_FIG

immunology↗

bioRxiv2025

Proof-of-Concept in a Murine Model of Treatment of Thrombotic Thrombocytopenic Purpura Using Engineered Red Blood Cells

Thrombotic Thrombocytopenic Purpura (TTP) is caused by congenital or acquired deficiency of ADAMTS13, a metalloproteinase that cleaves von Willebrand Factor (vWF) multimers. Current treatments--plasma exchange and immunosuppression--are costly and associated with significant morbidity therefore, alternative strategies are needed. We developed the kitJak2 platform for producing genetically engineered lab-grown red blood cells (lgRBCs) as drug delivery vectors. We hypothesized that membrane-bound ADAMTS13 displayed on lgRBCs could provide a durable treatment for TTP. To test this, we engineered erythroid cells expressing both wild-type and mutant variants MDTCS fragments of ADAMTS13, conferring resistance to autoantibodies. Flow cytometry and FRET-based assays confirmed robust membrane expression and enzymatic activity. Importantly, mutant MDTCS variants retained catalytic activity in the presence of plasma from TTP patients, whereas wild-type variants were inhibited. For in vivo evaluation, we generated transgenic mice expressing MDTCS ADAMTS13 on their RBC membranes. These mice exhibited normal RBC half-lives and stable, catalytically active ADAMTS13 expression. Using a murine model of TTP--where ADAMTS13 knockout mice challenged with recombinant human vWF (rhvWF) develop thrombocytopenia and schistocytes--we demonstrated that transfusion of ADAMTS13-expressing RBCs significantly mitigated disease, preventing platelet loss and schistocyte formation. This confirms that membrane-bound MDTCS ADAMTS13 cleaves circulating rhvWF under physiological flow conditions in vivo. Finally, employing our KitJak2 platform, we generated human enucleated lgRBCs expressing high levels of catalytically active ADAMTS13. This novel work establishes proof-of-concept that membrane-anchored ADAMTS13-expressing lab- grown RBCs may offer a feasible and effective therapeutic approach for both congenital and acquired TTP.

cell biology↗