Inhibition of Innate Immune Allorecognition Using Nanobiologics Effectively Overturns Ongoing T Cell Mediated Allograft Rejection 2305425

Introduction Acute T cell mediated rejection (TCMR) episodes are inadequately controlled by rejection treatment and impede long-term survival. Given that TCMR is driven by innate allorecognition memory (Allo-IMem), we investigated whether specifically inhibiting Allo-IMem using nanobiologics would overturn TCMR. Methods WT B6 recipients of Balb/c islet allografts were left untreated and then treated at the peak of TCMR (days 7-12) with innate immune cell specific high-density lipoprotein nanobiologics. Nanobiologics were either unloaded (control; U-NB) or loaded with the mTOR inhibitor rapamycin (mTORi-NB; 5mg/kg) and compared to free rapamycin (Rapa; 5mg/kg). Results We uncovered that Allo-IMem signals through mTOR, and unlike Rapa treatment, mTORi-NB inhibits Allo-IMem compared to U-NB. Remarkably, mTORi-NB treatment at the peak of TCMR overturned rejection in 90% of recipients and was therapeutically advantageous over Rapa treatment. scRNA-seq analysis of graft-infiltrating innate cells (day 10) demonstrated that mTORi-NB inhibited cell cycle, glycolysis, and type I/II interferon signaling, and promoted TGF-β signaling pathways, compared to U-NB. Multiphoton intravital microscopy of islet allografts on day 10 revealed that mTORi-NB significantly reduced both the dynamics (speed and distance traveled) and intracellular Ca+ signaling in effector T cells, compared to U-NB. Mechanistically, mTORi-NB significantly reduced the antigenic presentation capacity of graft-infiltrating innate cells compared to U-NB. In addition, both graft infiltrating effector T cell proliferation and IFNγ+ numbers were significantly decreased with mTORi-NB compared to U-NB. Conclusion Taken together, we demonstrate that inhibiting Allo-IMem using innate cell specific mTORi-NB effectively overturns TCMR, thus providing a novel targeted therapeutic treatment for acute rejection in transplant patients. Funding Source NIH U01 U01AI132758 (GC)↑, Thomas E. Starzl Postdoctoral Fellowship in Transplantation Biology (HB)↑ Topic Categories Transplantation Immunology (TRAN)