Urinary donor-derived cell-free DNA as a non-invasive biomarker for BK polyomavirus-associated nephropathy

BK polyomavirus-associated nephropathy(BKPyVAN)is a common cause of allograft failure.However,differentiation between BKPyVAN and type I T cell-mediated rejection(TCMR)is challenging when simian virus 40(SV40)staining is negative,because of the similarities in histopathology.This study investigated whether donor-derived cell-free DNA(ddcfDNA)can be used to differentiate BKPyVAN.Target region capture sequencing was applied to detect the ddcfDNAs of 12 recipients with stable graft function,22 with type I TCMR,21 with proven BKPy VAN,and 5 with possible Py VAN.We found that urinary ddcfDNA levels were upregulated in recipients with graft injury,whereas plasma ddcfDNA levels were comparable for all groups.The median urinary concentrations and fractions of ddcfDNA in proven BKPyVAN recipients were significantly higher than those in type I TCMR recipients(10.4 vs.6.1 ng/mL,P<0.001 and 68.4%vs.55.3%,P=0.013,respectively).Urinary ddcfDNA fractions(not concentrations)were higher in the BKPyVAN-pure subgroup than in the BKPyVAN-rejection-like subgroup(81.30%vs.56.64%,P=0.025).With a cut-off value of 7.81 ng/m L,urinary ddcf DNA concentrations distinguished proven BKPyVAN from type I TCMR(area under the curve(AUC)=0.848,95%confidence interval(95%CI):0.734 to 0.963).These findings suggest that urinary ddcf DNA is a non-invasive biomarker which can reliably differentiate BKPy VAN from type I TCMR.

Helper T Cell(CD4^(+))Targeted Tacrolimus Delivery Mediates Precise Suppression of Allogeneic Humoral Immunity

Antibody-mediated rejection(ABMR)is a major cause of dysfunction and loss of transplanted kidney.The current treatments for ABMR involve nonspecific inhibition and clearance of T/B cells or plasma cells.However,the prognosis of patients following current treatment is poor.T follicular helper cells(Tfh)play an important role in allograft-specific antibodies secreting plasma cell(PC)development.Tfh cells are therefore considered to be important therapeutic targets for the treatment of antibody hypersecretion disorders,such as transplant rejection and autoimmune diseases.Tacrolimus(Tac),the primary immunosuppressant,prevents rejection by reducing T cell activation.However,its administration should be closely monitored to avoid serious side effects.In this study,we investigated whether Tac delivery to helper T(CD4^(+))cells using functionalized mesoporous nanoparticles can block Tfh cell differentiation after alloantigen exposure.Results showed that Tac delivery ameliorated humoral rejection injury in rodent kidney graft by suppressing Tfh cell development,PC,and donor-specific antibody(DSA)generation without causing severe side effects compared with delivery through the drug administration pathway.This study provides a promising therapeutic strategy for preventing humoral rejection in solid organ transplantation.The specific and controllable drug delivery avoids multiple disorder risks and side effects observed in currently used clinical approaches.