PROJECT SUMMARY/ABSTRACT Despite remarkable short-term outcomes, the rate of late renal allograft loss has not improved. This is increasingly attributed to the cumulative effects of ongoing subtle immunological injury that often remains undetected. Clinical parameters and even surveillance biopsies have limited predictive value, underscoring the need for new predictive biomarkers. Dr. Cherukuri showed that: (i) Human Breg activity is best characterized by the ratio of IL-10/TNFα expression by immature T1 transitional B cells (T1Bs); and (ii) This T1B IL-10/TNFα ratio 3 mos post-transplant, predicts subsequent acute rejection (AR), allograft fibrosis, decreased eGFR and graft survival. Furthermore, assessment of T1B IL-10/TNFα ratio prior to transplantation showed that in ~75% of patients, the cytokine ratio remains stable after transplantation and predicts their risk for AR and subsequent outcomes (pre-determined). In contrast, in ~25% of patients, the cytokine ratio shifts from high to low or from low to high, and their risk for subsequent outcomes tracks with the direction of the shift. The mechanisms that regulate stable vs. switchable T1B cytokine expression are unknown. Understanding such mechanisms will allow us to accurately risk-stratify patients prior to transplantation and elucidate key regulatory mechanisms that contribute to an individual patient’s underlying immunological reactivity. We hypothesize that transcriptional regulation by genetic or epigenetic mechanisms dictate the stability of the T1B cytokine ratio, Breg activity, and determine a patient’s post-transplant clinical course. This hypothesis will be tested by examining the genetic and epigenetic underpinnings of stable vs. switchable T1B cytokine expression, and by determining whether clinical characteristics correlate with these changes. These Aims will allow Dr. Cherukuri to gain expertise in: (i) state of the art advanced genomic and epigenetic analysis approaches (e.g., ATACseq, bisulfite sequencing, RNAseq), (ii) bioinformatics, and (iii) traditional statistical modelling, and unsupervised machine learning approaches; in addition to honing standard lab techniques. These new indispensable approaches for basic and translational research will facilitate his transition to a career performing meaningful independent research. These skills will be developed under the guidance of a team of mentors, advisors, and collaborators at the Univ. of Pittsburgh. Dr. David Rothstein (1° mentor) is an established physician-scientist with expertise in transplant immunology, tolerance, and Bregs, as well as biomarker research. Dr. Harinder Singh (co-mentor), an internationally recognized scientist with expertise in genetic and epigenetic regulation of immune responses, directs the Univ. of Pittsburgh Center for Systems Immunology. Both mentors have excellent training track records. An advisory committee of accomplished investigators with expertise ranging from fundamental transplant immunology to translational and clinical science will monitor Dr. Cherukuri’s progress biannually. This proposal will promote Dr. Cherukuri’s goal of achieving scientific independence as a tenure track physician-scientist with expertise in Bregs, their transcriptional regulation and translational applications as biomarkers, and as therapeutic targets.

NARRATIVE We have discovered that the expression of cytokines by B cells prior to kidney transplantation can identify patients who are at increased risk for rejection and loss of their transplants. B cell cytokines remain stable and the immunological risk associated with this stability appears pre-determined in some patients, while in others the cytokine expression changes after transplantation along with the patient’s risk status. The proposed study will identify the genetic regulatory mechanisms that maintain stability vs. plasticity in the B cells, allowing us to accurately determine a patient’s risk for rejection prior to transplantation, and individualize immunosuppression, while providing novel insights into the mechanisms that regulate immunological reactivity.