Late acute cellular rejection after switch to everolimus monotherapy at 11 months following liver transplantation

Background Acute cellular rejection beyond the 6th month posttransplant is an uncommon complication after liver transplantation. The inadequate immunosuppression (IS) remains the main risk factor. We report a case of acute cellular rejection after a switch to everolimus monotherapy at 11 months following liver transplantation. Case presentation This was a 69-year-old man who underwent liver transplantation after hepatocellular carcinoma. The initial immunosuppression was a combination of three immunosuppressive drugs (corticosteroids + tacrolimus + mycophenolate mofetil). The corticosteroid therapy was stopped at the 4th month posttransplant. Serious side effects of the immunosuppressive drugs (agranulocytosis and renal dysfunction), which occurred 4 months after transplantation, required a reduction and then a discontinuation of tacrolimus and mycophenolate mofetil. Everolimus was introduced as a replacement. The patient was consulted at 11 months after liver transplantation, 1 month after stopping the two immunosuppressive drugs, for liver function test abnormalities such as cytolysis and anicteric cholestasis. A moderate late acute cellular rejection was confirmed by a liver biopsy. A satisfactory biological evolution was observed following corticosteroid boluses and optimization of basic immunosuppressive drugs. Conclusion Late acute cellular rejection remains an uncommon complication, observed mostly in the first year after liver transplantation. The main risk factor is usually the decrease of immunosuppression.

1380. Real-world Effectiveness and Complications of Valganciclovir (VGC) Prophylaxis for Kidney Transplant (KT) Recipients at High Risk for Cytomegalovirus (CMV) infection (CMV Donor (D)+/Recipient (R)-)

Background CMV infection is common post-kidney transplant (KT). Valganciclovir (VGC) prophylaxis (Px) has lessened CMV infection among high-risk (CMV D+/R-) KT recipients (KTRs), but VGC can induce neutropenia. We quantified the burden of CMV infection among CMV D+/R- KTRs and healthcare resources required to manage these patients (pts). Methods Retrospective study of pts undergoing KT between Jan 2014-Dec 2018. Study and control groups (gps) were CMV D+/R- and R+ KTRs, respectively. Standard post-KT immunosuppression was tacrolimus and mycophenolate mofetil (MMF). D+/R- and R+ KTRs received VGC Px (900 mg/day) for 6 and 3 months (mos), respectively. Results Clinical characteristics did not differ between D+/R- (n=131) and R+ (n=140) pts. Median VGC Px duration was longer for D+/R- (183 vs 104 days, p< .01). Within the first 6 mos post KT, a higher proportion of D+/R- KTRs received ≥1-course of granulocyte-stimulating factor (G-CSF) (15% vs 6%, p=.02). VGC Px was stopped prematurely/intermittently in 20% and 10% of D+/R- and R+, respectively, due to neutropenia (p=0.02); corresponding data for stopping MMF for ≥1 mos were 32% and 21% (p=.05). 50% of D+/R- pts received < 3 mos Px. Leukopenia prompted hospitalization in 3% of D+/R- vs 0% of R+ pts (p=.05). CMV infections did not differ between gps (7% vs 6%, p=.80); however, VGC-resistant CMV was higher in D+/R- gp (3% vs 0%, p=.05). Between 6-12 mos post-KT, D+/R- KTRs had higher rates of CMV infection (24% vs 4%,p< .01), VGC resistance (5% vs 0%, p=.01), hospitalization due to CMV (11% vs 2%, p=.01), MD intervention (22% vs 2%,p< .01), and infectious disease (ID) referral (8% vs 2%,p= .04). 57% of CMV resistance was observed in pts who prematurely stopped VGC. Hospitalizations were longer for CMV infections in D+/R- KTRs (8 vs 1 d, p< .01). There was a trend toward higher rejection for D+/R- KTRs (13% vs 6%, p=.09). Conclusion Universal VGC Px in D+/R- KTR remains challenging and requires significant resources for monitoring and intervention for neutropenia, including MD involvement and ID referral. Intermittent/premature stop of VGC may have led to VGC-resistant CMV,and stop of MMF may have led to a trend of higher cellular rejection at 1 yr. There is critical need for new CMV agents with a better safety profile. Disclosures Amit D. Raval, PhD, Merck and Co., Inc. (Employee) Yuexin Tang, PhD, JnJ (Other Financial or Material Support, Spouse’s employment)Merck & Co., Inc. (Employee, Shareholder) Cornelius J. Clancy, MD, Merck (Grant/Research Support) Minh-Hong Nguyen, MD, Merck (Grant/Research Support)

Sarcomere ACTC1 and MYO18A serum expression levels detect acute cellular rejection in cardiac transplant patients

Introduction and purpose The development of non-invasive approaches for the early diagnosis of cardiac allograft rejection is necessary. Given the central role of sarcomeric dysfunction in cardiomyocyte biology and sarcomere alterations, described in endomyocardial biopsies of transplant patients with rejection, we hypothesized that the serum expression levels of genes encoding sarcomeric proteins were altered in acute cellular rejection (ACR). Methods Forty consecutive serum samples from transplant recipients undergoing routine endomyocardial biopsies were included in an RNA sequencing analysis. Results We identified 61 sarcomeric genes, 19 of which were differentially expressed in patients with clinically relevant rejection (ACR grade ≥2R). A receiver operating characteristic curve was done to assess their accuracy for ACR detection, and found that 8 relevant actins, myosins, and other sarcomere-related genes showed great diagnostic capacity (AUC≥0.800); ACTC1 (AUC=1.000, p<0.0001) and MYO18A (AUC=1.000, p<0.0001) showed the best results. MYO18A had a good ability to detect mild rejection (AUC=0.789, p<0.05). We found a relationship between MYO18A and the left ventricular end-systolic (p<0.01) and end-diastolic (p<0.05) diameters. Conclusions ACTC1 and MYO18A also showed a significant correlation with the NT-proBNP levels (p<0.05). Because of their precision to detect ACR, we propose sarcomere ACTC1 and MYO18A serum expression levels as potential candidates for non-invasive ACR detection. FUNDunding Acknowledgement Type of funding sources: Public grant(s) – National budget only. Main funding source(s): National Institute of Health Carlos IIIEuropean Regional Development Fund (ERDF)

Renal allograft rejection with thrombotic microangiopathy associated with a Kidd blood group system alloantibody

Introduction/Objective The Kidd blood group antigens are urea transporters found on the surface of red blood cells, renal tubular epithelial cells, and endothelial cells in the renal medulla and vasa recta. While controversial, some reports have described an association between Kidd antigen donor/recipient mismatches and kidney transplant rejection when recipients possess or form anti-Kidd alloantibodies. To date, none of these reports have described development of a thrombotic microangiopathy (TMA) in the renal graft associated with these antibodies. We describe a case of fulminant renal transplant rejection associated with TMA in a patient with anti-Jk(a) alloantibodies who received a deceased-donor kidney transplant (DDKT). Methods/Case Report A 64-year-old woman with end-stage renal disease secondary to AL amyloidosis caused by plasma cell neoplasm received a DDKT associated with delayed graft function. No pre- or post-transplant donor specific antibodies (DSA) were detected, the flow crossmatch testing was negative, and a pre-operative type and screen identified anti-Jk(a) alloantibodies. On post-transplant day 5, her creatinine remained elevated at 6 mg/dL (ref range: 0.4–1.3 mg/dL) with an acute drop in platelets and undetectable haptoglobin. Allograft biopsy showed a combination of TMA with some additional evidence of acute cellular rejection. Tacrolimus was stopped to rule out drug-induced TMA, and the workup showed negative Shiga toxin, normal ADAMTS13 activity, negative atypical HUS genetic testing, and negative antiphospholipid syndrome testing. Genotyping of the donor kidney was positive for the Jk(a) antigen. Eculizumab, IVIG, and a trial of 8 sessions of therapeutic plasma exchange (TPE) were administered. Her creatinine improved (1.93–2.05 mg/dL), indicating a significant antibody-mediated etiology to her delayed graft function. About one month later, her creatinine worsened, and she received another trial of TPE with IVIG and eculizumab. Despite a mild decrease in her creatinine, repeat biopsies showed acute cellular rejection, persistent TMA, and chronic allograft injury. No DSAs were ever detected. Her creatinine never recovered, and she is now dialysis-dependent. Results (if a Case Study enter NA) NA Conclusion We speculate that anti-Jk(a) antibodies interacting with a Jk(a)-positive donor kidney account for graft TMA. This case underscores the potential importance of matching Kidd antigens in kidney transplantation.

Human lung tissue resident memory T cells are re-programmed but not eradicated with systemic glucocorticoids after acute cellular rejection

Acute cellular rejection is common after lung transplantation and is associated with an increased risk of early chronic rejection. We present combined single cell RNA and T cell receptor sequencing on recipient derived T cells obtained from the bronchoalveolar lavage of three lung transplant recipients with acute cellular rejection and compare them with T cells obtained from the same three patients after clinical treatment of rejection with high-dose, systemic glucocorticoids. At the time of acute cellular rejection, we find an oligoclonal expansion of cytotoxic CD8+ T cells, that all persist as tissue resident memory T cells following successful treatment. Persisting CD8+ allograft-resident T cells have reduced gene expression for cytotoxic mediators following therapy with glucocorticoids. This clonal expansion is discordant with circulating T cell clonal expansion at the time of rejection, suggesting in-situ expansion. These findings pose a potential biological mechanism linking acute cellular rejection to chronic allograft damage.

Donor Macrophages Modulate Rejection after Heart Transplantation

Background: Cellular rejection after heart transplantation imparts significant morbidity and mortality. Current immunosuppressive strategies are imperfect, target recipient T-cells, and have a multitude of adverse effects. The innate immune response plays an essential role in the recruitment and activation of T-cells. Targeting the donor innate immune response would represent the earliest interventional opportunity within the immune response cascade. There is limited knowledge regarding donor immune cell types and functions in the setting of cardiac transplantation and no current therapeutics exist for targeting these cell populations. Methods: Using genetic lineage tracing, cell ablation, and conditional gene deletion, we examined donor mononuclear phagocyte diversity and function during acute cellular rejection of transplanted hearts in mice. We performed single cell RNA sequencing on donor and recipient macrophages, dendritic cells, and monocytes at multiple timepoints after transplantation. Based on our single cell RNA sequencing data, we evaluated the functional relevance of donor CCR2+ and CCR2- macrophages using selective cell ablation strategies in donor grafts prior to transplant. Finally, perform functional validation of our single cell derived hypothesis that donor macrophages signal through MYD88 to facilitate cellular rejection. Results: Donor macrophages persisted in the transplanted heart and co-existed with recipient monocyte-derived macrophages. Single-cell RNA sequencing identified donor CCR2+ and CCR2- macrophage populations and revealed remarkable diversity amongst recipient monocytes, macrophages, and dendritic cells. Temporal analysis demonstrated that donor CCR2+ and CCR2- macrophages were transcriptionally distinct, underwent significant morphologic changes, and displayed unique activation signatures after transplantation. While selective depletion of donor CCR2- macrophages reduced allograft survival, depletion of donor CCR2+ macrophages prolonged allograft survival. Pathway analysis revealed that donor CCR2+ macrophages were being activated through MYD88/NF-κβ signaling. Deletion of MYD88 in donor macrophages resulted in reduced antigen presenting cell recruitment, decreased emergence of allograft reactive T-cells, and extended allograft survival. Conclusions: Distinct populations of donor and recipient macrophages co-exist within the transplanted heart. Donor CCR2+ macrophages are key mediators of allograft rejection and inhibition of MYD88 signaling in donor macrophages is sufficient to suppress rejection and extend allograft survival. This highlights the therapeutic potential of donor heart-based interventions.