Joanna Schaenman

Increased Frequency of BK Virus-Specific Polyfunctional CD8+ T Cells Predict Successful Control of BK Viremia After Kidney Transplantation.

Background BK virus infection remains an important cause of loss of allograft function after kidney transplantation. We sought to determine whether polyfunctional T cells secreting multiple cytokines simultaneously, which have been shown to be associated with viral control, could be detected early after start of BK viremia, which would provide insight into the mechanism of successful antiviral control. Methods Peripheral blood mononuclear cells collected during episodes of BK viral replication were evaluated by multiparameter flow cytometry after stimulation by overlapping peptide pools of BK virus antigen to determine frequency of CD8+ and CD4+ T cells expressing 1 or more cytokines simultaneously, as well as markers of T-cell activation, exhaustion, and maturation. Results BK virus controllers, defined as those with episodes of BK viremia of 3 months or less, had an 11-fold increase in frequency of CD8+ polyfunctional T cells expressing multiple cytokines, as compared with patients with prolonged episodes of BK viremia. Patients with only low level BK viremia expressed low frequencies of polyfunctional T cells. Polyfunctional T cells were predominantly of the effector memory maturation subtype and expressed the cytotoxicity marker CD107a. Conclusions Noninvasive techniques for immune assessment of peripheral blood can provide insight into the mechanism of control of BK virus replication and may allow for future patient risk stratification and customization of immune suppression at the onset of BK viremia.

Extended spectrum β-lactamase-producing Enterobacteriaceae infection in heart and lung transplant recipients and in mechanical circulatory support recipients.

Background Extended spectrum &bgr;-lactamase (ESBL)–producing gram-negative bacilli are increasingly reported in patients with a variety of risk factors including prior cephalosporin and antibiotic usage, prolonged hospitalizations, existence of comorbid conditions, and critical illness. Methods Retrospective review of infections caused by ESBL-producing Enterobacteriaceae was performed in heart transplant (HTx), lung transplant (LTx), and mechanical circulatory support (MCS) device recipients at a large transplant center. Results Among 1065 patients transplanted/implanted, the incidence of ESBL-related infections (bacteremia, urinary tract infections, pneumonia, central venous catheter–associated infection, and wound infections) in HTx, LTx, and MCS device recipients was reported at 2.2%, 5.5%, and 10.7%, respectively, caused by ESBL-producing Klebsiella pneumoniae, Escherichia coli, Klebsiella oxytoca, and Citrobacter freundii. Conclusions Early detection and adequate duration of therapy for ESBL-producing Enterobacteriaceae in solid organ transplants and MCS device recipients are essential in successful patient outcomes including prevention of recurrent infection.

T cell dysfunction and patient age are associated with poor outcomes after mechanical circulatory support device implantation

Immunologic impairment may contribute to poor outcomes after implantation of mechanical circulatory support device (MCSD), with infection often as a terminal event. The study of immune dysfunction is of special relevance given the growing numbers of older patients with heart disease. The aim of the study was to define which immunologic characteristics are associated with development of adverse clinical outcomes after MCSD implantation. We isolated peripheral blood mononuclear cells (PBMC) from patients pre- and up to 20 days post-MCSD implantation and analyzed them by multiparameter flow cytometry for T cell dysfunction, including terminal differentiation, exhaustion, and senescence. We used MELD-XI and SOFA scores measured at each time point as surrogate markers of clinical outcome. Older patients demonstrated increased frequencies of terminally differentiated T cells as well as NKT cells. Increased frequency of terminally differentiated and immune senescent T cells were associated with worse clinical outcome as measured by MELD-XI and SOFA scores, and with progression to infection and death. In conclusion, our data suggest that T cell dysfunction, independently from age, is associated with poor outcomes after MCSD implantation, providing a potential immunologic mechanism behind patient vulnerability to multiorgan dysfunction and death. This noninvasive approach to PBMC evaluation holds promise for candidate evaluation and patient monitoring.

Changes in Vitamin D levels After Kidney Transplantation

Introduction Low levels of serum vitamin D are common and associated with progression of chronic kidney disease. However, the frequency of hypovitaminosis D following kidney transplantation (KT) is not well studied. We examined how vitamin D levels change post-transplant and compared the changes between patients with low-and normal-vitamin D pre-transplant. Materials and Methods We examined KT recipients from January 1, 2006, to May 31, 2016, who had 25-hydroxy vitamin D tests both before and within the first year of KT. If there were multiple vitamin D levels, we took the closest value to the transplant date and defined as pre-Tx and post-Tx vitamin D levels. Patients with vitamin D levels greater than 50 were excluded. Patients were divided into two groups according to vitamin D levels, 1) low (<30) and 2) normal (30-50). Mean vitamin D levels were compared between pre-and post-Tx using t-test analysis. Results A total of 398 patients were included in this study. Mean pre-and post-Tx vitamin D levels were 21.12 and 20.39 ng/mL, respectively. We found that 315 patients (79.15%) had low pre-Tx vitamin D levels and 83 patients (20.85%) had normal pre-Tx vitamin D levels. Post-Tx vitamin D levels were 23.13 and 19.67 ng/mL in normal and low pre-Tx vitamin D patients, respectively (p<0.01)(figure1). Patients with low pre-Tx vitamin D levels were more likely to have low post-Tx vitamin D levels (p=0.03)(table1). Furthermore, we found that 60.5% of patients with decreasing post-Tx vitamin D levels had low pre-Tx vitamin D levels while patients with normal pre-Tx vitamin D levels had a greater reduction in post-Tx vitamin D levels than patients with low pre-Tx vitamin D (figure2). Conclusions Hypovitaminosis D was very common in kidney transplant recipients. Preexisting hypovitaminosis D patients were more likely to have persistent low post-transplant vitamin D levels. Moreover, Post-transplant vitamin D levels were still lower than normal values regardless of pre-transplant vitamin D levels. Future studies should include vitamin D supplement and graft survival to support how vitamin D may impact on long-term outcome. Figure. No caption available. Figure. No caption available.

Outcome of Second Kidney Transplantation According To Previous Pediatric Donor Type: A Retrospective Cohort Analysis

Background With the prioritization of age ⩽ 18 years old at the time of registration on the kidney transplant waiting list in the United States, deceased donor rates have increased. Majority of these patients require subsequent transplantation at a later time. Previous transplant has shown an impact on posttransplant outcomes. We hypothesized that recipients of those previous pediatric deceased donor kidney transplant (DDKT) would have worse posttransplant outcomes after the second KT than those after living donor KT (LDKT). Materials and Methods We used data from the Organ Procurement Transplant Network (OPTN/UNOS) as of December 8, 2016. A retrospective cohort analysis was created to examine the outcome of 1,930 recipients being second-time kidney transplanted at age 18-30 from January 1, 2000, to September 30, 2015, with previous KT at age less than 18. Those with more than two kidney transplant episodes or multiorgan transplant were excluded. Patients were divided into two groups according to donor type of the first pediatric KT; 1) those with failed DDKT and 2) those with failed LDKT. Results Recipients of the first LDKT group were more likely to be Caucasian and have subsequent LDKT compared to the first DDKT group. (Table1) We found an increase in median time to second KT since first graft failure and second registration in recipients with previous pediatric DDKT. The median PRA was higher in those with failed DDKT as well as higher number of patients with high PRA (>80%) and very high PRA (≥98%). (Table2) Looking at the outcome after the second KT, rejection rate, graft survival of the first DDKT group were similar to the first LDKT group, however, recipients of previous LDKT were more likely to have better GFR at 3 years after the second KT. (Table3) Table. No title available. Conclusions Recipients with previously failed pediatric DDKT had higher PRA and longer waiting time before re-transplantation. However, kidney allograft outcomes after the second KT were comparable. It would be preferable to perform LDKT as the first kidney transplant in childhood and adolescence to minimize their waiting times in the future. This Project was funded by the U.S. Department of Health and Human Services, Health Resources and Services Administration, Office of Special Programs, Division of Transplatation, under contract number 234-2005-37011C. for the operation of the Organ Procurement and Transplantation Network.

Screening Coccidioides serology in kidney transplant recipients: A 10-year cross-sectional analysis

Kidney transplant recipients (KTRs) are at risk for reactivation and complicated infection due to Coccidioides. Pre‐transplant serological screening should provide benefit for patients from endemic areas. We evaluated Coccidioides seroprevalence by area of residence in KTRs at a major transplant program in Los Angeles.

Clinical phenomapping and outcomes after heart transplantation

BACKGROUND Survival after heart transplantation (HTx) is limited by complications related to alloreactivity, immune suppression, and adverse effects of pharmacologic therapies. We hypothesize that time-dependent phenomapping of clinical and molecular data sets is a valuable approach to clinical assessments and guiding medical management to improve outcomes. METHODS We analyzed clinical, therapeutic, biomarker, and outcome data from 94 adult HTx patients and 1,557 clinical encounters performed between January 2010 and April 2013. Multivariate analyses were used to evaluate the association between immunosuppression therapy, biomarkers, and the combined clinical end point of death, allograft loss, retransplantation, and rejection. Data were analyzed by K-means clustering (K = 2) to identify patterns of similar combined immunosuppression management, and percentile slopes were computed to examine the changes in dosages over time. Findings were correlated with clinical parameters, human leucocyte antigen antibody titers, and peripheral blood mononuclear cell gene expression of the AlloMap (CareDx, Inc., Brisbane, CA) test genes. An intragraft, heart tissue gene coexpression network analysis was performed. RESULTS Unsupervised cluster analysis of immunosuppressive therapies identified 2 groups, 1 characterized by a steeper immunosuppression minimization, associated with a higher likelihood for the combined end point, and the other by a less pronounced change. A time-dependent phenomap suggested that patients in the group with higher event rates had increased human leukocyte antigen class I and II antibody titers, higher expression of the FLT3 AlloMap gene, and lower expression of the MARCH8 and WDR40A AlloMap genes. Intramyocardial biomarker-related coexpression network analysis of the FLT3 gene showed an immune system-related network underlying this biomarker. CONCLUSIONS Time-dependent precision phenotyping is a mechanistically insightful, data-driven approach to characterize patterns of clinical care and identify ways to improve clinical management and outcomes.

Increased T cell immunosenescence and accelerated maturation phenotypes in older kidney transplant recipients

Older kidney transplant recipients experience increased rates of infection and death, and less rejection, compared with younger patients. However, little is known about immune dysfunction in older compared with younger kidney transplant recipients and whether it is associated with infection. We evaluated T cell phenotypes including maturation, immune senescence, and exhaustion in a novel investigation into differences in older compared with younger patients receiving identical immune suppression regimens. We evaluated PBMC from 60 kidney transplant recipients (23 older and 37 matched younger patients) by multiparameter immune phenotyping. Older kidney transplant recipients demonstrated decreased frequency of naïve CD4+ and CD8+ T cells, and increased frequency of terminally differentiated, immune senescent, and NK T cells expressing KLRG1. There was a trend towards increased frequency of T cell immune senescence in patients experiencing infection in the first year after transplantation, which reached statistical significance in a multivariate analysis. This pilot study reveals immune dysfunction in older compared with younger transplant recipients, and suggests a likely mechanism for increased vulnerability to infection. The ability to assess T cell maturation and immune senescence in transplant recipients offers the potential for risk stratification and customization of immune suppression to prevent infection and rejection after transplantation.

Transplant center support for infectious diseases

Transplant Infectious Diseases (TID) is a rapidly growing subspecialty, which has contributed significantly to improving patient outcomes after transplantation. Obtaining institutional support to implement programs that promote excellence in patient care remains a challenge for many non‐surgical transplant‐related specialties.

Fungi as Eukaryotes: Understanding the Antifungal Effects of Immunosuppressive Drugs

The immunosuppressive agents cyclosporine, tacrolimus, and sirolimus are naturally occurring products of environmental fungi or bacteria, so the fact that they possess intrinsic antifungal activity is not surprising. Both calcineurin and the target of rapamycin (TOR) are conserved across eukaryotes and share a common function, regulating the organism’s ability to react to environmental changes and response to stress. In the medically important fungi Candida, Cryptococcus, and Aspergillus, mutations in the calcineurin gene affect in vitro patterns of growth and serum sensitivity, and attenuate virulence in animal models. Notably, cyclosporine, tacrolimus, and sirolimus exhibit strong synergy with many classes of antifungal drugs including azoles, amphotericin B, and the echinocandins, with potentiation of fungicidal effects even against drug-resistant strains. Hopefully, future studies will realize the promise of exploiting the antifungal properties of the immunosuppressive drugs to help decrease the burden of these clinically important infections on patient survival.