American Journal of Transplantation

BackgroundSolid organ transplant recipients have attenuated immune responses to SARS-CoV-2 vaccines. In this study, we report on immune responses to 3rd- (V3) and 4th- (V4) doses of heterologous and homologous vaccines in a kidney transplant population. Methods724 kidney transplant recipients were prospectively screened for serological responses following 3 primary doses of a SARS-CoV2 vaccine. 322 patients were sampled post-V4 for anti-spike (anti-S), with 69 undergoing assessment of SARS-CoV-2 T-cell responses. All vaccine doses were received post-transplant, only mRNA vaccines were used for V3 and V4 dosing. All participants had serological testing performed post-V2 and at least once prior to their 1st dose of vaccine. Results586/724 (80.9%) patients were infection-naive post-V3; 141/2586 (24.1%) remained seronegative at 31 (21-51) days post-V3. Timing of vaccination in relation to transplantation, OR: 0.28 (0.15-0.54), p=0.0001; immunosuppression burden, OR: 0.22 (0.13-0.37), p<0.0001, and a diagnosis of diabetes, OR: 0.49 (0.32-0.75), p=0.001, remained independent risk factors for non-seroconversion. Seropositive patients post-V3 had greater anti-S if primed with BNT162b2 compared with ChAdOx1, p=0.001. Post-V4, 45/239 (18.8%) infection-naive patients remained seronegative. De novo seroconversion post-V4 occurred in 15/60 (25.0%) patients who were seronegative post-V3. There was no difference in anti-S post-V4 by vaccine combination, p=0.50. Anti-S post-V4 were sequentially greater in those seroconverting post V2- compared with V3-, and V3- compared with V4-, at 1561 (567-5211), 379 (101-851) and 19 (9.7-48) BAU/ml respectively. T-cell responses were poor, with only 11/54 (20.4%) infection-naive patients having detectable T-cell responses post-V4, with no difference seen by vaccine type. ConclusionA significant proportion of transplant recipients remain seronegative following 3- and 4- doses of SARS-CoV-2 vaccines, with poor T-cell responses, and are likely to have inadequate protection against infection.

BackgroundSolid organ transplant recipients have attenuated immune responses to SARS-CoV-2 vaccines. Emerging evidence suggests at least equivalent immunogenicity of heterologous compared with homologous vaccine regimens in the general population. In this study, we report on immune responses to 3rd dose BNT162b2 vaccines in transplant recipients either primed with ChAdOx1 or BNT162b2. Methods700 kidney transplant recipients were prospectively screened for serological responses (median time of 33 (21-52) days) following 3 primary doses of a SARS-CoV2 vaccine. All vaccine doses were received post-transplant, and all 3rd doses were BNT162b2. All participants had serological testing performed post-2nd vaccination at a median time of 34 (IQR 26-46) days following the 2nd inoculation, and at least once prior to their 1st dose of vaccine. Results366/700 (52.3%) participants were primed with BNT162b2, whilst 334/700 (47.7) had received ChAdOx1. Overall, 139/700 (19.9%) participants had evidence of prior infection. Of 561 infection naive participants, 263 (46.9%) had no detectable anti-S following 2-doses of vaccine (V2). 134 (23.9%) participants remained seronegative post 3rd vaccine (V3); 54/291 (18.6%) and 79/270 (29.3%) of participants receiving BNT162b2 and ChAdOx1 respectively, p=0.0029. Median anti-S concentrations were significantly higher post-V3 in patients who had received BNT162b2 compared with ChAdOx1, at 612 (27-234) versus 122 (7.1-1111) BAU/ml respectively, p<0.0001. Cellular responses were investigated in 30 infection naive participants at a median time of 35 (24-46) days post-V3. Eighteen of 30 (60.0%) participants had undetectable T-cell responses. There were neither qualitative or quantitative differences in T-cell responses between those patients who received BNT162b2 or ChAdOx1 as their first 2-doses, with 10/16 (62.5%) and 8/14 (57.1%) respectively having undetectable T-cell responses, p=0.77. ConclusionA significant proportion of transplant recipients remain seronegative following 3 doses of SARS-CoV-2 vaccines, with anti-S concentrations lower in patients receiving heterologous versus homologous vaccinations.

BackgroundAttenuated immune responses to mRNA SARS-CoV-2 vaccines have been reported in solid organ transplant recipients. Most studies have assessed serological responses alone, and there is limited immunological data on vector-based vaccines in this population. This study compares the immunogenicity of BNT162b2 with ChAdOx1 in a cohort of kidney transplant patients, assessing both serological and cellular responses. Methods920 patients were screened for spike protein antibodies (anti-S) following 2 doses of either BNT162b2 (n=490) or ChAdOx1 (n=430). 106 patients underwent assessment with T-cell ELISpot assays. 65 health care workers were used as a control group. ResultsAnti-S was detected in 569 (61.8%) patients. Seroconversion rates in infection-naive patients who received BNT162b2 were higher compared with ChAdOx1, at 269/410 (65.6%) and 156/358 (43.6%) respectively, p<0.0001. Anti-S concentrations were higher following BNT162b, 58(7.1-722) BAU/ml, compared with ChAdOx1, 7.1(7.1-39) BAU/ml, p<0.0001. Calcineurin inhibitor monotherapy, vaccination occurring >1st year post-transplant and receiving BNT162b2 was associated with seroconversion. Only 28/106 (26.4%) of patients had detectable T-cell responses. There was no difference in detection between infection-naive patients who received BNT162b2, 7/40 (17.5%), versus ChAdOx1, 2/39 (5.1%), p=0.15. There was also no difference in patients with prior infection who received BNT162b2, 8/11 (72.7%), compared with ChAdOx1, 11/16 (68.8%), p=0.83. ConclusionsEnhanced humoral responses were seen with BNT162b2 compared with ChAdOx1 in kidney transplant patients. T-cell responses to both vaccines were markedly attenuated. Clinical efficacy data is still required but immunogenicity data suggests weakened responses to both vaccines in transplant patients, with ChAdOx1 less immunogenic compared with BNT162b2.

The main challenge of immunosuppressive therapy after solid organ transplantation is to create a new immunological balance that prevents organ rejection and does not promote opportunistic infection. Torque teno virus (TTV) a ubiquitous and non-pathogenic single-stranded DNA virus has been proposed as a marker of functional immunity in immunocompromised patients. Here investigate whether TTV loads predict the risk of common viral infection and allograft rejection in kidney transplantation recipients. In a retrospective cohort of 389 kidney transplantation recipients, individual TTV loads in were measured by qPCR in consecutive plasma samples during one year follow-up. The endpoints were allograft rejection, BK polyomavirus (BKPyV) viremia and cytomegalovirus (CMV) viremia. Repeated TTV measurements and rejection and infection survival data were analysed in a joint model. During follow-up, TTV DNA detection in the transplant recipients increased from 85 to 100%. The median viral load increased to 107 genome copies/ml within three months after transplantation. Rejection, BKPyV viremia and CMV viremia occurred in 23%, 27% and 17% of the patients, respectively. With every 10-fold TTV load-increase, the risk of rejection decreased considerably (HR: 0.74, CI 95%: 0.71-0.76), while the risk of BKPyV and CMV viremia remained the same (HR: 1.03, CI 95%: 1.03-1.04 and HR: 1.01, CI 95%: 1.01-1.01). In conclusion, TTV load kinetics predict allograft rejection in kidney transplantation recipients, but not the BKPyV and CMV infection. The potential use of TTV load levels as a guide for optimal immunosuppressive drug dosage to prevent allograft rejection deserves further validation.

The long-term impact of SARS-CoV-2 infection on kidney allograft survival remains incompletely understood, particularly regarding the influence of vaccination, acute kidney injury (AKI), and post-infection immunosuppression. We conducted a retrospective analysis of 129 kidney transplant recipients with confirmed SARS-CoV-2 infection between March 2020 and March 2022 with a median follow-up of 50 months. Among 129 recipients, 106 (82%) received vaccination at any time before or after SARS-CoV-2 infection (82%) while 23 (18%) remained unvaccinated. Unvaccinated patients experienced significantly lower long-term graft survival (52% vs. 85%; p = 0.0004) and patient survival (83% vs. 99%; p = 0.0003) compared with vaccinated recipients. AKI occurred in 15% of recipients and independently predicted graft failure (aHR 2.88; p = 0.0341). Post-SARS-CoV-2 serum creatinine and albuminuria were strong prognostic markers of graft loss. Unvaccinated status independently predicted graft failure in both transplantation-anchored (aHR 2.80; p = 0.0342) and SARS-CoV-2-anchored models (aHR 5.31; p = 0.0004). Continuation of mycophenolate mofetil at post-infection assessment was associated with reduced graft-failure risk (aHR 0.99; p = 0.0193). These findings underscore the importance of sustained vaccination in preserving long-term allograft function.

BackgroundKidney transplant recipients (KTR) have a diminished response to SARS-CoV-2 vaccination in comparison to immunocompetent individuals. Deeper understanding of the antibody response in KTRs following third-dose vaccination would enable identification of those who remain unprotected against Omicron and require additional treatment strategies. MethodsWe profiled antibody responses in KTRs pre- and at one and three months post-third-dose SARS-CoV2 mRNA-based vaccine. Anti-spike and anti-RBD IgG levels were determined by ELISA. Neutralization against wild-type, Beta, Delta and Omicron (BA.1) variants was determined using a SARS-CoV-2 spike pseudotyped lentivirus assay. Results44 KTRs were analysed at 1 and 3 months (n=26) post-third-dose. At one month, the proportion of participants with a robust antibody response had increased significantly from baseline, but Omicron-specific neutralizing antibodies were detected in just 45% of KTRs. Median binding antibody levels declined at 3 months, but the proportion of KTRs with a robust antibody response was unchanged. 38.5% KTRs maintained Omicron-specific neutralization at 3 months. No clinical variables were significantly associated with detectable Omicron neutralizing antibodies, but anti-RBD titres appeared to identify those with Omicron-specific neutralizing capacity. ConclusionOver 50% of KTRs lack an Omicron-specific neutralization response 1 month following a third mRNA-vaccine dose. Among responders, binding and neutralizing antibody responses were well preserved at 3 months. Anti-RBD antibody titres may be a useful identifier of patients with detectable Omicron neutralizing antibody response. Trial registrationClinical Trials Ontario: ID 3604 FundingFunded by the St. Michaels Hospital Foundation (CMM, DAY) and the Public Health Agency of Canada, through the COVID-19 Immunity Task Force (MAH, MJO, AL).

The development of de novo donor-specific antibodies (DSAs) against HLA is associated with premature graft failure in kidney transplantation. However, rates and factors influencing de novo DSA formation vary widely across the literature. We aimed to identify pre-transplant factors influencing the development of de novo HLA-specific antibodies following kidney transplantation using machine learning. Data from 460 kidney transplant recipients at a single centre between 2009-2014 were analysed. Pre-transplant variables were collected, and post-transplant sera were screened for HLA antibodies. Positive samples were investigated using Single Antigen Bead (SAB) testing. Machine learning models (Classification and Regression Trees, Random Forest, XGBoost, CatBoost) were trained on a training set of pre-transplant data to predict de novo DSA formation, with and without SMOTE oversampling. Model performance was evaluated on an independent testing set using F1 scores, and feature importance was assessed using SHAP. In the full cohort analysis, XGBoost models performed the best, with F1 scores of 0.54-0.59 without SMOTE and 0.72-0.79 with SMOTE. The strongest predictors were pre-transplant HLA antibodies, number of kidney transplants, cold ischemia time (CIT), recipient age and female gender. SHAP dependence plots showed that pre-existing HLA antibodies and past transplants increased the risk of de novo DSA development. In the unsensitised subgroup analysis, model performance was poor. Machine learning models can be used to identify pre-transplant risk factors for de novo HLA-specific antibody development in kidney transplantation. Monitoring and risk-stratifying patients based on these factors may help guide preventive immunological strategies and recipient selection to improve long-term allograft outcomes. Translational statementThis study identified pre-transplant risk factors for the development of de novo HLA-specific antibody in kidney transplantation. Monitoring and risk-stratifying patients based on these factors may help guide preventive immunological strategies and recipient selection to improve long-term allograft outcomes.

BackgroundMultiple factors affecting COVID19 vaccine induced antibody responses in SARS-CoV2 uninfected immunosuppressed solid organ transplant recipients have been reported; however, there is still a lack of information on non-ACE2 competing cross-CoV2 neutralizing functional antibodies induced in these cohorts, and similarly the vaccine efficacy in prior CoV2-infected immunosuppressed individuals is not well understood. MethodsCOVID19 vaccine efficacy was compared in a panel of kidney and heart transplant recipients who were either CoV2 uninfected (n=63) or CoV2 infected (n=13) prior to receiving two or three doses of mRNA vaccines using pseudoviral neutralization assays against eight CoV2 strains (the CoV2_D614G ancestral strain, alpha, beta, gamma, delta, kappa, lambda, and omicron-BA1 variants), while plasma antibody titers were determined by ELISA using recombinant CoV2-RBD-wt proteins. ResultsMinimally protective neutralizing plasma antibody titers (IC50 [&ge;] 1:50) against the variants were recorded 7-14% and 25-35% after the second and third doses respectively, with Omicron being the most resistant. In contrast, all previously infected vaccinees possessed minimal protective plasma titers against D614G after either two or three vaccine doses, with 11/13 exhibiting strong protection (IC50[&ge;] 1:500) and 10/13 exceeding the minimal protective titer against Omicron. Absorption of the selected plasma with immobilized parental RBD removed [&ge;] 90% of its neutralizing activity, indicating that the dominant neutralization targets were in the RBD. ConclusionsThis study showed that CoV2 infection followed by vaccination, but not vaccination alone, induces the presence of potent highly cross-reactive CoV2 neutralizing plasma antibodies that extend to Omicron variants, even in immunosuppressed SOTRs.

The COVID-19 pandemic has reduced access to solid organ transplantation, compounding organ shortages and waitlist mortality. A continued area of uncertainty is the safety of transplanting organs recovered from SARS-CoV-2 infected donors, as autopsies of patients who died with COVID-19 show that the virus can be found in extra-pulmonary organs1. Case reports and series on transplantation of these organs have been published 2, 3, but population-level data is lacking. We queried a national transplant database for recipients of organs recovered from donors recently infected by SARS-CoV-2. For organs with more than 50 cases, these were then propensity-score matched at a ratio of 1:10 to similar recipients of organs recovered from donors who tested negative for SARS-CoV-2 (controls). Data were extracted from the Scientific Registry of Transplant Recipients (SRTR - v2203 - updated March 2022), which collects detailed information on all solid organ transplants in the United States since 1986. Cases were defined as adult ([&ge;] 18 years) recipients of organs recovered from deceased donors who tested positive for SARS-CoV-2 by nasopharyngeal or lower respiratory sample polymerase chain reaction or antigen assay within 7 days of organ transplantation. Multiple organ transplants were excluded. There were 775 kidney, 330 liver, 123 heart, 44 kidney-pancreas, 16 lung, 5 pancreas, and 3 small bowel transplants of organs recovered from 393 deceased donors recently infected by COVID-19. For kidney, liver, and heart transplants, Kaplan-Meier curves of both overall and graft survival at 90 days were similar between cases and controls. Our data shows that transplanting kidneys, livers, and hearts recovered from deceased donors recently infected by SARS-CoV-2 was not associated with increased recipient mortality or worse graft-survival. This should help transplant providers make decisions regarding acceptance of these organs, and counsel transplant candidates on the safety of receiving them. The limited number of kidney-pancreas, lung, pancreas, and intestinal cases precludes significant conclusions for these organs. Our data also strongly supports the notion that donors with recent COVID-19 infection should not be automatically excluded from the donor pool. The limited number of kidney-pancreas, lung, pancreas, and intestinal cases precludes significant conclusions for these organs. Limitations include lack of data on donor infection timeline and estimates of viral load (PCR cycle thresholds), description of donor COVID-19 symptomatology at organ procurement, donor or recipient vaccination or prior COVID-19 infection status, which are not tracked in the database. We did not have information regarding transmission of COVID-19 to transplant recipients. Future analysis of updated versions of the database should help address. Our data strongly support the notion that donors with recent COVID infection should not be automatically excluded from the donor pool. Prospective studies are needed to confirm our findings and provide insights on optimal post-transplant management of these recipients.

BackgroundData on age-related differences in rejection rates, infectious episodes and tacrolimus exposure in pediatric kidney transplant recipients (pKTR) on a uniform tacrolimus-based immunosuppressive regimen are scarce. MethodsWe therefore performed a large-scale analysis of 802 pKTR from the CERTAIN registry from 40 centers in 14 countries. Inclusion criteria were a tacrolimus-based immunosuppressive regimen and at least two years of follow-up. The patient population was divided into three age groups (infants <6 years, school-aged children 6-12 years, and adolescents >12 years) to assess age-related differences in outcome. ResultsMedian follow-up was 48 months (IQR, 36-72). Within the first 2 years post-transplant, infants had a significantly higher incidence of infections (80.6% vs. 55.0% in adolescents, P<0.001) and a significantly higher number of cumulative hospital days (median 13 days vs. 7 days in adolescents, P < 0.001). Adolescents had a significantly higher rate of biopsy-proven acute rejection episodes in the first year post-transplant (21.7%) than infants (12.6%, P=0.007). Infants had significantly lower tacrolimus trough levels, lower concentration-to-dose ratios as an approximation for higher tacrolimus clearance, and higher intra-patient variability (all P < 0.01) than adolescents. ConclusionsThis largest study to date in European pKTR on a tacrolimus-based immunosuppressive regimen shows important age-related differences in rejection rates, infection episodes, tacrolimus exposure and clearance. These data suggest that immunosuppressive therapy in pKTR should be tailored according to the age-specific risk profiles of this heterogeneous patient population.

HLA evolutionary divergence (HED), a continuous metric quantifying the differences between each amino acid of two homologous HLA alleles, reflects the importance of the immunopeptidome presented to T lymphocytes. It has been associated with rejection after liver transplantation. This retrospective cohort study aimed to analyze the potential effect of donor or recipient HED on liver transplant rejection in a new series of patients transplanted during childhood and followed in adulthood. The study included 120 children who had been transplanted between 1991 and 2010 and were followed by routine biopsies and histological evaluations with a median of 14.1 years post-LT. Liver biopsies were performed routinely 1, 5, 10 and 20 years after transplantation and in the event of liver dysfunction. HED was calculated using the physicochemical Grantham distance for donor and recipient class I (HLA-A, -B, -C) and class II (HLA-DRB1, -DQB1) alleles. The influence of HED on rejection was analyzed using IPW and target trial emulation using the g method. Based on the IPW score, donor HED class I was correlated with the occurrence of late (>90 days) rejection (HR, 1.19, 95% CI: 1.01-1.40) independently of HLA mismatches, donor age and initial induction. This emulated target trial confirmed that donor HED class I has a causal effect on liver graft rejection and this relationship was observed long-term.

IntroductionDonor-derived cell-free DNA (dd-cfDNA) is a standard-of-care biomarker in kidney transplantation, reported as percentage of total cfDNA or copies/mL. We hypothesized that combining both metrics into a continuous composite score would reduce false classifications thus improving the accuracy of rejection diagnosis. MethodsWe analyzed 443 dd-cfDNA measurements in 383 individual patients from five independent kidney transplant cohorts with both percentage and copies/mL. A random discovery set of 31 biopsy-proven rejection and 29 non-rejection cases was used to derive a continuous composite score (CM-Score) integrating dd-cfDNA (%) and copies/mL. Fixed thresholds from the discovery group were validated in 75 rejections and 279 non-rejections for diagnostic performance and compared to twelve published cohorts. ResultsThe CM-Score outperformed dd-cfDNA percentage and cp/mL alone. At the predefined threshold (at 25% prevalence), the CM-Score retained a high NPV of 91% (89-93%), while significantly improving PPV to 80% (78-83%; P<0.002), compared to the published values (weighted average NPV: 88%; 89-90%; PPV: 51% 50-53%, N=6,861). In addition, a decision curve analysis yielded a significantly higher net benefit for the CM-Score (P<0.003; prevalence 10-25% at threshold 15-50%). This superior diagnostic performance of the CM-Score can broaden the applicability of dd-cfDNA to real-world transplantation populations. ConclusionsThe CM-Score is a robust and clinically meaningful tool that improves diagnostic accuracy for both ruling-out and ruling-in rejection using dd-cfDNA and establishes itself as a superior stand-alone metric with clear potential to improve decision-making in kidney transplantation. Lay Summary (Clinical)Kidney transplant failure remains a major concern, and early detection of injury is crucial to prevent long-term damage. A less invasive alternative to a biopsy is a simple blood test that measures tiny fragments of DNA from the transplanted kidney, called donor-derived cell-free DNA (dd-cfDNA). These results can be reported either as a percentage of total DNA or as the number of DNA copies in the blood. We examined whether combining both measurements could improve the detection of rejection. Using data from five transplant cohorts, we developed a combined measure (CM-score) and validated it in 279 samples without rejection and 75 with rejection. At an assumed rejection rate of 25%, it correctly identified rejection with a positive predictive value of 80% and ruled it out with a negative predictive value of 91%. Overall, the CM-score may help doctors diagnose rejection more accurately and make timely treatment decisions.

BackgroundPost-transplant lymphoproliferative disorder (PTLD) is a life-threatening complication following lung transplant. We aimed to study the incidence of and risk factors for PTLD in adult lung transplant recipients. MethodsThe International Society of Heart and Lung Transplant (ISHLT) Registry was used to identify adult, first-time, single and bilateral lung transplant recipients with at least one year follow-up and from centers reporting PTLD between January 2006 and June 2015. Kaplan Meier method was used to describe timing and distribution of PTLD. Univariable and multivariable Cox proportional hazards regression models were used to examine the clinical characteristics associated with PTLD. ResultsOf the 19,309 lung transplant recipients in the analysis cohort, we identified 454 cases of PTLD. Cumulative incidence of PTLD was 1.1% (95% CI = 1.0%, 1.3%) at 1 year and 4.1% (95% CI= 3.6%, 4.6%) at 10-years. We observed that 47.4% of all PTLD cases occurred within the first year following lung transplantation. In the multivariable model, independent risk factors for PTLD included age, EBV mismatch and native lung diseases. The risk of PTLD during the first year after transplant increased with increasing age in patients between 45 to 62 years at time of transplantation; the inverse was true for ages less than 45 year or greater than 62 years. Finally, receiving a donor organ with human leukocyte antigen (HLA) types A1 and A24 was associated with an increased risk of PTLD while the recipient HLA type DR11 was associated with a decreased risk. ConclusionsOur study indicates that PTLD is a relatively rare complication among adult lung transplant recipients. We identified clinical characteristics that are associated with increased risk of PTLD.

BackgroundOrgan graft recipients receiving immunosuppressive therapy are likely to be at heightened risk for the Coronavirus Disease 2019 (Covid-19) and adverse outcomes including death. It is therefore important to characterize the clinical course and outcome of Covid-19 in this vulnerable population and identify therapeutic strategies that are safe. MethodsWe performed a retrospective chart review of 54 adult kidney transplant patients diagnosed with Covid-19 and all managed in New York State, the epicenter of Covid-19 pandemic. All 54 patients were evaluated by video visits, or phone interviews, and referred to our Fever Clinic or Emergency Room for respiratory illness symptoms consistent with Covid-19 and admitted if deemed necessary from March 13, 2020 to April 20, 2020. Characteristics of the patients were stratified by hospitalization status and disease severity. Clinical course including alterations in immunosuppressive therapy were retrieved from their electronic medical records. Primary outcomes included recovery from Covid-19 symptoms, acute kidney injury, graft failure, and case fatality rate. ResultsOf the 54 SARS-Cov-2 positive kidney transplant recipients, 39 with moderate to severe symptoms were admitted and 15 with mild symptoms were managed at home. Hospitalized patients compared to non-hospitalized patients were more likely to be male, of Hispanic ethnicity, and to have cardiovascular disease. At baseline, all but 2 were receiving tacrolimus, mycophenolate mofetil (MMF) and 32 were on a steroid free immunosuppression regimen. Tacrolimus dosage was reduced in 46% of hospitalized patients and maintained at baseline level in the non-hospitalized cohort. Mycophenolate mofetil (MMF) dosage was maintained at the baseline dosage in 11% of hospitalized patients and 64% of non-hospitalized patients and was stopped in 61% hospitalized patients and 0% in the non-hospitalized cohort. Azithromycin or doxycycline were prescribed at a similar rate among hospitalized and non-hospitalized patients (38% vs. 40%). In addition, 50% of hospitalized patients were treated for concurrent bacterial infections including pneumonia, urinary tract infections and sepsis. Hydroxychloroquine was prescribed in 79% of hospitalized patients and only one of 15 non-hospitalized patients. Acute kidney injury occurred in 51% of hospitalized patients. Patients with severe disease were more likely to have elevations in inflammatory biomarkers at presentation. At a median of 21 days follow up, 67% of patients have had their symptoms resolved or improved and 33% have persistent symptoms. Graft failure requiring hemodialysis occurred in 3 of 39 hospitalized patients (8%). Three of 39 (8%) hospitalized patients expired and none of the 15 non-hospitalized patients expired. ConclusionsClinical presentation of Covid-19 in kidney transplant recipients was similar to what has been described in the general population. The case fatality rate in our entire cohort of 54 kidney transplant recipients was reassuringly low and patients with mild symptomology could be successfully managed at home. Data from the our study suggest that a strategy of systematic screening and triage to outpatient or inpatient care, close monitoring, early management of concurrent bacterial infections and judicious use of immunosuppressive drugs rather than cessation is beneficial.

BackgroundDespite current matching efforts to identify optimal donor-recipient pairs in kidney transplantation, alloimmunity remains a major proponent of late transplant failure. While kidney allocation based on human leukocyte antigen (HLA) matching has markedly prolonged short-term graft survival, new data suggests that additional genetic parameters in donor-recipient matching could help improve the long-term outcomes. Here, we studied the impact of a recently discovered non-muscle myosin heavy chain 9 gene (MYH9) polymorphism on kidney allograft failure. MethodsWe conducted a prospective observational cohort study, analyzing the DNA of 1,271 kidney donor-recipient transplant pairs from a single academic hospital for the MYH9 rs11089788 C>A polymorphism. The association of the MYH9 genotype with the risk of graft failure (primary outcome), biopsy-proven acute rejection (BPAR), and delayed graft function (DGF) (secondary outcomes) were determined. ResultsThe MYH9 polymorphism in the donor was not associated with 15-year death-censored kidney graft survival, whereas a trend was seen for the association between the MYH9 polymorphism in the recipient and graft failure (recessive model, P=0.056). Having the AA-genotype of the MYH9 polymorphism in recipients was associated with a higher risk of DGF (P=0.031) and BPAR (P=0.021), although the significance was lost after adjustment for potential confounders (P=0.15 and P=0.10, respectively). The combined presence of the MYH9 polymorphism in donor-recipient pairs was significantly associated with long-term kidney allograft survival (P=0.036), in which recipients with an AA-genotype receiving a graft with an AA-genotype had the worst outcome. After adjustment for covariates, this combined genotype remained significantly associated with 15-year death-censored kidney graft survival (HR 1.68, 95%-CI: 1.05 - 2.70, P=0.031). ConclusionsOur results reveal that recipients with an AA-genotype MYH9 polymorphism receiving a donor kidney with an AA-genotype, have a significantly elevated risk of graft failure after kidney transplantation. Key pointsO_LIIn recipients, the MYH9 SNP was associated with delayed graft function and biopsy-proven acute rejection after kidney transplantation, although the significance was lost in multivariable analysis. C_LIO_LIPresence of the MYH9 variant in both the donor and recipient significantly associated with long-term kidney allograft survival in multivariable analysis. C_LIO_LIOur present findings suggests that matching donor-recipient transplant pairs based on the MYH9 polymorphism may attenuate the risk of graft loss. C_LI

AimAllograft survival post-kidney transplantation (KT) are in large part attributed to genetics, which render the recipient susceptible or protected from allograft rejection. KT studies involving single nucleotide polymorphisms (SNPs) have reported the association of interleukin-18 (IL-18) with KT and its role in allograft rejection. However, the reported outcomes been inconsistent, prompting a meta-analysis to obtain more precise estimates. MethodsWe posed two hypotheses about the IL-18 SNPs: their association with KT (H1), and increase or decrease in the risks of allograft rejection (H2). Using standard genetic models, we estimated odds ratios [ORs] and 95% confidence intervals by comparing the IL-18 genotypes between two groups: (i) patients and controls for H1 (GD: genotype distribution analysis); (ii) rejectors and non-rejectors for H2 (allograft analysis). Multiple comparisons were corrected with the Holm-Bonferroni (HB) test. Subgrouping was ethnicity-based (Asians and Caucasians). Heterogeneity was outlier-treated and robustness of outcomes was sensitivity-treated. ResultsThis metaanalysis generated eight significant outcomes, which HB filtered into four core outcomes, found in the dominant/codominant models. Two of the four were in GD, indicating associations of the IL-18 SNPs with KT (ORs 1.34 to 1.39, 95% CIs 1.13-1.70, PHB = .0007-.004). The other two were in allograft analysis indicating reduced risk with HB P-values of .03 for overall (OR 0.74, 95% CI 0.56-0.93) and Asian (OR 0.70, 95% CI 0.53-0.92). In contrast to the protected Asian subgroup, Caucasians showed non-significant increased risk (OR 1.20. 95% CI .82-1.75, Pa = .35). Sensitivity treatment conferred robustness to all the core outcomes. ConclusionsOverall association of IL-18 SNPs with KT was significant (up to 1.4-fold) and Asians KT recipients were protected (up to 30%). Enabled by outlier treatment, these findings were supported by non-heterogeneity and robustness. More studies may confirm or modify our findings.

BackgroundThe effects of Banff histological diagnoses on kidney transplant outcome have been well characterized. However, repeated observation of such histological injury across multiple biopsies in kidney transplant recipients remains insufficiently explored. MethodsIn an observational cohort (N=1819 transplantations with 5736 post-transplant biopsies, recurrent event survival models quantified transitions between diagnoses of T-cell mediated rejection (TCMR), antibody-mediated rejection (AMR), DSA-negative C4d-negative microvascular inflammation (MVIDSA-/C4d-), BK polyomavirus nephropathy (BKPyVAN), borderline TCMR (bTCMR), and probable AMR (pAMR), revealing patterns in the disease trajectories. In two observational cohorts (N=1818 transplantations with 5732 biopsies, N=853 transplantations with 975 biopsies), time-dependent cumulative covariates were constructed for TCMR, AMR, MVIDSA-/C4d- and BKPyVAN, enabling estimation of associations of repeated diagnoses with graft failure using multivariable cause-specific Cox models. ResultsThe incidence rate of a diagnosis was most strongly associated with earlier diagnosis of the same type, but associations between different types of diagnoses also occurred. The hazard of kidney graft failure was significantly increased by repeated observation of TCMR in multiple biopsies (HR 7.97, 95% CI 4.94 - 12.86), as well as by repeated AMR (HR 6.19, 95% CI 3.15 - 12.17), repeated MVIDSA-/C4d- (HR 4.53, 95% CI 2.15-9.54) and repeated BKPyVAN (HR 10.90, 95% CI 5.83 - 20.35). The hazard of graft failure was increased more after repeated diagnoses in transplants than after first diagnoses. The effects of repeated TCMR and repeated AMR remained significant even when observed in protocol biopsies in the absence of graft dysfunction. Repeated observation of BKPyVAN was the most detrimental of all diagnoses when observed in indication biopsies, but it was the least harmful when observed in protocol biopsies. ConclusionIncidence of Banff histological diagnoses appears to be affected by earlier diagnoses, especially those of the same type. These repeated observations of a specific diagnosis have an additional effect on the hazard of graft failure, underscoring a critical unmet need for adequate treatment strategies for these recurrent or persistent injury processes. Lay summaryIn two observational cohorts of 1819 and 750 kidney transplant recipients, kidney transplant biopsies were taken at multiple time points after transplantation. Based on the Banff classification for transplant pathology, various post-transplant diseases were diagnosed, often at more than one time point during follow-up. We assessed patterns in the occurrence of diagnoses over time, and related these diagnoses to survival of the kidney grafts using survival models with time-dependent cumulative diagnoses. We found that repeated observation of the same diagnosis was much more common than consecutive observations of different diagnoses. Repeated diagnoses of tissue injury also decreased kidney graft survival more compared to single diagnoses. This indicates that treatment options for patients with repeated or persistent diagnoses are currently inadequate and novel strategies are needed.

BackgroundManagement of COVID-19 in transplant patients is a big challenge. Data on immunosuppression management, clinical picture, and outcomes are lacking. ObjectivesTo summarize the current literature on COVID-19 in transplant patients especially the data regarding the immunosuppression protocols, clinical presentation, and outcomes. Search strategyA systematic search of MEDLINE, EBSCO, CENTRAL, CINAHL, LitCovid, Web of Science, and Scopus electronic databases. The references of the relevant studies were also searched. The search was last updated on June 3, 2020. Selection CriteriaPrimary reports of solid organ transplant patients who developed COVID-19. An overlap of cases in different reports was checked. Data collection and analysisA descriptive summary of immunosuppression therapy (before and after COVID-19), clinical presentation (symptoms, imaging, laboratory, and disease severity), management (oxygen therapy, antiviral, and antibacterial), major outcomes (Intensive care admission, invasive mechanical ventilation, acute kidney injury), and mortality. Main resultsWe identified 74 studies reporting 823 cases of solid organ transplantation with COVID-19. Among 372 patients, 114 (30.6%) were mild COVID-19, 101 (27.2%) moderate, and 157 (42.2%) severe or critical. Major outcomes included intensive care unit admission, invasive ventilation, and acute kidney injury, which occurred in 121 (14.7%), 97 (11.8%), and 63 (7.7%) of patients, respectively. Mortality was reported in 160 (19.4%) patients. Missing individual data hindered making clinical correlations. ConclusionCOVID-19 in solid organ transplant patients probably has a more disease severity, worse major outcomes (Intensive care admission, invasive ventilation, acute kidney injury), and higher mortality than in non-transplant patients.

Background and objectivesT cell mediated rejection (TCMR) is the most frequent type of acute rejection and is associated with kidney allograft failure. Almost 40% of TCMR episodes fail to respond to anti-rejection therapy. FOXP3 is a specification factor for regulatory T cells and our single center study of 83 kidney allograft recipients showed that urinary cell FOXP3 mRNA level is diagnostic of TCMR and predicts TCMR reversibility and allograft survival. The objective of the current study is to determine whether our original findings could be replicated in an independent cohort of 480 kidney allograft recipients enrolled in the multicenter Clinical Trials of Organ Transplantation (CTOT)-04. Design, setting, participants, and measurementsWe measured levels of FOXP3 mRNA and levels of mRNA for CD25, CD3E, and perforin, and 18S rRNA in 3559 urines from 480 kidney allograft recipients prospectively enrolled in CTOT-04. RNA was isolated from the urinary cells and preamplification-enhanced real-time quantitative PCR assays were used to measure mRNAs. Results18S rRNA normalized levels of mRNA for FOXP3 (P=0.01, Kruskal-Wallis test), CD25 (P=0.01), CD3E (P<0.0001), and perforin (P<0.0001) distinguished patients with TCMR biopsies from those with No Rejection biopsies and those with stable graft function. FOXP3 mRNA level, but not the levels of mRNA for CD25, CD3E, or perforin, predicted TCMR reversal (AUC=0.764; 95% confidence interval, 0.611 to 0.917; P=0.008). Multivariable logistic regression analysis showed that FOXP3 mRNA level remains predictive after adjustment for potential cofounders. Kaplan-Meier survival curve analysis showed that FOXP3 mRNA level (P=0.0306) but not the levels of mRNA for CD25, CD3E, or perforin, is associated with kidney allograft survival. ConclusionIn the independent CTOT-04 cohort, we demonstrate that urinary cell level of FOXP3 mRNA is diagnostic of TCMR, predicts its reversibility, and is prognostic of kidney allograft survival following an episode of TCMR.

BackgroundKidney transplant recipients (KTRs) were given a 3-dose primary series of COVID-19 vaccination as they were vulnerable to infection due to immunosuppression. MethodsThis study was a longitudinal evaluation of nAB dynamics in 43 KTRs in a low-middle income setting receiving 3-dose homologous (mRNA-1273- mRNA-1273- BNT162b2) vaccination against COVID-19. Samples were obtained at time-points (TP) 0- pre-vaccination, TP1- 1 month post first dose(mRNA-1273), TP2-1-month post second dose (mRNA-1273), TP3- 4 months post-second dose, TP4- 2 weeks post-third dose(BNT162b2), TP5-5 months post-third dose and TP6-12 months-post third dose. Anti-SARS-CoV-2 nAB were detected using Genscript cPassTM pseudoviral neutralization kit. Demographic and clinical details were obtained through interviewer administered questionnaires. ResultsPre-vaccination serum analysis showed n=7 KTRs had prior COVID-19 infection, classified as infected+vaccinated, while others were vaccinated. Both groups were similar in age(41.7years vs 46.7years,p=0.2383), gender, and transplant characteristics. Seroconversion and MAB in the vaccinated and infected+vaccinated KTRs were:TP1-8.3% vs 100%(p<0.001), MAB-64.3IU/ml vs 1424IU/ml(p=0.0167TP2-52.7% vs 100%(p=0.0194), MAB-175IU/ml vs 2790IU/ml(p<0.0001), TP3-100% vs 100%, MAB-106IU/ml vs 2153IU/ml(p=0.0002), TP4-100% vs 100%, MAB-736 IU/ml vs 2152IU/ml(p=0.0307) and TP6-100% vs 100%, MAB >2565IU/ml vs >3028IU/ml(p=0.5238) No factors were associated with seroconversion or MAB. ConclusionKTRs receiving a three-dose mRNA COVID-19 vaccine regime maintained strong nAB levels at one-year follow-up, with comparable antibody levels seen between KTRs with prior infection + vaccination and vaccination alone.