The impact of early and late acute rejection on graft survival in renal transplantation

Serum IL-6 predicts risk of kidney transplant failure independently of immunological risk

Interleukin-6 (IL-6) is an important immune mediator and a target for novel antibody therapies. In this study, we aimed to determine whether serum IL-6 levels are associated with immunological risk, allograft rejection and outcomes in kidney transplant (Ktx) patients. We retrospectively analyzed the data of 104 patients who underwent Ktx at our center between 2011 and 2015. The patients were divided into high- and low-risk groups (n = 52 per group) based on panel reactive antibody (PRA) percentage ≥ 35%, the existence of pre-Ktx donor-specific antibodies (DSA), or a previous transplant. IL-6 concentrations were measured before and at 3 months, 12 months, and 3 years after Ktx. Serum IL-6 levels tended to be higher in high-risk patients than in low-risk patients prior to Ktx and at 12 months after Ktx; however, the difference did not reach statistical significance (pre-Ktx, high-risk: 1.995 ± 2.79 pg/ml vs. low-risk: 1.43 ± 1.76 pg/ml, p = 0.051; 12 mo. high-risk: 1.16 ± 1.87 pg/ml vs. low-risk: 0.78 ± 1.13 pg/ml, p = 0.067). IL-6 levels were correlated with the types (no rejection, T cell mediated rejection (TCMR), antibody-mediated rejection (ABMR), or both) and time (<1 year vs. >1 year after Ktx) of rejection, as well as patient and graft survival. Patients with both TCMR and ABMR had significantly higher IL-6 levels at 3 months (14.1 ± 25.2 pg/ml) than patients with ABMR (3.4 ± 4.8 pg/ml, p = 0.017), with TCMR (1.7 ± 1.3 pg/ml, p < 0.001), and without rejection (1.7 ± 1.4 pg/ml, p < 0.001). Three years after Ktx, patients with AMBR had significantly higher IL-6 levels (5.30 ± 7.66 pg/ml) than patients with TCMR (1.81 ± 1.61 pg/ml, p = 0.009) and patients without rejection (1.19 ± 0.95 pg/ml; p = 0.001). Moreover, three years after Ktx IL-6 levels were significantly higher in patients with late rejections (3.5 ± 5.4 pg/ml) than those without rejections (1.2 ± 1.0 pg/ml) (p = 0.006). The risk of death-censored graft failure was significantly increased in patients with elevated IL-6 levels at 12 months (IL-6 level > 1.396 pg/ml, HR 4.61, p = 0.007) and 3 years (IL-6 level > 1.976 pg/ml, HR 6.75, p = 0.003), but elevated IL-6 levels were not associated with a higher risk of death. Overall, our study highlights IL-6 as a risk factor for allograft failure and confirms that IL-6 levels are higher in patients developing ABMR compared to TCMR alone or no rejection.

Impact of Early Rejection Treatment on Infection Development in Kidney Transplant Recipients: A Propensity Analysis

Introduction

The impact of renal allograft rejection treatment on infection development has not been formally defined in the literature.

Methods

We conducted a retrospective cohort study of 185 rejection (case) and 185 nonrejection (control) kidney transplant patients treated at our institution from 2014 to 2020 to understand the impact of rejection on infection development. Propensity scoring was used to match cohorts. We collected data for infections within 6 months of rejection for the cases and 18 months posttransplant for controls.

Results

In 370 patients, we identified 466 infections, 297 in the controls, and 169 in the cases. Urinary tract infections (38.9%) and cytomegalovirus viremia (13.7%) were most common. Cumulative incidence of infection between the case and controls was 2.17 (CI 1.54-3.05); p < 0.001. There was no difference in overall survival (HR 0.90, CI 0.49-1.66) or graft survival (HR 1.27, CI 0.74-2.20) between the groups. There was a significant difference in overall survival (HR 2.28, CI 1.14-4.55; p = 0.019) and graft survival (HR 1.98, CI 1.10-3.56; p = 0.023) when patients with infection were compared to those without.

Conclusions

As previously understood, rejection treatment is a risk factor for subsequent infection development. Our data have defined this relationship more clearly. This study is unique, however, in that we found that infections, but not rejection, negatively impacted both overall patient survival and allograft survival, likely due to our institution's robust post-rejection protocols. Clinicians should monitor patients closely for infections in the post-rejection period and have a low threshold to treat these infections while also restarting appropriate prophylaxis.

Impact of timing of rejection episode on cardiovascular events in living donor kidney transplantation: a multicenter retrospective study

BACKGROUND

Cardiovascular diseases are still highly prevalent after kidney transplantation. However, little is known about the impact of the timing of rejection episodes on cardiovascular disease. The study aimed to analyze the influence of the timing of rejection episodes on cardiovascular events in recipients of living donor kidney transplantation.

METHODS

We studied 572 living donor kidney transplant recipients from the Michinoku Renal Transplant Network (MRTN), which includes 6 centers in the Tohoku region of Japan. Fine-Gray proportional hazards regression analysis with time-dependent variables was used to assess the effect of rejection episode on cardiovascular events. Recipients were divided into three groups: those without rejection (non-rejection, 370 patients), rejection within 6 months after transplantation (early rejection, 99 patients), and rejection after 6 months (late rejection, 103 patients). The effect of timing on cardiovascular events was evaluated using Fine-Gray proportional hazards regression analysis.

RESULTS

During a median follow-up of 77 months, 70 patients experienced cardiovascular events. Rejection episodes were significantly associated with cardiovascular events (hazard ratio [HR]: 2.08, 95% confidence interval [CI]: 1.26-3.43, P = 0.004), along with age and dialysis vintage. The 5-year cumulative incidence of cardiovascular events was significantly higher in the late rejection group than in the early rejection group (15% vs. 3.3%, P = 0.021). However, no significant difference in 5-year cumulative cardiovascular event incidence was observed between the early rejection and non-rejection groups. Late rejection was significantly associated with cardiovascular events (HR: 2.40, 95% CI: 1.38-4.18, P = 0.002), whereas early rejection was not significantly correlated with cardiovascular event risk (HR: 1.18, P = 0.670).

CONCLUSIONS

Rejections occurring more than 6 months after transplantation is significantly associated with risk of cardiovascular events.

TRIAL REGISTRATION NUMBER

2019-099-1, date of registration; 3 Dec. 2019, retrospectively registered.

Artificial Urinary Biomarkers for Early Diagnosis of Acute Renal Allograft Rejection

Acute renal allograft rejection (ARAR) after kidney transplantation associated with reduced graft survival and eventual graft failure is poorly diagnosed in hospitals. Here, we report the development of Artificial bioMarker Probes (AMPros) for sensitive urinalysis of ARAR in murine models. AMPros spontaneously go to the kidneys after systemic administration, specifically react with the prodromal immune biomarkers to activate their near-infrared fluorescence signals to report cell-mediated rejection, and efficiently undergo renal excretion into urine. Thus, AMPros enable convenient optical urinalysis that detects ARAR prior to histological manifestation of rejection, which is also earlier than current diagnostic methods measuring proinflammatory cytokines and peripheral blood lymphocyte mRNAs. Due to the high kidney specificity, AMPros-based urinalysis discriminates allograft rejection against other non-alloimmune specific diseases, which is unattainable by measurement of serological biomarkers. Such a noninvasive and sensitive urine test holds great promise in continuous monitoring of renal allograft conditions at low resource settings for timely clinical interventions.

Pre-transplant immune profile defined by principal component analysis predicts acute rejection after kidney transplantation

Background

Acute rejection persists as a frequent complication after kidney transplantation. Defining an at-risk immune profile would allow better preventive approaches.

Methods

We performed unsupervised hierarchical clustering analysis on pre-transplant immunological phenotype in 1113 renal transplant recipients from the ORLY-EST cohort.

Results

We identified three immune profiles correlated with clinical phenotypes. A memory immune cluster was defined by memory CD4⁺T cell expansion and decreased naïve CD4⁺T cell. An activated immune cluster was characterized by an increase in CD8⁺T cells and a decreased CD4/CD8 ratio. A naïve immune cluster was mainly defined by increased naïve CD4⁺T cells. Patients from the memory immune profile tend to be older and to have diabetes whereas those from the activated immune profile were younger and more likely to have pre-transplant exposure to CMV. Patients from the activated immune profile were more prone to experience acute rejection than those from other clusters [(HR=1.69, 95%IC[1.05-2.70], p=0.030) and (HR=1.85; 95%IC[1.16-3.00], p=0.011). In the activated immune profile, those without previous exposure to CMV (24%) were at very high risk of acute rejection (27 vs 16%, HR=1.85; 95%IC[1.04-3.33], p=0.039).

Conclusion

Immune profile determination based on principal component analysis defines clinically different sub-groups and discriminate a population at high-risk of acute rejection.

Effects of periodontal pathogen-induced intestinal dysbiosis on transplant immunity in an allogenic skin graft model

Periodontal disease can induce dysbiosis, a compositional and functional alteration in the microbiota. Dysbiosis induced by periodontal disease is known to cause systemic inflammation and may affect transplant immunity. Here, we examined the effects of periodontal disease-related intestinal dysbiosis on transplant immunity using a mouse model of allogenic skin graft in which the mice were orally administered the periodontal pathogen Porphyromonas gingivalis (Pg). For 6 weeks, the Pg group orally received Pg while the control group orally received phosphate-buffered saline solution. After that, both groups received allogenic skin grafts. 16 s rRNA analysis of feces revealed that oral administration of Pg significantly increased three short chain fatty acids (SCFAs) producing genera. SCFA (acetate and propionate) levels were significantly higher in the Pg group (p = 0.040 and p = 0.005). The ratio of regulatory T cells, which are positively correlated with SCFAs, to total CD4+ T cells in the peripheral blood and spleen was significantly greater (p = 0.002 and p < 0.001) in the Pg group by flowcytometry. Finally, oral administration of Pg significantly prolonged skin graft survival (p < 0.001) and reduced pathological inflammation in transplanted skin grafts. In conclusion, periodontal pathogen-induced intestinal dysbiosis may affect transplant immunity through increased levels of SCFAs and regulatory T cells. (198 words).

Toward generalizing the use of artificial intelligence in nephrology and kidney transplantation

With its robust ability to integrate and learn from large sets of clinical data, artificial intelligence (AI) can now play a role in diagnosis, clinical decision making, and personalized medicine. It is probably the natural progression of traditional statistical techniques. Currently, there are many unmet needs in nephrology and, more particularly, in the kidney transplantation (KT) field. The complexity and increase in the amount of data, and the multitude of nephrology registries worldwide have enabled the explosive use of AI within the field. Nephrologists in many countries are already at the center of experiments and advances in this cutting-edge technology and our aim is to generalize the use of AI among nephrologists worldwide. In this paper, we provide an overview of AI from a medical perspective. We cover the core concepts of AI relevant to the practicing nephrologist in a consistent and simple way to help them get started, and we discuss the technical challenges. Finally, we focus on the KT field: the unmet needs and the potential role that AI can play to fill these gaps, then we summarize the published KT-related studies, including predictive factors used in each study, which will allow researchers to quickly focus on the most relevant issues.

Metabolomic Profiling of Plasma, Urine, and Saliva of Kidney Transplantation Recipients

Kidney biopsy is commonly used to diagnose kidney transplant dysfunction after transplantation. Therefore, the development of minimally invasive and quantitative methods to evaluate kidney function in transplant recipients is necessary. Here, we used capillary electrophoresis-mass spectrometry to analyze the biofluids collected from transplant recipients with impaired (Group I, n = 31) and stable (Group S, n = 19) kidney function and from donors (Group D, n = 9). Metabolomics analyses identified and quantified 97 metabolites in plasma, 133 metabolites in urine, and 108 metabolites in saliva. Multivariate analyses revealed apparent differences in the metabolomic profiles of the three groups. In plasma samples, arginine biosynthesis and purine metabolism between the I and S Groups differed. In addition, considerable differences in metabolomic profiles were observed between samples collected from participants with T cell-mediated rejection (TCR), antibody-mediated rejection, and other kidney disorders (KD). The metabolomic profiles in the three types of biofluids showed different patterns between TCR and KD, wherein 3-indoxyl sulfate showed a significant increase in TCR consistently in both plasma and urine samples. These results suggest that each biofluid has different metabolite features to evaluate kidney function after transplantation and that 3-indoxyl sulfate could predict acute rejection.

Long-term outcomes and prognostic factors in kidney transplant recipients in Jakarta, Indonesia: a cohort study

OBJECTIVES

To determine the long-term survival rates and prognostic factors in kidney transplant (KT) recipients in Jakarta, Indonesia.

DESIGN

Retrospective cohort study.

SETTING

A KT centre in Jakarta.

PARTICIPANTS

We enrolled 754 consecutive adult recipients who underwent KT between 2010 and 2020.

MAIN OUTCOME MEASURES

Rates of 10-year patient, all-cause and death-censored graft survival and their prognostic factors in KT recipients.

RESULTS

The 10-year patient survival, all-cause survival and death-censored graft survival rates of KT recipients were 74%, 68% and 81%, respectively. The prognostic factors for poor patient survival were a pretransplant dialysis duration>24 months (HR 1.64, 95% CI, 1.08 to 2.49; p=0.02), cardiovascular disease (HR 1.59, 95% CI, 1.11 to 2.31; p=0.01), delayed graft function (DGF) (HR 4.94, 95% CI, 2.76 to 8.82; p<0.001), post-transplant infection (HR 2.63, 95% CI, 1.56 to 4.43; p<0.001) and acute rejection (HR 2.49, 95% CI, 1.20 to 5.15; p=0.01). All-cause graft survival was prognosticated by a pretransplant dialysis duration>24 months (HR 1.74, 95% CI, 1.15 to 2.47; p=0.007), cardiovascular disease (HR 1.65, 95% CI, 1.18 to 2.33; p=0.004), DGF (HR 5.39, 95% CI, 3.13 to 9.28; p<0.001), post-transplant infection (HR 2.46, 95% CI, 1.05 to 4.02; p<0.001) and acute rejection (HR 4.18, 95% CI, 2.23 to 7.84; p<0.001). Factors associated with poor death-censored graft survival were a pretransplant dialysis duration >24 months (HR 2.19, 95% CI, 1.32 to 3.63; p=0.002), cardiovascular disease (HR 1.65, 95% CI, 1.02 to 2.68; p=0.04) and acute rejection (HR 5.52, 95% CI, 2.80 to 10.83; p<0.001).

CONCLUSIONS

The survival rates of KT recipients are prognosticated by pretransplant dialysis duration, cardiovascular disease, DGF, post-transplant infection and acute rejection. Stricter eligibility criteria for recipients, more sensitive cross-match testing methods and better infection management strategies may be beneficial for improving the survival rates.

Histological diagnosis from kidney transplant biopsy can contribute to prediction of graft survival

Aim

The primary aim of this study was to in depth examine if the histological findings in a transplanted kidney biopsy can predict the prognosis for the graft and the patient. The secondary aim was to extend knowledge of the impact of time elapsed on biopsy findings.

Methods

Data from 1462 patients were merged from a kidney transplantation registry and a biopsy registry during 1 January 2007 and 30 September 2017. Kaplan–Meier analysis and multivariate Cox‐regression analysis were performed and hazard ratios (HR) with 95% confidence intervals (CI) were presented.

Results

Compared to normal biopsy findings, graft survival after biopsy (gsaBiopsy) was shorter for patients with glomerular diseases (HR 8.2, CI:3.2–21.1), rejections (HR 4.2, CI:1.7–10.3), chronic changes including IFTA (HR 3.2, CI:1.3–8.0), acute tubular injuries (HR 3.0, CI:1.2–7.8), and borderline changes (HR 2.9, CI:1.1–7.6). Sub‐analysis of rejections showed shorter gsaBiopsy for chronic TCMR (HR 4.7, CI:1.9–11.3), active ABMR (HR 3.6, CI:1.7–7.7) and chronic ABMR (HR 3.5, CI:2.0–6.0). Patients with TCMR Banff grade II (HR 0.35, CI:0.20–0.63) and grade I (HR 0.52, CI:0.29–0.93) had a better gsaBiopsy compared to all other types of rejections.

Conclusion

Shorter gsaBiopsy was noted in kidneys with glomerular diseases, rejections, acute tubular injuries and borderline changes. TCMR Banff rejections grade I and II were associated with a better prognosis.

This Swedish single centre study showed that the impact on allograft survival is dependent on the nature of the biopsy findings, with histological findings of glomerular disease, severe rejections and chronic changes being associated with more rapid allograft loss.

The effect of periodontitis on recipient outcomes after kidney transplantation

Background: Recent several reports have demonstrated that periodontitis is prevalent and adversely affects the survival in patients with chronic kidney disease (CKD) or end-stage kidney disease. However, its impact on transplant outcomes remains uncertain.Methods: This retrospective cohort study included 136 and 167 patients, respectively, who underwent living donor kidney transplantation (KT) at Seoul National University Hospital from July 2012 to August 2016 and Korea University Hospital from April 2008 to October 2018. We divided patients into three groups according to stages of periodontitis based on a new classification system. Results: Patients with severe periodontitis were older, had a higher prevalence of diabetes, a higher body mass index and C-reactive protein level, a lower cardiac output, and were more likely to be smokers, indicating its association with chronic systemic inflammation. After KT, stage IV periodontitis was independently associated with a lower incidence of acute T cell-mediated rejection, suggesting the possible effect of periodontitis on immune function. However, 1-year and 3-year estimated glomerular filtration rates were not different. Among the KT recipients followed up more than 3 years, new-onset cardiovascular disease occurred in nine patients, and coronary artery disease occurred more frequently in patients with stage IV periodontitis. However, diabetes was the independent predictor of new-onset coronary artery disease in multivariate logistic regression analysis.Conclusion: Our findings showed that periodontitis might be an important player in determining posttransplant outcomes in recipients. Further interventional trials to test whether treating periodontitis could modify transplant outcome are needed.

Survival Rate of Renal Transplant and Factors Affecting Renal Transplant Failure

OBJECTIVES

The most important complication in kidney transplant is acute/chronic rejection. In this study, we investigated the factors affecting kidney rejection and transplant survival.

MATERIALS AND METHODS

In this survival analysis study, 352 patients (mean follow-up of 12.9 ± 4.4 years) who underwent renal biopsy due to increased creatinine level from 2012 to 2016 were identified by glomerular filtration rate level and rejection. Probable factors affecting renal function and survival rate after transplant rejection were assessed. P < .05 was considered as significant.

RESULTS

Among our study patients, 40.9% developed early and 59.1% developed late acute kidney injury. Graft survival rates at 1 and 5 years were 98.9% and 68.5%, respectively, which was significant when rejection type was considered (P = .002). In addition, patient survival rates at 1 and 5 years were 99.7% and 98.6%, respectively. Graft survival at 5 years was significantly lower among older subjects, those with diabetes, those who received deceased donor organs, and those with late acute kidney injury (P < .002). Patient survival was significantly higher among young patients, those with systemic lupus erythematosus, those who received living donor organs, and those without cytomegalovirus infection (P < .003).

CONCLUSIONS

We observed that recipient age, type of donor, underlying disease, infection, and late acute kidney injury had great negative impacts on renal dysfunction and survival. In our center, because of the large number of kidney transplants from deceased donors, the necessity of antithymocyte globulin induction therapy was considered, since this study showed that patients who received rabbit antithymocyte globulin induction had better outcomes.

One-Year Outcomes with Use of Anti-T-Lymphocyte Globulin in Patients Undergoing Kidney Transplantation: Results from a Prospective, Multicentric, Observational Study from India

INTRODUCTION

Large-scale Indian data on the use of anti-T-lymphocyte globulin (ATLG) (Grafalon^®) as induction therapy in kidney transplantation (KT) patients is lacking. The aim of this study was to determine the 1-year patient and graft survival outcomes with the use of ATLG as induction regimen in KT.

METHODS

In a prospective, multicentric, observational study, adult patients who underwent ABO-compatible KT and had received ATLG as a part of induction were included in the study. The primary outcome measure was overall survival and death-censored graft survival at 12 months. The primary safety outcome was assessed by development of infectious complications and graft rejection.

RESULTS

In total, 359 patients were included in this study. The mean age was 42.77 ± 12.30 years and 83% were male. The average ATLG dose per patient was 6.2 ± 2.2 mg/kg whereas average cumulative dose per patient was 389.6 ± 149.8 mg. The rate of graft dysfunction was 13.4% of patients and 6.7% had biopsy-proven acute rejection (BPAR). There were a total of 12 (3.3%) deaths and one graft loss. Overall survival and death-censored graft survival at 12 months were 96.65% and 99.44%, respectively. The rate of infections was 13.6% with urinary tract infections being most common.

CONCLUSION

ATLG at an average dose of 6 mg/kg is an effective and safe induction regimen immunosuppressant for ABO-compatible KT with favourable impact on survival and graft function in Indian patients.

Oral health of patients suffering from end-stage solid organ insufficiency prior to solid organ re-transplantation: a retrospective case series study

Background

The oral health of organ transplanted patients before organ re-transplantation is largely unknown. This retrospective clinical study evaluates the necessity for intraoral surgical intervention and/or conservative treatment in candidates awaiting organ re-transplantation, both for graft failure and for reasons of another upcoming solid organ transplantation (renal or non-renal).

Methods

From January 2015 to March 2020 n = 19 transplant recipients in evaluation on the waiting list for solid organ re-transplantation could be included in the retrospective case series study. Using clinical and radiological examinations, necessity for oral surgical or conservative dental treatment was evaluated. On the basis of anamnesis data, current kidney function, renal replacement treatment (RRT), and medication, a risk profile for several patient subgroups was created.

Results

The clinical and radiological examinations showed a conservative and/or surgical treatment need in n = 13 cases (68.42%). In n = 7 cases (36.84%) surgical intervention was recommended due to residual root remnants (n = 5), unclear mucosal changes (n = 1), and periimplantitis (n = 1). In n = 16 recipients (84.2%) RRT (n = 15 hemodialysis; n = 1 peritoneal dialysis) had been performed. N = 14 recipients (73.68%) received immunosuppressants. In n = 1 patient (5.3%) displayed intraoral and n = 4 patients (21.1%) extraoral neoplasms due to drug-induced immunosuppression.

Conclusions

Solid organ transplant recipients with renal failure present a complex treatment profile due to a double burden of uremia plus immunosuppressants. In cases of surgical treatment need a hospitalized setting is recommended, where potentially necessary follow-up care and close cooperation with disciplines of internal medicine is possible in order to avoid surgical and/or internal complications.

Late first acute rejection in pediatric kidney transplantation: A North American Pediatric Renal Trials and Collaborative Studies special study

Rates of early AR in pediatric kidney transplantation have declined in every era but the most recent NAPRTCS cohort has shown an increase in late first AR rates. We hypothesized this was due to an increased proportion of deceased donor utilization and early steroid taper utilization. Using the NAPRTCS database, we compared the most recent three cohorts of patients transplanted between 2002-2006, 2007-2011, and 2012-2017. To determine variables that predict late first AR, we used two multivariable models: a standard Cox regression model and LASSO model. From the LASSO model, deceased donor source (P = .002), higher recipient age (P = .019), black race (P = .010), and transplant cohort 2012-17 (P = .014) were all significant predictors of more late first AR. On standard Cox regression analysis, those same variables, minus donor source, were significant, in addition to mycophenolates usage (P = .007) and lower eGFR at 12 months (P = .02). The most recent 2012-2017 cohort remains an independently significant risk factor for late first AR, suggesting unmeasured variables. Further research is needed to determine whether these higher late first AR rates will impact long-term graft survival in the most recent cohort.

Nationwide Glaucoma incidence in end stage renal disease patients and kidney transplant recipients

Glaucoma shares common risk factors with chronic kidney disease (CKD) but previous cross-sectional studies have demonstrated discrepancies in the risk of glaucoma in CKD patients. This study enrolled kidney transplantation recipients (KTRs) (n = 10,955), end stage renal disease (ESRD) patients (n = 10,955) and healthy controls (n = 10,955) from National Health Insurance Service database of the Republic of Korea. A Cox proportional hazard regression model was used to calculate the hazard ratios (HR) for primary open-angle glaucoma (POAG) and primary angle-closure glaucoma (PACG) incidences. The incidence of POAG was higher in ESRD patients (3.36/1,000 person-years, P < 0.0001) and KTRs (3.22 /1,000 person-years, P < 0.0001), than in healthy controls (1.20/1,000 person-years). However, POAG risk showed no significant increase in either ESRD patients (P = 0.07) or KTRs (P = 0.08) when adjusted for the confounding factors. The incidence of PACG was significantly higher in ESRD patients (0.41/1,000 person-years) than in healthy controls (0.14/1,000 person-years, P = 0.008). The PACG incidence was significantly lower in KTRs than in ESRD patients (HR = 0.35, P = 0.015). In conclusion, this nationwide cohort study demonstrated that kidney transplantation can reduce the risk of PACG but not POAG in ESRD patients.

Late-onset allograft rejection, cytomegalovirus infection, and renal allograft loss: Is anti-CMV prophylaxis required following late-onset allograft rejection?

Renal transplant recipients remain at risk of delayed-onset cytomegalovirus (CMV) infection occurring beyond a complete course of prophylaxis. In this retrospective cohort, all 278 patients who received renal allografts from deceased donors from 2014 to 2016 were followed until September 1, 2019. We determined the effect of early-vs late-onset acute rejection (EAR vs LAR [ie, occurring beyond 12 months after transplantation]) on CMV infection and subsequently long-term allograft outcome. Median (IQR) duration of follow-up was 1186.0 (904.7-1531.2) days. Seventy patients including 49 patients with EAR and 21 with LAR received augmented immunosuppression. In the same interval, 40 patients developed CMV infection (36 patients beyond 90 days after transplantation [90%]). In logistic regression analysis, D+/R- CMV serostatus (OR: 5.5, 95% CI: 2.5-12.2) and LAR (OR: 7.9, 95% CI: 2.8-22.2) significantly increased the risk of CMV infection. In Cox proportional hazard model, delayed-onset CMV infection (HR: 2.51, 95% CI: 1.08-5.86) and LAR (HR: 5.46, 95% CI: 2.26-13.14) significantly increased the risk of allograft loss. Patients with LAR are at risk of late-onset CMV infection. Post-LAR, targeted prophylaxis may reduce the risk of CMV infection and subsequently allograft loss. Further studies are required to demonstrate the effect of targeted prophylaxis following LAR.

Outcomes of first versus third kidney transplantations: propensity score matching and paired subgroup analysis-a single-centre experience

Background

In the Eurotransplant, 12.6% of kidney transplantations are a repeat procedure. Third transplants are significantly more complex than first and second ones. We compared the results of first (PRT) versus third (TRT) transplantations.

Methods

Between 2011 and 2016, we performed 779 deceased donor adult kidney transplantations, 14.2% out of them were second, 2.6% (20) third, and 0.3% fourth. We compared the pre-, intra-, and postoperative data, kidney function, and survival rate.

Results

Recipients of TRT were younger (53.4 vs. 47.3 p = 0.02). HCV infection rate (20%, p = 0.00) is ten times higher. The operation time is longer (132 vs. 152 min, p = 0.02), and delayed graft function is much more frequent (22.4% vs. 60%, p = 0.00). Induction therapy was given to every TRT (7.9% vs.100%), but as a result, the rejection rate was the same (~ 15%). Hospital stay is a week longer. Patient’s survival at 1, 3, and 5 years for PRT is 96.4%, 93.9%, and 91.2% and for TRT is 90%, 85%, and 78.4%, respectively (p = 0.023). TRT’s odds ratio of fatal outcome is 4.35 (1.5–12.5). Graft survival at 1, 3, and 5 years for PRT is 93.1%, 91.4%, and 90.3% and for TRT is 75%, 75%, and 75%, respectively (p = 0.020). TRT’s odds ratio of graft loss is 3.14 (1.1–8.9). Of PRT 85.76%, out of PRT 85.76%, while out of TRT 60% live with a functioning graft, p=0.00149.

Conclusion

In a third transplant, both graft and patient survival are significantly inferior to primer ones. Careful selection is required to minimize the patient risk and graft loss.

Deceased vs. living donor kidney transplantation in prediction of acute renal allograft rejection using Tc-99m DTPA renal scan

OBJECTIVES

No data are available regarding different prognostic values of Tc-99m diethylenetriaminepentaacetic acid (DTPA) renal scan in kidney transplantation (KT) recipients according to two distinct donor types: deceased donor KT (DDKT) and living donor KT (LDKT). We evaluated whether the interpretation of Tc-99m DTPA renal scan should be different by the donor type in predicting acute renal allograft rejection (AR).

METHODS

One hundred and seven KT recipients (61 DDKT and 46 LDKT) were included in this study. Tc-99m DTPA renal scan was performed 1 week after KT. AR was defined as pathological evidence of renal allograft rejection during the first 6 months of KT. Clinical factors and Tc-99m DTPA renal scan findings were compared between patients with and without AR. To further analyze the effect of the donor type, they were again compared within DDKT and LDKT recipients, respectively.

RESULTS

AR occurred in 15 patients (7 DDKT and 8 LDKT recipients). Among all patients, time to peak uptake (TTP) of the cortex (TTP_CX) measured by Tc-99m DTPA renal scan was independently predictive of AR. Moreover, TTP_KD (TTP of the whole transplanted kidney) and TTP_CX were the only predictors of AR among DDKT recipients. The most accurate predictors were TTP_CX and kidney area on renal scan for DDKT and LDKT, respectively. However, these parameters could not predict AR for the opposite donor type.

CONCLUSIONS

AR could be effectively predicted by Tc-99m DTPA renal scan obtained at 1 week post-KT. Different parameters should be applied according to the donor type in the prediction of AR.

Time-Varying Covariates and Risk Factors for Graft Loss in Kidney Transplantation

OBJECTIVES

The present study was designed to evaluate the factors involved in long-term graft survival in recipients of kidney transplantation.

MATERIALS AND METHODS

We reviewed 755 Iranian adult recipients who underwent kidney transplantation at Shahid Labbafinejad Medical Center in Tehran, Iran. Patients were followed for 5 years after transplantation. The primary outcome was the time between transplantation and graft loss. Using Cox regression, we studied the effect of time-independent variables (recipients' age and sex, donors' age, and type of donor), time-dependent covariates (body mass index [BMI], systolic blood pressure, diastolic blood pressure, high-density lipoprotein (HDL) and low-density lipoprotein (LDL) cholesterol levels, proteinuria and serum creatinine level), and immunosuppressive drugs on graft loss 60 months after transplantation. The results are presented as the hazard ratio (HR) with 95% confidence intervals.

RESULTS

Result from Cox proportional hazards model showed that the HR of graft loss was 1.62 (95% CI: 1.03-2.54) in cadaveric donor compared with living donor kidney recipients. The HR of graft loss for recipient age was 1.02 (95% CI: 1.002-1.030). Moreover, according to obtained results, the risk of losing functional transplant increased for each mg/dL rise in serum creatinine at least 9% and at most 40%. Our results also showed that 1 unit increase of BMI has at least a 2% and at most a 15% decremented effect on the hazard ratio of graft loss.

CONCLUSIONS

Having lower levels of creatinine and receiving a kidney from a younger living donor were associated with a decreased risk of graft loss. Graft loss is more likely to occur in patients with lower BMI.

Risk factors for death in kidney transplant patients: analysis from a large protocol biopsy registry

BACKGROUND

Identification and quantification of the relevant factors for death can improve patients' individual risk assessment and decision-making. We used a well-documented patient cohort (n = 892) in a renal transplant programme with protocol biopsies to establish multivariable Cox models for risk assessment at 3 and 12 months post-transplantation.

METHODS

Patients transplanted between 2000 and 2007 were observed up to 11 years (total observation 5227 patient-years; median 5.9 years). Loss to follow-up was negligible (n = 15). A total of 2251 protocol biopsies and 1214 biopsies for cause were performed. All rejections and clinical borderline rejections in protocol biopsies were treated.

RESULTS

Overall 10-year patient survival was 78%, with inferior survival of patients with graft loss and superior survival of patients with living-donor transplantation. Eight factors were common in the models at 3 and 12 months, including age, pre-transplant heart failure and a score of cardiovascular disease and type 2 diabetes, post-transplant urinary tract infection, treatment of rejection, new-onset heart failure, coronary events and malignancies. Additional variables of the model at 3 months included deceased donor transplantation, transplant lymphocele, BK virus nephropathy and severe infections. Graft function and graft loss were significant factors of the model at 12 months. Internal validation and validation with a separate cohort of patients (n = 349) demonstrated good discrimination of the models.

CONCLUSIONS

The identified factors indicate the important areas that need special attention in the pre- and post-transplant care of renal transplant patients. On the basis of these models, we provide nomograms as a tool to weigh individual risks that may contribute to decreased survival.

Observer variability in the assessment of renal 18F-FDG uptake in kidney transplant recipients

¹⁸F-FDG PET/CT imaging may help non-invasively disprove the diagnosis of acute kidney allograft rejection (AR) in kidney transplant recipients (KTR). The present study aims at evaluating the repeatability and reproducibility of the quantification of renal ¹⁸F-FDG uptake in KTR. We prospectively performed ¹⁸F-FDG PET/CT in 95 adult KTR who underwent surveillance transplant biopsy between 3 to 6 months post transplantation. Images were obtained 180 minutes after injecting 3 MBq ¹⁸F-FDG per kg body weight. Mean standard uptake value (SUV_mean) of kidney cortex was independently measured by 2 experienced observers in 4 volumes of interest (VOI) distributed in the upper (n = 2) and lower (n = 2) poles. The first observer repeated SUV assessment in the uppermost VOI, blinded to the initial results. Intra-class correlation coefficients (ICC) and Bland-Altman plots were calculated. An ICC of 0.96 with 95%CI of [0.94; 0.97] was calculated for the intra-observer measurements. The ICC for inter-observer reproducibility for each VOI was 0.87 [0.81–0.91], 0.87 [0.81–0.91], 0.85 [0.78–0.89] and 0.83 [0.76–0.88] for the upper to the lower renal poles, respectively. The repeatability and reproducibility of the quantification of kidney allograft ¹⁸F-FDG uptake are both consistent, which makes it transferrable to the clinical routine.

Microbiota in organ transplantation: An immunological and therapeutic conundrum?

The gastrointestinal (GI) tract microbiota is an environmental factor that regulates host immunity in allo-transplantation (allo-Tx). It is required for the development of resistance against pathogens and the stabilization of mucosa-associated lymphoid tissue. The gut-microbiota axis may also precipitate allograft rejection by producing metabolites that activate host cell-mediated and humoral immunity. Here, we discuss new insights into microbial immunomodulation, highlighting ongoing attempts to affect commensal colonization in an attempt to ameliorate allograft rejection cascade. Recent progress on the use of antibiotics to modulate GI microbiota diversity and innate-adaptive immune interface are discussed. Our focus on the microbiota's influence of endoplasmic reticulum (ER) stress and autophagy signaling through hepatic EP4/CHOP/LC3B platforms reveals a novel molecular pathway and potential biomarkers determining the progression of allo-Tx damage. Understanding and harnessing the potential of microbiome/bacteriophage therapies may offer safe and effective means for personalized treatment to reduce risks of infections and immunosuppression in allo-Tx.

A retrospective study of the relationship between postoperative urine output and one year transplanted kidney function

BACKGROUND

Kidney transplantation (KT) is the most obvious method of treating a patient with end-stage renal disease. In the early stages of KT, urine production is considered a marker of successful reperfusion of the kidney after anastomosis. However, there is no clear conclusion about the relationship between initial urine output after KT and 1-year renal function. Thus, we investigated the factors that affect 1-year kidney function after KT, including urine output.

METHODS

This retrospective study investigated the relationship between urine output in the 3 days after KT and transplanted kidney prognosis after 1-year. In total, 291 patients (129 living-donor and 162 deceased-donor transplant recipients) were analyzed; 24-h urine volume per body weight (in kilograms) was measured for 3 days postoperatively. The estimated glomerular filtration rate (eGFR), determined by the Modification of Diet in Renal Disease algorithm, was used as an index of renal function. Patients were grouped according to eGFR at 1-year after KT: a good residual function group, eGFR ≥60, and a poor residual function group, eGFR < 60.

RESULT

Recipients' factors affecting 1-year eGFR include height (P = 0.03), weight (P = 0.00), and body mass index (P = 0.00). Donor factors affecting 1-year eGFR include age (P = 0.00) and number of human leukocyte antigen (HLA) mismatches (P = 0.00). The urine output for 3 days after KT (postoperative day 1; 2 and 3) was associated with 1-year eGFR in deceased-donor (P = 0.00; P = 0.00 and P = 0.01). And, postoperative urine output was associated with the occurrence of delayed graft function (area under curve (AUC) = 0.913; AUC = 0.984 and AUC = 0.944).

CONCLUSION

Although postoperative urine output alone is not enough to predict 1-year GFR, the incidence of delayed graft function can be predicted. Also, the appropriate urine output after KT may differ depending on the type of the transplanted kidney.

TRIAL REGISTRATION

Clinical Research Information Service of the Korea National Institute of Health in the Republic of Korea (KCT0003571).

Risk Factors for 1-Year Graft Loss After Kidney Transplantation: Systematic Review and Meta-Analysis

BACKGROUND AND OBJECTIVES

With expansion of the pool of kidney grafts, through the use of higher-risk donors, and increased attention to donor management strategies, the 1-year graft survival rate is subject to change. It is, therefore, useful to elucidate 1-year graft survival rates by dissecting the characteristics of the low-risk and high-risk kidney transplant cases. The objective of our study was to evaluate factors purported to influence the risk of 1-year graft loss in kidney transplant recipients.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We searched bibliographic databases from 2000 to 2017 and included observational studies that measured the association between donor, recipient, the transplant operation, or early postoperative complications, and 1-year death-censored graft loss.

RESULTS

We identified 35 eligible primary studies, with 20 risk factors amenable to meta-analysis. Six factors were associated with graft loss, with moderate to high degree of certainty: donor age (hazard ratio [HR], 1.11 per 10-year increase; 95% confidence interval [95% CI], 1.04 to 1.18), extended criteria donors (HR, 1.35; 95% CI, 1.28 to 1.42), deceased donors (HR, 1.54; 95% CI, 1.32 to 1.82), number of HLA mismatches (HR, 1.08 per one mismatch increase; 95% CI, 1.07 to 1.09), recipient age (HR, 1.17 per 10-year increase; 95% CI, 1.09 to 1.25), and delayed graft function (HR, 1.89; 95% CI, 1.46 to 2.47) as risk factors for 1-year graft loss. Pooled analyses also excluded, with a high degree of certainty, any associations of cold ischemia time, recipient race, pretransplant body mass index, diabetes, and hypertension with 1-year graft loss.

CONCLUSIONS

Recipient age, donor age, standard versus extended criteria donor, living versus deceased donor, HLA mismatch, and delayed graft function all predicted 1-year graft survival. The effect of each risk factor is small.

Clinical Significance of Mycophenolate Mofetil Withdrawal in Kidney Transplant Recipients

INTRODUCTION

The most effective immunosuppressant protocol in kidney transplantation (KT) is the combination of a calcineurin inhibitor, steroid, and mycophenolate mofetil (MMF) until now. However, MMF withdrawal (MW) is performed for many reasons, and the clinical course of the KT recipients after MW is not clearly known. The purpose of this study was to investigate the clinical outcomes of KT after MW.

MATERIALS AND METHODS

We retrospectively analyzed the medical records of 626 KT recipients between 2000 and 2016. We evaluated the incidence of biopsy-proven acute rejection (BPAR), graft and patient survival rates, and risk factors related with graft failure.

RESULTS

The proportion of MW was 33.2% (208 of 626 patients). The median time between KT and MW was 6.4 months (range, 3.2-32.1 months). The common causes of MW were infection (70.7%), hematologic abnormalities (9.1%), and gastrointestinal trouble (7.7%). The incidence of BPAR was significantly higher in the MW group compared with the MMF continuation group (27.4% vs 8.9%, respectively, P < .001). Death-censored graft survival and patient survival rates were significantly lower in the MW group compared with the MMF continuation group (P < .001; P < .001, respectively). In the multivariate analysis, BPAR after MW was an independent risk factor for graft failure (hazard ratio 6.058, 95% confidence interval, 3.172-11.569, P < .001).

CONCLUSIONS

The incidence of rejection, graft failure, and patient mortality in KT were high after MW. Therefore, MW should be considered carefully.

Modeling Long-Term Graft Survival With Time-Varying Covariate Effects: An Application to a Single Kidney Transplant Centre in Johannesburg, South Africa

Objectives: Patients' characteristics that could influence graft survival may also exhibit non-constant effects over time; therefore, violating the important assumption of the Cox proportional hazard (PH) model. We describe the effects of covariates on the hazard of graft failure in the presence of long follow-ups.

Study Design and Settings: We studied 915 adult patients that received kidney transplant between 1984 and 2000, using Cox PH, a variation of the Aalen additive hazard and Accelerated failure time (AFT) models. Selection of important predictors was based on the purposeful method of variable selection.

Results: Out of 915 patients under study, 43% had graft failure by the end of the study. The graft survival rate is 81, 66, and 50% at 1, 5, and 10 years, respectively. Our models indicate that donor type, recipient age, donor-recipient gender match, delayed graft function, diabetes and recipient ethnicity are significant predictors of graft survival. However, only the recipient age and donor-recipient gender match exhibit constant effects in the models.

Conclusion: Conclusion made about predictors of graft survival in the Cox PH model without adequate assessment of the model fit could over-estimate significant effects. The additive hazard and AFT models offer more flexibility in understanding covariates with non-constant effects on graft survival. Our results suggest that the period of follow-up in this study is long to support the proportionality assumption. Modeling graft survival at different time points may restrain the possibility of important covariates showing time-variant effects in the Cox PH model.

Differences in Pathologic Features and Graft Outcomes of Rejection on Kidney Transplant

BACKGROUND

Rejection is still a barrier to long-term allograft survival, but there are not many reports of clinical outcomes according to rejection types. The purpose of this study was to investigate differences in pathologic features and graft outcomes of rejection on kidney transplant (KT).

MATERIALS AND METHODS

We retrospectively analyzed 139 kidney transplant recipients diagnosed to rejection by allograft biopsy results between 2006 and 2018. We divided kidney transplant recipients into 3 groups as follows: T cell-mediated rejection (TCMR), antibody-mediated rejection, and mixed rejection. We investigated clinical characteristics, pathologic findings, death-censored graft survival rates, and patient survival rates among the 3 groups.

RESULTS

Mean follow-up duration was 113.5 (SD, 80.6) months. The mixed rejection group was the youngest significantly. There were no significant differences of the proportion of sex, KT type, KT number, number of HLA mismatches, induction immunosuppressant, and maintenance immunosuppressant among the 3 groups. In pathologic findings, microvascular inflammation and C4d were significantly different among the 3 groups. Death-censored graft survival of mixed rejection was the least. In multivariate analysis, recipient age, TCMR, and positive C4d were the risk factors associated with graft failure. However, patient survival rates showed no significant differences among the 3 groups.

CONCLUSIONS

Our study showed that mixed rejection had poor prognosis in comparison with TCMR and antibody-mediated rejection groups, and TCMR and positive C4d were the most important risk factors for graft survival. Therefore, constant monitoring through allograft biopsy and early treatment for rejection are very important in post-transplant clinical outcomes.

Emergency Department Visits After Kidney, Liver, and Heart Transplantation in a Hospital of a University in Turkey: A Retrospective Study

OBJECTIVES

In our country, there are few publications evaluating emergency department visits among kidney, liver, and heart transplant recipients. Here, we examined emergency department visits of transplant recipients after initial hospital discharge following organ transplant performed in a medical faculty hospital in Ankara, Turkey.

MATERIALS AND METHODS

We retrospectively analyzed hospital records of 1144 transplant recipients (700 kidney, 332 liver, and 112 heart) who underwent living-donor and deceased-donor organ transplant procedures in a university hospital between 2007 and 2017 and were admitted to the emergency department during the same period.

RESULTS

The study population (1144 organ transplants) consisted of kidney (61.2%), liver (29.0%), and heart (9.8%) transplant recipients. Among them, 67.9% of kidney transplant recipients and 62.0% of liver transplant recipients were male, whereas 65.2% of heart transplant recipients were female. Average ages were 32.8 ± 15.5, 24.26 ± 21.6, and 29.9 ± 18.7 years, respectively. Among all groups, 41.4% visited the emergency department within 2 years after transplant. Median time to emergency department visit for kidney, liver, and heart transplant recipients was 4.7 months, 3.5 months, and 11.5 months, respectively. Emergency department admissions were due to complaints of abdominal/pelvic pain, fever, nausea/vomiting, hypertension, and nonspecific chest pain. Among all groups, the main diagnoses were most commonly classified by fluid and electrolyte disorders, abnormal results of renal function, urinary tract infections, and acute respiratory infections. One-third of patients were hospitalized.

CONCLUSIONS

Nearly one-quarter of kidney transplant recipients, one-fifth of liver transplant recipients, and one-tenth of heart transplant recipients visited the emergency department within 30 days of transplantation. Considering that one-third were rehospitalized, the recipients could be targeted for better transitions of care and for earlier or more frequent outpatient follow-up and also be informed about what symptoms are not normal and in which situations they should seek emergency care.

Tacrolimus trough and dose intra-patient variability and CYP3A5 genotype: Effects on acute rejection and graft failure in European American and African American kidney transplant recipients

BACKGROUND

Suboptimal immunosuppression after kidney transplantation contributes to toxicity and loss of efficacy. Little is known regarding the impact of intra-patient variability of tacrolimus (TAC) doses and troughs in the early post-transplant period or the influence of genetic variants on variability.

METHODS

Coefficients of variation (CV) of TAC troughs and doses of 1226 European American (EA) and 246 African American (AA) adult recipients enrolled in DeKAF Genomics were compared for association with acute rejection and graft failure. Additionally, the influence of recipients' number of CYP3A5 loss-of-function alleles was assessed.

RESULTS

Acute rejection was associated with greater CV of dose in AA (P < 0.001) and EA recipients (P = 0.012). Graft failure was associated with a greater CV of dose (P = 0.022) and trough (P < 0.001) in AA, and higher CV of trough (P = 0.024) in EA recipients. In EA, CYP3A5 loss-of-function alleles were associated with decreased CV of trough (P = 0.0042) and increased CV of dose (P < 0.0001).

CONCLUSION

CYP3A5 loss-of-function alleles influence intra-patient TAC trough and dose variability. High variability of TAC dose increases risk of acute rejection. High variability of TAC trough increases risk of graft failure. Early clinical recognition of TAC dose and trough variability may improve patient management and outcomes.

Clinical Impact of Pre-transplant Antibodies Against Angiotensin II Type I Receptor and Major Histocompatibility Complex Class I-Related Chain A in Kidney Transplant Patients

Background

Evidence of antibody-mediated injury in the absence of donor-specific HLA antibodies (HLA-DSA) has recently emerged, suggesting a role of antibodies in targeting non-HLA antigens expressed on renal allograft tissue. However, the clinical significance of pre-transplant non-HLA antibodies remains unclear. We compared the histological and clinical impact of pre-transplant HLA-DSA and non-HLA antibodies, especially angiotensin II type I receptor (anti-AT1R) and MHC class I-related chain A (anti-MICA), in kidney transplant patients.

Methods

Pre-transplant HLA-DSA, anti-AT1R, and anti-MICA were retrospectively examined in 359 kidney transplant patients to determine the effect of each antibody on allograft survival and clinical characteristics.

Results

Pre-transplant HLA-DSA, anti-AT1R, and anti-MICA were detected in 37 (10.3%), 174 (48.5%), and 50 patients (13.9%), respectively. Post-transplant antibody-mediated rejection was associated with a pre-transplant HLA-DSA (+) status only. The development of microvascular inflammation (MVI) was associated with pre-transplant HLA-DSA (P=0.001) and anti-AT1R (P=0.036). Anti-AT1R (+) patients had significantly lower allograft survival compared with anti-AT1R (−) patients (P=0.042). Only pre-transplant anti-AT1R positivity was an independent risk factor for allograft failure (hazard ratio 4.824, confidence interval 1.017–24.888; P=0.038). MVI was the most common histological feature of allograft failure in patients with pre-transplant anti-AT1R.

Conclusions

Pre-transplant anti-AT1R is an important risk factor for allograft failure, which may be mediated by MVI induction in the allograft tissue.

Racial disparity in kidney transplant survival relates to late rejection and is independent of steroid withdrawal

Black kidney transplant recipients have more acute rejection (AR) and inferior graft survival. We sought to determine whether early steroid withdrawal (ESW) had an impact on AR and death-censored graft loss (DCGL) in blacks. From 2006 to 2012, AR and graft survival were analyzed in 483 kidney recipients (208 black and 275 non-black). Rates of ESW were similar between blacks (65%) and non-blacks (67%). AR was defined as early (≤3 months) or late (>3 months). The impact of black race, early AR, and late AR on death-censored graft failure was analyzed using univariate and multivariate Cox models. Blacks had greater dialysis vintage, more deceased donor transplants, and less HLA matching, yet rates of early AR were comparable between blacks and non-blacks. However, black race was a risk factor for late AR (HR: 3.48 (95% CI: 1.87-6.47)) Blacks had a greater rate of DCGL, partially driven by late AR (HR with late AR: 5.6; 95% CI: 3.3-9.3). ESW had no significant interaction with black race for risk of early AR, late AR, or DCGL. Independent of ESW, black kidney recipients had a higher rate of late AR after kidney transplantation. Late AR was highly predictive of DCGL and contributed to inferior graft survival in blacks.

Gut microbes contribute to variation in solid organ transplant outcomes in mice

BACKGROUND

Solid organ transplant recipients show heterogeneity in the occurrence and timing of acute rejection episodes. Understanding the factors responsible for such variability in patient outcomes may lead to improved diagnostic and therapeutic approaches. Rejection kinetics of transplanted organs mainly depends on the extent of genetic disparities between donor and recipient, but a role for environmental factors is emerging. We have recently shown that major alterations of the microbiota following broad-spectrum antibiotics, or use of germ-free animals, promoted longer skin graft survival in mice. Here, we tested whether spontaneous differences in microbial colonization between genetically similar individuals can contribute to variability in graft rejection kinetics.

RESULTS

We compared rejection kinetics of minor mismatched skin grafts in C57BL/6 mice from Jackson Laboratory (Jax) and Taconic Farms (Tac), genetically similar animals colonized by different commensal microbes. Female Tac mice rejected skin grafts from vendor-matched males more quickly than Jax mice. We observed prolonged graft survival in Tac mice when they were exposed to Jax mice microbiome through co-housing or fecal microbiota transplantation (FMT) by gastric gavage. In contrast, exposure to Tac mice did not change graft rejection kinetics in Jax mice, suggesting a dominant suppressive effect of Jax microbiota. High-throughput sequencing of 16S rRNA gene amplicons from Jax and Tac mice fecal samples confirmed a convergence of microbiota composition after cohousing or fecal transfer. Our analysis of amplicon data associated members of a single bacterial genus, Alistipes, with prolonged graft survival. Consistent with this finding, members of the genus Alistipes were absent in a separate Tac cohort, in which fecal transfer from Jax mice failed to prolong graft survival.

CONCLUSIONS

These results demonstrate that differences in resident microbiome in healthy individuals may translate into distinct kinetics of graft rejection, and contribute to interpersonal variability in graft outcomes. The association between Alistipes and prolonged skin graft survival in mice suggests that members of this genus might affect host physiology, including at sites distal to the gastrointestinal tract. Overall, these findings allude to a potential therapeutic role for specific gut microbes to promote graft survival through the administration of probiotics, or FMT.

A Machine Learning Approach Using Survival Statistics to Predict Graft Survival in Kidney Transplant Recipients: A Multicenter Cohort Study

Accurate prediction of graft survival after kidney transplant is limited by the complexity and heterogeneity of risk factors influencing allograft survival. In this study, we applied machine learning methods, in combination with survival statistics, to build new prediction models of graft survival that included immunological factors, as well as known recipient and donor variables. Graft survival was estimated from a retrospective analysis of the data from a multicenter cohort of 3,117 kidney transplant recipients. We evaluated the predictive power of ensemble learning algorithms (survival decision tree, bagging, random forest, and ridge and lasso) and compared outcomes to those of conventional models (decision tree and Cox regression). Using a conventional decision tree model, the 3-month serum creatinine level post-transplant (cut-off, 1.65 mg/dl) predicted a graft failure rate of 77.8% (index of concordance, 0.71). Using a survival decision tree model increased the index of concordance to 0.80, with the episode of acute rejection during the first year post-transplant being associated with a 4.27-fold increase in the risk of graft failure. Our study revealed that early acute rejection in the first year is associated with a substantially increased risk of graft failure. Machine learning methods may provide versatile and feasible tools for forecasting graft survival.

Polyclonal and monoclonal antibodies for treating acute rejection episodes in kidney transplant recipients

BACKGROUND

Registry data shows that the incidence of acute rejection has been steadily falling. Approximately 10% to 35% of kidney recipients will undergo treatment for at least one episode of acute rejection within the first post-transplant year. Treatment options include pulsed steroid therapy, the use of an antibody preparation, the alteration of background immunosuppression, or combinations of these options. Over recent years, new treatment strategies have evolved, and in many parts of the world there has been an increase in use of tacrolimus and mycophenolate and a reduction in the use of cyclosporin and azathioprine use as baseline immunosuppression to prevent acute rejection. There are also global variations in use of polyclonal and monoclonal antibodies to treat acute rejection. This is an update of a review published in 2006.

OBJECTIVES

The aim of this systematic review was to: (1) to evaluate the relative and absolute effects of different classes of antibody preparation in preventing graft loss and resolving cellular or humoral rejection episodes when used as a treatment for first episode of rejection in kidney transplant recipients; (2) evaluate the relative and absolute effects of different classes of antibody preparation in preventing graft loss and resolving cellular or humoral rejection episodes when used as a treatment for steroid-resistant rejection in kidney transplant recipients; (3) determine how the benefits and adverse events vary for each type of antibody preparation; and (4) determine how the benefits and harms vary for different formulations of antibody within each type.

SEARCH METHODS

We searched the Cochrane Kidney and Transplant Specialised Register to 18 April 2017 through contact with the Information Specialist using search terms relevant to this review.

SELECTION CRITERIA

Randomised controlled trials (RCTs) in all languages comparing all mono- and polyclonal antibody preparations, given in combination with any other immunosuppressive agents, for the treatment of cellular or humoral graft rejection, when compared to any other treatment for acute rejection were eligible for inclusion.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed the risk of bias of the included studies and extracted data. Statistical analyses were performed using a random-effects model and results expressed as risk ratio (RR) or mean difference (MD) with 95% confidence intervals (CI).

MAIN RESULTS

We included 11 new studies (18 reports, 346 participants) in this update, bring the total number of included studies to 31 (76 reports, 1680 participants). Studies were generally small, incompletely reported, especially for potential harms, and did not define outcome measures adequately. The risk of bias was inadequate or unclear risk for random sequence generation (81%), allocation concealment (87%) and other bias (87%). There were, however, a predominance of low risk of bias for blinding (75%) and incomplete outcome data (80%) across all the studies. Selective reporting had a mixture of low (58%), high (29%), and unclear (13%) risk of bias.Seventeen studies (1005 participants) compared therapies for first acute cellular rejection episodes. Antibody therapy was probably better than steroid in reversing acute cellular rejection (RR 0.50, 95% CI 0.30 to 0.82; moderate certainty) and preventing subsequent rejection (RR 0.70, 95% CI 0.50 to 0.99; moderate certainty), may be better for preventing graft loss (death censored: (RR 0.80, 95% CI 0.57 to 1.12; low certainty) but there was little or no difference in death at one year. Adverse effects of treatment (including fever, chills and malaise following drug administration) were probably reduced with steroid therapy (RR 23.88, 95% CI 5.10 to 111.86; I2 = 16%; moderate certainty).Twelve studies (576 patients) investigated antibody treatment for steroid-resistant rejection. There was little or no benefit of muromonab-CD3 over ATG or ALG in reversing rejection, preventing subsequent rejection, or preventing graft loss or death. Two studies compared the use of rituximab for treatment of acute humoral rejection (58 patients). Muromonab-CD3 treated patients suffered three times more than those receiving either ATG or T10B9, from a syndrome of fever, chills and malaise following drug administration (RR 3.12, 95% CI 1.87 to 5.21; I2 = 31%), and experienced more neurological side effects (RR 13.10 95% CI 1.43 to 120.05; I2 = 36%) (low certainty evidence).There was no evidence of additional benefit from rituximab in terms of either reversal of rejection (RR 0.94, 95% CI 0.54 to 1.64), or graft loss or death 12 months (RR 1.0, 95% CI 0.23 to 4.35). Rituximab plus steroids probably increases the risk of urinary tract infection/pyelonephritis (RR 5.73, 95% CI 1.80 to 18.21).

AUTHORS' CONCLUSIONS

In reversing first acute cellular rejection and preventing graft loss, any antibody is probably better than steroid, but there is little or no difference in subsequent rejection and patient survival. In reversing steroid-resistant rejection there was little or no difference between different antibodies over a period of 12 months, with limited data beyond that time frame. In treating acute humoral rejection, there was no evidence that the use of antibody therapy conferred additional benefit in terms of reversal of rejection, or death or graft loss.Although this is an updated review, the majority of newer included studies provide additional evidence from the cyclosporin/azathioprine era of kidney transplantation and therefore conclusions cannot necessarily be extrapolated to patients treated with more contemporary immunosuppressive regimens which include tacrolimus/mycophenolate or sirolimus. However, many kidney transplant centres around the world continue to use older immunosuppressive regimes and the findings of this review remain strongly relevant to their clinical practice.Larger studies with standardised reproducible outcome criteria are needed to investigate the outcomes and risks of antibody treatments for acute rejection in kidney transplant recipients receiving contemporary immunosuppressive regimes.

Targeting the Monocyte-Macrophage Lineage in Solid Organ Transplantation

There is an unmet clinical need for immunotherapeutic strategies that specifically target the active immune cells participating in the process of rejection after solid organ transplantation. The monocyte–macrophage cell lineage is increasingly recognized as a major player in acute and chronic allograft immunopathology. The dominant presence of cells of this lineage in rejecting allograft tissue is associated with worse graft function and survival. Monocytes and macrophages contribute to alloimmunity via diverse pathways: antigen processing and presentation, costimulation, pro-inflammatory cytokine production, and tissue repair. Cross talk with other recipient immune competent cells and donor endothelial cells leads to amplification of inflammation and a cytolytic response in the graft. Surprisingly, little is known about therapeutic manipulation of the function of cells of the monocyte–macrophage lineage in transplantation by immunosuppressive agents. Although not primarily designed to target monocyte–macrophage lineage cells, multiple categories of currently prescribed immunosuppressive drugs, such as mycophenolate mofetil, mammalian target of rapamycin inhibitors, and calcineurin inhibitors, do have limited inhibitory effects. These effects include diminishing the degree of cytokine production, thereby blocking costimulation and inhibiting the migration of monocytes to the site of rejection. Outside the field of transplantation, some clinical studies have shown that the monoclonal antibodies canakinumab, tocilizumab, and infliximab are effective in inhibiting monocyte functions. Indirect effects have also been shown for simvastatin, a lipid lowering drug, and bromodomain and extra-terminal motif inhibitors that reduce the cytokine production by monocytes–macrophages in patients with diabetes mellitus and rheumatoid arthritis. To date, detailed knowledge concerning the origin, the developmental requirements, and functions of diverse specialized monocyte–macrophage subsets justifies research for therapeutic manipulation. Here, we will discuss the effects of currently prescribed immunosuppressive drugs on monocyte/macrophage features and the future challenges.

Metabolic Acidosis and Long-Term Clinical Outcomes in Kidney Transplant Recipients

Metabolic acidosis (MA), indicated by low serum total CO₂ (TCO₂) concentration, is a risk factor for mortality and progressive renal dysfunction in CKD. However, the long-term effects of MA on kidney transplant recipients (KTRs) are unclear. We conducted a multicenter retrospective cohort study of 2318 adult KTRs, from January 1, 1997 to March 31, 2015, to evaluate the prevalence of MA and the relationships between TCO₂ concentration and clinical outcomes. The prevalence of low TCO₂ concentration (<22 mmol/L) began to increase in KTRs with eGFR<60 ml/min per 1.73 m² and ranged from approximately 30% to 70% in KTRs with eGFR<30 ml/min per 1.73 m² Multivariable Cox proportional hazards models revealed that low TCO₂ concentration 3 months after transplant associated with increased risk of graft loss (hazard ratio [HR], 1.74%; 95% confidence interval [95% CI], 1.26 to 2.42) and death-censored graft failure (DCGF) (HR, 1.66; 95% CI, 1.14 to 2.42). Cox regression models using time-varying TCO₂ concentration additionally demonstrated significant associations between low TCO₂ concentration and graft loss (HR, 3.48; 95% CI, 2.47 to 4.90), mortality (HR, 3.16; 95% CI, 1.77 to 5.62), and DCGF (HR, 3.17; 95% CI, 2.12 to 4.73). Marginal structural Cox models adjusted for time-varying eGFR further verified significant hazards of low TCO₂ concentration for graft loss, mortality, and DCGF. In conclusion, MA was frequent in KTRs despite relatively preserved renal function and may be a significant risk factor for graft failure and patient mortality, even after adjusting for eGFR.

The Reasons of Renal Transplant Recipients' Admission to the Emergency Department; a Case Series Study

INTRODUCTION

Renal transplantation are admitted to emergency department (ED) more than normal population. The present brief report aimed to determine the reasons of renal transplant patients' ED visits.

METHODS

This retrospective case series study analyzed the reasons of renal transplant recipients' admission to one ED between 2011 and 2014. The patient data were collected via a checklist and presented using descriptive statistics tools.

RESULTS

41 patients with the mean age of 40.63 ± 10.95 years were studied (60.9% male). The most common ED presenting complaints were fever (36.6%) and abdominal pain (26.8%). Infections were the most common final diagnosis (68.3%). Among non-infectious causes, the most common was acute renal failure (9.7 %). 73.2% of the patients were hospitalized and no cases of graft loss and mortality were seen.

CONCLUSION

The most common reason for ED admission was fever, and infections were the most common diagnosis. Acute gastroenteritis being the most frequent infection and among non-infectious problems, acute renal failure was the most frequent one.