The impact of an acute rejection episode on long-term renal allograft survival (t1/2)

C-reactive protein orchestrates acute allograft rejection in vascularized composite allotransplantation via selective activation of monocyte subsets

INTRODUCTION

Despite advancements in transplant immunology and vascularized composite allotransplantation (VCA), the longevity of allografts remains hindered by the challenge of allograft rejection. The acute-phase response, an immune-inflammatory reaction to ischemia/reperfusion that occurs directly after allogeneic transplantation, serves as a catalyst for graft rejection. This immune response is orchestrated by acute-phase reactants through intricate crosstalk with the mononuclear phagocyte system.

OBJECTIVE

C-reactive protein (CRP), a well-known marker of inflammation, possesses pro-inflammatory properties and exacerbates ischemia/reperfusion injury. Thus, we investigated how CRP impacts acute allograft rejection.

METHODS

Prompted by clinical observations in facial VCAs, we employed a complex hindlimb transplantation model in rats to investigate the direct impact of CRP on transplant rejection.

RESULTS

Our findings demonstrate that CRP expedites allograft rejection and diminishes allograft survival by selectively activating non-classical monocytes. Therapeutic stabilization of CRP abrogates this activating effect on monocytes, thereby attenuating acute allograft rejection. Intravital imagining of graft-infiltrating, recipient-derived monocytes during the early phase of acute rejection corroborated their differential regulation by CRP and their pivotal role in driving the initial stages of graft rejection.

CONCLUSION

The differential activation of recipient-derived monocytes by CRP exacerbates the innate immune response and accelerates clinical allograft rejection. Thus, therapeutic targeting of CRP represents a novel and promising strategy for preventing acute allograft rejection and potentially mitigating chronic allograft rejection.

Effects of CYP3A4*22 and POR*28 variations on the pharmacokinetics of tacrolimus in renal transplant recipients: a meta-analysis of 18 observational studies

PURPOSE

This study aimed to investigate the association between cytochrome P450 (CYP) 3A4*22 and cytochrome P450 oxidoreductase (POR)*28 variations and the pharmacokinetics of tacrolimus.

METHODS

Cochrane Central Register of Controlled Trials (CENTRAL), Web of Science (SCI), MEDLINE, and Embase were systematically searched from inception to August 2022. The outcomes were weight-adjusted daily dose and dose-adjusted trough concentration (C0/Dose).

RESULTS

The study included 2931 renal transplant recipients from 18 publications. Weight-adjusted daily dose of CYP3A4*1/*1 carriers was 0.04 (WMD = 0.04, 95% CI: 0.02 to 0.06), 0.03 (WMD = 0.03, 95% CI: 0.02 to 0.05), 0.02 (WMD = 0.02, 95% CI: 0.01 to 0.03), or 0.02 mg/kg/day (WMD = 0.02, 95% CI: 0.00 to 0.04) higher than CYP3A4*22 carriers in Caucasians at 1 month, 3 months, 6 months, or 12 months post-transplantation. Conversely, C0/Dose was lower for CYP3A4*1/*1 carriers at 3 days (SMD = -0.35, 95% CI: -0.65 to -0.06), 1 month (SMD = -0.67, 95% CI: -1.16 to -0.18), 3 months (SMD = -0.60, 95% CI: -0.89 to -0.31), 6 months (SMD = -0.76, 95% CI: -1.49 to -0.04), or 12 months post-transplantation (SMD = -0.69, 95% CI: -1.37 to 0.00). Furthermore, C0/Dose of POR*1/*1 carriers was 22.64 (WMD = 22.64, 95% CI: 2.54 to 42.74) or 19.41 (ng/ml)/(mg/kg/day) (WMD = 19.41, 95% CI: 9.58 to 29.24) higher than POR*28 carriers in CYP3A5 expressers at 3 days or 7 days post-transplantation, and higher in Asians at 6 months post-transplantation (SMD = 0.96, 95% CI: 0.50 to 1.43).

CONCLUSIONS

CYP3A4*22 variant in Caucasians restrains the metabolism of tacrolimus, while POR*28 variant in CYP3A5 expressers enhances the metabolism of tacrolimus for renal transplant recipients. However, further well-designed prospective studies are necessary to substantiate these conclusions given some limitations.

Study the mRNA level of IL-27/IL-27R pathway molecules in kidney transplant rejection

BACKGROUND

Renal transplantation stands as the sole remedy for individuals afflicted with end-stage renal diseases, and safeguarding them from transplant rejection represents a vital, life-preserving endeavor posttransplantation. In this context, the impact of cytokines, notably IL-27, assumes a critical role in managing immune responses aimed at countering rejection. Consequently, this investigation endeavors to explore the precise function of IL-27 and its associated cytokines in the context of kidney transplant rejection.

METHODS

The study involved the acquisition of blood samples from a cohort of participants, consisting of 61 individuals who had undergone kidney transplantation (comprising 32 nonrejected patients and 29 rejected patients), and 33 healthy controls. The expression levels of specific genes were examined using SYBR Green Real-time PCR. Additionally, the evaluation encompassed the estimation of the ROC curve, the assessment of the relationship between certain blood factors, and the construction of protein-protein interaction networks for the genes under investigation.

RESULTS

Significant statistical differences in gene expression levels were observed between the rejected group and healthy controls, encompassing all the genes examined, except for TLR3 and TLR4 genes. Moreover, the analysis of the Area Under the Curve (AUC) revealed that IL-27, IL-27R, TNF-α, and TLR4 exhibited greater significance in discriminating between the two patient groups. These findings highlight the potential importance of IL-27, IL-27R, TNF-α, and TLR4 as key factors for distinguishing between individuals in the rejected group and those in the healthy control group.

CONCLUSIONS

In the context of kidney rejections occurring within the specific timeframe of 2 weeks to 2 months post-transplantation, it is crucial to emphasize the significance of cytokines mRNA level, including IL-27, IL-27R, TNF-α, and TLR4, in elucidating and discerning the diverse immune system responses. The comprehensive examination of these cytokines' mRNA level assumes considerable importance in understanding the intricate mechanisms underlying kidney rejection processes during this critical period.

Evaluation of Antithymocyte Globulin Efficacy in Reversing Refractory Graft Rejection Using Retrospective Event-Based Sequential Graft Biopsy Analysis in Living Related Donor Renal Transplant

OBJECTIVES

The main risk factor for poor graft outcomes is refractory acute rejection and its consequences. In this study, we compared the efficacy of antithymocyte globulins versus other antirejection strategies in reversing refractory acute graft rejection after living donor renal transplant.

MATERIALS AND METHODS

We retrospectively reviewed the records of 745 patients who received living-donor kidney transplants and experienced acute rejection episodes at Mansoura Urology and Nephrology Center in Egypt over the past 20 years. Based on the type of antirejection medication that they received, we divided patients into 2 groups, with 80 patients in the antithymocyte globulin group and 665 patients who had other antirejection strategies. By using event-based sequential graft biopsy histopathology analysis, we compared the efficacy of antithymocyte globulins in reversing refractory rejection in terms of graft and patient complications and survival.

RESULTS

Patient survival was comparable in both groups; however, graft survival was better in the antithymocyte globulin group than in the other group; in addition, event-based sequential graft biopsies revealed a lower incidence of acute and chronic rejection episodes after treatment of severe acute rejection in the antithymocyte globulin group compared with the other group. Incidence of posttreatment complications, particularly infection and malignancy, was comparable in both groups.

CONCLUSIONS

Our retrospective analysis of event-based sequential graft biopsy allowed us to track graft rejection resolution or worsening. Antithymocyte globulins are highly effective in reversing acute graft rejection when compared with other approaches, with no increased risk of infection or malignancy.

Inhibition of thrombin on endothelium enhances recruitment of regulatory T cells during IRI and when combined with adoptive Treg transfer, significantly protects against acute tissue injury and prolongs allograft survival

Ischemia-reperfusion injury (IRI) amplifies T cell alloimmune responses after transplantation with thrombin playing a key pro-inflammatory role. To explore the influence of thrombin on regulatory T cell recruitment and efficacy we used a well-established model of IRI in the native murine kidney. Administration of the cytotopic thrombin inhibitor PTL060 inhibited IRI, and by skewing expression of chemokines (reducing CCL2 and CCL3 but increasing CCL17 and CCL22) increased the infiltration of M2 macrophages and Tregs. When PTL060 was combined with infusion of additional Tregs, these effects were further amplified. To test the benefits of thrombin inhibition in a transplant model, BALB/c hearts were transplanted into B6 mice with or without perfusion with PTL060 in combination with Tregs. Thrombin inhibition or Treg infusion alone led to small increments in allograft survival. However, the combined therapy led to modest graft prolongation by the same mechanisms as in renal IRI; graft survival was accompanied by increased numbers of Tregs and anti-inflammatory macrophages, and reduced expression of pro-inflammatory cytokines. While the grafts succumbed to rejection associated with the emergence of alloantibody, these data suggest that thrombin inhibition within the transplant vasculature enhances the efficacy of Treg infusion, a therapy that is currently entering the clinic to promote transplant tolerance.

A novel phosphocholine-mimetic inhibits a pro-inflammatory conformational change in C-reactive protein

C-reactive protein (CRP) is an early-stage acute phase protein and highly upregulated in response to inflammatory reactions. We recently identified a novel mechanism that leads to a conformational change from the native, functionally relatively inert, pentameric CRP (pCRP) structure to a pentameric CRP intermediate (pCRP*) and ultimately to the monomeric CRP (mCRP) form, both exhibiting highly pro-inflammatory effects. This transition in the inflammatory profile of CRP is mediated by binding of pCRP to activated/damaged cell membranes via exposed phosphocholine lipid head groups. We designed a tool compound as a low molecular weight CRP inhibitor using the structure of phosphocholine as a template. X-ray crystallography revealed specific binding to the phosphocholine binding pockets of pCRP. We provide in vitro and in vivo proof-of-concept data demonstrating that the low molecular weight tool compound inhibits CRP-driven exacerbation of local inflammatory responses, while potentially preserving pathogen-defense functions of CRP. The inhibition of the conformational change generating pro-inflammatory CRP isoforms via phosphocholine-mimicking compounds represents a promising, potentially broadly applicable anti-inflammatory therapy.

Improve in-depth immunological risk assessment to optimize genetic-compatibility and clinical outcomes in child and adolescent recipients of parental donor kidney transplants: protocol for the INCEPTION study

Background

Parental donor kidney transplantation is the most common treatment option for children and adolescents with kidney failure. Emerging data from observational studies have reported improved short- and medium-term allograft outcomes in recipients of paternal compared to maternal donors. The INCEPTION study aims to identify potential differences in immunological compatibility between maternal and paternal donor kidneys and ascertain how this affects kidney allograft outcomes in children and adolescents with kidney failure.

Methods

This longitudinal observational study will recruit kidney transplant recipients aged ≤18 years who have received a parental donor kidney transplant across 4 countries (Australia, New Zealand, United Kingdom and the Netherlands) between 1990 and 2020. High resolution human leukocyte antigen (HLA) typing of both recipients and corresponding parental donors will be undertaken, to provide an in-depth assessment of immunological compatibility. The primary outcome is a composite of de novo donor-specific anti-HLA antibody (DSA), biopsy-proven acute rejection or allograft loss up to 60-months post-transplantation. Secondary outcomes are de novo DSA, biopsy-proven acute rejection, acute or chronic antibody mediated rejection or Chronic Allograft Damage Index (CADI) score of > 1 on allograft biopsy post-transplant, allograft function, proteinuria and allograft loss. Using principal component analysis and Cox proportional hazards regression modelling, we will determine the associations between defined sets of immunological and clinical parameters that may identify risk stratification for the primary and secondary outcome measures among young people accepting a parental donor kidney for transplantation. This study design will allow us to specifically investigate the relative importance of accepting a maternal compared to paternal donor, for families deciding on the best option for donation.

Discussion

The INCEPTION study findings will explore potentially differential immunological risks of maternal and paternal donor kidneys for transplantation among children and adolescents. Our study will provide the evidence base underpinning the selection of parental donor in order to achieve the best projected long-term kidney transplant and overall health outcomes for children and adolescents, a recognized vulnerable population.

Trial registration

The INCEPTION study has been registered with the Australian New Zealand Clinical Trials Registry, with the trial registration number of ACTRN12620000911998 (14th September 2020).

Early Transplant Arteriopathy in Kidney Transplantation

BACKGROUND

Early dysfunction of renal allografts may be associated with vascular injury, which raises the specter of active rejection processes that require medical intervention. In our practice, we have encountered patients who present with delayed graft function and demonstrate a unique pattern of endothelial cell injury that raises concern for rejection in their biopsy. Therefore, we sought to systematically determine the biopsy characteristics and outcome of these patients.

METHODS

During a 17-year period at the University of Washington in Seattle, United States, we identified 24 cases of a distinct arterial vasculopathy presenting in the first year posttransplantation. This early transplant arteriopathy (ETA) is characterized by endothelial cell swelling and intimal edema but without the intimal arteritis that defines vascular rejection.

RESULTS

Approximately 1% of transplant biopsies during the study period showed ETA, almost all of which were in deceased donor organs (96%), and most presented with delayed graft function (54%) or increased serum creatinine (38%) soon after transplantation (median 13 days; range, 5-139). In this study, 77% of patients were managed expectantly, with only 2 patients (7.6%) subsequently developing acute vascular rejection. Except for 1 patient who died, all patients had functioning allografts at 1 year follow-up.

CONCLUSION

Recognizing ETA and distinguishing it from vascular rejection is important to prevent over-treatment because most patients appear to recover allograft function rapidly with expectant management.

Donor-specific ELISPOT assay for predicting acute rejection and allograft function after kidney transplantation: A systematic review and meta-analysis

Acute rejection remains an important problem after kidney transplantation. Enzyme-linked immunosorbent spot (ELISPOT) assay has been investigated extensively and has shown promising results as a predictor of allograft rejection. The objective of this study was to systematically review and analyze the predictive value of the donor-specific ELISPOT assay to identify recipients at risk for acute rejection. Electronic databases were searched for studies reporting donor-specific ELISPOT and kidney transplantation outcomes. Odds ratio (OR) for acute rejection was calculated, along with standardized mean difference (SMD) of cytokine producing-cells between recipients with and without acute rejection. Pooled estimates were calculated using random-effect models. The positive ELISPOT cutoff frequencies were extracted from each study. From 665 articles found, 32 studies were included in the meta-analysis. IFN-γ was the most investigated cytokine (30 out of 32 studies). Patients with positive pre-transplantation donor-reactive IFN-γ ELISPOT had an OR of 3.3 for acute rejection (95%-CI 2.1 to 5.1), and OR of 6.8 (95%-CI 2.5 to 18.9) for post-transplantation ELISPOT. Recipients with rejection had significantly higher frequencies of pre- and post-transplantation cytokine producing-cells (SMD 0.47, 95%-CI 0.07 to 0.87 and SMD 3.68, 95%-CI 1.04 to 6.32, respectively). Pre-transplantation ELISPOT had a positive predictive value of 43% and a negative predictive value of 81% for acute rejection. A positive ELISPOT result was associated with a lower estimated glomerular filtration rate (SMD -0.59, 95%-CI -0.83 to -0.34). In conclusion, patients with a high frequency of donor-reactive IFN-γ ELISPOT are at higher risk for acute rejection. The donor-specific IFN-γ ELISPOT assay can serve as an immune-monitoring tool in kidney transplantation.

Reconstruction of Critical Nerve Defects Using Allogenic Nerve Tissue: A Review of Current Approaches

Regardless of the nerve defect length, nerve injury is a debilitating condition for the affected patient that results in loss of sensory and motor function. These functional impairments can have a profound impact on the patient’s quality of life. Surgical approaches for the treatment of short segment nerve defects are well-established. Autologous nerve transplantation, considered the gold standard, and the use of artificial nerve grafts are safe and successful procedures for short segment nerve defect reconstruction. Long segment nerve defects which extend 3.0 cm or more are more problematic for repair. Methods for reconstruction of long defects are limited. Artificial nerve grafts often fail to regenerate and autologous nerve grafts are limited in length and number. Cadaveric processed/unprocessed nerve allografts are a promising alternative in nerve surgery. This review gives a systematic overview on pre-clinical and clinical approaches in nerve allograft transplantation.

Prevention of Chronic Rejection of Marginal Kidney Graft by Using a Hydrogen Gas-Containing Preservation Solution and Adequate Immunosuppression in a Miniature Pig Model

In clinical kidney transplantation, the marginal kidney donors are known to develop chronic allograft rejection more frequently than living kidney donors. In our previous study, we have reported that the hydrogen gas-containing organ preservation solution prevented the development of acute injuries in the kidney of the donor after cardiac death by using preclinical miniature pig model. In the present study, we verified the impact of hydrogen gas treatment in transplantation with the optimal immunosuppressive protocol based on human clinical setting by using the miniature pig model. Marginal kidney processed by hydrogen gas-containing preservation solution has been engrafted for long-term (longer than 100 days). A few cases showed chronic rejection reaction; however, most were found to be free of chronic rejection such as graft tissue fibrosis or renal vasculitis. We concluded that marginal kidney graft from donor after cardiac death is an acceptable model for chronic rejection and that if the transplantation is carried out using a strict immunosuppressive protocol, chronic rejection may be alleviated even with the marginal kidney.

Bone Fragment Co-transplantation Alongside Bone Marrow Aspirate Infusion Protects Kidney Transplant Recipients

Integration of non-vascularized bone grafting and bone marrow aspirate infusion in transplantation may provide clinical benefit. Here we have incorporated bone fragment co-transplantation and bone marrow aspirate infusion (BF-BM) into living kidney transplantation (LKT). Twenty LKT recipients receiving bone fragments and bone marrow aspirates donated from their corresponding donors were enrolled into a retrospective study. A contemporaneous control group was formed of 38 out of 128 conventional LKT recipients, selected using propensity score matching by a 1:2 Greedy algorithm. Ultrasonography, contrast-enhanced ultrasonography (US/CEUS) and SPECT/CT showed that the co-transplanted bone fragments remained viable for 6 months, subsequently shrank, and finally degenerated 10 months post-transplantation. BF-BM resulted in earlier kidney recovery and more robust long-term kidney function. Throughout 5 years of follow-up, BF-BM had regulatory effects on dendritic cells (DCs), T helper (Th1/Th2) cells and regulatory T cells (Tregs). Both alloantigen-specific lymphocyte proliferation and panel reactive antibody levels were negative in all recipients with or without BF-BM. In addition, the BF-BM group experienced few complications during the 5-year follow-up (as did the donors)—this was not different from the controls. In conclusion, BF-BM is safe and benefits recipients by protecting the kidney and regulating the immune response.

Analysis of 75 Candidate SNPs Associated With Acute Rejection in Kidney Transplant Recipients: Validation of rs2910164 in MicroRNA MIR146A

BACKGROUND

Identifying kidney allograft recipients who are predisposed to acute rejection (AR) could allow for optimization of clinical treatment to avoid rejection and prolong graft survival. It has been hypothesized that a part of this predisposition is caused by the inheritance of specific genetic variants. There are many publications reporting a statistically significant association between a genetic variant, usually in the form of a single-nucleotide polymorphism (SNP), and AR. However, there are additional publications reporting a lack of this association when a different cohort of recipients is analyzed for the same single-nucleotide polymorphism.

METHODS

In this report, we attempted to validate 75 common genetic variants, which have been previously reported to be associated with AR, using a large kidney allograft recipient cohort of 2390 European Americans and 482 African Americans.

RESULTS

Of those variants tested, only 1 variant, rs2910164, which alters the expression of the microRNA MIR146A, was found to exhibit a significant association within the African American cohort. Suggestive variants were found in the genes CTLA and TLR4.

CONCLUSIONS

Our results show that most variants previously reported to be associated with AR were not validated in our cohort. This shows the importance of validation when reporting the associations with complex clinical outcomes such as AR. Additional work will need to be done to understand the role of MIR146A in the risk of AR in kidney allograft recipients.

Kidney transplant monitoring by urinary flow cytometry: Biomarker combination of T cells, renal tubular epithelial cells, and podocalyxin-positive cells detects rejection

Creatinine and proteinuria are used to monitor kidney transplant patients. However, renal biopsies are needed to diagnose renal graft rejection. Here, we assessed whether the quantification of different urinary cells would allow non-invasive detection of rejection. Urinary cell numbers of CD4⁺ and CD8⁺ T cells, monocytes/macrophages, tubular epithelial cells (TEC), and podocalyxin(PDX)-positive cells were determined using flow cytometry and were compared to biopsy results. Urine samples of 63 renal transplant patients were analyzed. Patients with transplant rejection had higher amounts of urinary T cells than controls; however, patients who showed worsening graft function without rejection had similar numbers of T cells. T cells correlated with histological findings (interstitial inflammation p = 0.0005, r = 0.70; tubulitis p = 0.006, r = 0.58). Combining the amount of urinary T cells and TEC, or T cells and PDX⁺ cells, yielded a significant segregation of patients with rejection from patients without rejection (all p < 0.01, area under the curve 0.89–0.91). Urinary cell populations analyzed by flow cytometry have the potential to introduce new monitoring methods for kidney transplant patients. The combination of urinary T cells, TEC, and PDX-positive cells may allow non-invasive detection of transplant rejection.

Life and death: A systematic comparison of antemortem and postmortem gene expression

Gene expression is the process by which DNA is decoded to produce a functional transcript. The collection of all transcripts is referred to as the transcriptome and has extensively been used to evaluate differentially expressed genes in a certain cell or tissue type. In response to internal or external stimuli, the transcriptome is greatly regulated by epigenetic changes. Many studies have elucidated that antemortem gene expression (transcriptome) may be linked to an array of disease etiologies as well as potential targets for drug discovery; on the other hand, a number of studies have utilized postmortem gene expression (thanatotranscriptome) patterns to determine cause and time of death. The "transcriptome after death" involves the study of mRNA transcripts occurring in human tissues after death (thanatos, Greek for death). While antemortem gene expression can provide a wide range of important information about the host, the determination of the communication of genes after a human dies has recently been explored. After death a plethora of genes are regulated via activation versus repression as well as diverse regulatory factors such as the absence or presence of stimulated feedback. Even postmortem transcriptional regulation contains many more cellular constituents and is massively more complicated. The rates of degradation of mRNA transcripts vary depending on the types of postmortem tissues and their combinatorial gene expression signatures. mRNA molecules have been shown to persist for extended time frames; nevertheless, they are highly susceptible to degradation, with half-lives of selected mRNAs varying between minutes to weeks for specifically induced genes. Furthermore, postmortem genetic studies may be used to improve organ transplantation techniques. This review is the first of its kind to fully explore both gene expression and mRNA stability after death and the trove of information that can be provided about phenotypical characteristics of specific genes postmortem.

MRI for diagnosis of post-renal transplant complications: current state-of-the-art and future perspectives

Kidney transplantation has developed into a widespread procedure to treat end stage renal failure, with transplantation results improving over the years. Postoperative complications have decreased over the past decades, but are still an important cause of morbidity and mortality. Early accurate diagnosis and treatment is the key to prevent renal allograft impairment or even graft loss. Ideally, a diagnostic tool should be able to detect post-transplant renal dysfunction, differentiate between the different causes and monitor renal function during and after therapeutic interventions. Non-invasive imaging modalities for diagnostic purposes show promising results. Magnetic resonance imaging (MRI) techniques have a number of advantages, such as the lack of ionizing radiation and the possibility to obtain relevant tissue information without contrast, reducing the risk of contrast-induced nephrotoxicity. However, most techniques still lack the specificity to distinguish different types of parenchymal diseases. Despite some promising outcomes, MRI is still barely used in the post-transplantation diagnostic process. The aim of this review is to survey the current literature on the relevance and clinical applicability of diagnostic MRI modalities for the detection of various types of complications after kidney transplantation.

Downregulation of Protein Inhibitor of Activated STAT (PIAS) 1 Is Possibly Involved in the Process of Allograft Rejection

BACKGROUND

Protein inhibitors of activated STAT (PIAS) proteins are regarded as negative regulators of cytokine-signaling and potent immunosuppressive proteins. However, their role in the process of organ transplant rejection has not been elucidated.

METHODS

In the current study, we compared transcript levels of PIAS1 to 4 in the peripheral blood of renal transplant recipients who experienced transplant rejection with those having normal transplant functions. Expression of PIAS1 was significantly higher in nonrejected group compared with the rejected group among male recipients; however, differences were insignificant among female recipients. Expressions of other PIAS genes were not different between study groups. Significant pairwise correlations were found between expression levels of PIAS genes in all study subgroups. The current investigation highlights the role of PIAS1 downregulation in the evolution of graft rejection and potentiates this gene as a predictive marker for transplant fate.

Trends in kidney transplant outcomes in children and young adults with cystinosis

Temporal changes in kidney transplant outcomes for cystinosis are unknown. We used the SRTR to identify all kidney transplants performed for cystinosis in patients younger than 31 years between 1987 and 2017. We divided time into three equal eras (1987-1997, 1998-2007, and 2008-2017) to assess changes in outcomes using Cox proportional and linear regression models. We examined 441 transplants in 362 patients. Age at ESRD progressively increased (12.1 vs 13.3 vs 13.4; P = .046). Eras 2 and 3 had lower risk of acute rejection (aHR 2 vs 1:0.45; P < .001) (aHR 3 vs 1:0.26; P < .001) and higher 5-year mean GFR (difference 2 vs 1:9.2 mL/min/1.73 m² ; P = .005) (difference 3 vs 1:12.9 mL/min/1.73 m² ; P = .002) compared with era 1. Five-year graft survival was similar across eras, but 5-year patient survival was higher for era 2 (aHR: 0.25; P = .01). Seventy-nine patients underwent retransplantation. Five-year patient (94.2% vs 92.5%; P = .57) and graft survival (79.1% vs 74.1%; P = .52) were similar between primary and subsequent transplants. Age at ESRD, acute rejection, GFR at 5 years, and patient survival improved over time. Kidney retransplantation is associated with excellent outcomes in children and young adults with cystinosis.

The Impact of CYP3A4*22 on Tacrolimus Pharmacokinetics and Outcome in Clinical Practice at a Single Kidney Transplant Center

Background: Although there is evidence that the CYP3A4*22 variant should be considered in tacrolimus dosing in renal transplantation, its impact beyond tacrolimus dose requirements remains controversial. Methods: In a cohort of 121 kidney transplant recipients, we analyzed the CYP3A4*1B, CYP3A4*22, and CYP3A5*3 alleles and the ABCB1 variants 1236C>T, 2677G>T/A, and 3435C>T for their impact on exposure and dose requirement. Relevant clinical outcome measures such as acute rejection within the first year after transplantation, delayed graft function, and renal function at discharge (estimated glomerular filtration rate) were evaluated. Results: Extensive metabolizer (n = 17, CYP3A4*1/*1 carriers with at least one CYP3A5*1 allele) showed significantly higher tacrolimus dose requirement (P = 0.004) compared with both intermediate metabolizer (IM, n = 93, CYP3A5*3/*3 plus CYP3A4*1/*1 or CYP3A4*22 carriers plus one CYP3A5*1 allele), and poor metabolizer (n = 11, CYP3A4*22 allele in combination with CYP3A5*3/*3) after onset of therapy. Significantly higher dose requirement was observed in CYP3A5 expressers (P = 0.046) compared with non-expressers again at onset of therapy. Using the log additive genetic model, the area under the curve for the total observation period up to 16 days was significantly associated with the CYP3A5*3 genotype (P = 3.34 × 10-4) as well as with the IM or extensive metabolizer phenotype (P = 1.54 × 10-4), even after adjustment for multiple testing. Heterozygous carriers for CYP3A4*22 showed significantly higher areas under the curve than the CYP3A4*1/*1 genotype in the second week post-transplantation (adjusted P = 0.016). Regarding clinical outcomes, acute rejection was significantly associated with human leukocyte antigen mismatch (≥3 alleles; OR = 12.14, 95% CI 1.76, 525.21, P = 0.019 after correction for multiple testing). Graft recipients from deceased donors showed higher incidende of delayed graft function (OR 7.15, 95% CI 2.23, 30.46, adjusted P = 0.0008) and a lower estimated glomerular filtration rate at discharge (P = 0.0001). Tested CYP3A4 or CYP3A5 variants did not show any effects on clinical outcome parameters. ABCB1 variants did neither impact on pharmacokinetics nor on clinical endpoints. Conclusion: At our transplantation center, both CYP3A5*3 and, to a lesser extent, CYP3A4*22 affect tacrolimus pharmacokinetics early after onset of therapy with consequences for steady-state treatment in routine clinical practice.

Renal Allograft Rejection: Noninvasive Ultrasound- and MRI-Based Diagnostics

To date, allogeneic kidney transplantation remains the best available therapeutic option for patients with end-stage renal disease regarding overall survival and quality of life. Despite the advancements in immunosuppressive drugs and protocols, episodes of acute allograft rejection, a sterile inflammatory process, continue to endanger allograft survival. Since effective treatment for acute rejection episodes is available, instant diagnosis of this potentially reversible graft injury is imperative. Although histological examination by invasive core needle biopsy of the graft remains the gold standard for the diagnosis of ongoing rejection, it is always associated with the risk of causing substantial graft injury as a result of the biopsy procedure itself. At the same time, biopsies are not immediately feasible for a considerable number of patients taking anticoagulants due to the high risk of complications such as bleeding and uneven distribution of pathological changes within the graft. This can result in the wrong diagnosis due to the small size of the tissue sample taken. Therefore, there is a need for a tool that overcomes these problems by being noninvasive and capable of assessing the whole organ at the same time for specific and fast detection of acute allograft rejection. In this article, we review current state-of-the-art approaches for noninvasive diagnostics of acute renal transplant inflammation, i.e., rejection. We especially focus on nonradiation-based methods using magnetic resonance imaging (MRI) and ultrasound.

Composite tissue allotransplantation: opportunities and challenges

Vascularized composite allotransplants (VCAs) have unique properties because of diverse tissue components transplanted en mass as a single unit. In addition to surgery, this type of transplant also faces enormous immunological challenges that demand a detailed analysis of all aspects of alloimmune responses, organ preservation, and injury, as well as the immunogenicity of various tissues within the VCA grafts to further improve graft and patient outcomes. Moreover, the side effects of long-term immunosuppression for VCA patients need to be carefully balanced with the potential benefit of a non-life-saving procedure. In this review article, we provide a comprehensive update on limb and face transplantation, with a specific emphasis on the alloimmune responses to VCA, established and novel immunosuppressive treatments, and patient outcomes.

Enhanced immunosuppression improves early allograft function in a porcine kidney transplant model of donation after circulatory death

It remains controversial whether renal allografts from donation after circulatory death (DCD) have a higher risk of acute rejection (AR). In the porcine large animal kidney transplant model, we investigated the AR and function of DCD renal allografts compared to the non-DCD renal allografts and the effects of increased immunosuppression. We found that the AR was significantly increased along with elevated MHC-I expression in the DCD transplants receiving low-dose immunosuppression; however, AR and renal function were significantly improved when given high-dose immunosuppressive therapy postoperatively. Also, high-dose immunosuppression remarkably decreased the mRNA levels of ifn-g, il-6, tgf-b, il-4, and tnf-a in the allograft at day 5 and decreased serum cytokines levels of IFN-g and IL-17 at day 4 and day 5 after operation. Furthermore, Western blot analysis showed that higher immunosuppression decreased phosphorylation of signal transducer and activator of transcription 3 and nuclear factor kappa-light-chain-enhancer of activated B cells-p65, increased phosphorylation of extracellular-signal-regulated kinase, and reduced the expression of Bcl-2-associated X protein and caspase-3 in the renal allografts. These results suggest that the DCD renal allograft seems to be more vulnerable to AR; enhanced immunosuppression reduces DCD-associated AR and improves early allograft function in a preclinical large animal model.

The level of intracellular tacrolimus in T cell is affected by CD44+ABCB1+activities triggered by inflammation

Rejection is an important issue in kidney transplant. Although with adequate trough level of tacrolimus, acute rejection occurs, and we are focused on these cases. We hypothesized that the lower concentration of tacrolimus in the peripheral blood mononuclear cell would be a cause of rejection; in this regard, we describe ABCB1, which regulates intracellular concentration of tacrolimus. The effect of inflammation on the intracellular concentration of tacrolimus was evaluated, as was the association between that concentration and ABCB1 and CD44 activities. Seven kidney recipients experiencing acute rejection were prospectively enrolled. Both the whole blood concentration of tacrolimus and intracellular concentration of tacrolimus were measured at the time of enrollment and after stabilization. A human T lymphoblastoid cell line (Jurkat T cell) was treated with various concentrations of tacrolimus for 21 h and then stimulated for 3 h. The levels of mRNA interleukin-2, interleukin-8, and interferon-γ decreased dose dependently by tacrolimus. Furthermore, a fluorescence-activated cell sorter was used to count cells expressing CD44 and ABCB1; changes in intracellular concentration of tacrolimus were explored after tacrolimus treatment and stimulation. Also, B6 splenocytes were tested in the same manner as previous Jurkat T cell experiments. The tacrolimus ratio of three patients was lower at the time of acute rejection than when patients were stabilized. In vitro, the intracellular concentration of tacrolimus decreased after stimulation. Under the same conditions, CD44+ABCB1+cells increased in proportion on tacrolimus treatment and stimulation. This work supports the hypothesis that inflammation reduces the intracellular tacrolimus level, possibly via drug efflux mediated by CD44+ABCB1+and inflammation could lead to acute rejection.

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.

Dissociation of C-Reactive Protein Localizes and Amplifies Inflammation: Evidence for a Direct Biological Role of C-Reactive Protein and Its Conformational Changes

C-reactive protein (CRP) is a member of the pentraxin superfamily that is widely recognized as a marker of inflammatory reactions and cardiovascular risk in humans. Recently, a growing body of data is emerging, which demonstrates that CRP is not only a marker of inflammation but also acts as a direct mediator of inflammatory reactions and the innate immune response. Here, we critically review the various lines of evidence supporting the concept of a pro-inflammatory “CRP system.” The CRP system consists of a functionally inert circulating pentameric form (pCRP), which is transformed to its highly pro-inflammatory structural isoforms, pCRP* and ultimately to monomeric CRP (mCRP). While retaining an overall pentameric structure, pCRP* is structurally more relaxed than pCRP, thus exposing neoepitopes important for immune activation and complement fixation. Thereby, pCRP* shares its pro-inflammatory properties with the fully dissociated structural isoform mCRP. The dissociation of pCRP into its pro-inflammatory structural isoforms and thus activation of the CRP system occur on necrotic, apoptotic, and ischemic cells, regular β-sheet structures such as β-amyloid, the membranes of activated cells (e.g., platelets, monocytes, and endothelial cells), and/or the surface of microparticles, the latter by binding to phosphocholine. Both pCRP* and mCRP can cause activation of platelets, leukocytes, endothelial cells, and complement. The localization and deposition of these pro-inflammatory structural isoforms of CRP in inflamed tissue appear to be important mediators for a range of clinical conditions, including ischemia/reperfusion (I/R) injury of various organs, cardiovascular disease, transplant rejection, Alzheimer’s disease, and age-related macular degeneration. These findings provide the impetus to tackle the vexing problem of innate immunity response by targeting CRP. Understanding the “activation process” of CRP will also likely allow the development of novel anti-inflammatory drugs, thereby providing potential new immunomodulatory therapeutics in a broad range of inflammatory diseases.

Genetics of acute rejection after kidney transplantation

Treatment of acute rejection (AR) following kidney transplantation has improved in recent years, but there are still limitations to successful outcomes. This review article covers literature in regard to recipient and donor genetics of AR kidney and secondarily of liver allografts. Many candidate gene and some genome-wide association studies (GWASs) have been conducted for AR in kidney transplantation. Genetic associations with AR in kidney and liver are mostly weak, and in most cases, the associations have not been reproducible. A limitation in the study of AR is the lack of sufficiently large populations that account for population stratification to study the AR phenotype which in this era occurs in <10% of transplants. Furthermore, the AR phenotype has been difficult to define and the definitions of classifications have evolved over time. Literature related to the pharmacogenomics of tacrolimus is robust and has been validated in many studies. Associations between gene expression and AR are emerging as markers of outcomes and AR classification. In the future, combinations of pretransplant genotype for AR risk prediction, genotype-based immune suppressant dosing, and pharmacogenomic markers to select AR maintenance or treatment and expression markers from biopsies may provide valuable clinical tools for guiding treatment.

Comparative top down proteomics of peripheral blood mononuclear cells from kidney transplant recipients with normal kidney biopsies or acute rejection

Recent studies utilizing transcriptomics, metabolomics, and bottom up proteomics have identified molecular signatures of kidney allograft pathology. Although these results make significant progress toward non-invasive differential diagnostics of dysfunction of a transplanted kidney, they provide little information on the intact, often modified, protein molecules present during progression of this pathology. Because intact proteins underpin diverse biological processes, measuring the relative abundance of their modified forms promises to advance mechanistic understanding, and might provide a new class of biomarker candidates. Here, we used top down proteomics to inventory the modified forms of whole proteins in peripheral blood mononuclear cells (PBMCs) taken at the time of kidney biopsy for 40 kidney allograft recipients either with healthy transplants or those suffering acute rejection. Supported by gas-phase fragmentation of whole protein ions during tandem mass spectrometry, we identified 344 proteins mapping to 2905 distinct molecular forms (proteoforms). Using an initial implementation of a label-free approach to quantitative top down proteomics, we obtained evidence suggesting relative abundance changes in 111 proteoforms between the two patient groups. Collectively, our work is the first to catalog intact protein molecules in PBMCs and suggests differentially abundant proteoforms for further analysis.

Association of IL1 beta gene polymorphism and allograft functions in renal transplant recipients :a case control study from Kashmir Valley

BACKGROUND

Cytokines have been found to be the important mediators during renal graft outcome. Therefore, we designed this study to investigate the role of recipients' IL-1 β promoter (-511) and IL-1 β exon-5 (+3954) polymorphisms with the risk of graft outcome.

METHODOLOGY

We enrolled one hundred recipients of living-related renal transplants together with the age and sex matched controls from the healthy population not having any renal abnormality for this study. Genotype frequencies of the IL-1 β promoter (-511) and IL-1 β exon-5 (+3954) were analyzed using PCR-RFLP technique.

RESULTS

Our results revealed significant differences in the healthy control group and patient group in IL 1β +3954 (p < 0.001). The frequency of variant type TT genotype was higher in RE group as compared to SGF and showed 4 fold risk of rejection (OR = 4.54, p < 0.069) although p value was not significant. The frequency of wild type CC genotype and CT was not significant (p value 0.89 and 0.74 respectively).

CONCLUSION

Our findings suggest that there is a prevalence of mutated allele of IL-1 gene cluster in our population, which may be responsible for renal dysfunction.

Steroid withdrawal after renal transplantation: a retrospective cohort study

BACKGROUND

Immunosuppressive regimens in renal transplantation frequently contain corticosteroids, but many centers withdraw steroids as a consequence of unwanted side effects of steroids. The optimal timing to withdraw steroids after transplantation, however, remains unclear. The aim of this study was to determine an optimal time point following kidney transplantation that is associated with reduced mortality without jeopardizing the allograft to allow safe discontinuation of steroids.

METHODS

We conducted a retrospective cohort study and computed a concatenated landmark-stratified Cox supermodel to estimate hazard ratios and 95% confidence intervals for mortality and graft loss using dynamic propensity score matching to adjust for confounding by indication.

RESULTS

A total of 6070 first kidney transplant recipients in the Austrian Dialysis and Transplant Registry who were transplanted between 1990 and 2012 were evaluated and classified according to steroid treatment status throughout follow-up after kidney transplantation; 2142 patients were withdrawn from steroids during the study period. Overall, 1131 patients lost their graft and 821 patients in the study cohort died. Steroid withdrawal within 18 months after transplantation was associated with an increased rate of graft loss compared to steroid maintenance during that time (6 months after transplantation: HR = 1.8; 95% CI, 1.3 to 2.6; 18 months after transplantation: HR = 1.3; 95% CI, 1.1 to 1.6; 24 months after transplantation: HR = 1.2; 95% CI, 0.9 to 1.5), while mortality was not different between groups.

CONCLUSIONS

Our findings suggest that steroid withdrawal after anti-IL-2 induction in the first 18 months after transplantation is associated with an increased risk of allograft loss.

Association Interleukin-4 and Interleukin-4 Receptor Gene Polymorphism and Acute Rejection and Graft Dysfunction After Kidney Transplantation

BACKGROUND

Cytokine genotypes have previously been studied in patients undergoing solid organ transplantation; certain polymorphisms have been implicated in the development of acute rejection (AR) and graft dysfunction (GD). Allograft outcomes determined, in part, by alloimmune responses is mainly mediated by T-cell responses, activated and driven by cytokines. Interleukin-4 (IL-4) is one such cytokine, which exerts its biological effects through binding to the IL-4 receptor (IL-4R) complex on target cells. In the present study, we investigated whether polymorphisms of the IL-4 and/or IL-4R gene were associated with susceptibility to acute AR and GD after kidney transplantation.

METHODS

We analyzed 2 single nucleotide polymorphism (SNPs) of IL-4 (rs2243250 and rs2070874) and 3 SNPs of IL-4R (rs1801275, rs2107356, and rs1805010) in 344 kidney transplant recipients. These patients included 62 of whom had developed AR and 215 of whom had GD in 1 year after kidney transplantation.

RESULTS

The AR group included 62 patients (45 men and 17 women). There was a statistically significant difference in the male-to-female ratio and the use of tacrolimus in the AR group. The GD group included 215 patients. Patients who developed GD were more likely to be older and have an underlying cause of end-stage renal disease that was unknown compared with patients who did not have GD, the cause of which was typically known. Among the SNPs examined, 1 of the SNPs in the IL-4R gene (ie, rs1801275) showed a statistical association with AR (co-dominant model, P = .061; dominant model, P = .019; and log-addictive model, P = .029). In addition, 1 of the IL-4R SNPs (ie, rs2107356) was statistically associated with GD (dominant model, P = .034). No significant difference in the IL-4 genotype was observed between the AR/GD and non-AR/non-GD subjects.

CONCLUSIONS

One IL-4R gene polymorphism (rs1801275) was associated with AR. In addition, a separate IL-4R SNP (rs2107356) was statistically associated with GD after kidney transplantation.

Randomized trial of rATg/Daclizumab vs. rATg/Alemtuzumab as dual induction therapy in renal transplantation: Results at 8years of follow-up

Our goal in using dual induction therapy is to bring the kidney transplant recipient closer (through more effectively timed lymphodepletion) to an optimally immunosuppressed state. Here, we report long-term results of a prospective randomized trial comparing (Group I,N=100) rATG/Dac (3 rATG, 2 Dac doses) vs. (Group II,N=100) rATG/Alemtuzumab(C1H) (1 dose each), using reduced tacrolimus dosing, EC-MPS, and early corticosteroid withdrawal. Lower EC-MPS dosing was targeted in Group II to avoid severe leukopenia. Median follow-up was 96mo post-transplant. There were no differences in 1st BPAR (including borderline) rates: 10/100 vs. 9/100 in Groups I and II during the first 12mo(P=0.54), and 20/100 vs. 20/100 throughout the study(P=0.90). Equally favorable renal function was maintained in both treatment arms(N.S.). While not significant, more patients in Group II experienced graft loss, 25/100 vs. 18/100 in Group I(P=0.23). Actuarial patient/graft survival at 96mo was 92%/83% vs. 85%/73% in Groups I and II(N.S.). DWFG-due-to-infection(N.S.), EC-MPS withholding-due-to-leukopenia during the first 2mo(P=0.03), and incidence of viral infections(P=0.09) were higher in Group II, whereas EC-MPS withholding-due-to-GI symptoms was higher in Group I(P=0.009). No other adverse event differences were observed. While long-term anti-rejection and renal function efficacy were demonstrated in both treatment arms, slight over-immunosuppression of Group II patients occurred.

Use of Basiliximab and Daclizumab in Kidney Transplantation

Kidney transplantation represents a major medical victory in patients with whom dialysis and medical therapy have failed. To increase survival rates and optimize the use of limited organs, both patient care and immunosuppression therapy must be improved. Reduction in rejection episodes or severity of rejection may ultimately improve long-term allograft survival. Traditional engineered monoclonal antibodies have been associated with severe cytokine release reactions and an increased risk of opportunistic infections. Basiliximab and daclizumab are chimeric and humanized monoclonal antibodies that inhibit thymus-dependent lymphocyte proliferation. Interleukin 2 also affects the proliferation of natural killer cells, macrophages and monocytes, bursa-equivalent lymphocytes, epidermal dendritic cells, and lymphokine-activated killer cells. Interleukin-2 receptor antagonists have been shown to reduce the incidence of acute rejection without increasing the incidence of opportunistic infections or malignancy. Further studies are needed to evaluate the overall effect of these agents on long-term patient and allograft survival.

Profiling risk for acute rejection in kidney transplantation: recipient age is a robust risk factor

Careful management of immunosuppression is paramount to prevent acute rejection in kidney transplantation. We studied a cohort of 139,875 kidney transplant recipients from the Organ Procurement and Transplantation Network (OPTN) database between 2002 and 2013. We confirmed the analysis with a cohort of 35,277 who received thymoglobulin induction with tacrolimus maintenance, and a third cohort of 12,161 recipients who received basiliximab induction with tacrolimus maintenance. We performed multivariate logistic regression analyses on data from all three cohorts and identified independent risk factors for treated acute rejection at 1 year. Recipient age was a robust risk factor for rejection in all three cohorts in a dose response pattern. Young age (18-25 years) was among the strongest risk factors for rejection in all three cohorts; thymoglobulin cohort: OR 1.87 (1.59-2.19); basiliximab cohort: OR 2.41 (1.89-3.05); and inclusive cohort: OR 1.97 (1.83-2.12). The opposite was true for old age (65-69 years); thymoglobulin cohort: OR 0.69 (0.59-0.81); basiliximab cohort: OR 0.77 (0.62-0.96); and inclusive cohort: OR 0.75 (0.70-0.80). This study is unique because it is the largest and most comprehensive multivariate analysis that demonstrates recipient age is a robust risk factor for acute rejection in an inverse dose response pattern.

Renal graft survival according to Banff 2013 classification in indication biopsies

INTRODUCTION

The impact of acute rejection in kidney graft survival is well known, but the prognosis of other diagnoses is uncertain. We evaluated the frequency and impact on graft survival of different diagnostic categories according to the Banff 2013 classification in a cohort of renal transplant recipients.

MATERIAL AND METHODS

Retrospective study of 495 renal biopsies by indication in 322 patients from 1990-2014. Two independent observers reviewed the histological reports, reclassifying according to the Banff 2013 classification.

RESULTS

Of 495 biopsies, 28 (5.7%) were not diagnostic. Of the remaining 467, 10.3% were «normal» (category 1), 19.6% antibody-mediated changes (category 2), 5.9% «borderline» changes (category 3), 8.7% T-cell-mediated rejection (category 4), 23.4% interstitial fibrosis/tubular atrophy (IFTA) (category 5) and 26.5% with other diagnoses (category 6). As time after transplantation increases, diagnoses of categories 1, 3 and 4 decrease, while categories 5 and 2 increase. Worse graft survival with category 2 diagnosis was observed (45% at 7.5 years, HR 4.29 graft loss [95% CI, 2.39-7.73]; P≤.001, compared to category 1). Grafts with «unfavourable histology» (chronic antibody-mediated rejection, moderate-severe IFTA) presented worse survival that grafts with «favourable histology» (normal, acute tubular necrosis, mild IFTA).

CONCLUSIONS

The Banff 2013 classification facilitates a histological diagnosis in 95% of indication biopsies. While diagnostic category 6 is the most common, a change in the predominant histopathology was observed according to time elapsed since transplantation. Antibody-mediated changes are associated with worse graft survival.

Acute Rejection Clinically Defined Phenotypes Correlate With Long-term Renal Allograft Survival

BACKGROUND

Classification of acute rejection (AR) based on etiology and timing may provide a means for enhancing therapeutic results and allograft survival. This study evaluated graft and patient survival after the first AR episodes among kidney transplant recipients with an early or late antibody-mediated rejection (AMR), acute cellular rejection (ACR) or mixed AR (MAR).

METHODS

A prospective institutional review board-approved database was queried to identify biopsy-proven first AR episodes occurring from January 2005 to October 2012. The ACR was defined by Banff criteria; borderline AR was excluded. The AMR was defined as 3 of 4 criteria: renal dysfunction, donor specific antibody, C4d positivity on biopsy, and histological changes. The MAR met criteria for both ACR and AMR. Early AR occurred within six months post-transplant. AR episodes were then assigned to 1 of the 6 categories--early AMR, early ACR, early MAR, late AMR, late ACR, and late MAR.

RESULTS

One hundred eighty-two kidney transplant recipients identified with a first AR episode. Mean follow-up was 773 days (± 715 days). No difference was observed in patient survival. Death-censored graft survival was 84%. Death-censored graft loss was higher with late versus early AMR (P = 0.01) and late versus early ACR (P = 0.03), but not late versus early MAR (P = 0.3).

CONCLUSIONS

The AR type demonstrated a hierarchy for graft survival with ACR better than MAR better than AMR, which persisted for both early and late AR. Improvement in long-term results of AR may require development of specific treatment for individual AR types.

Validation study of peripheral blood diagnostic test for acute rejection in kidney transplantation

BACKGROUND

Diagnosing acute rejection (AR) in kidney transplant recipients typically requires an invasive kidney biopsy. A previous study has suggested that expression of five genes in peripheral blood can indicate the presence of AR in American pediatric kidney transplant recipients. This study aims to validate if these five genes are also useful to diagnose AR in Korean adult kidney transplant patients.

METHODS

Blood samples were collected from 143 patients (39 biopsy-proven AR, 84 stable patients, and 20 other graft injuries) at an average of 9 months posttransplantation and performed real-time PCR for five-gene biomarkers (DUSP1, NKTR, MAPK9, PSEN1, and PBEF1).

RESULTS

Patients with acute cellular rejection (ACR) had a significantly decreased level of MAPK9 and a significantly increased level of PSEN1 when compared with controls and also with patients with other graft injury (OGI). In multivariate logistic regression analysis, for discrimination between ACR and OGI, an excellent diagnostic accuracy was observed in the gene sets but five-gene set generated a higher AUC than two-gene set. With clinical variables combined to these gene sets, the diagnostic accuracy increased in both five-gene set and two-gene set.

CONCLUSIONS

These results support the validity of 5 gene-set for the prediction of AR in Asian adult kidney transplant recipients and suggest the promising role of the peripheral blood gene test in the diagnosis of AR in kidney transplantation.

Robotic renal transplantation: Current status

INTRODUCTION:

Kidney transplantation (KT) has traditionally been performed by open renal transplantation, but recently, a few groups including our own have described a minimally invasive approach to KT. We aim to discuss the current status of robotic kidney transplantation (RKT) and describe our technique of RKT with regional hypothermia.

MATERIAL AND METHODS:

We used the search terms “minimally invasive” OR “robotic” OR “robot assisted” AND “kidney transplantation.” Papers written in English and concerning technical and/or clinical outcomes following minimally invasive kidney transplantation were selected. Three hundred and eighteen unique articles were retrieved and nine were relevant. Comparative outcomes data following RKT with regional hypothermia versus open KT (OKT) from our own group were also included.

FINDINGS:

Nine papers, so far, have evaluated the role of robotic approach in KT and have conclusively established the feasibility, safety, and reproducibility of RKT, although these studies have been performed by experienced robotic surgeons/teams. The contemporary published series note that rejection rates were similar in RKT and OKT patients. Mean serum creatinine at 6 months in RKT and OKT patients was equivalent, across the three series. Most of the studies also note a dramatic reduction in the wound-related complication rates.

CONCLUSION:

RKT appears to be a safe surgical alternative to the standard open approach of KT. RKT is associated with reduced postoperative pain, analgesic requirement, and better cosmesis. RKT, although in its infancy, appears to be associated with lower complication rates.

Clinicopathological characteristics and effect of late acute rejection on renal transplant outcomes

BACKGROUND

Late acute rejection (LAR) has been associated with inferior kidney allograft outcomes.

METHODS

We retrospectively evaluated 355 episodes of biopsy-confirmed LAR in a cohort of 5758 kidney transplants performed between 1998 and 2008. Estimated glomerular filtration rate was obtained before, at, and after each LAR episode as well as histology and treatment. Associations of LAR with subsequent death or graft loss were estimated with Cox proportional regression analysis.

RESULTS

A total of 215 patients had 1 episode, 57 had 2 episodes, and 13 had 3 episodes of LAR. Rates of LAR-free survival were 97.4% at 1 year and 93.7% at 5 years. Estimated glomerular filtration rate decreased after each episode of LAR (56±21 vs. 44±18 vs. 36±11 mL/min/1.73 m, P<0.01). The majority of rejections were Banff IA or less, but the chronicity scores as well as plasma cell infiltrates increased after each LAR. All patients requiring dialysis lost their grafts. In a multivariable analysis, the severity of histological score (risk ratio [RR], 3.5; 95% confidence interval [CI], 1.58-7.87; P<0.001), the need for dialysis at LAR (RR, 3.31; 95% CI, 1.44-7.59; P<0.001), and treatment with methylprednisolone (RR, 2.31; 95% CI, 1.07-4.94; P=0.03) were independently associated with graft loss at 5 years, whereas tacrolimus and mycophenolate use was associated with reduced risk (RR, 0.46; 95% CI, 0.25-0.87; P<0.001).

CONCLUSIONS

The prevalence and recurrence of LAR are considerable and associated with increased incidence of graft loss. Patients who need dialysis during LAR should be carefully evaluated owing to the high prevalence of graft failure.

Disappearance of T Cell-Mediated Rejection Despite Continued Antibody-Mediated Rejection in Late Kidney Transplant Recipients

The prevalent renal transplant population presents an opportunity to observe the adaptive changes in the alloimmune response over time, but such studies have been limited by uncertainties in the conventional biopsy diagnosis of T cell-mediated rejection (TCMR) and antibody-mediated rejection (ABMR). To circumvent these limitations, we used microarrays and conventional methods to investigate rejection in 703 unselected biopsies taken 3 days to 35 years post-transplant from North American and European centers. Using conventional methods, we diagnosed rejection in 205 biopsy specimens (28%): 67 pure TCMR, 110 pure ABMR, and 28 mixed (89 designated borderline). Using microarrays, we diagnosed rejection in 228 biopsy specimens (32%): 76 pure TCMR, 124 pure ABMR, and 28 mixed (no borderline). Molecular assessment confirmed most conventional diagnoses (agreement was 90% for TCMR and 83% for ABMR) but revealed some errors, particularly in mixed rejection, and improved prediction of failure. ABMR was strongly associated with increased graft loss, but TCMR was not. ABMR became common in biopsy specimens obtained >1 year post-transplant and continued to appear in all subsequent intervals. TCMR was common early but progressively disappeared over time. In 108 biopsy specimens obtained 10.2-35 years post-transplant, TCMR defined by molecular and conventional features was never observed. We conclude that the main cause of kidney transplant failure is ABMR, which can present even decades after transplantation. In contrast, TCMR disappears by 10 years post-transplant, implying that a state of partial adaptive tolerance emerges over time in the kidney transplant population.

Noninvasive allograft imaging of acute rejection: evaluation of (131)I-anti-CXCL10 mAb

The purpose of this study was to investigate the use of iodine-131-labeled anti-CXCL10 mAb as tracer targeted at CXCL10 to detect acute rejection (AR) with mice model. Expression of CXCL10 was proved by RT-PCR, ELISA, and immunochemistry staining. All groups were submitted to whole-body autoradioimaging and ex vivo biodistribution studies after tail vein injection of (131)I-anti-CXCL10 mAb. The highest concentration/expression of CXCL10 was detected in allograft tissue compared with allograft treated with tacrolimus and isograft control. Tacrolimus could obviously inhibit the rejection of allograft. Allograft could be obviously imaged at all checking points, much clearer than the other two groups. The biodistribution results showed the highest uptake of radiotracer in allograft. T/NT (target/nontarget) ratio was 4.15 ± 0.25 at 72 h, apparently different from allograft treated with tacrolimus (2.29 ± 0.10), P < 0.05. These data suggest that CXCL10 is a promising target for early stage AR imaging and (131)I-CXCL10 mAb can successfully image AR and monitor the effect of immunosuppressant.

Delayed-onset cytomegalovirus disease coded during hospital readmission after kidney transplantation

BACKGROUND

Use of prophylactic anti-CMV therapy for 3 to 6 months after kidney transplantation can result in delayed-onset CMV disease. We hypothesized that delayed-onset CMV disease (occurring >100 days posttransplant) occurs more commonly than early-onset CMV disease and that it is associated with death.

METHODS

We assembled a retrospective cohort of 15,848 adult kidney transplant recipients using 2004 to 2010 administrative data from the California and Florida Healthcare Cost and Utilization Project State Inpatient Databases. We identified demographic data, comorbidities, CMV disease coded during readmission, and inpatient death. We used multivariate Cox proportional hazards modeling to determine risk factors for delayed-onset CMV disease and inpatient death.

RESULTS

Delayed-onset CMV disease was identified in 4.0%, and early-onset CMV disease was identified in 1.2% of the kidney transplant recipients. Risk factors for delayed-onset CMV disease included previous transplant failure or rejection (HR 1.4) and residence in the lowest-income ZIP codes (HR 1.2). Inpatient death was associated with CMV disease occurring 101 to 365 days posttransplant (HR 1.5), CMV disease occurring greater than 365 days posttransplant (HR 2.1), increasing age (by decade: HR 1.5), nonwhite race (HR 1.2), residence in the lowest-income ZIP codes (HR 1.2), transplant failure or rejection (HR 3.2), previous solid organ transplant (HR 1.7), and several comorbidities.

CONCLUSION

These data showed that delayed-onset CMV disease occurred more commonly than early-onset CMV disease and that transplant failure or rejection is a risk factor for delayed-onset CMV disease. Further research should be done to determine if delayed-onset CMV disease is independently associated with death.

Effect of mycophenolate mofetil on progression of interstitial fibrosis and tubular atrophy after kidney transplantation: a retrospective study

OBJECTIVES

Chronic transplant dysfunction after kidney transplantation is a major reason of kidney graft loss and is caused by immunological and non-immunological factors. There is evidence that mycophenolate mofetil (MMF) may exert a positive effect on renal damage in addition to immunosuppression, by its direct antifibrotic properties. The aim of our study was to retrospectively investigate the role of MMF doses on progression of chronic allograft dysfunction and fibrosis and tubular atrophy (IF/TA).

SETTING

Retrospective, cohort study.

PARTICIPANTS

Patients with kidney transplant in a tertiary care institution. This is a retrospective cohort study that included 79 patients with kidney and kidney-pancreas transplantation. Immunosuppression consisted of anti-interleukin 2 antibody induction, MMF, a calcineurin inhibitor±steroids.

PRIMARY OUTCOME MEASURES

An association of average MMF doses over 1 year post-transplant with progression of interstitial fibrosis (Δci), tubular atrophy (Δct) and estimated-creatinine clearance (eCrcl) at 1 year post-transplant was evaluated using univariate and multivariate analyses.

RESULTS

A higher average MMF dose was significantly independently associated with better eCrcl at 1 year post-transplant (b=0.21±0.1, p=0.04). In multiple regression analysis lower Δci (b=-0.2±0.09, p=0.05) and Δct (b=-0.29±0.1, p=0.02) were independently associated with a greater average MMF dose. There was no correlation between average MMF doses and incidence of acute rejection (p=0.68).

CONCLUSIONS

A higher average MMF dose over 1 year is associated with better renal function and slower progression of IF/TA, at least partly independent of its immunosuppressive effects.

Bim regulates alloimmune-mediated vascular injury through effects on T-cell activation and death

OBJECTIVE

Bim is a proapoptotic Bcl-2 protein known to downregulate immune responses and to also be required for antigen-induced T-cell activation. However, it is not known how the effect of Bim on these offsetting processes determines the outcome of allogeneic immune responses. We have defined the role of Bim in regulating alloantigen-driven T-cell responses in a model of vascular rejection.

APPROACH AND RESULTS

Bim was required for proliferation of CD4 and CD8 T cells, and for interleukin-2 production, in T cells stimulated with alloantigen in vitro. Moreover, a partial reduction in Bim expression was sufficient to attenuate T-cell activation, whereas a complete elimination of Bim was required to prevent CD4 T-cell death in response to cytokine withdrawl. When alloimmune-mediated vascular rejection was examined using an aortic interposition model, there was significantly less intimal thickening in Bim(+/-), but not Bim(-/-), graft recipients. T-cell proliferation in response to allograft arteries was significantly reduced in both Bim(+/-) and Bim(-/-) mice, but cell death was attenuated only in Bim(-/-) animals.

CONCLUSIONS

Bim controls both T-cell activation and death in response to alloantigen stimulation. These processes act cooperatively to determine the outcome of immune responses in allograft arteries.

Association between a TGFBR2 gene polymorphism (rs2228048, Asn389Asn) and acute rejection in Korean kidney transplantation recipients

Transforming growth factor-β (TGF-β) signaling transduction initiates TGF-β activation, resulting in activation of TGF-β receptor II (TGFBR2). Any quantitative and qualitative changes in TGFBR2 are expected to affect the TGF-β signaling pathway, which occupies a central position with respect to the regulation of cell growth, differentiation, apoptosis, immune reaction, angiogenesis and extracellular matrix formation. Recent studies have shown that TGF-β1 gene polymorphisms may confer susceptibility to early acute and chronic allograft rejection in kidney transplantation recipients. In this study, we assessed whether polymorphisms of the TGFBR2 gene were associated with susceptibility to kidney transplantation rejection. A total of 347 renal allograft recipients transplanted at three centers in Korea were analyzed. Three SNPs (rs764522, rs3087465, rs2228048) of the TGFBR2 gene were genotyped from genomic DNA with direct sequencing. Multiple logistic regression models (codominant, dominant, recessive, and log-additive) were performed to evaluate odds ratios (ORs), 95% confidence intervals (CIs), and p-values. A total of 63 patients (18%) developed acute rejection (AR). There were no significant differences in age, sex, number of HLA mismatches, cause of renal failure, or immunosuppressant regimen between the AR and non-AR group. The synonymous SNP rs2228048 was significantly associated with AR (p = 0.020 in recessive model, and p = 0.036 in log-additive model. The allele frequencies of rs2228048 were different between the AR and non-AR group (p = 0.026). These results suggest that the synonymous TGFBR2 gene SNP rs2228048 may be associated with the development of AR in Korean kidney transplantation recipients. Authors Yeong-Hoon Kim and Tae Hee Kim contributed equally to this work and are considered co-first authors.