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Objectives: Rejection remains the most important factor limiting the survival of transplanted kidneys. Although a pathological biopsy of the transplanted kidney is the gold standard for diagnosing rejection, its limitations prevent it from being used as a routine monitoring method. Recently, peripheral blood lymphocyte subpopulation testing has become an important means of assessing the body's immune system, however, its application value and strategy in the field of kidney transplantation need further exploration. Additionally, the development and utilization of routine test parameters are also important methods for exploring diagnostic strategies and predictive models for kidney transplant diseases. This study aims to explore the correlation between peripheral blood lymphocyte subpopulations and T cell-mediated rejection (TCMR) and antibody-mediated rejection (ABMR), as well as their diagnostic value, in conjunction with routine blood tests., Methods: A total of 154 kidney transplant recipients, who met the inclusion and exclusion criteria and were treated at the Second Xiangya Hospital of Central South University from January to December, 2021, were selected as the study subjects. They were assigned into a stable group, a TCMR group, and an ABMR group, based on the occurrence and type of rejection. The basic and clinical data of these recipients were retrospectively analyzed and compared among the 3 groups. The transplant kidney function, routine blood tests, and peripheral blood lymphocyte subpopulation data of the TCMR group and the ABMR group before rejection treatment were compared with those of the stable group., Results: The stable, TCMR group, and ABMR group showed no statistically significant differences in immunosuppressive maintenance regimens or sources of transplanted kidneys (all P >0.05). However, the post-transplant duration was significantly longer in the ABMR group compared with the stable group ( P <0.001) and the TCMR group ( P <0.05). Regarding kidney function, serum creatinine levels in the ABMR group were higher than in the stable group and the TCMR group (both P <0.01), with the TCMR group also showing higher levels than the stable group ( P <0.01). Both TCMR and ABMR groups had significantly higher blood urea nitrogen levels than the stable group ( P <0.01), with no statistically significant difference between TCMR and ABMR groups ( P >0.05). The estimated glomerular filtration rate (eGFR) was lower in both TCMR and ABMR groups compared with the stable group (both P <0.01). In routine blood tests, the ABMR group had lower hemoglobin, red blood cell count, and platelet count than the stable group (all P <0.05). The TCMR group had higher neutrophil percentage ( P <0.05) and count ( P <0.05) than the stable group, and the ABMR group had a higher neutrophil percentage than the stable group ( P <0.05). The eosinophil percentage and count in the TCMR group were lower than in the stable and ABMR groups (all P <0.05). Both TCMR and ABMR groups had lower basophil percentage and count, as well as lower lymphocyte percentage and count, compared with the stable group (all P <0.05). There were no significant differences in monocyte percentage and count among the 3 groups (all P >0.05). In lymphocyte subpopulations, the TCMR and ABMR groups had lower counts of CD45 + cells and T cells compared with the stable group (all P <0.05). The TCMR group also had lower counts of CD4 + T cells, NK cells, and B cells than the stable group (all P <0.05). There were no significant differences in the T cell percentage, CD4 + T cell percentage, CD8 + T cell percentage and their counts, CD4 + /CD8 + T cell ratio, NK cell percentage, and B cell percentage among the stable, TCMR, and ABMR groups (all P >0.05)., Conclusions: The occurrence of rejection leads to impaired transplant kidney function, accompanied by characteristic changes in some parameters of routine blood tests and peripheral blood lymphocyte subpopulations in kidney transplant recipients. The different characteristics of changes in some parameters of routine blood tests and peripheral blood lymphocyte subpopulations during TCMR and ABMR may help predict and diagnose rejection and differentiate between TCMR and ABMR.

Despite the growing interest in the role of regulatory B cells (Bregs) in autoimmunity, their distinct role and function in kidney transplant outcomes remain elusive. Here, we retrospectively analyzed the proportion of Bregs, transitional Bregs (tBregs) and memory Bregs (mBregs) and their capacity to produce IL-10 in non-rejected (NR) versus rejected (RJ) kidney transplant recipients. In the NR group, we observed a significant increase in the proportion of mBregs (CD19 + CD24 hi CD27 + ) but no difference in tBregs (CD19 + CD24 hi CD38 + ), as compared to the RJ group. We also observed a significant increase in IL-10-producing mBregs (CD19 + CD24 hi CD27 + IL-10 + ) in the NR group. As our group and others have previously reported a potential role of the human leukocyte antigen G (HLA-G) in human renal allograft survival, notably through IL-10, we then investigated possible crosstalk between HLA-G and IL-10 + mBregs. Our ex vivo data suggest a role of HLA-G in enhancing IL-10 + mBreg expansion upon stimulation, which further decreased CD3 + T cell proliferation capability. Using RNA-sequencing (RNA-seq), we identified potential key signaling pathways involved in HLA-G-driven IL-10 + mBreg expansion, such as the MAPK, TNF and chemokine signaling pathways. Together, our study highlights a novel HLA-G-mediated IL-10-producing mBreg pathway that may serve as a therapeutic target to improve kidney allograft survival., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 American Society for Histocompatibility and Immunogenetics. Published by Elsevier Inc. All rights reserved.)

There is growing interest in daratumumab in the solid organ transplant realm owing to the potential immunomodulatory effects on CD38-expressing cells, primarily plasma cells, as they have a key role in antibody production. In particular there is interest in use of daratumumab for desensitization and potential treatment for antibody-mediated rejection. However, ongoing investigation with daratumumab has shown potential immunologic concerns in vitro, with a significant increase in populations of CD4-positive cytotoxic T cells and CD8-positive helper T cells in both peripheral blood and bone marrow that could lead to acute T cell-mediated rejection in the solid organ transplant patient. To date, there are no published reports of an association with daratumumab use and T cell-mediated rejection in vivo. In this case report we present what is to our knowledge the first documented case of an early severe T cell-mediated rejection in a low-immunologic-risk living-donor kidney transplant recipient who received daratumumab for multiple myeloma maintenance prior to transplant., (Copyright © 2023 National Kidney Foundation, Inc. Published by Elsevier Inc. All rights reserved.)

Background: A genome-wide association study (GWAS) in kidney transplant recipients reported the association of two polymorphisms located in the PTPRO gene and upstream of the CCDC67 (DEUP1) gene with increased risk of acute T cell-mediated rejection (TCMR). We aimed at replicating the assessment of mentioned associations and additionally ascertaining the influence of treatment and clinical features of the patients., Methods: The polymorphisms, PTPRO-rs7976329 and CCDC67-rs10765602 were genotyped by TaqMan chemistry in 641 consecutive kidney transplant recipients. The diagnosis of rejection was confirmed by biopsy and categorized according to the Banff classification. Associations were evaluated by Chi-square test or Fisher's exact test when necessary and multivariate logistic regression., Results: Considering the GWAS study we only replicated the association of the PTPRO-rs7976329*C allele in the Banff grade < II subjects. However, the homozygous mutant genotypes of both polymorphism seemed to increase the risk of TCMR Banff grade < II in the overall cohort and after stratification by Thymoglobulin induction therapy. In the multivariate analysis, we confirmed the association of PTPRO-rs7976329 with TCMR Banff grade < II, independently of the Thymoglobulin induction therapy and of CCDC67-rs10765602 only in the group of patients not receiving Thymoglobulin induction therapy. No association of these polymorphisms with TCMR Banff grade ≥ II was observed in either the overall cohort or in the subgroups stratified by Thymoglobulin therapy., Conclusions: Our study shows that the increased risk of TCMR related to polymorphisms PTPRO-rs7976329 and CCDC67-rs10765602 previously reported in a GWAS was replicated only in homozygous patients who presented TCMR Banff grade < II and for the minor allele of either polymorphism., (© 2022. The Author(s) under exclusive licence to Italian Society of Nephrology.)

In this cross-sectional and longitudinal analysis of mapping the T-cell repertoire in kidney transplant recipients, we have investigated and validated T-cell clonality, immune repertoire chronology at rejection, and contemporaneous allograft biopsy quantitative tissue injury, to better understand the pathobiology of acute T-cell fraction, T-cell repertoire and antibody-mediated kidney transplant rejection. To follow the dynamic evolution of T-cell repertoire changes before and after engraftment and during biopsy-confirmed acute rejection, we sequenced 323 peripheral blood samples from 200 unique kidney transplant recipients, with (n=100) and without (n=100) biopsy-confirmed acute rejection. We report that patients who develop acute allograft rejection, have lower (p=0.01) T-cell fraction even before transplantation, followed by its rise after transplantation and at the time of acute rejection accompanied by high TCR repertoire turnover (p=0.004). Acute rejection episodes occurring after the first 6 months post-transplantation, and those with a component of antibody-mediated rejection, had the highest turnover; p=0.0016) of their T-cell repertoire. In conclusion, we validated that detecting repertoire changes in kidney transplantation correlates with post-transplant rejection episodes suggesting that T-cell receptor sequencing may provide recipient pre-transplant and post-transplant predictors of rejection risk., Competing Interests: Authors PF, JH, and HR were employed by Adaptive Biotechnologies. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Sigdel, Fields, Liberto, Damm, Kerwin, Hood, Towfighi, Sirota, Robins and Sarwal.)

The continuous evolution of metabolomics over the past two decades has stimulated the search for metabolic biomarkers of many diseases. Metabolomic data measured from urinary samples can provide rich information of the biological events triggered by organ rejection in pediatric kidney transplant recipients. With additional validation, metabolic markers can be used to build clinically useful diagnostic tools. However, there are many methodological steps ranging from data processing to modeling that can influence the performance of the resulting metabolomic classifiers. In this study we focus on the comparison of various classification methods that can handle the complex structure of metabolomic data, including regularized classifiers, partial least squares discriminant analysis, and nonlinear classification models. We also examine the effectiveness of a physiological normalization technique widely used in the clinical and biochemical literature but not extensively analyzed and compared in urine metabolomic studies. While the main objective of this work is to interrogate metabolomic data of pediatric kidney transplant recipients to improve the diagnosis of T cell-mediated rejection (TCMR), we also analyze three independent datasets from other disease conditions to investigate the generalizability of our findings., (© 2022 John Wiley & Sons Ltd.)

The prevalence and long-term impact of T cell-mediated rejection (TCMR) is poorly defined in the modern era of tacrolimus/mycophenolate-based maintenance therapy. This observational study evaluated 775 kidney transplant recipients with serial histology and correlated TCMR events with the risk of graft loss. After a ~30% incidence of a first Banff Borderline or greater TCMR detected on for-cause (17%) or surveillance (13%) biopsies, persistent (37.4%) or subsequent (26.3%) TCMR occurred in 64% of recipients on follow-up biopsies. Alloimmune risk categories based on the HLA-DR/DQ single molecule eplet molecular mismatch correlated with the number of TCMR events (p = .002) and Banff TCMR grade (p = .007). Both a first and second TCMR event correlated with death-censored and all-cause graft loss when adjusted for baseline covariates and other significant time-dependent covariates such as DGF and ABMR. Therefore, a substantial portion of kidney transplant recipients, especially those with intermediate and high HLA-DR/DQ molecular mismatch scores, remain under-immunosuppressed, which in turn identifies the need for novel agents that can more effectively prevent or treat TCMR., (© 2021 The Authors. American Journal of Transplantation published by Wiley Periodicals LLC on behalf of The American Society of Transplantation and the American Society of Transplant Surgeons.)

T cell-mediated rejection (TCMR) is an important rejection type in kidney transplantation, characterized by T cells and macrophages infiltration. The application of bioinformatic analysis in genomic research has been widely used. In the present study, Microarray data was analyzed to identify the potential diagnostic markers of TCMR in kidney transplantation. Cell-type identification by estimating relative subsets of RNA transcript (CIBERSORT) was performed to determine the distribution of immune cell infiltration in the pathology. Totally 129 upregulated differently expressed genes (DEGs) and 378 downregulated DEGs were identified. The GO and KEGG results demonstrated that DEGs were mainly associated with pathways and diseases involved in immune response. The intersection of the two algorithms (PPI network and LASSO) contains three overlapping genes (CXCR6, CXCL13 and FCGR1A). After verification in GSE69677, only CXCR6 and CXCL13 were selected. Immune cells Infiltration analysis demonstrated that CXCR6 and CXCL13 were positively correlated with gamma delta T cells ( p < 0.001), CD4 + memory activated T cells ( p < 0.001), CD8 + T cells ( p < 0.001) and M1 macrophages ( p = 0.006), and negatively correlated with M2 macrophages ( p < 0.001) and regulatory T cells ( p < 0.001). Immunohistochemical staining and image analysis confirmed the overexpression of CXCR6 and CXCL13 in human allograft TCMR samples. CXCR6 and CXCL13 could be diagnostic biomarkers of TCMR and potential targets for immunotherapy in patients with TCMR., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Zhou, Lu, Sun, Wang, Zheng, Hang, Zhang, Tan and Gu.)

Allograft rejection is defined as tissue injury in a transplanted allogeneic organ produced by the effector mechanisms of the adaptive alloimmune response. Effector T lymphocytes and IgG alloantibodies cause two different types of rejection that can occur either individually or simultaneously: T cell-mediated rejection (TCMR) and antibody-mediated rejection (ABMR). In TCMR, cognate effector T cells infiltrate the graft and orchestrate an interstitial inflammatory response in the kidney interstitium in which effector T cells engage antigen-presenting myeloid cells, activating the T cells, antigen-presenting cells, and macrophages. The result is intense expression of IFNG and IFNG-induced molecules, expression of effector T cell molecules and macrophage molecules and checkpoints, and deterioration of parenchymal function. The diagnostic lesions of TCMR follow, i.e. interstitial inflammation, parenchymal deterioration, and intimal arteritis. In ABMR, HLA IgG alloantibodies produced by plasma cells bind to the donor antigens on graft microcirculation, leading to complement activation, margination, and activation of NK cells and neutrophils and monocytes, and endothelial injury, sometimes with intimal arteritis. TCMR becomes infrequent after 5-10 years post-transplant, probably reflecting adaptive mechanisms such as checkpoints, but ABMR can present even decades post-transplant. Some rejection is triggered by inadequate immunosuppression and non-adherence, challenging the clinician to target effective immunosuppression even decades post-transplant., (© 2021. Springer Nature Switzerland AG.)

Background: This study aims to examine the association of LIM zinc finger domain containing 1 (LIMS1) genotype with allograft rejection in an independent kidney transplant cohort., Methods: We genotyped 841 kidney transplant recipients for the LIMS1 rs893403 variant by Sanger sequencing followed by polymerase chain reaction confirmation of the deletion. Recipients who were homozygous for the LIMS1 rs893403 genotype GG were compared with the AA/AG genotypes. The primary outcome was T cell-mediated or antibody-mediated rejection (TCMR or ABMR, respectively) and secondary outcome was allograft loss., Results: After a median follow-up of 11.4 years, the rate of TCMR was higher in recipients with the GG genotype (n = 200) compared with the AA/AG genotypes (n = 641) [25 (12.5%) versus 35 (5.5%); P = 0.001] while ABMR did not differ by genotype [18 (9.0%) versus 62 (9.7%)]. Recipients with the GG genotype had 2.4 times higher risk of TCMR than those who did not have this genotype [adjusted hazard ratio2.43 (95% confidence interval 1.44-4.12); P = 0.001]. A total of 189 (22.5%) recipients lost their allografts during follow-up. Kaplan-Meier estimates of 5-year (94.3% versus 94.4%; P = 0.99) and 10-year graft survival rates (86.9% versus 83.4%; P = 0.31) did not differ significantly in the GG versus AA/AG groups., Conclusions: Our study demonstrates that recipient LIMS1 risk genotype is associated with an increased risk of TCMR after kidney transplantation, confirming the role of the LIMS1 locus in allograft rejection. These findings may have clinical implications for the prediction and clinical management of kidney transplant rejection by pretransplant genetic testing of recipients and donors for LIMS1 risk genotype., (© The Author(s) 2021. Published by Oxford University Press on behalf of ERA-EDTA. All rights reserved.)

Background: Despite advances in immune suppression, kidney allograft rejection and other injuries remain a significant clinical concern, particularly with regards to long-term allograft survival. Evaluation of immune activity can provide information about rejection status and help guide interventions to extend allograft life. Here, we describe the validation of a blood gene expression classifier developed to differentiate immune quiescence from both T cell-mediated rejection (TCMR) and antibody-mediated rejection (ABMR)., Methods: A five-gene classifier (DCAF12, MARCH8, FLT3, IL1R2, and PDCD1) was developed on 56 peripheral blood samples and validated on two sample sets independent of the training cohort. The primary validation set comprised 98 quiescence samples and 18 rejection samples: seven TCMR, ten ABMR, and one mixed rejection. The second validation set included eight quiescence and 11 rejection samples: seven TCMR, two ABMR, and two mixed rejection. AlloSure donor-derived cell-free DNA (dd-cfDNA) was also evaluated., Results: AlloMap Kidney classifier scores in the primary validation set differed significantly between quiescence (median, 9.49; IQR, 7.68-11.53) and rejection (median, 13.09; IQR, 11.25-15.28), with P <0.001. In the second validation set, the cohorts were statistically different ( P =0.03) and the medians were similar to the primary validation set. The AUC for discriminating rejection from quiescence was 0.786 for the primary validation and 0.800 for the second validation. AlloMap Kidney results were not significantly correlated with AlloSure, although both were elevated in rejection. The ability to discriminate rejection from quiescence was improved when AlloSure and AlloMap Kidney were used together (AUC, 0.894)., Conclusion: Validation of AlloMap Kidney demonstrated the ability to differentiate between rejection and immune quiescence using a range of scores. The diagnostic performance suggests that assessment of the mechanisms of immunologic activity is complementary to allograft injury information derived from AlloSure dd-cfDNA. Together, these biomarkers offer a more comprehensive assessment of allograft health and immune quiescence., Competing Interests: E. Akalin reports receiving research funding from Angion, Astellas, CareDx, and National Institutes of Health (NIH); and having consultancy agreements with, receiving honoraria from, and serving as a scientific advisor for or member of CareDx and Immucor. D.C. Brennan reports having consultancy agreements with CareDx, Medeor, Sanofi, and Veloxis; receiving research funding from CareDx and Natera; receiving honoraria from CareDx, Sanofi, and Veloxis; and serving as a scientific advisor for or member of the editorial boards of Transplantation and UpToDate. D.C. Brennan, J.S. Bromberg, R. Weir, S. Bunnapradist, R. Delos Santos, and A. Langone report being DART investigators. J.S. Bromberg reports receiving research funding from Angion, Astellas, CareDx, Natera, Novartis, and Quark; having consultancy agreements with Eurofins; and serving as a scientific advisor for, or member of, NIH and Transplantation. S. Bunnapradist reports receiving research funding from Alexion, Angion, Astellas, CareDx, and Merck; receiving honoraria from Bristol Myers Squibb (BMS), CareDx, Sanofi, and Veloxis; serving on speakers bureau for BMS, CareDx, Natera, Veloxis, and Vitaeris; and having consultancy agreements with CareDx. R. Delos Santos reports having other interests/relationships with the American Society of Transplantation (AST) Conflict of Interest Committee and AST Transplant Nephrology Fellowship Training Accreditation Program Review Committee; receiving research funding from CareDx, Merck, and Veloxis; having ownership interest in Pfizer; and receiving honoraria from UpToDate. S. Dholakia reports having ownership interest in CareDx. S. Dholakia, X. Jin, H. Xu, and R.N. Woodward report being employees of CareDx. A. Djamali reports having consultancy agreements with, receiving honoraria from, and serving as a scientific advisor for or member of CareDx and CSL; and receiving research funding from CareDx and Takeda. X. Jin reports having ownership interest in CareDx. M.R. Weir reports having consultancy agreements (all are modest, <$10,000) with, receiving honoraria from, and serving as a scientific advisor for or member of AstraZeneca, Boehringer-Ingelheim, Bayer, CareDx, Janssen, Merck, Novo Nordisk, and Vifor Pharma. R.N. Woodward reports having ownership interest in CareDx. H. Xu reports having ownership interest in CareDx and Proxim Diagnostics, and having consultancy agreements with Proxim Diagnostics., (Copyright © 2021 by the American Society of Nephrology.)

Chronic active T cell-mediated rejection (CA TCMR) is a newly described variant of kidney allograft rejection associated with long-term graft loss. Whether this form of rejection is related to under immunosuppression is debated and the benefit of immunosuppressive therapy in CA TCMR is unknown. Here we investigate the amenability of CA TCMR to treatment and examine the impact of clinical, histologic, and molecular parameters on outcomes. In a retrospective single institution review, we identified 48 cases of isolated CA TCMR, of which 44 were treated with pulse steroids or anti-thymocyte globulin, or both. Defining treatment response as an at least 50% estimated glomerular filtration rate recovery, a response was achieved in 20% of cases at four weeks post initiation of immunosuppressive therapy. Treatment responsiveness did not reflect the presence of concomitant acute T cell-mediated rejection, and was not significantly different between cases with mild, moderate, and severe parenchymal scarring. Although not statistically significant, there was a trend toward greater treatment responsiveness in cases with moderate as opposed to severe tubulitis. By targeted transcriptional profiling, increased allograft mast cells and alterations in lipid metabolism were identified as possible features of treatment resistant CA TCMR. Thus, our study shows that although its prognosis is generally poor, CA TCMR is not a homogenous entity and in a subset of cases, improvement in kidney function can be achieved with immunosuppressive therapy., (Copyright © 2021 International Society of Nephrology. Published by Elsevier Inc. All rights reserved.)

Preformed donor-reactive T cells are relatively resistant to standard immunosuppression and account for an increased incidence of T cell-mediated rejection (TCMR) and inferior kidney allograft outcomes. We analyzed 150 living donor kidney transplant recipients (KTRs) of a first kidney allograft. Ninety-eight ABO-compatible (ABOc) and 52 ABO-incompatible (ABOi) KTRs were included. Samples were collected at 6 time points, before rituximab, before immunoadsorption and pretransplantation, at +1, +2, and +3 months posttransplantation, and donor-reactive T cells were measured by interferon-γ ELISPOT assay. Twenty of 98 ABOc (20%) and 12 of 52 ABOi KTRs (23%) showed positive pretransplant ELISPOT. Eight of 20 ABOc-KTRs (40%) with positive pretransplant ELISPOT showed TCMR, whereas 17 of 78 ABOc-KTRs (22%) with negative pretransplant ELISPOT did (P = 0.148). Seven of 12 ABOi KTRs (57%) with positive pretransplant ELISPOT showed TCMR, whereas only 3 of 40 ABOi KTRs (8%) with negative pretransplant ELISPOT did (P < 0.001). Interestingly, 6 of 7 ABOi KTRs with positive pretransplant ELISPOT that persists after ABO desensitization developed TCMR. Among 118 KTRs with negative pretransplant ELISPOT, 10 of 72 ABOc-KTRs (14%), but 0 of 46 ABOi KTRs, developed positive posttransplant ELISPOT (P = 0.006). Preformed donor-reactive T cells that persist despite ABO desensitization identify KTRs at highest risk of TCMR. Less de-novo donor-reactive T cells after ABO desensitization may account for less TCMR. Both, the use of rituximab and early initiation of calcineurin inhibitor-based maintenance immunosuppression may contribute to these findings., (© 2019 The Authors. Transplant International published by John Wiley & Sons Ltd on behalf of Steunstichting ESOT.)

Suppressor of cytokine signaling (SOCS) proteins have acknowledged roles in regulation of immune responses. Moreover, their role in the evolution of allograft rejection is being elucidated. In the current investigation, we measured transcript levels of SOCS1-4 in the peripheral blood of a group of renal transplant recipients including both rejected and non-rejected allografts. Expression analyses showed that relative expression of SOCS2 was significantly higher in transplant-rejected male patients compared to non-rejected group. However, such significant difference was not detected between female subjects. Expression of SOCS2 was significantly higher in T-cell-mediated rejection group compared with non-rejected individuals with creatinine rise (Relative expression difference [95% CrI] =6.74 [0.94, 12.65], P = 0.043). Conversely, SOCS4 expression was significantly lower in T-cell-mediated rejection group compared with non-rejected individuals with creatinine rise (Relative expression difference [95% CrI] = -0.35 [-0.63, -0.1], P = 0.008). Patterns of correlations between expression levels of SOCS genes were different in non-rejected group. The obtained results indicate the role SOCS genes in development of allograft rejection., (Copyright © 2019 Elsevier B.V. All rights reserved.)

The presence of B-cell clusters in allogenic T cell-mediated rejection (TCMR) of kidney allografts is linked to more severe disease entities. In this study we characterized B-cell infiltrates in patients with TCMR and examined the role of serum CXCL-13 in these patients and experimentally. CXCL-13 serum levels were analyzed in 73 kidney allograft recipients at the time of allograft biopsy. In addition, four patients were evaluated for CXCL13 levels during the first week after transplantation. ELISA was done to measure CXCL-13 serum levels. For further mechanistic understanding, a translational allogenic kidney transplant (ktx) mouse model for TCMR was studied in BalbC recipients of fully mismatched transplants with C57BL/6 donor kidneys. CXCL-13 serum levels were measured longitudinally, CD20 and CD3 composition and CXCL13 mRNA in tissue were examined by flow cytometry and kidneys were examined by histology and immunohistochemistry. We found significantly higher serum levels of the B-cell chemoattractant CXCL13 in patients with TCMR compared to controls and patients with borderline TCMR. Moreover, in patients with acute rejection within the first week after ktx, a >5-fold CXCL13 increase was measured and correlated with B-cell infiltrates in the biopsies. In line with the clinical findings, TCMR in mice correlated with increased systemic serum-CXCL13 levels. Moreover, renal allografts had significantly higher CXCL13 mRNA expression than isogenic controls and showed interstitial CD20+ B-cell clusters and CD3+ cell infiltrates accumulating in the vicinity of renal vessels. CXCL13 blood levels correlate with B-cell involvement in TCMR and might help to identify patients at risk of a more severe clinical course of rejection.

Acute T cell-mediated rejection (TCMR) is an important cause of renal allograft loss. The Banff classification for tubulointerstitial (type I) rejection is based on the extent of both interstitial inflammation and tubulitis. Lymphocytes may also be present between parietal epithelial cells and Bowman capsules in this setting, which we have termed "capsulitis." We conducted this study to determine the clinical significance of capsulitis. We identified 42 patients from the pathology archives at The University of Chicago with isolated Banff type I TCMR from 2010 to 2015. Patient demographic data, Banff classification, and graft outcome measurements were compared between capsulitis and noncapsulitis groups using Mann-Whitney U test. Capsulitis was present in 26 (62%) and was more frequently seen in Banff IB than in IA TCMR (88% versus 44%, P = .01). Patients with capsulitis had a higher serum creatinine at biopsy (4.6 versus 2.9 mg/dL, P = .04) and were more likely to progress to dialysis (42% versus 13%, P = .06), with fewer recovering their baseline serum creatinine (12% versus 38%, P = .08). Patients with both Banff IA TCMR and capsulitis have clinical outcomes similar to or possibly worse than Banff IB TCMR compared with those with Banff IA and an absence of capsulitis. Capsulitis is an important pathologic parameter in the evaluation of kidney transplant biopsies with potential diagnostic, prognostic, and therapeutic implications in the setting of TCMR., (Copyright © 2018 Elsevier Inc. All rights reserved.)

We utilized mouse models to elucidate the immunologic mechanisms of functional graft loss during mixed antibody-mediated rejection of renal allografts (mixed AMR), in which humoral and cellular responses to the graft occur concomitantly. Although the majority of T cells in the graft at the time of rejection were CD8 T cells with only a minor population of CD4 T cells, depletion of CD4 but not CD8 cells prevented acute graft loss during mixed AMR. CD4 depletion eliminated antidonor alloantibodies and conferred protection from destruction of renal allografts. ELISPOT revealed that CD4 T effectors responded to donor alloantigens by both the direct and indirect pathways of allorecognition. In transfer studies, CD4 T effectors primed to donor alloantigens were highly effective at promoting acute graft dysfunction, and exhibited the attributes of effector T cells. Laser capture microdissection and confirmatory immunostaining studies revealed that CD4 T cells infiltrating the graft produced effector molecules with graft destructive potential. Bioluminescent imaging confirmed that CD4 T effectors traffic to the graft site in immune replete hosts. These data document that host CD4 T cells can promote acute dysfunction of renal allografts by directly mediating graft injury in addition to facilitating antidonor alloantibody responses., (© Copyright 2014 The American Society of Transplantation and the American Society of Transplant Surgeons.)

We previously developed a microarray-based test for T cell-mediated rejection (TCMR) in a reference set of 403 biopsies. To determine the potential impact of this test in clinical practice, we undertook INTERCOM, a prospective international study of 300 indication biopsies from 264 patients (ClinicalTrials.gov NCT01299168). Biopsies from six centers-Baltimore, Barcelona, Edmonton, Hannover, Manchester and Minneapolis-were analyzed by microarrays, assigning TCMR scores by an algorithm developed in the reference set and comparing TCMR scores to local histology assessment. The TCMR score correlated with histologic TCMR lesions-tubulitis and interstitial infiltration. The accuracy for primary histologic diagnoses (0.87) was similar to the reference set (0.89). The TCMR scores reclassified 77/300 biopsies (26%): 16 histologic TCMR were molecularly non-TCMR; 15 histologic non-TCMR were molecularly TCMR, including 6 with polyoma virus nephropathy; and all 46 "borderline" biopsies were reclassified as TCMR (8) or non-TCMR (38). Like the reference set, discrepancies were primarily in situations where histology has known limitations, for example, in biopsies with scarring and inflammation/tubulitis potentially from other diseases. Neither the TCMR score nor histologic TCMR was associated with graft loss. Thus the molecular TCMR score has potential to add new insight, particularly in situations where histology is ambiguous or potentially misleading., (© Copyright 2013 The American Society of Transplantation and the American Society of Transplant Surgeons.)

Rejection in kidney transplantation are significant barriers affecting the survival of recipients and transplant kidneys. To further standardize the clinical diagnosis and treatment of rejection in kidney transplant recipients in China, the Branch of Organ Transplantation of Chinese Medical Association and Branch of Organ Transplantation Physician of Chinese Medical Doctor Association organized kidney transplant experts, transplant immunologists and other experts. Based on the " Technical specification for clinical diagnosis and treatment of renal transplant rejection (2019 edition)" issued by Branch of Organ Transplantation of Chinese Medical Association, and referring to recent domestic and international research findings, expert consensus, guidelines, and mature clinical experience, combined with the current clinical situation of rejection diagnosis and treatment in kidney transplant recipients in China, the "Guidelines for clinical diagnosis and treatment of rejection in kidney transplant recipients in China" have been formulated. The content covers the clinical standard diagnosis and treatment of kidney transplant hyperacute rejection, acute rejection (acute T cell-mediated rejection, acute antibody-mediated rejection), and chronic rejection (chronic active T cell-mediated rejection, chronic active antibody-mediated rejection), aiming to provide theoretical and clinical practice references for the clinical diagnosis and treatment of rejection in Chinese kidney transplant recipients, with the goal of improving and promoting the quality of kidney transplantation. [ABSTRACT FROM AUTHOR]

In this cross-sectional and longitudinal analysis of mapping the T-cell repertoire in kidney transplant recipients, we have investigated and validated T-cell clonality, immune repertoire chronology at rejection, and contemporaneous allograft biopsy quantitative tissue injury, to better understand the pathobiology of acute T-cell fraction, T-cell repertoire and antibody-mediated kidney transplant rejection. To follow the dynamic evolution of T-cell repertoire changes before and after engraftment and during biopsy-confirmed acute rejection, we sequenced 323 peripheral blood samples from 200 unique kidney transplant recipients, with (n=100) and without (n=100) biopsy-confirmed acute rejection. We report that patients who develop acute allograft rejection, have lower (p=0.01) T-cell fraction even before transplantation, followed by its rise after transplantation and at the time of acute rejection accompanied by high TCR repertoire turnover (p=0.004). Acute rejection episodes occurring after the first 6 months post-transplantation, and those with a component of antibody-mediated rejection, had the highest turnover; p=0.0016) of their T-cell repertoire. In conclusion, we validated that detecting repertoire changes in kidney transplantation correlates with post-transplant rejection episodes suggesting that T-cell receptor sequencing may provide recipient pre-transplant and post-transplant predictors of rejection risk.

All chronic and treatment-resistant acute rejections are "difficult-to-treat" and lead to progressive loss of graft function in kidney transplant recipients (KTR), as no effective treatment exists for such rejections to date. We review our experience with a novel strategy to treat such rejections by adding everolimus as a "rescue" to conventional triple maintenance therapy with prednisolone, mycophenolate mofetil and calcineurin inhibitor. We retrospectively analysed data in 28 KTR who received everolimus-based quadruple therapy at our institution for biopsy-proven chronic active T cell-mediated or antibody-mediated rejection (n = 19) or treatment-resistant acute rejections (n = 9) between 2011–2017. The primary outcome was 5-year death-censored graft survival. Main secondary outcomes were response to treatment defined by stable or improved graft function, 5-year patient survival and discontinuation rate of treatment. The Kaplan–Meier estimate for 5-year death-censored graft survival was 79% in all patients, 90% for patients with chronic active T cell-mediated rejections, 78% for chronic active antibody-mediated rejection and 67% for acute rejections. Response to treatment was achieved in 43% and 5-year patient survival was 94%. Treatment was stopped in 12 (43%) patients due to adverse events. Everolimus-based maintenance quadruple therapy, despite high rate of everolimus discontinuation due to adverse events, may be a valid approach in a subset of kidney transplant recipients with such difficult-to-treat rejections, which otherwise would lead to a high rate of graft loss. [ABSTRACT FROM AUTHOR]

IntroductionPeripheral blood (PB) molecular patterns characterizing the different effector immune pathways driving distinct kidney rejection types remain to be fully elucidated. We hypothesized that transcriptome analysis using RNA sequencing (RNAseq) in samples of kidney transplant patients would enable the identification of unique protein-coding and noncoding genes that may be able to segregate different rejection phenotypes.MethodsWe evaluated 37 biopsy-paired PB samples from the discovery cohort, with stable (STA), antibody-mediated rejection (AMR), and T cell-mediated rejection (TCMR) by RNAseq. Advanced machine learning tools were used to perform 3-way differential gene expression analysis to identify gene signatures associated with rejection. We then performed functional in silico analysis and validation by Fluidigm (San Francisco, CA) in 62 samples from 2 independent kidney transplant cohorts.ResultsWe found 102 genes (63 coding genes and 39 noncoding genes) associated with AMR (54 upregulated), TCMR (23 upregulated), and STA (25 upregulated) perfectly clustered with each rejection phenotype and highly correlated with main histologic lesions (ρ = 0.91). For the genes associated with AMR, we found enrichment in regulation of endoplasmic reticulum stress, adaptive immunity, and Ig class-switching. In the validation, we found that the SIGLEC17P pseudogene and 9 SIGLEC17P-related coding genes were highly expressed among AMR but not in TCMR and STA samples.ConclusionsThis analysis identifies a critical gene signature in PB in kidney transplant patients undergoing AMR, sufficient to differentiate them from patients with TCMR and immunologically quiescent kidney allografts. Our findings provide the basis for new studies dissecting the role of noncoding genes in the pathophysiology of kidney allograft rejection and their potential value as noninvasive biomarkers of the rejection process.

Early diagnosis of acute rejection is of significance for the protection of renal allograft function. Pathological puncture biopsy is the gold standard for the diagnosis of acute rejection of renal allografts. Nevertheless, it may provoke multiple complications, such as bleeding, infection and renal parenchymal injury, which limit its widespread application. In recent years, the sensitivity of contrast-enhanced ultrasound in the diagnosis of acute rejection has been constantly improved. Ultrasound-targeted microbubble technique has further enhanced the diagnostic specificity of contrast-enhanced ultrasound, making it possible to replace pathological puncture biopsy. Besides, in the field of acute rejection treatment, microbubble ultrasonic cavitation may promote local delivery of immunosuppressants by inducing sonoporation and exhibit anti-rejection effect. In this article, the application of contrast-enhanced ultrasound in the diagnosis and treatment of acute rejection after kidney transplantation was reviewed, aiming to provide reference for widespread application of contrast-enhanced ultrasound in kidney transplantation. [ABSTRACT FROM AUTHOR]

The management of long-term immune suppressive medication in kidney transplant recipients is a poorly explored field in the area of transplant medicine. In particular, older recipients are at an increased risk for side effects and have an exponentially increased risk of infection-related death. In contrast, an aged immune system decreases the risk of acute T-cell-mediated rejection in older recipients. Recent advances in alloimmunity research have shown a rapid and substantial decline in polyfunctional, high-risk CD4+ T cells post-transplantation. This lowers the direct alloreactivity responsible for T-cell-mediated rejection, also known as donor-specific hyporesponsiveness. Chronic antibody-mediated rejection (c-aABMR) is the most frequent cause of kidney graft loss in the long term. However, in older adults, c-aABMR as a cause of graft loss is outnumbered by death with a functioning graft. In addition, DSA development and a diagnosis of c-aABMR plateau ~10 years after transplantation, resulting in a very low risk for rejection thereafter. The intensity of immune suppression regimes could likely be reduced accordingly, but trials in this area are scarce. Tacrolimus monotherapy for 1 year after transplantation seems feasible in older kidney transplant recipients with standard immunological risk, showing the expected benefits of fewer infections and better vaccination responses.

Over the past 70 years, kidney transplantation has become not only the most mature but also the highest-success-rate surgery among all organ transplantation surgeries. However, the long-term survival of kidney transplant recipients is still challenged by such key factors as ischemia-reperfusion injury related to kidney transplantation, rejection, chronic renal allograft dysfunction, renal allograft fibrosis, immunosuppressive therapy, infections and others. Relevant fundamental and clinical studies have emerged endlessly. At the same time, the research related to kidney transplantation also becomes a new hot spot accordingly in the context of the normalization of novel coronavirus pneumonia. This article reviewed the cutting-edge hot spots in relation to the fundamental and clinical aspects of kidney transplantation together with relevant new techniques and new visions. The studies included in this article focused on the reports published by Chinese teams that are more applicable to the current situation of kidney transplantation in China, for the purpose of providing new thoughts and strategies for the diagnosis and treatment of kidney transplantation related issues in China. [ABSTRACT FROM AUTHOR]

Introduction: Peripheral blood (PB) molecular patterns characterizing the different effector immune pathways driving distinct kidney rejection types remain to be fully elucidated. We hypothesized that transcriptome analysis using RNA sequencing (RNAseq) in samples of kidney transplant patients would enable the identification of unique protein-coding and noncoding genes that may be able to segregate different rejection phenotypes. Methods: We evaluated 37 biopsy-paired PB samples from the discovery cohort, with stable (STA), antibody-mediated rejection (AMR), and T cell–mediated rejection (TCMR) by RNAseq. Advanced machine learning tools were used to perform 3-way differential gene expression analysis to identify gene signatures associated with rejection. We then performed functional in silico analysis and validation by Fluidigm (San Francisco, CA) in 62 samples from 2 independent kidney transplant cohorts. Results: We found 102 genes (63 coding genes and 39 noncoding genes) associated with AMR (54 upregulated), TCMR (23 upregulated), and STA (25 upregulated) perfectly clustered with each rejection phenotype and highly correlated with main histologic lesions (ρ = 0.91). For the genes associated with AMR, we found enrichment in regulation of endoplasmic reticulum stress, adaptive immunity, and Ig class-switching. In the validation, we found that the SIGLEC17P pseudogene and 9 SIGLEC17P-related coding genes were highly expressed among AMR but not in TCMR and STA samples. Conclusions: This analysis identifies a critical gene signature in PB in kidney transplant patients undergoing AMR, sufficient to differentiate them from patients with TCMR and immunologically quiescent kidney allografts. Our findings provide the basis for new studies dissecting the role of noncoding genes in the pathophysiology of kidney allograft rejection and their potential value as noninvasive biomarkers of the rejection process.

T cell-mediated rejection (TCMR) Is an Important rejection type In kidney transplantation, characterized by T cells and macrophages infiltration. The application of bioinformatic analysis in genomic research has been widely used. In the present study, Microarray data was analyzed to identify the potential diagnostic markers of TCMR in kidney transplantation. Cell-type identification by estimating relative subsets of RNA transcript (CIBERSORT) was performed to determine the distribution of immune cell infiltration in the pathology. Totally 129 upregulated differently expressed genes (DEGs) and 378 downregulated DEGs were identified. The GO and KEGG results demonstrated that DEGs were mainly associated with pathways and diseases involved in immune response. The intersection of the two algorithms (PPI network and LASSO) contains three overlapping genes (CXCR6, CXCL13 and FCGR1A). After verification in GSE69677, only CXCR6 and CXCL13 were selected. Immune cells Infiltration analysis demonstrated that CXCR6 and CXCL13 were positively correlated with gamma delta T cells (p < 0.001), CD4+ memory activated T cells (p < 0.001), CD8+ T cells (p < 0.001) and M1 macrophages (p = 0.006), and negatively correlated with M2 macrophages (p < 0.001) and regulatory T cells (p < 0.001). Immunohistochemical staining and image analysis confirmed the overexpression of CXCR6 and CXCL13 in human allograft TCMR samples. CXCR6 and CXCL13 could be diagnostic biomarkers of TCMR and potential targets for immunotherapy in patients with TCMR. [ABSTRACT FROM AUTHOR]

Background The emergence of molecular systems offers opportunities for improving the assessment of rejection in heart transplant biopsy specimens. The present study developed a microarray-based system for assessing heart transplant endomyocardial biopsy (EMB) specimens. Methods We analyzed 331 protocol or for-cause EMB specimens from 221 subjects in 3 centers (Edmonton, Bologna, and Paris). Unsupervised principal component analysis (PCA) and archetype analysis used rejection-associated transcripts (RATs) shown in kidney transplants to be associated with antibody-mediated rejection (ABMR) or T cell–mediated rejection (TCMR), or both. To compare EMB specimens to kidney biopsy specimens, rejection status in both was simplified to TCMR, ABMR, or no rejection. Results The pattern of RAT expression was similar in EMB and kidney specimens, permitting use of RATs to assign scores and group (“cluster”) membership to each EMB, independent of histology. Three clusters emerged in EMB specimens, similar to kidney specimens: TCMR, ABMR, and no rejection. This permitted each EMB specimen to be given 3 scores and assigned to 1 cluster by its highest score. There was significant agreement between molecular phenotype—archetype scores or clusters—and both histologic diagnoses and donor-specific antibody. Area under curve estimates for predicting histologic TCMR, ABMR, and no rejection by molecular assessment were lower in EMB specimens than in kidney specimens, reflecting more uncertainty in EMB specimens, particularly in histologic diagnosis of TCMR. Conclusions Rejection-associated transcripts can be used to estimate the probability of TCMR and ABMR in heart transplant specimens, providing a new dimension to improve the accuracy of diagnoses and an independent system for recalibrating the histology guidelines. [ABSTRACT FROM AUTHOR]

Ushigome H, Okamoto M, Koshino K, Nobori S, Okajima H, Masuzawa N, Urasaki K, Yoshimura N. Findings of graft biopsy specimens within 90 days after ABO blood group incompatible living donor kidney transplantation compared with ABO-identical and non-identical transplantation. Clin Transplant 2010: 24 (Suppl. 22): 16–21. © 2010 John Wiley & Sons A/S. As immunosuppressive therapy has advanced, we have markedly improved the outcome of ABO blood group incompatible living donor kidney transplantation. Consequently, graft survival at early phase after ABO-incompatible transplantation has been favorable than ABO-compatible transplantation in Japan. But in these days, it has been assumed that transplant glomerulopathy within one yr after ABO-incompatible kidney transplantation might be significantly precipitated. That may be because of chronic, active antibody-mediated rejection (AMR). We performed kidney graft biopsies at the early phase within 90 d after living donor kidney transplantation that involved the episode and protocol biopsies and studied findings of graft biopsy specimens when compared with ABO incompatible and compatible involving non-identical and identical transplantations. In ABO-incompatible transplant cases, the ratio occurring glomerulitis, especially severe injury of g 2–3, was significantly higher than that of identical and non-identical transplant cases (p < 0.01). There was no significant difference in t score, i score, ptc score and v score between three transplant groups. The cases occurring AMR were concordant with the cases recognized with severe glomerulitis. AMR was difficult to be diagnosed by C4d analysis in ABO-incompatible transplant cases. Glomerular injury score, g score, may be considered as more significant and the injury should be cured thoroughly. [ABSTRACT FROM AUTHOR]

In this clinical validation study, we developed and validated a urinary Q-Score generated from the quantitative test QSant, formerly known as QiSant, for the detection of biopsy-confirmed acute rejection in kidney transplants. Using a cohort of 223 distinct urine samples collected from three independent sites and from both adult and pediatric renal transplant patients, we examined the diagnostic utility of the urinary Q-Score for detection of acute rejection in renal allografts. Statistical models based upon the measurements of the six QSant biomarkers (cell-free DNA, methylated-cell-free DNA, clusterin, CXCL10, creatinine, and total protein) generated a renal transplant Q-Score that reliably differentiated stable allografts from acute rejections in both adult and pediatric renal transplant patients. The composite Q-Score was able to detect both T cell-mediated rejection and antibody-mediated rejection patients and differentiate them from stable non-rejecting patients with a receiver–operator characteristic curve area under the curve of 99.8% and an accuracy of 98.2%. Q-Scores < 32 indicated the absence of active rejection and Q-Scores ≥ 32 indicated an increased risk of active rejection. At the Q-Score cutoff of 32, the overall sensitivity was 95.8% and specificity was 99.3%. At a prevalence of 25%, positive and negative predictive values for active rejection were 98.0% and 98.6%, respectively. The Q-Score also detected subclinical rejection in patients without an elevated serum creatinine level but identified by a protocol biopsy. This study confirms that QSant is an accurate and quantitative measurement suitable for routine monitoring of renal allograft status. [ABSTRACT FROM AUTHOR]