Kidney Transplant Rejection Research Articles

Multicenter, Real-World Clinical Evaluation of Alemtuzumab and Anti-Thymocyte Globulin for Severe Acute T Cell-Mediated Kidney Transplant Rejection.

Alemtuzumab can be an alternative to rabbit anti-thymocyte globulin (rATG) to treat severe or glucocorticoid-resistant acute T cell-mediated kidney transplant rejection (TCMR). Yet, there are few reports in which these two treatments are evaluated let alone, compared. This study describes the real-world clinical experience of both therapies and compares their efficacy and toxicity. Kidney transplant recipients of two Dutch transplant centers who received lymphocyte-depleting antibody therapy for severe or glucocorticoid-resistant TCMR were retrospectively evaluated. In the first, alemtuzumab was the standard treatment for this indication, in the second, it was rATG. Patient survival, graft survival and function, and the occurrence of infections and malignancies were reported and compared. One hundred and forty-three patients treated with alemtuzumab and 57 patients with rATG were evaluated. Patient survival was not significantly different during follow-up (p=0.55), and 5-year survival rates were 71.0% (95% confidence interval [CI]: 63.0-79.9) after alemtuzumab and 70.7% (95% CI: 58.3-85.7) after rATG. Graft survival was not significantly different during follow-up either (p=0.24), and 5-year graft loss rates were 32.3% (95% CI: 24.2-40.5) after alemtuzumab and 29.2% (95% CI: 16.0-42.4) after rATG. The occurrence of infections and malignancies did not differ between groups. Mostly, severe TCMRs have good long-term graft survival and function after either alemtuzumab or rATG therapy. No significant differences between the two therapies were found in this real-world clinical experience. Alemtuzumab is an effective alternative to rATG for the treatment of severe TCMR.

Deciphering the impact of senescence in kidney transplant rejection: An integrative machine learning and multi-omics analysis via bulk and single-cell RNA sequencing.

The demographic shift towards an older population presents significant challenges for kidney transplantation (KTx), particularly due to the vulnerability of aged donor kidneys to ischemic damage, delayed graft function, and reduced graft survival. KTx rejection poses a significant threat to allograft function and longevity of the kidney graft. The relationship between senescence and rejection remains elusive and controversial. Gene Expression Omnibus (GEO) provided microarray and single-cell RNA sequencing datasets. After integrating Senescence-Related Genes (SRGs) from multiple established databases, differential expression analysis, weighted gene co-expression network analysis (WGCNA), and machine learning algorithms were applied to identify predictive SRGs (pSRGs). A cluster analysis of rejection samples was conducted using the consensus clustering algorithm. Subsequently, we utilized multiple machine learning methods (RF, SVM, XGB, GLM and LASSO) based on pSRGs to develop the optimal Acute Rejection (AR) diagnostic model and long-term graft survival predictive signatures. Finally, we validated the role of pSRGs and senescence in kidney rejection through the single-cell landscape. Thirteen pSRGs were identified, correlating with rejection. Two rejection clusters were divided (Cluster C1 and C2). GSVA analysis of two clusters underscored a positive correlation between senescence, KTx rejection occurrence and worse graft survival. A non-invasive diagnostic model (AUC = 0.975) and a prognostic model (1- Year AUC = 0.881; 2- Year AUC = 0.880; 3- Year AUC = 0.883) for graft survival were developed, demonstrating significant predictive capabilities to early detect acute rejection and long-term graft outcomes. Single-cell sequencing analysis provided a detailed cellular-level landscape of rejection, supporting the conclusions drawn from above. Our comprehensive analysis underscores the pivotal role of senescence in KTx rejection, highlighting the potential of SRGs as biomarkers for diagnosing rejection and predicting graft survival, which may enhance personalized treatment strategies and improve transplant outcomes.

Blood Gene Expression Profiling and Donor-derived Cell-free DNA to Noninvasively Diagnose Clinical and Subclinical Kidney Transplant Rejection: A Real-life Appraisal Study

Background. Peripheral blood biomarkers aim to noninvasively diagnose kidney allograft rejection, but most lack robust independent validation. TruGraf is intended to exclude subclinical cellular rejection (TCMR), whereas donor-derived cell-free DNA Viracor-TRAC has proven value in excluding antibody-mediated rejection (AMR). We aim to validate both biomarkers for accurate rejection diagnosis in a real-world clinical setting. Methods. We prospectively included 230 unselected, consecutive kidney transplants from 6 centers undergoing for-cause and protocol biopsies with paired blood samples from December 2021 to 2022. TruGraf and Viracor-TRAC were blindly run by a central laboratory. Results. The incidence of rejection was 22.6% (17.3% surveillance; 27% for-cause biopsies). Inflammation was associated with higher TRAC levels, with AMR/mixed and microvascular inflammation (MVI) showing the highest levels (P < 0.05). TruGraf did not associate with any specific allograft injury. No biomarkers, individually or combined, accurately diagnosed any rejection (area under the receiver operating characteristic curve [AUROC] < 0.65). However, high TRAC levels, when combined with DSA in for-cause biopsies, predicted AMR/mixed rejection or MVI (AUROC = 0.817; P < 0.001), outperforming serum creatinine and DSA (AUROC < 0.65). Conclusions. In this large, prospective, observational real-life study, we were unable to validate TruGraf and TRAC to diagnose rejection but found a useful context of use for TRAC to noninvasively diagnose AMR/mixed or MVI in conjunction with DSA in dysfunctioning graft.

Spatial Transcriptomic Signatures of Early Acute T Cell-mediated Rejection in Kidney Transplants.

Kidney transplantation significantly improves the quality of life for those with end-stage renal failure, yet allograft rejection resulting from immune cell interactions remains a persistent challenge. Although T cell-directed immunosuppressive drugs effectively contain graft rejection in most patients, a notable proportion still experiences acute T cell-mediated rejection (TCMR). Despite an emphasis on suppressing T cell-mediated immune responses, successful control over TCMR is not always achieved, suggesting the potential involvement of factors beyond T cells. Biopsy samples from suspicious (borderline) for acute TCMR (borderline TCMR) and non-TCMR patients were obtained 9 d postsurgery, and spatial transcriptomics profiling was conducted using the GeoMx Digital Spatial Profiler platform. Regions of interest in the glomerulus and interstitium were selected on the basis of immunohistochemistry staining anti-CD3 to identify areas with T-lymphocyte infiltration. Differential gene expression analysis was performed using unpaired t tests. Unbiased clustering of transcriptional profiles across all regions of interest showed distinct transcriptional profiles between glomeruli and interstitium in non-TCMR samples, whereas borderline TCMR samples displayed no distinct transcriptional profiles between these regions. Contrary to the prevailing T cell-centric view, we observed pathways and genes associated with innate immunity-related inflammatory conditions expressed in glomerular regions of borderline TCMR biopsies. Immunofluorescence staining for CD68 confirmed the presence of macrophages in the glomeruli of the post-TCMR sample in a validation cohort, indicating macrophage involvement in the glomerular response after TCMR. Activation of the innate immune response in borderline TCMR appears to impact not only the interstitium but also the glomerulus. Glomerulus-specific immune signatures suggest the role of the innate immune system in rejection. This nuanced understanding proposes the necessity for tailored therapeutic interventions targeting both innate and adaptive immune pathways to enhance transplant outcomes.

Serological and Molecular Diagnosis of Human Cytomegalovirus among Hemodialysis Patients in Kirkuk/Iraq

Serological and Molecular Diagnosis of Human Cytomegalovirus among Hemodialysis Patients in Kirkuk/Iraq

Landscape of the immune infiltration and identification of molecular diagnostic markers associated with immune cells in patients with kidney transplantation

Rejection seriously affects the success of kidney transplantations. However, the molecular mechanisms underlying this rejection remain unclear. The GSE21374 and GSE36059 datasets were downloaded from the Gene Expression Omnibus (GEO) database. Next, the Cell-type Identification by Estimating Relative Subsets of RNA Transcripts (CIBERSORT) algorithm was used to infer the proportions of 22 immune cells. Moreover, infiltrating immune cell-related genes were identified using weighted gene co-expression network analysis (WGCNA), and enrichment analysis was conducted to observe their biological functions. Extreme Gradient Boosting (XGBoost) and Least Absolute Shrinkage and Selection Operator (LASSO) logistic regression algorithms were used to screen hub genes. Quantitative real-time PCR was conducted to verify the number of immune cells and hub gene expression levels. The rejection and non-rejection groups showed significantly different distributions (P < 0.05) of eight immune cells (B cell memory, Plasma cells, mast cells, follicular helper T cells, T CD8 cells, Macrophages M1, T Cells CD4 memory activated, and gamma delta T cells). Subsequently, CD8A, CRTAM, GBP2, WARS, and VAMP5 were screened as hub genes using the XGBoost and LASSO algorithms and could be used as diagnostic biomarkers. Finally, differential analysis and quantitative real-time PCR suggested that CD8A, CRTAM, GBP2, WARS, and VAMP5 were upregulated in rejection samples compared to non-rejection samples. The present study identified five key infiltrating immune cell-related genes (CD8A, CRTAM, GBP2,WARS, and VAMP5) involved in kidney transplant rejection, which may explain the molecular mechanism of rejection in kidney transplantation development.

C1q Binding Ability for Prior Risk Assessment of Acute Antibody-Mediated Rejection in ABO-Incompatible Kidney Transplantation.

In ABO blood group incompatible kidney transplantation (ABO-I), potential issues on acute antibody-mediated rejection (ABMR) remain to be solved. This study aimed to assess the risk factors of acute ABMR using recipient- or donor-derived specimens. Quantitative analysis of A/B antigen expression was conducted in 104 donor kidney tissues (Kt), platelets (Plt), and red blood cells (RBC) by immunohistochemical staining or flow cytometry (FCM). ABO-I pre-transplant recipient serum samples (ABMR = 12, non-ABMR = 27) were extracted by propensity score matching. Anti-A antibody titers of IgM, IgG and IgG subclasses, and C1q binding ability (%) on antibody were measured using RBC-FCM. No association was observed between ABMR and A/B antigen expression levels in donor's Plt, RBC, or Kt. In recipient's sample, C1q-IgG binding ability was significantly higher in the ABMR group than in the non-ABMR group (C1q-IgG: 9.04% vs. 5.93% p = 0.049). Neither the A/B antigen expression level in donors (grafts) nor anti-blood group IgG/IgM antibodies in recipient sera before desensitization seemed to influence ABMR incidence in ABO-I. In contrast, C1q-IgG binding ability could be a potential predictor for ABMR in ABO-I.

Circulating Immune Complexes and Complement Activation in Sensitized Kidney Transplant Recipients.

Chronic antibody-mediated rejection in kidney transplantation is a common cause of graft loss in the late post-transplant period. In this process, the role of the classical complement activation pathway is crucial due to the formation of immune complexes between donor-specific antibodies (DSAs) and donor antigens and the attachment of the C1q complement fragment. This study aimed to determine the levels of circulating C1q immunocomplexes (CIC-C1q) and complement activation (CH50), in sensitized kidney transplant recipients (KTRs). In this cross-sectional study we used serum samples from KTRs with de novo or preformed DSAs (n = 14), KTRs without DSAs (n = 28), and 22 subjects with no history of chronic kidney disease (controls). C1q immunocomplexes and CH50 concentration in serum were measured with the enzyme immunoassay (EIA) kit MicroVue CIC-C1q (Quidel, Athens, OH, USA) and EIA kit MicroVue CH50 (Quidel, OH, USA), respectively. Higher concentrations of CIC-C1q was observed in KTRs with DSAs in comparison with controls and with KTRs with no DSAs (6.8 ± 2.7 and 4.8 ± 1.9 vs. 5.0 ± 1.2 μg Eq/mL, respectively, p < 0.01). We found no difference in CIC-C1q between KTRs with no DSAs and controls. CIC-C1q levels were positively correlated with DSA titer. CH50 levels were decreased in KTRs with DSAs in comparison with controls and KTRs with no DSAs (39 ± 15 vs. 68 ± 40 and 71 ± 34 U Eq/mL, respectively, p < 0.01). There was no difference in CH50 between DSA-negative KTRs and controls. Kidney transplant recipients with DSAs had increased serum levels of C1q immunocomplexes and increased classical pathway complement activation.

Epithelial Injury Patterns Induced by Acute T Cell-Mediated Rejection in Kidney Transplants

Epithelial Injury Patterns Induced by Acute T Cell-Mediated Rejection in Kidney Transplants

Active immunologic participation and metabolic shutdown of kidney structural cells during kidney transplant rejection

Contrary to immune cells, the response of the kidney structural cells in rejection is less established. We performed single-cell RNA sequencing of 18 kidney transplant biopsies from 14 recipients. Single-cell RNA sequencing identified cells from the major compartments of the kidney, next to infiltrated immune cells. Endothelial cells from the glomerulus, peritubular capillaries, and vasa recta showed upregulation of class I and II human leukocyte antigen genes, adhesion molecules, cytokines, and chemokines, suggesting active participation in the alloimmune process, with compartment-specific differences. Epithelial cells including proximal tubular, loop of Henle, and collecting duct cells, also showed increased expression of immune genes. Strikingly, in proximal tubule cells, a strong downregulation of energy metabolism upon inflammation was observed. There was a large overlap between the cell-specific expression changes upon alloimmune inflammation and those observed in 2 large microarray biopsy cohorts. In conclusion, the kidney structural cells, being the main target of the alloimmune process, appear to actively contribute herein, enhancing the damaging effects of the infiltrating immune cells. In epithelial cells, a profound shutdown of metabolism was seen upon inflammation, which is associated with poor kidney function. These observations highlight the critical role of the graft in triggering and sustaining rejection after transplantation.

Pretransplantation assessment of BK virus seropositivity in kidney donors and recipients

Background: BK virus (BKV) is a member of the polyomavirus family. The determination of anti-BKV immunoglobulin G (IgG) antibody levels in kidney donors and recipients has been reported as a possible predictor of the risk of BK nephropathy. Allograft dysfunction is a significant risk factor. The main objective of this study was to address the high prevalence of renal failure due to BKV nephropathy in kidney transplant recipients. This investigation aims to determine whether donors and recipients of renal transplants had BKV IgG antibodies before transplantation. Methods: Blood samples were collected from 46 kidney transplant recipients and their corresponding 46 donors. An enzyme-linked immunosorbent assay was used to qualitatively analyze human BKV IgG. Results: Ninety-two participants, 46 kidney transplant donors, and 46 kidney transplant recipients, were analyzed. Pretransplantation anti-BKV antibody levels were higher in kidney transplant donors (73%) than in recipients (63%). Donors and recipients included in the study were grouped into seropositive and seronegative recipients, with the highest proportion of seropositive recipient-donor groups (48%) and the lowest percentages in the seronegative donor and seronegative recipient groups. Fifty-one percent of the participants were male and 49% were female. The age distribution of most subjects was &gt;50 years old. Conclusion: BKV can cause kidney transplant rejection. Routine screening of transplant recipients and donors for BKV IgG seropositivity is recommended before renal transplantation. This can improve transplant outcomes and prevent rejection.

Clazakizumab in Chronic Active Antibody-Mediated Kidney Transplant Rejection: Results of the IMAGINE Phase 3 Study

Clazakizumab in Chronic Active Antibody-Mediated Kidney Transplant Rejection: Results of the IMAGINE Phase 3 Study

Donor-derived cell-free DNA-based liquid biopsies to determine future kidney transplant rejection.

Donor-derived cell-free DNA (dd-cfDNA) based liquid kidney biopsies have the potential to detect the chances of kidney transplant rejection. Several studies have found that dd-cfDNA can be used to determine the risk of kidney transplant rejection and may correlate with antibody-mediated rejection (ABMR), T cell-mediated rejection (TCMR), and estimated glomerular filtration rate (eGFR). A high concentration of dd-cfDNA in the body fluids may indicate possible transplant rejection since dd-cfDNA is released as a result of apoptotic and necrotic processes initiated by the recipient's immune system. dd-cfDNA assays have advantages over conventional biopsies since they are noninvasive, and therefore, have the potential to provide a safe and reliable biomarker. Different dd-cfDNA levels have been reported above a number of cutoff thresholds: ABMR at 2.45% and TCMR at 1.3%, compared with 0.44% in healthy patients; and eGFR at 2.5%, a decrease of 25% compared with healthy patients. These results indicate the levels of dd-cfDNA that may be used to signal possible kidney rejection. dd-cfDNA assay is a rapid technique, making it particularly useful in emergencies, and further research into its use in the study of kidney rejection should prove beneficial.

Impact of non-human leukocyte antigen antibodies on delayed graft function, rejection, and graft survival in kidney transplantation

Impact of non-human leukocyte antigen antibodies on delayed graft function, rejection, and graft survival in kidney transplantation

The simultaneous presence of active BK, Epstein Barr, and human cytomegalovirus infection and their correlation by host factors in patients suspected of kidney transplant rejection

AimsThis study aims to evaluate the presence of EBV, HCMV, and BKV genomic sequences in the plasma samples (active infection/viremia) of kidney transplant recipients suspected of rejection and to investigate host and risk factors related to the activation of these viruses in these patients.MethodsIn this cross-sectional single-center study, plasma samples were collected from 98 suspected kidney transplant rejection patients at Labafinejad Hospital, Tehran, Iran, between December 2022 and June 2023. Quantitative real-time PCR assays for HCMV, EBV, and BK were performed using GeneProof Real-time PCR kits. ROC curve analysis was used to determine the viral load cutoff point for each virus.FindingsHCMV active viremia was detected in 18 (18.36%) recipients, EBV active viremia in 7 (7.14%), and BKV active viremia in 5 (5.10%). ROC results indicated viral load cutoff points of 778, 661, and 457 points for HCMV, EBV, and BKV, respectively. The duration of time after transplantation significantly differed between active viremia and no viremia groups (120.5 vs. 46 months, P = 0.014). In the BKV active viremia group, the increase in creatinine compared to baseline creatinine was significantly higher than in the no viremia group (2.7 vs. 0.8, P = 0.017). The odds ratio of HCMV active viremia in patients taking tacrolimus was 2.84 times higher, and the odds of HCMV active viremia in patients taking antithymocyte globulin was 3.01 times higher than in patients not taking these drugs.ConclusionRapid and timely diagnosis of viral active infections in kidney transplant patients is crucial for effective disease management and implementation of appropriate treatment strategies. Identifying potential risk factors, including host and treatment-related factors that influence transplantation, can facilitate the development of suitable preventive strategies.

Upregulated Expression of Janus Kinase Genes in T Cell-Mediated Acute Kidney Allograft Rejection

Background: T-cell-mediated acute kidney transplant rejection (TCMR) is a post-transplantation complication characterized by the infiltration of immune cells into the tissue and sudden dysfunction of the allograft. To develop effective diagnostic and therapeutic methods, it is crucial to understand the molecular mechanisms involved in the initiation and progression of TCMR. Janus kinase (JAK) enzymes, which are involved in proinflammatory cytokine signal transduction, may play a role in TCMR. Given the recent development of JAK inhibitors, the role of JAK molecules should be explored to determine whether they could be potential targets for the treatment of TCMR. Objectives: The study aimed to compare the relative expression of JAK-1, JAK-2, and JAK-3 genes between patients diagnosed with TCMR and stable recipients. Methods: The expression of JAK-1, JAK-2, and JAK-3 genes was evaluated in peripheral blood monocytes of 30 patients with TCMR and 30 stable patients using the RT-PCR method. Results: Janus kinase-1 gene expression in TCMR patients was significantly higher compared to stable patients (P-value = 0.02). However, the relative expression of JAK-2 and JAK-3 genes was comparable between the two groups. Additionally, there was a negative correlation between JAK-1 and JAK-3 gene expression and the estimated glomerular filtration rate in the studied population (P-value = 0.01 and 0.029, respectively). Conclusions: Janus kinase-1 gene expression increased significantly during TCMR of the kidney transplant. Therefore, specific inhibition of this molecule by JAK inhibitor drugs might be considered a therapeutic option for treating TCMR.

201.4: The combination of urine CXCL10 and donor-derived cell free DNA in the non-invasive diagnosis of antibody mediated and T cell mediated rejection in kidney transplantation.

201.4: The combination of urine CXCL10 and donor-derived cell free DNA in the non-invasive diagnosis of antibody mediated and T cell mediated rejection in kidney transplantation.

362.1: Increases in donor-derived cell-free DNA prior to biopsy proven rejection in kidney transplant.

362.1: Increases in donor-derived cell-free DNA prior to biopsy proven rejection in kidney transplant.

205.7: Dynamic release of kidney-derived urinary extracellular vesicles: potential biomarkers for acute rejection in kidney transplantation.

205.7: Dynamic release of kidney-derived urinary extracellular vesicles: potential biomarkers for acute rejection in kidney transplantation.

Gene expression–based molecular scoring of pancreas transplant rejection for a quantitative assessment of rejection severity and resistance to treatment

Pancreas transplantation improves glycemic control and mortality in patients with diabetes but requires aggressive immunosuppression to control the alloimmune and autoimmune response. Recent developments in “omics” methods have provided gene transcript-based biomarkers for organ transplant rejection. The tissue Common Response Module (tCRM) score is developed to identify the severity of rejection in kidney, heart, liver, and lung transplants. Still, it has not yet been validated in pancreas transplants (PT). We evaluated the tCRM score’s relevance in PT and additional markers of acute cellular rejection (ACR) for PT. An analysis of 51 pancreas biopsies with ACR identified 37 genes and 56 genes significantly upregulated in the case of grade 3 and grade 2 ACR, respectively (P < .05). Significant differences were seen with higher grades of rejection among several transcripts. Of the 22 genes differentially expressed in grade 3 ACR, 18 were also differentially expressed in grade 2 ACR. The rejection signal was attributable to activated leukocytes’ infiltration. Significantly higher tCRM scores were found in grade 3 ACR (P = .007) and grade 2 ACR (P = .004), compared to normal samples. The tCRM score was able to distinguish treatment-resistant cases from those successfully treated for rejection.