Search Results (119)

Introduction: Presently, liver transplantation is becoming a more common treatment option for adults and children suffering from liver failure. Antibody-mediated rejection (AMR), a phenomenon that is exceedingly uncommon and inadequately comprehended, may induce graft dysfunction. The objective of the investigation was to evaluate the clinical and histopathological manifestations of AMR in pediatric patients. Material and methods: The retrospective study comprised sixty-two liver core biopsies from forty-two pediatric patients. In a total of 10 biopsies, 7 children were diagnosed with AMR, while 35 of them exhibited features of acute T-cell-mediated rejection (TCMR) in 52 biopsies. The C4d binding assay was conducted in all biopsies using the immunohistochemical (IHC) method. Bilirubinostasis, steatosis and acute and chronic rejection were re-assessed in all specimens. The 6-grade Ishak scale was employed to evaluate fibrosis. The TCMR activity was established using the Banff classification. AMR was assessed according to a novel histopathological grading system that was developed by the authors. Depending on the type of rejection, the relationship between histopathological grading, morphological characteristics, and laboratory parameters was established for each group. Standard methods were implemented to conduct statistical analysis. Results: At the time of biopsy, the median age of patients was 47.6 months (15.03–98.83) and the median time from transplantation was 0.9 months (0.3–7.6). The study’s findings provided evidence that histopathological lesions were the least specific manifestation, which supported the presence of AMR. A positive C4d staining statistically increases the likelihood of AMR diagnosis, whether or not there are associated morphological abnormalities. The type of rejection and laboratory tests did not exhibit any statistically significant correlation. Conclusions: The diagnosis of AMR in a transplanted liver is intricate and requires a multifaceted approach. However, the proposed histopathological grading may be a helpful method for selecting patients who should be assessed for donor-specific antibodies (DSAs) or in whom AMR should be suspected when DSAs cannot be determined. Full article

Importance: Immune checkpoint inhibitors (ICIs) have expanded downstaging options for hepatocellular carcinoma (HCC) and cholangiocarcinoma (CCA), enabling bridging to liver transplantation (LT). However, the immunologic consequences of pre-transplant checkpoint blockade, particularly the risk of allograft rejection mediated by persistent T-cell activation, remain insufficiently characterized, creating a critical knowledge gap at the intersection of immuno-oncology and transplant medicine. Objective: To synthesize current evidence on oncologic outcomes, rejection risk, washout intervals, donor-type considerations, and immunosuppression strategies in LT recipients with pre-transplant ICI exposure. Evidence Review: A PRISMA-ScR-guided review was conducted using MEDLINE, Embase, Cochrane Library, and Web of Science from January 2015 through December 2025. Studies reporting outcomes in adult LT recipients with documented pre-transplant ICI exposure for HCC or CCA were included. Methodological quality was descriptively assessed using the Newcastle-Ottawa Scale and JBI tools. Given study heterogeneity, findings were narratively synthesized. Findings: Thirty studies were included. In HCC, neoadjuvant ICI therapy achieved downstaging to Milan criteria in 75.6% of candidates in the largest multicenter cohort (n = 117), with complete pathologic response rates ranging from 23.8% to 40%. Rejection rates ranged from 16.3% to 20.2% in large series but increased to 56.3% with short washout intervals. Washout intervals exceeding 50 days were associated with rejection rates approaching non-ICI controls, while an individual patient meta-analysis of 91 patients estimated each additional week of washout was associated with approximately 8% reduction in rejection risk, suggesting that approximately 94 days may be required to achieve a rejection probability of 20% or less. Rejection occurred at a median of 7–10 days post-transplantation, earlier than typical acute cellular rejection. Three-year overall survival exceeded 85.3% in major cohorts. Donor type was not consistently associated with rejection after adjustment for washout duration. CCA data remain limited. Immune-related adverse events during ICI therapy were associated with increased post-transplant rejection risk. Conclusions: Pre-transplant ICI therapy may expand transplant eligibility in advanced hepatobiliary malignancies but carries time-dependent rejection risk. Current evidence supports a minimum washout interval of at least 50 days, with emerging data favoring 90–94 days when feasible. Prospective multicenter studies, biomarker-guided risk stratification, and standardized immunosuppression protocols are needed to refine patient selection and optimize timing. Full article

Chronic kidney disease is rising worldwide, and kidney transplantation remains the preferred modality of kidney replacement therapy. However, long-term graft survival continues to be limited by chronic alloimmune injury, particularly antibody-mediated rejection (ABMR) and its chronic active form. This narrative review synthesizes contemporary evidence on the immunopathogenesis, epidemiology, diagnosis, and management of kidney allograft rejection, with a deliberate focus on studies from the last five years and on United States and European cohorts. We summarize current concepts of T cell–mediated rejection (TCMR), ABMR, mixed and donor-specific antibody (DSA)–negative phenotypes, and the evolution of the Banff classification, highlighting how chronic active ABMR has emerged as a leading cause of death-censored graft loss. We then critically appraise the conventional diagnostic triad of creatinine/eGFR, DSA, and biopsy and review emerging tools, including donor-derived cell-free DNA, urinary chemokines such as CXCL9 and CXCL10, additional blood- and urine-based biomarkers, and biopsy transcriptomics. We also examine how artificial intelligence and machine learning may support digital pathology, multimodal risk prediction, and data integration, while recognizing the current challenges of biological interpretability, external validation, and clinical implementation. Finally, we propose a rejection-focused precision-medicine framework and outline key research gaps, including multicenter validation, trial-ready endpoints, and governance for AI-enabled pathways. Overall, the field is moving from isolated diagnostic signals toward integrated, biologically informed, and clinically actionable approaches to rejection detection and risk stratification. Full article

Background and Objectives: Renal transplantation is the optimal treatment for end-stage renal disease, yet long-term allograft survival remains threatened by immune-mediated injury and chronic nephropathy. Conventional monitoring using serum creatinine and protocol biopsy suffers from limited sensitivity for early, subclinical injury. Liquid biopsy-based biomarkers offer a non-invasive alternative. Materials and Methods: We conducted a systematic narrative review of studies published between January 2010 and December 2024, identified through PubMed, Scopus, and Web of Science. Results: Extracellular vesicles carry injury-specific molecular cargo reflecting the biological state of tubular, glomerular, and endothelial cells; urinary EV CXCL9 protein and exosomal CD3ε mRNA have demonstrated AUC values of 0.81–0.88 for the detection of T-cell-mediated rejection. Donor-derived cell-free DNA quantifies global graft cell death; the FDA-cleared AlloSure assay achieves an AUC of 0.74 and NPV of 84% at the validated ≥1.0% threshold established in the DART trial. Donor-specific antibodies—particularly complement-fixing C1q-positive DSAs—confer markedly inferior 5-year graft survival compared with DSA-negative recipients (54% versus 93%). Multi-biomarker panels integrating all three modalities yield AUCs of 0.88–0.94 and NPVs of 91–95%. Conclusions: The integration of EV, ddcfDNA, and DSA monitoring into a unified surveillance framework offers a clinically meaningful advance over creatinine-based monitoring. Prospective randomized trials confirming improvement in long-term allograft survival will be the critical next step. Full article

Immune checkpoint inhibitors (ICIs) have transformed the therapeutic landscape of advanced hepatocellular carcinoma (HCC), establishing immunotherapy-based combinations as the standard of care. Improved treatment responses have expanded liver transplant eligibility for selected patients with advanced HCC through downstaging or bridging strategies. Such advances have directly influenced transplant candidacy and post-transplant outcomes. However, accumulating evidence indicates that pretransplant exposure to ICIs may disrupt post-transplant immune homeostasis, increasing the risk of acute allograft rejection and graft failure requiring retransplantation. From an immunological perspective, rejection following pretransplant ICI therapy predominantly manifests as T cell-mediated rejection and is characterized by the sustained activation of effector T cells and impairment of regulatory immune pathways. Blockade of immune checkpoint signaling interferes with mechanisms critical for allograft tolerance, including T cell apoptosis and regulatory T cell induction. Recent studies further underscore the importance of the washout period between ICI discontinuation and LT, with longer washout intervals being associated with lower rejection rates. Importantly, timely recognition and appropriate immunosuppressive management can often resolve acute rejection without adversely affecting long-term graft outcomes. This review integrates current immunological insights with emerging clinical evidence to inform optimal transplant timing and management strategies for liver transplant candidates receiving ICIs. Full article

Background/objectives: Kidney transplant recipients require lifelong immunosuppression and monitoring to prevent rejection, infection, and graft dysfunction. Current surveillance relies on tacrolimus therapeutic drug monitoring and, when needed, invasive biopsies. Dried blood spot (DBS) sampling provides a minimally invasive, patient-friendly option for remote follow-up. This study aims to develop and evaluate a DBS-based method for CXCL-10 quantification that, in combination with tacrolimus exposure monitoring, could help identify kidney recipients at risk of rejection and cytomegalovirus (CMV) infection and guide immunosuppression adjustment. Methods: The study included 81 selected kidney recipients for CXCL-10-DBS analysis by ELISA (12 T-cell mediated rejection; 10 antibody-mediated rejection; 6 CMV infection and 53 clinical event-free) and 10 healthy volunteers. A Tacrolimus-DBS LC-MS/MS method was developed and validated, and it was compared with the reference method on venous whole blood (WB) LC-MS/MS in a validation cohort (n = 160) and a clinical cohort (n = 36) using linear regression, Passing–Bablok and Bland–Altman analyses. Results: CXCL-10-DBS concentrations were significantly higher in rejectors (p < 0.001), with intermediate increases in CMV infection in comparison with event-free patients and healthy volunteers. ROC analysis demonstrated excellent diagnostic accuracy for rejection (AUC: 0.952; cutoff: 216.2 pg/mL; sensitivity: 100%; specificity: 79%; PPV: 88%; NPV: 100%). In contrast, tacrolimus trough concentrations did not differ significantly among the three clinical groups but showed strong correlation and agreement between DBS and venous WB with no systematic or proportional bias. Conclusions: This pilot study demonstrates the feasibility and diagnostic potential of DBS-based CXCL-10 measurement in adult kidney recipients. Integration of DBS-tacrolimus monitoring supports a minimally invasive pharmacokinetic–pharmacodynamic approach for personalized immunosuppression management. Full article

Chimeric antigen receptor (CAR)-T cell therapies represent a promising therapeutic approach for refractory autoimmune diseases. Although autologous CAR-T cells have achieved success thus far, they require expensive, individualised manufacturing, limiting their commercialisation potential. Allogeneic alternatives could overcome these scalability barriers, providing ‘off-the-shelf’ treatments, although they raise the issues of graft-vs-host reactions and host-mediated rejection. To mitigate such risks, gene-edited αβ T cells or non-alloreactive host cells (e.g., NK cells, γδ T cells) may be used. This review evaluates evidence of the functionality and commercial potential of various allogeneic CAR-T solutions for autoimmunity. Searches were conducted of PubMed, EMBASE and Web of Science to extract clinical and preclinical studies of allogeneic CAR-T cells, for the treatment of autoimmune diseases and B or T cell malignancies. In light of the paucity of data on autoimmune disease, the latter were included to facilitate extrapolation to the autoimmune setting. A total of 107 studies were included. The available clinical outcomes of efficacy and safety, as well as preclinical key findings, are reported. Current developments and potential future improvements for safety, effectiveness and cost-effective manufacture are then discussed. The findings of this review demonstrate the promising therapeutic potential of allogeneic CAR-T for autoimmune disease, with scope for the further optimisation of safety and scalable manufacture to facilitate commercialisation. Full article

Antibody-mediated rejection (ABMR) remains a leading cause of kidney allograft failure, yet the mechanistic roles of innate immune cell subsets such as monocytes and natural killer (NK) cells remain incompletely understood. In this retrospective cohort study, we applied OPAL-based multiplex immunofluorescence (mIF) to human kidney allograft biopsies from 38 recipients with biopsy-proven ABMR (n = 19), T-cell-mediated rejection (TCMR, n = 12), or no rejection (NR, n = 7), enabling spatially resolved quantification of immune subsets in situ. Fluorescence thresholds were pathologist-validated, and co-expression phenotypes were defined using standardized segmentation and spectral unmixing. We observed a significantly higher density of CD1^4+CD11c⁺ monocyte-derived cells in ABMR versus TCMR (p = 0.011), and of cytotoxic CD3⁻PAX8⁻CD16⁺CD57⁺ NK cells in ABMR versus TCMR (p = 0.008), implicating both subsets in ABMR pathogenesis. Spatial clustering of these populations was evident in ABMR biopsies, suggesting organized immune infiltration. A logistic regression model combining both subsets yielded an area under the ROC curve of 0.79 (95% CI: 0.65–0.93), indicating moderate discriminatory power for ABMR. While Cox regression did not reveal statistically significant associations with graft survival, CD3⁻PAX8⁻CD16⁺CD57⁺ cells showed a trend toward increased risk (HR = 2.73, p = 0.09). These findings support a mechanistic role for monocyte and NK cell subsets in ABMR and demonstrate the utility of OPAL mIF for high-resolution immune profiling in human allografts. Our study advances understanding of cellular immune contributors to ABMR and highlights the potential diagnostic value of intragraft mononuclear cell phenotyping. Full article

Peritubular capillaritis (ptc) is a hallmark lesion of antibody-mediated rejection (AMR), but the grading of its extent is historically based on arbitrary defined cut-offs. Molecular AMR diagnosis via intragraft gene expression measurements may provide evidence to challenge established ptc categories. We retrospectively included 38 renal allograft biopsies from clinical routine, performed because of suspicion of AMR. Biopsies were re-assessed by an experienced nephropathologist and intragraft gene expression was measured using the NanoString nCounter^® platform. Ptc categories were correlated with AMR gene expression to identify a ptc extent cut-off with optimal prediction of molecular diagnosis of AMR [gene expression levels above first quartile (AMR^Q>1)]. Finally, an independent validation cohort (n = 25, Erasmus MC, Rotterdam, The Netherlands) was included to reproduce the results. Re-assessment of biopsies revealed AMR in 26/68.4%, mixed rejection in 5/13.2%, and T-cell-mediated rejection in 3/7.9%. Biopsies with diffuse ptc had significantly higher AMR gene expression compared to biopsies with focal ptc and biopsies with no ptc (64.0/53.3–84.0 vs. 31.5/27.0–49.5, p = 0.023 and 27.0/14.3–31.8, p = 0.003, median/IQR). Sensitivity analysis revealed that a ≥35% ptc cut-off resulted in higher AUCs for predicting AMR^Q>1 compared to ptc^50% (AUC 0.78, 95% CI: 0.63–0.93, p = 0.009 versus AUC: 0.74, CI: 0.56–0.90, p = 0.03). In the validation cohort, only the ptc^35–, but not the ptc^50%, cut-off significantly predicted AMR^Q>1 (AUC 0.75, 95% CI: 0.54–0.96 p = 0.04 vs. AUC 0.69, CI: 0.46–0.93, p = 0.13). Using intragraft gene expression measurement, we identified a new ptc extent threshold with better prediction of molecular AMR. The newly proposed cut-off of ≥35% could potentially improve diagnostic evaluation and prognostication in cases with suspected or diagnosed AMR. Full article

Chimeric Antigen Receptor (CAR)-T cell therapy has transformed the treatment landscape of cancer, yet major challenges remain in enhancing efficacy, reducing adverse effects, and expanding accessibility. Autologous CAR-T cells, derived from individual patients, have achieved remarkable clinical success in hematologic malignancies; however, their highly personalized nature limits scalability, increases costs, and delays timely treatment. Allogeneic CAR-T cells generated from healthy donors provide an “off-the-shelf” alternative but face two critical immune barriers: graft-versus-host disease (GvHD), caused by donor T-cell receptor (TCR) recognition of host tissues, and host-versus-graft rejection, mediated by recipient immune responses against donor HLA molecules. Recent advances in genome engineering, particularly Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)/Cas9, allow precise modification of donor T cells to overcome these limitations. For example, TRAC gene knockout eliminates TCR expression, preventing GvHD, while disruption of HLA molecules reduces immunogenicity without impairing cytotoxicity. Beyond hematologic cancers, CRISPR-edited allogeneic CAR-T cells targeting the NKG2D receptor have shown promise in preclinical studies and early-phase trials. NKG2D CAR-T cells recognize stress ligands (MICA/B, ULBP1–6) expressed on over 80% of diverse solid tumors, including pancreatic and ovarian cancers, thereby broadening therapeutic applicability. Nevertheless, the genomic editing process carries risks of off-target effects, including potential disruption of tumor suppressor genes and oncogenes, underscoring the need for stringent safety and quality control. This review examines the distinguishing features of allogeneic versus autologous CAR-T therapy, with a particular focus on NKG2D-based allogeneic CAR-T approaches for solid tumors. We summarize current strategies to mitigate immune barriers, discuss practical manufacturing challenges, and analyze available clinical data on NKG2D CAR-T trials. Collectively, these insights underscore both the promise and the hurdles of developing safe, universal, and scalable allogeneic CAR-T therapies for solid malignancies. Full article

The early secreted antigenic target of 6 kDa (ESAT-6), a main effector molecule of the ESX-1 secretion system, is identified as a virulence determinant and immunoregulatory protein of Mycobacterium tuberculosis (Mtb), affecting the interaction between host immune cells and pathogens. ESAT-6 facilitates the survival of mycobacteria and their cell-to-cell spreading through membrane-permeabilizing activity and the regulation of host immune cell functions. In this review, we first summarize the recent knowledge of the roles of ESAT-6 in the survival of bacteria, phagosomal escape, and pathogenicity during Mtb infection. Then, we focused on its complex immunomodulatory effects on different immune cells, such as macrophages, dendritic cells, neutrophils, and T cells, accentuating its capability to either facilitate or inhibit immune responses through different signaling pathways. While our review has summarized its main roles in immunopathology in the context of tuberculosis, we additionally search for emerging evidence indicating that ESAT-6 has anti-inflammatory and immunosuppressive properties. Particularly, we discuss recent preclinical studies showing its capability to suppress transplant rejection and alloimmunity, probably via the induction of regulatory T cells. Nevertheless, the potential clinical use of ESAT-6 remains uncertain and needs further verification by comprehensive preclinical and clinical studies. Thus, we propose that ESAT-6 may be exploited to ameliorate immunopathology in TB infection and to suppress immune-mediated inflammation or transplant rejection as well. Full article

Background/Objectives: During cancer development, tumor cells accumulate somatic mutations, which could generate tumor-specific neoantigens. The aberrant protein can be recognized by the immune system as no-self, triggering an immune response against cells expressing this aberrant protein which could mediate tumor control or rejection. Since the expression of this mutated protein is exclusive to tumor cells, great efforts are being made to identify neoantigens of relevance in the development of new cancer treatment strategies. In comparison to adulthood tumors, pediatric malignancies present fewer mutations and thus fewer potential neoantigens. Acute lymphoblastic leukemia (ALL) is the most common pediatric malignancy worldwide that can be benefited by the identification of neoantigens for immunotherapy approaches, the landscape of neoantigens in ALL is not well known, therefore the aim of our study was to identify potential neoantigens in ALL pediatric patients. Methods: To identify neoantigens in ALL, whole-exome sequencing of matched tumor-normal cells from pediatric cases was performed, with these data HLA-I alleles predicted and somatic mutations identified to propose potential neoantigens based on binding affinity of mutated peptide-HLA-I. Results: We found a strong correlation between tumor mutational burden (TMB) and neoantigen load (p < 0.001) but no correlation with prognosis. Furthermore, TMB and neoantigens were greater in ALL patients with at least one mutated DNA mismatch repair gene (p < 0.001). Also, differences between B- and T-cell ALL were found but statistical significance did not remain after permutation. Conclusions: The presence of neoantigens in pediatric cases with ALL makes the neoantigen-based immunotherapy a promising new strategy for the treatment of this malignancy, especially for patients with relapse. Full article

Background: Ischemia/reperfusion injury (IRI) is considered one of the major risk factors involved in the development of delayed graft function that significantly impacts both the early and long-term function of allografts due to its harmful effects on cells. Purpose: This narrative review aims to explore the emerging aspects of IRI in organ transplantation, focusing on the still unclear relationships between IRI and the development of both T-cell-mediated and/or antibody-mediated rejections. Key findings: Recently, efforts aimed at increasing the knowledge of the mechanisms involved have revealed that IRI is connected to rejection processes through a complex of interconnected pathways. These pathways affect both the viability and the metabolism of immune cells, ultimately influencing graft outcomes. Therefore, these pathways demonstrate the complexity of immune responses after transplantation and play a role in both acute and chronic rejection processes. Conclusions: Improving graft outcomes requires an understanding of the multifaceted relationship between IRI and immune-mediated rejection, which is critical to improve graft outcomes. Further research is needed to clarify these mechanisms and develop targeted strategies to mitigate IRI and its impact on transplant rejection. Full article

Chimeric Antigen Receptor (CAR) T cell therapy has achieved high response rates in patients with relapsed or refractory hematologic malignancies. However, comparable efficacy in solid tumors remains limited, partly due to poor CAR T cell persistence and immune-mediated rejection. A major contributor, which has hampered the clinical efficacy of CAR T cells in clinical practice, is the immunogenicity of the murine-derived single-chain variable fragments (scFvs) commonly used in CAR constructs. Cell and humoral immune responses to the murine parts of CARs have been implicated in CAR T cell rejection. Here, we describe the generation and in vitro characterization of humanized CAR T cells targeting prostate-specific membrane antigen (PSMA) on prostate cancer cells, based on two distinct murine scFvs (A5 and D7). Humanization improved the germinality index and successfully preserved CAR surface expression. Functional assays demonstrated that humanized PSMA-CAR T cells retained antigen-specific binding, activation and cytotoxicity, differentiation, exhaustion and cytokine secretion profiles comparable to their murine counterparts. These results support the feasibility of humanization as a strategy to reduce immunogenicity without compromising CAR T cell capabilities, providing a foundation for further in vivo validation in solid tumor settings. Full article

Regulatory T cells (Tregs) have anti-inflammatory immunomodulatory activity and hold therapeutic potential for chronic neuroinflammatory neurodegenerative diseases, such as amyotrophic lateral sclerosis (ALS). We are developing engineered human Tregs with enhanced disease-modifying activity for treating ALS. A combination of a disease-specific chimeric antigen receptor (CAR) recognizing misfolded human superoxide dismutase-1 (hSOD1) and constitutive expression of brain-derived neurotrophic factor (BDNF) was tested. The scFv region of CAR demonstrated binding to anterior horn tissues of ALS patients with and without familial ALS mutations in SOD1. Tregs transduced to express BDNF showed the ability to secrete BDNF and protect co-cultured neuronal cells from peroxidase toxicity. Co-expression of BDNF did not inhibit CAR Treg expansion, Treg markers, or CAR-mediated anti-inflammatory cytokine production. Human Tregs co-expressing CAR and BDNF were tested for activity in G93A hSOD1-NSG transgenic mice, which develop an early-onset and aggressive ALS-like disease and do not reject human cells. Human Tregs expressing CAR and BDNF delayed the onset of disease development, extended survival, and decreased spinal cord neuroinflammation. The engineered Tregs showed enhanced disease-modifying activity and hold promise as a therapy for ALS. Full article