Diagnosis Of Rejection Research Articles

ESTADO ACTUAL DEL TRASPLANTE RENAL EN CHILE A 58 AÑOS DEL PRIMERO; “MI VISIÓN”

This article reviews the evolution of kidney transplantation in Chile, beginning with the first successful transplant in 1966 at the University of Chile. It highlights the establishment of kidney transplant programs that predominantly used living donors between 1968 and 1994, culminating in the first combined pancreas-kidney transplant in 1994. The article reviews the historical progression of immunosuppressive therapies, detailing the switch from steroids and azathioprine to cyclosporine, which improved graft survival. Advances in immunologic moni- toring, including the Terasaki crossmatch test and the Luminex procedure, have facilitated early diagnosis of rejection. The new immunosuppressants, Tacrolimus, Rituximab, and Belatacept, which have improved prevention and management of rejection, are discussed. Graft survival rates in Chile are comparable to those in the USA, but problems related to donor recruitment and post-transplant care persist. Finally, emerging alternatives such as xenotransplantation and tissue bioengineering are explored, with challenges to overcome before their clinical application.

PERFECCIONANDO EL DIAGNÓSTICO DE RECHAZO

The mechanisms of acute rejection and its diagnosis are analyzed, and we concluded: The diagnosis of rejection requires a high level of suspicion, knowledge of the patient’s situ- ation and access to different diagnostic approximation techniques. Diagnosis and treatment must be early. Biopsy remains the gold standard for diagnosis. New methods for early diagnosis are in the study and in validation, with many limitations for massification of these techniques and possibly of implementation in our environment. The best prevention of rejection is the selection of a good donor, adequate immunosuppres- sion and monitoring of this, which should be of very low intensity favoring rejection, or of very high intensity exposing the patient to toxicity from it.

Myocarditis diagnosis: From light microscope to molecular analysis and cardiac magnetic resonance.

Myocarditis diagnosis: From light microscope to molecular analysis and cardiac magnetic resonance.

Donor DNA Monitoring for Early Diagnosis of Kidney Transplant Rejection

Donor DNA Monitoring for Early Diagnosis of Kidney Transplant Rejection

Immune responses in rodent whole eye transplantation: elucidation and preliminary investigations into rejection diagnosis and monitoring.

Whole Eye Transplantation (WET) offers potential for vision restoration but is hindered by the complex challenge of immune rejection. Understanding and closely monitoring these immunological responses is crucial for advancing WET. This study delves into the timeline and nature of immune responses in a rodent model of WET without immunosuppression, aiming to elucidate a detailed picture of the immune landscape post-transplantation and establish innovative diagnostic and monitoring methods. We employed a multi-faceted approach to analyze immune responses post-WET, including assessments of gross changes in corneal transparency, thickness, and skin condition. Histopathological examinations of both ocular and surrounding skin tissues provided insights into cellular changes, complemented by ocular RT-qPCR for molecular analysis. Serological analysis was employed to quantify cytokines, chemokines, and donor-specific antibodies, aiming to identify potential biomarkers correlating with WET rejection and to validate the presence of antibody-mediated rejection. These methodologies collectively contribute to the development of non-invasive diagnostic and monitoring strategies for WET. Our study revealed a rapid and acute immune response following WET, characterized by an early innate immune response dominated by complement involvement, and infiltration of neutrophils and monocytes by post-operative day (POD) 2. This was succeeded by an acute T-cell-mediated immune reaction, predominantly involving T helper 1 (Th1) cells and cytotoxic T lymphocytes (CTLs). The presence of donor specific antibody (DSA) and indications of pyroptosis in the early phases of rejection were observed. Notably, the early elevation of serum CXCL10 by POD4, coupled with ocular CD3+ cell infiltration, emerged as a potential early biomarker for WET rejection. Additionally, corneal transparency grading proved effective as a non-invasive monitoring tool. This study offers a first-time comprehensive exploration of immune responses in WET, unveiling rapid and complex rejection mechanisms. The identification of early biomarkers and the development of non-invasive monitoring techniques significantly advance our understanding of WET rejection. Additionally, these findings establish an essential baseline for future research in this evolving field.

Racial Variation of Donor-Derived Cell-Free DNA in Kidney Transplant Recipients.

There is a need for a noninvasive, affordable, sensitive, and specific biomarker to diagnose early acute rejection, to negate the need for frequent biopsies. Dd-cfDNA is a powerful adjunct yet there is limited data on the ethnic differences in its values. There is anecdotal evidence that dd-cfDNA values at rejection may be higher in Black as compared to non-Black recipients. This study aims to add to this literature while defining such variability and comparing it to previously validated cutoffs for dd-cfDNA of 0.5% or 1%. This was a single-center retrospective observational study of patients who underwent graft biopsies with a preceding, paired, dd-cfDNA value. Recipients were separated into White, Black, and Hispanic racial and ethnic groups, and dd-cfDNA values at rejection versus nonrejection were compared. With 0.5% and 1% cutoffs, false negative rates for rejection were 13% and 22%, respectively. The false positive rate was 38.4%. 12.2% of Black recipients, 11.8% of Hispanic recipients, and 44% of White recipients had rejection with a negative AlloSure®. Values >0.5% corresponded to histologic rejection in 61.5% of Black, 66.7% of White, and 56.3% of Hispanic recipients. Antibody-mediated rejection occurred in 65.5% of rejection cases in Black recipients, while exhibiting the lowest rate of T-cell-mediated rejection. Dd-cfDNA values gave an accurate diagnosis of rejection in 52.8% of recipients with AMR versus 19.3% in TCMR. This study demonstrated that dd-cfDNA was applicable to Black recipients with a robust ability to detect antibody-mediated rejection, as compared to White and Hispanic recipients.

Integrating Donor Derived Cell-Free DNA Fraction and Absolute Quantification for Enhanced Rejection Diagnosis in Kidney Transplant Recipients.

Background: This study aimed to assess the diagnostic accuracy of combining donor-derived cell-free DNA (dd-cfDNA) fraction and absolute quantification in detecting kidney allograft rejection. Methods: A prospective study was conducted from December 2019 to April 2021 at the First Affiliated Hospital of Sun Yat-sen University. Kidney transplant recipients who underwent biopsy, including cases of T-cell-mediated rejection (TCMR), antibody-mediated rejection (ABMR), and borderline rejection, were included. dd-cfDNA fraction and absolute concentrations were measured, and diagnostic efficacy was evaluated using receiver operating characteristic (ROC) analysis. The double-positive and double-negative methods were applied to assess performance. Results: A total of 50 kidney transplant recipients were included. The dd-cfDNA fraction cutoff of 1.08% achieved 93.33% sensitivity and 91.43% specificity (AUC = 0.95), with an NPV of 96.97% and a PPV of 82.35%. The absolute dd-cfDNA threshold of 32 cp/mL yielded 80.00% sensitivity and 71.43% specificity (AUC = 0.78), with an NPV of 89.29% and a PPV of 54.55%. The double-positive method provided superior accuracy, with a PPV of 91.67% and an NPV of 89.47%, demonstrating 73.33% sensitivity and 97.14% specificity. The double-negative method achieved 100% NPV and 100% sensitivity. Conclusions: Combining dd-cfDNA fraction and absolute quantification improves diagnostic accuracy for kidney transplant rejection, especially ABMR. The double-positive and double-negative approaches show high predictive value, offering potential clinical value for monitoring kidney transplant recipients.

Timing of rejection events preceded by Covid-19 mRNA vaccination in recipients of solid organ transplants.

SARS-CoV-2 mRNA vaccine reactogenicity has raised concerns regarding the risk of rejection in solid organ transplant recipients. We explored whether SOT recipients diagnosed with acute rejection had previously received a vaccine injection within a timeframe consistent with a causal link. We identified all SOT recipients with a diagnosis of acute rejection from 2020 to 2022 and who had previously received a SARS-CoV-2 vaccination, and analysed whether the delay between vaccination and rejection was constant. In the 45 identified patients, median delay between the last SARS-CoV-2 vaccination and the rejection was 102days [IQR 48-178]; the continuous distribution of this delay, with no identifiable time pattern, is not in favor of a role of vaccination in rejection. SARS-CoV-2 mRNA vaccination is unlikely to trigger rejection in SOT recipients.

Assessing the real-world utility of novel biomarkers and diagnostics in surveillance and diagnosis of allograft rejection in kidney transplant

Assessing the real-world utility of novel biomarkers and diagnostics in surveillance and diagnosis of allograft rejection in kidney transplant

Gene expression profiling in PBMCs for acute rejection in lung transplant recipients reveals myeloid responses.

The acute rejection (AR) diagnosis depends on transbronchial biopsy, which is semi-invasive and not easily performed. Our study used the Nanostring gene expression technology on PBMCs obtained from lung transplant recipients (LTRs) to search for biomarkers. We identified distinct differential gene profiles between patients with stable status (STA) and AR. Subsequently, we independently evaluated monocyte compositions in PBMCs using flow cytometry and assessed the levels of 7 chemokines in serum using Luminex. The 48 top differentially expressed genes (DEGs) were identified, utilizing a criterion of at least a 1.5-fold change between two groups, with a false discovery rate (FDR) p-Adj < 0.05. Of these 48 genes, the top 10 genes with the highest fold changes and significant p-values were selected for qPCR validation. CD68, ANXA1, ITGB, and IFI30 can be confirmed among the validated genes. A significantly lower percentage of CD14 + CD16- classical monocytes was observed in AR than in STA patients, which aligns with downregulated DEGs. Many of the DEGs were related to monocytes-macrophages and chemokines. Although these results still need to be confirmed in larger cohorts, they suggest that gene profiling of PBMC can help to identify markers related to AR in LTRs.

Emerging role of circulating piRNAs in the diagnosis of heart transplant rejection.

Emerging role of circulating piRNAs in the diagnosis of heart transplant rejection.

Donor-derived cell-free DNA monitoring for early diagnosis of antibody-mediated rejection after kidney transplantation: a randomized trial.

Donor-derived cell-free DNA (dd-cfDNA) shows good diagnostic performance for the detection of antibody-mediated rejection (AMR) in kidney transplant recipients (KTR). However, the clinical benefits of dd-cfDNA monitoring need to be established. Early diagnosis of AMR at potentially reversible stages may be increasingly important due to emerging treatment options for AMR.We hypothesized that monitoring dd-cfDNA in KTR with de novo donor-specific anti-HLA antibodies (dnDSA) and performing kidney biopsy in case of increased dd-cfDNA may reduce time to AMR diagnosis in comparison to clinical indication biopsy. In this diagnostic, single-center, open-label, randomized clinical trial, we assigned 40 KTR with prevalent dnDSA and estimated glomerular filtration rate ≥20mL/min/1.73m2, but without previous biopsy-proven AMR, to either dd-cfDNA-guided biopsy (intervention group) or clinician-guided biopsy (control group) over a 12-months period. In both groups, dd-cfDNA was assessed at inclusion and 1, 3, 6, 9, and 12 months. In the intervention group, dd-cfDNA>50cp/mL indicated a biopsy. Biopsies for clinical indication could be performed at any point during the study period in both groups. A protocol biopsy was scheduled after 12 months for patients without dd-cfDNA-guided biopsy or clinical indication biopsy until study completion. The primary endpoint was time from study inclusion to diagnosis of active or chronic active AMR. 39/40 patients had functioning grafts at study completion. From these, 26 patients underwent biopsy, 13 in each group. AMR was diagnosed earlier in the intervention group than in the control group (median 2.8 months, IQR 1.7-5.3vs. median 14.5 months, IQR 13.3-16.7, p=0.003). Longitudinal dd-cfDNA monitoring had 77% positive predictive value and 85% negative predictive value for AMR. Dd-cfDNA-guided biopsy in KTR with prevalent dnDSA can reduce the time to AMR diagnosis and hereby expedite therapy initiation. (NCT04897438).

Current and emerging tools for simultaneous assessment of infection and rejection risk in transplantation.

Infection and rejection are major complications that impact transplant longevity and recipient survival. Balancing their risks is a significant challenge for clinicians. Current strategies aimed at interrogating the degree of immune deficiency or activation and their attendant risks of infection and rejection are imprecise. These include immune (cell counts, function and subsets, immunoglobulin levels) and non-immune (drug levels, viral loads) markers. The shared risk factors between infection and rejection and the bidirectional and intricate relationship between both entities further complicate transplant recipient care and decision-making. Understanding the dynamic changes in the underlying net state of immunity and the overall risk of both complications in parallel is key to optimizing outcomes. The allograft biopsy is the current gold standard for the diagnosis of rejection but is associated with inherent risks that warrant careful consideration. Several biomarkers, in particular, donor derived cell-free-DNA and urinary chemokines (CXCL9 and CXCL10), show significant promise in improving subclinical and clinical rejection risk prediction, which may reduce the need for allograft biopsies in some situations. Integrating conventional and emerging risk assessment tools can help stratify the individual's short- and longer-term infection and rejection risks in parallel. Individuals identified as having a low risk of rejection may tolerate immunosuppression wean to reduce medication-related toxicity. Serial monitoring following immunosuppression reduction or escalation with minimally invasive tools can help mitigate infection and rejection risks and allow for timely diagnosis and treatment of these complications, ultimately improving allograft and patient outcomes.

Decreasing Endomyocardial Biopsy Frequency in Pediatric Heart Transplantation Using A Rejection Risk Prediction Score-A Single Center Study.

Rejection remains an important cause of morbidity and mortality after pediatric heart transplantation (HT). Endomyocardial biopsy (EMB) is the gold standard for rejection diagnosis, but it comes with procedural risk. The frequency of EMB varies significantly across centers. Since April 2018, our center's surveillance EMB schedule is based on a rejection risk prediction score employing age, pre-HT diagnosis, and panel reactive antibodies (PRA). We aimed to evaluate outcomes in the 1st year post-HT before and after risk score implementation. Patients who underwent HT at our center at ≤ 18 years of age from January 2015 to December 2020 were reviewed. The primary endpoint was rejection-free survival at 1 year-post- HT. Clinical characteristics were compared for patients transplanted in Era 1 (January 2015-April 2018) and Era 2 (April 2018-December 2020). Cumulative 1-year survival free from rejection and from rejection with hemodynamic compromise (RHC) was compared between eras using Kaplan-Meier survival analysis. 115 patients underwent HT during our study period (52 in Era 1 and 63 in Era 2). There was an increase in VAD utilization between eras (19% in Era 1 vs. 40% in Era 2, p = 0.025), but otherwise no significant difference in demographic or clinical variables between the two eras. No statistically significant difference in freedom from rejection or freedom from RHC was identified between the two eras. There was a 60% reduction in the median number of EMB per patient in the first year post-HT after employing the score (5 in Era 1 vs. 2 in Era 2, p < 0.001). After employing a rejection risk prediction score, our center decreased the frequency of EMB without worsening early post-HT outcomes, thus establishing the clinical applicability of this tool.

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

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. 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. 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). 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.

A review of cell-free DNA and epigenetics for non-invasive diagnosis in solid organ transplantation.

Circulating cell-free DNA (cfDNA) is emerging as a non-invasive biomarker in solid organ transplantation (SOT) monitoring and data on its diagnostic potential have been increasing in recent years. This review aims to summarize the main advances in technologies, clinical applications and future perspectives of cfDNA for transplantation, and to approach the contribution of epigenetics to improve the specific detection of rejection. Published literature investigating cfDNA as a biomarker for the diagnosis of transplant rejection was systematically reviewed, specifically clinical trials evaluating the test performance of algorithms predicting rejection based on cfDNA fraction. Literature highlighting epigenetic features in transplant rejection was also reviewed to outline the potential contribution of the epigenomic analysis to the needs of rejection-specific diagnosis. 40 articles were reviewed, and results were extracted and summarized. 16 met the inclusion criteria by evaluating the diagnostic performance of a predictive test for the discrimination of rejection vs. non-rejection patients (2 heart, 3 liver, 4 kidney, and 7 lung transplantations). The recurring conclusion is the kinetics of dd-cfDNA levels, strongly increasing immediately after transplantation and reaching basal levels after days to weeks and remaining stable in non-rejection patients. On the other hand, rejection is characterized by an increase in dd-cfDNA levels, depending on the transplanted organs. In addition, the epigenetic signature can help improve the specificity of the diagnosis of rejection by searching for specific epigenetic features that are by the clinical status of patients. Cell-free DNA is a promising non-invasive biomarker but still needs standardization of technologies and protocols to be used for diagnostic purposes. Moreover, the lack of specificity of this marker can be compensated by the contribution of epigenetic analysis for which data are growing, although progress is still needed for its use in a clinical context.

Transition from Transbronchial Forceps to Cryobiopsy After Lung Transplantation: A Single-Centre Experience.

The gold standard for histological acute cellular rejection diagnosis is transbronchial forceps biopsy (FB), but in recent years, transbronchial cryobiopsy (CB) has been increasingly used. This study aims to compare the diagnostic rate and safety of FBs and CBs performed in two different periods. We retrospectively reviewed our case history for the two biopsy procedures: 251 FBs (223 for surveillance purposes and 28 for clinical indication) and 218 consecutive CBs (159 for surveillance purposes and 59 for clinical indication). All biopsies were scored according to the ISHLT criteria. Diagnostic yield was higher in the CB group for all the parameters considered: a grade of acute rejection (AR) was detected in 95.0% vs. 84.5% in the CB vs. FB groups (p < 0.001). The diagnostic rate of airway inflammation was 65.1% vs. 51.8% (p = 0.005), and 89.0% vs. 64.9% (p < 0.001) for chronic rejection. Pneumothorax requiring chest drainage occurred in 4% of the CB group and 3% of the FB group. Moderate and severe bleeding complicated CB and FB procedures in seven (3%) and three cases (1%), respectively. Transbronchial cryobiopsies improved the diagnostic yield in the monitoring of the lung allograft. The complication rate did not increase significantly in CBs vs. FBs.

The Use of Machine Learning in the Diagnosis of Kidney Allograft Rejection: Current Knowledge and Applications.

Kidney allograft rejection is one of the main limitations to long-term kidney transplant survival. The diagnostic gold standard for detecting rejection is a kidney biopsy, an invasive procedure that can often give imprecise results due to complex diagnostic criteria and high interobserver variability. In recent years, several additional diagnostic approaches to rejection have been investigated, some of them with the aid of machine learning (ML). In this review, we addressed studies that investigated the detection of kidney allograft rejection over the last decade using various ML algorithms. Various ML techniques were used in three main categories: (a) histopathologic assessment of kidney tissue with the aim to improve the diagnostic accuracy of a kidney biopsy, (b) assessment of gene expression in rejected kidney tissue or peripheral blood and the development of diagnostic classifiers based on these data, (c) radiologic assessment of kidney tissue using diffusion-weighted magnetic resonance imaging and the construction of a computer-aided diagnostic system. In histopathology, ML algorithms could serve as a support to the pathologist to avoid misclassifications and overcome interobserver variability. Diagnostic platforms based on biopsy-based transcripts serve as a supplement to a kidney biopsy, especially in cases where histopathologic diagnosis is inconclusive. ML models based on radiologic evaluation or gene signature in peripheral blood may be useful in cases where kidney biopsy is contraindicated in addition to other non-invasive biomarkers. The implementation of ML-based diagnostic methods is usually slow and undertaken with caution considering ethical and legal issues. In summary, the approach to the diagnosis of rejection should be individualized and based on all available diagnostic tools (including ML-based), leaving the responsibility for over- and under-treatment in the hands of the clinician.

Application of spatial-omics to the classification of kidney biopsy samples in transplantation.

Improvement of long-term outcomes through targeted treatment is a primary concern in kidney transplant medicine. Currently, the validation of a rejection diagnosis and subsequent treatment depends on the histological assessment of allograft biopsy samples, according to the Banff classification system. However, the lack of (early) disease-specific tissue markers hinders accurate diagnosis and thus timely intervention. This challenge mainly results from an incomplete understanding of the pathophysiological processes underlying late allograft failure. Integration of large-scale multimodal approaches for investigating allograft biopsy samples might offer new insights into this pathophysiology, which are necessary for the identification of novel therapeutic targets and the development of tailored immunotherapeutic interventions. Several omics technologies - including transcriptomic, proteomic, lipidomic and metabolomic tools (and multimodal data analysis strategies) - can be applied to allograft biopsy investigation. However, despite their successful application in research settings and their potential clinical value, several barriers limit the broad implementation of many of these tools into clinical practice. Among spatial-omics technologies, mass spectrometry imaging, which is under-represented in the transplant field, has the potential to enable multi-omics investigations that might expand the insights gained with current clinical analysis technologies.

Heart Transplant Rejection in the Setting of Glyphosate Herbicide Exposure; A Case Report

Glyphosate is a common herbicide utilized worldwide with known exposure related toxicities. Numerous adverse effects related to glyphosate exposure have been documented, specifically in non-human models, however literature is lacking on cardiotoxic effects specific to heart transplant patients. Rejection is the most common post-transplant complication and the diagnosis of such is vital in order to guide immediate and appropriate treatment. In addition to the endomyocardial biopsy, noninvasive genetic testing can aid in rejection diagnosis and distinguish between cell-mediated and antibody-mediated rejection. We describe a case of glyphosate exposure in a post orthotopic heart transplant and the subsequent heart transplant rejection, patient’s clinical course, treatment, and follow up.