Longitudinal Lower Airway Microbial Signatures of Acute Cellular Rejection in Lung Transplantation.

Rationale: Acute cellular rejection (ACR) after lung transplant is a leading risk factor for chronic lung allograft dysfunction. Prior studies have demonstrated dynamic microbial changes occurring within the allograft and gut that influence local adaptive and innate immune responses. However, the lung microbiome's overall impact on ACR risk remains poorly understood. Objectives: To evaluate whether temporal changes in microbial signatures were associated with the development of ACR. Methods: We performed cross-sectional and longitudinal analyses (joint modeling of longitudinal and time-to-event data and trajectory comparisons) of 16S rRNA gene sequencing results derived from lung transplant recipient lower airway samples collected at multiple time points. Measurements and Main Results: Among 103 lung transplant recipients, 25 (24.3%) developed ACR. In comparing samples acquired 1 month after transplant, subjects who never developed ACR demonstrated lower airway enrichment with several oral commensals (e.g., Prevotella and Veillonella spp.) than those with current or future (beyond 1 mo) ACR. However, a subgroup analysis of those who developed ACR beyond 1 month revealed delayed enrichment with oral commensals occurring at the time of ACR diagnosis compared with baseline, when enrichment with more traditionally pathogenic taxa was present. In longitudinal models, dynamic changes in α-diversity (characterized by an initial decrease and a subsequent increase) and in the taxonomic trajectories of numerous oral commensals were more commonly observed in subjects with ACR. Conclusions: Dynamic changes in the lower airway microbiota are associated with the development of ACR, supporting its potential role as a useful biomarker or in ACR pathogenesis.

Circulating T cell specific extracellular vesicle profiles in cardiac allograft acute cellular rejection.

There is a critical need for biomarkers of acute cellular rejection (ACR) in organ transplantation. We hypothesized that ACR leads to changes in donor-reactive T cell small extracellular vesicle (sEV) profiles in transplant recipient circulation that match the kinetics of alloreactive T cell activation. In rodent heart transplantation, circulating T cell sEV quantities (P < .0001) and their protein and mRNA cargoes showed time-specific expression of alloreactive and regulatory markers heralding early ACR in allogeneic transplant recipients but not in syngeneic transplant recipients. Next generation sequencing of their microRNA cargoes identified novel candidate biomarkers of ACR, which were validated by stem loop quantitative reverse transcription polymerase chain reaction (n = 10). Circulating T cell sEVs enriched from allogeneic transplant recipients mediated targeted cytotoxicity of donor cardiomyocytes by apoptosis assay (P < .0001). Translation of the concept and EV methodologies to clinical heart transplantation demonstrated similar upregulation of circulating T cell sEV profiles at time points of grade 2 ACR (n = 3 patients). Furthermore, T cell receptor sequencing of T cell sEV mRNA cargo demonstrated expression of T cell clones with intact complementarity determining region 3 signals. These data support the diagnostic potential of T cell sEVs as noninvasive biomarker of ACR and suggest their potential functional roles.

Kidney after liver transplantation does not have an increased risk of rejection compared to liver alone.

BACKGROUND: Simultaneous liver kidney (SLK) transplant protects against acute cellular rejection. In 2017, UNOS implemented a "safety net" policy to allow patients with renal recovery to avoid renal transplantation. Whether kidney after liver transplantation (KALT) increases the risk of rejection is unknown. METHODS: We performed a retrospective analysis of the Organ Procurement and Transplantation Network (OPTN) database of adult patients who received liver transplant, SLK or KALT between 2010 and 2020. We examined rejection of the liver within 6 months and 1 year of the liver transplant, as well as rejection of the kidney within 6 months and 1 year of receiving the kidney, as well as patient and graft loss. RESULTS: Sixty-six thousand seventy-nine patients were transplanted; 60 168 with liver transplant alone, 5627 with SLK, and 284 with KALT. Acute or chronic liver rejection rates within 6 or 12 months were statistically higher in the KALT group (10.0% and 10.9%) compared to the SLK group (6.1% and 7.5%), but comparable to the LTA group (9.3% and 11.1%). Kidney rejection and graft survival rates were not different. Liver graft survival was worse in KALT than SLK or LTA (Kaplan-Meier estimates .61 vs. .89 and .90), but these patients were more ill at the time of transplantation. KDPI and LDRI scores were notably lower in the SLK than KALT group. Patient survival was not clinically different between the groups. CONCLUSION: KALT does not increase the risk of acute or chronic kidney rejection. SLK has a lower risk of early liver rejection, but this effect diminishes by one year to being not clinically different compared to KALT. Given that KALT is immunologically safe, and potentially avoids unnecessary renal graft use, it should be preferred over SLK. BRIEF SUMMARY: Patients undergoing sequential kidney after liver transplant do not have an increased risk of liver or kidney rejection when compared to liver transplant alone or simultaneous liver and kidney transplant.

Treatment Responses in Histologic Versus Molecular Diagnoses of Lung Rejection.

Histologic evaluation of allograft biopsies after lung transplantation has several limitations, suggesting that molecular assessment using tissue transcriptomics could improve biopsy interpretation. This single-center, retrospective cohort study evaluated discrepancies between the histology of transbronchial biopsies (TBBs) with no rejection (NR) and T-cell mediated rejection (TCMR) by molecular diagnosis. The accuracy of diagnosis was assessed based on response to treatment. 54 TBBs from Prague Lung Transplant Program obtained between December 2015 and January 2020 were included. Patients with acute cellular rejection (ACR) grade ≥ 1 by histology received anti-rejection treatment. Response to therapy was defined as an increase in FEV1 of ≥ 10% 4 weeks post-biopsy compared to the pre-biopsy value. Among the 54 analyzed TBBs, 25 (46%) were concordant with histology, while 29 (54%) showed discrepancies. ACR grade 0 was found in 12 TBBs (22%) and grade A1 ≥ 1 in 42 TBBs (78%). Treatment response was present in 14% in the NR group and in 50% in the TCMR group (p = 0.024). Our findings suggest that low-grade acute cellular rejection is less likely to be associated with molecular TCMR, which might better identify lung transplant recipients who benefit from therapy.

Daratumumab Use Prior to Kidney Transplant and T Cell-Mediated Rejection: A Case Report.

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.

Unsupervised mRNA-seq classification of heart transplant endomyocardial biopsies.

BACKGROUND: Endomyocardial biopsy (EMB) is currently considered the gold standard for diagnosing cardiac allograft rejection. However, significant limitations related to histological interpretation variability are well-recognized. We sought to develop a methodology to evaluate EMB solely based on gene expression, without relying on histology interpretation. METHODS: Sixty-four EMBs were obtained from 47 post-heart transplant recipients, who were evaluated for allograft rejection. EMBs were subjected to mRNA sequencing, in which an unsupervised classification algorithm was used to identify the molecular signatures that best classified the EMBs. Cytokine and natriuretic peptide peripheral blood profiling was also performed. Subsequently, we performed gene network analysis to identify the gene modules and gene ontology to understand their biological relevance. We correlated our findings with the unsupervised and histological classifications. RESULTS: Our algorithm classifies EMBs into three categories based solely on clusters of gene expression: unsupervised classes 1, 2, and 3. Unsupervised and histological classifications were closely related, with stronger gene module-phenotype correlations for the unsupervised classes. Gene ontology enrichment analysis revealed processes impacting on the regulation of cardiac and mitochondrial function, immune response, and tissue injury response. Significant levels of cytokines and natriuretic peptides were detected following the unsupervised classification. CONCLUSION: We have developed an unsupervised algorithm that classifies EMBs into three distinct categories, without relying on histology interpretation. These categories were highly correlated with mitochondrial, immune, and tissue injury response. Significant cytokine and natriuretic peptide levels were detected within the unsupervised classification. If further validated, the unsupervised classification could offer a more objective EMB evaluation.

Comparison of two donor-derived cell-free DNA tests and a blood gene-expression profile test in heart transplantation.

BACKGROUND: Donor-derived cell-free DNA (dd-cfDNA) testing is an emerging screening modality for noninvasive detection of acute rejection (AR). This study compared the testing accuracy for AR of two commercially available dd-cfDNA and gene-expression profiling (GEP) testing in heart transplant (HTx) recipients. METHODS: This is a retrospective, observational study of HTx only patients who underwent standard and expanded single nucleotide polymorphism (SNP) dd-cfDNA between October 2020 to January 2022. Comparison with GEP was also performed. Assays were compared for correlation, accurate classification, and prediction for AR. RESULTS: A total of 428 samples from 112 unique HTx patients were used for the study. A positive standard SNP correlated with the expanded SNP assay (p < .001). Both standard and expanded SNP tests showed low sensitivity (39%, p = 1.0) but high specificity (82% and 84%, p = 1.0) for AR. GEP did not improve sensitivity and showed worse specificity (p < .001) compared to standard dd-cfDNA. CONCLUSION: We found no significant difference between standard and expanded SNP assays in detecting AR. We show improved specificity without change in sensitivity using dd-cfDNA in place of GEP testing. Prospective controlled studies to address how to best implement dd-cfDNA testing into clinical practice are needed.

Effective treatment of diabetes, improved quality of life and accelerated cognitive development after pancreas transplantation in a child with type 1 diabetes and allergy to manufactured insulin preparations.

BACKGROUND: Insulin hypersensitivity reactions are rare but serious and significantly affect the treatment of diabetes in children. METHODS: A 13-year-old girl with type 1 diabetes, hypoglycemic unawareness, and treatment refractory allergy to available insulin preparations underwent a solitary pancreas transplant. Before the pancreas transplantation, she was receiving a continuous subcutaneous infusion of rapid-acting insulin with an increasing need for antihistamines and steroids, negatively impacting her cognitive and social development. Her diabetes was poorly controlled, and her quality of life was progressively worsening. RESULTS: Following the transplant, she recovered well from surgery and achieved euglycemia without needing exogenous insulin. She had two biopsy proven episodes of acute cellular rejection, successfully treated. Her cognitive development also accelerated. Notable improvement was noted both in her personal quality of life and her family's overall well-being. CONCLUSIONS: This is the youngest pancreas transplant recipient with over 1-year graft survival reported in the literature. Pancreas transplant alone in a teenager without indications for kidney transplantation could be considered a last resort treatment for diabetes when continuing insulin therapy presents a high level of morbidity. A pancreas transplant is a feasible treatment modality for patients with refractory insulin allergy.

T-cell infiltrate intensity is associated with delayed response to treatment in late acute cellular rejection in pediatric liver transplant recipients.

BACKGROUND: Late acute cellular rejection (ACR) is associated with donor-specific antibodies (DSA) development, chronic rejection, and allograft loss. However, accurate predictors of late ACR treatment response are lacking. ACR is primarily T-cell mediated, yet B cells and plasma cells (PC) also infiltrate the portal areas during late ACR. To test the hypothesis that the inflammatory milieu is associated with delayed response (DR) to rejection therapy, we performed a single-center retrospective case-control study of pediatric late liver ACR using multiparameter immunofluorescence for CD4, CD8, CD68, CD20, and CD138 to identify immune cell subpopulations. METHODS: Pediatric liver transplant recipients transplanted at <17 years of age and treated for biopsy-proven late ACR between January 2014 and 2019 were stratified into rapid response (RR) and DR based on alanine aminotransferase (ALT) normalization within 30 days of diagnosis. All patients received IV methylprednisolone as an initial rejection treatment. Immunofluorescence was performed on archived formalin-fixed paraffin embedded (FFPE) liver biopsy tissue. RESULTS: Liver biopsies from 60 episodes of late ACR in 54 patients were included in the analysis, of which 33 were DR (55%). Anti-thymocyte globulin was only required in the DR group. The frequency of liver-infiltrating CD20+ and CD8+ lymphocytes and the prevalence of autoantibodies were higher in the DR group. In univariate logistic regression analysis, serum gamma-glutamyl transpeptidase (GGT) level at diagnosis, but not ALT, Banff score or presence of DSA, predicted DR. CONCLUSIONS: Higher serum GGT level, presence of autoantibodies, and increased CD8+ T-cell infiltration portends DR in late ACR treatment in children.

Successful Treatment with Letermovir in a Heart Transplant Recipient with UL97 Mutation Ganciclovir-Resistant Cytomegalovirus Colitis and Viremia.

Currently available anti-cytomegalovirus (CMV) agents are sometimes poorly tolerated, owing to their side effects. Letermovir is a novel anti-CMV drug that is only approved for CMV prophylaxis in hematopoietic stem cell transplant recipients, with fewer side effects. We report the case of a heart transplant recipient with UL97 mutation (L595F) ganciclovir-resistant cytomegalovirus colitis who was successfully treated with off-label use of letermovir. In treating CMV infection or disease with letermovir, a transient rise or lag in the clearance of CMV-DNA polymerase chain reaction levels has been observed. Our case suggests that CMV-pp65 antigenemia can be an additional marker of treatment efficacy.

Isolation of Structurally Heterogeneous TCR-CD3 Extracellular Vesicle Subpopulations Using Caliper Strategy.

Cells in different states can release diverse types of extracellular vesicles (EVs) that participate in intracellular communication or pathological processes. The identification and isolation of EV subpopulations are significant to explore their physiological functions and clinical value. In this study, structurally heterogeneous T-cell receptor (TCR)-CD3 EVs were proposed and verified for the first time using a caliper strategy. Two CD3-targeting aptamers were designed in the shape of a caliper with an optimized probe distance and were assembled on gold nanoparticles (Au-Caliper) to distinguish TCR-CD3 monomeric and dimeric EVs (m/dCD3 EVs) in skin-transplanted mouse plasma. Phenotyping and sequencing analysis revealed clear heterogeneity in the isolated m/dCD3 EVs, providing the potential for mCD3 EVs as a candidate biomarker of acute cellular rejection (ACR) and holding great prospects for distinguishing EV subpopulations based on protein oligomerization states.

Use of blood oxygen level-dependent magnetic resonance imaging to detect acute cellular rejection post-liver transplantation.

OBJECTIVES: Acute cellular rejection (ACR) is a major immune occurrence post-liver transplant that can cause abnormal liver function. Blood oxygen level-dependent (BOLD) magnetic resonance imaging (MRI) can be used to evaluate liver disease, but it has not been utilized in the diagnosis of ACR post-liver transplant. Therefore, the purpose of this study is to evaluate the diagnostic performance of BOLD MRI and to monitor treatment response in recipients with ACR. METHODS: This prospective study was approved by the local institutional review board. Fifty-five recipients with highly suspected ACR were enrolled in this study. Each patient underwent hepatic BOLD MRI, blood biochemistry, and biopsy before treatment. Of 55 patients, 19 recipients with ACR received a follow-up MRI after treatment. After obtaining the R2* maps, five regions-of-interest were placed on liver parenchyma to estimate the mean R2* values for statistical analysis. Receiver operating characteristic curve (ROC) analysis was performed to assess the diagnostic performance of R2* values in detecting patients with ACR. RESULTS: The histopathologic results showed that 27 recipients had ACR (14 mild, 11 moderate, and 2 severe) and their hepatic R2* values were significantly lower than those of patients without ACR. ROC analysis revealed that the sensitivity and specificity of the R2* values for detection of ACR were 82.1% and 89.9%, respectively. Moreover, the R2* values and liver function in patients with ACR significantly increased after immunosuppressive treatment. CONCLUSION: The non-invasive BOLD MRI technique may be useful for assessment of hepatic ACR and monitoring of treatment response after immunosuppressive therapy. KEY POINTS: • Patients with acute cellular rejection post-liver transplant exhibited significantly decreased R2* values in liver parenchyma. • R2* values and liver function were significantly increased after immunosuppressive therapy. • R2* values were constructive indicators in detecting acute cellular rejection due to their high sensitivity and specificity.

The optimal immunosuppression management to prevent early rejection after liver transplantation: A systematic review of the literature and expert panel recommendations.

BACKGROUND: The optimal immunosuppression protocol to prevent early acute cellular rejection (ACR) after liver transplantation (LT) avoiding prolonged hospitalization and early hospital readmission is undefined. OBJECTIVES: To identify the most suitable immunosuppression regimen for inclusion in ERAS programs in order to minimize early ACR after LT and to provide expert panel recommendations DATA SOURCES: Ovid MEDLINE, Embase, Scopus, Google Scholar, and Cochrane Central. METHODS: Systematic review following PRISMA guidelines and recommendations using the GRADE approach derived from an international expert panel. Studies from January 2000 onward focusing on early ACR were included. Rates of early renal dysfunction and infection were evaluated. CRD42021245586 RESULTS: Thirty-seven studies met inclusion criteria; 23 randomized controlled trials, 14 retrospective or prospective observational comparative or noncomparative studies. Several sources of biases which potentially confound conclusions were identified: heterogeneity in immunosuppression protocols, higher serum tacrolimus levels than currently used in clinical practice, differences in the definition of ACR. CONCLUSIONS: Tacrolimus is the standard immunosuppression after LT and can be used in combination with other drugs such as corticosteroids and MMF, and in association with anti-IL2 receptor antibody (IL2Ra) induction. (Quality of Evidence; Low | Grade of Recommendation; Strong). Low dose or delayed introduction of tacrolimus in association with corticosteroids and MMF and/or anti-IL2Ra induction can be used to reduce acute kidney injury. (Quality of Evidence; Low | Grade of Recommendation; Strong). Use of tacrolimus in association with corticosteroids and MMF and/or anti-IL2Ra induction does not lead to increased infection rates. (Quality of Evidence; Low | Grade of Recommendation; Weak).

Association of tacrolimus time-to-therapeutic range on renal dysfunction and acute cellular rejection after orthotopic heart transplantation in a high use basiliximab population.

BACKGROUND: Currently, clinicians often delay initiation of tacrolimus after orthotopic heart transplantation (OHT) to help mitigate nephrotoxicity. This study aimed to determine if there is an association between the time-to-therapeutic range (TTT) of tacrolimus, early renal dysfunction, and acute cellular rejection (ACR) after OHT. METHODS: This was a retrospective, single center study with adult patients who underwent OHT from July 2013 to April 2020. Logistic regression analysis was utilized to examine the association of TTT with new renal dysfunction after tacrolimus initiation post-OHT. RESULTS: In a study of 317 patients, the unadjusted analysis showed patients who developed new renal dysfunction after tacrolimus initiation had a numerically shorter TTT (9.5 vs. 11.0 days, P = .065), and were more likely to have supratherapeutic tacrolimus levels (56% vs. 39.2%, P = .010). When adjusted for established risk factors for renal dysfunction, TTT was significantly associated with new renal dysfunction (OR .95; 95% CI [.90, .99], P = .03). There was no association between TTT and the incidence of ACR (11.1 vs. 10.8 days, P = .64). CONCLUSION: When adjusting for known risk factors, a shorter TTT was associated with new renal dysfunction. Supratherapeutic tacrolimus levels were also associated with new renal dysfunction. There was no association between TTT and ACR in the setting of high use basiliximab induction.

Elevated Cardiac Troponin to Detect Acute Cellular Rejection After Cardiac Transplantation: A Systematic Review and Meta-Analysis.

Cardiac troponin is well known as a highly specific marker of cardiomyocyte damage, and has significant diagnostic accuracy in many cardiac conditions. However, the value of elevated recipient troponin in diagnosing adverse outcomes in heart transplant recipients is uncertain. We searched MEDLINE (Ovid), Embase (Ovid), and the Cochrane Library from inception until December 2020. We generated summary sensitivity, specificity, and Bayesian areas under the curve (BAUC) using bivariate Bayesian modelling, and standardised mean differences (SMDs) to quantify the diagnostic relationship of recipient troponin and adverse outcomes following cardiac transplant. We included 27 studies with 1,684 cardiac transplant recipients. Patients with acute rejection had a statistically significant late elevation in standardised troponin measurements taken at least 1 month postoperatively (SMD 0.98, 95% CI 0.33-1.64). However, pooled diagnostic accuracy was poor (sensitivity 0.414, 95% CrI 0.174-0.696; specificity 0.785, 95% CrI 0.567-0.912; BAUC 0.607, 95% CrI 0.469-0.723). In summary, late troponin elevation in heart transplant recipients is associated with acute cellular rejection in adults, but its stand-alone diagnostic accuracy is poor. Further research is needed to assess its performance in predictive modelling of adverse outcomes following cardiac transplant. Systematic Review Registration: identifier CRD42021227861.

Serial assessment of right ventricular function can detect acute cellular rejection in children with heart transplantation.

BACKGROUND: Echocardiographic markers of ACR are essential for early recognition and management. The literature's primary focus has been on the LV with little attention given to the RV. This study aimed to investigate echocardiographic right ventricular indices in the detection of ACR and to evaluate their utility as prognostic indicators of graft integrity. METHODS: We performed a retrospective chart review of children with biopsy-proven ACR following orthotopic heart transplant and an echocardiogram within 24 h of biopsy. Selected echocardiographic markers were compared at baseline, during ACR, and at follow-up. RESULTS: Forty-eight patients (56% male) had a total of 84 ACR episodes. Decrease in RV FAC (mean - 17.1%, p < .001) and TAPSE (mean - 8.9%, p < .001) with increase in left ventricular posterior wall thickness in diastole and systole (LVPWTd) (mean + 9.0%, p = .012) and LVPWTs (mean + 8.3%, p = .016) were found during ACR. Interestingly, these parameters improved following the episode of rejection. Additionally, these markers were compared after recovery between children with and without graft failure. RV dysfunction (FAC and TAPSE) and changes in LV posterior wall thickness were not found to have prognostic significance for graft integrity in children with heart transplantation. CONCLUSIONS: RV echocardiographic functional parameters should be considered as valuable adjuncts in rejection surveillance. Further, the presence of RV dysfunction does not have prognostic significance for graft integrity but is reversible as ongoing damage was not detectable by such.

Rapid clearance of tacrolimus blood concentration triggered by variant pharmacogenes.

WHAT IS KNOWN AND OBJECTIVE: Tacrolimus (TAC) is an immunosuppressant with large interpatient pharmacokinetic variability and a narrow therapeutic index. We report a case of acute cellular rejection (ACR) type IB with insufficient TAC blood concentrations (TAC C0 ). CASE SUMMARY: ACR developed on the eighth postoperative day of kidney transplantation. During this period, TAC C0 were insufficient. This referred pharmacogenetic assessment disclosed the patient as a CYP3A5 expresser and CYP3A4*1B carrier. According to the genotype, higher doses of TAC, 15 mg twice daily, were administered and targeted TAC C0 were achieved. WHAT IS NEW AND CONCLUSION: Our case presents an association of TAC rapid clearance and two alleles modifying greater CYP3A enzyme activity.

Identification of peripheral CD154+ T cells and HLA-DRB1 as biomarkers of acute cellular rejection in adult liver transplant recipients.

Decreasing graft rejection and increasing graft and patient survival are great challenges facing liver transplantation (LT). Different T cell subsets participate in the acute cellular rejection (ACR) of the allograft. Cell-mediated immunity markers of the recipient could help to understand the mechanisms underlying acute rejection. This study aimed to analyse different surface antigens on T cells in a cohort of adult liver patients undergoing LT to determine the influence on ACR using multi-parametric flow cytometry functional assay. Thirty patients were monitored at baseline and during 1 year post-transplant. Two groups were established, with (ACR) and without (NACR) acute cellular rejection. Leukocyte, total lymphocyte, percentages of CD4+ CD154+ and CD8+ CD154+ T cells, human leukocyte antigen (HLA) mismatch between recipient-donor and their relation with ACR as well as the acute rejection frequencies were analysed. T cells were stimulated with concanavalin A (Con-A) and surface antigens were analysed by fluorescence activated cell sorter (FACS) analysis. A high percentage of CD4+ CD154+ T cells (P = 0·001) and a low percentage of CD8+ CD154+ T cells (P = 0·002) at baseline were statistically significant in ACR. A receiver operating characteristic analysis determined the cut-off values capable to stratify patients at high risk of ACR with high sensitivity and specificity for CD4+ CD154+ (P = 0·001) and CD8+ CD154+ T cells (P = 0·002). In logistic regression analysis, CD4+ CD154+ , CD8+ CD154+ and HLA mismatch were confirmed as independent risk factors to ACR. Post-transplant percentages of both T cell subsets were significantly higher in ACR, despite variations compared to pretransplant. These findings support the selection of candidates for LT based on the pretransplant percentages of CD4+ CD154+ and CD8+ CD154+ T cells in parallel with other transplant factors.

Temporal dynamics of the plasma microbiome in recipients at early post-liver transplantation: a retrospective study.

BACKGROUND: Immunosuppression during liver transplantation (LT) enables the prevention and treatment of organ rejection but poses a risk for severe infectious diseases. Immune modulation and antimicrobials affect the plasma microbiome. Thus, determining the impact of immunosuppression on the microbiome may be important to understand immunocompetence, elucidate the source of infection, and predict the risk of infection in LT recipients. We characterized the plasma microbiome of LT recipients at early post-LT and assessed the association between the microbiome and clinical events. RESULTS: In this study, 51 patients who received LT at Nagoya University Hospital from 2016 to 2018 were enrolled. Plasma samples were retrospectively collected at the following time points: 1) within a week after LT; 2) 4 ± 1 weeks after LT; 3) 8 ± 1 weeks after LT; and 4) within 2 days after a positive blood culture. A total of 111 plasma samples were analyzed using shotgun next-generation sequencing (NGS) with the PATHDET pipeline. Relative abundance of Anelloviridae, Nocardiaceae, Microbacteriaceae, and Enterobacteriaceae significantly changed during the postoperative period. Microbiome diversity was higher within a week after LT than that at 8 weeks after LT. Antimicrobials were significantly associated with the microbiome of LT recipients. In addition, the proportion of Enterobacteriaceae was significantly increased and the plasma microbiome diversity was significantly lower in patients with acute cellular rejection (ACR) than non-ACR patients. Sequencing reads of bacteria isolated from blood cultures were predominantly identified by NGS in 8 of 16 samples, and human herpesvirus 6 was detected as a causative pathogen in one recipient with severe clinical condition. CONCLUSIONS: The metagenomic NGS technique has great potential in revealing the plasma microbiome and is useful as a comprehensive diagnostic procedure in clinical settings. Temporal dynamics of specific microorganisms may be used as indirect markers for the determination of immunocompetence and ACR in LT recipients.

Non-invasive cardiac allograft rejection surveillance: reliability and clinical value for prevention of heart failure.

Allograft rejection-related acute and chronic heart failure (HF) is a major cause of death in heart transplant recipients. Given the deleterious impact of late recognized acute rejection (AR) or non-recognized asymptomatic antibody-mediated rejection on short- and long-term allograft function improvement of AR surveillance and optimization of action strategies for confirmed AR can prevent AR-related allograft failure and delay the development of cardiac allograft vasculopathy, which is the major cause for HF after the first posttransplant year. Routine non-invasive monitoring of cardiac function can improve both detection and functional severity grading of AR. It can also be helpful in guiding the anti-AR therapy and timing of routine surveillance endomyocardial biopsies (EMBs). The combined use of EMBs with non-invasive technologies and methods, which allow detection of subclinical alterations in myocardial function (e.g., tissue Doppler imaging and speckle-tracking echocardiography), reveal alloimmune activation (e.g., screening of complement-activating donor-specific antibodies and circulating donor-derived cell-free DNA) and help in predicting the imminent risk of immune-mediated injury (e.g., gene expression profiling, screening of non-HLA antibodies, and circulating donor-derived cell-free DNA), can ensure the best possible surveillance and management of AR. This article gives an overview of the current knowledge about the reliability and clinical value of non-invasive cardiac allograft AR surveillance. Particular attention is focused on the potential usefulness of non-invasive tools and techniques for detection and functional grading of early and late ARs in asymptomatic patients. Overall, the review aimed to provide a theoretical and practical basis for those engaged in this particularly demanding up-to-date topic.