Shaida Varnous

MicroRNAs as non-invasive biomarkers of heart transplant rejection

AIM Rejection is one of the major causes of late cardiac allograft failure and at present can only be diagnosed by invasive endomyocardial biopsies. We sought to determine whether microRNA profiling could serve as a non-invasive biomarker of cardiac allograft rejection. METHODS We included 113 heart transplant recipients from four referral French institutions (test cohort, n = 60, validation cohort, n = 53). In the test cohort, we compared patients with acute biopsy-proven allograft rejection (n = 30) to matched control patients without rejection (n = 30), by assessing microRNAs expression in the heart allograft tissue and patients concomitant serum using RNA extraction and qPCR analysis. Fourteen miRNAs were selected on the basis of their implication in allograft rejection, endothelial activation, and inflammation and tissue specificity. RESULTS We identified seven miRNAs that were differentially expressed between normal and rejecting heart allografts: miR-10a, miR-21, miR-31, miR-92a, miR-142-3p miR-155, and miR-451 (P < 0.0001 for all comparisons). Four out of seven miRNAs also showed differential serological expression (miR-10a, miR-31, miR-92a, and miR-155) with strong correlation with their tissular expression. The receiver-operating characteristic analysis showed that these four circulating miRNAs strongly discriminated patients with allograft rejection from patients without rejection: miR-10a (AUC = 0.975), miR-31 (AUC = 0.932), miR-92a (AUC = 0.989), and miR-155 (AUC = 0.998, P < 0.0001 for all comparisons). We confirmed in the external validation set that these four miRNAs highly discriminated patients with rejection from those without. The discrimination capability of the four miRNAs remained significant when stratified by rejection diagnosis (T-cell-mediated rejection or antibody-mediated rejection) and time post-transplant. CONCLUSION This study demonstrates that a differential expression of miRNA occurs in rejecting allograft patients, not only at the tissue level but also in the serum, suggesting their potential relevance as non-invasive biomarkers in heart transplant rejection.

Resistance pattern of cytomegalovirus (CMV) after oral valganciclovir therapy in transplant recipients at high-risk for CMV infection.

In transplant recipients, cytomegalovirus (CMV) resistance to antivirals causes an increasing problem. Here we report the clinical, therapeutic, and virological characteristics of 11 cases of CMV resistance among transplant recipients at high-risk for CMV infection and receiving valganciclovir as a prophylactic, preemptive or maintenance therapy. Active CMV infection was monitored by viral DNA quantification in whole blood, and CMV resistance was assessed by UL97 and UL54 viral gene sequencing. For 10 patients, ganciclovir resistance detected after valganciclovir therapy was associated with one mutation within UL97 phosphotransferase located at codons 460 and 592-603, which constitutes a similar pattern of resistance to what has been reported previously in AIDS patients treated with valganciclovir. For the last patient, two mutations in UL97 and UL54 genes were identified. The start of valganciclovir maintenance treatment after an intravenous curative treatment while CMV DNA is still detectable in peripheral blood might represent a risk factor for the emergence of CMV resistance. The possible emergence of CMV resistance in transplant recipients at high-risk for CMV infection who receive valganciclovir therapy should be taken into account. Among those patients, CMV infection has to be closely monitored in order to detect promptly the emergence of drug-resistance.

Late Failing Heart Allografts: Pathology of Cardiac Allograft Vasculopathy and Association With Antibody-Mediated Rejection

In heart transplantation, there is a lack of robust evidence of the specific causes of late allograft failure. We hypothesized that a substantial fraction of failing heart allografts may be associated with antibody‐mediated injury and immune‐mediated coronary arteriosclerosis. We included all patients undergoing a retransplantation for late terminal heart allograft failure in three referral centers. We performed an integrative strategy of heart allograft phenotyping by assessing the heart vascular tree including histopathology and immunohistochemistry together with circulating donor‐specific antibodies. The main analysis included 40 explanted heart allografts patients and 402 endomyocardial biopsies performed before allograft loss. Overall, antibody‐mediated rejection was observed in 19 (47.5%) failing heart allografts including 16 patients (40%) in whom unrecognized previous episodes of subclinical antibody‐mediated rejection occurred 4.5 ± 3.5 years before allograft loss. Explanted allografts with evidence of antibody‐mediated rejection demonstrated higher endothelitis and microvascular inflammation scores (0.89 ± 0.26 and 2.25 ± 0.28, respectively) compared with explanted allografts without antibody‐mediated rejection (0.42 ± 0.11 and 0.36 ± 0.09, p = 0.046 and p < 0.0001, respectively). Antibody‐mediated injury was observed in 62.1% of failing allografts with pure coronary arteriosclerosis and mixed (arteriosclerosis and atherosclerosis) pattern, while it was not observed in patients with pure coronary atherosclerosis (p = 0.0076). We demonstrate that antibody‐mediated rejection is operating in a substantial fraction of failing heart allografts and is associated with severe coronary arteriosclerosis. Unrecognized subclinical antibody‐mediated rejection episodes may be observed years before allograft failure.

Fatal Disseminated Acanthamoeba lenticulata Acanthamebiasis in a Heart Transplant Patient

We report a fatal case of disseminated acanthamebiasis caused by Acanthamoeba lenticulata (genotype T5) in a 39-year-old heart transplant recipient. The diagnosis was based on skin histopathologic results and confirmed by isolation of the ameba from involved skin and molecular analysis of a partial 18S rRNA gene sequence (DF3).

Adapted Treatment of Epstein–Barr Virus Infection to Prevent Posttransplant Lymphoproliferative Disorder After Heart Transplantation

Up to 35% of posttransplant lymphoproliferative disorder (PTLD) cases occur within 1 year of transplantation, and over 50% are associated with Epstein–Barr virus (EBV). EBV primary infection and reactivation are PTLD predictive factors, but there is no consensus for their treatment. We conducted a prospective single‐center study on 299 consecutive heart‐transplant patients treated with the same immunosuppressive regimen and monitored by repetitive EBV viral‐load measurements and endomyocardial biopsies to detect graft rejection. Immunosuppression was tapered on EBV reactivation with EBV viral loads >105 copies/mL or primary infection. In the absence of response at 1 month or a viral load >106 copies/mL, patients received one rituximab infusion (375 mg/m2). All patients responded to treatment without increased graft rejection. One primary infection case developed a possible PTLD, which completely responded to diminution of immunosuppression, and one patient, whose EBV load was unevaluable, died of respiratory complications secondary to PTLD. Compared with a historical cohort of 820 patients, PTLD incidence was decreased (p = 0.033) by a per‐protocol analysis. This is the largest study on EBV primary infection/reactivation treatment, the first using rituximab following solid organ transplantation to prevent PTLD and the first to demonstrate an acceptable tolerability profile in this setting.

Gene Expression Profiling for the Identification and Classification of Antibody-Mediated Heart Rejection

Background: Antibody-mediated rejection (AMR) contributes to heart allograft loss. However, an important knowledge gap remains in terms of the pathophysiology of AMR and how detection of immune activity, injury degree, and stage could be improved by intragraft gene expression profiling. Methods: We prospectively monitored 617 heart transplant recipients referred from 4 French transplant centers (January 1, 2006–January 1, 2011) for AMR. We compared patients with AMR (n=55) with a matched control group of 55 patients without AMR. We characterized all patients using histopathology (ISHLT [International Society for Heart and Lung Transplantation] 2013 grades), immunostaining, and circulating anti-HLA donor-specific antibodies at the time of biopsy, together with systematic gene expression assessments of the allograft tissue, using microarrays. Effector cells were evaluated with in vitro human cell cultures. We studied a validation cohort of 98 heart recipients transplanted in Edmonton, AB, Canada, including 27 cases of AMR and 71 controls. Results: A total of 240 heart transplant endomyocardial biopsies were assessed. AMR showed a distinct pattern of injury characterized by endothelial activation with microcirculatory inflammation by monocytes/macrophages and natural killer (NK) cells. We also observed selective changes in endothelial/angiogenesis and NK cell transcripts, including CD16A signaling and interferon-&ggr;–inducible genes. The AMR-selective gene sets accurately discriminated patients with AMR from those without and included NK transcripts (area under the curve=0.87), endothelial activation transcripts (area under the curve=0.80), macrophage transcripts (area under the curve=0.86), and interferon-&ggr; transcripts (area under the curve=0.84; P<0.0001 for all comparisons). These 4 gene sets showed increased expression with increasing pathological AMR (pAMR) International Society for Heart and Lung Transplantation grade (P<0.001) and association with donor-specific antibody levels. The unsupervised principal components analysis demonstrated a high proportion of molecularly inactive pAMR1(I+), and there was significant molecular overlap between pAMR1(H+) and full-blown pAMR2/3 cases. Endothelial activation transcripts, interferon-&ggr;, and NK transcripts showed association with chronic allograft vasculopathy. The molecular architecture and selective AMR transcripts, together with gene set discrimination capacity for AMR identified in the discovery set, were reproduced in the validation cohort. Conclusions: Tissue-based measurements of specific pathogenesis-based transcripts reflecting NK burden, endothelial activation, macrophage burden, and interferon-&ggr; effects accurately classify AMR and correlate with degree of injury and disease activity. This study illustrates the clinical potential of a tissue-based analysis of gene transcripts to refine diagnosis of heart transplant rejection.

Heart transplantation in systemic (AL) amyloidosis: a retrospective study of eight French patients.

BACKGROUND Immunoglobulinic (AL) amyloidosis is a complication of plasma cell dyscrasia, characterized by widespread deposition of amyloid fibrils derived from monoclonal light chains. Cardiac amyloid is the main prognostic factor, with a median survival of six months. Cardiac transplantation in AL amyloidosis is associated with high mortality, due to disease recurrence in the allograft and systemic progression. Suppression of light chain (LC) production with chemotherapy by melphalan plus dexamethasone (MD) or high dose melphalan followed by autologous stem cell transplantation (HDM/ASCT) improves survival. However, both the indications and results of chemotherapy in patients transplanted for cardiac AL amyloidosis remain unclear. AIMS To assess the outcome of cardiac transplantation and haematological therapy in patients with cardiac AL amyloidosis. METHODS Eight French patients, who underwent heart transplantation for cardiac AL amyloidosis between 2001 and 2006 were studied retrospectively. RESULTS Before transplantation, six patients received MD (n=5) or HDM/ASCT (n=1). Haematological remission was obtained in three patients treated with MD. In the three remaining patients, postoperative HDM/ASCT (n=2) or allogeneic bone marrow transplantation (n=1) resulted in haematological remission in one patient. In 2 patients not treated before transplantation, post-operative treatment with MD resulted in complete hematological remission in one. After a median follow-up of 26 months from cardiac transplantation, six patients were alive and four had sustained haematological remission, as indicated by normal serum free LC levels. CONCLUSION Appropriate haematological therapy, including MD, may result in a survival benefit in AL amyloidosis patients with advanced heart failure requiring transplantation.

Release of brain natriuretic-related peptides (BNP, NT-proBNP) and cardiac troponins (cTnT, cTnI) in on-pump and off-pump coronary artery bypass surgery.

BackgroundWe studied the kinetic release of cardiac troponins (cTnI and cTnT) and B-type natriuretic peptides (BNP and NT-proBNP) in patients undergoing off-pump or on-pump coronary artery bypass surgery.MethodsTwenty-five consecutive patients were prospectively enrolled. The patients were divided into three groups: beating heart (I), and cardiopulmonary bypass (CPB) with warm (II) or cold cardioplegia (III). Plasma samples were obtained before anesthesia induction until the sixth day after surgery.Results and ConclusionsThe data were analyzed first for off-pump versus the CPB procedures and second for warm versus cold cardioplegia. The plasma troponin releases appeared to be significantly higher in the CPB groups in comparison to the beating heart group (P < 0.001 and P < 0.002 for cTnI and cTnT peak values, respectively). The peak of the B-type natriuretic peptide release appeared to be more delayed in the groups undergoing CPB than in the beating heart group (day 6 versus days 2 and 4 for NT-proBNP and BNP, respectively). Taken together, our results indicated that the new generation of cTnT assays seemed to be more sensitive than the cTnI assays for the diagnosis of myocardium injury. A lower increase in the cTnT values in the warm cardioplegic group indicated less damage of the myocardium than with cold cardioplegia. Our data also confirm better preservation of the myocardium with off-pump cardiac surgery than with CPB.

Desmosomal Cadherins Are Decreased in Explanted Arrhythmogenic Right Ventricular Dysplasia/Cardiomyopathy Patient Hearts

Aims Arrhythmogenic right ventricular Dysplasia/cardiomyopathy (ARVD/C) is an autosomal dominant inherited cardiomyopathy associated with ventricular arrhythmia, heart failure and sudden death. Genetic studies have demonstrated the central role of desmosomal proteins in this disease, where 50% of patients harbor a mutation in a desmosmal gene. However, clinical diagnosis of the disease remains difficult and molecular mechanisms appears heterogeneous and poorly understood. The aim of this study was to characterize the expression profile of desmosomal proteins in explanted ARVD/C heart samples, in order to identify common features of the disease. Methods and Results We examined plakophilin-2, desmoglein-2, desmocollin-2, plakoglobin and β-catenin protein expression levels from seven independent ARVD/C heart samples compared to two ischemic, five dilated cardiomyopathy and one healthy heart sample as controls. Ventricular and septum sections were examined by immunoblot analysis of total heart protein extracts and by immunostaining. Immunoblots indicated significant decreases in desmoglein-2 and desmocollin-2, independent of any known underlying mutations, whereas immune-histochemical analysis showed normal localization of all desmosomal proteins. Quantitative RT-PCR revealed normal DSG2 and DSC2 mRNA transcript levels, suggesting increased protein turn-over rather than transcriptional down regulation. Conclusion Reduced cardiac desmoglein-2 and desmocollin-2 levels appear to be specifically associated with ARVD/C, independent of underlying mutations. These findings highlight a key role of desmosomal cadherins in the pathophysiology of ARVD/C. Whether these reductions could be considered as specific markers for ARVD/C requires replication analysis.

Effect of intracoronary administration of AAV1/SERCA2a on ventricular remodelling in patients with advanced systolic heart failure: results from the AGENT-HF randomized phase 2 trial

Restoration of sarco/endoplasmic reticulum Ca2+ ATPase (SERCA2a) activity through gene transfer improved cardiac function in experimental and pilot studies in humans with heart failure. The AGENT‐HF (NCT01966887) trial investigated the impact of adeno‐associated virus (AAV1)/SERCA2a on ventricular remodelling using multimodality non‐invasive cardiac imaging.