H. Baron

Noninvasive discrimination of rejection in cardiac allograft recipients using gene expression profiling

Rejection diagnosis by endomyocardial biopsy (EMB) is invasive, expensive and variable. We investigated gene expression profiling of peripheral blood mononuclear cells (PBMC) to discriminate ISHLT grade 0 rejection (quiescence) from moderate/severe rejection (ISHLT ≥3A). Patients were followed prospectively with blood sampling at post‐transplant visits. Biopsies were graded by ISHLT criteria locally and by three independent pathologists blinded to clinical data. Known alloimmune pathways and leukocyte microarrays identified 252 candidate genes for which real‐time PCR assays were developed. An 11 gene real‐time PCR test was derived from a training set (n = 145 samples, 107 patients) using linear discriminant analysis (LDA), converted into a score (0–40), and validated prospectively in an independent set (n = 63 samples, 63 patients). The test distinguished biopsy‐defined moderate/severe rejection from quiescence (p = 0.0018) in the validation set, and had agreement of 84% (95% CI 66% C94%) with grade ISHLT ≥3A rejection. Patients >1 year post‐transplant with scores below 30 (approximately 68% of the study population) are very unlikely to have grade ≥3A rejection (NPV = 99.6%). Gene expression testing can detect absence of moderate/severe rejection, thus avoiding biopsy in certain clinical settings. Additional clinical experience is needed to establish the role of molecular testing for clinical event prediction and immunosuppression management.

Gene-Expression Profiling for Rejection Surveillance after Cardiac Transplantation

BACKGROUND Endomyocardial biopsy is the standard method of monitoring for rejection in recipients of a cardiac transplant. However, this procedure is uncomfortable, and there are risks associated with it. Gene-expression profiling of peripheral-blood specimens has been shown to correlate with the results of an endomyocardial biopsy. METHODS We randomly assigned 602 patients who had undergone cardiac transplantation 6 months to 5 years previously to be monitored for rejection with the use of gene-expression profiling or with the use of routine endomyocardial biopsies, in addition to clinical and echocardiographic assessment of graft function. We performed a noninferiority comparison of the two approaches with respect to the composite primary outcome of rejection with hemodynamic compromise, graft dysfunction due to other causes, death, or retransplantation. RESULTS During a median follow-up period of 19 months, patients who were monitored with gene-expression profiling and those who underwent routine biopsies had similar 2-year cumulative rates of the composite primary outcome (14.5% and 15.3%, respectively; hazard ratio with gene-expression profiling, 1.04; 95% confidence interval, 0.67 to 1.68). The 2-year rates of death from any cause were also similar in the two groups (6.3% and 5.5%, respectively; P=0.82). Patients who were monitored with the use of gene-expression profiling underwent fewer biopsies per person-year of follow-up than did patients who were monitored with the use of endomyocardial biopsies (0.5 vs. 3.0, P<0.001). CONCLUSIONS Among selected patients who had received a cardiac transplant more than 6 months previously and who were at a low risk for rejection, a strategy of monitoring for rejection that involved gene-expression profiling, as compared with routine biopsies, was not associated with an increased risk of serious adverse outcomes and resulted in the performance of significantly fewer biopsies. (ClinicalTrials.gov number, NCT00351559.)

The Economic Implications of Noninvasive Molecular Testing for Cardiac Allograft Rejection

Endomyocardial biopsy is the mainstay for monitoring cardiac allograft rejection. A noninvasive strategy—peripheral blood gene expression profiling of circulating leukocytes—is an alternative with proven benefits, but unclear economic implications. Financial data were obtained from five cardiac transplant centers. An economic evaluation was conducted to compare the costs of outpatient biopsy with those of a noninvasive approach to monitoring cardiac allograft rejection. Hospital outpatient biopsy costs averaged

The Role of Staphylococcus aureus Adhesins in the Pathogenesis of Ventricular Assist Device–Related Infections

3297, excluding reimbursement for professional fees. Costs to Medicare and private payers averaged

Concordance Among Pathologists in the Second Cardiac Allograft Rejection Gene Expression Observational Study (CARGO II)

3581 and

Principles of Transplantation Immunology

4140, respectively. A noninvasive monitoring test can reduce biopsy utilization. The savings to health care payers in the United States can be conservatively estimated at approximately

Nodular Endocardial Infiltrates (Quilty Lesions) Cause Significant Variability in Diagnosis of ISHLT Grade 2 and 3A Rejection in Cardiac Allograft Recipients

12.0 million annually. Molecular testing using gene expression profiling of peripheral circulating leukocytes is a new technology that offers physicians a noninvasive, less expensive alternative to endomyocardial biopsy for monitoring allograft rejection in cardiac transplant patients.

Cellular coating of the left ventricular assist device textured polyurethane membrane reduces adhesion of Staphylococcus aureus

Ventricular assist devices (VADs) are an important form of therapy for end-stage congestive heart failure. However, infection of the VAD, which is often caused by Staphylococcus aureus, poses a major threat to survival. Using a novel in vitro binding assay with VAD membranes and a heterologous lactococcal system of expression, we identify 3 S. aureus proteins--clumping factor A (ClfA) and fibronectin binding proteins A and B (FnBPA and FnBPB) as the main factors involved in adherence to VAD polyurethane membranes. Adherence is greatly diminished by long implantation times, reflecting a change in topological features of the VAD membrane, and is primarily mediated by the FnBPA domains in the staphylococcal proteins. We also compare the adherence of S. aureus mutant strains and show that other staphylococcal components appear to be involved in adherence to VAD membranes. Finally, we demonstrate that ClfA, FnBPA, and FnBPB mediate bacterial infection of implanted murine intra-aortic polyurethane patches.

Gene expression profiling of cardiac allograft recipients with mild acute cellular rejection

Background There has been no large evaluation of the ISHLT 2004 acute cellular rejection grading scheme for heart graft endomyocardial biopsy specimens (EMBs). Methods We evaluated agreement within the CARGO II pathology panel and between the panel (acting by majority) and the collaborating centers (treated as a single entity), regarding the ISHLT grades of 937 EMBs (with all grades ≥2R merged because of small numbers). Results Overall all-grade agreement was almost 71% both within the panel and between the panel and the collaborating centers but, in both cases, was largely because of agreement on grade 0: for the average pair of pathologists, fewer than a third of the EMBs assigned grade ≥2R by at least one were assigned this grade by both. Conclusion The 2004 revision has done little to improve agreement on the higher ISHLT grades. An EMB grade ≥2R is not by itself sufficient as a basis for clinical decisions or as a research criterion. Steps should be taken toward greater uniformity in EMB grading, and efforts should be made to replace the ISHLT classification with diagnostic criteria—EMB based or otherwise—that correspond better with the pathophysiology of the transplanted heart.

191: The clinical role of gene expression testing in anticipating the future development of acute cardiac allograft rejection

Publisher Summary This chapter emphasizes on the importance of suppression of alloimmune response for successful organ transplantation. The foreign antigens are presented either by the foreign cells or tissue of the donor or by the leukocytes of the recipient. The immunocompetent cells destroy the foreign cells. An inflammatory response involving monocytes and macrophages participates in this alloimmune response. Two pathways of allorecognition, direct and indirect, contribute to donor antigen (allograft) rejection. To prevent allograft rejection, pharmacological immune prophylaxis, continuous immune and allograft function monitoring, and, if necessary, an augmentation of immunosuppression must be conducted. The chapter discusses rejection management, which includes rejection diagnosis, induction therapy, glucocorticoid withdrawal, and sensitization therapy. Only true “immunologic” tolerance can provide the outcome pursued—namely, prolonged allograft function and otherwise normal immune function, without chronic immunosuppressive therapy and its risks. Until a successful tolerance-inducing protocol is developed, the current and upcoming immunosuppressive agents and techniques must be used.