Precision transplant pathology

The impact of donor-specific antibody and non-HLA antibodies on acute cellular rejection in pediatric liver transplantation

Antibodies to HLA or non-HLA antigens are associated with detrimental outcomes in organ transplants. Here, we aim to examine whether donor-specific antibodies (DSA) and non-HLA antibodies are associated with rejection in a single-center cohort of 101 pediatric liver transplant (PLTx) recipients. Rejection was found in 50/101 biopsies (49.5 %). DSA was positive in 32 paired sera and associated with rejection (HR = 2.63[1.10-6.30]). Antibodies to 3 non-HLA antigens, SNRPB (small nuclear ribonucleoprotein polypeptides B), GSTT1 (Glutathione S-transferase theta-1), and Actin were associated with rejection. Rejection was found in 22/35 cases positive for any of the three non-HLA antibodies. The presence of DSA and non-HLA antibodies was associated with an augmented risk of rejection (HR = 6.32[1.57-25.30], p < 0.01]. In conclusion, DSA or non-HLA antibodies were associated with a higher risk for rejection in PLTx recipients. When they were detected concomitantly, the risk for rejection increased significantly, indicating the synergistic effect of actions.

Advancing Models of Care in Transplant Psychiatry: A Review and Considerations for Enhancing the Multidisciplinary Approach

PURPOSE OF REVIEW

Psychosocial considerations in transplant candidacy evaluation, waitlist, and post-transplant period is tremendously important to overall transplant care. Integration of mental health services in multidisciplinary transplant teams improves adherence to medical regimens, enhances quality of life, and reduces the risk of post-transplant complications.

RECENT FINDINGS

Despite this, psychiatrists are often under-utilized by transplant centers, with engagement typically limited to transplant candidacy evaluations or reactive consults in a traditional CL model. In this review, we aim to 1) highlight the relevance of psychiatry throughout the transplant course, 2) outline the role of a CL psychiatrist in advancing patient care and supporting multidisciplinary teams in transplant, 3) develop an understanding of CL service models in both the inpatient and ambulatory setting and 4) consider the utility of innovating current transplant psychiatry practices.

Immunopathology of Corneal Allograft Rejection and Donor-Specific Antibodies (DSAs) as Immunological Predictors of Corneal Transplant Failure

Despite tremendous developments in the field of laboratory testing in transplantation, the rules of eligibility for corneal transplantation still do not include typing of human leukocyte antigens (HLAs) in the donor and recipient or detection of donor-specific antibodies (DSAs) in the patient. The standard use of diagnostic algorithms is due to the cornea belonging to immunologically privileged tissues, which usually determines the success of transplantation of this tissue. A medical problem is posed by patients at high risk of transplant rejection, in whom the immune privilege of the eye is abolished and the risk of transplant failure increases. Critical to the success of transplantation in patients at high risk of corneal rejection may be the selection of an HLA-matched donor and recipient, and the detection of existing and/or de novo emerging DSAs in the patient. Incorporating the assessment of these parameters into routine diagnostics may contribute to establishing immune risk stratification for transplant rejection and effective personalized therapy for patients.

Decellularized Extracellular Matrix: The Role of This Complex Biomaterial in Regeneration

Organ transplantation is understood as a technique where an organ from a donor patient is transferred to a recipient patient. This practice gained strength in the 20th century and ensured advances in areas of knowledge such as immunology and tissue engineering. The main problems that comprise the practice of transplants involve the demand for viable organs and immunological aspects related to organ rejection. In this review, we address advances in tissue engineering for reversing the current challenges of transplants, focusing on the possible use of decellularized tissues in tissue engineering. We address the interaction of acellular tissues with immune cells, especially macrophages and stem cells, due to their potential use in regenerative medicine. Our goal is to exhibit data that demonstrate the use of decellularized tissues as alternative biomaterials that can be applied clinically as partial or complete organ substitutes.

Next-generation pathology detection of T cell-antigen-presenting cell immune synapses in human liver allografts

BACKGROUND AND AIMS

In otherwise near-normal appearing biopsies by routine light microscopy, next-generation pathology (NGP) detected close pairings (immune pairs; iPAIRs) between lymphocytes and antigen-presenting cells (APCs) that predicted immunosuppression weaning failure in pediatric liver transplant (LTx) recipients (Immunosuppression Withdrawal for Stable Pediatric Liver Transplant Recipients [iWITH], NCT01638559). We hypothesized that NGP-detected iPAIRs enrich for true immune synapses, as determined by nuclear shape metrics, intercellular distances, and supramolecular activation complex (SMAC) formation.

APPROACH AND RESULTS

Intralobular iPAIRs (CD45 high lymphocyte-major histocompatibility complex II + APC pairs; n = 1167, training set) were identified at low resolution from multiplex immunohistochemistry-stained liver biopsy slides from several multicenter LTx immunosuppression titration clinical trials (iWITH; NCT02474199 (Donor Alloantigen Reactive Tregs (darTregs) for Calcineurin Inhibitor (CNI) Reduction (ARTEMIS); Prospective Longitudinal Study of iWITH Screen Failures Secondary to Histopathology). After excluding complex multicellular aggregates, high-resolution imaging was used to examine immune synapse formation ( n = 998). By enriching for close intranuclear lymphocyte-APC distance (mean: 0.713 μm) and lymphocyte nuclear flattening (mean ferret diameter: 2.1), SMAC formation was detected in 29% of iPAIR-engaged versus 9.5% of unpaired lymphocytes. Integration of these morphometrics enhanced NGP detection of immune synapses (ai-iSYN). Using iWITH preweaning biopsies from eligible patients ( n = 53; 18 tolerant, 35 nontolerant; testing set), ai-iSYN accurately predicted (87.3% accuracy vs. 81.4% for iPAIRs; 100% sensitivity, 75% specificity) immunosuppression weaning failure. This confirmed the presence and importance of intralobular immune synapse formation in liver allografts. Stratification of biopsy mRNA expression data by immune synapse quantity yielded the top 20 genes involved in T cell activation and immune synapse formation and stability.

CONCLUSIONS

NGP-detected immune synapses (subpathological rejection) in LTx patients prior to immunosuppression reduction suggests that NGP-detected (allo)immune activity usefulness for titration of immunosuppressive therapy in various settings.

Not only a small liver - The pathologist's perspective in the pediatric liver transplant setting

Pediatric liver transplantation represents a safe and long-lasting treatment option for various disease types, requiring the pathologist's input. Indeed, an accurate and timely diagnosis is crucial in reporting and grading native liver diseases, evaluating donor liver eligibility and identifying signs of organ injury in the post-transplant follow-up. However, as the procedure is more frequently and widely performed, deceptive and unexplored histopathologic features have emerged with relevant consequences on patient management, particularly when dealing with long-term treatment and weaning of immunosuppression. In this complex and challenging scenario, this review aims to depict the most relevant histopathologic conditions which could be encountered in pediatric liver transplantation. We will tackle the conditions representing the main indications for transplantation in childhood as well as the complications burdening the post-transplant phases, either immunologically (i.e., rejection) or non-immunologically mediated. Lastly, we hope to provide concise, yet significant, suggestions related to innovative pathology techniques in pediatric liver transplantation.