Biomarkers in Solid Organ Transplantation

Microvascular activation and exocytosis after exposure to the serum from mismatched recipients by using donor microvascular cultures

BACKGROUND

Microvascular injury resulting from activation and exocytosis are early signs of tissue damage caused by allografting. However, humoral anti-graft reactions are not easily detectable in transplant biopsies. The aim of this study was to establish a bioassay to recapitulate this process in a prospective approach.

METHODS

The study was executed by using our previously established protocol to isolate and freeze the donors' microvascular endothelial cells (MVEC) at the transplantation (34 living-related donors and 26 cadaver donors); and to collect sera from the recipients before the transplantation, one-, three- and six-months after transplantation. The activation and exocytosis of the MVEC were determined by incubating the donors' cultures with the recipients' sera. We determined if there was any endothelial activation by quantifying the releases of monocyte chemotactic protein-1 (MCP-1) and interleukin 8 (IL-8) in supernatants and the expressions of membrane intercellular adhesion molecule-1 (CD54) and intercellular adhesion molecule-1 (CD106) by flow cytometry. Endothelial exocytosis was determined by quantifying soluble E-selectin (CD62E) and cytoplasmic von Willebrand Factor (vWF) in supernatants. Endothelial activation or exocytosis was considered positive when the fold change (≧1.5) of post-transplantation to pre-transplantation was reached. We also monitored serum PRA and cytokines using Luminex multiple-plex and cytometric bead-based assay respectively.

RESULTS

We found 41.2% recipients (14 out of 34, ranging from 1.5 to 5.2 folds, p < 0.05) exhibited positive MVEC activation in the first month after transplantation as determined by IL-8 levels; 26.5% recipients (9 out of 34, ranging from 1.5 to 11.8 folds, p < 0.05) by MCP-1 levels. In the group of three months post-transplantation, 70.6% patients were positive (12 out of 17, ranging from 1.8 to 87.1 folds, p < 0.05) by IL-8 increased levels; 24% recipients (4 out of 17, ranging from 1.8 to 50.5 folds, p < 0.05) measured by MCP-1 levels. However, these changes disappeared six months after transplantation. Flow cytometric data showed that a time-dependent of CD54+ and CD106+ expressions existed over the course of six months. Most CD54+ and CD106+ cells were CD31- (platelet-endothelial cell adhesion molecule-1), though CD31+/CD106+ (37.5%, 3 out of 8) and CD31+/CD106+ (25%. 2 out of 8) were seen. When comparing donor MVEC activation to their recipient's proinflammatory cytokine levels or PRA status, we could not draw a conclusion regarding the connections between them. The sera collected from recipients at either one- or three-months after allografting did not significantly induce the release of either soluble CD62E or vWF (p > 0.05), indicating exocytosis was not significantly involved in the acute phase of allografting.

CONCLUSIONS

This bioassay enables us to detect the activation and exocytosis of donor MVEC elicited by respective sera from mismatched kidney recipients.

Impact of CD 28, CD86, CTLA-4 and PD-1 genes polymorphisms on acute renal allograft rejection and graft survival among Egyptian recipients

To study the impact of four gene polymorphisms on acute renal allograft rejection (AR) and graft survival among Egyptian population. These 4 gene polymorphisms include: (1) CD 28 (rs3116496), (2) CD86 (rs1129055), (3) CTLA-4 (rs3087243), (4) PD-1 (rs2227982). This is a non-concurrent cohort study including 50 kidney transplant recipients diagnosed histopathologically as (AR) [study group] and another 50 matched allograft recipients without AR [control group]. Blood samples were taken from both groups and subjected to genotyping for the selected four genetic polymorphisms by TaqMan genotyping assay. The difference in genotypic distribution of CD 28: rs3116496 and CD86: rs1129055 wasn't statistically significant between the study and control groups (P = 0.22 and 0.33 respectively) and also both polymorphisms had no effect on graft survival (P = 0.36 and 0.74 respectively) while the addition of C allele to IVS3 +17T/C polymorphism in CD28 gene showed a protective effect against AR (P = 0.03). CTLA-4: rs3087243 AG genotype showed a protective effect against AR as it was more frequent in no rejection group compared to those with AR (P = 0.001) with a statistically significant impact on graft survival (P < 0.001), while PD-1: rs2227982 AG genotype was equally distributed between both groups (variant of unknown significance). There was no detected association between CD86 polymorphism: rs1129055 and CD 28 polymorphism: rs3116496 with the development of AR. However, C allele of CD 28 IVS3 +17T/C polymorphism and CTLA-4 polymorphism: rs3087243AG genotype both demonstrated a protective effect against AR.

Advancing mouse models for transplantation research

Mouse models have been instrumental in understanding mechanisms of transplant rejection and tolerance, but cross-study reproducibility and translation of experimental findings into effective clinical therapies are issues of concern. The Mouse Models in Transplantation symposium gathered scientists and physician-scientists involved in basic and clinical research in transplantation to discuss the strengths and limitations of mouse transplant models and strategies to enhance their utility. Participants recognized that increased procedure standardization, including the use of prespecified, defined endpoints, and statistical power analyses, would benefit the field. They also discussed the generation of new models that incorporate environmental and genetic variables affecting clinical outcomes as potentially important. If implemented, these strategies are expected to improve the reproducibility of mouse studies and increase their translation to clinical trials and, ideally, new Food and Drug Administration-approved drugs.

Association of Polymorphisms in T-Cell Activation Costimulatory/Inhibitory Signal Genes With Allograft Kidney Rejection Risk

The genes CD28, CD86 and CTLA-4 conform the costimulatory (CD28-CD86) or inhibitory (CTLA-4-CD86) signal in T-cell activation. T-cell immune response has a critical role in allograft rejection, and single nucleotide polymorphisms (SNPs) located in these genes have been widely analyzed with controversial results. We analyzed a group of SNPs located in the three genes: CD28: rs3116496; CD86: rs1129055; and CTLA-4: rs231775 and rs3087243 in a cohort of 632 consecutively recruited kidney transplanted subjects. All polymorphisms were genotyped by TaqMan chemistry and the diagnosis of rejection was confirmed by biopsy and categorized according to the Banff classification. The analyses showed a statistically significant protective effect to T cell-mediated rejection (TCMR) in carriers of the CTLA-4 rs3087243*G allele, especially in patients with TCMR Banff ≥2 in the overall cohort and in patients without thymoglobulin induction therapy. Both associations were corroborated as independent factors in the multivariate analysis. Interestingly, associations with rejection were not found for any SNP in patients with thymoglobulin induction therapy. As expected, considering the major role of these genes in T-cell activation, no effect was observed for antibody-mediated rejection (ABMR). In conclusion, the SNP rs3087243 located in the CTLA-4 gene may be considered a useful independent biomarker for TCMR risk especially for severe TCMR in patients who did no received thymoglobulin induction therapy.

Postoperative Trends and Prognostic Values of Inflammatory and Nutritional Biomarkers after Liver Transplantation for Hepatocellular Carcinoma

Simple Summary

Inflammatory biomarkers have a strong prognostic value in surgically treated patients with hepatocellular carcinoma (HCC), but the underlying pathogenic mechanism has not been completely clarified. Conversely, nutritional biomarkers predict the outcomes after hepatic resection for HCC but not after liver transplantation (LT). Indeed, the impact of LT on the recipient’s nutritional status is heterogeneous, while the data on the patient’s outcome after LT in terms of inflammatory status are limited. Therefore, to address these unsolved questions, we conducted a retrospective analysis on 324 HCC patients treated with LT, exploring the postoperative trend up to 1 year post-LT and the prognostic value of the Platelet-to-Lymphocyte Ratio (PLR), Neutrophil-to-Lymphocyte Ratio (NLR), Controlling Nutritional Status (CONUT), Prognostic Nutritional Index (PNI). It was found that at 1 year post-LT, the nutritional status of liver-transplanted HCC patients significantly improved while their inflammatory state tended to persist. Consequently, post-LT PLR and NLR maintained a prognostic value for LT outcome while post-LT CONUT and PNI acquired it.

Abstract

Preoperative inflammatory biomarkers such as the Platelet-to-Lymphocyte Ratio (PLR) and the Neutrophil-to-Lymphocyte Ratio (NLR) strongly predict the outcome in surgically treated patients with hepatocellular carcinoma (HCC), while nutritional biomarkers such as the Controlling Nutritional Status (CONUT) and the Prognostic Nutritional Index (PNI) show an analogue prognostic value in hepatic resection (HR) but not in liver transplant (LT) cases. Data on the impact of LT on the inflammatory and nutritional/metabolic function are heterogeneous. Therefore, we investigated the post-LT trend of these biomarkers up to postoperative month (POM) 12 in 324 HCC patients treated with LT. Inflammatory biomarkers peaked in the early post-LT period but at POM 3 leveled off at values similar (NLR) or higher (PLR) than pre-LT ones. CONUT and PNI worsened in the early post-LT period, but at POM 3 they stabilized at significantly better values than pre-LT. In LT recipients with an overall survival >1 year and no evidence of early HCC recurrence, 1 year post-LT NLR and PNI independently predicted patient overall survival, while 1 year post-LT PLR independently predicted late tumor recurrence. In conclusion, at 1 year post-LT, the nutritional status of liver-transplanted HCC patients significantly improved while their inflammatory state tended to persist. Consequently, post-LT PLR and NLR maintained a prognostic value for LT outcome while post-LT CONUT and PNI acquired it.

The Role of Metabolomics in Current Concepts of Organ Preservation

In solid organ transplantation (Tx), both survival rates and quality of life have improved dramatically over the last few decades. Each year, the number of people on the wait list continues to increase, widening the gap between organ supply and demand. Therefore, the use of extended criteria donor grafts is growing, despite higher susceptibility to ischemia-reperfusion injury (IRI) and consecutive inferior Tx outcomes. Thus, tools to characterize organ quality prior to Tx are crucial components for Tx success. Innovative techniques of metabolic profiling revealed key pathways and mechanisms involved in IRI occurring during organ preservation. Although large-scale trials are needed, metabolomics appears to be a promising tool to characterize potential biomarkers, for the assessment of graft quality before Tx and evaluate graft-related outcomes. In this comprehensive review, we summarize the currently available literature on the use of metabolomics in solid organ Tx, with a special focus on metabolic profiling during graft preservation to assess organ quality prior to Tx.

Immunologic Risk Assessment and Approach to Immunosuppression Regimen in Kidney Transplantation

The outcomes of kidney transplantation show a steady improvement with an increasing number of transplantations and decreasing incidence of acute rejection episodes. Successful transplantation begins with a comprehensive immunologic risk assessment and judicious choice of therapeutic agents. In this review, we discuss the trends in transplant immunosuppression practices and outcomes in the United States. We discuss practical testing algorithms for clinical decision making in induction therapy and fine-tuning maintenance immunosuppression. We introduce assessment tools for immune monitoring after transplantation and speculate on future directions in management.

Current Trends in Applications of Circulatory Microchimerism Detection in Transplantation

Primarily due to recent advances of detection techniques, microchimerism (the proportion of minor variant population is below 1%) has recently gained increasing attention in the field of transplantation. Availability of polymorphic markers, such as deletion insertion or single nucleotide polymorphisms along with a vast array of high sensitivity detection techniques, allow the accurate detection of small quantities of donor- or recipient-related materials. This diagnostic information can improve monitoring of allograft injuries in solid organ transplantations (SOT) as well as facilitate early detection of relapse in allogeneic hematopoietic stem cell transplantation (allo-HSCT). In the present review, genetic marker and detection platform options applicable for microchimerism detection are discussed. Furthermore, current results of relevant clinical studies in the context of microchimerism and SOT or allo-HSCT respectively are also summarized.