Induction of heat shock proteins in a rat composite tissue allotransplantation model of acute rejection

B-Cell-Based and Soluble Biomarkers in Body Liquids for Predicting Acute/Chronic Graft-versus-Host Disease after Allogeneic Hematopoietic Stem Cell Transplantation

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is the main curative therapy for hematological malignancy such as leukemias, lymphomas, or multiple myelomas and some other hematological disorders. In this therapy, cure of hematological diseases relies on graft-versus-malignancy effects by allogenic immune cells. However, severe posttransplant treatment-associated complications such as acute graft-versus-host disease (aGvHD) and chronic graft-versus-host disease (cGvHD) limit this approach. Most research into GvHD has concentrated on the aGvHD, while the more complex and multifaceted chronic form has been largely poorly investigated. cGvHD is a multi-organ autoimmune disorder and is the major cause of non-relapse morbidity and mortality following allo-HSCT, occurring in about 50% of patients, or 13,000–15,000 patients per year worldwide. Therefore, there is a high medical need for an early prediction of these therapy-associated toxicities. Biomarkers have gained importance over the last decade in diagnosis, in prognosis, and in prediction of pending diseases or side effects. Biomarkers can be cells, factors isolated from target tissues, or soluble factors that can be detected in body fluids. In this review, we aim to summarize some of the recent developments of biomarkers in the field of allo-HSCT. We will focus on cell-based biomarkers (B-cell subsets) for cGvHD and soluble factors including microRNA (miRNA), which are excreted into serum/plasma and urine. We also discuss the potential role of cytosolic and extracellular 70 kDa heat shock proteins (HSP70) as potential biomarkers for aGvHD and their role in preclinical models. Proteomic biomarkers in the blood have been used as predictors of treatment responses in patients with aGvHD for many years. More recently, miRNAs have been found to serve as a biomarker to diagnose aGvHD in the plasma. Another development relates to urine-based biomarkers that are usually detected by capillary electrophoresis and mass spectrometry. These biomarkers have the potential to predict the development of severe aGvHD (grades III–IV), overall mortality, and the pending development of cGvHD in patients posttransplant.

Acute Rejection of Knee Joint Articular Cartilage in a Rat Composite Tissue Allotransplantation Model

BACKGROUND

Osteochondral allograft transplantation is used to treat severe cartilage injury or chondral defects, with good outcomes in clinical studies. However, allograft chondrocyte death due to apoptosis may occur during storage or as a result of implantation stress. We investigated a third possible cause, chondrocyte apoptosis resulting from an immune response, by means of composite tissue allografting, thus eliminating the role of storage and implantation stresses on osteochondral grafts.

METHODS

Vascularized composite tissue allotransplantation (from Fisher 344 to Lewis rat strains) and isotransplantation (from Lewis to Lewis strains) of rat hind limbs were performed. Immunohistochemistry was performed with use of caspase-3 and TUNEL (terminal deoxynucleotidyl transferase mediated dUTP nick end labeling) assays. Analyses were performed immediately after perfusion (day zero) and on postoperative days one, three, seven, twelve, and eighteen (n = 5 for immunohistochemistry). Transmission electron microscopy was used for detection of chondrocyte apoptosis. Laser capture microdissection followed by quantitative real-time polymerase chain reaction assays was used for analysis of postoperative caspase-3 gene expression.

RESULTS

Caspase-3 immunochemistry was increasingly positive in allograft chondrocytes from postoperative day seven onward. In contrast, caspase-3 gene expression decreased in all allografts. TUNEL assays showed increasing apoptosis of allograft chondrocytes, and electron microscopy also revealed evidence supporting the development of apoptosis.

CONCLUSIONS

Immunorejection of chondrocytes in transplanted cartilage has been thought to be unlikely, but our data reveal that chondrocytes can undergo apoptosis in allotransplantation. This apoptosis involves the caspase-3 cascade and indicates that chondrocytes may induce acute rejection.