Second Class Minors: Molecular Identification of the Autosomal H46 Histocompatibility Locus as a Peptide Presented by Major Histocompatibility Complex Class II Molecules

CD4 T cells regulate immune responses that cause chronic graft rejection and graft versus host disease but their target antigens remain virtually unknown. We developed a new method to identify CD4 T cell–stimulating antigens. LacZ-inducible CD4 T cells were used as a probe to detect their cognate peptide/MHC II ligand generated in dendritic cells fed with Escherichia coli expressing a library of target cell genes. The murine H46 locus on chromosome 7 was thus found to encode the interleukin 4–induced IL4i1 gene. The IL4i1 precursor contains the HAFVEAIPELQGHV peptide which is presented by Ab major histocompatibility complex class II molecule via an endogenous pathway in professional antigen presenting cells. Both allelic peptides bind Ab and a single alanine to methionine substitution at p2 defines nonself. These results reveal novel features of H loci that regulate CD4 T cell responses as well as provide a general strategy for identifying elusive antigens that elicit CD4 T cell responses to tumors or self-tissues in autoimmunity

Cyclosporin A Associated Helicase-Like Protein Facilitates the Association of Hepatitis C Virus RNA Polymerase with Its Cellular Cyclophilin B

BACKGROUND: Cyclosporin A (CsA) is well known as an immunosuppressive drug useful for allogeneic transplantation. It has been reported that CsA inhibits hepatitis C virus (HCV) genome replication, which indicates that cellular targets of CsA regulate the viral replication. However, the regulation mechanisms of HCV replication governed by CsA target proteins have not been fully understood. PRINCIPAL FINDINGS: Here we show a chemical biology approach that elucidates a novel mechanism of HCV replication. We developed a phage display screening to investigate compound-peptide interaction and identified a novel cellular target molecule of CsA. This protein, named CsA associated helicase-like protein (CAHL), possessed RNA-dependent ATPase activity that was negated by treatment with CsA. The downregulation of CAHL in the cells resulted in a decrease of HCV genome replication. CAHL formed a complex with HCV-derived RNA polymerase NS5B and host-derived cyclophilin B (CyPB), known as a cellular cofactor for HCV replication, to regulate NS5B-CyPB interaction. CONCLUSIONS: We found a cellular factor, CAHL, as CsA associated helicase-like protein, which would form trimer complex with CyPB and NS5B of HCV. The strategy using a chemical compound and identifying its target molecule by our phage display analysis is useful to reveal a novel mechanism underlying cellular and viral physiology

Angiogenesis‐related gene expression profile in clinical cases of canine cancer

Abstract The balance between pro‐ and anti‐angiogenic signalling is tightly regulated in normal tissues to maintain the functions of the vasculature. In contrast, the overproduction of angiogenic factors and enhanced angiogenesis are frequently observed in several types of tumours. Although there have been many reports on the correlation between tumour progression and angiogenesis in humans, little is known about tumour angiogenesis in canines. Hence, we attempted to clarify whether angiogenesis contributes to tumour progression in canines as well as humans. In this study, we investigated the expression of several angiogenesis‐related genes, including CD34, VEGF‐A, VEGFR‐1, VEGFR‐2, Ang‐1, Ang‐2, Tie1, and Tie2, in 66 canine tumour tissues and in the normal tissues surrounding the tumours by quantitative real‐time PCR analysis. Our comparative analysis between canine tumour tissues and normal tissues revealed that several angiogenesis‐related genes, such as vascular endothelial growth factor (VEGF) and VEGF‐receptor genes, were significantly upregulated in canine tumour tissues when compared to the normal tissues. We also found that the angiopoietin (Ang)‐1/Ang‐2 gene expression ratio was lower in canine tumour tissues than in the normal tissues, suggesting less association between vascular endothelial cells and perivascular cells in the canine tumour tissues. Taken together, our results suggest that several angiogenesis‐related genes may contribute to the malignant progression of canine tumours via tumour angiogenesis

Current progress and perspectives for human tumor immunotherapy

The investigation of human tumor immunotherapy has remarkably advanced in the past decade. In our laboratory, human tumor antigens and their HLA-A24-restricted immunogenic peptide epitopes were determined to develop therapeutic and prophylactic human cancer vaccines. Among these peptides, survivin 2B peptide derived from survivin, an inhibitor of apoptosis protein (IAP), is immunogenic in more than 50% of cancer patients with a wide variety of tumors, including colon, pancreas, lung, breast, urinary bladder and oral cancers. It is now under clinical trials, and with careful immunological monitoring we will finally be able to know if these vaccines can work clinically.To develop a potent clinical therapeutic protocol, the immunological tumor escape mechanism should be more thoroughly examined in human tumor materials. To this end, anti-HLA-A, B, and C allele-specific monoclonal antibody EMR8-5, which can be used in routine paraffin-embedded sections, was successfully established. Unexpectedly, our data indicated that a high percentage of human cancers, particularly breast and prostate cancers, lost HLA-class I molecules in their primary cancer tissues. We will discuss possibilities for resolution of this important old but yet new problem.Although recent evidence has been accumulating for an important role of the heat shock proteins (HSPs) as so-called danger signals in initiating innate immunity and consequently activating acquired immunity, the precise immunological basis for this phenomenon remains to be elucidated. Our study indicated that certain HSP-chaperoned immunogenic peptides, particularly HSP90, could efficiently enter the cross-priming pathway in dendritic cells. Interestingly, this cross-priming was TAP-independent and followed endocytic pathways. We also showed that HSP90-chaperoned peptide complexes could work as a potential tumor therapeutic vaccine in the HLA-A24 transgenic mouse model

Phase I vaccination trial of SYT-SSX junction peptide in patients with disseminated synovial sarcoma

<p>Abstract</p> <p>Background</p> <p>Synovial sarcoma is a high-grade malignant tumor of soft tissue, characterized by the specific chromosomal translocation t(X;18), and its resultant SYT-SSX fusion gene. Despite intensive multimodality therapy, the majority of metastatic or relapsed diseases still remain incurable, thus suggesting a need for new therapeutic options. We previously demonstrated the antigenicity of SYT-SSX gene-derived peptides by in vitro analyses. The present study was designed to evaluate in vivo immunological property of a SYT-SSX junction peptide in selected patients with synovial sarcoma.</p> <p>Methods</p> <p>A 9-mer peptide (SYT-SSX B: GYDQIMPKK) spanning the SYT-SSX fusion region was synthesized. Eligible patients were those (i) who have histologically and genetically confirmed, unresectable synovial sarcoma (SYT-SSX1 or SYT-SSX2 positive), (ii) HLA-A*2402 positive, (iii) between 20 and 70 years old, (iv) ECOG performance status between 0 and 3, and (v) who gave informed consent. Vaccinations with SYT-SSX B peptide (0.1 mg or 1.0 mg) were given subcutaneously six times at 14-day intervals. These patients were evaluated for DTH skin test, adverse events, tumor size, tetramer staining, and peptide-specific CTL induction.</p> <p>Results</p> <p>A total of 16 vaccinations were carried out in six patients. The results were (i) no serious adverse effects or DTH reactions, (ii) suppression of tumor progression in one patient, (iii) increases in the frequency of peptide-specific CTLs in three patients and a decrease in one patient, and (iv) successful induction of peptide-specific CTLs from four patients.</p> <p>Conclusions</p> <p>Our findings indicate the safety of the SYT-SSX junction peptide in the use of vaccination and also give support to the property of the peptide to evoke in vivo immunological responses. Modification of both the peptide itself and the related protocol is required to further improve the therapeutic efficacy.</p