Phase I Clinical Trial of Autologous Ascites-derived Exosomes Combined With GM-CSF for Colorectal Cancer

Induction of Tumor-specific Immune Response by Gene Transfer of Hsp70-cell-penetrating Peptide Fusion Protein to Tumors in Mice

T84-Intestinal Epithelial Exosomes Bear MHC Class II/Peptide Complexes Potentiating Antigen Presentation by Dendritic Cells

Exovesicles from Human Activated Dendritic Cells Fuse with Resting Dendritic Cells, Allowing Them to Present Alloantigens

The endoplasmic reticulum-located multimolecular peptide-loading complex functions to load optimal peptides onto major histocompatibility complex (MHC) class I molecules for presentation to CD8(+) T lymphocytes. Two oxidoreductases, ERp57 and protein-disulfide isomerase, are known to be components of the peptide-loading complex. Within the peptide-loading complex ERp57 is normally found disulfide-linked to tapasin, through one of its two thioredoxin-like redox motifs. We describe here a novel trimeric complex that disulfide links together MHC class I heavy chain, ERp57 and tapasin, and that is found in association with the transporter associated with antigen processing peptide transporter. The trimeric complex normally represents a small subset of the total ERp57-tapasin pool but can be significantly increased by altering intracellular oxidizing conditions. Direct mutation of a conserved structural cysteine residue implicates an interaction between ERp57 and the MHC class I peptide-binding groove. Taken together, our studies demonstrate for the first time that ERp57 directly interacts with MHC class I molecules within the peptide-loading complex and suggest that ERp57 and protein-disulfide isomerase act in concert to regulate the redox status of MHC class I during antigen presentation.

Exosomes and the kidney: prospects for diagnosis and therapy of renal diseases

d t For many decades, cell-free nucleic acids have been known to be present in peripheral blood. Several tudies have identified tumor-specific and/or tumor-assoiated alterations in the circulating nucleic acids of paients with various cancers. In recent years, cell-free miroRNA (miRNA) have been stably detected in the plasma nd serum, like other molecules; their presence in the lood has attracted the attention of researchers due to heir potential use as valuable blood biomarkers.1 MiRNAs are short, noncoding RNAs that play important roles in various physiologic and developmental processes. The mature miRNAs are produced from long primary transcripts through 2 sequential cleavage steps. The long primary miRNA transcript is cleaved by the Drosha complex in the nucleus, generating intermediate precursor miRNA. Precursor miRNA is transported by exportin-5 from the nucleus into the cytoplasm, and then subjected to further cleavage by a Dicer RNAase III enzyme, generating a short double-strand miRNA. One strand (guided strand) of mature miRNA is then incorporated into the RNA-induced silencing complex and subsequently hybridize to the 3=-untranslated region of their target mRNAs to repress translation or degrade these mRNAs. Thus, a single miRNA can influence the expression of hundreds of genes and allow them to function in a coordinated manner. Therefore, miRNAs have been implicated as key molecules in all cellular processes. Numerous studies have shown that alterations in miRNA expression correlate with various diseases, including the development and progression of cancer, and some miRNAs can function as oncogenes or tumor suppressors. These findings have opened up a new and interesting field in the diagnosis of cancer and the treatments of cancer patients. Mitchell et al2 first demonstrated that circulating miRNAs had the potential to be new biomarkers in patients with solid cancers. In recent years, several papers have demonstrated that circulating miRNAs can also be detected in the peripheral blood of patients with digestive tract cancers. Although the origins and physiologic functions of cell-free miRNAs in the blood remain to be fully elucidated, a noninvasive assay for miRNAs should be developed to exploit these molecules as potential diagnostic and prognostic biomarkers. This assay undoubtedly contributes to an improvement in the clinical outcomes of cancer patients. In this article, we review the current state of biological and clinical research regarding circulating miRNAs of digestive tract cancer patients and discuss the future perspectives.

Monoclonal T-Cell Receptors: New Reagents for Cancer Therapy

Human cytomegalovirus (HCMV1) US11 and US2 proteins cause rapid degradation of major histocompatibility complex (MHC) molecules, apparently by ligating cellular endoplasmic reticulum (ER)-associated degradation machinery. Here, we show that US11 and US2 bind the ER chaperone BiP. Four related HCMV proteins, US3, US7, US9, and US10, which do not promote degradation of MHC proteins, did not bind BiP. Silencing BiP reduced US11- and US2-mediated degradation of MHC class I heavy chain (HC) without altering the synthesis or translocation of HC into the ER or the stability of HC in the absence of US11 or US2. Induction of the unfolded protein response (UPR) did not affect US11-mediated HC degradation and could not explain the stabilization of HC when BiP was silenced. Unlike in yeast, BiP did not act by maintaining substrates in a retrotranslocation-competent form. Our studies go beyond previous observations in mammalian cells correlating BiP release with degradation, demonstrating that BiP is functionally required for US2- and US11-mediated HC degradation. Further, US2 and US11 bound BiP even when HC was absent and degradation of US2 depended on HC. These data were consistent with a model in which US2 and US11 bridge HC onto BiP promoting interactions with other ER-associated degradation proteins.

Human immunodeficiency virus, type 1 Nef disrupts viral antigen presentation and promotes viral immune evasion from cytotoxic T lymphocytes. There is evidence that Nef acts early in the secretory pathway to redirect major histocompatibility complex class I (MHC-I) from the trans-Golgi network to the endolysosomal pathway. However, a competing model suggests that Nef acts much later by accelerating MHC-I turnover at the cell surface. Here we demonstrate that Nef targets early forms of MHC-I molecules in the endoplasmic reticulum by preferentially binding hypophosphorylated cytoplasmic tails. The Nef-MHC-I complex migrates normally into the Golgi apparatus but subsequently fails to arrive at the cell surface and become phosphorylated. Cell type-specific differences in the rate of MHC-I transport through the secretory pathway correlate with responsiveness to Nef and co-precipitation of adaptor protein 1 with the Nef.MHC-I complex. We propose that the assembly of a Nef.MHC-I.adaptor protein 1 complex early in the secretory pathway is important for Nef activity.

Hereditary hemochromatosis: update for 2003

IDO in Colorectal Tumorigenesis: Involvement of Immune Tolerance and Significance in Prevention and Therapy

The discovery of the new haemochromatosis gene: Feder JN, Gnirke A, Thomas W, Tsuchihashi Z, Ruddy DA, Basava A, et al. A novel MHC class I-like gene is mutated in patients with hereditary haemochromatosis [Nat Genet 1996;13:399–408

Polysialic acid (PSA) is a unique linear homopolymer of alpha2,8-linked sialic acid that has been identified as a posttranslational modification on only five mammalian proteins. Studied predominantly on neural cell adhesion molecule (NCAM) during development of the vertebrate nervous system, PSA modulates cell interactions mediated by NCAM and other adhesion molecules. An isoform of NCAM (CD56) on natural killer (NK) cells is the only protein known to be polysialylated in cells of the immune system, yet the function of PSA in NK cells remains unclear. We show here that neuropilin-2 (NRP-2), a receptor for the semaphorin and vascular endothelial growth factor families in neurons and endothelial cells, respectively, is expressed on the surface of human dendritic cells and is polysialylated. Expression of NRP-2 is up-regulated during dendritic cell maturation, coincident with increased expression of ST8Sia IV, one of the key enzymes of PSA biosynthesis, and with the appearance of PSA on the cell surface. PSA on NRP-2 is resistant to digestion with peptide N-glycosidase F but is sensitive to release under alkaline conditions, suggesting that PSA chains are added to O-linked glycans of NRP-2. Removal of polysialic acid from the surface of dendritic cells or binding of NRP-2 with specific IgG promoted dendritic cell-induced activation and proliferation of T lymphocytes. Thus, this newly recognized polysialylated protein on the surface of dendritic cells influences dendritic cell-T lymphocyte interactions through one or more of its distinct extracellular domains.

Active Uptake of Dendritic Cell-Derived Exovesicles by Epithelial Cells Induces the Release of Inflammatory Mediators through a TNF-α-Mediated Pathway

The Connecdenn DENN Domain: A GEF for Rab35 Mediating Cargo-Specific Exit from Early Endosomes