A monoclonal antibody targeting nonjunctional claudin-1 inhibits fibrosis in patient-derived models by modulating cell plasticity.

Tissue fibrosis is a key driver of end-stage organ failure and cancer, overall accounting for up to 45% of deaths in developed countries. There is a large unmet medical need for antifibrotic therapies. Claudin-1 (CLDN1) is a member of the tight junction protein family.

Treatment of HCC with claudin-1-specific antibodies suppresses carcinogenic signaling and reprograms the tumor microenvironment.

Background & Aims: Despite recent approvals, the response to treatment and prognosis of patients with advanced hepatocellular carcinoma (HCC) remain poor. Claudin-1 (CLDN1) is a membrane protein that is expressed at tight junctions, but it can also be exposed non-junctionally, such as on the basolateral membrane of the human hepatocyte. While CLDN1 within tight junctions is well characterized, the role of non-junctional CLDN1 and its role as a therapeutic target in HCC remains unexplored.

Fingerprints of CD8+ T cells on human pre-plasma and memory B cells.

Differentiation of B cells is a stringently controlled multi-step process, which is still incompletely understood. Here we identify and characterize a rare population of human B cells, which surprisingly carry CD8AB on their surface. Existence of such cells was demonstrated both in tonsils and in human apheresis material.

Human CD180 Transmits Signals via the PIM-1L Kinase.

Toll-like receptors (TLRs) are important sensors of the innate immune system that recognize conserved structural motifs and activate cells via a downstream signaling cascade. The CD180/MD1 molecular complex is an unusual member of the TLR family, since it lacks the components that are normally required for signal transduction by other TLRs. Therefore the CD180/MD 1 complex has been considered of being incapable of independently initiating cellular signals.

Luminal decoration of blood vessels by activated perivasal mast cells in allergic rhinitis.

Background: In allergic diseases, like in rhinitis, antigen challenge induces rapid degranulation of tissue resident mast cells and subsequent recruitment of leukocytes in response to soluble immunmodulators. The fate of mast cell-derived, membrane associated factors in inflamed tissue remained however unresolved.

Methods: Components of the mast cell granular membrane, including the unique marker CD63var, were examined by FACS and by confocal laser scanning microscopy in cell culture and in diseased human tissue.

SAP-mediated inhibition of diacylglycerol kinase α regulates TCR-induced diacylglycerol signaling.

Diacylglycerol kinases (DGKs) metabolize diacylglycerol to phosphatidic acid. In T lymphocytes, DGKα acts as a negative regulator of TCR signaling by decreasing diacylglycerol levels and inducing anergy. In this study, we show that upon costimulation of the TCR with CD28 or signaling lymphocyte activation molecule (SLAM), DGKα, but not DGKζ, exits from the nucleus and undergoes rapid negative regulation of its enzymatic activity.

A granular variant of CD63 is a regulator of repeated human mast cell degranulation.

Background: Mast cells are secretory immune cells whose degranulation can provoke acute allergic reactions. It is presently unclear, however, whether an individual mast cell can repeatedly degranulate or turns dysfunctional after a single antigen stimulus. This work thus aims to better define the mast cell life cycle, with particular focus on new target structures for therapeutic or diagnostic approaches in allergy.

Molecular cancer vaccines: Tumor therapy using antigen-specific immunizations.

Vaccination against tumors promises selective destruction of malignant cells by the host's immune system. Molecular cancer vaccines rely on recently identified tumor antigens as immunogens. Tumor antigens can be applied in many forms, as genes in recombinant vectors, as proteins or peptides representing T cell epitopes.

EWI-2/CD316 is an inducible receptor of HSPA8 on human dendritic cells.

The activation of dendritic cells is marked by changes both on their cell surfaces and in their functions. We define EWI-2/CD316 as an early activation marker of dendritic cells upregulated by Toll-like receptor ligands clearly before CD86 and CD83. By expression cloning, human heat shock protein A8 (HSPA8), a member of the hsp70 family, was identified as the ligand for EWI-2.

Inhibition of human cord blood-derived mast cell responses by anti-Fc epsilon RI mAb 15/1 versus anti-IgE Omalizumab.

Aggregation of the alpha-chain of the high affinity IgE receptor (Fc epsilon RI alpha) on mast cells or basophils after cross-linking of receptor-bound IgE by its antigen or an anti-IgE antibody results in cell activation and release of inflammatory mediators. Omalizumab (Xolair), Novartis Pharmaceuticals; Genentech Inc.) is a recombinant humanized anti-IgE mAb developed for the treatment of severe allergic asthma.

Reconstitution of human telomerase reverse transcriptase expression rescues colorectal carcinoma cells from in vitro senescence: evidence against immortality as a constitutive trait of tumor cells.

Although in vitro establishment of new colorectal carcinoma (CRC) cell lines is an infrequent event, we have observed that primary cultures of CRC can be repeatedly and reproducibly initiated following in vitro plating of tumor-derived epithelial cells. These cultures, however, usually display a short life span as they undergo a limited number of cell passages before entering a state of irreversible growth arrest. In this study, we show that short-lived CRC primary cultures lack constitutive telomerase activity and undergo a senescence process characterized by progressive telomere shortening.

In vivo plasmid DNA electroporation generates exceptionally high levels of epitope-specific CD8+ T-cell responses.

Based on observations that DBA/2 mice develop a highly specific response towards an HLA-Cw3-derived epitope, consisting entirely of CD8+CD62L-Vbeta10+ cells, we have established an in vivo mouse model for screening a variety of immunization approaches. Responder cells were readily detectable in small samples of the peripheral blood using three-color FACS analysis. This permitted multiple, sequential determination of CD8+ T-cell responses in living animals at a very high degree of precision.

In vivo plasmid electroporation induces tumor antigen-specific CD8+ T-cell responses and delays tumor growth in a syngeneic mouse melanoma model.

Plasmid DNA-based molecular cancer vaccines generally suffer from suboptimal immunogenicity. One of the key limitations is insufficient level of gene expression, which was surmounted in our approach by using the novel technique of in vivo plasmid electroporation-enhanced vaccination (electrovaccination). Electrovaccination with plasmids encoding the full-length autologous melanocyte antigen tyrosinase-related protein-2 induced limited melanocyte destruction in a subset of mice.

Structural elements of a protein antigen determine immunogenicity of the embedded MHC class I-restricted T cell epitope.

Substantial effort has been invested into optimization of vector structure, DNA formulation, or delivery methods to increase the effectiveness of DNA vaccines. In contrast, it has been only insufficiently explored how the higher order structure of an antigenic protein influences immunogenicity of embedded epitopes in vivo. Potent CD8+ T cell responses specific for a single immunogenic epitope are induced upon electrovaccination with plasmid DNA encoding the full-length heavy chain of the human HLA-Cw3 molecule.

Identification of HLA-A*0201-restricted T cell epitopes derived from the novel overexpressed tumor antigen calcium-activated chloride channel 2.

Vaccination against tumor Ags may become a promising treatment modality especially in cancer types where other therapeutic approaches fail. However, diversity of tumors requires that a multitude of Ags become available. Differential expression in normal vs cancerous tissues, both at the mRNA and the protein level, may identify Ag candidates.

Activation requirements of circulating antigen-specific human CD8(+) memory T cells probed with insect cell-based artificial antigen-presenting cells.

We sought to define the molecular setup of an antigen-presenting cell that elicits antigen-specific T cell responses in vitro using insect cells that were infected with recombinant baculoviruses. Expression of single-chain HLA was complemented step-by-step with costimulatory molecules, including CD54 and CD80, by co-infection with the relevant viruses. Role of CD8 was assessed by introducing hybrid class I molecules where the alpha-3 domain of the HLA heavy chain molecule was replaced by its murine K(b) counterpart.

Interleukin-2 gene-modified allogeneic melanoma cell vaccines can induce cross-protection against syngeneic tumors in mice.

Vaccination using well-characterized allogeneic tumor cell lines expressing standardized doses of immunostimulatory cytokines is an attractive alternative for autologous gene-transfected tumor cell vaccines. In the present study, we show that vaccination with irradiated allogeneic K1 735 (H-2k) or B16F10 (H-2b) melanoma cells induces a moderate degree of cross-protection against the M-3 melanoma (H-2d) in DBA/2 mice. Cross-protection against the syngeneic tumor was markedly improved when the allogeneic vaccines were transfected with the interleukin-2 (IL-2) gene.

CD44-deficient mice develop normally with changes in subpopulations and recirculation of lymphocyte subsets.

Cell adhesion molecules are considered to be pivotal elements required for proper embryo development. The transmembrane glycoprotein CD44, which is expressed in numerous splice variants on the surface of many different cell types and tissues, has been suggested to be involved in several physiological processes such as cell-cell interactions, signal transduction, and lymphocyte homing and trafficking during embryogenesis and in the adult organism. Some splice variants are thought to play an important role in tumor progression.

Generation of effective cancer vaccines genetically engineered to secrete cytokines using adenovirus-enhanced transferrinfection (AVET).

Cancer vaccines are based on the concept that tumors express novel antigens and thus differ from their normal tissue counterparts. Such putative tumor-specific antigens should be recognizable by the immune system. However, malignant cells are of self origin and only poorly immunogenic, which limits their capability to induce an anticancer immune response.

Tumor cells expressing a recall antigen are powerful cancer vaccines.

Tumor cells were engineered to express a specific recall antigen molecule to serve as a target for the host's existing memory response, and then used as immunogens as a novel form of cancer vaccine. As recall antigen, the efficiently expressible hybrid protein Heat1 was employed, that contains an antigenic fragment of the Mycobacterium bovis 65-kDa heat shock protein (hsp65), and thus can be recognized in mice immunized with live Bacillus Calmette-Guérin (BCG) or its derivatives. Mouse M-3 melanoma cells were transfected to express Heat1, irradiated, and used as anti-melanoma vaccines.

Transloading of tumor cells with foreign major histocompatibility complex class I peptide ligand: a novel general strategy for the generation of potent cancer vaccines.

The major hurdle to be cleared in active immunotherapy of cancer is the poor immunogenicity of cancer cells. In previous attempts to overcome this problem, whole tumor cells have been used as vaccines, either admixed with adjuvant(s) or genetically engineered to express nonself proteins or immunomodulatory factors before application. We have developed a novel approach to generate an immunogeneic, highly effective vaccine: major histocompatibility complex (MHC) class I-positive cancer cells are administered together with MHC class I-matched peptide ligands of foreign, nonself origin, generated by a procedure we term transloading.

Adenovirus-enhanced receptor-mediated transferrinfection for the generation of tumor vaccines.

Cancer vaccines are genetically modified tumor cells that, by cytokine secretion or by expression of costimulatory molecules, are capable of mobilizing the host's immune system to destroy tumor cells. We have used adenovirus-enhanced transferrinfection (AVET) for the generation of cancer vaccines. This is a highly efficient method to deliver various genes into a large proportion of tumor cells, making further selection unnecessary.

Depletion of naive T cells of the peripheral lymph nodes abrogates systemic antitumor protection conferred by IL-2 secreting cancer vaccines.

It has been postulated that IL-2 secreting cancer vaccines establish antitumor immunity because the cytokine acting in a paracrine fashion would deliver a helper signal directly to the T cells making contact with the modified tumor cells at the site of vaccination. However, patterns of lymphocyte recirculation cannot be reconciled with the above direct interaction model: only primed memory T cells rather than naive T lymphocytes patrol the periphery, while naive T cells travel to the peripheral lymph nodes, where priming occurs. We have found that in vivo treatment of mice with the antibody MEL-14 directed against L-selectin, which is a molecule expressed at high levels on naive T cells, can completely abrogate protection against a mouse melanoma conferred by an IL-2 secreting vaccine.

Priming of tumor-specific T cells in the draining lymph nodes after immunization with interleukin 2-secreting tumor cells: three consecutive stages may be required for successful tumor vaccination.

Although both CD4+ and CD8+ T cells are clearly required to generate long-lasting anti-tumor immunity induced by s.c. vaccination with interleukin 2 (IL-2)-transfected, irradiated M-3 clone murine melanoma cells, some controversy continues about the site and mode of T-cell activation in this system.

Cancer vaccines: the interleukin 2 dosage effect.

Cancer vaccines genetically engineered to produce interleukin 2 have been investigated intensively in a series of animal models and are at the point of entering into clinical trials. In this study we demonstrate a strong correlation between the rate of interleukin 2 production and the protection efficiency of murine S91 melanoma cell (clone M-3) vaccines. Best immunization is achieved with vaccines producing medium interleukin 2 levels of 1000-3000 units per 10(5) cells per day.