Mutated cancer autoantigen implicated cause of paraneoplastic myasthenia gravis.

INTRODUCTION: Antitumor immune responses are postulated to initiate paraneoplastic neurological disorders when proteins that are normally restricted to neural cells are expressed as oncoproteins. Mutated oncopeptides could bypass self-tolerant T cells to activate cytotoxic effector T lymphocytes and requisite helper T lymphocytes to stimulate autoantibody production by B lymphocytes. METHODS: We investigated muscle-type nicotinic acetylcholine receptor (AChR) antigen expression at transcriptional and protein levels in a small-cell lung cancer line (SCLC) established from a patient with AChR-immunoglobulin G (IgG)-positive myasthenia gravis. RESULTS: We identified messenger RNA transcripts encoding the 2 AChR α1-subunit isoforms and 7 alternative-splicing products, 3 of which yielded premature stop codons. Despite detecting native muscle-type AChR pentamers in the tumor, we did not identify mutant α1-peptides. However, we found α1-subunit-derived peptides bound to tumor major histocompatibility complex (MHC)1-protein. In a control SCLC from an antineuronal nuclear autoantibody, type 1 (anti-Hu)-IgG-positive patient, we identified MHC1-complexed Hu protein-derived peptides but not AChR peptides. DISCUSSION: Our findings support onconeural protein products as pertinent immunogens initiating paraneoplastic neurological autoimmunity. Muscle Nerve 58: 600-604, 2018.

PEGylation of vesicular stomatitis virus extends virus persistence in blood circulation of passively immunized mice.

We are developing oncolytic vesicular stomatitis viruses (VSVs) for systemic treatment of multiple myeloma, an incurable malignancy of antibody-secreting plasma cells that are specifically localized in the bone marrow. One of the presumed advantages for using VSV as an oncolytic virus is that human infections are rare and preexisting anti-VSV immunity is typically lacking in cancer patients, which is very important for clinical success. However, our studies show that nonimmune human and mouse serum can neutralize clinical-grade VSV, reducing the titer by up to 4 log units in 60 min. In addition, we show that neutralizing anti-VSV antibodies negate the antitumor efficacy of VSV, a concern for repeat VSV administration. We have investigated the potential use of covalent modification of VSV with polyethylene glycol (PEG) or a function-spacer-lipid (FSL)-PEG construct to inhibit serum neutralization and to limit hepatosplenic sequestration of systemically delivered VSV. We report that in mice passively immunized with neutralizing anti-VSV antibodies, PEGylation of VSV improved the persistence of VSV in the blood circulation, maintaining a more than 1-log-unit increase in VSV genome copies for up to 1 h compared to the genome copy numbers for the non-PEGylated virus, which was mostly cleared within 10 min after intravenous injection. We are currently investigating if this increase in PEGylated VSV circulating half-life can translate to increased virus delivery and better efficacy in mouse models of multiple myeloma.

Concentrations and correlations for eight metals in human liver.

This study was undertaken to determine concentrations for eight metals in human liver and investigate correlations among these metals as well as subject age. Autopsy specimens from 32 males, ranging from 38-88 years of age, were analyzed for calcium (Ca), cadmium (Cd), copper (Cu), iron (Fe), mercury (Hg), magnesium (Mg), lead (Pb), and zinc (Zn). Respective mean concentrations were 49.6, 2.1, 4.9, 318.7, 0.72, 135.2, 0.19, and 53.4 microg/g wet wt., and 209.2, 8.8, 20.6, 1342.2, 0.81, 569.4, 3.1 and 228.8 microg/g dry wt. Variables, including age and metal concentrations, were subjected to simple and multiple correlation analysis. Four metal pairs Zn-Cd, Fe-Pb, Mg-Hg, and Mg-Zn gave significant positive correlations. Age and Cu correlated negatively. Multiple correlations were found for Mg with Hg and Zn, Pb with Fe and age, Pb with Fe and Cu, and Zn with Mg and Cd. Results are discussed within the context of relevant literature.

Neutralization capacity of measles virus H protein specific IgG determines the balance between antibody-enhanced infectivity and protection in microglial cells.

Neutralizing antibodies directed against measles virus (MV) surface glycoproteins prevent viral attachment and entry through the natural receptors. H protein specific IgG can enhance MV infectivity in macrophages via Fcγ receptor (FcγR)-dependent mechanism. H-specific IgM, anti-F antibodies and complement cascade activation are protective against antibody-mediated enhancement of MV infection. However, protective role of anti-H IgG against antibody-enhanced infection is not well understood. Here we designed a set of experiments to test the protective effect of H-specific IgG against FcγR-mediated infection in microglial cells. Microglial cells are also potential target of the antibody-mediated enhancement and spread of MV infection in the central nervous system. A partially neutralizing IgG monoclonal antibody (MAb) CL55, specific for MV H protein, at 10 µg/ml enhanced MV infection in mouse microglial cells by 13-14-fold. Infection-enhancing antibody concentrations induced large multinucleated syncytia formation 48-72 h post-inoculation. We generated anti-H IgG MAb 20H6 with a strong neutralization capacity >1:80,000 at 1mg/ml concentration in MV plaque-reduction neutralization assay. In contrast to the partially protective MAb CL55, enhancement of MV infectivity by MAb 20H6 required dilutions below the 1:120 serum titer considered protective against measles infection in humans. At a concentration of 10 µg/ml MAb 20H6 exhibited a dominant protective effect and prevented MAb CL55-mediated enhancement of MV infection and virus-mediated fusion. These results indicate that neutralization capacity of the H-specific IgG determines the balance between antibody enhancement and protection against MV infection in microglial cells.

Safety studies on intrahepatic or intratumoral injection of oncolytic vesicular stomatitis virus expressing interferon-beta in rodents and nonhuman primates.

Toxicology studies were performed in rats and rhesus macaques to establish a safe starting dose for intratumoral injection of an oncolytic vesicular stomatitis virus expressing human interferon-beta (VSV-hIFNbeta) in patients with hepatocellular carcinoma (HCC). No adverse events were observed after administration of 7.59 x 10(9) TCID(50) (50% tissue culture infective dose) of VSV-hIFNbeta into the left lateral hepatic lobe of Harlan Sprague Dawley rats. Plasma alanine aminotransferase and alkaline phosphatase levels increased and platelet counts decreased in the virus-treated animals on days 1 and 2 but returned to pretreatment levels by day 4. VSV-hIFNbeta was also injected into normal livers or an intrahepatic McA-RH7777 HCC xenograft established in Buffalo rats. Buffalo rats were more sensitive to neurotoxic effects of VSV; the no observable adverse event level (NOAEL) of VSV-hIFNbeta in Buffalo rats was 10(7) TCID(50). Higher doses were associated with fatal neurotoxicity and infectious virus was recovered from tumor and brain. Compared with VSV-hIFNbeta, toxicity of VSV-rIFNbeta (recombinant VSV expressing rat IFN-beta) was greatly diminished in Buffalo rats (NOAEL, >10(10) TCID(50)). Two groups of two adult male rhesus macaques received 10(9) or 10(10) TCID(50) of VSV-hIFNbeta injected directly into the left hepatic lobe under computed tomographic guidance. No neurological signs were observed at any time point. No abnormalities (hematology, clinical chemistry, body weights, behavior) were seen and all macaques developed neutralizing anti-VSV antibodies. Plasma interleukin-6, tumor necrosis factor-alpha, and hIFN-beta remained below detection levels by ELISA. On the basis of these studies, we will be proposing a cautious approach to dose escalation in a phase I clinical trial among patients with HCC.

Immunoglobulin g antibody-mediated enhancement of measles virus infection can bypass the protective antiviral immune response.

Antibodies to viral surface glycoproteins play a crucial role in immunity to measles by blocking both virus attachment and subsequent fusion with the host cell membrane. Here, we demonstrate that certain immunoglobulin G (IgG) antibodies can also enhance the entry of measles virus (MV) into monocytes and macrophages. Antibody-dependent enhancement of infectivity was observed in mouse and human macrophages using virions opsonized by a murine monoclonal antibody against the MV hemagglutinin (H) glycoprotein, polyclonal mouse anti-MV IgG, or diluted measles-immune human sera. Neither H-specific Fab fragments nor H-specific IgM could enhance MV entry in monocytes or macrophages, indicating involvement of a Fc gamma receptor (FcgammaR)-mediated mechanism. Preincubation with an anti-fusion protein (anti-F) monoclonal antibody or a fusion-inhibitory peptide blocked infection, indicating that a functional F protein was required for viral internalization. Classical complement pathway activation did not promote infection through complement receptors and inhibited anti-H IgG-mediated enhancement. In vivo, antibody-enhanced infection allowed MV to overcome a highly protective systemic immune response in preimmunized IfnarKo-Ge46 transgenic mice. These data demonstrate a previously unidentified mechanism that may contribute to morbillivirus pathogenesis where H-specific IgG antibodies promote the spread of MV infection among FcgammaR-expressing host cells. The findings point to a new model for the pathogenesis of atypical MV infection observed after immunization with formalin-inactivated MV vaccine and underscore the importance of the anti-F response after vaccination.