Antibodies, Volume 4, Issue 4 (December 2015) – 7 articles , Pages 279-440

CD3 bispecific therapies retargeting T cells to tumors have recently demonstrated striking activity in patients. Several CD3 bispecific antibodies directed against various tumor targets are currently being investigated in the clinic across different tumors. One limitation of these therapies is the risk of target-related toxicity due to low-level expression of tumor antigen in normal tissue. In this study we have engineered a bispecific CD3/HER2 FynomAb, COVA420, which redirects T cells with high potency and selectivity to tumor cells with high HER2 expression in vitro and in vivo. COVA420 activity depends on high HER2 density as no activity was observed on cells with lower HER2 levels as found in human normal tissue. These results suggest that COVA420 may spare normal tissue expressing low levels of HER2 while still having uncompromised efficacy on tumor cells with high HER2 expression. This concept may be applied to other cancer antigens that otherwise cannot be targeted by T cell redirecting approaches, and may therefore expand the applicability of CD3 bispecific FynomAbs to a larger number of solid tumors. Full article

Sjögren’s syndrome, an autoimmune disease characterized by exocrine gland dysfunction leading to dry mouth and dry eye diseases, is typified by lymphoplasmacytic infiltrations and a progressive destruction of the salivary and lacrimal glands. Despite an ever-increasing focus on identifying the underlying etiology of Sjögren’s syndrome, the factors that initiate this autoimmune disease and the mechanisms that cause the subsequent exocrine gland dysfunction remain a mystery. The original explanatory concept for the pathogenesis of Sjögren’s syndrome proposed a specific, self-perpetuating, immune-mediated loss of acinar and ductal cells as the principal cause of salivary gland dysfunction. We highlight the possible involvement of regenerating gene (Reg) in the regeneration and destruction of salivary gland acinar and ductal cells in Sjögren’s syndrome. The Reg gene was originally isolated as a gene specifically overexpressed in regenerating pancreatic islets and constitutes a growth factor family (Reg family). We describe how salivary gland dysfunction is initiated and maintained and how it can be regenerated or progressed, mediated by the Reg gene, Reg protein, and anti-REG autoantibodies in Sjögren’s syndrome. Full article

Numerous studies have revealed the pleiotropic functions of tumor necrosis factor alpha (TNF-α), and have linked it with several neurodegenerative disorders. This review describes the signaling pathways induced by TNF-α via its two receptors (TNFR1 and TNFR2), and their functions in neurodegenerative processes as in Alzheimer’s disease (AD), Parkinson’s disease (PD), multiple sclerosis (MS), and ischemic stroke. It has become clear that TNF-α may exert divergent actions in neurodegenerative disorders, including neurodegenerative and neuroprotective effects, which appear to depend on its signaling via either TNFR1 or TNFR2. Specific targeting of these receptors is a promising therapeutic strategy for many disorders. Full article

Earlier studies showed that the DNA-binding protein, Bright/ARID3a bound to a subset of human and mouse immunoglobulin heavy chain promoters where it enhanced expression. Indeed, mice with transgenic expression of ARID3a in all B lymphocytes have expanded MZ B cells and produce anti-nuclear antibodies (ANAs). Consistent with our findings in mice, we observed that human systemic lupus erythematosus (SLE) patients had expanded numbers of peripheral blood ARID3a⁺ B cells that were associated with increased disease activity (p = 0.0038). We hypothesized that ARID3a⁺ naïve B cells would eventually produce autoantibodies, explaining associations between ARID3a expression and disease activity in lupus. Unlike healthy controls, ARID3a was expressed in the naïve B cell population in SLE patients, and we hypothesized that these might represent expansions of autoreactive cells. Therefore, monoclonal antibodies were generated from single-sorted naïve B cells derived from patients with normal (ARID3a^N) and high (ARID3a^H) numbers of ARID3a⁺ B cells. We found that ARID3a expression did not correlate with autoantibody expression. Furthermore, measures of antigen specificities of autoreactive antibodies did not reveal skewing toward particular proteins. These data suggest that the association of increased disease activity in SLE with numbers of ARID3a⁺ B lymphocytes may be mediated by an antibody-independent mechanism. Full article

The serological presence of autoantibodies is diagnostic of autoimmunity, and these autoantibodies may be present for many years before the presentation of autoimmune disease (AID). Although a pathogenic role has been demonstrated for various autoantibodies reactive with cell surface and extracellular autoantigens, studies using monoclonal antibodies (mAb) show not all antibodies in the polyclonal response are pathogenic. Differences depend on Fab-mediated diversity in epitope specificity, Fc-mediated effects based on immunoglobulin (Ig) class and subclass, activation of complement, and the milieu in which the reaction occurs. These autoantibodies often occur in organ-specific AID and this review illustrates their pathogenic and highly specific effects. The role of autoantibodies associated with intracellular antigens is less clear. In vitro they may inhibit or adversely affect well-defined intracellular biochemical pathways, yet, in vivo they are separated from their autoantigens by multiple cellular barriers. Recent evidence that Ig can traverse cell membranes, interact with intracellular proteins, and induce apoptosis has provided new evidence for a pathogenic role for such autoantibodies. An understanding of how autoantibodies behave in the polyclonal response and their role in pathogenesis of AID may help identify populations of culprit B-cells and selection of treatments that suppress or eliminate them. Full article

Oral vaccination against bacterial pathogens that infect via the gastrointestinal tract is highly desirable for both economic reasons and the supposed benefits of local mucosal immunity. However, the majority of oral vaccine trials in humans result in failure. Here we try to assimilate our current knowledge to generate a model to improve vaccine development strategies. A model previously postulated describes the “immunogenicity” of intestinal bacterial species as a sum of the ability of the species to compete with the microbiota, the “pathogenicity index,” and the uniqueness of the species. While this model quite neatly explains the difficulties in generating appropriately attenuated live vaccine strains, it cannot explain the success of fully apathogenic or inactivated high-dose vaccines. We therefore propose a step away from focusing on bacterial traits, and towards the most basic requirements of mucosal vaccines: i.e., the delivery of antigen to the gut-associated lymphoid tissues and the ability of that antigen to induce germinal center formation. While the models seem trivial, both suggest that vaccination strategies permitting uncoupling of disease-causing phenomena from immune stimulation will have a much broader safety margin in a diverse human population. Our modified model further suggests the benefits of delivering antigen in the form of high-dose fully apathogenic or sterile particles, combined with relevant adjuvants. Full article

B cell activation and antibody production against foreign antigens is a central step of host defense. This is achieved via highly regulated multi-phase processes that involve a variety of cells of both innate and adaptive arms of the immune system. MHC class II-restricted CD4⁺ T cells specific for peptide antigens, which acquire professional follicular B cell helper functions, have been long recognized as key players in this process. Recent data, however, challenge this paradigm by showing the existence of other helper cell types. CD1d restricted NKT cells specific for lipid antigens are one such new player and can coopt bona fide follicular helper phenotypes. Their role in helping antigen-specific B cell response to protein antigens, as well as to the so called “help-less” antigens that cannot be recognized by T follicular helper cells, is being increasingly elucidated, highlighting their potential pathophysiological impact on the immune response, as well as on the design of improved vaccine formulations. Full article