Biomarkers for non-human primate Type-I hypersensitivity: Antigen-specific immunoglobulin E assays

IgE Aggravates the Senescence of Smooth Muscle Cells in Abdominal Aortic Aneurysm by Upregulating LincRNA-p21

Immunoglobulin E (lgE) activates immunity by binding to mast cells and basophils. It is well-known that IgE and its receptor, FcɛR1, play a key role in the development of airway inflammation and remodeling in allergic asthma. Recent studies show that IgE also plays an important role in abdominal aortic aneurysm (AAA) pathogenesis. However, the mechanism by which IgE promotes AAA remains unclear. Here we report that in our mouse model, asthma-induced high level of IgE aggravated AAA, but IgE lost this effect on AAA in FcɛR1^-/- mice. Our in vitro study revealed that IgE induced smooth muscle cell senescence via upregulating lincRNA-p21 against p21 without altering expression of p53. By this mechanism, IgE accelerated AAA in ApoE^-/- mice, which was blocked by knockdown of lincRNA-p21 in both vitro and vivo. This study suggests that IgE actives the lincRNAp21-p21 pathway to induce SMC senescence, which contributes to the formation of AAA, and lincRNA-p21 is a potential therapeutic target for AAA aggravated by asthma.

Development of a peptide conjugate vaccine for inducing therapeutic anti-IgE antibodies

INTRODUCTION

Given the multifaceted effector functions of IgE in immediate hypersensitivity, late-phase reactions, regulation of IgE receptor expression and immune modulation, IgE antibodies have long represented an attractive target for therapeutic agents in asthma and other allergic diseases. Effective pharmacologic blockade of the binding of IgE to its receptors has become one of most innovative therapeutic strategies in the field of allergic diseases in the last 10 years. Areas covered: The latest strategies targeting IgE include the development of a therapeutic vaccine, able to trigger our own immune systems to produce therapeutic anti-IgE antibodies, potentially providing a further step forward in the treatment of allergic diseases. The aim of this review is to discuss the discovery strategy, preclinical and early clinical development of a peptide conjugate vaccine for inducing therapeutic anti-IgE antibodies. Expert opinion: Outside the area of development of humanized anti-IgE monoclonal antibodies, the research field of therapeutic IgE-targeted vaccines holds potential benefits for the treatment of allergic diseases. However, most of the experimental observations in animal models have not yet been translated into new treatments and evidence of human efficacy and safety of this new therapeutic strategy are still lacking.

Cynomolgus monkeys (Macaca fascicularis) experimentally infected with B19V and hepatitis A virus: no evidence of the co-infection as a cause of acute liver failure

This study was conducted to analyse the course and the outcome of the liver disease in the co-infected animals in order to evaluate a possible synergic effect of human parvovirus B19 (B19V) and hepatitis A virus (HAV) co-infection. Nine adult cynomolgus monkeys were inoculated with serum obtained from a fatal case of B19V infection and/or a faecal suspension of acute HAV. The presence of specific antibodies to HAV and B19V, liver enzyme levels, viraemia, haematological changes, and necroinflammatory liver lesions were used for monitoring the infections. Seroconversion was confirmed in all infected groups. A similar pattern of B19V infection to human disease was observed, which was characterised by high and persistent viraemia in association with reticulocytopenia and mild to moderate anaemia during the period of investigation (59 days). Additionally, the intranuclear inclusion bodies were observed in pro-erythroblast cell from an infected cynomolgus and B19V Ag in hepatocytes. The erythroid hypoplasia and decrease in lymphocyte counts were more evident in the co-infected group. The present results demonstrated, for the first time, the susceptibility of cynomolgus to B19V infection, but it did not show a worsening of liver histopathology in the co-infected group.

Immunogenicity of a peptide-based anti-IgE conjugate vaccine in non-human primates

The anti-human immunoglobulin E (IgE) monoclonal antibody, omalizumab (Xolair®, Genentech, South San Fransisco, CA), is effective in the treatment of poorly controlled moderate to severe allergic asthma and chronic idiopathic urticaria. It acts by specifically binding to the constant domain (Cϵ3) of free human IgE in the blood and interstitial fluid. Although efficacious, use of omalizumab is limited due to restrictions on patient weight and pre-existing IgE levels, and frequent dosing (q2-4 weeks). A vaccine inducing anti-IgE antibodies has the potential for similar clinical benefits with less frequent dosing and relatively lower cost of goods. We developed a vaccine containing two IgE peptide-conjugates targeting the Cϵ3 domain of human IgE. As part of preclinical evaluation of the vaccine to optimize formulation and dose prior to initiating clinical studies, we evaluated the vaccine in non-human primates, and demonstrate the induction of anti-peptide antibodies that can bind to conformationally intact human IgE and are capable, at least in some animals, of substantial lowering circulating IgE levels.

Formation, Clearance, Deposition, Pathogenicity, and Identification of Biopharmaceutical-related Immune Complexes

Vascular inflammation, infusion reactions, glomerulopathies, and other potentially adverse effects may be observed in laboratory animals, including monkeys, on toxicity studies of therapeutic monoclonal antibodies and recombinant human protein drugs. Histopathologic and immunohistochemical (IHC) evaluation suggests these effects may be mediated by deposition of immune complexes (ICs) containing the drug, endogenous immunoglobulin, and/or complement components in the affected tissues. ICs may be observed in glomerulus, blood vessels, synovium, lung, liver, skin, eye, choroid plexus, or other tissues or bound to neutrophils, monocytes/macrophages, or platelets. IC deposition may activate complement, kinin, and/or coagulation/fibrinolytic pathways and result in a systemic proinflammatory response. IC clearance is biphasic in humans and monkeys (first from plasma to liver and/or spleen, second from liver or spleen). IC deposition/clearance is affected by IC composition, immunomodulation, and/or complement activation. Case studies are presented from toxicity study monkeys or rats and indicate IHC-IC deposition patterns similar to those predicted by experimental studies of IC-mediated reactions to heterologous protein administration to monkeys and other species. The IHC-staining patterns are consistent with findings associated with generalized and localized IC-associated pathology in humans. However, manifestations of immunogenicity in preclinical species are generally not considered predictive to humans.

Immunogenicity/hypersensitivity of biologics

This continuing education course was designed to provide an overview of the immunologic mechanisms involved in immunogenicity and hypersensitivity reactions following administration of biologics in nonclinical toxicity studies, the methods used to determine whether such reactions are occurring, and the associated clinical and anatomic pathology findings. Hypersensitivity reactions have classically been divided into type I, II, III, and IV reactions; type I and III reactions are those most often observed following administration of biologics. A variety of methods can be used to detect these reactions. Antemortem methods include hematology; detection of antidrug antibodies, circulating immune complexes and complement fragments, and immunoglobulin E in serum; tests for serum complement activity; and evaluation of complement receptor 1 on erythrocytes. Postmortem methods include routine light microscopy and electron microscopy, which can demonstrate typical findings associated with hypersensitivity reactions, and immunohistochemistry, which can detect the presence of immune complexes in tissues, including the detection of the test article. A final determination of whether findings are related to a hypersensitivity reaction in individual animals or across the entire study should rely on the overall weight of evidence, as findings indicative of these reactions are not necessarily consistent across all affected animals.