IgE production against innocuous food antigens can result in anaphylaxis, a severe life-threatening consequence of allergic reactions. The maintenance of IgE immunity is primarily facilitated by IgG+ ...memory B cells, as IgE+ memory B cells and IgE+ plasma cells are extremely scarce and short-lived, respectively.
Our aim was to investigate the critical requirements for an IgE recall response in peanut allergy.
We used a novel human PBMC culture platform, a mouse model of peanut allergy, and various experimental readouts to assess the IgE recall response in the presence and absence of IL-4Rα blockade.
In human PBMCs, we have demonstrated that blockade of IL-4/IL-13 signaling aborted IgE production after activation of a recall response and skewed the cytokine response away from a dominant type 2 signature. TH2A cells, identified by single-cell RNA sequencing, expanded with peanut stimulation and maintained their pathogenic phenotype in spite of IL-4Rα blockade. In mice with allergy, anti–IL-4Rα provided long-lasting suppression of the IgE recall response beyond antibody treatment and fully protected against anaphylaxis.
The findings reported here advance our understanding of events mediating the regeneration of IgE in food allergy.
Antibody responses are critical for protection against pathogens. However, diseases such as allergic rhinitis or food allergy result from aberrant production of IgE antibodies against otherwise ...innocuous environmental antigens. The production of allergen-specific IgE requires interaction between B cells and CD4+ T cells, and a granular understanding of these interactions is required to develop novel therapies for allergic disease. CD4+ T cells are exceptionally heterogeneous in their transcriptional, epigenetic, and proteomic profiles, which poses significant challenges when attempting to define subsets relevant to the study of allergy among a continuum of cells. Defining subsets such as the T follicular helper (TFH) cell cluster provides a shorthand to understand the functions of CD4+ T cells in antibody production and supports mechanistic experimentation for hypothesis-driven discovery. With a focus on allergic disease, this Rostrum article broadly discusses heterogeneity among CD4+ T cells and provides a rationale for subdividing TFH cells into both functional and cytokine-skewed subsets. Further, it highlights the plasticity demonstrated by TFH cells during the primary response and after recall, and it explores the possibility of harnessing this plasticity to reprogram immunity for therapeutic benefit in allergic disease.
The emerging SARS-CoV-2 variants of concern (VOCs) threaten the effectiveness of current COVID-19 vaccines administered intramuscularly and designed to only target the spike protein. There is a ...pressing need to develop next-generation vaccine strategies for broader and long-lasting protection. Using adenoviral vectors (Ad) of human and chimpanzee origin, we evaluated Ad-vectored trivalent COVID-19 vaccines expressing spike-1, nucleocapsid, and RdRp antigens in murine models. We show that single-dose intranasal immunization, particularly with chimpanzee Ad-vectored vaccine, is superior to intramuscular immunization in induction of the tripartite protective immunity consisting of local and systemic antibody responses, mucosal tissue-resident memory T cells and mucosal trained innate immunity. We further show that intranasal immunization provides protection against both the ancestral SARS-CoV-2 and two VOC, B.1.1.7 and B.1.351. Our findings indicate that respiratory mucosal delivery of Ad-vectored multivalent vaccine represents an effective next-generation COVID-19 vaccine strategy to induce all-around mucosal immunity against current and future VOC.
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•Two trivalent adenoviral-vectored COVID-19 vaccines were developed and evaluated•Intranasal, but not intramuscular, immunization induces tripartite mucosal immunity•Intranasal immunization protects against ancestral and variant strains of SARS-CoV-2•Optimal protection requires B and T cell immunity and trained innate immunity
Respiratory mucosal immunization with a next-generation adenoviral-vectored trivalent COVID-19 vaccine expressing spike, nucleocapsid, and RdRp antigens, induces all-around protective mucosal immunity against SARS-CoV-2 via induction of systemic and local antibodies, lung-tissue-resident memory T cells, and trained alveolar macrophages.
B cells generate antibodies that provide protection from infection, but also cause pathology in autoimmune and allergic conditions. Antigen-specific B cells can be detected by binding their surface ...antibody receptors with native antigens conjugated to fluorescent probes, a technique that has revealed substantial insight into B cell activation and function. This protocol describes the process of generating fluorescent antigen tetramer probes and delineates a process of enriching large samples based on antigen-specificity for high-resolution analyses of the antigen-specific B cell repertoire. Enrichment of tetramer-binding cells allows for detection of antigen-specific B cells as rare as 1 in 100 million cells, providing sufficient resolution to study naive B cells and IgE-expressing cells by flow cytometry. The generation of antigen tetramers involves antigen biotinylation, assessment of biotin:antigen ratio for optimal tetramer loading and polymerization around a streptavidin-fluorophore backbone. We also describe the construction of a control tetramer to exclude B cells binding to the tetramer backbone. We provide a framework to validate whether tetramer probes are detecting true antigen-specific B cells and discuss considerations for experimental design. This protocol can be performed by researchers trained in basic biomedical/immunological research techniques, using instrumentation commonly found in most laboratories. Constructing the antigen and control tetramers takes 9 h, though their specificity should be assessed before experimentation and may take weeks to months depending on the method of validation. Sample enrichment requires ~2 h but is generally time and cost neutral as fewer cells are run through the flow cytometer.
The IgE memory reservoir in food allergy Jiménez-Saiz, Rodrigo; Bruton, Kelly; Koenig, Joshua F.E. ...
Journal of allergy and clinical immunology,
November 2018, 2018-11-00, 20181101, Volume:
142, Issue:
5
Journal Article
Peer reviewed
Open access
The half-life of allergen-specific IgE+ PCs was calculated to be only 60 days in a mouse model of food allergy and anaphylaxis,1 which is consistent with the evidence that IgE+ B cells are ...predisposed to differentiate into short-lived PCs.2 Accordingly, allergen-specific IgE titers became undetectable between 3 and 6 months after sensitization in mice that were not re-exposed to the allergen.1 In patients with food allergy, whether allergen-specific IgE levels are maintained in the absence of allergen restimulation is exceedingly difficult to investigate because of the high rate of accidental and subclinical exposures.1 Evidence from helminth infections in which allergen (parasite) exposure and clearance can be ascertained is informative. ...subjects infected with Anisakis species, common contaminants of raw fish, show a continuous and substantial decrease in serum levels of allergen-specific IgE after parasite clearance.3 Together, these findings suggest that in the absence of repeated exposure to the IgE-eliciting antigen, allergen-specific IgE levels are not persistent in accordance with the limited survival of IgE+ PCs that has been demonstrated in mice.1 Although allergen-specific IgE levels in allergic mice are not sustained over time, the capacity to regenerate allergen-specific IgE and develop anaphylaxis is virtually lifelong. In mice orally sensitized to food allergens, a population of allergen-specific IgG1- but not IgE-expressing memory B cells was identified at least 9 months after sensitization.1 In a model of epicutaneous sensitization to foods, a population of immature allergen-specific IgG1+ memory B cells (PDL2−CD80−CD73+CD35+) predated IgE responses; on allergen re-exposure, a population of cells with more mature markers emerged (PDL2+CD73+CD80+).4 This mature phenotype of IgG1+ memory B cells was identified as a reservoir of high-affinity IgE in a model of Nippostrongylus brasiliensis infection.5 In a similar model IgE production was aborted when the extracellular domain of IgG1 was replaced with IgE sequences,6 thus establishing that high-affinity IgE originated from the IgG1+ memory compartment.5 In human subjects Scott Boyd's group sequenced almost 16 million immunoglobulin heavy regions from the peripheral blood of healthy and allergic subjects.
While type 2 immunity has been conventionally viewed as beneficial against helminths, venoms, and poisons, and harmful in allergy, contemporary research has uncovered its critical role in the ...maintenance of homeostasis. The initiation of a type 2 immune response involves an intricate crosstalk between structural and immune cells. Structural cells react to physical and chemical tissue perturbations by secreting alarmins, which signal the innate immune system to restore homeostasis. This pathway acts autonomously in the context of sterile injury and in the presence of foreign antigen initiates an adaptive Th2 response that is beneficial in the context of venoms, toxins, and helminths, but not food allergens. The investigation of the triggers and mechanisms underlying food allergic sensitization in humans is elusive because sensitization is a silent process. Therefore, the central construct driving food allergy modeling is based on introducing perturbations of tissue homeostasis along with an allergen which will result in an immunological and clinical phenotype that is consistent with that observed in humans. The collective evidence from multiple models has revealed the pre-eminent role of innate cells and molecules in the elicitation of allergic sensitization. We posit that, with the expanding use of technologies capable of producing formidable datasets, models of food allergy will continue to have an indispensable role to delineate mechanisms and establish causal relationships.
The upper respiratory tract is highly exposed to airborne pathogens and serves as an important inductive site for protective antibody responses, including mucosal IgA and systemic IgG. However, it is ...currently unknown to what extent inhaled environmental toxins, such as a cigarette smoke, affect the ability to induce antibody-mediated immunity at this site. Using a murine model of intranasal lipopolysaccharide and ovalbumin (LPS/OVA) immunization, we show that cigarette smoke exposure compromises the induction of antigen-specific IgA in the upper airways and systemic circulation. Deficits in OVA-IgA were observed in conjunction with a reduced accumulation of OVA-specific IgA antibody-secreting cells (ASCs) in the nasal mucosa, inductive tissues (NALT, cervical lymph nodes, spleen) and the blood. Nasal OVA-IgA from smoke-exposed mice also demonstrated reduced avidity during the acute post-immunization period in association with an enhanced mutational burden in the cognate nasal Igha repertoire. Mechanistically, smoke exposure attenuated the ability of the nasal mucosa to upregulate VCAM-1 and pIgR, suggesting that cigarette smoke may inhibit both nasal ASC homing and IgA transepithelial transport. Overall, these findings demonstrate the immunosuppressive nature of tobacco smoke and illustrate the diversity of mechanisms through which this noxious stimulus can interfere with IgA-mediated immunity in the upper airways.
Allergen-specific immunoglobulin E (IgE) antibodies mediate pathology in diseases such as allergic rhinitis and food allergy. Memory B cells (MBCs) contribute to circulating IgE by regenerating ...IgE-producing plasma cells upon allergen encounter. Here, we report a population of type 2-polarized MBCs defined as CD23
, IL-4Rα
, and CD32
at both the transcriptional and surface protein levels. These MBC2s are enriched in IgG1- and IgG4-expressing cells while constitutively expressing germline transcripts for IgE. Allergen-specific B cells from patients with allergic rhinitis and food allergy were enriched in MBC2s. Furthermore, MBC2s generated allergen-specific IgE during sublingual immunotherapy, thereby identifying these cells as a major reservoir for IgE. The identification of MBC2s provides insights into the maintenance of IgE memory, which is detrimental in allergic diseases but could be beneficial in protection against venoms and helminths.
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