Ablation of Adar1 in myeloid cells imprints a global antiviral state in the lung and heightens early immunity against SARS-CoV-2.
2023; 42 (1): 112038
Under normal homeostatic conditions, self-double-stranded RNA (self-dsRNA) is modified by adenosine deaminase acting on RNA 1 (ADAR1) to prevent the induction of a type I interferon-mediated inflammatory cascade. Antigen-presenting cells (APCs) sense pathogen-associated molecular patterns, such as dsRNA, to activate the immune response. The impact of ADAR1 on the function of APCs and the consequences to immunity are poorly understood. Here, we show that ADAR1 deletion in CD11c+ APCs leads to (1) a skewed myeloid cell compartment enriched in inflammatory cDC2-like cells, (2) enhanced numbers of activated tissue resident memory Tcells in the lung, and (3) the imprinting of a broad antiviral transcriptional signature across both immune and non-immune cells. The resulting changes can be partially reversed by blocking IFNAR1 signaling and promote early resistance against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Our study provides insight into the consequences of self-dsRNA sensing in APCs on the immune system.
View details for DOI 10.1016/j.celrep.2023.112038
View details for PubMedID 36732946
SREBP signaling is essential for effective B cell responses.
Our previous study using systems vaccinology identified an association between the sterol regulatory binding protein (SREBP) pathway and humoral immune response to vaccination in humans. To investigate the role of SREBP signaling in modulating immune responses, we generated mice with B cell- or CD11c+ antigen-presenting cell (APC)-specific deletion of SCAP, an essential regulator of SREBP signaling. Ablation of SCAP in CD11c+ APCs had no effect on immune responses. In contrast, SREBP signaling in B cells was critical for antibody responses, as well as the generation of germinal centers,memory B cells and bone marrow plasma cells. SREBP signaling was required for metabolic reprogramming in activated B cells. Upon mitogen stimulation, SCAP-deficient B cells could not proliferate and had decreased lipid rafts. Deletion of SCAP in germinal center B cells using AID-Cre decreased lipid raft content and cell cycle progression. These studies provide mechanistic insights coupling sterol metabolism with the quality and longevity of humoral immunity.
View details for DOI 10.1038/s41590-022-01376-y
View details for PubMedID 36577930
Mechanisms of innate and adaptive immunity to the Pfizer-BioNTech BNT162b2 vaccine.
Despite the success of the BNT162b2 mRNA vaccine, the immunological mechanisms that underlie its efficacy are poorly understood. Here we analyzed the innate and adaptive responses to BNT162b2 in mice, and show that immunization stimulated potent antibody and antigen-specific T cell responses, as well as strikingly enhanced innate responses after secondary immunization, which was concurrent with enhanced serum interferon (IFN)-gamma levels 1d following secondary immunization. Notably, we found that natural killer cells and CD8+ T cells in the draining lymph nodes are the major producers of this circulating IFN-gamma. Analysis of knockout mice revealed that induction of antibody and T cell responses to BNT162b2 was not dependent on signaling via Toll-like receptors 2, 3, 4, 5 and 7 nor inflammasome activation, nor the necroptosis or pyroptosis cell death pathways. Rather, the CD8+ T cell response induced by BNT162b2 was dependent on type I interferon-dependent MDA5 signaling. These results provide insights into the molecular mechanisms by which the BNT162b2 vaccine stimulates immune responses.
View details for DOI 10.1038/s41590-022-01163-9
View details for PubMedID 35288714
Hydrogel-Based Slow Release of a Receptor-Binding Domain Subunit Vaccine Elicits Neutralizing Antibody Responses Against SARS-CoV-2.
Advanced materials (Deerfield Beach, Fla.)
The development of effective vaccines that can be rapidly manufactured and distributed worldwide is necessary to mitigate the devastating health and economic impacts of pandemics like COVID-19. The receptor-binding domain (RBD) of the SARS-CoV-2 spike protein, which mediates host cell entry of the virus, is an appealing antigen for subunit vaccines because it is efficient to manufacture, highly stable, and a target for neutralizing antibodies. Unfortunately, RBD is poorly immunogenic. While most subunit vaccines are commonly formulated with adjuvants to enhance their immunogenicity, clinically-relevant adjuvants Alum, AddaVax, and CpG/Alum are found unable to elicit neutralizing responses following a prime-boost immunization. Here, it has been shown that sustained delivery of an RBD subunit vaccine comprisingCpG/Alumadjuvant in an injectable polymer-nanoparticle (PNP) hydrogelelicited potentanti-RBD andanti-spikeantibody titers, providing broader protection against SARS-CoV-2 variants of concern compared to bolus administration of the same vaccine and vaccines comprising other clinically-relevant adjuvant systems. Notably, a SARS-CoV-2 spike-pseudotyped lentivirus neutralization assay revealed that hydrogel-based vaccines elicited potent neutralizing responses when bolus vaccines didnot. Together, these results suggest that slow delivery of RBD subunit vaccines with PNP hydrogels can significantly enhance the immunogenicity of RBD and induce neutralizing humoral immunity.
View details for DOI 10.1002/adma.202104362
View details for PubMedID 34651342
Neutralizing Anti-Interleukin-1 Receptor-Antagonist Autoantibodies Induce Inflammatory and Fibrotic Mediators in IgG4-Related Disease.
The Journal of allergy and clinical immunology
BACKGROUND: IgG4-related disease (IgG4-RD) is a fibro-inflammatory condition involving loss of B cell tolerance and production of autoantibodies. However, the relevant targets and role of these aberrant humoral immune responses are not defined.OBJECTIVE: To identify novel autoantibodies and autoantigen targets that promote pathogenic responses in IgG4-RD.METHODS: We sequenced plasmablast antibody repertoires in patients with IgG4-RD. Representative monoclonal antibodies (mAb) were expressed and their specificities characterized using cytokine microarrays. The role of anti-interleukin-1 receptor-antagonist (IL-1RA) autoantibodies was investigated using in vitro assays.RESULTS: We identified strong reactivity against human IL-1RA using a clonally-expanded plasmablast-derived mAb from a patient with IgG4-RD. IgG4-RD patient plasma exhibited elevated levels of reactivity against IL-1RA compared to controls and neutralized IL-1RA activity, resulting in inflammatory and fibrotic mediator production in vitro. IL-1RA was detected in lesional tissues from IgG4-RD patients. Patients with anti-IL-1RA autoantibodies of the IgG4 subclass had greater numbers of organs affected than those without anti-IL-1RA autoantibodies. Peptide analyses identified IL-1RA epitopes targeted by anti-IL-1RA antibodies at sites near the IL-1RA/IL-1R interface. Serum from patients with systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA) also had elevated levels of anti-IL-1RA autoantibodies compared to controls.CONCLUSION: A subset of patients with IgG4-RD have anti-IL-1RA autoantibodies, which promote pro-inflammatory and pro-fibrotic meditator production via IL-1RA neutralization. These findings support a novel immunological mechanism underlying the pathogenesis of IgG4-RD. Anti-IL-1RA autoantibodies are also present in a subset of patients with SLE and RA, suggesting a potential common pathway in multiple autoimmune diseases.
View details for DOI 10.1016/j.jaci.2021.05.002
View details for PubMedID 33974929
Modeling human adaptive immune responses with tonsil organoids.
Most of what we know about adaptive immunity has come from inbred mouse studies, using methods that are often difficult or impossible to confirm in humans. In addition, vaccine responses in mice are often poorly predictive of responses to those same vaccines in humans. Here we use human tonsils, readily available lymphoid organs, to develop a functional organotypic system that recapitulates key germinal center features in vitro, including the production of antigen-specific antibodies, somatic hypermutation and affinity maturation, plasmablast differentiation and class-switch recombination. We use this system to define the essential cellular components necessary to produce an influenza vaccine response. We also show that it can be used to evaluate humoral immune responses to two priming antigens, rabies vaccine and an adenovirus-based severe acute respiratory syndrome coronavirus 2 vaccine, and to assess the effects of different adjuvants. This system should prove useful for studying critical mechanisms underlying adaptive immunity in much greater depth than previously possible and to rapidly test vaccine candidates and adjuvants in an entirely human system.
View details for DOI 10.1038/s41591-020-01145-0
View details for PubMedID 33432170
Distinct immune characteristics distinguish hereditary and idiopathic chronic pancreatitis.
The Journal of clinical investigation
Chronic pancreatitis (CP) is considered an irreversible fibroinflammatory pancreatic disease. Despite numerous animal model studies, questions remain about local immune characteristics in human CP. We profiled pancreatic immune cell characteristics in control organ donors and CP patients that included hereditary and idiopathic CP undergoing total pancreatectomy with islet auto-transplantation. Flow cytometric analysis revealed a significant increase in the frequency of CD68+ macrophages in idiopathic CP. In contrast, hereditary CP showed a significant increase in CD3+ T cell frequency, which prompted us to investigate the T cell receptor beta (TCRbeta) repertoire in CP and controls. TCRbeta-sequencing revealed a significant increase in TCRbeta repertoire diversity and reduced clonality in both CP groups versus controls. Interestingly, we observed differences in Vbeta-Jbeta gene family usage between hereditary and idiopathic CP and a positive correlation of TCRbeta rearrangements with disease severity scores. Immunophenotyping analyses in hereditary and idiopathic CP pancreata indicate differences in innate and adaptive immune responses, which highlights differences in immunopathogenic mechanism of disease among subtypes of CP. TCR repertoire analysis further suggests a role for specific T cell responses in hereditary versus idiopathic CP pathogenesis providing new insights into immune responses associated with human CP.
View details for DOI 10.1172/JCI134066
View details for PubMedID 32053120
B cells in rheumatoid arthritis synovial tissues encode focused antibody repertoires that include antibodies that stimulate macrophage TNF-α production.
Clinical immunology (Orlando, Fla.)
Rheumatoid arthritis (RA) is characterized by the production of anti-citrullinated protein antibodies (ACPAs). To gain insights into the relationship between ACPA-expressing B cells in peripheral blood (PB) and synovial tissue (ST), we sequenced the B cell repertoire in paired PB and ST samples from five individuals with established, ACPA+ RA. Bioinformatics analysis of paired heavy and light chain sequences revealed clonally-related family members shared between PB and ST. ST-derived antibody repertoires exhibited reduced diversity and increased normalized clonal family size compared to PB-derived repertoires. Functional characterization showed that seven recombinant antibodies (rAbs) expressed from subject-derived sequences from both compartments bound citrullinated antigens and immune complexes (ICs) formed using one ST-derived rAb stimulated macrophage TNF-α production. Our findings demonstrate B cell trafficking between PB and ST in subjects with RA and ST repertoires include B cells that encode ACPA capable of forming ICs that stimulate cellular responses implicated in RA pathogenesis.
View details for DOI 10.1016/j.clim.2020.108360
View details for PubMedID 32035179
Robust B Cell Responses Predict Rapid Resolution of Lyme Disease.
Frontiers in immunology
2018; 9: 1634
Lyme disease (Borrelia burgdorferi infection) is increasingly recognized as a significant source of morbidity worldwide. Here, we show that blood plasmablasts and CD27- memory B cells are elevated in untreated Lyme disease, with higher plasmablast levels associated with more rapid resolution of clinical symptoms. Stronger serum reactivity to surface proteins and peptides from B. burgdorferi was also associated with faster resolution of clinical symptoms. Through molecular identifier-enabled antibody heavy-chain sequencing of bulk B cells and single-cell paired-chain antibody sequencing of blood plasmablasts, we characterized immunoglobulin gene usage patterns specific to B. burgdorferi infection. Recombinantly expressed antibodies from expanded lineages bound B. burgdorferi antigens, confirming that these clones are driven by the infection. Furthermore, recombinant sequence-derived antibodies were functional, inhibiting growth of B. burgdorferi in vitro. Elevations and clonal expansion of blood plasmablasts were associated with rapid return to health, while poor plasmablast responses were associated with a longer duration of symptoms following treatment. Plasmablasts induced by B. burgdorferi infection showed preferential antibody gene segment usage, while bulk sequencing of total B cells revealed convergent CDR3 motifs specific to B. burgdorferi-infected patients. Our results show that robust plasmablast responses encoding Bb-static antibodies are associated with more rapid resolution of Lyme disease, and these antibodies could provide the basis for next-generation therapeutics for Lyme disease.
View details for DOI 10.3389/fimmu.2018.01634
View details for PubMedID 30072990
View details for PubMedCentralID PMC6060717
Affinity Maturation Drives Epitope Spreading and Generation of Pro-inflammatory Anti-Citrullinated Protein Antibodies in Rheumatoid Arthritis.
Arthritis & rheumatology (Hoboken, N.J.)
OBJECTIVE: Rheumatoid arthritis (RA) is characterized by anti-citrullinated protein antibodies (ACPAs), nevertheless, the origin, specificity, and functional properties of ACPAs remain poorly understood. To characterize the evolution of ACPAs, we sequenced the plasmablast antibody repertoire at serial timepoints in subjects with established RA.METHODS: Blood samples were obtained at up to four timepoints from eight anti-CCP+ individuals with established RA. We single-cell sorted CD19+CD3-IgD-CD14-CD20-CD27+CD38++ plasmablasts and co-stained with citrullinated-peptide tetramers to identify ACPA-expressing plasmablasts. Cell-specific oligonucleotide barcodes were utilized followed by large-scale sequencing and bioinformatic analysis to obtain error-corrected, paired, heavy and light chain antibody gene sequences for each B cell.RESULTS: Bioinformatic analysis revealed 170 persistent plasmablast lineages of which 19% included multiple isotypes. Among IgG- and IgA-expressing plasmablasts, we observed significantly more IgA-expressing persistent lineages compared to IgG (P < 0.01). We identified shared CDR3 sequence motifs across subjects. A subset of lineages comprised of later-timepoint derived members with divergent somatic hypermutations encoded antibodies that bind an expanded set of citrullinated antigens. Further, these recombinant, differentially mutated plasmablast antibodies formed immune complexes that stimulated higher levels of macrophage TNF-alpha production compared to antibodies representing earlier-timepoint, less-mutated lineage members.CONCLUSIONS: Our findings demonstrate that established RA is characterized by a persistent IgA ACPA response that exhibits ongoing affinity maturation. This observation suggests the presence of a persistent mucosal antigen that continually promotes the production of IgA plasmablasts, and their affinity maturation and epitope spreading to generate ACPAs that bind additional citrullinated antigens and more potently stimulate macrophage TNF-alpha production. This article is protected by copyright. All rights reserved.
View details for PubMedID 29927104