Immunological Reviews最新文献

Influenza viruses are a constant threat to human health. Current vaccines often confer low to moderate protection against infection with seasonal viruses and little-to-no protection against pandemic viruses. Improved vaccines are needed. These vaccines will need to reliably elicit antibodies to conserved sites that are broadly protective. One strategy to do so is to design immunogens that present epitopes that are targeted by antibodies that are genetically similar, that humans have the genetic capacity to produce, and that are likely present in human naive B cell repertoires. Among the more recently described epitopes for broadly binding, protective antibodies are those on surfaces at protein–protein interfaces. This review will focus on describing many of these sites and the genetic features of antibodies that engage them. Interface epitopes are immunogenic, and antibodies to these sites are likely present in human repertoires following influenza infection or vaccination.

Memory B cells are essential for long-lasting immunity induced by both encountered pathogens and vaccines. Functional diversity within the memory B cell pool is established through interactions between memory B cells and the environment in which they develop and reside. This review will discuss novel insights into the role of cytokines encountered in the microenvironment in modulating memory B cell transcriptomic, epigenetic, and phenotypic identity. Specifically, it will focus on how interferons can prime unique memory B cell subpopulations upregulated in chronic viral infection, autoimmunity, and cancer. Understanding how memory B cell identity is established and maintained in interferon-primed memory B cell subsets, and how memory B cell phenotype relates to function, may help advise novel vaccine design and diagnostic procedures for a wide range of immunopathologies.

Shape space is a decades-old conceptual model of antibody–antigen interactions that underlies antigenic maps used to trace viral evolution. Here, we apply this concept to T cell receptors (TCRs) and the peptide–MHC complexes (pMHCs) that they recognize. We start by reviewing the history of shape space and its deep connections to concepts in statistical physics (energy landscapes) and computer science (complexity theory). Leveraging these connections, we propose a model in which TCR-pMHC binding relies on multiple, possibly conflicting, structural constraints—implying that pMHCs recognized by the same TCR occupy several disjoint, non-convex regions in shape space. Our model makes two central predictions: (1) even small pMHC structure alterations can have major effects on immunogenicity; (2) two pMHCs recognized by the same TCR can have very different structures. We show that published TCR-pMHC interaction data generated by mutagenesis assays lend some support for this idea. We conclude by discussing implications of a multispecific and non-convex T cell epitope shape space for the prediction of immune responses in cancer immunotherapy and other applications.

Age-associated B cells (ABCs) are a distinct B cell population characterized by coexpression of T-bet and CD11c. First described in aged female mice and autoimmune-prone strains, ABCs are now recognized to be associated with multiple human autoimmune diseases, including systemic lupus erythematosus, rheumatoid arthritis, and multiple sclerosis, where their frequency correlates with disease activity. Their differentiation requires toll-like receptor (TLR) signaling, IFN-γ, IL-21, BCR engagement, with ZEB2 emerging as the nonredundant transcriptional master regulator of ABC identity. Here we review requirements for ABC differentiation, their defining phenotypic and functional features, and their tissue-specific distribution and pathogenic contributions in diverse inflammatory settings. A central theme is that ABCs are tissue-homing cells whose contribution extends beyond blood and lymphoid organs. In kidney, inflamed synovium, salivary glands, and adipose tissue, ABCs drive pathology through locally differentiated autoantibody-secreting cells, stromal activation, antigen presentation, and cytokine production. We further discuss roles for ABCs in neurological diseases, including their enrichment in the cerebrospinal fluid in multiple sclerosis (MS) and their contribution to neuroinflammation in Alzheimer's disease, and highlight the EBV–ABC axis as a mechanism linking viral infection to autoimmunity. In summary, ABCs are multi-functional, tissue-adaptable pathogenic effectors whose contributions to human disease extend beyond classical autoimmunity into metabolic dysfunction and neurodegeneration.

Citrullination and deamidation are post-translational modifications (PTMs) increasingly recognized as important contributors to neoepitope formation in type 1 diabetes (T1D). Under inflammatory and endoplasmic reticulum stress conditions, beta cells activate calcium-dependent peptidylarginine deiminase and transglutaminase enzymes, leading to self-protein modification, altered peptide charge and HLA-binding properties, thereby generating neoepitopes that can be recognized by autoreactive CD4⁺ and CD8⁺ T cells. Accumulating evidence from both murine and human studies demonstrates that immune responses against citrullinated and deamidated beta cell proteins are present and increase with disease progression, supporting a role in epitope spreading rather than disease initiation. Although both PTMs are biochemically analogous, their kinetics and regulation are distinct: citrullination appears as an earlier and partly intrinsic response of stressed beta cells, whereas deamidation is more closely associated with sustained inflammation and later disease stages. In parallel, reduced PTM-generating enzyme expression in the thymus may limit central tolerance to modified epitopes, facilitating escape of autoreactive T cells. In this review, we summarize current insights into the biochemical and immunological roles of citrullination and deamidation in T1D, with emphasis on their temporal regulation, contribution to neoepitope formation, and potential as therapeutic targets, highlighting key findings from our own work in the field.

Post-translational modifications (PTMs) can generate neo-epitopes, modified peptides that evade immune tolerance and trigger immune responses. This review focuses on the TG2/LRP1 pathway as a new paradigm for coupling the formation of post-translationally modified peptides with their effective presentation as T-cell antigens by dendritic cells. Transglutaminase 2 (TG2) catalyzes the Gln → Glu conversion of specific residues in peptides derived from dietary gluten thereby enhancing their affinity for HLA-DQ2, the principal genetic determinant of celiac disease. However, because such modified peptides are scarce in intestinal mucosa, an effective mechanism for lysosomal uptake by antigen-presenting cells (APCs) is necessary. Protein–protein interaction between certain peptide-bound TG2 complexes and the low-density lipoprotein receptor-related protein 1 (LRP1) results in efficient endocytosis of these antigenic peptides along with their concomitant release in the endo-lysosomal compartment as deamidated products. An analogous PTM-driven mechanism for antigen presentation may also operate in autoimmune conditions associated with peptidylarginine deiminase (PADI) activity, such as rheumatoid arthritis (RA). The exquisite cellular selectivity of the TG2/LRP1 pathway has implications not only for understanding its role in autoimmunity but also for its potential exploitation in vaccine design.

In vertebrate adaptive immune systems, somatically diversified antigen receptors assume a central role in self/nonself discrimination. Attesting to the presence of a unique but unknown selective environment at early stages of vertebrate evolution, this facility emerged twice, in the ancestors of jawless and jawed vertebrates. Thus, the molecular structure of incomplete antigen receptor genes and their mode of assembly into functional genes are different in the two sister groups of vertebrates. It appears that adaptive immunity evolved in steps, trading immunologically favorable diversity of antigen receptor repertoires against the inherent risks of potentially destructive self recognition. Initially, the associated quality control mechanisms were largely cell-autonomous and grounded in the evolutionarily selected sequence composition of individual components available for assembly. At later stages, diversity increased in lock-step with emerging cell-nonautonomous quality control strategies: primary lymphoid organs spatially and temporally coupled repertoire development and assessment for self reactivity; regulatory cell types emerged to keep self reactive clones in check in the periphery. In this review, we discuss how comparative studies of vertebrate species situated at key positions in the phylogenetic tree have revealed traces of the evolutionary past of adaptive immune systems.