Multifunctional Lipidated Protein Carrier with a Built-In Adjuvant as a Universal Vaccine Platform Potently Elevates Immunogenicity of Weak Antigens.

Weak antigens represented by MUC1 are poorly immunogenic, which greatly constrains the development of relevant vaccines. Herein, we developed a multifunctional lipidated protein as a carrier, in which the TLR1/2 agonist Pam3CSK4 was conjugated to the N-terminus of MUC1-loaded carrier protein BSA through pyridoxal 5'-phosphate-mediated transamination reaction. The resulting Pam3CSK4-BSA-MUC1 conjugate was subsequently incorporated into liposomes, which biomimics the membrane structure of tumor cells. The results indicated that this lipidated protein carrier significantly enhanced antigen uptake by APCs and obviously augmented the retention of the vaccine at the injection site. Compared with the BSA-MUC1 and BSA-MUC1 + Pam3CSK4 groups, Pam3CSK4-BSA-MUC1 evoked 22- and 11-fold increases in MUC1-specific IgG titers. Importantly, Pam3CSK4-BSA-MUC1 elicited robust cellular immunity and significantly inhibited tumor growth. This is the first time that lipidated protein was constructed to enhance antigen immunogenicity, and this universal carrier platform exhibits promise for utilization in various vaccines, holding the potential for further clinical application.

Planting a chemical flag on antigens.

Next-generation live vaccines are created by autonomous production of nitrated antigens.

Venous-plexus-associated lymphoid hubs support meningeal humoral immunity.

There is increasing interest in how immune cells in the meninges-the membranes that surround the brain and spinal cord-contribute to homeostasis and disease in the central nervous system1,2. The outer layer of the meninges, the dura mater, has recently been described to contain both innate and adaptive immune cells, and functions as a site for B cell development3-6. Here we identify organized lymphoid structures that protect fenestrated vasculature in the dura mater. The most elaborate of these dural-associated lymphoid tissues (DALT) surrounded the rostral-rhinal confluence of the sinuses and included lymphatic vessels. We termed this structure, which interfaces with the skull bone marrow and a comparable venous plexus at the skull base, the rostral-rhinal venolymphatic hub. Immune aggregates were present in DALT during homeostasis and expanded with age or after challenge with systemic or nasal antigens. DALT contain germinal centre B cells and support the generation of somatically mutated, antibody-producing cells in response to a nasal pathogen challenge. Inhibition of lymphocyte entry into the rostral-rhinal hub at the time of nasal viral challenge abrogated the generation of germinal centre B cells and class-switched plasma cells, as did perturbation of B-T cell interactions. These data demonstrate a lymphoid structure around vasculature in the dura mater that can sample antigens and rapidly support humoral immune responses after local pathogen challenge.

Autoimmune amelogenesis imperfecta in patients with APS-1 and coeliac disease.

Ameloblasts are specialized epithelial cells in the jaw that have an indispensable role in tooth enamel formation-amelogenesis1. Amelogenesis depends on multiple ameloblast-derived proteins that function as a scaffold for hydroxyapatite crystals. The loss of function of ameloblast-derived proteins results in a group of rare congenital disorders called amelogenesis imperfecta2. Defects in enamel formation are also found in patients with autoimmune polyglandular syndrome type-1 (APS-1), caused by AIRE deficiency3,4, and in patients diagnosed with coeliac disease5-7. However, the underlying mechanisms remain unclear. Here we show that the vast majority of patients with APS-1 and coeliac disease develop autoantibodies (mostly of the IgA isotype) against ameloblast-specific proteins, the expression of which is induced by AIRE in the thymus. This in turn results in a breakdown of central tolerance, and subsequent generation of corresponding autoantibodies that interfere with enamel formation. However, in coeliac disease, the generation of such autoantibodies seems to be driven by a breakdown of peripheral tolerance to intestinal antigens that are also expressed in enamel tissue. Both conditions are examples of a previously unidentified type of IgA-dependent autoimmune disorder that we collectively name autoimmune amelogenesis imperfecta.

How mothers tolerate their children.

Shifting pools of antigen can influence pregnancy-induced immune tolerance.

Reproductive outcomes after pregnancy-induced displacement of preexisting microchimeric cells.

Pregnancy confers partner-specific protection against complications in future pregnancy that parallel persistence of fetal microchimeric cells (FMcs) in mothers after parturition. We show that preexisting FMcs become displaced by new FMcs during pregnancy and that FMc tonic stimulation is essential for expansion of protective fetal-specific forkhead box P3 (FOXP3)-positive regulatory T cells (Treg cells). Maternal microchimeric cells and accumulation of Treg cells with noninherited maternal antigen (NIMA) specificity are similarly overturned in daughters after pregnancy, highlighting a fixed microchimeric cell niche. Whereas NIMA-specific tolerance is functionally erased by pregnancy, partner-specific resiliency against pregnancy complications persists in mothers despite paternity changes in intervening pregnancy. Persistent fetal tolerance reflects FOXP3 expression plasticity, which allows mothers to more durably remember their babies, whereas daughters forget their mothers with new pregnancy-imprinted immunological memories.

The ß1-adrenergic receptor links sympathetic nerves to T cell exhaustion.

CD8+ T cells are essential components of the immune response against viral infections and tumours, and are capable of eliminating infected and cancerous cells. However, when the antigen cannot be cleared, T cells enter a state known as exhaustion1. Although it is clear that chronic antigen contributes to CD8+ T cell exhaustion, less is known about how stress responses in tissues regulate T cell function. Here we show a new link between the stress-associated catecholamines and the progression of T cell exhaustion through the ß1-adrenergic receptor ADRB1. We identify that exhausted CD8+ T cells increase ADRB1 expression and that exposure of ADRB1+ T cells to catecholamines suppresses their cytokine production and proliferation. Exhausted CD8+ T cells cluster around sympathetic nerves in an ADRB1-dependent manner. Ablation of ß1-adrenergic signalling limits the progression of T cells towards the exhausted state in chronic infection and improves effector functions when combined with immune checkpoint blockade (ICB) in melanoma. In a pancreatic cancer model resistant to ICB, ß-blockers and ICB synergize to boost CD8+ T cell responses and induce the development of tissue-resident memory-like T cells. Malignant disease is associated with increased catecholamine levels in patients2,3, and our results establish a connection between the sympathetic stress response, tissue innervation and T cell exhaustion. Here, we uncover a new mechanism by which blocking ß-adrenergic signalling in CD8+ T cells rejuvenates anti-tumour functions.

Exogenous Antigen Upregulation Empowers Antibody Targeted Nanochemotherapy of Leukemia.

Acute myeloid leukemia (AML) is afflicted by a high-mortality rate and few treatment options. The lack of specific surface antigens severely hampers the development of targeted therapeutics and cell therapy. Here, it is shown that exogenous all-trans retinoic acid (ATRA) mediates selective and transient CD38 upregulation on leukemia cells by up to 20-fold, which enables high-efficiency targeted nanochemotherapy of leukemia with daratumumab antibody-directed polymersomal vincristine sulfate (DPV). Strikingly, treatment of two CD38-low expressing AML orthotopic models with ATRA and DPV portfolio strategies effectively eliminates circulating leukemia cells and leukemia invasion into bone marrow and organs, leading to exceptional survival benefits with 20-40% of mice becoming leukemia-free. The combination of exogenous CD38 upregulation and antibody-directed nanotherapeutics provides a unique and powerful targeted therapy for leukemia.

A Proximity-Induced Fluorogenic Reaction Triggered by Antibody-Antigen Interactions with Adjacent Epitopes.

Proximity-induced chemical reactions are site-specific and rapid by taking advantage of their high affinity and highly selective interactions with the template. However, reactions induced solely by antibody-antigen interactions have not been developed. Herein, we propose a biepitopic antigen-templated chemical reaction (BATER) as a novel template reaction. In BATER, reactive functional groups are conjugated to two antibodies that interact with two epitopes of the same antigen to accelerate the reaction. We developed a method for visualizing the progress of BATER using fluorogenic click chemistry for optimal antibody selection and linker design. The reaction is accelerated in the presence of a specific antigen in a linker length-dependent manner. The choice of the antibody epitope is important for a rapid reaction. This design will lead to various applications of BATER in living systems.

PD-1 maintains CD8 T cell tolerance towards cutaneous neoantigens.

The peripheral T cell repertoire of healthy individuals contains self-reactive T cells1,2. Checkpoint receptors such as PD-1 are thought to enable the induction of peripheral tolerance by deletion or anergy of self-reactive CD8 T cells3-10. However, this model is challenged by the high frequency of immune-related adverse events in patients with cancer who have been treated with checkpoint inhibitors11. Here we developed a mouse model in which skin-specific expression of T cell antigens in the epidermis caused local infiltration of antigen-specific CD8 T cells with an effector gene-expression profile. In this setting, PD-1 enabled the maintenance of skin tolerance by preventing tissue-infiltrating antigen-specific effector CD8 T cells from (1) acquiring a fully functional, pathogenic differentiation state, (2) secreting significant amounts of effector molecules, and (3) gaining access to epidermal antigen-expressing cells. In the absence of PD-1, epidermal antigen-expressing cells were eliminated by antigen-specific CD8 T cells, resulting in local pathology. Transcriptomic analysis of skin biopsies from two patients with cutaneous lichenoid immune-related adverse events showed the presence of clonally expanded effector CD8 T cells in both lesional and non-lesional skin. Thus, our data support a model of peripheral T cell tolerance in which PD-1 allows antigen-specific effector CD8 T cells to co-exist with antigen-expressing cells in tissues without immunopathology.

Perforin-2 is a pore-forming effector of endocytic escape in cross-presenting dendritic cells.

During initiation of antiviral and antitumor T cell-mediated immune responses, dendritic cells (DCs) cross-present exogenous antigens on major histocompatibility complex (MHC) class I molecules. Cross-presentation relies on the unusual "leakiness" of endocytic compartments in DCs, whereby internalized proteins escape into the cytosol for proteasome-mediated generation of MHC I-binding peptides. Given that type 1 conventional DCs excel at cross-presentation, we searched for cell type-specific effectors of endocytic escape. We devised an assay suitable for genetic screening and identified a pore-forming protein, perforin-2 (Mpeg1), as a dedicated effector exclusive to cross-presenting cells. Perforin-2 was recruited to antigen-containing compartments, where it underwent maturation, releasing its pore-forming domain. Mpeg1-/- mice failed to efficiently prime CD8+ T cells to cell-associated antigens, revealing an important role for perforin-2 in cytosolic entry of antigens during cross-presentation.

Channeling antigens to CD8+ T cells.

Perforin-2 facilitates antigen translocation to the cytosol in cross-presenting dendritic cells.

Oral vaccination as a potential strategy to manage chronic wasting disease in wild cervid populations.

Prion diseases are a novel class of infectious disease based in the misfolding of the cellular prion protein (PrPC) into a pathological, self-propagating isoform (PrPSc). These fatal, untreatable neurodegenerative disorders affect a variety of species causing scrapie in sheep and goats, bovine spongiform encephalopathy (BSE) in cattle, chronic wasting disease (CWD) in cervids, and Creutzfeldt-Jacob disease (CJD) in humans. Of the animal prion diseases, CWD is currently regarded as the most significant threat due its ongoing geographical spread, environmental persistence, uptake into plants, unpredictable evolution, and emerging evidence of zoonotic potential. The extensive efforts to manage CWD have been largely ineffective, highlighting the need for new disease management tools, including vaccines. Development of an effective CWD vaccine is challenged by the unique biology of these diseases, including the necessity, and associated dangers, of overcoming immune tolerance, as well the logistical challenges of vaccinating wild animals. Despite these obstacles, there has been encouraging progress towards the identification of safe, protective antigens as well as effective strategies of formulation and delivery that would enable oral delivery to wild cervids. In this review we highlight recent strategies for antigen selection and optimization, as well as considerations of various platforms for oral delivery, that will enable researchers to accelerate the rate at which candidate CWD vaccines are developed and evaluated.

[The reasons for the formation of tolerance to food antigens].

One of the main issues of the peculiarities of the immune reactions of the gastrointestinal tract is the mechanisms of ensuring tolerance to food antigens. Concentrations of antibodies to food antigens actually reflect the state of the intestinal mucosa barrier function, and the degree of penetration of antigens into the blood determines the level of immune response to them. The aim of the study was to determine the risk criteria for violation of tolerance to food antigens. Material and methods. The study included the results of a survey and examination of 1334 adults living in the north of the European part of the Russian Federation, including 1100 born in the North, of which 970 were women and 364 were men. The average age of the respondents was 45.5±1.0 years. The comparison group consisted of 344 patients with pathology of the gastrointestinal tract who applied to the medical company "Biocor". The content of immunoglobulins (Ig) G to food antigens, total IgA, cytokines (tumor necrosis factor α, interleukin-6, interleukin-4) in blood serum were determined by enzyme immunoassay. Results. Rural residents often (more than 28%) have elevated concentrations of IgG to potato, river fish, wheat and rye antigens. Urban residents have the most pronounced decrease in tolerance to food antigens of chicken, cod, beef and pork. In healthy individuals, elevated (>100 ME/ml) concentrations of antibodies to meat products are recorded in the range of 11.3-13.9%, to dairy antigens - 11.5-14.1%, cereals - 11.9-13.4%. Slightly less frequently, elevated concentrations of antibodies to fish antigens (7.5-10.1%), vegetables (3.8-7.0%) and fruits (4.9-6.5%) are detected. In inflammatory and oncological diseases of the gastrointestinal tract, the content of antibodies to food antigens increases sharply. On average, the frequency of impaired tolerance to food antigens in patients is 2.7-6.1 times higher than in healthy individuals. Conclusion. Violation of tolerance to food antigens is associated with an increase in blood pro-inflammatory cytokines, mainly interleukin-6. In practically healthy individuals, a decrease in tolerance to food antigens is associated with a deficiency of blood IgA. The risk criteria for violation of the diet or consumption of low-quality foods may be an increase in the frequency of detection of elevated concentrations of antibodies to meat products in 14.6±3.0%, fish - 10.7±2.3%, cereals - 13.7±1.6%, dairy products - 14.8±1.5%, vegetables - 7.8±2.4% and fruits - 6.9±5.8%.

Nanovaccine Based on a Biepitope Antigen to Potentiate the Immunogenicity of a Neoantigen.

Specific neoantigens are promising candidates for personalized cancer vaccines and immunotherapies, whereas the low immunogenicity and physicochemical variability are the main challenges in clinical trials. Herein, based on the rational design of neoantigens, we developed biepitope nanovaccines via integrating CD4+ with CD8+ T cell epitopes. A class of amphiphilic peptides composed of biepitope and hydrophilic amino acids can form well-defined nanostructures, thus incorporating functional sequences into an artificial platform. Cellular uptake studies demonstrated the enhanced endocytosis of biepitope neoantigens in dendritic cells (DCs). Such designed biepitopes can further stimulate the maturation of DCs, as validated by the upregulation of costimulatory molecules and secreted proinflammatory cytokines, which show the potential ability to prime T cells and evoke specific cellular immunity. The inspiring prophylactic and therapeutic efficacy of biepitope nanovaccines was evaluated in murine colon cancer. In contrast to individual CD8+ T cell epitopes, the rationally designed biepitope nanovaccines can efficiently provoke immune activation and potentiate antitumor immunity both in vitro and in vivo, presenting an alternative strategy for neoantigen vaccines.

Decoding foreign antigen tolerance.

Cell atlases of human tolerogenic milieus guide transformative immunotherapies.

Field-effect transistor antigen/antibody-TMDs sensors for the detection of COVID-19 samples.

We fabricated sensors by modifying the surface of MoS2 and WS2 with COVID-19 antibodies and investigated their characteristics, including stability, reusability, sensitivity, and selectivity. Thiols and disulfanes in antibodies strongly interact with vacant Mo or W sites of MoS2 or WS2, yielding durable devices that are stable for several days in the air or water. More importantly, detachment of the antibodies is suppressed even during the aggressive cleaning process of the devices at pH 3, which allows reusing the same device in several experiments without appreciable loss of sensitivity. Therefore, the nanodevice may be employed in samples of different patients. Further, we found a limit of detection (LOD) of 1 fg ml-1 at room temperature, time responses of 1 second, and selectivity against interferences such as KLH protein or Albumin.

An innovative immunotherapeutic strategy for rheumatoid arthritis: Selectively suppressing angiogenesis and osteoclast differentiation by fully human antibody targeting thymocyte antigen-1.

Thymocyte antigen-1 (THY-1)is a potential target for rheumatoid arthritis (RA) treatment, and THY-1 positive fibroblast-like synoviocytes (FLS) are enriched in the synovium of RA patients and participate in angiogenesis to accelerate RA progression. In this study, we screened an antibody targeting THY-1 (THY-1 Ab) and explored its mechanism in alleviating RA progression. THY-1 Ab was screened from ScFv phage antibody library by phage display technology (PDT). THY-1 Ab-treated collagen induced arthritis (CIA) mice had lower degree of arthritis scores. We explore the mechanism of THY-1 Ab in alleviating RA progression. THY-1 Ab can remarkably inhibit the secretion of pro-inflammatory factors and promote the secretion of anti-inflammatory factors. Further experiments showed that THY1 Ab downregulated the expression of JUNB by the hsa_circ_0094342/miRNA-155-5P/SPI1 axis, inhibited RA angiogenesis and osteoclast differentiation, and relieved RA progression. These findings support that THY-1 Ab is a promising therapeutic antibody for RA treatment.

Low protease activity in B cell follicles promotes retention of intact antigens after immunization.

The structural integrity of vaccine antigens is critical to the generation of protective antibody responses, but the impact of protease activity on vaccination in vivo is poorly understood. We characterized protease activity in lymph nodes and found that antigens were rapidly degraded in the subcapsular sinus, paracortex, and interfollicular regions, whereas low protease activity and antigen degradation rates were detected in the vicinity of follicular dendritic cells (FDCs). Correlated with these findings, immunization regimens designed to target antigen to FDCs led to germinal centers dominantly targeting intact antigen, whereas traditional immunizations led to much weaker responses that equally targeted the intact immunogen and antigen breakdown products. Thus, spatially compartmentalized antigen proteolysis affects humoral immunity and can be exploited.

Functional antibodies exhibit light chain coherence.

The vertebrate adaptive immune system modifies the genome of individual B cells to encode antibodies that bind particular antigens1. In most mammals, antibodies are composed of heavy and light chains that are generated sequentially by recombination of V, D (for heavy chains), J and C gene segments. Each chain contains three complementarity-determining regions (CDR1-CDR3), which contribute to antigen specificity. Certain heavy and light chains are preferred for particular antigens2-22. Here we consider pairs of B cells that share the same heavy chain V gene and CDRH3 amino acid sequence and were isolated from different donors, also known as public clonotypes23,24. We show that for naive antibodies (those not yet adapted to antigens), the probability that they use the same light chain V gene is around 10%, whereas for memory (functional) antibodies, it is around 80%, even if only one cell per clonotype is used. This property of functional antibodies is a phenomenon that we call light chain coherence. We also observe this phenomenon when similar heavy chains recur within a donor. Thus, although naive antibodies seem to recur by chance, the recurrence of functional antibodies reveals surprising constraint and determinism in the processes of V(D)J recombination and immune selection. For most functional antibodies, the heavy chain determines the light chain.