Rationale: Recurrent wheezing in children represents a severe public health concern. Wheezing attacks (WA), mainly associated with viral infections, lack effective preventive therapies. Objectives: To evaluate the efficacy and safety of mucosal sublingual immunotherapy based on whole inactivated bacteria (MV130) in preventing WA in children. Methods: A Phase 3 randomized, double-blind, placebo-controlled, parallel-group trial including a cohort of 120 children <3 years old with ⩾3 WA during the previous year was conducted. Children with a positive skin test to common aeroallergens in the area where the clinical trial was performed were excluded from the trial. Subjects received MV130 or placebo daily for 6 months. The primary endpoint was the number of WA within 1 year after the first dose comparing MV130 and placebo. Measurements and Main Results: There was a significant lower number of WA in MV130 versus the placebo group, 3.0 (interquartile range [IQR], 2.0–4.0) versus 5.0 (IQR, 3.0–7.0) (P < 0.001). As secondary outcomes, a decrease in the duration of WA and a reduction in symptoms and medication scores in the MV130 versus placebo group were found. No adverse events were reported related to the active treatment. Conclusions: Mucosal bacterial immunotherapy with MV130 shows safety and clinical efficacy against recurrent WA in children.Clinical trial registered with www.clinicaltrials.gov (NCT 01734811).

Background: Polymerized allergoids coupled to nonoxidized mannan (PM‐allergoids) may represent novel vaccines targeting dendritic cells (DCs). PM‐allergoids are better captured by DCs than native allergens and favor Th1/Treg cell responses upon subcutaneous injection. Herein we have studied in mice the in vivo immunogenicity of PM‐allergoids administered sublingually in comparison with native allergens.Methods: Three immunization protocols (4‐8 weeks long) were used in Balb/c mice. Serum antibody levels were tested by ELISA. Cell responses (proliferation, cytokines, and Tregs) were assayed by flow cytometry in spleen and lymph nodes (LNs). Allergen uptake was measured by flow cytometry in myeloid sublingual cells.Results: A quick antibody response and higher IgG2a/IgE ratio were observed with PM‐allergoids. Moreover, stronger specific proliferative responses were seen in both submandibular LNs and spleen cells assayed in vitro. This was accompanied by a higher IFNγ/IL‐4 ratio with a quick IL‐10 production by submandibular LN cells. An increase in CD4⁺CD25^highFOXP3⁺ Treg cells was detected in LNs and spleen of mice treated with PM‐allergoids. These allergoids were better captured than native allergens by antigen‐presenting (CD45⁺MHC‐II⁺) cells obtained from the sublingual mucosa, including DCs (CD11b⁺) and macrophages (CD64⁺). Importantly, all the differential effects induced by PM‐allergoids were abolished when using oxidized instead of nonoxidized PM‐allergoids.Conclusion: Our results demonstrate for the first time that PM‐allergoids administered through the sublingual route promote the generation of Th1 and FOXP3⁺ Treg cells in a greater extent than native allergens by mechanisms that might well involve their better uptake by oral antigen‐presenting cells.

Immunotherapy for treating IgE-mediated allergies requires high doses of the corresponding allergen. This may result in undesired side effects and, to avoid them, hypoallergenic allergens (allergoids) polymerized with glutaraldehyde are commonly used. Targeting allergoids to dendritic cells to enhance cell uptake may result in a more effective immunotherapy. Allergoids coupled to yeast mannan, as source of polymannoses, would be suitable for this purpose, since mannose-binding receptors are expressed on these cells. Conventional conjugation procedures of mannan to proteins use oxidized mannan to release reactive aldehydes able to bind to free amino groups in the protein; yet, allergoids lack these latter because their previous treatment with glutaraldehyde. The aim of this study was to obtain allergoids conjugated to mannan by an alternative approach based on just glutaraldehyde treatment, taking advantage of the mannoprotein bound to the polymannose backbone. Allergoid-mannan glycoconjugates were produced in a single step by treating with glutaraldehyde a defined mixture of allergens derived from Phleum pratense grass pollen and native mannan (non-oxidized) from Saccharomyces cerevisae. Analytical and structural studies, including 2D-DOSY and ¹H-¹³C HSQC nuclear magnetic resonance spectra, demonstrated the feasibility of such an approach. The glycoconjugates obtained were polymers of high molecular weight showing a higher stability than the native allergen or the conventional allergoid without mannan. The allergoid-mannan glycoconjugates were hypoallergenic as detected by the IgE reactivity with sera from grass allergic patients, even with lower reactivity than conventional allergoid without mannan. Thus, stable hypoallergenic allergoids conjugated to mannan suitable for using in immunotherapy can be achieved using glutaraldehyde. In contrast to mannan oxidation, the glutaraldehyde approach allows to preserve mannoses with their native geometry, which may be functionally important for its receptor-mediated recognition.

Background: Polymerized allergoids conjugated to mannan (PM) are suitable vaccines for allergen‐specific immunotherapy (AIT). Alum remains the most widely used adjuvant in AIT, but its way of action is not completely elucidated. The better understanding of the mechanisms underlying alum adjuvanticity could help to improve AIT vaccine formulations.Objective: We sought to investigate the potential influence of alum in the tolerogenic properties imprinted by PM at the molecular level.Methods: Flow cytometry, ELISAs, cocultures, intracellular staining and suppression assays were performed to assess alum and PM effects in human dendritic cells (DCs). BALB/c mice were immunized with PM alone or adsorbed to alum. Allergen‐specific antibodies, splenocyte cytokine production and splenic forkhead box P3 (FOXP3)⁺ regulatory T (Treg) cells were quantified. Metabolic and immune pathways were also studied in human DCs.Results: Alum decreases PD‐L1 expression and IL‐10 production induced by PM in human DCs and increases pro‐inflammatory cytokine production. Alum impairs PM‐induced functional FOXP3⁺ Treg cells and promotes Th1/Th2/Th17 responses. Subcutaneous immunization of mice with PM plus alum inhibits in vivo induction of Treg cells promoted by PM without altering the capacity to induce functional allergen‐specific blocking antibodies. Alum inhibits mTOR activation and alters metabolic reprogramming by shifting glycolytic pathways and inhibiting reactive oxygen species (ROS) production in PM‐activated DCs, impairing their capacity to generate functional Treg cells.Conclusion: We uncover novel mechanisms by which alum impairs the tolerogenic properties induced by PM, which might well contribute to improve the formulation of novel vaccines for AIT.

Chimeric antigen receptor (CAR)-T cell therapy has proven to be a powerful treatment for hematological malignancies. The situation is very different in the case of solid tumors, for which no CAR-T-based therapy has yet been approved. There are many factors contributing to the absence of response in solid tumors to CAR-T cells, such as the immunosuppressive tumor microenvironment (TME), T cell exhaustion, or the lack of suitable antigen targets, which should have a stable and specific expression on tumor cells. Strategies being developed to improve CAR-T-based therapy for solid tumors include the use of new-generation CARs such as TRUCKs or bi-specific CARs, the combination of CAR therapy with chemo- or radiotherapy, the use of checkpoint inhibitors, and the use of oncolytic viruses. Furthermore, despite the scarcity of targets, a growing number of phase I/II clinical trials are exploring new solid-tumor-associated antigens. Most of these antigens are of a protein nature; however, there is a clear potential in identifying carbohydrate-type antigens associated with tumors, or carbohydrate and proteoglycan antigens that emerge because of aberrant glycosylations occurring in the context of tumor transformation.

Innate immune cells experience long lasting metabolic and epigenetic changes after an encounter with specific stimuli. This facilitates enhanced immune responses upon secondary exposition to both the same and unrelated pathogens, a process termed trained immunity. Trained immunity‐based vaccines (TIbV) are vaccines able to induce innate immune memory, thus conferring heterologous protection against a broad range of pathogens. While trained immunity has been well documented in the context of infections and multiple immune‐mediated diseases, the role of innate immune memory and its contribution to the initiation and maintenance of chronic allergic diseases remains poorly understood. Over the last years, different studies attempting to uncover the role of trained immunity in allergy have emerged. Exposition to environmental factors impacting allergy development such as allergens or viruses induces the reprogramming of innate immune cells to acquire a more pro‐inflammatory phenotype in the context of asthma or food allergy. Several studies have convincingly demonstrated that prevention of viral infections using TIbV contributes to reduce wheezing attacks in children, which represent a high‐risk factor for asthma development later in life. Innate immune cells trained with specific stimuli might also acquire anti‐inflammatory features and promote tolerance, which may have important implications for chronic inflammatory diseases such as allergies. Recent findings showed that allergoid‐mannan conjugates, which are next generation vaccines for allergen‐specific immunotherapy (AIT), are able to reprogram monocytes into tolerogenic dendritic cells by mechanisms depending on metabolic and epigenetic rewiring. A better understanding of the underlying mechanisms of trained immunity in allergy will pave the way for the design of novel trained immunity‐based allergen vaccines as potential alternative strategies for the prevention and treatment of allergic diseases.