Preclinical safety and immunological efficacy of Alternaria alternata polymerized extracts

Polymerized Molecular Allergoid Alt a1: Effective SCIT in Pediatric Asthma Patients

Background: Allergy to Alternaria alternata (Alt a), although often underdiagnosed, is a significant global health issue. In the allergen immunotherapy (AIT) field, novel therapeutic strategies are emerging, particularly with the advent of polymerized allergoids. This study aims to evaluate the efficacy of subcutaneous immunotherapy (SCIT) based on these innovative molecules in children with respiratory allergies, assessing clinical and functional parameters. Methods: We enrolled 42 patients aged between 6 and 16 years, all of whom had allergic rhinitis (AR) and concomitant asthma and all of whom were monosensitized to Alt a. Between December 2020 and December 2021, 17 patients initiated SCIT with Modigoid® for Alt a1, while 25 patients continued with standard therapy. At the initial visit (T0), all the patients underwent nasal and bronchial evaluation, including exhaled nitric oxide (eFeNO) measurement and spirometry. The Asthma Control Test (ACT) was used to evaluate the control of asthma symptoms. Patients were followed up every 6 months, with a comprehensive re-evaluation at 24 months (T1) replicating the initial assessments. Results: After 24 months of SCIT with the new polymerized molecular allergoid Alt a1 (Modigoid®), children showed a statistically significant reduction in eFeNO levels, improved FEV1 values, and enhanced ACT scores. Conclusions: SCIT with the new molecular allergoid Alt a1 significantly improves functional parameters (FEV1 and eFeNO) and subjective asthma symptoms (ACT scores) in children with AR and objective asthma signs. This treatment represents an effective preventive strategy that can be used to halt the progression of the classic atopic march from AR to asthma and potentially reverse the atopic march.

Characterisation of Alternaria alternata Allergoids: Evaluation of the Stability of Grass Pollen Allergen Extracts Mixed with Alternaria alternata Allergoids

Allergens from pollen, mites, and moulds often sensitise patients simultaneously, posing challenges for developing stable and effective combination vaccines. Alternaria alternata, a major source of indoor and outdoor allergens, is strongly linked to asthma development and contains proteolytic enzymes that can degrade other allergens, potentially reducing vaccine efficacy. This study aimed to evaluate the safety, efficacy, and stability of polymerised A. alternata extracts (allergoids) compared to native extracts and their compatibility with pollen extracts (Phleum pratense). Allergoids were prepared using glutaraldehyde and characterised through SDS-PAGE, LC-MS/MS, NMR, and gas chromatography. Their immunogenicity and IgE-binding properties were assessed via Western blot and ELISA competition assays, while enzymatic activity was analysed using ApiZym kits. Mice immunisation experiments were conducted to evaluate antibody responses. Polymerised extracts exhibited reduced IgE-binding capacity while maintaining IgG-binding and immunogenicity. Mice immunised with allergoids generated antibodies that efficiently blocked IgE binding in allergic patients. Proteolytic activity was significantly reduced in allergoids, and pollen extracts remained stable when combined with them. These findings demonstrate that A. alternata allergoids are a safer, more stable alternative for immunotherapy, offering enhanced efficacy and reduced injections for polysensitised patients. This study provides critical insights for designing optimised combination vaccines.

Immunotherapy against environmental fungi causing respiratory allergy

Allergic respiratory diseases (ARDs) have been one of the major global health problems of the 21st century with an increasing prevalence. A significant proportion of aerobiological particles in the environment is constituted by fungal structures, including those from Alternaria, Cladosporium, Penicillium, and Aspergillus species which are regarded as the four most common fungal genera associated with allergic fungal airway diseases (AFADs). Allergen specific immunotherapy (AIT) has capacity to promote protection as well as long-term tolerance to the allergen, however there have not been adequate number of studies evaluating the efficacy of against AFADs, up till today. Our review would like to draw more attention to the field by summarizing the current literature regarding the clinical use of the immunotherapy, with special focus on Alternaria, and Cladosporium AITs. The area is considered to be vital to public health due to the potential increase in global AFAD cases because of ongoing air pollution and climate impacts. The review also aims to sum up immunological findings associated with mould-AIT which would help further studies to be performed in order to develop an objective method to identify non-responders early in the course of therapy.

In silico approaches for the identification of potential allergens among hypothetical proteins from Alternaria alternata and its functional annotation

Direct exposure to the fungal species Alternaria alternata is a major risk factor for the development of asthma, allergic rhinitis, and inflammation. As of November 23rd 2020, the NCBI protein database showed 11,227 proteins from A. alternata genome as hypothetical proteins (HPs). Allergens are the main causative of several life-threatening diseases, especially in fungal infections. Therefore, the main aim of the study is to identify the potentially allergenic inducible proteins from the HPs in A. alternata and their associated functional assignment for the complete understanding of the complex biological systems at the molecular level. AlgPred and Structural Database of Allergenic Proteins (SDAP) were used for the prediction of potential allergens from the HPs of A. alternata. While analyzing the proteome data, 29 potential allergens were predicted by AlgPred and further screening in SDAP confirmed the allergic response of 10 proteins. Extensive bioinformatics tools including protein family classification, sequence-function relationship, protein motif discovery, pathway interactions, and intrinsic features from the amino acid sequence were used to successfully predict the probable functions of the 10 HPs. The functions of the HPs are characterized as chitin-binding, ribosomal protein P1, thaumatin, glycosyl hydrolase, and NOB1 proteins. The subcellular localization and signal peptide prediction of these 10 proteins has further provided additional information on localization and function. The allergens prediction and functional annotation of the 10 proteins may facilitate a better understanding of the allergenic mechanism of A. alternata in asthma and other diseases. The functional domain level insights and predicted structural features of the allergenic proteins help to understand the pathogenesis and host immune tolerance. The outcomes of the study would aid in the development of specific drugs to combat A. alternata infections.

Subcutaneous Immunotherapy (SCIT) with the New Polymerized Molecular Allergoid Alt a1: A Pilot Study in Children with Allergic Rhinitis Sensitized to Alternaria Alternata

BACKGROUND

We followed the effects of a new SCIT with a chemically polymerized allergen Alt a1, evaluating the trend of clinical and functional parameters in an observational-prospective study.

METHODS

42 children with AR and intermittent asthma sensitized to A.A.: 17 patients started SCIT (Modigoid^®), and 25 continued symptomatic therapy. At the initial visit (T0), all patients performed total IgE (tIgE) and specific IgE (sIgE) for Alt a1, nasal nitric oxide (nFeNo), nasal cytology, anterior active rhinomanometry (AAR) and spirometry. After 24 months (T1), they repeated the same procedures as in T0.

RESULTS

Patients treated with Modigoid presented a statistically significant (p < 0.001) reduction of nFeNO (T0:1651.06 ± 149.18; T1: 1394.12 ± 108.98), tIgE (T0: 311.48 ± 144.18; T1: 164.73 ± 50.69), sIgE for Alt a1 (T0: 28.59 ± 12.69; T1: 19.54 ± 7.37), an improvement of nasal airflow (T0: 71.62 ± 8.66; T1: 95.12 ± 5.91), nasal eosinophils (T0: 20.59 ± 2.35; T1: 14.88 ± 1.65) and FEV1 (T0: 95.58 ± 7.91; T1: 116.64 ± 5.94).

CONCLUSIONS

The new SCIT for Alt a1 significantly improves AR symptoms from a subjective, objective point of view and laboratory and functional parameters.

Single-cell RNA sequencing identifies precise tolerogenic cellular and molecular pathways induced by depigmented-polymerized grass pollen allergen extract

BACKGROUND

Immunologic mechanism of action of allergoids remains poorly understood. Previous models of allergenicity and immunogenicity have yielded suboptimal knowledge of these immunotherapeutic vaccine products. Novel single-cell RNA sequencing technology offers a bridge to this gap in knowledge.

OBJECTIVE

We sought to identify the underpinning tolerogenic molecular and cellular mechanisms of depigmented-polymerized Phleum pratense (Phl p) extract.

METHODS

The molecular mechanisms underlying native Phl p, depigmented Phl p (DPG-Phl p), and depigmented-polymerized (DPG-POL-Phl p) allergoid were investigated by single-cell RNA sequencing. Allergen-specific T_H2A, T follicular helper (Tfh), and IL-10⁺ regulatory B cells were quantified by flow cytometry in peripheral blood mononuclear cells from 16 grass pollen-allergic and 8 nonatopic control subjects. The ability of Phl p, DPG-Phl p, and DPG-POL-Phl p to elicit FcεRI- and FcεRII-mediated IgE responses was measured by basophil activation test and IgE-facilitated allergen binding assay.

RESULTS

Analysis revealed that DPG-POL-Phl p downregulated genes associated with T_H2 signaling, induced functional regulatory T cells exhibiting immunosuppressive roles through CD52 and Siglec-10, modulated genes encoding immunoproteasome that dysregulate the processing and presentation of antigens to T cells and promoted a shift from IgE toward an IgA₁ and IgG responses. In grass pollen-allergic subjects, DPG-POL-Phl p exhibited reduced capacity to elicit proliferation of T_H2A, IL-4⁺ Tfh and IL-21⁺ Tfh cells while being the most prominent at inducing IL-10⁺CD19⁺CD5^hi and IL-10⁺CD19⁺CD5^hiCD38^intCD24^int regulatory B-cell subsets compared to Phl p (all P < .05). Furthermore, DPG-POL-Phl p demonstrated a hypoallergenic profile through basophil activation and histamine release compared to Phl p (31.54-fold, P < .001).

CONCLUSIONS

Single-cell RNA sequencing provides an in-depth resolution of the mechanisms underlying the tolerogenic profile of DPG-POL-Phl p.

Perspectives in Allergen-Specific Immunotherapy: Molecular Evolution of Peptide- and Protein-Based Strategies

Allergen-specific Immunotherapy (AIT), through repetitive subcutaneous or sublingual administrations of allergen extracts, represents up to now the unique treatment against allergic sensitizations. However, the clinical efficacy of AIT can be largely dependent on the quality of natural allergen extracts. Moreover, the long duration and adverse side effects associated with AIT negatively impact patient adherence. Tremendous progress in the field of molecular allergology has made possible the design of safer, shorter and more effective new immunotherapeutic approaches based on purified and characterized natural or recombinant allergen derivatives and peptides. This review will summarize the characteristics of these different innovative vaccines including their effects in preclinical studies and clinical trials.

Specific Dermatophagoides farinae extract for canine immunotherapy

BACKGROUND

Canine atopic dermatitis (cAD) is a pruritic allergic skin disease most often caused by Dermatophagoides farinae. Differences in the sensitization profile to D. farinae have been reported between people and dogs. However, allergic dogs traditionally have been treated with extracts intended for human immunotherapy.

HYPOTHESIS/OBJECTIVES

To develop a specific allergen immunotherapy for veterinary practice enriched in canine major allergens and to demonstrate its in vitro efficacy.

ANIMALS

Twenty privately owned dogs, clinically diagnosed with cAD, and three healthy dogs.

METHODS AND MATERIALS

A veterinary D. farinae allergen extract was manufactured and characterized compared to D. farinae extract used for human immunotherapy. The protein profile was analysed by SDS-PAGE and size exclusion chromatography and Der f 15 and Der f 18 allergens quantified by mass spectrometry. The allergenic profile was studied by immunoblot and the biological potency by enzyme-linked immunosorbent assay-inhibition assays. The extract's capacity to induce cytokine production [interleukin (IL)-10, interferon (IFN)-Ɣ] by peripheral blood mononuclear cells also was evaluated.

RESULTS

The veterinary extract showed a higher content of high molecular weight proteins, preferentially recognized by atopic dog sera. The fold-increases in Der f 15 and Der f 18 with respect to the human extract were 2.07 ± 0.32 and 1.63 ± 0.15, respectively. The veterinary extract showed higher biological potency (0.062 versus 0.132 µg required for 50% inhibition of dogs sera) compared to the human extract and induced significantly higher levels of IL-10 (1,780 pg/mL) and IFN-Ɣ (50.4 pg/mL) with respect to the negative control.

CONCLUSIONS AND CLINICAL IMPORTANCE

A veterinary D. farinae extract with a higher content of dog major allergens was developed and in vitro efficacy demonstrated by immunological parameters.

Allergen immunotherapy in asthma: current evidence

Background: Allergic asthma is the predominant phenotype in clinical practice. Allergen immunotherapy is the only curative and specific approach for the treatment of allergies with clinical benefits for several years after its discontinuation. Despite advances, the use of allergen immunotherapy in allergic asthma is still suboptimal and controversial.Objective: The purpose of this article is to review the published data about the impact of allergen immunotherapy with the most commonly used allergen extracts on allergic asthma outcomes, including both clinical parameters and patients' subjective experience (quality of life).Methods: As data sources several databases were used, including PubMed, Scopus, Web of Science (2002-2019) and search in English and Spanish languages was performed using the following terms: "allergen immunotherapy" and "asthma" in combination with "house dust mite", "birch pollen", "grass pollen", "olive tree pollen", "molds", "pets" and "asthma quality of life". Randomised control trials and meta-analysis from reviewed publications were selected.Results: Emerging data relating to the positive impact on asthma outcomes of allergen immunotherapy allows the addition of this treatment as a therapeutic option in mild to moderate asthmatics sensitized to house dust mite and pollens. Limited data are available for patients sensitized to molds and pets, as well in severe allergic asthma population.Conclusion: Allergen immunotherapy remains a potential therapeutic option for some patients with allergic asthma. Further research is needed to define the optimal period of treatment, the possible therapeutic role in the treatment of severe allergic asthma, and the cost-effectiveness of allergen immunotherapy in asthmatic patients.