Eduardo Santos da Silva

Background: Blomia tropicalis is an important source of inhalant allergens in Southeast Asia and Latin America. Previous proteomics identified multiple Blo t 2 isoforms, yet their clinical relevance to Latin American populations and association with asthma phenotypes remain a priority in the field. Objective: To produce and purify the two recombinant isoforms rBlo t 2.2 and rBlo t 2.5 and physicochemically characterize them. Methods: Isoforms were expressed in E. coli Shuffle T7 and purified via cation-exchange chromatography. Structural features were verified by mass spectrometry and Fourier-transform infrared spectroscopy. Further, proteolytic stability and LPS-binding activity were determined. IgE-reactivity and allergenic activity were evaluated by Western blot, ELISA and mediator release assays. Sensitization patterns were analyzed in serum samples of Blomia tropicalis -allergic individuals with and without asthma from Brazil, Colombia, and Ecuador. Results: Both isoforms were correctly folded with proper disulfide bonds and exhibited high stability against endolysosomal proteases. Recombinant Blo t 2.2 lacked specific LPS-binding activity and displayed low cross-reactivity with rDer p 2. Across the three countries, the average sensitization rate to rBlo t 2.2 was 50%. Specifically, sensitization was observed in 47% of Brazilian teenagers and 52% of adults, 53% of Colombian individuals, and 48% of Ecuadorian children and teenagers. Sera from the Ecuadorian study exhibited the highest IgE reactivity. The rBlo t 2.2 isoform displayed significantly higher IgE-binding than rBlo t 2.5 in Brazil. Sensitization to rBlo t 2.2 was significantly more frequent in severe asthma patients than in mild asthma and rhinitis patients. Conclusion: rBlo t 2.2 is a stable, mid-tier to major isoform and a candidate biomarker for severe asthma in Brazil. Its structural and immunological characteristics support its inclusion in molecular diagnostic panels. However further investigations with larger sample sizes and application of multivariate analyses are still warranted to confirm our findings.

Summary Box: Chimeric hypoallergens of Der p 1 and Blo t 1 (QBD2/QBD4) reduce IgE reactivity and airway inflammation in mice. QBD4 promotes Th1/regulatory responses, suppressing mucus and eosinophilia more effectively than QBD2.

Severe asthma is a heterogeneous condition often resistant to conventional corticosteroid therapy, necessitating the identification of novel biomarkers and therapeutic targets. This study investigates immunological, transcriptional, and proteomic biomarkers in severe asthma patients from the Brazilian ProAR cohort. Cytokines were measured using a multiplex technology and the differential sputum cell count was performed by cytospin preparations. Sputum transcriptomics was performed by RNA-seq using Ion S5 next-generation sequencing platform. The proteomic study of sputum was performed by liquid chromatography–tandem mass spectrometry (LC-MS/MS) using Q Exactive Orbitrap technology. Compared to mild-to-moderate asthma (MMA) and treatment-controlled severe asthma (SAC), the treatment-resistant severe asthma (SAR) group exhibited increased sputum neutrophilia, eosinophilia, and elevated IL-6 and TNF levels, correlating with impaired lung function. Transcriptomic and proteomic analyses revealed a Th2-independent molecular signature characterized by downregulation of the Hippo signaling pathway and upregulation of JAK–STAT inflammatory cascades. Distinctive microRNA profiles suggest regulatory involvement in inflammatory and proliferative processes. These findings align with prior studies, reinforcing the presence of an IL-6- and TNF-high severe asthma phenotype across diverse populations. Our results highlight key inflammatory pathways that may underlie corticosteroid resistance, offering potential targets for personalized therapeutic interventions in severe asthma.

Background/Objectives: Allergen-specific immunotherapy remains the only disease-modifying treatment for allergic diseases, and the use of recombinant hypoallergenic derivatives is a promising therapeutic approach. Among these, BTH2 has previously shown efficacy in an acute murine model of allergy induced by Blomia tropicalis. The present study aimed to evaluate both the efficacy and safety of BTH2 in a chronic asthma model induced by B. tropicalis. Methods: A/J male mice (n = 6) were sensitized and chronically challenged with B. tropicalis extract over four months. One group repeatedly received subcutaneous doses of BTH2 (25 µg) for three months (65 doses). Parameters of allergic airway inflammation, antibody profiles, cytokine levels, and markers of AIT success were evaluated in bronchoalveolar lavage fluid, lung tissue, serum, and splenocyte cultures. Results: Repeated BTH2 administration was well tolerated, with no signs of systemic toxicity. BTH2 significantly reduced neutrophilic and eosinophilic airway inflammation, while increasing lymphocytes and regulatory cytokines in the lungs. It suppressed IgE against B. tropicalis allergens, while inducing mucosal IgA responses and systemic IgG, which may be linked to the observed blocking antibody activity in BTH2-treated mice. The treatment also led to downregulation of Th2 cytokines and enhanced expression of regulatory and Th1-associated cytokines, especially IL-10, TGF-β and IFN-γ. Correlation matrix analyses indicated that regulatory cytokines were correlated with beneficial antibody responses and reduced inflammation. Conclusions: BTH2 shows strong therapeutic and immunomodulatory effects in a chronic asthma model induced by B. tropicalis, with a favorable safety profile. These findings support its potential for future clinical trials, including those involving patients with allergic asthma.

Severe asthma is a heterogeneous condition often resistant to conventional corticosteroid therapy, necessitating the identification of novel biomarkers and therapeutic targets. This study investigates immunological, transcriptional, and proteomic biomarkers in severe asthma patients from the Brazilian ProAR cohort. Cytokines were measured using a multiplex technology (Luminex, Merck) and the differential sputum cell count was performed by cytospin preparations. Sputum transcriptomics was performed by RNA-seq using Ion S5 next-generation sequencing platform (ThermoFisher). The proteomic study of sputum was done by liquid chromatography-tandem mass spectrometry (LC-MS/MS) using Q Exactive Orbitrap technology (ThermoFisher). Compared to mild-to-moderate asthma (MMA) and treatment-controlled severe asthma (SAC), the treatment-resistant severe asthma (SAR) group exhibited increased sputum neutrophilia, eosinophilia, and elevated IL-6 and TNF levels, correlating with impaired lung function. Transcriptomic and proteomic analyses revealed a Th2-independent molecular signature characterized by downregulation of the Hippo signaling pathway and upregulation of JAK-STAT inflammatory cascades. Distinctive microRNA profiles suggest regulatory involvement in inflammatory and proliferative processes. These findings align with prior studies, reinforcing the presence of an IL-6 and TNF-high severe asthma phenotype across diverse populations. Our results highlight key inflammatory pathways that may underlie corticosteroid resistance, offering potential targets for personalized therapeutic interventions in severe asthma.

Updated notions about the so-called hygiene hypothesis consider now that helminths may have influence in the training of the immune system during childhood. Considering the similar type of immune response between helminth infections and allergic illnesses, the objective of this study was to evaluate how structural and functional conservation between house-dust mite allergens and their helminth orthologs might contribute to the cross-induction of IgE responses in allergies and helminthiasis. Amino acid sequences from group-1, -2, -5, -9, -10, -18, -21, and -23 allergens of the house dust mite Dermatophagoides pteronyssinus were retrieved from curated databases, and orthologs were identified in other mite species and different helminth parasites. We also assessed structural, conservational, functional, and immunologic relationships between these major mite allergens and their helminth counterparts. De novo 3D-modelling, B-cell epitopes prediction, structural conservation, and docking analyses were analyzed by Robetta platform, ElliPro and CBTope, RaptorX, and Z-Dock, respectively. Our results extend previous findings on structural conservations between major allergens and parasite proteins and show that these conservations go beyond the well-known conservations and may account for the observed immunological cross-reactions. This understanding can contribute in the near future to the development of more specific serological testing for mite-induced allergies and helminthiasis.

(1) Background: Modification of the structural elements of allergens is widely used in the field of allergies. The goal of the present research was to express, purify, and characterize the shortened recombinant group 5 allergen of Dermatophagoides pteronyssinus (rDer p 5). (2) Methods: rDer p 5 storage stability and aggregation capacity were explored through in silico analysis, dynamic light scattering (DLS), and SDS-PAGE. Serum IgE reactivity and cytokine amount were investigated in sera or cell culture supernatants through ELISA, MULTIPLEX^®, and Western blot analysis using sera from sensitized humans from Brazil, Colombia, and Ecuador. (3) Results: Dimeric rDer p 5 was detected through native PAGE, and this result was confirmed by data from DLS. The protein was thermically stable, as it did not degrade at 4 °C for 21 days. The shortened rDer p 5 was classified as a major IgE allergen in Brazil and Colombia, but minor in Ecuador. IL-13, IL-10, IL-1β, and IL-6 were significantly elevated in the sera of rDer p 5-reactive patients. The same cytokines plus IL-5 were more secreted by human cells upon rDer p 5 stimulation. (4) Conclusions: N-terminal peptide deletion led to a higher rDer p 5 folding stability, which, even though dimeric, was an IgE-reactive protein. Therefore, rDer p 5 could be used for molecular diagnostic applications or as backbone for hypoallergen design.

Background: Allergen‐specific immunotherapy (AIT) is the only disease‐modifying treatment approach to change disease‐causing allergens. Hypoallergenic derivatives show promise as potential therapeutics, amongst which BTH2 was designed to induce tolerance against Blomia tropicalis allergy. Our aim was to investigate the hypoallergenicity and immunoregulatory activity of BTH2 in vitro and its therapeutic potential in a mouse model of AIT.Methods: Recombinant Blo t 5 and Blo t 21 allergens and their hybrid derivatives (BTH1 and BTH2) were expressed and purified. IgE binding capacity was tested by ELISA using sera from Brazilian, Colombian, and Ecuadorian subjects. Secretion of cytokines in supernatants from human cell cultures was measured following stimulation with the four recombinants and controls. The capacity of BTH2 to ameliorate allergic airway inflammation induced by B. tropicalis extract was evaluated in a murine model of AIT.Results: rBlo t 5 and rBlo t 21 were identified as major allergens in Latin American patients, and BTH2 had the lowest IgE binding. In vitro stimulation of human cells induced greater levels of IL‐10 and IFN‐γ and reduced the secretion of Th2 cytokines. BTH2 ameliorated allergic airway inflammation in B. tropicalis‐challenged A/J mice, as evidenced by the histopathological and humoral biomarkers: decreased Th2 cytokines and cellular infiltration (especially eosinophils), lower activity of eosinophil peroxidase, an increase in IgG blocking antibodies and strong reduction of mucus production by goblet cells.Conclusions: Our study shows that BTH2 represents a promising candidate for the treatment of B. tropicalis allergy with hypoallergenic, immune regulatory and therapeutic properties. Further pre‐clinical studies are required in murine models of chronic asthma to further address the efficacy and safety of BTH2 as a vaccine against B. tropicalis‐induced allergy.