Intralymphatic Immunotherapy with Ultrasound Guidance Seems to Be Associated with Improved Clinical Effect in Canine Atopic Dermatitis-A Retrospective Study of 109 Cases.

Background: Intralymphatic immunotherapy (ILIT) has been used successfully in both human and veterinary medicine as a safe and effective treatment for allergic diseases. Initially, ILIT was administered by ultrasound guidance, but palpation-based injections have become more popular among veterinary dermatologists. Data from human medicine, however, show that precise injection into the lymph node is mandatory, and injection quality clearly correlates with clinical response. Hypothesis: Our aim was to assess the impact of the injection method (ultrasound guidance versus palpation-based guidance) on clinical response in dogs with atopic dermatitis. Methods: A total of 129 canine atopic dermatitis (CAD) cases treated with ILIT between 2014 and 2022 were retrieved from the hospital clinical database. The included dogs had to receive at least three intralymphatic injections administered either by palpation or ultrasound guidance. Those cases were retrospectively assessed and compared regarding clinical response to ILIT. Results: In total, 84 dogs received ILIT by ultrasound guidance, and in 25 dogs, ILIT was injected based on palpation. The success rate of ILIT was significantly higher in the ultrasound guidance group when compared to palpation-based injections. Conclusions: Low-quality injections must be considered as a possible reason for ILIT failure in dogs. Further prospective and controlled studies are necessary to confirm these results.

Heterogenous Induction of Blocking Antibodies against Ragweed Allergen Molecules by Allergen Extract-Based Immunotherapy Vaccines.

Currently, allergen-specific immunotherapy (AIT) for ragweed allergy is still based on natural allergen extracts. This study aimed to analyse the ability of four commercially available AIT vaccines (CLUSTOID, TYRO-SIT, POLLINEX Quattro Plus and Diater Depot) regarding their ability to induce IgG antibodies against ragweed pollen allergens in rabbits. Accordingly, the IgG reactivity of AIT-induced rabbit sera was tested for ten different ragweed pollen allergens (Amb a 1, 3, 4, 5, 6, 8, 9, 10, 11 and 12) by an ELISA. Furthermore, the ability of rabbit AIT-specific sera to block allergic patients' IgE binding to relevant ragweed allergens (Amb a 1, 4, 6, 8 and 11) and to inhibit allergen-induced basophil activation was evaluated by an IgE inhibition ELISA and a mediator release assay. Only two AIT vaccines (Diater Depot > CLUSTOID) induced relevant IgG antibody levels to the major ragweed allergen Amb a 1. The IgG responses induced by the AIT vaccines against the other ragweed allergens were low and highly heterogeneous. Interestingly, the kinetics of IgG responses were different among the AIT vaccines and even within one AIT vaccine (Diater Depot) for Amb a 1 (long-lasting) versus Amb a 8 and Amb a 11 (short-lived). This could be due to variations in allergen contents, the immunogenicity of the allergens, and different immunization protocols. The IgE inhibition experiments showed that rabbit AIT-specific sera containing high allergen-specific IgG levels were able to inhibit patients' IgE binding and prevent the mediator release with Diater Depot. The high levels of allergen-specific IgG levels were associated with their ability to prevent the recognition of allergens by patients' IgE and allergen-induced basophil activation, indicating that the measurement of allergen-induced IgG could be a useful surrogate marker for the immunological efficacy of vaccines. Accordingly, the results of our study may be helpful for the selection of personalized AIT vaccination strategies for ragweed-allergic patients.

Hymenoptera Venom Immunotherapy Meets Factitious Disorder.

Factitious disorder on self is a psychiatric disorder in which individuals fabricate or induce signs or symptoms of a disease. Factitious anaphylaxis, with symptoms suggestive of a life-threatening allergic reaction, is extremely rare. Several cases of factitious disorder reactions during allergen immunotherapy for airborne allergens have been reported. We report the case of a young female patient who presented factitious anaphylaxis during venom immunotherapy to vespid venom extract. Symptoms of stridor, dyspnea, coughing and loss of consciousness were observed during the built-up phase of venom immunotherapy, mimicking allergic reactions to the venom extracts. Diagnosis of factitious disorder prompted the discontinuation of venom immunotherapy.

B cells: The many facets of B cells in allergic diseases.

B cells play a key role in our immune system through their ability to produce antibodies, suppress a proinflammatory state, and contribute to central immune tolerance. We aim to provide an in-depth knowledge of the molecular biology of B cells, including their origin, developmental process, types and subsets, and functions. In allergic diseases, B cells are well known to induce and maintain immune tolerance through the production of suppressor cytokines such as IL-10. Similarly, B cells protect against viral infections such as severe acute respiratory syndrome coronavirus 2 that caused the recent coronavirus disease 2019 pandemic. Considering the unique and multifaceted functions of B cells, we hereby provide a comprehensive overview of the current knowledge of B-cell biology and its clinical applications in allergic diseases, organ transplantation, and cancer.

Allergic asthma: An indication for allergen immunotherapy.

. Allergen immunotherapy (AIT) as a validated, disease-modifying treatment is nowadays a widely recommended therapy option for allergic rhinitis and allergic asthma. The registration of allergen extracts used for AIT is based on allergen standardization, dose finding trials, and phase 3 trials proving their efficacy in high-quality, statistically significant randomized clinical trials. Real-world evidence (RWE) studies confirm the clinical relevance of these findings. The most data are available for the treatment of patients suffering from allergic rhinitis. Due to the similar inflammatory mechanisms, allergic rhinitis is often associated with allergic asthma. AIT, which induces tolerance against individual allergens, is the approach to treat the underlying mechanisms of these two interrelated respiratory diseases. Some trials have been published focusing primarily on the effect of AIT on parameters of allergic asthma. Here we give a summary of the evidence for the efficacy of AIT in the indication of allergic asthma.

Immune response modulation by allergen loaded into mesenchymal stem cell-derived exosomes as an effective carrier through sublingual immunotherapy.

BACKGROUND: Allergen-specific sublingual immunotherapy (SLIT) was considered an interesting needle-free alternative for subcutaneous immunotherapy (SCIT). Mesenchymal stem cell (MSC)-derived exosomes were introduced as potent nanoscale delivery systems with immunomodulatory potentials. The current study investigated the therapeutic efficacy of SLIT using ovalbumin (OVA)-enriched MSC-derived exosomes formulation in a murine model of allergic asthma. MATERIAL AND METHODS: MSCs were harvested from mice adipose tissues. Then, exosomes were isolated, and OVA-loaded exosomes were prepared. Following sensitization, Balb/c mice received therapeutic formulation (10 µg/dose OVA-containing MSC-derived exosomes) twice a week for two months. Serum OVA-specific IgE levels as well as IFN-γ, IL-4, and TGF-ß secretions by cultured splenocytes were measured by ELISA. Also, lung tissue underwent histopathologic analysis, and the numbers of inflammatory cells and eosinophils in nasopharyngeal lavage fluid (NALF) were examined. RESULTS: SLIT using OVA-enriched exosomes significantly reduced IgE levels and IL-4 production, while the secretion of IFN-γ and TGF-ß were significantly elevated. Also, a decrease was observed in the numbers of total cells and eosinophils in the NALF, and lower levels of perivascular and peribronchiolar inflammation and cellular infiltrations were observed in the lung tissue. CONCLUSION: SLIT using OVA-loaded exosomes improved immunomodulatory responses and efficiently alleviated allergic inflammation.

Allergen-specific immunotherapy with Alutard SQ improves allergic inflammation in house-dust mites-induced allergic asthma rats through inactivation of the HMGB1/TLR4/NF-κB pathway.

Background: Allergen-specific immunotherapy (AIT) is the only available safe, effective, and long-term treatment for allergic airway diseases, including allergic asthma. However, the potential molecular mechanism of AIT in ameliorating airway inflammation remains unknown. Methods: Rats were sensitized and challenged with house dust mite (HDM) and administered with Alutard SQ or/and high mobility group box 1 (HMGB1) inhibitor, ammonium glycyrrhizinate (AMGZ) or HMGB1 lentivirus. The total and differential cell counts in rat bronchoalveolar lavage fluid (BALF) were detected. Hematoxylin and eosin staining (H&E) was performed to examine the pathological lesions in lung tissues. Enzyme-linked immunosorbent assay (ELISA) was performed to assess the expression of inflammatory factors in lungs, BALF, and serum. Quantitative real-time PCR (qRT-PCR) was used to measure the levels of inflammatory factors in the lungs. Western blot assay was used to evaluate the expression of HMGB1, Τoll-like receptor 4 (TLR4), and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) in the lungs. Results: Consequently, AIT with Alutard SQ attenuated airway inflammation, the total and differential cells in BALF, and expression of Th (T helper)2 related cytokines and transforming growth factor beta 1 (TGF-ß1). The regimen also upregulated Th-1-related cytokine expression by inhibiting the HMGB1/TLR4/NF-κB pathway in HDM-induced asthmatic rats. Furthermore, AMGZ, a HMGB1 antagonist, amplified the functions of AIT with Alutard SQ in the asthma rat model. Nevertheless, overexpression of HMGB1 reversed the functions of AIT with Alutard SQ in the asthma rat model. Conclusions: In summary, this work demonstrates the role of AIT with Alutard SQ, which inhibits the HMGB1/TLR4/NF-κB signaling pathway in allergic asthma management.

C-Type Lectin Receptor Mediated Modulation of T2 Immune Responses to Allergens.

PURPOSE OF REVIEW: Allergic diseases represent a major health problem of increasing prevalence worldwide. In allergy, dendritic cells (DCs) contribute to both the pathophysiology and the induction of healthy immune responses to the allergens. Different studies have reported that some common allergens contain glycans in their structure. C-type lectin receptors (CLRs) expressed by DCs recognize carbohydrate structures and are crucial in allergen uptake, presentation, and polarization of T cell responses. This review summarizes the recent literature regarding the role of CLRs in the regulation of type 2 immune responses to allergens. RECENT FINDINGS: In this review, we highlight the capacity of CLRs to recognize carbohydrates in common allergens triggering different signaling pathways involved in the polarization of CD4+ T cells towards specific Th2 responses. Under certain conditions, specific CLRs could also promote tolerogenic responses to allergens, which might well be exploited to develop novel therapeutic approaches of allergen-specific immunotherapy (AIT), the single treatment with potential disease-modifying capacity for allergic disease. At this regard, polymerized allergens conjugated to non-oxidized mannan (allergoid-mannan conjugated) are next-generation vaccines targeting DCs via CLRs that promote regulatory T cells, thus favoring allergen tolerance both in preclinical models and clinical trials. A better understanding of the role of CLRs in the development of allergy and in the induction of allergen tolerance might well pave the way for the design of novel strategies for allergic diseases.

Mechanisms in AIT: Insights 2021.

BACKGROUND: Allergen-specific immunotherapy (AIT) is currently the only treatment with potential long-term disease-modifying effects for patients suffering from allergic diseases such as allergic rhinitis, allergic asthma, venom allergy, or IgE-mediated food allergy. A better understanding of the molecular mechanisms underlying immune responses during successful AIT is of utmost importance and it may help to develop more effective and safer treatments. MATERIALS AND METHODS: PubMed literature review was performed using keywords such as allergen-specific immunotherapy; regulatory T cells; regulatory B cells; regulatory innate lymphoid cells; and allergen-specific antibody from years 2018 to 2021. RESULTS: The proposed mechanism of long-term tolerance induction in AIT, even upon treatment discontinuation, involves basophils, mast cells, innate lymphoid cells, dendritic cells, allergen-specific regulatory T and B cells, downregulation of effector type 2 responses, decrease in the production of IgE and increase in production of allergen-specific blocking antibodies, such as IgG2 and IgG4. CONCLUSION: We summarize the most recent advances related to mechanisms involved in the restoration of healthy immune responses to allergens during AIT. Our knowledge in this regard has significantly improved over the last years, which might well contribute to design novel and improved therapeutic approaches.

Recent advances in improving intranasal allergen-specific immunotherapy; focus on delivery systems and adjuvants.

Allergen-specific Immunotherapy (AIT) is the main therapeutic strategy to control and treat allergic disorders. Intranasal Immunotherapy (INIT) was introduced as a needle-free, noninvasive, and efficient approach among various routes of allergen administration. Since direct exposure of nasal mucosa to allergen extracts could induce local and systemic reactions, recent studies focus on establishing novel formulations using various delivery systems and adjuvants to improve INIT efficacy. This review categorizes and describes natural and synthetic micro/nanoparticles such as chitosan, PLGA, liposome, exosome, and nano-emulation droplets used as delivery systems or immunomodulatory and immune-regulatory agents. Also, multiple microbial agents, including probiotics, mycobacterial and viral components, TLR ligands, and biologic agents, i.e., antibody fragments, recombinant cytokines, vitamin A, and pulsed dendritic cells (DCs), are other platforms that are discussed. In addition, future perspectives and proposed strategies to help INIT were provided.

Immunotherapy in the Treatment of Allergic Rhinitis in Children.

Allergic rhinitis (AR) is an inflammation of the nasal membranes characterized by multiple allergic symptoms. It is a widespread health problem that affects patients' ability to engage in social and physical activity, which lowers their quality of life. The pathophysiology of AR is complex and requires sensitization and the development of a specific immune response to the allergen. Allergen-specific immunotherapy (AIT) is a therapeutic method that induces specific immune tolerance to allergens. The objectives of this review are to demonstrate the mechanism of action of immunotherapy, explain how it alleviates clinical symptoms of allergic rhinitis, list the indications and contraindications of immunotherapy in the treatment of allergic rhinitis, and identify different modalities of allergen immunotherapy, their disease-modifying effects, as well as their potential risks and benefits. The review of the literature highlights that T-cell and B-cell responses to inhaled allergens are altered by AIT, which decreases both early and late reactions to allergen exposure. To induce clinical and immunologic tolerance, especially in the pediatric age, escalating dosages of the causing allergen are administered subcutaneously or sublingually. AIT is indicated for severe persistent AR when avoidance measures and medications are inadequate to control the symptoms. To conclude, AIT is a disease-modifying therapy that is safe and effective for the treatment of allergic rhinitis. It is indicated when the symptoms are uncontrolled or when there are undesirable effects from pharmacotherapy.

The Role of Regulatory T Cells in Epicutaneous Immunotherapy for Food Allergy.

In recent decades, a rapid increase in the prevalence of food allergies has led to extensive research on novel treatment strategies and their mechanisms. Mouse models have provided preliminary insights into the mechanism of epicutaneous immunotherapy (EPIT)-induced immune tolerance. In EPIT, antigen applied on the skin surface can be captured, processed, and presented in the lymph nodes (LNs) by Antigen-presenting cells (APCs). In the LNs, induction of regulatory T cells (Treg cells) requires both direct contact during antigen presentation and indirect mechanisms such as cytokines. Foxp3+CD62L+ Treg cells can exhibit the characteristics of hypomethylation of Foxp3 TSDR and Foxp3-LAP+ Treg cells, which increase the expression of surface tissue-specific homing molecules to exert further sustained systemic immune tolerance. Studies have shown that EPIT is a potential treatment for food allergies and can effectively induce immune tolerance, but its mechanism needs further exploration. Here, we review Treg cells' role in immune tolerance induced by EPIT and provide a theoretical basis for future research directions, such as the mechanism of EPIT and the development of more effective EPIT treatments.

Two years of treatment with the recombinant grass pollen allergy vaccine BM32 induces a continuously increasing allergen-specific IgG4 response.

BACKGROUND: BM32, a grass pollen allergy vaccine containing four recombinant fusion proteins consisting of hepatitis B-derived PreS and hypoallergenic peptides from the major timothy grass pollen allergens adsorbed on aluminium hydroxide has been shown to be safe and to improve clinical symptoms of grass pollen allergy upon allergen-specific immunotherapy (AIT). We have investigated the immune responses in patients from a two years double-blind, placebo-controlled AIT field trial with BM32. METHODS: Blood samples from patients treated with BM32 (n = 27) or placebo (Aluminium hydroxide) (n = 13) were obtained to study the effects of vaccination and natural allergen exposure on allergen-specific antibody, T cell and cytokine responses. Allergen-specific IgE, IgG, IgG1 and IgG4 levels were determined by ImmunoCAP and ELISA, respectively. Allergen-specific lymphocyte proliferation by 3H thymidine incorporation and multiple cytokine responses with a human 17-plex cytokine assay were studied in cultured peripheral blood mononuclear cells (PBMCs). FINDINGS: Two years AIT comprising two courses of 3 pre-seasonal injections of BM32 and a single booster after the first pollen season induced a continuously increasing (year 2 > year 1) allergen-specific IgG4 response without boosting allergen-specific IgE responses. Specific IgG4 responses were accompanied by low stimulation of allergen-specific PBMC responses. Increases of allergen-specific pro-inflammatory cytokine responses were absent. The rise of allergen-specific IgE induced by seasonal grass pollen exposure was partially blunted in BM32-treated patients. INTERPRETATION: AIT with BM32 is characterised by the induction of a non-inflammatory, continuously increasing allergen-specific IgG4 response (year 2 > year1) which may explain that clinical efficacy was higher in year 2 than in year 1. The good safety profile of BM32 may be explained by lack of IgE reactivity and low stimulation of allergen-specific T cell and cytokine responses. FUNDINGS: Grants F4605, F4613 and DK 1248-B13 of the Austrian Science Fund (FWF).

Il-10 producing T and B cells in allergy.

The molecular and cellular mechanisms of allergen tolerance in humans have been intensively studied in the past few decades. The demonstration of epitope-specific T cell tolerance, particularly mediated by the immune suppressor functions of IL-10 led to a major conceptual change in this area more than 20 years ago. Currently, the known essential components of allergen tolerance include the induction of allergen-specific regulatory of T and B cells, the immune suppressive function of secreted factors, such as IL-10, IL-35, IL-1 receptor antagonist and TGF-ß, immune suppressive functions of surface molecules such as CTLA-4 and PD-1, the production IgG4 isotype allergen-specific blocking antibodies, and decreased allergic inflammatory responses by mast cells, basophils, and eosinophils in inflamed tissues. In this review, we explain the importance of the role of IL-10 in allergen tolerance.

Next-Generation of Allergen-Specific Immunotherapies: Molecular Approaches.

PURPOSE OF REVIEW: The aim of this article is to discuss how allergen-specific immunotherapy (AIT) can be improved through molecular approaches. We provide a summary of next-generation molecular AIT approaches and of their clinical evaluation. Furthermore, we discuss the potential of next generation molecular AIT forms for the treatment of severe manifestations of allergy and mention possible future molecular strategies for the secondary and primary prevention of allergy. RECENT FINDINGS: AIT has important advantages over symptomatic forms of allergy treatment but its further development is limited by the quality of the therapeutic antigen preparations which are derived from natural allergen sources. The field of allergy diagnosis is currently undergoing a dramatic improvement through the use of molecular testing with defined, mainly recombinant allergens which allows high-resolution diagnosis. Several studies demonstrate that molecular testing in early childhood can predict the development of symptomatic allergy later on in life. Clinical studies indicate that molecular AIT approaches have the potential to improve therapy of allergic diseases and may be used as allergen-specific forms of secondary and eventually primary prevention for allergy.

Mite-Allergic Rhinitis: How to Evaluate Clinical Efficacy in Allergen-Specific Immunotherapy Trials?

House dust mite (HDM) allergen exposure is the most important cause of perennial allergic rhinitis and/or asthma. Although allergen-specific immunotherapy (AIT) with HDM is well established, published studies have been characterized by substantial heterogeneity in clinical endpoints. Standardization in measuring clinical efficacy is required. Moreover, when designing an AIT trial with HDM allergens, several considerations have to be taken into account. The history of HDM allergy is less clear cut than the typical history of pollen allergy. In addition, clinical features of HDM allergy may differ from those of pollen allergy. Moreover, although not easily measurable, fluctuation in allergen exposure may cause variation in symptom severity and determine the timing of assessment of clinical effects of HDM AIT. Key points 1. A combined symptom and medication score (CSMS) is recommended as standard for the primary endpoint in future house dust mite (HDM) allergen-specific immunotherapy trials. 2. The diagnosis of HDM allergy is based on a carefully taken history in combination with sensitization to HDM allergens. 3. Eye symptoms are less prominent in patients with HDM-induced allergic rhinitis. Nasal symptoms, but not eye symptoms, should be included in the CSMS and in symptom scores as well. 4. As methods to determine allergen exposure vary and the efficacy of environmental control is a matter of debate, a practical approach consists of restraining patients from implementing HDM-reducing measures, such as removing carpets and introducing anti-mite covers, after the start of the study. 5. Efficacy evaluation in the period with the highest exposure to mites is recommended.