Allergen Immunotherapy in Asthma

Preventive allergen immunotherapy with inhalant allergens in children

The efficacy and safety of preventive allergen immunotherapy (pAIT) in children are currently under investigation. Here, we provide an overview of pAIT with respiratory allergens concerning the prevention of new sensitizations, allergic disease onset and progression as well as further immunomodulatory effects. Three databases were searched for clinical pAIT studies in children. Selected publications were reviewed for preventive outcomes according to prevention level (primary, secondary, and tertiary), allergen type, administration route, dose, and treatment duration. The primary prevention approach appears safe but showed no allergen-specific effect on new sensitizations. Secondary prevention seems feasible and may induce regulatory T cell-mediated immunotolerance. The number of studies at these prevention levels is limited. Tertiary prevention with grass and/or tree pollen-based pAIT has shown efficacy in preventing disease progression from allergic rhinitis/conjunctivitis to asthma. Data on tertiary pAIT with house dust mites and other allergen types are inconclusive. Subcutaneous and sublingual routes appear similarly effective, but head-to-head comparative paediatric studies are scarce. Additionally, there are fewer placebo-controlled studies. Nevertheless, immunomodulatory outcomes of pAIT are encouraging. Currently, limited but favourably suggestive evidence is available for preventing respiratory allergic diseases in children by pAIT. Primary and secondary prevention have potential and warrant further investigation through well-designed studies.

Three Artemisia pollens trigger the onset of allergic rhinitis via TLR4/MyD88 signaling pathway

OBJECTIVE

The prevalence of allergic rhinitis is high, making it a relatively common chronic condition. Countless patients suffer from seasonal Allergic rhinitis (AR). The objective of this investigation is to examine the potential involvement of common pollen allergens in seasonal allergic rhinitis, and study the proposed mechanism of Toll-like receptor 4 (TLR4)/Myeloid differentiation primary response gene 88 (MyD88) signaling pathway in the induction of AR.

METHOD

A mouse AR model (sensitized group) was constructed with pollen extracts and ovalbumin (OVA) of Artemisia annua (An), Artemisia argyi (Ar) and Artemisia Sieversiana (Si), and thereafter, AR symptom score was performed. After successful modeling, mouse serum and nasal mucosa tissues were extracted for subsequent experiments. The expression levels of immunoglobulin E (IgE), Interleukin (IL)-4, IL-5, IL-13 and Tumor Necrosis Factor-α (TNF-α) in serum were detected using Enzyme-linked immunosorbent assay (ELISA); Hematoxylin-eosin (H&E) staining methods were used to observe the pathological changes of the nasal mucosal tissue; Utilizing immunohistochemistry (IHC) staining, the expression levels of TLR4, MyD88 and Nuclear factor kappa B (NF-κB) p65 in mouse nasal mucosa were quantified; The mRNA and protein expression levels of TLR4, MyD88 and NF-κB p65 in nasal mucosa of sensitized mice were detected with Quantitative reverse transcription PCR (qRT-PCR) and Western Blot. Finally, the in vitro culture of Human nasal mucosal epithelial cells (HNEpC) cells was conducted, and cells were treated with 200 µg/ml Artemisia annua pollen extract and OVA for 24 h. Western Blot assay was used to detect the expression level of TLR4, MyD88 and NF-κB p65 proteins before and after HNEpC cells were treated with MyD88 inhibitor ST-2825.

RESULT

On the second day after AR stimulation, the mice showed obvious AR symptoms. H&E results showed that compared to the control group, the nasal mucosal tissue in the sensitized group was significantly more inflamed. Furthermore, ELISA assay showed increased expression levels of IgE, IL-4, IL-5, IL-13 and TNF-α in serum of mice induced by OVA and Artemisia annua pollen, Artemisia argyi pollen and Artemisia Sieversiana pollen than those of the control group. However, the expression level of IL-2 was lower than that of the control group (P < 0.05). Using Immunohistochemistry staining visually observed the expression levels of TLR4, MyD88 and NF-κB p65 in mouse nasal mucosa tissues and quantitatively analyzed. The expression levels of TLR4, MyD88 and NF-κB p65 in the sensitized group were higher than those in the control group, and the differences were statistically significant (P < 0.05). The results from qRT-PCR and Western Blot showed that the mRNA and protein expression levels of TLR4, MyD88 and NF-κB p65 in nasal mucosa of the sensitized group were significantly higher than those in the control group (P < 0.05). Finally, HNEpC cells were cultured in vitro and analyzed using Western Blot. The expression levels of TLR4, MyD88 and NF-κB p65 in OVA and An groups were significantly increased (P < 0.05). After ST-2825 treatment, TLR4 protein expression was significantly increased (P < 0.05) and MyD88 and NF-κB p65 protein expression were significantly decreased (P < 0.05).

CONCLUSION

To sum up, the occurrence and development of AR induced by OVA and pollen of Artemisia annua, Artemisia argyi and Artemisia Sieversiana were related to TLR4/MyD88 signal pathway.

Peripheral macrophages in the development and progression of structural cerebrovascular pathologies

The human cerebrovascular system is responsible for maintaining neural function through oxygenation, nutrient supply, filtration of toxins, and additional specialized tasks. While the cerebrovascular system has resilience imparted by elaborate redundant collateral circulation from supportive tertiary structures, it is not infallible, and is susceptible to developing structural vascular abnormalities. The causes of this class of structural cerebrovascular diseases can be broadly categorized as 1) intrinsic developmental diseases resulting from genetic or other underlying aberrations (arteriovenous malformations and cavernous malformations) or 2) extrinsic acquired diseases that cause compensatory mechanisms to drive vascular remodeling (aneurysms and arteriovenous fistulae). Cerebrovascular diseases of both types pose significant risks to patients, in some cases leading to death or disability. The drivers of such diseases are extensive, yet inflammation is intimately tied to all of their progressions. Central to this inflammatory hypothesis is the role of peripheral macrophages; targeting this critical cell type may lead to diagnostic and therapeutic advancement in this area. Here, we comprehensively review the role that peripheral macrophages play in cerebrovascular pathogenesis, provide a schema through which macrophage behavior can be understood in cerebrovascular pathologies, and describe emerging diagnostic and therapeutic avenues in this area.

Advancements in Allergen Immunotherapy for the Treatment of Atopic Dermatitis

Atopic dermatitis (AD) is a chronic inflammatory skin condition that affects individuals of all age groups, manifesting as a spectrum of symptoms varying from mild to severe. Allergen immunotherapy (AIT) involves the administration of allergen extracts and has emerged as a potential treatment strategy for modifying immune responses. Its pathogenesis involves epidermal barrier dysfunction, microbiome imbalance, immune dysregulation, and environmental factors. Existing treatment strategies encompass topical steroids to systemic agents, while AIT is under investigation as a potential immune-modifying alternative. Several studies have shown reductions in the severity scoring of atopic dermatitis (SCORAD) scores, daily rescue medication use, and visual analog scale (VAS) scores following AIT. Biomarker changes include increased IgG4 levels and decreased eosinophil counts. This review provides valuable insights for future research and clinical practice, exploring AIT as a viable option for the management of AD.

Allergen immunotherapy in China

Allergen immunotherapy (AIT) is an etiological treatment strategy that involves administering escalating doses of clinically relevant allergens to desensitize the immune system. It has shown encouraging results in reducing allergy symptoms and enhancing patients' quality of life. In this review, we offer a thorough overview of AIT in China, examining its efficacy, safety, current practices, and prospects. We further underscore the progress made in AIT research and clinical applications, as well as the distinct challenges and opportunities that China faces in this area.

Factors associated with allergic rhinitis and combined allergic rhinitis and asthma syndrome (CARAS) in adults undergoing immunotherapy in a tropical country: Is ISAAC-III questionnaire useful in adult populations?

BACKGROUND

Allergic diseases affect about 10-30% of the population in low- or middle-income tropical countries. Few studies describe the factors associated with allergic diseases in adult patients undergoing immunotherapy in Latin American countries.

OBJECTIVE

This study aimed to determine the factors associated with allergic rhinitis (AR) and AR in comorbidity with asthma (CARAS) in adults treated with immunotherapy in two allergy referral centers in Bogotá (Colombia).

MATERIAL AND METHODS

Observational, cross-sectional study conducted between January 2018 and January 2019. ISAAC-III and sociodemographic questionnaires were applied to determine the factors associated with AR and CARAS in adults treated with immunotherapy who attended the allergy consult at the Fundación Santa Fe de Bogotá and Unimeq-Orl.

RESULTS

Among 416 adults aged 18-68 years, 71.4% (n = 297) were women. Regarding the sensitization results obtained by skin prick test, the most frequent allergens were house dust mites (64.18%): 49.03% were positive for both Dermatophagoides pteronyssinus and Dermatophagoides farinae, while 28.61% were positive for Blomia tropicalis. Excluding house dust mites, the most frequent allergens were dog hair (31.01%), cat hair (15.1%), grasses (15.9%), and food (15.9%). The main factor associated with exclusive AR was regular acetaminophen use more than four times a year: Prevalence ratio (PR) = 1.77 (95% CI: 1.12-2.25). The main factor associated with CARAS was cesarean delivery PR: 1.44 (95% CI: 1.09-1.78).

CONCLUSION

The main factor associated with AR was regular acetaminophen use, while that associated with CARAS was cesarean delivery. The ISAAC-III questionnaire can be a useful low-cost tool to assess the factors associated with allergic diseases in adults in tropical countries.

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-β1). 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.

On the role of allergen-specific IgG subclasses for blocking human basophil activation

Successful treatment of IgE mediated allergies by allergen-specific immunotherapy (AIT) usually correlates with the induction of allergen-specific IgG4. However, it is not clear whether IgG4 prevents the allergic reaction more efficiently than other IgG subclasses. Here we aimed to compare allergen-specific monoclonal IgG1 and IgG4 antibodies in their capacity to inhibit type I allergic reactions by engaging FcγRIIb. We found that IgG1, which is the dominant subclass induced by viruses, binds with a similar affinity to the FcγRIIb as IgG4 and is comparable at blocking human basophil activation from allergic patients; both by neutralizing the allergen as well as engaging the inhibitory receptor FcγRIIb. Hence, the IgG subclass plays a limited role for the protective efficacy of AIT even if IgG4 is considered the best correlate of protection, most likely simply because it is the dominant subclass induced by classical AITs.

Impact of Therapeutics on Unified Immunity During Allergic Asthma and Respiratory Infections

Asthma is a common chronic respiratory disease that affects millions of people worldwide. Patients with allergic asthma, the most prevalent asthma endotype, are widely considered to possess a defective immune response against some respiratory infectious agents, including viruses, bacteria and fungi. Furthermore, respiratory pathogens are associated with asthma development and exacerbations. However, growing data suggest that the immune milieu in allergic asthma may be beneficial during certain respiratory infections. Immunomodulatory asthma treatments, although beneficial, should then be carefully prescribed to avoid misuse and overuse as they can also alter the host microbiome. In this review, we summarize and discuss recent evidence of the correlations between allergic asthma and the most significant respiratory infectious agents that have a role in asthma pathogenesis. We also discuss the implications of current asthma therapeutics beyond symptom prevention.