Further Understanding of Neuro-Immune Interactions in Allergy: Implications in Pathophysiology and Role in Disease Progression

The Clinical Efficacy and Safety of Endoscopic Vidian-Branch Neurectomy in Intractable Allergic Rhinitis

OBJECTIVE

Intractable allergic rhinitis (iAR) remains a clinical challenge. This study aims to evaluate the efficacy and safety of endoscopic selective vidian branch neurectomy for iAR.

STUDY DESIGN

A prospective clinical study.

SETTING

A tertiary referral center.

METHODS

A total of 205 iAR patients were initially recruited and divided into 3 groups: endoscopic vidian-branch neurectomy (EVBN), endoscopic vidian neurectomy (EVN), and conservative treatment (control). All patients were followed up for more than 2 years, and the efficacy and postoperative complications were compared.

RESULTS

After 2-year follow-up, a total of 195 patients were included, with 59 patients in EVBN group, 71 in EVN group, and 64 in control group. Post-treatment assessments at 6 months, 1 year, and 2 years revealed significant reductions in the total Rhinoconjunctivitis Quality of Life Questionnaire (RQLQ) scores and each domain in both EVBN and EVN groups compared to their baseline levels. However, no significant changes were observed in control group. Furthermore, the improvements in RQLQ 2 years post-treatment were higher in EVBN and EVN groups compared to control group. In EVBN group, only 3 (5.1%) patients reported mild eye dryness during the first month postoperation. However, in the EVN group, 15 (21.1%) patients experienced eye dryness, with 6 (8.5%) cases persisting for more than 1 year and remaining unresolved by the end of the 2-year follow-up.

CONCLUSION

Both EVBN and EVN were effective in iAR patients. However, EVBN appears to be a safer option, associated with fewer postoperative complications.

Neuro-immune regulation in allergic Diseases: Role of neuropeptides

The role of neuro-immune interaction in allergic diseases, a group of common immune system diseases, has garnered increasing attention. Neuropeptides, as a crucial component of neuro-immune crosstalk with local neuroendocrine and signaling functions, play a significant role that must not be overlooked. Neuropeptides are released by neurons and even some immune cells, and mediate neuro-immune crosstalk by activating relevant specific receptors on immune cells. Recent studies have found that neuropeptides have a certain regulatory effect on allergic diseases, which could be beneficial or detrimental for the development of allergic diseases. Nevertheless, the precise mechanism of neuropeptides in allergic diseases remains unclear, particularly in the context of food allergy where their role is poorly understood. This review summarized the interplay between neuropeptides and different immune cells, as well as their current research progress in several common allergic diseases: atopic dermatitis, allergic asthma, and food allergy. It is evident that neuropeptides such as substance P, calcitonin gene-related peptide, vasoactive intestinal peptide, and neuromedin U, exert important regulatory effects on allergic diseases, yet further investigation is required to fully elucidate their mechanisms of action, which may contribute to better understanding of the onset and progression of allergic diseases and finding better immunomodulatory strategies.

Environmental and behavioral mitigation strategies for patients with atopic dermatitis

Objective

Herein, we aimed to summarize the evidence-base for these interventions with a focus on the role of specific chemicals in driving AD.

Methods

A narrative review of nonprescription mitigation strategies in AD was conducted.

Results

We identified avoidance strategies for the various routes of exposure such as air pollution, water contamination, or inclusion in home goods, skin care products, and cleansers. Evidence for and against dietary modification and emollient use as primary prevention were also elucidated. To remember these interventions we propose a mnemonic, HELPSS AD: Home decor, Emollients, Laundering, Probiotics, Soaks, Social support, Air quality, and Diet.

Limitations

Each of these categories presents nuanced molecular differences that must be considered. For example, probiotic responses vary by the specific species while home products and pollution must be analyzed by the specific toxins.

Conclusion

Although the interventions discussed lack the level of evidence required for inclusion into formal guidelines, awareness of these approaches may offer aid to, and build trust with, patients and caregivers.

The Role of Neuro-Immune Interactions in the Pathology and Pathogenesis of Allergic Rhinitis

BACKGROUND

Allergic rhinitis (AR) is a non-infectious inflammatory disease of the nasal mucosa mediated by IgE and involving a variety of immune cells such as mast cells. In previous studies, AR was considered as an isolated disease of the immune system. However, recent studies have found that the nervous system is closely related to the development of AR. Bidirectional communication between the nervous and immune systems plays an important role in AR.

SUMMARY

The nervous system and immune system depend on the anatomical relationship between nerve fibers and immune cells, as well as various neurotransmitters, cytokines, inflammatory mediators, etc. to produce bidirectional connections, which affect the development of AR.

KEY MESSAGES

This article reviews the impact of neuro-immune interactions in AR on the development of AR, including neuro-immune cell units.

Allergic Diseases and Mental Health

Neuropsychiatric symptoms have long been acknowledged as a common comorbidity for individuals with allergic diseases. The proposed mechanisms for this relationship vary by disease and patient population and may include neuroinflammation and/or the consequent social implications of disease symptoms and management. We review connections between mental health and allergic rhinitis, atopic dermatitis, asthma, vocal cord dysfunction, urticaria, and food allergy. Many uncertainties remain and warrant further research, particularly with regard to how medications interact with pathophysiologic mechanisms of allergic disease in the neuroimmune axis. Proactive screening for mental health challenges, using tools such as the Patient Health Questionnaire and Generalized Anxiety Disorder screening instruments among others, can aid clinicians in identifying patients who may need further psychiatric evaluation and support. Although convenient, symptom screening tools are limited by variable sensitivity and specificity and therefore require healthcare professionals to remain vigilant for other mental health "red flags." Ultimately, understanding the connection between allergic disease and mental health empowers clinicians to both anticipate and serve the diverse physical and mental health needs of their patient populations.

Effects of nasal allergens and environmental particulate matter on brainstem metabolites and the consequence of brain-spleen axis in allergic rhinitis

BACKGROUND

The growing consensus links exposure to fine particulate matter (PM2.5) with an increased risk of respiratory diseases. However, little is known about the additional effects of particulate matter on brainstem function in allergic rhinitis (AR). Furthermore, it is unknown to what extent the PM2.5-induced effects in the brainstem affect the inflammatory response in AR. This study aimed to determine the effects, mechanisms and consequences of brainstem neural activity altered by allergenic stimulation and PM2.5 exposure.

METHODS

Using an AR model of ovalbumin (OVA) elicitation and whole-body PM2.5 exposure, the metabolic profile of the brainstem post-allergen stimulation was characterized through in vivo proton magnetic resonance imaging (1H-MRS). Then, the transient receptor potential vanilloid-1 (TRPV1) neuronal expression and sensitivity in the trigeminal nerve in AR were investigated. The link between TRPV1 expression and brainstem differential metabolites was also determined. Finally, we evaluated the mediating effects of brainstem metabolites and the consequences in the brain-spleen axis in the inflammatory response of AR.

RESULTS

Exposure to allergens and PM2.5 led to changes in the metabolic profiles of the brainstem, particularly affecting levels of glutamine (Gln) and glutamate (Glu). This exposure also increased the expression and sensitivity of TRPV1+ neurons in the trigeminal nerve, with the levels of TRPV1 expression closely linked to the brainstem metabolism of Glu and Gln. Moreover, allergens increased the activity of p38, while PM2.5 led to the phosphorylation of p38 and ERK, resulting in the upregulation of TRPV1 expression. The brainstem metabolites Glu and Gln were found to partially mediate the impact of TRPV1 on AR inflammation, which was supported by the presence of pro-inflammatory changes in the brain-spleen axis.

CONCLUSION

Brainstem metabolites are altered under allergen stimulation and additional PM2.5 exposure in AR via sensitization of the trigeminal nerve, which exacerbates the inflammatory response via the brain-splenic axis.

Omalizumab in combination with subcutaneous immunotherapy for the treatment of multiple allergies associated with attention-deficit/hyperactivity disorder: a case report and a literature review

We describe the case of a 10-year-old boy with asthma (AS), accompanied by allergic rhinitis (AR), food allergy (FA), and combined attention-deficit/hyperactivity disorder (ADHD), who was treated at Shanghai Renji Hospital on 11 July 2020. The efficiency of the previous treatment with salmeterol/ticlosone was poor. Treatment with montelukast sodium resulted in development of neurological symptoms. Treatment with omalizumab in combination with subcutaneous immunotherapy (SCIT) was then initiated in our department based on anti-asthmatic therapy. Symptoms of asthma were completely controlled, and FA and AR symptoms improved. The treatment regimen led to a significant improvement in ADHD symptoms and the overall quality of life of the patient. The literature search was done in the PubMed database using "attention deficit/hyperactivity disorder/ADHD" and "asthma" as keywords, and we identified 47 relevant articles. In conclusion, our results show that treating asthma with omalizumab in combination with salmeterol/ticlosone and SCIT is efficient in controlling symptoms of multiple allergies and may lead to the improvement in ADHD symptoms and the overall quality of life of pediatric patients with ADHD. While current studies suggest that allergic diseases are closely related to ADHD, there is still a lack of studies or case reports of complete treatment protocols to provide clinical clues for management of the disease.

Up-regulation of systemic and local BDNF in non-allergic Nasal Polyps in China

Objective

Although the role of brain-derived neurotrophic factor (BDNF) in allergic rhinitis and/or nasal polyps (NPs) development has been studied, the contribution of BDNF in non-allergic NPs has not been evaluated yet. This study was to investigate the possible role of BDNF in non-allergic NPs pathogenesis.

Methods

The study was carried out at The Second Hospital of Shandong University from December 2020 to November 2021. The non-allergic NPs patients (n=26) and the control group (n=22) were included. Lund-Mackay CT scores, nasal endoscopy scores, and pulmonary function testing were evaluated before surgery. Tissue and serum levels of BDNF, eosinophil cationic protein (ECP), and cytokeratins 5 (CK5) were assessed between different groups.

Result

The BDNF level in serum and tissue, CK5 count, and eosinophil infiltration in tissue were higher in non-allergic NPs. The eosinophils infiltration, ECP mRNA expression level, as well as BDNF mRNA level were increased in the BDNFhigh subgroup compared with BDNFlow subgroup. Significantly negative correlations between BDNF count and the situation of airway obstruction were found in non-allergic NPs.

Conclusion

BDNF may have both local and systemic effects in non-allergic NPs pathogenesis. BDNF may be a possible therapeutic target or an indicator for eosinophilic NPs management.

Endoscopic vidian and vidian-branch neurectomy for refractory allergic rhinitis: A systematic review

BACKGROUND

Endoscopic vidian neurectomy is expected to provide good therapeutic relief in patients with allergic rhinitis (AR) being refractory to medication therapy or conservative surgery. However, the evidence bases for its benefit remain debatable. In this study, we conducted a systematic review and meta-analysis to clarify the therapeutic role of various forms of vidian neurectomy in refractory AR.

METHOD

Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines were used to conduct a systematic review of primary studies that reported original patient data for endoscopic vidian neurectomy (EVN) and vidian-branch neurectomy, which includes selective vidian neurectomy (SVN) and posterior nasal neurectomy (PNN). The primary outcome was patient-reported outcome measures (PROMs), including the Rhinoconjunctivitis Quality of Life Questionnaire (RQLQ) and Visual Analog Scale (VAS), to assess an improvement in nasal symptom severity and quality of patient's life. The incidence of surgical complications and other objective outcomes were considered secondary outcomes.

RESULTS

This review included 24 clinical studies involving 1677 patients with refractory AR, of which 510 patients in six studies had combined chronic rhinosinusitis with nasal polyps (CRSwNP) and 95 patients in one study had combined asthma. Postoperative PROMs were significantly better than preoperatively in almost all patients who underwent vidianp (RQLQ: standardized mean difference [SMD] = 2.66, 95% confidence interval [CI] = 2.40-2.92, p < 0.001; VAS: SMD = 5.15, 95% CI = 4.29-6.02, p < 0.001) or vidian-branch neurectomy (RQLQ in PNN: SMD = 3.29, 95% CI = 2.45-4.13, p < 0.001; VAS in PNN: SMD = 4.38, 95% CI = 3.41-5.34, p < 0.001), and were generally better than in the conservative treatment group. Dividing with 18 months as the cutoff point, a subgroup analysis of the follow-up period was conducted, and the results showed that both long-term and short-term postoperative patients had considerably reduced symptoms compared to the preoperative period. The two surgical procedures, SVN and PNN, attributed to vidian-branch neurectomy have extremely few complications. However, EVN is more likely to cause dry eyes and palatal numbness, with no other serious complications. In patients with AR and CRSwNP, vidian or selective vidian neurectomy combined with functional endoscopic sinus surgery (FESS) is more effective than conventional FESS (RQLQ: SMD = 2.17, 95% CI = 1.66-2.69, p < 0.001; VAS: SMD = 6.42, 95% CI = 4.78-8.06, p < 0.001). For patients who have both AR and asthma, SVN with pharyngeal branch excision is a potential treatment option.

CONCLUSION

EVN and vidian-branch neurectomy (including SVN and PNN) are effective treatments, but the former has a higher risk of complications. Additionally, vidian-branch neurectomy with FESS is beneficial for patients with mixed CRSwNP. SVN is a potential approach for patients with coexisting AR and asthma.

Neuroimmune communication in allergic rhinitis

The prevalence rate of allergic rhinitis (AR) is high worldwide. The inhalation of allergens induces AR, which is an immunoglobulin E-mediated and type 2 inflammation-driven disease. Recently, the role of neuroimmune communication in AR pathogenesis has piqued the interest of the scientific community. Various neuropeptides, such as substance P (SP), vasoactive intestinal peptide (VIP), calcitonin gene-related peptide (CGRP), nerve growth factor (NGF), and neuromedin U (NMU), released via "axon reflexes" or "central sensitization" exert regulatory effects on immune cells to elicit "neurogenic inflammation," which contributes to nasal hyperresponsiveness (NHR) in AR. Additionally, neuropeptides can be produced in immune cells. The frequent colocalization of immune and neuronal cells at certain anatomical regions promotes the establishment of neuroimmune cell units, such as nerve-mast cells, nerve-type 2 innate lymphoid cells (ILC2s), nerve-eosinophils and nerve-basophils units. Receptors expressed both on immune cells and neurons, such as TRPV1, TRPA1, and Mas-related G protein-coupled receptor X2 (MRGPRX2) mediate AR pathogenesis. This review focused on elucidating the mechanisms underlying neuroimmune communication in AR.

Topical Corticosteroid Phobia Among Parents of Children with Atopic Dermatitis (Eczema)- A Cross-Sectional Study

Background

Anxiety about using topical corticosteroids (TCS) for childrens among parents and caretakers is a common cause of treatment failure and an overall decline in the child's quality of life. The purpose of this study was to examine the perspectives and worries of parents of Atopic dermatitis (AD) children regarding TCS. Additionally, we investigate the degree of phobia in relation to the use of the TCS.

Materials and Methods

A convenience sample of 301 parents of children who had been identified with atopic dermatitis from two hospitals in Taif city were enrolled in this study. Parents who chose to participate were sent a questionnaire measuring their level of fear of TCS using the TOPICOP© scale, which also included inquiries about their demographics and clinical characteristics. Multivariate analysis was used to determine what factors influence people's overall levels of fear.

Results

The median global TOPICOP score was 66.6% (IQR 60.4-75%), SD 12.83%, which showed that nearly two-thirds of the participants showed corticosteroid phobia. A multifactorial ANOVA model showed that parents who had a female child with AD and mothers who had experienced drug allergies had a significant influence on TOPICOP scores (P<0.05).

Conclusion

Topical corticosteroid phobia is widespread among parents of children patients with AD in Taif. Regarding the utilization of TCS, we place a strong emphasis on the significant role that physicians play as sources of reliable information and proper education.

Understanding food allergy through neuroimmune interactions in the gastrointestinal tract

Food allergies are adverse immune reactions to food proteins in the absence of oral tolerance, and the incidence of allergies to food, including peanut, cow's milk, and shellfish, has been increasing globally. Although advancements have been made toward understanding the contributions of the type 2 immune response to allergic sensitization, crosstalk between these immune cells and neurons of the enteric nervous system is an area of emerging interest in the pathophysiology of food allergy, given the close proximity of neuronal cells of the enteric nervous system and type 2 effector cells, including eosinophils and mast cells. At mucosal sites, such as the gastrointestinal tract, neuroimmune interactions contribute to the sensing and response to danger signals from the epithelial barrier. This communication is bidirectional, as immune cells express receptors for neuropeptides and transmitters, and neurons express cytokine receptors, allowing for the detection of and response to inflammatory insults. In addition, it seems that neuromodulation of immune cells including mast cells, eosinophils, and innate lymphoid cells is critical for amplification of the type 2 allergic immune response. As such, neuroimmune interactions may be critical targets for future food allergy therapies. This review evaluates the contributions of local enteric neuroimmune interactions to the underlying immune response in food allergy and discusses considerations for future investigations into targeting neuroimmune pathways for treatment of food allergies.

Type 2 chronic inflammatory diseases: targets, therapies and unmet needs

Over the past two decades, significant progress in understanding of the pathogenesis of type 2 chronic inflammatory diseases has enabled the identification of compounds for more than 20 novel targets, which are approved or at various stages of development, finally facilitating a more targeted approach for the treatment of these disorders. Most of these newly identified pathogenic drivers of type 2 inflammation and their corresponding treatments are related to mast cells, eosinophils, T cells, B cells, epithelial cells and sensory nerves. Epithelial barrier defects and dysbiotic microbiomes represent exciting future drug targets for chronic type 2 inflammatory conditions. Here, we review common targets, current treatments and emerging therapies for the treatment of five major type 2 chronic inflammatory diseases - atopic dermatitis, chronic prurigo, chronic urticaria, asthma and chronic rhinosinusitis with nasal polyps - with a high need for targeted therapies. Unmet needs and future directions in the field are discussed.

Fc Epsilon RI-Neuroimmune Interplay in Pruritus Triggered by Particulate Matter in Atopic Dermatitis Patients

Atopic dermatitis (AD) is the most common chronic relapsing neuroinflammatory skin disease that is characterized by a complex and multifactorial pathophysiology. It reflects a profound interplay between genetic and environmental factors, and a recently disclosed neuroimmune dysregulation that drives skin barrier disruption, pruritus, and microbial imbalance. In terms of the key external environmental players that impact AD, air quality and itch severity linkage have been thoroughly researched. The impact of ambient air pollutants including particulate matter (PM) and AD pruritic exacerbation has been recorded despite reductions in air pollution levels in in developed countries. The developing countries have, on the contrary, experienced significant urbanization and industrialization with limited environmental protection standards in the past decades. This unprecedented construction, petrochemical industry utilization, and increment in population counts has been paired with consistent exposure to outdoor PM. This may present a key cause of AD pruritic exacerbation supported by the fact that AD prevalence has intensified globally in the past 50 years, indicating that environmental exposure may act as a trigger that could flare up itch in vulnerable persons. At the molecular level, the impact of PM on severe pruritus in AD could be interpreted by the toxic effects on the complex neuroimmune pathways that govern this disease. AD has been recently viewed as a manifestation of the disruption of both the immune and neurological systems. In light of these facts, this current review aims to introduce the basic concepts of itch sensory circuits in the neuroimmune system. In addition, it describes the impact of PM on the potential neuroimmune pathways in AD pathogenesis with a special focus on the Fc Epsilon RI pathway. Finally, the review proposes potential treatment lines that could be targeted to alleviate pruritus based on immune mediators involved in the Fc Epsilon signaling map.

Basophils in pruritic skin diseases

Basophils are rare cells in the peripheral blood which have the capability to infiltrate into the skin. Invasion of basophils has been detected in pruritic skin diseases, including atopic dermatitis, bullous pemphigoid, chronic spontaneous urticaria and contact dermatitis. In the skin, basophils are important players of the inflammatory immune response, as they release Th2 cytokines, including interleukin (IL)-4 and IL-13, subsequently inducing the early activation of T-cells. Further, basophils release a multitude of mediators, such as histamine and IL-31, which both play an important role in the initiation of the pruritic response via activation of sensory nerves. Chronic pruritus significantly affects the quality of life and the working capability of patients, though its mechanisms are not fully elucidated yet. Since basophils and neurons share many receptors and channels, bidirectional interaction mechanisms, which drive the sensation of itch, are highlighted in this review.

Neuro-Immuno-Psychological Aspects of Chronic Urticaria

Urticaria is a condition characterized by the development of itchy wheals (hives), angioedema, or both. The pathophysiology of chronic spontaneous urticaria (CSU) is still poorly understood. It is suggested that there is no dominant and independent mechanism of CSU; however, there are different immunological and non-immunological abnormalities that act simultaneously or/and follow each other resulting in clinical symptoms. The latest hypothesis points out that mast cells (MCs) to be activated via autoantibodies in autoallergic or autoimmune mechanism mediators released from degranulated MCs are responsible for the vasoactive and neurospecific effect in CSU. According to many clinical observations, it is suggested that psychological stress can be both a triggering factor in the onset of CSU and a modulating one in the course of the disease and therapy effectiveness. Of importance, the mechanistic background of the psychological stress response in the skin has not yet been fully elucidated. However, of note, a variety of inflammatory mediators, neuropeptides, and neurotransmitters facilitate this phenomenon. This review presents recent findings on the neuro-immuno-psychological aspects of CSU, highlighting an emerging role of neuro-immune interactions. It also points out the usefulness of psychological tools employment for the baseline diagnosis of perceived stress level and the presence of its symptoms. Furthermore, it proposes the implementation of non-invasive interventions to reduce psychological stress and anxiety. A bio-psycho-social approach including psychological support and patient education seems to be as important as traditional pharmacotherapy for CSU. It facilitates the effective control of active disease and a prolonged remission time in this disease.

Psychiatric comorbidities in children and adolescents with chronic urticaria

BACKGROUND

Chronic urticaria (CU) has been shown to impact patients' quality of life negatively and may coexist with psychiatric disorders. We systematically reviewed the published evidence of comorbid psychiatric disorders in children and adolescents with CU.

METHODS

A systematic review of studies published until February 2022 in PubMed, Google Scholar, and Scopus was performed. An a priori set of inclusion criteria was predefined for the studies to be included: (1) clear distinction between urticaria and other allergies; (2) precise distinction between acute and CU; (3) participants younger than 18 years old, exclusively; (4) use of appropriate standardized questionnaires, psychometric tools, and standard diagnostic nomenclature for the mental health and behavioral disorders diagnosis; and (5) manuscripts written or published in the English language.

RESULTS

Our search identified 582 potentially relevant papers. Only eight of them satisfied the inclusion criteria. Quantitative meta-analysis was not deemed appropriate, given the lack of relevant randomized control trials, the small number of relevant shortlisted, the small sample size of the patients included in each study, and the remarkable heterogeneity of the studies' protocols.

CONCLUSIONS

The included studies suggest an increased incidence of psychopathology among children and adolescents with CU as opposed to healthy age-matched individuals, but the data are scarce. Further research is required to clarify whether psychopathology is just a comorbid entity, the cause, or the consequence of CU. Meanwhile an interdisciplinary collaboration between allergists/dermatologists and psychiatrists is expected to substantially minimize CU burden and improve patients' quality of life.