Naso-ocular neuropeptide interactions in allergic rhinoconjunctivitis, rhinitis, and conjunctivitis

The airway neuro-immune axis as a therapeutic target in allergic airway diseases

Recent evidence has increasingly underscored the importance of the neuro-immune axis in mediating allergic airway diseases, such as allergic asthma and allergic rhinitis. The intimate spatial relationship between neurons and immune cells suggests that their interactions play a pivotal role in regulating allergic airway inflammation. Upon direct activation by allergens, neurons and immune cells engage in interactions, during which neurotransmitters and neuropeptides released by neurons modulate immune cell activity. Meanwhile, immune cells release inflammatory mediators such as histamine and cytokines, stimulating neurons and amplifying neuropeptide production, thereby exacerbating allergic inflammation. The dynamic interplay between the nervous and immune systems suggests that targeting the neuro-immune axis in the airway could represent a novel approach to treating allergic airway diseases. This review summarized recent evidence on the nervous system's regulatory mechanisms in immune responses and identified potential therapeutic targets along the peripheral nerve-immune axis for allergic asthma and allergic rhinitis. The findings will provide novel perspectives on the management of allergic airway diseases in the future.

A Review on Novel Therapeutic Modalities and Evidence-based Drug Treatments against Allergic Rhinitis

Allergic rhinitis (AR) is an IgE-mediated atopic disease that occurs due to inhaled antigens in the immediate phase. Misdiagnosis, insufficient treatment, or no treatment at all are frequent problems associated with the widespread condition known as chronic allergic rhinitis. AR symptoms include runny, itchy, stuffy, and sneezing noses. Asthma and nasal polyps, for example, sometimes occur simultaneously in patients. In order for people living with AR to be as comfortable and productive as possible, treatment should center on reducing their symptoms. The online sources and literature, such as Pubmed, ScienceDirect, and Medline, were reviewed to gather information regarding therapeutic modalities of AR and evidence-based treatments for the disease as the objectives of the present study. An increasing number of people are suffering from AR, resulting in a heavy financial and medical burden on healthcare systems around the world. Undertreating AR frequently results in a decline in quality of life. Treatment compliance is a critical challenge in the administration of AR. Innovative therapies are needed for RA to provide patients with symptom alleviation that is less expensive, more effective, and longer duration of action. Evidence-based guidelines are helpful for managing AR illness. Treating AR according to evidence-based standards can help in disease management. AR treatment includes allergen avoidance, drug therapy, immunotherapy, patient education, and follow-up. However, AR treatment with intranasal corticosteroids is more popular. Hence, in this review article, treatment options for AR are discussed in depth. We also discussed the incidence, causes, and new treatments for this clinical condition.

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.

[Neuroimmunology of allergic rhinitis : Part 1: Cellular and humoral basic principles]

Allergic rhinitis (AR) is a very common disease with a high prevalence worldwide. It is an IgE-mediated type 2 inflammatory disease following exposure to inhalant allergens. A multitude of different neuropeptides including substance P, vasoactive intestinal peptide (VIP), calcitonin gene-related peptide (CGRP), nerve growth factor (NGF), and neuromedin U (NMU) can be released via peripheral axon or central reflexes, interact with immune cells, and thus contribute to neurogenic inflammation which causes the nasal hyperreactivity (NHR) characteristic of AR. Independent production of neuroendocrine hormones and neuropeptides by immune cells has also been demonstrated. Neuro-immune cell units arise when immune and neuronal cells colocalize, for which typical anatomic regions are, e.g., the mast cell-nerve functional unit. The focus of this review is the elucidation of neuroimmune communication mechanisms in AR.

A novel and alternative therapy for persistent allergic rhinitis via intranasal acupuncture: a randomized controlled trial

BACKGROUND

Acupuncture is used to treat allergic rhinitis (AR) in traditional Chinese medicine, and the ST2 and ST36 acupoints are generally selected in clinical practice. We report a new intranasal acupuncture method at the Neiyingxiang (EX-HN9) and Biqiu points for the treatment of persistent AR (PAR). Here, the efficacy and safety of this method were evaluated.

METHODS

A total of 120 patients diagnosed with PAR were randomly allocated (2:1 ratio) to intranasal acupuncture or Western medicine groups, the basic principle of random grouping is SAS random grouping method. The applicator held a nasal endoscope and a 0.30 × 75 mm filiform needle in their left and right hands, respectively. When aiming at the Neiyingxiang or Biqiu point, the applicator quickly inserted the needle to a 20-mm depth as parallel as possible to the inferior turbinate or middle turbinate, without special reinforcing and reducing techniques (the needle remained for 20 min). The intranasal acupuncture groups received acupuncture treatment three times per week for 2 weeks. The Western medicine group was treated with budesonide nasal spray (two sprays/nostril, twice/day) and loratadine (one tablet/night) for 2 weeks. Visual analog scale (VAS) scores were the primary outcome. Quality of life, medication dosages and adverse events were secondary outcomes measured using the Rhinoconjunctivitis Quality-of-Life Questionnaire (RQLQ). Confidence assessments were performed to evaluate data from the treatment and follow-up periods.

RESULTS

The results were as follows: (1) VAS and RQLQ scores were significantly lower in the intranasal acupuncture group than in the Western medicine group on day 1 (i.e., first treatment) (P < 0.05; 95% CI - 13.1 to - 9.6 VAS points) (P < 0.05; 95% CI - 20.27 to - 12.28 RQLQ points). Overall symptoms (95% CI - 2.86 to - 1.86 points), nasal obstruction (95% CI - 6.33 to - 5.36 points), olfactory function (95% CI - 2.91 to - 1.75 points), sleep (95% CI - 5.05 to - 3.57 points), actual problems (95% CI - 2.03 to - 0.06 points), nasal symptoms (95% CI - 6.62 to - 4.5 points), and emotional problems (95% CI - 5.05 to - 3.5 points) were significantly improved. (2) VAS and RQLQ scores in the two groups were significantly improved at week 2; however, there were no significant group differences in the VAS (P > 0.05; 95% CI - 1.21 to - 1.38 points) and RQLQ (P > 0.05; 95% CI - 0.33 to - 3.46 points) scores. Olfactory function symptoms were significantly improved (95% CI - 1.58 to - 0.21 points). (3) During the follow-up period, there was a significant difference between the two groups (P < 0.05) with higher RQLQ and VAS scores in the intranasal acupuncture group than in the Western medicine group. VAS scores on rhinobyon symptoms, nasal itch, rhinorrhea and olfactory function and RQLQ scores for activities, non-nasal/eye symptoms, actual problems, nasal symptoms, and eye symptoms were significantly improved. (4) No adverse events were observed in either group during treatment.

CONCLUSIONS

Intranasal acupuncture has good efficacy and safety in the treatment of PAR. Moreover, VAS and RQLQ scores were much lower in the intranasal acupuncture group than in the Western medicine group, and acupuncture had an immediate impact, especially for improving nasal congestion, olfactory function and sleep.

Substance P promotes immunotherapy efficacy for airway allergy

Background

Allergen-specific immunotherapy (AIT) has been employed in the treatment of allergic diseases for many years. However, the effectiveness of AIT requires improvement. Substance P (SP) can interact with immune cells, modulate immune cell activity, and regulate immune reaction. The purpose of this study is to use SP as an immune regulator to enhance the therapeutic efficacy of AIT.

Methods

An established mouse model of the airway allergy disorder (AAD) was employed with ovalbumin as a specific antigen. The AAD response was evaluated through established procedures. AAD mice were treated with AIT employing SP as an immune regulator. Dendritic cells were isolated from the airway tissues by magnetic cell sorting, and were analyzed by RNA sequencing (RNAseq).

Results

We observed that after sensitization with ovalbumin, mice exhibited AAD-like symptoms, serum specific IgE, and Th2 polarization. The presence of SP in the course of sensitization prevented the development of AAD. Treating mice with SP by nasal instillations induced IL-10, but not TGF-β, in dendritic cells of the airway tissues. The most differentially expressed genes (DEG) in the dendritic cells were those related to the IL-10 expression, including Il10, Tac1r, and Mtor. The gene ontology analysis showed that these DEGs mainly mapped to the tachykinin-PI3K-AKT-mTOR pathway. The addition of SP substantially enhanced the therapeutic efficacy of AIT for AAD by inducing antigen specific type 1 regulatory T cells (Tr1 cells).

Conclusion

Acting as an immune regulator, SP promotes the therapeutic efficacy for AAD by inducing antigen specific Tr1 cells in the airway tissues.

The Objective Assessment of dry Nose

Background

Dry nose (DN) is a common symptom in both patients with rhinitis and healthy individuals; however, it is often overlooked.

Objective

This study aimed to investigate the characteristics of and propose objective diagnostic criteria for DN.

Methods

This study was conducted from December, 2018 to October, 2021. Patients with complaints of a dry nasal cavity and normal controls were recruited consecutively from the allergy-rhinology outpatient clinic of Beijing TongRen Hospital. Questionnaires were completed by each participant during recruitment to record demographic data. DN test strips were used to evaluate the severity of DN. The length of the strip was recorded at 30 s, 1 min, 2 min, 3 min, 4 min, and 5 min, respectively. Nasal secretions were collected on sponges and allergic status was assessed based on serum sage levels.

Results

Twenty (13 men and 7 women) patients with DN and 100 (47 men and 53 women) controls were recruited for the study. The participants’ ages ranged from 23 to 73 years (mean  =  47.7 years). Nine of the 20 DN patients were diagnosed with vasomotor rhinitis. The weight of the sponges of DN patients was significantly lower than that of controls. At the last time point (5 min), the strips in the control group were significantly longer than those in the DN group. The reference range of 30 s, 1 min, 2 min, 3 min, 4 min, and 5 min of controls was 3.0 mm, 6.0 mm, 10.9 mm, 13.2 mm, 16.8 mm, and 17.0 mm, respectively.

Conclusions

Our study indicated that the strip length less than 17.0 mm at 5 min is a valuable reference for the diagnostic of DN in Beijing.

Update on pathomechanisms and treatments in allergic rhinitis

Allergic rhinitis (AR) is a global health problem with increasing prevalence and association with an enormous medical and socioeconomic burden. New recognition of immune cells such as type 2 innate lymphocytes (ILC2s), T helper (Th2) 2 cells, follicular helper T cells, follicular regulatory T cells, regulatory T cells, B cells, dendritic cells, and epithelial cells in AR pathogenesis has been updated in this review paper. An in-depth understanding of the mechanisms underlying AR will aid the identification of biomarkers associated with disease and ultimately provide valuable parameters critical to guide personalized targeted therapy. As the only etiological treatment option for AR, allergen-specific immunotherapy (AIT) has attracted increasing attention, with evidence for effectiveness of AIT recently demonstrated in several randomized controlled trials and long-term real-life studies. The exploration of biologics as therapeutic options has only involved anti-IgE and anti-type 2 inflammatory agents; however, the cost-effectiveness of these agents remains to be elucidated precisely. In the midst of the currently on-going COVID-19 pandemic, a global life-threatening disease, although some studies have indicated that AR is not a risk factor for severity and mortality of COVID-19, this needs to be confirmed in multi-centre, real-life studies of AR patients from different parts of the world.

Tear film and ocular surface neuropeptides: Characteristics, synthesis, signaling and implications for ocular surface and systemic diseases

Ocular surface neuropeptides are vital molecules primarily involved in maintaining ocular surface integrity and homeostasis. They also serve as communication channels between the nervous system and the immune system, maintaining the homeostasis of the ocular surface. Tear film and ocular surface neuropeptides have a role in disease often due to abnormalities in their synthesis (either high or low production), signaling through defective receptors, or both. This creates imbalances in otherwise normal physiological processes. They have been observed to be altered in many ocular surface and systemic diseases including dry eye disease, ocular allergy, keratoconus, LASIK-induced dry eye, pterygium, neurotrophic keratitis, corneal graft rejection, microbial keratitis, headaches and diabetes. This review examines the characteristics of neuropeptides, their synthesis and their signaling through G-protein coupled receptors. The review also explores the types of neuropeptides within the tears and ocular surface, and how they change in ocular and systemic diseases.