The SP-TLR axis, which locally primes the nasal mucosa, is impeded in patients with allergic rhinitis

Recent advances in the molecular signaling pathways of Substance P in Alzheimer's disease: Link to neuroinflammation associated with toll-like receptors

A significant quantity of substance P (SP) and its receptor, the neurokinin 1 (NK1) receptors are found in the brain. SP is a neuropeptide distributed in the central nervous system and functions as a neurotransmitter, neuromodulator, and neurotrophic factor. The concentrations of SP in the brain and cerebrospinal fluid fluctuate in individuals with Alzheimer's disease (AD). SP is an endogenous ligand for NK1 receptor, enhancing the expression of toll-like receptors (TLR) and vice versa. So, both pathways are interconnected, where activation of one pathway activates the second pathway. Researchers have observed the interaction of TLR with SP in the pathophysiology of AD. Thus, this review discusses various TLRs involved in regulating amyloid processing and its interaction with SP in AD. Further, in AD pathology, SP can regulate the non-amyloidogenic pathway. Recent studies have also demonstrated the capacity of SP in regulating voltage-gated potassium channel currents, emphasizing SP's neuroprotective ability. Therefore, we corroborate the findings linking the SP, NK1R, and TLRs in AD.

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.

The Assessment of TLR1 Gene Polymorphism Association with the Risk of Allergic Rhinitis in the Chinese Han Population from Northern China

Background

Environmental factors and genetic predisposition can influence the occurrence and development of AR. Toll-like receptor 1 (TLR1) belongs to the TLR receptor family, which plays a fundamental role in the activation of innate immunity. This study aimed to explore the association between TLR1 genetic loci and AR susceptibility in the Han Chinese from northern China.

Methods

Genotyping of three SNPs in the TLR1 has proceeded using the Agena MassARRAY platform. Odds ratio (OR) and 95% confidence interval (CI) were used to assess the correlation between candidate SNPs and AR susceptibility. Using FPRP (false-positive report probability analysis) to detect whether the positive results are noteworthy findings. The SNP-SNP interactions were detected by multifactor dimensionality reduction (MDR).

Results

TLR1-rs72493538 (Allele "G": OR=0.77, p = 0.034) and -rs76600635 (Allele "G": OR=0.75, p = 0.024) were associated with reducing the risk of AR among Han Chinese in northern China. In addition, we found evidence that TLR1-rs72493538 (males, participants with aging > 43 years, or coming from the wind-blown sand region) and -rs76600635 (males, participants with BMI ≤ 24 kg/m2, or coming from the wind-blown sand region) were associated with AR risk in stratified analyses. FPRP showed that all positive results are noteworthy findings. MDR analysis showed that a two-loci genetic model composed of rs72493538 and rs76600635 can be chosen as the best genetic model to predict the risk of AR.

Conclusion

TLR1-rs72493538 and -rs76600635 have a close association with reducing the risk of AR.

Prolonged inflammatory resolution in allergic asthma relates to dysfunctional interactions between neutrophils and airway epithelium

BACKGROUND

Allergic asthma is a heterogeneous disorder involving chronic airway inflammation, reversible airflow limitation, and tissue remodeling, causing chronic airflow limitation. Most of the asthma research has been focused on elucidating the proinflammatory pathways underlying disease pathogenesis. Paradoxically, the necessity of appropriate termination and resolution of inflammation has not been recognized until recently. The latter has led to the concept of chronic inflammation developing as a result of lack of specific "stop" signals for the inflammatory process.

OBJECTIVE

To investigate the interaction between neutrophils and airway epithelium during inflammatory resolution in patients with allergic asthma.

METHODS

An in vitro scratch assay with cultured epithelial cells, based on live-imaging microscopy, was used to evaluate regeneration and the influence of neutrophils on resolution. Epithelial cells and autologous neutrophils were derived from healthy donors and patients with allergic asthma. Supernatants and cells were collected for enzyme-linked immunosorbent assay and transcriptional analyses at the end of the experiment.

RESULTS

Healthy epithelial cells regenerated faster than epithelial cells from patients with allergic asthma. Autologous neutrophils improved the regeneration of healthy epithelial cells but not asthmatic epithelial cells. Interleukin (IL)-8 and β-catenin were down-regulated in healthy epithelial cells after resolution, but not in allergic asthmatic epithelial cells.

CONCLUSION

The prolonged duration of inflammation in the respiratory tract in patients with allergic asthma could be due to the impaired healing pattern of epithelial cells and their compromised interactions with the neutrophils.

Pathogenesis of chronic rhinosinusitis with nasal polyp and a prominent T2 endotype

Chronic rhinosinusitis is a heterogenous and multifactorial disease, characterized by persistent inflammation of the nose and paranasal sinuses, which causes nasal obstruction, nasal discharge, facial pain, and smell disturbance. Chronic rhinosinusitis is divided into two phenotypes: chronic rhinosinusitis with nasal polyp and chronic rhinosinusitis without nasal polyp. Nasal polyps can be associated with many inflammatory cells including eosinophil cells, neutrophil cells, plasma cells, and lymphocytes. T2 endotype is characterized by the type-2 immune response and nasal polyps are associated with eosinophilic dominant infiltration. In contrast, in the T1 and T3 endotypes, chronic rhinosinusitis can be associated with neutrophilic dominant infiltration. In addition, there are mixed types of inflammation with different proportions of eosinophils-neutrophils in chronic rhinosinusitis. In the T2 endotype, there is an increase in the production of Th2 cytokines, including interleukin-4, interleukin-5, and interleukin-13, high levels of immunoglobulin-E in polyp tissue, and eosinophilia. Stimulation of Th2 cells, type-2 innate lymphoid cells, epithelial cell damage, Staphylococcus aureus enterotoxins, and autoimmune antibodies have important roles in the enhancement of Th2 cytokines and pathogenesis of chronic rhinosinusitis with nasal polyp. Monoclonal antibodies target type-2 inflammation, decrease nasal polyp size, and improve the clinical symptoms of CRSwNP patients. The present review will focus on factors involved in the pathogenesis of chronic rhinosinusitis and its treatment.

Notch2 suppresses the development of allergic rhinitis by promoting FOXP3 expression and Treg cell differentiation

AIMS

Notch signaling is closely related to a variety of diseases, but the role of Notch2 in allergic rhinitis (AR) remain unclear. This study was performed to investigate the effects of Notch2 on the differentiation of Treg cells and on the inflammatory response of AR.

MATERIALS AND METHODS

Peripheral blood (including 101 AR patients and 66 Controls) and nasal mucosa (including 19 AR patients and 17 Controls) were collected to detect the expression levels of Notch2, NICD2 and FOXP3. CD4+ T cells of human origin were selected to detect the effects of Notch2 on the differentiation of Treg cells and FOXP3. An AR mouse model was established, and lentiviruses overexpressing Notch2 were administered. Then, allergic symptoms, OVA-sIgE titers, nasal mucosal inflammation, Th1/Th2/Th17 cytokines and splenic Treg cells were assessed.

KEY FINDINGS

Compared with that in the Control group, the expression of Notch2 in the AR group was decreased, and Notch2 expression was negatively correlated with the degree of allergy (P < 0.01). The expression levels of Notch2, NICD2 and FOXP3 were decreased in the nasal mucosa of AR patients. Notch2 can promote the differentiation of human Treg cells in vitro (P < 0.05), and Notch2 can directly promote FOXP3 transcription. Animal experiments showed after the upregulation of Notch2 expression, the allergic inflammatory of mice with AR was reduced, the differentiation of Treg cells was increased, and the imbalance of T cells was reversed (P < 0.05).

SIGNIFICANCE

Notch2 promotes the differentiation of Treg cells by upregulating FOXP3 expression, thus significantly inhibiting the inflammatory response of AR.