Nasal reactivity to capsaicin in patients with seasonal allergic rhinitis during and after the pollen season

Potential of Lactoferrin in the Treatment of Lung Diseases

Lactoferrin (LF) is a multifunctional iron-binding glycoprotein that exhibits a variety of properties, such as immunomodulatory, anti-inflammatory, antimicrobial, and anticancer, that can be used to treat numerous diseases. Lung diseases continue to be the leading cause of death and disability worldwide. Many of the therapies currently used to treat these diseases have limited efficacy or are associated with side effects. Therefore, there is a constant pursuit for new drugs and therapies, and LF is frequently considered a therapeutic agent and/or adjunct to drug-based therapies for the treatment of lung diseases. This article focuses on a review of the existing and most up-to-date literature on the contribution of the beneficial effects of LF on the treatment of lung diseases, including asthma, viral infections, cystic fibrosis, or lung cancer, among others. Although in vitro and in vivo studies indicate significant potency of LF in the treatment of the listed diseases, only in the case of respiratory tract infections do human studies seem to confirm them by demonstrating the effectiveness of LF in reducing episodes of illness and shortening the recovery period. For lung cancer, COVID-19 and sepsis, the reports are conflicting, and for other diseases, there is a paucity of human studies conclusively confirming the beneficial effects of LF.

Nasal Epithelial Barrier Integrity and Tight Junctions Disruption in Allergic Rhinitis: Overview and Pathogenic Insights

Allergic rhinitis (AR) is a common disorder affecting up to 40% of the population worldwide and it usually persists throughout life. Nasal epithelial barrier constitutes the first line of defense against invasion of harmful pathogens or aeroallergens. Cell junctions comprising of tight junctions (TJs), adherens junctions, desmosomes and hemidesmosomes form the nasal epithelial barrier. Impairment of TJ molecules plays causative roles in the pathogenesis of AR. In this review, we describe and discuss the components of TJs and their disruption leading to development of AR, as well as regulation of TJs expression by epigenetic changes, neuro-immune interaction, epithelial-derived cytokines (thymic stromal lymphopoietin, IL-25 and IL-33), T helper 2 (Th2) cytokines (IL-4, IL-5, IL-6 and IL-13) and innate lymphoid cells. These growing evidence support the development of novel therapeutic approaches to restore nasal epithelial TJs expression in AR patients.

A TRiP Through the Roles of Transient Receptor Potential Cation Channels in Type 2 Upper Airway Inflammation

PURPOSE OF REVIEW

Despite their high prevalence, the pathophysiology of allergic rhinitis (AR) and chronic rhinosinusitis (CRS) remains unclear. Recently, transient receptor potential (TRP) cation channels emerged as important players in type 2 upper airway inflammatory disorders. In this review, we aim to discuss known and yet to be explored roles of TRP channels in the pathophysiology of AR and CRS with nasal polyps.

RECENT FINDINGS

TRP channels participate in a plethora of cellular functions and are expressed on T cells, mast cells, respiratory epithelial cells, and sensory neurons of the upper airways. In chronic upper airway inflammation, TRP vanilloid 1 is mostly studied in relation to nasal hyperreactivity. Several other TRP channels such as TRP vanilloid 4, TRP ankyrin 1, TRP melastatin channels, and TRP canonical channels also have important functions, rendering them potential targets for therapy. The role of TRP channels in type 2 inflammatory upper airway diseases is steadily being uncovered and increasingly recognized. Modulation of TRP channels may offer therapeutic perspectives.

Nasal hyperreactivity in rhinitis: A diagnostic and therapeutic challenge

Although nasal hyperreactivity (NHR) is a common feature in patients suffering from allergic and nonallergic rhinitis, it is widely neglected during history taking, underdiagnosed in the majority of patients with rhinitis and rhinosinusitis, not considered as an outcome parameter in clinical trials on novel treatments for rhinitis and rhinosinusitis, and no target for routine treatment. In contrast to the simple nature of diagnosing NHR by a history of nasal symptoms induced by nonspecific exogenous and/or endogenous triggers, quantification is hardly performed in routine clinic given the lack of a simple tool for its diagnosis. So far, limited efforts have been invested into gaining better insight in the underlying pathophysiology of NHR, helping us to explain why some patients with inflammation develop NHR and others not. Of note, environmental and microbial factors have been reported to influence NHR, contributing to the complex nature of understanding the development of NHR. As a consequence of the neglect of NHR as a key clinical feature of rhinitis and chronic rhinosinusitis (CRS), patients with NHR might be suboptimally controlled and/or dissatisfied with current treatment. We here aim to provide a comprehensive overview of current knowledge on the pathophysiology, and the available tools to diagnose and treat NHR.

Sense and Immunity: Context-Dependent Neuro-Immune Interplay

The sensory nervous and immune systems, historically considered autonomous, actually work in concert to promote host defense and tissue homeostasis. These systems interact with each other through a common language of cell surface G protein-coupled receptors and receptor tyrosine kinases as well as cytokines, growth factors, and neuropeptides. While this bidirectional communication is adaptive in many settings, helping protect from danger, it can also become maladaptive and contribute to disease pathophysiology. The fundamental logic of how, where, and when sensory neurons and immune cells contribute to either health or disease remains, however, unclear. Our lab and others’ have begun to explore how this neuro-immune reciprocal dialog contributes to physiological and pathological immune responses and sensory disorders. The cumulative results collected so far indicate that there is an important role for nociceptors (noxious stimulus detecting sensory neurons) in driving immune responses, but that this is highly context dependent. To illustrate this concept, we present our findings in a model of airway inflammation, in which nociceptors seem to have major involvement in type 2 but not type 1 adaptive immunity.

Allergens Induce the Release of Lactoferrin by Neutrophils from Asthmatic Patients

Background

Despite the evidence that Lactoferrin (Lf) is involved in allergic asthma processes, it is unknown whether neutrophils can be one of the main cellular sources of this key inflammatory mediator directly in response of an IgE mediated stimulus. The present study was undertaken to analyze this question.

Methods

Neutrophils from healthy subjects (n = 34) and neutrophils from allergic asthmatic patients (n = 102) were challenged in vitro with specific allergens to which the patients were sensitized, PAF, or agonist mAbs against IgE-receptors, and the levels of Lf were measured in the culture supernatant. The levels of serum IgE together with the severity of symptoms were also analyzed.

Results

Lf was released into the culture supernatant of neutrophils from allergic asthmatic patients in response to allergens and PAF. This response was highly allergen-specific, and did not happen in neutrophils from healthy donors. Allergen effect was mimicked by Abs against FcεRI and galectin-3 but not by FcεRII. The levels of released Lf correlated well with the levels of serum specific IgE and severity of asthma symptoms. These observations represent a novel view of neutrophils as an important source of Lf in allergic asthma. Importantly, the levels of released Lf by neutrophils could therefore be used to evaluate disease severity in allergic asthmatic patients.

Comparative anti-inflammatory properties of Capsaicin and ethyl-aAcetate extract of Capsicum frutescens linn [Solanaceae] in rats

BACKGROUND

The analgesic effect of capsaicin (the active ingredient in Capsicum frutescens Linn. [Solanaceae]) had been reported in several studies. Current research is being directed at producing analgesics, anti-inflammatory agents with better side effect profile.

OBJECTIVES

To investigate if either the ethyl acetate extract of Capsicum frutescens Linn. [Solanaceae] (CFE) or capsaicin (Fluka Biotechnika-CPF) (in addition to the known analgesic properties) has any anti-inflammatory effect comparable to nonsteroidal anti-inflammatory analgesics (NSAIDS).

METHODS

The effects of ethyl acetate extract of Capsicum frutescens Linn. [Solanaceae] (CFE) and capsaicin (Fluka Biotechnika-CPF) was examined on rat hind paw. Inflammation was induced in the rat's hind paw by subplantar injections of fresh egg albumin (0.5 ml/kg). Diclofenac (100 mg/kg) was used as the reference anti-inflammatory agent for comparison, while distilled water was used as the placebo. The leucocytes count, corticosterone and C - reactive protein (CRP) levels were measured as biomarkers of inflammation. Data obtained were pooled and analysed using repeated ANOVA, in a general linear model with the CPSS software.

RESULTS

Sub-plantar injections of fresh egg albumin (0.5 ml/kg) produced profound and time-related oedema in the rat hind paw of the 'control' rats. Diclofenac (DIC, 100 mg/kg, i.p.) and reference capsaicin (CPF, 2.5 mg/kg, i.p.) significantly inhibited paw swelling at (p<0.05-0.001) (CI 95%) compared to distilled water-treated 'controls'. While the corticosterone levels were all very low in 7 rats treated with capsaicin, the leucocytes count was within normal range in 9 rats. However, in 16 specimens randomly assigned for CRP levels, there were very high CRP readings, up to a magnitude of 10 times the normal range.

CONCLUSIONS

Capsaicin in both forms (CFE and CPF) produced anti-inflammatory effects that were comparable to diclofenac in the experimental rat model at p<0.05. It may be concluded that capsaicin has both analgesic and anti-inflammatory properties.

Effect of mucosal TRPV1 inhibition in allergic rhinitis

Transient receptor potential vanilloid-1 (TRPV1) has been implicated as a mediator of itch in allergic rhinitis. To address this possibility, we synthesized a TRPV1 blocker (SB-705498) for nasal administration in patients with seasonal allergic rhinitis. The pharmacological activity of SB-705498 was confirmed on human TRPV1-expressing HEK293 cells, using fluorometric calcium imaging, and in patients with allergic rhinitis subjected to nasal capsaicin challenges. The effect of SB-705498 was studied in patients with seasonal allergic rhinitis subjected to daily allergen challenges for 7 days, using a double-blind, placebo-controlled, randomized and cross-over design. SB-705498 was delivered by nasal lavage 2 min. before each allergen challenge. Primary end-point was total nasal symptom score on days 5-7. Nasal peak inspiratory flow (nPIF) and eosinophil cationic protein (ECP) content in nasal lavages were also monitored. Daily topical applications of SB-705498 at a concentration that inhibited capsaicin-induced nasal symptoms had no effect on total symptom score, nPIF and ECP levels in allergen-challenged patients with seasonal allergic rhinitis. The individual symptoms, nasal itch or sneezes, were also not affected. These findings may indicate that TRPV1 is not a key mediator of the symptoms in allergic rhinitis. However, additional studies, using drug formulations with a prolonged duration of action, should be conducted before TRPV1 is ruled out as a drug target in allergic rhinitis.

TRPV1 and TRPA1 stimulation induces MUC5B secretion in the human nasal airway in vivo

AIM

Nasal transient receptor potential vanilloid 1 (TRPV1) stimulation with capsaicin produces serous and mucinous secretion in the human nasal airway. The primary aim of this study was to examine topical effects of various TRP ion channel agonists on symptoms and secretion of specific mucins: mucin 5 subtype AC (MUC5AC) and B (MUC5B).

METHODS

Healthy individuals were subjected to nasal challenges with TRPV1 agonists (capsaicin, olvanil and anandamide), TRP ankyrin 1 (TRPA1) agonists (cinnamaldehyde and mustard oil) and a TRP melastatin 8 (TRPM8) agonist (menthol). Symptoms were monitored, and nasal lavages were analysed for MUC5AC and MUC5B, i.e. specific mucins associated with airway diseases. In separate groups of healthy subjects, nasal biopsies and brush samples were analysed for TRPV1 and MUC5B, using immunohistochemistry and RT-qPCR. Finally, calcium responses and ciliary beat frequency were measured on isolated ciliated epithelial cells.

RESULTS

All TRP agonists induced nasal pain or smart. Capsaicin, olvanil and mustard oil also produced rhinorrhea. Lavage fluids obtained after challenge with capsaicin and mustard oil indicated increased levels of MUC5B, whereas MUC5AC was unaffected. MUC5B and TRPV1 immunoreactivities were primarily localized to submucosal glands and peptidergic nerve fibres, respectively. Although trpv1 transcripts were detected in nasal brush samples, functional responses to capsaicin could not be induced in isolated ciliated epithelial cells.

CONCLUSION

Agonists of TRPV1 and TRPA1 induced MUC5B release in the human nasal airways in vivo. These findings may be of relevance with regard to the regulation of mucin production under physiological and pathophysiological conditions.

Capsaicin-induced vasodilatation in human nasal vasculature is mediated by modulation of cyclooxygenase-2 activity and abrogated by sulprostone

Extensively based on evidence gained from experimental animal models, the transient receptor potential vanilloid receptor type 1 (TRPV1)-activator capsaicin is regarded as a valuable tool in the research on neurogenic inflammation. Although capsaicin-related drugs gained renewed interest as a therapeutic tool, there is also controversy as whether neurogenic inflammation actually takes place in humans. In this study, we verified the involvement of capsaicin in vascular responses that are regarded to be implicated in the cascade of neurogenic inflammatory mechanisms. By means of ex vivo functional experiments on human nasal mucosal vascular beds, the effect and mechanism of action of capsaicin was assessed in the absence and presence of various agents that interfere with potentially related transduction pathways. Ten micromolars of capsaicin induced vasodilatations that were reduced by the selective EP(1) prostanoid receptor antagonist SC19220 (10 μM) and almost abolished by the selective COX-2 inhibitor NS398 (1 μM) and the EP(1/3) receptor agonist sulprostone (0.1-10 nM), but not affected by the TRPV1-antagonists capsazepine (5 μM), the neurokinin NK(1) receptor antagonist GR20517A (1 μM), and the calcitonin-gene-related peptide (CGRP) receptor antagonist CGRP8-37 (100 nM). Spontaneously released PGE(2) and PGD(2) levels were significantly reduced in the presence of capsaicin. In conclusion, capsaicin-at concentrations clinically applied or under investigation for diverse disease backgrounds-induces a vasodilatory response in human nasal mucosa via a mechanism involving TRPV1-independent reduction of PGE(2) production by modulation of COX-2 enzymatic activity. These vasodilatations can be suppressed by the EP(1/3) receptor agonist sulprostone at subnanomolar concentrations.

TRPV1-mediated itch in seasonal allergic rhinitis

BACKGROUND

Patients with allergic rhinitis may be abnormally sensitive to stimulation of the ion channel transient receptor potential vanilloid-1 (TRPV1).

AIM OF THE STUDY

To examine effects of various TRP ion channel activators on sensory symptoms in allergic rhinitis prior to and during seasonal allergen exposure.

METHODS

Nasal challenges were carried out with the TRPV1-activators capsaicin, anandamide and olvanil. Moreover, challenges were performed with mustard oil (allylisothiocyanate) and cinnamaldehyde as well as menthol, activators of TRPA1 and TRPM8, respectively. Nasal symptoms were monitored after each challenge and compared with symptoms reported following corresponding sham challenges. Symptoms recorded after challenge prior to pollen season were also compared with challenge-induced symptoms during pollen season.

RESULTS

The TRPV1, TRPA1 and TRPM8-activators produced sensory symptoms dominated by pain and smart. During seasonal allergen exposure, but not prior to season, TRPV1-activators also induced itch. Furthermore, the seasonal challenge to the TRPV1-activator olvanil was associated with rhinorrhoea.

CONCLUSION

Patients with allergic rhinitis feature an increased itch response to TRPV1 stimulation at seasonal allergen exposure. We suggest that this reflects part of the hyperresponsiveness that characterizes on-going allergic rhinitis. Intervention with the TRPV1-signalling pathway may offer potential treatments of this condition.

Neuronal markers in allergic rhinitis: expression and correlation with sensory testing

INTRODUCTION

Although the role of immunoglobulin E-mediated hypersensitivity reactions in allergic rhinitis is well known, the relative contribution of sensory nerves to the symptoms of rhinitis is uncertain. This study looked at the level of specific neuronal markers including the nerve marker protein gene product 9.5 (PGP 9.5), sensory and autonomic neuropeptides, the capsaicin/heat receptor TRPV1, and nerve growth factor (NGF) in patients with allergic rhinitis and controls and their correlation with nasal sensitivity.

MATERIALS AND METHODS

Forty patients (23 controls, 17 rhinitis) having nasal surgery were recruited. Nasal sensitivity was tested using graded monofilaments. Inferior turbinate biopsies were collected and studied using immunohistology, with measurement of nerve fibers by direct observation or computerized image analysis.

RESULTS

Nerve fibers (PGP 9.5) in the epithelium, subepithelium, and glandular/vascular regions were significantly increased in allergic rhinitis (P=.037, <.01, and .04, respectively), as were subepithelial and glandular/vascular fibers immunoreactive for neuropeptide substance P (P=.04 subepithelium; .02 glandular/vascular) and neuropeptide tyrosine (P<.01 glandular/vascular), markers for sensory and sympathetic nerves, respectively. TRPV1 epithelial fiber counts were higher in rhinitis, but this was not statistically significant. Epithelial NGF immunoreactivity (% area) was significantly increased in rhinitis (P=.027). Nasal sensitivity was correlated significantly with PGP 9.5 subepithelial innervation (control touch P=.023, irritation P=.046; rhinitis touch P=.042, irritation P=.043). A correlation was also observed between epithelial NGF and subepithelial PGP 9.5 innervation, which included all subjects (P=.044).

CONCLUSION

The increased number and specific phenotypical changes of sensory nerves may play a role in nasal hypersensitivity and provide new targets for the treatment of rhinitis.

Challenge-induced plasma exudation and mucinous secretion in human airways

Secretion of mucins and exudation of plasma are distinct processes of importance to innate immunity and inflammatory disease. Yet, little is known about their relation in human airways. The objective of the present study was to use the human nasal airway to determine mucinous secretion and plasma exudation in response to common challenge agents and mediators. Ten healthy volunteers were subjected to nasal challenge-lavage procedures. Thus, the nasal mucosa was exposed to increasing doses of histamine (40 and 400 microg ml(-1)), methacholine (12.5 and 25 mg) and capsaicin (30 and 300 ng ml(-1)). Fucose was selected as a global marker of mucinous secretion and alpha(2)-macroglobulin as an index of exudation of bulk plasma. All challenge agents increased the mucosal output of fucose to about the same level (P<0.01-0.05). Once significant secretion had been induced the subsequently increased dose of the challenge agent, in the case of histamine and methacholine, failed to further increase the response. Only histamine increased the mucosal output of alpha(2)-macroglobulin (P<0.01). We conclude that prompt but potentially rapidly depleted mucinous secretion is common to different kinds of airway challenges, whereas inflammatory histamine-type mediators are required to produce plasma exudation. Along with the acknowledged secretion of mucins, a practically non-depletable, pluripotent mucosal output of plasma emerges as an important component of the innate immunity of human airways.

Relationship of airway symptoms from chemicals to capsaicin cough sensitivity in atopic subjects

BACKGROUND

It is well known that some patients with allergy complain of airway symptoms from chemicals (ASCs) and strong odours. However, the importance of such information for the treatment of allergic disease is not known. Such symptoms in non-allergic patients have previously been shown to be related to increased sensory nerve reactivity, which is expressed as increased cough sensitivity to inhaled capsaicin.

OBJECTIVE

The aim of this study was to examine ASC in atopic patients and relate it to cough reaction to capsaicin inhalation.

MATERIALS AND METHODS

Fifty-seven consecutively chosen, skin prick-positive patients with symptoms of the upper and/or lower airways completed a questionnaire concerning ASC. The patients were then divided into two groups, those with and those without such symptoms. Both groups were provoked with inhaled capsaicin in three increments and compared with 73 healthy control subjects.

RESULTS

Out of 57 atopic patients, 34 reported ASC agents and 23 did not. The patients with ASC were older (P<0.01) and coughed significantly more on capsaicin provocation (P<0.001), but did not differ from them with respect to the allergic disease or its treatment or to smoking habits. Patients with atopy but without ASC did not differ from healthy controls with regard to sensitivity to capsaicin inhalation. The scored degree of ASC was directly related to the number of coughs during the capsaicin provocation.

CONCLUSION

ASC in atopic patients are related to increased airway sensory nerve reactivity. There is still no explanation for this in certain patients with atopy, but age may be a confounding factor.

Capsaicin cough sensitivity in allergic asthmatic patients increases during the birch pollen season

BACKGROUND

A change in neural responsiveness may occur as the result of allergic inflammation in the lower airways as well as in the upper airways. In the lower airways, capsaicin cough sensitivity is known to reflect sensory neural reactivity.

OBJECTIVE

The aim of this study was to establish whether allergic inflammation changes airway neural sensory reactivity during prolonged allergen exposure.

METHODS

Ten nonsmoking patients with birch pollen-allergic asthma performed a capsaicin inhalation challenge twice, once in the off-pollen season and once during the pollen season. The number of coughs and symptoms induced by capsaicin were recorded and compared with those of healthy control subjects.

RESULTS

The response to capsaicin, expressed as number of coughs, increased in a dose-dependent manner during both tests. Before the season, the response was similar to that of healthy control subjects, but during the pollen season, the reactivity was significantly increased. Variations in forced expiratory volume in 1 second were not significant before and after each challenge, and values did not change during the pollen season as compared with the winter season.

CONCLUSIONS

Sensory reactivity in allergic asthmatic patients may be increased during prolonged allergen exposure as during the pollen season. This finding suggests that allergic inflammation in the lower and/or upper airways may trigger neurogenic mechanisms of significant clinical importance.