Tissue-specific effects of allergic rhinitis in mouse nasal epithelia

Effect of Probiotics on Respiratory Tract Allergic Disease and Gut Microbiota

Allergy is a hypersensitivity reaction triggered by specific cell or antibody-mediated immune mechanisms. Allergies have increased in industrialized countries in recent decades. The rise in allergic respiratory diseases such as allergic rhinitis (AR) and allergic asthma (AA) is a potential threat to public health. Searches were conducted using PubMed, Google Scholar and Medline using the following key terms: allergic rhinitis OR asthma AND probiotics, allergic airway inflammation AND immune disorders, probiotics OR gut microbiota AND allergic disease, probiotics AND inflammatory. Studies from all years were included, specifically those published within the last 10 years. Some review articles and their reference lists were searched to identify related articles. The role of microbiota in respiratory allergic diseases has attracted more and more attention. Pieces of evidence suggested that the development of allergic diseases causes a possible imbalance in the composition of the gut microbiota. Compared to colonized mice, germ-free mice exhibit exaggerated allergic airway responses, suggesting that microbial host interactions play an important role in the development of allergic diseases. Probiotics modulate both the innate and adaptive inflammatory immune responses, often used as dietary supplements to provide health benefits in gastrointestinal disorders. Probiotics may serve as immunomodulators and activators of host defense pathways. Besides, oral probiotics can modulate the immune response in the respiratory system. Recently, studies in humans and animals have demonstrated the role of probiotic in RA and AA. To understand the characterization, microbiota, and the potential role of probiotics intervention of AA/AR, this review provides an overview of clinical features of AA and AR, probiotics for the prevention and treatment of AR, AA, changes in gut microbiota, and their mechanisms of action.

Apigenin Attenuates Allergic Responses of Ovalbumin-Induced Allergic Rhinitis Through Modulation of Th1/Th2 Responses in Experimental Mice

Background

Allergic rhinitis (AR) is an immunoglobulin E (IgE)-mediated immune-inflammatory response mainly affecting nasal mucosa. Apigenin, a flavonoid, has been documented to possess promising anti-allergic potential.

Aim

To determine the potential mechanism of action of apigenin against ovalbumin (OVA)-induced AR by assessing various behavioral, biochemical, molecular, and ultrastructural modifications.

Materials and Methods

Allergic rhinitis was induced in BALB/c mice (18-22 grams) by sensitizing it with OVA (5%, 500 μL, intraperitoneal [IP] on each consecutive day, for 13 days) followed by intranasal challenge with OVA (5%, 5 μL per nostril on day 21). Animals were treated with either vehicle (distilled water, 10 mg/kg, IP) or apigenin (5, 10, and 20 mg/kg, IP).

Results

Intranasal challenge of OVA resulted in significant induction (P < .05) of AR reflected by an increase in nasal symptoms (sneezing, rubbing, and discharge), which were ameliorated significantly (P < .05) by apigenin (10 and 20 mg/kg) treatment. It also significantly inhibited (P < .05) OVA-induced elevated serum histamine, OVA-specific IgE, total IgE, and IgG1 and β-hexosaminidase levels. Ovalbumin-induced increased levels of interleukin (IL)-4, IL-5, IL-13, and interferon (IFN)-γ in nasal lavage fluid were significantly decreased (P < .05) by apigenin. Ovalbumin-induced alterations in splenic GATA binding protein 3 (ie, erythroid transcription factor) (GATA3), T-box protein expressed in T cells (T-bet), signal transducer and activator of transcription-6 (STAT6), suppressor of cytokine signaling 1 (SOCS1), nuclear factor-kappa B (NF-κB), and nuclear factor of kappa light polypeptide gene enhancer in B-cells inhibitor-alpha messenger RNA, as well as protein expressions were significantly inhibited (P < .05) by apigenin. It also significantly ameliorated (P < .05) nasal and spleen histopathologic and ultrastructure aberration induced by OVA.

Conclusion

Apigenin regulates Th1/Th2 balance via suppression in expressions of Th2 response (IgE, histamine, ILs, GATA3, STAT6, SOCS1, and NF-κB) and activation of Th1 response (IFN-γ and T-bet) to exert its anti-allergic potential in a murine model of OVA-induced AR.

Effects of Cigarette Smoke on the Nasal Respiratory and Olfactory Mucosa in Allergic Rhinitis Mice

Objective

Cigarette smoke (CS) exposure reportedly enhances allergic airway inflammation. However, some studies have shown an association between current cigarette smoke exposure and a low risk for allergic rhinitis. Thus, the impact of CS exposure on allergic rhinitis remains poorly understood. The purpose of this study was to investigate the effects of CS on the respiratory mucosa (RM) and the olfactory epithelium (OE) of mice with allergic rhinitis, as the effects may differ depending on the nasal histological compartments.

Methods

Eight-week-old male BALB/c mice were used for this study. We developed a mouse model of smoking by intranasally administering 10 doses of a CS solution (CSS), and a mouse model of allergic rhinitis by sensitization with intraperitoneal ovalbumin (OVA) injection and intranasal challenge with OVA. We examined the effects of CS on the nasal RM and OE in mice with or without allergic rhinitis using histological, serum, and genetic analyses. First, we examine whether CSS exposure induces allergic responses and then, examined allergic responses in the OVA-sensitized allergic rhinitis mice with or without CSS exposure.

Results

Short-term CSS administration intensified allergic responses including increased infiltration of eosinophils and inflammatory cells and upregulation of interleukin-5 expression in the nasal RM of OVA-immunized mice, although only CSS induced neither allergic responses nor impairment of the RM and OE. Notably, repetitive OVA-immunization partially impaired the OE in the upper-lateral area, but CSS administration did not reinforce this impairment in OVA-induced allergic mice.

Conclusion

Short-term CSS exposure strengthened allergic responses in the nasal RM and did not change the structure of the OE. These results suggest that patients with allergic rhinitis could experience exacerbation of allergic symptoms after CS exposure.

Type 2/Th2-driven inflammation impairs olfactory sensory neurogenesis in mouse chronic rhinosinusitis model

BACKGROUND

Chronic rhinosinusitis (CRS) with nasal polyps (CRSwNP) is a chronic inflammatory disease often accompanied by impairment of sense of smell. This symptom has been somewhat overlooked, and its relationship to inflammatory cytokines, tissue compression, neuronal loss, and neurogenesis is still unclear.

METHODS

In order to elucidate potential mechanisms leading to CRS in humans, we have established a type 2/T helper type 2 cell (Th2)-mediated allergic CRS mouse model, based on house dust mite (HDM) and Staphylococcus aureus enterotoxin B (SEB) sensitization. The inflammatory status of the olfactory epithelium (OE) was assessed using histology, biochemistry, and transcriptomics. The sense of smell was evaluated by studying olfactory behavior and recording electro-olfactograms (EOGs).

RESULTS

After 22 weeks, a typical type 2/Th2-mediated inflammatory profile was obtained, as demonstrated by increased interleukin (IL)-4, IL-5, and IL-13 in the OE. The number of mast cells and eosinophils was increased, and infiltration of these cells into the olfactory mucosa was also observed. In parallel, transcriptomic and histology analyses indicated a decreased number of immature olfactory neurons, possibly due to decreased renewal. However, the number of mature sensory neurons was not affected and neither the EOG nor olfactory behavior was impaired.

CONCLUSION

Our mouse model of CRS displayed an allergic response to HDM + SEB administration, including the type 2/Th2 inflammatory profile characteristic of human eosinophilic CRSwNP. Although the sense of smell did not appear to be altered in these conditions, the data reveal the influence of chronic inflammation on olfactory neurogenesis, suggesting that factors unique to humans may be involved in CRSwNP-associated anosmia.

Intranasal application of glucocorticoid alleviates olfactory dysfunction in mice with allergic rhinitis

The aim of the present study was to investigate the effect of glucocorticoid intervention on olfactory dysfunction in mice with allergic rhinitis (AR). An AR animal model was established by intraperitoneal injection and intranasal application of ovalbumin to mice. The olfactory function of the mice was evaluated using a buried food test, and morphological changes in the nasal mucosa were determined using hematoxylin and eosin staining. The expression of olfactory marker protein (OMP) in the olfactory mucosa was tested by immunohistochemistry, and was observed on days 7 and 14 after the application of glucocorticoid. The incidence rate of olfactory dysfunction in AR mice was 75.34%, and the olfactory epithelium became thinner in mice with AR compared to the control group. In addition, the expression of OMP in the olfactory epithelium was downregulated in mice with AR compared with the control group. Expression of OMP in the olfactory epithelium was upregulated in the budesonide group A and betamethasone group A compared with the medicine-free group, whereas the expression of OMP in the olfactory epithelium of budesonide group A or betamethasone group A was not significantly different from the control group. Moreover, the expression of OMP in the budesonide group B was similar to budesonide group A, and expression of OMP in betamethasone group B was similar to betamethasone group A. The expression of OMP in olfactory mucosa is downregulated in AR mice with olfactory dysfunction. Following the application of glucocorticoid, the expression of OMP in the olfactory mucosa in mice is upregulated. Moreover, intranasal local glucocorticoid has a low incidence of systemic adverse reactions, and is recommended for the treatment of olfactory dysfunction in AR.

Effects of 1,25-dihydroxyvitamin D3 in an ovalbumin-induced allergic rhinitis model

IL-17-producing Th17 cells play an important role in allergic airway diseases, but their local expression and regulation in allergic rhinitis (AR) is not well understood. This study investigated the effects of 1,25-dihydroxyvitamin D3 (1,25-(OH)₂D₃) on T-bet expression, Th1 cells, Th2 cells, Th17 cells and IL-33-positive epithelial cells in AR. C57BL/6 mice were intranasally sensitized and challenged with ovalbumin (OVA), and 1,25-(OH)₂D₃ was intraperitoneally injected into AR mice. Cytokine levels were measured with enzyme-linked immunosorbent assays, phenotypic analysis of Th1, Th2 and Th17 cells in the spleen was completed with flow cytometry, and the CD4⁺IL-17⁺ cells in the Nasopharynx-associated lymphoid tissue (NALT) and IL-33-positive cells in nasal mucosa was evaluated with immunofluorescence microscopy. AR mice shown significantly increased Th2 and Th17 cell ratio in spleen, IL-17 level in serum, IL-5 and IL-13 levels in NALF but a lower number of IL-33-positive epithelial cells and Th1 response (Th1 and Tbet⁺Th1 cell ratio in the spleen and serum IFN-γ level) than the control mice.1,25-(OH)₂D₃ treatment significantly decreased the number of sneezing, nasal rubbing, OVA-sIgE and IL-17 in serum, IL-5 and IL-13 levels in NALF, Th17 cell ratio in the spleen and the histological of nasal mucosal but increased the number of IL-33-positive epithelial cells in AR mice. However, 1,25-(OH)₂D₃ treatment did not significantly influence IFN-γ level in serum, and Th1, Tbet⁺Th1 and Th2 cell ratio in spleen. Thus, 1,25-(OH)₂D₃ may exert anti-allergic effects by suppressing Th17 responses and local production of IL-5 and IL-13 cytokines.

Role of the type I tumor necrosis factor receptor in inflammation-associated olfactory dysfunction

BACKGROUND

To understand mechanisms of human olfactory dysfunction in chronic rhinosinusitis, an inducible olfactory inflammation (IOI) model has been utilized to chronically express inflammatory cytokines locally, resulting in neuronal loss, diminished odorant responses, and repressed olfactory regeneration. Knockout of the minor tumor necrosis factor α receptor 2 (TNFR2) was previously shown to partially rescue these olfactory changes. The purpose of current study was to investigate the role of the major TNF receptor, TNFR1, in chronic olfactory inflammation.

METHODS

Two experimental groups of mice were studied: TNFR1 knockout in IOI background and TNFR1 knockout with allergen-induced inflammation. Olfactory function was assayed by electro-olfactogram (EOG), and olfactory tissue was processed for histology and immunohistochemical staining.

RESULTS

TNF-α was dramatically induced in IOI-TNFR1 knockout mice, but the olfactory epithelium did not show inflammation. EOG responses were normal after either 2 or 8 weeks of TNF-α expression. Ovalbumin-sensitized TNFR1 knockout mice developed markedly diminished eosinophilic inflammatory infiltration.

CONCLUSION

Genetic deletion of TNFR1 completely blocks TNF-α-induced inflammation and reduces allergen-induced inflammation. Preserved EOG responses suggest a TNFR1-dependent mechanism of TNF-α-induced olfactory neuron dysfunction.

Effects of the inhaled treatment of liriope radix on an asthmatic mouse model

As a treatment for allergic asthma, inhaled treatments such as bronchodilators that contain β2-agonists have an immediate effect, which attenuates airway obstructions and decreases airway hypersensitivity. However, bronchodilators only perform on a one off basis, but not consistently. Asthma is defined as a chronic inflammatory disease of the airways accompanying the overproduction of mucus, airway wall remodeling, bronchial hyperreactivity and airway obstruction. Liriope platyphylla radix extract (LPP), a traditional Korean medicine, has been thoroughly studied and found to be an effective anti-inflammatory medicine. Here, we demonstrate that an inhaled treatment of LPP can attenuate airway hyperresponsiveness (AHR) in an ovalbumin-induced asthmatic mouse model, compared to the saline-treated group (p < 0.01). Moreover, LPP decreases inflammatory cytokine levels, such as eotaxin (p < 0.05), IL-5 (p < 0.05), IL-13 (p < 0.001), RANTES (p < 0.01), and TNF-α (p < 0.05) in the bronchoalveolar lavage (BAL) fluid of asthmatic mice. A histopathological study was carried out to determine the effects of LPP inhalation on mice lung tissue. We performed UPLC/ESI-QTOF-MS, LC/MS, and GC/MS analyses to analyze the chemical constituents of LPP, finding that these are ophiopogonin D, spicatoside A, spicatoside B, benzyl alcohol, and 5-hydroxymethylfurfural. This study demonstrates the effect of an inhaled LPP treatment both on airway AHR and on the inflammatory response in an asthmatic mouse model. Hence, LPP holds significant promise as a nasal inhalant for the treatment of asthmatic airway disease.

Phenotypic characteristics of nasal mast cells in a mouse model of allergic rhinitis

BACKGROUND

Mast cells (MCs) in the nasal respiratory mucosa (NRM) play a triggering role in the pathogenesis of allergic rhinitis (AR). Recent research evidence in mouse models of AR suggests an underlying MC-related allergic response in mouse nasal olfactory mucosa (NOM).

OBJECTIVE

We sought to investigate the phenotypic characteristics of nasal MCs in a mouse model of AR.

METHODS

By MC-specific staining and immunohistochemistry, we analyzed the subset, protease and IgE-binding phenotypes of nasal MCs in ovalbumin (OVA)-sensitized unchallenged and challenged mice.

RESULTS

In OVA-sensitized challenged mice, increased serum OVA-specific IgE levels (p < 0.001) and eosinophil infiltration confirmed AR induction. In addition to constitutive connective tissue MCs, mucosal MCs were induced in NRM and NOM of OVA-sensitized challenged mice. Connective tissue MCs and mucosal MCs in mouse NRM and NOM were positive for mouse MC protease-1, -4, -5, -6, -7 and carboxypeptidase-A3. In line with MCs in NRM, there were increased numbers (p = 0.019) and proportions (p = 0.027) of MCs with surface-bound IgE in NOM of OVA-sensitized challenged mice.

CONCLUSION

In the setting of AR, MCs in mouse NOM exhibit the same subset, protease and IgE-binding phenotypes as MCs in mouse NRM.

Effect of ionic compositions in nasal irrigations on human olfactory thresholds

OBJECTIVES/HYPOTHESIS

Nasal irrigations are commonly employed to promote nasal hygiene in the treatment of various sinonasal conditions. Few studies have evaluated how the ionic composition of irrigation solutions affects olfactory performance. The purpose of this study was to determine the dose responsiveness of human olfactory thresholds for each of the following ions: potassium, sodium, and calcium.

STUDY DESIGN

Prospective translational study.

METHODS

Irrigation solutions with variable potassium, sodium, and calcium were tested in 25 healthy human participants. Six potassium concentrations (range, 2-10 mM), six sodium concentrations (range, 73.7-113.7 mM), and three calcium concentrations (range, 0.44-0.64 mM) were used. Before and immediately following irrigations, olfactory thresholds were determined using the Sniffin' Sticks test. Differences in olfactory threshold scores before and after irrigations were compared to assess the effect of ionic composition on olfactory sensitivity.

RESULTS

Physiologic concentrations of potassium, sodium, and calcium at 5.7, 89.5, and 0.54 mM, respectively, did not significantly change olfactory thresholds. Variations in both potassium and sodium concentrations demonstrated statistically significant dose-dependent elevations in olfactory thresholds (P < .05). Only the calcium concentration that was lower than the physiologic level led to significant elevations in olfactory thresholds.

CONCLUSIONS

Different potassium and sodium concentrations in irrigation solutions provide distinctive dose-dependent shifts in olfactory thresholds. Calcium concentrations also elevate olfactory thresholds, but calcium plays a less significant role than potassium and sodium in modulating olfactory thresholds. These results highlight the importance of the intranasal ionic microenvironment in olfactory physiology and suggest that optimal ionic concentrations in irrigation solutions exist to preserve olfactory function.

LEVEL OF EVIDENCE

NA.

Induction of allergic rhinitis in mice

We describe a method for allergic rhinitis (AR) induction in mice. Methodology involves nasal infusions of small volumes of ovalbumin for both initial sensitization and challenges. The latter are frequent and carried out over several weeks. This methodology more closely resembles natural AR induction than does the common use of systemic sensitization, often with adjuvants, followed by nasal challenges with relatively large allergen volumes. Also described are methodologies for collection of cardiac blood and perfusion for preparation of histological samples, both essential in verifying AR induction in individual animals.

In vivo determination of mouse olfactory mucus cation concentrations in normal and inflammatory states

OBJECTIVE

Olfaction is impaired in chronic rhinosinusitis (CRS). The study has two aims: (1) to determine whether changes in cation concentration occur in the olfactory mucus of mice with CRS, which may affect chemo-electrical transduction, (2) and to examine whether these alterations are physiologically significant in humans.

STUDY DESIGN

Animal study in mice and translational study in humans.

METHODS

Inflammation was induced by sensitization and chronic exposure of 16 C57BL/6 mice to Aspergillus fumigatus. The control group included 16 untreated mice. Ion-selective microelectrodes were used to measure free cation concentrations in the olfactory mucus of 8 mice from each treatment group, while the remaining mice were sacrificed for histology. To validate the findings in the animal model, olfactory threshold was measured in 11 healthy human participants using Sniffin' Sticks before and after nasal irrigation with solutions that were composed of either of the cation concentrations.

RESULTS

In 8 mice, olfactory mucus of chronically inflamed mice had lower [Na(+)] (84.8±4.45 mM versus 93.73±3.06 mM, p = 0.02), and higher [K(+)] (7.2±0.65 mM versus 5.7±0.20 mM, p = 0.04) than controls. No difference existed in [Ca(2+)] (0.50±0.12 mM versus 0.54±0.06 mM, p = 0.39). In humans, rinsing with solutions replicating ion concentrations of the mouse mucosa with chronic inflammation caused a significant elevation in the median olfactory threshold (9.0 to 4.8, p = 0.003) but not with the control solution (8.3 to 7.8, p = 0.75).

CONCLUSION

Chronic inflammation elevates potassium and lowers sodium ion concentration in mice olfactory mucus. Nasal irrigation with a corresponding solution induced olfactory threshold shift in humans.