GM-CSF, IL-8, IL-1R, TNF-alpha R, and HLA-DR in nasal epithelial cells in allergic rhinitis

Febuxostat Alleviates Allergic Rhinitis by Inhibiting Inflammation and Monocyte Adhesion in Human Nasal Epithelial Cells via Regulating KLF6

Introduction

Febuxostat is a novel inhibitor of xanthine oxidase that suppresses cell adhesion molecules-mediated (CAMs) inflammation by activating KLF6. In this study, we explored the therapeutic function and potential mechanisms of febuxostat against allergic rhinitis (AR).

Methods

We investigated the role of febuxostat through in vitro cell and in vivo animal experiments. Human nasal epithelial cells (hNECs) were cultured with histamine as an in vitro model. To establish the AR animal model, rats were exposed to ovalbumin. Rats were randomly grouped into control, model, 7.5 mg/kg febuxostat, and 15 mg/kg febuxostat groups.

Results

In the in vitro study, we found significantly increased release of lactate dehydrogenase, elevated production of inflammatory factors and chemokines, and upregulated CAMs in histamine-treated hNECs. However, these results were significantly reversed for the 10 and 20 μM febuxostat treatments. The enhanced adhesion between hNECs and monocytes induced by histamine was dramatically repressed by febuxostat. In the vivo experiments, we observed that febuxostat ameliorated the increased sneezing times, the number of nose scratching episodes, and elevated HE pathological scores as well as alleviated the inflammation in nasal mucous tissues of AR mice. We found that KLF6, which was downregulated in histamine-treated hNECs, was significantly upregulated by febuxostat. The inhibitory effects of febuxostat on the expression levels of CAMs and adhesion between histamine-treated hNECs and monocytes were significantly abolished by the knockdown of KLF6.

Conclusion

Febuxostat alleviates AR by inhibiting inflammation and monocyte adhesion in human nasal epithelial cells through the regulation of KLF6.

The role of regulatory T cells in the regulation of upper airway inflammation

Allergic rhinitis (AR) and chronic rhinosinusitis with nasal polyps (CRSwNP) are inflammatory diseases of the upper airway, with a similar immunologic profile, characterized by aberrant and persistent type 2 inflammation. One cell population that has been identified as altered in both disease types is regulatory T cell (Treg). Tregs have the capacity to modulate T-effector function and suppress inflammatory cytokine production in a broad range of cell types. Given the ability of Tregs to control inflammation, the role of Tregs in respiratory diseases has attracted much attention. As discussed in this article, alterations in the Treg numbers and function, or both, have been identified in AR and CRSwNP, although much of the data is conflicting. Here, we explored what is known and, in many cases, unknown about the mechanisms by which Tregs differentiate and function, and how these functions can be controlled in the mucosal microenvironment. By gaining a greater understanding of these processes, it may be possible to harness the natural immunosuppressive activity of Tregs to ameliorate the chronic inflammation associated with AR and CRSwNP.

Association between chronic acetaminophen exposure and allergic rhinitis in a rat model

Background:

Several population studies demonstrated an increased risk of allergic rhinitis in patients exposed to acetaminophen. However, no histologic studies have been conducted to assess the relationship between acetaminophen exposure and allergic rhinitis.

Objective:

In this study, we investigated the association between chronic acetaminophen exposure and the development of allergic rhinitis in a rat model.

Methods:

Ten female Sprague-Dawley rats were randomly assigned to either a control (n = 5) or an acetaminophen group (n = 5). The acetaminophen group received 200 mg/kg/day of acetaminophen suspended in yogurt via oral gavage for 120 days. The control group received only the yogurt vehicle. Allergic behavioral responses, including nose rub, eye rub, ear scratching, and neck and/or face scratching, were quantified. The rats were killed, and the noses were harvested. The portion of the nose, including the nasal septum and the inferior turbinates, was embedded in paraffin, sectioned, and stained with hematoxylin and eosin to quantify the inflammatory infiltrate.

Results:

The average number of allergic responses per animal was 13.2 in the acetaminophen group versus 6.2 in the control group (p = 0.032). All the rats in the acetaminophen group (100%) had mast cells infiltrating the lamina propria of the inferior turbinate, whereas mast cells were detected in only 40% of the animals in the control group. The average number of mast cells per animal in the acetaminophen group was 134 versus 21 in the control group (p = 0.048).

Conclusions:

Our study was the first to demonstrate a histologic association between chronic exposure to acetaminophen and rhinitis. Further research to elucidate the mechanism that underlies these findings is necessary.

Childhood allergic rhinitis, traffic-related air pollution, and variability in the GSTP1, TNF, TLR2, and TLR4 genes: results from the TAG Study

BACKGROUND

Associations between traffic-related air pollution (TRAP) and allergic rhinitis remain inconsistent, possibly because of unexplored gene-environment interactions.

OBJECTIVE

In a pooled analysis of 6 birth cohorts (Ntotal = 15,299), we examined whether TRAP and genetic polymorphisms related to inflammation and oxidative stress predict allergic rhinitis and sensitization.

METHODS

Allergic rhinitis was defined with a doctor diagnosis or reported symptoms at age 7 or 8 years. Associations between nitrogen dioxide, particulate matter 2.5 (PM2.5) mass, PM2.5 absorbance, and ozone, estimated for each child at the year of birth, and single nucleotide polymorphisms within the GSTP1, TNF, TLR2, or TLR4 genes with allergic rhinitis and aeroallergen sensitization were examined with logistic regression. Models were stratified by genotype and interaction terms tested for gene-environment associations.

RESULTS

Point estimates for associations between nitrogen dioxide, PM2.5 mass, and PM2.5 absorbance with allergic rhinitis were elevated, but only that for PM2.5 mass was statistically significant (1.37 [1.01, 1.86] per 5 μg/m(3)). This result was not robust to single-cohort exclusions. Carriers of at least 1 minor rs1800629 (TNF) or rs1927911 (TLR4) allele were consistently at an increased risk of developing allergic rhinitis (1.19 [1.00, 1.41] and 1.24 [1.01, 1.53], respectively), regardless of TRAP exposure. No evidence of gene-environment interactions was observed.

CONCLUSION

The generally null effect of TRAP on allergic rhinitis and aeroallergen sensitization was not modified by the studied variants in the GSTP1, TNF, TLR2, or TLR4 genes. Children carrying a minor rs1800629 (TNF) or rs1927911 (TLR4) allele may be at a higher risk of allergic rhinitis.

Transcriptome analysis of the ependymal barrier during murine neurocysticercosis

BACKGROUND

Central nervous system (CNS) barriers play a pivotal role in the protection and homeostasis of the CNS by enabling the exchange of metabolites while restricting the entry of xenobiotics, blood cells and blood-borne macromolecules. While the blood-brain barrier and blood-cerebrospinal fluid barrier (CSF) control the interface between the blood and CNS, the ependyma acts as a barrier between the CSF and parenchyma, and regulates hydrocephalic pressure and metabolic toxicity. Neurocysticercosis (NCC) is an infection of the CNS caused by the metacestode (larva) of Taenia solium and a major cause of acquired epilepsy worldwide. The common clinical manifestations of NCC are seizures, hydrocephalus and symptoms due to increased intracranial pressure. The majority of the associated pathogenesis is attributed to the immune response against the parasite. The properties of the CNS barriers, including the ependyma, are affected during infection, resulting in disrupted homeostasis and infiltration of leukocytes, which correlates with the pathology and disease symptoms of NCC patients.

RESULTS

In order to characterize the role of the ependymal barrier in the immunopathogenesis of NCC, we isolated ependymal cells using laser capture microdissection from mice infected or mock-infected with the closely related parasite Mesocestoides corti, and analyzed the genes that were differentially expressed using microarray analysis. The expression of 382 genes was altered. Immune response-related genes were verified by real-time RT-PCR. Ingenuity Pathway Analysis (IPA) software was used to analyze the biological significance of the differentially expressed genes, and revealed that genes known to participate in innate immune responses, antigen presentation and leukocyte infiltration were affected along with the genes involved in carbohydrate, lipid and small molecule biochemistry. Further, MHC class II molecules and chemokines, including CCL12, were found to be upregulated at the protein level using immunofluorescence microscopy. This is important, because these molecules are members of the most significant pathways by IPA analyses.

CONCLUSION

Thus, our study indicates that ependymal cells actively express immune mediators and likely contribute to the observed immunopathogenesis during infection. Of particular interest is the major upregulation of antigen presentation pathway-related genes and chemokines/cytokines. This could explain how the ependyma is a prominent source of leukocyte infiltration into ventricles through the disrupted ependymal lining by way of pial vessels present in the internal leptomeninges in murine NCC.

Influence of Orai1 intervention on mouse airway epithelium reactions in vivo and in vitro

BACKGROUND

Orai1 is crucial for store-operated Ca2(+) entry and Ca2(+) release-activated Ca2(+) channel activities. However, little is known about its function in allergic diseases.

OBJECTIVE

To assess the influence of Orai1 intervention on mouse airway epithelium reactions in vivo and in vitro.

METHODS

We used immunohistochemical staining, enzyme-linked immunosorbent assay, and real-time reverse transcription-polymerase chain reaction to evaluate Orai1 expression in nasal and tracheal mucosa epithelium of nonsensitized, control, and 2-aminoethoxydiphenyl borate (2-APB)-treated groups in vivo and in vitro. In addition, we analyzed concentrations of interleukin 1β, interleukin 6, macrophage inflammatory protein 2, and tumor necrosis factor α in nasal lavage fluid, bronchoalveolar lavage fluid, and culture supernatant and their messenger RNAs in nasal and tracheal mucosa and cultured nasal and tracheal epithelium.

RESULTS

Administration of 2-APB into the nostrils suppressed Orai1 expression in nasal and tracheal mucosa of treated mice compared with that in control mice and restrained the mediators in nasal lavage fluid, bronchoalveolar lavage fluid, and airway mucosa of treated groups compared with those in control groups. Similarly, the 2-APB intervention also alleviated Orai1 and the production of the mediators in culture supernatant and cultured airway epithelium under allergic conditions.

CONCLUSIONS

Our results indicate that 2-APB could effectively ameliorate reactions of upper and lower airway epithelial cells in mice in allergic states in vivo and in vitro.

Epithelial cells and airway diseases

The airway epithelial cell is the initial cell type impacted both by inhaled environmental factors, such as pathogens, allergens, and pollutants, and inhaled medications for airway diseases. As such, epithelial cells are now recognized to play a central role in the regulation of airway inflammatory status, structure, and function in normal and diseased airways. This article reviews our current knowledge regarding the roles of the epithelial cell in airway inflammation and host defense. The interactions of inhaled environmental factors and pathogens with epithelial cells are also discussed, with an emphasis on epithelial innate immune responses and contributions of epithelial cells to immune regulation. Recent evidence suggesting that epithelial cells play an active role in inducing several of the structural changes, collectively referred to airway remodeling, seen in the airways of asthmatic subjects is reviewed. Finally, the concept that the epithelium is a major target for the actions of a number of classes of inhaled medications is discussed, as are the potential mechanisms by which selected drugs may alter epithelial function.

Lack of association between CD58 genetic variations and aspirin-exacerbated respiratory disease in a Korean population

BACKGROUND

Exacerbation of asthma symptoms due to aspirin ingestion may lead to life-threatening lung failure. The adhesion molecule CD58 gene may play a crucial role in aspirin-exacerbated respiratory disease (AERD) pathogenesis by mediating the biological functions of asthma-inducing mechanisms including T helper cells, proinflammatory cytokines, and natural killer T cells.

OBJECTIVE

This study aimed to investigate the association of CD58 variations with aspirin-induced bronchospasm in Korean asthma patients.

METHODS

Seven single-nucleotide polymorphisms were selected for genotyping based on previously reported polymorphisms in the International HapMap database. Genotyping was carried out using TaqMan assay and 2 major haplotypes were obtained in 163 AERD cases and 429 aspirin-tolerant asthma controls. Frequency distributions of CD58 variations were analyzed using logistic and regression models.

RESULTS

Results showed that none of the analyzed CD58 single-nucleotide polymorphisms and haplotypes was significantly associated with AERD development and fall rate of FEV(1) by aspirin provocation, an important diagnostic marker of aspirin hypersensitivity.

CONCLUSIONS

This preliminary study suggests that CD58 does not affect AERD susceptibility in a Korean population, and may provide a new direction for future disease etiology.

Up-regulation of Orai1 in murine allergic rhinitis

Orai1 is an essential pore-forming subunit of the Ca(2+) release-activated Ca(2+) channels and plays a key role in the store-operated Ca(2+) entry. However, little is known about the function of this pathway in allergic airway diseases. In this study, we evaluated Orai1 expression in normal and allergic rhinitis (AR) mice airway and spleen. AR models were established by repetitive intraperitoneal sensitization followed by intranasal challenge with ovalbumin. Sneezing was counted, and eosinophils infiltration was analyzed through Luna stain. We performed the analysis of Orai1 protein in airway and spleen by immunohistochemical staining, Western blotting and enzyme-linked immunosorbent assay, and quantitatively examined Orai1 mRNA in the above tissues by real-time reverse transcription-polymerase chain reaction. Sneezes and eosinophil counts in the AR group were increased in comparison to those in the normal group. Orai1 protein was expressed in mucosal epithelium and submucosal glands epithelium of airway, and in immune cells of spleen. The immunostaining appeared stronger in AR mice than that in normal ones. Both the Orai1 protein and mRNA levels showed up-regulation in the AR group compared with those in the normal one. Our results indicate that Orai1 is up-regulated in the airway and spleen in allergic inflammation and may participate in the pathogenesis of allergic rhinitis.

Repression of TNF-alpha-induced IL-8 expression by the glucocorticoid receptor-beta involves inhibition of histone H4 acetylation

Increased expression of a number of proinflammatory genes, including IL-8, is associated with inflammatory conditions such as asthma. Glucocorticoid receptor (GR)beta, one of the GR isoforms, has been suggested to be upregulated in asthma associated with glucocorticoid insensitivity and to work as a dominant negative inhibitor of wild type GRalpha. However, recent data suggest that GRbeta is not a dominant negative inhibitor of GRalpha in the transrepressive process and has its own functional role. We investigated the functional role of GRbeta expression in the suppressive effect of glucocorticoids on tumor necrosis factor (TNF)-alpha-induced IL-8 release in an airway epithelial cell line. GRbeta expression was induced by treatment of epithelial cells with either dexamethasone or TNF-alpha. GRbeta was able to inhibit glucocorticoid-induced transcriptional activation mediated by binding to glucocorticoid response elements (GREs). The suppressive effect of dexamethasone on TNF-alpha-induced IL-8 transcription was not affected by GRbeta overexpression, rather GRbeta had its own weak suppressive activity on TNF-alpha-induced IL-8 expression. Overall histone deacetylase activity and histone acetyltransferase activity were not changed by GRbeta overexpression, but TNF-alpha-induced histone H4 acetylation at the IL-8 promoter was decreased with GRbeta overexpression. This study suggests that GRbeta overexpression does not affect glucocorticoid-induced suppression of IL-8 expression in airway epithelial cells and GRbeta induces its own histone deacetylase activity around IL-8 promoter site.

Increased expression of HLA-DR and CD86 in nasal epithelial cells in allergic rhinitics: antigen presentation to T cells and up-regulation by diesel exhaust particles

BACKGROUND

A proportion of nasal epithelial cells (NEC) in patients with allergic rhinitis (AR) are known to express the major histocompatibility complex Class II molecule (HLA-DR).

OBJECTIVE

We hypothesized that NEC may play a role in antigen presentation to T cells. To elucidate the possible role of NEC in antigen presentation, we examined the expression of HLA-DR, CD80 and CD86 in NEC, their regulation by cytokines and the capacity of NEC to induce antigen-specific proliferation of T cells.

METHODS

We examined the expression of HLA-DR, CD80 and CD86 in nasal epithelial scrapings of patients with seasonal allergic rhinitis (SAR) to Japanese cedar pollen pre-season and in-season, by immunohistochemistry. Next, we examined the effect of IL-1beta, TNF-alpha, (IFN-gamma), IL-4 alpha, IL-13 and diesel exhaust particles (DEP) on the HLA-DR, CD80 and CD86 expression in cultured nasal epithelial cells (CNEC), by flow cytometry. Further, we analysed the capacity of mite antigen (Der f II)-pulsed mitomycin-C-treated CNEC to induce proliferation of autologous T cells from patients with perennial allergic rhinitis.

RESULTS

NEC constitutively expressed HLA-DR and CD86, but not CD80. The expression of HLA-DR and CD86 in NEC was significantly increased in-season, in patients with SAR as compared with that of pre-season. While IFN-gamma up-regulated the expression of HLA-DR, IL-1beta and TNF-alpha up-regulated the expression of CD86 in CNEC. Furthermore, in the presence of mite antigen, CNEC induced the proliferation of autologous peripheral blood T lymphocytes. Anti-CD86 and anti-HLA-DR monoclonal antibody but not anti-CD80 inhibited the epithelial cell-induced T cell proliferation. Stimulation with a combination of DEP and mite antigen significantly up-regulated HLA-DR and CD86 expression in CNEC.

CONCLUSIONS

These studies suggest that NEC in patients with AR may play a role in antigen presentation through the enhanced expression of HLA-DR and CD86. Furthermore, these results suggest the possibility that DEP may enhance the antigen-presenting function of CNEC.

Staphylococcus aureus enterotoxins induce IL-8 secretion by human nasal epithelial cells

Background

Staphylococcus aureus produces a set of proteins which act both as superantigens and toxins. Although their mode of action as superantigens is well understood, little is known about their effects on airway epithelial cells.

Methods

To investigate this problem, primary nasal epithelial cells derived from normal and asthmatic subjects were stimulated with staphylococcal enterotoxin A and B (SEA and SEB) and secreted (supernatants) and cell-associated (cell lysates) IL-8, TNF-α, RANTES and eotaxin were determined by specific ELISAs.

Results

Non-toxic concentrations of SEA and SEB (0.01 μg/ml and 1.0 μg/ml) induced IL-8 secretion after 24 h of culture. Pre-treatment of the cells with IFN-γ (50 IU/ml) resulted in a further increase of IL-8 secretion. In cells from healthy donors pretreated with IFN-γ, SEA at 1.0 μg/ml induced release of 1009 pg/ml IL-8 (733.0–1216 pg/ml, median (range)) while in cells from asthmatic donors the same treatment induced significantly higher IL-8 secretion – 1550 pg/ml (1168.0–2000.0 pg/ml p = 0.04). Normal cells pre-treated with IFN-γ and then cultured with SEB at 1.0 μg/ml released 904.6 pg/ml IL-8 (666.5–1169.0 pg/ml). Cells from asthmatics treated in the same way produced significantly higher amounts of IL-8 – 1665.0 pg/ml (1168.0–2000.0 pg/ml, p = 0.01). Blocking antibodies to MHC class II molecules added to cultures stimulated with SEA and SEB, reduced IL-8 secretion by about 40% in IFN-γ unstimulated cultures and 75% in IFN-γ stimulated cultures. No secretion of TNF-α, RANTES and eotaxin was noted.

Conclusion

Staphylococcal enterotoxins may have a role in the pathogenesis of asthma.

Effect of desloratadine on epithelial cell granulocyte-macrophage colony-stimulating factor secretion and eosinophil survival

BACKGROUND

Second-generation antihistamines are H(1) receptor antagonists and may have additional anti-inflammatory effects.

OBJECTIVE

The aims of the study were to evaluate the effect of desloratadine (DL) on cytokine secretion by epithelial cells from both nasal mucosa (NM) and polyps (NP), and on eosinophil survival primed by epithelial cell secretions.

METHODS

Epithelial cells were cultured and stimulated with fetal bovine serum (FBS), IL-1beta or TNF-alpha with and without DL for 24 h. Culture supernatant cytokines concentration were measured by ELISA. Peripheral blood eosinophils were incubated with human epithelial cell conditioned media (HECM) and DL. Eosinophil survival was assessed by Trypan blue dye exclusion. Results are expressed as mean+/-SEM of cytokine concentration (pg/mL) or eosinophil survival index (%).

RESULTS

FBS increased granulocyte-macrophage colony-stimulating factor (GM-CSF), vascular endothelial growth factor (VEGF), IL-6, IL-8, and TGF-beta(1) secretion in epithelial cell cultures from both NM and NP. Only GM-CSF secretion was significantly (P<0.05) inhibited by a dose-response of DL compared with positive controls, in both NM (10(-5) m: 125+/-36 pg/mL, 10(-6) m: 95+/-22 pg/mL vs. control: 256+/-91 pg/mL, n=6) and NP (10(-5) m: 80+/-29 pg/mL, 10(-6) m: 109+/-45 pg/mL vs. control: 333+/-212 pg/mL, n=6). DL also showed an inhibitory effect on HECM-induced eosinophil survival from both NM and NP. At 72 h, DL significantly (P<0.01) inhibited eosinophil survival induced by HECM from NM (10(-5) m: 19.9+/-5.5%, n=9; 10(-6) m: 28.7+/-7.7%, n=9) and NP (10(-5) m: 6.2+/-2.8%, n=11) compared with HECM alone (NM: 42.1+/-7.3%; NP: 45.3+/-8.1%).

CONCLUSION

The inhibitory effects of DL on epithelial cell GM-CSF secretion and on eosinophil survival induced by epithelial cell secretions, suggest that this H(1) antagonist may regulate eosinophil inflammation in upper airways.

The time course of the bilateral release of cytokines and mediators after unilateral nasal allergen challenge

BACKGROUND

Late phase reactions after allergen challenge can be understood as a correlate of the inflammatory reaction in allergic rhinitis.

METHODS

To investigate which cytokines are involved in it and to dissect direct and indirect effects of nasal allergen challenge, we performed unilateral nasal allergen provocation with the disc method in 12 seasonal allergic volunteers. Symptom scores, nasal secretions and nasal airflow were quantified. In the secretions that were collected in the early phase and for 8 h after provocation, we measured histamine, and the cytokines interleukin (IL)-1beta, IL-8, IL-4, and the natural antagonist of IL-1beta, IL-1 receptor type 1 (IL-1Ra) using enzyme-linked immunosorbent (ELISA)-assays. Control challenges with diluent instead of allergen were performed in all subjects.

RESULTS

We demonstrated a bilateral increase in nasal secretion weights in the early and late phase. Histamine was significantly increased in the early and late phase in nasal secretions from both nostrils. IL-1beta increased in the late phase only, where it was also found on the unchallenged, contralateral side. Its antagonist IL-1Ra was found in very high quantities (1000-fold higher than IL-1beta) but demonstrated only marginal changes after provocation. IL-8 was increased in both nostrils early and late after challenge, whereas IL-4 was significantly elevated in the late phase.

CONCLUSIONS

We described the time course of mediator and cytokine release into nasal secretions after allergen challenge. We hypothesize that the observed indirect effects on the unchallenged, contralateral side can be at least partially attributed to neuronal reflexes.

Effect of glucocorticosteroids on tumour necrosis factor-alpha-induced intercellular adhesion molecule-1 expression in cultured primary human nasal epithelial cells

OBJECTIVE

In order to confirm the direct effect of glucocorticosteroids on epithelial intercellular adhesion molecule-1 (ICAM-1) expression, we examined ICAM-1 expression on primary cultured human nasal epithelial cells (HNECs) at both protein and mRNA levels.

MATERIAL AND METHODS

HNECs were stimulated with recombinant human TNF-alpha (20 pg/mL-20 ng/mL) for specified time periods (0, 12, 24, and 48 h) and ICAM-1 mRNA and the soluble ICAM-1 (sICAM-1) concentrations were measured by quantitative RT-PCR and ELISA, respectively. We also evaluated surface expression of ICAM-1 by flow cytometry 48 h after stimulation and determined the effect of dexamethasone (DEX) on TNF-alpha-induced ICAM-1 expression.

RESULTS

Significant increases in ICAM-1 gene expression in HNECs were initially detected at 24 h, peaking at 48 h after the stimulation. The TNF-mediated-ICAM-1 mRNA and ICAM-1 surface expression at 48 h was significantly inhibited by co-incubation with human recombinant soluble TNF receptor I. Similarly, TNF-alpha-induced release sICAM-1 occurred in a time- and concentration-dependent manner. DEX 10(-6) M attenuated the TNF-alpha-induced ICAM-1 expression at mRNA and protein levels.

CONCLUSIONS

Our finding suggests a potential role for topical steroids in allergic rhinitis in suppressing inflammatory reactions in the nasal mucosa by regulating ICAM-1 expression on nasal epithelium.

Mucosal T-cell phenotypes in persistent atopic and nonatopic rhinitis show an association with mast cells

BACKGROUND

Allergic rhinitis is characterized by selective expansion of T cell subsets with a CD4+ phenotype. Recently, we identified a subpopulation of nonallergic rhinitis subjects with increased epithelial mast cell and eosinophil populations, suggestive of local mucosal allergy. Previously, T cell subsets have not been characterized in this subselection of nonallergic subjects and furthermore, their relationship to mast cell and basophil effector cells remain unidentified.

OBJECTIVE

To determine if a subpopulation of nonallergic subjects with idiopathic rhinitis (IR) have localized allergy confined to their nasal mucosa by comparing the T cell subsets and major histocompatibility complex (MHC) II expressing cells to persistent allergic rhinitis (PAR). Furthermore, the relationship between T cell subsets and mast cells/basophils was investigated.

METHODS

None of the symptomatic patients in this study were clinically allergen-challenged. Nasal turbinate mucosa was removed from patients with PAR, IR and normal controls. Morphometry was performed on immunostained sections for T cell subset populations including CD3+, CD4+, CD8+, CD25+, CD45RA+, CD45RO+, human leucocyte antigen (HLA)-DRalpha (MHC class II), mast cell tryptase and for basophils.

RESULTS

Subjects with persistent allergic rhinitis differed to normal controls in showing significantly increased numbers of total (CD3+), activated (CD25+) and allergen-naïve (CD45RA+) T lymphocytes in their nasal mucosa (P < 0.025). The naïve CD45RA+ memory T cells correlated to mucosal mast cells in PAR (P = 0.03). IR patients differ to allergic subjects in showing significantly reduced numbers of epithelial HLA-DRalpha+ cells (P = 0.007), but increased numbers of CD8+ lymphocytes (P = 0.02). The CD8+ T cells correlated with mucosal mast cell numbers (P = 0.02). In both rhinitis groups, basophils were present in very low numbers obviating the need for statistical analysis.

CONCLUSION

PAR is characterized by increased numbers of CD3+, CD25+ and CD45RA+ T lymphocytes compared with normal mucosa. Allergic and nonallergic rhinitis groups can be separated by significant differences in the number of epithelial antigen presenting cells (APCs) (HLA-DRalpha+) and sub-epithelial activated (CD25+) T cells. Moreover, IR patients do not significantly differ to their allergic counterparts with respect to total (CD3+) and naïve (CD45RA+) T cell numbers, or numbers of epithelial activated (CD25+) lymphocytes. IR subjects show significantly increased numbers of CD8+ lymphocytes compared with control mucosa and although our findings suggest that the initiating inflammatory events may differ, both rhinitis groups show a similarity in pathology involving mucosal mast cells with an association to infiltrating T cells.

Tumor necrosis factor increases MUC1 mRNA in cultured human nasal epithelial cells

OBJECTIVE

Mucins are high molecular weight glycoproteins which are normally expressed on the surface of a variety of epithelia. It is possible that shedding of such molecules from the epithelium could play a role in preventing bacterial colonization at the mucosal surface. Immunohistochemical and reverse transcriptase polymerase chain reaction(RT-PCR) analyses of human inferior turbinates have shown the existence of MUC1 mucin in nasal mucosa. However, the regulatory mechanisms of MUC1 mucin are poorly understood. In order to clarify the modulation of mucin gene expression, we developed a real-time semi-quantitative RT-PCR based on TaqMan fluorescence methodology to quantify MUC1 mRNA in primary cultured human nasal epithelial cells (HNECs).

MATERIAL AND METHODS

HNECs were stimulated with recombinant human tumor necrosis factor (TNF)-alpha (20 pg/ml to 20 ng/ml) for specified time periods (0, 12, 24 and 48 h) and MUC1 mRNA was determined by means of semi-quantitative RT-PCR.

RESULTS

Significant increases in MUC1 gene expression in HNECs were initially detected at 12 h, peaking at 24 h after stimulation. TNF-mediated MUCI mRNA expression at 24 h was significantly inhibited by co-incubation with human recombinant soluble TNF receptor.

CONCLUSIONS

TNF-mediated MUC1 gene expression may contribute to the pathogenesis of human inflammatory upper airway disorders. Also, our mucin mRNA real-time PCR provides a quantitative method for investigating the regulation of mucin gene expression in both healthy and diseased samples.

Granulocyte macrophage colony-stimulating factor-driven respiratory mucosal sensitization induces Th2 differentiation and function independently of interleukin-4

The development of T helper (Th)2 responses is a key step in the pathogenesis of asthma. Interleukin (IL)-4 is thought to be important, although not strictly necessary, for Th2 differentiation, although triggers of IL-4-independent Th2 polarization have not been identified. We examined whether IL-4 is necessary for Th2-polarized responses during granulocyte macrophage colony-stimulating factor (GM-CSF)-driven respiratory mucosal sensitization. Balb/c wild type (WT) or IL-4 knockout (4KO) mice were exposed to aerosolized ovalbumin (OVA) in the context of airway GM-CSF expression. We examined the extent of Th2 polarization using real-time quantitative polymerase chain reaction on lymph node mRNA, flow cytometric analysis of lung Th cells, and measurement of cells, cytokines, and immunoglobulins in bronchoalveolar lavage (BAL) and serum. GATA-3 and CCR3, -4, and -8 were expressed in the lymph nodes of WT and 4KO mice at similar levels, as were IL-5 and IL-13 levels in the BAL, T1/ST2 on lung Th cells, and BAL eosinophils after recall challenge. With the exception of immunoglobulin production, expression of GATA-3, CCR-3, -4, -8, IL-5, and T1/ST2, and the generation of blood eosinophilia, were intact in mice doubly deficient in both IL-4 and IL-13. We conclude that IL-4 is not required for the generation of Th2-polarized responses in the presence of GM-CSF.

Mechanisms of allergic rhinitis

The pathogenesis of allergic rhinitis can be better appreciated by understanding the numerous protective mechanisms available for mucosal defense. The system of TH2 lymphocytes, IgE production, mast cell degranulation, eosinophil infiltration, and resident cell responses are central to our understanding and treatment of allergic rhinitis. Histamine remains preeminent in causing the cardinal symptoms of the immediate allergic reaction: itching, watery discharge, and nasal swelling. Recruitment and activation mechanisms responsible for the late-phase allergic response are also reviewed.

Dysregulated activation of activator protein 1 in keratinocytes of atopic dermatitis patients with enhanced expression of granulocyte/macrophage-colony stimulating factor

Keratinocytes of patients with atopic dermatitis produce high amounts of granulocyte/macrophage colony-stimulating factor, a factor essential for dendritic cell function and thus for the development of skin immune responses. In contrast to keratinocytes cultured from nonatopic, healthy individuals, granulocyte/macrophage colony-stimulating factor mRNA could be detected in unstimulated cultures of atopic dermatitis keratinocytes, and phorbol myristate acetate induced much greater granulocyte/macrophage colony-stimulating factor mRNA levels in these cells, although the decay kinetics were not altered. Using reporter gene (chloramphenicol acetyl transferase) analysis, a minimal granulocyte/macrophage colony-stimulating factor promoter was shown to confer constitutive and phorbol-myristate-acetate-induced regulation of transcriptional activity in keratinocytes, and significantly higher levels of chloramphenicol acetyl transferase activity were measured in lysates of unstimulated and phorbol-myristate-acetate-treated atopic dermatitis keratinocytes than in control keratinocyte cultures. Electrophoretic mobility shift assays showed that low levels of NF-kappa B binding activity could be induced by phorbol myristate acetate in both normal and atopic dermatitis keratinocytes. By contrast, activator protein 1 complexes were efficiently induced, and they were invariably present at higher levels in nuclear lysates of atopic dermatitis keratinocytes. Atopic dermatitis keratinocyte nuclear lysates had higher constitutive levels of c-Jun, and phorbol myristate acetate promoted an earlier and stronger expression of c-Jun, JunB, and of the phosphorylated forms of c-Fos. A dysregulated activation of activator protein 1 may be implicated in the molecular mechanisms leading to increased granulocyte/macrophage colony-stimulating factor expression in atopic dermatitis keratinocytes. J Invest Dermatol 115:1134-1143 2000

Recruitment of T cells to the lung in response to antigen challenge

T-cell recruitment to the lungs is thought to represent a key step in airway allergic inflammation. T cells coordinate and amplify effector functions of antigen-specific and nonspecific proinflammatory cells, such as B cells and eosinophils. The T(H)2 cell, in particular, promotes allergic inflammation through the expression of IL-4, IL-5, and IL-13, proinflammatory cytokines that are important in the induction of B-cell switching and the promotion of eosinophil proliferation and survival. This cytokine profile has been implicated in asthma; elevations in bronchoalveolar lavage IL-4 and IL-5 levels have been observed in asthmatic patients. The recruitment of T(H) cells to the site of allergic inflammation (lung) is the subject of this review.

Analysis of local cytokine gene expression in patients with allergic rhinitis treated with CO2 laser surgery

OBJECTIVES/HYPOTHESIS

Laser surgery of the inferior turbinates has become a popular surgical treatment for patients with allergic rhinitis, particularly for those who have persistent nasal obstruction and do not respond well to pharmacological therapy. The aim of this study was to investigate the effects of the laser surgery on local cytokine gene expression at the mucosal surface in relation to the improvement of nasal symptoms.

STUDY DESIGN

A prospective analysis of 25 patients with allergic rhinitis caused by the house dust mite who underwent laser surgery twice with a 1-month interval on an outpatient basis. Fifteen healthy volunteers served as normal control subjects.

METHODS

Improvement of the nasal symptoms was evaluated on a graded scale. Nasal mucosal cells were obtained by brushing from the inferior turbinate at each visit. The expression of messenger RNA (mRNA) encoding granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin (IL)-6, IL-8, RANTES (regulated on activation, normal T-cell expressed and secreted), and eotaxin was semiquantitatively analyzed by reverse transcription-polymerase chain reaction (RT-PCR).

RESULTS

Two months after treatment, the nasal symptom scores significantly decreased from baseline. The decrease was most apparent in nasal obstruction. RT-PCR analysis revealed that a significant decrease in IL-8 and RANTES expression (P < .001 and P = .012, respectively) was observed after successive laser treatment, and the reduction in these cytokines was significantly correlated. On the other hand, mRNA expression of GM-CSF, IL-6, and eotaxin remained unchanged.

CONCLUSIONS

This study provided evidence that the expression of local inflammatory cytokines can be attenuated in part by CO2 laser treatment, which may be closely related to the clinical effectiveness of this procedure.

Immediate effect of topical budesonide on allergen challenge-induced nasal mucosal fluid levels of granulocyte-macrophage colony-stimulating factor and interleukin-5

The nasal antiinflammatory effects produced by maintenance treatment with topical steroids include reduced production of cytokines. The present study explored nasal mucosal effects induced during the first 9 h after a single dose of topical budesonide. Nine subjects with allergic rhinitis due to birch or timothy pollen were given budesonide (256 microg; Rhinocort Aqua) or placebo in a double-blind, randomized, crossover (4 wk washout) manner. Nasal allergen challenges were performed 30 min after the steroid/placebo pretreatment. Before and 30 min, 1, 3, 5, 7, and 9 h after challenge, filter paper strips were placed on the nasal septum and inferior turbinates for 10 min to sample undiluted mucosal fluids. Strips were then extracted in 1 ml buffer for cytokine analysis (ELISA). Allergen challenge produced acute nasal symptoms that peaked at 30 min and then tapered off. Conversely, both GM-CSF and IL-5 were increased only at 3, 5, 7 and 9 h (p < 0.05 compared with baseline). Budesonide did not affect the nasal symptoms but inhibited (p < 0. 05; compared with placebo treatment) the allergen challenge-induced mucosal output of GM-CSF and IL-5. These data demonstrate that GM-CSF and IL-5 are induced in a nonsymptomatic, late phase response to nasal allergen challenge, and that this cytokine response is prevented by single dose budesonide pretreatment.

Induction of tumor necrosis factor alpha and interleukin-8 gene expression in bronchial epithelial cells by toxic shock syndrome toxin 1

Major histocompatibility complex (MHC) class II engagement by toxic shock syndrome toxin 1 (TSST-1) transduces signals leading to proinflammatory cytokine gene expression (tumor necrosis factor alpha [TNF-alpha]) in human monocytes. To study the proinflammatory role of MHC class II molecules expressed by bronchial epithelial cells (BEC), primary human BEC were isolated from surgical bronchial samples, expanded in vitro, and cultured in the presence or absence of gamma interferon (IFN-gamma) for 48 h. (125)I-TSST-1 binding to BEC pretreated with IFN-gamma was inhibited up to 97% by anti-MHC class II monoclonal antibody 3B12, indicating that in BEC also MHC class II molecules were targets for the staphylococcal exotoxin. As analyzed by a quantitative reverse transcriptase PCR, a 1-h stimulation of BEC with TSST-1 resulted in a vigorous expression of TNF-alpha and interleukin-8 (IL-8) genes. TNF-alpha and IL-8 expression was optimal in BEC pretreated with 50 IU of IFN-gamma/ml, whereas TSST-1 stimulation of BEC pretreated with 200 IU of IFN-gamma/ml failed to enhance either TNF-alpha or IL-8 transcripts. In a time course study, peak expression of TNF-alpha and IL-8 mRNA was reached 6 h after TSST-1 stimulation. These results demonstrate that bacterial superantigen TSST-1 binds to MHC molecules on BEC and induces TNF-alpha and IL-8 gene expression upon engagement of MHC class II molecules on BEC, thus contributing to the perpetuation of bronchial mucosa inflammation via chemokine or cytokine gene expression.

Allergic inflammation in upper and lower airways

OBJECTIVE

The primary reason for this review is to discuss the relationship between upper and lower airways at various levels with the emphasis on common pathophysiologic mechanisms, and how treatment of the upper airways will benefit the lower airways.

DATA SOURCES

The main source of information is derived from original articles and books, with an extensive bibliography included.

STUDY SELECTION

Studies were derived almost exclusively from articles and reviews in peer-reviewed journals.

RESULTS

The prevalence of rhinitis and asthma are both increasing. Common to both the upper and lower airways are the triggers, many of the inflammatory cells and mediators, and the treatment modalities. By contrast, there are organ-specific differences in the reaction to various stimuli in the nose or lung, with each organ manifesting its own vocabulary of response.

CONCLUSIONS

There are meaningful relationships between upper and lower airways at various levels of our understanding. Differential responses to medications help us better understand pathogenic mechanisms in rhinitis and asthma. Further, treatment of the upper airways provides additional benefit to the lower airways.

Effect of topical corticosteroids on seasonal increases in epithelial eosinophils and mast cells in allergic rhinitis: a comparison of nasal brush and biopsy methods

BACKGROUND

Nasal brushing and nasal biopsy are well-tolerated sampling techniques. Seasonal grass pollen-induced rhinitis is characterized by epithelial mast cell infiltration and seasonal increases in both epithelial and sub-mucosal eosinophils.

OBJECTIVE

To compare the ability of the nasal brush and nasal biopsy techniques to detect natural seasonal increases in eosinophils and mast cells, and to assess the influence of topical corticosteroid.

METHODS

Nasal brush samples and nasal biopsies were collected from 46 grass pollen-sensitive seasonal rhinitis patients before the grass pollen season and at the peak of the pollen season following 6 weeks' treatment with either fluticasone propionate aqueous nasal spray (200 microg, twice daily) or placebo nasal spray.

RESULTS

Placebo patients showed seasonal increases in epithelial eosinophils both with nasal brushing (P < 0.0001) and biopsy (P < 0.001). Epithelial mast cell numbers also increased during the pollen season as detectable by brushing (P < 0.0001) and biopsy (P < 0.03). Changes in cell numbers measured by nasal brushing correlated with those observed with nasal biopsy, both for eosinophils and mast cells (P < 0.05). Sub-mucosal eosinophils but not mast cells also increased during the pollen season (P < 0.002). Nasal brushing and biopsy revealed that fluticasone treatment inhibited seasonal increases in epithelial eosinophils (P < 0.00001) and epithelial infiltration by mast cells (nasal brushing P < 0.00001 and nasal biopsy P < 0.01). Fluticasone also inhibited seasonal increases in sub-mucosal eosinophils (P < 0.001) and significantly reduced nasal symptoms (P < 0.001).

CONCLUSION

Nasal brushing harvests sufficient inflammatory cells from the surface of the nasal mucosa to be used in lieu of nasal biopsies in observation of the effect of drugs on the nasal epithelium.

Pathophysiology of the inflammatory response

Airway allergic reactions enlist diverse cells and a multitude of chemical mediators that are responsible for the clinical symptoms of allergic rhinitis and asthma. Experiments in vitro and in animal models, as well as increasingly numerous studies in atopic human subjects, are revealing that an orchestrated continuum of cellular activities leading to airway allergic inflammation is set in motion in genetically predisposed individuals at the first exposure to a novel antigen. This sensitization step likely depends on differentiation of and cytokine release by T(H)2 lymphocytes. Among T(H)2-derived cytokines, IL-4 potently enhances B-lymphocyte generation of immunoglobulin E antibodies. The attachment of these antibodies to specific receptors on airway mast cells sets the stage for an acute inflammatory response on subsequent antigen exposure because IgE cross-linking by a bound antigen activates mast cells to release numerous inflammatory mediators. These mast cell-derived mediators collectively produce acute-phase clinical symptoms by enhancing vascular leak, bronchospasm, and activation of nociceptive neurons linked to parasympathetic reflexes. Simultaneously, some mast cell mediators up-regulate expression on endothelial cells of adhesion molecules for leukocytes (eosinophils, but also basophils and lymphocytes), which are key elements in the late-phase allergic response. Chemoattractant molecules released during the acute phase draw these leukocytes to airways during a relatively symptom-free recruitment phase, where they later release a plethora of cytokines and tissue-damaging proteases that herald a second wave of airway inflammatory trauma (late-phase response). The repetition of these processes, with the possible establishment in airway mucosa of memory T lymphocytes and eosinophils that are maintained by paracrine and autocrine cytokine stimulation, may account for airway hypersensitivity and chronic airway symptoms.

Intranasal Exposure to Protein Antigen Induces Immunological Tolerance Mediated by Functionally Disabled CD4+ T Cells

In this study we examined the immunological parameters underlying the natural immunity to inhaled nonpathogenic proteins. We addressed this question by examining the effect of intranasal exposure to OVA in both wild-type mice and mice reconstituted with OVA-TCR transgenic CD4+ T cells. Intranasal administration of OVA induced an initial phase of activation during which CD4+ T cells were capable of proliferating and producing cytokines. Although many of the OVA-specific CD4+ T cells were subsequently depleted from the lymphoid organs, a stable population of such T cells survived but remained refractory to antigenic rechallenge. The unresponsive state was not associated with immune deviation due to selective secretion of Th1- or Th2-type cytokines, and the presence of regulatory CD8+ T cells was not required. Moreover, neutralization of the immunosuppressive cytokines IL-10 and TGF-β did not abrogate the induction of tolerance. Inhibition of the interaction of T cells with CD86, but not CD80, at the time of exposure to intranasal Ag prevented the development of unresponsiveness, while selective blockade of CTLA-4 had no effect. Our results suggest that intranasal exposure to Ags results in immunological tolerance mediated by functionally impaired CD4+ T cells via a costimulatory pathway that requires CD86.

Modulation of HLA-DR antigen and ICAM-1 molecule expression on airway epithelial cells by sodium nedocromil

OBJECTIVE

To test in vitro and in vivo the hypothesis that sodium nedocromil could modulate the expression of surface molecules on airway epithelial cells.

METHODS

Human bronchial epithelial cells, obtained from surgically resected bronchi, were cultured and stimulated with recombinant IFN-gamma in the presence of sodium nedocromil. The intensity of the expression of surface molecules HLA-DR and ICAM-1 molecules on bronchial epithelial cells in vitro, was quantified by specific antibody staining and flow-cytometry analysis. Furthermore, we studied the effect of the drug on airway inflammation in vivo and on allergic rhinitis patients sensitized to house dust mites. Nasal epithelial cells were collected by brushing, at baseline and 2 to 3 weeks after treatment with sodium nedocromil. The expression of HLA-DR and ICAM-1 molecules was measured by flow-cytometry, and the proportions of neutrophils and eosinophils "contaminating" the epithelial cells evaluated by light microscopy examination of nasal brushings.

RESULTS

The enhanced HLA-DR and ICAM-1 expression, induced by IFN-gamma, was effectively downregulated, in a dose-dependent manner, by sodium nedocromil. At all the concentrations tested (10(-9) to 10(-4) M), the inhibitory activity of the drug was stronger on HLA-DR than on ICAM-1 expression (P<.05, all comparisons). As compared with healthy subjects, patients with allergic rhinitis had a higher expression of HLA-DR (P<.05) but not of ICAM-1 molecules (P>.05) on nasal epithelial cells, and higher proportions of nasal eosinophils (P<.05). Treatment with sodium nedocromil downregulated the expression of HLA-DR (P<.05), but not of ICAM-1 (P>.05), and induced a mild, but not statistically significant, decrease of nasal eosinophilia (P>.05).

CONCLUSION

These data demonstrate that the antiinflammatory activity of sodium nedocromil may include modulation of surface molecule expression on airway epithelial cells.

Elevated soluble tumor necrosis factor receptor levels in seasonal allergic rhinitis patients

In this study, we examined the symptom scores and tumor necrosis factor-alpha (TNF-alpha), p55 soluble tumor necrosis factor receptor (sTNFR1), and p75 soluble tumor necrosis factor receptor (sTNFR2) levels in the sera and nasal epithelial lining fluids (ELF) of 20 patients with Japanese cedar pollinosis from the pre- to the postseason period, and compared the results with those of 10 nonallergic control subjects. The symptom scores of the allergic subjects were significantly (P<0.01) higher than those of the nonallergic subjects during the early stage and mid-stage of the season. There were no statistical differences between the allergic and nonallergic subjects in the TNF-alpha levels in sera and ELF from the pre- to the postseason. In the allergic subjects, however, the levels of sTNFR1 and sTNFR2 in ELF were significantly elevated during the early stage (P<0.05) and mid-stage (P<0.01) of the season, whereas those in sera did not change from the pre- to the post-season period. The levels of TNF-alpha in ELF were more than 10 times higher than those in sera, whereas the levels of sTNFR1 and sTNFR2 in ELF were less than half of those in sera in the allergic and nonallergic subjects. These results suggest that sTNFR1 and sTNFR2 may play a role in the pathogenesis of nasal allergic reaction.

Hyperresponsiveness in the human nasal airway: new targets for the treatment of allergic airway disease

Allergic rhinitis is a condition which affects over 15% of the population in the United Kingdom. The pathological process involves two stages: nasal inflammation, and the development of nasal airway hyperresponsiveness (AHR) to allergen and a number of other stimuli. This results in the amplification of any subsequent allergic reaction, contributing to the chronic allergic state. A number of different hypotheses have been proposed to explain the underlying mechanism of AHR, including a role for eosinophil-derived proteins, free radicals and neuropeptides. While there may be a number of independent pathways which can result in AHR, evidence obtained from both animal models and in vivo experiments in humans indicate that some mediators may interact with one another, resulting in AHR. Further research into these interactions may open new avenues for the pharmacological treatment of chronic allergic rhinitis, and possibly other allergic airway diseases.

Stem cell factor in nasal polyposis and allergic rhinitis: increased expression by structural cells is suppressed by in vivo topical corticosteroids

BACKGROUND

Mast cells are increased in nasal polyp (Np) and allergic rhinitis (AR) tissue and are suppressed by topical corticosteroid treatment. Stem cell factor (SCF), a mast cell growth and survival factor, may explain these phenomena.

OBJECTIVE

We investigated structural cell gene expression and production of SCF in nasal tissues in patients who had received and who had not received in vivo intranasal corticosteroid therapy.

METHODS

Northern blot analyses for messenger RNA and ELISA for biologically active SCF protein from cultured Np epithelial cells and fibroblasts were performed. Immunostaining for SCF in cultured and tissue nasal structural cells in the presence or absence of steroid treatment was also performed.

RESULTS

We detected significant expression of SCF mRNA and protein by cultured Np epithelial cells and Np fibroblasts; Np fibroblast SCF supported the differentiation of mast cells in vitro. There were more immunoreactive SCF-positive Np epithelial cells in patients with AR than in control subjects (97.2 +/- 2.8 vs 45.6 +/- 22.0%; p < 0.0001). SCF that could be immunostained was significantly diminished overall in Np structural cells in the group given in vivo steroid treatment, with a modest (trend to significant) effect on any given cell type analyzed. In vitro treatment with budesonide of SCF-producing fibroblasts demonstrated inhibition of unstimulated, primary Np fibroblasts but not of IL-1-stimulated fibroblasts or transformed cell lines.

CONCLUSIONS

Human Np and AR tissue structural cells express and produce increased SCF. Our in vitro studies suggest that intranasal steroids blunt SCF expression in Nps, an effect that may be responsible for a decrease in mast cells and symptoms.

Pathogenesis of allergic rhinitis

Allergic rhinitis is an increasing problem for which new and exciting therapies are being developed. These can be understood through an appreciation of the newer concepts of pathogenesis of allergic rhinitis. Allergen induces Th2 lymphocyte proliferation in persons with allergies with the release of their characteristic combination of cytokines including IL-3, IL-4, IL-5, IL-9, IL-10, and IL-13. These substances promote IgE and mast cell production. Mucosal mast cells that produce IL-4, IL-5, IL-6, and tryptase proliferate in the allergic epithelium. Inflammatory mediators and cytokines upregulate endothelial cell adhesion markers, such as vascular cell adhesion molecule-1. Chemoattractants, including eotaxin, IL-5, and RANTES, lead to characteristic infiltration by eosinophils, basophils, Th2 lymphocytes, and mast cells in chronic allergic rhinitis. As our understanding of the basic pathophysiologic features of allergic rhinitis continues to increase, the development of new diagnostic and treatment strategies may allow more effective modulation of the immune system, the atopic disease process, and the associated morbidity.