APOE epsilon4 and the cognitive genetics of multiple sclerosis

BACKGROUND

Evidence linking APOE to myelin repair, neuronal plasticity, and cerebral inflammatory processes suggests that it may be relevant in multiple sclerosis (MS). The purpose of this study was to determine whether the epsilon4 allele of APOE is associated with cognitive deficits in patients with MS.

METHOD

Using a case-control design, 50 patients with MS with the epsilon4 allele (epsilon4+) and 50 epsilon4-negative (epsilon4-) patients with MS were tested using a comprehensive battery of tests evaluating the cognitive domains most often affected in MS.

RESULTS

The epsilon4+ and epsilon4- patients with MS were well-matched with respect to demographic variables (age, gender, ethnicity, education, employment status, premorbid IQ) and disease variables (disease course, disease duration, Expanded Disability Status Scale, 25-foot timed walk, 9-hole pegboard test). In addition, the groups were similar in depressive symptoms, in the proportion of patients receiving disease-modifying therapy, and in carriage of the APOE epsilon2 allele. Results showed that none of the 11 cognitive outcome variables differed between epsilon4+ and epsilon4- patients with MS. Cognitive measures were also unrelated to epsilon4 interactions with age and gender. The incidence of overall cognitive dysfunction did not differ between epsilon4+ and epsilon4- groups, nor did failure on any test, and epsilon4 carriage was not a significant predictor of any adverse cognitive outcome. These negative results endured with the exclusion of epsilon2+ subjects from the analyses.

CONCLUSION

This study does not support a role for the epsilon4 allele in cognitive dysfunction in multiple sclerosis.

Prefrontal cortex and episodic memory retrieval mode

A multistudy analysis of positron emission tomography data identified three right prefrontal and two left prefrontal cortical sites, as well as a region in the anterior cingulate gyrus, where neuronal activity is correlated with the maintenance of episodic memory retrieval mode (REMO), a basic and necessary condition of remembering past experiences. The right prefrontal sites were near the frontal pole [Brodmann's area (BA) 10], frontal operculum (BA 47/45), and lateral dorsal area (BA 8/9). The two left prefrontal sites were homotopical with the right frontal pole and opercular sites. The same kinds of REMO sites were not observed in any other cerebral region. Many previous functional neuroimaging studies of episodic memory retrieval have reported activations near the frontal REMO sites identified here, although their function has not been clear. Many of these, too, probably have signaled their involvement in REMO. We propose that REMO activations largely if not entirely account for the frontal hemispheric asymmetry of retrieval as described by the original hemispheric encoding retrieval asymmetry model.

In vivo expression of signal transducer and activator of transcription factor 6 (STAT6) in nasal mucosa from atopic allergic rhinitis: effect of topical corticosteroids

BACKGROUND

The allergen-induced late nasal response is associated with a high local expression of interleukin (IL) -4, a TH2-type cytokine implicated in immunoglobulin (Ig) E production, tissue eosinophilia and other events considered to be relevant to allergic inflammation. Interaction of IL-4 with its receptor activates at least two distinct signalling pathways that culminate in the transcription of specific target genes. One pathway involves the activation of a transcription factor termed signal transducer and activator of transcription factor 6 (STAT6).

OBJECTIVE

To investigate the expression of STAT6 in the allergen-induced late nasal response and to examine the effect of local steroid treatment on STAT6 expression.

METHODS

Inferior turbinate biopsies were obtained from subjects with allergic rhinitis out of the allergen season. Subjects were then randomized into topical steroid- (n = 6) and placebo-treated (n = 6) groups in a double-blind fashion. After a 6-week treatment period, a second nasal biopsy was performed 24 h after local challenge with allergen. STAT6 immunoreactivity was examined in biopsy specimens by immunocytochemistry using a specific monoclonal antibody. Numbers of inflammatory cells (CD3+ T cells and MBP+ eosinophils) and IL-4 mRNA+ cells were investigated by immunocytochemistry and in situ hybridization, respectively.

RESULTS

STAT6 immunoreactivity was detected in all biopsies studied and localized predominantly to inflammatory tissue of the nasal mucosa. After allergen challenge, expression of STAT6 was markedly increased in placebo-treated patients (P < 0.01). By confocal microscopy, STAT6 was localized to the cytoplasm and the nucleus of positively-staining cells. The allergen-induced increase in STAT6 immunoreactive cells was not observed in the steroid-treated patients. The change in STAT6 immunoreactivity after allergen challenge correlated significantly with the change in numbers IL-4 mRNA+ cells (r = 0.74, P = 0.006) and CD3+ T cells (r = 0.76, P = 0. 004), but not MBP+ eosinophils.

CONCLUSION

This study provides the first evidence of increased STAT6 expression in vivo in human allergic inflammation. The results support a role for STAT6 and IL-4 in the pathogenesis of late nasal response and show that decreases in STAT6 expression parallel the reduction in IL-4 expression that occurs with topical steroid treatment.

Constitutive and cytokine-stimulated expression of eotaxin by human airway smooth muscle cells

Airway eosinophilia is a prominent feature of asthma that is believed to be mediated in part through the expression of specific chemokines such as eotaxin, a potent eosinophil chemoattractant that is highly expressed by epithelial cells and inflammatory cells in asthmatic airways. Airway smooth muscle (ASM) has been identified as a potential source of cytokines and chemokines. The aim of the present study was to examine the capacity of human ASM to express eotaxin. We demonstrate that airway myocytes constitutively express eotaxin mRNA as detected by RT-PCR. Treatment of ASM for 24 h with different concentrations of TNF-alpha and IL-1beta alone or in combination enhanced the accumulation of eotaxin transcripts. Maximal mRNA expression of eotaxin was shown at 12 and 24 h following IL-1beta and TNF-alpha stimulation, respectively. The presence of immunoreactive eotaxin was demonstrated by immunocytochemistry, and constitutive and cytokine-stimulated release of eotaxin was confirmed in ASM culture supernatants by ELISA. Strong signals for eotaxin mRNA and immunoreactivity were observed in vivo in smooth muscle in asthmatic airways. In addition, chemotaxis assays demonstrated the presence of chemoattractant activity for eosinophils and PBMCs in ASM supernatants. The chemotactic responses of eosinophils were partly inhibited with antibodies directed against eotaxin or RANTES, and a combined blockade of both chemokines causes > 70% inhibition of eosinophil chemotaxis. The results of this study suggest that ASM may contribute to airway inflammation in asthma through the production and release of eotaxin.

Phenotype of IL-16-producing cells in bronchial mucosa: evidence for the human eosinophil and mast cell as cellular sources of IL-16 in asthma

BACKGROUND

We have previously shown increased expression of the CD4+ cell chemoattractant interleukin (IL)-16 in bronchial biopsies of atopic asthmatic subjects compared to normal controls. IL-16 immunoreactive cells were identified as both epithelial cells and non-epithelial inflammatory cells. The aim of this study was to characterize and compare the phenotype of non-epithelial inflammatory cells that express IL-16 immunoreactivity in bronchial biopsies from non-atopic normal controls and atopic asthmatic subjects.

METHODS

Sections from endobronchial biopsies obtained from non-atopic normal controls and atopic asthmatics were processed for double immunocytochemistry. IL-16 immunoreactivity was assessed using a polyclonal anti-IL-16 antibody and the avidin-biotin complex-diaminobenzidine method. The phenotype of IL-16 immunoreactive cells was assessed using anti-CD3, anti-MBP, anti-tryptase and anti-CD68 mAbs and the alkaline phosphatase complex-Fast Red method.

RESULTS

In normal subjects, the majority of IL-16 immunoreactive cells were CD3+ T cells (71.1+/-10.3%) and CD68+ macrophages (22.4+/-8.1%). IL-16 immunoreactivity coexpressed with tryptase+ mast cells in 4 of 7 normal subjects whereas IL-16 immunoreactivity coexpressed with MBP+ eosinophils in only 1 normal subject. In atopic asthmatic subjects, IL-16 immunoreactive cells were mainly CD3+ T cells (60.8+/-8.7%) and MPB+ eosinophils (16.8+/-8.2%). IL-16 immunoreactivity also coexpressed with tryptase+ mast cells (10.6+/-4.0%) in all asthmatic subjects. The number of IL-16 immunoreactive cells that coexpressed MBP was higher in asthmatic subjects compared to normal controls (p = 0.003).

CONCLUSION

Our data show that T cells are the major non-epithelial cellular source of IL-16 in normal and asthmatic airways. Eosinophils and mast cells comprised other potential cellular sources of IL-16 in asthmatic airways.

Gene expression of the GATA-3 transcription factor is increased in atopic asthma

BACKGROUND

High expression of IL-5 by T cells in the airways of asthmatic individuals is believed to play a fundamental role in the eosinophilia associated with this disease. Recently, the transcription factor GATA-3 was shown to be critical for IL-5 gene expression in TH2 cells in vitro.

OBJECTIVE

Our aim was to examine the expression of GATA-3 mRNA and its colocalization within the airways of asthmatic and nonasthmatic individuals.

METHODS

We investigated the association between GATA-3 gene expression, airway inflammatory cells, and IL-5 gene expression in bronchoalveolar lavage fluid and bronchial biopsy specimens from atopic asthmatic subjects (n = 10) and normal control subjects (n = 10).

RESULTS

We report that GATA-3 mRNA expression is significantly increased in the airways of asthmatic subjects compared with those of normal control subjects (P <.001). Numbers of cells expressing GATA-3 transcripts correlated significantly with reduced airway caliber (P <.05) and airways hyperresponsiveness (P <.05) in asthmatic subjects. Colocalization studies showed that the majority (approximately 60% to 90%) of GATA-3 mRNA+ cells in asthmatic airways were CD3(+) T cells, with smaller contributions from major basic protein+ eosinophils and tryptase+ mast cells. The density of GATA-3 mRNA+ cells correlated significantly with the numbers of cells expressing IL-5 mRNA (P <.001, r = 0.879 for bronchoalveolar lavage fluid; P <. 05, r = 0.721 for biopsy specimens). Furthermore, double in situ hybridization demonstrated that approximately 76% of GATA-3 mRNA+ cells coexpressed IL-5 mRNA and that 91% of IL-5 mRNA+ cells coexpressed GATA-3 mRNA.

CONCLUSION

The results of this study provide the first evidence of increased GATA-3 gene expression in association with IL-5 mRNA+ cells in asthmatic airways. These findings support a causal association between augmented GATA-3 expression and dysregulated IL-5 expression in atopic asthma.

Expression of the IL-4 receptor alpha-subunit is increased in bronchial biopsy specimens from atopic and nonatopic asthmatic subjects

BACKGROUND

Recent studies have provided evidence for increased IL-4 expression in the airways of atopic and nonatopic asthmatic subjects. IL-4 is believed to perform important regulatory roles in asthma; however, the expression of the IL-4 receptor has not been investigated. In this study we examined the mRNA and protein expression of the specific alpha-subunit of the IL-4 receptor (alphaIL-4R) in bronchial biopsy specimens obtained from atopic and nonatopic asthmatic subjects.

METHODS

Asthmatic subjects and nonasthmatic control subjects were recruited, and lung function measurements were performed before bronchoscopy. Endobronchial biopsy specimens were examined for the presence of alphaIL-4R mRNA and immunoreactivity by using in situ hybridization and immunocytochemistry, respectively.

RESULTS

alphaIL-4R mRNA-positive and immunoreactive cells were detected in the epithelium and subepithelium in biopsy specimens from all subjects. Expression of alphaIL-4R mRNA and protein was significantly increased in the epithelium and subepithelium of biopsy specimens from atopic asthmatic subjects compared with atopic control subjects (P <.05 and P <.001, respectively). Epithelial alphaIL-4R mRNA expression and immunoreactivity did not differ significantly between nonatopic asthmatic subjects and nonatopic control subjects. Although the numbers of alphaIL-4R mRNA-positive cells were augmented in the submucosa of intrinsic asthmatic subjects compared with nonatopic control subjects (P <.05), alphaIL-4R immunoreactivity did not differ significantly between these groups. Increased alphaIL-4R immunoreactive signals were also detected in the endothelial cell layer in both atopic and intrinsic asthmatic subjects compared with atopic and nonatopic control subjects, respectively (P <.05). Combined in situ hybridization immunocytochemistry performed on biopsy sections from asthmatic and control subjects demonstrated alphaIL-4R mRNA expression in CD3-positive T cells and tryptasepositive mast cells, with T cells comprising the larger proportion of alphaIL-4R mRNA-positive cells. Numbers of alphaIL-4R mRNA-positive or immunoreactive cells did not correlate with CD3-positive cell numbers, numbers of IL-4 mRNA-positive cells, or indices of pulmonary function.

CONCLUSION

These results demonstrate constitutive alphaIL-4R expression in normal airways and enhanced expression in airway tissue from asthmatic individuals.

Monocyte chemotactic protein expression in allergy and non-allergy-associated chronic sinusitis

OBJECTIVE

Chronic sinusitis (CS) is characterized by inflammatory mucosal thickening and polyp formation with a predominantly eosinophilic infiltrate. Chemokines are a novel group of inflammatory mediators capable of attracting specific inflammatory cell populations. Monocyte chemotactic proteins (MCP) are a subfamily of chemokines (MCP-1, MCP-2, MCP-3, and MCP-4) that share a number of functional properties including chemotactic activity for eosinophils. The purpose of this study was to investigate the expression of the MCP family of chemokines in allergy and non-allergy-associated chronic sinusitis using the technique of immunocytochemistry.

METHOD

We examined the expression of MCP-1, MCP-3, and MCP-4 in biopsies from the ethmoid sinuses of patients with CS and normal controls.

RESULTS

MCPs were localized to the epithelial cells and a subset of inflammatory cells within the mucosa. The expression of both MCP-3 and MCP-4 immunoreactivity were significantly increased in patients with both allergy and non-allergy-associated CS compared to normal controls (p < .001). There was no significant difference in the expression of MCP-1 in nasal biopsies from individuals with CS and normals. The level of expression of MCP-3 and MCP-4 correlated with eosinophil (p < .001) and CD4-positive T-cell infiltrate (p < .001) but not with CD8-positive T-cell infiltration.

CONCLUSIONS

Our data suggest biologic redundancy in the expression of eosinophil chemoattractants in CS and a potential role for MCP-3 and MCP-4, but not MCP-1, in the pathophysiology of this disorder. Further, chemokines may be a common link between the eosinophilia of allergy-associated and non-allergy-associated CS, a finding that may have therapeutic implications.

Association of increased CD4+ T-cell infiltration with increased IL-16 gene expression in atopic dermatitis

BACKGROUND

The mechanisms involved in the initiation and the maintenance of skin inflammation in atopic dermatitis (AD) are poorly understood. Previous studies have demonstrated increased numbers of infiltrating CD4+ T cells in acute lesions compared with normal control skin. IL-16 is a cytokine that has selective chemotactic activity for CD4+ cells.

OBJECTIVE

We sought to examine whether IL-16 expression might be upregulated in acute versus chronic AD.

METHODS

We investigated the expression of IL-16 mRNA in skin biopsy specimens from acute and chronic skin lesions, as well as from the uninvolved skin of patients with AD and normal skin. Cryostat sections from 4% paraformaldehyde-fixed skin biopsy specimens were processed for in situ hybridization by using cRNA coding for IL-16 mRNA. Numbers of infiltrating CD4+ and CD8+ cells were also determined by immunocytochemistry.

RESULTS

There were positive signals for IL-16 mRNA both in the basal layer of the epidermis and in the dermis of AD skin biopsy specimens from all subjects studied. The numbers of epidermal and dermal IL-16 mRNA+ cells were significantly increased in acute skin lesions compared with chronic (P <.01) and uninvolved (P <.001) skin lesions and compared with normal skin (P <.001). The number of CD4+ cells was significantly increased in acute skin lesions compared with chronic (P <.01) skin lesions and uninvolved skin (P <.01) and compared with normal skin (P <.01). Significant correlations were found between the numbers of CD4+ cells and the numbers of epidermal (r = 0.82, P <.001) and dermal (r = 0.71, P <.001) IL-16 mRNA+ cells.

CONCLUSION

The results demonstrate that upregulation of IL-16 mRNA expression in acute AD is associated with increased numbers of CD4+ cells, suggesting that IL-16 may play a role in the initiation of skin inflammation, presumably through recruitment of CD4+ cells.

In vivo expression of cytokine receptor mRNA in atopic dermatitis

BACKGROUND

Atopic dermatitis (AD) is a chronic inflammatory skin disease with immunopathologic features that vary depending on the duration of the lesion. Acute lesions are associated with a T-cell infiltrate and a high expression of IL-4 mRNA compared with chronic lesions, uninvolved AD skin, or skin from normal control subjects. Chronic lesions are rich in eosinophils and monocyte/macrophages and contain a greater number of IL-5, granulocyte-macrophage colony-stimulating factor (GM-CSF), and IL-12 (p40) mRNA-positive cells.

OBJECTIVES

In this study, we investigated the mRNA expression of the IL-4 receptor (IL-4Ralpha), IL-5Ralpha, GM-CSFRalpha, and IL-12Rbeta2 in biopsy specimens from acute and chronic AD lesions, uninvolved AD skin, normal skin, and psoriatic skin lesions.

METHODS

Cytokine receptor mRNA was examined in paraformaldehyde-fixed biopsy specimens with in situ hybridization with specific antisense riboprobes.

RESULTS

Acute and chronic skin lesions exhibited a significant increase in numbers of IL-5Rbeta and GM-CSFRalpha mRNA-positive cells compared with uninvolved AD skin and normal skin (P < .001). Chronic skin lesions had a significantly greater number of IL-5Ralpha and GM-CSFRalpha mRNA-positive cells when compared with acute AD skin (P < .001). In contrast, IL-4Ralpha mRNA expression was increased in acute but not chronic AD lesions compared with uninvolved and normal skin (P < .001). No significant differences were observed in numbers of IL-12Rbeta2 mRNA-positive cells when comparing acute AD, chronic AD, uninvolved AD, and normal skin. In psoriatic skin, the numbers of GM-CSFRalpha and IL-12Rbeta2 mRNA-positive cells were significantly increased compared with acute AD lesions, uninvolved skin, and normal control skin (P < .01).

CONCLUSIONS

These results demonstrate that acute AD is associated with a high expression of IL-4Ralpha, whereas IL-5Ralpha and GM-CSFRalpha mRNA are predominantly increased in chronic AD and to lesser extent in acute lesions. These findings support the biphasic role of IL-4, IL-5, and GM-CSF in the pathophysiology of AD.

Comparison of inflammatory cell profile and Th2 cytokine expression in the ethmoid sinuses, maxillary sinuses, and turbinates of atopic subjects with chronic sinusitis

Chronic sinusitis is a common disease characterized by persistent inflammation of the sinus mucosa. This study was undertaken to investigate immunopathologic findings in biopsy specimens from the ethmoid sinuses, maxillary sinuses, and inferior nasal turbinates of 14 allergic subjects with chronic sinusitis. The composition of the inflammatory infiltrate in the three tissue sites was examined by immunocytochemistry with anti-CD3 (total T cells), anti-CD4 (helper T cells), anti-CD8 (suppressor T cells), anti-MBP (eosinophils), antitryptase (mast cells), and antichymase (mast cells) antibodies. These revealed a significant increase in the T-cell helper/suppressor ratio and eosinophils in the ethmoid sinus mucosa compared with those in the maxillary sinus mucosa and the inferior turbinate. Eosinophil numbers were also higher in the maxillary sinus than in the inferior turbinate. Mast cells were present in significantly higher numbers in the ethmoid sinus and inferior turbinate biopsy sections than in the maxillary sinus. With antisense, radiolabeled riboprobes, we used in situ hybridization to examine the expression of interleukin-4 and interleukin-5 transcripts. The density of cells expressing interleukin-4 transcripts was significantly higher in the inferior turbinate biopsy sections than in those from the ethmoid and maxillary sinuses. In addition, the number of interleukin-4 mRNA-positive cells was higher in the ethmoid than in the maxillary sinus mucosa. The density of interleukin-5 mRNA-positive cells was significantly higher in the ethmoid and maxillary sinuses than in the inferior turbinate. The results of this study indicate (1) a more intense inflammatory response in the ethmoid sinus than in the maxillary sinus and inferior turbinate in allergic chronic sinusitis and (2) different inflammatory responses in the upper airways that are dependent on the anatomic site. These findings have potential implications in the design of new therapeutic interventions for allergic chronic sinusitis.

Expression of IgE heavy chain transcripts in the sinus mucosa of atopic and nonatopic patients with chronic sinusitis

We have recently shown the increased mRNA expression of interleukin (IL)-4 and IL-13 in sinus biopsies from allergic subjects with chronic sinusitis (ACS), whereas only IL-13 mRNA was elevated in biopsies obtained from nonallergic subjects with chronic sinusitis (NCS). In the lymph nodes and spleen, these cytokines may promote IgE production through transcriptional activation of the germline IgE heavy chain promoter, an event which precedes immunoglobulin isotype switching to IgE in B cells. We hypothesized that local expression of IL-4 and/or IL-13 might act by inducing germline IgE heavy chain transcript expression locally in the sinus mucosa of chronic sinusitis patients. Mucosal sinus biopsies were obtained from 13 patients with ACS, 12 subjects with NCS, and 11 normal control individuals. The numbers of B cells in the sinus mucosa were studied by immunocytochemistry with anti-CD20 monoclonal antibodies. In situ hybridization was performed using antisense radiolabeled riboprobes complementary to the IgE epsilon -heavy chain germline (Iepsilon) and heavy chain constant region (Cepsilon) gene transcripts. Riboprobes specific for the IgG gamma-heavy chain constant region (Cgamma) were used as an isotype control. Immunocytochemical analysis indicated augmented numbers of CD20-positive B cells in the biopsies obtained from ACS patients compared with NCS subjects (P < 0.05) and normal control subjects (P < 0.01). Statistically significant increases were observed in the numbers of cells expressing Iepsilon and Cepsilon transcripts in the sinus mucosa of ACS patients compared with those with NCS (P < 0. 001) and normal controls (P < 0.001), while Cgamma RNA expression did not differ significantly between the groups. In three randomly selected ACS biopsies, 92-100% of cells expressing Cepsilon transcripts and 100% of Iepsilon RNA-positive cells coexpressed CD20 immunoreactivity. Cells expressing Cepsilon transcripts were also significantly increased in NCS compared with normal controls (P < 0. 05). The results of this study suggest that local IgE class switching occurs in the pathogenesis of ACS and that ACS and NCS are both associated with increased expression of Cepsilon transcripts.

Assessment by nasal biopsy of long-term use of mometasone furoate aqueous nasal spray (Nasonex) in the treatment of perennial rhinitis

Allergic rhinitis is associated with specific histopathologic changes in the nasal mucosa including squamous metaplasia and local eosinophilia. Previous studies have shown that mometasone furoate aqueous nasal spray is effective and well tolerated in reducing perennial rhinitis and seasonal allergic rhinitis symptoms. We undertook a multicenter, open-label study to evaluate, by nasal biopsy, the tissue changes associated with mometasone furoate use (200 microg/day) during a 12-month treatment period in patients with perennial rhinitis. Of the 69 patients enrolled in the study, 52 completed all 12 months of treatment. Nasal biopsy specimens obtained from patients at baseline and after treatment were evaluated in a blinded fashion by computerized image analysis, qualitative histologic examination, and immunocytochemistry. Morphologic examination of nasal biopsy specimens showed a decrease in focal metaplasia, no change in epithelial thickness, and no sign of atrophy after treatment with mometasone furoate. Immunocytochemical analyses of nasal biopsy specimens obtained before and after treatment revealed a significant decrease in major basic protein-positive eosinophils and tryptase-positive mast cells in the epithelium and lamina propria after treatment. Mometasone furoate appeared to attenuate the inflammatory process by reducing the extent of inflammatory cell infiltration, particularly of eosinophils. This study demonstrated that long-term administration of mometasone furoate is not associated with adverse tissue changes in the nasal mucosa of patients with perennial rhinitis.

Interleukin-6 expression in chronic sinusitis: colocalization of gene transcripts to eosinophils, macrophages, T lymphocytes, and mast cells

Chronic sinusitis in allergic (ACS) and nonallergic (NCS) patients is characterized by persistent inflammation and subepithelial fibrosis of the sinus mucosa. The inflammatory infiltrate is rich in T lymphocytes, monocyte/macrophages, plasma cells, and eosinophils. Th2-type cytokines are thought to regulate inflammatory cell recruitment, activation, survival, and the release of tissue-damaging mediators. Interleukin-6 is a proinflammatory Th2-type cytokine that stimulates fibroblast proliferation and collagen synthesis. Expression of interleukin-6 has been reported in pulmonary fibrosis and a number of other conditions associated with fibrotic tissue changes. In vitro studies have indicated that interleukin-6 is produced by macrophages, T cells, eosinophils, mast cells, and other cell types. Here we examined interleukin-6 messenger RNA and immunoreactivity in the sinus epithelium and subepithelium of subjects with ACS and NCS by in situ hybridization and immunocytochemistry, performed on sinus biopsy and polyp sections obtained from patients. Nasal turbinate biopsy specimens from normal volunteers were used as controls. Interleukin-6 messenger RNA and immunoreactivity were expressed by a significantly greater proportion of epithelial and subepithelial cells in ACS and NCS subjects than in normal controls. There was no difference in epithelial or subepithelial interleukin-6 expression between ACS and NCS patients. Colocalization studies revealed that macrophages, T cells, eosinophils, and mast cells are sources of interleukin-6 messenger RNA in ACS and NCS. The numbers of interleukin-6 messenger RNA-positive cells coexpressing immunoreactivity for the mast-cell marker were significantly greater in ACS than in NCS subjects. The results of this study suggest a role for interleukin-6 in the inflammatory response of chronic sinusitis.

Interleukin-4, interleukin-5, and granulocyte-macrophage colony-stimulating factor receptor expression in chronic sinusitis and response to topical steroids

Chronic sinusitis and its associated eosinophilic infiltrate are believed to be mediated, at least in part, by the upregulation of Th-2 cytokines, including interleukin-4, interleukin-5, and granulocyte-macrophage colony-stimulating factor (GM-CSF). Interleukin-4 is involved in IgE production and in eosinophil recruitment through upregulation of vascular cell adhesion molecule-1. Interleukin-5 and GM-CSF are involved in eosinophil growth and survival. The aim of this study was to investigate the expression of receptors for these cytokines in the sinus mucosa of subjects with chronic sinusitis. Using the technique of in situ hybridization to detect specific cytokine receptor messenger RNA, we studied the sinus mucosa of subjects with nonallergic chronic sinusitis, subjects with allergic chronic sinusitis, subjects with allergic chronic sinusitis treated with topical steroids, and normal controls. Our data demonstrate higher expression of interleukin-4 receptor in subjects with allergic chronic sinusitis than in controls (p < 0.001) and higher expression of interleukin-5 receptor in both subjects with nonallergic chronic sinusitis and subjects with allergic chronic sinusitis than in controls (p < 0.001, p < 0.001). The expression of interleukin-4 receptor and interleukin-5 receptor was higher in subjects with allergic chronic sinusitis than in subjects with nonallergic chronic sinusitis (p < 0.001). GM-CSF receptor expression was also found to be higher in subjects with allergic chronic sinusitis and subjects with nonallergic chronic sinusitis than in controls (p < 0.001, p < 0.001). In contrast to interleukin-4 receptor and interleukin-5 receptor, however, expression of GM-CSF receptor was higher in subjects with nonallergic chronic sinusitis than in subjects with allergic chronic sinusitis (p < 0.001). In subjects with allergic chronic sinusitis treated with topical corticosteroids, the expression of interleukin-4 receptor and interleukin-5 receptor messenger RNA levels was significantly lower than levels in patients with allergic chronic sinusitis who were not taking topical steroids (p < 0.001, p < 0.001). Steroid treatment had no effect on GM-CSF receptor messenger RNA expression. In conclusion, our data support a role for Th-2 cytokine receptors in the pathophysiology of chronic sinusitis. Further, our data lend support to the theory that differential activation of distinct cytokine pathways mediates inflammation in chronic sinusitis depending on whether there is associated allergy. Finally, treatment with topical corticosteroids has been demonstrated in chronic sinusitis to downregulate receptors for interleukin-4 and interleukin-5.

Increased expression of eotaxin in bronchoalveolar lavage and airways of asthmatics contributes to the chemotaxis of eosinophils to the site of inflammation

Presently, there is considerable evidence for the participation of eosinophils in the pathophysiology of human bronchial asthma. Although increased numbers of eosinophils are present in the airways and bronchoalveolar lavage (BAL) fluid of atopic asthmatics, the mechanisms responsible for their preferential accumulation are still largely unknown. Eotaxin is a chemokine that promotes the selective recruitment of eosinophils. We report that atopic asthmatic patients have high concentrations of eotaxin in BAL fluid and an increased expression of eotaxin mRNA and protein in the epithelium and submucosa of their airways when compared with normal controls. In the BAL cells from asthmatic patients, eotaxin immunoreactivity colocalized predominantly to macrophages (62.2%), with a lesser contribution from T cells (16.3%) and eosinophils (8.9%). BAL fluid from asthmatics contained chemotactic activity for eosinophils that was attributable in part to the presence of eotaxin. Moreover, eotaxin was more effective at inducing in vitro eosinophil chemotaxis when eosinophils were stimulated with IL-5 (a cytokine that enhances the effector capacity of mature eosinophils). These observations suggest that eotaxin contributes to the pathogenesis of asthma by the specific recruitment of eosinophils into the airways.

Increased expression of eotaxin in bronchoalveolar lavage and airways of asthmatics contributes to the chemotaxis of eosinophils to the site of inflammation

Presently, there is considerable evidence for the participation of eosinophils in the pathophysiology of human bronchial asthma. Although increased numbers of eosinophils are present in the airways and bronchoalveolar lavage (BAL) fluid of atopic asthmatics, the mechanisms responsible for their preferential accumulation are still largely unknown. Eotaxin is a chemokine that promotes the selective recruitment of eosinophils. We report that atopic asthmatic patients have high concentrations of eotaxin in BAL fluid and an increased expression of eotaxin mRNA and protein in the epithelium and submucosa of their airways when compared with normal controls. In the BAL cells from asthmatic patients, eotaxin immunoreactivity colocalized predominantly to macrophages (62.2%), with a lesser contribution from T cells (16.3%) and eosinophils (8.9%). BAL fluid from asthmatics contained chemotactic activity for eosinophils that was attributable in part to the presence of eotaxin. Moreover, eotaxin was more effective at inducing in vitro eosinophil chemotaxis when eosinophils were stimulated with IL-5 (a cytokine that enhances the effector capacity of mature eosinophils). These observations suggest that eotaxin contributes to the pathogenesis of asthma by the specific recruitment of eosinophils into the airways.

Expression of IL-16 in allergen-induced late-phase nasal responses and relation to topical glucocorticosteroid treatment

Allergen-induced late nasal responses (LNRs) are associated with a cellular infiltrate in which CD4+ cells are prominent. These cells have been shown to be the major cellular source of Th2-type cytokines. Mechanisms responsible for the local accumulation of CD4+ cells in the nasal mucosa after allergen exposure are unclear. IL-16 is a potent chemoattractant for CD4+ cells in vitro and may play a significant role in recruiting CD4+ cells in LNRs. We investigated the expression of IL-16 messenger RNA and immunoreactivity in nasal biopsy specimens from 17 subjects with allergic rhinitis. A biopsy specimen of the nasal inferior turbinate was obtained before and 24 hours after local nasal provocation with grass pollen extract after 6 weeks of treatment with either topical fluticasone propionate (n = 9) or placebo (n = 8) nasal spray twice daily. IL-16 mRNA-positive cells and IL-16-immunoreactive cells were identified in both the epithelium and the subepithelial tissue at baseline. Within the placebo-treated group, the numbers of epithelial and subepithelial IL-16 mRNA-positive cells and IL-16-immunoreactive cells were significantly increased 24 hours after challenge compared with baseline (p < 0.001). Topical glucocorticoid therapy resulted in a decrease in allergen-induced epithelial immunoreactive cells and subepithelial IL-16 mRNA-positive cells. The numbers of CD4+ cells increased after antigen challenge compared with baseline (p < 0.05), and this increase was inhibited by glucocorticoid treatment. There were significant correlations between epithelial and subepithelial IL-16 immunoreactivity and CD4+ cell infiltration after antigen challenge. The upregulation of IL-16 expression in allergic nasal mucosa after antigen challenge may have critical implications in the accumulation of CD4+ cells in response to antigen exposure. Steroid-mediated inhibition of IL-16 may be partly responsible for the decrease in local CD4+ cells after topical glucocorticoid therapy.

Increased expression of interleukin-16 in bronchial mucosa of subjects with atopic asthma

Asthma is characterized by the presence of activated CD4+ cells in the airways. We hypothesized that the newly characterized cytokine interleukin (IL)-16 is involved in the pathogenesis of asthma through its ability to selectively induce CD4+ cell recruitment within the inflamed bronchial wall. We investigated the expression of IL-16 in bronchial biopsies obtained from subjects with mild asthma (n = 10), atopic nonasthmatic individuals (n = 6), and normal control subjects (n = 10). Cryostat sections from 4% paraformaldehyde-fixed fiberoptic bronchial biopsies were immunostained using a specific antibody that recognizes human IL-16. IL-16 mRNA expression was determined by in situ hybridization. IL-16 immunoreactivity and mRNA were demonstrated mainly in bronchial epithelial cells in all subjects. IL-16 immunoreactivity and IL-16 mRNA expression within the epithelium were significantly higher in bronchial biopsies obtained from asthmatic subjects as compared to both atopic nonasthmatic and normal controls (P < 0.001). The numbers of subepithelial IL-16 immunoreactive cells and IL-16 mRNA-positive cells were also greater in the bronchial biopsies obtained from asthmatic subjects as compared to both atopic nonasthmatic and normal controls (P < 0.001). Epithelial expression of IL-16 immunoreactivity and mRNA correlated with the CD4+ cell infiltration (r2 = 0.70, P < 0.001). There were significant associations between epithelial and subepithelial IL-16 immunoreactivity and airway responsiveness to methacholine. This study demonstates that IL-16 is expressed in airway tissues, particularly in the epithelial cells, and that up-regulation of its expression is a feature of allergic asthma. These results suggest an in vivo role for IL-16 in the pathogenesis of asthma, possibly through the recruitment of CD4+ cells, and support the increasing evidence for the participation of epithelial cells in regulating inflammatory responses.

IL-13 mRNA and immunoreactivity in allergen-induced rhinitis: comparison with IL-4 expression and modulation by topical glucocorticoid therapy

The allergen-induced late nasal response (LNR) is associated with high expression of interleukin-4 (IL-4) and IL-5 messenger RNA (mRNA) in the nasal mucosa, suggesting a role for Th2-type cytokines in the development of the LNR. Moreover, topical corticosteroid-mediated inhibition of the LNR is accompanied by inhibition of IL-4, but not IL-5, mRNA expression, IL-13 shares a number of functions with IL-4, including IgE switching and vascular cell adhesion molecule-1 (VCAM-1) upregulation. We investigated the expression of IL-13 mRNA and immunoreactivity in nasal biopsies from 10 normal subjects and 20 subjects with allergic rhinitis. IL-4 mRNA expression was examined in the same subjects. The allergic rhinitis patients were randomized to receive a 6-wk treatment with either topical fluticasone propionate (n = 10) or placebo (n = 10) nasal spray twice daily. A nasal biopsy was taken before treatment and 24 h after local nasal allergen provocation with a grass-pollen extract. Before treatment, there was no significant difference between the allergic rhinitis patients and controls in the expression of IL-13 mRNA and immunoreactivity. After allergen provocation, we observed a significant increase in IL-13 mRNA-positive and immunoreactive cells at 24 h only in subjects given placebo (P < 0.001). Inhibition of the LNR after corticosteroid treatment was associated with a marked decrease in allergen-induced IL-13 mRNA-positive (P < 0.001) and immunoreactive cells (P < 0.001). In subjects given placebo, 76.9 +/- 5.5% of IL-13 mRNA-positive cells observed after allergen were CD3+, whereas 11.2 +/- 2.7% coexpressed immunoreactivity for mast-cell tryptase. In these subjects, increases in cells expressing IL-13 mRNA were greater than for IL-4 mRNA (P = 0.001), and double in situ hybridization studies revealed that 100% of the IL-4 mRNA-positive cells coexpressed IL-13 mRNA, whereas 66.6 +/- 10.5% of IL-13 mRNA-positive cells coexpressed IL-4 transcripts after allergen challenge. The results of this study suggest that IL-13 expression is a prominent feature of the LNR, and that inhibition of the LNR following steroid therapy may be partly attributable to inhibition of IL-13 expression.

IL-4 and IL-13 expression in chronic sinusitis: relationship with cellular infiltrate and effect of topical corticosteroid treatment

OBJECTIVE

Chronic sinusitis with allergy (ACS) and without allergy (NCS) are inflammatory diseases with considerable morbidity. The present study was undertaken to investigate, by in situ hybridization, the expression of IL-13 and IL-4 mRNA in sinus biopsy sections.

METHOD

Specimens were obtained from subjects with NCS (n = 12), ACS (n = 13), ACS on steroid therapy (n = 11), and normal controls (n = 11). The composition of the inflammatory infiltrate was also examined in all cases.

RESULTS

The number of cells expressing IL-4 and IL-13 transcripts was significantly higher in subjects with ACS compared to normal controls. In contrast, the numbers of IL-13 but not IL-4 mRNA-positive cells were increased in the NCS subjects compared to the normal controls. IL-4 and IL-13 mRNA expression was suppressed in ACS subjects on topical steroid therapy compared to untreated patients. There was no significant difference in the numbers of eosinophils between the ACS subjects treated with steroids and those who were not treated, but the steroid-treated patients demonstrated significantly higher numbers of CD8+ cells in the sinus mucosa. Increased numbers of CD8+ cells were also observed in subjects with NCS compared with ACS subjects and normal controls.

CONCLUSIONS

These results demonstrate that increased IL-13 expression is an important feature of allergic and nonallergic patients with chronic sinusitis. Furthermore, our data indicate that IL-13 and IL-4 are under differential regulation in NCS subjects.