Phenotyping of difficult asthma using longitudinal physiological and biomarker measurements reveals significant differences in stability between clusters

Background

Although the heterogeneous nature of asthma has prompted asthma phenotyping with physiological or biomarker data, these studies have been mostly cross-sectional. Longitudinal studies that assess the stability of phenotypes based on a combination of physiological, clinical and biomarker data are currently lacking.

Our objective was to assess the longitudinal stability of clusters derived from repeated measures of airway and physiological data over a 1-year period in moderate and severe asthmatics.

Methods

A total of 125 subjects, 48 with moderate asthma (MA) and 77 with severe asthma (SA) were evaluated every 3 months and monthly, respectively, over a 1-year period. At each 3-month time point, subjects were grouped into 4 asthma clusters (A, B, C, D) based on a combination of clinical (duration of asthma), physiological (FEV₁ and BMI) and biomarker (sputum eosinophil count) variables, using k-means clustering.

Results

Majority of subjects in clusters A and C had severe asthma (93 % of subjects in cluster A and 79.5 % of subjects in cluster C at baseline). Overall, a total of 59 subjects (47 %) had stable cluster membership, remaining in clusters with the same subjects at each evaluation time. Cluster A was the least stable (21 % stability) and cluster B was the most stable cluster (71 % stability). Cluster stability was not influenced by changes in the dosage of inhaled corticosteroids.

Conclusion

Asthma phenotyping based on clinical, physiologic and biomarker data identified clusters with significant differences in longitudinal stability over a 1-year period. This finding indicates that the majority of patients within stable clusters can be phenotyped with reasonable accuracy after a single measurement of lung function and sputum eosinophilia, while patients in unstable clusters will require more frequent evaluation of these variables to be properly characterized.

Induction of GITRL expression in human keratinocytes by Th2 cytokines and TNF-α: implications for atopic dermatitis

BACKGROUND

Glucocorticoid-induced TNF receptor-related protein ligand (GITRL), a ligand for the T cell co-stimulatory molecule GITR, is expressed by keratinocytes and involved in chemokine production. The expression of GITRL in skin inflammation remains unknown.

OBJECTIVES

This study investigated cytokine regulation of keratinocyte GITRL expression.

METHODS

Glucocorticoid-induced TNF receptor expression was evaluated in cytokine-treated human epidermal keratinocytes (HEK)s, murine PAM 212 cell line, murine and human skin explants by real time PCR, flow cytometry and immunostaining. Functional responses to GITR fusion protein were examined by real time PCR and ELISA. GITRL expression in AD and psoriasis was studied by immunohistochemistry.

RESULTS

Skin biopsies from STAT6VT transgenic mice, which develop spontaneous atopic skin inflammation, were found by immunofluoresence, to have increased keratinocyte GITRL expression. Exposure to Th2 cytokines augmented GITRL mRNA expression in the murine PAM 212 keratinocytic cell line and murine skin explants. In contrast, GITRL mRNA and protein expression was only increased in HEKs and human skin explants in the presence of the combination of TNF-α and Th2 cytokines. A synergistic effect of Th2 cytokines and GITR fusion protein on production of CCL17, the Th2 chemokine, by murine keratinocytes was demonstrated. Immunohistochemical staining showed that acute AD lesions have increased expression of GITRL compared with normal skin, chronic AD lesions and psoriatic plaques.

CONCLUSIONS AND CLINICAL RELEVANCE

Our studies demonstrate that GITRL expression is augmented by Th2 cytokines and TNF-α in keratinocytes. Increased GITRL expression in acute AD skin lesions is shown. This observation suggests a link between cytokine-regulated keratinocyte GITRL expression and its role in inflammatory responses in AD.

Conjugates of ovalbumin and monomethoxypolyethylene glycol abolish late allergic responses and decrease IL-4 and IL-5 mRNA expression in the rat

The purpose of this study was to test the therapeutic potential of monomethoxypolyethylene glycol (mPEG) conjugated-allergen using a rodent model of allergic asthma. Previously, this conjugate has been shown to possess the dual capacity of inducing long-term ovalbumin (OA)-specific suppression of the antibody response and inactivating rat mast cells that have been sensitized with murine IgE to OA. Ovalbumin sensitized and challenged Brown Norway rats were studied. Fourteen days after sensitization, a test group of six rats received mPEG-OA solution intratracheally and were challenged 30 min later with aerosolized OA. Another group of seven sensitized rats was similarly challenged with OA 30 min after intratracheal administration of normal saline. A group of six sensitized rats received mPEG-OA solution intratracheally but were challenged with normal saline. Another group of seven sensitized rats received mPEG-BSA solution intratracheally and were challenged 30 min later with aerosolized OA. A final group of five unsensitized rats were neither challenged nor medicated intratracheally. Pulmonary resistance was measured before and for 8 h following inhalation challenge. mPEG-OA treatment had an inhibitory effect on the allergic late airway response, but the early response was not significantly altered. Both mPEG-OA and mPEG-BSA reduced the total cells, eosinophils and neutrophils, in bronchoalveolar lavage and decreased the expression of IL-4, IL-5 and IFN-gamma mRNA. In conclusion, mPEG-OA can prevent the development of allergen-induced late airway responses and reduce airway Th2-type cytokine expression whereas mPEG conjugated to an irrelevant antigen (BSA) is anti-inflammatory but does not affect the late response.

Neutrophilic airway inflammation in horses with heaves is characterized by a Th2-type cytokine profile

Heaves in horses shares many similarities with human asthma, including lower airway inflammation, reversible airway obstruction, and bronchial hyperresponsiveness. Extrinsic asthma is an allergic response to environmental allergens and a similar immunologic mechanism may be implicated in heaves. It is now recognized that a Th2 subset of CD4+ lymphocytes is associated with allergic diseases such as atopic asthma. The purpose of this study was to determine whether airway inflammation in heaves is associated with a pattern of expression of cytokine suggestive of a Th2 type response. The expression of mRNA, encoding interleukin (IL)-4, IL-5, and interferon gamma (IFN-gamma) was measured in bronchoalveolar cells from seven horses with heaves and five control horses, using in situ hybridization and radiolabeled equine-specific cRNA probes coding for these cytokines. Bronchoalveolar cells of horses with heaves had an increased expression of IL-4 (p = 0.01) and IL-5 (p = 0.02) mRNA and a decreased expression of INF-gamma (p = 0.01) compared with control horses. Here we show that inflammatory cells in lungs from horses with heaves display a Th2-type cytokine profile that is consistent with the hypothesis that heaves is an allergic condition with similarity to human asthma.

GRbeta expression in nasal polyp inflammatory cells and its relationship to the anti-inflammatory effects of intranasal fluticasone

BACKGROUND

Nasal polyposis disease is an inflammatory disorder with intense eosinophilic infiltration of respiratory mucosa that is often difficult to control with topical steroids. Recent evidence suggests that overexpression of the glucocorticoid receptor splice variant GRbeta in inflammatory cells might contribute to steroid insensitivity in diseases such as asthma.

OBJECTIVE

The purposes of this investigation were to determine whether nasal polyp (NP) inflammatory cells overexpress GRbeta and to examine whether GRbeta overexpression is associated with insensitivity to the potent topical steroid fluticasone propionate (FP).

METHODS

Biopsies were obtained from 10 subjects with NPs before and 4 weeks after treatment with intranasal FP. Middle turbinates biopsies from 6 healthy, nonallergic subjects served as normal controls. Biopsies were immunostained for inflammatory cell markers as well as GRbeta and probed for various cytokine mRNA. The anti-inflammatory response to FP was examined in relation to pretreatment levels of GRbeta expression.

RESULTS

The total numbers of inflammatory cells were increased in NPs. The percentage of inflammatory cells expressing GRbeta was also increased (40.5% +/- 19.2% vs 16.1% +/- 4.0%, P =.009). GRbeta expression in NPs was almost exclusive to T lymphocytes, eosinophils, and macrophages. An inverse correlation was observed between the baseline inflammatory cell GRbeta expression and the reduction after FP treatment in EG2-positive eosinophils, CD4-positive T lymphocytes, endothelial VCAM-1 expression, and IL-4 mRNA-positive cells. NPs that were "FP-insensitive" in terms of suppression of eosinophil numbers (major basic protein-positive) had a significantly greater percentage of GRbeta-positive inflammatory cells, a higher ratio of GRbeta-positive/GRalpha-positive cells, and increased numbers of GRbeta-positive eosinophils and macrophages in comparison with those that were "FP-sensitive." "FP-insensitive" NPs also demonstrated a higher percentage of IL-5-positive inflammatory cells expressing GRbeta before and after FP treatment.

CONCLUSION

GRbeta expression appears to be a marker of steroid insensitivity in NPs. Expression of GRbeta by NP inflammatory cells, particularly T cells and eosinophils, might render them resistant to suppression by topical steroids and thereby contribute to persistent NP inflammation.

Gene expression of vascular endothelial growth factor and its receptors and angiogenesis in bronchial asthma

BACKGROUND

Angiogenesis is a feature of airway remodeling in bronchial asthma. The mechanism responsible for this angiogenesis is unknown. Vascular endothelial growth factor (VEGF) is a potent inducer of endothelial cells, which may contribute to chronic inflammation and angiogenesis.

OBJECTIVE

We sought to investigate the molecular mechanisms underlying increased vascularity, and we examined the mRNA expression of VEGF and its receptors (flt-1 and flk-1) within bronchial biopsy specimens from asthmatic patients and normal control subjects.

METHODS

Endobronchial biopsy specimens were examined immunocytochemically by staining with anti-type IV collagen mAb to evaluate vessel density by using computer-assisted image analysis. Specimens were also analyzed for the presence of the mRNAs of VEGF and its receptors with in situ hybridization.

RESULTS

The extent of airway vascularity was increased in asthmatic subjects compared with that in control subjects (P <.01). Asthmatic subjects exhibited a greater expression of VEGF, flt-1, and flk-1 mRNA(+) cells in the airway mucosa compared with that in control subjects (P <.001 for each comparison). The degree of vascularity was associated with the number of VEGF, flt-1, and flk-1 mRNA(+) cells. Numbers of cells expressing VEGF mRNA inversely correlated with airway caliber (r = -0.83, P <.01) and airway hyperresponsiveness (r = -0.97, P <.001). Colocalization studies showed that macrophages, eosinophils, and CD34(+) cells were the major sources of VEGF; CD34(+) cells, macrophages, and T cells expressed both flt-1 and flk-1.

CONCLUSION

These findings provide evidence that VEGF may play an important role in angiogenesis and subsequent airway remodeling in bronchial asthma.

Inflammatory patterns of allergic and nonallergic rhinitis

Rhinitis is a chronic condition of the nasal mucosa that affects a large segment of the population. The symptoms of rhinitis occur in a variety of sinonasal conditions, which may be broadly classified as allergic (seasonal or perennial) or nonallergic (infectious or a number of noninfectious etiologies) based on the presence or absence of atopy. The cytokine profile and inflammatory patterns underlying these two conditions vary because of certain differences in their pathophysiology as discussed in this review.

Anti-inflammatory activity of clarithromycin in adults with chronically inflamed sinus mucosa

In a phase IV, open-label study, 25 patients with clinically stable chronic sinusitis and persistent maxillary sinus inflammation were treated for 14 days with clarithromycin 500 mg twice daily. Biopsy specimens of the maxillary sinus mucosa were obtained pretreatment and evaluated for macrophages (CD68), eosinophils (MBP), elastase, interleukin-6 (IL-6), IL-8, tumor necrosis factor-alpha (TNF-alpha), and activity of eosinophils (EG2), as well as edema score. Clinical signs and symptoms were assessed pretreatment, at the end of treatment, and 1 and 2 weeks later. Statistically significant reductions (P < or = .05) from pretreatment were observed for all markers of sinus mucosal inflammation, including CD68, EG2, elastase, IL-6, IL-8, TNF-alpha, and edema score, with a trend to decreased total eosinophil count. Improvement was observed for all clinical signs and symptoms of chronic sinusitis--sinus pain, sinus headache, nasal congestion, nasal discharge, and mucopurulent discharge--up to 14 days after the end of treatment. Cultures to evaluate persistent infection with Chlamydia pneumoniae showed negative results. Significant reductions in various markers of sinus mucosal inflammation support the role of clarithromycin in modulating immunologic responses. Improvement of clinical signs and symptoms in patients with chronic inflammatory sinusitis not meeting criteria for known or presumed bacterial infection was also noted up to 2 weeks after completion of a 14-day course of clarithromycin.

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.

Regulation of IL-1-induced gingival collagenase gene expression by activator protein-1 (c-Fos/c-Jun)

Matrix metalloproteinase-1 is probably involved in the progression of periodontal disease. The aim of this study was to investigate whether IL-1beta stimulates the expression of the activator protein 1 (AP-1) transcription factor and, consequently, if the AP-1 transcription factor participates in the regulation of collagenase gene expression in human gingival fibroblast cells. In this study, we demonstrate that the concentration of the protein components of AP-1 transcription factor, c-Fos and c-Jun, is enhanced by IL-1beta both at mRNA and protein levels, utilizing Northern blot analysis, electrophoretic mobility gel shift assay and Western blot analysis. The IL-1beta stimulated the collagenase-CAT and AP-1-CAT activities in a dose dependent manner with respect to the amount of DNA used in transfections. Further, overexpression of c-Fos and c-Jun proteins revealed a dose-dependent transcriptional activation of the collagenase promoter. These findings, coupled with the existence of AP-1 consensus DNA binding sites on the collagenase gene promoter, show that regulation of collagenase gene expression by IL-1beta involves the transcription factor AP-1 in gingival fibroblasts.

Increased number of glucocorticoid receptor-beta-expressing cells in the airways in fatal asthma

BACKGROUND

We have recently demonstrated an increased number of glucocorticoid receptor-beta (GRbeta)-positive cells in steroid-insensitive subjects with severe asthma. Insensitivity to steroids may be a major contributing factor in fatal asthma; however, no such direct evidence has been report previously.

OBJECTIVE

Our aims were to investigate the expression of GRbeta immunoreactivity, an endogenous inhibitor of steroid action previously associated with steroid insensitivity, within the airways of patients who died of slow-onset fatal asthma and to compare its expression in patients with emphysema and in nonasthmatic subjects who died of unrelated causes. Sections from airways, both large and small, were obtained from 7 patients who died of asthma, 6 who died from emphysema, and 8 who died from nonpulmonary diseases. Sections from lungs of 6 patients with mild asthma whose lungs were resected for carcinoma were also included as controls.

METHODS

Tissue samples were processed for immunocytochemistry with a polyclonal antibody to GRbeta with use of the avidin-biotin technique and with monoclonal CD3, major basic protein, CD68, and elastase antibodies with the alkaline phosphatase-anti-alkaline phosphatase technique. Sequential immunocytochemistry was performed to phenotype the GRbeta immunoreactive cells. Tissue sections from both large (>2 mm) and small (<2 mm) airways were examined.

RESULTS

There was a significantly greater number of GRbeta immunoreactive cells in fatal asthma compared with emphysema and controls (P <.001 and P <.05, respectively). There was no difference in the expression of GRbeta in emphysema compared with controls. GRbeta immunoreactivity was also significantly higher in fatal asthma compared with mild asthma. The expression of GRbeta in the small airways of patients with severe asthma did not differ significantly from that in the large airways. The majority of GRbeta-positive cells were T cells and to a lesser extent eosinophils, macrophages, and neutrophils.

CONCLUSION

The results of this study support the association of GRbeta expression with fatal asthma and suggest that alternative anti-inflammatory agents need to be considered in the acute setting for patients who are not responding to steroid therapy.

The pathology of chronic asthma

Our understanding of the pathophysiology of asthma has undergone great advances in the past decade, particularly with the recognition of cytokines and the roles they may take in orchestrating the local immune response. With this information, it has been possible to target new therapeutic entities such as cytokine or chemokine receptors. Eosinophils and T lymphocytes have a special place in the inflammatory and structural alterations contributing to the asthmatic diathesis. It is possible that phenotype subsets of these cells exist and they hold the key to perpetuation of immunologic and physiologic abnormalities in asthma.

Evidence for increased expression of eotaxin and monocyte chemotactic protein-4 in atopic dermatitis

BACKGROUND

Atopic dermatitis (AD) is a chronic inflammatory skin disease associated with tissue eosinophilia and the activation of T lymphocytes. The novel eosinophil chemoattractants, eotaxin and monocyte chemotactic protein (MCP)-4, are up-regulated at sites of allergic inflammation, yet their contribution to the pathophysiologic mechanisms of AD remains to be determined.

OBJECTIVE

We sought to investigate the expression of eotaxin and MCP-4 in acute and chronic lesions from patients with AD and to determine their relationship to the numbers of resident inflammatory cells.

METHODS

With use of in situ hybridization, the expression of eotaxin and MCP-4 messenger RNA (mRNA) in skin biopsy specimens from patients with acute and chronic AD skin lesions was compared with that of uninvolved skin from these patients and skin from healthy volunteers.

RESULTS

There was a constitutive expression of eotaxin and MCP-4 mRNA in skin biopsy specimens from healthy subjects. Positive signal for chemokine mRNA was observed both within the epidermis and inflammatory cells (macrophages, eosinophils, and T cells) of the subepidermis in AD skin lesions. Within the subepithelium acute and chronic skin lesions exhibited a significant increase in the numbers of eotaxin and MCP-4 mRNA-positive cells compared with uninvolved skin (P <.01), whereas the numbers of eotaxin and MCP-4 mRNA-positive cells were significantly higher in chronic AD compared with acute AD skin lesions (P <.005, P <.001, respectively). Correlations were observed between the expression of eotaxin and MCP-4 mRNA and the presence of eosinophils and macrophages, respectively, in AD lesions (r(2) = 0.84, r(2) = 0.94).

CONCLUSION

There is an increased expression of eotaxin and MCP-4 in acute and chronic lesions, suggesting that these chemotactic factors play a major role in the pathophysiologic mechanisms of AD.

Induction of corticosteroid insensitivity in human PBMCs by microbial superantigens

BACKGROUND

Microbial superantigens have been described to contribute to the pathogenesis of chronic inflammatory diseases often complicated by insensitivity to glucocorticoid therapy. In bronchial asthma glucocorticoid insensitivity has been associated with increased expression of glucocorticoid receptor beta, an endogenous inhibitor of the classic glucocorticoid receptor alpha.

OBJECTIVE

To study a potential mechanism by which superantigens could contribute to poor disease control, we examined their capacity to alter steroid sensitivity and expression of glucocorticoid receptor beta.

METHODS

The capacity of dexamethasone to inhibit stimulation of PBMCs from 7 healthy subjects with the prototypic superantigens, staphylococcal enterotoxin (SE) B, toxic shock syndrome toxin (TSST)-1 and SEE, versus PHA, was tested. The expression of glucocorticoid receptor beta in normal PBMCs after stimulation with SEB, versus PHA, was assessed by immunocytochemistry.

RESULTS

Dexamethasone 10(-6) mol/L caused a 99% inhibition of PHA-induced PBMC proliferation but only a 19% inhibition of the SEB-induced, 26% inhibition of the TSST-1, and 29% inhibition of the SEE-induced PBMC proliferation (P <.01 for all superantigens versus PHA) demonstrating that superantigens can induce steroid insensitivity. Stimulation of normal PBMCs with SEB induced a significant increase of glucocorticoid receptor beta compared with PHA and unstimulated cells (P <.01).

CONCLUSION

We have demonstrated the capacity of microbial superantigens to induce glucocorticoid insensitivity, which should be considered in the diagnosis and treatment of patients with superantigen-triggered diseases. These data suggest that superantigens may contribute to glucocorticoid insensitivity through induction of glucocorticoid receptor beta.

IL-9 and its receptor in allergic and nonallergic lung disease: increased expression in asthma

BACKGROUND

Bronchial asthma is a chronic inflammatory disease associated with genetic components. Recently IL-9 has been reported as a candidate gene for asthma and to be associated with bronchial hyperresponsiveness and elevated levels of total serum IgE.

OBJECTIVE

To investigate the contribution of IL-9 to the pathogenesis of asthma, we examined the expression of IL-9 and its receptor (IL-9R) in bronchial tissue from subjects with atopic asthma (n = 10), chronic bronchitis (n = 11), and sarcoidosis (n = 9) and from atopic (n = 7) and nonatopic (n = 10) healthy control subjects.

METHODS

Bronchial biopsy specimens were examined for the presence of IL-9 and IL-9R protein and messenger RNA (mRNA) by immunocytochemistry and in situ hybridization, respectively. To phenotype the cells expressing IL-9 in asthmatic tissue, combined in situ hybridization and immunocytochemistry was also performed.

RESULTS

There was a highly significant difference (P <.001) in the expression of IL-9 mRNA in asthmatic airways (20.6 +/- 4.0 cells/mm of basement membrane) compared with chronic bronchitis (5.6 +/- 4.4), sarcoidosis (2.5 +/- 1.8), atopic control subjects (7.7 +/- 2.2), and healthy control subjects (2.7 +/- 2.3). The number of IL-9 immunoreactive cells was also greater in asthmatic patients compared with the other groups (P <.05). Although the level of IL-9R mRNA expression did not differ in any of the groups (P >.05), IL-9R immunoreactivity was significantly higher in asthmatic compared with control subjects. Furthermore, IL-9 mRNA expression levels were also significantly correlated with FEV(1) (P <.05) and the airway responsiveness to methacholine producing a 20% fall in FEV(1) (P <. 01). The cells expressing IL-9 mRNA in asthmatic tissue were CD3(+) lymphocytes (68%), major basic protein(+) eosinophils (16%), and elastase(+) neutrophils (8%).

CONCLUSION

The results of this study demonstrate the potential of IL-9 to be a marker for atopic asthma and furthermore suggest an important role for this cytokine in the pathophysiologic mechanisms of this disease.

Molecular pathology of allergic disease: I: lower airway disease

Asthma is a complex disorder associated with eosinophil infiltration and the activation of T lymphocytes within the airways. Recent advances in the pathophysiologic mechanisms of asthma point to the importance of eosinophil-basophil progenitor cells and a family of transcription factors that underlie the development of T(H)2-type responses. Further research is needed to address the development of chronic inflammatory changes, the role of profibrotic cytokines, and especially their reliance on eosinophils in the lungs.

Epidermal HLA-DR and the enhancement of cutaneous reactivity to superantigenic toxins in psoriasis

Streptococcal and staphylococcal superantigens (SAg's) have been implicated in the pathogenesis of inflammatory skin diseases, but the mechanisms by which these toxins act are unknown. The present study assessed the ability of nanogram quantities of topically applied purified toxic shock syndrome toxin-1 (TSST-1), staphylococcal enterotoxin type B, and streptococcal pyrogenic enterotoxin types A and C to induce inflammatory reactions in clinically uninvolved skin of normal controls and subjects with psoriasis, atopic dermatitis, and lichen planus. These SAg's triggered a significantly greater inflammatory skin response in psoriatics than in normal control subjects or in subjects with atopic dermatitis or lichen planus. Surprisingly, skin biopsies did not exhibit the T-cell receptor Vbeta stimulatory properties predicted for SAg-induced skin reactions. By 6 hours after patch testing with SAg's, TNF-alpha mRNA had increased in the epidermis (but not the dermis) in biopsies from psoriatics, compared with controls. Immunohistochemical studies revealed significantly higher HLA-DR expression in keratinocytes from psoriatics than from controls. However, a mutant TSST-1 protein that fails to bind HLA-DR did not elicit an inflammatory skin reaction. These results indicate that keratinocyte expression of HLA-DR enhances inflammatory skin responses to SAg's. They may also account for previous studies failing to demonstrate selective expansion of T-cell receptor Vbetas in psoriatics colonized with SAg-producing Staphylococcus aureus, and they identify a novel T cell-independent mechanism by which SAg's contribute to the pathogenesis of inflammatory skin diseases.

Increased expression of IL-12 receptor mRNA in active pulmonary tuberculosis and sarcoidosis

Cytokines have been implicated in the pathophysiology and development of pulmonary diseases such as tuberculosis and sarcoidosis. In particular, the numbers of cells expressing Th1-type cytokines such as IFN-gamma and IL-12 are increased within the lungs of patients with these granulomatous diseases. As a factor promoting the commitment of naive lymphocytes to a Th1-type profile of cytokine expression, IL-12 may be pivotal in the cascade of proinflammatory events within the airways. In this study, we examined the expression of the IL-12 receptor (IL-12R) mRNA in bronchoalveolar lavage (BAL) fluid from patients with active pulmonary tuberculosis (n = 6) and active pulmonary sarcoidosis (n = 6), and from allergic asthmatics (n = 6) and normal control subjects (n = 6). Bronchoscopy with BAL was undertaken, and cell cytospins were examined using the technique of in situ hybridization. There was a significant increase in the numbers of cells expressing mRNA for both beta(1) and beta(2) subunits of the IL-12R in active pulmonary sarcoidosis (p < 0.02, p < 0.01, respectively) and active pulmonary tuberculosis (p < 0.01, p < 0.005, respectively) compared with normal control subjects. In contrast, the allergic asthmatic patients exhibited a significant decrease in the number of IL-12R mRNA-positive cells (both beta(1) and beta(2) subunits (p < 0.01, p < 0.005, respectively), compared with the normal control subjects. These patients did, however, exhibit a significant increase in IL-4R mRNA, which was not evident in those with either tuberculosis or sarcoidosis when compared with normal subjects (p < 0.05). Colocalization studies demonstrated that CD8+ve cells are a principal site for the expression of IL-12R in tuberculosis. In sarcoidosis, IL-12R was expressed both on CD4+ve and CD8+ve cells. The increased expression of receptors for IL-12 in granulomatous diseases such as pulmonary tuberculosis and sarcoidosis provides evidence supporting the commitment of lymphocytes to a Th1-type cytokine profile in vivo.

Airway epithelium expresses interleukin-18

Interleukin (IL)-18 is an interferon (IFN)-gamma-inducing cytokine suggested to be important in regulating inflammatory responses. This study investigated the pulmonary expression of IL-18 under conditions characterized by T-helper (Th)1 (lipopolysaccharide (LPS) treatment/sarcoidosis) and Th2 (ovalbumin (OVA) challenge/asthma) cytokine production. In situ hybridization and immunocytochemistry were used to determine the number of cells expressing IL-18, IFN-gamma, IL-5 and major basic protein (MBP) within lung tissue from Balb/c mice stimulated with LPS, OVA and in normal control mice. Bronchial biopsies from patients with sarcoidosis, asthma and control individuals were also examined. IL-18 was localized primarily to airway epithelium and mononuclear cells. Constitutive expression was observed within the lungs of control mice. Animals challenged with LPS exhibited more IL-18 messenger ribonucleic acid (mRNA)-positive and IFN-gamma immunoreactive cells, compared to control mice (p<0.01). OVA-challenged mice had fewer IL-18 mRNA positive and more IL-5 and MBP immunoreactive cells, compared to control mice (p<0.01). Similarly, constitutive expression of IL-18 protein was observed within the airway epithelium of control individuals, with more positive cells found within sarcoidosis tissue (p<0.01) and fewer within asthmatic tissue (p<0.01), compared to controls. These results demonstrate the expression of interleukin-18 within airway epithelium and the regulation of this cytokine under conditions of both T-helper1 and T-helper2 cytokine production.

Long-term clinical efficacy of grass-pollen immunotherapy

BACKGROUND

Pollen immunotherapy is effective in selected patients with IgE-mediated seasonal allergic rhinitis, although it is questionable whether there is long-term benefit after the discontinuation of treatment.

METHODS

We conducted a randomized, double-blind, placebo-controlled trial of the discontinuation of immunotherapy for grass-pollen allergy in patients in whom three to four years of this treatment had previously been shown to be effective. During the three years of this trial, primary outcome measures were scores for seasonal symptoms and the use of rescue medication. Objective measures included the immediate conjunctival response and the immediate and late skin responses to allergen challenge. Cutaneous-biopsy specimens obtained 24 hours after intradermal allergen challenge were examined for T-cell infiltration and the presence of cytokine-producing T helper cells (TH2 cells) (as evidenced by the presence of interleukin-4 messenger RNA). A matched group of patients with hay fever who had not received immunotherapy was followed as a control for the natural course of the disease.

RESULTS

Scores for seasonal symptoms and the use of rescue antiallergic medication, which included short courses of prednisolone, remained low after the discontinuation of immunotherapy, and there was no significant difference between patients who continued immunotherapy and those who discontinued it. Symptom scores in both treatment groups (median areas under the curve in 1995, 921 for continuation of immunotherapy and 504 for discontinuation of immunotherapy; P=0.60) were markedly lower than those in the group that had not received immunotherapy (median value in 1995, 2863). Although there was a tendency for immediate sensitivity to allergen to return late after discontinuation, there was a sustained reduction in the late skin response and associated CD3+ T-cell infiltration and interleukin-4 messenger RNA expression.

CONCLUSIONS

Immunotherapy for grass-pollen allergy for three to four years induces prolonged clinical remission accompanied by a persistent alteration in immunologic reactivity.

Increased glucocorticoid receptor beta in airway cells of glucocorticoid-insensitive asthma

Glucocorticoid (GC)-insensitive asthma is a challenging clinical problem that can be associated with life-threatening disease progression. The molecular basis of GC insensitivity is unknown. Alternative splicing of the GC receptor (GCR) pre-mRNA generates a second GCR, termed GCRbeta, which does not bind GC but antagonizes the transactivating activity of the classic GCR. Thus increased expression of GCRbeta could account for glucocorticoid insensitivity. Bronchoalveolar lavage (BAL) cells and peripheral blood mononuclear cells (PBMC) were examined for GCRbeta immunoreactivity using a GCRbeta-specific antibody by immunohistochemical staining. Cell localization of GCRbeta expression was performed using a double immunostaining technique. Patients with GC-insensitive asthma expressed a significantly higher number of GCRbeta-immunoreactive cells in their BAL and peripheral blood than GC-sensitive asthmatics or normal control subjects. Furthermore, GCRbeta expression in GC-insensitive asthma was particularly high in airway T cells, which are thought to play a major role in the pathogenesis of asthma. We also examined the expression of GCRbeta in specimens from the airways of patients with chronic bronchitis. In chronic bronchitis, few cells were GCRbeta-positive and their numbers did not differ significantly from normal control subjects. We conclude that GC-insensitive asthma is associated with increased expression of GCRbeta in airway T cells.

Cellular infiltration and cytokine mRNA expression in perennial allergic rhinitis

BACKGROUND

Allergen challenge in allergic rhinitis patients leads to local eosinophilia and Th2-type cytokine expression. Natural exposure to grass pollen is additionally characterized by epithelial mast-cell infiltration. We hypothesized that perennial allergic rhinitis is also associated with T-cell and eosinophil infiltration of the nasal mucosa, local Th2-type cytokine expression, and increased numbers of nasal epithelial mast cells.

METHODS

Nasal biopsies from perennial allergic rhinitis patients and controls were analysed by immunocytochemistry for different cell populations and in situ hybridization for cytokine mRNA-expressing cells.

RESULTS

Perennial allergic rhinitis was associated with increased numbers of submucosal CD3+ T cells (P=0.05), EG2+ activated eosinophils (P=0.01), and CD68+ macrophages (P=0.01) compared to controls. Epithelial, but not submucosal, tryptase-positive mast cells were also elevated in rhinitics compared to controls (P=0.01). The numbers of cells expressing interleukin (IL)-5 were higher (P=0.01) and the numbers of cells expressing IL-2 were lower (P=0.04) in rhinitic patients than controls. There were no significant differences for either IL-4 or interferon-gamma between the groups.

CONCLUSIONS

Perennial allergic rhinitis is characterized by mast-cell migration into the epithelium; submucosal infiltration by T cells, eosinophils, and macrophages; and an imbalance in local T-cell cytokine production in favour of enhanced IL-5 and reduced IL-2 expression.

Eotaxin and monocyte chemotactic protein-4 mRNA expression in small airways of asthmatic and nonasthmatic individuals

BACKGROUND

Although an eosinophilic infiltrate has been observed in the small airways of asthmatic individuals, the mechanisms responsible for cellular recruitment in the lung periphery remain to be clarified. Eotaxin and monocyte chemotactic protein (MCP)-4 are 2 eosinophil-associated chemokines shown to be upregulated at sites of allergic inflammation. However, their expression within the small airways of asthmatic individuals remains to be elucidated.

OBJECTIVE

We sought to determine the expression of eotaxin and MCP-4 in the peripheral airways and parenchyma of lungs of subjects with asthma and to assess their relationship to the numbers of resident eosinophils.

METHODS

We examined surgically resected lung tissue from 6 asthmatic and 10 nonasthmatic subjects for the presence of eotaxin and MCP-4 mRNA by in situ hybridization. Chemokine mRNA expression was examined with respect to the numbers of eosinophils within the airways, as detected by immunocytochemistry for major basic protein.

RESULTS

Numbers of chemokine mRNA-positive cells were significantly increased in the large and small airways of asthmatic subjects compared with nonasthmatic subjects. Although eotaxin and MCP-4 mRNA were widely expressed in the lungs of subjects with asthma, their expression was particularly evident within the bronchial epithelium and inflammatory cells. In the airways of the asthmatic individuals, the expression of eotaxin mRNA was significantly correlated to the numbers of eosinophils present.

CONCLUSION

There is an increased expression of eotaxin and MCP-4 mRNA within the peripheral airways of lungs of asthmatic subjects, suggesting that these chemokines contribute to the small airways and peripheral lung inflammation in asthma.

IL-4 and IL-5 mRNA expression in induced sputum of asthmatic subjects: comparison with bronchial wash

BACKGROUND

The local production of TH2 -type cytokines is thought to orchestrate the ongoing eosinophilic inflammation and contribute to the pathophysiologic features of allergic asthma. Previous studies investigating cytokine expression in asthmatic individuals have used invasive fiberoptic bronchoscopy techniques. To date, there have been no reports of cytokine mRNA expression in induced sputum as a means of quantifying local inflammatory events.

OBJECTIVES

We examined whether IL-4, IL-5, and IFN-gamma mRNA expression could be detected in cells from induced sputum in subjects with mild asthma and normal control subjects. In addition, we compared the profile of inflammatory cells and cytokine mRNA in sputum and bronchial wash fluid.

METHODS

Cells positive for IL-4, IL-5, and IFN-gamma mRNA were determined by using in situ hybridization on cytospun aliquots of sputum induced by successive inhalations of hypertonic saline. Inflammatory cells were quantified by using immunologic cell surface markers and immunocytochemistry.

RESULTS

IL-4 and IL-5 mRNA were detected in the sputum of all asthmatic subjects, and the number of cells expressing these cytokines was significantly higher than that found in control subjects. Colocalization studies showed CD3-positive T cells were the major sources of IL-4 and IL-5 mRNA.

CONCLUSIONS

This study demonstrates that induced sputum can be used to detect mRNA for TH2 -type cytokines in bronchial asthma and that the increase in IL-4 and IL-5 mRNA expression is similar to that seen with more invasive techniques. The qualitative differences in inflammatory cell numbers between sputum induction and bronchial wash are consistent with their sampling of different airway compartments.

Effect of intranasal fluticasone on cellular infiltration, endothelial adhesion molecule expression, and proinflammatory cytokine mRNA in nasal polyp disease

BACKGROUND

Nasal polyp (NP) disease demonstrates a gradual response to treatment with intranasal steroids. We hypothesized that various inflammatory features that promote NP eosinophilia would show a differential sensitivity to treatment with intranasal fluticasone.

OBJECTIVES

We conducted a double-blind, placebo-controlled trial of 4 weeks of intranasal fluticasone propionate or matching placebo to assess their effectiveness in reducing NP inflammatory cells, expression of endothelial vascular cell adhesion molecule (VCAM)-1 and P-selectin, and expression of cytokines involved in induction of a group of adhesion molecules (ie, IL-4, IL-13, TNF-alpha, and IL-1beta).

METHODS

Twenty subjects (9 women and 11 men) with severe chronic sinusitis and NP were studied. Systemic and intranasal steroids were withheld for a minimum of 1 month and 2 weeks, respectively, before the study. Biopsy specimens of NPs were obtained 1 week before and 4 weeks after treatment with intranasal fluticasone 100 microg or placebo per nostril administered twice daily. Biopsy specimens were snap frozen for immunostaining or fixed in paraformaldehyde for in situ hybridization. Pretreatment to posttreatment results were analyzed with Wilcoxon's signed-rank test.

RESULTS

Fluticasone treatment significantly reduced NP eosinophilia (P =.02) and CD4(+) T lymphocytes (P =.02). Eosinophils expressing the marker EG2 were more significantly reduced (P =.007). Fluticasone also reduced the expression of P-selectin (P =.005) and the number of IL-4 and IL-13 mRNA+ cells (P =.02 and.05, respectively). In contrast, fluticasone did not significantly reduce expression of endothelial VCAM-1 or the number of TNF-alpha or IL-1beta mRNA+ cells in the polyps.

CONCLUSIONS

We conclude that intranasal fluticasone reduced NP inflammation but that expression of proinflammatory cytokines and endothelial VCAM-1 were relatively unaffected by fluticasone treatment. These latter inflammatory features may contribute to the persistence of NP disease despite intranasal steroid treatment.

CD4+ T cells can induce airway hyperresponsiveness to allergen challenge in the brown norway rat

Airway hyperresponsiveness to inhalational challenge with methacholine (MCh) develops by 32 h after allergen challenge of actively sensitized BN rats. To test the hypothesis that CD4+ T cells mediate allergen-induced hyperresponsiveness independent of IgE-mediated mechanisms, we administered CD4+ T cells, CD8+ T cells, and a mixture of CD4+ and CD8+ T cells (total T cells) isolated from the cervical lymph nodes of rats sensitized with ovalbumin (OA) to naive BN rats that underwent aerosol challenge with either OA or bovine serum albumin (BSA) 2 d later. Responsiveness to MCh was measured 2 d before transfer of T cells and 32 h after challenge with OA or BSA. Airway responsiveness increased significantly in recipients of CD4+ T cells after OA challenge, but not in any other of the treatment groups. Analysis of bronchoalveolar lavage (BAL) cells for major basic protein expression by immunostaining showed eosinophilia in OA-challenged CD4+ and total T-cell recipients. Cells retrieved by bronchoalveolar lavage showed increased expression of IL-5 mRNA (in situ hybridization) in CD4+ T cell recipients after OA challenge compared with other groups. Interferon-gamma mRNA was expressed to the greatest extent in CD8+ recipients, but it was elevated in both OA- and BSA-challenged animals. We conclude that CD4+ T cells can induce airway hyperresponsiveness after inhalational challenge with allergen and this is associated with IL-5 production and eosinophilia. CD8+ T cells may have a negative regulatory effect on responsiveness, possibly mediated by interferon-gamma.

Antizyme prevents ornithine decarboxylase-mediated cell death in human fibroblasts

Ornithine decarboxylase (ODC) is a key enzyme of polyamine biosynthesis essential for growth-related cellular functions. Apart from its physiological role in cell proliferation, ODC also contributes to the induction of apoptosis under certain conditions, e.g. following growth factor withdrawal. The rate of cell death is a function of its enzyme activity, ODC activity is inhibited by a regulatory protein antizyme, also known to suppress polyamine uptake. We report that forced expression of antizyme prevents ODC-mediated cell death in human gingival fibroblasts under very low serum conditions. These data suggest an important antiapoptotic role for antizyme in cell survival.

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.

Nasal eosinophilia and IL-5 mRNA expression in seasonal allergic rhinitis induced by natural allergen exposure: effect of topical corticosteroids

BACKGROUND

Nasal allergen provocation in patients with allergic rhinitis leads to expression of the proeosinophilic cytokines IL-5 and GM-CSF and tissue eosinophilia.

OBJECTIVE

We sought to examine the effect of natural seasonal allergen exposure on IL-5 and GM-CSF mRNA expression and nasal eosinophilia and to evaluate the effects of topical corticosteroid therapy on these responses.

METHODS

Nasal biopsy specimens were collected from 46 grass pollen-sensitive patients with seasonal rhinitis before the grass pollen season. A second biopsy specimen was collected during the pollen season, by which time patients had received 6 weeks treatment with either fluticasone propionate (200 micro(g) twice daily) or placebo nasal spray.

RESULTS

Fluticasone treatment was clinically effective (P <.005). Patients receiving placebo, but not fluticasone, showed increased numbers of epithelial and submucosal EG2+ eosinophils (P <.005) and IL-5 and GM-CSF mRNA-expressing cells (P <.0001) during the pollen season. Colocalization experiments showed that greater than 80% of IL-5 mRNA-expressing cells were submucosal CD3+ T cells in both groups. The numbers of submucosal CD3+ T cells did not increase during the pollen season or decrease with fluticasone treatment. Fluticasone also inhibited IL-5 secretion by grass pollen-stimulated peripheral blood T cells from patients with seasonal rhinitis (n = 5, inhibitory concentration of 50% = 10(-9) to 10(-10) mol/L).

CONCLUSIONS

These results suggest that topical corticosteroids may reduce eosinophilia in seasonal rhinitis by inhibiting T cell IL-5 production.

Intravenous immunoglobulin inhibits IgE production in human B lymphocytes

BACKGROUND

Intravenous immunoglobulin (IVIG) is commonly used as both an immune-enhancing and immune-modulating agent. Treatment with high doses of IVIG diminishes IgE secretion in patients with severe steroid-dependent asthma.

OBJECTIVE

We studied the action of IVIG on IgE production in highly purified B lymphocytes stimulated without additional T cells to determine the action of IVIG on B lymphocytes.

METHODS

Human B cells were purified from tonsils, and T lymphocytes were removed by E-rosetting. B cells were cultured with IL-4 (400 U/mL) and anti-CD40 antibodies (1 microg/mL¿, with or without additional IVIG. Cell proliferation was determined by 3[H]-thymidine uptake, and supernatant IgE was determined by ELISA. Cell cycle analysis was performed by flow cytometry, and IgE transcripts were measured by in situ hybridization.

RESULTS

IVIG (5 mg/mL) decreased B-cell proliferation in IL4/anti-CD40-stimulated B cells by an average of 74% (+/-6%). Addition of IVIG up to 48 hours after initiation of cell culture led to significant diminution of cell proliferation at 96 to 120 hours. This effect was dose dependent, with 10 mg/mL being the most effective and doses under 0.1 mg/mL having minimal effect. IVIG diminished the number of stimulated cells progressing in the cell cycle by 30%, and there was no difference in cell viability between IVIG-treated and IVIG-untreated cells. The production of IgE in culture by anti-CD40/IL4-stimulated B lymphocytes was curtailed by greater than 80% after addition of 5 mg/mL IVIG. This was associated with a decrease in IgE (epsilon) transcripts in IVIG-treated cultures.

CONCLUSION

These data indicate that diminution of IgE production in anti-CD40/IL-4-stimulated B cells by IVIG is due to inhibition of early events related to proliferation and progression in the cell cycle.

Inhibition of gingival collagenase gene expression by dexamethasone

Glucocorticoids are potent immunosuppressants shown to be effective in the treatment of inflammatory diseases. Reportedly, they work, in part, by inhibiting cytokines and other transcription factors including AP-1. In this study we investigated the mechanisms of efficient repression of collagenase gene expression by dexamethasone in the human gingival fibroblast. Northern analyses showed that IL-1-dependent collagenase mRNA production was significantly decreased in the presence of dexamethasone. The influence of dexamethasone on the transcription factor NF-kappaB, STAT3, and AP-1 was investigated by using the gel mobility shift assay with nuclear extracts prepared from the cells grown in the presence of dexamethasone. We observed that in addition to AP-1, binding of NF-kappaB and STAT3 to DNA was also decreased significantly. Additionally, dexamethasone induced the transcription of the I kappaB-alpha gene suggesting that in the presence of dexamethasone, NF-kappaB quickly reassociates with newly synthesized I kappaB-alpha and markedly reduces the amount of NF-kappaB. CAT transfection studies utilizing collagenase promoter demonstrated a dose-dependent transcriptional inhibition of IL-1-induced gingival collagenase gene expression by dexamethasone. These data reveal that collagenase gene expression can be regulated by the impairment of IL-1-stimulated NF-kappaB, STAT3, and AP-1 activities, and can highlight a possible molecular mechanism for the anti-inflammatory effects of glucocorticoids.

Cytokine mRNA expression in asthma is not restricted to the large airways

BACKGROUND

Although previous studies have established the presence of an eosinophil-rich cellular infiltrate in the small airways of asthmatic lungs, the expression of cytokines within the peripheral airways has been largely unexplored. The purpose of our study was to test the hypothesis that TH2-type cytokines are increased in the peripheral airways and parenchyma of asthmatic lungs.

METHODS

The presence of messenger ribonucleic acid (mRNA) encoding both T-helper (TH1)-type (IL-2, interferon-gamma) and TH2-type (IL-4, IL-5) cytokines in surgically resected lungs from six asthmatic and 10 nonasthmatic subjects was determined by in situ hybridization. Colocalization of IL-5 mRNA within the large and small airways was performed by simultaneous in situ hybridization and immunocytochemistry.

RESULTS

Expression of IL-5 mRNA-positive cells was significantly increased in the large and small airways and in the lung parenchyma of asthmatic subjects compared with nonasthmatic subjects. In the asthmatic individuals, the expression of IL-5 mRNA was increased in the small airways compared with the large airways. There was also an increase in the number of cells expressing IL-4 mRNA in the large and small asthmatic airways compared with the nonasthmatic airways. In contrast, the numbers of IL-2 and interferon-gamma mRNA-positive cells did not differ between asthmatic and nonasthmatic individuals.

CONCLUSIONS

We conclude that there is an increased expression of TH2-type cytokines within the peripheral airways of asthmatic lungs and suggest that the small airways contribute to the pathophysiology of asthma.

Expression of IL-4, Cepsilon RNA, and Iepsilon RNA in the nasal mucosa of patients with seasonal rhinitis: effect of topical corticosteroids

BACKGROUND

Nasal allergen provocation has demonstrated that allergen-induced rhinitis is associated with an increase in local IL-4 mRNA and IgE heavy chain (Cepsilon) and IgE heavy chain promoter (Iepsilon) RNA and that pretreatment with topical glucocorticosteroids inhibits the increase in these transcripts.

OBJECTIVE

This study was undertaken to determine whether observations made after acute allergen provocation can be extended to the case of chronic exposure experienced during the pollen season.

METHODS

Biopsy specimens were obtained from the inferior turbinate of 33 pollen-sensitive subjects with allergic rhinitis before and during pollen season. Patients were randomized in a double-blind fashion and treated with either topical steroids (200 microg fluticasone propionate twice daily; n = 16) or matched placebo nasal spray (n = 17) before the pollen season. Alkaline phosphatase anti-alkaline phosphatase immunocytochemistry was used to identify B cells (CD20+), and in situ hybridization was used to detect IL-4, Cepsilon, and Iepsilon RNA+ cells.

RESULTS

Baseline examination revealed IL-4 and Cepsilon RNA but virtually no Iepsilon RNA+ cells in the nasal mucosa. Analysis revealed a significant difference in the expression of Cepsilon and Iepsilon RNA+ cells (p < 0.001). Biopsy specimens taken after antigen exposure exhibited highly significant increases in placebo-treated (p < 0.001) but not steroid-treated patients. In both groups, the number of CD20+ cells was unchanged when preexposure and postexposure biopsy specimens were compared.

CONCLUSIONS

These results show strong support for the hypothesis that IgE class switching occurs locally within the nasal mucosa of subjects with seasonal allergic rhinitis and that this response can be inhibited through strategies directed against local IgE production.

Expression of epsilon germ-line gene transcripts and mRNA for the epsilon heavy chain of IgE in nasal B cells and the effects of topical corticosteroid

We have studied the expression of the gene encoding the epsilon heavy chain of IgE in nasal B cells of hayfever patients. We developed probes to detect transcripts of the epsilon germ-line gene and the rearranged gene by in situ hybridization of biopsy sections from the nasal mucosa. We compared tissue from hayfever patients out of season with that of normal controls, and also of hayfever patients treated with topical corticosteroid (fluticasone propionate) or placebo for 6 weeks and then challenged with antigen. epsilon chain mRNA was expressed in an unexpectedly high proportion of nasal B cells of both hayfever patients and normal subjects. However, although similar numbers of B cells were found in both groups, the proportion of cells that express epsilon chain mRNA was several times higher in the hayfever patients. No transcripts of the epsilon germ-line gene were detected in either group before allergen challenge. When hayfever patients were administered antigen locally, early (10-30 min) and late (1-24 h) symptoms ensued. After 24 h, coincident with an increase in the number of cells expressing mRNA for IL-4 in the tissue, epsilon germ-line gene transcripts appeared in the nasal B cells. The induction by allergen of IL-4 mRNA and epsilon germ-line gene transcripts was suppressed by fluticasone propionate treatment. Our results suggest that local IgE synthesis and cytokine regulation of heavy chain switching to IgE occur in the nasal mucosa.

Local IgE production in nasal allergy

IgE mediates allergic reactions by binding to the high-affinity receptor, Fc epsilonR1, on mast cells and basophils at mucosal surfaces; then cross-linking of the receptor by multivalent antigen triggers the allergic response. We demonstrate here that B cells in the nasal mucosa of patients with hay fever express IgE. The results also suggest that allergen-induced heavy-chain switching to IgE occurs locally within the nasal mucosa. Local IgE synthesis may explain why some 'atopic' patients develop rhinitis whereas others have either no clinical manifestations or develop atopic disease elsewhere.

Structure of active chromatin: isolation and characterization of transcriptionally active chromatin from rat liver

Rat liver nuclei were isolated in low-ionic-strength buffer in the absence of bi- and multi-valent cations. Digestion of these nuclei by endogenous nuclease, micrococcal nuclease and DNase I revealed that a minor chromatin fraction was preferentially digested into poly- and oligo-nucleosomes. Southern blot hybridization with various active gene probes confirmed that these chromatin fragments represent coding and 5' upstream regions of transcriptionally active chromatin. Active chromatin fragments were released selectively into the medium, with inactive chromatin remaining inside the nuclei, under the above ionic conditions. The inclusion of bivalent cations during the digestion of nuclei reversed the solubility behaviour of active chromatin. Rearrangement and exchange of histone H1 between chromatin fragments was prevented by using low-salt conditions in all steps in the absence of bivalent cations. All histones, including H1, were present in stoichiometric amounts in this active chromatin fraction. Active nucleosomes showed a lower electrophoretic mobility than bulk nucleosomes in an acrylamide/agarose composite gel in the absence of Mg2+, but were selectively bound to the gel in the presence of this ion.

Structure of active chromatin: higher-order folding of transcriptionally active chromatin in control and hypothyroid rat liver

Investigation have been carried out into the salt-induced higher-order folding in the transcriptionally active chromatin region of rat liver nuclei by nuclease digestion, sedimentation and CD. The sensitivity of active chromatin in nuclei to micrococcal nuclease was suppressed by raising the ionic strength from 25 to 90 mM, indicating the occurrence of salt-induced condensation. The rate of sedimentation of fractionated inactive chromatin fragments of both moderate (approximately 3.5 kbp) and large (approximately 8.8 kbp) size increased maximally to the same extent, while that of active chromatin fragments was dependent on their size. The rate of sedimentation of moderately sized active chromatin fragments (approximately 5.5 kbp) showed a maximal 15% increase at 90 mM ionic strength. In contrast, a large increase (at least 60%) in the sedimentation rate of large active chromatin fragments (approximately 21 kbp) was observed at 65 mM ionic strength. A reasonable degree of higher-order folding was observed in large active chromatin fragment even at 25 mM ionic strength. On considering the percentage increase in sedimentation rate as a measure of the higher-order folding of chromatin, a different type of higher-order folding was observed in active chromatin fragments. Although the percentage increase in sedimentation decreased from 40 to 24% with an increase in the size of active chromatin from approximately 3 to approximately 9 kbp, a further increase in size up to 16 kbp brought the percentage increase back to 40%. CD studies agreed with the conclusions drawn from sedimentation studies. Active chromatin from hypothyroid rats showed similar folding behaviour, but the order of folding was slightly lower than for control active chromatin, at all sizes.

Increases in IL-12 messenger RNA+ cells accompany inhibition of allergen-induced late skin responses after successful grass pollen immunotherapy

IL-12, a novel cytokine produced by tissue macrophages and B lymphocytes, stimulates proliferation of TH1-type T lymphocytes. We recently showed that in patients with summer hay fever, immunotherapy was effective and was associated with inhibition of allergen-induced late skin responses and increases in local interferon-gamma messenger RNA-positive cells. In this study 10 patients were reassessed after 4 years of immunotherapy and compared with 10 untreated patients with hay fever. Intradermal grass pollen challenge was performed, the late response was measured, and biopsies were performed at 24 hours. In situ hybridization of biopsy sections was performed by using a riboprobe coding for IL-12 mRNA. When immunotherapy and control subjects were compared, there was a marked reduction in the size of the late skin response (p = 0.0001). Significant increases in allergen-induced IL-12 mRNA+ cells in cutaneous biopsy specimens occurred only in the immunotherapy-treated group (all 10 patients, p = 0.002). At allergen-challenged sites, IL-12+ cells correlated positively with interferon-gamma + cells (r = 0.64, p < 0.05) and inversely with IL-4+ cells (r = -0.67, p < 0.05). The principal cell source (55% to 80%) of IL-12 message was the tissue macrophage (CD68+ cells). We suggest that IL-12 may promote TH1 responses and inhibit late-phase responses after successful immunotherapy.

Adoptively transferred late allergic airway responses are associated with Th2-type cytokines in the rat

Late allergic airway responses can be transferred by CD4+ T cells in the rat. To investigate the role of T-cell cytokines in these responses, we examined the expression of mRNA for Th2 (interleukin [IL]-4 and IL-5) and Th1 (IL-2 and interferon gamma [INF-gamma])-type cytokines in Brown Norway rats that were administered either antigen-primed W3/25(CD4)+ or OX8(CD8)+ T cells. Donors were actively sensitized by subcutaneous injection of ovalbumin (OVA) in the neck and T cells were obtained from the cervical lymph nodes by immunomagnetic cell sorting for administration to unsensitized rats. Control rats received bovine serum albumin (BSA)-primed CD4+ and CD8+ T cells. Two days later, recipient rats were challenged with aerosolized OVA, and bronchoalveolar lavage (BAL) was performed 8 h after challenge. BAL cells expressing mRNA for IL-2, IL-4, IL-5, and INF-gamma were analyzed using the technique of in situ hybridization. Recipients of OVA-primed CD4+ T cells had an increase in the fraction of BAL cells expressing mRNA for IL-4 and IL-5 compared with BSA-primed CD4+ or OVA-primed CD8+ cells (P < 0.001). Recipients of CD8+ T cells had an increase in INF-gamma mRNA expression after OVA challenge compared with recipients of BSA-primed-CD8+ or OVA-primed CD4+ T cells (P < 0.001). In conclusion, T-cell-dependent allergen-induced late responses are associated with the expression of mRNA for IL-4 and IL-5, indicating Th2 cell activation. Furthermore, the increased expression of INF-gamma in allergen challenge recipients of antigen-primed CD8+ T cells suggests that CD8+ T cells may be important in modulating allergic responses.

An improved method to distinguish micrococcal nuclease sensitivity of chromatin

The resolution of the standard micrococcal nuclease assay for sensitivity of active chromatin has been enhanced by the inclusion of an additional step of digesting nuclease-digested DNA with a suitable restriction enzyme prior to Southern hybridization. The improved assay has been used to analyze the chromatin structure of the lamin A, albumin and alpha-fetoprotein genes during rat liver development.

Upregulation of Th-2 cytokine receptors in atopy- and nonatopy-associated chronic sinusitis

OBJECTIVE

This study was conducted to investigate the expression of alpha IL5 and alpha GM-CSF receptors (alpha IL5r and alpha GM-CSFr) mRNA in the paranasal sinus mucosa of atopic and nonatopic subjects with chronic sinusitis compared to controls.

DESIGN

This was a prospective study of patients presenting with the diagnosis of chronic sinusitis of at least 6 months' duration.

METHOD

Fourteen patients with stable chronic sinusitis (7 atopic, 7 nonatopic) and 7 controls were included, from whom sinus mucosal biopsies were obtained and examined for membrane-bound alpha IL5r and alpha GM-CSFr mRNA using in situ hybridization.

RESULTS

There was a significant difference in the number of cells expressing alpha IL5r mRNA per high-power field in both atopic and nonatopic subjects compared to controls, and in the number of cells expressing alpha GM-CSFr mRNA in both atopic and nonatopic subjects compared with controls. The number of alpha IL5r mRNA-positive cells was significantly greater in the atopic versus nonatopic groups, whereas alpha GM-CSFr mRNA-positive cells were greater in number in the nonatopic versus atopic groups.

CONCLUSION

Both alpha IL5r and alpha GM-CSFr are upregulated in chronic sinusitis, suggesting that increases in both Th-2 cytokines and their receptors may be important in the pathology of the disease. Furthermore, the predominant associations of alpha IL5r with atopic chronic sinusitis and alpha GM-CSFr with nonatopic chronic sinusitis suggest that the chronic inflammation in this condition may arise from differential activation of distinct cytokine pathways depending on whether or not there is associated atopy.

Interleukin-13 and interleukin-4 are coexpressed in atopic asthma

Interleukin-4 (IL-4) is an important cytokine in the allergic inflammation associated with atopic asthma. Interleukin-13 shares many of the biological effects of IL-4, and the evidence suggests that the expression of these two cytokine genes may be coregulated. We have investigated the expression of IL-13 and IL-4 mRNA in the bronchial mucosa of nine stable atopic asthmatics and 10 normal controls, characterized the major cellular source of IL-13 mRNA, and examined the colocalization of IL-13 and IL-4 mRNA. Endobronchial biopsies were obtained and examined for IL-13 and IL-4 mRNA using radiolabeled in situ hybridization. The number of positive cells per millimeter of basement membrane for both IL-13 and IL-4 mRNA was increased significantly in the bronchial mucosa of atopic asthmatics compared to normal controls (p < .001). In the atopic asthmatics, the expression of IL-13 was significantly greater than that for IL-4 (p < .01). In these subjects, 90% of the IL-13 mRNA-positive cells were CD3-positive T cells. Furthermore, although 100% of IL-4-positive cells also expressed IL-13 mRNA, only 60% of IL-13-positive cells also expressed IL-4. These results demonstrate that, in mild atopic asthma, IL-13 and IL-4 are coexpressed and that the upregulation of IL-13 expression is greater than that of IL-4. Our data support the role of IL-13 in the allergic inflammation present in atopic asthma.

Activation of the lamin A gene during rat liver development

We have studied the regulation of expression of the A-type lamins, which are constituents of the nuclear lamina. During rat liver development, high levels of lamin A and C mRNAs were observed in 15-day fetal liver but were barely detectable in the adult. The chromatin conformation of the lamin A gene was sensitive to DNase I in 15-day fetal liver but became mostly insensitive in the adult. Lamin A and C proteins could be detected in fetal liver and persisted in the adult. Our evidence suggests that the lamin A gene is actively transcribed early in liver differentiation and its activity declines considerably in adult liver.

Grass pollen immunotherapy inhibits allergen-induced infiltration of CD4+ T lymphocytes and eosinophils in the nasal mucosa and increases the number of cells expressing messenger RNA for interferon-gamma

BACKGROUND

Grass pollen injection immunotherapy is effective in patients with summer hay fever, although efficacy must be balanced against possible side effects. The mechanism of immunotherapy is unknown but may be related to its ability to inhibit allergen-induced late responses, which are known to be characterized by infiltration of T lymphocytes, eosinophils, and cells with messenger RNA for so-called TH2-type cytokines (IL-4 and IL-5).

OBJECTIVE

This study was designed to observe the effect of grass pollen immunotherapy on late nasal responses and associated cellular infiltration and cytokine mRNA expression.

METHODS

We performed local nasal provocation with grass pollen (and a control challenge) in 28 patients after a 12-month double-blind, placebo-controlled trial of immunotherapy. Nasal biopsy specimens were obtained at 24 hours and processed for immunohistology and in situ hybridization studies.

RESULTS

Grass pollen immunotherapy inhibited allergen-induced immediate (0 to 60 minutes) increases in sneezing (p < 0.02) and nasal blocking (p < 0.01) and late (0 to 24 hours) nasal symptoms (p < 0.05). Immunotherapy also inhibited the associated infiltration of the nasal mucosa by CD4+ T lymphocytes and total (major basic protein-containing) and "activated" (cationic protein-secreting) eosinophils (all p = 0.03). There was a significant (p = 0.04) increase in cells expressing mRNA for interferon-gamma at 24 hours after allergen challenge, which correlated inversely with patients' seasonal symptoms (r = -0.65, p < 0.05) and medication requirements (r = -0.75, p < 0.02) during the pollen season.

CONCLUSION

The results suggest that successful grass pollen immunotherapy for summer hay fever may act by inhibiting allergen-induced T lymphocyte and eosinophil recruitment and eosinophil activation in the target organ, possibly through a mechanism involving protective local increases in TH1-type cells.

Properties of oligonucleosomes from active genes of rat liver

Active chromatin fraction from rat liver nuclei has been isolated under the lower ionic strength conditions, to prevent salt induced rearrangement and exchange of linker histone H1. Salt induced higher order folding in these oligonucleosomes was determined by sedimentation, viscosity, aggregation and circular dichroism studies. Sedimentation studies indicate that upon raising the ionic strength from 25 mM to 65 mM (mainly NaCl), active oligonucleosomes show intrafragmental interaction and formation of soluble oligomers. These oligomers disaggregate into unfolded monomers at 90 mM ionic strength. In contrast, oligonucleosomes from inactive genes show gradual increase in intrafragmental higher order folding without any interfragmental interaction on raising salt concentration. A much higher decrease in viscosity of active oligonucleosomes in comparison to bulk oligonucleosomes also support the above conclusion. However, on raising salt concentration above 100 mM NaCl, both the chromatin fractions are capable of forming insoluble aggregates. Decrease in the molar ellipticities of bulk oligonucleosomes at 273 and 282 nm is observed on raising ionic strength from 25 mM to 65 mM. A different pattern of this decrease is observed in case of active oligonucleosomes, indicating adaptation of a different type of salt induced secondary structure of DNA in these oligonucleosomes. Melting profile of DNA from active and bulk chromatin suggests that the base composition of both the chromatin fractions is same.

T lymphocytes and mast cells express messenger RNA for interleukin-4 in the nasal mucosa in allergen-induced rhinitis

We have investigated the phenotype of interleukin-4 (IL-4) mRNA+ cells in the nasal mucosa of six subjects with allergic rhinitis before and 24 hr after local allergen provocation with grass pollen extract. Serial cryostat sections were cut from paraformaldehyde-fixed snap-frozen nasal biopsies, and immunocytochemistry (APAAP) followed by in situ hybridization performed on the same sections. For immunocytochemistry, antibodies against CD3, tryptase, major basic protein (MBP) and CD68 were used to identify T cells, mast cells, eosinophils and macrophages, respectively. Hybridization studies were performed using a digoxigenin-labelled IL-4 riboprobe. Nitroblue tetrazolium (NBT) and X-phosphate-5-bromo-4-chloro-3-indoly phosphate (BCIP) served as chromogens to detect hybridization IL-4 mRNA signals. Significant increases in T lymphocytes and eosinophils and in the number of IL-4 mRNA+ cells were observed after allergen challenge. Double immunocytochemistry/in situ hybridization demonstrated that the majority of IL-4 mRNA+ cells after allergen challenge were CD3+ (73.7% +/- 1.6). Lower numbers of IL-4 mRNA hybridization signals were co-localized to tryptase+ cells (26.0% +/- 1.6). In contrast, no IL-4 mRNA hybridization signals were co-localized to either eosinophils or macrophages. These results indicate that after allergen challenge T cells are the principal cellular source of IL-4 mRNA transcripts during human late nasal responses, with a lesser contribution from mast cells.