The role of superantigens in human diseases: therapeutic implications for the treatment of skin diseases

Although it is well established that immune mechanisms contribute to the pathogenesis of chronic inflammatory skin diseases such as atopic dermatitis (AD) and psoriasis, the actual events that trigger the immunological pathways resulting in these skin diseases are not well understood. Colonization and infection with Staphylococcus aureus and streptococci has been reported to exacerbate AD and psoriasis. Recent studies demonstrating that bacterial toxins can act as superantigens provide mechanism(s) by which S. aureus and streptococci could mediate an inflammatory skin lesion that consists predominantly of activated T-cells and monocytes. This review will explore the diverse mechanisms by which bacterial superantigens can induce skin inflammation following systemic or local infection. These observations provide a new direction for the development of novel approaches for the treatment of skin inflammation.

Collagen deposition in large airways may not differentiate severe asthma from milder forms of the disease

Chronic airway inflammation and remodeling, including fibrosis, have been proposed as important contributors to asthma pathophysiology. Previous studies of airway fibrosis have been performed mainly in mild and moderate asthmatics at the subepithelial "basement membrane" (SBM) level. The current study was designed to evaluate the large airway SBM thickness and submucosal collagen deposition, as measured by three different collagen staining methods, in endobronchial biopsies from 17 severe, nine moderate, and seven mild asthmatics, as well as eight normal control subjects. Tissue eosinophils and transforming growth factor-beta (TGF-beta) immunoreactivity were also examined. There were no statistically significant differences in the SBM thickness, submucosal collagen deposition, eosinophil numbers, or TGF-beta positive cells among the three groups of asthmatics and the normal control subjects. It was only when examining all asthmatics (n = 33) together, that a modestly thickened SBM (p = 0.04), as evaluated by collagen type III immunostaining, was observed as compared with normal control subjects. Despite this difference, no significant differences were found in the amount of submucosal collagen deposition and the number of eosinophils or TGF-beta expressing cells when comparing total asthmatics and normal control subjects. Additionally, no significant correlations were found between collagen deposition and eosinophil count, TGF-beta expression level, FEV1, or duration of asthma. These results suggest that although increased collagen deposition in the SBM at the large airway level is a characteristic of asthma, it may not explain the differences in severity of asthma.

A randomized, vehicle-controlled trial of tacrolimus ointment for treatment of atopic dermatitis in children. Pediatric Tacrolimus Study Group

BACKGROUND

A topical formulation of tacrolimus, an immunosuppressant currently marketed for the prevention of rejection after solid organ transplant, is a potential therapeutic agent for atopic dermatitis.

OBJECTIVE

We sought to determine the safety and efficacy of tacrolimus ointment in pediatric patients with moderate-to-severe atopic dermatitis.

METHODS

In this double-blind, vehicle-controlled multicenter trial, children ages 7 to 16 years were treated with twice daily application of tacrolimus ointment at 1 of 3 concentrations (0.03% [n = 43], 0.1% [n = 49], or 0.3% [n = 44]) or vehicle (n = 44) for up to 22 days, with a 2-week follow-up period.

RESULTS

The Physician's Global Evaluation of clinical response showed that 69% (95% confidence interval: 53-82) of patients in the 0.03% tacrolimus ointment group, 67% (95% confidence interval: 52-81) in the 0.1% tacrolimus ointment group, and 70% (95% confidence interval: 54-83) in the 0.3% tacrolimus ointment group, compared with 38% (95% confidence interval: 24-54) in the vehicle group, had a marked to excellent (> or =75%) improvement or clearing of their atopic dermatitis (P =.005, .007, and .004, respectively for the 3 tacrolimus groups compared with the vehicle group). The mean percent improvement for a modified Eczema Area and Severity Index at end of treatment for each of the 3 tacrolimus groups (0.03%, 72%; 0.1%, 77%: and 0.3%, 81%) was significantly better than that of the vehicle group (26%; P <.001). The median percent reduction in pruritus was significantly greater for tacrolimus-treated patients (74% to 89%) than for vehicle-treated patients (51%, P = .027). No serious systemic adverse events were noted, and systemic absorption was minimal.

CONCLUSION

Tacrolimus ointment appears to be safe and effective in children with atopic dermatitis.

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.

Application of color Doppler flow mapping to calculate orifice area of St Jude mitral valve

BACKGROUND

The effective orifice area (EOA) of a prosthetic valve is superior to transvalvular gradients as a measure of valve function, but measurement of mitral prosthesis EOA has not been reliable.

METHODS AND RESULTS

In vitro flow across St Jude valves was calculated by hemispheric proximal isovelocity surface area (PISA) and segment-of-spheroid (SOS) methods. For steady and pulsatile conditions, PISA and SOS flows correlated with true flow, but SOS and not PISA underestimated flow. These principles were then used intraoperatively to calculate cardiac output and EOA of newly implanted St Jude mitral valves in 36 patients. Cardiac output by PISA agreed closely with thermodilution (r=0.91, Delta=-0.05+/-0.55 L/min), but SOS underestimated it (r=0.82, Delta=-1.33+/-0.73 L/min). Doppler EOAs correlated with Gorlin equation estimates (r=0.75 for PISA and r=0.68 for SOS, P<0.001) but were smaller than corresponding in vitro EOA estimates.

CONCLUSIONS

Proximal flow convergence methods can calculate forward flow and estimate EOA of St Jude mitral valves, which may improve noninvasive assessment of prosthetic mitral valve obstruction.

GM-CSF, IL-5 and RANTES immunoreactivity and mRNA expression in chronic hyperplastic sinusitis with nasal polyposis (NP)

BACKGROUND

Eosinophils are a prominent feature of chronic hyperplastic sinusitis with nasal polyposis (CHS/NP). Our previous studies showed that their presence was associated with the expression of GM-CSF and RANTES mRNA. In allergic NP, increased expression of IL-5 was also found.

OBJECTIVE

We wished to examine cytokine immunoreactivity for IL-5, GM-CSF and RANTES mRNA in allergic and non-allergic NP and compare immunoreactivity with expression of cytokine mRNA by in situ hybridization. Methods NP were obtained from five allergic and eight non-allergic subjects with CHS/ NP. Middle turbinate tissue from eight normal subjects were used as controls. Cell-associated cytokine mRNA was detected by in situ hybridization (ISH). Cytokine immunoreactive cells were enumerated by immunostaining. Colocalization immunostaining was also performed to identify specific cell types producing IL-5.

RESULTS

Immunostaining for GM-CSF, IL-5 and RANTES protein was increased in both allergic and non-allergic NP compared with control middle turbinates. Allergic polyps contained greater numbers of IL-5 immunoreactive cells (P = 0.01), whereas non-allergic polyps contained greater numbers of GM-CSF immunoreactive cells (P = 0.04). Immunostaining was primarily associated with inflammatory cells, but immunostaining for RANTES and, to a lesser extent GM-CSF, was also seen in the epithelium. The density of immunoreactive cells was variably correlated with cytokine mRNA+ cells (GM-CSF: R=0.56, P=0.05; IL-5: R=0.76, P=0.003; and RANTES: R=0.89, P=0.0005). Colocalization immunostaining revealed that the majority of IL-5 immunoreactive cells in both allergic and non-allergic NP were T lymphocytes. However, allergic NP contained greater numbers of IL-5+/CD3+ T lymphocytes and IL-5+ mast cells, whereas non-allergic NP contained greater numbers of IL-5+ eosinophils.

CONCLUSION

We conclude that GM-CSF, IL-5 and RANTES are produced in increased amounts in both allergic and non-allergic NP. Distinguishing features of non-allergic NP include fewer numbers of CD3 T lymphocytes, fewer IL-5+/CD3+ T lymphocytes and greater numbers of IL-5+ eosinophils. These differences may suggest different mechanisms of eosinophil accumulation and activation in allergic vs non-allergic NP.

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.

Fluticasone propionate results in improved glucocorticoid receptor binding affinity and reduced oral glucocorticoid requirements in severe asthma

BACKGROUND

Inhaled glucocorticoids (iGC) have become important first line agents in the management of moderate-to-severe asthma. Severe asthma is associated with reduced glucocorticoid receptor (GCR) binding affinity.

METHODS

To evaluate the potential impact of inhaled fluticasone propionate on markers of airway inflammation [GCR binding affinity (Kd) and eosinophil cationic protein (ECP)] and oral GC requirements in steroid-dependent asthmatics, we examined the effects of fluticasone propionate (FP) 500 microg or 1000 microg BID and placebo in a double-blind, randomized study of 13 steroid-dependent asthmatics at a single center. Glucocorticoid receptor binding affinity and ECP values were obtained at baseline, 4, 6, 26, and 52 weeks after patients were enrolled into the study. Oral GC dose and FEV1 values were also recorded at each visit.

RESULTS

Inhaled FP resulted in large reductions in oral GC requirement by 6 weeks of therapy while no reduction was seen in the placebo group. All patients in the FP 2000 microg/d group who continued double-blind therapy at 52 weeks were able to eliminate oral prednisone use. In contrast, every patient in the placebo group had to be withdrawn from the study due to poor asthma control. Associated with the oral GC dose reduction on high dose FP therapy, were improvements in GCR binding affinity with the GCR Kd falling from 42.5 nM at baseline to 19.5 nM at 6 weeks (P=.08). The GCR KD values remained stable thereafter with values of 23.5 nM at 26 weeks (P=.02) and 19.5 nM at 52 weeks (P=.01). In addition, high dose FP therapy resulted in reductions in serum ECP values.

CONCLUSION

This study suggests that high dose FP therapy results in significant oral GC sparing effects associated with improved GCR binding affinity and reductions in serum ECP levels in patients with steroid-dependent asthma.

Enhanced expression of B7.2 (CD86) in patients with atopic dermatitis: a potential role in the modulation of IgE synthesis

Recent studies have suggested that the accessory molecules B7.1 (CD80) and B7.2 (CD86) differ in their capacity to generate Th1 vs Th2 responses. Atopic dermatitis (AD) is a chronic allergic skin disease associated with increased IgE synthesis. To determine the potential role of B7.2 molecules in AD, the present study was conducted to compare the expression of B7.1 vs B7.2 on B cells from patients with AD vs normal subjects or patients with psoriasis. The expression of B7.2 on B cells of AD patients (53.67 +/- 3.10%) was significantly higher than normals (38.02 +/- 4.95%; p = 0.02) and psoriasis patients (40.19 +/- 2.70%; p = 0.006). In contrast, there was no significant difference in B7.1 expression among the three subject groups. Interestingly, total serum IgE from AD patients and normal subjects correlated significantly with B7.2 expression on B cells (r = 0.68; p = 0.004), suggesting a role for B7.2+ B cells in IgE synthesis. Indeed, purified B7.2+ B cells produced significantly more IgE than B7.2- B cells in vitro (p = 0.04). Anti-human B7.2, but not B7.1, mAb significantly (p < 0.05) decreased IgE production by PBMC stimulated with IL-4 and anti-CD40 mAb. Furthermore, B7.2+ B cells had a significantly higher level of IL-4R and CD23 expression than B7.1+ B cells. These data demonstrate the predominant expression of B7.2 in AD, but not psoriasis, and a novel role for this molecule in IgE synthesis.

Mechanisms of glucocorticoid-resistant asthma

The term "steroid- or glucocorticoid-resistant (GR) asthma" has been used to describe a group of asthmatics who demonstrate persistent airway obstruction and inflammation despite treatment with high doses of systemic glucocorticoids (GCs). There are at least two forms of GR asthma. The first group of patients has an acquired form of GC resistance. Analysis of their bronchoalveolar lavage (BAL) cells indicates an extremely high level of IL-2 and IL-4 gene expression as compared to BAL cells from GC-sensitive asthmatics. The incubation of T cells from normal individuals with the combination of IL-2 and IL-4 induces GC receptor binding defects, and concomitant GC receptor beta expression, in their cells. Similar abnormalities in GC receptor binding defects can be detected in freshly isolated cells from type 1 GR asthmatics, but this defect is reversible when their cells are cultured in the absence of IL-2 and IL-4. The second group involves patients with primary GC resistance who do not develop side effects on high-dose GCs and have very low numbers of GC receptors in their mononuclear cells. This defect is irreversible in culture and affects their T cells as well as non-T cells. The current studies provide new insights into mechanisms by which inflammation induces GC resistance and how defects in the GC receptor may contribute to chronic inflammation, creating the vicious cycle leading to chronic inflammatory diseases.

Difficult-to-control asthma: clinical characteristics of steroid-insensitive asthma

BACKGROUND

Although widely used, little is known regarding the patterns of response that subjects with severe asthma exhibit to oral glucocorticoid (GC) therapy.

METHODS

We retrospectively reviewed the charts of 164 consecutive adolescents admitted to the National Jewish Medical and Research Center for difficult-to-control asthma. Data collected included medical history, pulmonary function measures by plethysmography, methacholine challenge results, AM cortisol levels, serum IgE, total eosinophil counts (TEC), serum eosinophil cationic protein (ECP), soluble IL-2 receptor (sIL-2R), and spirometry.

RESULTS

Eighty-seven patients (53%) required a GC burst during the hospitalization secondary to poor asthma control. Those requiring a GC burst had a significantly longer history of asthma, a greater degree of bronchial hyperresponsiveness, and lower pulmonary function. Twenty-one patients (24%) failed to respond with a greater than 15% improvement in their AM prebronchodilator FEV1 after the GC burst and were termed steroid insensitive (SI). Although those with SI asthma had a similar duration of asthma, they required oral GC therapy at a younger age, required a larger maintenance oral GC dose on admission, and were more likely to be African-American, compared with those with steroid-sensitive asthma. Furthermore, two distinct spirometry patterns were noted among the SI asthmatic subjects: "chaotic" and "nonchaotic." Patients with the chaotic pattern were characterized by a significant degree of variability (greater than 30%) in daily pulmonary function, whereas those with nonchaotic, SI asthma were characterized by less than 15% variability in daily lung function. Those with nonchaotic SI were diagnosed with asthma and treated with oral GCs at a later age.

CONCLUSIONS

This retrospective study suggests that SI asthma is quite common (25%) among adolescents with severe asthma evaluated at a national referral center. In addition, two distinct patterns of SI asthma have been identified that may constitute different pathophysiologic processes. Finally, the overrepresentation of African-Americans in the SI group supports the need for further epidemiologic studies investigating the prevalence of SI asthma and the impact early asthma intervention may have on this severe form of asthma.

Molecular basis of allergic diseases

This review examines our current understanding of the mechanisms underlying allergic diseases. The IgE molecule plays a central role in the pathogenesis of immediate hypersensitivity reactions by virtue of its capacity to bind specifically to high-affinity IgE receptors on mast cells and mediate the release of various mast cell-derived mediators and proinflammatory cytokines on exposure to allergen. Clinically significant allergic responses are followed by a late-phase response dominated by eosinophils and T lymphocytes. The majority of T cells in allergic responses are memory T cells secreting helper type 2 (TH2)-like cytokines, i.e., interleukin (IL)-4, IL-5, IL-13, but not interferon-gamma. These cytokines regulate IgE synthesis and promote eosinophil development, thus contributing to allergic inflammatory responses. Failure to control immune activation early in the course of allergic disease blunts responses to glucocorticoid therapy and contributes to disease progression. The identification of key cells and molecules involved in the initiation and maintenance of allergic inflammation is likely to become an important target in the treatment of this common group of illnesses.

New insights into steroid resistant asthma

The term "steroid resistant (SR) asthma" refers to a group of asthmatics who have persistent airway obstruction and immune activation despite treatment with high doses of systemic glucocorticoids. There are at least two forms of SR asthma, i.e. primary and acquired types. Type I SR asthma is acquired and is associated with abnormally reduced glucocorticoid receptor (GCR) ligand and DNA binding affinity. Type II SR asthma appears to be due to a constitutive defect and is associated with low numbers of GCRs. An important distinction between these two types of SR asthma is that the GCR defect in Type I, but not Type II, SR asthma is reversible in culture and is sustained by incubation with combination IL-2 and IL-4. Recent studies suggest that the abnormal GCR binding in Type I SR asthma may be due to cytokine-driven alternative splicing of the GCR pre-mRNA to a novel isoform called GCRbeta which does not bind glucocorticoids but antagonizes the transactivating activity of the classic GCR. These GCR changes along with recent evidence for increased transcription factor activation in SR asthma which may inhibit GCR/DNA interactions as well as the selective recruitment of neutrophils into the airways of certain patients with severe asthma contribute to the heterogeneity of mechanisms underlying steroid resistance.

Upregulation of B7.2, but not B7.1, on B cells from patients with allergic asthma

BACKGROUND

Allergic asthma is associated with TH2-like cell responses and increased IgE production. Recent studies in mice have suggested that the costimulatory molecule B7.2 (CD86) may influence the development of TH2 cells.

OBJECTIVE

We sought to determine the potential role of B7.2 in patients with asthma.

METHODS

We performed an analysis of B cells from patients with allergic asthma and healthy control subjects for expression of B7.1 and B7.2 on B cells using five-parameter flow cytometry.

RESULTS

We report that atopic patients with asthma who are exposed to allergens have significantly (p < 0.005) higher levels of B7.2 expression on B cells than atopic asthmatic subjects not exposed to allergen in vivo or nonatopic control subjects. In contrast, there were no differences in B7.1 (CD80) expression among the three study subject groups. When peripheral blood mononuclear cells from asthmatic patients or normal control subjects were stimulated with IL-4 or IL-13, the expression of B7.2, but not B7.1, was significantly increased (p < 0.005) on B cells. Interferon-gamma or IL-12 did not affect the expression of either molecule. The functional significance of B7.2 induction by IL-4 in allergic disease was suggested by the increased expression of this molecule on CD23+, but not CD23-, B cells.

CONCLUSION

These results indicate that the same B cell involved in allergen presentation also expresses the costimulatory molecule B7.2 and support the hypothesis that this molecule is an important costimulatory molecule in allergic responses, the expression of which can be modulated by TH2-like cytokines.

Allergic and immunologic skin disorders

The skin represents a unique immunologic organ poised to protect the host from invading organisms and environmental antigens. The skin is also an important target for a variety of allergic and autoimmune responses. Mast cells are key to the pathogenesis of urticaria, angioedema, and mastocytosis. Atopic dermatitis is the consequence of an immunoregulatory abnormality resulting in a skin-directed T helper type 2 response. Allergic contact dermatitis is an example of classic delayed type hypersensitivity. Circulating autoantibodies against the epidermis are a key mechanism by which bullous skin diseases occur.

Accuracy and cost-effectiveness of exercise echocardiography for detection of coronary artery disease in patients with mitral valve prolapse

Mitral valve prolapse is sometimes associated with chest pain, but this symptom may also be caused by coexisting coronary disease. The accuracy of exercise echocardiography in diagnosing coronary disease in these patients and the most cost-efficient diagnostic approach are unclear. We studied 96 patients (aged 59 +/- 12 years; 70 men) with mitral valve prolapse who underwent exercise electrocardiography, exercise echocardiography, and coronary angiography. The accuracies of seven diagnostic strategies based on the current and expected use of exercise electrocardiography and exercise echocardiography in patients with mitral valve prolapse were examined, with the costs calculated based on Medicare reimbursement. Thirteen (13.5%) patients had significant coronary artery disease. The sensitivity and specificity of exercise electrocardiography in the 71 patients with interpretable electrocardiograms were 50% and 72%, respectively. For the 73 patients who achieved >85% of maximal heart rate, 52 had interpretable exercise electrocardiograms (sensitivity 50%; specificity 69%). Exercise echocardiography had a sensitivity of 69% and a specificity of 98% in the 96 patients and a sensitivity of 82% and a specificity of 96% in patients who achieved >85% of maximal heart rate. Approaches adopting Bayes' theorem and restricting further investigation to patients with at least intermediate pretest probability of coronary disease were the least costly. When combined with exercise echocardiography as the initial test, clinical stratification was associated with a false-negative rate of 21%. The utility of exercise electrocardiography is limited by the high prevalence of resting electrocardiographic abnormalities and suboptimal sensitivity and specificity. The best balance of cost and diagnostic accuracy is to perform exercise echocardiography in patients with at least intermediate probability of coronary artery disease.

Eotaxin mRNA and protein expression in chronic sinusitis and allergen-induced nasal responses in seasonal allergic rhinitis

Eotaxin is an eosinophil-specific chemokine associated with the recruitment of eosinophils to the site of allergic inflammation. The aims of this study were to determine the expression of eotaxin in nasal biopsies from allergic and nonallergic individuals with chronic severe sinusitis, and to examine whether the expression of this chemokine is upregulated following allergen challenge in the nasal mucosa of patients with allergic rhinitis. We also undertook to phenotype of inflammatory cells within the submucosa expressing eotaxin mRNA. Nasal turbinate tissue from 16 individuals with allergic or nonallergic chronic sinusitis and 10 normal controls were examined for the presence of eotaxin mRNA and immunoreactivity by in situ hybridization and immunocytochemistry. The numbers of cells expressing eotaxin mRNA were also determined after either allergen or diluent challenge in atopic subjects with a history of allergic rhinitis. There was a constitutive expression of eotaxin-immunoreactivity and the presence of eotaxin mRNA-positive cells in nasal biopsies from normal individuals. Compared with normal controls, the numbers of cells expressing eotaxin mRNA and protein were significantly increased in both allergic and nonallergic sinusitis (P < 0.001). Eotaxin mRNA was expressed by nasal epithelial cells and primarily colocalized to CD68-positive macrophages within the subepithelium. In subjects with allergic rhinitis, allergen challenge markedly increased the numbers of cells expressing eotaxin mRNA and immunoreactivity in the epithelial and subepithelial cell layers (P < 0.05). This could be largely attributed to a local increase in eotaxin production within the nasal tissues. The results of this study demonstrate the constitutive expression of eotaxin and show that the numbers of cells expressing eotaxin mRNA are increased within the epithelial and subepithelial layers of the nasal mucosa in individuals with chronic sinusitis. Furthermore, allergen challenge of the nasal mucosa in atopic subjects results in a local upregulation of eotaxin expression. These data suggest a potential role for this chemokine in the pathogenesis of allergic and nonallergic eosinophilic inflammation characterizing chronic sinusitis and allergic rhinitis.

Association of glucocorticoid insensitivity with increased expression of glucocorticoid receptor beta

In many chronic inflammatory disorders, glucocorticoid (GC) insensitivity is a challenging clinical problem associated with life-threatening disease progression. The molecular basis of GC insensitivity, however, is unknown. Alternative splicing of the GC receptor (R) pre-messenger RNA generates a second GCR, termed GCR-beta, which does not bind GCs but antagonizes the transactivating activity of the classic GCR, termed GCR-alpha. In the current study, we demonstrate that GC-insensitive asthma is associated with a significantly higher number of GCR-beta-immunoreactive cells in peripheral blood than GC-sensitive asthmatics or normal controls. Furthermore, we show that patients with GC-insensitive asthma have cytokine-induced abnormalities in the DNA binding capability of the GCR. These abnormalities can be reproduced by transfection of cell lines with the GCR-beta gene resulting in significant reduction of their GCR-alpha DNA binding capacity. We conclude that increased expression of GCR-beta is cytokine inducible and may account for GC insensitivity in this common inflammatory condition.

Immunologic basis of chronic allergic diseases: clinical messages from the laboratory bench

During the past decade there have been significant advances in our understanding of the mechanisms underlying allergic responses. Immediate hypersensitivity reactions are mediated primarily by mast cells in an IgE-dependent manner. After the local release of various mediators, proinflammatory cytokines, and chemokines, there is a cell-mediated response that is dominated by eosinophils and T lymphocytes. The majority of T cells in early allergic reactions are memory T cells secreting helper type 2 (TH2)-like cytokines, i.e. IL-4, IL-5, and IL-13, but not interferon-gamma. These cytokines regulate IgE synthesis and promote eosinophil differentiation and cell survival, thus contributing to allergic inflammatory responses. Failure to control immune activation early in the course of allergic inflammation may blunt the response to glucocorticoid therapy and contribute to long-term morbidity of disease. The identification of key cells and cytokines involved in the initiation and maintenance of allergic inflammation is likely to become an important therapeutic target in the future management of this important group of diseases.

Comparison of exhaled nitric oxide, serum eosinophilic cationic protein, and soluble interleukin-2 receptor in exacerbations of pediatric asthma

The hypotheses tested in this study were that during acute asthma exacerbations (1) exhaled nitric oxide concentrations [eNO] are a more sensitive, noninvasive indicator of asthma disease activity than serum markers of inflammation such as eosinophil cationic protein (ECP) or soluble interleukin 2 receptor (sIL2R), and (2) elevated [eNO] are reduced after treatment with glucocorticoids (GC). Peak eNO levels were measured by chemiluminescence during slow expiration. Seven asthmatic subjects (mean age 11 yrs; mean morning FEV1 65% predicted) receiving inhaled GC, and with no radiographic evidence of acute sinusitis, were studied before and after a course of oral GC. Measurements of [eNO], ECP and sIL2R levels, and FEV1% were obtained before and after a course of GC. Six atopic nonasthmatic subjects (mean age 12 years; mean FEV1 94% predicted) and seven normal subjects (mean age 13 years; mean FEV1 100% predicted) were studied. The mean peak [eNO] level (parts per billion: ppb) for the asthma subjects before treatment (52 +/- 5 ppb SEM) was greater than the value for both nonasthmatic atopic and normal subjects (16 +/- 2 ppb and 14 +/- 2 ppb SEM, respectively; P < 0.0001). There was no significant difference in ECP or sIL2R values between asthmatic subjects and either atopic or normal subjects (P > 0.05). Baseline pre-GC treatment ECP levels in the asthmatic subjects were significantly higher (P < 0.002) than post-GC treatment values. The mean peak [eNO] level in the asthmatic subjects declined after oral GC treatment to 14 +/- 1 ppb (P < 0.0002) and was less than 2 ppb different from either control group (P > 0.75). We conclude that [eNO] is a more sensitive marker of asthma disease activity than ECP and sIL2R levels. In addition, [eNO] appears to be a more useful indicator of the beneficial response to GC therapy than these other measurements in pediatric asthma.

Diagnosis and management of steroid-resistant asthma

The term "steroid-resistant (SR) asthma" has been used to describe a group of asthmatics who demonstrate persistent airway obstruction and inflammation despite treatment with high doses of systemic glucocorticoids. There are at least two forms of SR asthma, that is, primary and acquired types. Type I SR asthma is acquired and is associated with abnormally reduced glucocorticoid receptor (GR) ligand and DNA binding affinity. Type II SR asthma is due to a primary GR binding abnormality. An important distinction between these two types of SR asthma is that the GR defect in Type I, but not Type II, SR asthma is reversible in culture and is sustained by incubation with combination IL-2 and IL-4. The treatment of these patients requires a systematic approach to rule out confounding factors, including triggers of immune activation, optimizing steroid therapy, and use of alternative strategies to inhibit airway inflammation.

Bronchoscopic evaluation of severe asthma. Persistent inflammation associated with high dose glucocorticoids

The role of inflammation in the pathogenesis of severe asthma chronically treated with high doses of glucocorticoids is poorly understood. Despite this, treatment has been aimed at advancing anti-inflammatory and immunomodulator therapy. This study was designed to evaluate both the presence and type of airway inflammation in patients with severe asthma. A prospective bronchoscopic study evaluated 14 severe, high-dose oral glucocorticoid dependent asthmatics. Bronchoalveolar lavage fluid was analyzed for cytology and inflammatory mediators. Endobronchial and transbronchial biopsies were performed in selected patients for morphometric evaluation of macrophage/monocytes, neutrophils, eosinophils and lymphocytes. These results were compared with lavage and endo- and transbronchial biopsy studies in normal controls and patients with moderate asthma. The concentration of eosinophils in bronchoalveolar lavage fluid was highest in the moderate asthmatics not on glucocorticoids, with very little difference between normal controls and severe asthmatics (significant difference among the groups, p = 0.007). In contrast, the severe asthmatics demonstrated a twofold higher concentration of neutrophils in lavage than either the mild-moderate asthmatics, or the normal controls (p = 0.032 among the groups, p < 0.05 between the severe asthmatics and both controls). Similar results were obtained in the endobronchial and transbronchial biopsy specimens, which consistently showed significantly higher numbers of neutrophils in the severe asthmatics than in the control groups. The eicosanoid mediators, thromboxane and leukotriene B4, were also highest in the severe asthma group (differences among the groups, p = 0.019 and p = 0.023, respectively). These findings suggest that inflammation remains in severe symptomatic asthmatics despite treatment with high dose glucocorticoids which may be due to the severity of disease, glucocorticoid treatment, or other as yet undefined factors.