Acetylcholine inhalation test in atopic dermatitis

Respiratory symptoms, bronchial hyper-responsiveness, and eosinophilic airway inflammation in patients with moderate-to-severe atopic dermatitis

BACKGROUND

Patients with atopic dermatitis (AD) often have symptoms suggestive of asthma or rhinitis. The prevalence and signs of respiratory disease in AD patients have been studied to a limited extent.

OBJECTIVES

To assess the prevalence and clustering of respiratory symptoms, bronchial hyper-responsiveness (BHR), and eosinophilic airway inflammation in patients with moderate-to-severe AD.

METHODS

Eighty-six consecutive patients with moderate-to-severe AD and 49 randomly selected control subjects without AD were studied by questionnaire, flow volume spirometry, histamine challenge to detect BHR, induced sputum test to detect eosinophilic airway inflammation, and skin prick tests (SPTs) and total serum immunoglobulin (Ig)E measurements to detect atopy.

RESULTS

The patients with AD showed increased risk of physician-diagnosed asthma (36% vs. 2%, odds ratio (OR) 10.1, confidence interval (CI) 1.3-79.7, P=0.03), physician-diagnosed allergic rhinitis (AR) (45% vs. 6%, OR 4.5, CI 1.2-16.7, P=0.02), BHR (51% vs. 10%, OR 5.5, CI 1.5-20.1, P=0.01), and sputum eosinophilia (81% vs. 11%, OR 76.1, CI 9.3-623.5, P<0.0001) compared with the control subjects. In AD patients, elevated s-IgE and positive SPTs were associated with the occurrence of physician-diagnosed asthma and AR, BHR, and the presence of sputum eosinophilia.

CONCLUSIONS

BHR and eosinophilic airway inflammation are more common in patients with AD than in control subjects. The highest prevalences were seen in patients with AD who were SPT positive and had high IgE levels. Longitudinal studies are needed to assess the outcome of patients with signs of airway disease, in order to identify those who need early initiation of asthma treatment.

Transcutaneous oxygen tension measurements during methacholine challenge of prematurity in infants with chronic lung disease

Chronic lung disease (CLD) of prematurity may be caused by a number of insults during mechanical ventilation, including barotrauma and hyperoxia. To evaluate bronchial hyperresponsiveness (BHR) in infants with CLD of prematurity, we measured changes in transcutaneous oxygen tensions (tcPO2) during methacholine inhalation challenge. Twelve infants with CLD and 22 age-matched children without respiratory diseases were enrolled in this study (ages--5 to 36 months; mean age--16.2 months). Serial doses of methacholine were doubled until a 10% decrease in tcPO2 from baseline was reached. The cumulative dose of methacholine inhaled by the time tcPO2 had been reached (Dmin-PO2) was considered to represent the dose at which reactivity to methacholine (RO2meth) had occurred. In the CLD group, Dmin-PO2 (3.50 +/- 0.1 log x milli-units) was significantly lower than in the preterm control infant group (4.31 +/- 0.2 log x milli-units) and the term infant group (4.21 +/- 0.1 log x milli-units) (P = 0.004, P < 0.001). Dmin-PO2 in the preterm control infant group was not significantly different than in the term infant group (P > 0.5). These results suggest that infants who require additional therapeutic oxygen and mechanical ventilation during the early months of life are at risk of developing early-onset, long-lasting respiratory disease that is related to an acquired BHR.

Bronchial hyperresponsiveness in atopic dermatitis

We investigated the prevalence of bronchial asthma, immediate skin reactivity and bronchial hyperresponsiveness in 40 patients with atopic dermatitis (AD). Eight patients reported to have asthma while 29 were found responders to methacholine test (PC20 Mch less than 64 mg/ml) and 21 were skin reactors. The prevalence of skin positive reactions did not differ in responder and non-responder (PC20 Mch greater than 64 mg/ml) groups. Males were more likely both to have bronchial asthma and be responders to methacholine test than females. Moreover, responders had an earlier age of onset of AD than the non-responders. We suggest that bronchial responsiveness should be evaluated in children with AD.

Pruritic dermatitis in asthmatic basenji-greyhound dogs: a model for human atopic dermatitis

A recurrent, nonseasonal pruritic dermatitis manifested as lichenified plaques and as inflammatory nodules and papules in each of fourteen basenji-greyhound (B-G) crossbreed dogs, all of which demonstrated both nonspecific and Ascaris-specific airway hyperreactivity, with changes in pulmonary mechanics of the same order as those seen in symptomatic human asthma. Other features analogous to human atopic disease included blunted cyclic adenosine monophosphate (cAMP) responsiveness to beta adrenergic agents and in vivo release of histamine and slow-reacting substance of anaphylaxis in response to antigen aerosol challenge. The dermatitis appears to be a manifestation of the atopic state in these dogs and may provide an animal model for the study of human atopic dermatitis.

Leukocyte and lymphocyte cyclic AMP responses in atopic eczema

Lymphocytes from subjects with mild and severe atopic eczema were compared with normal control subjects in regard to their cAMP (3';5'-cyclic adenosine monophosphate) responses to a variety of stimulatory agents. Individuals in the severe eczema group were shown to have a significant diminution in their unstimulated lymphocyte cAMP levels and absolute cAMP responses to 0.5 mM theophylline, 0.5 mM theophyline + 1 micronM epinephrine, 10 mM isoproternol, 1 mM isoproterenol, 10 mM salbutamol, and 3 micron M PGE1. Individuals with mild eczema had a reduced response to 0.5 mM theophylline. The severe eczema groups also differed in a number of these responses from a group of 5 subjects with severe psoriasis. Mixed leukocyte cAMP responses to 10 mM isoproterenol also were examined and found to be diminished in individuals with eczema.

Alterations in cyclic adenosine monophosphate metabolism in human bronchial asthma. I. Leukocyte responsiveness to -adrenergic agents

In an effort to better define the role of betaadrenergic blockade in human bronchial asthma, peripheral blood leukocytes and lymphocytes from individuals with this condition were studied for possible alterations in cyclic AMP metabolism. Using a previously described radioimmunoassay to measure cyclic AMP, cells from asthmatic subjects were shown to have a highly significant decrease in their cyclic AMP response to beta-adrenergic agents (isoproterenol, norepinephrine, and epinephrine) by comparison with normal control cells. The alteration in responsiveness was most marked at the time of severe active asthma and returned toward normal during periods of clinical remission. Evidence was presented to indicate that the reduced response in cells from asthmatic individuals was not due to marked alterations in the proportion of T and B lymphocytes. Five normal volunteers were treated with an oral bronchodilator preparation containing theophylline and ephedrine over a 2 wk period without a significant change in the lymphocyte cyclic AMP response. These results provide unambiguous evidence for altered adrenergic responsiveness in bronchial asthma and indicate that purified peripheral blood lymphocytes should be a suitable in vitro system for further elucidation of the abnormality. Despite the reduction in catecholamine responsiveness in the asthmatic population as a whole, major alterations were largely restricted to individuals with severe, chronic asthma. Conclusive evidence for beta-adrenergic blockade in individuals who have not had recent asthmatic symptoms was not obtained, casting some doubt on the theory that bronchial asthma is due to a congenital derangement of cyclic AMP metabolism. Moreover, transient episodes of bronchospasm were often accompanied by a normal cyclic AMP response indicating that episodes of asthma frequently occur in the absence of easily demonstrable adrenergic blockade.