**2. Atopic dermatitis is associated with asthma**

Asthma frequently develops by the age of 3 yr (1) and recent research has demonstrated that its onset is tending to occur at a younger age (2). Various hypotheses have been suggested with respect to the etiology of asthma. According to the Tucson cohort study performed in the United States, there is a low probability of atopic asthma developing in infants with recurrent wheezing up to the age of 3 yr, and they are considered to be a separate population from the infants in whom recurrent wheezing persists until later childhood (3). In the former group, viral infection is the direct cause of wheezing, while the latter group have an atopic constitution and their asthma may persist during the school years and even into adulthood. Thus, this latter group may be a population for which early intervention is important. It is known that chronic asthma is more likely to develop in patients who are positive in tests for food or house dust allergens (4, 5). The rate of progression to adult asthma is also high among individuals who test positive for food allergens, such as those in

Suplatast Tosilate for Prophylaxis of Pediatric Atopy 291

suggesting the prior existence of asthma, such as wheeze and chronic cough unrelated to respiratory tract infection. Infants who had used oral sodium cromoglycate or other antiallergy drugs within the previous 4 wk (agents that could potentially affect the outcome of this study) were also excluded, but those using topical steroids rated as medium strength

Thirty children were randomly assigned to oral treatment with suplatast tosilate dry syrup (IPD dry syrup 5%, Taiho Pharmaceutical Co. Ltd, Tokyo Japan) at a dose of 3 mg/kg twice daily (the total daily dose was 6 mg/kg) and 30 were assigned to receive ketotifen fumarate dry syrup at dose of 0.03 mg/kg twice daily (the total daily dose was 0.06 mg/kg). Both these drugs were administered for at least 2 yr, and could be continued for up to 4 yr at the request of the parents. After the start of the study, subjects were reviewed at the outpatient department once monthly until completion of the study. Blood was collected at the start and after 6 months of treatment for measurement of the total IgE level; the specific IgE levels for egg white, cow's milk, Der P, and house dust mite; the eosinophil count; and the Th1/Th2 ratio. The primary endpoints of this study were the incidence of asthma and the time to the initial episode of wheezing among the patients in whom asthma occurred. Wheezing was confirmed by the authors via auscultation, and the date of the initial of wheezing, as well as subsequent episodes of wheezing and persistent cough excluding those caused by infection, was recorded in each infant. Asthma was defined as the occurrence of three or more episodes of wheezing associated with expiratory dyspnea, and the day of onset of asthma was defined as the day when the initial episode of wheezing occurred in each patient with asthma. The secondary endpoints of this study were the percentage of patients admitted to hospital because of asthma and changes of the peripheral blood eosinophil count, IgE level, and Th1/Th2 ratio. For the treatment of atopic dermatitis and food allergies, the use of concomitant drugs other than medium-strength to weak topical steroids was not allowed during the study period. After the onset of asthma, antiasthma medications, mainly anti-

The Th1/Th2 ratio was measured by flow cytometry using a FACScan (23). In brief, CD4 positive cells (helper T cells) were isolated. Then Th2 cytokine-positive cells were detected and counted after staining with an anti-IL-4 antibody, while Th1 cytokine – positive cells were identified with an anti-IFN-c antibody, after which the Th1/Th2 ratio was

Serum total IgE was measured using a fluoroenzyme immunoassay (FEIA) (CAP RIST FEIA, Pharmacia, Uppsala, Sweden). The levels of specific IgE for house dust mite, Der P, egg

This study was approved by the Regional Ethics Committee for Human Research at Dokkyo University School of Medicine Hospital. The parents of all patients participating in this

white, and cow's milk were measured using FEIA (CAP RAST FEIA, Pharmacia).

or weak to control atopic dermatitis were permitted to enter the study.

**2.2.2 Study design** 

inflammatory drugs, could be prescribed.

**2.2.3 Measurement of the Th1/Th2 ratio** 

**2.2.4 Measurement of serum total IgE and specific IgE** 

study gave oral and written informed consent.

calculated.

**2.2.5 Ethics** 

eggs or milk, during early infancy (6), while another study has shown that the strongest risk factor for life- threatening asthma is the presence of food allergy (7). Atopic dermatitis was reported to be associated with asthma that has a later onset (8), while inhibition of the occurrence of asthma has been reported in dermatitis patients treated with H1-blocker therapy (9, 10).

#### **2.1 Th2 cytokine inhibitor: Suplatast tosilate**

We have tested the preventive effect of treatment with a Th2 inhibitor, suplatast tosilate. In previous in vitro and in vivo studies, suplatast tosilate has been shown to inhibit the production of IgE antibodies, reduce tissue eosinophil infiltration, and block the production of IL-4 and IL-5 (11–13). More recently, it was shown to prevent goblet cell hyperplasia by blocking IL-13 production (14). According to a study performed in a mouse model of food allergy, suplatast tosilate decreases IL-4 and IL-6 production in the small intestine, and also ameliorates small bowel necrosis (15). In adults with asthma, suplatast tosilate shows comparable anti-inflammatory activity to inhaled steroids (16), as well as improving lung function, asthma symptoms, and airway hyperresponsiveness (16, 17). In patients receiving high-dose inhaled steroids, addition of suplatast tosilate allows the steroid dose to be reduced (18). Furthermore, evaluation by bronchial biopsy has shown that this drug decreases the number of eosinophils and EG2-positive cells in the airway mucosa, as well as inhibiting goblet cell hyperplasia (17, 19). Infants with a family history of atopy and infants in whom atopic disease occurs soon after birth have been reported to show a shift of the Th1-Th2 cytokine balance towards Th2 dominance (20, 21). Accordingly, the Th1-Th2 balance during the early postnatal period is believed to be a key factor in determining whether or not allergy develops.
