Eligibility Criteria:
Inclusion Criteria:
* Male or female subject
* Female subjects must have a negative pregnancy test at the Screening and Day -1 Visits (prior to dosing), must be using a reliable form of contraception throughout the trial, or must be of non-childbearing potential as follows:
* Be post-menopausal (their last menstrual period was at least 12 months ago), and have a serum follicle-stimulating hormone (FSH) level consistent with postmenopausal status as determined by the investigator, or
* Have undergone a hysterectomy, a bilateral oophorectomy or a bilateral salpingectomy
* Aged 18 to 55 years
* Hemoglobin level of ≥11.5 g/dL for females and ≥13.0 g/dL for males
* Weigh at least 50 kg, and body mass index (Quetelet index) in the range 18.0-32.0 kg/m2, inclusive
* Forced expiratory volume in 1 second (FEV1) of more than 1.69 L at the Screening Visit
* Ability to comprehend the nature of the trial and any hazards of participating in it. Ability to communicate satisfactorily with the investigator and to participate in, and comply with the requirements of, the entire trial
* Give written consent to participate after reading the consent form, and after having the opportunity to discuss the trial with the investigator or his/her delegate
Additional Inclusion Criteria for Part 3:
* Documented clinical history of mild asthma (mild as defined by the National Asthma Evaluation and Prevention Program (NAEPP) guidelines) for at least 6 months before the Screening Visit, but otherwise healthy
* FEV1 reversibility (increase of at least 12% and 200 mL in absolute FEV1 from pre bronchodilator value within 15±5 minutes post bronchodilator) at the Screening Visit or during past 12 months
* Values for FEV1 of at least 80% of predicted value and normal FEV1/forced vital capacity (FVC; as defined by NAEPP guidelines). Assessment should be performed without treatment with β2-agonists. If a subject's FEV1 is outside that range at the Screening Visit, the test may be repeated once on another day during the Screening Period
Exclusion Criteria:
* Clinically relevant abnormal medical history, physical findings, ECG, or laboratory values at the screening assessment that could interfere with the objectives of the trial or the safety of the subject (excluding mild asthma in Part 3)
* Subjects who have impaired cardiovascular, endocrine, autoimmune, metabolic, neurological, renal, respiratory (excluding mild asthma in Part 3), gastrointestinal, hepatic, hematological or any other system abnormalities
* Respiratory tract infection within 4 weeks before the Screening Visit
* History of surgery or medical intervention within 6 weeks before the Screening Visit, or planned surgery or medical intervention, that could interfere with the objectives of the trial or the safety of the subject
* Regular treatment (more than 1 month duration) with oral or parenteral corticosteroids in the last year prior to the Screening Visit
* Use of the following prescription medications within 28 days prior to the first dose:
* corticosteroids by any route, androgenic steroids (e.g., testosterone), ritonavir and similar drugs for HIV prophylaxis, ketoconazole, itraconazole or similar azole anti-fungal drugs and macrolide antibiotics (e.g., erythromycin)
* Presence or history of severe adverse reaction to any drug, or sensitivity to components of the trial medication
* Use of a prescription or over-the-counter medicine, nutritional and vitamin supplements, with the exception of acetaminophen and hormonal contraceptives, during the 7 days before the first dose of trial medication. For Part 3 only, inhaled short-acting β2-agonists in addition to acetaminophen and hormonal contraceptives are permitted
* Participation in another clinical trial of a new chemical entity, new device, or a prescription medicine within the 3 months before dosing, or participation within 5 half-lives of receiving an experimental drug (whichever is longer)
* Presence or history of drug or alcohol abuse, or intake of more than 21 units (14 units for women) of alcohol weekly
* Evidence of drug abuse on urine testing, or a positive test for alcohol
* Current smoker; or ex-smokers who (a) gave up less than 1 year ago, or (b) who have a history of more than 10 pack years. A pack year is calculated as the number of cigarettes per day multiplied by number of years smoked divided by 20
* Blood pressure and heart rate at the screening examination outside the ranges 90-140 mmHg systolic, 40-90 mm Hg diastolic, heart rate 40-100 beats/min
* Loss of more than 400 mL blood, e.g., as a blood donor, or donation of blood products, during the 3 months before the Screening Visit
* Positive test for hepatitis B, hepatitis C, or HIV
* History of, or latent, tuberculosis (TB) infection
* Evidence of any other clinically significant infection, including bacterial or viral infections
* Possibility that the subject will not cooperate with the requirements of the protocol, including effective use of the nebulizer
* Employee of the investigational site or the Sponsor, who is directly involved in the trial, or a family member of such a person
Additional Exclusion Criteria for Part 3:
* Any life-threatening asthmatic episode in the past
* Asthmatic episode or respiratory tract infection requiring systemic steroid treatment or hospitalization 3 months prior to the Screening Visit
* Use of inhaled short-acting β2-agonists for \> 2 days/week for symptom relief during 28 days prior to the Screening Visit