Identification of Allergic Asthmatics Reactive to Felis Catus (Cat Hair) Allergen Inhalation

Asthma is an increasingly common chronic illness among children and adults, and allergen
exposure is among the most common triggers for asthma exacerbations. Exacerbations of
allergic asthma are characterized by an early phase response (EPR), mediated by release of
preformed mediators like histamine from mast cells, and a late phase response (LPR) 3-7 hours
later mediated by chemokines and cytokines that attract leukocytes such as neutrophils and
eosinophils to the airways, increase mucus production, trigger airway smooth muscle
contraction, and result in airway constriction and airway hyperreactivity (AHR). The LPR does
not occur in the absence of an EPR. The LPR is thought to be predominantly responsible for
the symptoms associated with acute exacerbations of allergic asthma and is often used as the
measure of efficacy in trials of asthma therapeutics.

This group has taken a particular interest in targeting an inflammatory cytokine,
Interleukin-1β, involved in both the early and late phase asthmatic responses to inhaled
allergen in allergic asthmatics. In the lung, interleukin 1 beta (IL-1β) is produced by
numerous cell types (including epithelial cells, macrophages, neutrophils, eosinophils, and
mast cells), where it signals through its receptor to induce transcription of
pro-inflammatory genes (17-19). IL-1β is increased in bronchoalveolar lavage fluid from
persons with symptomatic asthma vs. those with asymptomatic asthma; likewise,
immunohistochemistry of bronchial biopsies of allergic asthmatics reveal increased expression
of IL-1β in both bronchial epithelial cells and macrophages.

In order to better understand the role of IL-1β in allergen-induced airway inflammation,
induced sputum will be obtained to determine if higher baseline sputum IL-1β concentrations
or larger increases in IL-1β following allergen challenge impact non-specific airway
hyperresponsiveness (via methacholine challenge), sputum granulocyte recruitment (neutrophil
and eosinophil counts and exhaled nitric oxide (eNO), a marker of airway eosinophilia), or
changes in expression of inflammatory or allergy-related genes. To this last point, little is
known about the mechanisms contributing to response patterns in allergic asthmatics
undergoing allergen challenge. Changes in gene expression occurring during the window of time
between the EPR and LPR, as these expression changes may dictate whether or not a LPR occurs
or to what extent it occurs.

The goal of this screening protocol is to identify subjects who exhibit both an EPR and LPR
and who will be eligible for enrollment in the yet to be developed IL-1β protocols. Subjects
will undergo a baseline methacholine challenge to establish reactivity, then allergen
exposure, followed 24 hours later by methacholine challenge.

Inclusion Criteria:

- Age range 18-45 years, inclusive

- FEV1 of at least 80% of predicted and FEV1/FVC (Forced Vital Capacity) ratio of at
least 0.7 (without use of bronchodilator medications for 8 hours or long acting beta
agonists for 24 hours), consistent with lung function of persons with no more than
mild episodic or mild persistent asthma.

- Physician diagnosis of asthma

- Allergic sensitization to felis catus (cat hair) as confirmed by positive immediate
skin prick test response

- Negative pregnancy test for females who are not s/p hysterectomy or who have been
amenorrheic for 12 months or more.

- Oxygen saturation of >94% and blood pressure within the following limits: (Systolic
between 150-90 mmHg, Diastolic between 90-60 mmHg).

Exclusion Criteria:

Clinical contraindications:

- Any chronic medical condition considered by the PI as a contraindication to
participation in the study including significant cardiovascular disease, diabetes,
chronic renal disease, chronic thyroid disease, history of chronic infections or
immunodeficiency.

- Physician directed emergency treatment for an asthma exacerbation within the preceding
12 months.

- Exacerbation of asthma more than 2x/week which could be characteristic of a person of
moderate or severe persistent asthma as outlined in the current NHLBI guidelines for
diagnosis and management of asthma.

- Daily requirements for albuterol due to asthma symptoms (cough, wheeze, chest
tightness) which would be characteristic of a person of moderate or severe persistent
asthma as outlined in the current NHLBI guidelines for diagnosis and management of
asthma (not to include prophylactic use of albuterol prior to exercise).

- Viral upper respiratory tract infection within 4 weeks of challenge.

- Any acute infection requiring antibiotics within 6 weeks of exposure or fever of
unknown origin within 6 weeks of challenge.

- Severe asthma

- Mental illness or history of drug or alcohol abuse that, in the opinion of the
investigator, would interfere with the participant's ability to comply with study
requirements.

- Cigarette smoking >1 pack per month

- Nighttime symptoms of cough or wheeze greater than 1x/week at baseline (not during a
clearly recognized viral induced asthma exacerbation) which would be characteristic of
a person of moderate or severe persistent asthma as outlined in the current NHLBI
guidelines for diagnosis and management of asthma.

- Allergy/sensitivity to study drugs or their formulations

- Known hypersensitivity to methacholine or to other parasympathomimetic agents

- History of intubation for asthma

- Unwillingness to avoid coffee, tea, cola drinks, chocolate, or other foods containing
caffeine after midnight on the days that methacholine challenge testing is to be
performed.

- Unwillingness to use reliable contraception if sexually active (IUD, birth control
pills/patch, condoms).

- Pregnancy or nursing a baby. Female volunteers will be asked to use effective birth
control (stable regimen of hormonal contraceptive use for at least 3 months,
intrauterine device placement, tubal ligation or endometrial ablation for at least 3
months through at least one week after study completion) and will provide a urine
sample to test for pregnancy on study days. If the test is positive or the subject has
reason to believe she may be pregnant, she will be dismissed from the study. Women who
have been amenorrheic for 12 months may participate. Male volunteers will be asked to
use condoms for the duration of the study through at least one week after study
completion.

Usage of the following medications:

- Use of systemic steroid therapy within the preceding 12 months for an asthma
exacerbation. All use of systemic steroids in the last year will be reviewed by a
study physician.

- Subjects who are prescribed daily inhaled corticosteroids, cromolyn, or leukotriene
inhibitors (Montelukast or Zafirlukast) will be required to discontinue these
medications at least 2 weeks prior to their screening visit.

- Use of daily theophylline within the past month.

- Daily requirement for albuterol due to asthma symptoms (cough, wheeze, chest
tightness) which would be characteristic of a person of moderate or severe persistent
asthma as outlined in the current NHLBI guidelines for diagnosis and management of
asthma. (Not to include prophylactic use of albuterol prior to exercise).

- Use of any immunosuppressant therapy within the preceding 12 months will be reviewed
by the study physician.

- Receipt of Live Attenuated Influenza Vaccine (LAIV), also known as FluMist®, or any
other live viral vaccine within the prior 30 days, or any vaccine for at least 5 days

- Use of beta blocking medications

- Antihistamines in the 5 days prior to allergen challenge

- Routine use of NSAIDs, including aspirin.

Physical/laboratory indications:

- Abnormalities on lung auscultation

- Temperature >37.8°C

- Oxygen saturation of <94%

- Systolic BP>150 mmHg or <90 mmHg or diastolic BP>90 mmHg or <60 mmHg

- Inability or unwillingness of a participant to give written informed consent