Screening Inhaled Allergen Challenge for Dermatophagoides Farinae

Asthma is an increasingly common chronic illness among children and adults, and allergen
exposure is among the most common 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. Previous studies in animal and
in vitro models demonstrate that IL-1β can directly impact three aspects of an airway
inflammatory response: 1). granulocyte (neutrophil/eosinophil) recruitment; 2). non-specific
(23, 24) and allergen-specific airway reactivity; and 3). production and clearance of airway
mucous. Supporting literature and preliminary studies in human subjects further promote the
study of IL-1 blockade for mitigating features of acute allergen-induced asthma exacerbation.

The role of IL-1 in allergen challenge models has not been fully defined. In a study
examining 12 asthmatics allergic to D. farinae at this research center, we found that 9/12
asthmatics had a greater than 10% reduction in forced expiratory volume in 1 second (FEV1)
after inhaled dust mite challenge. These individuals were considered responders. It was
notable that when comparing post-allergen levels of cytokines between responders and
non-responders there was a much greater concentration of IL-1β in post-challenge sputum from
responders vs. nonresponders, Furthermore, within the responders, post challenge IL-1β also
significantly correlated with sputum eosinophil concentrations (r=0.83, P<0.05) and
neutrophil concentrations (r=0.89, P<0.05) 24 hours after allergen challenge. These data
suggest that IL-1β may play a role in both immediate airway hyperresponsiveness and the late
phase recruitment of inflammatory cells (neutrophils and eosinophils) after inhaled allergen
challenge.

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

1. Age range 18-45 years, inclusive

2. FEV1 of at least 80% of predicted and forced expiratory volume in 1 second/forced
vital capacity (FEV1/FVC) 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 intermittent or mild persistent
asthma.

3. Physician diagnosis of asthma

4. Positive methacholine inhalation challenge as performed in the separate screening
protocol within the prior 12 months (defined as provocative concentration of
methacholine of 10 mg/ml or less producing a 20% fall in FEV1 (PC20 methacholine)

5. Allergic sensitization to house dust mite (D. farinae) as confirmed by positive
immediate skin prick test response

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

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

Exclusion Criteria

1. Clinical contraindications:

1. 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.

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

3. 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.

4. 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).

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

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

7. Severe asthma

8. 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.

9. Cigarette smoking >1 pack per month

10. 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.

11. Allergy/sensitivity to study drugs or their formulations

12. Known hypersensitivity to methacholine or to other parasympathomimetic agents

13. History of intubation for asthma

14. 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.

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

2. 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.

3. Usage of the following medications:

1. 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.

2. 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.

3. Use of daily theophylline within the past month.

4. 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).

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

6. 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

7. Use of beta blocking medications

8. Antihistamines in the 5 days prior to allergen challenge

9. Routine use of NSAIDs, including aspirin.

4. Physical/laboratory indications:

1. Abnormalities on lung auscultation

2. Temperature >37.8 C

3. Oxygen saturation of <94%

4. Systolic BP>150 mmHg or <90 mmHg or diastolic BP>90 mmHg or <60 mmHg

5. Inability or unwillingness of a participant to give written informed consent.