Genetics of Asthma - Bronchoscopy Studies

Background:

Endotoxin or lipopolysaccharide (LPS), a cell wall component of gram-negative bacteria, is
ubiquitous in the environment, and is often present in high concentrations in organic dusts,
as well as in air pollution, and household dusts. There is convincing evidence that
endotoxin exacerbates airflow obstruction and airway inflammation in allergic asthmatics.
Additional findings indicate that allergic airways can enhance the response to inhaled
endotoxin, and that endotoxin can enhance the airway response to allergens. However, when
considering the interaction between endotoxin and allergens, the timing of the exposure
appears to be critical. Emerging evidence suggests that early exposure to endotoxin, a
potent inducer of Th1 type cytokines (IFN-g and IL-12), may minimize the risk of allergen
sensitization which could has profound effects on reducing the risk of developing asthma in
children. Independent of its effect in allergic asthma, several studies demonstrate that
inhalation of air contaminated with endotoxin is associated with the classical features of
asthma (reversible airflow obstruction and airway inflammation, and persistent airway
hyperreactivity and airway remodeling). Epidemiological studies have shown that the
concentration of inhaled endotoxin in the bioaerosol is strongly and consistently associated
with reversible airflow obstruction among cotton workers, agricultural workers, and
fiberglass workers. Importantly, the concentration of endotoxin in the bioaerosol is the
most important occupational exposure associated with the development and progression of
airway disease in agricultural workers. Experimentally, inhalation of endotoxin can cause
reversible airflow obstruction and airway inflammation in previously unexposed healthy study
subjects. The ability of the host to respond to endotoxin is highly variable, and is
influenced in part by genetic factors.:

The rationale for this investigation is based on the following points:

- asthma is caused in large part by both genetic susceptibility and environmental
exposure,

- a variety of immune and non-immune mechanisms can function independently or
interactively to cause airway hyper-reactivity, airflow obstruction, airway
inflammation, and airway remodeling,

- environmental challenges can be used to "narrow the asthma phenotype" and allow one to
investigate unique gene-environment interactions that are involved in the development
of biologically specific forms of asthma,

- genes that are over or under stimulated in the airway epithelia of asthmatics following
inhalation challenge are important in the pathogenesis of asthma

Inclusion Criteria:

- Allergic asthmatic, allergic non-asthmatic, or nonallergic nonasthmatic

- Willing/able to give informed consent & adhere to visit/protocol schedules.

- Screening visit laboratory, C-Xray, EKG, results within normal limits

- Women of childbearing potential must have a negative serum pregnancy test

- Screening Pulmonary function testing above study criteria parameters

Exclusion Criteria:

- Systemic corticosteroid administration for asthma within the previous 90days

- Antibiotic administration within the previous 30 days.

- Viral respiratory infection within the previous 14 days.

- History of severe asthma requiring intubation.

- Occupational exposure to hay or grain dust.

- Significant exposure history to cigarette smoke

- Past or present history of allergen immunotherapy to within the last 10 yrs

- Underlying illnesses that may result in altered lung function

- Students or employees under direct supervision by protocol investigators are
ineligible

- Subjects allergic to medications used (or potentially used) in the study will be
excluded.

- Subjects using aspirin will be excluded

- Subjects who abuse alcohol or illicit substances will be excluded

- Medication use other than for asthma, allergies or contraception

- Other medical or psychological conditions which, in the opinion of the investigator,
might create undue risk to the subject or interfere with the subject's ability to
comply with the protocol requirements

- Nursing mothers

- Other investigational medication within the last 30 days