Defective FGFR2 Signaling in the Small Airway Basal Progenitor Cells in COPD

Changes within the small airways of the lungs represent the key element in the mechanism of
COPD, as they precede the development of emphysema and contribute to the progressive decline
in expiratory airflow. One of the key features of COPD is the remodeling of the small airway
epithelium (SAE), and COPD SAE phenotypes are often induced by smoking and broad gene
expression changes in the SAE. Many of the specific mechanisms for maintenance and
regeneration of small airways and differentiated SAE in adult human lungs are largely
unknown, but smoking associated defects in the maintenance of the SAE may be an early event
of COPD. Preliminary data from murine studies have indicated that fibroblast growth factor
receptor 2 (FGFR2) signaling is critical for lung architecture and development, and
preliminary evidence has shown the FGFR2 pathway is down regulated within the small airway
epithelium (SAE) of smokers and smokers with COPD. We hypothesize that the suppression of
FGFR2 signaling in SAE BC stem cells by cigarette smoking causes these cells to become less
potent, shifting the expression of normally differentiated SAE towards the COPD-associated
small airway phenotype and therefore affecting the generation and maintenance of these cells.
Using technologies established in our laboratories, pure populations of BC will be isolated
from the SAE of healthy nonsmokers, healthy smokers, and COPD smokers. The stem/progenitor
cell capacities of the SAE BC of each group will then be analyzed through the use of 3D
modeling. The basic mechanisms of COPD will be tested by focusing on the phenotypes present
in the lungs of COPD patients and comparison to their nonsmoker and healthy smoker
counterparts. The 3 aims will be assessed in parallel, with all aims sharing in the biologic
samples:

Aim 1 (n=60). To determine whether BC from the SAE of COPD smokers have reduced capacity to
generate normally differentiated SAE, e.g initiate airway branching and repair in response to
injury in vitro but generate airway epithelium with the phenotype similar to that present in
SAE of COPD smokers in vivo.

Aim 2 (n=20). To test the hypothesis that FGFR2 signaling is necessary for normal SAE BC stem
cell function and suppression of FGFR2 caused by inhibitors and smoking associated factors
(EGF and TGF- beta) leads an altered stem cell functional phenotype similar to SAE BC from
COPD smokers with reduced capacity as characterized by Aim 1.

Aim 3 (n=40). To assess the hypothesis that increasing FGFR2 signaling and suppressing
smoking induced EGF receptors and TGF-beta pathways will restore the FGFR2 expression and
normalize the capacity of SAE BC stem cells to generate and maintain normally differentiated
SAE.

Samples from newly recruited research subjects will be collected under the IRB approved
protocol "Collection of Airway, Blood and/or Urine Specimens from Subjects for Research
Studies" (IRB # 1204012331) or may have been collected under previous IRB approved
collection protocols: #0005004439, #0005004440, and #0905010391.

Inclusion Criteria:

- Must be capable of providing informed consent

- Males and females, age 18 or older

- Nonsmoking, matched with other groups by age, sex, ethnic/racial group

- Good overall health without history of chronic lung disease, including asthma, and
without recurrent or recent (within 3 months) acute pulmonary disease

- Normal physical examination

- Normal routine laboratory evaluation, including general hematologic studies, general
serologic/ immunologic studies, general biochemical analyses, and urine analysis

- Negative HIV serology

- Normal chest X-ray (PA and lateral)

- Normal electrocardiogram

- Females - not pregnant

- No history of allergies to medications to be used in the bronchoscopy procedure

- Not taking any medications relevant to lung disease or having an effect on the airway
epithelium

- Willingness to participate in the study

Exclusion Criteria:

- Unable to meet the inclusion criteria

- Pregnancy

- Current active infection or acute illness of any kind

- Current alcohol or drug abuse

- Evidence of malignancy within the past 5 years