Airway epithelial cells from asthmatic children differentially express proremodeling factors

BACKGROUND

The airway epithelium can express factors that drive subepithelial airway remodeling. TGF-β2, vascular epithelial growth factor (VEGF), a disintegrin and metalloprotease 33 (ADAM33), and periostin are hypothesized to be involved in subepithelial remodeling and are overexpressed in adult asthmatic airways. Epidemiologic data suggest that lung function deficits in asthmatic patients are acquired in childhood.

OBJECTIVES

We sought to determine whether airway epithelial cells (AECs) from asthmatic children differentially express TGF-β2, VEGF, ADAM33, or periostin compared with cells from atopic nonasthmatic and healthy children intrinsically or in response to IL-4/IL-13 stimulation.

METHODS

Bronchial and nasal epithelial cells were obtained from brushings from well-characterized asthmatic (n = 16), atopic nonasthmatic (n = 9), and healthy (n = 15) children after achievement of anesthesia for elective procedures. After differentiation at an air-liquid interface (ALI) for 3 weeks, conditioned media were sampled and RNA was extracted from unstimulated and IL-4/IL-13-stimulated cultures. TGF-β2 and VEGF levels were measured with ELISA. ADAM33 and periostin expression was assessed by using real-time PCR.

RESULTS

TGF-β2 and VEGF production was significantly greater in bronchial and nasal ALI cultures from asthmatic children than in cultures from atopic nonasthmatic and healthy children. TGF-β2 levels increased significantly in asthmatic cultures after IL-4/IL-13 stimulation. Within-subject correlation between nasal and bronchial ALI production of TGF-β2 (r = 0.64, P = .001) and VEGF (r = 0.73, P < .001) was good. Periostin expression was 3.7-fold higher in bronchial cells (P < .001) and 3.9-fold higher in nasal cells (P < .004) from asthmatic children than in cells from atopic nonasthmatic or healthy children. ADAM33 was not differentially expressed by AECs from asthmatic patients compared with that from cells from atopic nonasthmatic or healthy children.

CONCLUSION

AECs from asthmatic children differentially express TGF-β2, VEGF, and periostin compared with cells from atopic nonasthmatic and healthy children. Nasal epithelial cells might be a suitable surrogate for bronchial cells that could facilitate investigation of the airway epithelium in future longitudinal pediatric studies.

Information retrieved from a database and the augmentation of personal knowledge

OBJECTIVE

To assess the degree to which information retrieved from a biomedical database can augment personal knowledge in addressing novel problems, and how the ability to retrieve information evolves over time.

DESIGN

This longitudinal study comprised three assessments of two cohorts of medical students. The first assessment occurred just before student course experience in bacteriology, the second occurred just after the course, and the third occurred five months later. At each assessment, the students were initially given a set of bacteriology problems to solve using their personal knowledge only. Each student was then reassigned a sample of problems he or she had answered incorrectly, to work again with assistance from a database containing information about bacteria and bacteriologic concepts. The initial pass through the problems generated a "personal knowledge" score; the second pass generated a "database-assisted" score for each student at each assessment.

RESULTS

Over two cohorts, students' personal knowledge scores were very low (approximately 12%) at the first assessment. They rose substantially at the second assessment (approximately 48%) but decreased six months later (approximately 25%). By contrast, database-assisted scores rose linearly: from approximately 44% at the first assessment to approximately 57% at the second assessment, to approximately 75% at the third assessment.

CONCLUSION

The persistent increase in database-assisted scores, even when personal knowledge had attenuated, was the most remarkable finding of this study. While some of the increase may be attributed to artifacts of the design, the pattern seems to result from the retained ability to recognize problem-relevant information in a database even when it cannot be recalled.

Database access and problem solving in the basic sciences

This study examined the potential contribution that access to a database of biomedical information may offer in support of problem-solving exercises when personal knowledge is inadequate. Thirty-six medical students were assessed over four occasions and three domains in the basic sciences: bacteriology, pharmacology, and toxicology. Each assessment consisted of a two-pass protocol in which students were first assessed for their personal knowledge of a domain with a short-answer problem set. Then, for a sample of problems they had missed, they were asked to use a database, INQUIRER, to respond to questions which they had been unable to address with their personal knowledge. Results indicate that for a domain in which the database is well-integrated in course activities, useful retrieval of information which augmented personal knowledge increased over three assessment occasions, even continuing to increase several months after course exposure and experience with the database. For all domains, even at assessments prior to course exposure, students were able to moderately extend their ability to solve problems through access to the INQUIRER database.