Deficiency of cyclooxygenases transcripts in cultured primary bronchial epithelial cells of aspirin-sensitive asthmatics.

BACKGROUND

Airway function is actively regulated by epithelium through generating PGE(2), the production of which depends on cyclooxygeneses (COX-1 and COX-2). Analysis of bronchial biopsies and bronchial epithelial cells in culture conducted so far gave conflicting results of expression pattern of these enzymes in healthy subjects and asthmatics patients, with and without aspirin hypersensitivity.

OBJECTIVE

Our aim was to investigate the expression of COX-1 and COX-2 mRNA in primary human bronchial epithelial cells (HBEC) isolated from asthmatics and non-asthmatics.

METHODS

We isolated HBEC from bronchial brushing preparations taken during bronchoscopy of 10 non-asthmatics (NA), 8 aspirin-tolerant asthmatics (ATA) and 9 aspirin-intolerant asthmatics (AIA). HBEC were cultured in serum free medium until 80% confluent. Total cellular RNA was isolated and reversed transcribed using oligo(dT)(15) primers. Real time PCR was performed with primers to COX-1, COX-2, GAPDH and beta-actin in the presence of SYBR green dye. The cycle threshold (C(T)) for COX-1 or COX-2 was normalized using beta-actin and GAPDH as the internal standards.

RESULTS

Not only COX-1 but also COX-2 mRNA were expressed by HBEC without any proinflammatory stimulation. We detected the smallest amount of COX-1 mRNA in the AIA group. The same trend was observed for COX-2 mRNA, though it didn't reach the statistical significance. We also analysed the relationship between DeltaC(TCOX-1) to DeltaC(TCOX-2) by calculating the difference DeltaDeltaC(TCOX-1-COX-2). This analysis revealed that AIA group can be characterized by relatively smallest COX-1 mRNA expression in comparison to COX-2. There is a strong positive correlation between C(TCOX1) and C(TCOX2) in NA group (r=0.85; p< 0.001). In both groups of asthmatics this correlation is absent (ATA - r=0.5, p>0.1; AIA - r=0.43, p>0.1).

CONCLUSIONS

Cyclooxygeneases transcripts expression is altered in HBEC derived from the asthmatic patients, and this phenomenon is pronounced in case of aspirin hypersensitivity.