LPS-induced inflammation delays the transportation of ASP⁺ due to down-regulation of OCTN1/2 in alveolar epithelial cells

Abstract

Organic cation transporters (OCTNs) can significantly affect drug disposition in alveolar epithelial cells (A549), but this process is not well understood. We investigated the expression and function of OCTN1/2 in A549 cells under different inflammatory status to examine pulmonary drug distribution. This experiment used lipopolysaccharide (LPS)-treated A549 cells to mimic inflammation in alveolar epithelial cells, and the expression of OCTN1/2, interleukin-6 (IL6), IL18, IL1β and tumour necrosis factor-alpha (TNF-α) was investigated by western blot and quantitative real-time PCR (qRT-PCR). The fluorescent compound 4-(4-(dimethylamino)styryl)-N-methylpyridinium iodide (ASP⁺) was chosen as a probe to study the activity of OCTN1/2. OCTN1/2 down-regulation induced by LPS was more pronounced than that in normal control (NC) groups. Experiments further detected the release of inflammatory factors that revealed a negative correlation between OCTN1/2 expression and inflammation secretion in human alveolar epithelial cells exposed to different concentrations of LPS. The Michaelis constant (K_m) and apparent permeability coefficient (P_app) of ASP⁺ were also decreased significantly. Our results thus show that LPS-induced inflammation could inhibit the expression and activity of OCTN1/2 in vitro and reduce the distribution of inhaled medicine in pulmonary diseases.

Keywords:

• OCTN1/2
• inflammation
• distribution
• ASP⁺
• K_m
• P_app
• pulmonary diseases

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

The authors have received support from the National Natural Science Foundation of China (No. 81803868), Natural Science Foundation of Anhui Province (No. 1308085QH153), Natural Science Foundation of Anhui Province (No. 1708085QH196) and Provincial Natural Science Foundation of Universities of Anhui Province (No. KJ2014A109).