Research

Bronchiolar chemokine expression is different after single versus repeated cigarette smoke exposure

Tomoko Betsuyaku¹ , Ichiro Hamamura² , Junko Hata² , Hiroshi Takahashi² , Hiroaki Mitsuhashi² , Tracy L Adair-Kirk³ , Robert M Senior³ and Masaharu Nishimura¹

¹  First Department of Medicine, Hokkaido University School of Medicine, Kita-15, Nishi-7, Kita-ku, Sapporo, 060-8683, Japan

²  Teijin Institute for Bio-medical Research, Teijin Pharma Ltd., 4-3-2 Asahigaoka, Hino, Tokyo 191-8512, Japan

³  Division of Pulmonary and Critical Care Medicine, Department of Medicine, Washington University School of Medicine and Barnes-Jewish Hospital, 660 So. Euclid Avenue St. Louis, MO 63110, USA

author email corresponding author email

Respiratory Research 2008, 9:7doi:10.1186/1465-9921-9-7

Published:	21 January 2008

Abstract

Background

Bronchioles are critical zones in cigarette smoke (CS)-induced lung inflammation. However, there have been few studies on the in vivo dynamics of cytokine gene expression in bronchiolar epithelial cells in response to CS.

Methods

We subjected C57BL/6J mice to CS (whole body exposure, 90 min/day) for various periods, and used laser capture microdissection to isolate bronchiolar epithelial cells for analysis of mRNA by quantitative reverse transcription-polymerase chain reaction.

Results

We detected enhanced expression of keratinocyte-derived chemokine (KC), macrophage inflammatory protein-2 (MIP-2), tumor necrosis factor-α (TNF-α), and interleukin-1β (IL-1β) by bronchial epithelial cells after 10 consecutive days of CS exposure. This was mirrored by increases in neutrophils and KC, MIP-2, TNF-α, and IL-1β proteins in the bronchoalveolar lavage (BAL) fluid. The initial inhalation of CS resulted in rapid and robust upregulation of KC and MIP-2 with concomitant DNA oxidation within 1 hr, followed by a return to control values within 3 hrs. In contrast, after CS exposure for 10 days, this initial surge was not observed. As the CS exposure was extended to 4, 12, 18 and 24 weeks, the bronchiolar KC and MIP-2 expression and their levels in BAL fluid were relatively dampened compared to those at 10 days. However, neutrophils in BAL fluid continuously increased up to 24 weeks, suggesting that neutrophil accumulation as a result of long-term CS exposure became independent of KC and MIP-2.

Conclusion

These findings indicate variable patterns of bronchiolar epithelial cytokine expression depending on the duration of CS exposure, and that complex mechanisms govern bronchiolar molecular dynamics in vivo.