Original Article
Copyright ©2012 Baishideng Publishing Group Co., Limited. All rights reserved.
World J Gastroenterol. May 14, 2012; 18(18): 2180-2187
Published online May 14, 2012. doi: 10.3748/wjg.v18.i18.2180
Side-stream smoking reduces intestinal inflammation and increases expression of tight junction proteins
Hui Wang, Jun-Xing Zhao, Nan Hu, Jun Ren, Min Du, Mei-Jun Zhu
Hui Wang, Jun-Xing Zhao, Min Du, Mei-Jun Zhu, Department of Animal Science, University of Wyoming, Laramie, WY 82071, United States
Nan Hu, Jun Ren, School of Pharmacy, University of Wyoming, Laramie, WY 82071, United States
Author contributions: Wang H, Zhao J and Hu N performed the majority of experiments; Ren J, Du M and Zhu MJ designed the study and wrote the manuscript.
Supported by INBRE P20RR016474; USDA-NRI 2008-35203-19084; USDA-AFRI 2009-65203-05716
Correspondence to: Dr. Mei-Jun Zhu, Department of Animal Science, University of Wyoming, Laramie, WY 82071, United States. meijun@uwyo.edu
Telephone: +1-307-7663140 Fax: +1-307-7662355
Received: September 21, 2011
Revised: February 12, 2012
Accepted: April 10, 2012
Published online: May 14, 2012

AIM: To investigate the effect of side-stream smoking on gut microflora composition, intestinal inflammation and expression of tight junction proteins.

METHODS: C57BL/6 mice were exposed to side-stream cigarette smoking for one hour daily over eight weeks. Cecal contents were collected for microbial composition analysis. Large intestine was collected for immunoblotting and quantitative reverse transcriptase polymerase chain reaction analyses of the inflammatory pathway and tight junction proteins.

RESULTS: Side-stream smoking induced significant changes in the gut microbiota with increased mouse intestinal bacteria, Clostridium but decreased Fermicutes (Lactoccoci and Ruminococcus), Enterobacteriaceae family and Segmented filamentous baceteria compared to the control mice. Meanwhile, side-stream smoking inhibited the nuclear factor-κB pathway with reduced phosphorylation of p65 and IκBα, accompanied with unchanged mRNA expression of tumor necrosis factor-α or interleukin-6. The contents of tight junction proteins, claudin3 and ZO2 were up-regulated in the large intestine of mice exposed side-stream smoking. In addition, side-stream smoking increased c-Jun N-terminal kinase and p38 MAPK kinase signaling, while inhibiting AMP-activated protein kinase in the large intestine.

CONCLUSION: Side-stream smoking altered gut microflora composition and reduced the inflammatory response, which was associated with increased expression of tight junction proteins.

Keywords: Inflammation, Microbiota, Tight junction protein, Side-stream smoking, Intestine