The antioxidant, taurine reduced lipopolysaccharide (LPS)-induced generation of ROS, and activation of MAPKs and Bax in cultured pneumocytes.
Lipopolysaccharide (LPS) can cause damage to the epithelia of the respiratory tract. However, taurine can protect the lung tissue from such oxidant-induced inflammation. This study examined the effects of a LPS treatment on the intracellular calcium levels ([Ca(2+)]i) as well as the specific mechanisms of LPS-induced cell death in pneumocytes. In addition, the effects of taurine on the LPS-induced increase in the accumulation of reactive oxygen species (ROS) in pneumocytes were investigated. The [Ca(2+)]i in cultured pneumocytes was determined using microfluorescence techniques. The level of activation of the mitogen-activated protein kinases (MAPKs) and Bax protein were measured by Western blotting. LPS at 10 and 100 ng/ml induced cell death and decreased the viability of MRC-5 cells. Moreover, the intracellular Ca(2+) and ROS levels were increased by LPS. The LPS treatment led to the phosphorylation of ERK1/2, JNK and the activation of Bax. A pretreatment with 20 mM taurine reduced the LPS-induced production of ROS and MARK activity. These results show that a LPS treatment induces cell death in MRC-5 cells by increasing the intracellular ROS and Ca(2+) levels. The increase in the intracellular level of ROS promotes MAPKs activation and Bax translocation. Overall, LPS induces lung cell death by activating MAPKs. Furthermore, taurine decreased the LPS-induced generation of ROS and activation of MAPK and Bax.
Jeon
Seol-Hee
SH
Department of Pharmacology and Toxicology, College of Veterinary Medicine, Chonbuk National University, Jeonju 561-756, Republic of Korea.
Lee
Mun-Young
MY
Rahman
Md Mizanur
MM
Kim
Shang-Jin
SJ
Kim
Gi-Beum
GB
Park
Sang-Youel
SY
Hong
Chul-Un
CU
Kim
Sung-Zoo
SZ
Kim
Jin-Shang
JS
Kang
Hyung-Sub
HS
D056809:Alveolar Epithelial Cells / Q000187:drug effects*; D000975:Antioxidants / Q000494:pharmacology*; D020013:Calcium Signaling / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D004396:Coloring Agents; D004789:Enzyme Activation / Q000187:drug effects; D005347:Fibroblasts / Q000187:drug effects; D006801:Humans; D008070:Lipopolysaccharides / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D008168:Lung / Q000166:cytology* / Q000187:drug effects; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism*; D013654:Taurine / Q000494:pharmacology*; D013778:Tetrazolium Salts; D013844:Thiazoles; D051028:bcl-2-Associated X Protein / Q000378:metabolism*
D000975:Antioxidants; D004396:Coloring Agents; D008070:Lipopolysaccharides; D017382:Reactive Oxygen Species; D013778:Tetrazolium Salts; D013844:Thiazoles; D051028:bcl-2-Associated X Protein; D013654:Taurine; D020928:Mitogen-Activated Protein Kinases; C022616:thiazolyl blue