Bile acid aspiration in suspected ventilator-associated pneumonia.
OBJECTIVE
The aims of this study were to measure the levels of bile acids in patients with suspected ventilator-associated pneumonia (VAP) and provide a possible pathway for neutrophilic inflammation to explain its proinflammatory effect on the airway.


METHODS
Bile acid levels were measured by spectrophotometric enzymatic assay, and liquid chromatography mass spectrometry was used to quantify the major bile acids. Alveolar cells were grown on modified air-liquid interface culture inserts, and bile acids were then employed to stimulate the cells. Reverse transcriptase polymerase chain reaction and Western blots were used to determine the involved gene expression and protein levels.


RESULTS
The mean (+/- SE) concentration of total bile acids in tracheal aspirates was 6.2 +/- 2.1 and 1.1 +/- 0.4 mumol/L/g sputum, respectively, for patients with and without VAP (p < 0.05). The interleukin (IL)-8 level was significantly higher in the VAP group (p < 0.05). The major bile acid, chenodeoxycholic acid, stimulated alveolar epithelial cells to increase IL-8 production at both the messenger RNA and protein level through p38 and c-Jun N-terminal kinase (JNK) activation. The selective p38 and JNK inhibitors, as well as dexamethasone, successfully inhibited IL-8 production.


CONCLUSIONS
These data suggest that early intervention to prevent bile acid aspiration may reduce the intensity of neutrophilic inflammation in intubated and mechanically ventilated patients in the ICU.
Wu
Yu-Chung
YC
Division of Thoracic Surgery, Taipei Veterans General Hospital, Taipei, Taiwan; School of Medicine, National Yang-Ming University, Taipei, Taiwan.
Hsu
Po-Kuei
PK
Division of Thoracic Surgery, Taipei Veterans General Hospital, Taipei, Taiwan; School of Medicine, National Yang-Ming University, Taipei, Taiwan.
Su
Kang-Cheng
KC
School of Medicine, National Yang-Ming University, Taipei, Taiwan.
Liu
Lung-Yu
LY
School of Medicine, National Yang-Ming University, Taipei, Taiwan.
Tsai
Cheng-Chien
CC
School of Medicine, National Yang-Ming University, Taipei, Taiwan; School of Nursing, National Yang-Ming University, Taipei, Taiwan.
Tsai
Shu-Ho
SH
Department of Surgery, and the Department of Chest Medicine, Taipei Veterans General Hospital, Taipei, Taiwan.
Hsu
Wen-Hu
WH
Division of Thoracic Surgery, Taipei Veterans General Hospital, Taipei, Taiwan; Department of Surgery, and the Department of Chest Medicine, Taipei Veterans General Hospital, Taipei, Taiwan.
Lee
Yu-Chin
YC
Department of Surgery, and the Department of Chest Medicine, Taipei Veterans General Hospital, Taipei, Taiwan; School of Medicine, National Yang-Ming University, Taipei, Taiwan.
Perng
Diahn-Warng
DW
Department of Surgery, and the Department of Chest Medicine, Taipei Veterans General Hospital, Taipei, Taiwan; School of Medicine, National Yang-Ming University, Taipei, Taiwan. Electronic address: dwperng@vghtpe.gov.tw.