Synthesis of Toll-like receptor 4 in Kupffer cells and its role in alcohol-induced liver disease.
OBJECTIVE
To observe the synthesis of Toll-like receptor (TLR) 4 protein and its mRNA expression in Kupffer cells (KCs) and evaluate the role of TLR 4 in liver injury to rats through alcohol-induced liver disease.


METHODS
Twenty-eight Wistar rats were divided into two groups: ethanol-fed (group E) and control (group C). Group E rats were given ethanol at a dose of 5 - 12 g x kg(-1) x d(-1), while group C received dextrose. Animals from both groups were killed at 4 and 8 weeks. The KCs were isolated and synthesis of TLR 4 protein was determined by laser scanning confocal microscopy. TLR 4 mRNA expression in KCs was determined by reverse transcription polymerase chain reaction (RT-PCR) analysis. The levels of endotoxin, tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) in plasma were determined. Changes in liver pathology were observed.


RESULTS
Laser scanning confocal microscopy showed that the intensity of fluorescence of TLR 4 protein in group E was stronger than group C. Ethanol administration led to a significant increase in TLR 4 mRNA expression in group E compared with group C (P < 0.05). The concentrations of plasma endotoxin, TNF-alpha and IL-6 were higher in group E than in group C (P < 0.05). Liver sections from rats in group E demonstrated marked pathological changes.


CONCLUSIONS
Ethanol administration can lead to the synthesis of TLR 4 protein and its gene expression in KCs, indicating that TLR 4 may play a major role in the development of alcohol-induced liver injury.
Zuo
Guoqing
G
Department of Digestive Disease, The Second College of Clinical Medicine and The Second Affiliated Hospital, Chongqing University of Medical Sciences, Chongqing 400010, China.
Gong
Jianping
J
Liu
Chang'an
C
Wu
Chuanxin
C
Li
Shengwei
S
Dai
Lili
L
D000818:Animals; D029721:Drosophila Proteins; D005260:Female; D015850:Interleukin-6 / Q000097:blood; D007728:Kupffer Cells / Q000502:physiology*; D018950:Lipopolysaccharide Receptors / Q000502:physiology; D008108:Liver Diseases, Alcoholic / Q000209:etiology* / Q000473:pathology; D008562:Membrane Glycoproteins / Q000235:genetics / Q000502:physiology*; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017208:Rats, Wistar; D011956:Receptors, Cell Surface / Q000235:genetics / Q000502:physiology*; D051197:Toll-Like Receptor 4; D051193:Toll-Like Receptors; D014409:Tumor Necrosis Factor-alpha / Q000032:analysis
D029721:Drosophila Proteins; D015850:Interleukin-6; D018950:Lipopolysaccharide Receptors; D008562:Membrane Glycoproteins; D012333:RNA, Messenger; D011956:Receptors, Cell Surface; C495347:Tlr4 protein, rat; D051197:Toll-Like Receptor 4; D051193:Toll-Like Receptors; D014409:Tumor Necrosis Factor-alpha