The effects of SOCS-1 on liver endotoxin tolerance development induced by a low dose of lipopolysaccharide are related to dampen NF-kappaB-mediated pathway.
BACKGROUND
Endotoxin tolerance is an important mechanism to maintain the homeostasis of liver. It was reported that suppressors of cytokine signalling-1 was a negative regulator of lipopolysaccharide-induced macrophages activation, however, the mechanism underlying endotoxin tolerance and suppressors of cytokine signalling-1 has not been fully elucidated.


OBJECTIVE
Our aim here is to clarify whether suppressors of cytokine signalling-1 was involved in the mechanisms of endotoxin tolerance in liver through dampening nuclear factor-kappaB-mediated pathway.


METHODS
Endotoxin tolerance models of C57BL/6J mice and isolated Kupffer cells were established by pretreating them with a low dose of lipopolysaccharide to observe the changes of suppressors of cytokine signalling-1 expression during endotoxin tolerance inducement. Moreover, a vector-based short hairpin RNA expression system was used to specifically inhibit suppressors of cytokine signalling-1 expression in RAW264.7 macrophage cells to further explore the role of suppressors of cytokine signalling-1 in endotoxin tolerance inducement. The expression of suppressors of cytokine signalling-1 was analysed by immunohistochemistry, reverse transcription-polymerase chain reaction and Western blotting, respectively. The responses to lipopolysaccharide were assessed by the activation of nuclear factor-kappaB and the production of tumour necrosis factor-alpha, which were analysed by ELISA.


RESULTS
The histopathologic changes in the liver of the non-endotoxin tolerance group were more serious than those of the endotoxin tolerance group. The phagocytic activity of Kupffer cells were depressed and suppressors of cytokine signalling-1 expression in the endotoxin tolerance group obviously increased. Endotoxin tolerance also led to a hyporesponse of Kupffer cells to lipopolysaccharide with less activation of nuclear factor-kappaB, less production of tumour necrosis factor-alpha and more expression of suppressors of cytokine signalling-1 than those of non-endotoxin tolerance group. Moreover, the inhibitive effect was partly refracted in pSOCS-1-short hairpin RNA transfected RAW264.7 cells.


CONCLUSIONS
Endotoxin tolerance induced by lipopolysaccharide pretreatment was accompanied with upregulation of suppressors of cytokine signalling-1 and the silence of suppressors of cytokine signalling-1 by RNA interference obviously attenuated this inhibitive effect, indicating that the absence of suppressors of cytokine signalling-1 caused abnormal enhancement of inflammatory cytokine production and suppressors of cytokine signalling-1 was involved in endotoxin tolerance inducement through dampening nuclear factor-kappaB-mediated pathway. Therefore, suppressors of cytokine signalling-1 may be a new target for the clinical treatment of sepsis.
Liu
Z J
ZJ
Center of Liver Transplantation, West China Hospital, Sichuan University, Chengdu 610041, PR China.
Liu
X L
XL
Zhao
J
J
Shi
Y J
YJ
Yan
L N
LN
Chen
X F
XF
Li
X H
XH
You
H B
HB
Xu
F L
FL
Gong
J P
JP
D000818:Animals; D015153:Blotting, Western; D016207:Cytokines / Q000096:biosynthesis* / Q000276:immunology; D004195:Disease Models, Animal; D004731:Endotoxins / Q000276:immunology*; D007150:Immunohistochemistry; D007728:Kupffer Cells / Q000276:immunology / Q000378:metabolism; D008070:Lipopolysaccharides / Q000276:immunology / Q000494:pharmacology*; D008099:Liver / Q000201:enzymology / Q000276:immunology* / Q000473:pathology; D008262:Macrophage Activation / Q000187:drug effects; D008264:Macrophages / Q000187:drug effects / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D016328:NF-kappa B / Q000187:drug effects*; D011897:Random Allocation; D017472:Receptors, Interleukin-1 / Q000096:biosynthesis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000187:drug effects; D000071222:Suppressor of Cytokine Signaling 1 Protein; D050826:Suppressor of Cytokine Signaling Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000378:metabolism
D016207:Cytokines; D004731:Endotoxins; D008070:Lipopolysaccharides; D016328:NF-kappa B; D017472:Receptors, Interleukin-1; C491590:Socs1 protein, mouse; D000071222:Suppressor of Cytokine Signaling 1 Protein; D050826:Suppressor of Cytokine Signaling Proteins; D014409:Tumor Necrosis Factor-alpha