Hepatic stellate cells primed with cytokines upregulate inflammation in response to peptidoglycan or lipoteichoic acid.
Gram-positive bacterial products such as peptidoglycan (PGN) and lipoteichoic acid (LTA) are potent stimulators of innate inflammatory responses. We previously reported that lipopolysaccharide (LPS), a major biologically active agent of gram-negative bacteria, induces a proinflammatory response via the Toll-like receptor (TLR) 4 in hepatic stellate cells (HSCs). Here we investigated the mechanism of proinflammatory action by PGN and LTA in activated human HSCs. Following treatment with either TNF-alpha or IL-1beta, expression of TLR2 and CD14 was determined by real-time PCR and Western blotting. NF-kappaB activation was assessed by NF-kappaB-driven luciferase assay and electrophoretic mobility shift assay. Interleukin-8 (IL-8) from culture supernatant was measured by ELISA. Activated human HSCs express TLR2 and CD14, which are receptors for PGN and LTA signaling. TNF-alpha and IL-1beta significantly upregulated the expression of TLR2 mRNA and protein in HSCs. PGN and LTA induced NF-kappaB activation and stimulated production of IL-8 in HSCs. Pretreatment with TNF-alpha or IL-1beta augmented NF-kappaB activation and IL-8 production in response to PGN or LTA. Both PGN- and LTA-induced NF-kappaB activation and IL-8 secretion were completely inhibited by anti-TLR2 blocking antibody (T2.5). These findings suggest that TNF-alpha or IL-1beta primed HSCs enhance the production of IL-8 in response to PGN and LTA through augmentation of the TLR2 system.
Paik
Yong-Han
YH
Department of Internal Medicine, Institute of Gastroenterology, Yonsei University College of Medicine, Seoul, South Korea.
Lee
Kwan Sik
KS
Lee
Hyun Jin
HJ
Yang
Kyung Min
KM
Lee
Se Jun
SJ
Lee
Dong Ki
DK
Han
Kwang-Hyub
KH
Chon
Chae Yoon
CY
Lee
Sang In
SI
Moon
Young Myoung
YM
Brenner
David A
DA
D000256:Adenoviridae / Q000235:genetics; D015415:Biomarkers / Q000378:metabolism; D018929:Cell Culture Techniques; D002461:Cell Line, Transformed; D016207:Cytokines / Q000276:immunology*; D005355:Fibrosis / Q000139:chemically induced / Q000473:pathology; D017930:Genes, Reporter; D022781:Hepatocytes / Q000166:cytology / Q000502:physiology*; D006801:Humans; D007249:Inflammation / Q000139:chemically induced / Q000473:pathology; D007375:Interleukin-1 / Q000276:immunology; D016209:Interleukin-8 / Q000096:biosynthesis; D018950:Lipopolysaccharide Receptors / Q000276:immunology; D008070:Lipopolysaccharides / Q000276:immunology*; D008099:Liver / Q000166:cytology*; D008156:Luciferases / Q000276:immunology; D016328:NF-kappa B / Q000276:immunology; D010457:Peptidoglycan / Q000276:immunology*; D013682:Teichoic Acids / Q000276:immunology*; D051195:Toll-Like Receptor 2 / Q000276:immunology; D014409:Tumor Necrosis Factor-alpha / Q000276:immunology; D015854:Up-Regulation / Q000276:immunology
D015415:Biomarkers; D016207:Cytokines; D007375:Interleukin-1; D016209:Interleukin-8; D018950:Lipopolysaccharide Receptors; D008070:Lipopolysaccharides; D016328:NF-kappa B; D010457:Peptidoglycan; D013682:Teichoic Acids; D051195:Toll-Like Receptor 2; D014409:Tumor Necrosis Factor-alpha; C009900:lipoteichoic acid; D008156:Luciferases