The cachectic mediator proteolysis inducing factor activates NF-kappaB and STAT3 in human Kupffer cells and monocytes.
A novel proteoglycan, proteolysis inducing factor (PIF), is capable of inducing muscle proteolysis during the process of cancer cachexia, and of inducing an acute phase response in human hepatocytes. We investigated whether PIF is able to activate pro-inflammatory pathways in human Kupffer cells, the resident macrophages of the liver, and in monocytes, resulting in the production of pro-inflammatory cytokines. Normal liver tissue was obtained from patients undergoing partial hepatectomy and Kupffer cells were isolated. Monocytes were isolated from peripheral blood. Following exposure to native PIF, pro-inflammatory cytokine production from Kupffer cells and monocytes was measured and the NF-kappaB and STAT3 transcriptional pathways were investigated using electrophoretic mobility shift assays. We demonstrate that PIF is able to activate the transcription factor NF-kappaB and NF-kappaB-inducible genes in human Kupffer cells, and in monocytes, resulting in the production of pro-inflammatory cytokines such as TNF-alpha, IL-8 and IL-6. PIF enhances the expression of the cell surface molecules LFA-1 and CD14 on macrophages. PIF also activates the transcription factor STAT3 in Kupffer cells. The pro-inflammatory effects of PIF, mediated via NF-kappaB and STAT3, are important in macrophage behaviour and may contribute to the inflammatory pro-cachectic process in the liver.
Watchorn
Tammy M
TM
Tissue Injury and Repair Group, Cell Injury and Apoptosis Section, Centre for Inflammation Research, University of Edinburgh, Edinburgh, UK.
Dowidar
Nabil
N
Dejong
Cornelis H C
CH
Waddell
Ian D
ID
Garden
O James
OJ
Ross
James A
JA
D000210:Acute-Phase Reaction; D001798:Blood Proteins / Q000502:physiology*; D002100:Cachexia / Q000473:pathology*; D002462:Cell Membrane / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism; D016207:Cytokines / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D005434:Flow Cytometry; D006801:Humans; D007249:Inflammation; D015850:Interleukin-6 / Q000378:metabolism; D016209:Interleukin-8 / Q000378:metabolism; D007728:Kupffer Cells / Q000166:cytology*; D018950:Lipopolysaccharide Receptors / Q000096:biosynthesis; D008070:Lipopolysaccharides / Q000378:metabolism; D008099:Liver / Q000378:metabolism; D008264:Macrophages / Q000378:metabolism; D009000:Monocytes / Q000737:chemistry* / Q000166:cytology / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism*; D011509:Proteoglycans; D050796:STAT3 Transcription Factor / Q000378:metabolism*; D013997:Time Factors; D014158:Transcription, Genetic; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
D001798:Blood Proteins; D016207:Cytokines; D015850:Interleukin-6; D016209:Interleukin-8; D018950:Lipopolysaccharide Receptors; D008070:Lipopolysaccharides; D016328:NF-kappa B; D011509:Proteoglycans; D050796:STAT3 Transcription Factor; D014409:Tumor Necrosis Factor-alpha; C042057:proteolysis-inducing peptide