Extracellular heat shock protein 70 inhibits tumour necrosis factor-alpha induced proinflammatory mediator production in fibroblast-like synoviocytes.
BACKGROUND
It was recently suggested that heat shock protein (HSP)70, an intracellular protein, is a potential mediator of inflammatory disease when it is released into the extracellular compartment. Although elevated HSP70 levels have been identified in rheumatoid arthritis (RA) synovial tissues and RA synovial fluid compared with patients with osteoarthritis and healthy individuals, it remains unclear what role extracellular HSP70 plays in the pathogenesis of RA. This study was conducted to investigate the effects of extracellular HSP70 on the production of RA-associated cytokines in fibroblast-like synoviocytes from patients with RA and to elucidate the mechanisms involved.


METHODS
IL-6, IL-8 and monocyte chemoattractant protein (MCP)-1 levels in culture supernatants were measured using enzyme-linked immunosorbent assays. Activation of mitogen-activated protein kinases (MAPKs), such as extracellular signal-regulated protein kinases (ERKs), c-Jun amino-terminal kinase (JNK) and p38 MAPK, was detected using Western blotting. Nuclear translocation of nuclear factor-kappaB (NF-kappaB) and degradation of the inhibitory protein IkappaBalpha were examined using immunohistochemistry and Western blotting.


RESULTS
Human HSP70 downregulated IL-6, IL-8 and MCP-1 production in RA fibroblast-like synoviocytes induced by tumour necrosis factor (TNF)-alpha in a concentration dependent manner. HSP70 inhibited the activation of ERK, JNK and p38 MAPK in fibroblast-like synoviocytes stimulated by TNF-alpha. Furthermore, HSP70 also significantly inhibited nuclear translocation of nuclear factor-kappaB and degradation of IkappaBalpha induced by TNF-alpha.


CONCLUSIONS
Extracellular HSP70 has an anti-inflammatory effect on RA by downregulating production of IL-6, IL-8 and MCP-1 in fibroblast-like synoviocytes, which is mediated through inhibited activation of the MAPKs and NF-kappaB signal pathways.
Luo
Xinjing
X
Department of Pathophysiology, Xiangya School of Medicine, Central South University, Xiangya Road, Changsha, Hunan 410008, China. luoxjing@yahoo.com.cn
Zuo
Xiaoxia
X
Zhou
Yaou
Y
Zhang
Bing
B
Shi
Yongzhong
Y
Liu
Meidong
M
Wang
Kangkai
K
McMillian
D Randy
DR
Xiao
Xianzhong
X
D001172:Arthritis, Rheumatoid / Q000276:immunology / Q000378:metabolism*; D015153:Blotting, Western; D002478:Cells, Cultured; D016207:Cytokines / Q000096:biosynthesis*; D004797:Enzyme-Linked Immunosorbent Assay; D045604:Extracellular Fluid / Q000737:chemistry / Q000378:metabolism; D005347:Fibroblasts / Q000378:metabolism*; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism*; D006801:Humans; D007150:Immunohistochemistry; D007249:Inflammation / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology; D013583:Synovial Membrane / Q000166:cytology / Q000378:metabolism*; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism*
D016207:Cytokines; D018840:HSP70 Heat-Shock Proteins; D014409:Tumor Necrosis Factor-alpha; D020928:Mitogen-Activated Protein Kinases