S100A8/S100A9在骨关节炎疾病中的研究进展

S100A8(钙粒蛋白A)和S100A9(钙粒蛋白B)是钙结合蛋白S100家族的重要成员,作为重要的促炎介质,参与多种慢性炎症性疾病的病理进程,在炎症反应和机体固有免疫过程中发挥重要作用.最近有研究表明S100A8和S100A9蛋白在骨关节炎炎症的病理发展中发挥关键作用,针对S100A8和S100A9的干预有望成为骨关节炎临床治疗的潜在靶点.     

S100A8, S100A9 and the S100A8/A9 heterodimer complex specifically bind to human endothelial cells: identification and characterization of ligands for the myeloid-related proteins S100A9 and S100A8/A9 on human dermal microvascular endothelial cell line-1 cells

The natural ligands of the S100 EF hand proteins S100A8 and A9 [myeloid-related proteins 8 and 14] have long been searched for in order to further the understanding of the role of the S100A8/A9-expressing monocyte subpopulation in progressing inflammatory processes. We demonstrate that S100A8, S100A9 and the S100A8/A9 heterodimeric complex bind to human dermal microvascular endothelial cell line (HMEC)-1 with an increasing binding capacity progressing from S100A8 < or = S100A9 < or = S100A8/A9. Similar results were obtained in the apolipoprotein E knockout mouse model, where preferably recombinant S100A9 but no S100A8 bound to the endothelium of the aorta ascendens. The binding of the S100A8/A9 heterodimer complex to activated HMEC-1 is specific as demonstrated by a dose-responding and satiable binding curve and the competition of FITC-labeled versus unlabeled protein. The protein character of the binding site was proven by treatment with trypsin. S100A8/A9 binding to HMEC-1 is inducible by lipopolysaccharide and tumor necrosis factor-alpha, and in the presence of calcium. A 163-kDa protein was isolated from a cell lysate of activated HMEC-1 cells using an affinity-chromatography protocol. The endothelial cell-associated ligand proteins isolated by the use of the S100A9 monomer and the S100A8/A9 dimer were subjected to mass spectrometry for protein identification. Clearly, alpha(2)-macroglobulin was identified as a binding partner for the S100A9 monomer, whereas no protein could be identified from the database for the ligand of the S100A8/A9 dimer.     

S100A9 promotes human lung fibroblast cells activation through receptor for advanced glycation end‐product‐mediated extracellular‐regulated kinase 1/2, mitogen‐activated protein‐kinase and nuclear factor‐κB‐dependent pathways

S100A9 belongs to the S100 family of calcium‐binding proteins and plays a key role in many inflammatory conditions. Recent studies have found that S100A9 was elevated significantly in the bronchoalveolar lavage fluid of idiopathic pulmonary fibrosis patients, and might be a biomarker for fibrotic interstitial lung diseases. However, the exact function of S100A9 in pulmonary fibrosis needs further studies. We performed this study to investigate the effect of S100A9 on human embryo lung fibroblast (HLF) proliferation and production of cytokines and collagen, providing new insights into the possible mechanism. S100A9 promoted proliferation of fibroblasts and up‐regulated expression of both proinflammatory cytokines interleukin (IL)‐6, IL‐8, IL‐1β and collagen type III. S100A9 also induced HLF cells to produce α‐smooth muscle actin (α‐SMA) and receptor for advanced glycation end‐product (RAGE). In addition, S100A9 caused a significant increase in extracellular‐regulated kinase (ERK)1/2 mitogen‐activated protein kinase (MAPK) phosphorylation, while the status of p38 and c‐Jun N‐terminal kinase (JNK) phosphorylation remained unchanged. Treatment of cells with S100A9 also enhanced nuclear factor kappa B (NF‐κB) activation. RAGE blocking antibody pretreatment inhibited the S100A9‐induced cell proliferation, cytokine production and pathway phosphorylation. S100A9‐mediated cell activation was suppressed significantly by ERK1/2 MAPK inhibitor and NF‐κB inhibitor. In conclusion, S100A9 promoted HLF cell growth and induced cells to secret proinflammatory cytokines and collagen through RAGE signalling and activation of ERK1/2 MAPK and NF‐κB pathways.     

Expression of S100 proteins in normal human tissues and common cancers using tissue microarrays: S100A6, S100A8, S100A9 and S100A11 are all overexpressed in common cancers

AIMS: To survey the expression of members of the S100 family of calcium-binding proteins in normal human tissues and common cancers using tissue microarrays. S100A6, S100A8, S100A9 and S100A11 have all been suggested to have potential roles in carcinogenesis and tumour progression but their expression has not been described in a wide range of human tissues and tumours. METHODS AND RESULTS: A custom-made tissue array, containing 291 tissue cores representing 28 tissue types and 21 tumour types, was used to produce sections that were immunostained for S100A2, S100A6, S100A8, S100A9, S100A11, calbindin 1, calbindin 2, S100B and parvalbumin. S100A6, S100A8 and S100A9 were expressed in 32%, 12% and 28% of breast cancers, respectively. There was a translocation of S100A11 expression from exclusively nuclear in normal tissues to cytoplasmic and nuclear in all common cancers. CONCLUSIONS: S100A6, S100A8, S100A9 and S100A11 are all expressed in common cancers, especially breast cancer. In addition, S100A11 undergoes a nucleocytoplasmic translocation which may have a direct influence on the proliferation of the cancer cells.     

S100A9-induced release of interleukin (IL)-6 and IL-8 through toll-like receptor 4 (TLR4) in human periodontal ligament cells

S100A8, S100A9, and calprotectin (the S100A8/S100A9 complex) are calcium-binding proteins that promote extracellular pro-inflammatory functions and may play an important role in periodontal disease. Both toll-like receptor 4 (TLR4) and the receptor for advanced glycation end-products (RAGE) are thought to be important receptors for S100A8, S100A9, and calprotectin, but the specific pathways in periodontal ligament (PDL) cells are not yet clear. Our study was designed to identify the specific receptors for S100A9 in human PDL cells. Additionally, we investigated the specific pathways that activate the secretion of pro-inflammatory cytokines interleukins (IL)-6 and IL-8 in PDL cells. The role of nuclear factor (NF)-κB, mitogen-activated protein kinase (MAPK) and reactive oxygen species (ROS) in S100A9-induced pro-inflammatory cytokines were investigated through western blot analysis, dichlorodihydrofluorescein diacetate (H₂DCFDA) probe and the application of specific pathway inhibitors. Our results suggest that the S100A9-induced release of IL-6 and IL-8 from human PDL cells is dependent on TLR4, but not RAGE. We provide evidence that S100A9 promotes the secretion of IL-6 and IL-8 through different pathways. Specifically, S100A9 up-regulates the secretion of IL-6 from human PDL cells through NF-κB and p38 pathways and up-regulates the release of IL-8 from human PDL cells through the NF-κB, extracellular-regulated kinase (ERK) 1/2, c-Jun amino-terminal kinase (JNK) 1/2, and p38 signaling pathways. In addition, the release of both cytokines depends on ROS production. The release of both cytokines depends on ROS production. These results suggest that S100A9 promotes pro-inflammatory responses in PDL cells through the TLR4-mediated NF-κB and MAPK signaling pathways.     

Serum amyloid A induces interleukin‐6 in dermal fibroblasts via Toll‐like receptor 2, interleukin‐1 receptor‐associated kinase 4 and nuclear factor‐κB

Systemic sclerosis is an autoimmune idiopathic connective tissue disease, characterized by vasculopathy, inflammation and fibrosis. There appears to be a link between inflammation and fibrosis, although the exact nature of the relationship is unknown. Serum amyloid A (SAA) is an acute‐phase protein that is elevated up to 1000‐fold in times of infection or inflammation. This acute‐phase reactant, as well as being a marker of inflammation, may initiate signals in a cytokine‐like manner, possibly through toll‐like receptors (TLRs) promoting inflammation. This study addressed the role of SAA in initiating interleukin‐6 (IL‐6) production in dermal fibroblasts and the role of TLR2 in this system. We show that SAA induces IL‐6 secretion in healthy dermal fibroblasts and that blockade of TLR2 with a neutralizing antibody to TLR2 or specific small interfering RNA attenuated the SAA‐induced IL‐6 secretion and that this was also mediated through the TLR adaptor protein IL‐1 receptor‐associated kinase 4. The effect is nuclear factor‐κB‐mediated because blockade of nuclear factor‐κB reduced the induction. We also demonstrate that dermal fibroblasts express TLR2; this is functional and over‐expressed in the fibroblasts of patients with systemic sclerosis. Taken together these data suggest that SAA is a danger signal that initiates IL‐6 signalling in systemic sclerosis via enhanced TLR2 signalling.