sphingosine-1-phosphate and Graves-Ophthalmopathy

Graves' orbitopathy (GO) is an autoimmune orbital disorder associated with Graves' disease caused by thyrotropin receptor autoantibodies. Orbital fibroblasts (OFs) and CD40 play a key role in disease pathogenesis. The bioactive lipid sphingosine-1-phosphate (S1P) has been implicated in promoting adipogenesis, fibrosis, and inflammation in OFs. We investigated the role of CD40 signaling in inducing S1P activity in orbital inflammation.. OFs and T cells were derived from GO patients and healthy control (Ctl) persons. S1P abundance in orbital tissues was evaluated by immunofluorescence. OFs were stimulated with CD40 ligand and S1P levels were determined by ELISA. Further, activities of acid sphingomyelinase (ASM), acid ceramidase, and sphingosine kinase were measured by ultraperformance liquid chromatography. Sphingosine and ceramide contents were analyzed by mass spectrometry. Finally, the role for S1P in T-cell attraction was investigated by T-cell migration assays.. GO orbital tissue showed elevated amounts of S1P as compared to control samples. Stimulation of CD40 induced S1P expression in GO-derived OFs, while Ctl-OFs remained unaffected. A significant increase of ASM and sphingosine kinase activities, as well as lipid formation, was observed in GO-derived OFs. Migration assay of T cells in the presence of SphK inhibitor revealed that S1P released by GO-OFs attracted T cells for migration.. The results demonstrated that CD40 ligand stimulates GO fibroblast to produce S1P, which is a driving force for T-cell migration. The results support the use of S1P receptor signaling modulators in GO management.

Topics: Acid Ceramidase; CD40 Antigens; CD40 Ligand; Cell Movement; Enzyme-Linked Immunosorbent Assay; Fibroblasts; Fluorescent Antibody Technique, Indirect; Graves Ophthalmopathy; Humans; Inflammation; Lysophospholipids; Mass Spectrometry; Orbit; Phosphotransferases (Alcohol Group Acceptor); Signal Transduction; Sphingolipids; Sphingomyelin Phosphodiesterase; Sphingosine; T-Lymphocytes

Graves' orbitopathy (GO) is initiated by excessive amount of various inflammatory mediators produced by orbital fibroblasts. This study aimed to assess the crucial role of sphingosine-1-phosphate (S1P) in the inflammatory process of GO.. Orbital adipose/connective tissue samples were obtained from 10 GO patients and 10 normal control individuals during surgery. Primary orbital fibroblast culture was done. After the expression of S1P receptors and sphingosine kinase (SphK) was assessed with the treatment of interleukin (IL)-1β, we evaluated the expression of pro-inflammatory factors [intercellular adhesion molecule-1 (ICAM-1), cyclooxygenase-2 (COX-2) and IL-6] after treating S1P. S1P receptor antagonists and SphK 1 inhibitor were pretreated and the expression of the pro-inflammatory factors was assessed.. IL-1β exacerbated the inflammatory process by enhancing the expression of S1P receptors and SphK in GO orbital fibroblasts. IL-1β also induced the expressions of ICAM-1, COX-2, and IL-6 in GO orbital fibroblasts, and these expressions were effectively inhibited by S1P receptor antagonists and SphK1 inhibitor.. S1P has an important role in the pathological inflammatory process of GO, which is mediated through the SphK1-S1P- S1P receptor pathway. SphK1 inhibitors and S1P receptors or antagonists could be potential approaches for controlling the inflammatory process of GO.

Topics: Adult; Aged; Connective Tissue; Cyclooxygenase 2; Female; Fibroblasts; Graves Ophthalmopathy; Humans; Inflammation; Interleukin-1beta; Interleukin-6; Lysophospholipids; Middle Aged; Phosphotransferases (Alcohol Group Acceptor); Receptors, Lysosphingolipid; Sphingosine

To investigate the effect of sphingosine-1-phosphate (S1P) on fibrosis in orbital fibroblasts in Graves' orbitopathy (GO).. Orbital fibroblasts were cultured from orbital adipose/connective tissues of patients with GO and healthy control subjects. Effects of treatment with TGF-β and cigarette smoke extract (CSE) on S1P receptor (S1PR) messenger RNA (mRNA) and S1P expression were evaluated by real-time polymerase chain reaction and Western blotting. To evaluate the role of S1P in fibrosis, cells were pretreated with W146 (S1PR1 antagonist); JTE013 (S1PR2 antagonist); FTY720 (S1PR1 modulator); or 5C (sphingosine kinase-1 blocker) for 1 hour before stimulation with TGF-β, CSE, or IL-1β. Expression of fibrosis-related proteins (collagen Iα, fibronectin, and α-smooth muscle actin [SMA]) and tissue remodeling-related proteins (matrix metalloproteinases [MMPs] and tissue inhibitor of metalloproteinase [TIMP]-1) was then evaluated by Western blotting.. Expression levels of S1PR mRNA and S1P in GO orbital fibroblasts increased upon TGF-β and CSE treatment. Treatment with S1PR blockers and 5C inhibited TGF-β and CSE-induced expression of collagen Iα, fibronectin, and α-SMA, as well as IL-1β-induced expression of MMP-1, MMP-2, MMP-9, and TIMP-1. Exogenous S1P treatment without profibrotic stimulants upregulated collagen Iα, fibronectin, α-SMA, MMP-1, MMP-2, MMP-9, and TIMP-1 expression in a dose-dependent manner.. Blocking of S1PR activity and inhibition of S1P synthesis led to decreased expression of fibrosis and tissue remodeling-related proteins in primary cultures of orbital fibroblasts derived from patients with GO. Thus, modulation of S1P activity might have therapeutic potential in the suppression of fibrosis in GO.

Topics: Adult; Blotting, Western; Cells, Cultured; Female; Fibroblasts; Fibrosis; Gene Expression Regulation; Graves Ophthalmopathy; Humans; Lysophospholipids; Male; Middle Aged; Real-Time Polymerase Chain Reaction; RNA; Signal Transduction; Sphingosine

To investigate the action of sphingosine-1-phosphate (S1P) in adipocyte differentiation of orbital fibroblasts and determine its putative role in the pathogenesis of Graves' orbitopathy (GO).. Primary preadipocyte orbital fibroblast cultures were stimulated for adipogenesis. Real-time PCR was performed to evaluate the expression of S1P receptor mRNA. To evaluate the effect of S1P and S1P receptor blockers (W146 and FTY720) on adipocyte differentiation, cultures were exposed to each receptor blocker for the first 4 days of the differentiation period. Differentiated cells were stained with Oil Red O, and the production of peroxisome proliferator activator gamma (PPARγ) and CCAAT-enhancer-binding proteins (C/EBP) α and β were determined by Western blot analysis.. Sphingosine-1-phosphate receptor 1, 2, and 3 mRNA expression levels were significantly higher in GO tissue samples than non-GO. Sphingosine-1-phosphate receptor 1 through 5 mRNA expression was significantly increased during the 10 days of adipogenesis. Sphingosine-1-phosphate treatment increased the size and number of adipocytes, and increased the expression of adipogenic transcriptional regulators. Treatment with S1P1 receptor inhibitor (W146) for 4 days after induction of adipogenesis attenuated adipocyte differentiation. Sphingosine-1-phosphate receptor blocker also decreased reactive oxygen species (ROS) production in GO orbital fibroblasts and H2O2-stimulated HO-1 production in GO orbital fibroblasts. S1P1 receptor inhibitor reduced the number of adipocytes and suppressed the accumulation of lipid droplets induced by 10 μM H2O2 or 2% cigarette smoke extract (CSE) treatment.. Sphingosine-1-phosphate could play a role in orbital adipocyte differentiation of GO. Modulation of S1P actions may provide a therapeutic target for the treatment of GO.

Topics: Adipogenesis; Adult; Blotting, Western; CCAAT-Enhancer-Binding Protein-beta; CCAAT-Enhancer-Binding Proteins; Cell Differentiation; Cells, Cultured; Female; Fibroblasts; Fingolimod Hydrochloride; Graves Ophthalmopathy; Humans; Immunosuppressive Agents; Lysophospholipids; Male; Middle Aged; Orbit; PPAR gamma; Reactive Oxygen Species; Real-Time Polymerase Chain Reaction; Receptors, Lysosphingolipid; RNA, Messenger; Sphingosine