sphingosine-kinase 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