RANKL/RANK/OPG Axis Is Deregulated in the Cerebrospinal Fluid of Multiple Sclerosis Patients at Clinical Onset.

OBJECTIVES: Our study focused on the RANKL (receptor activator of nuclear factor-κB ligand)/RANK/OPG (osteoprotegerin) axis and selected proinflammatory/immunoregulatory upstream mediators in the peripheral blood (PBL) and cerebrospinal fluid (CSF) of multiple sclerosis (MS) patients. METHODS: PBL and CSF were collected from healthy controls (n = 35) and MS patients at the clinical onset of the disease (n = 33). In addition, PBL samples were obtained from relapse-remitting (RR)-MS patients (n = 30). Patients were assessed by means of the expanded disability status scale (EDSS) and routine laboratory parameters. Soluble (s)RANKL and OPG were measured in the CSF and plasma; gene expression was detected for RANKL, RANK, OPG, and selected cytokines/chemokines (interleukin [IL]-4, IL-10, IL-17, CCL2, and CXCL12) in PBL mononuclear cells. RESULTS: The OPG level in the CSF was lower in MS patients at clinical onset than in controls. Moreover, the sRANKL/OPG ratio was higher in the CSF of MS patients at clinical onset and in the plasma of RR-MS patients than in controls. Gene expression of RANKL/RANK/OPG in PBL mononuclear cells was higher only in RR-MS patients. IL-4, CCL2, and CXCL12 were positively correlated and IL-10 was negatively correlated with RANKL/RANK expression. OPG was negatively correlated with EDSS and alkaline phosphatase level. CONCLUSION: Our study revealed that changes of RANKL/RANK/OPG axis are associated with MS, particularly the decreased OPG level in the CSF at disease onset. Therefore, these factors may serve as disease biomarkers and molecular targets of novel therapeutic approaches.

Decreased level of sRAGE in the cerebrospinal fluid of multiple sclerosis patients at clinical onset.

OBJECTIVES: Receptor for advanced glycation end products (RAGE) ligands/RAGE interactions have been proposed to have a pathogenic role in neuroinflammatory disorders. Our study aimed to assess changes in high-mobility group box (HMGB)1 and its receptor RAGE in peripheral blood (PBL) and cerebrospinal fluid (CSF) of patients with multiple sclerosis (MS) at the disease onset compared with control subjects. METHODS: PBL and CSF were collected from control subjects (n = 30) and MS patients (n = 27) at clinical onset. Soluble RAGE (sRAGE), HMGB1, S100 calcium-binding protein A12 (S100A12), interleukin (IL)-1ß and tumor necrosis factor (TNF)-α were measured in the CSF and plasma by enzyme-linked immunosorbent assay. Gene expression in PBL mononuclear cells (PBMCs) was detected by quantitative PCR for RAGE, HMGB1, S100A12 and several proinflammatory/immunoregulatory cytokines. RESULTS: We found a significantly lower expression of IL-10 (p = 0.031) in the PBMCs of MS patients. The level of sRAGE in the CSF of MS patients was lower (p = 0.021), with the ability to discriminate between MS patients and control subjects. Moreover, PBMC gene expression for HMGB1 and S100A12 positively correlated with IL-6. CONCLUSIONS: Our study confirmed that the cytokine network is disturbed in PBL and CSF at MS clinical onset. The deregulated HMGB1/RAGE axis found in our study may present an early pathogenic event in MS, proposing sRAGE as a possible novel therapeutic strategy for MS treatment.