Chemokines CXCL10 and CCL2: differential involvement in intrathecal inflammation in multiple sclerosis

Studies of chemokines in cerebrospinal fluid (CSF) of patients with active multiple sclerosis (MS) have indicated that specific chemokines may have important roles in disease pathogenesis. We previously reported that CSF concentrations of CXCL10 (previously known as IP-10) were elevated in MS patients in relapse, whilst levels of CCL2 (MCP-1) were reduced. Here, we report a serial analysis of CSF CXCL10 and CCL2 concentrations in 22 patients with attacks of MS or acute optic neuritis (ON) treated with methylprednisolone, and 26 patients treated with placebo in two randomized controlled trials. Chemokine concentrations were measured by enzyme linked immunosorbent assay (ELISA) in CSF obtained at baseline and after 3 weeks, and were compared with other measures of intrathecal inflammation. At baseline CSF concentrations of CCL2 were significantly lower in the patient group than in controls. The levels of CXCL10 were higher in the patient group than in controls but two outliers in the control group also had high CSF concentrations of CXCL10. The CSF concentrations of CXCL10 did not change over time or after treatment. The CSF concentration of CXCL10 was positively correlated with the CSF leukocyte count, the CSF concentration of neopterin, matrix metalloproteinase (MMP)-9, and intrathecal IgG and IgM synthesis. The concentration of CCL2 increased between baseline for 3 weeks in both groups, more distinctly so in patients treated with methylprednisolone. CCL2 correlated negatively with MMP-9 and IgG synthesis levels. CXCL10 may be involved in the maintenance of intrathecal inflammation whereas CCL2 correlates negatively with measures of inflammation, suggesting differential involvement of CXCL10 and CCL2 in CNS inflammation.