IFN-beta1b induces transient and variable gene expression in relapsing-remitting multiple sclerosis patients independent of neutralizing antibodies or changes in IFN receptor RNA expression.

Multiple sclerosis (MS) is an inflammatory disease of the central nervous system (CNS). Interferon-beta (IFN-beta) therapy for MS is hypothesized to cause short-term and long-term changes in gene expression that shift the inflammation from Th1 to Th2. In vivo gene induction to define kinetics of response to IFN-beta therapy in a large cohort of MS patients is described. Differential gene expression in peripheral blood mononuclear cells (PBMCs) obtained from relapsing-remitting MS patients (RRMS) was assessed using high content microarrays. Rapid onset of gene expression appeared within 4 h of subcutaneous IFN-beta administration, returning to baseline levels at 42 h in clinically stable RRMS. IFN-beta therapy in vivo rapidly but transiently induced strong upregulation of genes mediating immune modulation, IFN signaling, and antiviral responses. RT-PCR showed significant patient-to-patient variation in the magnitude of expression of multiple genes, especially for IFN-beta-inducible genes, such as MxA, IRF7, and CCL8, a Th1 product. Variation among patients in IFN-beta-induced RNA transcription was not explained by neutralizing antibodies or IFN receptor expression. Surprisingly, genes regulated in vivo by IFN-beta therapy do not support a simple Th1 to Th2 shift. A complex interplay between both proinflammatory and anti-inflammatory immune regulatory genes is likely to act in concert in the treatment of RRMS.