Global gene expression analysis of CD14+ monocytes and CD4+ effector memory T cells before and during fingolimod treatment

Treatment of multiple sclerosis (MS) patients with sphingosine-1-phosphate receptor agonist fingolimod (FTY) increases for unknown reasons the risk for symptomatic reactivation of alpha-herpesviruses, in particular of varicella zoster virus (VZV), but not of other co-infecting herpesviruses (e.g. human cytomegalovirus (HCMV). To elucidate this specific signal in adverse events, we systematically assessed changes in global and herpesvirus-specific immune responses and signatures in MS patients before and during FTY therapy. In addition to phenotypical and functional changes, we thought to identify FTY-induced modifications on the gene expression level, which might add to perturbations in antiviral immune responses. Therefore, gene expression of CD4+ EM T cells and CD14+ monocytes were analyzed. These two subsets, CD4+ EM T cells and CD14+ monocytes, were isolated from PBMC of six female RRMS patients collected before (V0) and after 9 months of FTY therapy (V9) for RNA sequencing (RNASeq). Comparison of gene expression profiles of monocytes between V0 and V9 revealed 226 down- and 38 upregulated genes. Gene ontology categories and pathway analysis detected most significant alterations for genes involved in immune response, defense against viruses as well as type-1 interferon signaling pathways. Next, we compared gene expression profiles of CD4+ EM T cells collected at V0 and V9 of FTY therapy and found 314 down- and 219 upregulated genes. The most significantly modified pathways were involved in immune responses, including NK cell chemotaxis, cytotoxicity and antiviral responses. In summary, gene expression analysis of monocytes suggests that HCMV might be more susceptible to reactivation during FTY treatment because of FTY-induced modifications of immune control pathways important for HCMV latency. However, increased cytolytic potential of CD4+ EM T cells and expansion of HCMV-specific CD4+ T cells might counteract synthesis or release of viral particles and prevent viremia. Overall design: RNA of CD14+ monocytes and effector memory T cells collected from PBMC of six female RRMS patients before and nine month during Fingolimod therapy was isolated and sequenced.