Fingolimod Treatment Reduces Circulating CD4+ Regulatory T Cells and Th17 Cells in Blood of Patients with Multiple Sclerosis (P02.112)

Abstract

Objective: To determine the relative percentages of Th17 and Treg cells in CD3+ T cells isolated from the blood of healthy control subjects, untreated MS patients, and IFNb- or fingolimod-treated MS patients. Background Fingolimod has recently been approved as the first oral treatment for relapsing Multiple Sclerosis (MS). Fingolimod treatment reduces the blood CD4 T cell count by approximately 60-70%. As a consequence, the quantification of the small functional T helper (Th) and regulatory T cell (Treg) subsets in blood of fingolimod-treated patients requires prior enrichment of T cells. Design/Methods: The percentage of FOXP3+ Treg cells and of RORC2+ TH17 cells was determined by quantitative RT-PCR in CD3+ T cells purified by MACS. The percentages of CD4+ and CD8+ naive, central memory and effector memory T cells were determined by flow cytometry, using the markers CCR7 and CD45RA. Results: Compared to healthy controls, the percentage of both Tregs and Th17 cells was increased in MS patients, both untreated and those treated with IFNb. In fingolimod-treated MS patients, the percentages of both Treg and TH17 cells were reduced by approximately 70% compared to control groups, and this correlated with a reduction of the total CD4+ T cell count. The remaining blood CD4+ T cells were enriched in CCR7-CD45RA+/- effector memory T cells. Conclusions: The increase of Tregs and TH17 cells in blood of drug-untreated and IFNb-treated MS patients suggests activation of pro- and anti-inflammatory pathways. In fingolimod-treated MS patients, the reduction of Tregs and TH17 cells corresponds to reduction of CD4+CCR7+ T cells, suggesting that mechanisms leading to reduced counts involve the lymph node retention receptor CCR7, rather than specific functional helper/regulatory phenotypes. Supported by: We thank L Kappos and M Mehling for providing blood samples. Disclosure: Dr. Brinkmann has received personal compensation for activities with Novartis as an employee. Dr. Brinkmann has received research support from Novartis. Dr. Raulf has received personal compensation for activities with Novartis as an employee.Dr. Raulf has received research support from Novartis. Dr. Vedrine has received personal compensation for activities with Novartis. Dr. Vedrine has received research support from Novartis. Dr. Allard has received personal compensation for activities with Novartis as an employee. Dr. Allard has received research support from Novartis.