Reconstitution of the peripheral immune repertoire following withdrawal of fingolimod.

BACKGROUND: Following fingolimod cessation, immune reconstitution or lack thereof may have consequences for disease rebound or safety of commencing alternative therapies. OBJECTIVE: To examine the degree and profile of peripheral blood lymphocyte reconstitution following fingolimod withdrawal. METHODS: Total lymphocyte counts (TLC) and CD4+/CD8+ T-cell counts were measured in 18 multiple sclerosis (MS) patients pre-treatment, on fingolimod, and up to 8-9 months post-cessation. T-cell subsets were analyzed using flow cytometry. RESULTS: At 2-week post-fingolimod cessation, TLC reconstitution was variable and not correlated with age, treatment duration, pre-, or on-treatment TLC. Despite normalization of TLC and CD4+:CD8+ ratios over months, naive subsets remained lower and effector memory subsets higher in frequency compared with pre-treatment. Drug-induced increases in ratios of regulatory to pathogenic Th17-containing central memory populations appeared to rapidly return to baseline. CONCLUSION: Early peripheral lymphocyte reconstitution after fingolimod withdrawal remains partial and heterogeneous. Relative frequencies of circulating naive and memory T-cell subsets may not recover for many months, even when clinical laboratory tests have normalized. Analyzing specific components of the peripheral immune repertoire helps define the overall immune status of patients. To be determined is whether assessment of such immune measures will have implications for the timing and safety of commencing alternative therapies.

Naive CD4 T-cell activation identifies MS patients having rapid transition to progressive MS.

OBJECTIVE: Our objective was to determine whether altered naive CD4 T-cell biology contributes to development of disease progression in secondary progressive multiple sclerosis (SPMS). METHODS: We compared the naive CD4 T-cell gene expression profiles of 19 patients with SPMS and 14 healthy controls (HCs) using a whole-genome microarray approach. We analyzed surface protein expression of critical genes by flow cytometry after T-cell receptor (TCR) stimulation of naive CD4 T cells isolated from HCs and patients with SPMS. RESULTS: Hierarchical clustering segregated patients with SPMS into 2 subgroups: SP-1, which had a short duration of relapsing-remitting multiple sclerosis (MS), and SP-2, which had a long duration of relapsing-remitting MS. SP-1 patients upregulated numerous immune genes, including genes within TCR and toll-like receptor (TLR) signaling pathways. SP-2 patients showed immune gene downregulation in comparison with HCs. We identified an SP-1-specific transcriptional signature of 3 genes (TLR4, TLR2, and chemokine receptor 1), and these genes had higher surface protein expression in SP-1 than in SP-2. After TCR stimulation for 48 hours, only SP-1 showed a progressive linear increase in TLR2 and TLR4 protein expression. CONCLUSIONS: Differences in naive CD4 T-cell biology, notably of TCR and TLR signaling pathways, identified patients with MS with more rapid conversion to secondary progression, a critical determinant of long-term disability in MS.

Reduced thymic output and peripheral naïve CD4 T-cell alterations in primary progressive multiple sclerosis (PPMS).

We compared naïve CD4 and CD8 T-cell homeostasis in primary progressive multiple sclerosis (PPMS), relapsing-remitting MS (RRMS) and controls. Quantitation of signal joint T-cell receptor (TCR) excision circles (sjTRECs) and quantitative estimates of daily thymic export confirm our previous report of reduced thymic output in RRMS and demonstrate reduced thymic output in PPMS. In PPMS, the decreasing % CD31+ naïve CD4 T-cells but constant sjTRECs and constant naïve CD4 T-cell numbers with age, together with increased Bcl-2 expression suggest increased TCR signaling with increased naïve T-cell survival. We conclude PPMS patients have peripheral immune alterations related to reduced thymic output.