Sustained effects on immune cell subsets and autoreactivity in multiple sclerosis patients treated with oral cladribine.

Introduction: Cladribine tablet therapy is an efficacious treatment for multiple sclerosis (MS). Recently, we showed that one year after the initiation of cladribine treatment, T and B cell crosstalk was impaired, reducing potentially pathogenic effector functions along with a specific reduction of autoreactivity to RAS guanyl releasing protein 2 (RASGRP2). In the present study we conducted a longitudinal analysis of the effect of cladribine treatment in patients with RRMS, focusing on the extent to which the effects observed on T and B cell subsets and autoreactivity after one year of treatment are maintained, modulated, or amplified during the second year of treatment. Methods: In this case-control exploratory study, frequencies and absolute counts of peripheral T and B cell subsets and B cell cytokine production from untreated patients with relapsing-remitting MS (RRMS) and patients treated with cladribine for 52 (W52), 60 (W60), 72 (W72) and 96 (W96) weeks, were measured using flow cytometry. Autoreactivity was assessed using a FluoroSpot assay. Results: We found a substantial reduction in circulating memory B cells and proinflammatory B cell responses. Furthermore, we observed reduced T cell responses to autoantigens possibly presented by B cells (RASGRP2 and a-B crystallin (CRYAB)) at W52 and W96 and a further reduction in responses to the myelin antigens myelin basic protein (MBP) and myelin oligodendrocyte glycoprotein (MOG) after 96 weeks. Conclusion: We conclude that the effects of cladribine observed after year one are maintained and, for some effects, even increased two years after the initiation of a full course of treatment with cladribine tablets.

Cerebrospinal fluid soluble CD27 is associated with CD8+ T cells, B cells and biomarkers of B cell activity in relapsing-remitting multiple sclerosis.

Cerebrospinal fluid (CSF) soluble CD27 (sCD27) is a sensitive biomarker of intrathecal inflammation. Although generally considered a biomarker of T cell activation, CSF sCD27 has been shown to correlate with biomarkers of B cell activity in multiple sclerosis. We analyzed CSF from 40 patients with relapsing-remitting multiple sclerosis (RRMS) and nine symptomatic controls using flow cytometry and multiplex electrochemiluminescence immunoassays. CSF sCD27 levels were increased in RRMS and correlated with IgG index, soluble B cell maturation antigen, cell count, B cell frequency and CD8+ T cell frequency. We provide new data indicating that CSF sCD27 is associated with CD8+ T cells and B cells in RRMS.

Cladribine Effects on T and B Cells and T Cell Reactivity in Multiple Sclerosis.

OBJECTIVE: Cladribine tablet therapy is an efficacious treatment for multiple sclerosis (MS), however, its mechanism of action on T and B cell subsets remains unclear. The purpose of this study was to investigate the treatment effects of cladribine on the peripheral pool of T and B cells subsets and reactivity toward central nervous system (CNS) antigens. METHODS: In this cross-sectional exploratory study, frequencies and absolute counts of peripheral T and B cell subsets and B cell cytokine production from untreated patients with relapsing-remitting MS (RRMS) and patients treated with cladribine for 1 year were measured using flow cytometry. Autoreactivity was assessed using a FluoroSpot assay. RESULTS: We found that 1 year after initiation of cladribine treatment, a lower number of CD4+ T cells was persisting whereas CD19+ B cell counts were normalized compared to untreated patients with RRMS. Follicular helper T cells and their effecter subsets producing cytokines exerting distinct B cell helper activity were lower and, additionally, the peripheral B cell pool was skewed toward a naïve and anti-inflammatory phenotype. Finally, reactivity to the recently identified CNS-enriched autoantigen RAS guanyl-releasing protein 2 (RASGRP2), but not to myelin basic protein and myelin oligodendrocyte glycoprotein, was lower in cladribine-treated patients. INTERPRETATION: Together, these investigations on T and B cell subsets suggest that cladribine treatment impairs the B-T cell crosstalk and reduces their ability to mediate pathogenic effector functions. This may result in specific reduction of autoreactivity to RASGRP2 which is expressed in B cells and brain tissue. ANN NEUROL 2023;94:518-530.

Biomarkers of systemic inflammation, soluble IL-2Rα and the multiple sclerosis-associated IL2RA SNP rs2104286 in healthy subjects and multiple sclerosis patients.

Soluble interleukin-2 (IL-2) receptor α (sIL-2Rα) antagonizes IL-2 signaling and is involved in the pathogenesis of several immune-mediated diseases including multiple sclerosis (MS). The level of sIL-2Rα is affected by the MS-associated single nucleotide polymorphism (SNP) rs2104286. By use of ELISA and electrochemiluminescence, we investigated if 26 biomarkers of systemic inflammation were associated with sIL-2Rα and rs2104286 in cohorts of healthy subjects and MS patients in serum and heparin plasma. We found that sIL-2Rα significantly correlated with the level of tumor necrosis factor-α (TNFα) (r = 0.391, p = 0.002) in healthy subjects and the association was validated in a separate cohort. Additional, in healthy subjects we confirmed a previous report indicating that C-reactive protein (CRP) correlates with sIL-2Rα (r = 0.278, p = 0.034). None of the biomarkers of systemic inflammation were significantly associated with sIL-2Rα in MS patients. Furthermore, the MS-associated SNP rs2104286 was not significantly associated with any of the biomarkers of systemic inflammation in neither healthy subjects nor MS patients. We conclude that sIL-2Rα is associated with TNFα and CRP in healthy subjects. However, further research is required to confirm the use of sIL-2Rα as biomarker of systemic inflammation as well as to assess the mechanism underlying the observed correlation between levels of sIL-2Rα and TNFα.