B cell depletion via anti-CD20 antibodies is a highly effective treatment for multiple sclerosis (MS). However, little is known about the maturation/activation stage of the returning B cell population after treatment cessation and the wider effects on other immune cells. In the present study, 15 relapsing-remitting MS patients receiving 1,000 mg of rituximab were included. B, T, and myeloid cells were analyzed before anti-CD20 administration and in different time intervals thereafter over a period of 24 mo. In comparison to the phenotype before anti-CD20 treatment, the reappearing B cell pool revealed a less mature and more activated phenotype: 1) reappearing B cells were significantly enriched in transitional (before: 10.1 ± 1.9%, after: 58.8 ± 5.2%) and mature naive phenotypes (before: 45.5 ± 3.1%, after: 25.1 ± 3.5%); 2) the frequency of memory B cells was reduced (before: 36.7 ± 3.1%, after: 8.9 ± 1.7%); and 3) reappearing B cells showed an enhanced expression of activation markers CD25 (before: 2.1 ± 0.4%, after: 9.3 ± 2.1%) and CD69 (before: 5.9 ± 1.0%, after: 21.4 ± 3.0%), and expressed significantly higher levels of costimulatory CD40 and CD86. T cells showed 1) a persistent increase in naive (CD4+: before: 11.8 ± 1.3%, after: 18.4 ± 3.4%; CD8+: before: 12.5 ± 1.4%, after: 16.5 ± 2.3%) and 2) a decrease in terminally differentiated subsets (CD4+: before: 47.3 ± 3.2%, after: 34.4 ± 3.7%; CD8+: before: 53.7 ± 2.1%, after: 49.1 ± 2.7%).

The origin and function of CD20 + T cells are poorly understood. Here, we characterized CD20 + T cells in mice and humans and investigated how they are affected by anti-CD20 antibody treatment. We report that murine CD20 + T cells are unable to endogenously express the B cell lineage marker CD20; the development of CD20 + T cells in rodents requires the presence of CD20-expressing B cells. Our results demonstrated that both murine and human T cells acquire CD20 from B cells via trogocytosis while being activated by an antigen-presenting B cell. In patients with multiple sclerosis (MS) and mice with experimental autoimmune encephalomyelitis (EAE), expression of CD20 on T cells is associated with an up-regulation of activation markers, proinflammatory cytokines, and adhesion molecules, suggesting high pathogenic potential. Supporting this hypothesis, CD20 + T cells expand during active EAE in rodents; furthermore, adoptive transfer of CD20 + T cells into EAE-diseased mice worsened histological and clinical severity. Of direct therapeutic relevance, we demonstrate that the exclusive therapeutic elimination of CD20 + T cells effectively ameliorates EAE, independent of B cells. The results support the hypothesis that CD20 + T cells arise upon B cell–T cell interaction and that depletion of CD20 + T cells might contribute to the success of anti-CD20 antibody therapies in MS and other inflammatory disorders.

BackgroundIn the past, multiple sclerosis (MS) medications have been primarily designed to modulate T cell properties. Based on the emerging concept that B cells are equally important for the propagation of MS, we compared the effect of four commonly used, primarily T cell-targeting MS medications on B cells.MethodsUsing flow cytometry, we analyzed peripheral blood mononuclear cells (PBMC) of untreated (n = 19) and dimethyl fumarate (DMF; n = 21)-, fingolimod (FTY; n = 17)-, glatiramer acetate (GA; n = 18)-, and natalizumab (NAT; n = 20)-treated MS patients, focusing on B cell maturation, differentiation, and cytokine production.ResultsWhile GA exerted minor effects on the investigated B cell properties, DMF and FTY robustly inhibited pro-inflammatory B cell function. In contrast, NAT treatment enhanced B cell differentiation, activation, and pro-inflammatory cytokine production when compared to both intraindividual samples collected before NAT treatment initiation as well as untreated MS controls. Our mechanistic in vitro studies confirm this observation.ConclusionOur data indicate that common MS medications have differential, in part opposing effects on B cells. The observed activation of peripheral B cells upon NAT treatment may be instructive to interpret its unfavorable effect in certain B cell-mediated inflammatory conditions and to elucidate the immunological basis of MS relapses after NAT withdrawal.Trial registrationProtocols were approved by the ethical review committee of the University Medical Center Göttingen (#3/4/14).

Acute ischemic cardiac injury predisposes one to cognitive impairment, dementia, and depression. Pathophysiologically, recent positron emission tomography data suggest astroglial activation after experimental myocardial infarction (MI). We analyzed peripheral surrogate markers of glial (and neuronal) damage serially within 12 months after the first ST-elevation MI (STEMI). Serum levels of glial fibrillary acidic protein (GFAP) and neurofilament light chain (NfL) were quantified using ultra-sensitive molecular immunoassays. Sufficient biomaterial was available from 45 STEMI patients (aged 28 to 78 years, median 56 years, 11% female). The median (quartiles) of GFAP was 63.8 (47.0, 89.9) pg/mL and of NfL 10.6 (7.2, 14.8) pg/mL at study entry 0–4 days after STEMI. GFAP after STEMI increased in the first 3 months, with a median change of +7.8 (0.4, 19.4) pg/mL (p = 0.007). It remained elevated without further relevant increases after 6 months (+11.7 (0.6, 23.5) pg/mL; p = 0.015), and 12 months (+10.3 (1.5, 22.7) pg/mL; p = 0.010) compared to the baseline. Larger relative infarction size was associated with a higher increase in GFAP (ρ = 0.41; p = 0.009). In contrast, NfL remained unaltered in the course of one year. Our findings support the idea of central nervous system involvement after MI, with GFAP as a potential peripheral biomarker of chronic glial damage as one pathophysiologic pathway.

Introduction: Acute ischemic cardiac injury predisposes for cognitive impairment, dementia and depression. Beyond altered cerebral blood flow and neurohumoral activation, recent positron emission tomography data pathophysiologically suggest acute and chronic neuroinflammation, which is accompanied by astroglial activation, after acute experimental myocardial infarction (MI). Hypothesis: Peripheral serum biomarkers indicating neuronal and glial involvement are altered in the year after first acute MI. Methods: Within the investigator-initiated, prospective, multicenter diagnostic ETiCS study, we quantified serum levels of neurofilament light chain (NfL) and glial fibrillary acidic protein (GFAP) using ultra-sensitive molecular immunoassays serially in the year after first ST-elevation MI (STEMI). Cardiac magnetic resonance imaging enabled precise detection of infarction volume and ejection fraction. Results: Sufficient biomaterial was available from 45 STEMI patients (aged 28 to 78 years, median 56 years, 11% female). Median serum NfL (quartiles) at hospital admission was 10.6 (7.2, 14.8 pg/ml) and median GFAP 63.8 (47.0, 89.9 pg/ml). Absolute levels of NfL (ρ=0.78; p<0.001) and GFAP (ρ=0.56; p<0.001) correlated to patient age at all time-points. While NfL remained unaltered in the course of one year, GFAP after STEMI increased in the first 3 months after MI with a mean change of +10.6±25.0 pg/ml (p=0.007), and remained elevated after 6 months (+12.4±32.9 pg/ml; p=0.015) and 12 months (+12.6±31.2 pg/ml; p=0.010) compared to baseline. Larger relative infarction volume (ρ=0.41; p=0.009) and higher peak creatine kinase levels (ρ=0.39; p<0.001), but not ejection fraction, correlated to increases of GFAP and NfL, respectively. Conclusions: Our findings suggest subtle glial damage after STEMI which correlates to infarction volume. Further studies need to evaluate the valence of serum GFAP as a peripheral biomarker of cognitive decline after MI.