Contributions
Abstract: P757
Type: Poster Sessions
Abstract Category: Pathology and pathogenesis of MS - Immunology
Introduction: Clinical trials on the efficacy of B-cell depleting therapies in relapsing MS have suggested that B cells may contribute to MS pathogenesis, potentially through antibody independent mechanisms. Meningeal aggregates full of B cells and plasma cells have been observed in all forms of MS. Even if there has been significant progress in the understanding of B cell roles in MS, the exact implication of plasma cells and their functions at different disease stages remain relatively unknown.
Methods:
(1) In order to characterize the B cell differentiation profile of MS patients, we used an in vitro model of peripheral B cell differentiation. We assessed the abilities of B cells to differentiate into plasmablasts/plasma cells, the sensitivity to apoptosis and the proliferation of these cells using flow cytometry. All MS samples were compared to healthy controls (HC).
(2) The major role of follicular helper T cells (TFH) in B cell differentiation in vivo led us to characterize the phenotype of TFH cells in the blood and the cerebrospinal fluid (CSF) of MS patients using flow cytometry.
Results:
(1) Thirteen HC (38.8 ± 4.7 y.o) and 17 untreated relapsing-remitting MS patients (39.2 ± 9.9 y.o) were included for the differentiation analysis. We found that MS patients present a lower proliferation of total B cells, and a significantly decreased frequency of plasmablasts with higher sensitivity to apoptosis compared to HC.
(2) Thirty-four HC (35.71 ± 1.38 y.o) and 47 untreated MS patients (40.15 ± 2 y.o) were included for the TFH part. We observed that MS patients have a higher frequency of circulating TFH17 and a lower frequency of circulating TFH1, suggesting high helping abilities. As of now, we have analysed the phenotype of TFH cells within the CSF of 7 untreated MS patients (39.14 ± 12.48 y.o). Interestingly, not only did we find higher frequencies of CSF TFH cells compared to paired blood, but they also present an activated profile.
Conclusion: For the first time, we show that MS patients present a defect in their B cell differentiation with altered circulating TFH phenotype. Our future plans include analysing the cytokines secreted after differentiation, performing RNA sequencing on differentiated plasmablasts and also testing the supernatant's cytotoxic effects on human oligodendrocytes cultures.
Disclosure: J. Morille, F. Lejeune, M. Chesneau, A. Garcia, L. Berthelot, A. Nicot, S. Brouard : nothing to disclose.
D.A. Laplaud : consultancy fees, speaker fees, research grants (non-personal), or honoraria from Novartis, Biogen-Idec, Merck, Bayer Schering, Roche, Medday, Teva and Genzyme Sanofi.
L. Michel : received honoraria as consultant from Merck, Teva, Novartis, Roche, Sanofi genzyme and Biogen.
Abstract: P757
Type: Poster Sessions
Abstract Category: Pathology and pathogenesis of MS - Immunology
Introduction: Clinical trials on the efficacy of B-cell depleting therapies in relapsing MS have suggested that B cells may contribute to MS pathogenesis, potentially through antibody independent mechanisms. Meningeal aggregates full of B cells and plasma cells have been observed in all forms of MS. Even if there has been significant progress in the understanding of B cell roles in MS, the exact implication of plasma cells and their functions at different disease stages remain relatively unknown.
Methods:
(1) In order to characterize the B cell differentiation profile of MS patients, we used an in vitro model of peripheral B cell differentiation. We assessed the abilities of B cells to differentiate into plasmablasts/plasma cells, the sensitivity to apoptosis and the proliferation of these cells using flow cytometry. All MS samples were compared to healthy controls (HC).
(2) The major role of follicular helper T cells (TFH) in B cell differentiation in vivo led us to characterize the phenotype of TFH cells in the blood and the cerebrospinal fluid (CSF) of MS patients using flow cytometry.
Results:
(1) Thirteen HC (38.8 ± 4.7 y.o) and 17 untreated relapsing-remitting MS patients (39.2 ± 9.9 y.o) were included for the differentiation analysis. We found that MS patients present a lower proliferation of total B cells, and a significantly decreased frequency of plasmablasts with higher sensitivity to apoptosis compared to HC.
(2) Thirty-four HC (35.71 ± 1.38 y.o) and 47 untreated MS patients (40.15 ± 2 y.o) were included for the TFH part. We observed that MS patients have a higher frequency of circulating TFH17 and a lower frequency of circulating TFH1, suggesting high helping abilities. As of now, we have analysed the phenotype of TFH cells within the CSF of 7 untreated MS patients (39.14 ± 12.48 y.o). Interestingly, not only did we find higher frequencies of CSF TFH cells compared to paired blood, but they also present an activated profile.
Conclusion: For the first time, we show that MS patients present a defect in their B cell differentiation with altered circulating TFH phenotype. Our future plans include analysing the cytokines secreted after differentiation, performing RNA sequencing on differentiated plasmablasts and also testing the supernatant's cytotoxic effects on human oligodendrocytes cultures.
Disclosure: J. Morille, F. Lejeune, M. Chesneau, A. Garcia, L. Berthelot, A. Nicot, S. Brouard : nothing to disclose.
D.A. Laplaud : consultancy fees, speaker fees, research grants (non-personal), or honoraria from Novartis, Biogen-Idec, Merck, Bayer Schering, Roche, Medday, Teva and Genzyme Sanofi.
L. Michel : received honoraria as consultant from Merck, Teva, Novartis, Roche, Sanofi genzyme and Biogen.