Integrative analysis of the biology of plasma cells in health and disease – AUTO-PLASMO
We are using an integrative and original approach combining classic immunology techniques with innovative cutting-edge technologies.
In the first part of this project, based on proteomics data, we are developing in vitro and ex vivo assays to analyse plasma cell fitness and antibody secretion.
The second task is based on the analysis of plasma cells at the transcriptomic level by single-cell RNAseq and at the protein level by CyTOF.
Finally, in the last task of this project plasma cell homing and survival within inflamed tissues from both SLE patients and autoimmune prone mouse models are analysed by flow cytometry, laser capture microdissection, transcriptomics and functional assays.
Task 1: Identification of new regulators of plasma cell function and survival in health and disease:
The role of 6 candidates have been tested in an in vitro differentiation assay based on the use of a plasma cell line. On the basis of this work we have then tested the impact of the 2 best candidates on primary plasma cell function and survival. Our results strongly suggest that they are key regulators of plasma cell survival and antibody secretion.
We are now investigating by which mechanisms these 2 proteins are impacting plasma cell fitness. Our results suggest that they both affect different signalling pathways.
In parallel, we have obtained from EUCOMM a conditional KO mouse model for one of these two proteins and are currently analysing its immune respose
Task 2: In-depth analysis of plasma cell phenotypic and functional heterogeneity in health and disease:
We analysed single-cell RNAseq data obtained from bone marrow plasma cells and our results were striking as we identified two subpopulations within long-lived plasma cells in this organ. From these datasets we extracted markers to discriminate these 2 subpopulations by mass cytometry and single cell qPCR.
Task 3: Characterization of inflamed tissue PC migration and survival.
We have recruited 24 SLE patients during flare and paired them with healthy volunteers. For each we have assessed which chemokine receptors are expressed at the surface of circulating plasma cells. This has allowed us to distinguish 4 chemokine receptors that are more expressed in patients than in controls. In parallel, we have started investigating the plasma cell microenvironment within the inflamed tissues in a mouse model of SLE by laser capture microdissection and qPCR.
Task1: In the next 18 months we will investigate how one of our candidate affects plasma cell biology in vivo in a mouse model.
Task 2: The use of single-cell RNAseq has allowed us to identify two subsets of plasma cells likely to have distinct functions and/or behaviour during an immune response. This discovery would not have been possible using another approach. During the next 18 months we will assess how these 2 subpopulations are generated, whether they depend on the hematopoietic organ analysed and if similar discrimination could be made in inflammatory conditions in mouse and human.
Task 3: Surprisingly, we have observed that not all patients express the same set of chemokine receptors at the surface of plasma cells. These results suggest that among this disease, different types of inflammation will predispose plasma cells to migrate towards different molecular clues. In the next 18 months we will finish the recruitment of our cohort of patients and confirm functionally the relevance of our results for plasma cell migration and survival.
Scientific production:
Accepted and peer-reviewed article:
Biajoux V, Natt J, Freitas C, Alouche N, Sacquin A, Hémon P, Gaudin F, Fazilleau N, Espéli M*, Balabanian K*. 2016. Efficient plasma cell differentiation and trafficking require Cxcr4 desensitization. Cell Reports. 2016 ; 17, 193–205 * co-last and co-corresponding authors
Book chapter:
1. Natt J and Espéli M. 2015. Assessing T follicular helper cell function in vivo: Antigen-specific B cell response to hapten and affinity maturation. in T follicular helper cells: Methods and protocols. Methods in Molecular Biology. 2015;1291:87-101
International oral communications:
1. BSI seminar series, Department of Pathology, Cambridge, UK, January 2016
2. European Congress of Immunology, Vienna, Austria, September 2015
Local oral communication:
Mercredi de Bichat-Baujean, CRI, Paris, France, May 2016
Autoimmune diseases represent an increasing burden on global health, with a steadily rising incidence and a consistent association with chronic illness and premature death. Despite this, therapy often relies on non-specific and potentially toxic immunosuppression, which carries its own morbidity. The recent development of antibody-mediated therapies has shown great promise for the treatment of several autoimmune diseases demonstrating that the development of specifically targeted therapies is the way forward for the treatment of these disabling conditions. Autoimmune disease are complex conditions characterized by a deregulation of the immune system that can implicate several cell types including B and T cells and affect different organs. Thus, we need to gain a better insight into the biology of the cells involved in these pathologies if we are to design and develop safer and more efficient therapies. The proposal AUTO-PLASMO focuses on plasma cells - the cells that are responsible for antibody production within the adaptive immune system. Plasma cells play an essential protective role against infection but they are also implicated in the pathology of several autoimmune diseases including systemic lupus erythematosus via secretion of pathologic autoantibodies. Despite their essential role in health and disease, how plasma cells are generated, survive and secrete antibodies is still not fully elucidated. Moreover, plasma cells are resistant to most therapies currently used to treat autoimmune disease. There is thus a knowledge gap that needs to be filled in order to offer new therapeutic options for the control or elimination of this cell subset.
This question forms the core of this research project that is divided in three complementary axes:
-Identification of new regulators of plasma cell survival and antibody secretion in health and disease.
-Analysis of plasma cell phenotypic and functional heterogeneity in health and disease.
-Characterization of plasma cell survival and migration in inflamed tissue in systemic lupus erythematosus.
These three axes form an integrative approach combining basic immunology techniques with innovative single-cell methods to study plasma cell function and survival in health and disease, which in turn could facilitate the identification and validation of new therapies that target this cell subset.
Project coordination
Marion Espéli (Inserm)
The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.
Partner
Inserm UMR-S996 Inserm
Help of the ANR 499,445 euros
Beginning and duration of the scientific project:
April 2015
- 48 Months
