Lymphopoiesis (P. Guglielmi)

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Lymphopoiesis
Paul Guglielmi

The similarities between mammalian and fish lymphopoiesis allow the identification of patterns of differentiation and robust mechanisms conserved during evolution. In Danio rerio, we have established fluorescent transgenic lines identifying B cells at all stages of their maturation, allowing us to take advantage of this model in terms of live animal imaging. Confocal imaging has established that Danio B-lymphopoiesis is carried out through two main pathways:
1 / the primitive hematopoiesis, which originates at 2 jpf from hemogenic buds on the surface of the yolk sac;
2 / the classical hematopoiesis, dependent on conventional stem cells and taking place first in the caudal hematopoietic tissue, then in the cephalic kidney. 
We complete our imaging work by analyzing the transcriptome of B cells during their maturation. Our aim is to develop analysis protocols on isolated individual cells. An analysis of the antibody repertoire by RNA-Seq completes this study.
Research axes

Until recently, analyses on the lymphopoiesis in Danio rerio have primarily focused on T cells due to the lack of reagents and specific biological models for B cells. We have established fluorescent transgenic lines identifying B cells at all stages of their maturation, allowing us to take advantage of this model in terms of live animal imaging. Confocal imaging has established that Danio B-lymphopoiesis is carried out through two main pathways:

1 / the primitive hematopoiesis, which originates at 2 dpf from hemogenic buds on the surface of the yolk sac;

2 / the classical hematopoiesis, dependent on conventional stem cells and taking place first in the caudal hematopoietic tissue, then in the cephalic kidney. 

This type of organization is parallel to that leading to the production of B1 and B2 lymphocytes in mammals.

We use these reporter lines to study the differentiation of B cells in a context where it occurs mainly in non-lymphoid tissues (a situation that is close to certain human pathologies).

Axis 1 : B-cell precursors and primitive antibody repertoire

A first approach will place particular emphasis on the characterization of B-cell precursors and primitive antibody repertoires. We will perform a transcriptomic analysis of individual cells belonging to different types of B lymphocytes in order to characterize the molecular signatures associated with the various developmental trajectories. In a following validation step, representative antibody properties will be assayed using chimeric recombinant immunoglobulins.

Axis 2 : B-cell function during infection in the zebrafish

A second approach will consist in monitoring the evolution of B-cell functions during the life of fish in a stable situation or during host-pathogen interactions. Models of parasitic infections (Trypanosoma carassii and Trypanoplasma borreli) developed in the common carp, recently adapted to Danio rerio and characterized by the polyclonal activation of B and T lymphocytes, make this type of approach possible.

Team members involved in the project
Collaborations
Selected publications
Alumni

Theme leader


Paul GUGLIELMI
Research Director (DR2) INSERM, Emeritus
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