A fully-financed PhD position is avalaibale for outstanding master students at the institut Simon Veil / UMR1173 / University of Versailles-Saint Quentin en yvelines. The selected candidate will work within the team of Prof Maxime Breban.

Study of HLA-27 effect on Th17 differentiation in response to BMP/TGFbeta family ligands

Read the full project here:

Spondyloarthritis (SpA) refers to a group of inflammatory joint disorders strongly associated with a particular genetic risk factor, the HLA-B27 allele, by unknown mechanism (1). Trying to elucidate such 46-years-old mystery, we have recently developed a new HLA-B27 transgenic Drosophila model that allowed us to evidence an unpredicted deleterious consequence of HLA-B27 expression (2). We observed that HLA-B27 interacted specifically with an inhibitory type I receptor of the BMP/TGFb family in Drososphila and with its mammalian ortholog, ALK2 in human cells. We showed an exacerbation of BMP/TGFb signaling in human T cells and B cells from HLA-B27+ SpA patients that could potentially lead an aberrant inflammatory response and in particular to a Th17 differentiation bias that is considered as a key effector pathway in SpA (3).

The first aim of this thesis work will be to expand from our initial findings to identify if HLA-B27+ T cells are biased towards Th17 differentiation in response to ligands of the BMP/TGFb family. This will be done using peripheral blood T lymphocytes from HLA-B27+ SpA patients and in an animal model of SpA, i.e. the HLA-B27 transgenic rat. CD4+ T lymphocytes will be purified a

nd activated in the presence of recombinant ligands of the BMP/TGFb family, i.e. TGFb, Activin A alone or in combination. The differentiation will be carried in vitro towards Th17 phenotype, using suitable protocols available in the team. The result of the differentiation process will be assessed by evaluating the production of cytokines such as IL-17 and TNFa, both intra-cellularly by Flow Cytometry and in culture supernatant by ELISA. Perspectives: if it is confirmed that the presence of HLA-B27 results in skewing T lymphocytes differentiation towards Th17 bias, the underlying biological mechanism will be assessed to try connecting the early signaling events with the observed bias, using RNAseq and epigenetic approach.

The second aim will be to identify the HLA-B27-bound specific peptidome from HLA-B27-tg Drosophila imaginal wings, in collaboration with Dr. Arie Admon (Technion–Israel Institute of Technology, Israel), to compare this peptidome with known HLA-B27 bound peptides from HLA-B27+ human cells and SpA-prone HLA-B27 transgenic rats (4,5). Selected peptides will be synthetized and added to HLA-B27-transfected murine cell line to assess their influence on HLA-B27 stability and on the interaction between HLA-B27 and type I BMP/TGFb receptors.

1- Bowness P. HLA-B27. Annu Rev Immunol 2015;33:29–48. doi:10.1146/annurev-immunol-032414-112110

2- Grandon B. et al, HLA-B27 alters BMP/TGFb signaling in Drosophila, revealing putative pathogenic mechanism for spondyloarthritis. Ann Rheum Dis in press.

3- Glatigny S, Fert I, Blaton MA, et al. Proinflammatory Th17 cells are expanded and induced by dendritic cells in spondylarthritis-prone HLA-B27-transgenic rats. Arthritis Rheum 2012;64:110–20. doi:10.1002/art.33321

4- García-Medel N, Sanz-Bravo A, Alvarez-Navarro C, et al. Peptide Handling by HLA-B27 Subtypes Influences Their Biological Behavior, Association with Ankylosing Spondylitis and Susceptibility to Endoplasmic Reticulum Aminopeptidase 1 (ERAP1). Mol Cell Proteomics 2014;13:3367–3380.

5- Barnea E, Melamed Kadosh D, Haimovich Y, et al. The Human Leukocyte Antigen (HLA)-B27 Peptidome in Vivo, in Spondyloarthritis-Susceptible HLA-B27 Transgenic Rats and the Effect of Erap1 Deletion. Mol Cell Proteomics 2017;16:642–662. doi.org/10.1074/mcp.M116.066241