Ce mois-ci, la SFI et le Club Français des Jeunes Immunologistes mettent en avant l’article publié dans Blood, de Charlotte Boussard, qui fait sa thèse avec le Dr. Frédéric RIEUX-LAUCAT, à l’Institut Imagine, Paris. L’article concourra pour le prix du  » Meilleur article doctorant » au mois de juillet prochain.


Journal Blood, March 2023

DOCK11 deficiency in patients with X-linked actinopathy and autoimmunity

Auteurs Boussard C., Delage L. et al, Blood 2023
Résumé Dedicator of cytokinesis (DOCK) proteins play a central role in actin cytoskeleton regulation. This is highlighted by the DOCK2 and DOCK8 deficiencies leading to actinopathies and immune deficiencies. DOCK8 and DOCK11 activate CDC42, a RHO-GTPase involved in actin cytoskeleton dynamics, among many cellular functions. The role of DOCK11 in human immune disease has been long suspected but has never been described so far. We studied eight male patients, from seven unrelated families, with hemizygous DOCK11 missense variants leading to reduced DOCK11 expression. The patients were presenting with early-onset autoimmunity, including cytopenia, systemic lupus
erythematosus, skin, and digestive manifestations. Patients’ platelets exhibited abnormal ultrastructural morphology and spreading as well as impaired CDC42 activity. In vitro activated T cells and B lymphoblastoid cell lines (B-LCL) of patients exhibited aberrant protrusions and abnormal migration speed in confined channels concomitant with altered actin polymerization during migration. A DOCK11 knock-down recapitulated these abnormal cellular phenotypes in monocytesderived dendritic cells (MDDC) and primary activated T cells from healthy controls. Lastly, in line
with the patients’ autoimmune manifestations, we also observed abnormal regulatory T cells (Tregs) phenotype with profoundly reduced FOXP3 and IKZF2 expression. Moreover, we found a reduced T cell
proliferation and an impaired STAT5B phosphorylation upon IL2 stimulation of the patients’lymphocytes. In conclusion, DOCK11 deficiency is a new X-linked immune-related actinopathy leading
to impaired CDC42 activity and STAT5 activation, and associated with abnormal actin cytoskeleton remodeling as well as Tregs phenotype culminating in immune dysregulation and severe early-onset

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