Phenotype and functions of B cells in patients with acute brain injuries

Alexis Chenouard (1, 2) , Mélanie Chesneau (1, 2) , Faouzi Braza (1, 2) , Thomas Dejoie (3) , Raphael Cinotti (4) , Antoine Roquilly (4, 5) , Sophie Brouard (1, 6, 2) , Karim Asehnoune (4, 5)

1 U1064 Inserm - CRTI - Centre de Recherche en Transplantation et Immunologie
2 ITUN - Institut de transplantation urologie-néphrologie
3 Laboratoire de Biochimie [Nantes]
4 Département d'anesthésie et de soins intensifs - Unité de Soins Intensifs [CHU Nantes]
5 EA 3826 - Thérapeutiques cliniques et expérimentales des infections (EA 3826)
6 CIC biothérapies CBT 0503 [Nantes]

Background: Brain injuries (BI) induce a state of systemic immunosuppression, leading to a high risk of pneumonia. In this pilot study, we investigated the status of B cell compartment in BI patients. Methods: A prospective observational study was performed in 2 intensive care units in a university hospital. Blood samples were collected in 14 patients at day 1 and day 7 after acute BI. The phenotype and the ability of B cells to secrete IL-10 were compared to 11 healthy volunteers (HV). Results: Among the circulating lymphocytes, the frequency of B cells was significantly higher in BI patients compared to HV (p < 0.001). B cells from BI patients displayed an activated profil on day 7 after BI, reflected by a significantly higher proportion of CD27 + memory (p = 0.01) and CD27 + IgD − switched memory B cells (p = 0.02), as well as a significantly higher blood level of IgA (p = 0.001) and IgM (p < 0.001) as compared to day 1. The frequency of IL-10 secreting B cells (IL-10 + B cells) on day 1 and day 7 was significantly lower in BI patients compared to HV (p < 0.05). Interestingly, we observed that all BI patients with high frequency of IL-10 + B cells on day 1 displayed an episode of pneumonia, and had a longer duration of mechanical ventilation and ICU stay compared to BI patients with low proportion of IL-10 + B cells. Conclusion: This study provides an extensive description of the phenotype and function of B cells in BI patients. Our results suggest that IL-10 + B cells could play a major role in immunosuppression after BI.

Mots clés: B cells; Brain injury; IL-10; IL-10(+) B cells; Immune suppression; Regulatory B cells

Domaines: Médecine humaine et pathologie

Alexis Chenouard, Mélanie Chesneau, Faouzi Braza, Thomas Dejoie, Raphael Cinotti, et al.. Phenotype and functions of B cells in patients with acute brain injuries. Molecular Immunology, 2015, 68 (2), pp.350-356. ⟨10.1016/j.molimm.2015.09.001⟩. ⟨inserm-02147900⟩