Abstract
Background: Hereditary hemorrhagic telangiectasia (HHT) is a rare genetic disease characterized by a deregulated neo-angiogenesis. Besides a mainly vascular phenotype (telangiectasia, arteriovenous malformations), patients exhibit a specific infectious risk and a deficit of T and natural killer (NK) lymphocytes. As the CXCR4/CXCL12 chemotactic axis is dysregulated in HHT endothelial cells, we hypothesized that a similar phenomenon could occur on lymphocytes.Results: Eighteen HHT patients with history of severe infection (HSI) were matched in age and sex with 18 HHT without HSI and 18 healthy control subjects (HC). We assessed the cell count and the surface expression of CXCR4 and CD26 (CXCL12 inactivating peptidase) of circulating helper and cytotoxic T lymphocytes (including naive, memory and activated subsets) and NK cells.The overall HHT group of 36 patients exhibited a reduction of circulating T-helper lymphocytes compared to HC (median: 517 vs 1026 cells/mm3, p<0.0001), correlated with age (r=-0.46, p=0.005), requirement of intravenous iron or blood transfusions (median: 291 vs 627 cells/mm3, p=0.03) and CXCR4 surface expression (r=0.353, p=0.0345). CXCR4 and CD26 membrane expression were both decreased on HHT T-helper lymphocytes (median MFI ratio: 4.49 vs 5.74 for CXCR4 and 3.21 vs 4.33 for CD26, p=0.03 and 0.0018 respectively) with an unchanged CXCR4/CD26 ratio. The HHT group with HSI had a higher CXCR4/CD26 ratio on the naive T-helper lymphocytes (median: 2.34 vs 1.32, p=0.0002), also observed on the T and T-helper populations.Conclusions: Our findings support a dysregulation of the CXCL12/CXCR4 chemotaxis of T-helper lymphocytes in HHT patients, potentially linked to their T-helper lymphopenia and susceptibility to infection.
R-loops cause genomic instability in T helper lymphocytes from patients with Wiskott-Aldrich syndrome
