Upregulation of NKG2D ligands impairs hematopoietic stem cell function in Fanconi anemia
José A. Casado, … , Paula Rio, Juan A. Bueren
José A. Casado, … , Paula Rio, Juan A. Bueren
Published June 7, 2022
Citation Information: J Clin Invest. 2022;132(15):e142842. https://doi.org/10.1172/JCI142842.
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Upregulation of NKG2D ligands impairs hematopoietic stem cell function in Fanconi anemia

Abstract

Fanconi anemia (FA) is the most prevalent inherited bone marrow failure (BMF) syndrome. Nevertheless, the pathophysiological mechanisms of BMF in FA have not been fully elucidated. Since FA cells are defective in DNA repair, we hypothesized that FA hematopoietic stem and progenitor cells (HSPCs) might express DNA damage–associated stress molecules such as natural killer group 2 member D ligands (NKG2D-Ls). These ligands could then interact with the activating NKG2D receptor expressed in cytotoxic NK or CD8+ T cells, which may result in progressive HSPC depletion. Our results indeed demonstrated upregulated levels of NKG2D-Ls in cultured FA fibroblasts and T cells, and these levels were further exacerbated by mitomycin C or formaldehyde. Notably, a high proportion of BM CD34+ HSPCs from patients with FA also expressed increased levels of NKG2D-Ls, which correlated inversely with the percentage of CD34+ cells in BM. Remarkably, the reduced clonogenic potential characteristic of FA HSPCs was improved by blocking NKG2D–NKG2D-L interactions. Moreover, the in vivo blockage of these interactions in a BMF FA mouse model ameliorated the anemia in these animals. Our study demonstrates the involvement of NKG2D–NKG2D-L interactions in FA HSPC functionality, suggesting an unexpected role of the immune system in the progressive BMF that is characteristic of FA.

Authors

José A. Casado, Antonio Valeri, Rebeca Sanchez-Domínguez, Paula Vela, Andrea López, Susana Navarro, Omaira Alberquilla, Helmut Hanenberg, Roser Pujol, José-Carlos Segovia, Jordi Minguillón, Jordi Surrallés, Cristina Díaz de Heredia, Julián Sevilla, Paula Rio, Juan A. Bueren

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Figure 4

Effects of FANCA knockdown on NKG2D-L levels in HD CD34+ cells.

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Effects of FANCA knockdown on NKG2D-L levels in HD CD34+ cells. (A) Comp...
(A) Comparative analysis of NKG2D-L in HD CB CD34+ cells transduced with a control shRNA (shSCR/EGFP) or FANCA shRNA (shFANCA/EGFP) LVs. Left panel: NKG2D-L levels in EGFP+CD34+ cells that were transduced with either LV for 4–12 days prior to NKG2D-L analyses (n = 9). Right panels: Representative histograms of NKG2D-L levels in CD34+EGFP+ cells transduced with either LV. NKG2D-Ls were quantified 7 days (Exp 1) or 12 days (Exp 2) after transduction. (B) Left panel shows comparative analyses of NKG2D-L MFI ratios between EGFP+ and EGFP– cells in samples from the same culture as in A (n = 9). Right panels: Representative histograms showing comparative levels of NKG2D-L in EGFP+ versus EGFP– cells after transduction with shSCR/EGFP or shFANCA/EGFP LVs. (C) Seven days after transduction, FA-like CD34+ cells were incubated with a CHEK-1 inhibitor or DMSO vehicle, and NKG2D-L levels were analyzed in EGFP+ cells. Histograms show NKG2D-L levels in 2 independent experiments after incubation with a CHEK-1 inhibitor for 24 hours (Exp 1) or 48 hours (Exp 2). Differences in A were determined by paired t test. Differences in B were determined by Mann-Whitney U test. Mean values ± SEM are shown.