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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Research Article Immunology

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 6

Clonogenic potential of NKG2D-L+ and NKG2D-L– FA CD34+ cells and NKG2D receptor blockade effects.

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Clonogenic potential of NKG2D-L+ and NKG2D-L– FA CD34+ cells and NKG2D r...
(A) Analysis of the clonogenic potential of NKG2D-L–expressing and nonexpressing BM CD34+ cells from 2 patients with FA. Left panels show the cell-sorting strategy used to determine the clonogenic potential of NKG2D-L+ and NKG2D-L– CD34+ cell fractions. FMO corresponds to the PE fluorochrome used for the sorting of NKG2D-L+ and NKG2D-L– cells. Right graphs show the colony numbers generated by NKG2D-L+ and NKG2D-L– CD34+ cells from patients with FA. The numbers above the red bars indicate the percentage of colonies generated by NKG2D-L+ compared with NKG2D-L– CD34+ cells. (B) Effects mediated by NKG2D receptor blockade on the clonogenic potential of BM samples from HDs and patients with FA. Left panel shows the experimental protocol used to evaluate the clonogenic effects mediated by inhibition of the NKG2D receptor. Right panel shows the ratio between the number of hematopoietic colonies generated by HD (n = 9) or FA (n = 23) BM samples after incubation with an anti-NKG2D–blocking antibody (a-NKG2D) or an isotype control. Black data points represent colony numbers generated in experiments performed with mononuclear BM cells. Some experiments (red data points) were performed using purified BM CD34+ cells (as target cells) and purified BM NK cells (as effector cells) from the same donor (effector/target cell ratio of 10:1). Mean values ± SEM are shown. An unpaired t test was used to compare mean values. Total colony numbers are shown in Supplemental Figure 7.