Autoinflammation in patients with leukocytic CBL loss of heterozygosity is caused by constitutive ERK-mediated monocyte activation
Jonathan Bohlen, et al.
Jonathan Bohlen, et al.
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Research Article Autoimmunity Immunology

Autoinflammation in patients with leukocytic CBL loss of heterozygosity is caused by constitutive ERK-mediated monocyte activation

Abstract

Patients heterozygous for germline CBL loss-of-function (LOF) variants can develop myeloid malignancy, autoinflammation, or both, if some or all of their leukocytes become homozygous for these variants through somatic loss of heterozygosity (LOH) via uniparental isodisomy. We observed an upregulation of the inflammatory gene expression signature in whole blood from these patients, mimicking monogenic inborn errors underlying autoinflammation. Remarkably, these patients had constitutively activated monocytes that secreted 10 to 100 times more inflammatory cytokines than those of healthy individuals and CBL LOF heterozygotes without LOH. CBL-LOH hematopoietic stem and progenitor cells (HSPCs) outgrew the other cells, accounting for the persistence of peripheral monocytes homozygous for the CBL LOF variant. ERK pathway activation was required for the excessive production of cytokines by both resting and stimulated CBL-LOF monocytes, as shown in monocytic cell lines. Finally, we found that about 1 in 10,000 individuals in the UK Biobank were heterozygous for CBL LOF variants and that these carriers were at high risk of hematological and inflammatory conditions.

Authors

Jonathan Bohlen, Ivan Bagarić, Taja Vatovec, Masato Ogishi, Syed F. Ahmed, Axel Cederholm, Lori Buetow, Steicy Sobrino, Corentin Le Floc’h, Carlos A. Arango-Franco, Luis Seabra, Marine Michelet, Federica Barzaghi, Davide Leardini, Francesco Saettini, Francesca Vendemini, Francesco Baccelli, Albert Catala, Eleonora Gambineri, Marinella Veltroni, Yurena Aguilar de la Red, Gillian I. Rice, Filippo Consonni, Laureline Berteloot, Laetitia Largeaud, Francesca Conti, Cécile Roullion, Cécile Masson, Boris Bessot, Yoann Seeleuthner, Tom Le Voyer, Darawan Rinchai, Jérémie Rosain, Anna-Lena Neehus, Lucia Erazo-Borrás, Hailun Li, Zarah Janda, En-Jui Cho, Edoardo Muratore, Camille Soudée, Candice Lainé, Eric Delabesse, Claire Goulvestre, Cindy S. Ma, Anne Puel, Stuart G. Tangye, Isabelle André, Christine Bole-Feysot, Laurent Abel, Miriam Erlacher, Shen-Ying Zhang, Vivien Béziat, Chantal Lagresle-Peyrou, Emmanuelle Six, Marlène Pasquet, Laia Alsina, Alessandro Aiuti, Peng Zhang, Yanick J. Crow, Nils Landegren, Riccardo Masetti, Danny T. Huang, Jean-Laurent Casanova, Jacinta Bustamante

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Figure 4

Characterization of activated monocytes in CBL-LOH patients.

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Characterization of activated monocytes in CBL-LOH patients. (A) Number ...
(A) Number of differentially expressed genes in the detected leukocyte subsets on scRNA-Seq on cryopreserved PBMCs from healthy adult (n = 11) and pediatric (n = 6) controls, and adults (n = 2) and children (n = 4) with CBL-LOH. (B and C) Gene set enrichment analysis of genes differentially expressed in classical (B) and non-classical (C) monocytes of CBL-LOH patients relative to healthy controls. (D) Numbers of differentially expressed genes in the detected leukocyte subsets common to CBL-LOH patients and patients with heterozygous gain-of-function (GOF) variants of STAT1, STAT3, and PIK3CD (n = 1, 1, and 2, respectively), and an MIS-C patient with RNase L deficiency. (E) Bulk RNA-Seq on healthy control (n = 10) and CBL-LOH patient monocytes after 24 hours of culture without stimulation ex vivo. Gene set enrichment analysis was performed, and the pathways for which significant enrichment was detected are shown in blue and red. (F) Diagram of UPR stress-induced XBP1 splicing. (G and H) Quantification of stress-dependent XBP1 splicing in PBMCs (G) and monocytes (H) from healthy controls (n = 10) and CBL-LOH patients (n = 6). *P < 0.05, ***P < 0.0005 by Mann-Whitney test. (I) Cytokine production by the indicated THP-1 cell lines following TNF stimulation with or without ASTX-029 at the indicated concentrations, including pretreatment with the inhibitor for 1 hour. Supernatants were collected after 24 hours. Dose-response curves were plotted. (J) Cytokine production by monocytes from patients and healthy controls stimulated with TNF with or without 1 μM ASTX-029, including pretreatment with the inhibitor for 1 hour. Supernatants were collected after 24 hours.