Benjamin Terrier1, Celine Posseme2, Marie Temple3, Aurélien Corneau4, Francesco Carbone5, Eugénie Duroyon3, camille Gobeaux3, Estibaliz Lazaro6, Roderau Outh7, Guillaume Le Guenno8, Francois Lifermann9, Marie Berleur10, Thierry Weitten11, Vivien Guillotin12, Cédric Lenormand13, Hang-Korng Ea14, Mickael Ménager5, Darragh Duffy2 and Olivier Kosmider3, 1National Referral Center for Rare Systemic Autoimmune Diseases, Cochin Hospital, Paris, France, 2Institut Pasteur, Paris, France, 3Cochin Hospital, Paris, France, 4Pitié Salpêtrière Hospital, Paris, France, 5Institut Imagine, Paris, France, 6Bordeaux Hospital University, Bordeaux, France, 7CH, Perpignan, France, 8CHU, Clermont-Ferrand, France, 9Dax Hospital, Dax, France, 10CH, Versailles, France, 11CHIGAS, Gap, France, 12CHU Bordeaux, Bordeaux, France, 13CHRU, Strasbourg, France, 14Lariboisière Hospital, Paris, France
Background/Purpose: Acquired mutations in the UBA1 gene, occurring in myeloid cells and resulting in expression of a catalytically impaired isoform of the enzyme E1, were recently identified in patients with severe adult-onset auto-inflammatory syndrome called VEXAS (vacuoles, E1 enzyme, X-linked, autoinflammatory, somatic). The precise physiological and clinical impact of these mutations remains poorly defined.
Methods: We studied a unique prospective cohort of individuals with severe autoinflammatory disease with (VEXAS) or without (VEXAS-like) UBA1 somatic mutations and compared with low-risk myelodysplastic syndromes (MDS) and aged gender-matched healthy controls. We performed an integrated immune analysis including multiparameter phenotyping of peripheral blood leukocytes, cytokines profiling, bulk and single-cell gene expression analyses and skin tissue imaging mass cytometry.
Results: Focusing on myeloid cells, we show that monocytes from UBA1-mutated individuals were quantitatively and qualitatively impaired and displayed features of exhaustion with aberrant expression of chemokine receptors. Within affected tissues, pathological skin biopsies from VEXAS patients showed an abundant enrichment of CD16+CD163+ monocytes adjacent to blood vessels and M1 macrophages, possibly promoting local inflammation in part through STAT3 activation. In peripheral blood from VEXAS patients, we identified a significant increase in circulating levels of many proinflammatory cytokines, including IL-1β and IL-18 which reflect inflammasome activation and markers of myeloid cells dysregulation. Gene expression analysis of whole blood confirmed the role of circulating cells in the IL-1β and IL-18 dysregulation in VEXAS patients and revealed a significant enrichment of TNF-a and NFkB signaling pathways that could mediate cell death and inflammation. Single-cell analysis confirmed the inflammatory state of monocytes from VEXAS patients and allowed us to identify specific molecular pathways that could explain monocytopenia, especially the activation of PANoptosis and a deficiency in the TYROBP/DAP12 axis and β-catenin signaling pathway.
Conclusion: Our findings on monocytes from patients with UBA1 mutations provide important insights into the molecular mechanisms involving the mature myeloid commitment in VEXAS syndrome and suggest that the control of the undescribed inflammasome activation and PANoptosis could be novel therapeutic targets in this condition.
Disclosures: B. Terrier, AstraZeneca, GlaxoSmithKline, Bristol-Myers Squibb(BMS), Eli Lilly, LFB, Boehinger Ingelheim, Vifor Pharma, Pfizer, Roche; C. Posseme, None; M. Temple, None; A. Corneau, None; F. Carbone, None; E. Duroyon, None; c. Gobeaux, None; E. Lazaro, None; R. Outh, None; G. Le Guenno, None; F. Lifermann, Roche; M. Berleur, None; T. Weitten, None; V. Guillotin, None; C. Lenormand, None; H. Ea, None; M. Ménager, None; D. Duffy, None; O. Kosmider, None.