Inhibition of CXCR1/2 reduces the emperipolesis between neutrophils and megakaryocytes in the Gata1low model of myelofibrosis.

Abstract

Emperipolesis between neutrophils and megakaryocytes was first identified by transmission electron microscopy. Although rare under steady-state conditions, its frequency greatly increases in myelofibrosis, the most severe of myeloproliferative neoplasms, in which it is believed to contribute to increasing the transforming growth factor (TGF)-β microenvironmental bioavailability responsible for fibrosis. To date, the challenge of performing studies by transmission electron microscopy has hampered the study of factors that drive the pathological emperipolesis observed in myelofibrosis. We established a user-friendly confocal microscopy method that detects emperipolesis by staining with CD42b, specifically expressed on megakaryocytes, coupled with antibodies that recognize the neutrophils (Ly6b or neutrophil elastase antibody). With such an approach, we first confirmed that the bone marrow from patients with myelofibrosis and from Gata1low mice, a model of myelofibrosis, contains great numbers of neutrophils and megakaryocytes in emperipolesis. Both in patients and Gata1low mice, the emperipolesed megakaryocytes were surrounded by high numbers of neutrophils, suggesting that neutrophil chemotaxis precedes the actual emperipolesis event. Because neutrophil chemotaxis is driven by CXCL1, the murine equivalent of human interleukin 8 that is expressed at high levels by malignant megakaryocytes, we tested the hypothesis that neutrophil/megakaryocyte emperipolesis could be reduced by reparixin, an inhibitor of CXCR1/CXCR2. Indeed, the treatment greatly reduced both neutrophil chemotaxis and their emperipolesis with the megakaryocytes in treated mice. Because treatment with reparixin was previously reported to reduce both TGF-β content and marrow fibrosis, these results identify neutrophil/megakaryocyte emperipolesis as the cellular interaction that links interleukin 8 to TGF-β abnormalities in the pathobiology of marrow fibrosis.

• Authors: Francesca Arciprete, Paola Verachi, Fabrizio Martelli, Mauro Valeri, Manjola Balliu, Paola Guglielmelli, Alessandro Maria Vannucchi, Anna Rita Migliaccio, Maria Zingariello
• Journal: Experimental hematology (Exp Hematol) Vol. 121 Pg. 30-37 (05 2023) ISSN: 1873-2399 [Electronic] Netherlands
• PMID: 36863479 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't)
• Copyright: Copyright © 2023 ISEH -- Society for Hematology and Stem Cells. Published by Elsevier Inc. All rights reserved.

Chemical References

• GATA1 Transcription Factor
• Interleukin-8
• reparixin
• Transforming Growth Factor beta
• Gata1 protein, mouse
• Gata2 protein, mouse

Topics

• Animals
• Humans
• Mice
• Emperipolesis (drug effects)
• GATA1 Transcription Factor (antagonists & inhibitors)
• Interleukin-8
• Megakaryocytes (metabolism)
• Neutrophils (metabolism)
• Primary Myelofibrosis (drug therapy, metabolism)
• Transforming Growth Factor beta (metabolism)