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Interleukin-6 mediates neutrophil mobilization from bone marrow in pulmonary hypertension
Journal article   Open access   Peer reviewed

Interleukin-6 mediates neutrophil mobilization from bone marrow in pulmonary hypertension

Jonathan Florentin, Jingsi Zhao, Yi-Yin Tai, Sathish Babu Vasamsetti, Scott P. O'Neil, Rahul Kumar, Anagha Arunkumar, Annie Watson, John Sembrat, Grant C. Bullock, …
Cellular & molecular immunology, Vol.18(2), pp.374-384
02/01/2021
DOI: 10.1038/s41423-020-00608-1
PMCID: PMC8027442
PMID: 33420357
url
https://doi.org/10.1038/s41423-020-00608-1View
Published (Version of record) Open Access

Abstract

Myeloid cells, such as neutrophils, are produced in the bone marrow in high quantities and are important in the pathogenesis of vascular diseases such as pulmonary hypertension (PH). Although neutrophil recruitment into sites of inflammation has been well studied, the mechanisms of neutrophil egress from the bone marrow are not well understood. Using computational flow cytometry, we observed increased neutrophils in the lungs of patients and mice with PH. Moreover, we found elevated levels of IL-6 in the blood and lungs of patients and mice with PH. We observed that transgenic mice overexpressing Il-6 in the lungs displayed elevated neutrophil egress from the bone marrow and exaggerated neutrophil recruitment to the lungs, resulting in exacerbated pulmonary vascular remodeling, and dysfunctional hemodynamics. Mechanistically, we found that IL-6-induced neutrophil egress from the bone marrow was dependent on interferon regulatory factor 4 (IRF-4)-mediated CX(3)CR1 expression in neutrophils. Consequently, Cx(3)cr1 genetic deficiency in hematopoietic cells in Il-6-transgenic mice significantly reduced neutrophil egress from bone marrow and decreased neutrophil counts in the lungs, thus ameliorating pulmonary remodeling and hemodynamics. In summary, these findings define a novel mechanism of IL-6-induced neutrophil egress from the bone marrow and reveal a new therapeutic target to curtail neutrophil-mediated inflammation in pulmonary vascular disease.
Immunology Life Sciences & Biomedicine Science & Technology

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