Nissim Ben Efraim AH, Eliashar R, Levi-Schaffer F. Hypoxia modulates human eosinophil function.
Clin Mol Allergy 2010;
8:10. [PMID:
20642833 PMCID:
PMC2923626 DOI:
10.1186/1476-7961-8-10]
[Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2010] [Accepted: 07/19/2010] [Indexed: 01/21/2023] Open
Abstract
Background
Eosinophils are involved in various inflammatory processes including allergic inflammation during which angiogenesis has been documented. Angiogenesis is most likely connected to the hypoxia which characterizes inflamed tissues. Eosinophils produce VEGF and are pro-angiogenic. However, to the best of our knowledge no study has been performed to verify the existence of a direct link between eosinophils, hypoxia and angiogenesis in allergic inflammation.
Objective
To characterize eosinophil function and angiogenic potential under hypoxic conditions.
Methods
Human peripheral blood eosinophils were cultured in normoxic or hypoxic conditions with or without cytokines. Viability and apoptosis were assessed by Annexin V/PI staining. Anti- or pro-apoptotic protein levels, HIF-1α levels and MAPK phosphorylation were analyzed by immunoblot analysis. Angiogenic mediator release was evaluated by ELISA.
Results
Hypoxic eosinophils were more viable than normoxic ones after up to three days. In addition in hypoxia, anti-apoptotic Bcl-XL protein levels increased more than pro-apoptotic Bax levels. Hypoxia increased VEGF and IL-8 release. In hypoxic eosinophils high levels of HIF-1α were observed, particularly in the presence of GM-CSF. MAPK, particularly ERK1/2 inhibitors, decreased hypoxia-mediated VEGF release and HIF-1α expression.
Conclusion
Eosinophils respond to hypoxia by up-regulation of survival and of some of their pro-angiogenic functions indicating a correlation between eosinophilic inflammation and angiogenesis.
Collapse