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Qin Zhang, Andre Cunha, Shu Li, Qin Hao, Vanessa Kainz, Qian Huang, Henry Wu; IL-27 regulates HIF-1α-mediated VEGFA response in macrophages of diabetic retinopathy patients and healthy individuals. Invest. Ophthalmol. Vis. Sci. 2018;59(9):2515.
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© ARVO (1962-2015); The Authors (2016-present)
Human macrophages produce vascular endothelial growth factor A (VEGFA) for angiogenesis in diabetic retinopathy (DR). The regulatory function of IL-27 on human macrophages is not well understood. In particular, the effect of IL-27 on VEGFA response in human macrophages has not been investigated.
Purified human monocytes (from healthy donors or DR patients) were stimulated with M-CSF or IL-27, with the addition of adenosine, ATP, an adenosine receptor antagonist, or a potent JAK2 inhibitor. Following stimulation in the different conditions VEGFA protein and gene level were checked by ELISA and qPCR. Adenosine level in cell culture was detected by LCMS. HIF1α was detected by Western blot and FACS. CD73 and CD39 expression was detected by FACs.
We find that IL-27 suppresses VEGFA mRNA expression as well as protein secretion by human macrophages. The synergistic action of purinergic signaling and activation of hypoxia-inducible factor 1 alpha (HIF-1a) induces VEGFA production in a positive feedback loop. IL-27 signaling in human macrophages disrupts this positive feedback loop leading to suppression of VEGFA production. Blockade of IL-27 signaling with a JAK2 inhibitor reverses this downregulatory effect on HIF-1α and partially rescues the inhibitory effect on VEGFA production. DR patient macrophages have a higher propensity to produce VEGFA and this is amplified by an in vitro challenge with the pro-inflammatory cytokine IL-1b. IL-27 suppresses VEGFA production by DR patient macrophages even in the presence of IL-1b challenge.
To the best of our knowledge, studies presented here are the first to demonstrate IL-27 can regulate VEGFA production in human macrophages. We provide evidence to support a mechanism in which IL-27 signaling regulates the expression of HIF-1a and thereby affects purinergic signaling resulting in a disruption of the positive feedback loop that drives VEGFA production in human macrophages. Lastly, IL-27 is effective in suppressing DR patient macrophages that have a heightened VEGFA response. Our novel findings shed new light on a previously unappreciated function of IL-27 and potentially open a new avenue for IL-27 and other protein therapeutics to treat ophthalmic diseases such as diabetic retinopathy.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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