Flavones induce neutrophil apoptosis by down‐regulation of Mcl‐1viaa proteasomal‐dependent pathway

Abstract

Neutrophil apoptosis and subsequent nonphlogistic clearance by surrounding phagocytes are key to the successful resolution of neutrophilic inflammation, with dysregulated apoptosis reported in multiple human inflammatory diseases. Enhancing neutrophil apoptosis has proresolution and anti-inflammatory effects in preclinical models of inflammation. Here we investigate the ability of the flavones apigenin, luteolin, and wogonin to induce neutrophil apoptosis in vitro and resolve neutrophilic inflammation in vivo. Human neutrophil apoptosis was assessed morphologically and by flow cytometry following incubation with apigenin, luteolin, and wogonin. All three flavones induced time- and concentration-dependent neutrophil apoptosis (apigenin, EC50=12.2 μM; luteolin, EC50=14.6 μM; and wogonin, EC50=28.9 μM). Induction of apoptosis was caspase dependent, as it was blocked by the broad-spectrum caspase inhibitor Q-VD-OPh and was associated with both caspase-3 and caspase-9 activation. Flavone-induced apoptosis was preceded by down-regulation of the prosurvival protein Mcl-1, with proteasomal inhibition preventing flavone-induced Mcl-1 down-regulation and apoptosis. The flavones abrogated the survival effects of mediators that prolong neutrophil life span, including lipoteichoic acid, peptidoglycan, dexamethasone, and granulocyte-macrophage colony stimulating factor, by driving apoptosis. Furthermore, wogonin enhanced resolution of established neutrophilic inflammation in a zebrafish model of sterile tissue injury. Wogonin-induced resolution was dependent on apoptosis in vivo as it was blocked by caspase inhibition. Our data show that the flavones induce neutrophil apoptosis and have potential as neutrophil apoptosis-inducing anti-inflammatory, proresolution agents.—Lucas, C. D., Allen, K. C., Dorward, D. A., Hoodless, L. J., Melrose, L. A., Marwick, J. A., Tucker, C. S., Haslett, C., Duffin, R., Rossi, A. G. Flavones induce neutrophil apoptosis by down-regulation of Mcl-1 via a proteasomal-dependent pathway.

The co‑treatment of metformin with flavone synergistically induces apoptosis through inhibition of PI3K/AKT pathway in breast cancer cells

“…In addition, p53 reduces Bcl-2 transcription (41). Flavones induce caspase-dependent apoptosis in A549 cells (42) and primary human neutrophils (43). Our present study showed that metformin, flavone and combination induced apoptosis by decreasing Bcl-2, increasing Bax and cleaved caspase3 protein level.…”

Proresolving Actions of Synthetic and Natural Protease Inhibitors Are Mediated by Annexin A1

“…5E). Neutrophils are exposed to inflammatory mediators at sites of inflammation that may extend their life span by delaying apoptosis (28). Because SIV induced apoptosis in vivo, in a milieu exposure to prosurvival factors, we investigated the ability of SIV to counteract the prosurvival effects of LPS.…”

“…In vitro experiments to evaluate neutrophil apoptosis Neutrophils were isolated from human peripheral blood from healthy donors (Ethics Committee of the Universidade Federal de Minas Gerais, BrazilInstitutional Review Board Project number 0319.0.203.000-11) by using histopaque gradient (Histopaque 11191 and 10771; Sigma-Aldrich) as described previously (28). Neutrophils (1 3 10 6 cells/well) were resuspended in RPMI 1640 medium, seeded in 24-well culture plates (BD Biosciences), and incubated at 37˚C in a 5% CO 2 atmosphere.…”

Wogonin Induces Eosinophil Apoptosis and Attenuates Allergic Airway Inflammation

“…The flavone wogonin (5,7-dihydroxy-8-methoxyflavone) has been proposed to have anticancer and antiinflammatory properties (18,19). Recently, we showed that flavones, including wogonin, were able to drive neutrophil apoptosis by downregulating the prosurvival Bcl-2 family member Mcl-1.…”