Pomegranate Juice Polyphenols Induce Macrophage Death via Apoptosis as Opposed to Necrosis Induced by Free Radical Generation: A Central Role for Oxidative Stress

Abstract

At high concentrations, polyphenols induce cell death, and the polyphenols-rich pomegranate juice (PJ), known for its antioxidative/antiatherogenic properties, can possibly affect cell death, including macrophage death involved in atherogenesis. In the present study, apoptotic/necrotic macrophage death was analyzed in J774A.1 macrophages and in peritoneal macrophages isolated from atherosclerotic apoE-/- mice treated with PJ. The effects of PJ were compared with those of the free radical generator 2, 2'-azobis (2-amidinopropane) dihydrochloride (AAPH). Both PJ and AAPH significantly increased J774A.1 macrophage death; however, flow cytometric and microscopic analyses using annexin V/propidium iodide revealed that PJ increased the early apoptosis of the macrophage dose dependently (up to 2.5-fold, P < 0.01), whereas AAPH caused dose-dependent increases in late apoptosis/necrosis (up to 12-fold, P < 0.001). Unlike PJ, AAPH-induced macrophage death was associated with increased intracellular oxidative stress (up to 7-fold, P < 0.001) and with lipid stress demonstrated by triglyceride accumulation (up to 3-fold, P < 0.01) and greater chromatic vesicle response to culture medium (up to 5-fold, P < 0.001). Accordingly, recombinant paraoxonase 1, which hydrolyzes oxidized lipids, attenuated macrophage death induced by AAPH, but not by PJ. Similar apoptotic and oxidative effects were found in macrophages from apoE-/- mice treated with PJ or AAPH. As macrophage apoptotic/necrotic death has considerable impact on atherosclerosis progression, these findings may provide novel mechanisms for the antiatherogenicity of PJ.

Nitro‐Oleic Acid Reduces J774A.1 Macrophage Oxidative Status and Triglyceride Mass: Involvement of Paraoxonase2 and Triglyceride Metabolizing Enzymes

“…These effects were augmented in MPM from PON2-deficient mice under high glucose conditions [52]. Similarly, treatment of J774A.1 with AAPH was found to increase macrophage ROS generation and the accumulation of triglycerides [45]. Various anti-oxidants were shown to attenuate the accumulation of triglycerides, including recombinant PON2, the NADPH-oxidase inhibitor apocynin, or pomegranate polyphenols; all inhibited the enhanced rate of triglyceride biosynthesis and the activation of DGAT1 under the above prooxidative conditions [44,48,52].…”

“…Also, in mouse peritoneal macrophages (MPM) isolated from PON2-deficient mice, triglycerides accumulated as a result of enhanced triglyceride biosynthesis rate [44]. Similarly, treatment of macrophages with exogenous pro-oxidants such as the free radical generator 2,2′-amidinopropane hydrochloride (AAPH), silicon dioxide nanoparticles, or exposure to cigarette smoke were shown to impair the metabolism of triglycerides or cholesterol, leading to their accumulation in macrophages [44][45][46][47]. Accordingly, the above effects were blunted by treatment of macrophages with endogenous anti-oxidants (PON2, catalase or superoxide dismutase) or with exogenous anti-oxidants (N-acetylcysteine or pomegranate polyphenols) [43-45, 47, 48].…”

Effects of Pomegranate (Punica Granatum L.) Seed and Peel Methanolic Extracts on Oxidative Stress and Lipid Profile Changes Induced by Methotrexate in Rats

“…1 PJ is a major source of soluble polyphenols such as gallic acid, ellagic acid, punicalagin and quercetin. 25 Further, a research has demonstrated that polyphenols possess powerful antioxidant properties, which represent the most likely mechanism responsible for the protective benefits of pomegranate. 8 The antioxidant capacity of pomegranate has been shown to be 3 times higher than that of red wine or green tea infusion.…”

Pu-erh Tea Ameliorates Atherosclerosis Associated with Promoting Macrophage Apoptosis by Reducing NF-κB Activation in ApoE Knockout Mice

“…As mentioned above, pu-erh tea is comprised of a variety of biochemical ingredients. Polyphenols, the main contents of pu-erh tea, were reported to induce the apoptosis of macrophages in both macrophage cell line and in macrophages isolated from atherosclerotic ApoE null mice [31]. Therefore, we assume that the function of pu-erh tea on atherosclerosis is mainly dependent on polyphenols, but the mechanism has not been examined yet.…”