The Methyl Xanthine Caffeine Inhibits DNA Damage Signaling and Reactive Species and Reduces Atherosclerosis in ApoE −/−

Objective—Caffeine remains one of the most widely consumed drugs in the world. Caffeine has multiple actions, including inhibition of the DNA damage response, and its metabolites, 1-methylxanthine and 1-methyluric acid, are potent antioxidants. Combined, these properties can exert direct effects on cell proliferation, cell death, inflammation, and DNA repair, all important processes that occur in atherosclerosis. Methods and Results—We first examined the effects of caffeine on mouse vascular smooth muscle cells. Caffeine inhibited activation of the DNA damage response regulator ataxia telangiectasia mutated protein and its downstream targets. Caffeine delayed DNA repair, had a concentration-dependent effect on cell proliferation, and protected against apoptosis. In vitro caffeine reduced oxygen consumption and decreased generation of reactive oxygen species. In vivo caffeine reduced DDR activation in vascular and nonvascular tissues, reduced reactive nitrogen species and serum levels of the DNA adduct 8-oxo-guanine, and inhibited atherogenesis in fat−fed ApoE−/− mice. Reduction in atherosclerosis was independent of the effects on blood pressure and serum lipids but associated with reduced cell proliferation and ataxia telangiectasia mutated protein activation. Conclusion—The Methyl Xanthine caffeine inhibits the DNA damage response in vitro and in vivo, regulates both cell proliferation and apoptosis after DNA damage, inhibits reactive species, and reduces atherogenesis in ApoE−/− mice

Contribution of inducible nitric oxide synthase to protein tyrosine nitration and biopterin oxidation in ApoE-null mice

Diminished nitric oxide (NO) bioactivity and enhanced peroxynitrite formation have been implicated as major contributors to atherosclerotic vascular dysfunctions. Hallmark reactions of peroxynitrite include the accumulation of 3-nitrotyrosine (3-NT) in proteins and oxidation of the NO synthase (NOS) cofactor, tetrahydrobiopterin (BH(4)). The present study sought to 1) quantify the extent to which 3-NT accumulates and BH(4) becomes oxidized in organs of apolipoprotein E-deficient (ApoE(-/-)) atherosclerotic mice and 2) determine the specific contribution of inducible NOS (iNOS) to these processes. Whereas protein 3-NT and oxidized BH(4) were undetected or near the detection limit in heart, lung, and kidney of 3-wk-old ApoE(-/-) mice or ApoE(-/-) mice fed a regular chow diet for 24 wk, robust accumulation was evident after 24 wk on a Western (atherogenic) diet. Since 3-NT accumulation was diminished 3- to 20-fold in heart, lung, and liver in ApoE(-/-) mice missing iNOS, iNOS-derived species are involved in this reaction. In contrast, iNOS-derived species did not contribute to elevated protein 3-NT formation in kidney or brain. iNOS deletion also afforded marked protection against BH(4) oxidation in heart, lung, and kidney of atherogenic ApoE(-/-) mice but not in brain or liver. These findings demonstrate that iNOS-derived species are increased during atherogenesis in ApoE(-/-) mice and that these species differentially contribute to protein 3-NT accumulation and BH(4) oxidation in a tissue-selective manner. Since BH(4) oxidation can switch the predominant NOS product from NO to superoxide, we predict that progressive NOS uncoupling is likely to drive atherogenic vascular dysfunctions

Epidemic Inflammation: Pondering Obesity

Over the past two decades, inflammation has been recognized as a major driver in the pathogenesis of several common diseases, including atherosclerosis, diabetes, cancer, and asthma. Over the same period, there has been a steep rise in the incidence of obesity, a major risk factor for these disorders. Inflammation of adipose tissue is now recognized to accompany obesity and contribute to its sequelae. Thus, whereas obesity is primarily a disorder of energy balance, it may be helpful to consider it also as a form of epidemic inflammation that predisposes to other forms of epidemic inflammation. It is a fundamental biologic challenge to understand how a positive energy balance and inflammation are linked. This work reviews evidence that reactive oxygen and nitrogen intermediates (ROI and RNI) help drive chronic inflammation in the obese. This is proposed to be a maladaptive instance of our evolved dependence on ROI and RNI for both homeostatic signaling and host defense. ROI and RNI are well suited for these seemingly contradictory dual functions by their metabolic origin, high diffusibility in water and lipid, atomic specificity, and large number of molecular targets. When we eat so much and work so little that we repeatedly generate reactive compounds at levels normally reserved for emergencies, we treat our own cells like invading microbes