- Email: [email protected]
Beyond and behind the fingerprints of oxidative stress in age-related diseases: Secrets of successful aging
Archives of Biochemistry and Biophysics 595 (2016) 50e53
Contents lists available at ScienceDirect
Archives of Biochemistry and Biophysics journal homepage: www.elsevier.com/locate/yabbi
Beyond and behind the fingerprints of oxidative stress in age-related diseases: Secrets of successful aging M. Cristina Polidori a, *, Marlies Scholtes b a b
Ageing Clinical Research, Dpt. II Internal Medicine, University Hospital of Cologne, Cologne, Germany Institute of Biochemistry and Molecular Biology I, Heinrich-Heine University Düsseldorf, Düsseldorf, Germany
a r t i c l e i n f o
a b s t r a c t
Article history: Received 12 June 2015 Accepted 13 June 2015
Several years after the first publication of the definition of oxidative stress by Helmut Sies, this topic is still focus of a large body of attention and research in the field of aging, neurodegeneration and disease prevention. The conduction of clinical and epidemiological research without a solid biochemical rationale has led to largely frustrating results without being able to disprove the oxidative stress hypothesis. The present work is dedicated to Helmut Sies and describes the successful scientific approach to benchto-bedside (-to-behavior) oxidative stress clinical research. © 2015 Elsevier Inc. All rights reserved.
1. Introduction In an elegant abstract of an elegant review, “The metabolic role of aldehydes, hydroperoxides, and quinones […] investigated with emphasis on oxidative transitions involving oxygen free radicals and associated with enzymatic activities” was mentioned in light of “[…] enzyme-catalyzed disproportionation of hydroperoxides as a source of a potent oxidizing equivalent, singlet molecular oxygen […], cytotoxicity of quinones […]” and “[…] monitoring changes in quinone metabolism […]” [1]. In the same year, Helmut Sies published the definition of “oxidative stress” [2] and reviewed its biochemistry one year later [3]. In only one decade, the PubMed citations on this subject would sharply increase to several hundred. No wonder that as a post-doc student of Balz Frei at Boston University in the mid-nineties, one would be very interested in hearing “if you want to go back to Europe and pursue your academic career in the field oxidative stress, you need to go to Professor Sies in Düsseldorf”. One would be really excited about the idea of working in the Institute of the pioneer of the concept of oxidative stress. This brief introduction is mandatory to know premise, dynamics and development of research at the Institute of Biochemistry and Molecular Biology I e formerly Institute of Physiological Chemistry e under the Direction of Professor Sies in Düsseldorf, Heinrich-Heine University. The faith of any student, post-doc, and habilitation
* Corresponding author. Ageing Clinical Research, Dpt. II Internal Medicine, University Hospital of Cologne, Kerpener Str 62, 50937 Cologne, Germany. E-mail address: [email protected] (M.C. Polidori). http://dx.doi.org/10.1016/j.abb.2015.06.021 0003-9861/© 2015 Elsevier Inc. All rights reserved.
candidate would be to be encouraged “with gentle force” to complete their thesis within due, good time. This is not only the reason why such a large number of people from all over the world completed their studies successfully at Helmut's Institute, but also the explanation for the development of a number of wellrecognized oxidative stress-related research groups led by motivated postdocs working under good mentoring first and independently afterwards (see this issue). For those young researchers happening to perform an academic stay at Helmut's Institute, the work in a really international place, the exposure to high-level critical scientific thinking and exchange as well as the resulting publications in high ranking magazines were a certainty. The understanding of the potential of better exploring the unbalance between oxidants and antioxidants in aging and agerelated diseases has been the first impulse for a series of human studies aiming at the identification of antioxidant profiles in specific diseases. In previous studies, free radical-induced lipid peroxidation and DNA oxidation as assessed by the state-of-the-art methods available had been shown to play an important role in subarachnoid hemorrhage [4], iron overload [5], ischemic stroke [6], Huntington's disease [7] and Alzheimer's disease [8]. A clear relationship was getting delineated between oxidative stress and the pathophysiological mechanisms of neurodegeneration which is still under considerable attention [9]. Our group during the “Sies' years” focused its research on three main aspects related to the importance of redox alterations in aging: the relationship between antioxidant defense systems and lifestyle habits in humans; the bioavailability and metabolism of lipophilic antioxidants including their non-antioxidant actions; and the importance of not splitting
M.C. Polidori, M. Scholtes / Archives of Biochemistry and Biophysics 595 (2016) 50e53
the axis antioxidant-biomarker of oxidative stress e clinical marker of disease when translating bench to bedside data, particularly in advanced age. 2. The challenge of oxidative stress science in older humans Helmut as a mentor always had time and an open ear for the worries and problems of his staff and students. The door of his office was (almost) always open. By always pointing out at the resources of results rather than at their frustrating, p-less side, a solid way was paved for the performance of well-controlled clinical studies in which rigorous inclusion and exclusion criteria would guarantee interpretability and reliability of results. With the aim of exploring profiles of oxidant/antioxidant balance in humans of different ages and with different lifestyle habits on one side and with specific age-related diseases on the other side, the unavoidable premises would be in any clinical study from Helmut Sies' group that 1) free radicals cannot be measured in any biological fluid no matter how promising any new method would be presented; 2) total antioxidant activity in plasma does not allow the identification of adequacy of the antioxidant defense system due to intrinsic methodological limitations and to the strongly influence exerted by the presence and levels of non-typical antioxidant molecules; that 3) like with antimicrobials, the goal of studies on redox imbalance should not be to completely neutralize oxidants, being these important physiological actors of health; and 4) that “anti-aging” is still a poorly defined concept unfortunately more used for attractive commercial purposes rather than for scientific goals e probably like the current “rejuvenation” concept. As a clinician working in a strong basic science environment, these pillars would be critical to ensure a secure approach to the older patient exposed to a large amount of confounding, even mediatic, medical information. The above cited “principles” accompanied also studies of chemistry, metabolism and antioxidant behavior in healthy humans of different ages and with different lifestyle habits. Research on antioxidant micronutrient plasma levels and antioxidant enzyme activities in healthy centenarians led to the observations that age does not seem to be the main contributor to antioxidant depletion, as centenarians do show higher plasma vitamin A and E levels e but not of other antioxidants e compared to younger subjects [10e12]. This was confirmed afterwards in other studies also from other groups and by us showing that dietary habits are major determinants of the plasma antioxidant status in healthy elderly subjects [13] and that levels of circulating antioxidants can be increased by a nutritional intervention following the concept of “five-a-day” [14]. Lipophilic antioxidants were extensively studied, also in groundbreaking European actions, as far as bioavailability, metabolism, methods of analytical measurement and their outcome implications in human studies are concerned [15e20]. The observation from our group, among others, of a biological antioxidant activity of vitamin E metabolites with potential implications in human health gained considerable attention and our results were presented at several important scientific meetings including a special workshop organized by Bruce Ames at Berkley on the terrible September 11th, 2001. As the evidence-based approach is in any case difficult to apply to aging and geriatric medicine, the problems intrinsic to oxidative stress research due to its systemic nature are not new when designing studies in older humans. A few key strategies to overcome the obstacles related to patient heterogeneity and oxidative stress confounders include the application of rigorous inclusion and exclusion criteria and the use of state-of-the-art methods of measurements of antioxidants and bioproducts of oxidative stress. This might sound obvious, but in fact aging and redox/antioxidant/
51
lifestyle research are all threatened by methodological limitations. Even in the fortunate case of best-method-scenario, the interpretability of results is highly dependent on the multifactorial nature of the aging process as well as on the influence exerted by a multitude of endogenous and exogenous factors on redox status, virtually impossible to be controlled for in their totality. Putting together the bench-to-bedside results collected in the eighties and nineties of the last century, it became clear that a proper conclusion on the status of the antioxidant system of the aging human organism with and without disease would only be possible when antioxidant profiles are identified through the analysis of their major water-soluble and lipophilic components by the best available methods and are used in conjunction with other parameters of the oxidative stress status [21]. This kind of objective information coupled with very selective study inclusion criteria was indeed obtained in a series of investigations in which for each age-related disease in question the association between a reliable, reproducible, non-invasive and standardized clinical marker of disease and markers of the oxidant-antioxidant balance of the organism would be explored. This way a relationship could be established between antioxidant profiles and glycemic control in older patients with type 2 diabetes mellitus [22], between antioxidant profiles and left ventricular ejection fraction of the heart in older patients with congestive heart failure [23], between antioxidant profiles and carotid or iliofemoral intima-media thickness in older patients with atherosclerosis [24], as well as between antioxidant profiles and neurological impairment in older stroke patients [25]. In general, one would basically be able to perform any study on oxidative stress at Helmut's lab. He always thinks positively, looks up and has a great sense of humor. Regarding the latter, his faithful secretary over many successful years recalls of having once spilt coffee all over an important visiting professor from Japan, which Helmut commented with a smile: Well, this is what we would call a German Coffee Ceremony. One true highlight of the year was the annual Carneval celebration Party. When foreign member of staff asked about the strange Carneval tradition and celebrations of the region, Helmut asked: Is there anything we can do and show them? Yes we can.
That is when legendary annual Carneval Party was born and carried out each year for more than ten years. The foreign members of staff must have thought it strange that the ever so correct and well behaved Germans could dress up in silly costumes on the day and sing and dance all day. They soon learned and joined in the celebrations, which were again an opportunity to get together and celebrate at ease away from the daily lab worries. And back to the worries, the research trajectory in the field of oxidative stress and age-related disease was getting more and more challenging: the main question would arise about the possibility of significantly influencing, and how, and with which implications for health, the profiles of antioxidants. This is still a huge point in human health, as it was clear from the beginning that, even if getting significant
52
M.C. Polidori, M. Scholtes / Archives of Biochemistry and Biophysics 595 (2016) 50e53
increases in plasma concentrations of antioxidant micronutrients through nutritional interventions [14] or smoking cessation [26], a decrease in biomarkers of free radical damage to biological molecules would not be the typical associated observation. Here also, however, such apparently frustrating result is to be seen as a starting point for the design of steadily improving clinical study design. During the past recent years, in fact, the reasons for largely negative observations from intervention studies with antioxidants have been delineated. Neurodegeneration is a hallmark example for the need of exact requirements in study design to explore presence and effects of antioxidant micronutrient depletion [27]. Through a continuous support including appreciation for not giving up, our research at Helmut's Institute led to the preliminary conclusion, in agreement with other groups, of a chronological primacy of oxidative stress in the development of Alzheimer's disease (AD) [28] as strongly suggested by the fact that antioxidants are similarly depleted in AD and in its prophase, mild cognitive impairment (MCI), independent from dietary intake and comorbidities [29]. The reasons for frustrating results in oxidative stress research during aging and in agerelated diseases are related, as mentioned above, to the intrinsic multifactorial nature of aging and oxidative stress conditions; however, a large amount of study limitations have been identified during the course of the years which render mandatory to keep improving and studying this field, especially when concerning AD and neurodegeneration [30,31]. One could go ahead and write pages and pages on the tight boundary between human and scientific hallmarks of working with Helmut. Being an Editorial Board Member of a number of high ranking international magazines Helmut was always intensely involved in high level editorial activities. Editorial work involves a lot of correspondence and at a time when no email was available it had to be done by fax. Sometimes this involved sending 20 pages and more to Helmut's Hotel when he was attending meetings overseas. He complained once that he had received a 2 m long fax message which he had to cut to page size with whatever cutting tool was available to him at the time e a pair of nail scissors had to do the job in the end. Helmut's Ph.D. students and Postdocs were steadily encouraged and supported to attend international congresses and meetings to get them into the international circle of scientists which was always highly appreciated and so important for their future careers. He also initiated a large number of local seminars and meetings with other departments of the Medical Faculty and the North-RhineWestfalian Academy of Science. As President of the Academy he encouraged and let members of his staff take part in various high ranking meeting activities. If on one hand this would strongly influence the development of a very demanding approach as far as science is concerned, on the other hand this straightforward way of doing research was and is always coupled with Helmut's rare ability of communicating with anybody no matter what rank or background people have. He is a true ‘Weltmensch’ and excellent one in a million boss and of course a passionate outstanding scientist. In summary, feedback and feedforward, science and humanity, rigorousness and flexibility are impossible to separate if you want to get a closer collaboration with Professor Sies. We are proud and honored to have been subject of his attention and support and sure got enough from him to transmit with enthusiasm to the next generation of young researchers.
References [1] E. Cadenas, H. Sies, Oxidative stress: excited oxygen species and enzyme activities, Adv. Enzyme Regul. 23 (1985) 217e237. [2] H. Sies, Oxidative stress: introductory remarks, in: H. Sies (Ed.), Oxidative
Stress, Academic Press, London, 1985, pp. 1e8. [3] Sies, Biochemistry of oxidative stress, Angew. Chem. Int. Ed. Engl. 25 (1986) 1058e1071. [4] M.C. Polidori, B. Frei, G. Rordorf, C.S. Ogilvy, W.J. Koroshetz, M.F. Beal, Increased levels of plasma cholesteryl ester hydroperoxides in patients with subarachnoid hemorrhage, Free Radic. Biol. Med. 23 (1997) 762e767. [5] T.M. Berger, M.C. Polidori, A. Dabbagh, P.J. Evans, B. Halliwell, J.D. Morrow, L. Jackson Roberts II, B. Frei, Antioxidant activity of vitamin C in ironoverloaded human plasma, J. Biol. Chem. 272 (1997) 15656e15660. [6] M.C. Polidori, B. Frei, A. Cherubini, G. Nelles, G. Rordorf, J.F. Keaney Jr., L. Schwamm, Koroshetz WJ. Mecocci, M.F. Beal, Increased plasma levels of lipid hydroperoxides in patients with ischemic stroke, Free Radic. Biol. Med. 25 (1998) 561e567. [7] M.C. Polidori, P. Mecocci, S.E. Browne, U. Senin, M.F. Beal, Oxidative damage to mitochondrial DNA in Huntington's disease parietal cortex, Neurosci. Lett. 272 (1999) 53e56. [8] M.C. Polidori, P. Mecocci, Plasma susceptibility to free radical-induced antioxidant consumption and lipid peroxidation is increased in very old subjects with Alzheimer's disease. [9] A.E. Moneim, Oxidant/antioxidant imbalance and the risk of Alzheimer's disease, Curr. Alzh Res. 12 (2015) 335e349. G.J. McBean, M. Aslan, H.R. Griffiths, R.C. Torrao, Thiol redox homeostasis in neurodegenerative disease, Redox Biol 5 (2015) 186e194. [10] P. Mecocci, M.C. Polidori, L. Troiano, A. Cherubini, R. Cecchetti, G. Pini, M. Straatmann, D. Monti, W. Stahl, H. Sies, C. Franceschi, U. Senin, Plasma antioxidants and longevity: a study on healthy centenarians, Free Radic. Biol. Med. 28 (2000) 1243e1248. [11] M.C. Polidori, P. Mecocci, A. Reimann, A. Cherubini, R. Cecchetti, K. Briviba, W. Stahl, H. Sies, U. Senin, Plasma lipid peroxidation and vitamin C status in healthy centenarians, J. Am. Geriatr. Soc. 47 (1999) 1038e1039. [12] M.C. Polidori, A. Cherubini, W. Stahl, L. Troiano, C. Franceschi, U. Senin, H. Sies, P. Mecocci, Extreme longevity: the role of antioxidant enzymes, vitamins, and micronutrients, in: K. Nesaretnam, L. Packer, (Eds.), Micronutrients and Health: Molecular Biological Mechanisms. AOCS Press, Champaign, IL, pp. 254e262, (Chapter 24). [13] T. Anlasik, H. Sies, H.R. Griffiths, W. Stahl, M.C. Polidori, Dietary habits are major determinants of the plasma antioxidant status in healthy elderly subjects, Br. J. Nutr. 94 (2005) 639e642. [14] M.C. Polidori, J.C. Carrillo, P.E. Verde, H. Sies, H. Siegrist, W. Stahl, Plasma micronutrient status is improved after a 3-month dietary intervention with 5 daily portions of fruits and vegetables: implications for optimal antioxidant levels, Nutr. J. 10 (2009) 8e10. €rtner, [15] W. Stahl, H. van den Berg, J. Arthur, A. Bast, J. Dainty, R.M. Faulks, C. Ga G. Haenen, P. Hollmann, B. Holst, F.J. Kelly, M.C. Polidori, C.C. Rice-Evans, S. Southon, T. van Vliet, J. Vina-Ribes, G. Williamson, S.B. Astley, in: S.B. Astley, D.G. Lindsay (Eds.), Bioavailability and Metabolism. Molecular Aspects of Medicine, 23, 2002, pp. 39e100. Special Issue on European Research on the Functional Effects of Dietary Antioxidants (EUROFEDA QLK1-1999-00179). [16] O. Aust, H. Sies, W. Stahl, M.C. Polidori, Analysis of lipophilic antioxidants in human serum and tissues: tocopherols and carotenoids, J. Chromatogr. A 936 (2001) 83e93. [17] W. Stahl, N. Ale-Agha, M.C. Polidori, Non-antioxidant properties of carotenoids, Biol. Chem. 383 (2002) 553e558. [18] A. Betancor-Fernandez, H. Sies, W. Stahl, M.C. Polidori, In vitro antioxidant activity of 2,5,7,8-tetrametyl-2-(20 -carboxyethyl)-6-hydroxychroman (aCEHC), a vitamin E metabolite, Free Radic. Res. 36 (2002) 915e921. [19] D. Radosavac, P. Graf, M.C. Polidori, H. Sies, W. Stahl, Tocopherol metabolites 2,5,7,8-tetrametyl-2-(20 -carboxyethyl)-6-hydroxychroman (a-CEHC) and 2,7,8-trimetyl-2-(20 -carboxyethyl)-6-hydroxychroman (g-CEHC) in human serum after a single dose of natural vitamin E, Eur. J. Nutr. 41 (2002) 119e124. [20] M.C. Polidori, H. Sies, W. Stahl, R. Brigelius-Flohe, E. Vitamin, Metabolism and Biological Activity of Metabolic Products, The Encyclopedia of vitamin E, 2007 (Chapter 2). [21] M.C. Polidori, W. Stahl, O. Eichler, I. Niestroj, H. Sies, Profiles of antioxidants in human plasma, Free Radic. Biol. Med. 30 (2001) 456e462. [22] M.C. Polidori, P. Mecocci, W. Stahl, B. Parente, R. Cecchetti, A. Cherubini, P. Cao, H. Sies, U. Senin, Plasma levels of lipophilic antioxidants in very old patients with type 2 diabetes, Diabetes Met. Res. Rev. 16 (2000) 15e19. [23] M.C. Polidori, K. Savino, G. Alunni, M. Freddio, U. Senin, H. Sies, W. Stahl, P. Mecocci, Plasma lipophilic antioxidants and malondialdehyde in congestive heart failure patients: relationship to disease severity, Free Radic. Biol. Med. 32 (2002) 148e152. , B. Parente, E. Mariani, R. Cecchetti, Y. Yao, H. Sies, [24] M.C. Polidori, D. Pratico P. Cao, P. Mecocci, W. Stahl, Elevated lipid peroxidation biomarkers and low antioxidant status in atherosclerotic patients with increased carotid or iliofemoral intima-media thickness, J. Invest. Med. 55 (2007) 163e167. [25] M.C. Polidori, A. Cherubini, W. Stahl, U. Senin, H. Sies, P. Mecocci, Plasma carotenoid and malondialdehyde in ischemic stroke patients: relationship to early outcome, Free Radic. Res. 36 (2002) 265e268. [26] M.C. Polidori, P. Mecocci, W. Stahl, H. Sies, Cigarette smoking cessation increases plasma levels of several antioxidant micronutrients and improves resistance towards oxidative challenge, Br. J. Nutr. 90 (2003) 147e150. , [27] H. Sies, Oxidative stress: impact in neuroscience research, in: D. Pratico P. Mecocci (Eds.), Studies on Alzheimer's Disease. Oxidative Stress in Applied Basic Research and Clinical Practice, Springer, New York, 2013, pp. 3e7
M.C. Polidori, M. Scholtes / Archives of Biochemistry and Biophysics 595 (2016) 50e53 (Chapter 1). [28] M. Smith, A. Nunomura, H.G. Lee, X. Zhu, P.I. Moreira, J. Avila, G. Perry, Chronological primacy of oxidative stress in Alzheimer's disease, Neurobiol. Aging 26 (2005) 579e580. [29] P. Rinaldi, M.C. Polidori, A. Metastasio, A. Cherubini, R. Cecchetti, U. Senin, P. Mecocci, Plasma antioxidants are similarly depleted in Mild Cognitive Impairment and Alzheimer disease, Equal contributors, Neurobiol. Aging 24
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(2003) 915e919. [30] M.C. Polidori, G. Nelles, Antioxidant clinical trials in mild cognitive impairment and Alzheimer's disease e challenges and perspectives, Curr. Pharm. Des. 20 (2014) 3083e3092. [31] M.C. Polidori, R.J. Schulz, Nutritional contributions to dementia prevention: main issues on antioxidant micronutrients, Genes. Nutr. 9 (2014) 382.
Contents lists available at ScienceDirect
Archives of Biochemistry and Biophysics journal homepage: www.elsevier.com/locate/yabbi
Beyond and behind the fingerprints of oxidative stress in age-related diseases: Secrets of successful aging M. Cristina Polidori a, *, Marlies Scholtes b a b
Ageing Clinical Research, Dpt. II Internal Medicine, University Hospital of Cologne, Cologne, Germany Institute of Biochemistry and Molecular Biology I, Heinrich-Heine University Düsseldorf, Düsseldorf, Germany
a r t i c l e i n f o
a b s t r a c t
Article history: Received 12 June 2015 Accepted 13 June 2015
Several years after the first publication of the definition of oxidative stress by Helmut Sies, this topic is still focus of a large body of attention and research in the field of aging, neurodegeneration and disease prevention. The conduction of clinical and epidemiological research without a solid biochemical rationale has led to largely frustrating results without being able to disprove the oxidative stress hypothesis. The present work is dedicated to Helmut Sies and describes the successful scientific approach to benchto-bedside (-to-behavior) oxidative stress clinical research. © 2015 Elsevier Inc. All rights reserved.
1. Introduction In an elegant abstract of an elegant review, “The metabolic role of aldehydes, hydroperoxides, and quinones […] investigated with emphasis on oxidative transitions involving oxygen free radicals and associated with enzymatic activities” was mentioned in light of “[…] enzyme-catalyzed disproportionation of hydroperoxides as a source of a potent oxidizing equivalent, singlet molecular oxygen […], cytotoxicity of quinones […]” and “[…] monitoring changes in quinone metabolism […]” [1]. In the same year, Helmut Sies published the definition of “oxidative stress” [2] and reviewed its biochemistry one year later [3]. In only one decade, the PubMed citations on this subject would sharply increase to several hundred. No wonder that as a post-doc student of Balz Frei at Boston University in the mid-nineties, one would be very interested in hearing “if you want to go back to Europe and pursue your academic career in the field oxidative stress, you need to go to Professor Sies in Düsseldorf”. One would be really excited about the idea of working in the Institute of the pioneer of the concept of oxidative stress. This brief introduction is mandatory to know premise, dynamics and development of research at the Institute of Biochemistry and Molecular Biology I e formerly Institute of Physiological Chemistry e under the Direction of Professor Sies in Düsseldorf, Heinrich-Heine University. The faith of any student, post-doc, and habilitation
* Corresponding author. Ageing Clinical Research, Dpt. II Internal Medicine, University Hospital of Cologne, Kerpener Str 62, 50937 Cologne, Germany. E-mail address: [email protected] (M.C. Polidori). http://dx.doi.org/10.1016/j.abb.2015.06.021 0003-9861/© 2015 Elsevier Inc. All rights reserved.
candidate would be to be encouraged “with gentle force” to complete their thesis within due, good time. This is not only the reason why such a large number of people from all over the world completed their studies successfully at Helmut's Institute, but also the explanation for the development of a number of wellrecognized oxidative stress-related research groups led by motivated postdocs working under good mentoring first and independently afterwards (see this issue). For those young researchers happening to perform an academic stay at Helmut's Institute, the work in a really international place, the exposure to high-level critical scientific thinking and exchange as well as the resulting publications in high ranking magazines were a certainty. The understanding of the potential of better exploring the unbalance between oxidants and antioxidants in aging and agerelated diseases has been the first impulse for a series of human studies aiming at the identification of antioxidant profiles in specific diseases. In previous studies, free radical-induced lipid peroxidation and DNA oxidation as assessed by the state-of-the-art methods available had been shown to play an important role in subarachnoid hemorrhage [4], iron overload [5], ischemic stroke [6], Huntington's disease [7] and Alzheimer's disease [8]. A clear relationship was getting delineated between oxidative stress and the pathophysiological mechanisms of neurodegeneration which is still under considerable attention [9]. Our group during the “Sies' years” focused its research on three main aspects related to the importance of redox alterations in aging: the relationship between antioxidant defense systems and lifestyle habits in humans; the bioavailability and metabolism of lipophilic antioxidants including their non-antioxidant actions; and the importance of not splitting
M.C. Polidori, M. Scholtes / Archives of Biochemistry and Biophysics 595 (2016) 50e53
the axis antioxidant-biomarker of oxidative stress e clinical marker of disease when translating bench to bedside data, particularly in advanced age. 2. The challenge of oxidative stress science in older humans Helmut as a mentor always had time and an open ear for the worries and problems of his staff and students. The door of his office was (almost) always open. By always pointing out at the resources of results rather than at their frustrating, p-less side, a solid way was paved for the performance of well-controlled clinical studies in which rigorous inclusion and exclusion criteria would guarantee interpretability and reliability of results. With the aim of exploring profiles of oxidant/antioxidant balance in humans of different ages and with different lifestyle habits on one side and with specific age-related diseases on the other side, the unavoidable premises would be in any clinical study from Helmut Sies' group that 1) free radicals cannot be measured in any biological fluid no matter how promising any new method would be presented; 2) total antioxidant activity in plasma does not allow the identification of adequacy of the antioxidant defense system due to intrinsic methodological limitations and to the strongly influence exerted by the presence and levels of non-typical antioxidant molecules; that 3) like with antimicrobials, the goal of studies on redox imbalance should not be to completely neutralize oxidants, being these important physiological actors of health; and 4) that “anti-aging” is still a poorly defined concept unfortunately more used for attractive commercial purposes rather than for scientific goals e probably like the current “rejuvenation” concept. As a clinician working in a strong basic science environment, these pillars would be critical to ensure a secure approach to the older patient exposed to a large amount of confounding, even mediatic, medical information. The above cited “principles” accompanied also studies of chemistry, metabolism and antioxidant behavior in healthy humans of different ages and with different lifestyle habits. Research on antioxidant micronutrient plasma levels and antioxidant enzyme activities in healthy centenarians led to the observations that age does not seem to be the main contributor to antioxidant depletion, as centenarians do show higher plasma vitamin A and E levels e but not of other antioxidants e compared to younger subjects [10e12]. This was confirmed afterwards in other studies also from other groups and by us showing that dietary habits are major determinants of the plasma antioxidant status in healthy elderly subjects [13] and that levels of circulating antioxidants can be increased by a nutritional intervention following the concept of “five-a-day” [14]. Lipophilic antioxidants were extensively studied, also in groundbreaking European actions, as far as bioavailability, metabolism, methods of analytical measurement and their outcome implications in human studies are concerned [15e20]. The observation from our group, among others, of a biological antioxidant activity of vitamin E metabolites with potential implications in human health gained considerable attention and our results were presented at several important scientific meetings including a special workshop organized by Bruce Ames at Berkley on the terrible September 11th, 2001. As the evidence-based approach is in any case difficult to apply to aging and geriatric medicine, the problems intrinsic to oxidative stress research due to its systemic nature are not new when designing studies in older humans. A few key strategies to overcome the obstacles related to patient heterogeneity and oxidative stress confounders include the application of rigorous inclusion and exclusion criteria and the use of state-of-the-art methods of measurements of antioxidants and bioproducts of oxidative stress. This might sound obvious, but in fact aging and redox/antioxidant/
51
lifestyle research are all threatened by methodological limitations. Even in the fortunate case of best-method-scenario, the interpretability of results is highly dependent on the multifactorial nature of the aging process as well as on the influence exerted by a multitude of endogenous and exogenous factors on redox status, virtually impossible to be controlled for in their totality. Putting together the bench-to-bedside results collected in the eighties and nineties of the last century, it became clear that a proper conclusion on the status of the antioxidant system of the aging human organism with and without disease would only be possible when antioxidant profiles are identified through the analysis of their major water-soluble and lipophilic components by the best available methods and are used in conjunction with other parameters of the oxidative stress status [21]. This kind of objective information coupled with very selective study inclusion criteria was indeed obtained in a series of investigations in which for each age-related disease in question the association between a reliable, reproducible, non-invasive and standardized clinical marker of disease and markers of the oxidant-antioxidant balance of the organism would be explored. This way a relationship could be established between antioxidant profiles and glycemic control in older patients with type 2 diabetes mellitus [22], between antioxidant profiles and left ventricular ejection fraction of the heart in older patients with congestive heart failure [23], between antioxidant profiles and carotid or iliofemoral intima-media thickness in older patients with atherosclerosis [24], as well as between antioxidant profiles and neurological impairment in older stroke patients [25]. In general, one would basically be able to perform any study on oxidative stress at Helmut's lab. He always thinks positively, looks up and has a great sense of humor. Regarding the latter, his faithful secretary over many successful years recalls of having once spilt coffee all over an important visiting professor from Japan, which Helmut commented with a smile: Well, this is what we would call a German Coffee Ceremony. One true highlight of the year was the annual Carneval celebration Party. When foreign member of staff asked about the strange Carneval tradition and celebrations of the region, Helmut asked: Is there anything we can do and show them? Yes we can.
That is when legendary annual Carneval Party was born and carried out each year for more than ten years. The foreign members of staff must have thought it strange that the ever so correct and well behaved Germans could dress up in silly costumes on the day and sing and dance all day. They soon learned and joined in the celebrations, which were again an opportunity to get together and celebrate at ease away from the daily lab worries. And back to the worries, the research trajectory in the field of oxidative stress and age-related disease was getting more and more challenging: the main question would arise about the possibility of significantly influencing, and how, and with which implications for health, the profiles of antioxidants. This is still a huge point in human health, as it was clear from the beginning that, even if getting significant
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M.C. Polidori, M. Scholtes / Archives of Biochemistry and Biophysics 595 (2016) 50e53
increases in plasma concentrations of antioxidant micronutrients through nutritional interventions [14] or smoking cessation [26], a decrease in biomarkers of free radical damage to biological molecules would not be the typical associated observation. Here also, however, such apparently frustrating result is to be seen as a starting point for the design of steadily improving clinical study design. During the past recent years, in fact, the reasons for largely negative observations from intervention studies with antioxidants have been delineated. Neurodegeneration is a hallmark example for the need of exact requirements in study design to explore presence and effects of antioxidant micronutrient depletion [27]. Through a continuous support including appreciation for not giving up, our research at Helmut's Institute led to the preliminary conclusion, in agreement with other groups, of a chronological primacy of oxidative stress in the development of Alzheimer's disease (AD) [28] as strongly suggested by the fact that antioxidants are similarly depleted in AD and in its prophase, mild cognitive impairment (MCI), independent from dietary intake and comorbidities [29]. The reasons for frustrating results in oxidative stress research during aging and in agerelated diseases are related, as mentioned above, to the intrinsic multifactorial nature of aging and oxidative stress conditions; however, a large amount of study limitations have been identified during the course of the years which render mandatory to keep improving and studying this field, especially when concerning AD and neurodegeneration [30,31]. One could go ahead and write pages and pages on the tight boundary between human and scientific hallmarks of working with Helmut. Being an Editorial Board Member of a number of high ranking international magazines Helmut was always intensely involved in high level editorial activities. Editorial work involves a lot of correspondence and at a time when no email was available it had to be done by fax. Sometimes this involved sending 20 pages and more to Helmut's Hotel when he was attending meetings overseas. He complained once that he had received a 2 m long fax message which he had to cut to page size with whatever cutting tool was available to him at the time e a pair of nail scissors had to do the job in the end. Helmut's Ph.D. students and Postdocs were steadily encouraged and supported to attend international congresses and meetings to get them into the international circle of scientists which was always highly appreciated and so important for their future careers. He also initiated a large number of local seminars and meetings with other departments of the Medical Faculty and the North-RhineWestfalian Academy of Science. As President of the Academy he encouraged and let members of his staff take part in various high ranking meeting activities. If on one hand this would strongly influence the development of a very demanding approach as far as science is concerned, on the other hand this straightforward way of doing research was and is always coupled with Helmut's rare ability of communicating with anybody no matter what rank or background people have. He is a true ‘Weltmensch’ and excellent one in a million boss and of course a passionate outstanding scientist. In summary, feedback and feedforward, science and humanity, rigorousness and flexibility are impossible to separate if you want to get a closer collaboration with Professor Sies. We are proud and honored to have been subject of his attention and support and sure got enough from him to transmit with enthusiasm to the next generation of young researchers.
References [1] E. Cadenas, H. Sies, Oxidative stress: excited oxygen species and enzyme activities, Adv. Enzyme Regul. 23 (1985) 217e237. [2] H. Sies, Oxidative stress: introductory remarks, in: H. Sies (Ed.), Oxidative
Stress, Academic Press, London, 1985, pp. 1e8. [3] Sies, Biochemistry of oxidative stress, Angew. Chem. Int. Ed. Engl. 25 (1986) 1058e1071. [4] M.C. Polidori, B. Frei, G. Rordorf, C.S. Ogilvy, W.J. Koroshetz, M.F. Beal, Increased levels of plasma cholesteryl ester hydroperoxides in patients with subarachnoid hemorrhage, Free Radic. Biol. Med. 23 (1997) 762e767. [5] T.M. Berger, M.C. Polidori, A. Dabbagh, P.J. Evans, B. Halliwell, J.D. Morrow, L. Jackson Roberts II, B. Frei, Antioxidant activity of vitamin C in ironoverloaded human plasma, J. Biol. Chem. 272 (1997) 15656e15660. [6] M.C. Polidori, B. Frei, A. Cherubini, G. Nelles, G. Rordorf, J.F. Keaney Jr., L. Schwamm, Koroshetz WJ. Mecocci, M.F. Beal, Increased plasma levels of lipid hydroperoxides in patients with ischemic stroke, Free Radic. Biol. Med. 25 (1998) 561e567. [7] M.C. Polidori, P. Mecocci, S.E. Browne, U. Senin, M.F. Beal, Oxidative damage to mitochondrial DNA in Huntington's disease parietal cortex, Neurosci. Lett. 272 (1999) 53e56. [8] M.C. Polidori, P. Mecocci, Plasma susceptibility to free radical-induced antioxidant consumption and lipid peroxidation is increased in very old subjects with Alzheimer's disease. [9] A.E. Moneim, Oxidant/antioxidant imbalance and the risk of Alzheimer's disease, Curr. Alzh Res. 12 (2015) 335e349. G.J. McBean, M. Aslan, H.R. Griffiths, R.C. Torrao, Thiol redox homeostasis in neurodegenerative disease, Redox Biol 5 (2015) 186e194. [10] P. Mecocci, M.C. Polidori, L. Troiano, A. Cherubini, R. Cecchetti, G. Pini, M. Straatmann, D. Monti, W. Stahl, H. Sies, C. Franceschi, U. Senin, Plasma antioxidants and longevity: a study on healthy centenarians, Free Radic. Biol. Med. 28 (2000) 1243e1248. [11] M.C. Polidori, P. Mecocci, A. Reimann, A. Cherubini, R. Cecchetti, K. Briviba, W. Stahl, H. Sies, U. Senin, Plasma lipid peroxidation and vitamin C status in healthy centenarians, J. Am. Geriatr. Soc. 47 (1999) 1038e1039. [12] M.C. Polidori, A. Cherubini, W. Stahl, L. Troiano, C. Franceschi, U. Senin, H. Sies, P. Mecocci, Extreme longevity: the role of antioxidant enzymes, vitamins, and micronutrients, in: K. Nesaretnam, L. Packer, (Eds.), Micronutrients and Health: Molecular Biological Mechanisms. AOCS Press, Champaign, IL, pp. 254e262, (Chapter 24). [13] T. Anlasik, H. Sies, H.R. Griffiths, W. Stahl, M.C. Polidori, Dietary habits are major determinants of the plasma antioxidant status in healthy elderly subjects, Br. J. Nutr. 94 (2005) 639e642. [14] M.C. Polidori, J.C. Carrillo, P.E. Verde, H. Sies, H. Siegrist, W. Stahl, Plasma micronutrient status is improved after a 3-month dietary intervention with 5 daily portions of fruits and vegetables: implications for optimal antioxidant levels, Nutr. J. 10 (2009) 8e10. €rtner, [15] W. Stahl, H. van den Berg, J. Arthur, A. Bast, J. Dainty, R.M. Faulks, C. Ga G. Haenen, P. Hollmann, B. Holst, F.J. Kelly, M.C. Polidori, C.C. Rice-Evans, S. Southon, T. van Vliet, J. Vina-Ribes, G. Williamson, S.B. Astley, in: S.B. Astley, D.G. Lindsay (Eds.), Bioavailability and Metabolism. Molecular Aspects of Medicine, 23, 2002, pp. 39e100. Special Issue on European Research on the Functional Effects of Dietary Antioxidants (EUROFEDA QLK1-1999-00179). [16] O. Aust, H. Sies, W. Stahl, M.C. Polidori, Analysis of lipophilic antioxidants in human serum and tissues: tocopherols and carotenoids, J. Chromatogr. A 936 (2001) 83e93. [17] W. Stahl, N. Ale-Agha, M.C. Polidori, Non-antioxidant properties of carotenoids, Biol. Chem. 383 (2002) 553e558. [18] A. Betancor-Fernandez, H. Sies, W. Stahl, M.C. Polidori, In vitro antioxidant activity of 2,5,7,8-tetrametyl-2-(20 -carboxyethyl)-6-hydroxychroman (aCEHC), a vitamin E metabolite, Free Radic. Res. 36 (2002) 915e921. [19] D. Radosavac, P. Graf, M.C. Polidori, H. Sies, W. Stahl, Tocopherol metabolites 2,5,7,8-tetrametyl-2-(20 -carboxyethyl)-6-hydroxychroman (a-CEHC) and 2,7,8-trimetyl-2-(20 -carboxyethyl)-6-hydroxychroman (g-CEHC) in human serum after a single dose of natural vitamin E, Eur. J. Nutr. 41 (2002) 119e124. [20] M.C. Polidori, H. Sies, W. Stahl, R. Brigelius-Flohe, E. Vitamin, Metabolism and Biological Activity of Metabolic Products, The Encyclopedia of vitamin E, 2007 (Chapter 2). [21] M.C. Polidori, W. Stahl, O. Eichler, I. Niestroj, H. Sies, Profiles of antioxidants in human plasma, Free Radic. Biol. Med. 30 (2001) 456e462. [22] M.C. Polidori, P. Mecocci, W. Stahl, B. Parente, R. Cecchetti, A. Cherubini, P. Cao, H. Sies, U. Senin, Plasma levels of lipophilic antioxidants in very old patients with type 2 diabetes, Diabetes Met. Res. Rev. 16 (2000) 15e19. [23] M.C. Polidori, K. Savino, G. Alunni, M. Freddio, U. Senin, H. Sies, W. Stahl, P. Mecocci, Plasma lipophilic antioxidants and malondialdehyde in congestive heart failure patients: relationship to disease severity, Free Radic. Biol. Med. 32 (2002) 148e152. , B. Parente, E. Mariani, R. Cecchetti, Y. Yao, H. Sies, [24] M.C. Polidori, D. Pratico P. Cao, P. Mecocci, W. Stahl, Elevated lipid peroxidation biomarkers and low antioxidant status in atherosclerotic patients with increased carotid or iliofemoral intima-media thickness, J. Invest. Med. 55 (2007) 163e167. [25] M.C. Polidori, A. Cherubini, W. Stahl, U. Senin, H. Sies, P. Mecocci, Plasma carotenoid and malondialdehyde in ischemic stroke patients: relationship to early outcome, Free Radic. Res. 36 (2002) 265e268. [26] M.C. Polidori, P. Mecocci, W. Stahl, H. Sies, Cigarette smoking cessation increases plasma levels of several antioxidant micronutrients and improves resistance towards oxidative challenge, Br. J. Nutr. 90 (2003) 147e150. , [27] H. Sies, Oxidative stress: impact in neuroscience research, in: D. Pratico P. Mecocci (Eds.), Studies on Alzheimer's Disease. Oxidative Stress in Applied Basic Research and Clinical Practice, Springer, New York, 2013, pp. 3e7
M.C. Polidori, M. Scholtes / Archives of Biochemistry and Biophysics 595 (2016) 50e53 (Chapter 1). [28] M. Smith, A. Nunomura, H.G. Lee, X. Zhu, P.I. Moreira, J. Avila, G. Perry, Chronological primacy of oxidative stress in Alzheimer's disease, Neurobiol. Aging 26 (2005) 579e580. [29] P. Rinaldi, M.C. Polidori, A. Metastasio, A. Cherubini, R. Cecchetti, U. Senin, P. Mecocci, Plasma antioxidants are similarly depleted in Mild Cognitive Impairment and Alzheimer disease, Equal contributors, Neurobiol. Aging 24
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(2003) 915e919. [30] M.C. Polidori, G. Nelles, Antioxidant clinical trials in mild cognitive impairment and Alzheimer's disease e challenges and perspectives, Curr. Pharm. Des. 20 (2014) 3083e3092. [31] M.C. Polidori, R.J. Schulz, Nutritional contributions to dementia prevention: main issues on antioxidant micronutrients, Genes. Nutr. 9 (2014) 382.