DAMAGE ASSAYS RATHER THAN BIOMARKERS OF AGING Ben Best 1 1 President, Cryonics Institute, Clinton Township, Michigan ASSERTIONS Biomarkers of aging attempt to measure biological age and thereby be a better predictor of life expectancy and future functionality than chronological age.[1] Biomarkers of aging assume a singular underlying process, often measured by multiple components. There is no singular underlying aging process or biological age. Predicting future functionality and life expectancy are distinct, such that neither can be claimed to represent biological age. Aging is multiple forms of damage. Aging is primarily damage to macromolecules: proteins, lipids, carbohydrates, mtDNA and nDNA (including telomeres). Aging damage is primarily due to ROS, RNS, sugars (glycation), radiation, pathogens, inflammatory cytokines, and accumulated toxins (metals, PCBs, dioxins, etc.). Endogenous and exogenous damaging agents can accelerate aging. Genetics can affect defenses against damage (antioxidant enzymes, heat shock proteins, etc.), damage repair, and molecular disposal & re-synthesis systems. Genetics can accelerate or decelerate aging. Most aging damage contributes to aging-associated diseases. The great majority of nonviolent, non-contagious deaths are due to aging-associated diseases. Different organs and tissues age (accumulate aging damage) at different rates. Death due to aging-associated disease will be caused by the most damage to the most vulnerable organ or tissue. Aging damage contributing to aging-associated disease is usually (but not necessarily) more organ- or tissue- specific than aging damage that does not contribute to aging-associated disease. Validating that damage is “aging damage” or proving that a defect or toxin causes an “aging phenotype” or “accelerated aging” can involve circular reasoning (petitio principii). Valid biomarkers of aging would be the only way to prove “accelerated aging”. Validating biomarkers of aging presumes a singular aging process. Extending maximum lifespan and extending mean lifespan both require damage reduction or repair. ASSERTIONS (CONTINUED)RELEVANT STUDY RESULTS (CONTINUED) Interventions that increase average lifespan, but not maximum lifespan, probably reduce aging damage. Extending maximum lifespan would require reduction in the most critical form of aging damage. Accelerated aging damage leads to accelerated mortality, but accelerated mortality is not necessarily due to accelerated aging. “Aging phenotype” features in animals with accelerated mortality does not prove “accelerated aging”. Damage assays are a key to understanding aging. Genuine animal models of accelerated aging can allow for invasive aging damage assays, and provide a model for finding non-invasive aging damage assays. Comprehensive aging damage assays can allow for ranking forms of aging damage, prioritizing interventions, and monitoring intervention effectiveness. Apoptosis and cellular senescence due to defective DNA repair enzymes cause the most extreme and general forms of accelerated aging disease. [2] LITERATURE CITED RELEVANT STUDY RESULTS Telomere length in RBCs predict life expectancy better than chronological age in Alpine swift living in the wild [13] The rate of leukocyte telomere length attrition predicts cardiovascular mortality in healthy men [14] White blood cell telomere attrition rate is accelerated in obesity and insulin resistance [15] Plasma inflammatory cytokines increase with age and are positively associated with cardiovascular mortality [16] Plasma inflammatory cytokines are significantly associated with age-related cataract [17] In normal subjects a high-fat meal elevates plasma inflammatory cytokines significantly more than a high- carbohydrate meal [18] Hypertension is the second most common cause of chronic kidney disease (after diabetes) [19] Transgenic Drosophila with decreased and increased DNA excision repair show “accelerated aging” and “decelerated aging”, respectively [20] [1] Baker,GT,…;Exp Gerontol; 23:223 (1998) [2] Best,BP;Rejuvenation Res; 12:199 (2009) [3] Sato,Y,…;Histopathology; 38:217 (2001) [4] Koschinsky,T,…;Proc Natl Acad Sci USA;94:6474 (1997) [5] Young,RP,…;Eur Respir J;30:616 (2007) [6] Loft,S,…;Carcinogenesis;13:2241 (1992) [7] Morrow,JD,…;N Eng J Med; 332:1198 (1995) [8] Pratico,D,…;J Clin Invest; 100:2028 (1997) [9] Basu,S,…;Biochem Biophys Res Commun; 288:275 (2001) [10] Derhovanessian,E,…;Curr Opin Immunol;21:440 (2009) [11] El-Domyati,M,…;Exp Dermatol;11:398 (2002) [12] Niedernhofer,LJ,…;Mech Ageing Dev;129:408 (2008) [13] Bize,P,…;Proc R Soc;276:1679 (2009) [14] Epel,ES,…;Aging;1:81 (2009) [15] Gardner,JP,…;Circulation;111:2171 (2005) [16] Bruunsgaard,H,…;Immunol Allergy Clin N Am 23:15 (2003) [17] Klein,BEK,…;Am J Ophthalmol;141:116 (2006) [18] Nappo,F,…;J Am Coll Cardiol;39:1145 (2002) [19] Libby,P,et al (Editors); Braunwald’s Heart Disease (8 th Edition); page 1037; Saunders Elsevier; 2008) [20] Symphorien,S,…;J Gerontol;58;B782 (2003) In the hippocampus of human cadavers there is significant correlation between advanced glycation end-products (AGEs) and chronological age [3] Diabetes & dietary AGEs acclerated protein cross-linking [4] Forced expiratory volume in one second ranked second only to smoking as a predictor of all-cause mortality [5] The urine of smokers contains 50% more 8OHdG (a measure of in vivo oxidative DNA damage) than the urine of nonsmokers [6] F2-Isoprostanes (the best available in vivo marker of lipid peroxidation) in the urine of smokers drops by more than one third after two weeks of smoking cessation [7] Foam cells in atherosclerotic plaque are significantly positive for F2-Isoprostanes [8] F2-Isoprostanes are significantly elevated in the urine of victims of osteoporosis (a disease vulnerable to oxidative stress) and vary inversely with bone density [9] Immunosenescence (especially low numbers of naïve CD8+ T-cells) is significantly associated with cytomegalovirus (CMV) [10] There is considerable overlap in the histopathology of skin photoaging and skin intrinsic aging [11] Victims of the tissue-specific “accelerated aging disease” xeroderma pigmentosum (defective DNA nuclear excision repair) show photoaging in skin areas exposed to light [12]