Journal of Cardiology 63 (2014) 329–334
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Review
Is atherosclerosis fundamental to human aging? Lessons from ancient mummies Emily M. Clarke a , Randall C. Thompson (MD) b,c , Adel H. Allam (MD) d , L. Samuel Wann (MD) e , Guido P. Lombardi (PhD) f , M. Linda Sutherland (MD) g , James D. Sutherland (MD, MS) h , Samantha L. Cox (MD) i , Muhammad Al-Tohamy Soliman (PhD) j , Gomaa Abd el-Maksoud (PhD) k , Ibrahem Badr (PhD) l , Michael I. Miyamoto (MD, MBA) m , Bruno Frohlich (PhD) n , Abdel-Halim Nur el-din (PhD) o , Alexandre F.R. Stewart (PhD) p , Jagat Narula (MD, PhD) q , Albert R. Zink (PhD) r , Caleb E. Finch (PhD) s , David E. Michalik (DO) t,u , Gregory S. Thomas (MD, MPH) v,u,∗ a
University of California, Los Angeles, CA, USA Saint Luke’s Mid America Heart Institute, Kansas City, MO, USA c University of Missouri–Kansas City School of Medicine, Kansas City, MO, USA d Al Azhar Medical School, Cairo, Egypt e Columbia St Mary’s Healthcare, Milwaukee, WI, USA f Laboratorio de Paleopatologia, Catedra Pedro Weiss, Universidad Peruana Cayetano Heredia, Lima, Peru g Newport Diagnostic Center, Newport Beach, CA, USA h Saddleback Memorial, Laguna Hills, CA, USA i University of Cambridge, Cambridge, UK j National Research Center, Giza, Egypt k Cairo University, Cairo, Egypt l Institute of Restoration, Alexandria, Egypt m Mission Internal Medical Group, Mission Viejo, CA, USA n Smithsonian Institution, National Museum of Natural History, Washington, DC, USA o University for Science and Technology, 6th of October City, Egypt p University of Ottawa Heart Institute, Ottawa, Ontairo, Canada q Mount Sinai, New York, NY, USA r Institute for Mummies and the Iceman, European Academy, Bolzano, Italy s University of Southern California, Los Angeles, CA, USA t Miller Children’s Hospital, Long Beach, CA, USA u University of California, Irvine, CA, USA v MemorialCare Heart & Vascular Institute, Long Beach Memorial, Long Beach, CA, USA b
a r t i c l e
i n f o
Article history: Received 9 December 2013 Accepted 11 December 2013 Available online 28 February 2014 Keywords: Mummies Atherosclerosis Aging Paleopathology Coronary artery disease
a b s t r a c t Case reports from Johan Czermak, Marc Ruffer, and others a century or more ago demonstrated ancient Egyptians had atherosclerosis three millennia ago. The Horus study team extended their findings, demonstrating that atherosclerosis was prevalent among 76 ancient Egyptian mummies and among 61 mummies from each of the ancient cultures of Peru, the American Southwest, and the Aleutian Islands. These findings challenge the assumption that atherosclerosis is a modern disease caused by present day risk factors. An extensive autopsy of an ancient Egyptian teenage male weaver named Nakht found that he was infected with four parasites: Schistosoma haematobium, Taenia species, Trichinella spiralis, and Plasmodium falciparum. Modern day patients with chronic inflammatory disease such as rheumatoid arthritis, systemic lupus erythematosus, and human immunodeficiency virus experience premature atherosclerosis. Could the burden of chronic inflammatory disease have been a risk factor for atherosclerosis in these ancient cultures? The prevalence of atherosclerosis in four diverse ancient cultures is consistent with atherosclerosis being fundamental to aging. The impact of risk factors in modern times, and potentially
∗ Corresponding author at: Long Beach Memorial, 2801 Atlantic Avenue, Long Beach, CA 90806, USA. Tel.: +1 562 933 3317; fax: +1 562 933 1819. E-mail address: [email protected] (G.S. Thomas). 0914-5087/$ – see front matter © 2014 Japanese College of Cardiology. Published by Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.jjcc.2013.12.012
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in ancient times, suggests a strong gene-environmental interplay: human genes provide a vulnerability to atherosclerosis, the environment determines when and if atherosclerosis becomes manifest clinically. © 2014 Japanese College of Cardiology. Published by Elsevier Ltd. All rights reserved.
Contents Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Pioneering work . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Horus study team investigations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Funding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Conflict of interest . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Introduction Why do humans develop atherosclerosis? Is atherosclerosis fundamental to aging? Is it environmental? Chockalingam and colleagues suggest that classic risk factors account for 50% of the attributable risk of atherosclerosis [1]. Whereas Yusuf and colleagues argue risk factors account for a greater proportion of that risk [2]. One of the first to describe the importance of environmental risk, the authors of the landmark Ni-Hon-San study of 1975 demonstrated that among men of Japanese ancestry, those living in Japan (Hiroshima and Nagasaki) had the lowest incidence of coronary artery disease (CAD), with increasing incidence in those living in Honolulu, and greater still among those living in the San Francisco Bay area [3]. Atherosclerosis was found to be present in humans long before modern civilization and present day risk factors. With the help of computed tomography (CT) scanning, Murphy and colleagues demonstrated bilateral carotid calcific atherosclerosis in Otzi the Iceman, a mummy dating back to 3300 BCE [4] (BCE, Before Common Era is equivalent to BC, Before Christ). Their discovery represents the earliest documentation of atherosclerosis in humans. Pioneering work In 1852, Czermak was the first to report atherosclerosis in ancient people [5]. Autopsying the mummy of an elderly Egyptian woman in Vienna, Austria, Czermak found “multiple considerably large and calcified plaques” in her descending aorta. How does this finding fit into our current risk factor model of atherosclerosis? What risk factors would be present in this woman living along the Nile in ancient Egypt? Czermak’s findings were confirmed over fifty years later by Marc Armand Ruffer, MD, a bacteriologist who trained with Louis Pasteur. He found evidence of atherosclerosis on autopsy of multiple Egyptian mummies and mummified limbs and presented his findings at the Cairo Scientific Society in December 1908 [5,6]. Ruffer received these specimens from archeological colleagues who were asked to excavate ancient Egyptian tombs prior to the expected downstream flooding that would occur with the raising of the height of the Aswan Dam in 1907 [7]. The brittleness of dehydrated mummies had baffled previous scientist’s autopsy attempts to create slides for microscopic analysis. Ruffer, however, determined that he could slowly rehydrate the tissue by its immersion in a solution composed of an alkali salt and alcohol of varying concentrations over several days. This rehydration process allowed microtome sectioning of the fragile tissue and demonstrated calcific atherosclerosis to be common in
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Egyptian mummies. In his classic 1911 article [8], Ruffer stated, “In my opinion, therefore, the old Egyptians suffered as much as we do from arterial lesions identical with those found in the present time. Moreover, when we consider that few of the arteries examined were quite healthy, it would appear that such lesions were as frequent 3,000 years ago as they are today.” He thus concluded, “I can not therefore give any reason why arterial disease should have been so prevalent in ancient Egypt. I think, however, that it is interesting to find that it was common and that 3,000 years ago it represented the same anatomic characters as it does now.” Horus study team investigations A century following Ruffer’s landmark work [9], the Horus study team formed to evaluate the presence, extent, and potential etiologies of atherosclerosis in Egyptian and non-Egyptian ancient peoples. The team has since grown to become an international multidisciplinary group of physicians and scientists that includes the authors of this paper and other members. The team’s namesake (Horus) is one of the oldest and most significant deities of ancient Egypt. One of Horus’ many tasks was that of protector. His depiction as falcon made of gold serves as a breastplate for many royal Egyptian mummies (Fig. 1). Using a Siemens Emotion 6 slice CT scanner (Florsheim, Germany) on site at the Egyptian National Museum of Antiquities in Cairo, Egypt in February 2009, the initial Horus team imaged 20 mummies and was provided the CT scans of two others [10–12]. The CT scanner was initially donated by Siemens and the National Geographic Society to image Pharaoh Tutankhamun. The team used
Fig. 1. The deity Horus depicted as a falcon, the breastplate of Tjanefer of Thebes, and the Third intermediate period (1080–712 BCE). Mummy 9 of Thompson and colleagues [17].
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arterial calcification as a pathognomonic marker of atherosclerosis [13]. Calcification in the wall of a clearly identifiable artery was labeled diagnostic of atherosclerosis, calcification along an artery’s expected course was labeled as probable atherosclerosis [10]. To the team’s surprise, definite atherosclerosis was present in 5 and probable in 4 out of the 22 scanned mummies. A larger team returned to Egypt in May 2010 to scan 22 more mummies and review the CT scans of 8 additional mummies which were provided to them. Mummies now totaled 52. Of these, 20 had definite or probable atherosclerosis [14]. One of the mummies imaged was Princess Ahmose-Meryet-Amon, the daughter of 17th Dynasty Pharaoh Seqenenre Tao II and his wife Queen Ahhotep I. The Princess’ half brother, Ahmose I, became the first Pharaoh of the New Kingdom, the Golden Age of Egypt. When Princess AhmoseMeryet-Amon died at an estimated age of 40–45 years, she had atherosclerosis of all her major vascular beds, including her right coronary and left anterior descending coronary arteries (Fig. 2). She is thus far the earliest human in history with CAD. Prior to this discovery, the earliest recorded case of CAD was by Allen Long, MD in 1931 of Lady Teye, who lived during the 21st dynasty, circa. 1000 BCE [15]. Following the Egyptian revolution of 2011, the Horus team transitioned to imaging mummies in Lima, Peru. The work of Guido P. Lombardi, MD, MA and Clide M. Vallodolid resulted in the provision for the scanning of 51 ancient Peruvian mummies from the Museo de Sitio Puruchuco – Arturo Jimenez Borja. These ancient Peruvians lived between 900 BCE and 1500 CE on or near the coast of modern day Lima. Without written word until the arrival of the Spanish in 1524, they were prehistoric people who were farmers who kept guinea pigs and other domestic animals as sources of meat [16]. Of these 51 mummies, 13 (25%) had definite or probable atherosclerosis [17], with a nonsignificant trend toward less atherosclerosis than in the Egyptian samples. Ancient Peruvians had been naturally mummified, simply dried in the desert sun without evisceration of the abdominal cavity. Such evisceration and other techniques were key components of Egyptian mummification designed to decrease putrefaction. Thus, the difference may have been related to less effective arterial and organ preservation in the Peruvians rather than a true difference in the prevalence of atherosclerosis. Environment and lifestyles did differ between the cultures, however.
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Fig. 3. Coronary calcifications in the mummy of a Unangan woman aged 47–51 years who lived in the late 19th century CE and was found in a cave on Kagamil Island of the Aleutian Islands (sagittal three-dimensional volume rendered image). Mummy 133 of Thompson and colleagues [17].
Janet Monge, PhD of the University of Pennsylvania Department of Anthropology and Museum of Archaeology and Anthropology arranged for the team to review the whole body CT images of five Ancestral Puebloan Native American mummies excavated from Southeast Utah and southwestern Colorado 120 years ago. They lived between 1500 BCE and 1500 CE and were likely forager–farmers [18]. Like the Peruvians, they predated the written word and were thus a prehistoric culture. One of the five mummies had definite atherosclerosis, another probable atherosclerosis [17]. Bruno Frohlich, PhD and colleagues at the Smithsonian Institution arranged for the review of the whole body CT scans of five Unangan mummies who lived in the Aleutian Islands between 1756 and 1930 CE. The Unangans were hunter–gatherers, without agriculture or domesticated animals [19]. Like the Ancestral Puebloans, individuals of their era lived in subterranean earthen homes in which fire used for cooking and light would have resulted in an often smoky household. Three of the five mummies had definite atherosclerosis. This included a 40–44-year-old woman with atherosclerosis of the right coronary artery, aorta, and peripheral arteries (Fig. 3). To our knowledge, she represents the first hunter–gatherer diagnosed with CAD [17]. As would be expected, these ancient peoples often died young. The mean age at death of all 137 mummies in the Horus cohort was 36 (SD 15) years. We acknowledge that the uncertainty of skeletal age dates may be >10 years for middle-aged and older specimens. Gender could be determined for 121 mummies; 77 were male and 44 female. Presence of atherosclerosis was specifically evaluated in five vascular beds: carotids, coronary, aorta, iliofemoral arteries, and popliteal/tibial arteries. The mean age of those without atherosclerosis was 32 (SD 15) years. For those with atherosclerosis of one to two beds, the mean age was 42 (SD 10) years and those with atherosclerosis of three to five beds, 44 (SD 8) years (p < 0.001) [17]. There was a nonsignificant trend in this cohort toward more extensive atherosclerosis among women. Discussion
Fig. 2. Coronary artery calcifications in the mummy of Ahmose-Meritamun of Thebes, an Egyptian princess aged 40–45 years who lived about 1580–1550 BCE (sagittal oblique 3D volume rendered image). Mummy 35 of Thompson and colleagues [17]. RCA, right coronary artery. Reprinted with permission.
Why would atherosclerosis be so prevalent among four cultures with such diverse diets and lifestyles? Chan and Boerwinkle estimate that human genetics predict approximately 50% of the prevalence for CAD, for example [20]. The findings of the Horus team and those of previous paleopathology researchers are consistent with a substantial innate vulnerability of humans to atherosclerosis. The epidemiologic and clinical work of thousands of researchers over the past half-century demonstrated that diet,
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lifestyle, and their impact on currently understood risk factors, contribute greatly to whether this vulnerability results in clinically apparent atherosclerosis or via imaging techniques. Referring back to the question raised in the introduction, is atherosclerosis a fundamental component of human aging? Our finding that atherosclerosis is common to four diverse populations is consistent with the hypothesis that atherosclerosis is indeed fundamental to aging. Studies by Lakatta and others suggest that arterial degeneration begins early in postnatal life and is progressive in all human populations for which there is postmortem analysis [21]. However, the degree of atherosclerosis can be delayed by a lifelong avoidance of lifestyle risk factors [22] or the genetic luck of having an abundance of low-density lipoprotein (LDL) receptors secondary to a loss of function single nucleotide polymorphism for PCSK9 and thus a lifetime of low LDL cholesterol [23]. A synthesis of these findings is consistent with a strong geneenvironmental interplay. Vulnerability to atherosclerosis is hard wired into the human genome with a substantial environmental, in this case, risk factor related, influence. With the 1961 coining of the phrase “factors of risk” by Kannel et al. [24] and the confirmation of their importance in the development of CAD in the Framingham and many other populations, clinicians now rely on their characterization and quantitation to predict and try to alter atherosclerosis risk [25]. Yet have we fully characterized all key risk factors involved? Researchers have carefully evaluated what is currently measurable by laboratory and other tests in the prediction of atherosclerosis. But what of processes we currently do not have the knowledge to measure? Why would our current medical knowledge necessarily include the ability to measure all physiologic or other factors that increase the risk of atherosclerosis? An inflammatory disease, atherosclerosis occurs prematurely in those with chronic inflammatory diseases such as rheumatoid arthritis (RA) and systemic lupus erythematosus [26]. Stamatelopoulos and colleagues found cardiovascular risk in RA to be comparable to the risk reported in patients with diabetes mellitus of similar disease duration [27]. CAD also occurs prematurely in those with human immunodeficiency virus, another chronic inflammatory disease [28].
Acute infection has also been found to play a role in the expression of atherosclerosis in individuals following influenza infections [29] or by its relative avoidance following immunization [30]. The environments in which these ancient persons lived predated the understanding of germ theory, modern hygiene, and antibiotics. Infection, and thus inflammation, was likely rampant [31]. This makes the profiling of infectious agents undertaken during one of the most sophisticated mummy autopsies ever performed, particularly important. In August 1974, a dozen Canadian-, US-, and British-based physicians, scientists, and technologists assembled for a carefully planned two-day autopsy of Nakht, the mummy of an Egyptian boy in his mid-teens [32]. The setting was the Anatomy Department of the Medical Sciences Building of the University of Toronto. Autopsy tools had evolved since the time of Ruffer, who only had a light microscope available. An early scanning electron microscope was one of these new tools, capable of magnifying tissue 1000 times greater than Ruffer had at his disposal [33]. Following the gross autopsy, tissues were directed to various laboratories of the team for more in-depth analyses. Sandison’s modification of Ruffer’s solution and other methods were used to rehydrate the tissue [34,35]. Identified by the hieroglyphics on his coffin as a weaver, he lived in Thebes, now the city of Luxor, during the last century of the New Kingdom (Fig. 4) [33]. Hieroglyphics on the coffin indicate that he worked in the temple of Pharaoh Setnakth, the first ruler of the 20th Dynasty (Fig. 5). Pharaoh Setnakth died circa. 1198 BCE [35]. As a weaver, Nakht would have sewn linen, the common cloth of the time, from the fiber of the local flax plant. In death, he was wrapped in linen badges and two linen robes. Nakht is depicted on the lid of his painted anthropoid coffin wearing a long wig striped in blue [36]. Pre-autopsy radiographs found that his mummification had not been typical of ancient Egyptians [37]. Like the Peruvian mummies, he had simply been dried out in the desert sun, in this case along the Nile, without evisceration or traditional preservation methods. As a dehydrated mummy, he weighed only 5.1 kg and was 1.4 m tall [33]. Excavated houses of Nakht’s era suggest that commoners such as a weaver would likely have lived in a two- or
Fig. 4. Mummy of Nakht, an Egyptian teenage boy of the New Kingdom [33]. Reprinted with permission of the Royal Ontario Museum © ROM.
Fig. 5. Painted anthropoid coffin of Nakht. Hieroglyphics on the coffin indicate that he worked as a weaver in the time of the Pharaoh Setnakth, the first ruler of the 20th Dynasty [33]. Reprinted with permission of the Royal Ontario Museum © ROM.
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Fig. 6. Images of the parasites that infected Nakht, an Egyptian teenage boy of the New Kingdom. (A) Schistosoma haematobium, found at autopsy to be in his liver, large and small intestine, kidney, and bladder [35]. Reprinted with the permission of Cambridge University Press. (B) Taenia species (tapeworm), found in his large and small intestine [35,42]. (C) Trichinella spiralis, found in an intercostal muscle. Reprinted with the permission of Cambridge University Press [35]. (D) Plasmodium falciparum identified by antigen immunoassay [35]. This image was not found in Nakht but is a representative image of the parasite.
three-room mud brick house with a flat roof of earth on rafters of palm logs. Cooking was carried out in an outside courtyard or on the roof [33,36]. A diverse diet was available during the New Kingdom. Eggs, butter, milk, lettuce, honey, cucumber, garlic, spices, dates, lentils, grapes, and figs have been retrieved from archeologic finds. Beer and wine, fish, domesticated cattle, sheep, pigs, and fowl were also known to be available [38–40]. The histologic and hematologic findings of the autopsy were remarkable, young Nakht was infected with four different parasites [41] (Fig. 6): (1) Schistosoma species were found in his liver, large and small bowel, kidney, and bladder. His bladder contained red blood cells, consistent with hematuria characteristic of infection by Schistosoma haematobium [42]. Schistosomiasis is endemic in modern-day Egypt. (2) Taenia species (tapeworm) ova were present in his small and large intestine. Adult worms, which can grow many meters long, were not found [42]. (3) Trichinella spiralis, suggestive of undercooked pork consumption, was found in an intercostal muscle [43]. (4) Plasmodium falciparum, which causes malaria, was identified by antigen immunoassay two decades later when this technique was available [41]. One of the authors (DEM), a mid-career pediatric infectious disease specialist practicing in the USA, has never knowingly cared for a patient with four different parasites. In another autopsy finding relevant to atherosclerosis, like most Egyptian mummies, Nakht had substantial pulmonary anthracosis – carbon deposition in the lungs from smoke. This
exposure could represent an unexpected risk factor for the development of atherosclerosis [17,44,45]. The trend toward more extensive atherosclerosis in women is of note, as women held a traditional role that included cooking in each of the four cultures. While not found during the evaluation of Nakht, Zink and colleagues determined by ancient DNA analysis that tuberculosis was common in ancient Thebes. Among 85 Thebean Egyptian mummies, ca. 2050 BCE to ca. 500 BCE, 48 had amplifiable ancient DNA. Of these, 25 had tuberculosis. This analytic DNA technique had not been developed at the time of Nakht’s autopsy [46]. Chronic infections were not limited to commoners of ancient civilizations. Arguably the most famous of all mummies, Pharaoh Tutankhamun, reigned during the 18th dynasty of the New Kingdom and died at the age of 19 ca.1324 BCE. Like Nakht, molecular analysis demonstrated that he had malaria, in Tutankhamen’s case, he had two different strains of P. falciparum, the parasite that causes malaria [47]. If Nakht is at all representative of ancient Egyptians, and potentially other ancient cultures, a lifelong inflammatory burden analogous to modern day chronic inflammatory diseases, may represent a decisive risk factor in the development of atherosclerosis [31,48–51]. Other yet to be discovered risk factors or etiologies could also be causal for the development of atherosclerosis in these ancient cultures. Further work in this field could provide rich rewards. Conclusion Insights from paleopathology suggest that our knowledge of risk factors and the etiology of atherosclerosis are incomplete. A chronic
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inflammatory burden may have played a greater role in ancient cultures than previously appreciated. While increasingly prevalent with age in ancient and modern cultures, a synthesis of the work reviewed is consistent with a strong gene-environmental interplay in the development of atherosclerosis across the lifespan. While genes create the vulnerability, the environment determines when and if atherosclerosis becomes manifest clinically. Funding Funding for the Horus study was provided by the National Endowment for the Humanities (#HJ-50069-12), the Paleocardiology Foundation, Siemens, the National Bank of Egypt, and the St Luke’s Hospital Foundation of Kansas City. Conflict of interest None declared. References [1] Chockalingam A, Balaguer-Vinto I, editors. Impending global pandemic of cardiovascular diseases: challenges and opportunities for the prevention and control of cardiovascular diseases in developing countries and economies in Transition World Heart Federation. Barcelona: Prous Science; 1999. [2] Yusuf S, Reddy S, Ounpuu S, Anand S. Global burden of cardiovascular diseases: part I: general considerations, the epidemiologic transition, risk factors, and impact of urbanization. Circulation 2001;104(22):2746–53. [3] Syme SL, Marmot MG, Kagan A, Kato H, Rhoads G. Epidemiologic studies of coronary heart disease and stroke in Japanese men living in Japan, Hawaii and California: introduction. Am J Epidemiol 1975;102(6):477–80. [4] Murphy Jr WA, zur Nedden D, Gostner P, Knapp R, Recheis W, Seidler H. The Iceman: discovery and imaging. Radiology 2003;226(3):614–29. [5] Czermak J. Description and microscopic findings of two Egyptian mummies. Meeting of the Academy of Science 1852;9:27. [6] Moodie RL, editor. Studies in the paleopathology of Egypt. Chicago, IL: University of Chicago Press; 1923. [7] Cockburn A. Introduction. In: Cockburn A, Cockburn E, editors. Mummies, disease and ancient cultures. first ed. Cambridge, UK: Cambridge University Press; 1980. p. 1–8. [8] Ruffer MA. On arterial lesions found in Egyptian mummies (1580 BC–535 AD). J Pathol Bacteriol 1911;16:453–62. [9] Ruffer MA. Preliminary note on the histology of Egyptian mummies. Br Med J 1909;1(2521):1005. [10] Allam AH, Thompson RC, Wann LS, Miyamoto MI, Thomas GS. Computed tomographic assessment of atherosclerosis in ancient Egyptian mummies. JAMA 2009;302(19):2091–4. [11] Allam AH, Nurledin H, Adelmaksoub G, Badr I, Amer HA, Soliman MAT, Thomas GS, Thompson RC, Miyamoto MI, Thomas IG, Thompson A, Wann S. Something old, something new-computed tomography studies of the cardiovascular system in ancient Egyptian mummies. Am Heart Hosp J 2010;8(1):10–3. [12] Abdelfattah A, Allam AH, Wann S, Thompson RC, Abdel-Maksoud G, Badr I, Amer HA, Nurledin H, Finch C, Miyamoto MI, Sutherland ML, Sutherland JD, Thomas GS. Atherosclerotic cardiovascular disease in Egyptian women: 1570 BCE–2011 CE. Int J Cardiol 2013;167(2):570–4. [13] Stary HC, Chandler AB, Dinsmore RE, Fuster V, Fuster V, Glagov S, Insull Jr W, Rosenfeld ME, Schwartz CJ, Wagner WD, Wissler RW. A definition of advanced types of atherosclerotic lesions and a histological classification of atherosclerosis. A report from the Committee on Vascular Lesions of the Council on Arteriosclerosis. Circulation 1995;92:1355–74. [14] Allam AH, Thompson RC, Wann LS, Miyamoto MI, Nur El-Din Ael-H, El-Maksoud GA, Soliman MA, Badr I, el-Amer HA, Sutherland ML, Sutherland JD, Thomas GS. Atherosclerosis in ancient Egyptian mummies: the Horus study. JACC Cardiovasc Imaging 2011;4(4):315–27. [15] Long A. Cardiovascular renal disease: a report of a case three thousand years ago. Arch Pathol (Chic) 1931;12:92–4. [16] Antunez de Mayolo S. La Nutricion en el Antiguo Perú. Lima, Peru: Banco Central de Reserva del Peru; 1981. [17] Thompson RC, Allam AH, Lombardi GP, Wann LS, Sutherland ML, Sutherland JD, Soliman MAT, Frohlich B, Mininberg DT, Monge JM, Vallodolid CM, Cox SL, Abd el-Maksoud G, Badr I, Miyamoto MI, et al. Atherosclerosis across 4000 years of human history: the Horus study of four ancient populations. Lancet 2013;381(9873):1211–22. [18] Downum C. Hisat’sinom. Ancient peoples in a land without water. Santa Fe, New Mexico: School for Advanced Research Press; 2012. [19] Laughlin WS. Aleuts: survivors of the Bering land bridge. New York, NY: Holt, Rinehart and Winston; 1980. [20] Chan L, Boerwinkle E. Gene–environment interactions and gene therapy in atherosclerosis. Cardiol Rev 1994;2:130–7.
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[25] Stone NJ, Robinson J, Lichtenstein AH, Bairey Merz CN, Lloyd-Jones DM, Blum CB, McBride P, Eckell RH, Schwartz JS, Goldberg AC, Shero ST, Gordon D, Smith SC, Levy D, Watson K, et al. 2013 ACC/AHA Guideline on the treatment of blood cholesterol to reduce atherosclerotic cardiovascular risk in adults: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines. J Am Coll Cardiol 2013. [26] Kahlenberg JM, Kaplan MJ. Mechanisms of premature atherosclerosis in rheumatoid arthritis and lupus. Ann Rev Med 2013;64:249–63. [27] Stamatelopoulos KS, Kitas GD, Papamichael CM, Chryssohoou E, Kyrkou K, Georgiopoulos G, Protogerou A, Panoulas VF, Sandoo A, Tentolouris N, Mavrikakis M, Sfikakis PP. Atherosclerosis in rheumatoid arthritis versus diabetes: a comparative study. Arterioscler Thromb Vasc Biol 2009;29(10): 1702–8. ˜ [28] Kingsley L, Cuervo-Rojas J, Alvaro Munoz, Palella F, Post W, Witt M, Budoff M, Kullerb L. Subclinical coronary atherosclerosis HIV infection and antiretroviral therapy: Multicenter AIDS Cohort Study. AIDS 2008;22(13):1589–99. [29] Warren-Gash C, Smeeth L, Hayward AC. Influenza as a trigger for acute myocardial infarction or death from cardiovascular disease: a systematic review. Lancet Infect Dis 2009;9(10):601–10. [30] Udell JA, Zawi R, Bhatt DL, Keshtkar-Jahromi M, Gaughran F, Phrommintikul A, Ciszewski A, Vakili H, Hoffman EB, Farkouh ME, Cannon CP. Association between influenza vaccination and cardiovascular outcomes in high-risk patients: a meta-analysis. JAMA 2013;310(16):1711–20. [31] Finch C. Evolution of the human lifespan, past, present, and future: phases in the evolution of human life expectancy in relation to the inflammatory load. Proc Natl Acad Sci U S A 2012;156(1):9–44. [32] Autopsy of an Egyptian mummy (Nakht-ROM 1). Can Med Assoc J 1977;177:461. [33] David R, Archbold R. Conversations with mummies. New York: William Morris; 2000. [34] Horne P, Lewin P. Electron microscopy of mummified tissue. Can Med Assoc J 1977;117:472–3. [35] Millet N, Reyman T, Hart G, Zimmerman MR, Lewin PK. ROM I: mummification for the common people. In: Cockburn A, Cockburn E, editors. Mummies, disease and ancient cultures. first ed. Cambridge, UK: Cambridge University Press; 1983. p. 71–84. [36] Millet NB. Archeologic background. Can Med Assoc J 1977;177:462. [37] Rideout DF. Radiologic examination. Can Med Assoc J 1977;177:463. [38] Finch CE. Atherosclerosis is an old disease: summary of the Ruffer Centenary Symposium, The Paleocardiology of Ancient Egypt, a meeting report of the Horus Study team. Exp Gerontol 2011;46(11):843–6. [39] Nur El-Din Ael-H, Food and beverage in ancient EgyptHorus symposium. 2010. [40] Darby W, Ghalioungui P, Grivatti L. Food: the gift of Osiris. London, UK: Academic Press; 1957. [41] Millet N, Hart G, Reyman T, Zimmerman M, Lewin P. ROM I: mummification for the common people. In: Cockburn A, Cockburn E, Reyman T, editors. Mummies, diseases & ancient cultures. second ed. Cambridge, UK: Cambridge University Press; 1998. p. 91–105. [42] Reyman T, Zimmerman M, Lewin P. Histopathologic investigation. Can Med Assoc J 1977;177:470–1. [43] de Boni U, Lenczner M, Scott JW. Trichinella spiralis cyst. Can Med Assoc J 1977;177:472. [44] Campen M, Lund A, Doyle-Eisele M, Jacob D, McDonald J, Knuckles T, Rohr AC, Knipping EM, Mauderly JL. A comparison of vascular effects from complex and individual air pollutants indicates a role for monoxide gases and volatile hydrocarbons. Environ Health Perspect 2010;118:921–7. [45] Unosson J, Blomberg A, Sandstrom T, Muala A, Boman C, Nystrom R, Westerholm R, Mills NL, Newby DE, Langrish JP, Bosson JA. Exposure to wood smoke increases arterial stiffness and decreases heart rate variability in humans. Part Fibre Toxicol 2013;10:20. [46] Zink AR, Sola C, Reischl U, Grabner W, Rastogi N, Wolf H, Nerlich AG. Characterization of Mycobacterium tuberculosis complex DNAs from Egyptian mummies by spoligotyping. J Clin Microbiol 2003;41(1):359–67. [47] Hawass Z, Gad Y, Ismail S, Khairat R, Fathalla D, Hasan N, Ahmed A, Elleithy H, Ball M, Gaballah F, Wasef S, Fateen M, Amer H, Gostner P, Selim A, et al. Ancestry and pathology in King Tutankhamun’s family. JAMA 2010;303(7): 638–47. [48] Finch CE. Evolution in health and medicine Sackler colloquium: evolution of the human lifespan and diseases of aging: roles of infection, inflammation, and nutrition. Proc Natl Acad Sci U S A 2010;107(Suppl. 1):1718–24. [49] Gurven M, Kaplan H, Winking J, Finch C, Crimmins EM. Aging and inflammation in two epidemiological worlds. J Gerontol A Biol Sci Med Sci 2008;63(2):196–9. [50] Finch CE. The biology of human longevity. Inflamation, nutrition and aging in the evolution of lifespans. Amsterdam, Netherlands: Academic Press; 2007. [51] Crimmins EM, Finch CE. Infection, inflammation, height, and longevity. 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Contents lists available at ScienceDirect
Journal of Cardiology journal homepage: www.elsevier.com/locate/jjcc
Review
Is atherosclerosis fundamental to human aging? Lessons from ancient mummies Emily M. Clarke a , Randall C. Thompson (MD) b,c , Adel H. Allam (MD) d , L. Samuel Wann (MD) e , Guido P. Lombardi (PhD) f , M. Linda Sutherland (MD) g , James D. Sutherland (MD, MS) h , Samantha L. Cox (MD) i , Muhammad Al-Tohamy Soliman (PhD) j , Gomaa Abd el-Maksoud (PhD) k , Ibrahem Badr (PhD) l , Michael I. Miyamoto (MD, MBA) m , Bruno Frohlich (PhD) n , Abdel-Halim Nur el-din (PhD) o , Alexandre F.R. Stewart (PhD) p , Jagat Narula (MD, PhD) q , Albert R. Zink (PhD) r , Caleb E. Finch (PhD) s , David E. Michalik (DO) t,u , Gregory S. Thomas (MD, MPH) v,u,∗ a
University of California, Los Angeles, CA, USA Saint Luke’s Mid America Heart Institute, Kansas City, MO, USA c University of Missouri–Kansas City School of Medicine, Kansas City, MO, USA d Al Azhar Medical School, Cairo, Egypt e Columbia St Mary’s Healthcare, Milwaukee, WI, USA f Laboratorio de Paleopatologia, Catedra Pedro Weiss, Universidad Peruana Cayetano Heredia, Lima, Peru g Newport Diagnostic Center, Newport Beach, CA, USA h Saddleback Memorial, Laguna Hills, CA, USA i University of Cambridge, Cambridge, UK j National Research Center, Giza, Egypt k Cairo University, Cairo, Egypt l Institute of Restoration, Alexandria, Egypt m Mission Internal Medical Group, Mission Viejo, CA, USA n Smithsonian Institution, National Museum of Natural History, Washington, DC, USA o University for Science and Technology, 6th of October City, Egypt p University of Ottawa Heart Institute, Ottawa, Ontairo, Canada q Mount Sinai, New York, NY, USA r Institute for Mummies and the Iceman, European Academy, Bolzano, Italy s University of Southern California, Los Angeles, CA, USA t Miller Children’s Hospital, Long Beach, CA, USA u University of California, Irvine, CA, USA v MemorialCare Heart & Vascular Institute, Long Beach Memorial, Long Beach, CA, USA b
a r t i c l e
i n f o
Article history: Received 9 December 2013 Accepted 11 December 2013 Available online 28 February 2014 Keywords: Mummies Atherosclerosis Aging Paleopathology Coronary artery disease
a b s t r a c t Case reports from Johan Czermak, Marc Ruffer, and others a century or more ago demonstrated ancient Egyptians had atherosclerosis three millennia ago. The Horus study team extended their findings, demonstrating that atherosclerosis was prevalent among 76 ancient Egyptian mummies and among 61 mummies from each of the ancient cultures of Peru, the American Southwest, and the Aleutian Islands. These findings challenge the assumption that atherosclerosis is a modern disease caused by present day risk factors. An extensive autopsy of an ancient Egyptian teenage male weaver named Nakht found that he was infected with four parasites: Schistosoma haematobium, Taenia species, Trichinella spiralis, and Plasmodium falciparum. Modern day patients with chronic inflammatory disease such as rheumatoid arthritis, systemic lupus erythematosus, and human immunodeficiency virus experience premature atherosclerosis. Could the burden of chronic inflammatory disease have been a risk factor for atherosclerosis in these ancient cultures? The prevalence of atherosclerosis in four diverse ancient cultures is consistent with atherosclerosis being fundamental to aging. The impact of risk factors in modern times, and potentially
∗ Corresponding author at: Long Beach Memorial, 2801 Atlantic Avenue, Long Beach, CA 90806, USA. Tel.: +1 562 933 3317; fax: +1 562 933 1819. E-mail address: [email protected] (G.S. Thomas). 0914-5087/$ – see front matter © 2014 Japanese College of Cardiology. Published by Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.jjcc.2013.12.012
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in ancient times, suggests a strong gene-environmental interplay: human genes provide a vulnerability to atherosclerosis, the environment determines when and if atherosclerosis becomes manifest clinically. © 2014 Japanese College of Cardiology. Published by Elsevier Ltd. All rights reserved.
Contents Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Pioneering work . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Horus study team investigations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Funding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Conflict of interest . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Introduction Why do humans develop atherosclerosis? Is atherosclerosis fundamental to aging? Is it environmental? Chockalingam and colleagues suggest that classic risk factors account for 50% of the attributable risk of atherosclerosis [1]. Whereas Yusuf and colleagues argue risk factors account for a greater proportion of that risk [2]. One of the first to describe the importance of environmental risk, the authors of the landmark Ni-Hon-San study of 1975 demonstrated that among men of Japanese ancestry, those living in Japan (Hiroshima and Nagasaki) had the lowest incidence of coronary artery disease (CAD), with increasing incidence in those living in Honolulu, and greater still among those living in the San Francisco Bay area [3]. Atherosclerosis was found to be present in humans long before modern civilization and present day risk factors. With the help of computed tomography (CT) scanning, Murphy and colleagues demonstrated bilateral carotid calcific atherosclerosis in Otzi the Iceman, a mummy dating back to 3300 BCE [4] (BCE, Before Common Era is equivalent to BC, Before Christ). Their discovery represents the earliest documentation of atherosclerosis in humans. Pioneering work In 1852, Czermak was the first to report atherosclerosis in ancient people [5]. Autopsying the mummy of an elderly Egyptian woman in Vienna, Austria, Czermak found “multiple considerably large and calcified plaques” in her descending aorta. How does this finding fit into our current risk factor model of atherosclerosis? What risk factors would be present in this woman living along the Nile in ancient Egypt? Czermak’s findings were confirmed over fifty years later by Marc Armand Ruffer, MD, a bacteriologist who trained with Louis Pasteur. He found evidence of atherosclerosis on autopsy of multiple Egyptian mummies and mummified limbs and presented his findings at the Cairo Scientific Society in December 1908 [5,6]. Ruffer received these specimens from archeological colleagues who were asked to excavate ancient Egyptian tombs prior to the expected downstream flooding that would occur with the raising of the height of the Aswan Dam in 1907 [7]. The brittleness of dehydrated mummies had baffled previous scientist’s autopsy attempts to create slides for microscopic analysis. Ruffer, however, determined that he could slowly rehydrate the tissue by its immersion in a solution composed of an alkali salt and alcohol of varying concentrations over several days. This rehydration process allowed microtome sectioning of the fragile tissue and demonstrated calcific atherosclerosis to be common in
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Egyptian mummies. In his classic 1911 article [8], Ruffer stated, “In my opinion, therefore, the old Egyptians suffered as much as we do from arterial lesions identical with those found in the present time. Moreover, when we consider that few of the arteries examined were quite healthy, it would appear that such lesions were as frequent 3,000 years ago as they are today.” He thus concluded, “I can not therefore give any reason why arterial disease should have been so prevalent in ancient Egypt. I think, however, that it is interesting to find that it was common and that 3,000 years ago it represented the same anatomic characters as it does now.” Horus study team investigations A century following Ruffer’s landmark work [9], the Horus study team formed to evaluate the presence, extent, and potential etiologies of atherosclerosis in Egyptian and non-Egyptian ancient peoples. The team has since grown to become an international multidisciplinary group of physicians and scientists that includes the authors of this paper and other members. The team’s namesake (Horus) is one of the oldest and most significant deities of ancient Egypt. One of Horus’ many tasks was that of protector. His depiction as falcon made of gold serves as a breastplate for many royal Egyptian mummies (Fig. 1). Using a Siemens Emotion 6 slice CT scanner (Florsheim, Germany) on site at the Egyptian National Museum of Antiquities in Cairo, Egypt in February 2009, the initial Horus team imaged 20 mummies and was provided the CT scans of two others [10–12]. The CT scanner was initially donated by Siemens and the National Geographic Society to image Pharaoh Tutankhamun. The team used
Fig. 1. The deity Horus depicted as a falcon, the breastplate of Tjanefer of Thebes, and the Third intermediate period (1080–712 BCE). Mummy 9 of Thompson and colleagues [17].
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arterial calcification as a pathognomonic marker of atherosclerosis [13]. Calcification in the wall of a clearly identifiable artery was labeled diagnostic of atherosclerosis, calcification along an artery’s expected course was labeled as probable atherosclerosis [10]. To the team’s surprise, definite atherosclerosis was present in 5 and probable in 4 out of the 22 scanned mummies. A larger team returned to Egypt in May 2010 to scan 22 more mummies and review the CT scans of 8 additional mummies which were provided to them. Mummies now totaled 52. Of these, 20 had definite or probable atherosclerosis [14]. One of the mummies imaged was Princess Ahmose-Meryet-Amon, the daughter of 17th Dynasty Pharaoh Seqenenre Tao II and his wife Queen Ahhotep I. The Princess’ half brother, Ahmose I, became the first Pharaoh of the New Kingdom, the Golden Age of Egypt. When Princess AhmoseMeryet-Amon died at an estimated age of 40–45 years, she had atherosclerosis of all her major vascular beds, including her right coronary and left anterior descending coronary arteries (Fig. 2). She is thus far the earliest human in history with CAD. Prior to this discovery, the earliest recorded case of CAD was by Allen Long, MD in 1931 of Lady Teye, who lived during the 21st dynasty, circa. 1000 BCE [15]. Following the Egyptian revolution of 2011, the Horus team transitioned to imaging mummies in Lima, Peru. The work of Guido P. Lombardi, MD, MA and Clide M. Vallodolid resulted in the provision for the scanning of 51 ancient Peruvian mummies from the Museo de Sitio Puruchuco – Arturo Jimenez Borja. These ancient Peruvians lived between 900 BCE and 1500 CE on or near the coast of modern day Lima. Without written word until the arrival of the Spanish in 1524, they were prehistoric people who were farmers who kept guinea pigs and other domestic animals as sources of meat [16]. Of these 51 mummies, 13 (25%) had definite or probable atherosclerosis [17], with a nonsignificant trend toward less atherosclerosis than in the Egyptian samples. Ancient Peruvians had been naturally mummified, simply dried in the desert sun without evisceration of the abdominal cavity. Such evisceration and other techniques were key components of Egyptian mummification designed to decrease putrefaction. Thus, the difference may have been related to less effective arterial and organ preservation in the Peruvians rather than a true difference in the prevalence of atherosclerosis. Environment and lifestyles did differ between the cultures, however.
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Fig. 3. Coronary calcifications in the mummy of a Unangan woman aged 47–51 years who lived in the late 19th century CE and was found in a cave on Kagamil Island of the Aleutian Islands (sagittal three-dimensional volume rendered image). Mummy 133 of Thompson and colleagues [17].
Janet Monge, PhD of the University of Pennsylvania Department of Anthropology and Museum of Archaeology and Anthropology arranged for the team to review the whole body CT images of five Ancestral Puebloan Native American mummies excavated from Southeast Utah and southwestern Colorado 120 years ago. They lived between 1500 BCE and 1500 CE and were likely forager–farmers [18]. Like the Peruvians, they predated the written word and were thus a prehistoric culture. One of the five mummies had definite atherosclerosis, another probable atherosclerosis [17]. Bruno Frohlich, PhD and colleagues at the Smithsonian Institution arranged for the review of the whole body CT scans of five Unangan mummies who lived in the Aleutian Islands between 1756 and 1930 CE. The Unangans were hunter–gatherers, without agriculture or domesticated animals [19]. Like the Ancestral Puebloans, individuals of their era lived in subterranean earthen homes in which fire used for cooking and light would have resulted in an often smoky household. Three of the five mummies had definite atherosclerosis. This included a 40–44-year-old woman with atherosclerosis of the right coronary artery, aorta, and peripheral arteries (Fig. 3). To our knowledge, she represents the first hunter–gatherer diagnosed with CAD [17]. As would be expected, these ancient peoples often died young. The mean age at death of all 137 mummies in the Horus cohort was 36 (SD 15) years. We acknowledge that the uncertainty of skeletal age dates may be >10 years for middle-aged and older specimens. Gender could be determined for 121 mummies; 77 were male and 44 female. Presence of atherosclerosis was specifically evaluated in five vascular beds: carotids, coronary, aorta, iliofemoral arteries, and popliteal/tibial arteries. The mean age of those without atherosclerosis was 32 (SD 15) years. For those with atherosclerosis of one to two beds, the mean age was 42 (SD 10) years and those with atherosclerosis of three to five beds, 44 (SD 8) years (p < 0.001) [17]. There was a nonsignificant trend in this cohort toward more extensive atherosclerosis among women. Discussion
Fig. 2. Coronary artery calcifications in the mummy of Ahmose-Meritamun of Thebes, an Egyptian princess aged 40–45 years who lived about 1580–1550 BCE (sagittal oblique 3D volume rendered image). Mummy 35 of Thompson and colleagues [17]. RCA, right coronary artery. Reprinted with permission.
Why would atherosclerosis be so prevalent among four cultures with such diverse diets and lifestyles? Chan and Boerwinkle estimate that human genetics predict approximately 50% of the prevalence for CAD, for example [20]. The findings of the Horus team and those of previous paleopathology researchers are consistent with a substantial innate vulnerability of humans to atherosclerosis. The epidemiologic and clinical work of thousands of researchers over the past half-century demonstrated that diet,
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lifestyle, and their impact on currently understood risk factors, contribute greatly to whether this vulnerability results in clinically apparent atherosclerosis or via imaging techniques. Referring back to the question raised in the introduction, is atherosclerosis a fundamental component of human aging? Our finding that atherosclerosis is common to four diverse populations is consistent with the hypothesis that atherosclerosis is indeed fundamental to aging. Studies by Lakatta and others suggest that arterial degeneration begins early in postnatal life and is progressive in all human populations for which there is postmortem analysis [21]. However, the degree of atherosclerosis can be delayed by a lifelong avoidance of lifestyle risk factors [22] or the genetic luck of having an abundance of low-density lipoprotein (LDL) receptors secondary to a loss of function single nucleotide polymorphism for PCSK9 and thus a lifetime of low LDL cholesterol [23]. A synthesis of these findings is consistent with a strong geneenvironmental interplay. Vulnerability to atherosclerosis is hard wired into the human genome with a substantial environmental, in this case, risk factor related, influence. With the 1961 coining of the phrase “factors of risk” by Kannel et al. [24] and the confirmation of their importance in the development of CAD in the Framingham and many other populations, clinicians now rely on their characterization and quantitation to predict and try to alter atherosclerosis risk [25]. Yet have we fully characterized all key risk factors involved? Researchers have carefully evaluated what is currently measurable by laboratory and other tests in the prediction of atherosclerosis. But what of processes we currently do not have the knowledge to measure? Why would our current medical knowledge necessarily include the ability to measure all physiologic or other factors that increase the risk of atherosclerosis? An inflammatory disease, atherosclerosis occurs prematurely in those with chronic inflammatory diseases such as rheumatoid arthritis (RA) and systemic lupus erythematosus [26]. Stamatelopoulos and colleagues found cardiovascular risk in RA to be comparable to the risk reported in patients with diabetes mellitus of similar disease duration [27]. CAD also occurs prematurely in those with human immunodeficiency virus, another chronic inflammatory disease [28].
Acute infection has also been found to play a role in the expression of atherosclerosis in individuals following influenza infections [29] or by its relative avoidance following immunization [30]. The environments in which these ancient persons lived predated the understanding of germ theory, modern hygiene, and antibiotics. Infection, and thus inflammation, was likely rampant [31]. This makes the profiling of infectious agents undertaken during one of the most sophisticated mummy autopsies ever performed, particularly important. In August 1974, a dozen Canadian-, US-, and British-based physicians, scientists, and technologists assembled for a carefully planned two-day autopsy of Nakht, the mummy of an Egyptian boy in his mid-teens [32]. The setting was the Anatomy Department of the Medical Sciences Building of the University of Toronto. Autopsy tools had evolved since the time of Ruffer, who only had a light microscope available. An early scanning electron microscope was one of these new tools, capable of magnifying tissue 1000 times greater than Ruffer had at his disposal [33]. Following the gross autopsy, tissues were directed to various laboratories of the team for more in-depth analyses. Sandison’s modification of Ruffer’s solution and other methods were used to rehydrate the tissue [34,35]. Identified by the hieroglyphics on his coffin as a weaver, he lived in Thebes, now the city of Luxor, during the last century of the New Kingdom (Fig. 4) [33]. Hieroglyphics on the coffin indicate that he worked in the temple of Pharaoh Setnakth, the first ruler of the 20th Dynasty (Fig. 5). Pharaoh Setnakth died circa. 1198 BCE [35]. As a weaver, Nakht would have sewn linen, the common cloth of the time, from the fiber of the local flax plant. In death, he was wrapped in linen badges and two linen robes. Nakht is depicted on the lid of his painted anthropoid coffin wearing a long wig striped in blue [36]. Pre-autopsy radiographs found that his mummification had not been typical of ancient Egyptians [37]. Like the Peruvian mummies, he had simply been dried out in the desert sun, in this case along the Nile, without evisceration or traditional preservation methods. As a dehydrated mummy, he weighed only 5.1 kg and was 1.4 m tall [33]. Excavated houses of Nakht’s era suggest that commoners such as a weaver would likely have lived in a two- or
Fig. 4. Mummy of Nakht, an Egyptian teenage boy of the New Kingdom [33]. Reprinted with permission of the Royal Ontario Museum © ROM.
Fig. 5. Painted anthropoid coffin of Nakht. Hieroglyphics on the coffin indicate that he worked as a weaver in the time of the Pharaoh Setnakth, the first ruler of the 20th Dynasty [33]. Reprinted with permission of the Royal Ontario Museum © ROM.
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Fig. 6. Images of the parasites that infected Nakht, an Egyptian teenage boy of the New Kingdom. (A) Schistosoma haematobium, found at autopsy to be in his liver, large and small intestine, kidney, and bladder [35]. Reprinted with the permission of Cambridge University Press. (B) Taenia species (tapeworm), found in his large and small intestine [35,42]. (C) Trichinella spiralis, found in an intercostal muscle. Reprinted with the permission of Cambridge University Press [35]. (D) Plasmodium falciparum identified by antigen immunoassay [35]. This image was not found in Nakht but is a representative image of the parasite.
three-room mud brick house with a flat roof of earth on rafters of palm logs. Cooking was carried out in an outside courtyard or on the roof [33,36]. A diverse diet was available during the New Kingdom. Eggs, butter, milk, lettuce, honey, cucumber, garlic, spices, dates, lentils, grapes, and figs have been retrieved from archeologic finds. Beer and wine, fish, domesticated cattle, sheep, pigs, and fowl were also known to be available [38–40]. The histologic and hematologic findings of the autopsy were remarkable, young Nakht was infected with four different parasites [41] (Fig. 6): (1) Schistosoma species were found in his liver, large and small bowel, kidney, and bladder. His bladder contained red blood cells, consistent with hematuria characteristic of infection by Schistosoma haematobium [42]. Schistosomiasis is endemic in modern-day Egypt. (2) Taenia species (tapeworm) ova were present in his small and large intestine. Adult worms, which can grow many meters long, were not found [42]. (3) Trichinella spiralis, suggestive of undercooked pork consumption, was found in an intercostal muscle [43]. (4) Plasmodium falciparum, which causes malaria, was identified by antigen immunoassay two decades later when this technique was available [41]. One of the authors (DEM), a mid-career pediatric infectious disease specialist practicing in the USA, has never knowingly cared for a patient with four different parasites. In another autopsy finding relevant to atherosclerosis, like most Egyptian mummies, Nakht had substantial pulmonary anthracosis – carbon deposition in the lungs from smoke. This
exposure could represent an unexpected risk factor for the development of atherosclerosis [17,44,45]. The trend toward more extensive atherosclerosis in women is of note, as women held a traditional role that included cooking in each of the four cultures. While not found during the evaluation of Nakht, Zink and colleagues determined by ancient DNA analysis that tuberculosis was common in ancient Thebes. Among 85 Thebean Egyptian mummies, ca. 2050 BCE to ca. 500 BCE, 48 had amplifiable ancient DNA. Of these, 25 had tuberculosis. This analytic DNA technique had not been developed at the time of Nakht’s autopsy [46]. Chronic infections were not limited to commoners of ancient civilizations. Arguably the most famous of all mummies, Pharaoh Tutankhamun, reigned during the 18th dynasty of the New Kingdom and died at the age of 19 ca.1324 BCE. Like Nakht, molecular analysis demonstrated that he had malaria, in Tutankhamen’s case, he had two different strains of P. falciparum, the parasite that causes malaria [47]. If Nakht is at all representative of ancient Egyptians, and potentially other ancient cultures, a lifelong inflammatory burden analogous to modern day chronic inflammatory diseases, may represent a decisive risk factor in the development of atherosclerosis [31,48–51]. Other yet to be discovered risk factors or etiologies could also be causal for the development of atherosclerosis in these ancient cultures. Further work in this field could provide rich rewards. Conclusion Insights from paleopathology suggest that our knowledge of risk factors and the etiology of atherosclerosis are incomplete. A chronic
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