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RED WINE’S ENIGMATIC DIRTY DRUG
GIVEN THAT SCIENTISTS generally saw the quest for anti-aging drugs as a shady enterprise until around 2000, it isn’t surprising that many of the researchers drawn to it before then hailed from the rambunctious end of the psychic spectrum. I mean the kind of person who, during his boy scientist days, didn’t patiently wait for the miracle of metamorphosis to play out in his jar of tadpoles, but instead told his little brother that the jar was full of lemonade and watched with fascination as the tyke eagerly gulped its contents down. Or who investigated the power of the compound bow by shooting arrows straight up, then madly scrambling for cover after losing sight of them. Or who figured out how to trap a cloud of methane in a sink during high school chem class, then tossed in a match to see how high the flames would go. In short, the enterprise has been a magnet for scientists like David Sinclair, from whose life these episodes were drawn.11
Sinclair’s teachers could readily trace his bent for science, which he excelled in when not clowning around. Both of his parents worked for a medical diagnostics firm in Sydney, and his family’s dinner table conversations often touched on topics like the wonderfully grisly effects of certain diseases. To fathom his puckish side, though, one needed to know about his grandmother, Vera, who often oversaw the young “Dr. Sinclair,” as she playfully called him, during his formative years while his parents were at work.
The free-spirited daughter of a Hungarian movie director, Vera had given birth to Sinclair’s father, Andrew, in her midteens. During the Nazi occupation of Hungary in the 1940s, her family had thumbed their noses at Hitler by secretly sheltering Jewish friends in their apartment. When Soviet tanks rolled into Hungary in 1956, she was one of the daring few who got out, dodging searchlights one snowy night while running across the border to Austria with Andrew, then sixteen. She set up a new life in Australia but continued to flout authority, once getting run off a Sydney beach for wearing a bikini before skimpy was in. Later she went off to New Guinea for a year, where she mingled with natives whose funeral rites included eating the brains of the recently departed. Sinclair proudly recounts that “my grandmother was a former accountant who lived with human flesh eaters.”
By his twenties, Sinclair had become a rebel with a cause: making a major discovery in molecular biology. After his postdoc in Guarente’s lab at MIT, he landed a coveted post as an assistant professor at Harvard Medical School. Once ensconced in his own lab, he began challenging elder scientists’ views, beginning with one of Guarente’s theories. At a meeting in 2002, Sinclair questioned his former mentor’s hypothesis about how SIR2 is activated and proposed an alternative mechanism that he later detailed in a research report. It was a technical dispute of limited significance—they later agreed that both mechanisms may come into play. But then a weightier contest took shape between them.
In mid-2003, Sinclair’s lab made its first big splash by identifying resveratrol and related plant compounds as SIR2 boosters. The discovery promised to lead to CR mimetics targeting SIR2—resveratrol itself was obviously a candidate. It was a major coup, one that Guarente had hoped to make in his MIT lab or to see happen at Elixir, which he’d cofounded three years earlier.
Sinclair followed up by forming his own biotech, Sirtris Pharmaceuticals, that aimed to beat Elixir at its own game. Pulling no punches, the brash Harvard researcher told Science magazine in early 2004 that Elixir “is doing exactly what we’re doing, and it’s a race.” Guarente, who earlier had tried to enlist Sinclair as an adviser to Elixir, acknowledged in the same article that the contretemps with Sinclair “has run me through so many emotions, some of which I didn’t know I had.” Despite being attacked, one of his feelings was the pride a father feels when his unruly offspring does something great.
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The discovery that resveratrol may be a CR mimetic represented a landmark in several ways, one of which got little notice: The fact that the advance came out of Harvard Medical School effectively stamped the establishment’s imprimatur on the quest for a way to extend life span. No institution could have done that more definitively. Stroll along Boston’s Longwood Avenue and you can’t help but notice how the neoclassical white marble buildings at the medical school’s center look down with the august repose of a latter-day Parthenon, as if to let passing mortals know that Asclepius, the Greek god of medicine, would be on the faculty except for a minor oversight by the Fates. Making up for their baffling mistake, the school has brought forth a series of medical demigods—its professors have racked up no less than thirteen Nobel Prizes.
Behind the stately exterior, of course, you’ll find academe’s usual clashing of massive egos and desperate clawing for tenure. The passionate desires to unravel mysteries and to alleviate suffering are part of the picture too. Such discord, ambition, and compassion might be found at any medical school. But only one of them is Harvard’s, and if you make your mark here it tends to loom large and last long.
The study that elevated both resveratrol and Sinclair to stardom didn’t start at Harvard, though. Its first step was taken at Biomol Research Laboratories, a supplier of research reagents in Plymouth Meeting, Pennsylvania, near Philadelphia. (Biomol is now a unit of Enzo Biochem.) Konrad Howitz, Biomol’s director of molecular biology, had developed a test for measuring how fast SIRT1, SIR2’s mammalian counterpart, shaves acetyl groups off proteins. The assay was designed to help find compounds that affect the reaction’s speed, a sign that they abet or hinder the SIRT1 enzyme’s activity. Sinclair had assisted Biomol by providing Howitz with genetic material for making the assay, and in return Howitz had sent him Biomol’s finished test kit.
After refining the assay in early 2003, Howitz screened various chemicals with it and turned up two that seemed to boost SIRT1. That was quite unexpected. Enzymes are known as nature’s fine-tuned molecular Porsches. Chemical additives that make them run faster than they normally do are very rare. Indeed, pharmaceutical developers have never shown much interest in trying to develop such additives as drugs, for even if they existed, which was deemed questionable for most enzymes, it seemed prohibitively hard to find them.
But Howitz’s surprising discovery seemed real, partly because there was something of pattern to it. The two chemicals that seemed to grease SIRT1’s wheels, piceatannol and quercetin, are structurally related members of a family of molecules, called polyphenols, that are found in fruits and other plant foods. Polyphenols are antioxidants and had long been thought to confer health benefits by mopping up free radicals. Howitz tested other polyphenols and soon uncovered more than a dozen that sped up SIRT1 in the test tube. The most potent one was resveratrol, a compound found in grape skins, peanuts, and other foods, as well as in giant knotweed, a plant used in traditional Chinese medicine. (The latter is the main source of resveratrol used to make dietary supplements.)
Sinclair could hardly contain his excitement when Howitz told him about the findings—SIRT1 stimulators, he knew, might act as CR mimetics in mammals, possibly including humans. And it didn’t take him long to discover that a lot was already known about resveratrol indicating that it could confer a remarkably broad array of health benefits, which is just what a CR mimetic should do.
First isolated in 1940 from the roots of a plant called white hellebore, resveratrol had come to many researchers’ attention in 1992 when two Cornell University food scientists suggested that its presence in red wine is what gives the drink, in moderation, its ability to reduce the risk of heart disease. Red wine’s cardiac benefits had been spotlighted a few months earlier when 60 Minutes had covered the “French paradox,” a term referring to the curiously low mortality from heart disease in France despite buttery diets there loaded with fat. The popular news show had singled out consumption of red wine as the paradox’s most likely explanation.
The Cornell scientists speculated that resveratrol confers heart benefits by lowering blood levels of cholesterol and triglycerides. That idea didn’t hold up, though, and in 1997 researchers at the University of Illinois at Chicago proposed a sounder theory: that resveratrol has potent anti-inflammatory effects. The Chicago scientists also discovered that it has a striking ability to block cancer. In fact, when they topically administered resveratrol to mice along with chemicals that induce skin cancer, the number of rodents that got tumors was cut by nearly 90 percent. And resveratrol seemed totally nontoxic.
After the Chicago report, the number of studies citing resveratrol literally rose at an exponential rate. By the time Howitz discovered that resveratrol stimulates SIRT1, there was preliminary evidence that it can lower risk of multiple forms of cancer, Alzheimer’s disease, heart disease, strokes, hearing loss, and osteoarthritis. To Sinclair and Howitz, the next step was glaringly obvious: test whether resveratrol can extend life span.
Dousing short-lived yeast cells with the compound was the fastest way to do that, and Sinclair quickly lined up a group of mother cells for the job. He had reason to hurry. Howitz had told him that Biomol had supplied its SIRT1 assay to Elixir. Thus, it was entirely possible that the biotech company had also discovered SIRT1 activators, possibly including resveratrol, and was about to scoop Sinclair’s team, which Howitz had joined for the yeast study. Determined to get the experiment right the first time, Sinclair took the unusual step of carrying it out himself rather than entrusting the nitty-gritty work to one of his lab’s junior researchers.
The task took him back to his days of doing marathon life-span studies in Guarente’s lab, when he often felt like a midwife during a birthing process that went on for a week. After spending most of the day at his Harvard lab plucking away newly budded daughter cells under the microscope, he told me, “I’d drive home with the four plates [containing the mother cells], get home, do a round of plucking at a little lab I set up on the dining room table, have dinner, then do another round. I’d have to tell my one-year-old daughter not to run across the floor, because it would shake my dissecting needle. Sandra [Luikenhuis, his wife] got pretty annoyed.”
But she could also sympathize, having experienced the mesmerizing effect of the big experiment herself. A German native, she’d met Sinclair in Australia while studying abroad. After joining him in the United States, she earned a Ph.D. in biology at MIT and then launched her career handling corporate development at a fledgling biotech in Cambridge, Massachusetts. Naturally, she was always the first to hear how her husband’s mothers were doing.
When it became clear one fine spring day that yeast cells on resveratrol were replicating significantly more times than control cells that hadn’t been dosed with it, Sinclair rushed out of his lab and drove to a park where Sandra was pushing the couple’s oldest daughter in a stroller. After spotting her and rushing up, he blurted out, “I think it worked!” A matter-of-fact stickler for details, she calmly asked him exactly what did he mean by that.
No one realized it at the time, but one thing it meant was that Sinclair would soon get more public attention in a single day than the vast majority of scientists get in a lifetime. In August 2003, Nature published the study, which showed that adding resveratrol to yeast cells’ medium increased their average life span by a spectacular 70 percent and boosted maximum life span by nearly as much. The paper also reported that resveratrol activated the SIRT1 enzyme in human cells, fortifying them against DNA-damaging radiation. And in a tantalizing hint of things to come, it disclosed that resveratrol had extended life span in preliminary studies with nematodes and fruit flies. Concluding with a flourish, Sinclair and colleagues proposed that polyphenols like resveratrol are CR mimetics that can confer many health benefits by activating SIR2-like genes, collectively known as sirtuins (pronounced sir-TWO-ins).
The presence of a possible CR mimetic in red wine put new zing into the French paradox, and the idea that you might brake aging by hoisting glasses of wine instantly became one of the top, feel-good medical stories of the year. Mobbed by the press, Sinclair proved himself a natural at the art of sounding thoughtfully optimistic. “We’re making history,” he told Newsweek. But “I don’t think we’ll see any Methuselahs in our lifetime . . . we might each get another five years of life.” Or we might not, he cautiously mused in a Boston Globe interview. In fact, “we clearly don’t know if this will work in anything more complex than a fly.”
But much of the coverage bordered on the tipsy. The headline in Sinclair’s hometown paper, Sydney’s Daily Telegraph, nicely captured the rosy glow: BETTER RED THAN DEAD, STUDY FINDS.
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Nutraceutical makers wasted no time introducing resveratrol pills that presumably would do for people what the Harvard group had done for yeast. One of the first to play up resveratrol as a possible CR mimetic was Bill Sardi, a writer of consumer health books who interviewed Sinclair at Harvard soon after the yeast study was completed. There were already a number of resveratrol supplements on the market at that point, but Sardi had heard that most of them contained little or no intact molecules of the compound, which quickly degrades when exposed to air. Seizing the day, he organized a company to sell pills that reportedly contain resveratrol whose chemical integrity is maintained by a special encapsulation technology and other tricks—the brand name is Longevinex.
Sardi briefly enlisted Sinclair as a paid consultant, but the arrangement didn’t last long. After a dustup over Longevinex’s use of Sinclair-attributed quotes on its Web site, the Harvard researcher parted ways with the nutraceutical maker in late 2003 and went on to cofound Sirtris, which planned to develop FDA-approved drugs instead of dietary supplements.
To many scientists, however, the excitement about resveratrol, and especially the buzz about its potential to slow human aging, seemed somewhere between naïve enthusiasm and reckless hype. For one thing, Sinclair’s findings hadn’t yet been corroborated by other researchers. And even if they held up, it wasn’t clear that resveratrol’s effects on yeast could be extrapolated to the much more complex process of human aging.
And then there was the lingering two-part question that arose when resveratrol was first linked to the French paradox in 1992: What exactly does the compound do inside cells, and can that mechanism, whatever it is, really explain the benefits attributed to resveratrol?
Unlike the kind of experimental drugs pharmaceutical developers generally prefer to work with, which single out and primarily bind to a single, well-understood molecular target in the body, resveratrol promiscuously consorts with a confusing welter of targets—it’s a “dirty drug,” as researchers say. That made its mechanism of action extremely difficult to sort out. The fact that it’s an antioxidant, for example, might mean that it had extended yeast life span in Sinclair’s study by blocking free radicals, not by stimulating SIRT1. That would be nice, but it wouldn’t represent a potential breakthrough in human medicine, nor would it support the idea that resveratrol is a CR mimetic. As we saw in chapter 2, antioxidants have repeatedly failed to slow aging in mammals.
To be sure, Sinclair’s group addressed the dirty-drug issue in their study. For instance, they reported that resveratrol failed to extend life span in yeast cells with disabled SIR2 genes—evidence that the compound’s anti-aging effect was mainly exerted via SIR2.
They also presented a clever evolutionary argument to support the idea that resveratrol is a CR mimetic, and that sirtuins are a major conduit of its anti-aging effect. The theory rested upon the fact that plants churn out resveratrol and other polyphenols when stressed by things like nutrient deprivation, dehydration, and diseases. Indeed, wines with the highest levels of resveratrol are typically made from grapes grown in cool, moist areas in which fungal infections often occur. Thus, plant-eating animals may have evolved inner systems to register the presence of such stress-induced compounds in their food in order to get an early warning of imminent food shortages. The animals could then preventively gear up their CR-like stress defenses before hard times hit, perhaps boosting their chances of surviving. According to this “xenohormesis” theory, sirtuins represent the core of the early warning system—they trigger anti-aging effects when exposed to stress-induced plant compounds, as well as when activated by CR.
But the skeptics wanted confirmatory data, not theorizing. And soon after the famous yeast study appeared, the two most prominent skeptics, Brian Kennedy and Matt Kaeberlein, reported that they had tried to confirm Sinclair’s findings but had gotten totally different results.
Their names may ring an ironic bell. Kennedy had helped initiate the Guarente lab’s aging research a decade earlier, and Kaeberlein, another alumnus of the lab, had played a leading role in singling out SIR2 as a yeast gerontogene. After leaving MIT, they’d both wound up launching academic careers at the University of Washington in Seattle, where they’d joined forces to conduct further research on anti-aging genes. But a number of their experiments at the West Coast school had cast doubt on some of the Guarente lab’s studies, particularly ones indicating that CR’s effects are mainly channeled through SIR2. Thus, the Seattle researchers were also skeptical about the related research by Sinclair indicating that resveratrol mimics CR by stimulating SIR2. Not surprisingly, they decided to investigate the compound’s effect on yeast themselves.
The results didn’t make for chummy Guarente lab reunions. In a 2005 paper coauthored by Elixir’s Peter DiStefano, Kennedy and Kaeberlein reported that resveratrol failed to extend life span in three different yeast strains. Further, only one of several different test-tube assays of SIRT1 activity that they employed indicated that resveratrol stimulated SIRT1—the single assay that yielded data like Sinclair’s happened to be the Biomol one that the Harvard group had primarily used.
The Seattle researchers attributed the discrepancy between their test-tube findings and Sinclair’s to a special molecule incorporated into Biomol’s assay. Called Fluor de Lys, it generates a fluorescent glow when the SIRT1 enzyme removes acetyl groups from proteins, providing a readout of the enzyme’s activity. Their data suggested that resveratrol stimulates the enzyme only in the presence of Fluor de Lys. In other words, a reagent that was supposed to act as a kind of uninvolved witness to SIRT1-related chemical reactions in the test tube seemed to have gotten mixed up in the reactions as a major player. Kaeberlein and Kennedy concluded that resveratrol’s reported SIR-boosting effect was probably a test-tube “artifact” rather than a general phenomenon that occurs in living cells.
Their report appeared in tandem with a similar study led by University of Wisconsin biochemist John Denu. His analysis indicated that various kinds of fluorescing molecules—not just Fluor de Lys—somehow combine forces with resveratrol to amplify the SIRT1 enzyme’s action in the test tube. But Denu, who later served on Sirtris’s scientific advisory board, was less starkly skeptical about Sinclair’s take on resveratrol. In fact, he proposed that unidentified natural molecules might interact with resveratrol and SIRT1 in cells in the same way that the fluorescing molecules do in the test tube. That implied Sinclair’s test-tube results weren’t just an artifact—surprisingly, they might actually emulate what goes on in cells.
But the Seattle team’s critiques went way beyond the minutiae of test-tube assays. Their doubts largely stemmed from studies with various strains of yeast that indicated SIR2’s purported link to CR is tenuous at best. For instance, in one strain they studied, CR boosted life span even when SIR2 genes were disabled, contradicting Guarente’s hypothesis that CR’s effects are primarily channeled through SIR2 in yeast. After conducting many such experiments with different strains, they concluded that the effects of CR and SIR2 are channeled through different, “parallel” biochemical pathways in yeast and, perhaps, animals too. Thus, in their view even if resveratrol did boost sirtuin genes in yeast and other organisms, it probably wouldn’t elicit CR’s anti-aging magic.
Neither Guarente nor Sinclair was fazed by the attacks. By 2004 they had separately moved on from the study of yeast aging—the main subject of their arguments with the Seattle scientists—to investigate sirtuins in animals. Sinclair collaborated with Brown University’s Marc Tatar and the University of Connecticut’s Stephen Helfand in a study showing that resveratrol can modestly extend the lives of fruit flies and nematodes by stimulating their SIR2-like genes.
Meanwhile, Guarente jumped to mice. His lab reported that the tendency of calorie-restricted rodents to become more active, as if impelled to forage more, is absent in mice with SIRT1 deficiencies—an indication that SIRT1 mediates CR effects in the rodents. In another study, his group showed that SIRT1 comes into play in calorie-restricted mice to help suppress formation of new fat cells and to draw down fat reserves. The MIT group also reported that resveratrol, acting via SIRT1, had similar effects on fat reserves—a sign that Guarente and Sinclair were forming a common front against their University of Washington critics.
Important support for the Guarente/Sinclair side came from experiments in various labs suggesting that one of SIRT1’s main functions is to help cells stay alive when stressed. A collaborative study by Guarente and Columbia University’s Wei Gu in 2001 had raised that possibility, and three years later a group at Washington University in St. Louis led by Jeffrey Milbrandt supported it by showing that SIRT1 helps prevent neurons from withering after nervous-system injury—an effect reportedly abetted by resveratrol. Researchers at the New Jersey School of Medicine in Newark added a study showing that boosting SIRT1 in the heart cells of mice shields their cardiac tissues from free radical damage.
Molecular details of the protective effect were elucidated in another study, coauthored by Sinclair, showing that SIRT1 inhibits genes that sometimes push stressed cells toward suicide. But why, you might ask, would any of our cells, the precious little dears, ever do themselves in? The answer is simple: They’re heroically sacrificing themselves to save our lives. The deadly risk springs from the continual damaging of DNA by free radicals and other insults. Such damage is usually repaired, but in some cases it isn’t, and on rare occasions it can permanently switch on progrowth genes that lead to the runaway cell division of cancer. To guard against that catastrophe, key genes, most prominently p53 (the two-faced anticancer gene we ran across in chapter 1), are set to induce a kind of orderly self-destruction, called apoptosis, when signs of major damage crop up in cells.
As we age, it seems that many of our cells, increasingly deranged by the ravages of time, wobble ever more perilously along a tightrope between ill-controlled progrowth mode, which tends toward cancer, and hurtful antigrowth mode, which abets aging by robbing cells of their youthful powers of renewal and tips them toward suicide. According to studies led by Guarente, Sinclair, and other scientists, SIRT1 inhibits p53 and other genes that trigger apoptosis. Thus, revving up SIRT1 by means of calorie restriction or CR mimetics might slow aging in part by coaxing stressed cells back from the apoptosis cliff. SIRT1 also has been found to directly induce cells’ resistance to stress by enhancing the action of a key stress-response regulator called heat shock factor 1—revving it up is the cellular equivalent of donning body armor.
As all this came into focus, however, Kennedy and Kaeberlein continued to sound a drumbeat of dissonance that reverberated throughout gerontology. The strife seemed to fall somewhere between a Greek tragedy and a lavishly intricate soap opera—a family feud in which two stubborn brothers (Kennedy and Kaeberlein) had turned against their equally headstrong father (Guarente) and brother (Sinclair). The embattled patriarch was characteristically wry when I asked him about the unfolding drama in 2006. “Without naming names, I tell my audiences at conferences that the good news about my lab is that I train students to be iconoclasts,” Guarente said. “The bad news is that I’m the nearest icon.”
Actually, he didn’t need to train Kaeberlein, who, like Sinclair, is a natural at the sweet science of clobbering icons. (Kennedy, the statesmanlike, quietly intense elder brother in the sirtuin saga, seems less comfortable in the contentious role that his findings with Kaeberlein have obliged him to take.) Blunt, bright, headstrong, and driven, Kaeberlein didn’t take to his parents’ Lutheran faith while growing up in Seattle—in eighth grade he was pointedly absent at his church confirmation ceremony. In high school he aspired to heavy-metal rock fame with pierced ear and long, flowing hair, a look that led to an imbroglio with the basketball coach soon after he joined the team. Free at last after graduating, he put college on the back burner to work the three A.M. shift at United Parcel Service. Three years later, he enrolled in a community college, then decided to go into science after hearing the Darwinian case against creationism laid out in a basic biology course—its rigorous detonation of received wisdoms appealed greatly. After majoring in math and biochemistry at Western Washington University, he went to MIT for graduate studies. He signed up to work in Guarente’s lab after attending a seminar on its research—Kaeberlein was especially taken by Sinclair’s work, proving yet again that truth is more ironic than fiction.
By 2006, the two sides in the sirtuin dispute were blasting away at each other in acidly worded commentaries, letters to editors, and research reports that purported to correct sins of omission in each other’s work. As is often the case in academia, the points of contention—most of which are still subject to debate at this writing—became increasingly arcane as the emotional temperature rose. One of the most hotly contested issues was the proper amount of sugar to give yeast cells in CR experiments. But there was nothing esoteric about the fight’s importance—conceivably, both a Nobel Prize and a pharmaceutical fortune hung in the balance.
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When Clive McCay initiated his pioneering research on CR in the 1920s, his animal of choice for a quick life-span study—the kind that could be carried out by a junior researcher with limited resources—was brook trout. Following in his footsteps, Italian scientists led by Dario Valenzano at the Scuola Normale Superiore in Pisa set out in 2005—two years after Sinclair’s high-profile yeast study with resveratrol—to test the compound’s anti-aging power in the turquoise killifish. Found in African seasonal ponds that disappear within weeks after rains, the animal lives only about three months.
The researchers tried three doses of resveratrol on different groups of the fish beginning at four weeks of age; in all, 110 fish were fed the substance. Only six weeks later it was evident that the fish on the two higher doses were living longer, and by the end of the study the ones on the highest dose had attained a maximum life span 59 percent greater than the control group had.
Equally arresting, the fish on resveratrol were zipping about in their tanks in a youthful way long after the control animals had lost their get-up-and-go. At nine weeks of age, the resveratrol group’s average swimming speed was more than three times greater than that of the controls. The study, reported in February 2006, got little attention in the press. But it was arguably more provocative than anything that had appeared before on resveratrol—it marked the first time the compound’s anti-aging promise had been observed on our side of the animal world’s great backbone divide.
Mice were obviously next on the list. Sinclair had begun readying a mouse study with resveratrol before the hubbub about his 2003 yeast study had died down. He had discovered a good place to get the rodents: a nondescript, unmarked building tucked away on a side street near Baltimore’s waterfront, where the National Institute on Aging maintains a large colony of lab mice for research. He also knew an ideal collaborator for the study: NIA researcher Rafael de Cabo, a burly, convivial native of Spain known for groundbreaking studies on CR and for having a deft touch with rodents. (The latter is not a trivial virtue in biomedical research.) De Cabo had closely tracked the resveratrol story and, though skeptical that the compound would extend life span in mice, was eager to collaborate with Sinclair to test its ability to mimic CR effects in mammals.
But the two were stymied. As a junior scientist living from one smallish grant to the next, Sinclair lacked the twenty thousand dollars needed to pay for the hundreds of rodents required to undertake the ambitious multipart study he designed with de Cabo. Swinging for the fences, they planned to examine the effects of two different doses of the compound on groups of mice fed both high-fat and normal diets—control groups would be required too, of course. Every week that went by with the study on fiscal hold raised the odds that Sinclair would be left in the dust in what was shaping up as the most important research race of his career.
Then one day a man named Tom LoGiudice phoned the Sinclair lab out of the blue to ask about resveratrol. As usual, Sinclair stopped what he was doing to take the call. Unlike many scientists, he genuinely enjoys talking to nonscientists about his work and has a gift for lucid explanation. LoGiudice turned out to be foreman at the U4EA (“euphoria”) Ranch, a two-hundred-acre spread near Thousand Oaks, California. An affable Brooklyn native who’d gone west during the Age of Aquarius in an aerodynamically incorrect, hand-crafted double-decker VW van, he had phoned Sinclair on behalf of the ranch’s owner, Hank Rasnow. A reserved eighty-five-year-old, Rasnow was thinking about taking resveratrol pills and wanted to know more about their pros and cons.
While answering LoGiudice’s questions, Sinclair mentioned his frustrated desire to test the compound in mice. A few days later, LoGiudice, who had a lively personal interest in resveratrol (regular doses of it even livened up his old dog, he told me), arranged for his boss to talk directly with Sinclair. Although Rasnow had never funded research before, he was so taken by the young Harvard scientist that he mailed him a check for twenty thousand dollars immediately after hanging up. Rasnow explained to me in an interview that he had “an eighty-five-year-old passion for longevity, and David sounded like he was really onto something.”
Some months later, Sinclair got another call from the U4EA’s enterprising foreman. LoGiudice told him that Rasnow happened to know businessman Paul Glenn, a longtime supporter of aging research, and was prepared to help Sinclair approach Glenn for a major grant. Sinclair jumped on a flight to California. Over an impromptu lunch served on paper plates at a condo Rasnow owned in Ventura Beach, the young scientist told Glenn about his dream of setting up a major biogerontology center at Harvard. An alumnus of Harvard Law School, Glenn liked the idea, and in early 2005 the Glenn Foundation for Medical Research in Santa Barbara, California, awarded $5 million to Harvard Medical School to launch a center on the biology of aging, with Sinclair as its founding director.
Meanwhile, Sinclair pushed ahead with the crucial mouse study. He tapped an energetic postdoc named Joseph Baur to coordinate its twenty-seven authors, including experts on rodent pathology, biomarkers, genetics, statistics, and calorie restriction. The mice available for the study were a year old when it got under way—middle-aged for a mouse. Initiating CR at that age typically yields only modest life-span extension at best, and thus the researchers were running a sizable risk that even if resveratrol could mimic CR in mice, their study might fail to show significant anti-aging effects. But using mice whose lives were nearly half over made for a relatively short life-span study. And that was important: Word came through the grapevine that a rival team led by a French scientist named Johan Auwerx had launched a similar study.
To the Harvard group’s relief, their mice quickly began generating publishable results. Within three months there were clear signs that when put on fattening diets, mice on resveratrol tended to live longer than undosed control animals. The scientists assembled a paper on the study’s initial findings when the mice were about 2.2 years old, at which point resveratrol had cut the mortality risk from the high-fat diet by 31 percent.
Resveratrol also induced a number of CR-like effects. For instance, even though the overfed mice on resveratrol were obese, their livers and hearts appeared to be in really good shape—even better than the organs of normal-weight control mice on regular diets. Resveratrol also prevented glucose levels and insulin sensitivity from trending toward diabetes in mice on the fattening diet. And a gene-chip analysis revealed that resveratrol emulated CR-like changes in nineteen of thirty-six metabolic pathways while opposing 94 percent of the changes associated with the high-fat diet.
Sinclair was suddenly famous all over again—echoes of the study were still resounding two years after its publication in November 2006 when Barbara Walters, glass of red wine in hand, interviewed him about his work for a special ABC report on anti-aging research. To be sure, very high doses of resveratrol were required to induce the CR-like effects. Equaling it in an average-sized person was estimated to require the daily consumption of three hundred glasses of wine. But that didn’t lessen the buzz. The New York Times headlined its front-page story on the study, YES, RED WINE HOLDS ANSWER. CHECK DOSAGE. Chip Bok, a cartoonist at the Akron Beacon Journal, comically memorialized the study by picturing a rodent connoisseur commenting on the “timid nose” of the stuff he’s sipping while a fellow mouse covers his eyes, exclaiming, “I can’t believe you’re drinking Merlot.”
While giving pause to wine drinkers, the dosage issue didn’t diminish the study’s biological significance. After all, Sirtris, Sinclair’s company, was based on the premise that it would probably take SIRT1 activators more powerful than plain resveratrol to deliver the kind of therapeutic punch needed to ameliorate diseases and win FDA approval. And the team at Sirtris was already making fast progress in developing such drugs.
But some of the study’s findings did provide fodder for skeptics. For instance, it showed that resveratrol affected CR-related enzyme-making genes besides SIRT1, including a well-known one called AMPK that’s known as a key conduit for metformin’s health benefits. (Metformin is the diabetes drug that increases insulin sensitivity.) That suggested SIRT1 may be only one of several of resveratrol’s molecular targets in cells that switch on the red-wine ingredient’s CR-like effects. If that were true, Sirtris’s pursuit of SIRT1 activators might yield little of value.
Further, the study didn’t establish that resveratrol slows normal aging. Rather, it showed that resveratrol opposes the effects in mice of awful diets in which 60 percent of calories come from fat. (By comparison, about 34 percent of a typical U.S. citizen’s calories come from fat, according to federal surveys.) Thus, strictly speaking, the study showed that resveratrol promises to ameliorate certain diseases caused by pigging out, not to retard aging.
But even the skeptics had to concede that something else quite exciting had happened to the mice on resveratrol: Like the killifish that got the compound, they became livelier over time, seeming to defy the usual slowing with age. As mentioned in the prologue, I got a chance to see this striking phenomenon during a visit to the NIA’s Baltimore lab in mid-2006, several months before the study was published.
As I watched, Kevin Pearson, a scientist at the lab, slowly lowered two seriously pudgy old mice onto a device resembling a slowly spinning rolling pin—called a rotarod, it’s used to measure endurance and motor skill. Both had been on high-fat diets, but one had also been taking resveratrol. When the rodents touched down, they instinctively began walking in place like log-rolling lumberjacks. The spinner soon accelerated, however, forcing them to run harder until they maxed out and fell harmlessly onto a plastic tray below. Pathetically trembling with exertion, the nonresveratrol mouse dropped after 81 seconds.
But the resveratrol mouse was still going strong at 100 seconds, at 120 seconds, 130, 140. When it finally fell onto the tray after 144 seconds, I was playing the theme song from Chariots of Fire in my head. Even fit, young mice rarely last that long. And the rotarod performance gap had widened during the course of the study between the dosed and undosed mice, indicating that resveratrol had had a cumulative benefit. In fact, mice that had been on resveratrol for a year could stay on the rod nearly twice as long, on average, as the control animals.
Two weeks after the Nature paper on resveratrol came out, Auwerx’s group in Strasbourg, France—the competition Sinclair had worried about—followed up with a report that confirmed and illuminated this invigorating effect. The French researchers had put their mice on doses up to eighteen times higher than Sinclair’s group had. Again, the compound was shown to make mice immune to many of the deleterious effects of high-fat diets. But Auwerx’s very high doses induced an additional effect: Mice on resveratrol could chow down on rich diets without getting fat. The animals also could run about twice as far on a treadmill as counterparts that weren’t on resveratrol. Under the microscope, their muscle fibers appeared to have been remodeled by resveratrol in the same way that they would have been by lots of exercise.
Importantly, the French team’s data indicated that the performance enhancement sprang from resveratrol’s stimulation of SIRT1 rather than one of its other effects in cells—very good news for Sirtris, which had helped to fund the study. Let’s briefly zoom in on this SIRT1-mediated supermouse effect, which might explain a lot of things about resveratrol’s effects in us mammals.
Auwerx’s group showed that resveratrol indirectly activates an enzyme called PGC-1-alpha, which carries out the heavy lifting of the performance enhancement. (Specifically, resveratrol revs up SIRT1, which in turn stimulates PGC-1-alpha.) PGC-1-alpha had entered the sirtuin picture a year earlier in experiments that had riveted attention on SIRT1’s effects on mitochondria, cells’ power plants. This line of research, spearheaded by Harvard Medical School’s Pere Puigserver, a Sirtris adviser, revealed that during calorie restriction, PGC- 1-alpha, juiced up by SIRT1, engenders formation of new mitochondria in muscles. This chain of events probably explains why mice on high doses of resveratrol became elite rodent athletes. Boosting PGC-1-alpha also induces mitochondria to burn stored fat instead of glucose, which may have contributed to the ability of Auwerx’s resveratrol mice to eat rich diets without getting fat.
Intriguingly, Auwerx’s group also reported that they had linked certain variants of the human SIRT1 gene to a high metabolic rate in people, possibly protecting those carrying such variants from at least some of the deleterious effects of rich diets—a kind of natural version of what high doses of resveratrol do in mice.
Might such people also be endowed with the athletic potential of resveratrol-dosed mighty mice? And could weekend warriors become elite athletes by ingesting large doses of resveratrol?
At this writing, there are no good answers to these questions. But I wouldn’t be surprised to find out that resveratrol can have performance-enhancement power in people. Just before the two mouse studies appeared, I was talking to Sinclair about the 2006 U.S. Open, where thirty-six-year-old tennis star Andre Agassi ended his career in tears after losing to twenty-five-year-old Benjamin Becker. When I asked him about Agassi’s loss to a young guy who wasn’t even ranked in the top one hundred players, he grinned and shot back, “Agassi should have been taking resveratrol.”