Alcohol Use Affects Levels of Cholesterol Regulator through Epigenetics

In an analysis of the epigenomes of people and mice, researchers at Johns Hopkins Medicine and the National Institutes of Health report that drinking alcohol may induce changes to a cholesterol-regulating gene.

The findings suggest that these changes to the gene, known as PCSK9, may explain at least some of the differences in how cholesterol is processed in people who drink alcohol, or may affect those taking a relatively new class of PCSK9 cholesterol-lowering drugs designed to reduce LDL cholesterol, commonly known as bad cholesterol.

Epigenomics is the study of potentially heritable changes in gene expression caused by “environmental” or other processes that do not involve changes to underlying DNA itself.

In a report on the study, published Aug. 29 in Molecular Psychiatry, the researchers caution that their analysis looked at and found only associations between alcohol consumption and epigenetic changes, not cause-and-effect, and that more studies are needed to demonstrate any direct link.

“Small amounts of alcohol are well known to be seemingly protective against heart disease in some studies, whereas heavy, chronic alcohol use can have detrimental effects on the liver as well as on the cardiovascular system,” says Zachary Kaminsky, Ph.D., assistant professor of psychiatry and behavioral sciences. “Regulation of PCSK9 seems to correlate with this pattern and may be a significant underlying factor behind the variations in the relationship between cholesterol and cardiovascular disease when it comes to alcohol use.”

For their study, the researchers sought to measure how environment, in this case alcohol use, might lead to changes in which genes are expressed — turned on or off — when alcohol is consumed.

They did so by examining information from so-called DNA “chips” known as microarrays that can reveal which genes have chemical methyl groups added across the whole genome. These chips looked at about 450,000 methyl groups at a time. Such “methylation” affects the level of gene expression.

The researchers used several different sets of data. One set of data had DNA from the brains of 23 deceased people with documented alcohol dependence or abuse as compared to 23 healthy controls, all subjects whose DNA was gathered at The University of Sydney in Australia. Another set of data compared DNA from blood samples of 68 people who had documented alcohol dependence with 72 healthy controls recruited by the U.S. National Institute on Alcohol Abuse and Alcoholism (NIAAA). And a third set of data from the U.S. National Institute of Child Health and Human Development compared brain DNA samples from 29 people who had major depression with 29 nondepressed controls, some of whom were known to abuse alcohol.

When the investigators cross-compared epigenetic data from the three sets of data to find out what changes occurred in common in all three data sets and what changes did not, the common factor highlighted the gene PCSK9.

The researchers then looked at DNA from blood samples from a different NIAAA study, which enrolled people seeking treatment for alcohol dependence, and measured their PCSK9 levels. This group was composed of 90 people with documented alcohol dependence. The researchers found the higher the methylation at the PCSK9 gene, the higher the PCSK9 level in blood.

In another set of experiments, the researchers fed mice alcohol in their diets for 10 days along with a single-binge feeding — which is similar to what we see in people with alcohol use disorder — and compared their epigenetic profiles to mice not fed alcohol.

They took brain, blood and liver samples and analyzed the DNA for methyl groups on the PCSK9 gene and PCSK9 protein levels in liver. They found that in mice fed alcohol, methylation of the PCSK9 gene increased in all the tissues measured. But the mice given alcohol had lower PCSK9 protein levels in the liver.

Kaminsky says results from the liver samples puzzled them. These samples had many more methyl groups on PCSK9 but not the increased protein levels that would be expected. They looked back in human liver samples from people with alcohol dependence who underwent a liver transplant and noticed a similar pattern: more methylation on PCSK9 and unexpectedly lower PCSK9 protein levels. In samples from people who abused alcohol, the researchers detected that PCSK9 gene expression was only a third of the level in people who didn’t abuse alcohol.

“Given that alcohol is metabolized by the liver and can cause liver damage if used in large amounts over long periods of time, this result made immediate sense—the liver cells were dying, which is why we didn’t see the high levels of PCSK9 protein as would be expected,” says lead author of the study Falk Lohoff, M.D.,  of the NIAAA. The researchers confirmed this by looking at a set of human tissue samples from patients with end-stage liver disease.

Kaminsky and Lohoff concluded that PCSK9 regulation by alcohol seems to be dynamic, with small amounts of alcohol leading to lower PCSK9 methylation and gene expression, while chronic heavy alcohol use leads to higher methylation and higher gene expression, with ultimately low PCSK9 protein levels due to liver damage.

In people, PCSK9 is found at its highest levels in liver, but is also found in other tissues, such as brain and blood. PCSK9 binds to the “bad cholesterol” receptors and blocks uptake and breakdown of bad cholesterol by cells, leading to accumulation in the bloodstream, where it then presumably clogs arteries.

A new class of cholesterol-lowering drugs, for those who either can’t tolerate statins or for whom statins don’t work, reduces PCSK9 protein levels and helps take bad cholesterol out of the bloodstream. The drugs are expensive and carry some side effects.

“So far, the safety and interaction of PCSK9 inhibitors and alcohol use hasn’t been studied, but this is an important area of research given how common alcohol use is,” says Lohoff.  “Our finding of a PCSK9-alcohol link is intriguing, since PCSK9 inhibitors might be particularly useful in lowering bad cholesterol for people who have high PCSK9 levels due to drinking.” Also, he says, PCSK9 inhibitors aren’t metabolized by the liver, which is often damaged in individuals with heavy chronic alcohol use, meaning they wouldn’t put an extra strain on the liver as some other medications might.

Among the limitations of their study, the researchers say, is that they only looked at tissue DNA samples at one point of time. Because of this, they don’t know if the epigenetic changes they observed are stable over time or reversible.

Additional authors on the study include Ilenna Jones of Johns Hopkins University; Jill Sorcher, Allison Rosen, Kelsey Mauro, Rebecca Fanelli, Reza Momenan, Colin Hodgkinson, Melanie Schwandt, David George, Andrew Holmes, Zhou Zhou, Ming-Jiang Xu, Bin Gao, Hui Sun, Monte Phillips, Christine Muench and George Koob of the NIAAA; and Leandro Vendruscolo of the National Institute on Drug Abuse.

Intramural funding for the study was provided by the NIAAA (ZIA-AA000242).

Source : The Johns Hopkins University

NIH Findings Link Aldosterone with Alcohol Use Disorder

A new study led by scientists at the National Institute on Alcohol Abuse and Alcoholism (NIAAA), part of the National Institutes of Health, demonstrates that aldosterone, a hormone produced in the adrenal glands, may contribute to alcohol use disorder (AUD). The novel research, conducted in collaboration with a team of investigators in the United States and Europe, appears in the journal Molecular Psychiatry.

“ This intriguing work – conducted in humans as well as two other species — provides a compelling example of how basic and preclinical research is translated into studies with direct relevance to humans,” said NIAAA Director George F. Koob, Ph.D., a co-author of the study. “It also demonstrates how interactions between the brain and the endocrine system may serve as potential targets for the development of new AUD medications.”

Aldosterone helps regulate electrolyte and fluid balance by binding to mineralocorticoid receptors (MRs), which are located throughout the body. In the brain, MRs are mainly located in the amygdala and the prefrontal cortex — two key brain areas involved in the development and maintenance of AUD. In AUD, amygdala dysfunction heightens activation of brain stress systems resulting in anxiety and other negative emotions, while disruption of the prefrontal cortex impairs executive control systems involved in the ability to make decisions and regulate one’s actions, emotions, and impulses.

“Previous studies, including a pilot clinical study that we published in 2008, illustrate the possible role for aldosterone in AUD,” said senior author Lorenzo Leggio, M.D., Ph.D., chief of the Section on Clinical Psychoneuroendocrinology and Neuropsychopharmacology, a NIAAA intramural laboratory jointly funded with the National Institute on Drug Abuse, also part of NIH. “Our overall hypothesis has been that aldosterone may play a role in AUD via its MR receptor and that this neuroendocrine pathway may be particularly important in anxiety, stress and stress-induced alcohol drinking.”

The new report describes three separate studies, conducted with non-human primates, rats, and humans, that investigated the potential contribution of the aldosterone/MR pathway to AUD.

In a study conducted with non-human primates, the researchers found that animals which self-administered alcohol every day for six to 12 months had significantly higher blood aldosterone concentrations, compared with the concentrations measured prior to alcohol administration. In fact, the aldosterone increase observed at six months remained high after 12 months of continued drinking, and did not increase further, suggesting that blood aldosterone concentrations become regulated at a new set-point under daily alcohol consumption. Furthermore, the researchers found that in the amygdala, lower MR gene expression – the process of making functional MR protein from the MR gene – was associated with increased alcohol drinking in the animals.  Similar results were not found in the prefrontal cortex.

In a study conducted in a rat model of AUD, the researchers found that lower levels of MR gene expression in the amygdala (but not in the prefrontal cortex) were associated with increased anxiety-like behavior and compulsive drinking, compared to rats not exposed to alcohol. Conversely, higher levels of MR gene expression in the amygdala were associated with decreased anxiety and less compulsive alcohol drinking. Overall, these findings suggest that higher MR gene expression in the amygdala may protect against compulsive drinking or, conversely, that lower levels of MR gene expression may increase vulnerability for anxiety-related compulsive drinking in the rat AUD model.

“The amygdala is a key regulator of emotion and stress and its adaptation to aldosterone signaling due to chronic alcohol drinking illustrates fundamental adaptations across organ systems that underlie the pathological state associated with AUD,” said Kathleen Grant, Ph.D., study co-author and head of the Division of Neuroscience, Oregon National Primate Research Center at Oregon Health & Science University, Portland.

In a human study of about 40 individuals undergoing treatment for AUD, the researchers found that blood aldosterone concentrations were higher in individuals who continued drinking during the 12-week period, compared with those who were abstinent during the same time frame. For those who drank, the researchers found that aldosterone concentrations correlated with the amount of alcohol consumed during the study –  higher drinking levels were associated with higher aldosterone concentrations. The researchers also found that increasing blood aldosterone concentrations correlated with increasing levels of both alcohol craving and anxiety.

Taken together, the researchers conclude that the findings provide support across three different species for a relationship between alcohol misuse, AUD, and specific changes in the aldosterone/MR pathway marked by increased circulating aldosterone and decreased mineralocorticoid receptor gene expression in the amygdala.

“Future studies should further investigate the mechanisms underlying the relationship between alcohol drinking and the aldosterone/MR pathway and whether this pathway might be targeted for the development of new pharmacotherapies for AUD,” said Dr. Leggio.

Source : National Institutes of Health (NIH)

NIH Competition Seeks Wearable Device to Detect Alcohol Levels in Real-time

The National Institute on Alcohol Abuse and Alcoholism, part of the National Institutes of Health, is once again challenging the biotech community to design a wearable device capable of measuring blood alcohol in near real-time. The ideal device would be capable of measuring alcohol concentration in the blood or interstitial fluid that surrounds the body’s cells, which differs from existing technology that detects alcohol released through the skin in sweat or vapor. The creators of the winning prototype will be awarded $200,000 and second place will receive $100,000 through Challenge.gov, which lists federal incentive prizes and competitions.

“I expect tangible breakthroughs in real-time alcohol-sensing technology through this competition,” said NIAAA Director George F. Koob, Ph.D. “Creative solutions could include the adaptation and miniaturization of technologies such as spectroscopy or wave technology or other designs. I think we can build on the success of our first challenge, which made important strides in improving transdermal alcohol sensing.”

Many alcohol studies rely on self-report to measure drinking, which can be unreliable. The wearable alcohol biosensor competition was conceived primarily to aid researchers in collecting more accurate data. This could help in the understanding and treatment of alcohol use disorder, as well as conditions affected by alcohol use, such as liver disease and HIV/AIDS. In addition to its potential for researchers, alcohol biosensors could also be a tool for consumers who wish to track their own personal drinking patterns. While initiating this second challenge, NIAAA hopes to continue to collaborate with the winners of the first competition to develop a viable prototype to use in NIAAA studies.

“We have learned that there is real interest in the private sector around wearable alcohol biosensors, and that innovation using distinct means of alcohol detection are on the horizon,” said Kathy Jung, Ph.D., director of NIAAA’s Division of Metabolism and Health Effects, and co-leader of the competition.

“We want to continue to harness the power of the private sector because if alcohol biosensors become a part of the ‘wearable toolbox,’ then tangible new opportunities will become available that will profoundly affect the field of alcohol research.”

Competition submissions (a working prototype, data proving functionality/reliability, and photos/videos) will be accepted until May 15, 2017. Judging is expected to take place May 16, 2017 – July 26, 2017, with winners announced on or after August 1, 2017. More details about the competition here: http://niaaa.nih.gov/research/challenge-prize

In May 2016, NIAAA announced that BACTrack(link is external) had won the first Wearable Alcohol Biosensor Challenge with its Skyn prototype. The wrist-worn device detects BAC using a fuel cell technology similar to that in devices used by law enforcement for roadside alcohol testing. MILO, Inc.(link is external), won second prize with its design using disposable cartridges to continuously track BAC.

Competition contacts are M. Katherine Jung, Ph.D., acting director, NIAAA Division of Metabolism and Health Effects; and F.L. Dammann, special assistant to the executive officer, NIAAA: NIAAAChallengePrize@mail.nih.gov(link sends e-mail).

Scientists Propose Neuroscience Framework for Diagnosing Addictions

“The assessment framework that we describe recognizes the great advances that continue to be made in our understanding of the neuroscience of addiction.”

George F. Koob, Ph.D., Director, NIAAA

Scientists at the National Institute on Alcohol Abuse and Alcoholism (NIAAA), part of the National Institutes of Health, propose using an assessment tool to diagnose addictive disorders that considers addiction-related behaviors, brain imaging, and genetic data. According to a new review article, the Addictions Neuroclinical Assessment (ANA) would facilitate future understanding of the origin of addiction at a biological level, and could ultimately lead to more effective individualized treatments for addictions.  The review appears online in the journal Biological Psychiatry(link is external).

The ANA would include behavioral assessment of three functional processes considered most relevant to addiction: altered perception of an object or event by drug-taking that makes it seem more attractive or important (incentive salience), increased negative emotional responses (negative emotionality) when drugs are no longer available, and deficits in organizing behavior toward future goals (executive functioning).  The authors note that the selection of these processes is based on our understanding of the neuroscience of addiction.

“The assessment framework that we describe recognizes the great advances that continue to be made in our understanding of the neuroscience of addiction,” said NIAAA director George F. Koob, Ph.D., a co-author of the review.  “These advances underscore how much we know about the core neurobiological manifestations of addiction in people.”

The classification of addictive disorders typically is based on the substance of abuse, for example, alcohol versus cocaine, and the presence or absence of various symptoms, such as difficulty controlling consumption or craving for a substance. But the authors note that differences and similarities between addictions are not constrained by the substance of abuse. They therefore propose a dimensional framework that incorporates behavioral measures with brain imaging and genetic data.

“We currently approach addiction diagnosis as a ‘yes or no’ proposition,” added first author Laura E. Kwako, Ph.D., a researcher in the Office of the NIAAA Clinical Director.  “The Addictions Neuroclinical Assessment that we propose leverages knowledge of the neuroscience of addiction to identify a package of assessments that may be used to more precisely identify different subtypes of addictive disorders.”

In describing the potential usefulness of their proposed assessment tool, the authors draw a comparison to how clinicians combine cellular, genetic, molecular, and imaging information, with clinical history to make cancer diagnoses.  They note that by integrating this information, cancer clinicians have been able to tailor the treatment of certain cancers to the specific characteristics that an individual with cancer might have.

“Although addiction treatment options exist, and indeed continue to expand, they are limited by significant within-diagnosis heterogeneity and by a failure, thus far, to define addictive disorders by their neurobiological substrates,” said Dr. Koob.

The researchers emphasize the need to also collect brain imaging and genetic information from patients. Although they currently have little utility in the clinic, the researchers hope that the comprehensive measures will facilitate future understanding of the origin of addiction at a biological level.

The National Institute on Alcohol Abuse and Alcoholism, part of the National Institutes of Health, is the primary U.S. agency for conducting and supporting research on the causes, consequences, prevention, and treatment of alcohol use disorder. NIAAA also disseminates research findings to general, professional, and academic audiences. Additional alcohol research information and publications are available at: http://www.niaaa.nih.gov.