Posted on by Dr. Francis Collins
The coronavirus 2019 (COVD-19) pandemic has brought into sharp focus many of the troubling things that we already knew about health disparities in the United States but have failed to address. With the bright light now shining on this important issue, it is time to talk about the role research can play in reducing the disproportionate burden of COVID-19, as well as improving the health of all people in our great nation.
In recent weeks, we’ve seen a growing list of disturbing statistics about how blacks, Hispanics, tribal communities, and some other racial, ethnic, and disadvantaged socioeconomic groups are bearing the brunt of COVID-19. One of the latest studies comes from a research team that analyzed county-by-county data gathered about a month ago. Their findings? The 22 percent of U.S. counties that are disproportionately black accounted for 52 percent of our nation’s COVID-19 cases and 58 percent of COVID-19 deaths. In a paper awaiting peer review, the team, led by Emory University, Atlanta, and amfAR, the Foundation for AIDS Research, Washington, DC., noted that neither the size of the county nor whether it was urban or rural mattered .
Recently, I had an opportunity to discuss the disparate burden of COVID-19 with Dr. Eliseo Pérez-Stable, Director of NIH’s National Institute on Minority Health and Health Disparities (NIMHD). Besides leading an institute, Dr. Pérez-Stable is a widely recognized researcher who studies various factors that contribute to health disparities. Our conversation took place via videoconferencing, with him linking in from his home in Washington, D.C., and me from my home in nearby Maryland. Here’s a condensed transcript of our chat:
Collins: Eliseo, you and I recently had a chance to have a pretty intense discussion with the Congressional Black Caucus about health disparities and the COVID-19 pandemic. So, could you start off with a little bit about what populations are being hit hardest?
Pérez-Stable: Collecting data about disease incidence and mortality on the basis of race and ethnicity and other important demographic factors, like socioeconomic status, had really been absent in this pandemic until recently.
Part of that I think is entirely understandable. Hospitals were pressed with a surge of very sick patients, and there was a certain amount of fear and panic in the community. So, people were not completing all these forms that usually get turned in to the health departments and then forwarded to the CDC. If you go back in history, similar things happened in the early 1980s with the HIV epidemic. We weren’t collecting data on race and other sociodemographic variables initially. But, with time, we did complete these data and a picture emerged.
With the COVID-19 pandemic, obviously, the outcomes are much faster, with over 60,000 deaths in just a matter of three months. And we started to see reports, initially out of Connecticut, Milwaukee, Chicago, and New Orleans, that African Americans were dying at a disproportionate rate.
Now, the initial—and I think still the most likely—explanation for this higher mortality relates to two factors. The first is a higher rate of co-morbidities. We know that if you have cardiovascular disease, more than mild obesity, or diabetes, you’re more likely to get severe COVID-19 and potentially die from it. So, we could have just said, “Aha! It’s obvious why this population, and others with higher rates of co-morbidities might be expected to have higher rates of severe disease and higher mortality.”
But there is a second factor that relates to getting infected, for which we have much-less clear data. There was recently a map in The Washington Post showing the distribution of the rate of COVID-19 infections in Washington, D.C., by ward. The highest rates are in the wards that are east of the Anacostia River, which are about 90 percent African American. So, there is an appearance of a correlation between the proportion of African Americans in the community and the rate of Covid-19 infection. Now why could that be?
Collins: Yes, what explains that?
Pérez-Stable: Well, I think crowding is part of it, certainly in this neighborhood. A second option would be multiple families living under one roof.
Collins: So, you can’t exactly practice physical distancing very well in that situation.
Pérez-Stable: Absolutely. You and I can go into our respective rooms, probably have our respective bathrooms, and socially and physically isolate from the rest of the household if need be. Many people can’t do that. They have three generations in one small apartment, all using one bathroom, maybe two bedrooms for six or eight people.
So, we do face different conditions by which one casual infection can lead to much more community transmission. But much information still needs to be ascertained and there does seem to be some regional variance. For example, in Chicago, Milwaukee, and Atlanta, the reports, at least initially, are worse than they are in Connecticut or Florida. Also, New York City, which has been the epicenter of the U.S. for this pandemic, has an increased rate of infections and mortality among Latino-Hispanic populations as well. So, it isn’t isolated to an African-American issue.
Collins: What about access to healthcare?
Pérez-Stable: Again, we can postulate based on a little bit of anecdote and a little bit of data. I’m a general internist by background, and I can see the enormous impact this pandemic has had on healthcare settings.
First, elective ambulatory visits and elective admissions to the hospital have been postponed, delayed, or cancelled. About 90 percent of ambulatory care is occurring through telemedicine or telephone connections, so in-person visits are occurring only for really urgent matters or suspected COVID-19.
If you have health insurance and can use systems, you can probably, through telephone triage with a nurse, get either approval or nonapproval for being tested [for COVID-19], drive to a place, get tested by someone wearing protective equipment, and never actually have to visit with anyone. And you’ll get your result now back as soon as one day, depending on the system. Now, if you’re insured, but don’t really know how to use systems, navigating all these things can be a huge challenge. So, that could be a factor.
People are also afraid to come to clinic, they’re afraid to show up at the emergency room, because they’re afraid to get infected. So, they’re worried about going in, unless they get very sick. And when they get very sick, they may be coming in with more advanced cases [of COVID-19].
So, telephone triage, advice from clinicians on the phone, is critical. We are seeing some doctors base their decisions on whether a person is able to breathe okay on the phone, able to say a whole sentence without catching their breath. These kinds of basic things that we learned in clinical medicine training are coming into play in a big way now, because we just cannot provide the kind of care, even in the best of circumstances, that people may need.
Of course, uninsured patients will have even more barriers, although everyone in the healthcare system is trying their best to help patients when they need to be helped, rather than depend on insurance triage.
Collins: A big part of trying to keep the disease from spreading has been access to testing so that people, even those with mild symptoms, can find out if they have this virus and, if so, quarantine and enable public health workers to check out their contacts. I’m guessing, from what you said, that testing has been happening a lot less in urban communities that are heavily populated by African Americans and that further propagates the spread of the disease. Am I right?
Pérez-Stable: So far, most testing has been conducted on the basis of symptoms. So, if you have enough symptoms that you may potentially need to be hospitalized, then you get tested. Also, if you’re a healthcare worker who had contact with a COVID-19 patient, you might be tested, or if there’s someone you’ve been very close to that was infected, you may be tested. So, I don’t think so much it’s a matter of disproportionate access to testing by one group or another, as much as that the overall triage and selection criteria for testing have been rather narrow. Up until now, it has not been a simple process to get tested for COVID-19. As we scale up and get better point-of-care tests and much easier access to getting tested, I think you’ll see dissemination across the board.
Collins: It’s interesting we’re talking about this, because this is an area that Congress recently came to NIH and said, “We want you to do something about the testing by encouraging more technology, particularly technology that can be distributed to the point-of-care, and that is out in the community.”
Everyone wants a test that gives you a quick turnaround, an answer within an hour, instead of maybe a day or two. A big part of what NIH is trying to do is to make sure that if we’re going to develop these new testing technologies, they get deployed in places that otherwise might not have much access to testing—maybe by working through the community health centers. So, we’re hoping we might be able to make a contribution there.
Pérez-Stable: The economic factors in this pandemic are also huge. A significant proportion of the population that we’re referring to—the disparity population, the minorities, the poor people—work in service jobs where they’re on the front line. They were the restaurant servers and people in the kitchen, they’re still the bus drivers and the Uber drivers, and those who are working in pharmacies and supermarkets.
On the one hand, they are at higher risk for getting infected because they’re in more contact with people. On the other hand, they’re really dependent on this income to maintain their household. So, if they test positive or get exposed to COVID-19, we really do have a challenge when we ask them to quarantine and not go to work. They’re not in a position where they have sick leave, and they may be putting themselves at risk for being laid off.
Collins: Eliseo, you’ve been studying health disparities pretty much your whole research career. You come from a community where health disparities are a reality, having been born in Cuba and being part of the Latino community. Did you expect that COVID-19 would be this dramatic in the ways in which it has so disproportionately affected certain groups?
Pérez-Stable: I can’t say that I did. My first thought as a physician was to ask: “Is there any reason to think that an infectious agent like COVID-19 would disproportionally infect or impact any population?” My gut answer was “No.” Infectious diseases usually seem to affect all people; sort of equal opportunity invaders. There are some data that would say that influenza and pneumonia are not any worse among African Americans or Latinos than among whites. There are some slight differences in some regions, but not much.
Yet I know this a question that NIH-funded scientists are interested in addressing. We need to make sure that there aren’t any particular susceptibility factors, possibly related to genetics or the lung epithelium, that lead to such different COVID-19 outcomes in different individuals. Clearly, something must be going on, but we don’t know what that is. Maybe one of those factors tracks through race or ethnicity because of what those social constructs represent.
I recently listened to a presentation by Rob Califf, former FDA Commissioner, who spoke about how the pandemic has created a spotlight on our disparities-creating system. I think much of the time this disparities-creating system is in the background; it doesn’t really affect most people’s daily lives. Now, we’re suddenly hit with a bucket of cold water called COVID-19, and we’re saying what is going on and what can we do about it to make a difference. I hope that, once we begin to emerge from this acute crisis, we take the opportunity to address these fundamental issues in our society.
Collins: Indeed. Let’s talk about what you’re doing at NIMHD to support research to try to dig into both the causes of health disparities and the interventions that might help.
Pérez-Stable: Prompted by your motivation, we started talking about how minority health and health disparities research could respond to this pandemic. In the short-term, we thought along the lines of how can we communicate mitigation interventions, such as physical distancing, in a more effective way to our communities? We also asked what we could do to enhance access to healthcare for our populations, both to manage chronic conditions and for diagnosis and treatment of acute COVID-19.
We also considered in the mid- and long-term effects of economic disruption—this surge of unemployment, loss of jobs, loss of insurance, loss of income—on people’s health. Worries include excess use of alcohol and other substances, and worsening of mental and emotional well-being, particularly due to severe depression and chronic mental disorders not being well controlled. Intimate partner violence has already been noted to increase in some countries, including France, Spain, and the United States, that have gone on physical distancing interventions. Similarly, child abuse can be exacerbated under these circumstances. Just think of 24/7 togetherness as a test of how people can hold it together all the time. I think that that can bring out some fragility. So, interventions to address these, that really activate our community networks and community-based organizations, are real strengths. They build on the resilience of the community to highlight how we can get through this difficult period of time.
I feel optimistic that science will bring answers, in the form of both therapies and vaccines. But in the meantime, we have a way to go and we a lot to do.
Collins: You mentioned the promise of vaccines. The NIH is working intensively on this, particularly through a partnership called ACTIV, Accelerating Covid-19 Therapeutic Interventions and Vaccines. We hope that in several more months, we’ll be in a position to begin testing these vaccines on a large scale, after having some assurances about their safety and efficacy. From our conversation, it sounds like we should be trying to get early access to those vaccines to people at highest risk, including those in communities with the heaviest burden. But how will that be received? There hasn’t always been an easy relationship between researchers, particularly government researchers, and the African-American community.
Pérez-Stable: I think we have learned from our historical experiences that mistrust of the system is real. To try to pretend that it isn’t there is a big mistake. Address these concerns upfront, obtain support from thought leaders in the community, and really work hard to be inclusive. In addition to vaccines, we need participation in any clinical trials that are coming up for therapeutics.
We also need research on how optimally to communicate this with all the different segments of the population. This includes not just explaining what it means to be eligible for vaccine trials or therapeutic trials, but also discussing the consequences of, say, getting tested, whether it be a viral or antibody test. What does the information mean for them?
Most people just want to know “Am I clear of the virus or not?” That certainly could be part of the answer, but many may require more nuanced responses. Then there’s behavior. If I’m infected and I recover, am I safe to go back out and do things that other people shouldn’t do? We’d love to be able to inform the population about that. But, as you know, we don’t really have the answers to that just yet.
Collins: Good points. How do we make sure, when we’re trying to reach out to populations that have shouldered such a heavy burden, that we’re actually providing information in a fashion that is readily understood?
Pérez-Stable: One thing to keep in mind is the issue of language. About 5 to 10 percent of U.S. adults don’t speak English well. So, we really have to address the language barrier. I also want to highlight the challenge that some tribal nations are facing. Navajo country has had particular challenges with COVID-19 infections in a setting of minimal medical infrastructure. In fact, there are communities that have to go and get their water for the day at a distant site, so they don’t have modern plumbing. How can we recommend frequent hand washing to someone who doesn’t even have running water at home? These are just a few examples of the diversity of our country that need to be addressed as we deal with this pandemic.
Collins: Eliseo, you’ve given us a lot to think about in an obviously very serious situation. Anything you’d like to add?
Pérez-Stable: In analyzing health outcomes, researchers often think about responses related to a metabolic pathway or to a gene or to a response to a particular drug. But as we use the power of science to understand and contain the COVID-19 pandemic, I’d like to re-emphasize the importance of considering race, ethnicity, socioeconomic status, the built environment, the social environment, and systems. Much of the time these factors may only play secondary roles, but, as in all science related to humans, I think they have to be considered. This experience should be a lesson for us to learn more about that.
Collins: Thank you for those wonderful, inspiring words. It was good to have this conversation, Eliseo, because we are the National Institutes of Health, but that has to be health for everybody. With COVID-19, we have an example where that has not turned out to be the case. We need to do everything we can going forward to identify ways to change that.
 Assessing Differential Impacts of COVID-19 on Black Communities. Millet GA et al. MedRxiv. Preprint posted on May 8, 2020.
Coronavirus (COVID-19) (NIH)
Director’s Corner (National Institute on Minority Health and Disparities/NIH)
COVID-19 and Racial/Ethnic Disparities. Webb Hooper M, Nápoles AM, Pérez-Stable EJ.JAMA. 2020 May 11.
amfAR Study Shows Disproportionate Impact of COVID-19 on Black Americans, amfAR News Release, May 5, 2020.
Posted on by Dr. Francis Collins
Drug overdoses continue to take far too many lives, driven primarily by the opioid crisis (though other drugs, such as methamphetamine and cocaine, are also major concerns). While NIH’s Helping to End Addiction Long-term (HEAL) Initiative is taking steps to address this terrible crisis, new findings serve as another wake-up call that young people battling opioid addiction need a lot more assistance to get back on the right track.
In a study of more than 3,600 individuals, aged 13-22, who survived an opioid overdose, an NIH-funded team found that only about one-third received any kind of follow-up addiction treatment . Even more troubling, less than 2 percent of these young people received the gold standard approach of medication treatment.
The findings reported in JAMA Pediatrics come from Rachel Alinsky, an adolescent medicine and addiction medicine fellow at Johns Hopkins Children’s Center, Baltimore. She saw first-hand the devastating toll that opioids are taking on our youth.
Alinsky also knew that nationally more than 4,000 fatal opioid overdoses occurred in people between the ages of 15 and 24 in 2016 . Likewise, rates of nonfatal opioid overdoses for teens and young adults also have been escalating, leading to more than 7,000 hospitalizations and about 28,000 emergency department visits in 2015 alone .
In the latest study, Alinsky wanted to find out whether young people who overdose receive timely treatment to help prevent another life-threatening emergency. According to our best evidence-based guidelines, timely treatment for youth with an opioid addiction should include medication, ideally along with behavioral interventions.
That’s because opioid addiction rewires the brain—will power alone is simply not sufficient to achieve and sustain recovery. After one overdose, the risk of dying from another one rises dramatically. So, it is critical to get those who survived an overdose into effective treatment right away.
Alinsky and her team dove into the best-available dataset, consisting of data on more than 4 million mostly low-income adolescents and young adults who’d been enrolled in Medicaid for at least six months in 16 states. The sample included 3,606 individuals who’d been seen by a doctor and diagnosed with opioid poisoning. A little over half of them were female; most were non-Hispanic whites.
Heroin accounted for about a quarter of those overdoses. The rest involved other opioids, most often prescription painkillers. However, the researchers note that some overdoses attributed to heroin might have been caused by the powerful synthetic opioid fentanyl. The use of fentanyl, often mixed with heroin, was on the rise in the study’s final years, but it was rarely included in drug tests at the time.
Less than 20 percent of young people in the sample received a diagnosis of opioid use disorder, or a problematic pattern of opioid use resulting in impairment or distress. What’s more, in the month following an overdose, few received the current standard for addiction treatment, which should include behavioral therapy and treatment with one of three drugs: buprenorphine, naltrexone, or methadone.
Drilling a little deeper into the study’s findings:
• 68.9 percent did not receive addiction treatment of any kind.
• 29.3 percent received behavioral health services alone.
• Only 1.9 percent received one of three approved medications for opioid use disorder.
It’s been estimated previously that teens and young adults are one-tenth as likely as adults 25 years and older to get the recommended treatment for opioid use disorder . How can that be? The researchers suggest that one factor might be inexperience among pediatricians in diagnosing and treating opioid addiction. They also note that, even when the problem is recognized, doctors sometimes struggle to take the next step and connect young people with addiction treatment facilities that are equipped to provide the needed treatment to adolescents.
As this new study shows, interventions designed to link teens and young adults with the needed recovery treatment and care are desperately needed. As we continue to move forward in tackling this terrible crisis through the NIH’s HEAL Initiative and other efforts, finding ways to overcome such systemic barriers and best engage our youth in treatment, including medication, will be essential.
 Receipt of addiction treatment after opioid overdose among Medicaid-enrolled adolescents and young adults. Alinsky RH, Zima BT, Rodean J, Matson PA, Larochelle MR, Adger H Jr, Bagley SM, Hadland SE. JAMA Pediatr. 2020 Jan 6:e195183.
 Overdose death rates. National Institute on Drug Abuse, NIH.
 2018 annual surveillance drug-related risks and outcomes—United States: surveillance special report. Centers for Disease Control and Prevention.
 Medication-assisted treatment for adolescents in specialty treatment for opioid use disorder. Feder KA, Krawczyk N, Saloner B. J Adolesc Health. 2017 Jun;60(6):747-750.
Opioid Overdose Crisis (National Institute on Drug Abuse/NIH)
Opioid Overdose (Centers for Disease Control and Prevention, Atlanta)
Decisions in Recovery: Treatment for Opioid Use Disorder (Substance Abuse and Mental Health Services Administration, Rockville, MD)
Rachel Alinsky (Johns Hopkins University Children’s Center, Baltimore)
NIH Support: Eunice Kennedy Shriver National Institute of Child Health and Human Development; National Institute on Drug Abuse
Posted on by Dr. Francis Collins
A few weeks ago, I was pleased to take part in the announcement of NIH’s HEALing Communities Study in four states hard hit by the opioid epidemic. This study will test a comprehensive, evidence-based approach—which includes the wide distribution of naloxone to reverse overdoses—with the aim of reducing opioid-related deaths in selected communities by 40 percent over three years.
That’s a very ambitious goal. So, I was encouraged to read about new findings that indicate such reductions may be within our reach if society implements a number of key changes. Among those is the need to arm friends, family members, and others with the ability to save lives from opioid overdoses. Between 2013 and 2016, nine states instituted laws that give pharmacists direct authority to dispense naloxone to anyone without a prescription. However, the impact of such changes has remained rather unclear. Now, an NIH-funded analysis has found that within a couple of years of these new laws taking effect, fatal opioid overdoses in these states fell significantly .
The misuse and overuse of opioids, which include heroin, fentanyl, and prescription painkillers, poses an unprecedented public health crisis. Every day, more than 130 people in the United States die from opioid overdoses . Not only are far too many families losing their loved ones, this crisis is costing our nation tens of billions of dollars a year in lost productivity and added expenses for healthcare, addiction treatment, and criminal justice.
Opioid overdoses lead to respiratory arrest. If not reversed in a few minutes, this will be fatal. In an effort to address this crisis, the federal government and many states have pursued various strategies to increase access to naloxone, which is a medication that can quickly restore breathing in a person overdosing on opioids. Naloxone, which can be delivered via nasal spray or injection, works by binding opioid receptors to reverse or block the effect of opioids. The challenge is to get naloxone to those who need it before it’s too late.
In some states, a physician still must prescribe naloxone. In others, naloxone access laws (NALs) have given pharmacists the authority to supply naloxone without a doctor’s orders. But not all NALs are the same.
Some NALs, including those in Alaska, California, Connecticut, Idaho, New Mexico, North Dakota, Oklahoma, Oregon, and South Carolina, give pharmacists direct authority to dispense naloxone to anyone who requests it. But NALs in certain other states only give pharmacists indirect authority to dispense naloxone to people enrolled in certain treatment programs, or who meet other specific criteria.
In the new analysis, published in JAMA Internal Medicine, a team that included Rahi Abouk, William Paterson University, Wayne, NJ, and Rosalie Liccardo Pacula and David Powell, RAND Corp., Arlington, VA, asked: Do state laws to improve naloxone access lead to reductions in fatal overdoses involving opioids? The answer appears to be “yes,” but success seems to hinge on the details of those laws.
The evidence shows that states allowing pharmacists direct authority to dispense naloxone to anyone have seen large increases in the dispensing of the medication. In contrast, states granting pharmacists’ only indirect authority to dispense naloxone have experienced little change.
Most importantly, the research team found that states that adopted direct authority NALs experienced far greater reductions in opioid-related deaths than states with indirect authority NALs or no NALs. Specifically, the analysis showed that in the year after direct authority NALs were enacted, fatal opioid overdoses in those states fell an average of 27 percent, with even steeper declines in ensuing years. Longer-term data are needed, and, as in all observational studies of this sort, one must be careful not to equate correlation with causation. But these findings are certainly encouraging.
There were some other intriguing trends. For instance, the researchers found that states that allow pharmacists to dispense naloxone without a prescription also saw an increase in the number of patients treated at emergency departments for nonfatal overdoses. This finding highlights the importance of combining strategies to improve naloxone access with other proven interventions and access to medications aimed to treat opioid addiction. Integration of all possible interventions is exactly the goal of the HEALing Communities Study mentioned above.
Successfully tackling the opioid epidemic will require a multi-pronged approach, including concerted efforts and research advances in overdose reversal, addiction treatment, and non-addictive pain management . As I’ve noted before, we cannot solve the opioid addiction and overdose crisis without finding innovative new ways to treat pain. The NIH is partnering with pharmaceutical industry leaders to accelerate this process, but it will take time. The good news based on this new study is that, with thoughtful strategies and policies in place, many of the tools needed to help address this epidemic and save lives may already be at our disposal.
 Association Between State Laws Facilitating Pharmacy Distribution of Naloxone and Risk of Fatal Overdose. Abouk R, Pacula RL, Powell D. JAMA Intern Med. 2019 May 6
 Opioid Overdose Crisis. National Institute on Drug Abuse/NIH. Updated January 2019.
Naloxone for Opioid Overdose (National Institute on Drug Abuse/NIH)
NIH Support: National Institute on Drug Abuse
Posted on by Dr. Francis Collins
Serotonin is best known for its role as a chemical messenger in the brain, helping to regulate mood, appetite, sleep, and many other functions. It exerts these influences by binding to its receptor on the surface of neural cells. But startling new work suggests the impact of serotonin does not end there: the molecule also can enter a cell’s nucleus and directly switch on genes.
While much more study is needed, this is a potentially groundbreaking discovery. Not only could it have implications for managing depression and other mood disorders, it may also open new avenues for treating substance abuse and neurodegenerative diseases.
To understand how serotonin contributes to switching genes on and off, a lesson on epigenetics is helpful. Keep in mind that the DNA instruction book of all cells is essentially the same, yet the chapters of the book are read in very different ways by cells in different parts of the body. Epigenetics refers to chemical marks on DNA itself or on the protein “spools” called histones that package DNA. These marks influence the activity of genes in a particular cell without changing the underlying DNA sequence, switching them on and off or acting as “volume knobs” to turn the activity of particular genes up or down.
The marks include various chemical groups—including acetyl, phosphate, or methyl—which are added at precise locations to those spool-like proteins called histones. The addition of such groups alters the accessibility of the DNA for copying into messenger RNA and producing needed proteins.
In the study reported in Nature, researchers led by Ian Maze and postdoctoral researcher Lorna Farrelly, Icahn School of Medicine at Mount Sinai, New York, followed a hunch that serotonin molecules might also get added to histones . There had been hints that it might be possible. For instance, earlier evidence suggested that inside cells, serotonin could enter the nucleus. There also was evidence that serotonin could attach to proteins outside the nucleus in a process called serotonylation.
These data begged the question: Is serotonylation important in the brain and/or other living tissues that produce serotonin in vivo? After a lot of hard work, the answer now appears to be yes.
These NIH-supported researchers found that serotonylation does indeed occur in the cell nucleus. They also identified a particular enzyme that directly attaches serotonin molecules to histone proteins. With serotonin attached, DNA loosens on its spool, allowing for increased gene expression.
The team found that histone serotonylation takes place in serotonin-producing human neurons derived from induced pluripotent stem cells (iPSCs). They also observed this process occurring in the brains of developing mice.
In fact, the researchers found evidence of those serotonin marks in many parts of the body. They are especially prevalent in the brain and gut, where serotonin also is produced in significant amounts. Those marks consistently correlate with areas of active gene expression.
The serotonin mark often occurs on histones in combination with a second methyl mark. The researchers suggest that this double marking of histones might help to further reinforce an active state of gene expression.
This work demonstrates that serotonin can directly influence gene expression in a manner that’s wholly separate from its previously known role in transmitting chemical messages from one neuron to the next. And, there are likely other surprises in store.
The newly discovered role of serotonin in modifying gene expression may contribute significantly to our understanding of mood disorders and other psychiatric conditions with known links to serotonin signals, suggesting potentially new targets for therapeutic intervention. But for now, this fundamental discovery raises many more intriguing questions than it answers.
Science is full of surprises, and this paper is definitely one of them. Will this kind of histone marking occur with other chemical messengers, such as dopamine and acetylcholine? This unexpected discovery now allows us to track serotonin and perhaps some of the brain’s other chemical messengers to see what they might be doing in the cell nucleus and whether this information might one day help in treating the millions of Americans with mood and behavioral disorders.
 Histone serotonylation is a permissive modification that enhances TFIID binding to H3K4me3. Farrelly LA, Thompson RE, Zhao S, Lepack AE, Lyu Y, Bhanu NV, Zhang B, Loh YE, Ramakrishnan A, Vadodaria KC, Heard KJ, Erikson G, Nakadai T, Bastle RM, Lukasak BJ, Zebroski H 3rd, Alenina N, Bader M, Berton O, Roeder RG, Molina H, Gage FH, Shen L, Garcia BA, Li H, Muir TW, Maze I. Nature. 2019 Mar 13. [Epub ahead of print]
Any Mood Disorder (National Institute of Mental Health/NIH)
Drugs, Brains, and Behavior: The Science of Addiction (National Institute on Drug Abuse/NIH)
Epigenomics (National Human Genome Research Institute/NIH)
Maze Lab (Icahn School of Medicine at Mount Sinai, New York, NY)
NIH Support: National Institute on Drug Abuse; National Institute of Mental Health; National Institute of General Medical Sciences; National Cancer Institute