Science has shown that bacteria, viruses and other microbes that live in and on the human body – the microbiota – are essential in maintaining and restoring health. Researchers across UofL are investigating the roles of specific bacteria and their metabolites – the substances they produce – and how to employ them in improving health.

Two recent studies from researchers in UofL’s have shown that a specific type of bacteria shows significant benefits in the treatment of alcohol-associated liver disease and alcohol use disorder. The research reveals that both probiotics and the metabolites made by the bacteria have beneficial effects.

One study, a clinical trial in which patients took oral doses of the bacterium Lactobacillus rhamnosus GG (LGG), resulted in reduced alcohol use and liver injury in these patients. A related laboratory study in animal models showed that metabolites from LGG are a source of the benefits.

In the multi-center clinical trial, led by Craig McClain, professor of medicine and director of the Alcohol Research Center, LGG reduced liver injury and, just as importantly, reduced drinking in patients with early alcohol-associated liver disease. Study participants who were treated with LGG showed a significant reduction in liver injury after one month. Six months of LGG therapy was associated with a reduction of heavy drinking to social or abstinence levels.

“There are multiple lines of evidence from several groups showing that altering gut flora plays a role in alcohol consumption and alcohol use disorder treatment. We are pursuing this line of inquiry, but the study is early work,” McClain said. The study was  in April.

In preclinical research, lab studies led by Wenke Feng, professor in the UofL Department of Pharmacology and Toxicology, showed that the substances produced by LGG, its metabolites, are responsible for the beneficial effects to the gut and liver of alcohol-treated mice. That study, , was published in Hepatology in April.

“Our ongoing research aims to uncover mechanistic insights that could pave the way for new treatments for alcohol-associated disorders,” Feng said.

“Dr. Feng’s studies show that it is not the live bacteria that is required to obtain benefits, but instead substances that the bacteria make are the active, beneficial ingredients. Working with our metabolomics group, Dr. Xiang Zhang and colleagues, we have identified some of these active substances,” McClain said. Zhang is professor of chemistry and director of the UofL Center for Regulatory and Environmental Analytical Metabolomics.

“These exciting results suggest that probiotics may be a source of new therapies for alcohol-use disorder as well as alcohol-associated liver disease,” McClain said.

Alcohol use disorder (AUD) is a medical condition in which people have limited ability to stop or control their alcohol use. According to the 2021 National Survey on Drug Use and Health, AUD affected 29.5 million Americans over the age of 12 in the past year. Prolonged excessive alcohol use can result in high blood pressure, heart disease, stroke, liver disease and digestive problems, as well as cancer, mental health problems, weakened immune system and social problems.

For more information on alcohol use disorder, visit the .

“Aging is not inevitable; it is an opportunity. Not everyone has the chance to grow old,” said Robert Friedland, professor of neurology at the University of Louisville and an expert on aging. “How well we age depends on what we do.”

Inspired by his grandfather’s struggle with dementia, Friedland has spent nearly five decades as a neurologist and researcher, studying the causes of neurological diseases and seeking new ways to treat and prevent them. In addition to seeing patients with a focus on cognitive, behavioral and geriatric neurology, his ongoing research investigates the connection between microbes in the gut and mouth and the development of Alzheimer’s and Parkinson’s disease and other neurodegenerative conditions.

Based on this work, Friedland says it is possible for people to preserve health into later years by stockpiling reserves in cognitive, physical, psychological and social health.

Although Friedland admits that certain physical declines are inevitable with age and that genetics can predispose a person to certain diseases, he believes in many cases these reserves can prevent diseases or lessen their effects, delay age-related declines and allow an older person to recover from accidents and illness.

“Genetics do have a role in our health but they are not the whole story. Choices we make throughout life affect whether diseases develop and how much they reduce our health when they do,” Friedland said. “We can do things that delay or mitigate heart disease, diabetes and cognitive and neurological diseases and allow us to recover from life events that otherwise may cause permanent declines in health.”

Each of Friedland’s four factors, described below, is dependent on the others. Friedland provides tips on increasing reserves of each area. By developing habits that add to these reserves, you can maximize your opportunity to remain active and healthy as you get older.

Cognitive reserve – The ability of the brain to work effectively, solve problems and make decisions.

Since the brain controls every system in the body, it makes sense that a healthy brain will support other reserve factors (physical, psychological, social).

Keep the brain healthy by seeking opportunities to learn new things and challenge your ways of thinking throughout life. Learn a new language or a new skill, such as playing a musical instrument or crochet. Play chess or other games. Any activity that involves learning and strategy will strengthen your brain.

“Watching television is not a good activity since it is completely passive and does not require participation. Reading is a better choice as it demands involvement,” Friedland said. “Telling stories is good for your memory and attention skills.”

Physical reserve – The health of the body’s cardiovascular, neurological, musculoskeletal and other systems.

These reserves depend on eating the right food, engaging in physical activity every day and receiving regular health care.

A diverse diet of healthy foods supports both your body and your microbiota, the microorganisms that live in and on the body and are essential to your overall health. Friedland recommends a diet that is mostly plants, high in fiber and low in sugar, salt and saturated fat. When you improve your diet, you also can improve the health of your microbes which aids your own health.

“I call it gene therapy in the kitchen,” Friedland said. “By making the best choices in your food, you can alter the genetic makeup of your microbiota and improve your overall health in as little as two weeks.”

Exercising for 30 minutes each day, regardless of weather or circumstance, is enough to improve physical health, Friedland says. More is better, of course, and when you combine physical activity with social interactions and cognitive activity by playing a sport such as golf or tennis, the benefits multiply.

Taking steps to protect yourself from injury or illness also is important. Wear a helmet when you are riding a bike, wash your hands and avoid exposure to toxins.

It also is important to get enough quality sleep each night, practice good dental hygiene, avoid excess alcohol and have regular medical checkups.

Polypharmacy is another problem to avoid. Friedland said that as people age, they may accumulate prescriptions for multiple health concerns that can interact or alter the effectiveness of each other. If you are taking several prescriptions, regularly evaluate all of them with your health care provider.

Psychological reserve – A healthy mental state that is free of agitation, anxiety and depression.

Poor mental health can affect your ability to interact with others or maintain your physical health. Practice a positive mental attitude, engage in activities that are meaningful to you and manage stress with meditation or other measures.

“Depression is common in older people, and that can lead to memory problems,” Friedland said. “Physical factors can contribute to depression, such as poor sleep or vitamin deficiency. A lack of social interactions and physical activity also can cause or aggravate depression.”

Social reserve – Personal relationships and the ability to function in society.

The company of others can motivate people to take care of themselves and encourage them to maintain healthful behaviors. Positive relationships can be with a spouse, a group of friends or professional colleagues.

“Studies indicate that dementia is more common among people whose social activity declines later in life,” Friedland said. “Humans need relationships with others in order to maintain good health.”  

Social engagement can go hand in hand with the other types of activity by including friends in physical exercise, games, a craft or work. Involvement in community or religious activities also can increase a sense of belonging and a desire to stay active.

Ideally, you will begin developing habits that contribute to these reserves early in life, but Friedland says it is possible to add to reserves and improve your health at any age – even once you reach an age when you experience the effects of deficits.

“Aging is not inevitable,” Friedland said. “The chance to be alive should be recognized as an opportunity – an opportunity to manage our lifestyle factors to maximize survival, health, fitness and meaning as we age.”

More detailed advice from Friedland that may help people live longer, healthier lives and a deeper discussion of the reasons he makes these recommendations are available in his book, “.” Published in October by Cambridge University Press, the book was cited by the Wall Street Journal as one of the five best books on aging and retirement published in 2022.

University of Louisville researcher Levi Beverly, PhD, is here to help.

At the next Beer with a Scientist Jan. 22, Beverly, associate professor in the Department of Medicine, will explain these and other recent developments in biomedical research for people without a degree in science.

“We will talk about CRISPR, microbiota and other topics, but we also are asking the audience what they want to learn about,” Beverly said. “People are invited to bring an article or headline they have seen that needs more explanation or to post questions or topics on our Facebook page, .”

Beverly’s talk begins at 7 p.m. on Wednesday, Jan. 22 at , 8023 Catherine Lane. A 30-minute presentation will be followed by an informal Q&A session.

The researchers at UofL have determined that Urolithin A (UroA) and its synthetic counterpart, UAS03, mitigate IBD by increasing proteins that tighten epithelial cell junctions in the gut and reducing gut inflammation in animal models. Tight junctions in the gut barrier prevent inappropriate microorganisms and toxins from leaking out, causing inflammation characteristic of IBD. Preclinical research published today in shows the mechanism by which UroA and UAS03 not only reduce inflammation and restore gut barrier integrity, but also protect against colitis.

“The general belief thus far in the field is that urolithins exert beneficial effects through their anti-inflammatory, anti-oxidative properties. We have for the first time discovered that their mode of function also includes repairing the gut barrier dysfunction and maintaining barrier integrity,” said Rajbir Singh, PhD, a postdoctoral fellow at UofL and the paper’s first author.

Venkatakrishna Rao Jala, PhD, assistant professor of microbiology and immunology at UofL, led the research, conducted by Singh and other collaborators at UofL, the Institute for Stem Cell Biology and Regenerative Medicine (inStem) in Bangalore, India, the University of Toledo College of Medicine and Life Sciences, and Dalhousie University in Nova Scotia. Jala, Singh and other researchers at UofL have been investigating how metabolites produced by the human microbiota – bacteria, viruses and fungi that inhabit the human body – affect many areas of health. By understanding the effects of specific metabolites, they hope to use them directly as therapeutic agents in treating disease.

It has been reported that the microbe Bifidobacterium pseudocatenulatum INIA P815 strain in the gut has the ability to generate UroA from ellagic acid (EA), a compound found in berries and pomegranates. Variations in UroA levels, despite consumption of foods containing EA, may be the result of varied populations of bacteria responsible for the production of UroA from one individual to another, and some individuals may not have the bacteria at all. While encouraging natural levels of UroA in the gut by consuming the appropriate foods and protecting populations of beneficial bacteria should have positive health effects, the researchers believe the use of the more stable synthetic UAS03 may prove to be therapeutically effective in cases of acute colitis. Further experiments and clinical testing are needed to test these beliefs.

“Microbes in our gut have evolved to generate beneficial microbial metabolites in the vicinity of the gut barrier,” Jala said. “However, this requires that we protect and harbor the appropriate gut microbiota and consume a healthy diet. This study shows that direct consumption of UroA or its analog can compensate for a lack of the specific bacteria responsible for production of UroA and continuous consumption of pomegranates and berries.”

Haribabu Bodduluri, PhD, professor of microbiology and immunology at UofL and an author of the article, said another key finding of the research is that UroA and UAS03 show both therapeutic and protective effects. Administration of UroA/UAS03 after the development of colitis reverses the condition and administration prior to development of colitis prevents it from occurring.

This research was facilitated by funding from the National Cancer Institute to Jala and the , established at UofL in 2018 with funding from the National Institute of General Medical Sciences.

University of Louisville neurology professor and professor at the University of Michigan, have proposed a new term to describe an interaction between gut microbiota and the brain in an article released today in .

Friedland and Chapman propose the term “mapranosis” for the process by which amyloid proteins produced by microbes (bacteria, fungi and others) alter the structure of proteins (proteopathy) and enhance inflammation in the nervous system, thereby initiating or augmenting brain disease. The term is derived from Microbiota Associated Protepathy And Neuroinflammation + osis (a process).

Friedland hopes that giving the process a name will facilitate awareness and research leading to therapeutic opportunities.

“It is critical to define the ways in which gut bacteria and other organisms interact with the host to create disease, as there are many ways in which the microbiota may be altered to influence health,” Friedland said.

Research into the multitude of microbes that inhabit the human body has expanded considerably in recent years. Genomic analysis has begun to reveal the full diversity of bacteria, viruses, fungi, archaea and parasites living in and on the body, the majority of them in the gut. Even more recently, researchers have begun to explore how the proteins and other metabolites produced by microbes in the gut influence functions in other parts of the body, including the brain. However, we do not yet fully understand how these systems work. The relationship between the microbiota and the brain has been called the “gut-brain axis.”

It is understood that the clumping of misfolded amyloid proteins, structures produced by neurons in the brain, are associated with neurodegeneration and conditions such as Alzheimer’s disease, Parkinson’s disease and amyotrophic lateral sclerosis (ALS).

“It is well known that patterns of amyloid misfolding of neuronal proteins are involved in age-related brain diseases. Recent studies suggest that similar protein structures produced by gut bacteria, referred to as bacterial amyloid, may be involved in the initiation of neurodegenerative processes in the brain,” Friedland said. “Bacterial amyloids are produced by a wide range of microbes that inhabit the GI tract, including the mouth.”

In research published in 2016 in , Friedland and colleagues showed that when E. coli microbes in the gut of rats and worms (nematodes) produced misfolded amyloids, the amyloids produced in the animals’ brains and intestines also misfolded, a process called cross-seeding.

“Our work suggests that our commensal microbial partners make functional extracellular amyloid proteins, which interact with host proteins through cross-seeding of amyloid misfolding and trigger neuroinflammation in the brain,” Friedland said.

In today’s article, Friedland and Chapman also address other factors related to the microbiota and its products and how they influence neurodegenerative disorders.

1. The microbiota modulates (enhances) immune processes throughout the body, including the central nervous system.
2. The microbiota may induce oxidative toxicity (free radicals) and related inflammation that contributes to neurodegeneration.
3. Metabolites produced by the microbiota may be either beneficial (health sustaining) or damaging (pathogenic).
4. Host genetics influence microbiota populations, illustrating that the gut-brain axis is bidirectional.

Friedland believes further research in this area may lead to therapies for these neurodegenerative diseases, which are increasing in frequency and for which there are few effective treatments.

“Now we are hoping to determine which bacteria or metabolites are interacting to determine the severity or lack of severity of illness in the individual,” Schmidt said. “If we can identify the bacteria, it raises hope that we can target those mechanisms to prevent severity of the disease, thereby reducing illness and death from malaria in sub-Saharan Africa.”

Globally, afflicts more than 200 million people and causes more than 400,000 deaths each year, with 90 percent of cases occurring in sub-Saharan Africa. However, many more individuals are infected with the Plasmodium parasite but do not become seriously ill. Schmidt’s research aims to learn more about why some people become seriously ill while others do not.

In 2016, Schmidt published research in revealing that mice having one community of microbiota colonizing their gut were less susceptible to severe infection from Plasmodium than mice with a different community of microbiota. In this research, Schmidt showed that when the microbiota from the mice experiencing low or high levels of illness were transplanted to mice that previously had no microbiota (germ-free mice), the transplanted mice had similar levels of disease following infection as the low and high donor controls, respectively. These results demonstrate that it was the gut microbiota causing differences in disease severity.

In another series of experiments, he treated mice with antibiotics followed by doses of Lactobacillus and Bifidobacteria in lab-cultured yogurt. The parasite burden in the susceptible mice decreased dramatically and symptoms of illness were reduced in the mice treated with the yogurt.

Schmidt believes the antibiotic allowed the Lactobacillus and Bifidobacteria introduced in the yogurt to colonize the gut, thereby controlling the Plasmodium population.

“Enteric bacteria provide a competitive environment for other bacteria to grow and survive in. Treatment of mice with antibiotics provided an opportunity for the Lactobacillus and Bifidobacteria to grow and provide protection against severe malaria. Alternatively, it is possible the Lactobacillus prevented recovery of bacteria that cause severe malaria,” Schmidt said.

Schmidt hopes to further isolate which bacteria are responsible for protecting the host from illness and tease apart the mechanisms by which they influence Plasmodium populations and immune response. This should allow collaboration with other researchers to test those effects in humans.

“Nathan’s current findings and the proposed studies will enhance our understanding of how microbiota may modulate host immunity to malaria, which could explain why some individuals develop severe disease while others suffer milder symptoms. This is an understudied area with many opportunities,” said Nejat Egilmez, PhD, chair of the Department of Microbiology and Immunology.

Schmidt is one of a growing number of researchers investigating links between gut microbiota and disease across the UofL Health Sciences Center campus.

“The role of commensal microbiota in host physiology and health is a highly active, cutting-edge area of research amounting to a new paradigm in medicine,” Egilmez said. “In addition to Nathan, several of our faculty, including Drs. Michele Kosiewicz, Krishna Jala and Hari Bodduluri, have ongoing projects exploring the link between host microbiota and diseases such as autoimmune disorders, infectious disease and cancer. The new award will create opportunities for future collaborations not only amongst these individuals but also with others in the department who study the more basic processes underlying host immunity and microbial pathogenesis.”

Robert Friedland, MD, professor in the Department of Neurology at the University of Louisville, has conducted research showing that the microorganisms in the intestines can affect the brain, and may be responsible for causing Alzheimer’s, Parkinson’s and other neurodegenerative diseases. He will discuss this research and other valuable insights on microbiota at the next event, Feb. 15. 

“These partner microbes have more than 100 times more genes than our own DNA. Since they are dependent upon our diet for their nutrition and sustenance, we can substantially alter the microbiota through alteration of food intake, performing a type of ‘gene therapy,’” Friedland said. “We will discuss the role of the microbiota in health and disease and review what people can do to lower their risk of cancer, stroke, and Alzheimer’s and Parkinson’s diseases.”

Friedland is a clinical and research neurologist and has researched neurodegenerative diseases and other brain disorders associated with aging for more than 30 years. He is collaborating on research projects with investigators in Ireland, the United Kingdom and Japan.

The Beer with a Scientist event begins at 8 p.m. on Wednesday, Feb. 15, at Against the Grain Brewery, 401 E. Main St. in Louisville. A 30-minute presentation will be followed by an informal Q&A session. Admission is free. Purchase of beer, other beverages or menu items is not required but is encouraged.

The next Beer with a Scientist is scheduled for March 15.

Robert P. Friedland, MD, the Mason C. and Mary D. Rudd Endowed Chair and professor of Neurology at the University of Louisville School of Medicine, and a team of researchers have discovered that these processes may be triggered by proteins made by our gut bacteria (the microbiota). Their research has revealed that exposure to bacterial proteins called amyloid, that have structural similarity to brain proteins, leads to an increase in clumping of the protein alpha-synuclein in the brain. Aggregates, or clumps, of misfolded alpha-synuclein and related amyloid proteins are seen in the brains of patients with the neurodegenerative diseases AD, PD and ALS.

Alpha-synuclein (AS) is a protein normally produced by neurons in the brain. In both PD and AD, alpha-synuclein is aggregated in a clumped form called amyloid, causing damage to neurons. Friedland has hypothesized that similarly clumped proteins produced by bacteria in the gut cause brain proteins to misfold via a mechanism called cross-seeding, leading to the deposition of aggregated brain proteins. He also proposed that amyloid proteins produced by the microbiota cause priming of immune cells in the gut, resulting in enhanced inflammation in the brain.

The research, which was supported by , involved the administration of bacterial strains of E. coli that produce the bacterial amyloid protein curli to rats. Control animals were given identical bacteria that lacked the ability to make the bacterial amyloid protein. The rats fed the curli-producing organisms showed increased levels of AS in the intestines and the brain and increased cerebral AS aggregation, compared with rats who were exposed to E. coli that did not produce the bacterial amyloid protein. The curli-exposed rats also showed enhanced cerebral inflammation.

Similar findings were noted in a related experiment in which nematodes (Caenorhabditis elegans) that were fed curli-producing E. coli also showed increased levels of AS aggregates, compared with nematodes not exposed to the bacterial amyloid. A research group led by neuroscientist Shu G. Chen, PhD, of Case Western Reserve University, performed this collaborative study.

This new understanding of the potential role of gut bacteria in neurodegeneration could bring researchers closer to uncovering the factors responsible for initiating these diseases and ultimately developing preventive and therapeutic measures.

“These new studies in two different animals show that proteins made by bacteria harbored in the gut may be an initiating factor in the disease process of Alzheimer’s disease, Parkinson’s disease and ALS,” Friedland said. “This is important because most cases of these diseases are not caused by genes, and the gut is our most important environmental exposure. In addition, we have many potential therapeutic options to influence the bacterial populations in the nose, mouth and gut.”

Friedland is the corresponding author of the article, , published online Oct. 6 in Scientific Reports, a journal of the Nature Publishing Group. UofL researchers involved in the publication in addition to Friedland include Vilius Stribinskis, PhD, Madhavi J. Rane, PhD, Donald Demuth, PhD, Evelyne Gozal, PhD, Andrew M. Roberts, PhD, Rekha Jagadapillai, Ruolan Liu, MD, PhD, and Richard Kerber, PhD. 

This work supports recent studies indicating that the microbiota may have a role in disease processes in age-related brain degenerations. It is part of Friedland’s ongoing research on the relationship between the microbiota and age-related brain disorders, which involves collaborations with researchers in Ireland and Japan.

“We are pursuing studies in humans and animals to further evaluate the mechanisms of the effects we have observed and are exploring the potential for the development of preventive and therapeutic strategies,” Friedland said.