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Parkinson's Disease Linked to Microbiome

Caltech scientists have discovered for the first time a functional link between bacteria in the intestines and Parkinson's disease (PD). The researchers show that changes in the composition of gut bacterial populations—or possibly gut bacteria themselves—are actively contributing to and may even cause the deterioration of motor skills that is the hallmark of this disease.


Written by Lori Dajose | Dec 1, 2016


Written by Abby Olena | Dec 1, 2016

Bacteria in the intestine influence motor dysfunction and neuroinflammation in a mouse model of Parkinsons's Disease.


Written by Sanden Totten | Dec 1, 2016


Written by Jason Henry | Dec 1, 2016


Written by Alice Park | Dec 1, 2016


Written by Lori Dajose | Dec 1, 2016


Written by Lauren Tousignant | Dec 2, 2016



Written by James Gallagher | Dec 2, 2016


Written by Claire Maldarelli | Dec 2, 2016





Credit: Timothy Sampson

When Beneficial Bacteria Knock But No One is Home

The community of beneficial bacteria that live in our intestines, known as the gut microbiome, are important for the development and function of the immune system. There has been growing evidence that certain probiotics—therapies that introduce beneficial bacteria into the gut—may help alleviate some of the symptoms of intestinal disorders such as Crohn's disease. By studying the interplay between genetic risk factors for Crohn's and the bacteria that populate the gut, researchers at Caltech have discovered a new potential cause for this disorder in some patients—information that may lead to advances in probiotic therapies and personalized medicine.


Written by Jessica Stoller-Conrad | May 6, 2016

Credit: Mark Ladinsky/Greg Donaldson/Caltech

Partnership with Heritage Medical Research Institute Will Augment Translational Medicine Research

A new partnership will support translational sciences and health technology at Caltech thanks to a three-year commitment from Heritage Medical Research Institute (HMRI), a nonprofit founded and led by Caltech trustee Richard N. Merkin. 


Written by Marisa Demers | Sept 10, 2015

Credit: Lara Everly

Meet Sarkis Mazmanian and the Bacteria That Keep Us Healthy

As a child, Sarkis Mazmanian frequently took things apart to figure out how they worked. At the age of 12, he dismantled his family’s entire television set—to the dismay of his parents and the unsuccessful TV repairman.


Written by Ruchi Shah | Aug 6, 2015

Sarkis K. Mazmanian
Credit: New York Academy of Sciences 

When gut bacteria changes brain function

Some researchers believe that the microbiome may play a role in regulating how people think and feel.


By David Kohn | June 25, 2015


Can the Bacteria in Your Gut Explain Your Mood?

The rich array of microbiota in our intestines can tell us more than you might think.


By Peter Andrey Smith | June 23, 2015


Andrew Rae

Microbes Help Produce Serotonin in Gut

Although serotonin is well known as a brain neurotransmitter, it is estimated that 90 percent of the body's serotonin is made in the digestive tract. In fact, altered levels of this peripheral serotonin have been linked to diseases such as irritable bowel syndrome, cardiovascular disease, and osteoporosis. New research at Caltech, published in the April 9 issue of the journal Cell, shows that certain bacteria in the gut are important for the production of peripheral serotonin.


Posted by Jessica Stoller-Conrad | April 9, 2015

Credit: E. Hsiao/Caltech

Gut Bug Enthusiast

Over the past few years, the microbial world’s reputation has been turned on its head. Since Louis Pasteur proved the so-called germ theory of disease in almost 150 years ago, we humans have diligently tried to purge bacteria from our lives. But scientists today are telling us at that the story isn’t so simple, and that the bacteria that colonize our bodies – more than one hundred trillion of them – are actually our coevolutionary partners, crucial to maintaining human health.


Posted by Alla Katnelson | Jan/Feb 2015



Mental Health May Depend on Creatures in the Gut

The microbiome may yield a new class of psychobiotics for the treatment of anxiety, depression and other mood disorders


Jessica Fortner

Can Microbes in the Gut Influence the Brain?

"The Kavli Foundation brought together three researchers at the forefront of this emerging field to discuss the microbiome-brain connection and whether we can treat disorders of the brain through the gut."


Lindsay Borthwick, The Kavli Foundation | Jan 8, 2015 



Gut–brain link grabs neuroscientists

Idea that intestinal bacteria affect mental health gains ground


By Sara Reardon | Nov 12, 2014  


Lester V. Bergman/Corbis

Bacteria in our gut may influence both our physical and mental health

If bacteria in your gut can affect your health, can they affect your brain, too?



Tipping the Balance of Behavior

 Humans with autism often show a reduced frequency of social interactions and an increased tendency to engage in repetitive solitary behaviors. Autism has also been linked to dysfunction of the amygdala, a brain structure involved in processing emotions. Now Caltech researchers have discovered antagonistic neuron populations in the mouse amygdala that control whether the animal engages in social behaviors or asocial repetitive self-grooming. This discovery may have implications for understanding neural circuit dysfunctions that underlie autism in humans. 



Credit: Lance Hayashida/Caltech Office of Strategic Communications

Research Update: Battling Infection With Microbes

A relationship between gut bacteria and blood cell development helps the immune system fight infection, Caltech researchers say.

The human relationship with microbial life is complicated. At almost any supermarket, you can pick up both antibacterial soap and probiotic yogurt during the same shopping trip. Although there are types of bacteria that can make us sick, Caltech professor of biology and biological engineering Sarkis Mazmanian and his team are most interested in the thousands of other bacteria—many already living inside our bodies—that actually keep us healthy. His past work in mice has shown that restoring populations of beneficial bacteria can help alleviate the symptoms of inflammatory bowel disease, multiple sclerosis, and even autism. Now, he and his team have found that these good bugs might also prepare the immune cells in our blood to fight infections from harmful bacteria. 


An artist’s representation of gut microbes promoting hematopoiesis.
An artist’s representation of gut microbes promoting hematopoiesis.
Credit: Arya Khosravi and Wesley McBride/Caltech

Probiotic Therapy Alleviates Autism-like Behaviors in Mice

Autism spectrum disorder (ASD) is diagnosed when individuals exhibit characteristic behaviors that include repetitive actions, decreased social interactions, and impaired communication. Curiously, many individuals with ASD also suffer from gastrointestinal (GI) issues, such as abdominal cramps and constipation.


Credit: Elaine Hsiao

A Home for the Microbiome

Caltech biologists identify, for the first time, a mechanism by which beneficial bacteria reside and thrive in the gastrointestinal tract

The human body is full of tiny microorganisms—hundreds to thousands of species of bacteria collectively called the microbiome, which are believed to contribute to a healthy existence. The gastrointestinal (GI) tract—and the colon in particular—is home to the largest concentration and highest diversity of bacterial species. But how do these organisms persist and thrive in a system that is constantly in flux due to foods and fluids moving through it? A team led by California Institute of Technology (Caltech) biologist Sarkis Mazmanian believes it has found the answer, at least in one common group of bacteria: a set of genes that promotes stable microbial colonization of the gut.


A section of mouse colon is shown with gut bacteria (outlined in yellow) residing within the crypt channel.
Credit: Caltech / Mazmanian Lab

Sarkis Mazmanian: Microbe Machinist

When Sarkis Mazmanian was 13 years old, he took apart the family television “because I wanted to understand how it worked,” he says. “And I was convinced I was going to be able to put it back together.” He was wrong on both counts, and his parents were forced to throw the TV out. But it foreshadowed how Mazmanian would spend his career: taking systems apart to understand how they function. “There are a lot of parallels between a television and how it operates and an organism and how it operates,” he says—“a lot of different pieces working in a system as a whole.”



Caltech Biologist Named MacArthur Fellow

PASADENA, Calif.—Sarkis Mazmanian, a microbiology expert at the California Institute of Technology (Caltech) whose studies of human gut bacteria have revealed new insights into how these microbes can be beneficial, was named a MacArthur Fellow and awarded a five-year, $500,000 "no strings attached" grant. Each year, the John D. and Catherine T. MacArthur Foundation awards the unrestricted fellowships—also known as "genius" grants—to individuals who have shown "extraordinary originality and dedication in their creative pursuits and a marked capacity for self-direction," according to the foundation's website. 


MacArthur Fellow/Meet the Class of 2012

The MacArthur Fellows Program awards unrestricted fellowships to talented individuals who have shown extraordinary originality and dedication in their creative pursuits and a marked capacity for self-direction.



Credit: John D. & Catherine T. MacArthur Foundation

Caltech Researchers Find Evidence of Link between Immune Irregularities and Autism

PASADENA, Calif.—Scientists at the California Institute of Technology (Caltech) pioneered the study of the link between irregularities in the immune system and neurodevelopmental disorders such as autism a decade ago. Since then, studies of postmortem brains and of individuals with autism, as well as epidemiological studies, have supported the correlation between alterations in the immune system and autism spectrum disorder. 


Credit: Elaine Hsiao

Sarkis Mazmanian Discusses Benevolent Bacteria in Scientific American

There are trillions of bacteria living in our bodies, making up complex communities of microbes regulating processes like digestion and immunity. For Caltech biologist Sarkis Mazmanian, they also make up the focus of his research: understanding how the "good" bacteria promote human health. Featured in the cover story for the June issue of Scientific American, he makes a case for devoting more attention to the helpful bugs after years of scientific dedication to pathogens. "It goes against dogma to think that bacteria would make our immune systems function better," he says, in the article. "But the picture is getting very clear: the driving force behind the features of the immune system are commensals." 

The magazine is available now on newsstands and the article, "The Ultimate Social Network," can be read online with a subscription.

Written by Katie Neith | May 30, 2012

Caltech Biologists Link Gut Microbial Equilibrium to Inflammatory Bowel Disease

PASADENA, Calif.—We are not alone—even in our own bodies. The human gut is home to 100 trillion bacteria, which, for millions of years, have co-evolved along with our digestive and immune systems. Most people view bacteria as harmful pathogens that cause infections and disease. Other, more agreeable, microbes (known as symbionts) have taken a different evolutionary path, and have established beneficial relationships with their hosts. Still other microbes may be perched somewhere in between, according to research by biologists at the California Institute of Technology (Caltech) that offers new insight into the causes of inflammatory bowel disease (IBD) and colon cancer.

A paper about their work appears in the April 22 issue of the journal Cell Host & Microbe



Credit: Courtesy of Arya Khosravi and Sarkis Mazmanian/Caltech