Stories about: microbiome

Which bacteria in the gut microbiome are really influencing disease?

investigating the 'influencers' in the gut microbiome

Over the last decade, multiple studies have examined possible links between groups of microbes and the presence or absence of multiple diseases, including diabetes, multiple sclerosis, autism and inflammatory bowel disease. But on an individual basis, it’s been unclear which microbes are innocent bystanders, mere markers of disease, and which are active agents, causing harm or providing protection.

Scientists from Harvard Medical School and Boston Children’s Hospital have now designed and successfully used a method to tease out cause-and-effect relationships within the microbiome. Their work, conducted in mice, was described Dec. 6 in Nature.

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Food for thought: How your microbiome celebrates Thanksgiving

Image of microbiome superimposed over a Thanksgiving turkeySeth Rakoff-Nahoum, MD, PhD, a Boston Children’s Hospital physician-scientist who does infectious disease research and is taking an evolutionary approach to understanding the human microbiome and its effect on health, offers us some insight into what’s happening to the bugs in our gut as a result of the Thanksgiving meal. 

Q: Does the traditional American Thanksgiving meal affect the human microbiome?

A: Anything you put in your body has the potential to affect your microbiome, and Thanksgiving dinner is no different.

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Immune gene guards against type 1 diabetes by changing the microbiome. Do early antibiotics undercut its effects?

type 1 diabetes microbiome antibiotics

The health of our immune system is increasingly linked with the health of our intestinal bacteria. A mouse study from Harvard Medical School now hammers this home for autoimmune disorders, in which the body attacks its own cells. It looked specifically at type 1 diabetes, in which the body destroys the cells that make insulin.

Scientists have long known that the human leukocyte antigen (HLA) complex of proteins (also known as the major histocompatibility complex, or MHC) keep autoimmune responses in check. Certain common variants of the HLA/MHC genes are known to protect against a type 1 diabetes. But until now, how these genes prevent autoimmune reactions has been a mystery.

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Another microbiome perspective: The host holds the leash

Abstract depiction of the microbiome

Most scientists and clinicians accept that the human microbiome impacts a person’s nutrition, immune system function, physical health and perhaps even mental illness, but exactly how or why is not well understood. Now, taking an evolutionary approach, a Boston Children’s Hospital infectious disease researcher suggests the host may play a more active role in controlling the microbiome than previously appreciated.

“I think we need to re-evaluate the way in which we think about the microbiome,” says Seth Rakoff-Nahoum, MD, PhD, a physician-scientist at Boston Children’s in the Divisions of Infectious Diseases and Gastroenterology, whose perspective was published today in Nature.

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Could fecal transplants heal Crohn’s and colitis in children? Two trials are set to find out

two trials test fecal transplant in Crohn's and colitis in children

Could an exciting potential treatment for inflammatory bowel disease (IBD) be found in the gastrointestinal tract itself? That’s the theory behind a pair of new studies by Stacy A. Kahn, MD, which will investigate the potential role of fecal microbial transplant (FMT) in the treatment of Crohn’s disease and ulcerative colitis in children.

In IBD, the immune system attacks healthy cells in the digestive tract, triggering symptoms such as abdominal pain, fatigue, poor growth and bloody diarrhea. Children with IBD can also experience problems elsewhere in the body, including joint pain, liver disorders and eye inflammation.

Known colloquially as the “poop pill,” or “stool transplant,” FMT harnesses growing knowledge about the gut microbiota, the collection of bacteria and other microbes that populate our GI tract.

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News Notes: Pediatric science roundup

A quick look at recent research Vector finds noteworthy.

Tracking infants’ microbiomes

cute microbes-shutterstock_317080235-croppedMicrobiome studies are blooming as rapidly as bacteria in an immunocompromised host. But few studies have been done in children, whose microbiomes are actively forming and vulnerable to outside influences. Two studies in Science Translational Medicine on June 15 tracked infants’ gut microbiomes prospectively over time. The first, led by researchers at the Broad Institute and Massachusetts General Hospital, analyzed DNA from monthly stool samples from 39 Finnish infants, starting at 2 months of age. Over the next three years, 20 of the children received at least one course of antibiotics. Those who were repeatedly dosed had fewer “good” bacteria, including microbes important in training the immune system. Overall, their microbiomes were less diverse and less stable, and their gut microbes had more antibiotic resistance genes, some of which lingered even after antibiotic treatment. Delivery mode (cesarean vs. vaginal) also affected microbial diversity. A second study at NYU Langone Medical Center tracked 43 U.S. infants for two years and similarly found disturbances in microbiome development associated with antibiotic treatment, delivery by cesarean section and formula feeding versus breastfeeding.

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Microbiome therapeutics: 6 takeaways from a MassBio panel

microbiome therapeuticsSeeing the surprising success of “poop pills” in gastrointestinal C. difficile infection, pharma companies and startups are embracing the microbiome as a new therapeutic target for an astonishing range of maladies. To learn what pioneering companies in the space are thinking about the hope and the hype, Vector recently attended a panel on microbiome therapeutics at the MassBio Annual Meeting.

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Probing the link between autism, GI disorders and the microbiome

autism microbiome
(Dubova/Shutterstock)

Sonia A. Ballal is an attending physician in the Division of Gastroenterology, Hepatology and Nutrition at Boston Children’s Hospital.

Eleven-year-old Lyle has autism and doesn’t speak, but his mother is used to reading his nonverbal cues. He prefers a routine, but has always been a generally cheerful child who enjoys school and playing with his little sister.

Several weeks before I met Lyle (not his real name), his mother observed a dramatic shift. He was agitated, at times hitting his head against the wall, not receiving his typical sunny reports from school.

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News Notes: Headlines in science and innovation

An occasional roundup of news items Vector finds noteworthy.

Zika’s surface in stunning detail; mosquito tactics

Zika virus
(Purdue University image/courtesy of Kuhn and Rossmann research groups)

We haven’t curbed the Zika epidemic yet. But cryo-electron microscopy — a newer, faster alternative to X-ray crystallography — at least reveals the structure of the virus, which has been linked to microcephaly (though not yet definitively). The anatomy of the virus’s projections gives clues to how the virus is able to attach to and infect cells, and could provide toeholds for developing antiviral treatments and vaccines. Read coverage in the Washington Post and see the full paper in Science.

Meanwhile, as The New York Times reports, scientists are coming together in an effort to control Zika by genetically manipulating the mosquito that spreads it, Aedes aegypti.

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Respiratory illness in children with gastroesophageal reflux: Are acid blockers part of the problem?

Lungs stomach-cropped-Shutterstock-flatcat
(Flatcat via Shutterstock)

Gastroesophageal reflux disease (GERD), in which stomach acids back up into the esophagus, is increasingly diagnosed in children. One study based on insurance-claims data found that GERD diagnoses in infants more than tripled between 2000 and 2005 (from 3.4 to 12.3 percent). In addition to heartburn and chest pain, GERD has been implicated in cough, wheezing and pneumonia.

To reduce such acid-related symptoms, doctors increasingly prescribe acid suppression medications such as proton pump inhibitors (PPIs). They’re among the most-prescribed drug classes in the U.S. But clinicians in the Aerodigestive Program at Boston Children’s Hospital noticed that a large number of their GERD patients had lung cultures positive for bacteria, and that a strong predictor was the amount of non-acid reflux the child had.

“We then had to ask the question, ‘are acid suppression medications, which are being prescribed to treat respiratory symptoms, actually worsening the problem?’” says program director Rachel Rosen, MD, MPH. “What are these medications doing to change the bacteria composition in children?”

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