Breaking News
January 23, 2019 - Short interval between last meal of the day and bedtime may not affect blood glucose levels
January 23, 2019 - Still Too Many Highway Deaths Tied to Speeding
January 23, 2019 - Prenatal valproate exposure linked to increased ADHD risk
January 23, 2019 - Compound identified that may help treat heart failure
January 23, 2019 - Undiagnosed Asthma in Urban Adolescents May Be Common
January 23, 2019 - Study describes metabolism of intestinal microbiota in babies for the first time
January 22, 2019 - Study links concussions to development of epilepsy
January 22, 2019 - Specialist-led hospital bereavement service may help restrain legal action after difficult deaths
January 22, 2019 - Genetic study reveals possible new routes to treating osteoarthritis
January 22, 2019 - Blood test may detect early signs of lung-transplant rejection
January 22, 2019 - Blood marker could aid in early prediction of Alzheimer’s progression
January 22, 2019 - Orthodontic treatment does not guarantee future dental health
January 22, 2019 - Rutgers researchers discover cause of bone loss in people with joint replacements
January 22, 2019 - Diversity among rural Africans extends to their gut microbiomes
January 22, 2019 - Newly developed biological system lets cells to create self-curving cornea
January 22, 2019 - VTv Therapeutics Announces Publication of Comprehensive Data in Science Translational Medicine Detailing the Discovery and Clinical Development of TTP399, including Results of Phase 2 AGATA Study
January 22, 2019 - about one in three adults with prediabetes has arthritis
January 22, 2019 - A look at how data is democratizing health care
January 22, 2019 - Alcohol-Linked Disease Overtakes Hep C As Top Reason For Liver Transplant
January 22, 2019 - Researchers identify new genes linked with age-related macular degeneration
January 22, 2019 - MPFI researchers identify synaptic logic for connections between two brain hemispheres
January 22, 2019 - New study extends our knowledge of the link between miRNAs and cancer
January 22, 2019 - Asthma, eczema are not barriers to active lifestyle in teenagers
January 22, 2019 - Genetic changes may predict likelihood of relapse in breast cancer patients
January 22, 2019 - Antiepileptic drug use by people with Alzheimer’s disease linked to accumulation of hospital days
January 22, 2019 - IUPUI researcher receives $2.85 million grant to find ways to improve bone strength
January 22, 2019 - Precision medicine can help keep astronauts healthy during deep space missions
January 22, 2019 - Detecting signs of neurodegeneration earlier and more accurately
January 22, 2019 - Mouse studies challenge ‘inhibition’ theory of autism
January 22, 2019 - SSB launches BIOSTAT RM TX single-use bioreactor for producing consistent quality cellular products
January 22, 2019 - Experimental drug can positively modify key characteristic behavior in FXS patients
January 22, 2019 - Low-Income Women Lack Menstrual Hygiene Supplies
January 22, 2019 - Better mouse model built to enable precision-medicine research for Alzheimer’s
January 22, 2019 - Molecular profiling of precancerous lung lesions could lead to early detection and new treatments
January 22, 2019 - Genetic factors influence where fat is stored in our bodies
January 22, 2019 - The Psychology Behind Sticking to Your New Year’s Resolutions
January 22, 2019 - Scientists aim to find genetic causes of developmental abnormalities in the vagina and uterus
January 22, 2019 - New survey reveals scale of preventative healthcare challenge in the UK
January 22, 2019 - Looming Global Crisis Means People’s Diets Must Change: Experts
January 22, 2019 - Excessive social media use is comparable to drug addiction
January 22, 2019 - Researchers show how mechanical stress affects bone development
January 22, 2019 - Study takes a step closer to understanding the body’s response to opioid painkillers
January 22, 2019 - Unexpected connection found between feeding and memory centers of the brain
January 22, 2019 - A revolutionary approach transforms bone trauma treatment
January 22, 2019 - Early studies and recent clinical trials on nerve growth factor
January 22, 2019 - Dry Mouth and Older Adults: Information for Caregivers
January 22, 2019 - Are your grandparents getting tipsy at the holiday party?
January 22, 2019 - New machine learning algorithms identify early symptoms of urinary tract infections
January 22, 2019 - Young women skipping the Pap smear test due to embarrassment
January 22, 2019 - A global influenza pandemic high on the WHO’s agenda
January 22, 2019 - Amgen Makes All Repatha (evolocumab) Device Options Available In The US At A 60 Percent Reduced List Price
January 22, 2019 - Elastronics—hydrogel-based microelectronics for localized low-voltage neuromodulation
January 22, 2019 - Branched-chain amino acids in tumors can be targeted to prevent and treat cancer
January 22, 2019 - Fueling macrophages with energy to attack and eat cancer cells
January 22, 2019 - Amgen And UCB Receive Positive Vote From FDA Advisory Committee In Favor Of Approval For Evenity (romosozumab)
January 22, 2019 - Does being bilingual make children more focused? Study says no
January 22, 2019 - Study reveals new genes and biological pathways linked to osteoarthritis
January 22, 2019 - FSU study provides better understanding of spinal cord injuries
January 22, 2019 - Delaying bath for newborn babies increases breastfeeding rates, finds study
January 21, 2019 - WHO identifies non-communicable diseases as major threat to human health
January 21, 2019 - Many parents still try non-evidence-based cold prevention methods for children
January 21, 2019 - High Levels of Activity, Motor Ability Linked to Better Cognition
January 21, 2019 - Killer blows? Knockout study of pair of mouse MicroRNA provides cancer insight
January 21, 2019 - Buffalo researchers receive grant to quicken development of generic equivalents of contraceptives
January 21, 2019 - One-third of pregnant women do not believe cannabis is harmful to their fetus
January 21, 2019 - Fiderstat could be used as chemopreventative drug for intestinal cancers caused by APC gene mutations
January 21, 2019 - Modifying healthcare delivery practices may improve discussions between youth and healthcare providers
January 21, 2019 - UNIST researcher named as recipient of Merck’s 2018 Life Science Awards
January 21, 2019 - How Getting a Flu Shot Could Save Your Life
January 21, 2019 - Surgical adhesions can be treated, prevented in mice
January 21, 2019 - Increased physician-targeted marketing associated with higher opioid overdose deaths
January 21, 2019 - Researchers uncover specific microbial signatures of intestinal disease
January 21, 2019 - Researchers discover new blood vessel system in bones
January 21, 2019 - Simple blood test reliably detects signs of Alzheimer’s damage before symptoms
January 21, 2019 - Study to investigate new targeted oral treatments for severe asthma
January 21, 2019 - Plan Your Plate | NIH News in Health
January 21, 2019 - Fecal occult blood test may improve CRC outcomes in some
January 21, 2019 - Blood test detects Alzheimer’s disease years before symptoms develop
January 21, 2019 - Mount Sinai joins with Paradigm and ReqMed to repurpose drug for treatment of MPS
January 21, 2019 - FDA Advisory Committee Votes on Zynquista (sotagliflozin) as Treatment for Adults with Type 1 Diabetes
Druglike molecules produced by gut bacteria can affect gut, immune health

Druglike molecules produced by gut bacteria can affect gut, immune health

image_pdfDownload PDFimage_print
Credit: CC0 Public Domain

Stanford researchers found that manipulating the gut microbe Clostridium sporogenes changed levels of molecules in the bloodstreams of mice and, in turn, affected their health.

Here’s some food for thought: When you lick your Thanksgiving plate clean this week, you’re not just feeding yourself; you’re also providing meals to the trillions of microbes that live in your gut.

And if your dinner includes turkey, a notoriously rich source of the amino acid tryptophan, the gut bacterium Clostridium sporogenes will have the job of breaking down that tryptophan. Then the molecules that are produced by the microbe will flow into your bloodstream in the same way a prescription drug might, interacting with your immune system and changing the biology of the intestines.

Stanford University School of Medicine researchers have used mice to demonstrate how gut bugs could be bioengineered to produce possibly therapeutic changes in the body.

A paper describing their efforts was published online Nov. 22 in Nature. Justin Sonnenburg, PhD, associate professor of microbiology and immunology, and Michael Fischbach, PhD, associate professor of bioengineering, share senior authorship. The lead author is Dylan Dodd, MD, PhD, instructor in pathology.

When the researchers blocked the ability of C. sporogenes to break down tryptophan in mice, levels of certain molecules in their bloodstreams changed. Moreover, the researchers saw physiological changes to the mice’s immune systems and intestines.

“This is a vivid example of not only how the microbiome is affecting things all over your body, but of how we can leverage that to improve health,” said Sonnenburg, using a term for the collection of microbes living on or inside an animal, or in a particular part.

Improving health from the inside

Over the past 15 years, researchers have shown that the composition of a person’s gut microbiome can alter their risk for all sorts of health problems, from diabetes and heart disease to allergies and depression. One reason these tiny microbes have such an outsized effect: They can produce molecules known as metabolites that enter the bloodstream and circulate throughout the body. Pinning down exactly which molecules are produced by which bacteria, however, and how to alter their levels to change health, has been challenging.

Previous studies have shown that just a few bacteria, including C. sporogenes, can break down tryptophan and produce the metabolite known as indolepropionic acid. Studies have also hinted that IPA helps fortify the intestinal wall, letting fewer molecules leak through.

In the new work, the researchers first detailed exactly how C. sporogenes produces IPA from tryptophan. They identified a handful of other compounds also produced in the process—12 metabolites in total, nine of which can accumulate in the blood and three of which are produced only by bacteria. Then, the researchers pinpointed for the first time the genes that C. sporogenes requires for the breakdown of tryptophan and metabolism of the resulting molecules. A gene called fldC, they showed, is required for the production of IPA.

Next, the team gave germ-free mice either wild-type C. sporogenes—with the ability to produce IPA—or a version of the bacteria that lacked fldC. In mice that received the wild-type bacteria, levels of IPA in the bloodstream were around 80 micromolar; in mice that received the engineered version of the bacteria, IPA was undetectable.

Finally, they looked at how altering the levels of IPA affected the mice. Mice with undetectable IPA, they found, had higher levels of immune cells, including neutrophils, classical monocytes and memory T cells. This suggested activation of two branches of the immune system—the innate and adaptive immune system. In addition, the mice with the engineered version of C. sporogenes had more permeable intestines, a defect which is often seen in gut diseases, including inflammatory bowel disease.

Targeting microbes

If the results hold true in humans, said Sonnenburg, it could point toward a new paradigm for treating some diseases: rather than give a compound, such as IPA, physicians may one day be able to tweak levels of bacteria to affect levels of metabolites. For instance, it might be possible to treat inflammatory bowel disease by boosting levels of C. sporogenes and ensuring patients eat enough tryptophan.

“This gives us a specific example of how we can target individual microbes and pathways in the gut to change a person’s health,” Dodd said. “And this is just one example of hundreds or thousands that are likely out there.”

The group next plans to study C. sporogenes and IPA levels in mice with more complex gut microbiomes—rather than germ-free mice—and begin tracking down other metabolites produced by the gut microbes that may have health effects.

“While providing a stunning example of how a single gut microbe, and a single gene within that microbe, can impact host health, IPA is just the tip of the iceberg,” said Fischbach, “The possibility to positively impact human health through microbiome-produced chemicals is tremendous, and we are poised to take big strides and make this a reality.”

Other Stanford authors are Matthew Spitzer, PhD, a former graduate student; graduate students William Van Treuren and Bryan Merrill; postdoctoral scholar Andrew Hryckowian, PhD; life science researcher Steven Higginbottom, PhD; Gary Nolan, PhD, professor of microbiology and immunology; adjunct faculty member Anthony Le; and Tina Cowan, PhD, professor of pathology.


Explore further:
Mice fed tryptophan develop immune cells that foster a tolerant gut

More information:
A gut bacterial pathway metabolizes aromatic amino acids into nine circulating metabolites, Nature (2017). nature.com/articles/doi:10.1038/nature24661

Journal reference:
Nature

Provided by:
Stanford University Medical Center

Tagged with:

About author

Related Articles