Tag Archives: UC San Diego

Biologists Develop Models to Aid Development of Novel Therapies to Fight Clostridioides difficile (C. diff.) Pathogen

The Clostridium difficile pathogen takes its name from the French word for “difficult.” A bacterium that is known to cause symptoms ranging from diarrhea to life-threatening colon damage,




C. difficile is part of a growing epidemic of concern for the elderly and patients on antibiotics.

Outbreaks of C. difficile-infected cases have progressively increased in Western countries, with 29,000 reported deaths per year in the United States alone.

Now, biologists at the University of California San Diego are drawing parallels from newly developed models of the common fruit fly to help lay the foundation for novel therapies to fight the pathogen’s spread. Their report is published in the journal iScience.

C. difficile infections pose a serious risk to hospitalized patients,” said Ethan Bier, a distinguished professor in the Division of Biological Sciences and science director of the UC San Diego unit of the Tata Institute for Genetics and Society (TIGS). “This research opens a new avenue for understanding how this pathogen gains an advantage over other beneficial bacteria in the human microbiome through its production of toxic factors. Such knowledge could aid in devising strategies to contain this pathogen and reduce the great suffering it causes.”

As with most bacterial pathogens, C. difficile secretes toxins that enter host cells, disrupt key signaling pathways and weaken the host’s normal defense mechanisms. The most potent strains of C. difficile unleash a two-component toxin that triggers a string of complex cellular responses, culminating in the formation of long membrane protrusions that allow the bacteria to attach more effectively to host cells.

UC San Diego scientists in Bier’s lab-created strains of fruit flies that are capable of expressing the active component of this toxin, known as “CDTa.” The strains allowed them to study the elaborate mechanisms underlying CDTa toxicity in a live model system focused on the gut, which is key since the digestive system of these small flies is surprisingly similar to that of humans.

“The fly gut provides a rapid and surprisingly accurate model for the human intestine, which is the site of infection by C. difficile,” said Bier. “The vast array of sophisticated genetic tools in flies can identify new mechanisms for how toxic factors produced by bacteria disrupt cellular processes and molecular pathways. Such discoveries, once validated in a mammalian system or human cells, can lead to novel treatments for preventing or reducing the severity of C. difficile infections.”

The fruit fly model gave the researchers a clear path to examine genetic interactions disrupted at the hands of CDTa. They ultimately found that the toxin induces a collapse of networks that are essential for nutrient absorption. As a result, the model flies’ body weight, fecal output and overall lifespan were severely reduced, mimicking symptoms in human C. difficile-infected patients.

In addition to Bier, study coauthors include first-author Ruth Schwartz, Annabel Guichard, Nathalie Franc, and Sitara Roy.

The National Institutes of Health (R01 AI110713) funded the research.

Story Source:

Materials provided by the University of California – San Diego. Original written by Mario Aguilera. Note: Content may be edited for style and length.

Journal Reference:

  1. Ruth Schwartz, Annabel Guichard, Nathalie C. Franc, Sitara Roy, Ethan Bier. A Drosophila Model for Clostridium difficile Toxin CDT Reveals Interactions with Multiple Effector Pathways. iScience, 2020; 100865 DOI: 10.1016/j.isci.2020.100865

Transgenic fruit flies help scientists trace the cascade of symptoms caused by toxic infection

Date: February 7, 2020

Source: University of California – San Diego
Summary: Clostridium difficile, a bacterium is known to cause symptoms from diarrhea to life-threatening colon damage, is part of a growing epidemic for the elderly and hospitalized patients. Biologists have now developed models of the common fruit fly to help develop novel therapies to fight the pathogen

The American Gastroenterological Association (AGA) Fecal Microbiota Transplantation (FMT) National Registry Enrolls First Patient

Largest planned fecal microbiota transplantation (FMT) study enrolls first patient

The FMT National Registry also announces collaborations with American Gut and OpenBiome

The first participant has enrolled in the American Gastroenterological Association (AGA) Fecal Microbiota Transplantation (FMT) National Registry, which is planned to be the largest FMT study ever.

The AGA FMT National Registry — funded by the National Institutes of Health (NIH) and administered by the AGA Center for Gut Microbiome Research and Educationwill track 4,000 patients for 10 years after their FMT procedure, providing a wealth of data about the procedure’s effectiveness and both short- and long-term effects of FMT.

Fecal microbiota transplant is a medical procedure in which the stool from a healthy person is prepared and then put into the intestine of a sick patient. FMT is most commonly used to treat Clostridium difficile (C. diff) infection, if antibiotics have not been able to get rid of the infection.

“Today is an important milestone for the AGA FMT National Registry. What’s ahead is a significant repository of data for investigators working to advance FMT research, better information for physicians on when and how to use FMT, and reassurance for patients that we now understand the risks and benefits of this procedure,” said Gary D. Wu, MD, a principal investigator for the registry and founding chair of the AGA Center for Gut Microbiome Research and Education scientific advisory board. “We look forward to embarking on this comprehensive data collection project and are eager to share our findings with the public.”

First Patient Enrolled

The first patient enrolled in the FMT National Registry received a fecal transplant through the Gastroenterology Center of Connecticut/Medical Research Center of Connecticut by Paul Feuerstadt, MD, assistant clinical professor of medicine at Yale School of Medicine, New Haven, CT. The patient being treated had experienced multiple recurrences of C. difficile infection. As part of the registry,

Dr. Feuerstadt will follow up with the patient four times over the next two years and report back on the patient’s health post-FMT. The patient will also provide yearly reports for up to 10 years.

How Patients Can Take Part in the FMT National Registry

AGA expects 75 sites to be included in this registry. Visit ClinicalTrials.Gov <https://clinicaltrials.gov/ct2/show/study/NCT03325855?cond=FMT+National+registry&rank=1> on a regular basis to track new sites added to the registry. Patients should reach out to their health care provider to discuss participation in the registry.

Patients should first review AGA’s patient information on fecal microbiota transplantation (FMT) <http://www.gastro.org/info_for_patients/clostridium-difficile-106-fmt-details>.

UC San Diego to Build FMT National Registry Biobank

AGA is collaborating with the American Gut Project — an academic effort run by the laboratory of Rob Knight, PhD, professor and director of the Center for Microbiome Innovation at the University of California, San Diego — to build a biobank of stool samples from participants in the FMT National Registry. American Gut will receive stool samples from registry participants before and after their FMT. The microbiota will be sequenced in each sample, and remaining material will be frozen to be made available for future research. Eventually, this information could help doctors screen and select the best donor samples for individual patients.

OpenBiome Joins as a Registry Collaborator

AGA is also collaborating with OpenBiome, a public stool bank and nonprofit research organization that provides clinicians with rigorously screened, ready-to-use stool preparations for fecal transplant procedures. As the only public stool bank in the country, OpenBiome serves as the source of stool preparations for nearly 1,000 clinical partners performing FMT across the United States. For patients enrolled in the registry who receive OpenBiome FMT material, OpenBiome will provide screening information and samples to support the registry’s research analyses.

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