Featured Research

from universities, journals, and other organizations

New defense discovered against common hospital-acquired infection

Date:
August 21, 2011
Source:
University of Texas Medical Branch at Galveston
Summary:
Researchers have discovered a key mechanism used by intestinal cells to defend themselves against one of the world's most common hospital-acquired bacterial infections -- a mechanism they think they can exploit to produce a therapy to protect against the effects of the antibiotic-resistant bacteria.

Researchers have discovered a key mechanism used by intestinal cells to defend themselves against one of the world's most common hospital-acquired bacterial infections -- a mechanism they think they can exploit to produce a therapy to protect against the effects of the antibiotic-resistant bacteria.

Related Articles


The scientists made their discovery while investigating cellular responses to two powerful toxins generated by the bacteria Clostridium difficile, which can cause symptoms ranging from diarrhea to life-threatening bowel inflammation.

"About one percent of all hospital patients develop a C. difficile infection -- they're treated with antibiotics to the point that benign gut bacteria are knocked out, and because C. difficile is resistant to antibiotics it's able to proliferate," said University of Texas Medical Branch at Galveston associate professor Tor Savidge, lead author of a paper on the discovery to be published online Aug. 21 in Nature Medicine. "Then it releases these toxins that trigger colonic disease."

The toxins wreak havoc on cell structural proteins and biochemical communications networks, eventually killing the cell. But in order to do this damage, the toxins first have to get into the cell, and that means passing through the protective membrane that surrounds it.

It's there that Savidge and his collaborators -- a multidisciplinary team of researchers from UTMB, UCLA, Case Western Reserve University, Tufts University and the Commonwealth Medical College -- may have found a way to stop them.

On the molecular scale, C. difficile toxin proteins are quite large -- big enough that they have to "cleave" so that a smaller piece can slip through the membrane and into the cell. This cleavage is accomplished by a built-in molecular guillotine called a cysteine protease, which activates when the toxin encounters a molecule called InsP6 that is present at much higher levels inside the cell than outside.

"It's sort of like a sensor mechanism that detects when it's in a cell -- the toxins say, InsP6 is here, it's time to cleave," Savidge said. "But we've identified a previously unknown protective response that activates after the toxins have induced gut inflammation, in which the host uses a process called nitrosylation to shut down the cysteine protease and prevent cleavage."

A toxin that's unable to cleave stays stuck in the cell membrane, incapable of attacking the cell.

The researchers used test-tube, cell culture, patient specimens and animal model experiments, along with computer simulations of molecular interactions, to thoroughly explore this response -- and to successfully devise a way to mimic it for therapeutic purposes.

"Think of these toxins as missiles that the bacteria is producing to go off and detonate inside the cell," Savidge said. "One way to defend against missiles is to send out signals that trick them into either disarming their sensory mechanisms or get them to prematurely detonate."

Cell culture and mouse experiments demonstrated that a combination of GSNO (the nitrosylating agent and the "disarming" part of Savidge's analogy) and InsP6 (the "premature detonation" part) worked to prevent damage from C. difficile. In fact, the combination therapy worked so well that the team is now preparing to test it in a clinical trial sponsored by UTMB's Institute for Translational Sciences.

"Identification of new treatment modalities to treat this infection would be a major advance," said Dr. Charalabos Pothoulakis, director of UCLA's Inflammatory Bowel Disease Center and a co-author on the study. "If we are successful with this approach, we may be able to treat other bacterial diseases in a similar way."

Other authors of the Nature Medicine article include UTMB's Petri Urvil, Numan Oezguen, Vine Zachary, Irina Pinchot, Alfredo Torres, Robert English, John E. Wiktorowicz, Michael Loeffeholz and Werner Braun; Case Western Reserve's Jonathan Stamler, Alfred Hausladen and Bo Herman; Commonwealth Medical College's Raj Kumar; and Hanping Feng, Lianfa Shi and Weijia Nie of the Tufts University Cummings School of Veterinary Medicine.


Story Source:

The above story is based on materials provided by University of Texas Medical Branch at Galveston. Note: Materials may be edited for content and length.


Journal Reference:

  1. Tor C Savidge, Petri Urvil, Numan Oezguen, Kausar Ali, Aproteem Choudhury, Vinay Acharya, Irina Pinchuk, Alfredo G Torres, Robert D English, John E Wiktorowicz, Michael Loeffelholz, Raj Kumar, Lianfa Shi, Weijia Nie, Werner Braun, Bo Herman, Alfred Hausladen, Hanping Feng, Jonathan S Stamler, Charalabos Pothoulakis. Host S-nitrosylation inhibits clostridial small molecule–activated glucosylating toxins. Nature Medicine, 2011; DOI: 10.1038/nm.2405

Cite This Page:

University of Texas Medical Branch at Galveston. "New defense discovered against common hospital-acquired infection." ScienceDaily. ScienceDaily, 21 August 2011. <www.sciencedaily.com/releases/2011/08/110821141132.htm>.
University of Texas Medical Branch at Galveston. (2011, August 21). New defense discovered against common hospital-acquired infection. ScienceDaily. Retrieved January 31, 2015 from www.sciencedaily.com/releases/2011/08/110821141132.htm
University of Texas Medical Branch at Galveston. "New defense discovered against common hospital-acquired infection." ScienceDaily. www.sciencedaily.com/releases/2011/08/110821141132.htm (accessed January 31, 2015).

Share This


More From ScienceDaily



More Health & Medicine News

Saturday, January 31, 2015

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

CDC: Get Vaccinated for Measles

CDC: Get Vaccinated for Measles

Reuters - US Online Video (Jan. 30, 2015) The CDC is urging people to get vaccinated for measles amid an outbreak that began at Disneyland and has now infected more than 90 people. Linda So reports. Video provided by Reuters
Powered by NewsLook.com
Obama To Outline New Plan For Personalized Medicine

Obama To Outline New Plan For Personalized Medicine

Newsy (Jan. 30, 2015) President Obama is expected to speak with drugmakers Friday about his Precision Medicine Initiative first introduced last week. Video provided by Newsy
Powered by NewsLook.com
NFL Concussions Down; Still on Parents' Minds

NFL Concussions Down; Still on Parents' Minds

AP (Jan. 30, 2015) The NFL announced this week that the number of game concussions dropped by a quarter over last season. Still, the dangers of the sport still weigh on players, and parents&apos; minds. (Jan. 30) Video provided by AP
Powered by NewsLook.com
U.S. Wants to Analyze DNA from 1 Million People

U.S. Wants to Analyze DNA from 1 Million People

Reuters - US Online Video (Jan. 30, 2015) The U.S. has proposed analyzing genetic information from more than 1 million American volunteers to learn how genetic variants affect health and disease. Rough Cut (no reporter narration). Video provided by Reuters
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

More Coverage


New Way to Treat Common Hospital-Acquired Infection: Novel Approach May Offer Treatment for Other Bacterial Diseases

Aug. 21, 2011 Researchers have discovered a molecular process by which the body can defend against the effects of Clostridium difficile, an intestinal disease that impacts several million in the U.S. each year. A ... read more

Strange & Offbeat Stories


Health & Medicine

Mind & Brain

Living & Well

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins