Featured Research

from universities, journals, and other organizations

Gatekeepers: How microbes make it past tight spaces between cells

Date:
June 17, 2011
Source:
University of Pennsylvania School of Medicine
Summary:
There are ten microbial cells for every one human cell in the body, and microbiology dogma holds that there is a tight barrier protecting the inside of the body from outside invaders, in this case bacteria. Bacterial pathogens can break this barrier to cause infection and researchers wondered how microbes get inside the host and circulate in the first place. They tested to see if microbes somehow weaken host cell defenses to enter tissues.

There are ten microbial cells for every one human cell in the body, and microbiology dogma holds that there is a tight barrier protecting the inside of the body from outside invaders, in this case bacteria. Bacterial pathogens can break this barrier to cause infection and senior author Jeffrey Weiser, MD, professor of Microbiology and Pediatrics from the Perelman School of Medicine at the University of Pennsylvania, and first author Thomas Clarke, PhD, a postdoctoral fellow in the Weiser lab, wondered how microbes get inside the host and circulate in the first place. Weiser and Clarke tested to see if microbes somehow weaken host cell defenses to enter tissues.

Related Articles


In this Cell Host & Microbe study, the investigators found that microbes open and get through the initial cellular barrier -- epithelial cells that line the airway -- in a programmed and efficient way. They surmise this could be a normal physiological event and the epithelial lining may not be as effective at keeping microbes out as once thought. Microbes that survive once past the epithelial lining tend to be pathogenic, such as Streptococcus pneumoniae and Haemophilus influenzae, two major human pathogens causing invasive infections. Their data support a general mechanism for epithelial opening exploited by invasive pathogens to facilitate movement into tissue to initiate disease.

Using microarray and PCR analysis of the epithelial cells' response to invasion by S. pneumoniae and H. influenzae, the researchers found a downregulation of genes called claudins that encode proteins key to keeping the spaces between epithelial cells tight. All animals recognize molecules in microbial cell walls. It was detection of these microbial molecules by host molecules called Toll-like receptors that caused the proteins responsible for keeping the cellular barrier tight to fall down on the job.

When modeled in a cell assay, claudin downregulation was preceded by upregulation of another protein called SNAIL1 that suppresses claudins, the cellular components that keep the junctions tight. What's more, inhibiting claudin expression in a cell assay or stimulating the Toll-like receptors in an animal model loosened the junctions between cells and promoted bacterial movement across the epithelium.

"This study provides an understanding of how microbes gain access into their host to affect its physiology," concludes Weiser.

This research was funded by the National Institute of Allergy and Infectious Diseases.


Story Source:

The above story is based on materials provided by University of Pennsylvania School of Medicine. Note: Materials may be edited for content and length.


Cite This Page:

University of Pennsylvania School of Medicine. "Gatekeepers: How microbes make it past tight spaces between cells." ScienceDaily. ScienceDaily, 17 June 2011. <www.sciencedaily.com/releases/2011/06/110616193905.htm>.
University of Pennsylvania School of Medicine. (2011, June 17). Gatekeepers: How microbes make it past tight spaces between cells. ScienceDaily. Retrieved March 6, 2015 from www.sciencedaily.com/releases/2011/06/110616193905.htm
University of Pennsylvania School of Medicine. "Gatekeepers: How microbes make it past tight spaces between cells." ScienceDaily. www.sciencedaily.com/releases/2011/06/110616193905.htm (accessed March 6, 2015).

Share This


More From ScienceDaily



More Plants & Animals News

Friday, March 6, 2015

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Praying Mantis Looks Long Before It Leaps

Praying Mantis Looks Long Before It Leaps

Reuters - Innovations Video Online (Mar. 5, 2015) Slowed-down footage of the leaps of praying mantises show the insect&apos;s extraordinary precision, say researchers. Video provided by Reuters
Powered by NewsLook.com
Octopus Grabs Camera and Turns It Around On Photographer

Octopus Grabs Camera and Turns It Around On Photographer

Buzz60 (Mar. 5, 2015) A photographer got the shot of a lifetime, or rather an octopus did, when it grabbed the camera and turned it around to take an amazing picture of the photographer. Jen Markham (@jenmarkham) has the story. Video provided by Buzz60
Powered by NewsLook.com
Ringling Bros. Eliminating Elephant Acts

Ringling Bros. Eliminating Elephant Acts

AP (Mar. 5, 2015) The Ringling Bros. and Barnum & Bailey Circus is ending its iconic elephant acts. The circus&apos; parent company, Feld Entertainment, told the AP exclusively that the acts will be phased out by 2018 over growing public concern about the animals. (March 5) Video provided by AP
Powered by NewsLook.com
Raw: Tourists Visit Rare Grey Whales in Mexico

Raw: Tourists Visit Rare Grey Whales in Mexico

AP (Mar. 4, 2015) Once nearly extinct, grey whales now migrate in their thousands to Mexico&apos;s Vizcaino reserve in Baja California, in search of warmer waters to mate and give birth. Tourists flock to the reserve to see the whales, measuring up to 49 feet long. (March 4) Video provided by AP
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:

Strange & Offbeat Stories


Plants & Animals

Earth & Climate

Fossils & Ruins

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