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From harmless colonizers to virulent pathogens: Microbiologists identify what triggers disease

Date:
August 6, 2013
Source:
University at Buffalo
Summary:
The bacteria Streptococcus pneumoniae harmlessly colonizes the mucous linings of throats and noses in most people, only becoming virulent when they leave those comfortable surroundings. Now, researchers reveal how that happens.

The bacteria Streptococcus pneumoniae harmlessly colonizes the mucous linings of throats and noses in most people, only becoming virulent when they leave those comfortable surroundings and enter the middle ears, lungs or bloodstream. Now, in research published in July in mBio, University at Buffalo researchers reveal how that happens.

"We were asking, what is the mechanism behind what makes us sick?" explains Anders P. Hakansson, PhD, assistant professor of microbiology and immunology in the UB School of Medicine and Biomedical Sciences. "We are looking to find ways to interfere with the transition to disease. Few have looked at the specific mechanism that suddenly makes these bacteria leave the nose where they typically prefer to reside and travel into the lungs or the middle ear where they cause disease. If we can understand that process, then maybe we can block it."

Hakansson and his colleagues had previously found that when the pneumococci colonize the nose, they form sophisticated, highly structured biofilm communities.

In the current study, the research team grew biofilms of pneumococci on top of human epithelial cells, where the bacteria normally grow. They then infected these bacteria with influenza A virus or exposed them to the conditions that typically accompany the flu, including increased temperature to mimic fever, increased concentrations of ATP (the energy molecule in cells), and the stress hormone norepinephrine, released during flu infection. All three stimuli triggered a sudden release and departure of bacteria from the biofilm in the nose into otherwise normally sterile organs, such as the middle ears and lungs or into the bloodstream. At the same time, the researchers found that the gene expression profile of the bacteria that had dispersed from the biofilms revealed far more virulence.

Hakansson says the research demonstrates how the mammalian and bacterial kingdoms interact. "Humans are the only natural hosts for these bacteria," he explains, "when the viral infection comes in, there is this interkingdom signaling, where the bacteria respond to host molecules. If we can find ways to interrupt that signaling, we might be able to prevent disease."

Hakansson is affiliated with the Witebsky Center for Microbial Pathogenesis and Immunology and the New York State Center of Excellence in Bioinformatics and Life Sciences, both at UB. The major portion of the work was conducted by co-author Laura R. Marks, an MD/PhD candidate in the UB Department of Microbiology and Immunology, with co-authors Bruce A. Davidson, research assistant professor of anesthesiology and Paul R. Knight, III, MD, PhD, professor of anesthesiology and microbiology and immunology.

The work was funded by the UB Department of Microbiology and Immunology.


Story Source:

The above story is based on materials provided by University at Buffalo. The original article was written by Ellen Goldbaum. Note: Materials may be edited for content and length.


Journal Reference:

  1. L. R. Marks, B. A. Davidson, P. R. Knight, A. P. Hakansson. Interkingdom Signaling Induces Streptococcus pneumoniae Biofilm Dispersion and Transition from Asymptomatic Colonization to Disease. mBio, 2013; 4 (4): e00438-13 DOI: 10.1128/mBio.00438-13

Cite This Page:

University at Buffalo. "From harmless colonizers to virulent pathogens: Microbiologists identify what triggers disease." ScienceDaily. ScienceDaily, 6 August 2013. <www.sciencedaily.com/releases/2013/08/130806111021.htm>.
University at Buffalo. (2013, August 6). From harmless colonizers to virulent pathogens: Microbiologists identify what triggers disease. ScienceDaily. Retrieved July 31, 2014 from www.sciencedaily.com/releases/2013/08/130806111021.htm
University at Buffalo. "From harmless colonizers to virulent pathogens: Microbiologists identify what triggers disease." ScienceDaily. www.sciencedaily.com/releases/2013/08/130806111021.htm (accessed July 31, 2014).

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