Navigation Links
National Jewish Health researchers discover how virulent bacteria

Researchers at National Jewish Health have discovered how the virulent food-borne bacteria Listeria monocytogenes induces infected immune cells to sabotage their own defensive response. The studies offer insight into host-pathogen interactions and suggest potential therapeutic targets for food poisoning, tuberculosis and autoimmune diseases.

In the Feb. 15 issue of the Journal of Experimental Medicine, Laurel Lenz, PhD, and his colleagues report that macrophages infected by the bacteria Listeria release interferon-αβ (IFN- αβ), which makes them and nearby immune cells unresponsive to activation signals. This reduces immune resistance to the bacteria, which causes thousands of cases of food poisoning -- and more than 500 deaths -- each year in the United States.

"Listeria appears to benefit by triggering an endogenous pathway of the host that dampens its own immune response," said Dr. Lenz. "Our findings suggest that Listeria increases its survival in infected individuals by inducing cross-talk between host interferon signaling pathways."

When patrolling immune-system cells encounter non-pathogenic microbes, they normally engulf and destroy them. However, certain pathogens such as Listeria can grow within immune cells, which then release alarm signals to other nearby cells. One of these alarms is IFN-αβ. IFN-αβ protects host cells from viral infection. However, IFN- also increases growth of Listeria and certain other bacteria.

Dr. Lenz and his colleagues showed that IFN-αβ does this by down-regulating expression of receptors for interferon-γ (IFN-γ). With its receptors down-regulated, IFN-γ cannot drive resting macrophages into an activated state that is especially effective against bacterial pathogens inside the cell.

"IFN-αβ acts as a sort of anesthetic to numb the response of immune cells to IFN-γ," said Dr. Lenz.

The research highlights the crosstalk that exists between the antibacterial and anti-viral arms of the immune response. Dr. Lenz's findings demonstrate that IFN-αβ, well known to stimulate antiviral defenses, dampens anti-bacterial activity as well.

He speculates that this may be a way for the immune system to more efficiently defend against viral pathogens, while avoiding collateral damage caused by an overactive immune cells. In fact, interferon-β, a medication widely used for multiple sclerosis, may do just that. Dr. Lenz speculates that this medication may act in part by down-regulating expression of IFN- γ receptors on myeloid cells, thus reducing the stimulation of autoimmune T cells.

The next step will be to define more precisely how IFN-αβ mediates down-regulation of the IFN-γ receptors, and to determine whether prevention of these effects improves resistance to infection by Listeria and other bacterial pathogens.


Contact: Adam Dormuth
National Jewish Medical and Research Center

Related biology news :

1. Wolves find happy hunting grounds in Yellowstone National Park
2. BIO-key(R) International to Showcase Deployed Biometric Security Applications at 2007 Biometric Technology Expo
3. ESMO International Symposium on Immunology
4. Story tips from the US Department of Energys Oak Ridge National Laboratory, September 2007
5. Office of the Director of National Intelligence, CIO to Speak at Government Security Conference
6. Director of National Intelligence to Speak at Conference
7. Singapore National Science and Technology Awards
8. Conservation International and Toyota partner to protect Philippines rain forests
9. International team shows mercury concentrations in fish respond quickly to increased deposition
10. International team shows mercury concentrations in fish respond quickly to increased deposition
11. Office of the Director of National Intelligence, CIO to Speak at Government Security Conference
Post Your Comments:
(Date:11/19/2015)... , Nov. 19, 2015  Based on its in-depth ... Sullivan recognizes BIO-key with the 2015 Global Frost & ... Frost & Sullivan presents this award to the company ... to the needs of the market it serves. The ... meets and expands on customer base demands, the overall ...
(Date:11/17/2015)... Paris from 17 th until 19 ... from 17 th until 19 th November 2015. ... invented the first combined scanner in the world which scans ... now two different scanners were required: one for passports and ... the same surface. This innovation is an ideal solution for ...
(Date:11/16/2015)... 16, 2015  Synaptics Inc. (NASDAQ: SYNA ... today announced expansion of its TDDI product portfolio ... controller and display driver integration (TDDI) solutions designed ... new TDDI products add to the previously-announced ... (WQHD resolution), and TD4322 (FHD resolution) solutions. All ...
Breaking Biology News(10 mins):
(Date:11/25/2015)... ... November 25, 2015 , ... Jessica ... on AngelList early in their initial angel funding process. Now, they are paying ... looking to make early stage investments in the microbiome space. In this, ...
(Date:11/24/2015)... 24, 2015 /CNW/ - iCo Therapeutics ("iCo" or "the ... results for the quarter ended September 30, 2015. ... dollars and presented under International Financial Reporting Standards ... ," said Andrew Rae , President & ... are not only value enriching for this clinical ...
(Date:11/24/2015)... 24, 2015 --> ... report "Oligonucleotide Synthesis Market by Product & Services (Primer, ... Diagnostic, DNA, RNAi), End-User (Research, Pharmaceutical & Biotech, Diagnostic ... the market is expected to reach USD 1,918.6 Million ... a CAGR of 10.1% during the forecast period. ...
(Date:11/24/2015)... AVIV, Israel , Nov. 24, 2015  Tikcro Technologies Ltd. (OTCQB: ... held on December 29, 2015 at 11:00 a.m. Israel ... Co., Electra Tower, 98 Yigal Allon Street, 36 th Floor, ... election of Eric Paneth and Izhak Tamir to ... and Rami Skaliter as external directors; , approval of an amendment ...
Breaking Biology Technology: