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-££] (IFN- ££]), 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-££]. IFN-££] protects host cells from viral infection. However, IFN-ƒÑƒÒ also increases growth of Listeria and certain other bacteria.
Dr. Lenz and his colleagues showed that IFN-££] does this by down-regulating expression of receptors for interferon-£^ (IFN-£^). With its receptors down-regulated, IFN-£^ cannot drive resting macrophages into an activated state that is especially effective against bacterial pathogens inside the cell.
"IFN-££] acts as a sort of anesthetic to numb the response of immune cells to IFN-£^," 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-££], 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-£], 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- £^ receptors on myeloid cells, thus reducing the stimulation of autoimmune T cells.
The next step will be to define more precisely how IFN-££] mediates down-regulation of the IFN-£^ receptors, and to determine whether prevention of these effects improves resistance to infection by Listeria and other bacterial pathogens.
National Jewish Health is known worldwide for treatment of patients with respiratory, cardiac, immune and related disorders, and for groundbreaking medical research. Founded in 1899 as a nonprofit hospital, National Jewish remains the only facility in the world dedicated exclusively to these disorders. Since1998, U.S. News & World Report has ranked National Jewish the #1 respiratory hospital in the nation.
Adam Dormuth | EurekAlert!
Newly discovered bacteria-binding protein in the intestine
08.12.2016 | University of Gothenburg
The balancing act: An enzyme that links endocytosis to membrane recycling
07.12.2016 | National Centre for Biological Sciences
In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.
Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...
Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...
A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.
Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...
In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.
“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...
The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.
The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...
16.11.2016 | Event News
01.11.2016 | Event News
14.10.2016 | Event News
08.12.2016 | Materials Sciences
08.12.2016 | Materials Sciences
08.12.2016 | Physics and Astronomy