A team of University of British Columbia microbiologists has identified a key defence mechanism used by the immune system against Listeria with strong implications for the future development of vaccines.
Listeria is the bacteria that causes listeriosis, a food-borne infection that caused 22 deaths in Canada in an August 2008 outbreak in meat products produced by Maple Leaf Foods.
"We know a great deal about how our body's adaptive immune system reacts to viruses but generally very little about immune response against bacterial infections," says Wilfred Jefferies, a professor at UBC's Michael Smith Laboratories and Biomedical Research Centre.
The study, published today in the online journal PLoS ONE, focuses on dendritic cells that help activate the immune system. Dendritic cells collect pathogen materials and present them to other parts of the immune system – such as T-cells – a mechanism called cross-presentation.
The UBC team also includes post-doctoral fellows Anna Reinicke and Genc Basha and graduate student Kyla Omilusik.
"Dendritic cells are gatekeepers; they are small in numbers but very active in patrolling tissues that are in contact with the external environment, such as the skin," says Jefferies, who is also a member of the UBC Blood Research Centre, the Brain Research Centre and the Vancouver Coastal Health Research Institute.
"Their job is to apprehend the pathogens while avoiding getting infected," says Jefferies. "We've found that they achieve this by sampling bits and pieces of the bacterial pathogens in the area surrounding infected cells, instead of directly approaching the bacteria."
Their research also shows that when cross-presentation is deactivated, the host becomes severely compromised in its ability to generate the appropriate T-cells to fight the Listeria infection.
"This study establishes the vital role of dendritic cell cross-presentation in fighting bacteria infections and sheds light on how we can manipulate and engage immune responses. This knowledge will ultimately aid in the design of vaccines against bacteria and other pathogens," says Jefferies.
The study was supported by funding from The Canadian Institutes of Health Research (CIHR). "Better understanding of the body's immune system is the key to develop new strategies for treating bacterial infections and for creating new vaccines for Listeria ", says Dr. Bhagirath Singh, Scientific Director at CIHR's Institute of Infection and Immunity. "Dr. Jefferies's work advances our collective effort to prevent listerosis by focusing on the way our immune defences are wired and triggered upon initial infection by invading pathogens."
The paper is available at http://dx.plos.org/10.1371/journal.pone.0007210.
The Canadian Institutes of Health Research (CIHR) is the Government of Canada's agency for health research. CIHR's mission is to create new scientific knowledge and to enable its translation into improved health, more effective health services and products, and a strengthened Canadian health-care system. Composed of 13 Institutes, CIHR provides leadership and support to more than 13,000 health researchers and trainees across Canada. www.cihr-irsc.gc.ca
The Biomedical Research Centre is an interdisciplinary research centre with the goal to generate new knowledge about how the immune system and adult stem cells accomplish these vital tasks, and how disturbances in these processes result in disease. The aim is to translate this new knowledge into innovative treatments for chronic diseases like arthritis, Alzheimer's disease, asthma, diabetes, and cancer. www.brc.ubc.ca.
The Brain Research Centre comprises more than 200 investigators with multidisciplinary expertise in neuroscience research ranging from the test tube, to the bedside, to industrial spin-offs. The centre is a partnership of UBC and VCHRI. For more information, visit www.brain.ubc.ca.
UBC's Michael Smith Laboratories is Canada's first interdisciplinary biotechnology unit. Officially launched in 2004, the facility is named in honour of its founding director and Nobel Laureate, the late Michael Smith. Home to approximately 250 research personnel, investigations include: human/animal molecular genetics; fermentation and bio-process engineering; plant and forestry molecular genetics; and bioinformatics.
VCH Research Institute is the research body of Vancouver Coastal Health Authority. In academic partnership with UBC, the institute advances health research and innovation across B.C., Canada, and beyond. www.vchri.ca
Journal
PLoS ONE