Dr. Philip Griebel
Canada Research Chair in Neonatal Mucosal Immunology
There’s a war zone where our bodies meet our environment, a skirmish line where we are under constant attack by pathogens – infectious agents such as viruses or bacteria. These attackers meet our first line of defence at the mucosal surface, the warm, mucus-lined areas such as our airways and digestive tracts.
While many of these attackers meet their demise at the mucosal surface, some still get through. About 90 per cent of the pathogens that make us sick are able to evade this first line of defence. This problem is even more acute for newborn babies and animals, which are much more susceptible to infections invading via the mucosal surfaces in the intestines. The consequences can be deadly.
Philip Griebel is working to strengthen this first line of defence, particularly for newborns.
Griebel is studying dendritic cells – cells that act as guards on the mucosal surfaces, recognizing pathogens and sounding the alarm for the immune system to fight back.
“By understanding the function of the dendritic cells we will be able to improve vaccine protection against pathogens that enter through the small intestine,” Griebel says.
Since dendritic cells are rare and difficult to isolate, Griebel and his team are using a piece of equipment called a High Speed Cell Sorter. This sorter allows them to identify, isolate, and sort 30,000 cells per second.
Dendritic cells can be very different from one another, so they must be sorted into different “subpopulations.” These subpopulations have different capacities to recognize each infectious agent.
With the cells identified and isolated, the next step is to test the function of these cells by creating cultures.
“We’ll culture individual dendritic cell subpopulations with specific infectious agents and analyze their capacity to recognize and respond to pathogens. This information will then be validated by determining if specific dendritic cell populations influence a neonate’s capacity to respond to an actual infection by the virus or bacteria,” Griebel says.
Ultimately, Griebel’s work is aimed at new vaccines and immune therapies designed to enhance dendritic cells capacity to recognize and help repel infection sooner and more effectively. This approach promises to lead to better vaccines that strengthen the body’s first line of defence: the intestinal mucosal surface.
“We decided that to develop better mucosal vaccines we needed to understand exactly what immune cells we needed to target at the mucosal surface to induce the strongest immune response and the most protective immune response,” Griebel says.
Vaccines that target dendritic cells could not only protect newborns, but could also help adults fight mucosal infections like HIV or influenza.