Despite having multiple vaccines against Streptococcus pneumoniae available today, over a million people die each year due to pneumococcal infections. Mike Dorrington, a Ph.D. candidate in Dr. Dawn Bowdish's lab, is attempting to understand how to produce better vaccines by gaining a better grasp on how the immune system fights these bacteria. Mike has recently published a manuscript entitled "MARCO is required for TLR2- and NOD2-mediated responses to Streptococcus pneumoniae and clearance of pneumococcal colonization in the murine nasopharynx" in the Journal of Immunology. Mike's work focuses on the importance of macrophage scavenger receptors in immune protection against S. pneumoniae, the most common cause of bacterial pneumonia. This manuscript provides us with evidence that Macrophage Receptor with Collagenous structure (MARCO), a class A scavenger receptor, plays an integral role in establishing and maintaining the appropriate innate immune response to the bacteria in its preferred niche, the nasal passage.      

S. pneumoniae is a very common pathogen that causes fatal disease in children under the age of 5 (where it often causes meningitis) and adults over the age of 65 (where it most often presents in pneumonia). Before infectious disease occurs, bacteria colonize the nasal passages of individuals where they replicate. If the bacteria are able to persist for long enough, they will then move to the lungs, blood, or meninges and cause potentially life-threatening disease. It has previously been shown that the clearance of the bacteria from the nasal passages was dependent on an influx of macrophages to the site. These cells are able to internalize and kill the bacteria efficiently. MARCO is expressed by these active macrophages and has been shown to play a role in the recognition of the bacteria.

Dr. A.J. Robert (Bob) McGray (pictured here with sushi) and Dr. Kyle Stephenson (pictured here with beer) recently defended their PhD Theses.

Congratulations to both of you!  You have done us proud and we wish you continued success in the future.

Immune function deteriorates with age, in a process known as immunosenescence. This involves a drop in the number of newly manufactured immune cells, whose role is to engage and destroy novel pathogens, and a subsequent over-population of the immune system with old, long-lived cells. As a result, elderly individuals are more susceptible to infections and generally respond poorly to vaccines, such as seasonal influenza.

Now, Alina Lelic, a final year Ph.D. student from the Bramson lab in the McMaster Immunology Research Centre, has shown in a new study published in the journal PLoS Pathogens that a specialised class of immune cells, known as T cells, retains its functionality with age, and can respond to virus infections with the same vigour as T cells from a young person.

Congratulations to Fiona Whelan (MSc, Bowdish lab) for publishing her first manuscript “The Evolution of the class A scavenger receptors” in BMC Evolutionary Biology. The scavenger receptors are an evolutionarily ancient family of proteins required for host defence and homeostasis but teasing apart their function and even their structure has been challenging. The goal of this manuscript was to use evolution as a guide to discover how the class A scavenger receptor family was formed and to identify regions of conservation and hence probable functional importance for future study. Phagocytic receptors such as the class A scavenger receptors are integral members of the innate immune response, which is conserved in all classes of life and after reproduction and nutrient acquisition is probably the major most fundamental requirement for survival.