Picturing the fight against Strep pneumonia

The bacterium Streptococcus pneumoniae is part of our body’s natural ecosystem but when the immune system is weakened it can turn into a formidable foe. Not only is it the most common cause of community-acquired pneumonia and meningitis in the elderly but it can lead to sepsis, and even death. While available vaccines have led to a decline in pneumococcal infections, an estimated 14 million serious infections worldwide still remain. Recently, several S. pneumoniae strains have emerged that are resistant to conventional antibiotics emphasizing the urgent need for improved vaccines and treatments against this costly pathogen.

In order to develop improved therapies, Dr. Crosby wants to first understand how healthy individuals combat S. pneumoniae. When pathogens invade the lung, the immune system’s early responders are coordinated by a highly critical, elite class of immune cells: invariant natural killer T (iNKT) cells. Although Dr. Crosby’s previous work has illustrated the profound importance of these cells, it is still not fully clear why they are so important and what their primary functions are.

To answer these questions, Dr. Crosby’s relies on cutting-edge intravital microscopy to visualize in real time which cell types engulf the bacteria, and which cells directly interact during an active S. pneumoniae infection. This will enable her to map the locations of iNKT cells as well as other immune cells within the lungs. In addition, she will look inside the iNKT cells at the genetic level to quantify which genes are turned on or turned off during infection. Of particular interest are genes that code for special messengers called cytokines and chemokines that iNKT cells us to send signals to other cells.

Her findings will grant Dr. Crosby new insight into the true complexity of the iNKT cell response to S. pneumonia and bring her one step closer to developing novel therapeutics to defeat potentially deadly lung pathogens.

6-month Update