During flu season, our bodies become a battlefield, with our internal weaponry waging war against perpetually adapting armies of the influenza virus. Like any war, we must be cognizant of our arsenal and our lookouts. The incredible way our body builds up its resistance to disease hinges on the successful functioning of our personal, curated immune systems. But despite these remarkable innate lines of defense, we still get sick. So, how can we help our body fight off its enemies?
Scientists at Emory University School of Medicine believe that they have found a way. Dr. Jacob Kohleimer and his team have identified two signaling molecules, CXCR6 and CXCL16, that may hold the key to improving our immunity [1]. We know that CD8 T cells recognize epitopes, which are small segments of viral protein, and signal to the body that there is a viral infection. Through the release of cytokines, CD8 T cells can recruit other parts of the immune system and help to kill those infected cells [2]. However, T cells cannot survive long in the lungs due to their low nutrient state, which compromises lung immunity [3]. Through experimentation with mice models, the researchers were able to find populations of CD8 T cells cells in the interstitium, which is the space between the epithelial cells in the lungs and blood vessels. These epithelial cells produce CXCL16, while CXR6 can be found directly on T cells [1]. In reaction to an infection, CXCR6 acts as a homing beacon, enabling the efficient and reliable recruitment of T cells to the lungs and into the airways.
The discovery of these two signaling molecules may revolutionize how we make our vaccines. Currently, vaccines do not account for the directing of CD8 T cells to the airways; they mainly work by introducing pathogenic molecules into the body, teaching the immune system how to react if it were actually attacked [3]. But with the enhancement of these two signaling proteins, vaccines could increase the transport to and longevity of T cells in the lungs, thus decreasing or even eliminating symptoms altogether. As a result, these lookout proteins might just be the soldiers we need to win the war against foreign invaders.
References
Eastman, Q. Immunologists identify T cell homing beacons for lungs. https://news.emory.edu/stories/2019/09/jem_kohlmeier_tcells_lungs/index.html.
Harper, R. T cell homing beacons for lungs identified by researchers. https://www.drugtargetreview.com/news/50299/t-cell-homing-beacons-for-lungs-identified-by-researchers/
Emory Health Sciences. Immunologists identify T cell homing beacons for lungs. https://eurekalert.org/pub_releases/2019-09/ehs-iit092719.php.