New research using human lung samples and three-dimensional bioengineering techniques to replicate the lung environment has revealed the important role of a subset of immune cells in the lung in fighting tuberculosis. The cells, called T Helper 17 cells or Th17, are important in animal models of TB but are rarely detected in humans’ blood, so their importance in human disease has not been clear until now. TB, a bacterial disease that mainly affects the lung, remains one of the leading causes of death in South Africa, and the World Health Organization estimates that in 2019 1.4 million people died from the disease globally. They found that the type of immune cells in TB-infected lung was significantly different than what is seen in the blood.
In particular, they found Th17 cells were highly enriched in the lung. They found that the presence of IL-17, the molecule that Th17 cells produce, reduces the growth of TB bacteria. This data confirms that Th17 cells are likely to have a protective role in humans and gives researchers a new focus for vaccine strategies.
“There is a strong case that the slow progress in TB control strategies could be, in part, because we have been studying TB in the ‘wrong place’.” Dr. Ogongo joined AHRI from the Institute of Primate Research in Kenya and is now based at the University of California, San Francisco, in Prof Joel Ernst’s group where his work on the human TB immune response continues. “The cutting-edge tissue culture technologies developed by their group have been transferred to AHRI, meaning we can run these experiments here. In turn, due to the high burden of disease in South Africa and our dedicated clinical collaborators, led by Dr. Raj Madansein, we can access the lung tissue that makes these discoveries possible”.