The lung-on-a-chip model provides a new perspective on how the body responds to early TB infection. The development will help in future research on respiratory and other infections, including COVID-19, according to eLife magazine.

Tuberculosis is a disease caused by the bacterium Mycobacterium tuberculosis (M. tuberculosis) and most often affects the lungs. The model developed by scientists demonstrates that the respiratory system cells (alveolar epithelial cells) play an important role in the fight against infection at an early stage. They produce a substance called surfactant (a mixture of lipids and proteins) that reduces the surface tension in the areas of the lungs where air and fluid are most common.

These results add to the scientists’ understanding of what happens in the early stages of tuberculosis infection. The new data also partly explains why smokers or people with impaired surfactant production are more likely to contract a primary or recurrent respiratory infection.

Tuberculosis affects people of all ages. Although the disease primarily affects adults, there are currently no effective vaccines for this group. This is partly due to the difficulty in studying the early stages of infection, which occurs when only one or two M. tuberculosis bacteria are deposited deep in the lungs. The creation of the light-on-a-chip model allows scientists to investigate early infection processes.

The team used their lung-on-a-chip model to recreate a surfactant deficiency produced by alveolar epithelial cells and then see how lung cells respond to early TB infection. Their studies showed that a lack of surfactant leads to the uncontrolled and rapid growth of bacteria both in macrophages and in the alveolar epithelium cells. Also, the presence of a surfactant significantly reduces this growth in both cells, and in some cases, completely prevents it.

The study authors state that they are now using the model to study how the lungs might respond to a low dose of infection and the novel coronavirus vaccine.