New mechanism of TB infection identified

Researchers, including one of Indian-origin, have identified a new way that tuberculosis bacteria get into the body, revealing a novel potential therapeutic angle to explore.

The bacterium that causes tuberculosis, Mycobacterium tuberculosis, or Mtb, previously was thought to infect the body only through inhalation and subsequent infection of cells in the lungs.

The new research found that microfold cell (M-cell) translocation is a new and previously unknown mechanism by which Mtb enters the body.

Vidhya Nair, postdoctoral researcher at The University of Texas Southwestern Medical Center, is the lead author of the study published online in the journal Cell Reports.

"The current model of disease is that when Mtb bacteria are inhaled, they reach the end of the lung - the alveolus - and then are ingested by a macrophage, a type of white blood cell that swallows and kills invading bacteria," Michael Shiloh, Assistant Professor of Internal Medicine and Microbiology at UT Southwestern said.

"Our study shows that once Mtb bacteria are inhaled, they also can enter the body directly through M-cells that line the airway tissue, and then travel to the lymph nodes and beyond,” Shiloh explained.

M-cells are specialised epithelial cells that transport particles from the airway or mucosal surface to the compartment below the cell.

"This is a key finding that suggests disease onset outside of alveolar macrophages is not only possible, but also important in the pathogenesis of tuberculosis infection," Shiloh noted.

Although further studies are necessary, potential clinical applications of the team's finding would involve developing methods or drugs that prevent Mtb from entering M-cells.

For example, preventing Mtb from attaching to receptors on the M-cell surface - such as by vaccinating against a bacterial protein - could block the bacteria's entry, infection, and spread to other organs, Shiloh said.

One of the world's most deadly diseases, tuberculosis - primarily a lung disease - infects more than eight million people and is responsible for 1.5 million deaths each year.

According to the US Centers for Disease Control and Prevention, approximately one-third of the world's population is infected with tuberculosis.