A Clue to TB Awakening

Article

The factors instrumental in triggering latent tuberculosis (TB) infection to progress into active disease have long remained elusive to researchers. New insight into the mystery is provided by professor David Russell, speaking at the Society for General Microbiology's spring meeting in Edinburgh today. His work could help develop innovative strategies for treating the disease.

Russell and his group at Cornell University in New York, have demonstrated that TB-causing bacteria are able to hijack fat metabolism in the host to drive the progression of the disease. The team's research shows that Mycobacterium tuberculosis (Mtb) is able to stimulate macrophages -- the immune cells the bacterium infects -- to accumulate fat droplets, turning them into "foamy" cells. This cellular transformation can trigger a reawakening of the TB infection from its latent state.

Following initial infection by Mtb, the infected immune cells in the body can clump together in the lungs in a cellular mass that is surrounded by a fibrous cuff. This containing structure, called a tubercle, physically protects the bacteria from being destroyed by the immune system. This allows them to persist inside the host for years during a latent period in which the host shows no symptoms. The respiratory infection is reactivated only in a small percentage of individuals (often those who are immunosuppressed) in whom it progressively destroys lung tissue. Very little is known about the exact causes of reactivation and the relative roles of the host and the pathogen.

Russell's group discovered that inside the tubercle, surface molecules of Mtb prompted host macrophage cells to take up vast quantities of cholesterol-type lipids from the surrounding blood vessels. "We think that the lipids in the newly-formed foamy cell are then expelled into the cellular environment, which contributes to the collapse of the tubercle," he said.

Once freed from their containing structure, the infectious bacteria are able to leak out into the airways where they can progressively destroy lung tissue. "If our model is correct, it has huge implications for vaccines and chemotherapy programs. A more detailed knowledge of the bacterium's life cycle and its host interactions will allow us to spot new targets for drugs -- opening up new possibilities for treatment," said Russell.

Related Videos
Anne Meneghetti, MD, speaking with Infection Control Today
Patient Safety: Infection Control Today's Trending Topic for March
Infection Control Today® (ICT®) talks with John Kimsey, vice president of processing optimization and customer success for Steris.
Picture at AORN’s International Surgical Conference & Expo 2024
Infection Control Today and Contagion are collaborating for Rare Disease Month.
Rare Disease Month: An Infection Control Today® and Contagion® collaboration.
Vaccine conspiracy theory vector illustration word cloud  (Adobe Stock 460719898 by Colored Lights)
Rare Disease Month: An Infection Control Today® and Contagion® collaboration.
Infection Control Today Topic of the Month: Mental Health
Related Content