TB may be treatable with common glaucoma medication

24 Jul

Scientists have discovered a compound found in many drugs prescribed for the treatment of

glaucoma may also be effective against tuberculosis.

patient having injection
The researchers believe their discovery may shorten TB treatment, and thus tackle the problem of drug


Tuberculosis (TB) is an infectious disease caused by the bacterium Mycobacterium

tuberculosis that most commonly affects the lungs.

The World Health Organization (WHO) estimate that around 2 billion people around the world are

infected with TB bacteria, but in most cases the immune system keeps it under control.

But if the immune system becomes weak, then the bacterium gains the upper hand, spreads and

causes disease. One strategy that helps it do this is an ability to evade the immune system.

In the journal Antimicrobial Agents and Chemotherapy, the team from Michigan

State University (MUS) in East Lansing describes how the sulfa-based compound ethoxzolamide switches

off the TB bacterium’s ability to evade the immune system.

They also found the compound reduces disease symptoms in mice.

Compound ‘shuts down TB’s ability to grow in immune cells’

Senior author Robert Abramovitch, an assistant professor of microbiology, says they found ethoxzolamide stops the TB bacterium from deploying its

immune-evasion strategy, effectively “shutting down its ability to grow inside certain white blood

cells in the immune system.”

Fast facts about TB

  • TB is spread from person to person through the air
  • Over 95% of TB cases and deaths are in developing countries
  • More than 20% of TB cases worldwide are due to smoking.

Find out more about TB

TB bacteria are very good at sensing certain cues and adapting to their environment. One such cue

is a change in acidity – or pH level – that could herald an attack from the immune system.

“The compound we found inhibits TB’s ability to detect acidic environments,” Prof. Abramovitch

explains, “effectively blindfolding the bacterium so it can’t resist the immune system’s


For the study, he and his colleagues screened 273,000 compounds for any that might be effective

against the TB bacterium.

In earlier research, Prof. Abramovitch had developed a fluorescent biosensor that glows green

under conditions that mimic TB infection. They used this to screen the compounds.

They ran several tests and showed that “ethoxzolamide reduces M. tuberculosis

growth in both macrophages and infected mice.” Macrophages are a type of immune cell that the TB

bacterium invades and replicates in.

The team is excited by their find because not only may the compound be able to prevent the spread

of TB, it may also shorten the duration of treatment, and thus tackle the problem of drug


Resistance to standard anti-TB drugs is widespread. The biggest reason for this is because the

treatment takes a long time, as Prof. Abramovitch explains:

“It’s difficult for a patient to complete the entire antibiotic course required to

kill all of the bacteria. Shortening the duration will help slow the development of these resistant


He also notes that it is not necessary to kill the bacterium to stop TB. Drugs that give the

immune system a boost by blocking the pathogen’s ability to sense and evade the immune system should

also be effective.

The National Institutes of Health, AgBioResearch, the Jean P. Schultz Biomedical Research Fund,

and MSU startup funds helped finance the study.

Earlier this year, Medical News Today reported a large gene study that found new clues

on how the TB bacterium evades the immune system. In the journal

Nature Genetics, researchers from the UK and Germany describe how they found variants

in the gene ASAP1 on chromosome 8 appear to affect a person’s susceptibility to TB.

Written by Catharine Paddock PhD

Copyright: Medical News Today