Ancient Herbal Traditional Chinese Medicine Can Fight Malaria and TB, Says New Study
A
centuries-old herbal Chinese medicine, used to effectively treat
malaria, may help fight tuberculosis and slow the evolution of drug
resistance, scientists have found. In a study led by Robert
Abramovitch, from the Michigan State University in the US, the
ancient remedy artemisinin stopped the ability of TB-causing
bacteria, known as Mycobacterium tuberculosis, to become dormant.
This stage of
the disease often makes the use of antibiotics ineffective. “When
TB bacteria are dormant, they become highly tolerant to antibiotics,”
Abramovitch said. “Blocking dormancy makes the TB bacteria more
sensitive to these drugs and could shorten treatment times,” he
said.
Mycobacterium
tuberculosis, or Mtb, needs oxygen to thrive in the body. The immune
system starves this bacterium of oxygen to control the infection.
Abramovitch and his team found that artemisinin attacks a molecule
called heme, which is found in the Mtb oxygen sensor.
By disrupting
this sensor and essentially turning it off, the artemisinin stopped
the disease’s ability to sense how much oxygen it was getting.
“When the Mtb is starved of oxygen, it goes into a dormant state,
which protects it from the stress of low-oxygen environments,”
Abramovitch said. “If Mtb can’t sense low oxygen, then it can’t
become dormant and will die,” he said.
Abramovitch
indicated that dormant TB can remain inactive for decades in the
body. However, if the immune system weakens at some point, it can
wake back up and spread. Whether it wakes up or stays ‘asleep’
though, he said TB can take up to six months to treat and is one of
the main reasons the disease is so difficult to control. “Patients
often don’t stick to the treatment regimen because of the length of
time it takes to cure the disease,” he said.
“Incomplete
therapy plays an important role in the evolution and spread of
multi-drug resistant TB strains,” he said. The research could be
key to shortening the course of therapy because it can clear out the
dormant, hard-to-kill bacteria. This may lead to improving patient
outcomes and slowing the evolution of drug-resistant TB.
After
screening 540,000 different compounds, Abramovitch also found five
other possible chemical inhibitors that target the Mtb oxygen sensor
in various ways and could be effective in treatment as well. “TB is
a global problem that requires new tools to slow its spread and
overcome drug resistance. This new method of targeting dormant
bacteria is exciting because it shows us a new way to kill it,”
said Abramovitch.
The study was
published in the journal Nature Chemical Biology.
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