Compound found to slow tuberculosis growth

By Ivana Susic

While tuberculosis rates have decreased in the United States, the rates continue to climb worldwide. According to statistics from the Center for Disease Control and Prevention, approximately one third of people worldwide are infected with TB. Each year, 9 million people are infected with the disease and nearly 2 million people die from TB-related illnesses.

Scientists at Johns Hopkins University in Baltimore discovered a new chemical compound that can inhibit the growth of an enzyme integral to the production of TB. This enzyme, methionine aminopeptidase (MetAP), which is essential to humans and other organisms, ensures proteins are manufactured correctly.

The MetAP inhibitors have successfully blocked growth of the disease in test tubes, which could lead to creating a new way to enhance current drug treatments, according to the Johns Hopkins study published in the magazine Chemistry and Biology.

Tuberculosis, an airborne disease caused by bacteria, spreads from person to person through sneezing or the persistent, violent cough that is the trademark of the disease.

Christine Sizemore, chief of the tuberculosis section in National Institute of Allergies and Infectious Diseases’ division of microbiology and infectious diseases, explained while there are only about 12,000 cases of TB a year in the United States, it has reached epidemic status in states with high levels of HIV.  Any disease that compromises the immune system makes an individual susceptible to TB.

“The two diseases often occur together as co-epidemics,” Sizemore said. “[Tuberculosis] is the leading killer of those with AIDS.”

Another troubling factor of TB is that drug-resistant strains now exist worldwide. The estimated half a million cases each year is likely an underestimate, she said.

“It affects current effectiveness,” Sizemore said. “[Drug-resistant] strains are being transmitted person to person. It’s becoming very worrisome.”

Burton Andersen, a professor of medicine at the University of Illinois at Chicago, said drug-resistant TB rates started rising because patients will feel better after a couple of weeks and assume they can stop taking the medications, which is how bacteria develop drug resistance.

“It’s a chronic problem with TB because of the prolonged treatment,” Andersen said.

The treatment for the disease currently requires regular shots of antibiotics for six months or more. Because of the weight loss associated with TB, patients sometimes “run out of muscle” in which to administer the injections, Andersen said.

Studies on the disease, like those at Johns Hopkins, and any new treatments, are beneficial to providing more cures for the disease, Andersen said.

“[New treatments are] increasing the opportunity to attack the organism,” he said. “They’ve found pathways we’ve not targeted before.”

Dr. Edward Nardell, associate professor at the Harvard School of Medicine, said TB is one of history’s greatest killers and globally still is, along with malaria and HIV. Although the disease is not as prevalent in the United States as it once was, it still affects many Americans, he said.

“The drug resistance is low, but it’s rising,” Nardell said. “But [we have to consider] immigrants, visitors from other countries … we will always have TB if the world has TB.”

While the approach the scientists from Johns Hopkins used is not new, the enzyme inhibitor they discovered is, he said.

“In the past, people discovered antibiotics [for TB] by chance,” Nardell said. “There wasn’t a lot of forethought. Now we identify the target, then develop the drug.”

Nardell said it’s important for students to understand the risks of TB because of traveling abroad. While one may feel safe in the states, other countries have very high rates that may leave the student susceptible.

“Students are flocking to parts of the world with [disease] risks,” Nardell said. “Since it’s airborne, there’s no special activity you have to do besides breathing. [Students should] investigate precautions.”