Arunachal community throws light on TB bacteria

A tribal community living in a remote corner of Arunachal Pradesh has helped scientists understand how tuberculosis bacteria can hide inside the body for years, evading detection.

Researchers found that the TB bacteria lived in a dormant state inside a particular class of stem cells in the bone marrow, escaping drugs and even the body’s immunity system.

Though in its early days, the new research, published in the “Science Translational Medicine” on Wednesday, may lead to development of new drug against TB. Around 1,000 Indians die of TB every day.

Not only did team members comprising researchers from Stanford University, Forsyth Institute in Massachusetts and Hospital for Sick Children in Toronto, along with doctors in the north-east, find genetic material from the TB bacteria in those stem cells, but they also isolated bacteria from the cells of TB patients from Arunachal Pradesh’s Idu-Mishmi tribe. The bacteria target mesenchymal stem cells. It can stay there for long even after drug was administered, as was found in case of nine patients from the tribal community.

“The infection is in a large number of people, only a fraction of which show disease symptoms,” Deepjyoti Kalita, a microbiologist from Gauhati Medical College and a team member told Deccan Herald.

The Idu-Mishmi community, with a population of around 20,000, live an isolated life in the Lower Dibang Valley district of Arunachal Pradesh.

Unlike the urban population, which tends to consult doctors, the only drugs available to this community are the ones provided by the government’s DOTS (directly observed therapy short course) programme for TB control.

“We now need to learn how the bacteria finds and infects this tiny population of stem cells and what triggers it to reactivate years or decades after successful treatment of the disease,” said Standard University’s Bikul Das, who first noticed the presence of the TB bacteria in the bone marrow while attending to patients in Bhutan.

The scientists carried out the study in the laboratory and on mouse before moving to the human population. The first hint, Das claimed, came from Bhutan where he went to “live in peace do self-training in clinical medicine”.

“ While treating TB patients, we found tuberculosis bacteria in bone marrow biopsies obtained from some of these patients for other reasons. This was a totally unexpected and accidental finding, but it gave me the idea that the bacteria could be infiltrating these cells," he said.

“ This study further vouch for our earlier observation that mesenchymal stem cells play important role in establishing latent infection. I strongly believe these stem cells are important targets for designing therapy,” said Gobardhan Das, a professor at University of Kwazulu-Natal in Durban who is not linked to the study but worked on similar area while researching in Delhi.