Tuberculosis (TB) is an infectious disease caused by the bacteria Mycobacterium tuberculosis. While the bacteria primarily attack the lungs, they can also affect the brain, spine, kidney, and other parts of the body.
M. tuberculosis is an airborne bacterium; when a person with TB in the lungs or throat coughs, sneezes, or even speaks, TB bacteria enter the air, where they can be inhaled by another person, though not all individuals infected with the bacteria become ill.
Still, last year, TB infected around 10.4 million people across the globe, causing around 1.8 million deaths - 95 percent of which occurred in low- and middle-income countries.
While there are vaccines that can prevent TB and drugs that can treat it, TB bacteria are becoming increasingly resistant to current medications.
Last year, around 480,000 TB cases worldwide were multidrug-resistant, and only 52 percent of these cases were successfully treated.
TB bacteria trigger autoimmunity
Now, a new study may pave the way for new vaccines and drugs for TB, after finding evidence that suggests TB "tricks" the immune system into attacking the lungs, enabling the bacteria to become more infectious.
The research team - led by Prof. Paul Elkington of the University of Southampton in the United Kingdom - reviewed a number of published studies that looked at the TB infection process.
The review - published in the journal Trends in Immunology - uncovered evidence that TB bacteria trigger autoimmunity, prompting the immune system to launch an attack on healthy lung tissue.
"It seems that TB tricks the immune system into damaging our own lung tissue, which therefore makes the person highly infectious through coughing and the TB then spreads by aerosol droplets to other individuals."
Prof. Paul Elkington
The researchers believe this theory is feasible, given that some patients with TB also experience eye and joint inflammation and skin rashes - symptoms that are not normally associated with TB, but which arise in certain autoimmune diseases.
"These symptoms are usually associated with diseases like rheumatoid arthritis and Crohn's disease, which led us to believe autoimmunity plays a key role in the TB disease process," notes Prof. Elkington.
The authors emphasize that more research is warranted to confirm whether autoimmunity is involved in TB infection; they plan to isolate cells from patients with TB and use 3-D microengineering to better determine how TB bacteria damage the lungs.
If their hypothesis is proven true, the researchers believe it could have significant implications for the development of new vaccines and drug therapies for TB.