A recent study by McGill University showed that it is the body’s ability to “tolerate” rather than “resist” TB infection which alleviates the symptoms of the disease.
Published in the journal Science Immunology, the study highlighted the fact that “disease tolerance” is effective in lessening the consequences of the infection.
The conventional theory on host defence against infection stated that the body eradicates disease by eliminating pathogens.
Dr Maziar Divangahi, the pulmonary immunologist and professor of Medicine has been trying to figure out why a number of people infected with Mycobacterium tuberculosis (Mtb) have tolerance towards the bacteria, without receiving any treatment.
According to Dr Divangahi, this “latent tuberculosis” is a perfect example of disease tolerance and it exists within a whole quarter of the population worldwide. His study shows that it is not the body’s ability to fight the Mtb pathogen, but to prevent it, which prevents the spreading of infection.
Also, the study shows that an excessive levels of T cells, which help in fighting infection, could be harmful for the body. It shouldn’t exceed the normal levels.
Cyclophilin D (CypD), a protein in mitochondria is the central checkpoint for T cell activation. It is also essential for controlling the T cell metabolism.
Though a number of scientists and researchers have been considering T cells to be important in eliminating Mtb since the past few years. However, the research by Divangahi showed that increasing T cell activation in mice by eliminating a metabolic checkpoint unexpectedly compromised host survival, without any impact on the growth of Mtb.
Thus, considering the extensive drug resistance of various Mtb strains and the lack of a vaccine or effective antibiotics, there arises a dire need for alternative treatment approaches.
In the words of Dr Divangahi, “If we could understand the mechanisms of ‘natural immunity’ that controls TB in 90-95 per cent of infected individuals, we will able to design a novel therapy or vaccine to substantially reduce the world-wide burden of this ancient disease.”