New theory explains TB symptoms

xray-lungs

Tuberculosis may cause our body's own defences to turn on us according to new evidence found by researchers from our NIHR Southampton Biomedical Research Unit.

A new theory

Tuberculosis (TB), historically known as 'consumption, is caused by a bacterial infection and can be fatal. If it affects the lungs, it can lead to symptoms such as breathlessness and coughing up blood.

While we can now immunise against TB and treat it with antibiotics, there are still many symptoms of the disease that cannot be explained by the current theory of how it develops.

Paul Elkington, Marc Tebruegge and Salah Mansour have therefore put forward a new theory, published in Trends in Immunology, which states that the bacterial infection triggers an autoimmune response that exacerbates the disease and worsens the symptoms.

Unexplained observations

Using samples from the Southampton Research Biorepository, the researchers made clinical observations and conducted experiments, providing the evidence needed to support their theory.

They argue that the current theory of how the disease develops cannot explain some observations that they made, whereas their new theory can. For example, the small number of bacteria which cause the disease is insufficient to explain the large response by the immune system.

Another unexplained observation they noted was that TB affecting the lungs is most common in young people, who have a strong immune system, whereas HIV patients with a weak immune system rarely develop the lung cavities associated with the later stages of the disease.

Striking similarities

Comparing TB symptoms with autoimmune diseases, where a person’s immune system turns against their own body, they found a number of striking similarities and shared symptoms.

In particular, they found that the autoimmune disease sarcoidosis bore such a striking resemblance to TB that they suggested the two conditions might share a common cause.

This new theory challenges current thinking, providing a new avenue for research and the potential for a better understanding of this deadly disease and improved TB treatments in the future.   

Posted on Friday 11 November 2016