Gut bacteria may protect women against MS

The stomach ulcer bacterium Helicobacter pylori has been associated with a lower risk of multiple sclerosis (MS) and may also play a protective role in the development of this demyelinating disease.

The research, led by Clinical Professor Allan Kermode and Dr Marzena Fabis Pedrini at the Western Australian Neuroscience Research Institute, in collaboration with Nobel Laureate, Professor Barry Marshall AC, has shown that prior infection with H. pylori is associated with a lower risk of women developing MS.

The results also provide support for the role of the ‘hygiene hypothesis’ in autoimmune disorders, which states that exposure to infections in early childhood may be required to prime the immune system and suppress the development of allergic and autoimmune conditions in later life.

The prevalence of MS, which is thought to be an autoimmune disease, has increased worldwide alongside our modern lifestyle - although the cause of this increase is not well understood.

H. pylori infects about half of the entire human population and in most people causes no symptoms.

The study is the largest to date on the relationship between H. pylori and MS - it was enabled by the Perth Demyelinating Disease Database which contains clinical and DNA information for over 80% of people registered with MS in Western Australia.

The researchers looked for evidence of prior infection with H. pylori in blood samples taken from 550 people with MS and compared these to samples from 299 age- and sex-matched healthy controls.

They found that H. pylori infection was significantly lower in women with MS than in healthy controls, indicating that the presence of H. pylori infection may reduce the risk of developing MS. The same association was not seen in men.

Prior infection with H. pylori was also associated with lower disability scores in women with MS, suggesting H. pylori infection may play a protective role in the development of MS.

The researchers speculate that infections such as H. pylori may shift the balance of the immune system to a less inflammatory state, therefore reducing the risk of immune hypersensitivity and lowering the likelihood of developing autoimmune disorders such as MS.

The study has been published in the The Journal of Neurology Neurosurgery & Psychiatry.