Researchers in Italy may have found a way to ward off multiple sclerosis (MS) in those at high risk of developing the condition. According to a new study published today in the journal Neurology, a vaccine against tuberculosis (TB) could play a key role in keeping those who show early signs of the disease from progressing to MS.
“Sclerosis” is the Latin word for “scaring,” so multiple sclerosis means “many scars” or lesions on a person’s spinal cord and brain. According to the MacDonald Criteria used to diagnose MS, more than one episode—resulting in multiple lesions or scars—is required for a definite MS diagnosis.
Patients who have only had MS-like symptoms once are classified as having clinical isolated syndrome (CIS). Only about half of those with CIS go on to develop MS within two years.
Seventy-three volunteers with CIS took part in the study. About half of the participants received one shot of a live vaccine called Bacille Calmette-Guérin (BCG), which is used to prevent tuberculosis in some countries.
The rest of the volunteers received a placebo. All of the participants were given MRI scans once a month for six months, and both groups were given the MS drug interferon beta-1a (Avonex) for a year.
After the first six months, those who had received the TB vaccine showed fewer MS-like lesions on MRI scans compared to the placebo group. By the end of the study period, 58 percent of the vaccinated volunteers had not developed MS, compared 30 percent of those who had been given the placebo.
It Works, But Doctors Don't Know Why
While encouraging news, why the vaccine works is unclear. “There seems to be complex multiple effects on brain inflammation,” said study author Giovanni Ristori, M.D., Ph.D., of Sapienza University of Rome, in an interview with Healthline. “Other recent studies on BCG in autoimmunity point to a neuroprotective effect produced by cytokines [which help regulate immune response] that is especially induced by BCG.”
Even used for its original purpose, this TB vaccine “is only effective in 50 to 60 percent of all cases,” said Ristori, but researchers were motivated to study it further when a pilot study in patients diagnosed with MS revealed that “BGC was safe and effective in reducing disease activity on MRI.”
“The idea that MS is not a single disease is common among researchers,” said Ristori, and could explain why this TB vaccine was not 100 percent effective at preventing patients with CIS from developing MS.
As with any medication or therapy, safety is as important as effectiveness. “BCG proved to be safe in virtually all patients who took it,” said Ristori.
And the fact that the virus is live is no cause for concern. He points out that even the live flu vaccine has been proven safe for MS patients. “[The flu vaccine] may be even advisable just to prevent those upper respiratory infections that may favor MS relapses,” Ristori said.
“We plan to design phase III studies in people with a first demyelinating episode and possibly in subjects ‘at risk’ of MS,” said Ristori. While further studies are needed, these preliminary results promise that a vaccine for MS could be within reach.