Digestive fluid molecule linked to slower MS progression

Higher levels of bile acids in the blood – molecules in bile that aid in fat absorption – are associated with slower progression of multiple sclerosis (MS), according to a study by US researchers.

A small clinical trial involving people with progressive MS showed that daily supplements of a bile acid called tauroursodeoxycholic acid (TUDCA) reduced levels of specific pro-inflammatory immune cells in the blood.

They didn’t cause significantly better clinical outcomes when compared with a placebo, but the researchers said this was likely down to the short treatment period and follow-up.

Previous studies have shown that people with progressive MS often have lower levels of bile acid metabolites, and animal studies have suggested that bile acid supplements may offer some protection and lessen disease severity. But how these supplements impact people living with MS has been unclear.

To investigate further, researchers at Johns Hopkins University School of Medicine in Maryland examined the connection between bile acid levels and disease progression in people with MS. They studied 107 patients with available MRI brain scans and 192 who had retinal scans using optical coherence tomography (OCT).

Findings revealed that higher levels of primary bile acids (those made in the liver) were linked to slower brain atrophy, as shown by MRI scans. In the OCT group, people with higher bile acid levels at the study’s start had slower degeneration in a specific layer of the eye containing photoreceptor cells, which are responsible for collecting light.

“Overall, these data show that baseline levels of circulating bile acid metabolites are linked with slower MS progression based on imaging,” the researchers noted.

Building on these findings, the team conducted a Phase 1/2 clinical trial to test TUDCA’s impact on adults with progressive MS. The trial included 54 participants, with 26 having primary progressive MS and 28 with secondary progressive MS. Participants received either 1g of TUDCA twice daily or a placebo over about four months.

Data revealed that TUDCA supplementation significantly raised TUDCA levels in the blood and increased levels of other bile acids. It also reduced certain types of immune T-cells compared to the placebo and influenced the composition of gut microbiota.

Despite these effects, TUDCA did not show significant benefits on several clinical assessments. The researchers concluded that a larger, longer trial would likely be needed to understand TUDCA’s potential effects on disease severity in MS.