- MS progression involves immune system-driven inflammation and nerve damage, alongside gradual low-grade inflammation along old (chronic) lesion edges, contributing to their expansion over time.
- Studies have found a correlation between the size of a region of the brain, called the choroid plexus, and chronic lesion expansion.
- MS Australia-supported researchers have explored choroid plexus changes in relapsing remitting MS, examining links to chronic lesion expansion and brain volume loss.
What is the choroid plexus and its role in chronic lesion expansion?
The progression of MS is complex and involves a combination of inflammation mediated by the immune system and processes that cause nerve damage. When a new lesion is formed in the brain or spinal cord, the blood brain barrier, which normally restricts the passage of certain substances from the bloodstream to the brain, is disrupted. There is also an influx of various immune cells to the affected area.
In addition to this process, there is a gradual accumulation of “low-grade” inflammation in the brain and spinal cord. This occurs at the edges of old (chronic) lesions, causing them to expand in size over time. This has been linked to disease progression, nerve damage, brain volume loss (atrophy) and worsening disability in MS.
Several studies have investigated the role of a brain region called the choroid plexus in the MS disease process. The choroid plexus plays a vital role in regulating the composition of cerebrospinal fluid (fluid from the spinal cord) and facilitating the entry of immune cells into the brain and spinal cord. It has been suggested to be involved in the onset and progression of inflammatory processes in MS.
A recent study has shown a correlation between the size of the choroid plexus and the degree of chronic lesion expansion in relapsing remitting MS. This suggests that changes in the choroid plexus may be driving progression of chronic lesions in MS.
Another study that focused on clinically isolated syndrome (CIS), the precursor of MS, found an increase in the size of the choroid plexus during new bouts of inflammation.
So, what happens with the choroid plexus in people with relapsing remitting MS?
What did the researchers do?
In a study led by MS Australia-supported researchers, Mr Samuel Klistorner and Professor Alexander Klistorner, the team investigated how the choroid plexus changes in people living with relapsing remitting MS over time. They looked at whether it is linked to the expansion of chronic lesions and volume loss in different regions of the brain.
Published in Multiple Sclerosis Journal, the researchers assessed the choroid plexus of 57 people living with relapsing remitting MS annually using magnetic resonance imaging (MRI) techniques.
What did the researchers find?
The researchers found that the volume of the choroid plexus increased by 1.4% annually, although the extent of enlargement varied between individuals. This magnitude of enlargement correlated with a reduction in central and total brain volume, as well as the volume of the deep grey matter (consisting of nerve cells) and white matter (consisting of projections of myelinated nerve cells).
Additionally, progressive enlargement on the choroid plexus was associated with the volume of chronic lesions as well as the amount of chronic lesion expansion, but not with the number or volume of new lesions.
What is the significance of this?
This study reveals a significant finding – that the choroid plexus enlarges over time in people with relapsing remitting MS. This enlargement correlates with nerve fibre loss around chronic lesions as well as a decrease in brain volume.
These findings strongly suggest that the choroid plexus plays a pivotal role in the ongoing inflammatory process and nerve damage in relapsing remitting MS.
Mr Sam Klistorner said, “As a researcher dedicated to advancing our understanding of MS, it’s profoundly rewarding to reveal pivotal insights into how changes in the choroid plexus correlate with disease progression. This study opens new avenues for diagnosing and managing MS more effectively.”
Identifying the choroid plexus as a marker for inflammation and nerve damage could aid in early detection and monitoring of disease progression, allowing healthcare professionals to intervene earlier and delay progression.