By Meltem Karadeniz, Monash University
MELBOURNE, Sept 5 — Chances are you probably know or have met someone with the chronic neurological disease multiple sclerosis or MS.
MS affects 2.8 million people worldwide and more than 33,000 people in Australia alone. It also affects three times more women than men in Australia.
There are three different forms of MS, but 85 per cent of patients are diagnosed with relapsing remitting MS.
This form of MS is characterised by bursts of disease activity known as a relapse followed by periods of stability or remission.
However, detecting when someone is going through a relapse can be difficult, which then impacts how doctors care for and treat these patients.
Researchers are working to solve this problem by studying what happens in the immune system during a relapse.
MS develops as a result of the body’s own immune system mistakenly attacking healthy nerve cells in the brain and spinal cord.
Immune cells accidentally target the protective coating of these nerve cells, called myelin. Myelin is essential for normal nerve function as it helps electrical signals travel quickly and protects the nerves from damage.
The migration of these misdirected immune cells from the blood into the brain results in the development of a lesion. A lesion is an area of damaged nerve cells without their protective coating.
A lesion leads to communication between the brain and the rest of the body being disrupted.
Depending on which part of the brain or spinal cord is affected patients may experience different symptoms including loss of vision, altered sensation, weakness in an arm or leg, bowel and bladder issues, or problems with speech and swallowing.
Relapses can be diagnosed when patients experience new symptoms or when a new or reactivated lesion appears in their brain or spinal cord as seen on an MRI scan.
Active lesions are those with current nerve cell destruction occurring and are often characterised by high levels of inflammation.
Unfortunately, diagnosing a relapse can be difficult.
This is because MRIs are not always immediately accessible and can’t detect very minor lesions. Every patient experiences relapse differently, leading to some difficulties with diagnosis, and some patients also experience pseudo relapses.
Pseudo relapses occur when patients seem to be having a relapse episode but are actually experiencing symptoms as a result of other external triggers such as extreme heat, stress, sleep deprivation, or an infection.
Currently, there is no easily accessible and objective way to determine when a patient is experiencing a “true” relapse. This then impacts how doctors care for and treat MS patients.
Some patients tend to underreport episodes of true relapse meaning they go untreated. Others overreport pseudo relapses which then leads to them being unnecessarily treated.
This is particularly concerning because the long-term and recurrent use of steroids — the current treatment for a relapse — can cause multiple unwanted side effects.
Steroids act as a scattergun approach and are not specific to MS disease activity. Instead, they mainly work by suppressing general immune system responses.
Other treatments include disease-modifying therapies, which offer a more targeted approach, with the goal of reducing relapse risk.
But these treatments are preventative in that they aim to stop relapses, but do not treat the symptoms or damage caused by a relapse if it does occur.
Sadly, none of these treatments can completely abolish relapses.
In order to improve MS clinical care, particularly when a patient is having a relapse episode, more needs to be understood about what is going on in the patient’s immune system to both start and maintain a relapse.
Immune cells are integral in facilitating relapse and can be divided into two categories: adaptive and innate immunity.
The innate immune system is your first line of defence and offers a more general response to any threats, whilst adaptive immunity is more specialised and targeted and has the ability to remember previous infections.
Researchers tend to focus on adaptive immunity when considering complex autoimmune diseases like MS.
In fact, all of the current disease-modifying therapies in MS mainly target adaptive immune cells and most of the research in this field explores adaptive immune responses.
However, within an active MS lesion most of the immune cells actually belong to the innate immune system.
These cells can release special chemicals that initiate inflammation and are able to “eat” the protective coating on nerve cells.
Despite their abundance in MS lesions, little is known about the role of these cells during a MS relapse and what is even more confusing is that sometimes they can act in a protective manner.
Certain innate immune cells can produce chemicals to reduce inflammation in the brain as well as “clean up” the damaged area allowing other cells to come in and repair the destruction.
Better understanding these cells could completely change our whole understanding of MS.
If researchers were able to use easily accessible samples like blood to identify accurate markers of disease activity, for example a change in innate immune cells, this would hopefully lead to better diagnostics and treatments for MS and MS relapse.
One goal of Australian MS research is the discovery of such a “signature” of relapse in the blood.
This signature — which could involve cells or molecules that significantly differ between relapse and remission states — could then be used to clearly diagnose relapse, and hopefully provide clues to reduce the risk of future relapses.
Additionally, such a signature could also shed new light on what causes MS, which still remains a great mystery despite more than 50 years of research into the disease.
Meltem Karadeniz is a PhD candidate at Monash University.
Article courtesy of 360info.