A disease with a similar pathology to multiple sclerosis may shed light on ways to prevent MS-related attacks in people, says an international team of medical researchers. A study published online in the journal Brain last month1 zeroed in on a mechanism known as tissue preconditioning in a disease called Balo's concentric sclerosis.
A Rare MS-Like Disease
Like MS, Balo's concentric sclerosis (BCS) is a disease featured by extensive damage to myelin, a protective, fatty sheath that covers nerve fibers in the central nervous system. But unlike MS, Balo's concentric sclerosis is very rare and the odds of survival are grim. Reportedly, people diagnosed with this disease can die within weeks to months.2
Tissue damage in BCS appears in the form of large lesions that are made up of concentric, or centralized, rings with alternating layers of preserved and destroyed myelin. But, according to the National Multiple Sclerosis Society, doctors don't know much about why this pattern of damage occurs. Similarly, smaller lesions with concentric rings have been reported in MS.3
"We performed this study to identify why concentric lesions can be formed in a subtype of multiple sclerosis, and what we can learn from this in more general terms about the pathogenesis [origins] of MS," explained Hans Lassmannn, MD, at the Medical University of Vienna in Austria, in an interview with Priority Healthcare.
Body's Defense Mechanism
For their analysis, Lassmannn and his fellow researchers examined tissue samples taken from a small group of 14 people with acute or chronic MS. Each had concentric lesions similar to that found in Balo's concentric sclerosis. These were compared to the tissue samples taken from people with active and inactive MS who lacked this pattern of damage.
In those with BCS-like lesions, the investigators found evidence of "hypoxia-like" tissue damage involving complete loss of myelin protein and the death of myelin-making cells. Additionally, at the edges of the BCS lesions, in an outermost layer of preserved myelin, the researchers located molecules involved in "tissue preconditioning". This is a natural process by which the brain launches protective measures to prevent further damage. But this process doesn't always secure a complete victory over the oncoming immune assault that is believed to lay at the earliest origins of multiple sclerosis. When tissue preconditioning "is insufficient to stop the progression and expansion of the lesions, concentric patterns of demyelination can be formed," Lassmannn theorized.
These concentric patterns of tissue damage are fairly rare in MS among people living in Western countries, he told Priority Healthcare. "They are much more frequent in some countries in the Far East. However, small areas of concentric demyelination are much more frequently found in a subset of MS patients, provided the patients suffer from a very severe disease course."
Genetic Underpinning
In earlier studies, medical experts have found genes that played a role in tissue preconditioning located in the healthy parts of the brains of people with MS. This suggests, they say, that the body mounts a protective strategy to fend off future MS attacks. These areas of tissue preconditioning "may be resistant to further damage in an expanding lesions and may therefore remain as a layer of preserved myelinated tissue," Lassmannnn and his team reported.
Tissue preconditioning "is quite frequent" in MS lesions, as other studies have suggested, Lassmannn told Priority Healthcare. "This may represent a more general phenomenon, which allows the brain tissue to counteract the damaging effect of inflammation," he said.
Lassmannnn's group concludes that more research is needed in this area to better understand whether preconditioning is a common phenomenon in MS and whether medical experts could develop future medicines that could stimulate the body's protective mechanisms in this area.
1. Stadelmann C. Ludwin S, Tabira T et al. Tissue preconditioning may explain concentric lesions in Balo's type of multiple sclerosis. Brain 2005 Mar 17;[Epub ahead of print].
2. Karaarslan E, Altintas A, Senol U et al. Balo's concentric sclerosis: clinical findings and radiologic features of five cases. Am J Neuroradiol 2001 Aug;22(7):1362-7.
3. Revel MP, Valiente E, Gray F et al. Concentric MR patterns in multiple sclerosis. Report of two cases. J Neuroradiol 1993 Dec;20(4):252-7.
John Martin is a long-time health journalist and an editor for Priority Healthcare. His credits include coverage of health news for the website of Fox Television's The Health Network, and articles for the New York Post and other consumer and trade publications.
