Brain inflammation, lesions & 'black holes'
Physicians commonly measure multiple sclerosis (MS) disease activity based on the appearance of new T2-weighted hyperintense MRI lesions, which arise due to edema, inflammation, gliosis, and axonal loss. Given the nonspecific disease processes leading to these lesions and the often-mediocre correlation between T2 lesions and clinical outcomes, however, the search continues for a more specific tool that lends insight into MS pathophysiology and disease activity.
In recent years, increasing attention has been paid to the possibility of measuring chronic or persistent T1-weighted lesions that appear hypointense relative to normal-appearing white matter—lesions also known as “black holes”—as a means of gauging MS-associated neurodegeneration. This approach is supported by a considerable body of histopathological evidence indicating that chronic T1 black holes reflect irreversible demyelination and axonal loss.1
“In general, knowledge of the spatial localisation and time evolution of T1-weighted lesions may help resolve some mysterious aspects of MS, which remains a largely unresolved pathology,” explained Khader M. Hasan, PhD, an Associate Professor of Radiology at the University of Texas Medical School at Houston, in an interview with MedPage Today.
Some consider the evolution of T1 lesions to be one of the most promising endpoints in phase 2 clinical trials of neuroprotective and reparative MS interventions.2 But despite this enthusiasm, a proven link between persistent black holes and clinical outcomes in MS remains elusive. Whereas a handful of studies have pinpointed a correlation between black hole volume and clinical disability as measured by the Expanded Disability Status Scale (EDSS), several others have failed to identify such ties.1
To shed more light on whether black holes can be utilised to measure clinically relevant disease progression over time, lead investigator Nicola De Stefano, MD, PhD, an Associate Professor of Neurology at the University of Siena, Italy, and his colleagues conducted a longitudinal MRI study among a small group of 57 patients with confirmed relapsing-remitting MS for an average of 5 years. The investigators obtained brain scans of patients in 2000-2001 and again 10 years later using the same MRI protocol, thus ensuring comparable image quality at both time points. The scans were then compared to evaluate how patients’ brain lesions evolved over time and the impact of these changes on long-term disability, as measured using the EDSS.3
The majority of patients—82%—experienced disease relapse over the 10-year study period, and the average EDSS score for the total cohort worsened from 1.8±1.1 (mean [SD]) at baseline to 2.5±1.7 after 10 years (P<.001).3 In tandem, over the 10-year follow-up period mean T2 lesion volume increased from 5.8 ±6.4 to 8.3±8.1 cm3 (P<.001), and mean T1 lesion volume from 2.4±3.6 to 4.4±5 cm3 (P<.001).3
The investigators found that the long-term change in EDSS score was linked to the number of new and enlarging T1 and T2 lesions, as well as to increasing lesion volume. Notably, stepwise multiple regression analysis revealed that EDSS-measured declines in clinical disability best correlated with the combined measure of baseline T1 lesion count and increase in T1 lesion volume over time.3 Together, these factors explained 37% of the variability in worsening of the EDSS score over 10 years.3
“The finding in our study that the number of black holes at baseline and their volume increase over time were the only significant brain lesion correlates of EDSS worsening over 10 years highlights the role of neurodegeneration in the pathophysiology of long-term disability in MS,” wrote Dr. De Stefano and colleagues about their results, published in the Multiple Sclerosis Journal.3
Despite these findings, Dr. Hasan still views the relationship between T1 black holes and clinical measures of disease activity as tenuous. “Yes, black hole lesions are important, but other lesion types are also important. The lesion-centered approach in MS has not provided breakthrough insights into the pathogenesis of MS, as most MS lesions remain asymptomatic,” he commented.
One of Dr. Hasan’s biggest criticisms of the study is that the investigators provided no analysis of the possible effect of therapy. Fifty of the 57 patients received disease-modifying therapy during the study period, which makes it difficult to ascertain if and how much lesion evolution was influenced by the presence of treatment and the specific type of treatment.3 Phase 3 clinical studies that measure T1 black hole evolution may provide a deeper understanding of the ongoing disease process in MS and the possible effects of treatment.
These criticisms aside, Robert T. Naismith, MD, an Assistant Professor of Neurology at Washington University School of Medicine in St. Louis, believes that the findings from the recent Italian MRI study increase our understanding of T1 black holes in MS and may help inform treatment decisions. “The presence of black holes at baseline or their appearance during treatment should be one of several factors in predicting risk and may tip the decision toward either a first-line therapeutic with relatively high efficacy, or increased monitoring if an agent is chosen based primarily on established safety,” Dr. Naismith stated in a commentary on this study published last August in NEJM Journal Watch.4
1 Sahraian MA, Radue EW, Haller S, et al. Black holes in multiple sclerosis: definition, evolution, and clinical correlations. Acta Neurol Scand. 2010;122:1-8.
2 Barkhof F, Calabresi PA, Miller DH, et al. Imaging outcomes for neuroprotection and repair in multiple sclerosis trials. Nat Rev Neurol. 2009;5:256-266.
3 Giorgio A, Stromillo ML, Bartolozzi ML, et al. Relevance of hypointense brain MRI lesions for long-term worsening of clinical disability in relapsing multiple sclerosis. Mult Scler. 2014;20:214-219.
4 Naismith RT. “Black holes” and long-term disability in multiple sclerosis. NEJM Journal Watch. http://www.jwatch.org/na31801/2013/08/05/black-holes-and-long-term-disability-multiple-sclerosis. Published August 5, 2013. Accessed March 25, 2014.
Source: Medpage Today © 2014 Everyday Health Media, LLC (19/06/14)
Rutgers professor’s advanced analysis could let therapy start earlier and lead MS research in new directions.
The search for the cause of multiple sclerosis, a debilitating disease that affects up to two and a half million people worldwide, has confounded researchers and medical professionals for generations. But Steven Schutzer, a physician and scientist at Rutgers New Jersey Medical School, has now found an important clue why progress has been slow – it appears that most research on the origins of MS has focused on the wrong part of the brain.
Look more to the gray matter, the new findings published in the journal PLOS ONE suggest, and less to the white. That change of approach could give physicians effective tools to treat MS far earlier than ever before.
Until recently, most MS research has focused on the brain’s white matter, which contains the nerve fibers. And for good reason: Symptoms of the disease, which include muscle weakness and vision loss, occur when there is deterioration of a fatty substance called myelin, which coats nerves contained in the white matter and acts as insulation for them. When myelin in the brain is degraded, apparently by the body’s own immune system, and the nerve fiber is exposed, transmission of nerve impulses can be slowed or interrupted. So when patients’ symptoms flare up, the white matter is where the action in the brain appears to be.
But Schutzer attacked the problem from a different direction. He is one of the first scientists to analyze patients’ cerebrospinal fluid (CSF) by taking full advantage of a combination of technologies called proteomics and high-resolution mass spectrometry. “Proteins present in the clear liquid that bathes the central nervous system can be a window to physical changes that accompany neurological disease,” says Schutzer, “and the latest mass spectrometry techniques allow us to see them as never before.” In this study, he used that novel approach to compare the cerebrospinal fluid of newly diagnosed MS patients with that of longer term patients, as well as fluid taken from people with no signs of neurological disease.
What Schutzer found startled one of his co-investigators, Patricia K. Coyle of Stony Brook University in New York, one of the leading MS clinicians and researchers in the country. The proteins in the CSF of the new MS patients suggested physiological disruptions not only in the white matter of the brain where the myelin damage eventually shows up. They also pointed to substantial disruptions in the gray matter, a different part of the brain that contains the axons and dendrites and synapses that transfer signals between nerves.
Several scientists had in fact hypothesized that there might be gray matter involvement in early MS, but the technology needed to test their theories did not yet exist. Schutzer’s analysis, which Coyle calls “exquisitely sensitive,” provides the solid physical evidence for the very first time. It includes a finding that nine specific proteins associated with gray matter were far more abundant in patients who had just suffered their first attack than in longer term MS patients or in the healthy controls. “This evidence indicates gray matter may be the critical initial target in MS rather than white matter,” says Coyle. “We may have been looking in the wrong area.”
According to Coyle, that realization presents exciting possibilities. One, she says, is that patients who suffer attacks that appear related to MS could have their cerebrospinal fluid tested quickly. If proteins that point to early MS are found, helpful therapy could begin at once, before the disease can progress further.
Coyle says Schutzer’s findings may also lead one day to more effective treatments for MS with far fewer side effects. Without specific knowledge of what causes multiple sclerosis, patients now need to take medications that can broadly weaken their immune systems. These drugs slow the body’s destruction of myelin in the brain, but also degrade the immune system’s ability to keep the body healthy in other ways. By suggesting an exciting new direction for MS research, Schutzer and his team may have set the stage for more targeted treatments that attack MS while preserving other important immune functions.
Schutzer sees an even broader future for the work he is now doing. He also has used advanced analysis of cerebrospinal fluid to identify physical markers for neurological ailments that include Lyme disease, in which he has been a world leader in research for many years, as well as chronic fatigue syndrome. He says, “When techniques are refined, more medical conditions are examined, and costs per patient come down, one day there could be a broad panel of tests through which patients and their doctors can get early evidence of a variety of disorders, and use that knowledge to treat them both more quickly and far more effectively than is possible now.”
This research was funded by the National Institutes of Health.
Source: Newsfix.ca Copyright 2013 NewsFix.ca (20/11/13)