Research

Two studies appearing back-to-back in PubMed today evaluated agents with potential neuroprotective activities for efficacy in MS. One of the studies came out with a positive finding, the other produced no evidence for efficacy.

The first study evaluated an oral drug called ibudilast which belongs to a class called phosphodiesterase inhibitors. This drug is used in Japan and Korea to treat asthma and cerebrovascular disorders. Based on pilot MS trial results and hints of possible neuroprotective effects in animal studies, a group of investigators decided to conduct a multi-center, placebo-controlled trial to see whether it would affect MS disease activity and progression. 297 people with MS participated and were randomized to 60 mg or 30 mg ibudilast daily, or placebo. At the end of 12 months, a 12-month extension followed, with placebo subjects moved to one of the two ibudilast doses.

The results of the study showed no major effect of the drug on indicators of disease activity such as number or volume of new lesions or relapses. However, subjects on ibudilast, particularly the higher dose, had lower brain atrophy rates. A comparison of MRIs showed that ibudilast treatment was associated with fewer lesions converting to MRI "persistent black holes," an indication of lasting damage. In addition, after 24 months, those subjects who had been on ibudilast from the beginning were less likely to have progressed on the EDSS scale than those who were initially on placebo.

No serious safety concerns were reported at the doses tested, so it seems that ibudilast is worth further study. Since the drug had little effect on inflammatory activity, the authors suggest studying it in conjunction with an immune-modulating drug to see if the combination results in both lower disease activity and improved brain tissue preservation.

The second study did assess this type of combination -- inosine plus IFN-beta -- but did not demonstrate the hypothesized effect on disability progression. Inosine is a precursor of uric acid, a protein which appears to be neuroprotective based on lab and animal studies, but is found in decreased levels in the serum of people with MS. 159 subjects were randomized to IFN-beta combined with either oral inosine supplements or placebo and followed for 24 months. Unfortunately, the primary endpoint of reduced risk of EDSS progression was not met; nor were any other endpoints having to do with disability or relapses. The authors conclude that the uric acid pathway and other neuroprotective mechanisms need to be better understood in MS. They also noted, as has been observed before, that success in treating EAE is not a great predictor of success in human trials.

In a recently published study, Australian MS pathologist John Prineas and his colleagues examined autopsy brain tissue of 15 people with MS (11 with early MS) to understand the process by which active MS lesions expand. They examined tissue sections from 10 active lesions using staining methods and microscopy to identify the features of the samples and perform counts of the cells found there. The types of immune cells identified included T cells, B cells, microglia (immune cells of the central nervous system that can become phagocytes, which clean up debris), and dendritic cells (immune cells that display fragments on their surface to activate other immune cells). The study describes what they found in the lesions, working from the outside in:

• Normal appearing white matter bordering MS lesions: These areas contained activated microglia; antibodies binding to some astrocytes, axons, and oligodendrocytes; and dendritic cells along blood vessels. No T or B cells were present.
• Outer borders of active MS lesions ("pre-phagocytic"): Decreased numbers of oligodendrocyte cell bodies were seen; remaining oligodendrocytes were sometimes swollen or showed signs of dying. Myelin sheaths were still intact although they were often swollen due to fluid having gotten in between their layers. These areas had a small increase in activated microglia and a small number of T cells.
• Actively demyelinating areas ("phagocytic"): These sites contained myelin debris which was being taken up by local microglia as well as phagocytes entering the lesion from the bloodstream. A small to moderate increase in the number of T cells was seen in these areas, as well as increased numbers of T and B cells in the space adjacent to blood vessels.
• Recently demyelinated tissue: These tissues were full of myelin-containing phagocytes. Signs of early remyelination were present including the appearance of small numbers of oligodendrocytes. Numerous T cells were found throughout the area, and large numbers of T cells, B cells, and other immune cells were concentrated around blood vessels (perivascular cuffs).
• Inactive lesions: As in the outer border of active lesions, the borders of inactive lesions contained activated microglia, and dendritic cells were also found around blood vessels.

In a couple of cases of acute, rapidly fatal MS (disease duration of only 18 or 21 days), the level of inflammation in active lesions was much lower than in the other subjects. Also, the microglia bordering the lesions showed no sign of activation.

The authors interpret their findings to indicate that plaques grow through loss of oligodendrocytes on the plaque border, which is followed by myelin breakdown, scavenging of debris by phagocytes, and infiltration of immune cells such as T cells. What causes the oligodendrocytes to die is not known -- for instance, it could be toxic elements seeping outward from the plaque, factors produced by activated microglia, or something else. The fact that T cells are not abundant in areas where phagocytes are actively scavenging myelin debris suggests that this process is not activated by T cells but instead is initiated by the macrophages themselves, similar to what is seen in injured tissue. The presence of T and B cells in greater numbers in recently demyelinated tissue indicates that these cells are part of the immune system's response to demyelination, as opposed to being a driver of the demyelination. Also, the fact that these cells are present where remyelination is taking place suggests that they don't prevent the regeneration process and may even help it.

Although this study doesn't reveal the critically important initial cause of oligodendrocyte death that drives lesion growth, having a better idea of the sequence of events nevertheless helps enrich our understanding of the disease. It's also interesting that inactive lesions remain surrounded by a sentinel of activated microglia and dendritic cells. Perhaps as these cells build up throughout the course of the disease, they provide a continual inflammatory presence that in time has an additional effect independent of relapses.

Thanks to MSNews reader Rob Swenson for the pointer to this study!

We've previously reported on imaging and surgical results suggesting that impaired blood drainage from the CNS is associated with MS (chronic cerebrospinal venous insufficiency, or CCSVI). One of the criticisms of this work is that it was conducted at a single center using ultrasound, a technique which can produce varying results across operators. So there have been calls for replication of this study, and as a result several centers have stepped up to answer these calls.

One of these centers, based at the University of Buffalo, has gotten off to a fast start and is reporting preliminary results from an imaging study that evaluated 500 people (MS subjects and controls). Participants in this study (Combined Transcranial and Extracranial Venous Doppler Evaluation (CTEVD)) were imaged with both Doppler ultrasound and MRI. These preliminary results showed that 56% of the MS subjects and 22% of the controls met two of the five criteria developed to confirm CCSVI. These results were not quite as striking as the original results presented by Dr. Zamboni, which showed complete association of CCSVI with MS. However, they certainly are strong enough to compel further investigation in this area.

This preliminary report only gave a glimpse into the findings from this study; full results will be revealed at the next American Academy of Neurology meeting in April.

The first-line MS therapies (interferon beta and glatiramer acetate) have the benefit of long track records and good safety profiles, but they're not effective in everyone. Many of those who start one of these drugs but go on to have further relapses wind up switching therapies. However, another potential option is to add on another drug that might have a synergistic effect with the MS therapy. Recently two studies were reported that tested this strategy in people with MS who had tried interferon-beta but continued to have disease activity.

The CHOICE study was a 24-week, multi-center study that evaluated adding daclizumab to IFN-beta in people with MS. Daclizumab is a drug that is used to prevent rejection of transplanted tissues. It controls T cell expansion by binding to the CD25 molecule; this molecule is expressed by T cells and helps transmit signals that initiate cell division. In this study, 230 people who had been taking IFN-beta but who still had disease activity were randomized to added-on high-dose daclizumab, low-dose daclizumab, or placebo. The primary outcome of reducing the development of new or enlarged enhancing lesions was met, with the high-dose daclizumab group having on average only 1.32 of these events over the 24 weeks vs. 4.75 for the placebo group. This difference may be related to a 7-8 times increase in a type of immune cell called "CD56bright natural killer cells" for the daclizumab recipients vs. the placebo group. New trials to further evaluate daclizumab in MS are currently underway.

The ACTIVE trial studied adding on statins (namely, atorvastatin or Lipitor) to IFN-beta in people who had also been on IFN-beta for a while but continued to have relapses or new lesions. 45 people were randomized to IFN-beta plus statin (20 mg/day) or placebo and followed for 24 months. At the end of the study, the statin group had a significant reduction in enhancing lesions and relapses compared with baseline values, whereas the placebo group also had reductions in these measures but they were not significant. Other trials have assessed the impact of statins on MS before, with mixed results. Although this study was small in terms of numbers, it had the longest duration of any MS statin trial to date. A previous small study produced evidence that IFN-beta plus higher doses of atorvastatin may aggravate MS, but the ACTIVE study results showed the oppostive effect; this difference may be due to dose.

It's been said that "the only constant is change," and while this applies to everyone, it applies even more to people with MS. A study in the American Journal of Occupational Therapy describes how the effects of MS can change a person's ability to engage in occupations or activities they need or want to participate in. The study was based on in-depth interviews with 10 people with MS who described how their disease has limited their participation in activities, and how these restrictions have affected their self-identity. Continual change meant continual struggle for these people, and often resulted in a significantly different life.

Some of the themes emerging from the analysis include the following: Difficulties in performing activities, limitations in the choices available, and lack of ability to plan ahead each contribute to decreased engagement in occupations. The struggle to stay involved in activities is influenced by society (e.g., availability of social service support), by social interactions and attitudes, and physical restrictions such as fatigue. However, self-esteem is influenced by one's capability to do things -- and therefore incapability can lead to feelings of being a burden or a "nobody." Although some of the interviewees felt that restrictions on activities diminished their life, others hoped to regain some of their former activities in the future, or found a "silver lining" in their more restrained life, such as having more time to spend with children.

This article is addressed to occupational therapists who work with people with MS. The authors wanted their readers to understand the factors affecting engagement in activities that go beyond just the physical ability to perform tasks. However, it may also be of interest to people with MS or their families and friends in anticipating and adapting to changes resulting from MS so that engagement in meaningful activities remains a part of life. A full-text version is available here (try to ignore the ads...).

The New England Journal of Medicine recently published the results of three major studies of oral therapies being tested for treating MS:

• FREEDOMS -- a two-year trial of fingolimod (aka FTY720) that was completed by 1,033 subjects given either high-dose or low-dose fingolimod or placebo
• TRANSFORMS -- a one-year trial of fingolimod that was completed by 1,153 subjects given either high-dose or low-dose fingolimod or Avonex (interferon-1a)
• CLARITY -- a two-year trial of oral cladribine that was completed by 1,184 subjects given either high-dose or low-dose oral cladribine or placebo

Oral cladribine is being developed by Merck Serono and fingolimod is being developed by Novartis. These two drugs are thought to have the best chances to become the first oral disease-modifying drugs approved for treating MS. Their biological effects are different. Fingolimod works to trap immune cells in lymph nodes, preventing them from circulating; it may also have a neuroprotective effect. Cladribine wipes out T and B immune cells and thereby dampens the inflammatory response. Fingolimod is taken on a daily basis, while cladribine is taken over the course of a few weeks in a year.

Each of these trials found the study drug to be significantly superior to placebo (CLARITY and FREEDOMS) or Avonex (TRANSFORMS) in multiple aspects. Both drugs showed a relative reduction in relapse rate (on the order of 40-60%) compared to placebo or Avonex, as well as better MRI results. CLARITY and FREEDOMS also found a beneficial effect of the two drugs on delaying disability progression. However, the results also describe a number of adverse events that occurred during the trials. Most of these were mild or moderate, but there were also some serious adverse events including a few fatalities. Reported adverse events included infections, such as herpes virus infections, cardiac abnormalities, macular edema (swelling of the retina), and various cancers/tumors. In addition, as we've seen with Tysabri, other adverse events may come to light with longer-term usage of these drugs. As the authors of the studies themselves point out, fingolimod and cladribine may have many potential benefits for treating MS, but these benefits need to be weighed against the potential risks.

These results are available to read for FREE on the journal's website (just click on the name of the study in the list above). You can also read an editorial by Dr. William Carroll discussing these studies, or see the press releases provided by Novartis and EMD Serono. I highly encourage anyone who is considering trying cladribine or fingolimod if/when they are approved by the FDA to take advantage of this opportunity to learn more about these drugs.

One question about MS that really interests me is why severity of symptoms can vary so widely among people with the same diagnosis. It seems that if this was better understood, perhaps the knowledge about the less-severe forms could be turned into therapies, or at least people diagnosed with MS could get a better sense of what may lie ahead for them. Here are a couple of recent studies from research teams looking into this topic.

The first study comes from a group of Italian researchers who looked carefully at MRIs from people with benign MS (EDSS <=3 with disease duration >= 10 years) for clues as to why their motor function was relatively unimpaired. These subjects were first screened for cognitive function to rule out significant problems which would contradict the determination of "benign MS." By analyzing MRI measurements in motor-related brain regions and the spinal cord, and comparing them against those from healthy controls, the researchers found something interesting. In the people with benign MS, there was evidence of gray matter volume loss in the brain and extensive demyelination in the spinal cord. However, a measurement called fractional anisotropy (FA) that reflects the integrity of the axonal pathways in the spinal cord was the same in the MS group compared with the controls. Whether the disease mechanisms at work in MS tend to spare spinal cord axons in benign MS, or whether these results are due to strong axonal repair/plasticity mechanisms in people with benign MS, still remains to be seen.

The second study looked at why intellectual enrichment appears to protect against cognitive decline in MS and other neurological diseases. This study was carried out at UMDNJ-New Jersey Medical School where 18 people with MS were recruited. Each person was assessed for vocabulary knowledge as a measure of educational attainment, and each was given MRIs, including functional MRIs showing which brain areas were active while the subjects performed cognitive tests.

Having greater educational enrichment didn't result in less brain atrophy or better performance on simple cognitive tests. However, greater enrichment was associated with better scores on more complicated tests. Furthermore, enrichment level appeared to affect the types of brain networks that were used while performing these cognitive tests. MS subjects with higher intellectual enrichment were able to use their "default network" (brain areas active during rest) during the cognitive tests more than those with lower enrichment, who had to recruit other brain areas more heavily while performing the tests. This shift away from the default network has been seen in other neurological conditions as well as in aging, and is thought to represent cerebral inefficiency. The authors interpret these results to mean that greater intellectual enrichment doesn't provide complete protection against brain atrophy and cognitive decline, but does give people with MS more of a buffer before cognitive effects become apparent. Also, exactly how intellectual enrichment connects with cerebral efficiency is not yet known, but if it turns out that there's a direct effect, perhaps cognitive training of people with MS can help build up this buffer as well.

If you, like me, watch the TV show "House," you'll be familiar with the concept that tumors in the body can over-secrete all kinds of substances which can cause baffling symptoms (baffling to the doctors on "House," anyway!). Here's a very interesting case study of that exact phenomenon in a man diagnosed with MS. (This link should lead to an open-access copy if you'd like to read the article for yourself.)

As the case study describes, the man went to the doctor at age 32 with symptoms of optic neuritis and leg weakness. MRI imaging revealed demyelinating lesions as well as a tumor on his pituitary gland (an adenoma) that was secreting excess prolactin. Prolactin is a hormone that stimulates the production of breast milk, but it can also have strong effects on the immune system (both stimulatory and inhibitory effects depending on other factors). CSF testing also revealed the presence of oligoclonal bands, a strong diagnostic marker of MS. The man's tumor was removed and he remained MS symptom-free and prolactin-normal for the next 12 years. Then the tumor came back, his prolactin levels rose, and he simultaneously developed new MS symptoms and MRI lesions. The man is now being treated with a prolactin-lowering drug, and has been in remission apart from one breakthrough episode of high prolactin levels and new MS lesions.

Although suppressing prolactin in this man correlated with suppression of his MS activity as well, it's hard to generalize this example to others with MS. Interestingly, prolactin levels in pregnant women reach levels that are many times higher than reported in this case study, and pregnancy and breastfeeding are both associated with lower relapse rates in women with MS. Furthermore, case-control studies have not found significantly higher levels of prolactin in people with MS. Still, unusual cases like this can sometimes be very informative -- so understanding why prolactin seems to be such a strong MS trigger in this man could lead to new insights about MS.

I always enjoy learning about whizzy new technologies -- especially those that are developed for medical research -- and especially those that are applied to understanding MS, because we need all the help we can get! This gene expression study takes advantage of a new technology called laser capture microdissection (LCM) to isolate individual cells in a tissue sample for analysis.

Studying gene expression in MS brain lesions vs. MS normal appearing brain tissue vs. non-MS control brain tissue has provided many insights into the proteins that the different cells in the brain are producing. These studies show which genes are activated (or de-activated), either as part of the disease or as part of the body's response to the disease. Most of these studies have looked at gene expression in blocks of tissue which contain many different cell types. However, by using LCM, scientists are able to analyze gene expression in just a certain type of cell -- in the case of this study, endothelial cells which form the blood-brain barrier. It's a painstaking process but it provides for a clearer picture of gene expression differences in just that specific type of cell.

The study did identify several genes that were expressed at higher or lower levels in the endothelial cells within MS lesions. For example, ICAM-2, which helps immune cells adhere to the surface of blood vessels so they can migrate into the tissue, was expressed at higher levels in lesions. By fine-tuning the measurement of gene expression in certain types of brain cells, LCM can increase our understanding of disease mechanisms and perhaps lead to new drug targets for MS.

Through brain tissue studies, scientists have known for a long time that the presence and activity of immune cells in the brain is a characteristic of MS. However, not much is known about how and why they are there. For instance, these cells need to cross the blood-brain barrier, a tight formation of blood vessel cells and cells surrounding the blood vessels that limits access to the brain. How they do this is not known.

However, a team of German scientists have now described part of this process, at least as it occurs in rats with the mouse model EAE. I encourage you to read the very interesting press release from the Max Planck Institute and watch the video from the experiment. They rigged a special optical camera to monitor the activities of fluorescently labeled T cells as they moved through blood vessels in the animal. The cells flowed normally in areas outside the brain, but when they got to the brain, some of the cells were seen to cling to the inside surface of the blood vessel. Furthermore, they began to "crawl" on the surface of the blood vessel, even going upstream, as if moving toward the source of a signal. After a while, some of the cells squeezed through the blood vessel walls into the brain. Once there, the T cells crawled again on the outside surface of the vessel until they touched a phagocyte (a type of cell that cleans up debris and can activate T cells). The scientists observed that many more T cells came through the barrier in locations where an inside T cell had made contact with a phagocyte -- indicating that the T cell had been activated and was sending out its own signals.

Finally, the team reported that MS antibody-based drugs (e.g., Tysabri) inhibited the crawling behavior of the T cells.

This type of imaging is something that could not ethically be done in humans, but it seems likely that the cellular behavior seen in this experiment is representative of what happens in other species as well. The team would next like to identify what signals guide the T cell behaviors (stopping, crawling, etc.) that they observed and potentially use this information to develop new MS treatments.