blood-brain barrier (BBB)

A bacterial toxin in the gut — specifically, the epsilon toxin produced by Clostridium perfringens bacteria in the intestinal tract — may be a key environmental driver of multiple sclerosis (MS), according to a recent study. After finding the toxin at a higher abundance in the fecal samples of MS…

The protective barrier that prevents cells and large molecules from crossing into the central nervous system (CNS) is known to be unusually “leaky” in multiple sclerosis (MS), but targeting a protein called ARF6 can help to stabilize this barrier, a study in mouse models of MS found. Such a treatment…

Among multiple sclerosis (MS) patients starting on Lemtrada (alemtuzumab), an early decrease in the leakiness of the blood-brain barrier (BBB) is associated with a lower likelihood of disease activity after two years, according to a new study. The blood-brain barrier is a cellular divisor that regulates which substances…

Use of GA Depot in Treating Progressive MS Given US Patent In the area of MS treatments, one major need is for medications that treat more than just the relapsing form of our disease. GA Depot might help fill that void. The U.S. patent the medication received says it’s…

Editor’s note: “Need to Know” is a series inspired by common forum questions and comments from readers. Have a comment or question about MS? Visit our forum. This week’s question is inspired by the forum topic “How the Blood Brain Barrier May Thwart MS Progression” from Feb. 9, 2017. What…

The first patient has been dosed in a Phase 2B clinical trial evaluating the safety, efficacy, and tolerability of SAR442168 in people with relapsing multiple sclerosis (MS). SAR442168, formerly known as PRN2246, is being developed by Principia Biopharma, in collaboration with Sanofi Genzyme, for MS and other central nervous…

Oligodendrocyte precursor cells (OPCs), the cells responsible for myelin production, are unable to migrate into sites of myelin loss in the brain. These cells then cluster and disrupt the blood-brain barrier (BBB), triggering an inflammatory process in the early stages of multiple sclerosis (MS), a study shows. The study, “Aberrant oligodendroglial–vascular interactions disrupt the blood–brain barrier, triggering CNS inflammation,” was published in the journal Nature Neuroscience. MS is an autoimmune disease characterized by the loss of myelin (demyelination) — the fat-rich substance that protects nerve fibers — which leads to neurodegeneration. Along with loss of myelin, researchers have observed that the blood-brain barrier — a highly selective membrane that shields the central nervous system with its cerebrospinal fluid from the general blood circulation — breaks down in the initial stages of disease. A team led by researchers at the University of California, San Francisco, have now discovered that OPCs are involved in the disruption of the blood-brain barrier in MS, according to a press release from the National MS Society, which funded the study. Oligodendrocytes are myelin-producing cells and are responsible for myelinating the nerve cells’ axons — a single oligodendrocyte is capable of myelinating multiple axons. Mature myelin-producing oligodendrocytes develop from more immature, stem cell-like OPCs. In a normal brain, upon myelin loss, OPCs are called into action and travel into the damage site where they mature and generate myelin-producing oligodendrocytes. In this study, the researchers found that OPCs in MS form clusters in blood vessels of the brain-blood barrier, having lost the ability to detach from these vessels and migrate to injury sites. In an animal model of MS, they saw that OPC aggregates altered the location of other cells — called astrocytes — in a competition for space, and contributed to the disruption of blood vessels. Astrocytes are a group of star-shaped cells, belonging to the group of glial cells, that provide neurons with energy, and work as a platform to clean up their waste. They also have other functions within the brain, such as regulating blood flow and inflammation. The team also observed that OPC aggregates trigger an immune inflammatory response, shown by a large number of microglia (the central nervous system immune cells) and immune cells called macrophages around these cell clusters. “We find in several MS cases, in lesion areas with active inflammation, that OPCs can be found clustered on vasculature, representing a defect in single cell perivascular migration and inability to detach from blood vessels,” the researchers wrote. Further molecular analysis revealed that OPCs have high levels of Wnt signaling, and elevated secretion of Wif1 factor to the extracellular space that could explain why OPCs accumulate and destroy the blood-brain barrier. The WiF1 factor is actually a negative regulator of Wnt signaling that is essential for the maintenance of the blood-brain barrier structure. This factor competes with Wnt ligands, and affects the integrity of cellular junctions, making the blood-brain barrier more fragile and permeable. "Evidence for this defective oligodendroglial–vascular interaction in MS suggests that aberrant OPC perivascular migration not only impairs their lesion recruitment but can also act as a disease perpetuator via disruption of the BBB,” the researchers wrote. They suggested that more studies are needed to better understand the interactions between blood vessels and oligodendrocytes, which could help identify new therapeutic targets for promoting myelin repair in MS.

Podocalyxin, a protein found in cells lining the interior of blood vessels, is key for maintaining the integrity of the blood-brain barrier (BBB) in mice with systemic infection, suggesting its potential as a therapeutic target for neurodegenerative diseases such as multiple sclerosis (MS), a study shows. Disruption of the…

A protein called MMP-9 could be a predictive marker of progressive multifocal leukoencephalopathy development in patients with relapsing-remitting multiple sclerosis (RRMS) who are being treated with Tysabri (natalizumab), a study suggests. The study, “Dynamic changes of MMP-9 plasma levels correlate with JCV reactivation and immune activation in natalizumab-treated multiple sclerosis patients,” was published in the journal Nature Scientific Reports. Brain inflammation in multiple sclerosis patients occurs when immune cells breach the blood-brain barrier. This layer of cells protect the brain and its supporting fluids, such as cerebral spinal fluid (CSF), from dangerous agents circulating in blood. How easily immune cells can break through the blood-brain barrier depends on its porousness. For instance, it is known that decreasing the activity of matrix metalloproteinases (MMP) increases the protective layer’s permeability. Matrix metalloproteinases are a family of proteins responsible for the degradation of collagen and other proteins in the extracellular matrix, which provides structural and biochemical support to surrounding cells. One metalloproteinase, called MMP-9, has been extensively studied in multiple sclerosis. MMP-9 levels are elevated in the CSF of multiple sclerosis patients and considered a potential biomarker of disease activity and possible therapeutic target. Tysabri (marketed by Biogen) is one of the most effective treatments for RRMS currently available. It works by blocking the entry of immune cells into the brain. Tysabri is known to decrease MMP-9 levels in the CSF and serum in RRMS patients. However, Tysabri has been associated with an increased risk of developing progressive multifocal leukoencephalopathy (PML). This rare and often fatal viral disease, caused by the John Cunningham virus (JCV), is characterized by progressive damage and/or inflammation at multiple sites in the brain. The reduced migration of immune cells across the blood-brain barrier induced by Tysabri is thought to be the cause of this increased PML risk. Whether MMP-9 is involved in this process has not been studied. To look at this, a team led by researchers from Sapienza University and Aldo Moro University in Italy investigated MMP plasma levels following Tysabri treatment in the context of JCV. The team specifically looked at how levels of MMP-9 were linked to disease-related processes. Samples from 34 RRMS patients being treated with Tysabri (intravenous dose of 300 mg every four weeks) were analyzed. As expected, results showed that MMP-9 plasma levels stabilized within one year of Tysabri treatment (up to 12 Tysabri infusions), although they began to steadily rise afterward (between 12 and 24 infusions). These increased MMP-9 plasma levels were not associated with clinical relapses in RRMS patients. "MMP-9 levels increased in plasma accordingly with [Tysabri] infusion number," the researchers wrote. In comparing JCV-positive and JCV-negative samples, the researchers observed an increase in MMP-9 plasma levels in JCV-positive samples. This result suggested that JCV circulation in peripheral blood could be implicated in the increase of MMP-9 levels. Interestingly, increased MMP-9 plasma levels were found to be correlated with immune cell activation. "Our findings suggest a potential pathogenic role of MMP-9 in the development of progressive multifocal leukoencephalopathy during [Tysabri] treatment, and its possible use as a marker of JCV reactivation,” the researchers wrote. Future studies are nonetheless needed to confirm these findings in larger groups of RRMS patients.

Editor’s note: “Need to Know” is a series inspired by common forum questions and comments from readers. Have a comment or question about MS? Visit our forum. This week’s question was inspired by the forum topic “Do you know any natural remedies that help fight inflammation?“, from May…

Results from a first-in-human study assessing the safety and early activity of PRN2246 confirmed that the oral compound can reach into the brain and spinal cord. This finding adds new evidence that PRN2246 has the potential to target the immune cells that drive the inflammatory process involved in multiple sclerosis…

New Spherix Report Finds PPMS Treatment Increased Significantly in Past Year Primary progressive MS has, in some eyes, been the stepchild of the disease-modifying therapies. PPMS patients move steadily downhill, and some believe treatments haven’t kept pace with their disease. Now, the research company Spherix has news…

Biogen and AbbVie Voluntarily Withdraw Marketing Authorizations for MS Therapy Zinbryta You may have heard about this already, so forgive me if it’s not new to you, but it’s important information. A dozen cases of encephalitis or meningoencephalitis have been reported in patients using Zinbryta, and…