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Patricia Inacio, PhD

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Patricia holds her PhD in cell biology from the University Nova de Lisboa, Portugal, and has served as an author on several research projects and fellowships, as well as major grant applications for European agencies. She also served as a PhD student research assistant in the Department of Microbiology & Immunology, Columbia University, New York, for which she was awarded a Luso-American Development Foundation (FLAD) fellowship.

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Articles by Patricia Inacio, PhD

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Oligodendrocyte Precursor Cells Disrupt Blood-brain Barrier, Trigger Brain Inflammation in MS, Study Shows

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.

News

Genetic Variants in Inflammasome Genes Influence MS Severity, Progression, Study Suggests

Genetic variants that enhance the activity of the NLRP3 inflammasome or the interleukin-1 beta cytokine are linked to higher severity and progression of multiple sclerosis, a study suggests. Previous studies with mouse models of MS have shown that a complex of innate immune system receptors and sensors, known as the inflammasome, is likely a player promoting the immune system’s attack on the central nervous system in MS and, consequently, the loss of myelin. Follow-up studies showed that people carrying mutations that enhance the function of the NLRP3 inflammasome — one of the three components of the inflammasome complex — had a worse prognosis, once again supporting the role of the inflammasome in MS. Once activated, the inflammasome triggers an enzyme called caspase-1 that promotes the production of two very powerful proinflammatory cytokines called interleukin (IL)-1 beta and IL-18. To further evaluate the role of the inflammasome in MS, a team led by researchers at the Universidade de Sao Paulo in Brazil analyzed the genetic sequence of five inflammasome genes — NLRP1, NLRP3, NLRC4, IL-1 beta, and IL-18 — in blood samples retrieved from 264 patients diagnosed with MS or other demyelinating diseases. They also analyzed 233 healthy individuals used as controls. The team specifically looked at eight variations in certain nucleotides (the building blocks of DNA), called single nucleotide polymorphisms (SNPs). Previous studies reported a link between SNPs in inflammasome-related genes and certain forms of MS. Results showed that SNPs associated with low serum levels of IL-18 were significantly less frequent in MS patients than in controls. In contrast, variants that enhance the function of NLRP3 and IL-1 beta were associated with severity and progression of MS, as measured by the Expanded Disability Status Scale. These results suggest that the "activation of NLRP3 inflammasome could represent a risk factor for MS clinical presentation,” the researchers wrote. A particular variant in the NLRC4 gene was less frequent in patients whose disease progressed rapidly compared with those who had a slower disease, an intriguing observation, according to researchers, suggestive of a “protection effect of this variant against a bad prognosis.” Carriers of this variant also responded better to treatment with interferon-beta. Regarding MS type, the genetic variant that promotes the function of the IL-1 beta gene was significantly more frequent in progressive forms of MS than in relapsing-remitting MS, strengthening once again the negative effects of IL-1 beta in the disease. An analysis of inflammasome activity in blood monocytes, a group of immune cells, showed that the inflammasome is permanently activated in MS compared with healthy controls. "This study emphasizes that a constitutive activation of NLRP3 inflammasome, principally through IL-1 beta production, represents a risk factor for both the development of MS and the progression to severe forms of the disease. On the other hand, low IL-18 production and/or NLRC4 activation were beneficial for MS patients,” the team concluded.

News

Gilenya Better at Lowering Relapse Rate than Tecfidera or Aubagio, Study Suggests

Gilenya is linked to significantly lower annualized relapse rates in relapsing-remitting multiple sclerosis (RRMS) patients compared to Tecfidera or Aubagio, a study suggests. All three therapies showed similar effects on disability outcomes. Oral immunotherapies — including Novartis’ Gilenya, Biogen’s Tecfidera, and Sanofi Genzyme’s Aubagio — are currently standard therapies for RRMS treatment. But while these therapies are highly effective at modulating MS activity, studies comparing their efficacy on relapse and disability are missing. This is an important point for MS patients, so that if a change in oral therapies is needed (due to lack of tolerance, for example), the decision on a more suitable therapy is based on scientific evidence. To address this matter, a group of researchers used the MsBase, an international observational MS cohort study, to identify RRMS patients who had been treated with Gilenya, Tecfidera, or Aubagio for at least three months. The team compared Tecfidera versus Aubagio, Gilenya versus Aubagio, and Gilenya versus Tecfidera, specifically for the therapy’s impact on relapse activity, six-month disability worsening or improvement, and persistence of treatment. Relapse was defined as the occurrence of new symptoms or exacerbation of existing ones for a period of over 24 hours, at least 30 days after a previous relapse. Disability was assessed using the Expanded Disability Status Scale (EDSS); the six-month disability worsening or improvement were defined as an increase or a decrease by one value in EDSS. The study included 614 patients treated with Aubagio, 782 with Tecfidera, and 2,332 with Gilenya. Patients were followed over a median of 2.5 years. Patients’ characteristics at baseline differed among the three groups. Aubagio-treated patients tended to be older, with longer periods of disease, fewer relapses, and lower EDSS scores compared to the other two groups. Patients treated with Gilenya had higher EDSS and more relapses during the prior year, compared to those treated with Tecfidera. The majority of the patients had been treated with other immunotherapies prior to being given one of these three oral treatments. Results showed that Gilenya-treated patients had significantly lower annualized relapse rates than those treated with Tecfidera (0.20 versus 0.26) or Aubagio (0.18 versus 0.24), while patients taking either Tecfidera or Aubagio had a similar rate. However, during the 2.5-year period analyzed, researchers found no differences in disability accumulation or disability improvement among the three therapies. Regarding treatment persistence, Tecfidera and Aubagio were more likely to be discontinued than Gilenya. Overall, the results suggest that treatment with Gilenya may have a greater impact on relapse frequency in RRMS patients compared to Tecfidera and Aubagio, although the "effect of the three oral therapies on disability outcomes was similar during the initial 2.5 years on treatment," researchers said. “Choosing a therapy in individual patients remains a complex task that requires thorough and individualized evaluation of disease prognosis, and the corresponding risks and benefits of the increasing number of available therapies,” they concluded.