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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

June 11, 2019 News by Patricia Inacio, PhD

Aubagio Targets Highly Metabolic Auto-reactive T-Cells, Study Shows

Aubagio (teriflunomide), an approved medicine for relapsing forms of multiple sclerosis (MS), specifically targets highly metabolic and more autoreactive T-cells, analysis of the Phase 3 TERI-DYNAMIC clinical trial data shows. The findings, contrary to expectations, support a selective effect of Aubagio on different T-cell populations. The study “Teriflunomide treatment for multiple sclerosis modulates T cell mitochondrial respiration with affinity-dependent effects” was published in the Science Translational Medicine journal. In MS, immune cells, or lymphocytes known as T-cells, attack and destroy myelin, the fat-rich substance that wraps around nerve fibers (axons). Myelin loss creates lesions that affect nerves of the brain and spinal cord. Previous evidence suggested that T-cells, depending on their active or resting state, rely on specific ways of energy production or metabolism. Aubagio, marketed by Sanofi Genzyme, is a well-known inhibitor of a mitochondrial enzyme called dihydroorotate dehydrogenase (DHODH), that is crucial for the activity of T-cells. However, how Aubagio selectively targets the autoreactive T-cells is poorly understood. To shed light on this matter, an international group of researchers used data from the TERI-DYNAMIC clinical trial that tested Aubagio in patients with relapsing form of MS to better understand how the therapy inhibited the patients' self-immune responses. The Phase 3, open-label TERI-DYNAMIC trial (NCT01863888) included 70 patients from Belgium, Germany, and The Netherlands, aged 18 to 56. Participants received Aubagio as a 14 milligram (mg) once-daily, oral dose, and researchers assessed the changes in immune cells' profile up to 24 weeks. Results showed that, contrary to what was expected, Aubagio was not generally decreasing T-cell levels in treated patients. Instead, it significantly reduced a particular subset of T-cells, called "Th1 helper cells." Moreover, researchers found that the diversity of T-cell receptors — the surface proteins that can recognize a particular antigen (a protein that can elicit an immune response) — making T-cells specific to a certain target was reduced in MS patients after treatment with Aubagio. These findings suggested that some T-cells were particularly susceptible to Aubagio. Using a mouse model for MS, the experimental autoimmune encephalomyelitis (EAE) model, researchers showed that the CD4+ T-cells (helper T-cells) and CD8+ T-cells, those that reacted most strongly against self-antigens, were the most sensitive to DHODH inhibition by Aubagio. Moreover, researchers saw that Aubagio was not affecting the production of pro-inflammatory molecules — called cytokines — at the cell level, but their overall decrease probably was due to the reduction in T-cell numbers. In line with these findings, CD4+ T-cells that produced the cytokine interferon gamma were significantly reduced with Aubagio treatment, whereas CD4+ T-cells that produced interleukin 17A were unchanged. This suggests that Aubagio is able to interfere with specific sub-types of immune cells. When the team compared the metabolic profile of T-cells from healthy subjects with that from patients with relapsing-remitting MS (RRMS) in both remission and in relapse phases, they found that the metabolism of T-cells from the last group was significantly altered, and thus targetable. Altogether, the results suggested that T-cells with a high-affinity to self-antigens are more susceptible to inhibition of the DHODH enzyme by Aubagio. “Therapeutic targeting of metabolic alterations might represent an attractive concept in MS, and might represent an as yet unrecognized key mechanism of teriflunomide-mediated immune modulation in this disease,” the researchers concluded.

April 18, 2019 News by Patricia Inacio, PhD

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.