T-cells

January 24, 2020 News by Patricia Inacio, PhD

Mayzent Helps Regulate the Immune System in SPMS, Study Shows

Mayzent (siponimod), an approved oral therapy for activeĀ secondary progressive multiple sclerosisĀ (SPMS), promotes a more regulatory immune system, which may explain its added benefits for SPMS, new clinical data show. The study ā€œSiponimod enriches regulatory T and B lymphocytes in secondary progressive multiple sclerosisā€ was published in the…

June 11, 2019 News by Patricia Inacio, PhD

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

AubagioĀ (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 ā€œTeriflunomide treatment for multiple sclerosis modulates T cell mitochondrial respiration with affinity-dependent effectsā€ was published in the Science Translational MedicineĀ 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 byĀ Sanofi Genzyme, is a well-known inhibitor of a mitochondrial enzyme called dihydroorotate dehydrogenase (DHODH), that is crucial for the activity of T-cells.Ā However, how Aubagio selectively targets the autoreactive T-cells is poorly understood. To shed light on this matter, an internationalĀ 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 ā€” the surface proteins that can recognize a particular antigen (a protein that can elicit an immune response) ā€” 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+Ā 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 ā€” called cytokines ā€” at the cell level, but their overall decrease probably was due to the reduction in T-cell numbers. In line with these findings, CD4+Ā T-cells that produced the cytokine interferon gamma were significantly reduced with Aubagio treatment, whereas CD4+Ā 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 fromĀ 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. ā€œTherapeutic 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,ā€ the researchers concluded.

March 11, 2019 News by Jose Marques Lopes, PhD

Tecfidera May Work to Lower Relapses by Inducing Epigenetic Changes in T-cells, Study Suggests

TreatingĀ multiple sclerosis with Tecfidera induces specific genetic alterations that may reduce the levels of immune T-cells targeting the central nervous system, researchers report. Environmental stimuli may induce epigenetic changes in cells ā€” meaning not alterations in the genes themselves, but changes in gene expression (the process by which information in a gene is synthesized to create a working product, like a protein). Epigenetic changes may induce MS development, as these alterations can cause T-cells to attack the central nervous system. One type of epigenetic change is DNA demethylation, the removal of methyl chemical groups, in which molecules involved in metabolism (such as fumarate) interact with enzymes known as DNA demethylases. This process in key for T-cell activation, function and memory, suggesting that it could be an immunomodulatory target. Fumaric acid esters were shown to be effective in MS clinical trials, leading to the approval ofĀ Tecfidera (by Biogen) for people with relapsing-remitting forms of the disease.Ā However, their complete mechanism of action remains unclear. Aiming to address this gap, scientists at theĀ Advanced Science Research Center (ASRC) at The Graduate Center of The City University of New YorkĀ and theĀ Icahn School of Medicine at Mount Sinai, recruited 98 MS patients, either previously untreated (47 people, mean age of 38.4), treated with Tecfidera (35 people, mean age of 42.3), or treated with glatiramer acetate (16 patients, mean age of 43.4) ā€” marketed asĀ CopaxoneĀ byĀ Teva Pharmaceuticals, with generic forms byĀ SandozĀ (asĀ Glatopa) and byĀ Mylan. All patients had stable disease for at least three months, but disease duration was shortest in untreated patients ā€” 40.4 months vs. 130 months in those given Tecfidera, and 100 months in patients using glatiramer acetate. Blood samples were collected from each participant to assess epigenetic changes in T-cells expressing the cell surface marker CD4. MS patients typicallyĀ have an activated formĀ of these cells in their blood and cerebrospinal fluid, the liquid surrounding the brain and spinal cord. Results revealed that, compared to the other two groups,Ā treatmentĀ with Tecfidera was associated with a lower percentage of T-cells containing the CD3, CD4, and CD8 markers, as well as lower levels of subsets of T-cells expressing the CCR4 and CCR6 receptors, which are critical to T-cell migration to the gut, brain, and skin. Treatment with glatiramer acetate resulted in significantly milder alterations in T-cell percentages compared to no treatment. Researchers then found that FAEs induce excessive methylation ā€” the addition of methyl groups ā€” in T-cells containing CD4, compared to glatiramer acetate. Specifically, this overmethylation was observed in a micro-RNA ā€” tiny RNA molecules than control gene expression ā€” known as miR-21, key for the differentiation of a subset of T-cells called T helper-17 (Th17) cells and for CCR6 expression in MS mouse models. These Th17 cells are critical in tissue inflammation and destruction, and have beenĀ implicatedĀ in MS. The epigenetic effects of FAEs were subsequently validated by comparing pre- to post-treatment with Tecfidera in seven patients. In turn, in vitroĀ (lab dish) experiments showed that FAEs act specifically on the activation of naĆÆve T-cells ā€” those able to respond to new pathogens to the immune system ā€” containing the CD4 or the CD8 markers. Of note, patients with MS have shown increased miR-21 levels, particularly during acute relapses. As such, the team hypothesized that its hypermethylation by FAEs could contribute to remission and the prevention of relapses in this patient population. These results "suggest that the metabolic-epigenetic interplay in T-cells could be harnessed for therapeutic purposes," the researchers wrote, and that the immunomodulatory effect of FAEs in MS is due at least in part to the epigenetic regulation of T-cells. The researchers believe that their findings have a broader implication, beyond MS. "Our findings about therapeutically active metabolites have implications for the treatment of not only multiple sclerosis but also other autoimmune diseases, such as psoriasis and inflammatory bowel disease, which involve the same type of T-cells," Achilles Ntranos, the studyā€™s lead author, said in a press release. "Understanding the epigenetic effect of metabolites on the immune system will help us develop several novel strategies for the treatment of autoimmune diseases, which could help patients and physicians achieve better clinical outcomes," Ntranos added. Patrizia Casaccia, the studyā€™s senior author, concluded:Ā "It may one day be possible to target and suppress production of the specific brain-homing T-cells that play a role in the development of MS."

 

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