A
A
- Active lesion – Lesion that is new or growing
- Adhesion molecule – A protein that promotes the binding of one cell to another or to the extracellular matrix.
- Allele – Refers to different versions of a gene.
- Angiogenesis – The formation of new blood vessels.
- Animal model – An animal with an MS-like disease that is used to study the development and progression of MS as well as test new treatments before they are given to humans. Mice are commonly selected as the preferred animal model for most diseases, including MS.
- Antibody – A protein made by a plasma cell (mature B cell) in response to the presence of an antigen. Antibodies protect the body against foreign invaders like bacteria and viruses.
- Antigen – A substance that activates the immune system, causing the body to produce antibodies against it. Viral and bacterial molecules and even the body’s own molecules can be antigens.
- Antigen presenting cell – A specialized cell that presents antigens on its surface for passing immune cells to recognize and elicit an immune response. Dendritic cells, macrophages and B cells are the main antigen-presenting cells.
- Astrocyte – A type of cell in the central nervous system that provides metabolic, nutritional, and physical support. Astrocytes make the scars on damaged tissue during MS.
- Autoimmune disease – A disorder in which the body’s immune system attacks its own cells because it is unable to differentiate between foreign and normal cells.
B
B
- B cell – A type of white blood cell or immune cell that makes antibodies. B cells are important contributors of MS pathogenesis.
- Biomarker – A measurable indicator of a biological process that can be used as a predictor of health or disease. Biomarkers that are being evaluated for MS include those that reflect changes in the immune system, damage to myelin and nerve cells, disruption of the blood brain barrier, or myelin repair.
- Blinding – A process in clinical trials that involves concealing information about a test or treatment from the experimenter, subject, or both (double-blind), in order to eliminate potential bias – whether intentional or accidental – from interpretation of the data.
- Blood brain barrier (BBB) – A barrier formed by a continuous layer of tightly connected endothelial cells that controls the movement of molecules and cells between the blood and brain tissue.
- Body mass index (BMI) – A measure of body fat calculated from an individual’s height and weight.
- Brain atrophy – Loss of brain tissue (brain shrinkage).
- Brain ventricles – Hollow structures deep within the brain that are filled with cerebrospinal fluid.
- Bruton tyrosine kinase inhibitor (BTKi) – A new class of disease-modifying therapies that target and inhibit the BTK protein found in immune cells that are associated with MS disease processes, such as B cells and myeloid cells.
C
C
- Central nervous system (CNS) – The brain, spinal cord, and optic nerve.
- Cerebrospinal fluid (CSF) – The fluid that bathes the surfaces of the brain and spinal cord in the central nervous system. The CSF protects the brain and spinal cord from injury and supplies nutrients.
- Chemokine – A protein that attracts immune cells to sites of inflammation to help the body fight infections, inflammatory reactions, and other conditions.
- Choroid plexus – A specialized tissue in the brain ventricles that produces the cerebrospinal fluid (CSF) that surrounds the central nervous system.
- Clinically isolated syndrome (CIS) – A single, first neurological episode that shows characteristics of inflammation/demyelination in the central nervous system and is suggestive of MS. Many people with CIS eventually develop MS.
- Clinical trial – A type of research study that tests the safety and efficacy of a specific intervention (i.e., drug, diet, exercise, medical procedure) in people.
- Cognition – The mental action of acquiring, processing, understanding, and retaining knowledge.
- Comorbidities – The presence of more than one disease or condition in a person at the same time. Hypertension, depression, chronic lung, and anxiety are common comorbidities in MS.
- Compartmentalized inflammation – Inflammation that occurs as a result of immune cells being trapped within the central nervous system and causing tissue injury. This type of inflammation is difficult to target with current disease-modifying therapies and thought to be a key contributor of the processes that lead to disease progression in MS.
- Control – The standard against which experimental interventions are evaluated.
- Cytokine – A small messenger molecule that influences the actions of immune cells. There are many different cytokines, including chemokines and interferons.
D
D
- Demyelination – A process during which myelin becomes damaged and is stripped from nerve fibres.
- Dendritic cells – A type of white blood cell that specializes in presenting antigens on its surface to other immune cells to activate an immune response.
- Deoxyribonucleic acid (DNA) – A unique code of genetic instructions that shapes the development of every individual.
- Differentiation – A series of steps that cells go through to reach their mature state.
- Disease-modifying therapy (DMT) – A class of treatment that targets the underlying processes of the disease in order to delay, stop, or reverse the disease.
E
E
- Endothelial cell – Lines the heart and blood vessels of the circulatory and immune systems; an important component of the blood brain barrier.
- Ependymal cell – Lines the fluid-filled spaces in the brain and acts as a key barrier between the cerebrospinal fluid (CSF) and the underlying brain tissue.
- Epigenetics – The study of how non-genetic or environmental factors influence the way genes in our body are turned on or off in a particular cell.
- Epstein-Barr virus (EBV) – A human herpesvirus that causes infectious mononucleosis (commonly referred to as ‘mono’) and is a known risk factor of MS.
- Expanded Disability Status Score (EDSS) – A test for measuring the disability level of a person with MS.
- Experimental autoimmune encephalomyelitis (EAE) – A common model of MS-like disease used in the laboratory to study MS.
- Extracellular matrix (ECM) – A large, complex network of proteins and other molecules that provides structural support to surrounding cells and tissues.
F
F
- Fibroblasts – A type of cell that provides structural support to connective tissues. In MS, fibroblasts can accumulate in the central nervous system and form scar-like structures in the brain and spinal cord.
- Functional magnetic resonance imaging (fMRI) – An imaging technique that looks at blood flow in the brain in real time to detect areas of activity. Where there is increased activity, blood flow to that region increases.
G
G
- Gadolinium enhanced lesion (GEL) – Gadolinium is a chemical compound used to visualize tissue on MRI scans which are affected by inflammation. Gadolinium is a large molecule that cannot normally enter the brain, but when there is active inflammation the barrier which separates the circulating blood and brain is ‘leaky’ and gadolinium can get through. Thus, gadolinium makes it possible to identify new or growing lesions.
- Gene – Pieces of DNA that include the genetic code for making proteins; located on chromosomes.
- Gene regulation – A process by which cells control which genes to ‘turn on’ (express) and ‘turn off’ (not express).
- Glial cell – Support cells in the nervous system; oligodendrocytes, astrocytes and microglial cells in the central nervous system and Schwann cells in the peripheral nervous system.
- Glial fibrillary acidic protein (GFAP) – A biomarker associated with disease progression in MS. GFAP can be measured in both the blood and cerebrospinal fluid.
H
H
- Health Related Quality of Life (HRQL) – Quality of life of people with MS based on patient-perceived functional status and well-being.
- Hematopoietic Stem Cells (HSC) – Found in the bone marrow, blood, and umbilical cord. These stem cells are capable of maturing into all cells that comprise the blood and immune system. Autologous hematopoietic stem cell transplantation (aHSCT) involves collecting stem cells from an individual’s own (autologous) bone marrow. The individual is then subjected to chemotherapy to deplete the immune system and stem cells are reintroduced into the body where they mature into new, healthy immune cells.
- Human immunodeficiency virus (HIV) – A virus that attacks the body’s own immune cells. Individuals with HIV and those with HIV who are taking antiretroviral therapy were associated with lower risk of MS.
I
I
- Immunoglobulin – The membrane-bound version of an antibody secreted by B cells in response to an antigen.
- Immunoregulation – The control of specific responses in the immune system.
- Inflammation – A normally protective response of the immune system to physical/chemical injury, infection, or exposure to harmful substances that lead to tissue damage. Inflammation may be acute (rapid, short-term) or chronic (slow, long-term). Acute inflammation may be accompanied with loss of function, swelling, redness, heat, and pain. Chronic inflammation may be associated with underlying disease, such as MS.
- Interferons (IFN) – A type of cytokine that helps cells to fight viruses. Manufactured versions of interferons may be useful as MS treatments (i.e., beta interferon).
J
J
K
K
L
L
- Lesion – Damage to body tissues as a result of injury or disease. In MS, brain and spinal lesions indicate damage to myelin in those tissues.
- Lipid – Fatty molecules (i.e., triglycerides, phospholipids, cholesterol) that perform a variety of functions in the body including storing energy, absorbing vitamins, maintaining healthy cells, etc.
- Lymphocytes – White blood cells (B cells, T cells and NK cells) of the immune system that originate from the bone marrow and help fight specific infections.
M
M
- Macrophage – An immune cell that is among the first line of defense against invaders; also acts as antigen presenting cells. Macrophages are called different names depending where they are found in the body (e.g. microglial cells in the brain).
- Magnetic resonance imaging (MRI) – An imaging tool that allows for the anatomical detection of lesions in the brain and spinal cord and may be used to track disease progress.
- Magnetic resonance spectroscopy (MRS) – A technological tool similar to MRI that provides chemical rather than anatomical information of body tissues. MRS provides information of the different chemicals and their quantities in body tissues.
- Mass spectrometry – An analytical technique used to measure the mass of molecules or group of molecules. Mass spectrometry provides information on the structure of molecules.
- Mast cell – Originates in the bone marrow; involved in allergic responses.
- Memory B cells – B cells living in the body for long periods of time. Memory B cells remember previously presented antigens and upon exposure can be triggered to make antibodies to the same antigen in the future.
- Mesenchymal stem cell (MSC) – Found in several places in the body including the bone marrow, skin, and fat. Autologous mesenchymal stem cell transplantation (aMSCT) involves collecting stem cells from an individual’s own (autologous) bone marrow. The stem cells are then allowed to multiply in a laboratory setting prior to being reintroduced into the body where they mature into new, healthy immune cells. Unlike aHSCT, (aMSCT) does not use chemotherapy to deplete the immune system.
- Microbiome – The community of microbes/bacteria that are present in the gut.
- Microglia – Macrophage-like cells that reside in the brain. Microglia ‘eat’ cellular debris from dead cells and stimulate immune responses.
- MicroRNA (miRNA) – A group of small molecules that can control how genes are turned on or off in a particular cell. miRNA can be found in the blood and are being explored as biological indicators or biomarkers for MS.
- Monocyte – A white blood cell that resides only in the blood. Once it migrates into the tissues, a monocyte changes into a macrophage.
- MSQLI – The Multiple Sclerosis Quality of Life Inventory is a questionnaire designed to evaluate the burden of disease experienced by people with MS.
- Myelin – A protective layer or sheath around nerve fibres that speeds transmission of nerve signals in the body. In MS, damage to myelin causes inflammation and disrupts the nerve signals from the brain to the rest of the body.
- Myelin basic protein (MBP) – One of the principal proteins found in myelin.
- Myelin oligodendrocyte glycoprotein antibody disease (MOGAD) – An autoimmune disease that presents with similar symptoms to MS and can be misdiagnosed as MS. In MOGAD, antibodies target the molecule MOG found in myelin, resulting in demyelination of nerve fibres
N
N
- Nerve fibre (axon) –The slender, long branch extending from a nerve cell that carries nerve impulses to adjacent nerve cells throughout the body. Most nerve fibres are surrounded by 1-200 layers of myelin.
- Neurodegeneration – The slow, progressive loss of nerve fibres.
- Neurofilament light chain (NfL) – A biomarker of nerve fibre damage in the central nervous system. NfL can be measured in both the blood and cerebrospinal fluid.
- Neuroglia (glial cells) – Cells that support neurons and their function (e.g. astrocytes and oligodendrocytes).
- Neuroinflammation – Inflammation in the central nervous system (brain and spinal cord).
- Neuromyelitis optica spectrum disorder (NMOSD) – An autoimmune disease that presents with similar symptoms to MS and can be misdiagnosed as MS. In NMOSD, the immune system attacks the optic nerve, spinal cord, and sometimes the brain resulting in inflammation and demyelination of nerve fibres in the central nervous system.
- Neuron (nerve cell) – A cell within the nervous system that consists of a cell body and the associated membrane extensions, called dendrites (short, branched) or axons/nerve fibres (long, unbranched). Neurons send and receive signals throughout the body.
- Neuropathology – The study of diseases affecting the nervous system; involves analyzing tissues (i.e., brain, spinal cord, nerves) collected from autopsy or biopsy.
- Neuroprotection – The preservation of the structural and functional integrity of nerve cells
- Neutrophil – A type of white blood cell that migrates quickly to a site of inflammation to help fight infections
- NK cells – Natural Killer (NK) cells are a group of lymphocytes (not T or B cells) that can destroy infected or diseased cells.
- No evidence of disease activity (NEDA) – A criterion for assessing the effectiveness of a treatment for MS on the basis of complete remission across four key disease measures: relapses, MRI lesions, brain volume loss, and disability progression.
O
O
- Oligodendrocyte – The cell in the central nervous system that makes and maintains the myelin that surrounds nerve fibres.
- Oligodendrocyte precursor cells (OPCs) – Cells that mature into oligodendrocytes.
- Open label – A type of study in which both investigators and participants know of the intervention the participant is receiving (i.e., experimental drug or placebo).
P
P
- Paramagnetic rim lesions (PRLs) – A type of chronic active lesions that are detectable by MRI and correspond to highly active macrophages/microglia that are present at edge of the lesion.
- Pathogenesis – The underlying processes through which a disease develops and progresses.
- Pediatric-onset MS (POMS) – MS diagnosed prior to age 18. Children and youth with POMS present with distinct clinical features from adult-onset MS.
- Peptide – A chain of amino acid building blocks strung together. The chain can be two (di-) amino acids, three (tri-) amino acids, or more (poly-) amino acids in length.
- Peripheral nervous system (PNS) – Nervous system that lies outside of the brain and spinal cord and sends nerve signals throughout the body. The PNS can be affected by MS.
- Placebo – A substance used in clinical trials to resemble an actual treatment or medicine (i.e. a dummy or mock treatment). Use of a placebo can help determine how much benefit is being derived from the actual treatment, and how much is due to the psychological state of the subject (i.e. placebo effect).
- Plaque – An area of myelin loss characteristic of multiple sclerosis.
- Primary progressive MS (PPMS) – A clinical subtype of MS characterized by a slow accumulation of disability in the absence of defined relapses.
- Prodrome – A set of early non-specific signs and symptoms that can emerge several years prior to the onset of classical symptoms and clinical diagnosis of a disease, such as MS.
- Progression – The gradual accumulation of disability in the presence or absence of relapses or new MRI activity.
- Progression independent of relapse activity (PIRA) – An important mechanism of irreversible disability accumulation in MS that can occur from the earliest stages of MS, such as CIS.
- Proteolipid Protein (PLP) – One of the major proteins found in the myelin sheath.
Q
Q
R
R
- Radiologically isolated syndrome (RIS) – The earliest detectable stage of MS in which individuals present with lesions in the central nervous system suggestive of MS as seen by MRI, but do not have any clinical symptoms of MS. Many people with RIS eventually develop MS.
- Randomization – The process whereby participants in a study are randomly assigned to different treatment groups in order to eliminate or reduce bias in any particular group.
- Regeneration – A process of restoring damaged or lost cells/tissues in the body.
- Relapsing-remitting MS (RRMS) – A clinical subtype of MS characterized by unpredictable but clearly defined relapses during which new symptoms appear or existing ones get worse.
- Remyelination – A process during which new myelin is re-added to demyelinated nerve fibres by oligodendrocytes in the central nervous system or Schwann cells in the peripheral nervous system.
- Ribonucleic acid (RNA) – A copy or transcript of DNA that is involved in making the proteins in our body.
S
S
T
T
- Schwann cell – The cell in the peripheral nervous system that makes and maintains myelin.
- Secondary progressive MS (SPMS) – A clinical subtype of MS characterized by progressive worsening and fewer relapses. Most people with RRMS will eventually transition to SPMS.
- Sham – Analogous to a placebo drug. A clinical trial participant may receive a 'sham' or 'fake' procedure (i.e., surgery, injection, intervention) that removes the therapeutic component of the procedure being evaluated, as part of the control group.
- Single digit modalities test (SDMT) – A test for cognitive function that measures processing speed.
- Slowly expanding lesions (SELs) – A type of chronic active lesions that are detectable by MRI and corresponds to ongoing demyelination and loss of axons.
- Stem cell – Unspecialized cell that can mature into a cell that performs a highly specific function. A stem cell can also divide to produce more stem cells.