week 8 part 1 Flashcards
What is multiple sclerosis ?
Demyelinating disease of the central nervous system which include the brain and the spinal cord
autoimmune disease
polygenic - over 200 different genes that have been identified that are associated with susceptibility
What is myelin?
protective sheath that surrounds the axon of neuron allowing them to quickly send electrical impulses
What is myelin produced by?
oligodendrocytes - group of cells that supports the neuron
When does demyelination happen?
when the immune system attacks and destroys the myelin which makes communication between neurons break diown
What does demyelination cause?
sensory, motor and cognitive problems
What is the most important gene?
HLADRB1*1501
What is HLADRB1*1501?
a Class II member of the major histocompatibility complex (MHC)
Who is more likely to be affected by MS?
- females
2. It is around 1-3
What does MS have?
Graphical distribution
It is more common further away from the equator
What does MS relate to?
Vitamin D responsiveness
What are some of the most common risk factors for multiple sclerosis include?
- Genetics
- Certain Infections
- Smoking
- Obesity
- Environmental factors
- Certain autoimmune diseases
- Age, sex, race
What do individuals with MS have?
- Epstein Barr Virus infection
When a disease manifests itself what does it manifest as?
Relapsing remitting diseases
What is secondary progressive MS?
Many people who are initially diagnosed with relapsing remitting MS find that, over time, their MS changes so that there are fewer or no relapses but disability is increasing.
Why is there different residuals signs and symptoms?
As a consequence of losing myelin and axons and neurons and synapses
What does the symptoms you will get depend on?
Where in the nervous system the attacks occur
In MS brain, where are the lesions observed?
Paraventricular lesions
Lesions around the ventricles
What are lesions associated with?
- De-myelination
2. Astrocytic scarring
Where are the active lesions located?
Perivascular areas
Occur around the blood vessels
Contain lymphocytes and monocytes
What are the features of active lesions?
- Foamy macrophages
- Myelin losses
- Hypertrophi astrocytes
- Perivascular infiltrates
What are chronic active lesions?
- Large, grey lesions - inactive centre but show an outer hyperceullar rim - contain foamy macrophages
- Myelin remnants are seen in the macrophages
- Hypertrophic astrocytes are often present in the rim
- Oligodendrocytes numbers are depleted, increased or normal
- Perivascular lymphoid infiltrates are present
What are macrophages full off?
Lipid
What are shadow plaque?
If the inflammatory process is arrested at an early phase, plaques are partially remyelinated
What are consequences of chronic inactive lesions?
- Complete myelin loss
- Loss of oligodendrocytes
- Few or no inflammatory cells
- Gliotic
- Surrounded by ‘normal’ white matter
- The lesions are clearly hypocellular
What are repairing lesions?
- Myelin replacement
- Thinner myelin
- Smaller internode length
What is pathology of MS?
- Characterised by multifocal lesions - MS plaque
- in the acute phase - activated mononuclear cells - including lymphocytes, microglia and macrophages destroy myelin
- Myelin debris are picked up by macrophages and degraded
- At early stage - macrophages contain myelin fragments
- later stage - they contain proteins and lipids from chemical degradation of myelin
- with time gliosis develops
- Plaques reach a burned-out stage - demyelinated axons traversing glial scar tissue
- Remaining oligodendroyctes attempt to make new myelin
- If the inflammatory process is arrested at an early phase, plaques are partially remyelinated (shadow plaque)
In more advanced lesions, why is remyelination ineffective?
Gliosis creates a barrier between myelin producing cells and their axonal targets
what is Experimental autoimmune encephalomyelitis?
animal model of brain inflammation
It is an inflammatory demyelinating disease of the central nervous system (CNS)
What is MS?
Immune mediated
How does EAE work?
immunization with myelin proteins or peptides induces the migration of activated autoreactive T cells across the blood-brain barrier and into the CNS;
What are killing oligodendrocytes which is causing the demyelination?
perivascular lesion around blood vessels, these are secreting toxin factors
What was the first drug to affect progressive MS?
Ocrelizumab
When do we get an accumulated risk of opportunity infections?
When the drugs are not specific and is targeting large parts of immune response
When do you have a risk of malignancy?
constantly depressing your immune system
Cannot take live vaccines
What is pulsed immunotherapies?
Non-continuous administration
Get treatment over a week or month
What are non-selective Immunotherapy?
Gets rid of adaptive and innate immune system
What are semi-selective Immunotherapy?
Doesn’t target immune system so much