Multiple Sclerosis From neuroscience to treatment

1. Multiple SclerosisFrom neuroscience to treatment Dr Rosie Jones The Brain Centre, Southmead Hospital

2. Characteristics of MS “Autoimmune mediated inflammation (causing damage) triggered by unknown factors in susceptible individuals and resulting in”: • Patchy damage to myelin / loss of Oligodendrocytes (?) • Failure of nerve conduction • Axonal damage • Axonal/nerve cell degeneration • Reduced brain Volume • Development of scarring In the CNS MS Research Unit

3. This session • Understanding MS • Demographics • Pathology • Immuno-pathology • Myelin damage • Axonal damage • Routes to designing treatment • Possible CNS repair mechanisms • Some examples of MS Symptoms

4. MS Demographics • Prevalence between 10/100,000 and 170/100,000 (around 100,000 in the UK , 3 million world wide) • Most common in temperate latitudes • 2:1 women:men • Diagnosed in early adulthood (teens to 30s, range “x” to 70 years) Childhood MS now acknowledged. • Familial (genetic) susceptibility + unidentified factors • Significantly more common in Caucasian populations • Multiple symptoms-sensory and motor • Progressive with or without relapses Relapse Remitting, Primary Progressive Secondary Progressive (RR PP SP)

5. POPULATION STUDIES Some examples of prevalence figures world-wide: UK 99-178/100,000 (Orkney 287/100,00?) France 50/100,000 Italy 35-50/100,000 USA 70-165/100,000 (New Mexico 22/100/000) Australia 11-40/100,000 New Zealand 24-77/100,000 Middle East 20 -50/100,000 (?)

6. Environment: MIGRATION STUDIES Studies of migration from high prevalence area to low prevalence area: • South Africa and Israel are both low prevalence areas. • Europeans migrating to these areas retain high prevalence risk unless they migrate before the age of 15 years.

7. Environment: EXPOSURE • Levels of sunlight/Vit. D • Temperate latitudes, lack of exposure to sun • Exposure to chemicals • Solvents, fuel pollution, smoking • Exposure to (viral) infections • Measles, hepatitis, herpes etc. Vaccinations • Exposure to stress/trauma • MS may occur/worsen after giving birth, physical injury traumatic life events • Dietary differences • High saturated fat levels-lack of polyunsaturated fats in diet.

8. MULTIPLE SCLEROSIS Spring 2012 MS Research Unit

9. EDSS expanded disability status scale Kurtzke JF (1983) Neurology 33 (11): 1444–52.

10. SPMS Clinical Impairment MRI-Defined Plaque Burden Occurrence, Extent of Severity Late RRMS Early RRMS Enhancements Time Progression of DisabilityMS Courses as Redefined by MRI Adapted with permission from Dr. J.S. Wolinsky.

11. Natural History of MS • Relapse remitting phase- intermittent clinical events 1 to 4/year - 5 to 20 years • Secondary progressive phase-few or no relapses, steady progression in disability levelling off by about 20 years after diagnosis • Primary progressive – steady increase in disability with or without relapses. • Severe - very rare. Fast progression to wheelchair/bed-bound/death in 3 to 10 years

12. Pathology Development of an MS Plaque Inflammation, Demyelination Axonal damage

13. Characteristics of MS pathology “Autoimmune mediated inflammation resulting in”: • Damage to/loss of myelin/or loss of Oligodendrocytes? • Axonal damage • Axonal degeneration • Loss of brain bulk

14. Myelin and Nerve Conduction

15. Demyelination: Myelin and Oligodendrocytes in the CNS • Myelination in the CNS is by Oligodendrocytes-(peripheral nervous system myelin is produced by Schwann cells-not present in CNS and not affected by MS) • Each Oligodendrocyte produces myelin extensions that wrap around several nerve axons • What happens to Oligodendrocytes in MS?

16. OLIGODENDROCYTES Oligodendrocyte in culture (Immunofluorescence for galactocerebroside)

17. Brain Imaging

18. PATHOLOGY Not all aspects of MS pathology are understood • Blood brain barrier disruption- immune cells move into CNS. • Complex inflammatory responses • Localised CNS damage-demyelination, axonal damage

19. Pathology Local infiltration of inflammatory cells across blood vessel walls requires: • Adhesion to blood vessel epithelium • Transit across blood vessel wall • Migration into local brain tissue

21. Evidence that MS is an Autoimmune disease. Immune activity overview • Activated T lymphocytes appear in the blood and CSF. Reactive to myelin proteins e.g. *MOG or MBP • Activated T cells and macrophages seen in MS plaques • Increased CD4+ (helper) to CD8+ (suppresser) T cell ratio. • Local IgG production seen in CSF-action of B cells? Possible antibody candidates:*MOG (oligodendrocyte glycoprotein), MBP (myelin basic protein), viral infection?

22. William Lindsey and Jerry Wolinsky

24. Immune markers Increased circulating levels of immune markers of immune activity during MS exacerbations observed including: • T cell activation markers • Markers of macrophage activation • Markers of cellular adhesion • Markers of extracellular matrix breakdown • Markers of inflammatory cellular amplification

25. T cell activation markers Markers of T Helper cell (Th-1) activation • Activated T helper cells release IL-2 (soluble IL-2 receptors detected) • IL-4 is associated with T cell activation • Interferon-gamma (INF) is associated with T cell activation • Macrophage activation follows. aTNF IL=interleukin, TNF = tumour necrosis factor, INF=interferon

26. Macrophage activation Macrophage demyelination in vitro is mediated by tumour necrosis factor-(TNF ) and Interferon (INF) • TNF is increased in MS during relapse • INF and TNF act synergistically to heighten immune responses • TNF damages Oligodendrocytes in vitro Beta interferon, INF, counteracts the influence of TNFand INF

27. Aims of Disease Modifying Drugs DMDs are designed to break a key link or links in the presumed pathway to tissue destruction in active disease Links include • Immune cell activation (PB, CNS other?) • Immune cell adhesion and migration (BBB) • Immune cell clonal expansion (PB or CNS) • Immune cell/cytokine cycle amplification

28. William Lindsey and Jerry Wolinsky

29. Autoreactive T Cells Danger Signal or Trigger T T T T T Activation, Differentiation,Clonal Expansion Adhesion/Attraction T Periphery Transmigration T BBB B APC T IFN- Antibodies Local Reactivation M CNS APC T TNF- Release of Cytokines; Recruitment of M NO TNF- Demyelination and Axon Loss Adapted with kind permission from Prof. R. Hohlfeld.

30. The Dual Nature of Inflammation in MS Pro-inflammatory and Neurotoxic Factors Anti-inflammatory and Neuroprotective Factors • Th1 cytokines • TNF- • IL-1 • Nitric oxide • Reactive oxygen species • Glutamate • Antibodies and complement • Cell-mediated neurotoxicity • Th2 cytokines • TGF- • IL-1 • Neurotrophic factors – BDNF – NGF – NT-3 – CNTF – GDNF TISSUE DAMAGE TISSUE PROTECTION

31. Aims of Disease Modifying Drugs DMDs are designed to break a key link or links in the presumed pathway to tissue destruction in active disease Links include • Immune cell activation (PB, CNS other?) • Immune cell adhesion and migration (BBB) • Immune cell clonal expansion (PB or CNS) • Immune cell/cytokine cycle amplification

32. Clonal cell expansion-promotion of cellular reactivity? Mechanisms for clonal expansion of auto-reactive immune cells and cellular amplification/restriction unclear • Following BBB breach other cells follow: In MS plaques T cells and macrophages • Macrophage activation: e.g. TNFa , macrophage inflammatory proteins • Pro-inflammatory cytokines detected in lesions • TNFa, INf-g, IL-2,IL-6,Il12.

33. Treatments based on modifying immune function • Some tested disease modifying agents • Beta interferon- (betaseron betaferon, Avonex) • Glatiramir acetate (Copaxone, copolymer 1) • Natalizumab (Antegren)-affects adhesion molecules • Campath H (Alemtuzumab) acts against CD52 lymphocytes • Cell proliferation modulation? • Stem cells??

34. BBB Action of Adhesion Molecules Peripheral circulation T cells express adhesion molecules e.g. LFA-1 VLA-4 Basementmembrane CNS Blood vessel Blood vessels express Adhesion molecules e.g. E-Selectin Matrix degrading enzymes e.g. matrix metallo-proteinases LFA- Leukocyte function associated antigen-1 VLA Very late antigen-4

35. Current drug trials

36. Clinical outcome of some DMDs • Reduction in number of relapses in early RR MS • Reduction in new MRI (enhancing) CNS lesions in early RR MS • Reduction in progression of disease by 9 to 12 months • Changes broadly reverse when treatments stops.

37. Current treatments • Inflammatory phase-steroids • Non–acute phases • General immunosuppressant agents • Possible non-drug immuno-suppressants • e.g. diet, lifestyle changes • Statins?

38. Damage to axons and nerve cells

39. Myelin damage and axonal loss in MS

40. Fate of axons and nerve cells It is now clear that axonal loss and damage are major features of MS • Presence of NAA (N-acetyle aspartate) in MR spectroscopy • Loss of brain bulk • Increasing disability • Alterations in physiological measures

41. Neuronal/axonal damage Axonal damage thought to be secondary to myelin damage. Loss of trophic support or direct injury to axon BUT In some models of MS axonal damage appears early with or without evidence of demyelination. AND Reduction in CNS bulk continues in absence of demyelination episodes (e.g. Progressive MS)

42. Possible causes of axonal loss Damage by • Proteases • Inflammatory cytokines • Nitric oxide • Glutamate/Glutamine Evidence of up-regulation of all these possible mechanisms seen in active MS.

43. Possible mechanisms of repair

44. Remyelination Remyelination requires: • Viable myelin making cells (oligodendrocytes) • Intact nerve processes • Suitable environment for cellular survival and activation

45. Oligodendrocyte - development ?

46. Features of Oligodendrocytes • Progenitor cells +ve for 04 mabs. Present throughout CNS. Undifferentiated. • Precursor cells +ve for Galacto-cerebroside (GalC). Earliest OG specific marker to be expressed. Large pale nucleus. • May produce myelin processes. • Mature cell +ve for myelin oligodendrocyte glycoprotein MOG. Small dense nucleus.

47. Possibilities for promoting remyelination • Stimulate cell activity/differentiation • Block progenitor cell inhibitory factors • Block agents that kill myelin-making cells • Transplant new OG cells-stem cells

48. Oligodendrocytes and myelin Extensive remyelination does not occur despite presence of intact axons and GalC+ve cells in the same lesion area. • GalC +ve cells do not appear to mature into MOG +ve cells to form new myelin • Cells appear quiescent. Die before they can mature? • GalC and MOG +ve cells appear to be destroyed in long term plaques • MOG+ve (mature) cells are destroyed selectively • Possibilities for treatment- stimulate cell activity/differentiation block inhibitory/cytotoxic factors Induce/transplant new OG cells?

49. Nerve cell repair Loss of axonal capability to repair may be : • Intrinsic-no mechanism in mature CNS • Due to Nogo-A mediated damage-Block or ablate. • Lack of access to or response to nerve growth factors • Hostile cytotoxic soup-too many factors to control Neurotrophic support may be developed e.g. CNTF ciliary neurotrophic factor.

50. Stem cells Can stem cells be used to effect repair in MS? • Types of possible stem cells • Resident/introduced oligodendrocyte precursor cells. • Used in early repair? Depleted? • Embryonic stem cells • ethical and cross reactivity issues. Tumours • Other stem cells-e.g. haematopoietic • Autologous and relatively easy to obtain