screening model for Multiple sclerosis
- 1. Screening model of Multiple Sclerosis Yogeeta M. Pharmacy Pharmacology Ist yr
- 2. Content : • Introduction • Screening model of multiple sclerosis • References
- 3. Introduction • Multiple sclerosis (MS) is an immune-mediated inflammatory disease that attacks myelinated axons in the central nervous system, destroying the myelin and the axon in variable degrees • and producing significant physical disability within 20–25 years in more than 30% of patients.
- 4. • Inflammation: body’s own immune cells attack the nervous system. • Demyelination : myelin (protective covering of the nerves)is destroyed leaving multiple areas of scar tissue or sclerosis • It is a progressive disease
- 6. Screening model for multiple sclerosis: 1. In-vitro models: • neurons • Microglia • Oligodendrocytes • Brain slice and aggregate systems • Blood –brain barrier models
- 7. 2. In-vivo model: • experimental autoimmune encephalomyeltis • viral • toxin model • transgenic ,mutant and parabiotic • mice
- 8. In-vitro models: • Microglia • Microglia activation is observed in actively demyelinating MS lesions, pre-active lesions, area of remyelination as well as the normal – appearing white matter • Primary microglia cultures are derived from embryonic or early post- natal animals
- 9. Procedure • This method is simple and allows for relatively high yield of cells • Microglia can also be separated from confluent primary mixed glial culture by agitation on a rotary shaker , producing a highly enriched cell culture(more than 95%) • Given that microglia in a brain, he initial trigger of microglia activation • Microglia phenotype supportive of regeneration is observed at the earliest stages of demyelination
- 10. In-vivo test: 1. Experimental Auto Immune Encephalomyelitis • EAE is a spectrum of neurological disorder induced in lab animals following immunisation with CNS • These models generally use purified myelin, recombinant protein or encephalitogenic peptides of myelinproteins • EAE studies used myelin basic proteins (MBP) since it is a major protein component of the myelin sheath and highly soluble, and can therefor be purified relatively easily
- 11. Procedure : • Active EAE relies on CNS- reactive T cells that are induced following immunization by an autoantigen • Emulsified in an adjuvant , while passive or adaptive transfer EAE is induced by transferring the autoreactive T cells to native recipient animals • Adjuvants used for EAE induction frequently contain killed mycobacteria that elicit T cell responses as well as antibody production due to innate immune activation via Toll- like receptor triggering
- 12. Continue…. • The first adjuvant of EAE studies was an oil in water emulsion called incomplete freund’s adjuvant. Addition of inactivated DRIED MYCOBACTERIA SUCH as M. butyricum , M. tuberculosis • This has led to the development of secondary progressive EAE, models of cortical demyelinated and experimental inflammatory neuro-degenrative and spastic disease.
- 13. 2. viral • Several mech. Have been proposed to explain how viruses can induce demyelinated , and may thus be involved in MS. • Damage may either result from a direct effect on neurons, in which case myelin damage occur as a secondary event
- 14. Procedure • Some of the virus are used to induce the disorder, virus infection could additionally induce or augment autoimmunity to myelin and neurons via several pathways 1. Semliki forest virus 2. Japanese macaques encephalomyelitis 3. Theiler’s murine encephalomyelitis virus
- 15. 1. Semliki forest virus • It does not cause demyelination in human. SFV is an enveloped Togavirus, first isolated from mosquitoes in 1942. the common strains used to induce myelin damage in mice are the mutant M9 and avirulent A7. SFV is neuroinvasive. • Once inoculated peripherally and after crossing the BBB, the virus infects neuron and oligodendrocytes. While the M9 strain is highly virulent , casing death in 10-20% of adult mice or paralysis as a result of neuronal damage
- 16. 2. JAPANESE MACAQUES ENCEPHALOMYELITIS • A spontaneous inflammatory demyelinating disease was reported in a colony of japanese macaque in Oregon from which a gamma –herpes virus was isolated 3. THEILER,S MURINE ENCEPHALOMYELITIS VIRUS • TME virus, first identified by Max Theiler, is a natural pathogen of mice, causing paralysis and encephalomyelitis • TME virus infection induces clinical neurological disease in immunocompetent mice, along with atrophy of the brain an a spinal cord.
- 17. Toxin model • These models, demyelination is induced after focal application or systemic administration of toxins. • Agents for focal demyelination used so far are • Lysolecithin, also called LPC • Ethidium bromide • Antibodies to oligodendrocyte- related proteins • Bacterial endotoxin
- 18. Reference : • Snell’s clinical neuroanatomy 7th edition • Harsh Mohan ,Text book of Pathology, published in 2005. • Baukje J. van der star etal., invitro an invivo models of multiple sclerosis CNS &Neurological Disorder – Drug Target, 2012 ,11, 570-588
- 19. Thank you