inflammation, demyelination, gliosis, and neuronal loss are all components of multiple sclerosis (MS), a chronic autoimmune disease that affects the central nervous system (CNS). Myelinated axons in the CNS are the target of MS attacks, which can cause varying degrees of damage to both myelin and axons.MS affects 2.3 million people worldwide. MS is often diagnosed between the ages of 20 and 50 years, with females experiencing it more often than males. Four MS phenotypes exist: clinically isolated syndrome, relapsing-remitting (RRMS), secondary progressive and primary progressive.Many factors have been found to be associated, including environmental toxins..Pathological features that require explanation are the presence of demyelination in both white and grey matter , the targeting of oligodendrocytes, damage to the blood-brain barrier, inflammation in MS plaques and in the meninges, astrocyte activation, the central role of blood vessels and their perivascular spaces, and the presence of oxidative stress, mitochondrial damage, and oligodendrocyte apoptosis.Oxidative Stress and MS
.the oxidative damage of oligodendrocytes and neurons is associated with inflammation, and play a major role in neurodegeneration.Many autopsy studies describe an increase in various markers of lipid peroxidation, markers of DNA damage.CSF levels of trace metals involved in oxidative stress processes were the subject of a single study, which described increased lead, decreased magnesium, and similar calcium, manganese, and zinc levels in patients with primary progressive MS (PPMS) compared to those with secondary progressive MS (SPMS) and controls. lead(Pb) is a well-known toxic metal that threatens public health and is widely involved in the pathogenesis of MS. Accumulation of Pb in cells has been associated with the development of autoantibodies against different cellular structures such as neurofilaments, neuronal cytoskeletal proteins, and myelin basic protein.Lead exposure primarily occurs through ingesting tainted food or water, or inhaling Pb-contaminated air.The primary sources of occupational Pb exposure include the production of paint, recycling of batteries, wood preservation, welding, textile, printing, and handicraft industry . Some other sources, like canned food, cosmetics, lead pipes for water supply, and use of herbal products, also lead to Pb exposure in humans.The specific pathophysiological mechanisms mediating the relationship between environmental risk factors and MS susceptibility remain unknown, and DNA methylation may provide information on these mechanisms.This epigenetic pathway contributes to various MS pathophysiological processes, such as demyelination and remyelination, inflammatory response, and the collapse of the blood brain barrier (BBB).Research shows that lead has a deleterious impact on the immune system and is an important factor in inflammation. Lead also impacts cytokine metabolism (interleukins IL-1b, IL-4, IL-2, IL-8, and IL-6), TNF-α and INF-γ, and the expression of inflammatory enzymes (cyclooxygenases). Numerous studies have examined the impact of lead on immune system cells, including macrophages, B and T lymphocytes, and Langerhans cells. However, the impact depends on the kind of lead, dosage, route of entry, exposure period, age, host and genetic predisposition.Mechanisms by which lead may contribute to MS pathogenesis
1. oxidative stress (increased reactive oxygen species (ROS)/ malonyldialdehyde( MDA)/\[8-Hydrox-2-deoxyguanosine( 8-oHdG)\])
2. Immune system dysregulation (activation of microglia/shift toward pro-inflammatory cytokines IL-6,TNF-a)
3. Blood brain barrier disruption (lead increase BBB permeability)
4. Epigenetic effects (effect DNA methyltransferase/altered gene expression lead to autoimmunity) Therefore, studyig the effect of lead exposure on pathogenesis of multiple sclerosis is of great importance.
