Your Body Attacking Itself: Multiple Sclerosis

In the United States of America, it has been computed that nearly 20 percent of the population suffers from autoimmune diseases, and the majority of the population does not know what these grave diseases are.  So what are autoimmune diseases?  They occur when your body's immune system begins attacking healthy cells by mistake.  One of the most puzzling autoimmune diseases that we know of is multiple sclerosis (MS).

Multiple sclerosis involves an immune-mediated process in which an abnormal response of the body's immune system is directed against the central nervous system (CNS).  Autoimmune diseases are a subset of immune-mediated responses, which occur when the immune system is changed in some way.  Multiple sclerosis is basically a disease that affects the working capability of your brain, spinal cord, and optic nerves.  The central nervous system is extremely important in performing daily functions and people with multiple sclerosis have problems with vision, balance, muscle control, and other basic bodily functions.  It's hard to imagine not being able to do basic things that come as second nature to us, but this is the reality of people with multiple sclerosis.

The Body's Central Nervous System

You're probably wondering, what is going on in the brain that causes this to happen to people!  Well, nerve fibers, or axons, within the brain are important because they transmit information.  In Mrs. Eckert's Biology class, we learned about the electrical impulses, or action potentials, in these nerve fibers that triggered responses within the body.  Multiple sclerosis is extremely damaging because it affects myelin, a fatty substance that surrounds and insulates the nerve fibers, and oligodendrocytes, cells that produce myelin in the CNS.  The abnormal immune reaction produces inflammation in the central nervous system, which leads to damage of the nerve fibers exposed from demyelination.  When any part of the myelin sheath or nerve fiber is damaged or destroyed, nerve impulses traveling to and from the brain are distorted or interrupted.  Neurons in the spinal cord also become demyelinated and signals from the brain to the spinal cord may become disrupted, which leads to the decreased ability of many motor functions.  While learning about the nervous system in class, I was completely entranced by the fact that one's entire nervous system could shut down because of a lack of myelin sheaths covering their nerve fibers.  I instantly knew I wanted to learn more about how a complex, intricate body system could deteriorate just from damaged fatty substances.

A Nerve Fiber: How your body receives information

MRI Scan of a multiple sclerosis patient

Multiple sclerosis and autoimmune diseases are thought to be triggered by both genetics and outside environmental factors.  This leads us into an entirely different section in the science world: nature versus nurture.  "Nature versus nurture summarizes a long-running debate on whether human behavior is determined by the environment, whether prenatal or during a person's life, or by their genes."  Some scientists believe that people can be more susceptible to certain diseases because of the environment that they were brought up in, rather than from their genetic makeup.  There is increasing evidence that a number of environmental factors are important in the development and course of multiple sclerosis.  There is a global latitude gradient in MS prevalence, and instances of MS are increasing in the female population.  Scientists have reviewed the evidence and potential mechanisms of action for three exposures:  vitamin D, Epstein Barr virus, and cigarette smoking.  However, there is support for the debate that heredity has a large effect on people contracting MS.  Studies based upon familial aggregation and twin pairs have found increased risk to relatives with the disease.  There is evidence for both sides of the debate and as a biology student, it's interesting to learn about how the environment that one has grown up in can make them more susceptible for certain diseases.  You can read more about the complicated topic of nature versus nurture here.  

The Heavily Debated Nature vs Nurture Question

Scientists are learning more and more about science every day, including the nature of multiple sclerosis, so there is currently no cure but new possibilities are found every day.  For example, a major breakthrough in MS research was when scientists recently discovered that transcription factor T-Bet may trigger multiple sclerosis and other autoimmune diseases.  Through genetic manipulation, scientists found that "age associated B cells drive autoimmune diseases."  As our technology is becoming increasingly advanced, we can expect that scientists will ultimately find the causes of multiple sclerosis and a cure for the disease altogether.