Myositis Overview: Directions and New Frontiers of Research and Treatment

Summary of a presentation to the Myositis Education and Support Program at HSS on March 12, 2008


 


Stephen J. Di Martino, MD, PhD, RhMSUS

Assistant Attending Rheumatologist, Hospital for Special Surgery
Instructor in Clinical Medicine, Weill Cornell Medical College

Myositis Key Terms

To prepare the audience for a discussion of the direction of myositis research and treatment, Dr. Dimartino began the meeting by offering some basic definitions of the following terms, which are key to understanding myositis:

  • Immune: to be free from the possibility of acquiring an infectious disease; to be resistant to an infectious disease by a specific disease-producing agent.
  • Immunity: the status of being immune.
  • Immune system: an intricate working of cellular and molecular components. This provides a defense (immune response) against foreign organisms or substances and abnormal native cells.
  • Inflammation: a basic way in which the body responds to infection, irritation, or other injury. The key features of inflammation are: redness, warmth, swelling, and pain. 
  • Autoimmunity: a misguided immune response that occurs when the immune system goes awry and attacks its own body. The progression from benign (harmless) immunity to pathogenic immunity can cause a wide range of human illnesses which are grouped collectively as autoimmune diseases. Autoimmunity is evidenced by the presence of autoantibodies (antibodies that are directed against one’s own body),which react with host antigens. The inflammatory myopathies are considered to be autoimmune diseases.

What is myopathy?

Simply stated, myopathy is a disorder of the muscle. There are different causes and types of myopathy:

  • Drug-induced myopathy: caused by the use of certain drugs, such as statins, steroids, cocaine, and alcohol.
  • Endocrine myopathy: caused by problems of the endocrine system. Examples of this are over- (hyper) active and under- (hypo) active thyroids and Cushing’s Syndrome.
  • The muscular dystrophies: a term that describes a genetic (inherited) disorder of the muscles. Muscular dystrophy causes the muscles to become very weak.
  • Infection: Sometimes myopathy can be caused by a viral, bacterial, or parasitic infection.
  • Inflammatory myopathy: These are systemic and idiopathic types of myopathy, and include: polymyositis, dermatomyositis, inclusion body myositis, paraneoplastic myositis, and overlap syndromes.

What is myositis?

The simplest definition of myositis is that it is a chronic inflammation of the muscle. It is an inflammatory myopathy that includes polymyositis, dermatomyositis, and inclusion body myositis as its three main types.

Dr. DiMartino reviewed the cellular events that relate to myositis that cause inflammation, as well as how antibodies and white blood cells work together to fight invading organisms. He then discussed myositis in the context of other related systemic inflammatory diseases, such as rheumatoid arthritis and lupus, explaining that the presence of autoantibodies (antibodies against the self) can precede clinical symptoms by years.

Treatment Options for Myositis

Treatment options for myositis include several medications, including the following:

  • Steroids: used to decrease inflammation. Prednisone is a commonly prescribed steroid.
  • IVIG (Intravenous immune globulin): a blood product that is administered intravenously to boost the body’s immune response, and is usually reserved as an option when other treatments prove less effective. It may be used for patients with inclusion body myositis, especially when swallowing difficulty is present.
  • Methotrexate: an immunosuppressant that can be used alone or in conjunction with other medications to suppress the immune system
  • Imuran: an immunosuppressant, similar to Methotrexate, that can be used alone or in conjunction with other medications.
  • CellCept: yet another immunosuppressant (borrowed from transplant medicine) being used as a treatment option.
  • Plaquenil: may be useful for treatment of rash in patients with dermatomyositis

The importance of physical therapy in the treatment of myositis cannot be overlooked. It is essential to improving muscle strength and range of motion, to prevent muscle atrophy, and to improve one’s quality of life. Programs should be tailored to specific needs; therefore, it is important to discuss this with your physician and/or physical therapist.

It should be noted that there is no one treatment option - or combination of treatment options - that is appropriate for everyone. Each patient’s disease is unique and will probably vary along the course of the disease. Keeping this in mind, all treatment options and concerns should be discussed with one’s own physician.

What’s on the horizon?

Research for myositis and the inflammatory myopathies is ongoing. There is more research that is occurring for other diseases such as lupus and rheumatoid arthritis, but while this research is not specifically targeted for myositis, there is often a crossover benefit for myositis treatment, since they are categorized similarly.

Future treatment possibilities include, but are not limited to:

  • Rituximab: also known as Rituxan, is administered intravenously and targets B-cells, which play a role in the inflammation of myositis.
Dr. DiMartino is the principal investigator of a multicenter study, funded by The National Institutes of Health (NIH), which is being conducted at HSS. To learn more about this important study, please contact Dr. DiMartino at: Dimartinos@hss.edu
  • TNF blockers: suppress tumor necrosis factor proteins (TNF) that are associated with inflammation. The names of TNF blockers used in the treatment of myositis are: Remicade (administered intravenously), Enbrel, and Humira, (given by subcutaneous - under the skin - injection).
  • Orencia (abatacept): has been used in the treatment of rheumatoid arthritis; usefulness in myositis is not yet known.
  • Interferon alfa blockade: drugs that block interferon; are in early trials for patients with autoimmune conditions.

It is hoped that these and future medications and research will offer many additional treatment options and, eventually, a cure for myositis.


 

Myositis Support Group at HSS

Learn more about the Myositis Support Group, a free support and education group held monthly at the Hospital for Special Surgery


Summary by Suzan Fischbein, LMSW, Myositis Support Group Coordinator

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