Multiple sclerosis (MS) is a long-term neurodegenerative disorder that affects the central nervous system, causing disturbances in movement, balance and vision. MS is an autoimmune condition and is caused by the body’s immune system mistaking the protective covering of nerve fibres for a foreign body and mounting an attack against it. This protective covering is called myelin and diseases that cause damage to the myelin are referred to as demyelinating diseases.
Most individuals with MS have the relapsing remitting form of the condition where symptoms come and go. Others have secondary progressive MS, which is characterized by a gradual worsening of symptoms, with fewer or no periods of remission. The least common form of MS is primary progressive MS in which patients deteriorate over time and find there are no periods of remission.
Many individuals with MS can be treated with disease-modifying drugs which are aimed at slowing disease progression and providing symptom relief. Examples of these drugs include beta interferon, atalizumab and glatiramer acetate. These agents are only useful in people with the relapsing remitting or secondary progressive forms of MS, and do not benefit those with primary progressive MS.
Studies have shown that beta interferon can significantly benefit patients with MS. For example, in a placebo-controlled trial of interferon beta-1b treatment in 372 patients with relapsing remitting disease, there were significant reductions in disease activity and the formation of new lesion in patients administered 1.6 or 8.0 MIU of the drug, compared with those who received placebo.
The mechanism of action of interferon beta in MS remains unclear. The drug is an immune modulator and helps balance the levels of pro-and anti-inflammatory cells that cross the blood–brain barrier, which has the overall effect of reducing inflammation of the nerve cells. The drug is also thought to help promote neuronal growth. Although the exact mechanism by which interferon beta exerts its effects is not yet clear, some details of the drug’s effects include:
Inhibition of T cell activation and proliferation
Induced cell death of autoreactive T cells
Modulation of the cytokine profile production to anti-inflammatory rather than pro-inflammatory
Reduced leukocyte migration across blood-brain barrier
Side effects and contraindications of beta interferon
Mild side effects include flu-like symptoms such as fever, chills, headache, muscle ache and fatigue. Symptoms may occur within 48 hours of the injection but tend to fade and disappear after 3 months of treatment. In the meantime, symptoms can be relieved with anti-inflammatory agents such as ibuprofen. Interferon beta is not prescribed to those aged under 18 years or to pregnant or breastfeeding women.
Reviewed by Sally Robertson, BSc