A new discovery, which could lead to better treatments for people with multiple sclerosis (MS) in the future, has been made by scientists at Trinity College Dublin (TCD).
MS is an autoimmune disease and according to the researchers, their discovery could also lead to more effective treatments for people living with other autoimmune conditions, such as rheumatoid arthritis and psoriasis.
With autoimmune conditions, the immune system mistakenly attacks healthy cells in the body. MS affects the central nervous system - the brain and the spinal cord. It causes a gradual degeneration of the nerves, which results in a progressive deterioration in various functions controlled by the nervous system, such as vision, speech and movement.
Around 2.3 million people are affected worldwide, including over 9,000 people in Ireland.
The way in which this disease works is still unclear. However, studies in a mouse model of MS, called experimental autoimmune encephalomyelitis (EAE), have shown that immune ‘T cells', which secrete an immune molecule called ‘IL-17', cause damage to the myelin sheath that surrounds nerves in the central nervous system.
Early clinical trials with antibody-based drugs that block IL-17 have shown promise in the treatment of relapsing-remitting MS - the most common form of the condition - and have already been licensed for the treatment of psoriasis.
However, the team at TCD has discovered an entirely new role for IL-17 in EAE, and potentially in MS.
"Our team found that IL-17 plays a critical ‘priming' role in kick-starting the disease-causing immune response that mediates the damage in EAE and MS.
"The new research shows that, instead of playing a direct part in CNS pathology, a key role of IL-17 is to mobilise and activate an army of disease-causing immune cells in the lymph nodes that then migrate to the CNS to cause the nerve damage," explained one of the lead researchers, Prof Kingston Mills, of TCD.
According to co-lead researcher, Dr Aoife McGinley, of TCD, these findings suggest that drugs that block IL-17 "may not need to get across the blood-brain-barrier to be effective in treating MS".
"So, as well as shedding new light on the importance of IL-17 as a drugs target in relapsing-remitting MS, our research highlights the huge potential of drugs that block IL-17 in the treatment of other autoimmune diseases, such as psoriasis and rheumatoid arthritis," she noted.
Details of these findings are published in the journal, Immunity.
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