In a new study, researchers have discovered that patients suffering from obsessive-compulsive disorder (OCD) have increased levels of a protein called Immuno-moodulin (Imood) in their lymphocytes, a type of immune cell.
Mice with high levels of this protein also showed behaviors that are characteristic of anxiety and stress, such as digging and excessive grooming.
When the researchers treated the mice with an antibody that neutralized Imood, the animals’ anxiety levels reduced.
The findings have led them to file a patent application for the antibody and they are now working with a drug company to develop a potential treatment for human patients.
The research was conducted by scientists at the Queen Mary University of London and the University of Roehampton.
There is mounting evidence that the immune system plays an important role in mental disorders.
And in fact, people with auto-immune diseases are known to have higher than average rates of mental health disorders such as anxiety, depression, and OCD.
The current findings overturn a lot of conventional thinking about mental health disorders being solely caused by the central nervous system.
The team first identified Imood by chance while studying a different protein called Annexin-A1 and the role it plays in autoimmune diseases such as multiple sclerosis and lupus.
They had created transgenic mice to over-express this protein in their T-cells, one of the main cells responsible for the development of autoimmune diseases, but found the mice showed more anxiety than normal.
When the team analyzed the genes expressed in the animals’ T-cells, they discovered one gene, in particular, was especially active.
The protein produced from this gene was what they eventually named Immuno-moodulin, or Imood.
When the anxious mice were given an antibody that blocked Imood, their behavior returned to normal in a couple of days.
The researchers tested the immune cells from 23 patients with OCD and 20 healthy volunteers. They found Imood expression was around six times higher in the OCD patients.
Other recent research by scientists elsewhere has also found the same protein may also play a role in Attention-Deficit/Hyperactivity Disorder.
The team believes Imood does not directly regulate brain functions in a classical way, for example by changing the levels of chemical signals in neurons.
Instead, it may influence genes in brain cells that have been linked to mental disorders like OCD.
In the meantime, the team is trying to develop antibodies against Imood that can be used in humans and to understand how this could be used to treat patients with mental disorders.
The lead author of the study is Professor Fulvio D’Acquisto, a professor of immunology.
The study is published in Brain, Behavior, and Immunity.
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