IBD is a long-term disease involving inflammation of the gut and affecting around 260 000 in the UK. The term usually refers to two conditions – ulcerative colitis and Crohn's disease.
The exact causes of IBD are not yet known, but it is widely accepted that a combination of genetic factors and disruptions to the immune system play a central role in the condition.
The Kennedy researchers showed that the production of eosinophils – a type of white blood cell present in the immune system – is higher in colitis, as is the accumulation of substances linked to eosinophils in the inflamed intestine. The team led by Prof Fiona Powrie and Dr Thibault Griseri also found that eosinophils release toxic and inflammatory substances during colitis, highlighting their potential for causing disease.
Whilst eosinophils are commonly associated with beneficial immune responses against parasites they are also linked to harmful allergic responses. Although they are quite abundant in the healthy intestine, their role in the gut immune stability is enigmatic and the molecular signals that drive them from protective to tissue damaging are unknown.
Identifying the molecular mechanisms causing IBD is key to developing new treatments for the condition, and in this study Dr Griseri and team were able to identify the inflammatory molecule - the cytokine GM-CSF - as a crucial driver of the pathogenic activity of eosinophils in colitis.
"We are enthusiastic about these data as we think that together with our former study revealing a key role for GM-CSF in dysregulated white blood cell production in the bone marrow during colitis, our study highlights GM-CSF as a key driver of chronic inflammation and a potential novel therapeutic target in IBD", says Dr Thibault Griseri.
Read full paper at Immunity.
Image: Microscopic view of eosinophil granulocyte, component of the white blood cells or leukocytes of the immune system having cytoplasmic granules, showing the lobed nucleus; Somersault1824/Shutterstock.com.