CORDIS - EU research results

Revisiting immunomodulatory functions of IL10 by examining human knock-outs

Final Report Summary - RIFEK (Revisiting immunomodulatory functions of IL10 by examining human knock-outs)

Inflammatory bowel disease (IBD) such as Crohn's disease and ulcerative colitis is a chronic inflammation that primarily affects the gut. IBD patients present with abdominal pain, diarrhoea and bleeding, but may also come down with extraintestinal manifestations affecting joints, skin and eyes, giving it the aspect of a systemic disease. IBD is relatively frequent; it affects an estimated 2.2 millions in Europe and usually becomes apparent in the second or third decade of life. IBD, however, may also affect small children as young as 3 months. Apart from the gut several other organ systems might be affected including joints, skin and eyes.
The prevailing theory is that IBD is caused by an uncontrolled reaction of the immune system to harmless bacteria in the gut. Several mechanisms, however, protect humans from such excessive immune reactions and from possible tissue damage. The probably most powerful component that keeps the human immune system in check, is a small molecule called interleukin (IL)-10.
We have found patients without IL-10 or the molecule needed to make it work, the IL-10 receptor (IL-10R). These patients come down within the first months of life with utterly severe inflammation of the gut. This disease, called IL-10 and/or IL-10R deficiency is life threatening as it cannot be treated with usual medicines. The only possibility to cure them is bone-marrow transplantation; this substantially improves their quality of life and helps them live a more or less normal life.
Aim of this project was to find such patients without IL-10 or IL-10R and to assess the frequency of the disease and to shed light on the mechanism why such children get that severely ill. Blood samples from children with severe inflammation of the gut were taken, and their white blood cells (a substantial proportion of our immune cells) were examined for functional failures of their IL-10 and IL-10R.
We have established a network with other researchers and specialist in immunology and paediatric gastroenterology within and outside Europe. This networking made it possible to get access to a larger number of blood samples from patients with suspected IL-10/IL-10R deficiency. Overall, blood samples of more than 100 patients were examined, primarily from children. By carrying out functional and/or genetic analyses several children with a defective IL-10R have been identified; this paved the way to carry out a life saving and curing bone marrow transplantation in these small patients.
We discovered several more abnormalities in affected patients: some of them did not have enough antibodies, some appeared to be more prone to infections and others had either too many or not enough certain immune cells. In contrast to healthy individuals, IL-10R deficient patients revealed increased numbers of certain T lymphocytes that have been shown to associated with IBD, namely IL-17 producing T cells (Th17) cells and IL-17/IFN-gamma producing so-called "double positive" T cells. We showed that these potentially tissue damaging T lymphocytes were also increased in IBD patients with normal IL-10 function demonstrating their importance in the development of IBD.
Other T lymphocytes, so called regulatory T cells as they can produce IL-10 and thus can control these tissue damaging cells, were similar in number and function when compared with healthy control persons.
When analysing the release of inflammation associated molecules (so called pro-inflammatory cytokines) from white blood cells of patients without IL-10R we found that several of such cytokines were up regulated. The most important ones were classical cytokines such as tumour necrosis factor, IL-1-alpha/-beta and IL-6.
When stimulated, white blood cells do not only release such pro-inflammatory cytokines but also IL-10; this IL-10 release is part of a negative feedback loop to avoid an excessive pro-inflammatory response. This negative feedback does not work anymore in IL-10R deficient patients, but we found that it may also be impaired in other IBD patients. We identified patients whose white blood cells secreted only very low amounts of IL-10 what may contribute to their disease.
Patients with IL-10/IL-10R deficiency do not benefit from immunosuppressive medicines such as cortisone and hence we hypothesized that IL-10 might be required for the function of this and other immunosuppressive drug. Our experimental approach, however, did not deliver evidence, that IL-10 is required to make cortisone and other immunosuppressive medicines work.
Our work supported and helped paediatricians, paediatric gastroenterologists and immunologists make the right diagnosis and clinical decision. Early diagnosis of IL-10/IL-10R deficiency can save the small children's live as a bone-marrow donor can be instantly looked for. In addition, the prospects of a bone-marrow transplantation is much the better the smaller the children are. Detecting this rare disease and its quick treatment with a bone-marrow transplant is an impressive example for the use of genetic diagnostics and translational medicine.

Contact details of the project manager:
PD Dr. E. Glocker
Department of Medical Microbiology, University Hospital Freiburg