Prof. Yan Yiannakou
Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle, UK
Irritable bowel syndrome (IBS) is a relatively common condition characterised by a number of symptoms affecting the digestive system, including stomach cramps, bloating, diarrhoea and constipation. The symptoms can be different between individuals, and are often triggered by stress or particular foods.
Interestingly, the prevalence of ME/CFS is estimated to be 35 times higher among people with IBS than in the rest of the population. And, conversely, there is also a high prevalence of IBS among people with ME/CFS.
But that’s not the only link between the two conditions. Both ME/CFS and IBS are often reported to occur after an infection, and they are also both associated with abnormal activation of the immune system, as indicated by raised levels of various cytokines and immune cells.
There is also evidence of changes to the gut microbiome in ME/CFS and IBS. The microbiome generally refers to the collection of around 100 trillion microorganisms, including bacteria, that live on or inside the human body. Many of these bacteria are beneficial to us and essential to our survival. In the gut, they live on the membranous lining, or mucosa, and break down our food and help protect us against infection. This whole area has become a hot topic of research in many diseases.
The similarities between ME/CFS and IBS suggest that the two conditions may be part of a spectrum of illness, with shared pathophysiological changes in response to infection. This is the fascinating idea that Prof. Yan Yiannakou and his team in Newcastle are planning to investigate in a new project recently awarded funding by ME Research UK.
Prof. Yiannakou suggests that, if the two conditions are linked in this way, then ‘patients with ME/CFS alone would have mucosal immune and microbiome changes that are similar to, though less pronounced, than patients with both ME/CFS and IBS’.
To explore this, the team will recruit four groups of individuals: 25 patients with ME/CFS alone, 25 with IBS alone, 25 with both ME/CFS and IBS, and 25 healthy control subjects. Following clinical assessment, blood samples will be collected to analyse a variety of markers of immune activation, while stool samples will be taken from which to measure changes in the faecal microbiome using DNA analysis.
In addition, in five individuals from each group, biopsies of the colon will be taken in order to analyse the mucosal immunology and microbiome more directly. This whole process is particularly challenging and involves invasive tests, so its feasibility and acceptability to patients need to be explored.
Although these are relatively small groups of patients, Prof. Yiannakou hopes that the results of this study will demonstrate that the techniques are achievable, and provide pilot data on which to base larger studies examining the links between the gut microbiome and immune system in ME/CFS and IBS.