A new study suggests overactive immune system triggers persistent fatigue, which eventually leads to chronic fatigue syndrome (CFS) or called myalgic encephalomyelitis (ME). This is a long-term debilitating condition wherein those who are suffering from it are experiencing exhaustion not relieved by rest, pain, trouble with memories and sleeping, as well as mental fogginess.
Several studies have suggested the immune system might be involved in the CFS - specifically viral infections could be one of the potential triggers. However, the evidence of these studies was inconclusive, in which some revealed elevated levels of the inflammatory markers, yet the abnormalities were inconsistent across studies, according to Alice Russell from King's College London who is also the first author of the study.
Since it's impossible to identify who will get the virus, it is also impossible to find out the levels of biological molecules before, during, and after a possible CFS trigger infection. So, experts of the latest study used a group of people with different conditions so they can explore what's the role of immune response in persistent fatigue, the South China Morning Post reported.
The study, published in the journal Psychoneuroendocrinology, shows how researchers recruited 55 patients with a chronic hepatitis C infection. All of the participants were given a six- to 12-month course of injections of interferon alpha, which is a protein naturally produced by the body and stimulates white blood cells to provoke an immune response. This treatment was previously linked to certain side effects - particularly ongoing fatigue to some patients.
Even though the majority of patients recovered from hepatitis C, there's increased fatigue during the treatment, which was reduced when injections ended. But, six months after the treatment was done, 18 patients stayed more fatigue compared before when the treatment started. They also had slightly higher levels of a protein known as IL10 - linked to inflammation in their blood before treatment began.
After four weeks of treatment, their levels of IL10 and another inflammatory protein known as IL6 were twice as high as compared to those who recovered without persistent fatigue. But, when the interferon alpha injections stopped after six months, there were no differences in the inflammation proteins levels between those without and with persistent fatigue.
The study indicates that by the time ongoing fatigue was established, the immune activation was no longer present, said Professor Carmine Pariante, a co-author of the study from King's College London. He added overactive immune response might trigger the changes in the muscle, metabolism, as well as the brain which leads to ongoing fatigue. Genetics and frequent infection during childhood might also explain why only some people had a heightened immune response.
But still, the study has limitations: those with persistent fatigue were not diagnosed with CFS, most hepatitis C participants were men, the study was small, and the levels of interferon-alpha given to patients were higher than it would normally be produced in the body.
