Alterations in Amino Acids in Blood That Affect Metabolism May Help Explain Chronic Fatigue
Chronic fatigue syndrome, more recently known as myalgic encephalopathy, is a debilitating and somewhat mysterious illness. However, a 2016 article in the Journal of Clinical Investigation Insight suggests that low blood levels of amino acids related to oxidative metabolism, the process by which oxygen is used to make energy from sugars, may play a role in the illness. High levels of amino acids related to the breakdown of proteins were also seen.
The study by Øystein Fluge and colleagues compared blood concentrations of 20 amino acids in 200 patients with chronic fatigue and 102 healthy participants. There were shortages in 6 amino acids that fuel oxidative metabolism in those with chronic fatigue, particularly women. Men with chronic fatigue had high levels of a different amino acid related to protein catabolism, the breaking down of complex molecules, a process that releases energy.
The differences between men and women with the illness might be because men use muscle tissue as a source for amino acids, while women, who have less muscle mass, use amino acids from blood as fuel.
The changes in both sexes suggest a functional impairment in pyruvate dehydrogenase (PDH), an enzyme that is important for the conversion of carbohydrates into energy. If PDH fails to work and cells turn elsewhere to create energy, muscles may suddenly weaken and lactate may build up, which patients experience as a burning in their muscles after the slightest exertion.
Fluge and colleagues are cancer researchers. They stumbled into chronic fatigue research when they noticed that people with chronic fatigue who were treated for cancer with the drug rituximab saw reductions in their fatigue. Rituximab, which is also used to treat some autoimmune diseases, is a monoclonal antibody directed at B cells. When it binds, it induces cell death. The researchers hope to clarify the link between the immune system and the problems with energy metabolism they have identified in people with chronic fatigue.
