Researchers have discovered differences in levels of an important group of proteins in chronic fatigue syndrome patients which they say could potentially be used as a biomarker to diagnose the condition.
The study published in the latest edition of the journal Clinical and Investigative Medicine suggests that chronic fatigue syndrome (ME/CFS) patients have an abnormal adaptive response to oxidative stress. This means patients are less able to deal with potentially damaging free radicals than healthy people are.
Researchers determined this by comparing levels of heat shock proteins in ME/CFS patients and healthy individuals immediately before and after and up to a week after a standardised treadmill exercise session.
Heat shock proteins (HSPs), also known stress proteins, are a group of proteins that are present in all cells in the body. Their levels typically rise when the body (or individual cells) are exposed to various types of environmental stress like exercise, temperature changes, and oxygen deprivation.
Also present under normal conditions HSPs are vital to the production and metabolism of proteins within the cells of the body. They make sure proteins are the right shape so they function correctly, shuttle them to different areas of the cell, and transport old proteins to 'waste disposal' sites within the cell where they are broken down. It is also thought HSPs may play a role in immune system function by making sure the correct proteins are present on cell membranes so that the immune systen can identify diseased cells and take approach action to dispose of them.
In this latest study the researchers measured levels of various HSPs in the cells of 6 ME/CFS patients and 7 age and sex-matched healthy controls. Levels were measured immediately before, after, and at 1 day and 7 days following the standardised treadmill exercise.
They found that before exercise the levels of one particular HSP (HSP27) were significantly higher in patients than in controls. Since HSP levels rise when the body is under stress this could suggest that in ME/CFS the body is under constant stress so HSPs are chronically activated. Following exercise however these levels in ME/CFS patients decreased immediately and remained below resting levels the following day. This is the opposite to the normal response expected. In contrast, HSP27 levels remained relatively constant following exercise among control subjects.
Similar patterns of declining HSPs were seen for other variants following exercise in the ME/CFS sufferers even up to a week later while levels remained constant or increased in the healthy controls.
The researchers conclude that: "These preliminary findings suggest an abnormal or defective adaptive response to oxidative stress [induced here by exercise] in CFS, and raise the possibility that HSP profiling may provide a more objective biologic marker for this illness."