The gut microbiome may play a role in the chronic pain condition fibromyalgia. Based on experiments in mice and humans, a faecal microbiota transplant (FMT) from people with fibromyalgia induces its painful symptoms, which can be relieved by an FMT from those without the condition.
Fibromyalgia, which affects around 2 per cent of people in the UK and US, is characterised by widespread pain over the body, often with no clear cause.
Researchers have previously observed . To better understand the role this ecosystem may play, at McGill University in Montreal, Canada, and his colleagues transplanted faecal samples from women with and without the condition into 鈥済erm-free鈥� mice, which lacked any gut microbes. Samples were taken from women as they are much more likely to develop fibromyalgia than men.
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Four weeks later, the mice that received faecal matter from women with fibromyalgia had a different gut bacterial make-up than those transplanted with faecal matter from women without the condition.
The researchers also found that the mice that received the fibromyalgia-associated faecal matter became hypersensitive to pain when a pinprick or hot and cold temperatures were applied to their back paw, unlike the other mice.
In a second part of the experiment, the researchers tested for a potential fibromyalgia therapy. Existing treatments focus on exercise, talking therapies and medication, with mixed success.
The mice that had received the fibromyalgia-associated faecal matter were given an 鈥渁ntibiotic cocktail鈥� to deplete the bacteria in their guts. They were then given an FMT from the women without the condition.
The animals soon started showing a dramatic decrease in their perception of pain, the researchers write in their paper.
鈥淲e transplanted the faecal matter from sick women to mice and we鈥檝e shown that there is a definite change in the behaviour of the mice that is directly associated with the transplant,鈥� says Shir. 鈥淲e鈥檝e also shown that the phenomenon disappears when the mice are given a transplant from healthy women.鈥�
In a third part of the study, the researchers gave 14 women with fibromyalgia a round of antibiotics. They were then given five faecal samples, administered via an oral capsule every two weeks, from people without the condition.
One week after the last transplant, 12 of the women said their pain had decreased by an average of two points on a 10-point scale, with this pain reduction being sustained throughout the 12-week trial. A statistical analysis suggests this pain reduction wasn鈥檛 a chance finding. The women also reported experiencing reduced anxiety and depression symptoms, which often occur with fibromyalgia, as well as improved sleep and overall quality of life.
With regards to FMTs being a potential fibromyalgia treatment, Shir says: 鈥淲e鈥檙e at the beginning of a long road, but what we鈥檙e seeing is really promising.鈥�
The third part of the study was small and open label, meaning that the women knew the treatment they were being given, so could have been expecting an improvement to their symptoms. Regardless, , who researches the link between the gut microbiome and fibromyalgia at the University of Sydney, Australia, says it is a big step.
鈥淭his is critically important work which helps to inform our evolving understanding of the complex function of the human gut microbiome and how it affects the lived experience of pain,鈥� she says. The intervention 鈥渨arrants a larger-scale exploration鈥�, to help us better understand how gut microbes can affect the perception of pain for some, says Erdrich.
bioRxiv
