June 25 (UPI) — Early stages of liver disease were detected using chemical compounds produced by bacteria in the gut, and suggest a simple blood test could be used for detection.
Researchers in England, Spain and Italy investigated whether there is a link between the early stages of non-alcoholic fatty liver disease and the trillions of bacteria, viruses and other microbes living in the digestive tract. Their findings were published Monday in Nature Medicine.
Previous studies show that the number of active microbial genes drop dramatically with metabolic disorders, such as obesity, which inspired the researchers to investigate whether a similar decrease occurs with liver disease.
“The concept that we could use chemical signals produced by our gut bacteria to spot disease is an exciting one,” Dr. Marc-Emmanuel Dumas, of the Department of Surgery & Cancer at Imperial College London, said in a press release. “It opens the possibility that simple screening test at a GP clinic could one day be used to spot the early signs of disease.”
He said someday the test may identify patients at risk and even predict the course of disease.
“The scientific literature shows that the microbiome changes in a range of diseases. But it may be a case of ‘chicken and egg,’ and not necessarily cause and effect,” said Dr. Lesley Hoyles, a researcher in the Department of Surgery & Cancer at ICL. “It’s clear that the microbiome influences us because at any one time we have around 200 metabolites in our circulation from our gut bacteria, so they have long-term effects and may be influencing disease.”
Although researchers said an estimated one in three adults may have the early stages of NAFLD, patients usually show few or no symptoms until the disease is advanced. The condition can be diagnosed with a blood test, as well as with an ultrasound in advanced cases.
With the disease, it starts with the build-up of fat in the liver and can lead to scarring and cirrhosis. If this happens, the organ eventually shrinks, leading to possible liver failure and cancer.
In addition, NAFLD increases risk for developing type 2 diabetes and cardiovascular diseases.
Researchers identified a compound called phenylacetic acid, or PAA, which is produced by bacteria in the gut. Its presence in the blood is connected with the early onset of NAFLD.
“Through this work we may have uncovered a biomarker for the disease itself,” Hoyles said. “Overall, it demonstrates the microbiome is definitely having an effect on our health.”
The researchers collected biological data from 100 obese women with fatty livers, including blood and urine samples, liver biopsies and fecal samples. These samples were compared with healthy patients.
Among the differences they found was increased levels of PAA, a compound produced by gut bacteria as they break down amino acids for food.
Researchers also found subtle changes in the makeup of the microbiome itself. As the disease became more advanced, the number of genes encoded by gut bacteria began to decrease.
They found that treating healthy mice with PAA caused fat to build up in their livers.
In addition, they also transplanted a tiny fecal sample from a patient with fatty liver disease into mice whose microbiomes had been cleared with antibiotics. That led to them developing fatty livers.
This means that the key gut bugs may be lost in patients with fatty liver disease.
“We have discovered exciting connections between gut microbiota composition, fatty liver and carbohydrate metabolism,” said Dr. Jose Manuel Fernandez-Real, lead clinician from University of Girona in Spain. “This contributes to better understand why 30 percent of subjects with massive obesity do not develop a fatty liver despite dramatically increased fat mass.”
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