Gulf War Illness (GWI) has many symptoms, and now a link between changes in the gut microbiome (bacteria living in the intestines) and neuroinflammation (inflammation of the brain) has been identified, according to a new study. These findings may result in new treatment approaches for people with GWI gastrointestinal disturbances and symptoms of brain impairment.
The study, “Altered gut microbiome in a mouse model of Gulf War Illness causes neuroinflammation and intestinal injury via leaky gut and TLR4 activation,” published in PLOS One, was conducted at the University of South Carolina Arnold School of Public Health.
Gulf War Illness (also known as Gulf War Syndrome) affects 25 to 32 percent of the 700,000 U.S. veterans who served in the 1990-91 Persian Gulf War, and can be traced to chemical exposure. Symptoms of GWI include chronic headache; cognitive impairment such as memory and concentration difficulties; debilitating fatigue; widespread pain; respiratory, sleep, and gastrointestinal problems; and other unexplained medical symptoms.
Previous studies have focused on the neurological effects of the disease; less is know about the mechanisms that link intestinal and neurological abnormalities.
Researchers used a mouse model of GWI and found that the disease alters the stomach microbiome. The “bad” bacteria then produce toxic substances known as endotoxins, which cross the lining of the gut into the blood and circulate throughout the body. These endotoxins trigger an inflammatory response that, in turn, causes several abnormalities in the brain commonly observed in GWI patients.
These results can lead to new treatments for GWI, benefiting current patients as well as veterans of later military operations who show similar signs of the illness, though less severe.
“Humans and animals have specific types of bacteria that help aid various physiological processes, including digestion, absorption, immunity and gut integrity, and when external factors change the bacterial composition in our digestive systems, we have problems,” Dr. Saurabh Chatterjee, associate professor in the Department of Environmental Health Sciences at the Arnold School of Public Health, said in a press release.
“Obesity, metabolic syndrome, inflammatory bowel syndrome, and liver disease have already been linked with changes in bacterial composition of the gut,” Chatterjee said.
“When the composition [of the gut] changes due to an increase in certain bad bacteria, this causes disruption to the mucosal lining of the intestinal walls — leading more intestinal contents to leak into the blood,” he added.
These endotoxins, which leach into the blood and circulate to the brain, activate receptors that impair the body’s inflammatory mediators.
“We know that many diseases like obesity, liver disease, and inflammatory bowel syndrome can be cured or at least decreased by consuming good bacteria, like probiotics,” Chatterjee said. “Now that this connection has been established, it opens the door to new studies where GWI patients take probiotics for a longer period of time and, hopefully, see improvement in symptoms connected with metabolic syndrome, gastrointestinal disturbances, and maybe even neuroinflammation.”