In a new study, researchers found that the gut may be the ticket to reducing chemo’s side effects.
They observed several reactions in mice given a common chemotherapy drug: Their gut bacteria and tissue changed, their blood and brains showed signs of inflammation, and their behaviors suggested they were fatigued and cognitively impaired.
The research is the first to show these combined events in the context of chemotherapy.
It opens the door to the possibility that regulating gut bacteria could not only calm chemo side effects like nausea and diarrhea but also lessen the memory and concentration problems many cancer survivors reports.
The research was conducted by a team from Ohio State University.
In this study, female mice received six injections of the chemotherapy drug paclitaxel and a control group of mice received placebo injections.
Compared to the controls, the team found that the treated mice lost weight and showed signs of fatigue, and their performance on tests suggested they had memory loss.
The treated animals’ guts, blood, and brains were also affected in ways not seen in the control mice.
The mix of bacteria in the gut microbiome changed, and the tissue lining the colon became abnormally extended.
Specific proteins were present in circulating blood and the brain—along with activated immune cells in the brain—all indicating the immune system was busy producing a total-body inflammatory response.
The sequence of events suggested all these physiological changes were related: The gut was showing signs of permeability, meaning bits of bacteria could slip out of tight junctions in the intestine, an event that triggers an immune system attack.
When the brain detects through the blood and neural signals that the body’s immune system is activated, the brain responds in kind with its own inflammation.
And brain inflammation is the culprit behind the “mental fog” symptoms known as chemo brain.
The team says that chemotherapy is affecting the microbes in the gut and affecting the lining of the gut, and both of those changes cause inflammation in the periphery, which creates signals that promote inflammation in the brain.
That’s how it gets the brain involvement—through the immune system. And inflammation in the brain leads to sickness behaviors like fatigue and weight loss, as well as cognitive impairment.
Confirmation of these connections could lead to better interventions for cancer patients to improve bacteria and conditions in the gut that protect the brain from inflammation, which should reduce chemo brain symptoms.
The lead author of the study is Leah Pyter, an assistant professor of psychiatry and behavioral health.
The study is published in the journal Scientific Reports.
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