New Study Finds Probiotic Potential in Battling Pesticide Damage

Researchers have mapped how pesticides impact specific gut microbes, uncovering potential protective bacteria and opening the door to new health interventions.

Study in mice suggests potential for probiotic treatment.

Although previous research has linked pesticide exposure to harmful effects on gut microbes, a new study is the first to chart how specific bacteria in the human digestive system respond to interactions with insecticides, both in laboratory settings and in an animal model.

The researchers found that more than a dozen commonly used pesticides altered the growth of human gut bacteria, disrupted how these microbes handle nutrients, and in some cases, accumulated inside bacterial cells. The team created a publicly available “atlas” detailing these molecular interactions, which could support future research into disease mechanisms and potential treatments.

Mouse experiments revealed that a particular species of gut bacteria helped reduce the toxic effects of pesticides, specifically by limiting inflammation. This finding points to the potential for probiotic therapies aimed at countering some of the health risks associated with pesticide exposure.

Gut bacteria may help detoxify pesticides

“We’ve provided further understanding of how pesticides or environmental pollutants impact human health by modulating an important collection of microorganisms,” said senior author Jiangjiang Zhu, associate professor of human sciences at The Ohio State University.

“We also identified certain microbes that can degrade, remove or clear some of these pesticides from biological systems, which may be potential therapeutics in the future to help people clear toxicity from the gut that have been introduced by food and water intake, providing better solutions for human health.”

The research was published recently in Nature Communications.

Lab study tests 18 pesticides and 17 gut species

The researchers conducted laboratory experiments to examine how 18 widely used agricultural pesticides interact with 17 different species of gut bacteria. These bacterial species represent four major groups commonly found in the human digestive system and are known to play roles in either maintaining health or contributing to disease.

The pesticides tested included well-known chemicals such as DDT (which is banned in the United States but still used indoors in some regions to control malaria-carrying mosquitoes), atrazine, permethrin, and chlorpyrifos. According to Zhu, despite restrictions or bans on some of these compounds, residues from older, persistent pesticides continue to be found in soil and water.

“We grew bacteria in culture and exposed them to relevant concentrations of pesticides to see how microbes responded to those pesticide exposures,” said first author Li Chen, a senior research associate in Zhu’s lab, who managed over 10,000 samples that were analyzed in the study.

Drawing from their results, the researchers created a detailed interaction map showing how specific pesticides affect gut bacteria. The network identifies which pesticides stimulated or suppressed bacterial growth, as well as which bacterial species absorbed pesticide compounds. This absorption may help explain how pesticide exposure can persist in the body over time.

“Most previous environmental health studies reported that pesticide contamination affects the overall composition of gut bacteria,” Chen said. “We showed those pesticides really can affect specific gut bacteria and detailed how these changes will affect the general composition.”

Pesticide exposure alters metabolism and lipids

The analysis identified specific metabolic changes in 306 pesticide-gut microbe pairs, leading to examination of how those altered growth patterns and accumulation of chemicals affected metabolites – the molecular products of biochemical reactions that break down nutrients to produce energy and perform other essential functions. Metabolites have numerous roles, from altering the metabolic process itself to sending signals related to multiple cell functions and immune system activation.

In addition, the study team performed a separate analysis zeroing in on another important class of molecules that can be produced by gut microbes – the fatty, oily, and waxy compounds called lipids that are essential to many body functions.

Researchers also studied the effects of pesticide exposure in healthy mice first given antibiotics to clear their digestive systems of microbes. The team introduced Bacteroides ovatus, a common strain of human gut bacteria, to one group of mice and compared them to controls after four weeks of exposure to pesticides.

Results verified what was seen in the lab, showing that pesticides generated inflammation in multiple organs in the mice and that the presence of the introduced bacteria after chemical exposure set off a range of changes in metabolic activity and lipid production. Specifically, an increase in some classes of lipids inhibited the signaling pathway of a protein linked to oxidative stress.

Gut microbes could buffer pesticide effects

“We identified microbes that may modulate the toxic effect of pesticides to the host by somehow buffering the inflammation process,” said Zhu, also an investigator in The Ohio State University Comprehensive Cancer Center Molecular Carcinogenesis and Chemoprevention Research Program.

“We know inflammation is generally bad for the body. If something toxic is going to induce it, and there are other molecules that can counteract that agent, you may have a solution to intervene or prevent larger-scale damage.”

In the next phase of this work, Zhu’s lab plans to further explain where metabolic changes to gut microbes fit into various health and disease conditions after pesticide exposure. He expects other scientists will do the same.

“We are mapping out this central interaction between pesticides and gut microbes. And then other labs can leverage what we have discovered – for example, after exposure to a pesticide, gut microbe reactions may lead to downstream consequences that contribute to disease research and eventually help with predicting targets or identifying an intervention strategy,” he said.

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