Dysregulation found in gut microbiomes of two Native American groups

Last Updated: 2015-12-07

By Anne Harding

NEW YORK (Reuters Health) - The gut microbiomes of Cheyenne and Arapaho individuals living in western Oklahoma show signs of dysregulation similar to those seen in people with inflammatory bowel disease, according to new findings.

Researchers also found that the microbiomes of the Cheyenne and Arapaho study participants had much more in common with their non-native-American neighbors than with the gut microbiomes of indigenous South Americans living more traditional lifestyles.

"Without question the Cheyenne and Arapaho look much more like Norman, Oklahoma," senior author Dr. Cecil Lewis from the University of Oklahoma in Norman told Reuters Health. "We do see a distinct microbiome in individuals living industrialized lifestyles."

The findings, online December 3 in Current Biology, show that looking at the microbiome in terms of broad categories of people - like Native American and non-Native American - is overly simplistic, Dr. Lewis added. "What we're talking about here in this study is really thinking more regional-, location-, population-specific."

Native American populations are poorly represented in studies of the gut microbiome in the United States, Dr. Lewis and his colleagues note in their report. To better understand gut microbiome diversity among these individuals, the researchers analyzed fecal samples from 38 Cheyenne or Arapaho individuals, 20 non-Native Americans from Norman, 10 samples from indigenous American hunter-gatherers, and 11 from indigenous American rural agriculturalists.

Overall, the U.S. samples had less microbial richness than the samples from the indigenous South Americans, the team found, and higher proportions of Firmicutes. While the microbiomes of the Cheyenne and Arapahoe and the Norman residents were similar at the phylum level, there were differences in the relative distribution of several genera in the Lachnospiraceae and Ruminococcaceae families.

The fecal metabolite profiles of the Cheyenne and Arapahoe individuals were also significantly different from the non-Native group, with higher levels of bile acid derivatives, phospholipids, cadaverine and histamine. The non-Natives were enriched for amino acids and medium/long-chain fatty acids.

"Collectively, these results indicate that the (Cheyenne and Arapahoe) participants have a gut-metabolite profile with features similar to those observed in inflammatory bowel disorders," Dr. Lewis and his team write.

Local Cheyenne and Arapaho communities have a higher prevalence of obesity and type 2 diabetes, Dr. Lewis noted. "We saw a pattern that is consistent with some clinical patterns, even though it was a non-clinical study, which really made a bold statement to us about how serious it is," he said.

"This doesn't appear to be a story about genetics," he added. "This appears to be a story about people's built environment and what they do, such as what they eat and where they live, and their access to quality food and their access to quality health care."

An important next step in the research, according to Dr. Lewis, will be to look at the relationship between dysbiosis and clinical factors such as diabetes and obesity.

"What is it that it's actually doing functionally in the gut, and how does this relate to those health variables that we're really concerned about?"

SOURCE: http://bit.ly/1YTLvv3

Curr Biol 2015.