Western study unlocking secrets of breast tissue

A unique population of microbes in the female breast may lay the groundwork for understanding how this bacterial community contributes to health and disease, according to a Western study.

The human body is home to a large and diverse population of bacteria boasting both harmful and beneficial properties. For this reason, there has been a push in recent years to characterize the bacteria associated with different parts of the body under different health conditions.

“First, we wanted to see if breast tissue actually had bacteria. Until now, we thought it (the breast tissue) was sterile, because usually, deep tissue is considered sterile,” said Camilla Urbaniak, a PhD student in the Department of Microbiology & Immunology, working under the supervision of Schulich School of Medicine & Dentistry professor Dr. Gregor Reid.

Urbaniak was the first author of the study, Bacterial microbiota of human breast tissue. The study was published online, ahead of print, in the journal, Applied and Environmental Microbiology.

Researchers believed microbes might be present in breast tissue given the known presence of bacteria in human milk.

“We found there is a lot more bacteria than people would expect,” Urbaniak said.

Proteobacteria was the most abundant in breast tissue, unlike in other parts of the body, where they make up only a small proportion of the overall bacterial community. That may reflect the fact breast tissue produces high concentrations of fatty acids, and these bacteria are fatty acid metabolizers.

Led by Reid, director of the Canadian Centre for Human Microbiome and Probiotic Research, researchers collected breast tissue from 81 women. Ten of the women had undergone breast reduction; their breast microbiota served as controls. The remaining women had had benign or cancerous tumours.

Studies of the microbiome in other parts of the body, most notably the gastrointestinal tract, showed changes in bacterial populations can lead to a variety of illnesses – from gastrointestinal conditions (inflammatory bowel disease) to more unexpected ailments (diabetes, obesity, cancer and even neurological conditions).

“When you think about the ‘cancer angle,’ now that we know it’s (bacteria) there, and what’s there, can we modulate the bacteria with probiotics? For women at risk for cancer, we know the bacteria is there, so can we can give it that extra push?” Urbaniak said. “These are questions that weren’t asked until what we discovered.”

Future studies will examine the new questions raised by these findings: How is breast microbiome established? Why don’t infections accompany colonization, despite the fact that some of these bacteria cause infections elsewhere in the body? What impact do these organisms have on the host? Can external factors such as diet, antibiotics and illness affect this bacterial community? What consequences does all this have for women and their children?

The final version of the article is scheduled for the May 2014 issue of Applied and Environmental Microbiology.