A new understanding of the essential role of gut microbes in the immune system may hold the key to dealing with some of the more significant health problems facing people in the world today, according to a new analysis from Oregon State University.

Problems ranging from autoimmune to clinical depression and obesity may be linked to immune dysfunction that begins with a “failure to communicate” in the human gut, according to the researchers. The new analysis, published in the journal Clinical Reviews in Allergy and Immunology, suggests that health care of the future may include personalised diagnosis of an individual’s “microbiome” to determine what prebiotics or probiotics might provide better balance.

“Asked about their immune system, most people might think of white blood cells, lymph glands or vaccines,” said Dr Natalia Shulzhenko, author of the report and Assistant Professor and Physician in the Oregon State University Department of Biomedical Sciences. “They would be surprised that’s not where most of the action is. Our intestines contain more immune cells than the entire rest of our body,” she said.

“The human gut plays a huge role in immune function,” Dr Shulzhenko said. “This is little appreciated by people who think its only role is digestion. The combined number of genes in the microbiota genome is 150 times larger than the person in which they reside. They do help us digest food, but they do a lot more than that,” she said.

According to the researchers, an emerging theory of disease is a disruption in the “crosstalk” between the microbes in the human gut and other cells involved in the immune system and metabolic processes.

“In a healthy person, these microbes in the gut stimulate the immune system as needed, and it in turn talks back,” Dr Shulzhenko said. “There’s an increasing disruption of these microbes from modern lifestyle, diet, overuse of antibiotics and other issues. With that disruption, the conversation is breaking down,” she said.

Links to range of diseases

An “explosion” of research in the field of genomic sequencing is for the first time allowing scientists to understand some of this conversation between the microbes in the gut and the rest of the body and appreciate its significance, the researchers said.

The results show links that lead to a range of diseases, including coeliac disesase and inflammatory bowel disease. Researchers said obesity may also be related, and there is some evidence of relevance to depression, late-onset autism, allergies, asthma and cancer.

In the new Oregon State University review, researchers analysed how microbe dysfunction can sometimes result in malabsorption and diarrhea, which affects tens of millions of children worldwide and is often cured merely by better nutrition. In contrast, a high-fat diet may cause the gut microbes to quickly adapt to and prefer these foods, leading to increased lipid absorption and weight gain.

Researchers said the chronic inflammation linked to most of the diseases that kill people in the developed world – heart disease, cancer, diabetes – may begin with dysfunctional gut microbiota.

Future therapies may work with microbiotic balance

Understanding these processes is a first step to addressing them, the researchers said. Once scientists have a better idea of what constitutes a ‘healthy’ microbiota in the gut, they may be able to personalise therapies to restore that balance. According to the researchers, it should also be possible to identify and use new types of probiotics to mitigate the impact of antibiotics, when such drugs are necessary and must be used.

Such approaches are “an exciting target for therapeutic interventions” to treat health problems in the future, the researchers said.

The study, supported by Oregon State University, included researchers from both the College of Veterinary Medicine and the College of Pharmacy.

Australian Food News reported earlier in September 2013 that researchers at the Washington University School of Medicine had found that altering the gut microbes in mice could prevent obesity if combined with a ‘healthy’ diet.

Share