As people get older there is an increase in levels of tumor necrosis factor and other pro-inflammatory cytokines within the bloodstream and tissues. People who have elevated levels of these molecules are more likely to be frail and perhaps hospitalized. In addition, people with the condition are more likely to suffer from cardiovascular disease. The underlying cause (or causes) of age-associated inflammation have long remained unknown.
To investigate if gut microbes are a trigger, researchers used mice born into germ-free conditions and compared these rodents to mice reared in the normal environment. The germ-free mice did not show an age-related increase or any evidence of bacterial products or pro-inflammatory cytokines in the bloodstream (the conventionally reared mice did, as they grew older). In addition, the specific pathogen free mice lived for longer.
Further studies looking into the relationship between inflammation and the gut microbiome showed that the use of a probiotic, with conventionally reared mice, appeared to delay inflammation and extend the life expectancy of the mice.
These observations
led to the conclusion that reason for the rise in inflammation appears to be due to imbalances in the gut microbes. Studies on older mice showed that the wrong mix of microbes triggers the intestines to become leaky. This, in turn, leads to the release of bacterial metabolites which lead to inflammation as well as impairing the immune function. The new research adds to the growing set of findings of how the
human microbiome affects overall health.
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Commenting on the study, lead researcher Dr. Dawn Bowdish, who works at the Michael G. DeGroote Institute for Infectious Disease Research at McMaster University, discusses
the implications of the research: "We hope that in the future we will be able use drugs or pre- or probiotics to increase the barrier function of the gut to keep the microbes in their place and reduce age-associated inflammation and all the bad things that come with it."
The research has been
published in the journal Cell Host & Microbe. The research paper is titled “Age-Associated Microbial Dysbiosis Promotes Intestinal Permeability, Systemic Inflammation, and Macrophage Dysfunction.”
