Scientists have found that short chain fatty acids (SCFAs), a product of gut bacteria, may protect the kidneys from acute kidney injury (AKI), a condition with high mortality rates that can also lead to other very serious kidney diseases. AKI is often caused by something called ischemia reperfusion injury, an injury resulting from a loss of oxygen to the tissue (ischemia) and a rush of blood back to the site (reperfusion). This instigates a cascade of events resulting in several immune cell populations accumulating at the site of the injury, causing inflammation and kidney damage.
Because AKI is a result of inflammation and because SCFAs are known to have anti-inflammatory effects, scientists in Brazil hypothesized that treatment with SCFAs could ameliorate kidney function. The results published in the Journal of the American Society of Nephrology were the first to show the protective role of SCFAs in kidney ischemia reperfusion injury (IRI). They found that when the three main SCFAs (acetate, propionate, and butyrate) were administered to mice undergoing this IRI injury, they protected the kidney from undergoing AKI. As suspected, the SCFAs prevented an autoimmune response which resulted in less inflammation and apoptosis (cell death).
Acetate was the SCFA that was most protective to the kidney, so in another experiment the scientists administered acetate-producing bacteria to the mice. Bifidobacterium adolescentis and Bifidobacterium longum were administered separately and each did produce acetate, as evidenced by increased acetate levels in the mice's feces. They found that these mice were protected from kidney IRI and therefore the bacteria were effective. They did note, though, that it is unlikely the bacteria colonized the gut, so further investigation is needed.
This study provides another example of probiotics preventing conditions that may have resulted in serious injury and even death. The bacteria in this study are already used in probiotics to treat other diseases, and so repurposing them for kidney disease should be possible. The study also describes the anti-inflammatory effects of SCFAs, which we have written extensively about in this blog.