Clever bacteria A recent intriguing finding from the Human microbiome Project is that babies born through Caesarean sections apparently miss out on acquiring their mothers' microbiota.
“The birth canal is very heavily colonized by bacteria,” said Maria Dominguez-Bello, a University of Puerto Rico biologist who has been studying microbiota around the world, including in isolated tribes in the Amazon. “We think that is not by chance.” The interaction between the microbiota and the immune system may also play a role in other diseases in adults, including those caused at least in part by chronic inflammation from hyperactive immune systems. “Gut bacteria have figured out a way to network with our immune system so it doesn’t attack them,” said Sarkis Mazmanian of the California Institute of Technology. The microbiota apparently sends signals that dampen the “inflammatory response,” a crucial defense also believed to play a role in a variety of diseases, including many forms of cancer, the “metabolic syndrome” caused by obesity, diabetes and heart disease. The theory is that one reason some people may be prone to these diseases is that they are missing certain microbes. One anti-inflammatory compound produced by a bacterium appears to cure the equivalent of colitis and multiple sclerosis in mice, both of which are caused by misfiring immune systems, Mazmanian found. Similarly, studies indicate that gut dwellers secrete messengers to cells lining the digestive tract to modulate key hormones, such as leptin and ghrelin, which are players in regulating metabolism, hunger and a sense of fullness.