A long-term goal of gut microbiota research is to find a method of normalizing the microbiota early in life and sustaining it though the lifespan. Researchers from Alabama, USA, have found a method of doing this in mice. They found that cross-fostering — giving pups to a nursing non-birth mother — permanently shifted the pups’ microbiota composition.
The study examined two strains of mice: non-obese diabetic (NOD) and non-obese diabetic-resistant (NOR). In litters of newborn pups, half were given to a mother of the opposite strain and half stayed with the birth mother.
The nursing mother, not the birth mother, determined the fecal microbiota composition of the offspring. This was true both at weaning and at 32 weeks of age. Although the microbiota shifted with age, it remained similar to the nursing mother.
The shift in microbiota also had a functional impact on the young mice. Male NOD mice fostered by NOR mothers showed a decreased incidence of type 1 diabetes at 32 weeks: researchers observed no cases of diabetes in male NOD mice nursed by NOR mothers, and an 80% disease incidence in male NOD mice nursed by NOD mothers.
They concluded that cross-fostering is an effective means of inducing an early and sustained shift in the commensal microbiota of mice.
Authors discussed applicability of this research to humans. They advised caution in considering the positive health benefits of the microbiota shift, as they did not determine whether the microbiota of the fostered pups introduced susceptibility to other diseases.
Generalizability of this method will become clearer in the future; previous studies of this kind have reported that the foster mothers sometimes reject the new pups. Study co-author Robin Lorenz told GMFH editors, “We did not have any problems – but we did make sure to put our gloved hands into the bedding (to get rid of the glove smell) before we touched the pups to transfer them, and we did make sure the transfer was within 48 hours of birth.”
Daft, JG, et al. (2015) Cross-fostering immediately after birth induces a permanent microbiota shift that is shaped by the nursing mother. Microbiome doi:10.1186/s40168-015-0080-y