Microbe-mediated intestinal NOD2 stimulation improves linear growth of undernourished infant mice.

The intestinal microbiota is known to influence postnatal growth. We previously found that a strain of (strain Lp) buffers the adverse effects of chronic undernutrition on the growth of juvenile germ-free mice. Here, we report that Lp sustains the postnatal growth of malnourished conventional animals and supports both insulin-like growth factor-1 (IGF-1) and insulin production and activity. We have identified cell walls isolated from Lp, as well as muramyl dipeptide and mifamurtide, as sufficient cues to stimulate animal growth despite undernutrition. Further, we found that NOD2 is necessary in intestinal epithelial cells for Lp-mediated IGF-1 production and for postnatal growth promotion in malnourished conventional animals. These findings indicate that, coupled with renutrition, bacteria cell walls or purified NOD2 ligands have the potential to alleviate stunting.