Potential impact of early-life probiotic supplementation on peritoneal macrophage function

Abstract

Clinical and animal trials show that early life probiotic consumption provides health benefits in adult life by modulating the immune response. We tested the effects of early life oral consumption of the probiotic Lactobacillus rhamnosus on the function and phenotype of rat peritoneal cavity cells in a model of induced colitis. For the first month of their lives, rats were either fed with an aqueous probiotic bacteria suspension (LB group) or tap water (control group). When the rats grew to 3 months old, we studied the response of their peritoneal macrophages to autologous fecal bacteria stimulation in vitro, both before and after colitis induction (TNBS 40mg/kg of body mass in 50% ethanol). Compared to the controls, the peritoneal cavity cells of the LB group produced less nitric oxide (NO) and had an increased proportion of CD163+ cells. The rats in the LB group have shown milder symptoms of colitis (shorter length of colon under necrosis, less severe submucosal infiltration, lesser degree of colonic wall thickening), along with a diminished increase of peritoneal proinflammatory CCR7+ cells and blunted NO production in response to stimulation by autologous fecal bacteria. Our results may indicate that early oral probiotic administration attenuates macrophage responses to fecal bacteria, which are the primary cause of tissue inflammation and necrosis in chemically induced colitis models, and that this attenuation may be involved in improving the health of colitic rats.