Neonatal enteropathogenic Escherichia coli infection disrupts microbiota-gut-brain axis signaling
BackgroundDiarrheal diseases are a leading cause of death in children under age five worldwide. Repeated early life exposures to diarrheal pathogens can result in co-morbidities including stunted growth and cognitive deficits suggesting an impairment in the microbiota-gut-brain (MGB) axis. MethodsNeonatal C57BL/6 mice were infected with EPEC (strain e2348/69; {Delta}escV [T3SS mutant]), or vehicle (LB broth) via orogastric gavage (105 CFU) at post-natal day (P7). Behavior (novel object recognition [NOR] task, light/dark [L/D] box, and open field test [OFT]), intestinal physiology (Ussing chambers), and the microbiota (16S Illumina sequencing) were assessed in adulthood (6-8 weeks). ResultsNeonatal infection of mice with EPEC impaired recognition memory (NOR task), coupled with increased neurogenesis (Ki67 and doublecortin immunostaining) and neuroinflammation (increased microglia activation [Iba1]) in adulthood. Intestinal pathophysiology was characterized by increased secretory state (short circuit current; Isc) and permeability (conductance; FITC-dextran flux) in the ileum and colon of neonatally EPEC-infected mice, along with increased expression of pro-inflammatory cytokines (Tnf, Il12, Il6) and pattern recognition receptors (Nlr, Tlr). Finally, neonatal EPEC infection caused significant dysbiosis of the gut microbiota, including decreased Firmicutes, in adulthood. ConclusionsTogether these findings demonstrate that infection in early life can significantly impair the MGB axis in adulthood.