Indole-3-lactic acid, a metabolite of tryptophan, secreted by Bifidobacterium longum subspecies infantis is anti-inflammatory in the immature intestine.

BACKGROUND: Necrotizing enterocolitis (NEC), a necrotic inflammation of the intestine, represents a major health problem in the very premature infant. Although prevention is difficult, the combination of ingestion of maternal-expressed breastmilk in conjunction with a probiotic provides the best protection. In this study, we establish a mechanism for breastmilk/probiotic protection. METHODS: Ultra-high-performance liquid chromatography-tandem mass spectrometry of Bifidobacterium longum subsp. infantis (B. infantis) secretions was used to identify an anti-inflammatory molecule. Indole-3-lactic acid (ILA) was then tested in an established human immature small intestinal cell line, necrotizing colitis enterocytes, and other immature human enteroids for anti-inflammatory effects and to establish developmental function. ILA was also examined in immature and mature enterocytes. RESULTS: We have identified ILA, a metabolite of breastmilk tryptophan, as the anti-inflammatory molecule. This molecule is developmentally functional in immature but not mature intestinal enterocytes; ILA reduces the interleukin-8 (IL-8) response after IL-1ß stimulus. It interacts with the transcription factor aryl hydrocarbon receptor (AHR) and prevents transcription of the inflammatory cytokine IL-8. CONCLUSIONS: This molecule produced by B. infantis (ATCC No. 15697) interaction with ingested breastmilk functions in a complementary manner and could become useful in the treatment of all at-risk premature infants for NEC if safety and clinical studies are performed.

A year-long immune profile of the systemic response in acute stroke survivors.

Stroke is a leading cause of cognitive impairment and dementia, but the mechanisms that underlie post-stroke cognitive decline are not well understood. Stroke produces profound local and systemic immune responses that engage all major innate and adaptive immune compartments. However, whether the systemic immune response to stroke contributes to long-term disability remains ill-defined. We used a single-cell mass cytometry approach to comprehensively and functionally characterize the systemic immune response to stroke in longitudinal blood samples from 24 patients over the course of 1 year and correlated the immune response with changes in cognitive functioning between 90 and 365 days post-stroke. Using elastic net regularized regression modelling, we identified key elements of a robust and prolonged systemic immune response to ischaemic stroke that occurs in three phases: an acute phase (Day 2) characterized by increased signal transducer and activator of transcription 3 (STAT3) signalling responses in innate immune cell types, an intermediate phase (Day 5) characterized by increased cAMP response element-binding protein (CREB) signalling responses in adaptive immune cell types, and a late phase (Day 90) by persistent elevation of neutrophils, and immunoglobulin M+ (IgM+) B cells. By Day 365 there was no detectable difference between these samples and those from an age- and gender-matched patient cohort without stroke. When regressed against the change in the Montreal Cognitive Assessment scores between Days 90 and 365 after stroke, the acute inflammatory phase Elastic Net model correlated with post-stroke cognitive trajectories (r = -0.692, Bonferroni-corrected P = 0.039). The results demonstrate the utility of a deep immune profiling approach with mass cytometry for the identification of clinically relevant immune correlates of long-term cognitive trajectories.