Lactococcus lactis CNCM I-5388 versus NCDO2118 by its GABA hyperproduction ability, counteracts faster stress-induced intestinal hypersensitivity in rats

Irritable bowel syndrome (IBS) is a functional gastrointestinal disorder characterized by its main symptom, visceral hypersensitivity (VH), which is aggravated by stress. Gut-brain interactions and gut bacteria may alleviate IBS symptoms, including VH. γ-amino butyric acid (GABA), produced notably by lactic acid bacteria (LAB), shows promising result in IBS symptoms treatment. In bacteria, GABA is generated through glutamate decarboxylase (GAD) metabolism of L-glutamic acid, maintaining intracellular pH. In mammals, GABA acts as an inhibitory neurotransmitter, modulating pain, stress, and anxiety. Therefore, utilizing GABA-producing LAB as a therapeutic approach might be beneficial. Our previous work showed that a GABA-producing Lactococcus lactis strain, NCDO2118, reduced VH induced by acute stress in rats after a 10-day oral treatment. Here, we identified the strain CNCM I-5388, with a four-fold higher GABA production rate under the same conditions as NCDO2118. Both strains shared 99.1% identical GAD amino acid sequences and in vitro analyses revealed the same optimal pH for GAD activity; however, CNCM I-5388 exhibited 17 times higher intracellular GAD activity and increased resistance to acidic pH. Additionally, in vivo experiments have demonstrated that CNCM I-5388 has faster anti-VH properties in rats compared with NCDO2118, starting from the fifth day of treatment. Finally, CNCM I-5388 anti-VH effects partially persisted after 5-day treatment interruption and after a single oral treatment. These findings highlight CNCM I-5388 as a potential therapeutic agent for managing VH in IBS patients.

Automated selection of changepoints using empirical P-values and trimming

OBJECTIVES

One challenge that arises when analyzing mobile health (mHealth) data is that updates to the proprietary algorithms that process these data can change apparent patterns. Since the timings of these updates are not publicized, an analytic approach is necessary to determine whether changes in mHealth data are due to lifestyle behaviors or algorithmic updates. Existing methods for identifying changepoints do not consider multiple types of changepoints, may require prespecifying the number of changepoints, and often involve nonintuitive parameters. We propose a novel approach, Automated Selection of Changepoints using Empirical P-values and Trimming (ASCEPT), to select an optimal set of changepoints in mHealth data.

MATERIALS AND METHODS

ASCEPT involves 2 stages: (1) identification of a statistically significant set of changepoints from sequential iterations of a changepoint detection algorithm; and (2) trimming changepoints within linear and seasonal trends. ASCEPT is available at https://github.com/matthewquinn1/changepointSelect.

RESULTS

We demonstrate ASCEPT's utility using real-world mHealth data collected through the Precision VISSTA study. We also demonstrate that ASCEPT outperforms a comparable method, circular binary segmentation, and illustrate the impact when adjusting for changepoints in downstream analysis.

DISCUSSION

ASCEPT offers a practical approach for identifying changepoints in mHealth data that result from algorithmic updates. ASCEPT's only required parameters are a significance level and goodness-of-fit threshold, offering a more intuitive option compared to other approaches.

CONCLUSION

ASCEPT provides an intuitive and useful way to identify which changepoints in mHealth data are likely the result of updates to the underlying algorithms that process the data.

Lactococcus lactis NCDO2118 exerts visceral antinociceptive properties in rat via GABA production in the gastro-intestinal tract

Gut disorders associated to irritable bowel syndrome (IBS) are combined with anxiety and depression. Evidence suggests that microbially produced neuroactive molecules, like γ-aminobutyric acid (GABA), can modulate the gut-brain axis. Two natural strains of Lactococcus lactis and one mutant were characterized in vitro for their GABA production and tested in vivo in rat by oral gavage for their antinociceptive properties. L. lactis NCDO2118 significantly reduced visceral hypersensitivity induced by stress due to its glutamate decarboxylase (GAD) activity. L. lactis NCDO2727 with similar genes for GABA metabolism but no detectable GAD activity had no in vivo effect, as well as the NCDO2118 ΔgadB mutant. The antinociceptive effect observed for the NCDO2118 strain was mediated by the production of GABA in the gastro-intestinal tract and blocked by GABA_B receptor antagonist. Only minor changes in the faecal microbiota composition were observed after the L. lactis NCDO2118 treatment. These findings reveal the crucial role of the microbial GAD activity of L. lactis NCDO2118 to deliver GABA into the gastro-intestinal tract for exerting antinociceptive properties in vivo and open avenues for this GRAS (Generally Recognized As safe) bacterium in the management of visceral pain and anxious profile of IBS patients.