Combined intervention with Limosilactobacillus reuteri and Lactobacillus johnsonii improved GDM-associated maternal metabolic and sex-specific placental abnormalities, with links to tryptophan metabolism and aryl hydrocarbon receptor signaling.
Key Findings
Results
Metagenomic sequencing of fecal samples from GDM women revealed reduced abundance of Lactobacillaceae compared to normal pregnant women.
Metagenomic sequencing was performed on fecal samples from both normal and GDM pregnant women
The reduction in Lactobacillaceae family members was identified as a key microbial signal distinguishing GDM from normal pregnancy
This finding guided the selection of Limosilactobacillus reuteri and Lactobacillus johnsonii as candidate probiotic strains
A GDM mouse model was subsequently used to screen and confirm these candidate probiotics
Results
Combined L. reuteri and L. johnsonii intervention improved glycemic control and insulin resistance in GDM mice.
The probiotic intervention was applied to a GDM mouse model established after candidate screening in clinical samples
Improvements were observed in glucose metabolism and insulin resistance following the combined probiotic treatment
These metabolic improvements were part of a broader assessment that also included inflammation and intestinal barrier function
The intervention addressed multiple facets of GDM-associated metabolic abnormalities simultaneously
Results
Probiotic intervention improved colon barrier function and alleviated placental lesions in GDM mice.
The combined probiotic treatment improved intestinal barrier integrity in GDM mice
Placental structural lesions associated with GDM were alleviated following intervention
Both intestinal and placental improvements were assessed as part of the comprehensive intervention evaluation
Improvements in colon barrier function were considered potentially relevant to systemic metabolic and inflammatory changes
Results
GDM-associated placental nutrient transporter expression abnormalities were sex-specific and were normalized by probiotic intervention.
The sex-specific patterns of placental nutrient transporter dysregulation were normalized by combined L. reuteri and L. johnsonii treatment
This finding represents a novel observation linking GDM-associated placental dysfunction to fetal sex
Normalization of these transporters by probiotics suggests a mechanistic link between gut microbiota and placental function
Results
Maternal plasma 5-hydroxyindoleacetic acid (5-HIAA), a tryptophan metabolite, was reduced in GDM mice and restored after probiotic intervention.
5-HIAA levels in maternal plasma were significantly reduced in GDM mice compared to controls
Probiotic intervention with L. reuteri and L. johnsonii restored maternal plasma 5-HIAA levels
5-HIAA levels correlated with metabolic indices, placental status, and fetal growth
5-HIAA restoration was also linked to aryl hydrocarbon receptor (AhR) signaling, suggesting a tryptophan metabolism-AhR axis as a key mechanism
These findings connect gut microbiota composition to tryptophan catabolism and downstream receptor signaling in GDM
Results
Aryl hydrocarbon receptor (AhR) signaling was identified as a mechanistic link between tryptophan metabolism and GDM-associated placental and metabolic abnormalities.
AhR signaling was assessed in the context of tryptophan metabolite changes in GDM mice
Restoration of 5-HIAA by probiotic intervention correlated with changes in AhR signaling
The tryptophan metabolism-AhR signaling pathway was proposed as a key mechanism underlying probiotic effects on placental nutrient transporters
AhR is a ligand-activated transcription factor known to respond to tryptophan-derived metabolites produced by gut bacteria
Methods
The study used a two-stage approach combining clinical metagenomic data with a mouse model to identify and validate candidate probiotics for GDM.
Fecal metagenomic sequencing was performed on clinical samples from normal and GDM pregnant women in the first stage
A GDM mouse model was established for candidate probiotic screening in the second stage
The combined intervention assessed glucose metabolism, inflammation, intestinal barrier integrity, placental structure, nutrient transporter expression, and tryptophan metabolism
This translational design aimed to identify 'potential probiotics using microbial signals from clinical GDM cases and a mouse model'
What This Means
This research suggests that two specific probiotic bacteria — Limosilactobacillus reuteri and Lactobacillus johnsonii — may help address some of the metabolic and placental problems associated with gestational diabetes mellitus (GDM), a common complication of pregnancy. The researchers first analyzed gut bacteria from stool samples of pregnant women with and without GDM, finding that women with GDM had lower levels of a bacterial family called Lactobacillaceae. They then tested these two strains in a mouse model of GDM, where the combined treatment improved blood sugar control, reduced insulin resistance and inflammation, and helped restore the gut's protective lining.
A particularly novel finding was that GDM altered the expression of placental nutrient transporters — proteins that control what nutrients pass from mother to fetus — in ways that differed depending on the sex of the fetus. The probiotic treatment normalized these sex-specific abnormalities. The researchers also found that a metabolite of the amino acid tryptophan, called 5-HIAA, was reduced in GDM mice and restored by the probiotic intervention. Levels of this metabolite correlated with blood sugar control, placental health, and fetal growth, and were linked to a signaling pathway involving the aryl hydrocarbon receptor (AhR), suggesting a biological chain connecting gut bacteria to placental function through tryptophan chemistry.
This research suggests that specific probiotic strains identified through analysis of clinical gut microbiome data may have potential for addressing multiple aspects of GDM, including effects on the placenta that differ based on fetal sex. The connection between gut bacteria, tryptophan metabolism, and placental nutrient transport opens new avenues for understanding how the gut microbiome influences pregnancy outcomes, though further studies in humans would be needed to confirm these findings.
Check Your Own Numbers
Upload your bloodwork. We'll cross-reference your results against this study and 4,700 others.
Wang J, Zhang D, Hu S, Guo H, Zou L, Wang N, et al.. (2026). Limosilactobacillus reuteri and Lactobacillus johnsonii intervention ameliorates gestational diabetes mellitus-associated sex-specific placental nutrient transporter abnormalities: Links with tryptophan metabolism and aryl hydrocarbon receptor signaling.. Diabetes research and clinical practice. https://doi.org/10.1016/j.diabres.2026.113510