Bifidobacterium longum inhibits Aggregatibacter actinomycetemcomitans- associated gingival epithelial ferroptosis and protects cellular junctions.

BACKGROUND

Periodontal pathogens disrupt the gingival epithelial barrier, but the molecular links among junctional damage, ferroptosis, and inflammation remain unclear.

OBJECTIVE

To investigate whether Bifidobacterium longum (BL) counteracts Aggregatibacter actinomycetemcomitans (Aa)-induced junctional injury via regulation of ferroptosis in human gingival epithelial cells (HGECs).

DESIGN

Oral microbiota differences between periodontitis patients and healthy controls were analyzed using 16S rRNA sequencing, combined with GSE16134 bioinformatics analysis. HGECs were exposed to Aa (1 × 10⁴ CFU/ml) and treated with BL (1 × 10⁸ CFU/ml) or ferrostatin-1 (Fer-1, 2 μM). Cell viability, mitochondrial morphology, ROS, junction proteins (CDH1, CLDN1), ferroptosis markers (SLC7A11, GPX4, NFE2L2), and inflammatory cytokines (IL-6, IL-10, TNF) were assessed.

RESULTS

Bioinformatics revealed enrichment of junction-related pathways associated with ferroptosis. Aa induced mitochondrial damage, ROS accumulation, suppression of ferroptosis-protective signaling and junction proteins, and pro-inflammatory cytokine imbalance. BL significantly restored mitochondrial integrity, ferroptosis-related signaling, epithelial junctions, and inflammatory homeostasis, with effects comparable to or exceeding Fer-1.

CONCLUSION

Aa disrupts gingival epithelial integrity through ferroptosis-mediated oxidative and inflammatory damage. BL effectively suppresses this cascade and protects epithelial junctions, highlighting its therapeutic potential for periodontitis.