Porphyromonas gingivalis Lysate Induces TLR-2/4-Dependent NF-κB Activation and Inflammatory Damage in the Human Placental Barrier

Periodontitis has been associated with adverse pregnancy outcomes, but the effect of oral pathogens on placental tissue and local immunity remains unclear. In this study, we investigated the response of human placental explants (HPEs) to lysates of Porphyromonas (P.) gingivalis, a keystone periodontal pathogen. Exposure to P. gingivalis induced significant histological damage and extracellular matrix degradation in placental tissue. The lysate activated the canonical NF-κB pathway, as demonstrated by increased phosphorylation of IκBα, particularly in the trophoblast. This activation was predominantly mediated by Toll-like receptor 2 (TLR-2), with partial contribution from TLR-4. Notably, TLR-2 protein levels decreased upon stimulation, while soluble (s) TLR-2 was markedly elevated in culture supernatants, suggesting receptor cleavage as a regulatory mechanism. P. gingivalis also triggered a robust proinflammatory cytokine secretion, including IL-1β, IL-6, IL-8, and TNF-α, with variable dependence on TLR-2 and TLR-4 signaling. These findings reveal that P. gingivalis components elicit a complex innate immune response in the placenta, driven by TLR-mediated NF-κB activation and modulated by sTLR-2. This study provides mechanistic insight into how periodontitis may contribute to placental inflammation and highlights potential pathways linking maternal oral health to pregnancy complications.