Vitamin D decreases Porphyromonas gingivalis internalized into macrophages by promoting autophagy

Area of Science:

• Cell Biology
• Immunology
• Microbiology

Background:

• Porphyromonas gingivalis is an opportunistic pathogen implicated in periodontitis.
• Macrophages play a crucial role in innate immunity against bacterial infections.
• Autophagy is a cellular process involved in the degradation of intracellular pathogens.

Purpose of the Study:

• To investigate the effect of calcitriol (active vitamin D) on intracellular Porphyromonas gingivalis.
• To determine the role of autophagy in the calcitriol-mediated clearance of Porphyromonas gingivalis.
• To examine the impact of calcitriol on macrophage autophagy.

Main Methods:

• Quantitative RT-PCR and bacterial culture to quantify internalized Porphyromonas gingivalis.
• Western blot assays to assess autophagy markers in macrophages.
• Transmission electron microscopy and confocal laser scanning microscopy to visualize bacterial degradation and autophagosome-lysosome colocalization.

Main Results:

• Calcitriol significantly reduced the number of viable intracellular Porphyromonas gingivalis in a dose-dependent manner.
• Calcitriol enhanced both basal and Porphyromonas gingivalis-induced autophagy in macrophages.
• Calcitriol promoted the colocalization of Porphyromonas gingivalis with autophagosome and lysosome markers, indicating increased bacterial degradation via autophagy.

Conclusions:

• Calcitriol promotes the degradation of intracellular Porphyromonas gingivalis in macrophages.
• The mechanism involves the enhancement of the autophagy pathway, leading to increased colocalization with autophagosomes and lysosomes.
• Calcitriol represents a potential therapeutic agent for managing Porphyromonas gingivalis infections by boosting innate immune responses.