Inflammatory Pulpal Responses to LPS Repeated Inductions in Rat Molar

Area of Science:

• Dental Pulp Biology
• Inflammation Research
• Animal Models

Background:

• Chronic inflammation, often involving the nuclear factor-κB (NF-κB) pathway, is linked to conditions like sepsis and arthritis.
• Deep caries expose dental pulp to bacterial toxins, mimicking chronic inflammatory stimuli.
• Lipopolysaccharide (LPS) stimulation is a standard model for inducing inflammation.

Purpose of the Study:

• To evaluate the effects of repeated lipopolysaccharide (LPS) or phosphate-buffered saline (PBS) inductions on rat molar pulp.
• To determine if 1-3 inductions cause progressive molecular and histological changes.
• To establish a model for studying chronic pulp inflammation due to recurrent bacterial challenges.

Main Methods:

• Rat upper first molars were exposed and received 1-3 applications of LPS or PBS.
• Pulp tissue was harvested at 6, 24, and 48 hours post-induction.
• Histology and quantitative polymerase chain reaction (qPCR) were used for analysis.

Main Results:

• Gene expression of inflammatory and remodeling markers (e.g., IL6, MMP3, MMP9, DSPP) was significantly altered by repeated LPS/PBS exposure.
• Histological changes intensified with multiple exposures, with no significant difference between LPS and PBS groups.
• An increasing MMP9/DSPP ratio was observed, suggesting potential for tracking pulpal degradation.

Conclusions:

• This study presents a preliminary model for investigating sequential pulp responses to repeated bacterial challenges.
• The findings provide insights into the early molecular and histological dynamics of pulp inflammation.
• Further research is needed to differentiate LPS-specific effects and confirm chronic inflammatory characteristics.