Salivary Microbiome Lipid A Profile in Periodontal Health and Disease

Objectives: Lipopolysaccharide (LPS) is a key microbial stimulus that triggers the host response in periodontal tissues. Lipid A, the bioactive centre of LPS, is considered to be an archetypal microbe-associated molecular pattern (MAMP) molecule. Regulation of lipid A chemical composition is an important, naturally occurring mechanism that drives bacteria-host immune system interactions into either a symbiotic or pathogenic relationship. The objectives of this study were to analyse salivary microbiome lipid A profiles and endotoxin activities in periodontal health and disease.
Methods: Unstimulated, mixed saliva samples were collected from healthy individuals (33) and chronic periodontitis patients (32) before and after non-surgical periodontal therapy. Chemical composition of salivary lipid A moieties was determined by ESI-Mass Spectrometry. Endotoxin activity of salivary LPS extracts was assessed using the recombinant factor C assay and their inflammatory potential was examined in THP-1-derived macrophages by measuring TNF-α and IL-8 production.
Results: Characteristic lipid A molecular signatures, with predominant m/z peaks between 1600-2000 in the positive-ion mode and below 1300 in the negative-ion mode, were observed in diseased samples. Healthy and post-treatment samples were characterized by more evenly spread m/z peaks ranging from 1000-2000. Endotoxin activity levels and inflammatory potentials of post-treatment salivary LPS extracts were significantly higher compared to healthy and diseased samples.
Conclusions: Salivary microbiome lipid A profile and endotoxin activity show significant differences between healthy and diseased patients and may be used for monitoring periodontal health.