Smoking Modifies the Genetic Risk for Early-Onset Periodontitis

Area of Science:

• Genetics and Periodontology
• Gene-Environment Interactions
• Oral Health Research

Background:

• Early-onset periodontitis is a severe destructive disease affecting adolescents and young adults.
• Genetic susceptibility and smoking are known risk factors, but their combined effect is not well understood.
• Understanding gene-smoking interactions is crucial for identifying disease mechanisms and potential interventions.

Purpose of the Study:

• To identify genetic variants associated with early-onset periodontitis that are influenced by tobacco smoke exposure.
• To investigate the direct impact of tobacco smoke on the expression of genes implicated in periodontitis.
• To elucidate the gene-smoking interaction in the context of severe alveolar bone destruction.

Main Methods:

• Genome-wide association study (GWAS) analyzing 79,780,573 common variants in 741 individuals with early-onset periodontitis.
• Case-only logistic regression analysis comparing never versus ever smokers to identify gene-smoking interactions.
• In vitro study exposing primary gingival fibroblasts to cigarette smoke extract to quantify gene expression changes via reverse transcription polymerase chain reaction.

Main Results:

• Identified 16 loci associated with increased early-onset periodontitis risk when interacting with smoking (P < 5 × 10^-5).
• Found genome-wide significant cis expression quantitative trait loci for ST8SIA1 and SOST, suggesting their causal role in tobacco-related periodontitis.
• Demonstrated that cigarette smoke extract significantly altered the expression of SSH1 and ST8SIA1, genes involved in immune response and bone homeostasis.

Conclusions:

• Genetic predisposition to early-onset periodontitis is partly triggered by smoking.
• Tobacco smoke directly modulates the expression of key genes involved in bone homeostasis, tissue repair, and immune responses.
• This study reveals a significant gene-environment interaction, where smoking exacerbates genetic susceptibility to severe periodontitis.