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Causal Relationships Between Oral Microbiota and Inflammatory Skin Diseases
Xian Zhang1, Min Rao2, Haibin Wu3
1Department of Dermatology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China.
International Dental Journal
|July 23, 2026
Summary
This study used Mendelian randomization to investigate the causal link between oral bacteria and inflammatory skin diseases. Specific oral bacteria are causally associated with systemic lupus erythematosus, vitiligo, pemphigus, localized scleroderma, and dermatitis herpetiformis.
Area of Science:
- Microbiome research
- Immunodermatology
- Genetics
Background:
- The oral microbiome is increasingly linked to systemic inflammation and immune dysregulation.
- The causal role of specific oral bacteria in inflammatory skin diseases is not well understood.
- Confounding factors and reverse causation complicate observational studies.
Purpose of the Study:
- To assess the causal effects of 43 oral microbiota taxa on the risk of five inflammatory skin diseases.
- To utilize a Mendelian randomization (MR) approach to overcome confounding and reverse causation.
- To investigate the oral microbiome's contribution to cutaneous autoimmunity and inflammation.
Main Methods:
- A two-sample Mendelian randomization (MR) analysis was performed.
- Genetic instruments for oral microbiota were derived from genome-wide association studies.
- Outcome data for five inflammatory skin diseases were obtained from the FinnGen consortium.
- Inverse-variance weighted method was the primary analysis, supported by sensitivity analyses for pleiotropy, heterogeneity, and reverse causality.
Main Results:
- Several putative causal associations between oral microbiota and inflammatory skin diseases were identified.
- Genus Granulicatella and Streptococcus species were linked to systemic lupus erythematosus.
- Family Lachnospiraceae_[XIV] and Rothia species were associated with vitiligo.
- Five oral taxa were causally associated with pemphigus.
- Actinomyces species micronuciformis was linked to localized scleroderma.
- Fusobacteriales and Neisseria species were associated with dermatitis herpetiformis.
- Sensitivity analyses detected no significant heterogeneity or horizontal pleiotropy.
Conclusions:
- This MR study provides genetic evidence for a causal role of specific oral bacteria in inflammatory skin diseases.
- The oral microbiome is highlighted as a potential contributor to cutaneous autoimmunity and inflammation.
- Findings suggest the oral microbiome as a target for future mechanistic and clinical investigations in managing inflammatory skin diseases.
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