Impact of oral flora in tongue coating and saliva on oral cancer risk and the regulatory role of Interleukin-8.

Background: Oral flora and inflammatory factors play a crucial role in oral cancer, but the relationship between them and oral cancer has not been clearly established.

Methods: Oral flora served as exposure factor, oral cancer as outcome factor, and inflammatory factors as mediating factor. Mendelian randomization (MR) analysis was used to analyze the relationship between oral flora and oral cancer, and the potential mediating effect of inflammatory factors was explored through mediation analysis.

Results: 29 kinds of oral flora in tongue coating and 22 kinds of oral flora in saliva were associated with increased risk of oral cancer. 18 species of oral flora in tongue coating and 25 species in saliva were associated with a reduced risk of oral cancer. Interleukin-8 (IL8) played a mediating role in the relationship between oral flora and oral cancer, and it was associated with an increased risk of oral cancer. Granulicatella, Streptococcus mitis, Saccharimonadaceae and Haemophilus in oral flora caused oral cancer indirectly through IL8. IL8 expression increased in oral cancer, which has good diagnostic value. IL8-related genes in oral cancer are closely associated with immune cell infiltration. What's more, IL8 has potential medicinal properties.

Conclusion: Oral flora of tongue coating and saliva is closely related to oral cancer, and IL8 plays a mediating role in the causal relationship between oral flora and oral cancer.