Differential Gene Expression of Porphyromonas gingivalis in the Presence or Absence of Xanthohumol and Curcumin in a Dynamic In Vitro Biofilm Model

This study aimed to characterize the transcriptional response of Porphyromonas gingivalis biofilms to treatment with xanthohumol and curcumin. A validated dynamic in vitro biofilm model, based on microbial growth under flow and shear conditions resembling the oral cavity, was used to develop mature biofilms of P. gingivalis on sterile ceramic calcium hydroxyapatite discs. Transcriptional profiles of biofilms, treated and untreated with both extracts, were obtained through RNA-Sequencing (RNA-Seq). The biofilm development and the lack of phenotypic effects from sublethal concentrations of xanthohumol and curcumin were confirmed via Scanning Electron Microscopy (SEM) and Confocal Laser Scanning Microscopy (CLSM). Reverse transcription quantitative PCR (RT-qPCR) was employed to verify differentially expressed genes identified by RNA-Seq. Xanthohumol and curcumin caused extensive reprogramming of P. gingivalis biofilm gene expression. Out of 1,973 genes, xanthohumol activated 173 and repressed 286, whereas curcumin activated 170 and repressed 163. These changes affected genes involved in membrane integrity, oxidative stress, transmembrane transport, and virulence, suggesting a mechanism of action that involves membrane disruption.