Modulatory effects of bromelain on dual-species oral biofilm formation and quorum sensing–associated inflammatory responses in human cell lines

Dental caries and periodontitis are driven by QS-regulated oral biofilms formed by Streptococcus mutans (S. mutans) and Staphylococcus aureus (S. aureus), which promote inflammation via NF-κB and TRPV1 signaling, Bromelain, a proteolytic enzyme derived from pineapple, has been reported to possess antibiofilm, QS-inhibitory, and anti-inflammatory properties, making it a promising natural therapeutic candidate. To date, no studies have examined the dual role of bromelain in disrupting oral biofilm formation and QS while simultaneously modulating TRPV1-mediated inflammatory responses in human cell models. Thus, this study aimed to evaluate the effects of ultrafiltered bromelain (UFB) on dual-species oral biofilm formation, QS regulation, and biofilm-induced inflammatory responses in human cell lines. Bromelain was extracted, purified, and characterized by SDS-PAGE, HPLC, Bradford assay and UV–Vis spectrophotometry. Dual-species biofilms of S. mutans and S. aureus were developed and validated using crystal violet staining, colony counting, and scanning electron microscopy (SEM). The co-culture of dual-species biofilms with HaCaT and HGF cells was established to examine cytotoxicity and inflammatory responses. Biofilm inhibition and disruption were assessed by crystal violet assays, microscopy, and SEM, while QS modulation was evaluated by qPCR targeting comC, comDE, and gtfC in S. mutans, and agrD, agrA, agrC, and RNAIII in S. aureus