Bromelain inhibits the inflammatory mediators induced by LPS in human dental pulp cells

Objectives: Conventional root canal treatment is the treatment of choice for the irreversible pulpitis caused by bacterial infection. Vital pulp therapy has been proposed as an alternative for management of inflamed dental pulp.
Bromelain is a complex mixture of protease extracted from the fruit or stem of the pineapple. Although the complete molecular mechanism of action of bromelain has not been completely identified, it is widely used as anti-inflammatory, antithrombotic and fibrinolytic affects, anticancer activity and immunomodulatory effects, in addition to being a wound healing and circulatory improvement agent. Here, we examined the effect of bromelain on the expressions of inflammatory mediators induced by LPS in dental pulp cells.
Methods: The effect of bromelain on human dental pulp cell (HDPCs) viability was measured using WST-1 assay. Human dental pulp cells were exposed to LPS or LPS+bromelain, and real-time PCR and Western blot were used to detect interleukin-6, interleukin-8 and tumor necrosis factor-α. To determine the mechanism involved in the response to bromelain, the effect of bromelain on LPS-stimulated NF-κB pathway was examined by western blots.
All experiments were performed in triplicate. Each value represents the mean ± SD. Statistical significance was determined using ANOVA test when compared with control. Differences with P-values <0.05 were considered significant.

Results: LPS induced interleukin-6, interleukin-8 and tumor necrosis factor α expression in dental pulp cells. Bromelain significantly inhibited interleukin-6, interleukin-8 and tumor necrosis factor α in LPS-stimulated dental pulp cells. Bromelain treatment significantly decreased LPS-induced p65 expression and phosphorylation of IκB.
Conclusions: Bromelain inhibited expression of inflammatory mediators in dental pulp cells stimulated with LPS. The inhibitory effect of bromelain on inflammatory cytokines is associated with inhibition of NF-κB pathway. Therefore, bromelain might be a useful candidate as vital pulp therapy.