An in vitro anti-inflammatory effect of Thai propolis in human dental pulp cells

• Published in: Journal of applied oral science Vol. 31; p. e20230006
• Main Authors: Kantrong, Nutthapong, Kumtawee, Jittranut, Damrongrungruang, Teerasak, Puasiri, Subin, Makeudom, Anupong, Krisanaprakornkit, Suttichai, Chailertvanitkul, Pattama
• Format: Journal Article
• Language: English
• Published: Brazil Faculdade De Odontologia De Bauru - USP 01-01-2023; University of São Paulo
• Subjects: Cyclooxygenase-2; Dental pulp cells; DENTISTRY, ORAL SURGERY & MEDICINE; Interleukin-1; Original; Propolis; Prostaglandin E2; Prostaglandin E2; Interleukin-1; Cyclooxygenase-2; Dental pulp cells; Propolis
• ISSN: 1678-7757; 1678-7765; 1678-7765
• DOI: 10.1590/1678-7757-2023-0006

To explore the potential for development of Thai propolis extract as a pulp capping agent to suppress pulpal inflammation from dental pulp infections. This study aimed to examine the anti-inflammatory effect of the propolis extract on the arachidonic acid pathway, activated by interleukin (IL)-1β, in cultured human dental pulp cells.
Dental pulp cells, isolated from three freshly extracted third molars, were first characterized for their mesenchymal origin and treated with 10 ng/ml of IL-1β in the presence or absence of non-toxic concentrations of the extract from 0.08 to 1.25 mg/ml, as determined by the PrestoBlue cytotoxic assay. Total RNA was harvested and analyzed for mRNA expressions of 5-lipoxygenase (5-LOX) and cyclooxygenase-2 (COX-2). Western blot hybridization was performed to investigate COX-2 protein expression. Culture supernatants were assayed for released prostaglandin E2 levels. Immunofluorescence was conducted to determine involvement of nuclear factor-kappaB (NF-kB) in the inhibitory effect of the extract.
Stimulation of the pulp cells with IL-1β resulted in the activation of arachidonic acid metabolism via COX-2, but not 5-LOX. Incubation with various non-toxic concentrations of the propolis extract significantly inhibited upregulated COX-2 mRNA and protein expressions upon treatment with IL-1β (p<0.05), resulting in a significant decrease in elevated PGE2 levels (p<0.05). Nuclear translocation of the p50 and the p65 subunits of NF-kB upon treatment with IL-1β was also blocked by incubation with the extract.
Upregulated COX-2 expression and enhanced PGE2 synthesis upon treatment with IL-1β in human dental pulp cells were suppressed by incubation with non-toxic doses of Thai propolis extract via involvement of the NF-kB activation. This extract could be therapeutically used as a pulp capping material due to its anti-inflammatory properties.