Understanding the Effects of Arrabidaea chica on Inflammatory Signaling Pathways

Objectives: Oral mucositis is the painful inflammation and ulceration of oral tissues as a side-effect of aggressive cancer therapies such as radiotherapy or chemotherapy. Activation of the innate immune response by bacterial PAMPs is an important component in the initiation and severity of mucositis. Currently there is no treatment or cure for mucositis and the only relief available to patients is pain management. Arrabidaea chica, popularly known as Crajiru, has been traditionally used as wound healing agent for its anti-inflammatory properties. These properties can be utilized in the treatment of oral mucositis. The aim of this study is to investigate the anti-inflammatory effects and underlying cell signaling transduction of A. chica extract in lipopolysaccharide (LPS) stimulated oral fibroblast.
Methods: Human gingival fibroblasts (HGF-1, ATCC CRL-2014) were cultured in DMEM-5% FBS media at 37^oC in 5% CO₂. The cytotoxicity of A. chica extract on HGF-1 was determined by 24-hour exposure of cells seeded in 24-well plate (1*10^5-cells/mL) at concentrations from 0.025-250μg/mL. CellTiter-Blue cell viability assays were then performed to determine the LD50. HGF-1 were exposed to stimulating concentrations of LPS with or without A. chica extract. Sample supernatants were collected from samples at 0, 3, and 6-hour time points. Cytokine production was determined by Luminex analysis of the supernatants.
Results: Viability assays determined that A. chica extract is not toxic to HGF cells in low concentrations (LD50= 9.316μg/mL). Luminex assays indicated that cells exposed to A. chica extract expressed lower amounts of pro-inflammatory cytokines IL-6 (58% decrease) and IL-8 (67.7% decrease) when exposed to LPS than cells without extract. Cells exposed to A. chica extract also expressed higher amounts of anti-inflammatory cytokine IL-10 (60.0% increase).
Conclusions: Arrabidaea chica extract inhibits pro-inflammatory cytokine expression and promotes anti-inflammatory cytokine expression in human gingival fibroblasts after exposure to LPS and this data suggests that Arrabidaea chica extract may be a potential anti-inflammatory agent.