Immunostimulatory activity of hydrolyzed and fermented Platycodon grandiflorum extract occurs via the MAPK and NF-κB signaling pathway in RAW 264.7 cells

Jae In Jung; Hyun Sook Lee; So Mi Kim; Soyeon Kim; Jihoon Lim; Moonjea Woo; Eun Ji Kim

doi:10.4162/nrp.2022.16.6.685

Immunostimulatory activity of hydrolyzed and fermented Platycodon grandiflorum extract occurs via the MAPK and NF-κB signaling pathway in RAW 264.7 cells

Nutr Res Pract. 2022 Dec;16(6):685-699. doi: 10.4162/nrp.2022.16.6.685. Epub 2022 Apr 21.

Authors

Jae In Jung¹, Hyun Sook Lee², So Mi Kim¹, Soyeon Kim³, Jihoon Lim³, Moonjea Woo³, Eun Ji Kim¹

Affiliations

¹ Regional Strategic Industry Innovation Center, Hallym University, Chuncheon 24252, Korea.
² Department of Food Science & Nutrition, Dongseo University, Busan 47011, Korea.
³ R&D Center, World Food Services Co. Ltd., Gangneung 25451, Korea.

Abstract

Background/objectives: Platycodon grandiflorum (PG) has long been known as a medicinal herb effective in various diseases, including bronchitis and asthma, but is still more widely used for food. Fermentation methods are being applied to increase the pharmacological composition of PG extracts and commercialize them with high added value. This study examines the hydrolyzed and fermented PG extract (HFPGE) fermented with Lactobacillus casei in RAW 264.7 cells, and investigates the effect of amplifying the immune and the probable molecular mechanism.

Materials/methods: HFPGE's total phenolic, flavonoid, saponin, and platycodin D contents were analyzed by colorimetric analysis or high-performance liquid chromatography. Cell viability was measured by the MTT assay. Phagocytic activity was analyzed by a phagocytosis assay kit, nitric oxide (NO) production by a Griess reagent system, and cytokines by enzyme-linked immunosorbent assay kits. The mRNA expressions of inducible nitric oxide synthase (iNOS) and cytokines were analyzed by reverse transcription-polymerase chain reaction, whereas MAPK and nuclear factor (NF)-κB activation were analyzed by Western blots.

Results: Compared to PGE, HFPGE was determined to contain 13.76 times and 6.69 times higher contents of crude saponin and platycodin D, respectively. HFPGE promoted cell proliferation and phagocytosis in RAW 264.7 cells and regulated the NO production and iNOS expression. Treatment with HFPGE also resulted in increased production of interleukin (IL)-1β, IL-6, tumor necrosis factor (TNF)-α, C-X-C motif chemokine ligand10, granulocyte-colony-stimulating factor, granulocyte-macrophage colony-stimulating factor, and monocyte chemoattractant protein-1, and the mRNA expressions of these cytokines. HFPGE also resulted in significantly increasing the phosphorylation of NF-κB p65, extracellular signal-regulated kinase, and c-Jun N-terminal kinase.

Conclusions: Taken together, our results imply that fermentation and hydrolysis result in the extraction of more active ingredients of PG. Furthermore, we determined that HFPGE exerts immunostimulatory activity via the MAPK and NF-κB signaling pathways.

Keywords: NF-κB; Platycodon grandiflorum; chemokines; cytokines; immunostimulation.