Nonsaponin fraction of Korean Red Ginseng attenuates cytokine production via inhibition of TLR4 expression

Huijeong Ahn; Byung-Cheol Han; Jeongeun Kim; Seung Goo Kang; Pyeung-Hyeun Kim; Kyoung Hwa Jang; Seung Ho So; Seung-Ho Lee; Geun-Shik Lee

doi:10.1016/j.jgr.2018.03.003

Nonsaponin fraction of Korean Red Ginseng attenuates cytokine production via inhibition of TLR4 expression

J Ginseng Res. 2019 Apr;43(2):291-299. doi: 10.1016/j.jgr.2018.03.003. Epub 2018 Apr 4.

Authors

Huijeong Ahn¹, Byung-Cheol Han^{1

2}, Jeongeun Kim¹, Seung Goo Kang³, Pyeung-Hyeun Kim⁴, Kyoung Hwa Jang², Seung Ho So², Seung-Ho Lee², Geun-Shik Lee¹

Affiliations

¹ College of Veterinary Medicine and Institute of Veterinary Science, Kangwon National University, Chuncheon, Republic of Korea.
² Korea Ginseng Research Institute, Korea Ginseng Corporation, Daejeon, Republic of Korea.
³ Division of Biomedical Convergence, College of Biomedical Science, Kangwon National University, Chuncheon, Republic of Korea.
⁴ Department of Molecular Bioscience, School of Biomedical Science, Kangwon National University, Chuncheon, Republic of Korea.

Abstract

Background: Ginsenosides of Korean Red Ginseng extracts (RGE) and its saponin components suppress secretion of inflammasome-mediating cytokines, whereas the nonsaponin fraction (NS) of RGE oppositely stimulates cytokine secretion. Although direct exposure of NS to macrophages in mice induces cytokine production, oral administration of NS has not been studied in inflammasome-related disease in animal models.

Methods: Mice were fed RGE or NS for 7 days and then developed peritonitis. Peritoneal cytokines were measured, and peritoneal exudate cells (PECs) were collected to assay expression levels of a set of toll-like receptors (TLRs) and cytokines in response to NS ingestion. In addition, the role of intestinal bacteria in NS-fed mice was assessed. The effect of preexposure to NS in bone marrow-derived macrophages (BMDMs) on cytokine production was further confirmed.

Results: NS ingestion attenuated secretion of peritoneal cytokines resulting from peritonitis. In addition, the isolated PECs from NS-fed mice presented lower TLR transcription levels than PECs from control diet-fed mice. BMDMs treated with NS showed downregulation of TLR4 mRNA and protein expression, which was mediated by the TLR4-MyD88-NFκB signal pathway. BMDMs pretreated with NS produced less cytokines in response to TLR4 ligands.

Conclusion: NS administration directly inhibits TLR4 expression in inflammatory cells such as macrophages, thereby reducing secretion of cytokines during peritonitis.

Keywords: Alum, aluminum potassium sulfate; BMDMs, bone marrow–derived macrophages; Cytokine; HKST, heat-killed Salmonella typhimurium; IL, interleukin; Korean Red Ginseng extracts; LB, Luria-Bertani; LCCM, L929 cell-conditioned medium; LPS, lipopolysaccharide; Lys, lysate; MSU, monosodium urate crystal; NF-kB, nuclear factor kappa-light-chain-enhancer of activated B cells; NLRP3, (NOD)2-like receptor protein 3; NOD, nucleotide-binding and oligomerization domain; NS, nonsaponin fraction; Non, nontreatment; Nonsaponin fraction; PECs, peritoneal exudate cells; Peritonitis; RGE, Korean Red Ginseng extracts; SF, saponin fraction; Sup, supernatant; TLR4; TLRs, toll-like receptors; ip, intraperitoneally.