Fuzi polysaccharides improve immunity in immunosuppressed mouse models by regulating gut microbiota composition

Ran Tu; Cheng Zhou; Wenfeng Huang; Zhengping Feng; Qiufang Zhao; Xiaofei Shi; Langjun Cui; Keke Chen

doi:10.1016/j.heliyon.2023.e18244

Fuzi polysaccharides improve immunity in immunosuppressed mouse models by regulating gut microbiota composition

Heliyon. 2023 Jul 13;9(7):e18244. doi: 10.1016/j.heliyon.2023.e18244. eCollection 2023 Jul.

Authors

Ran Tu¹, Cheng Zhou¹, Wenfeng Huang¹, Zhengping Feng^{2

3}, Qiufang Zhao², Xiaofei Shi², Langjun Cui², Keke Chen⁴

Affiliations

¹ Medical Laboratory of Jingmen People's Hospital, Jingchu University of Technology Affiliated Central Hospital, Jingmen, Hubei, China.
² National Engineering Laboratory for Resource Development of Endangered Crude Drugs in Northwest China, Key Laboratory of Medicinal Resources and Natural Pharmaceutical Chemistry, Ministry of Education, College of Life Sciences, Shaanxi Normal University, Xi'an, Shaanxi, China.
³ Yan'an Hospital of Traditional Chinese Medicine, Yan'an, Shaanxi, China.
⁴ School of Biological and Environmental Engineering, Xi'an University, Xi'an Key Laboratory of Natural Product Development and Anticancer Innovative Drug Research in Qinling, Xi'an, Shaanxi, China.

Abstract

Rationale and objectives: Fuzi, the dried root of Aconitum carmichaelii Debx, is one of the widely used traditional Chinese medicines. Fuzi polysaccharides are considered the most bioactive compounds with immunomodulatory functions, however, the mechanisms have not been evaluated. This study aims to systematically investigate the effects of Fuzi polysaccharides on the gut microbiota and immune function using a mouse model immunosuppressed with cyclophosphamide.

Methods: The short-chain fatty acid levels in cecal contents were measured by gas chromatography-mass spectrometry. The gut microbiota 16S rRNA gene were sequenced by next generation sequencing. The mRNA expression levels of NF-κB, IL-6, TNF-α, iNOS and COX-2 were measured using quantitative real-time polymerase chain reaction. The protein expression of occludin and zonula occludens-1 were analyzed by Western blot. The white blood cells were counted using automated hematology analyzer, and CD4⁺FOXP3⁺/CD4⁺ ratio was measured by flow cytometry.

Results and conclusions: Fuzi polysaccharides had the function of elevating the concentration of acetic acid, propionic acid, isobutyric acid, and n-butyric acid in the cecum. Meanwhile, Fuzi polysaccharides could decrease the relative abundance of Helicobacter, Anaerotruncus, Faecalibacterium, Lachnospira, Erysipelotrichaceae_UCG-003, Mucispirillum, and Mycoplasma, and increase the relative abundance of Rhodospirillales, Ruminococcaceae_UCG-013, Mollicutes_RF39, Ruminococcus_1, Christensenellaceae_R-7_group, and Muribaculaceae in the gut. Furthermore, Fuzi polysaccharides exhibited the function of increasing spleen and thymus indices and number of white blood cells and lymphocytes. Fuzi polysaccharides could reverse the decreased mRNA expression of NF-кB, IL-6, and iNOS, differentiation of CD4⁺FOXP3⁺ regulatory T cells as well as protein expression of occludin and zonula occludens-1 induced by cyclophosphamide. In addition, the mRNA and protein expression of cytokines were significantly correlated with the abundance of gut microbiota under Fuzi polysaccharides treatment. Collectively, the above results demonstrated that Fuzi polysaccharides could regulate inflammatory cytokines and gut microbiota composition of immunosuppressive mice to improve immunity, thereby shedding light on revealing the molecular mechanism of polysaccharides of traditional Chinese medicines in the future.

Keywords: 16S rRNA; Fuzi polysaccharides; Gut microbiota; Immunosuppressive mouse model; Short-chain fatty acids.