Modulation of the Gut Microbiota and Liver Transcriptome by Red Yeast Rice and Monascus Pigment Fermented by Purple Monascus SHM1105 in Rats Fed with a High-Fat Diet

Abstract

Hyperlipidemia can easily cause atherosclerosis and induce cardiovascular and cerebrovascular diseases. Red yeast rice (RYR) contains a variety of active ingredients and is commonly used as medicine and food, and has pharmacological effects such as lowering blood lipids. In this study, we select Monascus strain SHM1105 with a high yield of Monacolin K and monascus pigment (PIG), and studied the effects of the RYR and PIG fermented by this strain on blood lipids, intestinal flora, and liver transcriptome in hyperlipidemia model rats. The experimental results show that, compared with the high-fat model group, the weight growth rate, liver weight ratio, kidney weight ratio, spleen weight ratio, and fat weight ratio of rats in the gavage lovastatin (LOV), RYR, and PIG group were all significantly decreased (p < 0.05). Intervention with RYR and PIG can significantly reduce the serum TC, TG, and LDL-C levels, which has the effect of lowering blood lipids. The 16SrDNA sequencing results showed that the ratio of Firmicutes/Bacteroidetes decreased significantly (p ≤ 0.01) after the intervention of LOV, RYR, and PIG; the abundance of the ratio of Lachnospiraceae, Ruminococcaceae, Prevotellaceae, and Bacteroidales-S24-7-group also changed. The combined analysis of transcriptome and metabolome showed that lovastatin, RYR, and PIG can all improve lipid metabolism in rats by regulating Steroid hormone biosynthesis, Glycerolipid metabolism, and the Arachidonic acid metabolism pathway. In addition, RYR and PIG also have a unique way of regulating blood lipids. Although a lot of research on the lipid-lowering components of Monascus rice and the single pigment component of Monascus has been carried out, the actual application is RYR and pigments as mixtures, as a mixture of RYR and PIG contains a variety of biologically active ingredients, and each component may have a synergistic effect. Hence it has a lipid-lowering mechanism that lovastatin does not have. Therefore, RYR and PIG are effective in reducing lipid potential development and can be utilized in functional foods.

Keywords: RNA-seq; hyperlipidaemia; intestinal flora; pigment; red yeast rice.

FIGURE 1

Determination results of body mass and viscera quality of different groups of rats (n = 8). Note: Compared with CK group, “#” means significant difference (p < 0.05), “##” means extremely significant difference (p < 0.01); Compared with HFS group, “*” showed significant difference (p < 0.05), and “**” showed extremely significant difference (p < 0.01), the same as below.

FIGURE 2

Determination results of blood lipid indexes of different groups of rats (n = 8).

FIGURE 3

Metabolic (A) and Gene (B) profile of the CK, HFS, LOV, RYR, and PIG groups visualized by principal component analysis (PCA) (n = 3).

FIGURE 4

A) Statistical histogram of differential genes between samples; (B) Statistical histogram of differential metabolites (In (A) and (B), the x-coordinate is samples compared in pairs, and the vertical table is the number of differentially expressed genes or metabolites; Green and red represent differentially expressed genes or metabolites that are down-regulated and up-regulated, respectively); (C) Venn diagram showing the differentially expressed genes shared by the mice from each group; (D) Venn diagram showing the differentially expressed metabolites shared by the mice from each group (n = 3).

FIGURE 5

Changes in metabolites and genes in metabolic pathways (The red circles indicate the metabolites with up-regulated abundance, the green circles indicate the metabolites with down-regulated abundance, the red boxes indicate genes whose expression levels are up-regulated, and the green boxes indicate genes whose expression levels are down-regulated).

FIGURE 6

Differential metabolites and differential gene expression statistics histogram (n = 3).

FIGURE 7

Effects of HFS, LOV, RYR, and PIG on mRNA expression in liver-related genes of hyperlipidemic rats (n = 3). (A) phosphatidate phosphatase LPIN; (B) CYP2C; (C) sPLA2; (D) CYP7A1. The mRNA levels of the CK group were used as the reference value. Data were expressed as the relative mRNA level for each gene and represented as the mean ± SD (n = 3).

FIGURE 8

Composition of the gut microbiota (n = 3). (A) Gut microbiota composition at the phylum level. (B) Gut microbiota composition at the family level. (C) F/B ratio (Firmicutes/Bacteroides). (D) Community abundance on phylum level.

FIGURE 9

Heat map of the correlation between metabolites and intestinal bacteria (n = 3). (A) shows a heat map of intestinal bacteria and differential metabolites at the phylum level, and (B) shows a heat map of intestinal bacteria and differential metabolites at the family level. The horizontal axis is intestinal bacteria, and the vertical axis is metabolites. Each grid represents the correlation coefficient between intestinal bacteria and metabolites. The color changes from white to red, indicating the positive correlation is from weak to strong; from white to blue indicates the negative correlation is from weak to strong. “*” means significant correlation (p < 0.05); “**” means extremely significant correlation (p < 0.01).