Mogroside V ameliorates broiler pulmonary inflammation via modulating lung microbiota and rectifying Th17/Treg dysregulation in lipopolysaccharides-induced lung injury

Abstract

The dysbiosis of lung microbiota and inflammatory factors play a crucial role in the occurrence of lipopolysaccharides (LPS)-induced lung injury. Recently, mogroside V (MGV) has received increasing attention due to its potential health benefits in pneumonia, but its complex mechanism needs further experimental elucidation. In this study, we established an LPS-induced chicken lung injury model to investigate the protective effect of MGV on LPS-induced acute lung injury in broiler and its related mechanisms. A total of 192 one-day-old white-finned broilers were randomly assigned into 4 groups with 6 replicates: 1) control group: basal diet (d 1-44), saline (d 43); 2) LPS group: basal diet (d 1-44), LPS (d 43); 3) MGV group: basal diet + 0.2% MGV (d 1-44), saline (d 43); 4) MGV-LPS group: basal diet + 0.2% MGV (d 1-44), LPS (d 43). The results showed that pathological examination showed that lung tissue inflammation infiltration was reduced after MGV treatment. In addition, MGV can promote the balance of Th17 and Treg cell cytokines, significantly inhibit the expression of proinflammatory cytokines (IL-1β (P < 0.01), IL-6 (P < 0.001), IL-17F (P < 0.05)), and decrease immunosuppressive target expression (PD-L1 (P < 0.01), PD-1 (P < 0.001), RORα (P < 0.001)), activating the immune system. Furthermore, 16S rRNA sequencing analysis showed that MGV treatment could increase the abundance of beneficial bacteria in the lung and reduce the abundance of bacteria associated with inflammation. Generally, MGV intervention has a preventive effect on the pathological damage induced by lipopolysaccharides. Its mechanism is related to inhibiting the inflammatory response, regulating the Th17/Treg balance, and maintaining the stability of lung microbiota.

Keywords: lipopolysaccharides; lung microbiota; mogroside V; pulmonary inflammation.

Figure 1

Mogroside V on the organotypic index and lung morphology of broiler with acute lung injury. (A) Lung index; (B) Bursa of Fabricius index; (C) Spleen index; (D) Representative histological images of lung tissue from control or LPS-challenged broilers stained with hematoxylin and eosin (H&E). (A–C) Data are expressed as the mean ± SEM (n = 6). Long arrow indicates hyperemia in the pulmonary capillary, short arrow indicates inflammatory infiltrates, and triangle indicates collapsed alveolar spaces. CON-Saline: control group; CON-LPS: LPS group; MGV-Saline: MGV group; MGV-LPS: MGV-LPS group. *, P < 0.05.

Figure 2

Effects of dietary mogroside V supplementation on the pulmonary mucosal barrier of broiler with acute lung injury. The mRNA levels of ZO-1 (A), Claudin (B), Occludin (C), MUC1 (D), MUC2 (E) in lung were analyzed by qRT-PCR. Data are expressed as the mean ± SEM (n = 6). CON-Saline: control group; CON-LPS: LPS group; MGV-Saline: MGV group; MGV-LPS: MGV-LPS group. *, P < 0.05, **, P < 0.01.

Figure 3

Effects of dietary mogroside V supplementation on lung inflammation cytokine gene expression of broiler with acute lung injury. The relative expression of IL-1β (A), IL-6 (B), IL-4 (C), IL-8 (D), Caspase1 (E), and TGF-β1 (F) of broiler with acute lung injury was quantified by qRT-PCR. Data are expressed as the mean ± SEM (n = 6). CON-Saline: control group; CON-LPS: LPS group; MGV-Saline: MGV group; MGV-LPS: MGV-LPS group. *, P < 0.05, **, P < 0.01, ***, P < 0.001.

Figure 4

Effects of dietary mogroside V supplementation on lung Th17/Treg of broiler with acute lung injury. The mRNA levels of RORα(A), AhR(B), Foxp3 (C), IL-17A (D), IL-17F (E), IL-10 (F), PD-L1 (G), and PD-1 (H) in lung were analyzed by qRT-PCR. Data are expressed as the mean ± SEM (n = 6). CON-Saline: control group; CON-LPS: LPS group; MGV-Saline: MGV group; MGV-LPS: MGV-LPS group. *, P < 0.05, **, P < 0.01, ***, P < 0.001.

Figure 5

Mogroside V on the inflammatory factors in lung tissue of broilers with acute lung injury. Effects of mogroside V on the inflammatory factors TGF-β (A), IL-6 (B), IL-17 (C), and IL-10 (D) in the lungs of broilers with acute lung injury. Data are expressed as the mean ± SEM (n = 6). CON-Saline: control group; CON-LPS: LPS group; MGV-Saline: MGV group; MGV-LPS: MGV-LPS group. *, P < 0.05.

Figure 6

Mogroside V on the lung microbiota of broilers with acute lung injury. (A) Evaluation of sequencing volume adequacy by plotting dilution curves; (B) Alpha diversity refers to the diversity within a given habitat or ecosystem and is usually calculated using 2 important parameters: species richness (species status) and species evenness (distribution status); (C) Microbial Venn diagram analysis of broiler lungs based on OTU abundance information; (D) Partial least squares discriminant analysis (PLS-DA) is performed to discriminate the community structure data based on the given grouping information (n = 5).

Figure 7

Mogroside V on the relative abundances of bacterial taxa in the lungs of broilers with acute lung injury. (A) The 10 most dominant phyla were plotted. (B) Differential microbes on phylum level in lung of broiler chickens by T test. (C) The 10 most dominant genera were plotted. (D) Differential microbes on genus level in lung of broiler chickens by T test (n = 5).

Figure 8

Analysis of intergroup colony differences by LEFse and prediction of relevant phenotypic abundance in samples based on Bugbase. (A) Bar chart showing the LDA score of bacterial taxa in the groups. Bacterial taxa covered from phylum to genus level. Significant differences were defined as P < 0.05 and LDA score >3.0. (B) Cladogram revealed significantly enriched bacterial taxa. (C, D) Bugbase predicted organism-level microbiome phenotypes (n = 5). **, P < 0.01.