Mogroside V protects lipopolysaccharides-induced lung inflammation chicken via suppressing inflammation mediated by the Th17 through the gut-lung axis

Abstract

Lipopolysaccharide (LPS) exposure triggers pulmonary inflammation, leading to compromised lung function in broiler. As amplified by policy restrictions on antibiotic usage, seeking antibiotic alternatives has become imperative. Mogroside V (MGV) has been reported to have a beneficial role in livestock and poultry production due to its remarkable antiinflammatory effects. Despite evidence showcasing MGV's efficacy against LPS-triggered lung inflammation, its precise mechanism of action remains elusive. In this study, we transplanted normal fecal microbiota (CF), fecal microbiota modified by MGV (MF), and sterile fecal filtrate (MS) into broiler with LPS-induced pneumonia. The results showed that through fecal microbiota transplantation (FMT), transplanting MGV-induced microbial populations significantly mitigated tissue damage induced by LPS and enhanced the mRNA level of pulmonary tight junction proteins and mucoprotein (P < 0.01). The expression levels of RORα (P < 0.001), Foxp3 (P < 0.01), and PD-L1 (P < 0.01) were significantly increased in the MF group than CF group. The concentrations of IL-6 and IL-17 in broilers lung tissue of MF group were lower than those in broilers of CF group (P < 0.05). Furthermore, the concentration of TGF-β in broilers serum of MS and MF groups was higher than those in broilers of CF group (P < 0.05). Microbial community analysis demonstrated that at genus level, the harmful bacterial populations Escherichia-Shigella and Helicobacter following FMT treatment were significantly reduced in MF group (P < 0.05), potentially mediating its protective effects. Compared with CF group, valerate content and FFAR2 mRNA expression levels in MF group were significantly increased (P < 0.05). The study suggests that MGV via the gut-lung axis, attenuates Th17-mediated inflammation, offering promise as a therapeutic strategy against LPS-induced lung inflammation in chickens.

Keywords: broiler; intestinal microbiota; lipopolysaccharides; mogroside V; pulmonary inflammation.

Graphical Abstract

Figure 1.

Effects of dietary MGV supplementation on the Cecum bacterial diversity and species composition of broilers. (A) A Venn diagram was drawn to reveal the number of common and unique OTUs existing in the control and 0.20% MGV groups. (B) Principal co-ordinates analysis (PCoA) of unweighted_unifrac in the control and 0.20% MGV groups. (C) The 10 most dominant phyla were plotted. (D) The 15 most dominant genera were plotted. (E) and (F) Differences between the control and 0.20% MGV groups at the phylum level bacterial. (G), (H) and (I) Differences between the control and 0.20% MGV groups at the genus level bacterial. *P < 0.05, **P < 0.01, ***P < 0.001. Data are expressed as the mean ± SEM (n = 5).

Figure 2.

Analysis of indicator species in cecum microbiota of broilers. (A) Cladogram revealed significantly enriched bacterial taxa. (B) LDA effect size (LefSe) demonstrating taxa with significantly different abundance (phylum to species, LDA score > 4). LDA (linear discriminant analysis) (C) Random forest analysis at phylum level. (D) Random forest analysis at genus level. (E) Indicator analysis at phylum level. (F) Indicator analysis at genus level (n = 5).

Figure 3.

Functional analysis of cecum microbiota in broilers. (A) KEGG function prediction was performed using Tax4Fun SILVA annotation for 16S sequences. (B) Predicted phenotypic classification and abundance in samples based on Bugbase. (C) Welch’s t-test: comparison of two groups to determine whether there is a significant difference in the mean value of functional abundance by Tax4Fun. (D) Welch’s t-test: comparison of two groups to determine whether there is a significant difference in the mean value of functional abundance by Bugbase (n = 5).

Figure 4.

FMT attenuates LPS-induced acute lung injury in broilers. (A) Histological examination. (B)–(F) Pulmonary barrier relative genes expression of broilers with acute lung injury. Note: Arrows indicate bronchial congestion and triangles indicate pulmonary capillary fusion. *P < 0.05, **P < 0.01, ***P < 0.001. Data are expressed as the mean ± SEM (n = 6).

Figure 5.

Effect of FMT on Th17/Treg pathway in the lung of broilers with acute lung injury. The mRNA levels of RORα (A), AhR (B), Foxp3 (C), PD-1 (D), PD-L1 (E), TGF-β (F), IL-17 (G) and IL-22 (H) in lung were analyzed by qRT-PCR. (I) TGF-β concentration in lung tissue. (J) IL-6 concentration in lung tissue. (K) IL-17 concentration in lung tissue. (L) IL-10 concentration in lung tissue. *P < 0.05, **P < 0.01, ***P < 0.001. Data are expressed as the mean ± SEM (n = 6).

Figure 6.

Effect of FMT on microbial diversity and composition in the cecum of broilers. (A) Venn diagram of the OTUs. (B) Shannon index was evaluated by Turkey-HSD. (C) UPGMA cluster tree analysis was performed based on the unweighted_unifrac distance index. (D) PCoA principal coordinate analysis was performed based on unweighted_unifrac distance index. (E) The 10 most dominant phyla were plotted. (F) The 10 most dominant genera were plotted (n = 5).

Figure 7.

Differences in the characteristic cecal microbiota of broilers between three groups. (A) The phyla with significant differences among CF and MF groups. (B) The genera with significant differences among CF and MF groups. (C) Random forest analysis at genus level between CF and MF groups. (D) Indicator analysis between CF and MF groups was performed. Significant differences were defined as P < 0.05. Welch’s t-test was used to compare whether there were significant differences in the mean abundance of species between the two groups (n = 5).