Sihui Li            Ocean University of China

Main findings

1) LPC significantly improved intestinal tissue damage in turbot

Figure 1. Histological sections of the distal intestine in four experimental groups. Scale bar = 500 μm for (A-D), and scale bar = 50 μm for (E-H). Staining: H & E. Red stars showed the infiltration of mixed leucocytes in the lamina propria (LP). MF mucosal folds. MM muscularis mucosa. MV microvilli(black arrows).

Figure 2. Intestinal histology parameters. (A) The height of mucosal folds (hMF); (B) The height of muscularis mucosa (hMM); (C) The height of microvilli (hMV); (D) perimeter ratio (PR). Results were expressed as means + S.E., and different superscript letters indicate significant differences (p < 0.05).

2)The expression of intestinal barrier genes indicates that LPC improves intestinal mucosal barrier function

Diets with 0.1-0.5% LPC supplementation significantly decreased the genes expressionOf TLR3, TLR8, TLR9, and TLR22 (p < 0.05)(Figure 3A).

Figure 3. Gene expression of TLR signaling pathway and intestinal mucosal barrier-related factors in the distal intestines (n = 6). (A,B) Gene expression of Toll-like receptors (TLRs), adaptor proteins and downstream regulator molecules; (C) Gene expression of inflammatory cytokines; (D) Gene expression of epithelial cell apoptosis and proliferation. Results were expressed as means ± S.E., and different superscript letters indicate significant differences (p < 0.05).

3）LPC alters the composition and structure of gut microbiota

Figure 4. Taxonomy classification of reads at different levels (n = 4). (A) Rarefaction curve; (B) Speciesa ccumulation boxplot; (C) Venn plot; (D,E) Bacteria taxonomic profiling at the phylum and genus level; (F) The Firmicutes / Bacteroides ratio.

Figure 5. α diversity of the intestinal microbiota. Results were expressed as means ± S.E., and different superscript letters indicate significant differences (p< 0.05).

Figure 6. diversity of the intestinal microbiota. (A) Principal Coordinate Analysis (PCoA) based

on unweighted unifrac distances; (B) Non-metric Multidimensional Scaling (NMDS) based on unweighted unifrac distances; (C) Unweighted Pair-Group Method with Arithmetic mean (UPGMA)-

clustering trees based on unweighted unifrac distances

4) LPC upregulated the relative abundance of multiple potential beneficial bacteria

Figure 7. Metastat analysis of the intestinal microbiota communities among groups at different

taxonomy. (A–C) Potential beneficial bacteria in intestinal microbiota at genus level. (A) Short-chain

fatty acid producer, (B) Lactic acid producer, (C) Digestive enzyme-producing bacteria, (D,E) Potential beneficial bacteria in intestinal microbiota at species level. (D) Short-chain fatty acid producer (E) Lactic acid producer. * means significant difference between the LPC0 group and the LPC0.1,LPC0.25 or LPC0.5 group (* p < 0.05, ** p < 0.01, *** p < 0.001).

5) LPC has a higher relative abundance in pathways such as lipid metabolism and the immune system, while its enrichment in pathways such as metabolic diseases and immune system diseases is relatively low

Figure 8. The functional profile predicted at level 2 (A) and level 3 (B) KEGGs Orthologs.

Conclusions

1、Dietary LPC (0.1–0.5%) had protective effects on the intestinal health of turbot fed high-lipid diets.

2、The TLR-mediated NF-κB pathway and TLR-mediated JNK and p38 signaling pathways might play important roles in the regulations mentioned above, respectively.

3、The composition and function of turbot intestinal microbiota were also significantly

altered by dietary LPC, which may contribute to the regulation of intestinal health by LPC.