Bile acid toxicity in Paneth cells contributes to gut dysbiosis induced by high-fat feeding
Hui Zhou, … , Xianjun Xu, Chung Owyang
Hui Zhou, … , Xianjun Xu, Chung Owyang
Published October 15, 2020
Citation Information: JCI Insight. 2020;5(20):e138881. https://doi.org/10.1172/jci.insight.138881.
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Research Article Gastroenterology

Bile acid toxicity in Paneth cells contributes to gut dysbiosis induced by high-fat feeding

Abstract

High-fat feeding (HFF) leads to gut dysbiosis through unclear mechanisms. We hypothesize that bile acids secreted in response to high-fat diets (HFDs) may act on intestinal Paneth cells, leading to gut dysbiosis. We found that HFF resulted in widespread taxonomic shifts in the bacteria of the ileal mucosa, characterized by depletion of Lactobacillus and enrichment of Akkermansia muciniphila, Clostridium XIVa, Ruminococcaceae, and Lachnospiraceae, which were prevented by the bile acid binder cholestyramine. Immunohistochemistry and in situ hybridization studies showed that G protein–coupled bile acid receptor (TGR5) expressed in Paneth cells was upregulated in the rats fed HFD or normal chow supplemented with cholic acid. This was accompanied by decreased lysozyme+ Paneth cells and α-defensin 5 and 6 and increased expression of XBP-1. Pretreatment with ER stress inhibitor 4PBA or with cholestyramine prevented these changes. Ileal explants incubated with deoxycholic acid or cholic acid caused a decrease in α-defensin 5 and 6 and an increase in XBP-1, which was prevented by TGR5 antibody or 4PBA. In conclusion, this is the first demonstration to our knowledge that TGR5 is expressed in Paneth cells. HFF resulted in increased bile acid secretion and upregulation of TGR5 expression in Paneth cells. Bile acid toxicity in Paneth cells contributes to gut dysbiosis induced by HFF.

Authors

Hui Zhou, Shi-Yi Zhou, Merritt Gillilland III, Ji-Yao Li, Allen Lee, Jun Gao, Guanpo Zhang, Xianjun Xu, Chung Owyang

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Figure 1

TGR5 expression in the Paneth cells; HFD increases bile acids and enhances TGR5 expression in ileal crypts.

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TGR5 expression in the Paneth cells; HFD increases bile acids and enhanc...
(A and B) Immunocytochemical staining using sections of ileal specimens and isolated crypt cells showed that TGR5 expression was observed in the lysozyme+ Paneth cells (white arrows) in ileal crypts. Scale bar: 10 μm. (C) Left: hybridization using antisense probes. Purple represents lysozyme mRNA, a specific marker for Paneth cells, which are located at the bottom portion of crypt; silver grains indicate TGR5 mRNA. Arrows indicate colocalization. Right: Dig-lysozyme and [35S]-TGR5 sense probes were used as the negative control. Note that TGR5 receptors are also expressed in other cell types in the intestinal crypts. Scale bar: 50 μm; 3-fold magnification (inset). (D) Measurement of total bile acid concentration. A 2-week high-fat diet (HFD) induced a 45% increase in serum and 60% increase in fecal bile acid compared with control (RC) (n = 5–6). The increased total serum bile acid was prevented by concurrent administration of cholestyramine (n = 6). A similar increase in serum bile acid was observed in cholic acid group (n = 6). (E) The density of the TGR5-immunoreactive band at 33 kDa was observed in the ileal crypts of rats given HFD. TGR5 protein expression increased in ileal crypts of HFD rats compared with control (n = 5). This increase was prevented by concurrent administration of cholestyramine (n = 5). A similar increase was also observed in rats with cholic acid (n = 4–5). Each bar represents mean ± SEM. C, RC; H, HFD; CHO, HFD + cholestyramine; CA, cholic acid. P values were determined by 1-way ANOVA. *P < 0.05, **P < 0.01.