Figure 4 Salmonella infection perturbs the host’s hepatobiliary homeostasis. (A) bile volumes recovered from the gallbladders of mice orally infected with Salmonella at the indicated hours post-infection (hpi). (B) Transcript levels of hepatic genes involved in liver biliary metabolism in mice infected with Salmonella, relative to the levels of uninfected 17DMAG animals (defined as 1, dashed line) at 24, 72 and 120 hours post-infection. Data by qPCR. Figure 5 Salmonella infection downregulates the neutral
bile acid synthesis buy Pitavastatin pathway. (A) relative levels of liver Cyp7a1 transcripts in mice infected with Salmonella. (B) CYP7A1 western blot of liver lysates. (C) Cholesterol and (D) triglycerides accumulation in the liver of Salmonella-infected vs. uninfected mice, (*p < 0.05; ****p < 0.0001). Salmonella infection leads to depletion of the hepatic FGF15 receptor complex Signaling of FGF15 in hepatocytes requires the tyrosine kinase membrane receptor
FGFR4 and the protein βKlotho. To determine if Salmonella infection disturbs the homeostasis of this pathway, we analyzed the levels of FGFR4 and βKlotho in infected and uninfected livers. Figures 6A and 6B show that the transcript levels of both Fgfr4 and Klb (βKlotho) were significantly decreased by infection. In addition, the protein Ruboxistaurin research buy levels were also reduced, as evidenced by western blot (Figure 6C). Two major FGFR4 bands were detected in
uninfected animals, with apparent molecular weights of 115 and 125 KDa, likely corresponding to the core-glycosylated (FGFR4115) and fully-glycosylated, functional (FGFR4125) forms of FGFR4, respectively . Infection led to the disappearance of FGFR4125 and a decrease of FGFR4115. Immunofluorescent staining of liver sections confirmed the reduction of FGFR4 and βKlotho. Both proteins were Alanine-glyoxylate transaminase clearly detected in uninfected hepatocytes (Figure 6D); in contrast, hepatocytes from Salmonella-infected livers were devoid of FGFR4 and βKlotho. Figure 6 Salmonella infection causes the loss of the hepatic FGF15 receptor complex. (A) relative levels of Fgfr4 and (B) Klb (βKlotho) transcripts in the livers of mice infected with Salmonella. The animals analyzed in (A) and (B) are from the high-infection group in Figure 1, the data is by qPCR, (**p < 0.01; ***p < 0.001). (C) FGFR4 and βKlotho western blots of liver lysates. (D) FGFR4 and βKlotho immunostaining of uninfected (top panel) and Salmonella-infected (bottom panel) liver samples. The figure shows a single, representative hepatocyte in each case. Scale bar is 5 μm. Discussion The FGF19-FGFR4 endocrine axis is currently considered a potential intervention point for the therapy of cancer, gallstone disease, and metabolic disorders associated to the metabolic syndrome [7, 30].