Changes of the liver metabolome following an intravenous lipopolysaccharide injection in Holstein cows supplemented with dietary carnitine

Background:Carnitine facilitates the flux of long-chain fatty acids for hepatic mitochondrial beta-oxidation,which acts to ameliorate the negative energy balance commonly affecting high-yielding dairy cows.Inflammation triggered by lipopolysaccharide(LPS)load can however pose a challenge to the metabolic integrity via the expression of pro-inflammatory mediators,leading to immune system activation and respective metabolic alterations.The effect of enhanced carnitine availability on hepatic metabolome profiles during an inflammatory challenge has not yet been determined in dairy cows.Herein,Holstein cows were supplemented with 25 g/d rumen-protected carnitine from 42d prepartum until 126 d postpartum(n=16)or assigned to the control group with no supplementation during the same period(n=14).We biopsied the liver of the cows before(100 d postpartum)and after(112 d postpartum)an intravenous injection of 0.5μg/kg LPS.Liver samples were subjected to a targeted metabolomics analysis using the AbsoluteIDQ p180 Kit(Biocrates Life Sciences AG,Innsbruck,Austria).Results:Multivariate statistical analyses revealed that hepatic metabolome profiles changed in relation to both the carnitine supplementation and the LPS challenge.Comparing the metabolite profiles on 100 d,carnitine increased the concentration of short-and long-chain acyl-carnitines,which may be explained by an enhanced mitochondrial fatty acid shuttle and hence greater energy availability.The LPS injection affected hepatic metabolite profiles only in the carnitine supplemented group,particularly altering the concentration of biogenic amines.Conclusions:Our results point to interactions between an acute hepatic inflammatory response and biogenic amine metabolism,depending on energy availability.

The protective effects of Levilactobacillus brevis FZU0713 on lipid metabolism and intestinal microbiota in hyperlipidemic rats

Levilactobacillus brevis FZU0713, a potential probiotic previously isolated from the traditional brewing process of Hongqu rice wine, may have the beneficial effects on improving lipid metabolism. This study aimed to evaluate the in vivo protective effects and possible mechanism of L. brevis FZU0713 on the disturbance of lipid metabolism in hyperlipidemic rats fed a high-fat diet(HFD). Results showed that oral administration of L. brevis FZU0713 could significantly inhibit obesity, ameliorate the lipid metabolism disorder, including serum/liver biochemical parameters and hepatic oxidative stress in HFD-fed rats. Histopathological result also indicated that dietary intervention of L. brevis FZU0713 could reduce the accumulation of lipid droplets in liver induced by 8 weeks HFD feeding. Furthermore, L. brevis FZU0713 intervention significantly increased the fecal levels of short-chain fatty acids(SCFAs, including acetate, propionate, butyrate, isobutyrate, valerate and isovalerate)in HFD-fed rats, which may be closely related to the changes of intestinal microbial composition and metabolic function. Intestinal microbiota profiling by 16S rRNA gene sequencing revealed that L. brevis FZU0713 intervention significantly altered the relative abundance of Coprococcus, Butyricicoccus, Intestinimonas, Lachnospiraceae FCS020 group, Ruminococcaceae_NK4A214 group, Ruminococcaceae_UCG-005 and UCG-014 at genus levels. Based on Spearman's rank correlation coefficient, serum and liver lipid metabolism related biochemical parameters were positively correlated with genera Ruminococcus, Pediococcus and Lachnospiraceae, but negatively correlated with genera Pseudoflavonifractor, Butyricicoccus and Intestinimonas. Furthermore, liver metabolomics analysis demonstrated that L. brevis FZU0713 had a significant regulatory effect on the composition of liver metabolites in hyperlipidemic rats, especially the levels of some important biomarkers involved in the metabolic pathways of arachidonic acid metabolism, primary bile acid biosynthesis, amino sugar and nucleotide sugar metabolism, taurine and hypotaurine metabolism, biosynthesis of unsaturated fatty acid, fructose and mannose metabolism, tyrosine metabolism, etc. Additionally, oral administration of L. brevis FZU0713 significantly regulated the mR NA levels of liver genes(including Acat2, Acox1, Hmgcr, Cd36, Srebp-1c and Cyp7a1)involved in lipid metabolism and bile acid homeostasis. In conclusion, our findings provide the evidence that L. brevis FZU0713 has the potential to improve disturbance of lipid metabolism by regulating intestinal microflora and liver metabonomic profile. Therefore, L. brevis FZU0713 may be used as a potential probiotic strain to produce functional food to prevent hyperlipidemia.

Combination of LC/MS and GC/MS based metabolomics to study the hepatotoxic effect of realgar nanoparticles in rats

Realgar nanoparticles(NPs) are increasingly used as therapeutic agents for their enhanced anti-proliferation effect and cytotoxicity on cancer cells. However, the alteration of particle size may enhance biological reactivity as well as toxicity. A LC/MS and GC/MS based metabolomics approach was employed to explore the mechanism of realgar NPs-induced hepatotoxicity and identify potential biomarkers. Male Sprague-Dawley rats were administrated intragastrically with realgar or realgar NPs at a dose of 1.0 g·kg^(-1)·d^(-1) for 28 days and toxic effects of realgar NPs on liver tissues were examined by biochemical indicator analysis and histopathologic examination. Increased levels of serum enzymes and high hepatic steatosis were discovered in the realgar NPs treated group. Multivariate data analysis revealed that rats with realgar NPs-induced hepatotoxicity could be distinctively differentiated from the animals in the control and realgar treated groups. In addition, 21 and 32 endogenous metabolites were apparently changed in the serum and live extracts, respectively. Realgar NPs might induce free fatty acid and triglyceride accumulation, resulting in hepatotoxicity. In conclusion, the present study represents the first comprehensive LC/MS-and GC/MS-based metabolomics analysis of realgar NPs-induced hepatotoxicity, which may help further research of nanotoxicity.

Ameliorative effects of monascin from red mold rice on alcoholic liver injury and intestinal microbiota dysbiosis in mice

Monascus-fermented red mold rice(RMR)has excellent physiological efficacy on lipid metabolism and liver function.This study investigated the ameliorative effects of monascin(MS)from RMR on alcoholic liver injury(ALI)in mice,and further illustrated its mechanism of action.Results indicated that dietary MS intervention obviously ameliorated lipid metabolism and liver function in mice with over-drinking.In addition,MS intervention alleviated alcohol-induced oxidative stress in the liver by reducing the hepatic activities of lactate dehydrogenase(LDH)and hepatic levels of malondialdehyde(MDA),increasing the hepatic activities of catalase(CAT),superoxide dismutase(SOD),alcohol dehydrogenase(ADH)and hepatic levels of glutathione(GSH).16S rRNA amplicon sequencing showed that excessive drinking had a significant effect on the composition of the gut microbiota in mice.MS intervention was beneficial to ameliorate intestinal microbiota dysbiosis by elevating the proportion of Lactobacillus,Lachnospiraceae_UCG-006,Coriobacteriales,etc.,but decreasing the proportion of Staphylococcus,Muribaculaceae,Desulfovibrionaceae,etc.Additionally,correlation analysis indicated that the key intestinal bacterial taxa intervened by MS were closely related to some biochemical indicators of lipid metabolism,liver function and oxidative stress.Moreover,liver metabolomics analysis revealed that dietary MS supplementation significantly regulated the levels of liver metabolites involved in taurine and hypotaurine metabolism,riboflavin metabolism,and purine metabolism,etc.Furthermore,MS intervention regulated gene transcription and protein expression associated with lipid metabolism and oxidative stress in the liver.In short,these findings suggest that MS mitigates alcohol-induced hepatic oxidative damage through modulating the intestinal microbiome and liver metabolic pathway,and thus can be served as a functional component to prevent alcoholic liver disease.

Chronic exposure to high-density polyethylene microplastic through feeding alters the nutrient metabolism of juvenile yellow perch (Perca flavescens)

Microplastics are emergent contaminants threatening aquatic organisms including aquacultured fish.This study investigated the effects of high-density polyethylene(HDPE,100 to 125 mm)on yellow perch(Perca flavescens)based on integrative evaluation including growth performance,nutritional status,nutrient metabolism,fish health,and gut microbial community.Five test diets(0,1,2,4,or 8 g HDPE/100 g diet)containing 41%protein and 10.5%lipid were fed to juvenile perch(average body weight,25.9±0.2 g;n=15)at a feeding rate of 1.5%to 2.0%body weight daily.The feeding trial was conducted in a flow-through water system for 9 wk with 3 tanks per treatment and 15 yellow perch per tank.No mortality or HDPE accumulation in the fish was found in any treatments.Weight gain and condition factor of fish were not significantly impacted by HDPE(P>0.05).Compared to the control group,fish fed the 8%HDPE diet had significantly decreased levels of protein and ash(P<0.05).In response to the increasing levels of HDPE exposure,the hepatosomatic index value,hepatocyte size,and liver glycogen level were increased,but lipid content was reduced in the liver tissues.Compared to the control treatment,fish fed the 8%HDPE diet had significant accumulations of total bile acids and different metabolism pathways such as bile acid biosynthesis,pyruvate metabolism,and carnitine synthesis.Significant enterocyte necrosis was documented in the foregut of fish fed the 2%or 8%HDPE diet;and significant cell sloughing was observed in the midgut and hindgut of fish fed the 8%HDPE diet.Fish fed the 2%HDPE diet harbored different microbiota communities compared to the control fish.This study demonstrates that HDPE ranging from 100 to 125 mm in feed can be evacuated by yellow perch with no impact on growth.However,dietary exposure to HDPE decreased whole fish nutrition quality,altered nutrient metabolism and the intestinal histopathology as well as microbiota community of yellow perch.The results indicate that extended exposure may pose a risk to fish health and jeopardize the nutrition quality of aquacultured end product.This hypothesis remains to be investigated further.

The probiotic effects of host-associated Bacillus velezensis in diets for hybrid yellow catfish(Pelteobagrus fulvidraco♀×Pelteobagrus vachelli♂)

This study was to evaluate the potential of a host-associated Bacillus velezensis as a probiotic for hybrid yellow catfish(Pelteobagrus fulvidraco♀×Pelteobagrus vachelli♂).Diets(B0 to B5)containing 0,0.90×10^(8),0.80×109,0.85×10^(10),0.90×10^(11),0.83×10^(12)CFU/kg B.velezensis YFI-E109 were fed to the fish with initial weight(3.07±0.08 g)in a recirculating aquaculture system for six weeks with three replicates,respectively.Probiotic effects were analyzed based on growth,body composition,liver and gut morphology,gut microbiome,and liver metabolome.Analysis of the bacterial genome has shown that the most abundant genes in B.velezensis YFI-E109 were distributed in carbohydrate and amino acid metabolism.Fish in groups B3 and B4 had better growth performance,and higher intestinal amylase(AMS)and lipase(LPS)activities compared with other groups(P<0.05).Fish in groups B0 and B5 showed significant liver damage,while this status improved in group B3.The liver malondialdehyde(MDA)content in group B3 was lower than that in other groups(P<0.05).The abundance of Mycoplasma,Ralstonia and Acinetobacter was significantly reduced in B3 and B5 compared to B0.The amino acid and carbohydrate metabolism pathways were enriched in group B3 compared with group B0.In conclusion,dietary B.velezensis YFI-E109 supplementation has the potential to improve growth,liver metabolism,and liver and gut health,and reshape the gut microbiome of hybrid yellow catfish.Excessive B.velezensis YFI-E109 reduced the prebiotic effects.The recommended dietary supplementation of B.velezensis YFI-E109 is 0.31×10^(10) to 0.77×10^(11)CFU/kg for hybrid yellow catfish according to the quadratic regression method by plotting specific growth rate(SGR),feed conversion ratio(FCR),MDA and activities of AMS against dietary B.velezensis YFI-E109 levels.