Medium and Long Chain Fatty Acids Differentially Modulate Apoptosis and Release of Inflammatory Cytokines in Human Liver Cells

Salivary metabolites are promising noninvasive biomarkers of drug-induced liver injury

BACKGROUND

Drug-induced liver injury (DILI) is one of the most common adverse events of medication use, and its incidence is increasing. However, early detection of DILI is a crucial challenge due to a lack of biomarkers and noninvasive tests.

AIM

To identify salivary metabolic biomarkers of DILI for the future development of noninvasive diagnostic tools.

METHODS

Saliva samples from 31 DILI patients and 35 healthy controls (HCs) were subjected to untargeted metabolomics using ultrahigh-pressure liquid chromatography coupled with tandem mass spectrometry. Subsequent analyses, including partial least squares-discriminant analysis modeling, t tests and weighted metabolite coexpression network analysis (WMCNA), were conducted to identify key differentially expressed metabolites (DEMs) and metabolite sets. Furthermore, we utilized least absolute shrinkage and selection operato and random fores analyses for biomarker prediction. The use of each metabolite and metabolite set to detect DILI was evaluated with area under the receiver operating characteristic curves.

RESULTS

We found 247 differentially expressed salivary metabolites between the DILI group and the HC group. Using WMCNA, we identified a set of 8 DEMs closely related to liver injury for further prediction testing. Interestingly, the distinct separation of DILI patients and HCs was achieved with five metabolites, namely, 12-hydroxydodecanoic acid, 3-hydroxydecanoic acid, tetradecanedioic acid, hypoxanthine, and inosine (area under the curve: 0.733-1).

CONCLUSION

Salivary metabolomics revealed previously unreported metabolic alterations and diagnostic biomarkers in the saliva of DILI patients. Our study may provide a potentially feasible and noninvasive diagnostic method for DILI, but further validation is needed.

The potential of hydroxytyrosol fatty acid esters to enhance oral bioavailabilities of hydroxytyrosol and fatty acids: Continuous and slow-release ability in small intestine and blood

HPLC-UV analysis in rat everted gut sac and in vitro simulated digestion models indicated that hydroxytyrosol fatty acid esters (HTy-Es) could be hydrolyzed by pancreatic lipase to slow-release of free fatty acids (FAs) and HTy. Meanwhile, the HTy-Es, the liberated FAs and the HTy could cross the membrane and were transported into blood circulation. HTy-Es were further hydrolyzed by carboxylesterase in in vitro rat plasma hydrolysis model, which also showed slow-release of FAs (C1-C4) and HTy. Especially, the rates of hydrolysis and transport initially increased and then decreased with the increasing alkyl chain length. Besides, the above rates of the HTy-Es with a straight chain were greater than those of its isomer with a branched chain. Therefore, the above-mentioned continuous and slow-release of FAs and HTy in small intestine and blood clearly demonstrated that HTy-Es would be an effective approach to enhance oral bioavailabilities of free fatty acids and hydroxytyrosol.

Acute Oral Toxicity and Genotoxicity Test and Evaluation of Cinnamomum camphora Seed Kernel Oil

Cinnamomum camphora seed kernel oil (CCSKO) is one of the important natural medium chain triglycerides (MCT) resources, with more than 95.00% of medium chain fatty acids found in the world, and has various physiological effects. However, CCSKO has not been generally recognized as a safe oil or new food resource yet. The acute oral toxicity test and a standard battery of genotoxicity tests (mammalian erythrocyte micronucleus test, Ames test, and in vitro mammalian cell TK gene mutation test) of CCSKO as a new edible plant oil were used in the study. The results of the acute oral toxicity test showed that CCSKO was preliminary non-toxic, with an LD50 value higher than 21.5 g/kg body weight. In the mammalian erythrocyte micronucleus test, there was no concentration-response relationship between the dose of CCSKO and micronucleus value in polychromatic erythrocytes compared to the negative control group. No genotoxicity was observed in the Ames test in the presence or absence of S9 at 5000 μg/mL. In vitro mammalian cell TK gene mutation test showed that CCSKO did not induce in vitro mammalian cell TK gene mutation in the presence or absence of S9 at 5000 μg/mL. These results indicated that CCSKO is a non-toxic natural medium-chain oil.

Transcriptomic and metabolic signatures of diatom plasticity to light fluctuations

Unlike in terrestrial and freshwater ecosystems, light fields in oceans fluctuate due to both horizontal current and vertical mixing. Diatoms thrive and dominate the phytoplankton community in these fluctuating light fields. However, the molecular mechanisms that regulate diatom acclimation and adaptation to light fluctuations are poorly understood. Here, we performed transcriptome sequencing, metabolome profiling, and 13C-tracer labeling on the model diatom Phaeodactylum tricornutum. The diatom acclimated to constant light conditions was transferred to six different light conditions, including constant light (CL5d), short-term (1 h) high light (sHL1h), and short-term (1 h) and long-term (5 days) mild or severe light fluctuation conditions (mFL1h, sFL1h, mFL5d, and sFL5d) that mimicked land and ocean light levels. We identified 2,673 transcripts (25% of the total expressed genes) expressed differentially under different fluctuating light regimes. We also identified 497 transcription factors, 228 not reported previously, which exhibited higher expression under light fluctuations, including 7 with a light-sensitive PAS domain (Per-period circadian protein, Arnt-aryl hydrocarbon receptor nuclear translocator protein, Sim-single-minded protein) and 10 predicted to regulate genes related to light-harvesting complex proteins. Our data showed that prolonged preconditioning in severe light fluctuation enhanced photosynthesis in P. tricornutum under this condition, as evidenced by increased oxygen evolution accompanied by the upregulation of Rubisco and light-harvesting proteins. Furthermore, severe light fluctuation diverted the metabolic flux of assimilated carbon preferentially toward fatty acid storage over sugar and protein. Our results suggest that P. tricornutum use a series of complex and different responsive schemes in photosynthesis and carbon metabolism to optimize their growth under mild and severe light fluctuations. These insights underscore the importance of using more intense conditions when investigating the resilience of phytoplankton to light fluctuations.

Identification of key genes associated with the progression of liver fibrosis to hepatocellular carcinoma based on iTRAQ proteomics and GEO database

INTRODUCTION AND OBJECTIVE

Liver fibrosis (LF) often leads to cirrhosis and even hepatocellular carcinoma (HCC), but the molecular mechanism remains unclear. The aims of the present study were to identify potential biomarkers for the progression of LF to HCC and explore the associated molecular mechanisms.

MATERIALS AND METHODS

The isobaric tags for relative and absolute quantitation (iTRAQ) was used to detect changes in the protein expression profiles of liver tissues and to screen the differentially expressed proteins (DEPs). The differentially expressed genes (DEGs) of LF rats and patients were screened by Gene Expression Database (GEO). Subsequently, the clinicopathological analysis of the overlapping genes in different pathological stages in HCC patients based on GEPIA database was conducted.

RESULTS

iTRAQ proteomic analysis revealed 689, 749 and 585 DEPs in the 6W, 8W and 12W groups, respectively. ALDH2, SLC27A5 and ASNS were not only the DEPs found in rats with LF with different stages but were also the DEGs related to the pathological stages and survival in patients with HCC.

CONCLUSIONS

ALDH2, SLC27A5 and ASNS were the potential biomarkers associated with the progression of LF to HCC.

The Impact of Medium Chain and Polyunsaturated ω-3-Fatty Acids on Amyloid-β Deposition, Oxidative Stress and Metabolic Dysfunction Associated with Alzheimer's Disease

Alzheimer’s disease (AD), the most common cause of dementia in the elderly population, is closely linked to a dysregulated cerebral lipid homeostasis and particular changes in brain fatty acid (FA) composition. The abnormal extracellular accumulation and deposition of the peptide amyloid-β (Aβ) is considered as an early toxic event in AD pathogenesis, which initiates a series of events leading to neuronal dysfunction and death. These include the induction of neuroinflammation and oxidative stress, the disruption of calcium homeostasis and membrane integrity, an impairment of cerebral energy metabolism, as well as synaptic and mitochondrial dysfunction. Dietary medium chain fatty acids (MCFAs) and polyunsaturated ω-3-fatty acids (ω-3-PUFAs) seem to be valuable for disease modification. Both classes of FAs have neuronal health-promoting and cognition-enhancing properties and might be of benefit for patients suffering from mild cognitive impairment (MCI) and AD. This review summarizes the current knowledge about the molecular mechanisms by which MCFAs and ω-3-PUFAs reduce the cerebral Aβ deposition, improve brain energy metabolism, and lessen oxidative stress levels.

The Divergent Immunomodulatory Effects of Short Chain Fatty Acids and Medium Chain Fatty Acids

Fatty acids are derived from diet and fermentative processes by the intestinal flora. Two to five carbon chain fatty acids, termed short chain fatty acids (SCFA) are increasingly recognized to play a role in intestinal homeostasis. However, the characteristics of slightly longer 6 to 10 carbon, medium chain fatty acids (MCFA), derived primarily from diet, are less understood. Here, we demonstrated that SCFA and MCFA have divergent immunomodulatory propensities. SCFA down-attenuated host pro-inflammatory IL-1β, IL-6, and TNFα response predominantly through the TLR4 pathway, whereas MCFA augmented inflammation through TLR2. Butyric (C4) and decanoic (C10) acid displayed most potent modulatory effects within the SCFA and MCFA, respectively. Reduction in TRAF3, IRF3 and TRAF6 expression were observed with butyric acid. Decanoic acid induced up-regulation of GPR84 and PPARγ and altered HIF-1α/HIF-2α ratio. These variant immune characteristics of the fatty acids which differ by just several carbon atoms may be attributable to their origins, with SCFA being primarily endogenous and playing a physiological role, and MCFA exogenously from the diet.

The effect of a 6-month ketogenic medium-chain triglyceride supplement on plasma cardiometabolic and inflammatory markers in mild cognitive impairment

INTRODUCTION

Mild cognitive impairment (MCI) is often accompanied by metabolic abnormalities and inflammation that might play a role in the development of cognitive impairment. The use of ketogenic medium-chain triglycerides (kMCT) to improve cognition in this population has shown promising results but remains controversial because of the potentially detrimental effect of elevated intake of saturated fatty acids on cardiovascular (CV) health and perhaps inflammatory processes. The primary aim of this secondary data analysis report is to describe changes in cardiometabolic markers and peripheral inflammation during a 6-month kMCT intervention in MCI.

METHODS

Thirty-nine participants with MCI completed the intervention of 30 g/day of either a kMCT drink or calorie-matched placebo (high-oleic acid) for 6 months. Plasma concentrations of cardiometabolic and inflammatory markers were collected before (fasting state) and after the intervention (2 h following the last drink).

RESULTS

A mixed model ANOVA analysis revealed a time by group interaction for ketones (P < 0.001), plasma 8:0 and 10:0 acids (both P < 0.001) and IL-8 (P = 0.002) with follow up comparison revealing a significant increase in the kMCT group (+48%, P = 0.005), (+3,800 and +4,900%, both P < 0.001) and (+147%, P < 0.001) respectively. A main effect of time was observed for insulin (P = 0.004), triglycerides (P = 0.011) and non-esterified fatty acids (P = 0.036).

CONCLUSION

Under these study conditions, 30 g/d of kMCT taken for six months and up to 2-hour before post-intervention testing had minimal effect on an extensive profile of circulating cardiometabolic and inflammatory markers as compared to a placebo calorie-matched drink. Our results support the safety kMCT supplementation in individuals with MCI. The clinical significance of the observed increase in circulating IL-8 levels is presently unknown and awaits future studies.

Dynamic Metabolome Analysis Reveals the Metabolic Fate of Medium-Chain Fatty Acids in AML12 Cells

Several studies in hepatocyte cell lines reported that medium-chain fatty acids (MCFAs) with 6-12 carbons showed different metabolic properties from long-chain fatty acids (LCFAs). However, these studies reported unclear effects of different fatty acid molecules on hepatocyte metabolism. This study is aimed to capture the metabolic kinetics of MCFA assimilation in AML12 cells treated with octanoic acid (FA 8:0), decanoic acid (FA 10:0), or lauric acid (FA12:0) [LCFA; oleic acid (FA 18:1)] via metabolic profiling and dynamic metabolome analysis with ¹³C-labeling. The concentrations of total ketone bodies in the media of cells treated with FA 8:0 or FA 10:0 were 3.22- or 3.69-fold higher than those obtained with FA 18:1 treatment, respectively. FA 12:0 treatment did not significantly increase ketone body levels compared to DMSO treatment (control), whereas FA 12:0 treatment increased intracellular triacylglycerol (TG) levels 15.4 times compared to the control. Metabolic profiles of FA 12:0-treated samples differed from those of the FA 8:0-treated and FA 10:0-treated samples, suggesting that metabolic assimilation of MCFAs differed significantly depending on the MCFA type. Furthermore, the dynamic metabolome analysis clearly revealed that FA 8:0 was rapidly and quantitatively oxidized to acetyl-CoA and assimilated into ketone bodies, citrate cycle intermediates, and glucogenic amino acids but not readily into TGs.

Effects of medium- and long-chain fatty acids on acetaminophen- or rifampicin-induced hepatocellular injury

Drug-induced liver injury (DILI) is one of the common adverse effects of drug therapy, which is closely associated with oxidative stress, apoptosis, and inflammation response. Medium-chain fatty acids (MCFA) were reported to relieve inflammation and attenuate oxidative stress. However, little has been known about the hepatoprotective effects of MCFA in DILI. In the present study, acetaminophen (AP) and rifampicin (RFP) were used to establish DILI models in LO2 cells, and the cytoprotective effects of MCFA on hepatocellular injury were investigated. Results showed that the optimal condition for the DILI model was treatment with 10 mM AP or 600 µM RFP for 24 hr. LCFA treatment markedly reduced the cell viability and increased the activities of alanine aminotransferase, aspartate aminotransferase, and lactate dehydrogenase. Meanwhile, LCFA treatment aggravated cell apoptosis, mitochondrial dysfunction, and oxidative stress. The mRNA and protein expression levels of inflammatory cytokines (IL-1β and TNF-α) were significantly elevated by LCFA. In contrast, MCFA treatment did not significantly affect cell viability, apoptosis, oxidative, stress and inflammation, and it did not produce the detrimental effects on DILI models. Therefore, we proposed that MCFA may be more safe and suitable than LCFA as nutrition support or the selection of daily dietary oil and fat for the patients with DILI.

Inhibition of p53 alleviates prostate cell apoptosis in Escherichia coli‑induced bacterial prostatitis

Previous studies demonstrated that uropathogenic Escherichia coli infection contributes to human bacterial prostatitis. Apoptosis of prostate epithelial cells is closely associated with the progression of bacterial prostatitis. The aim of the present study was to investigate the effect of cellular tumor antigen p53 (p53) on the apoptosis of bacterial prostatitis cells. The prostate epithelial RWPE‑1 cell line was infected with Escherichia coli, and treated cells and the culture supernatant were obtained at specific time points. The cell apoptosis rates, protein and mRNA of p53 were detected in the different treatment groups. Flow cytometry and terminal deoxynucleotidyl‑transferase‑mediated dUTP nick end labeling assays were used for the detection of cell apoptosis, and cell proliferation was determined by a Cell Counting Kit‑8 assay. The expression of p53 was inhibited by small interfering (si)RNA, and its mRNA and protein were detected. An ELISA was used for detecting cytokines in the culture supernatant. The result demonstrated that Escherichia coli infection led to an increase in prostate epithelial cell apoptosis (P<0.05), and resulted in increases of interleukin (IL)‑4, IL‑6 and IL‑8, and decrease in IL‑10. p53, apoptosis regulator BAX (Bax), caspase‑9 and Caspase‑3 expression were upregulated upon Escherichia coli exposure (P<0.05). Following transfection with p53 siRNA, the promotion of cell apoptosis induced by Escherichia coli infection was decreased, and the p53 and Bax protein expression were additionally decreased. Therefore, it was suggested that Escherichia coli increases cell apoptosis in bacterial prostatitis by activating the death receptor pathway involving p53. Inhibition of p53 alleviated prostate cell apoptosis induced by Escherichia coli.

Hexanoic, Octanoic and Decanoic Acids Promote Basal and Insulin-Induced Phosphorylation of the Akt-mTOR Axis and a Balanced Lipid Metabolism in the HepG2 Hepatoma Cell Line

Metabolic illnesses such as non-alcoholic fatty liver disease (NAFLD) are in constant increase worldwide. Highly consumed long chain fatty acids (LCFA) are among the most obesogenic and steatogenic nutrients. Hepatic steatosis is associated with several complications such as insulin resistance. Growing evidence points to medium chain fatty acids (MCFA), more efficiently oxidized than LCFA, as a promising dietary alternative against NAFLD. However, reports on the hepatic effects of MCFA are sometimes conflicting. In this study we exposed HepG2 cells, a human hepatocellular model, to 0.25 mM of hexanoic (C6), or octanoic (C8), and decanoic (C10) acids separately or in a C8 + C10 equimolar mix reflecting commercially available MCFA-rich oils. We found that C6, a poorly studied MCFA, as well as C8 and C10 did not provoke the deleterious lipid anabolism runaway typically induced by LCFA palmitate. MCFA tended, instead, to promote a balanced metabolic profile and were generally non-cytotoxic. Accordingly, mitochondrial integrity was mostly preserved following MCFA treatment. However, treatments with C8 induced a mitochondrial membrane potential decrease, suggesting prolonged exposure to this lipid could be problematic. Finally, MCFA treatments maintained optimal insulin sensitivity and even fostered basal and insulin-dependent phosphorylation of the Akt-mTOR pathway. Overall, MCFA could constitute an effective nutritional tool to manage liver steatosis and hepatic insulin resistance.

Medium-chain TAG improve intestinal integrity by suppressing toll-like receptor 4, nucleotide-binding oligomerisation domain proteins and necroptosis signalling in weanling piglets challenged with lipopolysaccharide

This study was conducted to evaluate whether medium-chain TAG (MCT) could alleviate Escherichia coli lipopolysaccharide (LPS)-induced intestinal injury by regulating intestinal epithelial inflammatory response, as well as necroptosis. A total of twenty-four weanling piglets were randomly allotted to one of four treatments in a 2×2 factorial arrangement including diet type (5 % maize oil v. 4 % MCT+1 % maize oil) and immune stress (saline v. E. coli LPS). The piglets were fed diets containing maize oil or MCT for 21 d. On 21 d, piglets were injected intraperitoneally with saline or LPS. The blood and intestinal samples were collected at 4 h post injection. Supplementation with MCT improved intestinal morphology, digestive and barrier function, indicated by increased jejunal villus height, increased jejunal and ileal disaccharidases (sucrase and maltase) activities, as well as enhanced protein expression of claudin-1. Furthermore, the protein expression of heat-shock protein 70 in jejunum and the concentration of TNF-α in plasma were reduced in the piglets fed diets supplemented with MCT. In addition, MCT down-regulated the mRNA expression of toll-like receptor 4 (TLR4) and nucleotide-binding oligomerisation domain proteins (NOD) signalling-related genes in jejunum and ileum. Finally, MCT inhibited jejunal and ileal enterocyte necroptosis indicated by suppressed mRNA expression of the receptor-interacting protein 3 and mixed-lineage kinase domain-like protein. These results indicate that MCT supplementation may be closely related to inhibition of TLR4, NOD and necroptosis signalling pathways and concomitant improvement of intestinal integrity under an inflammatory condition.