Bile acid-based therapies for non-alcoholic steatohepatitis and alcoholic liver disease

The Role of Gut Microbiota on Cholesterol Metabolism in Atherosclerosis

Hypercholesterolemia plays a causal role in the development of atherosclerosis and is one of the main risk factors for cardiovascular disease (CVD), the leading cause of death worldwide especially in developed countries. Current data show that the role of microbiota extends beyond digestion by being implicated in several metabolic and inflammatory processes linked to several diseases including CVD. Studies have reported associations between bacterial metabolites and hypercholesterolemia. However, such associations remain poorly investigated and characterized. In this review, the mechanisms of microbial derived metabolites such as primary and secondary bile acids (BAs), trimethylamine N-oxide (TMAO), and short-chain fatty acids (SCFAs) will be explored in the context of cholesterol metabolism. These metabolites play critical roles in maintaining cardiovascular health and if dysregulated can potentially contribute to CVD. They can be modulated via nutritional and pharmacological interventions such as statins, prebiotics, and probiotics. However, the mechanisms behind these interactions also remain unclear, and mechanistic insights into their impact will be provided. Therefore, the objectives of this paper are to present current knowledge on potential mechanisms whereby microbial metabolites regulate cholesterol homeostasis and to discuss the feasibility of modulating intestinal microbes and metabolites as a novel therapeutic for hypercholesterolemia.

Integrated metabolomics and transcriptomics reveal the anti-aging effect of melanin from Sepiella maindroni ink (MSMI) on D-galactose-induced aging mice

Sepiella maindroni ink, a flavoring and coloring agent in food, has attracted considerable attention due to its various pharmacological activities. Our previous study showed that the melanin of Sepiella maindroni ink (MSMI) can alleviate oxidative damage and delay aging in D-galactose(D-gal)-induced aging mice. This study aimed to reveal the possible mechanisms of the anti-aging effect of MSMI. In this article, a comprehensive analysis of gas chromatography-mass spectrometry (GC-MS)-based metabolomics and microarray-based transcriptomics revealed that 221 mRNAs were differentially expressed and 46 metabolites were significantly changed in the anti-aging progress of MSMI. Integrated analysis of transcript and metabolic profiles indicated that MSMI mainly altered carbohydrate metabolism, lipid metabolism, and insulin signaling pathway. MSMI achieved anti-aging effects not only by reducing oxidative damage and sorbitol toxicity but also by regulating lipid metabolism, improving insulin sensitivity, and reducing the formation of advanced glycation end products (AGEs). Moreover, our findings firstly demonstrated that MSMI could increase the expression of interferon-induced proteins and might be a potential antiviral compound.

Deoxycholic acid-functionalised nanoparticles for oral delivery of rhein

Rhein (RH) is a candidate for the treatment of kidney diseases. However, clinical application of RH is impeded by low aqueous solubility and oral bioavailability. Deoxycholic acid-conjugated nanoparticles (DNPs) were prepared by ionic interaction for enhancing intestinal absorption by targeting the apical sodium-dependent bile acid transporter in the small intestine. Resultant DNPs showed relatively high entrapment efficiency (90.7 ± 0.73)% and drug-loading efficiency (6.5 ± 0.29)% with a particle size of approximately 190 nm and good overall dispersibility. In vitro release of RH from DNPs exhibited sustained and pH-dependent profiles. Cellular uptake and apparent permeability coefficient (P_app) of the DNPs were 3.25- and 5.05-fold higher than that of RH suspensions, respectively. An in vivo pharmacokinetic study demonstrated significantly enhanced oral bioavailability of RH when encapsulated in DNPs, with 2.40- and 3.33-fold higher C_max and AUC_0-inf compared to RH suspensions, respectively. DNPs are promising delivery platforms for poorly absorbed drugs by oral administration.

FOXO4 ameliorates alcohol-induced chronic liver injury via inhibiting NF-κB and modulating gut microbiota in C57BL/6J mice

BACKGROUND

Intestinal mucosa barrier function and gut-liver axis are impaired by ethanol in chronic alcoholic liver disease (ALD). However, the possible mechanism is not clear. This study aimed to investigate the effects of Forkhead Box O4 (FOXO4) on alcohol-induced chronic liver injury and its molecular mechanism(s).

METHODS

Male C57BL/6J mice were injected with or without FOXO4-WT, FOXO4-TB or NF-κB vectors, and fed with Lieber-DeCarli liquid diets containing 36% ethanol for eight weeks to induce chronic ALD. Thereafter, blood, liver, colon and fecal samples were collected. Biochemical parameters, endotoxin and inflammatory cytokines in the blood and antioxidant enzymes in the liver were tested by commercial kits. Histopathological changes in the liver were evaluated by HE staining. In addition, the mRNA and protein expression of FOXO4, NF-κB, ZO-1 and Occluding in the colon were measured by quantitative real-time PCR and Western blot, respectively. Furthermore, gut microbiota composition in the fecal samples was investigated with 16S rDNA sequencing.

RESULTS

FOXO4 significantly ameliorated liver histopathological damage. Moreover, FOXO4 reduced the serum endotoxin, biochemical parameters (ALT, AST, ALP and TG), antioxidant enzymes (ROS and MDA), inflammatory cytokines (IL-6, IL-1β, and TNF-α), but restored the levels of GSH, SOD and IL-10. Furthermore, FOXO4 significantly inhibited the expression of NF-κB, p-NF-κB p65, p-IKKα and p-IKKβ, and up-regulated the expression of ZO-1 and Occludin. Additionally, FOXO4 modulated the gut microbiota composition and certain bacteria including Odoribacter, Parasutterella and Psychrobacter.

CONCLUSION

These findings suggest that FOXO4 protects against alcohol-induced chronic liver injury via inhibiting NF-κB and modulating gut microbiota in C57BL/6J mice.

Pure total flavonoids from citrus attenuate non-alcoholic steatohepatitis via regulating the gut microbiota and bile acid metabolism in mice

BACKGROUND

Our previous studies found that Pure total flavnoids from citrus (PTFC) can effectively improve non-alcoholic steatohepatitis (NASH) in mice. Here, we discuss on the mechanism of PTFC in treating NASH with focus on the regulation of the gut microbiota and bile acid metabolism.

METHODS

C57BL/6 J mice were randomly divided into three groups: normal diet group (Normal), high-fat diet group (HFD) and high-fat + PTFC treatment group (PTFC). Mice in the Normal group were fed chow diet, while the other groups were fed high fat diet (HFD) for 16 weeks. In the 5th week, the mice in the PTFC group were treated with 50 mg/kg/day PTFC for an additional twelve weeks. After sacrifice, histopathology of the liver was assessed, and the gut microbial composition was analyzed by 16S rDNA gene sequencing. Bile Acid profiles in serum were determined by ultraperformance liquid chromatography (UPLC-MS/MS).

RESULTS

PTFC intervention significantly attenuated HFD-induced NASH symptoms compared with the HFD group in mice. 16S rDNA sequencing showed that PTFC treatment increased the phylogenetic diversity of the HFD-induced microbiota dysbiosis. PTFC intervention significantly increased the relative abundances of Bacteroidaceae and Christensenellaceae. Furthermore, PTFC reduced the content of toxic bile acids, such as TDCA, DCA, TCA, CA and increased the ratio of secondary to primary bile acids. FXR and TGR5 deficiency were significantly alleviated.

CONCLUSION

PTFC can improve NASH via the the gut microbiota and bile acid metabolism.

Functions of nuclear receptors SUMOylation

The nuclear receptor superfamily is a family of ligand-activated transcription factors that play a key role in cell metabolism and human diseases. They can be modified after translation, such as acetylation, ubiquitination, phosphorylation and SUMOylation. Crosstalk between SUMO and ubiquitin, phosphorylation and acetylation regulates a variety of metabolic and physiological activities. Nuclear receptors play an important role in lipid metabolism, inflammation, bile acid homeostasis and autophagy. SUMOylation nuclear receptors can regulate their function and affect cell metabolism. It also provides a potential therapeutic target for atherosclerosis, tumor and other metabolic and inflammation-related diseases. This review focuses on the function of SUMOylation nuclear receptors.

Effect of different bile acids on the intestine through enterohepatic circulation based on FXR

Farnesoid X receptor (FXR) is a nuclear receptor for bile acids (BAs) that is widely expressed in the intestine, liver and kidney. FXR has important regulatory impacts on a wide variety of metabolic pathways (such as glucose, lipid, and sterol metabolism) and has been recognized to ameliorate obesity, liver damage, cholestasis and chronic inflammatory diseases. The types of BAs are complex and diverse. BAs link the intestine with the liver through the enterohepatic circulation. BAs derivatives have entered clinical trials for liver disease. In addition to the liver, the intestine is also targeted by BAs. This article reviews the effects of different BAs on the intestinal tract through the enterohepatic circulation from the perspective of FXR, aiming to elucidate the effects of different BAs on the intestinal tract and lay a foundation for new treatment methods.

Metabolite Sensing GPCRs: Promising Therapeutic Targets for Cancer Treatment?

G-protein-coupled receptors constitute the most diverse and largest receptor family in the human genome, with approximately 800 different members identified. Given the well-known metabolic alterations in cancer development, we will focus specifically in the 19 G-protein-coupled receptors (GPCRs), which can be selectively activated by metabolites. These metabolite sensing GPCRs control crucial processes, such as cell proliferation, differentiation, migration, and survival after their activation. In the present review, we will describe the main functions of these metabolite sensing GPCRs and shed light on the benefits of their potential use as possible pharmacological targets for cancer treatment.

ASBT(SLC10A2): A promising target for treatment of diseases and drug discovery

Bile acids has gradually become a new focus in various diseases, and ASBT as a transporter responsible for the reabsorption of ileal bile acids, is a key hinge associated to the bile acids-cholesterol balance and bile acids of enterohepatic circulation. The cumulative studies have also shown that ASBT is a promising target for treatment of liver, gallbladder, intestinal and metabolic diseases. This article briefly reviewed the process of bile acids enterohepatic circulation, as well as the regulations of ASBT expression, covering transcription factors, nuclear receptors and gut microbiota. In addition, the relationship between ASBT and various diseases were discussed in this paper. According to the structural classification of ASBT inhibitors, the research status of ASBT inhibitors and potential ASBT inhibitors of traditional Chinese medicine (such resveratrol, jatrorrhizine in Coptis chinensis) were summarized. This review provides a basis for the development of ASBT inhibitors and the treatment strategy of related diseases.

Teneligliptin Promotes Bile Acid Synthesis and Attenuates Lipid Accumulation in Obese Mice by Targeting the KLF15-Fgf15 Pathway

Bile acids (BAs) play essential physiological roles not only by facilitating the absorption and transport of nutrients but also by acting as a complex molecular signaling system. Reduced levels of BAs have been observed in obesity and other metabolic disorders. In the present study, we explored the effect of the dipeptidyl peptidase-4 (DPP-4) inhibitor teneligliptin on BA synthesis, both in vitro and in vivo. In our in vivo experiments, we found that teneligliptin increased the liver, ileal, and serum BA concentrations in mice undergoing teneligliptin treatment for 10 weeks. We further found that in mice fed a high-fat diet, teneligliptin prevented an increase in markers of obesity (body weight, total cholesterol, total triglyceride, adipocyte size) while increasing the total serum and ileal levels of BA. Mechanistically, teneligliptin increased BA synthesis through the alternative synthesis pathway, as the levels of both 7α-hydroxylase (CYP7A1) and sterol 27-hydroxylase (CYP27A1) along with downstream oxysterol 7α-hydroxylase (CYP7B1) but not sterol 12α-hydroxylase (CYP8B1) were increased. Importantly, teneligliptin suppressed the expression of the BA synthesis inhibitory factor Fgf15, which was mediated through phosphatidylinositol 3-kinase (PI3K)/AKT/Krüppel-like factor 15 (KLF15) signaling. Inhibition of KLF15 abolished this effect. Together, our results provide evidence of the potential benefit of teneligliptin in the treatment of metabolic disorders via increased BA production.

Evaluating the Efficacy of Taurodeoxycholic Acid in Providing Otoprotection Using an in vitro Model of Electrode Insertion Trauma

Cochlear implants (CIs) are widely used to provide auditory rehabilitation to individuals having severe to profound sensorineural hearing loss (SNHL). However, insertion of electrode leads to inner trauma and activation of inflammatory and apoptotic signaling cascades resulting in loss of residual hearing in implanted individuals. Pharmaceutical interventions that can target these signaling cascades hold great potential for preserving residual hearing by preventing sensory cell damage. Bile salts have shown efficacy in various regions of the body as powerful antioxidants and anti-inflammatory agents. However, their efficacy against inner ear trauma has never been explored. The objective of this study was to determine whether taurodeoxycholic acid (TDCA), a bile salt derivative, can prevent sensory cell damage employing an in vitro model of electrode insertion trauma (EIT). The organ of Corti (OC) explants were dissected from postnatal day 3 (P-3) rats and placed in serum-free media. Explants were divided into control and experimental groups: (1) untreated controls; (2) EIT; (3) EIT+ TDCA (different concentrations). Hair cell (HC) density, analyses of apoptosis pathway (cleaved caspase 3), levels of reactive oxygen species (ROS) as well as inducible nitric oxide synthase (iNOS) activity and Mitochondrial Membrane Potential (MMP) were assayed. Treatment with TDCA provided significant otoprotection against HC loss in a dose-dependent manner. The molecular mechanisms underlying otoprotection involved decreasing oxidative stress, lowering levels of iNOS, and abrogating generation of cleaved caspase 3. The results of the present study suggest that TDCA provides efficient otoprotection against EIT, in vitro and should be explored for developing pharmaceutical interventions to preserve residual hearing post-cochlear implantation.