A triple combination strategy of UHPLC-MSn, hypolipidemic activity and transcriptome sequencing to unveil the hypolipidemic mechanism of Nelumbo nucifera alkaloids.

ETHNOPHARMACOLOGICAL RELEVANCE: Nelumbo nucifera (N. nucifera), a kind of edible Chinese herbal, has been studied in treating hyperlipidemia. However, the hypolipidemic mechanism of N. nucifera remains unknown. Aims of this review: We aimed to screen the effective constituent of N. nucifera alkaloids and elucidated the potential mechanism for treating hyperlipidemia. A triple combination strategy of UHPLC-MSn, hypolipidemic activity and transcriptome sequencing was built to unveil the hypolipidemic mechanism of Nelumbo nucifera alkaloid. MATERIALS AND METHODS: We comprehensively investigated the characterization of N. nucifera alkaloids by using UHPLC-LTQ-Orbitrap MSn. And the hypolipidemic activity of candidate active ingredients were evaluated on sodium oleate-induced HepG2 cell. Finally, O-nornuciferine and N. nucifera alkaloid extraction were analyzed by RNA sequence (RNA-seq) to decipher the underlying hypolipidemic mechanism and were verified by qRT-PCR. RESULTS: 35 compounds were identified from N. nucifera alkaloid extraction by UHPLC-LTQ-Orbitrap MSn. Among them, O-nornuciferine and N. nucifera alkaloid extraction which showed significant hypolipidemic activity were analyzed by transcriptome sequencing. After the intervention of O-nornuciferine and N. nucifera alkaloid extraction, 1 and 158 differentially expressed genes (DEGs) were identified, severally. The enrichment analysis indicated that the hypolipidemic effect was adjusted by the expression of numerous key DEGs involved in bile secretion, glycerolipid and sphingolipid metabolism, PPAR signaling pathway. CONCLUSIONS: O-nornuciferine and N. nucifera alkaloids had exibited significant effects in hyperlipidemia. The candidate genes were LDLR, LPL and ANGPTL4, etc. It was most likely that they adjusted lipid metabolism by modulating expression levels of various key factors which were involved in bile secretion, glycerolipid metabolism, sphingolipid metabolism and PPAR signaling pathway, and so on. This study clarified the hypolipidemic mechanism of the alkaloids in N. nucifera, and laid a foundation for the subsequent development of clinical application and better quality of N. nucifera.

Circadian Angiopoietin-Like-4 as a Novel Therapy in Cardiovascular Disease.

Angiopoietin-like 4 (ANGPTL4) is critical for regulating plasma lipids, and thus an attractive therapeutic target for cardiovascular diseases. Unfortunately, targeting ANGPTL4 results in a proinflammatory and ultimately lethal phenotype in animals. The serendipitous discovery of cardiac ANGPTL4 as a circadian protein reveals novel mechanistic insight and a solution for this therapeutic dilemma.

Fructo-Oligosaccharides and Pectins Enhance Beneficial Effects of Raspberry Polyphenols in Rats with Nonalcoholic Fatty Liver.

In recent years, nonalcoholic fatty liver disorders have become one of the most common liver pathologies; therefore, it is necessary to investigate the dietary compounds that may support the regulation of liver metabolism and related inflammatory processes. The present study examines the effect of raspberry polyphenolic extract (RE) combined with fructo-oligosaccharides (FOSs) or pectins (PECs) on caecal microbial fermentation, liver lipid metabolism and inflammation in rats with fatty liver induced by an obesogenic diet. The combination of RE with FOSs or PECs reduced the production of short-chain fatty acids in the caecum. RE combined with FOSs exerted the most favourable effects on liver lipid metabolism by decreasing liver fat, cholesterol, triglyceride content and hepatic steatosis. RE and FOSs reduced lobular and portal inflammatory cell infiltration and IL-6 plasma levels. These effects might be related to a decrease in the hepatic expressions of PPARγ and ANGPTL4. In conclusion, PECs and FOSs enhanced the effects of RE against disorders related to nonalcoholic fatty liver; however, the most effective dietary treatment in the regulation of liver lipid metabolism and inflammation caused by an obesogenic diet was the combination of RE with FOSs.

Regulation of gene transcription by thyroid hormone receptor ß agonists in clinical development for the treatment of non-alcoholic steatohepatitis (NASH).

Thyroid hormones are important modulators of metabolic activity in mammals and alter cholesterol and fatty acid levels through activation of the nuclear thyroid hormone receptor (THR). Currently, there are several THRß agonists in clinical trials for the treatment of non-alcoholic steatohepatitis (NASH) that have demonstrated the potential to reduce liver fat and restore liver function. In this study, we tested three THRß-agonism-based NASH treatment candidates, GC-1 (sobetirome), MGL-3196 (resmetirom), and VK2809, and compared their selectivity for THRß and their ability to modulate the expression of genes specific to cholesterol and fatty acid biosynthesis and metabolism in vitro using human hepatic cells and in vivo using a rat model. Treatment with GC-1 upregulated the transcription of CPT1A in the human hepatocyte-derived Huh-7 cell line with a dose-response comparable to that of the native THR ligand, triiodothyronine (T3). VK2809A (active parent of VK2809), MGL-3196, and VK2809 were approximately 30-fold, 1,000-fold, and 2,000-fold less potent than T3, respectively. Additionally, these relative potencies were confirmed by quantification of other direct gene targets of THR, namely, ANGPTL4 and DIO1. In primary human hepatocytes, potencies were conserved for every compound except for VK2809, which showed significantly increased potency that was comparable to that of its active counterpart, VK2809A. In high-fat diet fed rats, a single dose of T3 significantly reduced total cholesterol levels and concurrently increased liver Dio1 and Me1 RNA expression. MGL-3196 treatment resulted in concentration-dependent decreases in total and low-density lipoprotein cholesterol with corresponding increases in liver gene expression, but the compound was significantly less potent than T3. In conclusion, we have implemented a strategy to rank the efficacy of THRß agonists by quantifying changes in the transcription of genes that lead to metabolic alterations, an effect that is directly downstream of THR binding and activation.

Tongxinluo attenuates oxygen-glucose-serum deprivation/restoration-induced endothelial barrier breakdown via peroxisome proliferator activated receptor-α/angiopoietin-like 4 pathway in high glucose-incubated human cardiac microvascular endothelial cells.

BACKGROUND: Traditional Chinese medicine Tongxinluo (TXL) has been widely used to treat coronary artery disease in China, since it could reduce myocardial infarct size and ischemia/reperfusion injury in both non-diabetic and diabetic conditions. It has been shown that TXL could regulate peroxisome proliferator activated receptor-α (PPAR-α), a positive modulator of angiopoietin-like 4 (Angptl4), in diabetic rats. Endothelial junction substructure components, such as VE-cadherin, are involved in the protection of reperfusion injury. Thus, we hypothesized cell-intrinsic and endothelial-specific Angptl4 mediated the protection of TXL on endothelial barrier under high glucose condition against ischemia/reperfusion-injury via PPAR-α pathway. METHODS: Incubated with high glucose medium, the human cardiac microvascular endothelial cells (HCMECs) were then exposed to oxygen-glucose-serum deprivation (2 hours) and restoration (2 hours) stimulation, with or without TXL, insulin, or rhAngptl4 pretreatment. RESULTS: TXL, insulin, and rhAngptl4 had similar protective effects on the endothelial barrier. TXL treatment reversed the endothelial barrier breakdown in HCMECs significantly as identified by decreasing endothelial permeability, upregulating the expression of JAM-A, VE-cadherin, and integrin-α5 and increasing the membrane location of VE-cadherin and integrin-α5, and these effects of TXL were as effective as insulin and rhAngptl4. However, Angptl4 knock-down with small interfering RNA (siRNA) interference and PPAR-α inhibitor MK886 partially abrogated these beneficial effects of TXL. Western blotting also revealed that similar with insulin, TXL upregulated the expression of Angptl4 in HCMECs, which could be inhibited by Angptl4 siRNA or MK886 exposure. TXL treatment increased PPAR-α activity, which could be diminished by MK886 but not by Angptl4 siRNA. CONCLUSION: These data suggest cell-intrinsic and endothelial-specific Angptl4 mediates the protection of TXL against endothelial barrier breakdown during oxygen-glucose-serum deprivation and restoration under high glucose condition partly via the PPAR-α/Angptl4 pathway.

Mining the role of angiopoietin-like protein family in gastric cancer and seeking potential therapeutic targets by integrative bioinformatics analysis.

BACKGROUND: The indistinctive effects of antiangiogenesis agents in gastric cancer (GC) can be attributed to multifaceted gene dysregulation associated with angiogenesis. Angiopoietin-like (ANGPTL) proteins are secreted proteins regulating angiogenesis. They are also involved in inflammation and metabolism. Emerging evidences have revealed their various roles in carcinogenesis and metastasis development. However, the mRNA expression profiles, prognostic values, and biological functions of ANGPTL proteins in GC are still elucidated. METHODS: We compared the transcriptional expression levels of ANGPTL proteins between GC and normal gastric tissues using ONCOMINE and TCGA-STAD. The prognostic values were evaluated by LinkedOmics and Kaplan-Meier Plotter, while the association of expression levels with clinicopathological features was generated through cBioPortal. We conducted the functional enrichment analysis with Metascape. RESULTS: The expression of ANGPTL1/3/6 was lower in GC tissues than in normal gastric tissues. High expression of ANGPTL1/2/4 was correlated with short overall survival and post-progression survival in GC patients. Upregulated ANGPTL1/2 was correlated with higher histological grade, non-intestinal Lauren classification, and advanced T stage, while ANGPTL4 exhibited high expression in early T stage, M1 stage, and non-intestinal Lauren classification. CONCLUSIONS: Integrative bioinformatics analysis suggests that ANGPTL1/2/4 may be potential therapeutic targets in GC patients. Among them, ANGPTL2 acts as a GC promoter, while ANGPTL1/4's role in GC is still uncertain.

Urtica dioica Whole Vegetable as a Functional Food Targeting Fat Accumulation and Insulin Resistance-a Preliminary Study in a Mouse Pre-Diabetic Model.

The shoot of Urtica dioica is used in several cultures as a vegetable or herb. However, not much has been studied about the potential of this plant when consumed as a whole food/vegetable rather than an extract for dietary supplements. In a 12-week dietary intervention study, we tested the effect of U. dioica vegetable on high fat diet induced obesity and insulin resistance in C57BL/6J mice. Mice were fed ad libitum with isocaloric diets containing 10% fat or 45% fat with or without U. dioica. The diet supplemented with U. dioica attenuated high fat diet induced weight gain (p < 0.005; n = 9), fat accumulation in adipose tissue (p < 0.005; n = 9), and whole-body insulin resistance (HOMA-IR index) (p < 0.001; n = 9). Analysis of gene expression in skeletal muscle showed no effect on the constituents of the insulin signaling pathway (AKT, IRS proteins, PI3K, GLUT4, and insulin receptor). Notable genes that impact lipid or glucose metabolism and whose expression was changed by U. dioica include fasting induced adipocyte factor (FIAF) in adipose and skeletal muscle, peroxisome proliferator-activated receptor-α (Ppar-α) and forkhead box protein (FOXO1) in muscle and liver, and Carnitine palmitoyltransferase I (Cpt1) in liver (p < 0.01). We conclude that U. dioica vegetable protects against diet induced obesity through mechanisms involving lipid accumulation and glucose metabolism in skeletal muscle, liver, and adipose tissue.

Tandem mass tag-based proteomic analysis reveals the treatment mechanism of Bushen Huoxue Formula on psychological stress-induced premature ovarian insufficiency.

ETHNOPHARMACOLOGICAL RELEVANCE: Bushen Huoxue formula (BSHXF) is a Chinese herbal prescription composed of eleven herbs widely used to treat psychological stress-induced premature ovarian insufficiency (POI) in clinical. However, the underlying mechanism is still unclear. AIM OF THE STUDY: The purpose of this study was to clarify the underlying molecular mechanisms of BSHXF in the treatment of psychological stress-induced POI. MATERIALS AND METHODS: The rat model was induced by corticosterone (CORT, 40mg/kg). Drugs were administered to rats once daily for 21 days. The serum E2, FSH and AMH levels were examined by enzyme-linked immunosorbent assays. Tandem mass tag-based proteomic analysis was used to identify differentially expressed proteins. Western blot was used to verify the results of proteomic. RESULTS: Our results indicate that BSHXF can improve ovarian disfunction. The levels of serum FSH were signally enhanced in model group compared to control group. As respected, BSHXF treatment for 3 weeks led to the decreased FSH levels than the model group. The concentrations of AMH showed an obvious decrease in the model group and were increased by BSHXF treatment. Moreover, the size and number of follicles in the BSHXF groups were similar to those in the control group. The proteomic screened out that Np4 and Angptl4 were simultaneously enriched by GO and KEGG, thus these two proteins were chosen for further study. CONCLUSIONS: These findings revealed that BSHXF might regulate the expression of Np4 and Angptl4 to improve psychological stress-induced POI.

Therapeutic and antiproteinuric effects of salvianolic acid A in combined with low-dose prednisone in minimal change disease rats: Involvement of PPARγ/Angptl4 and Nrf2/HO-1 pathways.

Danshen (Salvia miltiorrhiza) and prednisone are extensively applied in the treatment of kidney disease. Salvianolic acid A (SAA), the major biologically active component of Danshen, which has various biological effects. Our previous findings have demonstrated the renoprotective effect of SAA in various kidney disease rodent models. Here, we explore the therapeutic potential and possible mechanisms of SAA in combination with low-dose prednisone in adriamycin (ADR)-induced minimal change disease (MCD) rat model and mouse podocyte injury cell model. SAA was injected via tail vein at 10 mg/kg/day and prednisone at 5 mg/kg/day via gavage. Each drug was administered daily alone or in combination for 3 weeks. Combination therapy showed significant therapeutic efficacy as manifested by relieved urinary proteins, improved blood biochemical indicators including serum total protein, albumin, triglyceride, cholesterol, the indices of renal function i.e. blood urea nitrogen and serum creatinine levels, and ameliorated pathological lesions. Particularly, co-administration showed a significant anti-proteinuria effect in MCD rats. Further studies suggested that co-administration effectively ameliorated the podocyte injury as indicated by the reduction of podocyte foot processes fusion, up-regulation of synaptopodin and down-regulation of desmin. These beneficial effects are accompanied by activation of the Nrf2/HO-1 and PPARγ/Angptl4 pathways in vivo, and the effect of SAA on PPARγ/Angptl4 is also demonstrated in vitro. These findings suggested that SAA exerted podocyte-protection against MCD injury through PPARγ/Angptl4 and Nrf2/HO-1 pathways, and combined with low-dose prednisone possessed a significant anti-proteinuria and therapeutic effects in MCD rats.

Intestinal vitamin D receptor modulates lipid metabolism, adipose tissue inflammation and liver steatosis in obese mice.

OBJECTIVE: Hypovitaminosis D is common in the obese population and patients suffering from obesity-associated disorders such as type 2 diabetes and fatty liver disease, resulting in suggestions for vitamin D supplementation as a potential therapeutic option. However, the pathomechanistic contribution of the vitamin D-vitamin D receptor (VDR) axis to metabolic disorders is largely unknown. METHODS: We analyzed the pathophysiological role of global and intestinal VDR signaling in diet-induced obesity (DIO) using global Vdr-/- mice and mice re-expressing an intestine-specific human VDR transgene in the Vdr deficient background (Vdr-/- hTg). RESULTS: Vdr-/- mice were protected from DIO, hepatosteatosis and metabolic inflammation in adipose tissue and liver. Furthermore, Vdr-/- mice displayed a decreased adipose tissue lipoprotein lipase (LPL) activity and a reduced capacity to harvest triglycerides from the circulation. Intriguingly, all these phenotypes were partially reversed in Vdr-/- hTg animals. This clearly suggested an intestine-based VDR activity on systemic lipid homeostasis. Scrutinizing this hypothesis, we identified the potent LPL inhibitor angiopoietin-like 4 (Angptl4) as a novel transcriptional target of VDR. CONCLUSION: Our study suggests a VDR-mediated metabolic cross-talk between gut and adipose tissue, which significantly contributes to systemic lipid homeostasis. These results have important implications for use of the intestinal VDR as a therapeutic target for obesity and associated disorders.

Preventive effect of Tongxinluo on endothelial survival and vascular integrity, together with inhibition of inflammatory reaction in rats model of intestine ischemia/reperfusion injury.

This study was design to investigate preventive function of Tongxinluo (TXL) capsule on micro vascular function and endothelial survival in rats model of intestine ischemia/reperfusion (I/R) injury. We randomly divided fifty male Sprague-Dawley rats into Sham group, I/R group, TXL0.4+I/R group, TXL0.8+I/R group, TXL1.6+I/R group (10 rats each). Rat intestine I/R injury was carried out using a model of acute superior mesenteric artery occlusion with 30 min ischemia followed by 60 min reperfusion. The distribution of endothelial apoptosis in intestine was determined by CD31+TUNEL immunofluorescent double staining analysis. VE-Cadherin, ANGPTL4, HMGB1 and NF-κB were determined by immunohistochemical analysis. I/R induced massively endothelial cell apoptosis, accompanied with reduced expression of adherens junction protein VE-Cadherin and up regulation of inflammatory mediator HMGB1 and NF-κB. TXL pretreatment groups (TXL0.4+I/R, TXL0.8+I/R and TXL1.6+I/R group) significantly attenuated endothelial cell apoptosis with a dose-dependent effect. TXL pretreatment could maintain the expression of VE-Cadherin and promote the expression of ANGPTL4 which help to maintain endothelial integrity. TXL pretreatment also exert great influence in inhibiting HMGB1 expression and NF-κB expression induced by I/R. It could be concluded from this study that micro vascular dysfunction and endothelial damage play a causal role in rat intestine I/R injury. TXL pretreatment could significantly prevent the I/R induced pathology of endothelial apoptosis, micro vascular integrity disruption and inflammatory reaction.

Tongxinluo attenuates reperfusion injury in diabetic hearts by angiopoietin-like 4-mediated protection of endothelial barrier integrity via PPAR-α pathway.

OBJECTIVE: Endothelial barrier function in the onset and Tongxinluo (TXL) protection of myocardial ischemia/reperfusion (I/R) injury, and TXL can induce the secretion of Angiopoietin-like 4 (Angptl4) in human cardiac microvascular endothelial cells during hypoxia/reoxygenation. We intend to demonstrate whether TXL can attenuate myocardial I/R injury in diabetes, characterized with microvascular endothelial barrier disruption, by induction of Angptl4-mediated protection of endothelial barrier integrity. METHODS AND RESULTS: I/R injury was created by coronary ligation in ZDF diabetic and non-diabetic control rats. The animals were anesthetized and randomized to sham operation or I/R injury with or without the exposure to insulin, rhAngptl4, TXL, Angptl4 siRNA, and the PPAR-α inhibitor MK886. Tongxinluo, insulin and rhAngptl4 have the similar protective effect on diabetic hearts against I/R injury. In I/R-injured diabetic hearts, TXL treatment remarkably reduced the infarct size, and protected endothelial barrier integrity demonstrated by decreased endothelial cells apoptosis, microvascular permeability, and myocardial hemorrhage, fortified tight junction, and upregulated expression of JAM-A, integrin-α5, and VE-cadherin, and these effects of TXL were as effective as insulin and rhAngptl4. However, Angptl4 knock-down with siRNA interference and inhibition of PPAR-α with MK886 partially diminished these beneficial effects of TXL and rhAngptl4. TXL induced the expression of Angptl4 in I/R-injured diabetic hearts, and was canceled by Angptl4 siRNA and MK886. TXL treatment increased myocardial PPAR-α activity, and was abolished by MK886 but not by Angptl4 siRNA. CONCLUSIONS: TXL protects diabetic hearts against I/R injury by activating Angptl4-mediated restoration of endothelial barrier integrity via the PPAR-α pathway.

Buyang Huanwu Tang improves denervation-dependent muscle atrophy by increasing ANGPTL4, and increases NF-κB and MURF1 levels.

Denervated-dependent skeletal muscle atrophy (DSMA) is a disorder caused by the peripheral neuro­disconnection of skeletal muscle. The current study aimed to investigate the molecular mechanism and potential therapeutic strategies for the DSMA. A DSMA rat model was established. A lentiviral vector expressing small interfering RNA (siRNA) targeting angiopoietin­like protein 4 (ANGPTL4) was generated and injected into the rats that were also treated with Buyang Huanwu Tang (BYHWT). Reverse transcription­quantitative polymerase chain reaction was performed to examine ANGPTL4 mRNA expression in anterior cervical muscle samples. Western blot assay was used to evaluate ANGPTL4, nuclear factor­κB (NF­κB) and muscle RING­finger protein­1 (MURF1) expression. The ultrastructure of muscle tissues was viewed using transmission electron microscopy. The cell apoptosis in muscle tissues was detected using the terminal deoxynucleotidyl transferase dUTP nick end labeling. The results indicated that BYHWT treatment increased ANGPTL4 mRNA and protein levels in muscle tissues. The suppression of ANGPTL4 using siRNA significantly increased inflammatory cells compared with the control siRNA group. BYHWT protected the ultrastructure muscle tissues and inhibited cell apoptosis in the DSMA model. The protective effect of BYHWT protected may be mediated by increased expression of NF­κB p65 and MURF1. In conclusion, BYHWT may improve denervation­dependent muscle atrophy by increasing ANGPTL4 expression, involving NF­κB and MURF1 signaling.

Paeoniflorin ameliorates Adriamycin-induced nephrotic syndrome through the PPARγ/ANGPTL4 pathway in vivo and vitro.

Paeoniflorin (PF), an effective composition that is extracted from Radix Paeoniae Alba, plays a role in protecting against various kidney diseases. However, the mechanism of PF on nephrotic syndrome (NS) remains unclear. The aim of this study was to investigate the protective role of PF on Adriamycin (ADR)-induced NS in vivo and vitro as well as its potential mechanism. In animal study, PF significantly decreased the levels of 24-h urine protein, blood urea nitrogen, serum creatinine, total cholesterol and triglycerides in NS rats, but increased the total protein and albumin levels. Hematoxylin-eosin (HE) staining revealed that the kidney lesion was resolved upon PF treatment. After treatment with PF, the morphology and number of podocytes in renal tissue were restored to normal. PF increased expression of synaptopodin and decreased expression of desmin, demonstrating a protective effect in podocyte injury. Further studies revealed that PF upregulated Peroxisome proliferator-activated receptor gamma (PPARγ) and restrained Angiopointin-like 4 (ANGPTL4) in kidney tissue. In vitro study, PF reduced Caspase3 and Bax and increased Bcl-2, indicating that the apoptosis rate of podocytes induced by ADR was reduced by PF. Furthermore, PF ameliorated podocyte injury by upregulating synaptopodin and reducing desmin. In accordance with animal study, PF downregulated ANGPTL4 by activating PPARγ. However, the therapeutic effects of PF were reversed by GW9662 (PPARγ inhibitor), likely by suppressing ANGPTL4 degradation. In general, these results demonstrate that PF has a good therapeutic effect on NS by activating PPARγ and subsequently inhibiting ANGPTL4.

ANGPTL4 promotes bile acid absorption during taurocholic acid supplementation via a mechanism dependent on the gut microbiota.

Angiopoietin-like 4 (ANGPTL4) raises plasma triglyceride levels by inhibiting lipoprotein lipase. A set of compounds that are able to reduce plasma triglyceride levels are bile acids (BA). Because BA have been shown to decrease ANGPTL4 secretion by intestinal cells, we hypothesized that BA lower plasma triglycerides (partly) via ANGPTL4. To test that hypothesis, wild-type and Angptl4-/- mice were fed chow supplemented with taurocholic acid (TCA) for seven days. TCA supplementation effectively lowered plasma triglycerides in wild-type and Angptl4-/- mice, indicating that ANGPTL4 is not required for plasma triglyceride-lowering by BA. Intriguingly, however, plasma and hepatic BA concentrations were significantly lower in TCA-supplemented Angptl4-/- mice than in TCA-supplemented wild-type mice. These changes in the Angptl4-/- mice were accompanied by lower BA levels in ileal scrapings and decreased expression of FXR-target genes in the ileum, including the BA transporter Slc10a2. By contrast, faecal excretion of specifically primary BA was higher in the Angptl4-/- mice, suggesting that loss of ANGPTL4 impairs intestinal BA absorption. Since the gut microbiota converts primary BA into secondary BA, elevated excretion of primary BA in Angptl4-/- mice may reflect differences in gut microbial composition and/or functionality. Indeed, colonic microbial composition was markedly different between Angptl4-/- and wild-type mice. Suppression of the gut bacteria using antibiotics abolished differences in plasma, hepatic, and faecal BA levels between TCA-supplemented Angptl4-/- and wild-type mice. In conclusion, 1) ANGPTL4 is not involved in the triglyceride-lowering effect of BA; 2) ANGPTL4 promotes BA absorption during TCA supplementation via a mechanism dependent on the gut microbiota.