Taurochenodeoxycholic acid induces apoptosis of fibroblast-like synoviocytes

Bile acid metabolism regulatory network orchestrates bone homeostasis

Bile acids (BAs), synthesized in the liver and modified by the gut microbiota, have been widely appreciated not only as simple lipid emulsifiers, but also as complex metabolic regulators and momentous signaling molecules, which play prominent roles in the complex interaction among several metabolic systems. Recent studies have drawn us eyes on the diverse physiological functions of BAs, to enlarge the knowledge about the "gut-bone" axis due to the participation about the gut microbiota-derived BAs to modulate bone homeostasis at physiological and pathological stations. In this review, we have summarized the metabolic processes of BAs and highlighted the crucial roles of BAs targeting bile acid-activated receptors, promoting the proliferation and differentiation of osteoblasts (OBs), inhibiting the activity of osteoclasts (OCs), as well as reducing articular cartilage degradation, thus facilitating bone repair. In addition, we have also focused on the bidirectional effects of BA signaling networks in coordinating the dynamic balance of bone matrix and demonstrated the promising effects of BAs on the development or treatment for pathological bone diseases. In a word, further clinical applications targeting BA metabolism or modulating gut metabolome and related derivatives may be developed as effective therapeutic strategies for bone destruction diseases.

Parabacteroides distasonis ameliorates hepatic fibrosis potentially via modulating intestinal bile acid metabolism and hepatocyte pyroptosis in male mice

Parabacteroides distasonis (P. distasonis) plays an important role in human health, including diabetes, colorectal cancer and inflammatory bowel disease. Here, we show that P. distasonis is decreased in patients with hepatic fibrosis, and that administration of P. distasonis to male mice improves thioacetamide (TAA)- and methionine and choline-deficient (MCD) diet-induced hepatic fibrosis. Administration of P. distasonis also leads to increased bile salt hydrolase (BSH) activity, inhibition of intestinal farnesoid X receptor (FXR) signaling and decreased taurochenodeoxycholic acid (TCDCA) levels in liver. TCDCA produces toxicity in mouse primary hepatic cells (HSCs) and induces mitochondrial permeability transition (MPT) and Caspase-11 pyroptosis in mice. The decrease of TCDCA by P. distasonis improves activation of HSCs through decreasing MPT-Caspase-11 pyroptosis in hepatocytes. Celastrol, a compound reported to increase P. distasonis abundance in mice, promotes the growth of P. distasonis with concomitant enhancement of bile acid excretion and improvement of hepatic fibrosis in male mice. These data suggest that supplementation of P. distasonis may be a promising means to ameliorate hepatic fibrosis.

Bile acids as regulatory molecules and potential targets in metabolic diseases

Bile acids are important hydroxylated steroids that are synthesized in the liver from cholesterol for intestinal absorption of lipids and other fatty-nutrient. They also display remarkable and immense functions such as regulating immune responses, managing the apoptosis of cells, participating in glucose metabolism, and so on. Some bile acids were used for the treatment or prevention of diseases such as gallstones, primary biliary cirrhosis, and colorectal cancer. Meanwhile, the accumulation of toxic bile acids leads to apoptosis, necrosis, and inflammation. Alteration of bile acids metabolism, as well as the gut microbiota that interacted with bile acids, contributes to the pathogenesis of metabolic diseases. Therefore, the purpose of this review is to summarize the current functions and pre-clinical or clinical applications of bile acids, and to further discuss the alteration of bile acids in metabolic disorders as well as the manipulation of bile acids metabolism as potential therapeutic targets.

Taurochenodeoxycholic Acid Increases cAMP Content via Specially Interacting with Bile Acid Receptor TGR5

Taurochenodeoxycholic acid (TCDCA) is one of the main components of bile acids (BAs). TCDCA has been reported as a signaling molecule, exerting anti-inflammatory and immunomodulatory functions. However, it is not well known whether those effects are mediated by TGR5. This study aimed to elucidate the interaction between TCDCA and TGR5. To achieve this aim, first, the TGR5 eukaryotic vector was constructed. The expression level of TGR5 in 293T cells was determined by immunofluorescence, real-time quantitative PCR (RT-PCR, qPCR), and Western blot. The luciferase assay, fluorescence microscopy, and enzyme-linked immunosorbent assay (ELISA) were recruited to check the interaction of TCDCA with TGR5. TCDCA treatment in 293T cells resulted in TGR5 internalization coupled with a significant increase in cAMP luciferase expression. Our results demonstrated that TCDCA was able to bind to the TGR5 receptor and activate it. These results provide an excellent potential therapeutic target for TCDCA research. Moreover, these findings also provide theoretical evidence for further TCDCA research.

2-Deoxy-D-glucose Alleviates Collagen-Induced Arthritis of Rats and Is Accompanied by Metabolic Regulation of the Spleen and Liver

Rheumatoid arthritis (RA) is significantly associated with glycolysis. This study used 2-deoxy-D-glucose (2-DG), an inhibitor of glycolysis, to treat rats with collagen-induced arthritis (CIA) and investigate the metabolic regulatory mechanism of glycolysis in the disease. 2-DG significantly alleviated CIA. Metabolomics and transcriptomics, as well as their integrative analysis, detected significant changes in the pathways of bile secretion, cholesterol and linoleic acid metabolism in the plasma, liver and spleen during the CIA process and the opposite changes following 2-DG treatment, whereas the expression of the genes regulating these metabolic pathways were changed only in the spleen. In the rat liver, levels of (S)-5-diphosphomevalonic acid in the terpenoid backbone biosynthesis pathway were significantly decreased during CIA progression and increased following 2-DG treatment, and levels of taurochenodeoxycholic acid in the pentose and glucuronate interconversions pathway showed the opposite results. In the spleen, levels of 3-methoxy-4-hydroxyphenylglycol glucuronide in bile secretion and 12(S)-leukotriene B4 in arachidonic acid metabolism were significantly decreased during CIA progression and increased following 2-DG treatment. The changes in the gene-metabolite network of bile secretion in the spleen correlated with a decreased plasma L-acetylcarnitine level in CIA rats and an increase following 2-DG treatment. Our analysis suggests the involvement of spleen and liver metabolism in CIA under the control of glycolysis.

A systematic review of preclinical studies on the efficacy of taurine for the treatment of rheumatoid arthritis

Due to the undesirable effects of conventional medical therapies prescribed for rheumatoid arthritis (RA), complementary therapies, especially nutritional agents, have recently gained great attention. Recent animal and in vitro researches have shown benefits of taurine (Tau), a sulfur-containing amino acid, in RA and suggest that Tau may be a therapeutic candidate in RA; however, no systematic review exists regarding Tau and RA. Accordingly, this paper systematically reviewed the available researches regarding Tau and RA and plausible underlying mechanisms. We searched electronic databases like Scopus, WOS, PubMed, Embase, ProQuest, Cochrane Library, and a search engine Google Scholar until December 2020 and we have applied search alert services to detect related papers published after the primary search. We did not have any restriction in publication date and/or language. We found no clinical study; thus we considered related animal and in vitro researches. Furthermore, we checked the citations or references of these researches and grey literature to detect possible studies. We did not consider reviews, book chapters, conference abstracts, and articles about Tau in health problems other than RA. Eighteen articles were entered in present systematic review. Animal and in vitro researches showed that Tau either directly or indirectly (via Tau derivatives such as Tau-chloramine, Tau-bromamine, taurochenodeoxycholic acid, and taurolidine) could control RA by different mechanisms such as reducing inflammation, suppressing oxidative stress, and inducing apoptosis. This review serves convincing clues about the efficacy of Tau in RA and explains the importance of additional clinical investigations.

Transcriptome investigation of anti-inflammation and immuno-regulation mechanism of taurochenodeoxycholic acid

BACKGROUND

Taurochenodeoxycholic acid (TCDCA) is one of the major active components in bile acid. It was proven to have inhibitory activities on inflammation and also participate in host immuno-regulation. TCDCA exerts anti-inflammatory and immuno-regulatory effects through the glucocorticoid receptor (GR) mediated genomic signaling pathway and the G protein-coupled bile acid receptor 5 (TGR5) mediated AC-cAMP-PKA signaling pathway. However, it is unclear whether GR or TGR5 plays an important role in the regulatory effects of TCDCA. In order to further investigate this effects mechanism of TCDCA, the research use the transcriptome to identify the major genes and pathway in the anti-inflammatory and immuno-regulatory effects.

METHODS

After the Fibroblast-like synoviocytes (FLS) being treated by different concentrations (10- 5, 10- 6 and 10- 7 M) of TCDCA for 12 h, the resulting mRNA was analyzed by RNA-seq. The differentially expressed genes were screened from sequencing results using bioinformatics techniques. In the next step, other published literature were referred in order to find out whether those genes mentioned above are related to inflammation. The final selected differentially expressed genes associated with inflammation were then validated by q-PCR and western blot assays.

RESULTS

Five genes associated with anti-inflammatory and immuno-regulatory effects, include Glyceraldehyde-3-phosphate dehydrogenase (GAPDH), Glutathione peroxidase 3 (GPX3), Serine/arginine-rich splicing factor-9 (SRSF9), Connective tissue growth factor (CTGF) and Cystatin B (CSTB) were identified. TCDCA at the concentrations of 10- 5, 10- 6 and 10- 7 M significantly (p < 0.05) up-regulate the mRNA and protein expression of SRSF9 and GPX3 and also up-regulate the mRNA expression of CSTB, CTGF and GAPDH. RNA-seq results of GPX3 and SRSF9 expression were consistent with q-PCR results, while q-PCR results of CTGF, GAPDH showed inconsistent with their RNA-seq results. Q-PCR result of CSTB expression also showed inconsistent with the RNA-seq result.

CONCLUSIONS

The anti-inflammatory and immuno-regulatory activities of TCDCA are proven to be related to the up-regulation expression of GPX3, SRSF9 and CSTB.

Circulating Pro- and Anti-Inflammatory Metabolites and Its Potential Role in Rheumatoid Arthritis Pathogenesis

Rheumatoid arthritis (RA) is a chronic systemic autoimmune disease that affects synovial joints, leading to inflammation, joint destruction, loss of function, and disability. Although recent pharmaceutical advances have improved the treatment of RA, patients often inquire about dietary interventions to improve RA symptoms, as they perceive pain and/or swelling after the consumption or avoidance of certain foods. There is evidence that some foods have pro- or anti-inflammatory effects mediated by diet-related metabolites. In addition, recent literature has shown a link between diet-related metabolites and microbiome changes, since the gut microbiome is involved in the metabolism of some dietary ingredients. But diet and the gut microbiome are not the only factors linked to circulating pro- and anti-inflammatory metabolites. Other factors including smoking, associated comorbidities, and therapeutic drugs might also modify the circulating metabolomic profile and play a role in RA pathogenesis. This article summarizes what is known about circulating pro- and anti-inflammatory metabolites in RA. It also emphasizes factors that might be involved in their circulating concentrations and diet-related metabolites with a beneficial effect in RA.

Taurochenodeoxycholic Acid Inhibited AP-1 Activation via Stimulating Glucocorticoid Receptor

Taurochenodeoxycholic acid (TCDCA) as a primary bioactive substance of animal bile has been shown to exert good anti-inflammatory and immunomodulatory functions in adjuvant arthritis in rats. The anti-inflammatory and immunomodulatory properties of TCDCA have exhibited interesting similarities with the effects of glucocorticoids (GCs). To investigate the potential mechanisms of TCDCA in anti-inflammation and immunomodulation, we used a luciferase reporter assay to evaluate the activation of the glucocorticoid receptor (GR) stimulated by TCDCA. Our results showed that GR was activated by TCDCA in a concentration-dependent manner. Moreover, the elevated expressions of c-Fos and phosphorylated c-Jun induced by interleukin-1β (IL-1β) were reversed by TCDCA. The inhibition of TCDCA on the transactivation of activator protein-1 (AP-1) was observed as well. However, the suppression of TCDCA on the phosphorylation of c-Jun was blocked incompletely by GR inhibitor RU486. These results have indicated that the anti-inflammatory and immunomodulatory functions of TCDCA involve multiple pathways, with contributions from GR and its related AP-1 signaling pathway.

Postprandial Responses of Serum Bile Acids in Healthy Humans after Ingestion of Turmeric before Medium/High-Fat Breakfasts

SCOPE

Bile acids (BAs) are known to regulate a number of metabolic activities in the body. However, very little is known about how BAs are affected by diet. This study aims to investigate whether a single dose of turmeric-based beverage (TUR) before ingestion of medium- (MF) or high-fat (HF) breakfasts would improve the BA profile in healthy subjects.

METHODS AND RESULTS

Twelve healthy subjects are assigned to a randomized crossover single-blind study. The subjects receive isocaloric MF or HF breakfasts after a drink containing flavored water with or without an extract of turmeric with at least 1-week wash-out period between the treatments. Postprandial BAs are measured using protein precipitation followed by ultra-high-performance liquid chromatography-mass spectrometry analysis. The concentration of BAs is generally higher after HF than MF breakfasts. Ingestion of TUR before MF breakfast increases the serum concentrations of free and conjugated forms of cholic (CA) and ursodeoxycholic acids (UDCA), as well as the concentrations of chenodeoxycholic acid (CDCA) and its taurine-conjugated forms. However, the concentration of conjugated forms of deoxycholic acid (DCA) decreases when TUR is taken before HF breakfast.

CONCLUSION

TUR ingestion before MF and HF breakfasts improve BA profiles and may therefore have potential health-promoting effects on BA metabolism.

Bufalin exerts inhibitory effects on IL-1β-mediated proliferation and induces apoptosis in human rheumatoid arthritis fibroblast-like synoviocytes

Rheumatoid arthritis fibroblast-like synoviocytes (RAFLSs) proliferate abnormally and resist apoptosis. Bufalin inhibits cell proliferation and induces apoptosis in human cancer cells. In this study, we explored the effects of bufalin on interleukin-1beta (IL-1β)-induced proliferation and apoptosis of RAFLSs. The cell proliferation and apoptosis were measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazoliumbromide assay and annexin V/propidium iodide staining, respectively. Bufalin dose-dependently inhibited IL-1β-induced RAFLS proliferation. Mechanistically, bufalin decreased the activation of mitogen-activated protein kinases (MAPKs) and nuclear factor-kappa B (NF-κB), both of which are involved in IL-1β-mediated RAFLS proliferation. Moreover, bufalin induced apoptosis and mitochondrial damage of RAFLSs, which was associated with Bcl-2 downregulation, Bax upregulation, mitochondrial cytochrome c release, and enhanced cleavages of caspase-3 and poly-(ADP-ribose) polymerase. Collectively, our results reveal that bufalin suppresses IL-1β-induced proliferation of RAFLSs through MAPK and NF-κB signaling pathways and induces RAFLS apoptosis via the mitochondria-dependent pathway.

Synthesis and biological evaluation of bile carboxamide derivatives with pro-apoptotic effect on human colon adenocarcinoma cell lines

We previously reported that the cinnamylpiperazinyl group in the side chain of the chenodeoxycholic acid showed apoptosis-inducing activity on multiple myeloma cancer cell line KMS-11. In the present study, we synthesized and tested the pro-apoptotic potency of fifteen new piperazinyl bile carboxamide derived from cholic, ursodeoxycholic, chenodeoxycholic, deoxycholic and lithocholic acids on human colon adenocarcinoma cell lines DLD-1, HCT-116, and HT-29. Cell viability was first measured using XTT assay. The most of the synthetic bile carboxamide derivatives decreased significantly cell viability in a dose-dependent manner. HCT-116 and DLD-1 cell lines were more sensitive than HT-29 to tested compounds. 9c, 9d showed the best in vitro results in term of solubility and dose-response effect on the three colon adenocarcinoma cell lines. Additionally, flow cytometric and Western-blotting analysis showed that 9c induced pro-apoptosis in DLD-1 and HCT-116 whereas 9d did not. We conclude that the benzyl group improved anti-proliferative activity and that the α-hydroxyl group was found to be more beneficial at the 7-position in steroid skeleton.