Glucocorticoid receptor-dependent immunomodulatory effect of ursodeoxycholic acid on liver lymphocytes in mice

Optimized therapeutic potential of Yinchenhao decoction for cholestatic hepatitis by combined network meta-analysis and network pharmacology

BACKGROUND

Cholestatic hepatitis is recognized as a significant contributor to the development of liver fibrosis and cirrhosis. As a well-known classic formula for the treatment of cholestatic hepatitis, Yinchenhao decoction (YCHD) is widely used in countries in Asia, including China, Japan, and Korea. However, in recent years, a risk of liver injury has been reported from Rheum palmatum L. and Gardenia jasmonoides J.Ellis which are the main ingredients of YCHD. Therefore, the question arises whether YCHD is still safe enough for the treatment of cholestatic hepatitis or whether an optimized ratio of ingredients should be applied. These is inevitable questions for the clinical application of YCHD.

PURPOSE

To provide a scientific basis for the clinical application of YCHD through a combination of meta-analysis and network pharmacology and to find the best ratio of components to ensure optimal therapeutic efficacy and safety. At the same time, a deeper understanding of the mechanisms of YCHD was explored.

METHODS

We retrieved relevant trials from various databases including PubMed, Web of Science, EMBASE, Cochrane Library, China National Knowledge Infrastructure (CNKI), VIP and Wanfang databases up to August 2023. After screening for inclusion and exclusion criteria, we assessed efficiency, ALT, AST, and TBIL as outcome parameters. The relevant data underwent a network meta-analysis using STATA 16.0 software. Based on network pharmacology, we screened the disease targets, active ingredients, and targets related to YCHD. The targets were visualized using Cytoscape 3.9.1. Then, potential mechanisms were explored based on bioinformatic techniques.

RESULTS

Twenty eligible studies were finally screened and a total of 1,591 patients who fulfilled the inclusion criteria were enrolled in the study. The meta-analysis results indicated that TG-c (treatment group c) [(Artemisia capillaris Thunb. : Gardenia jasminoides J.Ellis : Rheum palmatum L. = 10:5:2-10:5:3) + CT] was the most promising therapeutic approach, demonstrating superior efficacy and notable improvements in both AST and TBIL levels. For ALT, TG-d [(Artemisia capillaris : Gardenia jasminoides : Rheum palmatum = 5:1:1-5:2:1) + CT] exhibited the greatest potential as optimal therapy option. Based on the surface under the cumulative ranking curve (SUCRA) values, TG-c was the best therapy in terms of efficiency and improvement in TBIL levels, while TG-d was the most effective in reducing ALT levels. For AST levels, TG-e [(Artemisia capillaris : Gardenia jasminoides : Rheum palmatum = 5:2:2-5:3:3) + CT] was the most effective therapy. The comprehensive analysis revealed that TG-c exhibited the most pronounced efficacy. Combined network pharmacology, GO enrichment analysis and KEGG pathway enrichment analysis displayed that the key target genes of Artemisia capillaris, Rheum palmatum, and Gardenia jasminoides were closely involved in inflammation response, bile transport, apoptosis, oxidative stress, and regulation of leukocyte migration. Notably, bile secretion dominated the common pathway of the three herbs. On the other hand, Artemisia capillaris exhibited a unique mode of action by regulating the IL-17 signaling pathway, which may play a crucial role in its effectiveness.

CONCLUSION

Based on our findings, the optimal TG-C demonstrated the most favorable overall therapeutic efficacy by increasing the dosage of Artemisia capillaris while reducing the dosage of Gardenia jasminoides and Rheum palmatum. This is attributed to the potent ability of Artemisia capillaris. to effectively modulate the IL-17 signaling pathway, thereby exerting a beneficial therapeutic effect. Conversely, Gardenia jasminoides and Rheum palmatum may potentially enhance the activation of the NF-кB signaling pathway, thereby elevating the risk of hepatotoxicity.

Glucocorticoid receptor-dependent therapeutic efficacy of tauroursodeoxycholic acid in preclinical models of spinocerebellar ataxia type 3

Spinocerebellar ataxia type 3 (SCA3) is an adult-onset neurodegenerative disease caused by a polyglutamine expansion in the ataxin-3 (ATXN3) gene. No effective treatment is available for this disorder, other than symptom-directed approaches. Bile acids have shown therapeutic efficacy in neurodegenerative disease models. Here, we pinpointed tauroursodeoxycholic acid (TUDCA) as an efficient therapeutic, improving the motor and neuropathological phenotype of SCA3 nematode and mouse models. Surprisingly, transcriptomic and functional in vivo data showed that TUDCA acts in neuronal tissue through the glucocorticoid receptor (GR), but independently of its canonical receptor, the farnesoid X receptor (FXR). TUDCA was predicted to bind to the GR, in a similar fashion to corticosteroid molecules. GR levels were decreased in disease-affected brain regions, likely due to increased protein degradation as a consequence of ATXN3 dysfunction being restored by TUDCA treatment. Analysis of a SCA3 clinical cohort showed intriguing correlations between the peripheral expression of GR and the predicted age at disease onset in presymptomatic subjects and FKBP5 expression with disease progression, suggesting this pathway as a potential source of biomarkers for future study. We have established a novel in vivo mechanism for the neuroprotective effects of TUDCA in SCA3 and propose this readily available drug for clinical trials in SCA3 patients.

Potential role of bile acids in the pathogenesis of necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is one of the most common acute gastrointestinal diseases in preterm infants. Recent studies have found that NEC is not only caused by changes in the intestinal environment but also by the failure of multiple systems and organs, including the liver. The accumulation of bile acids (BAs) in the ileum and the disorder of ileal BA transporters are related to the ileum injury of NEC. Inflammatory factors such as tumor necrosis factor (TNF)-α and interleukin (IL)-18 secreted by NEC also play an important role in regulating intrahepatic BA transporters. As an important link connecting the liver and intestinal circulation, the bile acid metabolic pathway plays an important role in the regulation of intestinal microbiota, cell proliferation, and barrier protection. In this review, we focus on how bile acids explore the dynamic changes of bile acid metabolism in necrotizing enterocolitis and the potential therapeutic value of targeting the bile acid signaling pathways.

Therapeutic mechanisms and beneficial effects of non-antidiabetic drugs in chronic liver diseases

The global burden of chronic liver disease (CLD) is substantial. Due to the limited indication of and accessibility to antiviral therapy in viral hepatitis and lack of effective pharmacological treatment in nonalcoholic fatty liver disease, the beneficial effects of antidiabetics and non-antidiabetics in clinical practice have been continuously investigated in patients with CLD. In this narrative review, we focused on non-antidiabetic drugs, including ursodeoxycholic acid, silymarin, dimethyl4,4'-dimethoxy-5,6,5',6'-dimethylenedixoybiphenyl-2,2'-dicarboxylate, L-ornithine L-aspartate, branched chain amino acids, statin, probiotics, vitamin E, and aspirin, and summarized their beneficial effects in CLD. Based on the antioxidant, anti-inflammatory properties, and regulatory functions in glucose or lipid metabolism, several non-antidiabetic drugs have shown beneficial effects in improving liver histology, aminotransferase level, and metabolic parameters and reducing risks of hepatocellular carcinoma and mortality, without significant safety concerns, in patients with CLD. Although the effect as the centerpiece management in patients with CLD is not robust, the use of these non-antidiabetic drugs might be potentially beneficial as an adjuvant or combined treatment strategy.

Ursodeoxycholic acid impairs liver-infiltrating T-cell chemotaxis through IFN-γ and CX3CL1 production in primary biliary cholangitis

Ursodeoxycholic acid (UDCA) is the primary treatment for primary biliary cholangitis (PBC), but its mechanism of action remains unclear. Studies suggest that UDCA enhances NF erythroid 2-related factor 2 (NFE2L2) expression and that the interaction between IFN-γ and C-X3-C motif chemokine ligand 1 (CX3CL1) facilitates biliary inflammation in PBC. Therefore, we examined the effects of UDCA on the expression of IFN-γ and CX3CL1 in in vitro and in vivo PBC models such as human liver tissue, a murine model, cell lines, and isolated human intrahepatic biliary epithelial cells (IHBECs). We observed a significant decrease in IFN-γ mRNA levels and positive correlations between IFN-γ and CX3CL1 mRNA levels post-UDCA treatment in PBC livers. NFE2L2-mediated transcriptional activation was significantly enhanced in UDCA-treated Jurkat cells. In 2-octynoic acid-immunized mice, IFN-γ production by liver-infiltrating T cells was dependent on NFE2L2 activation. IFN-γ significantly and dose-dependentlyinduced CX3CL1 expression, which was significantly decreased in HuCC-T1 cells and IHBECs upon UDCA treatment. These results suggest that UDCA-induced suppression of IFN-γ and CX3CL1 production attenuates the chemotactic and adhesive abilities of liver-infiltrating T cells in PBC.

Bile Acids: A Communication Channel in the Gut-Brain Axis

Bile acids are signalling hormones involved in the regulation of several metabolic pathways. The ability of bile acids to bind and signal through their receptors is modulated by the gut microbiome, since the microbiome contributes to the regulation and synthesis of bile acids as well to their physiochemical properties. From the gut, bacteria have been shown to send signals to the central nervous system via their metabolites, thus affecting the behaviour and brain function of the host organism. In the last years it has become increasingly evident that bile acids affect brain function, during normal physiological and pathological conditions. Although bile acids may be synthesized locally in the brain, the majority of brain bile acids are taken up from the systemic circulation. Since the composition of the brain bile acid pool may be regulated by the action of intestinal bacteria, it is possible that bile acids function as a communication bridge between the gut microbiome and the brain. However, little is known about the molecular mechanisms and the physiological roles of bile acids in the central nervous system. The possibility that bile acids may be a direct link between the intestinal microbiome and the brain is also an understudied subject. Here we review the influence of gut bacteria on the bile acid pool composition and properties, as well as striking evidence showing the role of bile acids as neuroactive molecules.

Primary biliary cholangitis: pathogenesis and therapeutic opportunities

Primary biliary cholangitis is a chronic, seropositive and female-predominant inflammatory and cholestatic liver disease, which has a variable rate of progression towards biliary cirrhosis. Substantial progress has been made in patient risk stratification with the goal of personalized care, including early adoption of next-generation therapy with licensed use of obeticholic acid or off-label fibrate derivatives for those with insufficient benefit from ursodeoxycholic acid, the current first-line drug. The disease biology spans genetic risk, epigenetic changes, dysregulated mucosal immunity and altered biliary epithelial cell function, all of which interact and arise in the context of ill-defined environmental triggers. A current focus of research on nuclear receptor pathway modulation that specifically and potently improves biliary excretion, reduces inflammation and attenuates fibrosis is redefining therapy. Patients are benefiting from pharmacological agonists of farnesoid X receptor and peroxisome proliferator-activated receptors. Immunotherapy remains a challenge, with a lack of target definition, pleiotropic immune pathways and an interplay between hepatic immune responses and cholestasis, wherein bile acid-induced inflammation and fibrosis are dominant clinically. The management of patient symptoms, particularly pruritus, is a notable goal reflected in the development of rational therapy with apical sodium-dependent bile acid transporter inhibitors.

Comparative analysis of thymic subpopulations during different modes of atrophy identifies the reactive oxygen species scavenger, N-acetyl cysteine, to increase the survival of thymocytes during infection-induced and lipopolysaccharide-induced thymic atrophy

The development of immunocompetent T cells entails a complex pathway of differentiation in the thymus. Thymic atrophy occurs with ageing and during conditions such as malnutrition, infections and cancer chemotherapy. The comparative changes in thymic subsets under different modes of thymic atrophy and the mechanisms involved are not well characterized. These aspects were investigated, using mice infected with Salmonella Typhimurium, injection with lipopolysaccharide (LPS), an inflammatory but non-infectious stimulus, etoposide (Eto), a drug used to treat some cancers, and dexamethasone (Dex), a steroid used in some inflammatory diseases. The effects on the major subpopulations of thymocytes based on multicolour flow cytometry studies were, first, the CD4^-  CD8^- double-negative (DN) cells, mainly DN2-4, were reduced with infection, LPS and Eto treatment, but not with Dex. Second, the CD8⁺  CD3^lo immature single-positive cells (ISPs) were highly sensitive to infection, LPS and Eto, but not Dex. Third, treatment with LPS, Eto and Dex reduced all three subpopulations of CD4⁺  CD8⁺ double-positive (DP) thymocytes, i.e. DP1, DP2 and DP3, but the DP3 subset was relatively more resistant during infection. Fourth, both CD4⁺ and CD8⁺ single-positive (SP) thymocytes were lowered by Eto and Dex, but not during infection. Notably, LPS lowered CD4⁺ SP subsets, whereas the CD8⁺ SP subsets were relatively more resistant. Interestingly, the reactive oxygen species quencher, N-acetyl cysteine, greatly improved the survival of thymocytes, especially DNs, ISPs and DPs, during infection and LPS treatment. The implications of these observations for the development of potential thymopoietic drugs are discussed.

Guts and Gall: Bile Acids in Regulation of Intestinal Epithelial Function in Health and Disease

Epithelial cells line the entire surface of the gastrointestinal tract and its accessory organs where they primarily function in transporting digestive enzymes, nutrients, electrolytes, and fluid to and from the luminal contents. At the same time, epithelial cells are responsible for forming a physical and biochemical barrier that prevents the entry into the body of harmful agents, such as bacteria and their toxins. Dysregulation of epithelial transport and barrier function is associated with the pathogenesis of a number of conditions throughout the intestine, such as inflammatory bowel disease, chronic diarrhea, pancreatitis, reflux esophagitis, and cancer. Driven by discovery of specific receptors on intestinal epithelial cells, new insights into mechanisms that control their synthesis and enterohepatic circulation, and a growing appreciation of their roles as bioactive bacterial metabolites, bile acids are currently receiving a great deal of interest as critical regulators of epithelial function in health and disease. This review aims to summarize recent advances in this field and to highlight how bile acids are now emerging as exciting new targets for disease intervention.

Bile Acids in Hepatic Encephalopathy

Hepatic encephalopathy describes the array of neurological complications that arise due to liver insufficiency and/or portal-systemic shunt. The pathogenesis of hepatic encephalopathy shares a longstanding association with hyperammonemia and inflammation. Recently, aberrant bile acid signaling has been implicated in the development of key features of hepatic encephalopathy due to acute liver failure including neuronal dysfunction, neuroinflammation and blood-brain barrier permeability. This review summarizes the findings of recent studies demonstrating a role for bile acids in hepatic encephalopathy and speculates on the possible downstream consequences of bile acid signaling.

Bile Acids in the Treatment of Cardiometabolic Diseases

Bile acids (BA), for decades considered only to have fat-emulsifying functions in the gut lumen, have recently emerged as novel cardio-metabolic modulators. They have real endocrine effects, acting via multiple intracellular receptors in various organs and tissues. BA affect energy homeostasis through the modulation of glucose and lipid metabolism, predominantly by activating the nuclear farnesoid X receptor (FXR), as well as the cytoplasmic membrane G protein-coupled BA receptor TGR5 in a variety of tissues; although numerous other intracellular targets of BA are also in play.The roles of BA in the pathogenesis of diabetes, obesity, metabolic syndrome, and cardiovascular diseases are seriously being considered, and BA and their derivatives seem to represent novel potential therapeutics to treat these diseases of civilization.

Novel strategies and therapeutic options for the management of primary biliary cholangitis

Primary biliary cholangitis (PBC) is a chronic autoimmune liver disease. It has a varied course of progression ranging from being completely asymptomatic to aggressive disease leading to cirrhosis and resulting in liver transplantation. In addition, symptoms can be debilitating and can have a major impact on quality of life. For decades, there was only one anti-cholestatic agent available to target this disease and that was only effective in around half of patients, with little or no effect on symptoms. With increasing understanding of the pathogenic mechanisms of PBC and potential targets for drug treatment, pharmaceutical companies have shown a greater interest in this rare disease. A large number of novel therapeutic molecules have been developed and are currently being evaluated. In this review article all the novel molecules in use and in trials targeting cholestasis and symptoms in PBC are discussed.

Management of cholestatic disease in 2017

Primary biliary cholangitis (PBC) and primary sclerosing cholangitis (PSC) are the most frequent chronic cholestatic liver diseases and serve as model diseases to discuss the management of cholestasis in 2017 in the lecture that is summarized in this report. PBC and PSC are characterized by inflammation and fibrosis of small intrahepatic (PBC) or larger intra- and/or extrahepatic (PSC) bile ducts. Bile duct damage leads to cholestasis and can progress to liver fibrosis and even cirrhosis. Various genetic, environmental and endogenous factors may contribute to the development of chronic cholestatic liver diseases, but the exact pathogenesis of PBC and PSC has not been clarified. Ursodeoxycholic acid (UDCA) is the standard treatment of PBC and is used also for other cholestatic conditions including PSC, and it exerts anticholestatic effects at adequate doses. Novel anticholestatic therapeutic options for patients not adequately responding to UDCA are under development or have, like obeticholic acid, already been proven to have efficacy when combined with UDCA in the treatment of PBC. The future role of immunomodulating/immunosuppressive drug regimens must be critically reviewed.

Effects of bile acids on neurological function and disease

Bile acids are synthesized from cholesterol and are known to be involved with the emulsification and digestion of dietary lipids and fat-soluble vitamins. Outside of this role, bile acids can act as cell signaling effectors through binding and activating receptors on both the cell membrane and nucleus. Numerous reports have investigated these signaling pathways in conditions where the liver is damaged. More recently, effort has been made to investigate the role of bile acids in diseases outside of those associated with liver damage. This review summarizes recent findings on the influences that bile acids can exert in normal neurological function and their contribution to diseases of the nervous system, with the intent of highlighting the role of these metabolites as potential players in neurological disorders.-McMillin, M., DeMorrow, S. Effects of bile acids on neurological function and disease.

Glucocorticoid receptor expression and binding capacity in patients with burn injury

BACKGROUND

Burn injuries are associated with strong inflammation and risk of secondary sepsis which both may affect the function of the glucocorticoid receptor (GR). The aim of this study was to determine GR expression and binding capacity in leucocytes from patients admitted to a tertiary burn center.

METHODS

Blood was sampled from 13 patients on admission and days 7, 14 and 21, and once from 16 healthy subjects. Patients were grouped according to the extent of burn and to any sepsis on day 7. Expression and binding capacity of GR were determined as arbitrary units using flow cytometry.

RESULTS

GR expression and binding capacity were increased compared to healthy subjects in most circulating leucocyte subsets on admission irrespective of burn size. Patients with sepsis on day 7 displayed increased GR expression in T lymphocytes (51.8%, P < 0.01) compared to admission. There was a negative correlation between GR binding capacity in neutrophils and burn size after 14 days (P < 0.05).

CONCLUSIONS

GR expression and binding capacity are increased in most types of circulating leucocytes of severely burned patients on their admission to specialized burn care. If sepsis is present after 1 week, it is associated with higher GR expression in T lymphocytes and NK cells.

New paradigms in the treatment of hepatic cholestasis: from UDCA to FXR, PXR and beyond

Cholestasis is an impairment of bile formation/flow at the level of the hepatocyte and/or cholangiocyte. The first, and for the moment, most established medical treatment is the natural bile acid (BA) ursodeoxycholic acid (UDCA). This secretagogue improves, e.g. in intrahepatic cholestasis of pregnancy or early stage primary biliary cirrhosis, impaired hepatocellular and cholangiocellular bile formation mainly by complex post-transcriptional mechanisms. The limited efficacy of UDCA in various cholestatic conditions urges for development of novel therapeutic approaches. These include nuclear and membrane receptor agonists and BA derivatives. The nuclear receptors farnesoid X receptor (FXR), retinoid X receptor (RXR), peroxisome proliferator-activated receptor α (PPARα), and pregnane X receptor (PXR) are transcriptional modifiers of bile formation and at present are under investigation as promising targets for therapeutic interventions in cholestatic disorders. The membrane receptors fibroblast growth factor receptor 4 (FGFR4) and apical sodium BA transporter (ASBT) deserve attention as additional therapeutic targets, as does the potential therapeutic agent norUDCA, a 23-C homologue of UDCA. Here, we provide an overview on established and future promising therapeutic agents and their potential molecular mechanisms and sites of action in cholestatic diseases.

Novel insights in the HPA-axis during critical illness

Critical illness represents a major challenge for the human body, implicating that an adequate stress response is indispensable for survival. Therefore, for a long time, activation of the hypothalamic pituitary adrenal axis was assumed to be increased to respond to this stressful situation. Recent novel insights, however, provided evidence that the HPA-axis is regulated differently during critical illness. Cortisol metabolism was shown to be reduced which contributed to hypercortisolism in an energy efficient way without increasing cortisol production dramatically. Yet, the concomitant low ACTH levels, explained by negative feedback inhibition, could lead to an understimulation of the adrenal gland and affect adrenal structure and function, given the crucial role of ACTH for adrenal gland maintenance. This side-effect could negatively affect outcome predominantly in the prolonged phase of critical illness and could explain the increased incidence of adrenal failure in these patients. Altogether, novel findings represent a paradigm shift in our current understanding of HPA-axis regulation during critical illness and redirect future research perspectives with an urgent need to well-designed clinical trials to further explore HPA-axis functioning during critical illness.

Cortisol metabolism in critical illness: implications for clinical care

PURPOSE OF REVIEW

Critical illness is uniformly characterized by elevated plasma cortisol concentrations, traditionally attributed exclusively to increased cortisol production driven by an activated hypothalamic pituitary adrenal axis. However, as plasma adrenocorticotropic hormone (ACTH) concentrations are often not elevated or even low during critical illness, alternative mechanisms must contribute.

RECENT FINDINGS

Recent investigations revealed that plasma clearance of cortisol is markedly reduced during critical illness, explained by suppressed expression and activity of the main cortisol metabolizing enzymes in liver and kidney. Furthermore, unlike previously inferred, cortisol production rate in critically ill patients was only moderately increased to less than double that of matched healthy subjects. In the face of low-plasma ACTH concentrations, these data suggest that other factors drive hypercortisolism during critical illness, which may suppress ACTH by feedback inhibition. These new insights add to the limitations of the current diagnostic tools to identify patients at risk of failing adrenal function during critical illness. They also urge to investigate the impact of lower hydrocortisone doses than those hitherto used.

SUMMARY

Recent novel insights reshape the current understanding of the hormonal stress response to critical illness and further underline the need for more studies to unravel the pathophysiology of adrenal (dys)functioning during critical illness.