Intestinal epithelial damage-derived mtDNA activates STING-IL12 axis in dendritic cells to promote colitis.

Rationale: The treatment of ulcerative colitis (UC) presents an ongoing clinical challenge. Emerging research has implicated that the cGAS-STING pathway promotes the progression of UC, but conflicting results have hindered the development of STING as a therapeutic target. In the current study, we aim to comprehensively elucidate the origins, downstream signaling and pathogenic roles of myeloid STING in colitis and colitis-associated carcinoma (CAC). Methods: Tmem173 fl/fl Lyz2-Cre ert2 mice were constructed for inducible myeloid-specific deletion of STING. RNA-sequencing, flow cytometry, and multiplex immunohistochemistry were employed to investigate immune responses in DSS-induced colitis or AOM/DSS-induced carcinogenesis. Colonic organoids, primary bone marrow derived macrophages and dendritic cells, and splenic T cells were used for in vitro studies. Results: We observed that myeloid STING knockout in adult mice inhibited macrophage maturation, reduced DC cell activation, and suppressed pro-inflammatory Th1 and Th17 cells, thereby protecting against both acute and chronic colitis and CAC. However, myeloid STING deletion in neonatal or tumor-present mice exhibited impaired immune tolerance and anti-tumor immunity. Furthermore, we found that TFAM-associated mtDNA released from damaged colonic organoids, rather than bacterial products, activates STING in dendritic cells in an extracellular vesicle-independent yet endocytosis-dependent manner. Both IRF3 and NF-κB are required for STING-mediated expression of IL-12 family cytokines, promoting Th1 and Th17 differentiation and contributing to excessive inflammation in colitis. Conclusions: Detection of the TFAM-mtDNA complex from damaged intestinal epithelium by myeloid STING exacerbates colitis through IL-12 cytokines, providing new evidence to support the development of STING as a therapeutic target for UC and CAC.

Transcriptotype-Driven Discovery of Apigenin as a Therapy against Cholestatic Liver Fibrosis: Through Inhibition of PANoptosis and Following Type-I Interferon Responses.

Cholangiopathies lack effective medicines and can progress into end-stage liver diseases. Mining natural product transcriptome databases for bioactive ingredients, which can reverse disease-associated transcriptomic phenotypes, holds promise as an effective approach for drug discovery. To identify disease-associated transcriptomic changes, we performed RNA-sequencing on bile duct ligation (BDL)-induced cholestatic liver fibrosis mice, as well as PBC and PSC patients, and found that PANoptosis and activation of type-I interferon (IFN) signaling were observed in BDL mice and patients with PBC and PSC. We then established a transcriptotype-driven screening system based on HERB and ITCM databases. Among 283 natural ingredients screened, apigenin (Api), which is widely distributed in varieties of food and medicinal plants, was screened out by our screen system since it reversed the expression pattern of key genes associated with PANoptosis and type-I IFN responses. In BDL, Abcb4-/-, and DDC-fed mice, Api effectively ameliorated liver injuries, inflammation, and fibrosis. It also protected cholangiocytes from bile acid-stimulated PANoptosis, thus alleviating damage-associated molecular pattern-mediated activation of TBK1-NF-κB in macrophages. Additionally, Api directly inhibited type-I IFN-induced downstream inflammatory responses. Our study demonstrated the pathogenic roles of PANoptosis and type-I IFN signaling in cholestatic liver fibrosis and verified the feasibility of transcriptotype-based drug screening. Furthermore, this study revealed a novel anti-inflammatory mechanism of Api and identified it as a promising candidate for the treatment of cholestatic liver fibrosis.

Aurantio-obtusin ameliorates obesity by activating PPARα-dependent mitochondrial thermogenesis in brown adipose tissues.

Obesity contributes to the progression of various chronic diseases, and shortens life expectancy. With abundant mitochondria, brown adipose tissue (BAT) dissipates energy through heat to limit weight gain and metabolic dysfunction in obesity. Our previous studies have shown that aurantio-obtusin (AO), a bioactive ingredient in Chinese traditional medicine Cassiae semen significantly improves hepatic lipid metabolism in a steatotic mouse model. In the current study we investigated the effects of AO on lipid metabolism in the BAT of diet-induced obesity mice and in oleic acid and palmitic acid (OAPA)-stimulated primary mature BAT adipocytes. Obese mice were established by feeding a HFHS diet for 4 weeks, and then administered AO (10 mg/kg, i.g.) for another 4 weeks. We showed that AO administration significantly increased the weight of BAT and accelerated energy expenditure to protect the weight increase in the obese mice. Using RNA sequencing and molecular biology analysis we found that AO significantly enhanced mitochondrial metabolism and UCP1 expression by activating PPARα both in vivo and in vitro in the primary BAT adipocytes. Interestingly, AO administration did not improve metabolic dysfunction in the liver and white adipose tissue of obese mice after interscapular BAT excision. We demonstrated that low temperature, a trigger of BAT thermogenesis, was not a decisive factor for AO to stimulate the growth and activation of BATs. This study uncovers a regulatory network of AO in activating BAT-dependent lipid consumption and brings up a new avenue for the pharmaceutical intervention in obesity and related comorbidities.

Targeting bile acid signaling for the treatment of liver diseases: From bench to bed.

Liver diseases and related complications have become one of the leading causes of morbidity and mortality worldwide, yet effective medicine or approved treatment approach is still limited. Thus, novel therapy is urgently required to prevent or at least slow down the growing burden of liver transplantation or even death caused by malignant liver diseases. As the irreplaceable modulator of hepatic and intestinal signaling cascades, bile acids (BAs) play complex physiological as well as pathological roles in regulating energy and immune homeostasis in various liver diseases, including but not limited to metabolic diseases and cholangiopathies, making them highly attractive therapeutic targets. In the current review, recent progress in the research of enterohepatic circulation of BAs and potential therapeutic targets of BAs signaling, especially the development of currently available treatments, including agonizts of FXR and TGR5, analogs of FGF19, inhibitors of ASBT, and the regulation of gut microbiome through fecal microbiota transplantation were extensively summarized. Their protective effects, molecular mechanisms, and outcomes of clinical trials were highlighted. The structural features of these candidates and perspectives for their future development were further discussed. In conclusion, we believe that pharmacological therapies targeting BAs signaling represent promising and efficient strategies for the treatment of complex and multifactorial liver disorders.

Saikosaponin D attenuates metabolic associated fatty liver disease by coordinately tuning PPARα and INSIG/SREBP1c pathway.

BACKGROUND: Metabolic associated fatty liver disease (MAFLD) is a progressive chronic liver disease, yet there is still a lack of effective pharmacological therapies at present. Saikosaponin D (SSd) has been reported to exhibit hepatoprotective and anti-steatosis activities in our previous research. PURPOSE: The current study aims to further investigate the underlying mechanisms of SSd on MAFLD from the perspectives of the crosstalk between fatty acid (FA) biosynthesis and catabolism to provide strong support for further clinical management of MAFLD. METHODS: A MAFLD mouse model induced by a high-fat diet and glucose-fructose water (HFSW) was used for in vivo study. HepG2 cells, primary mouse hepatocytes and adipocytes were further employed for in vitro studies. RESULTS: SSd improved intracellular lipid accumulation both in the liver and adipose tissues in HFSW-fed mice. Mechanistically, SSd may serve as a potent PPARα agonist, and the activation of PPARα by SSd in both hepatocytes and adipocytes not only promoted FA oxidation but also concurrently induced INSIG1/2 expression, which subsequently inhibited SREBP1c maturation and ultimately FA synthesis. Moreover, the regulative effect of SSd on lipid metabolism was abolished by the PPARα inhibitor, GW6471. CONCLUSION: This study demonstrated that SSd improved lipid homeostasis by coordinately regulating PPARα activation-mediated both inhibition of SREBP1c-dependent FA biosynthesis and induction of FA degradation, and thus shed novel light on the discovery of SSd-based therapeutic strategies for MAFLD.

Vitexin protects against ethanol-induced liver injury through Sirt1/p53 signaling pathway.

In the present study, we aimed to investigate the therapeutic effect of Vitexin on inhibiting ethanol-induced liver damage and explore the underling mechanism. In vitro, the injury was induced in LO2 cell by 100 mM ethanol. Cell viability, AST, oxidative stress, inflammation, apoptosis rate, and related gene and protein expressions were assessed. Alcoholic liver injury model was made by intragastric infusion of alcohol for 4 weeks on male KM mice. Liver index, AST, ALT, TC, TG, TP, TBIL in serum and liver pathology were evaluated. Meanwhile, the level of SOD, MDA and TNF-α also were detected by Kits. Quantitative RT-PCR and Western blotting analysis the Sirt1/p53 pathway related gene and protein expressions. In vitro, Vitexin restored cytoactive and inhibited the releasing of AST induced by ethanol in LO2 cell. Vitexin treatment significantly suppressed the elevation of aminotransferase, blood lipid, UA in mice. Vitexin ameliorated liver pathological changes induced by ethanol. Vitexin supplement restored the decrease of Sirt1/Bcl-2 expression, restrained the elevation of caspase3, cleaved caspse-3, p53 and ac-p53 expression in vivo and in vitro. Vitexin has a protective effect against ethanol-induced liver damage, and the underlying mechanism is probably through Sirt1/p53 mediated mitochondrial apoptotic pathway.

Effect of vitexin on alleviating liver inflammation in a dextran sulfate sodium (DSS)-induced colitis model.

As one of commonly used herbs with dual-purpose of drug and food, it has been reported that vitexin has hepatoprotective effects. However, the protective effects of vitexin on colitis-induced liver injury as well as the underlying molecular mechanisms remain unclear. The purpose of the current study was to investigate the effects and mechanisms of vitexin on liver injury induced by acute ulcerative colitis in mice. In this study, the mice model of acute ulcerative colitis was induced by 4 % dextran sodium sulphate (DSS). And then, the degree of liver injury in colitis mice was evaluated, the hepatic ALT, AST, TC and TG levels were measured by specific determination kits, the levels of TNF-α, IL-6 and IL-1ß were examined by ELISA, the expressions of TLR4/NF-κB pathway related protein were detected by western blot analysis. The results indicated that hepatic histopathological changes induced by DSS were normalized by vitexin treatment, administration of vitexin decreased the liver levels of ALT and TC in mice with liver injury and reduced the release amounts of DSS-induced pro-inflammatory cytokines TNF-α, IL-6 and IL-1ß. Furthermore, we found that vitexin inhibited the activation of TLR4/NF-κB signaling pathway induced by DSS. In conclusion, vitexin possess hepatoprotective activities against colitis-induced liver injury, it has potential application prospects in the treatment of liver injury induced by ulcerative colitis.

Curcumin attenuates potassium oxonate-induced hyperuricemia and kidney inflammation in mice.

Current evidences suggest that hyperuricemia is closely related to the overproduction or underexcretion of uric acid (UA). Curcumin (CUR), a natural polyphenol component extracted from the rhizome of Curcuma longa, has been reported to treat various symptoms such inflammation disease, seems to be efficacious in hyperuricemia. In this study, we aimed to investigate the effect of CUR on hyperuricemia and kidney inflammation in hyperuricemic mice. Administration with CUR (20 or 40 mg/kg) or allopurinol (ALL, 5 mg/kg) was given to mice orally one hour later after the injection of potassium oxonate (PO) (300 mg/kg, i.p.) for 14 days. CUR administration decreased the levels of uric acid (UA), creatinine (CRE) and blood urea nitrogen (BUN) in serum. Meanwhile, treatment with CUR effectively inhibited serum and liver xanthine oxidase (XOD) levels, and further renewed normal antioxidant enzymes activities (SOD, GSH-Px), reduced MDA accumulation in serum. Further studies showed that CUR decreased inflammatory cytokines productions (IL-1ß, IL-18) in serum, as well as inhibited PO-induced the activation of NLRP3 inflammasome signaling in the kidney. In conclusion, the study revealed that CUR exhibited anti-hyperuricemic and anti-inflammatory effects through suppressing NLRP3 inflammasome activation in kidney and provided the evidence for treating hyperuricemia and associated renal inflammation.