Conditional loss of geranylgeranyl diphosphate synthase alleviates acute obstructive cholestatic liver injury by regulating hepatic bile acid metabolism.
- 作者列表："Jia WJ","Tang QL","Jiang S","Sun SQ","Xue B","Qiu YD","Li CJ","Mao L
:Previous studies have suggested that metabolites in the mevalonate pathway are involved in hepatic bile acid metabolism, yet the details of this relationship remain unknown. In this study, we found that the hepatic farnesyl pyrophosphate (FPP) level and the ratio of FPP to geranylgeranyl pyrophosphate (GGPP) were increased in mice with acute obstructive cholestasis compared with mice that underwent a sham operation. In addition, the livers of the mice with acute obstructive cholestasis showed lower expression of geranylgeranyl diphosphate synthase (GGPPS), which synthesizes GGPP from FPP. When Ggps1 was conditionally deleted in the liver, amelioration of liver injury, as shown by downregulation of the hepatic inflammatory response and decreased hepatocellular apoptosis, was found after ligation of the common bile duct and cholecystectomy (BDLC). Subsequently, liquid chromatography/mass spectrometry analysis showed that knocking out Ggps1 decreased the levels of hepatic bile acids, including hydrophobic bile acids. Mechanistically, the disruption of Ggps1 increased the levels of hepatic FPP and its metabolite farnesol, thereby resulting in farnesoid X receptor (FXR) activation, which modulated hepatic bile acid metabolism and reduced hepatic bile acids. It was consistently indicated that digeranyl bisphosphonate, a specific inhibitor of GGPPS, and GW4064, an agonist of FXR, could also alleviate acute obstructive cholestatic liver injury in vivo. In general, GGPPS is critical for modulating acute obstructive cholestatic liver injury, and the inhibition of GGPPS ameliorates acute obstructive cholestatic liver injury by decreasing hepatic bile acids, which is possibly achieved through the activation of FXR-induced bile acid metabolism.
: 以前的研究表明，甲羟戊酸途径中的代谢产物参与肝胆汁酸代谢，但这种关系的细节尚不清楚。在这项研究中，我们发现肝脏法尼基焦磷酸 (FPP) 水平和 FPP 与香叶基焦磷酸 (GGPP) 的比例与接受假手术的小鼠相比，急性阻塞性胆汁淤积小鼠的 was 增加。此外，急性梗阻性胆汁淤积小鼠的肝脏显示出低表达的香叶基香叶酰二磷酸合成酶 (GGPPS)，其从 FPP 合成 GGPP。当 Ggps1 在肝脏中被条件性删除时，肝损伤的改善，如通过下调肝脏炎症反应和减少肝细胞凋亡所示, 在胆总管结扎和胆囊切除术 (BDLC) 后发现。随后，液相色谱/质谱分析显示敲除 Ggps1 降低了肝胆汁酸的水平，包括疏水性胆汁酸。机械上，Ggps1 的破坏增加了肝脏 FPP 及其代谢产物法尼醇的水平，从而导致法尼醇 X 受体 (FXR) 激活，从而调节肝脏胆汁酸代谢，降低肝脏胆汁酸。一致表明，GGPPS 的特异性抑制剂二香叶酰双膦酸盐和 FXR 的激动剂 GW4064 也可减轻体内急性阻塞性胆汁淤积性肝损伤。总的来说，GGPPS 对调节急性阻塞性胆汁淤积性肝损伤至关重要，抑制 GGPPS 通过降低肝胆汁酸改善急性阻塞性胆汁淤积性肝损伤, 这可能是通过激活 FXR 诱导的胆汁酸代谢实现的。
METHODS:BACKGROUND & AIMS:Lifetime risk of biliary tract cancer (BTC) in primary sclerosing cholangitis (PSC) exceeds 20% and BTC is currently the leading cause of death in PSC patients. To open new avenues for management, we aimed to delineate novel and clinically relevant genomic and pathological features of a large panel of PSC-associated BTC (PSC-BTC). APPROACH & RESULTS:We analysed formalin fixed, paraffin embedded tumor tissue from 186 PSC-BTC patients from 11 centers in eight countries with all anatomical locations included. We performed tumor DNA sequencing at 42 clinically relevant genetic loci to detect mutations, translocations and copy number variations, along with histomorphological and immunohistochemical characterization. Irrespective of the anatomical localization, PSC-BTC exhibited a uniform molecular and histological characteristic similar to extrahepatic cholangiocarcinoma. We detected a high frequency of genomic alterations typical of extrahepatic cholangiocarcinoma, e.g. TP53 (35.5%), KRAS (28.0%), CDKN2A (14.5%), and SMAD4 (11.3%), as well as potentially druggable mutations (e.g. HER2/ERBB2). We found a high frequency of non-typical/non-ductal histomorphological subtypes (55.2%) and of the usually rare BTC precursor lesion, intraductal papillary neoplasia (18.3%) CONCLUSION: Genomic alterations in PSC-BTC include a significant number of putative actionable therapeutic targets. Notably, PSC-BTC show a distinct extrahepatic morpho-molecular phenotype, independent of the anatomical location of the tumor. These findings advance our understanding of PSC-associated cholangiocarcinogenesis and provide strong incentives for clinical trials to test genome-based personalized treatment strategies in PSC-BTC.
METHODS:BACKGROUND:The impact of inflammatory bowel disease (IBD) activity on long-term outcomes after liver transplantation (LT) for primary sclerosing cholangitis (PSC) is unknown. We examined the impact of post-LT IBD activity on clinically significant outcomes. METHODS:One hundred twelve patients undergoing LT for PSC from 2 centers were studied for a median of 7 years. Patients were divided into 3 groups according to their IBD activity after LT: no IBD, mild IBD, and moderate to severe IBD. Patients were classified as having moderate to severe IBD if they met at least 1 of 3 criteria: (i) Mayo 2 or 3 colitis or Simple Endoscopic Score-Crohn's Disease ≥7 on endoscopy; (ii) acute flare of IBD necessitating steroid rescue therapy; or (iii) post-LT colectomy for medically refractory IBD. RESULTS:Moderate to severe IBD at any time post-transplant was associated with a higher risk of Clostridium difficile infection (27% vs 8% mild IBD vs 8% no IBD; P = 0.02), colorectal cancer/high-grade dysplasia (21% vs 3% both groups; P = 0.004), post-LT colectomy (33% vs 3% vs 0%) and rPSC (64% vs 18% vs 20%; P < 0.001). Multivariate analysis revealed that moderate to severe IBD increased the risk of both rPSC (relative risk [RR], 8.80; 95% confidence interval [CI], 2.81-27.59; P < 0.001) and colorectal cancer/high-grade dysplasia (RR, 10.45; 95% CI, 3.55-22.74; P < 0.001). CONCLUSIONS:Moderate to severe IBD at any time post-LT is associated with a higher risk of rPSC and colorectal neoplasia compared with mild IBD and no IBD. Patients with no IBD and mild IBD have similar post-LT outcomes. Future prospective studies are needed to determine if more intensive treatment of moderate to severe IBD improves long-term outcomes in patients undergoing LT for PSC.
METHODS::T cells from patients with primary sclerosing cholangitis (PSC) show a prominent IL-17 response upon stimulation with bacteria or fungi, yet the reasons for this dominant TH17 response in PSC are not clear. Here, we analyzed the potential role of monocytes in microbial recognition and in skewing the T cell response towards Th17. Monocytes and T cells from blood and livers of PSC patients and controls were analyzed ex vivo and in vitro using trans-well experiments with cholangiocytes. Cytokine production was measured using flow cytometry, ELISA, RNA in situ hybridization and quantitative real time PCR. Genetic polymorphisms were obtained from Immunochip analysis. Following ex vivo stimulation with PMA/Ionomycin, PSC patients showed significantly increased numbers of IL-17A-producing peripheral blood CD4+ T cells compared to PBC patients and healthy controls, indicating increased Th17 differentiation in vivo. Upon stimulation with microbes, monocytes from PSC patients produced significantly more IL-1β and IL-6, cytokines known to drive Th17 cell differentiation. Moreover, microbe-activated monocytes induced the secretion of Th17 and monocyte-recruiting chemokines CCL-20 and CCL-2 in human primary cholangiocytes. In livers of patients with PSC cirrhosis, CD14hi CD16int and CD14lo CD16hi monocytes/macrophages were increased compared to alcoholic cirrhosis and monocytes were found to be located around bile ducts. Conclusion: PSC patients show increased Th17 differentiation already in vivo. Microbe-stimulated monocytes drive Th17 differentiation in vitro and induce cholangiocytes to produce chemokines mediating recruitment of Th17 cells and more monocytes into portal tracts. Taken together, these results point to a pathogenic role of monocytes in patients with PSC.