Project description:Constitutive androstane receptor (CAR) is a xenobiotic nuclear receptor mainly expressed in the liver, where it regulates drug metabolism and energy homeostasis. CAR has emerged as a promising therapeutic target for diabetes, fatty liver disease, and alcoholic liver disease, but it has not been investigated in the context of sepsis. Here, we show that sepsis impairs CAR function in the liver, partly due to reduced transcription mediated by HNF4α, the key liver identity transcription factor, and partly due to decreased DNA binding, caused by chromatin remodelling, also mediated by HNF4α. This impairment leads to the downregulation of several genes involved in monocarboxylic acid, fatty acid, and xenobiotic metabolism, contributing to increased sepsis lethality, and is associated with an elevated hepatic acute phase response. NCT protects against sepsis by enhancing HNF4α binding to the CAR promoter, thereby increasing both CAR transcription and activity.
Project description:To describe the transcriptional changes associated with polymicrobial-sepsis induced myocardial depression in wild type and iNOS deficient mice. Keywords: myocardium, contractility, differential gene expression, nitric oxide synthase, infection We compared the transcriptional profile of C57/BL6 WT mice and congenic B6 129P2-Nos2tm1Lau/J mice after 48 hrs of polymicrobial sepsis induced by caecal ligation and perforation. 48 hours after surgery, mice were anaesthetised (intraperitoneal 100 mg/kg ketamine and 10 mg/kg xylazine). The right common carotid artery was cannulated (Millar Mikro-Tip pressure transducing catheter: 1.4F sensor, 2F catheter; Houston TX). Pressure tracings from the aorta and left ventricle were recorded (SonoLAB software; Sonometrics Corp., London Ontario Canada) and analysed using Cardiosoft and Origin 6.0 (Sonometrics Corp., and Microcal Software, Northampton MA). The heart was removed, emptied of blood, and snap frozen.
Project description:In sepsis, limited food intake and increased energy expenditure induce a starvation response, which is compromised by a quick decline in expression of hepatic PPARα, a transcription factor essential in intracellular catabolism of free fatty acids. The mechanism upstream of this PPARα downregulation is unknown. We found that sepsis causes a progressive hepatic loss-of-function of HNF4α, which has strong impact on the expression of several important nuclear receptors, including PPARα. HNF4α depletion in hepatocytes dramatically increases sepsis lethality, steatosis and organ damage and prevents an adequate response towards IL6, which is critical for liver regeneration and survival. An HNF4α agonist protects against sepsis at all possible levels, irrespectively of bacterial loads, suggesting HNF4α is crucial in disease tolerance to sepsis. In conclusion, hepatic HNF4α fails in sepsis, causing PPARα downregulation and metabolic problems and a disturbed IL6-mediated acute phase response. The data open new insights and therapeutic options in sepsis.
Project description:Sepsis is a maladaptive host response towards an infection leading to tissue damage, organ failure, and ultimately death. In sepsis, limited food intake and increased energy expenditure induce a starvation response, which is hindered by hepatic disappearance of the key transcription factor PPARα. Since PPARα acts as a central player in intracellular catabolism of fatty acids (FAs), sepsis results in excess free FAs, which cause lipotoxicity. The mechanism upstream of the PPARα downregulation in sepsis is unknown. A potential mechanism resides in HNF4α, which regulates liver lipid metabolism directly by activating Ppara gene expression and indirectly by interacting with PPARα itself. A proper functioning of HNF4α is essential for maintaining liver identity. We here show that sepsis causes a progressive HNF4α loss-of-function in the liver, which impacts expression of several nuclear receptors, among which PPARα, and is characterized by a reduced HNF4α DNA binding. Specific HNF4α depletion in the liver dramatically worsens sepsis lethality, associated with increased steatosis and hepatocyte damage. HNF4α dysfunction also prevents an adequate response towards IL6, controlled by CEBPβ and STAT3, which is critical for a proper liver regeneration and survival. In addition, the HNF4α agonist NCT partially protects against sepsis by limiting hepatic steatosis and liver dysfunction. In conclusion, hepatic HNF4α fails in sepsis, causing PPARα downregulation and consequent metabolic problems on the one hand, and a disturbed IL6-mediated acute phase response and regeneration on the other hand. The data open new insights and therapeutic options in sepsis
Project description:We systematically assessed the transcriptomic changes of livers of MxCreFthD/D vs. Fthlox/lox mice after induction of polymicrobial sepsis using Cecal Ligation and Puncture. Data indicates a distinct set of genes differentially regulated between MxCreFthD/D and Fthlox/lox mice after sepsis induction reflecting altered iron and glucose metabolism.
Project description:In sepsis, limited food intake and increased energy expenditure induce a starvation response, which is compromised by a quick decline in expression of hepatic PPARα, a transcription factor essential in intracellular catabolism of free fatty acids. The mechanism upstream of this PPARα downregulation is unknown. We found that sepsis causes a progressive hepatic loss-of-function of HNF4α, which has strong impact on the expression of several important nuclear receptors, including PPARα. HNF4α depletion in hepatocytes dramatically increases sepsis lethality, steatosis and organ damage and prevents an adequate response towards IL6, which is critical for liver regeneration and survival. An HNF4α agonist protects against sepsis at all possible levels, irrespectively of bacterial loads, suggesting HNF4α is crucial in disease tolerance to sepsis. In conclusion, hepatic HNF4α fails in sepsis, causing PPARα downregulation and metabolic problems and a disturbed IL6-mediated acute phase response. The data open new insights and therapeutic options in sepsis.
Project description:In sepsis, limited food intake and increased energy expenditure induce a starvation response, which is compromised by a quick decline in expression of hepatic PPARα, a transcription factor essential in intracellular catabolism of free fatty acids. The mechanism upstream of this PPARα downregulation is unknown. We found that sepsis causes a progressive hepatic loss-of-function of HNF4α, which has strong impact on the expression of several important nuclear receptors, including PPARα. HNF4α depletion in hepatocytes dramatically increases sepsis lethality, steatosis and organ damage and prevents an adequate response towards IL6, which is critical for liver regeneration and survival. An HNF4α agonist protects against sepsis at all possible levels, irrespectively of bacterial loads, suggesting HNF4α is crucial in disease tolerance to sepsis. In conclusion, hepatic HNF4α fails in sepsis, causing PPARα downregulation and metabolic problems and a disturbed IL6-mediated acute phase response. The data open new insights and therapeutic options in sepsis.
Project description:In sepsis, limited food intake and increased energy expenditure induce a starvation response, which is compromised by a quick decline in expression of hepatic PPARα, a transcription factor essential in intracellular catabolism of free fatty acids. The mechanism upstream of this PPARα downregulation is unknown. We found that sepsis causes a progressive hepatic loss-of-function of HNF4α, which has strong impact on the expression of several important nuclear receptors, including PPARα. HNF4α depletion in hepatocytes dramatically increases sepsis lethality, steatosis and organ damage and prevents an adequate response towards IL6, which is critical for liver regeneration and survival. An HNF4α agonist protects against sepsis at all possible levels, irrespectively of bacterial loads, suggesting HNF4α is crucial in disease tolerance to sepsis. In conclusion, hepatic HNF4α fails in sepsis, causing PPARα downregulation and metabolic problems and a disturbed IL6-mediated acute phase response. The data open new insights and therapeutic options in sepsis.