Arginine vasopressin in vasodilatory shock: effects on metabolism and beyond

Hepatic circadian and differentiation factors control liver susceptibility for fatty liver disease and tumorigenesis

Hepatocellular carcinoma (HCC) is a leading cause of cancer deaths, and the most common primary liver malignancy to present in the clinic. With the exception of liver transplant, treatment options for advanced HCC are limited, but improved tumor stratification could open the door to new treatment options. Previously, we demonstrated that the circadian regulator Aryl Hydrocarbon-Like Receptor Like 1 (ARNTL, or Bmal1) and the liver-enriched nuclear factor 4 alpha (HNF4α) are robustly co-expressed in healthy liver but incompatible in the context of HCC. Faulty circadian expression of HNF4α- either by isoform switching, or loss of expression- results in an increased risk for HCC, while BMAL1 gain-of-function in HNF4α-positive HCC results in apoptosis and tumor regression. We hypothesize that the transcriptional programs of HNF4α and BMAL1 are antagonistic in liver disease and HCC. Here, we study this antagonism by generating a mouse model with inducible loss of hepatic HNF4α and BMAL1 expression. The results reveal that simultaneous loss of HNF4α and BMAL1 is protective against fatty liver and HCC in carcinogen-induced liver injury and in the "STAM" model of liver disease. Furthermore, our results suggest that targeting Bmal1 expression in the absence of HNF4α inhibits HCC growth and progression. Specifically, pharmacological suppression of Bmal1 in HNF4α-deficient, BMAL1-positive HCC with REV-ERB agonist SR9009 impairs tumor cell proliferation and migration in a REV-ERB-dependent manner, while having no effect on healthy hepatocytes. Collectively, our results suggest that stratification of HCC based on HNF4α and BMAL1 expression may provide a new perspective on HCC properties and potential targeted therapeutics.

A Transcriptomic Response to Lactiplantibacillus plantarum-KCC48 against High-Fat Diet-Induced Fatty Liver Diseases in Mice

The most prevalent chronic liver disorder in the world is fatty liver disease caused by a high-fat diet. We examined the effects of Lactiplantibacillus plantarum-KCC48 on high-fat diet-induced (HFD) fatty liver disease in mice. We used the transcriptome tool to perform a systematic evaluation of hepatic mRNA transcripts changes in high-fat diet (HFD)-fed animals and high-fat diet with L. plantarum (HFLPD)-fed animals. HFD causes fatty liver diseases in animals, as evidenced by an increase in TG content in liver tissues compared to control animals. Based on transcriptome data, 145 differentially expressed genes (DEGs) were identified in the liver of HFD-fed mice compared to control mice. Moreover, 61 genes were differentially expressed in the liver of mice fed the HFLPD compared to mice fed the HFD. Additionally, 43 common DEGs were identified between HFD and HFLPD. These genes were enriched in metabolic processes, retinol metabolism, the PPAR signaling pathway, fatty acid degradation, arachidonic metabolism, and steroid hormone synthesis. Taking these data into consideration, it can be concluded that L. plantarum-KCC48 treatment significantly regulates the expression of genes involved in hepatosteatosis caused by HFD, which may prevent fatty liver disease.

Recovery from Liver Failure and Fibrosis in a Rat Portacaval Anastomosis Model after Neurointermediate Pituitary Lobectomy

Liver diseases, including cirrhosis, viral hepatitis, and hepatocellular carcinoma, account for approximately two million annual deaths worldwide. They place a huge burden on the global healthcare systems, compelling researchers to find effective treatment for liver fibrosis-cirrhosis. Portacaval anastomosis (PCA) is a model of liver damage and fibrosis. Arginine vasopressin (AVP) has been implicated as a proinflammatory-profibrotic hormone. In rats, neurointermediate pituitary lobectomy (NIL) induces a permanent drop (80%) in AVP serum levels. We hypothesized that AVP deficiency (NIL-induced) may decrease liver damage and fibrosis in a rat PCA model. Male Wistar rats were divided into intact control (IC), NIL, PCA, and PCA+NIL groups. Liver function tests, liver gene relative expressions (IL-1, IL-10, TGF-β, COLL-I, MMP-9, and MMP-13), and histopathological assessments were performed. In comparison with those in the IC and PCA groups, bilirubin, protein serum, and liver glycogen levels were restored in the PCA+NIL group. NIL in the PCA animals also decreased the gene expression levels of IL-1 and COLL-I, while increasing those of IL-10, TGF-β, and MMP-13. Histopathology of this group also showed significantly decreased signs of liver damage with lower extent of collagen deposition and fibrosis. Low AVP serum levels were not enough to fully activate the AVP receptors resulting in the decreased activation of cell signaling pathways associated with proinflammatory-profibrotic responses, while activating cell molecular signaling pathways associated with an anti-inflammatory-fibrotic state. Thus, partial reversion of liver damage and fibrosis was observed. The study supports the crucial role of AVP in the inflammatory-fibrotic processes and maintenance of immune competence. The success of the AVP deficiency strategy suggests that blocking AVP receptors may be therapeutically useful to treat inflammatory-fibrotic liver diseases.

The activation of α2-adrenergic receptor in the spinal cord lowers sepsis-induced mortality

The effect of clonidine administered intrathecally (i.t.) on the mortality and the blood glucose level induced by sepsis was examined in mice. To produce sepsis, the mixture of D-galactosamine (GaLN; 0.6 g/10 ml)/lipopolysaccharide (LPS; 27 µg/27 µl) was treated intraperitoneally (i.p.). The i.t. pretreatment with clonidine (5 µg/5 µl) increased the blood glucose level and attenuated mortality induced by sepsis in a dose-dependent manner. The i.t. post-treatment with clonidine up to 3 h caused an elevation of the blood glucose level and protected sepsis-induced mortality, whereas clonidine post-treated at 6, 9, or 12 h did not affect. The pre-treatment with oral D-glucose for 30 min prior to i.t. post-treatment (6 h) with clonidine did not rescue sepsis-induced mortality. In addition, i.t. pretreatment with pertussis toxin (PTX) reduced clonidine-induced protection against mortality and clonidine-induced hyperglycemia, suggesting that protective effect against sepsis-induced mortality seems to be mediated via activating PTX-sensitive G-proteins in the spinal cord. Moreover, pretreatment with clonidine attenuated the plasma tumor necrosis factor α (TNF-α) induced by sepsis. Clonidine administered i.t. or i.p. increased p-AMPKα1 and p-AMPKα2, but decreased p-Tyk2 and p-mTOR levels in both control and sepsis groups, suggesting that the up-regulations of p-AMPKα1 and p-AMPKα2, or down-regulations of p-mTOR and p-Tyk2 may play critical roles for the protective effect of clonidine against sepsis-induced mortality.

Altered hepatic lipid metabolism in mice lacking both the melanocortin type 4 receptor and low density lipoprotein receptor

Obesity is often associated with dyslipidemia and hepatosteatosis. A number of animal models of non-alcoholic fatty liver disease (NAFLD) are established but they significantly differ in the molecular and biochemical changes depending on the genetic modification and diet used. Mice deficient for melanocortin type 4 receptor (Mc4r^mut) develop hyperphagia, obesity, and subsequently NAFLD already under regular chow and resemble more closely the energy supply-driven obesity found in humans. This animal model was used to assess the molecular and biochemical consequences of hyperphagia-induced obesity on hepatic lipid metabolism. We analyzed transcriptome changes in Mc4r^mut mice by RNA sequencing and used high resolution ¹H magic angle spinning NMR spectroscopy and MALDI-TOF mass spectrometry to assess changes in the lipid composition. On the transcriptomic level we found significant changes in components of the triacylglycerol metabolism, unsaturated fatty acids biosynthesis, peroxisome proliferator-activated receptor signaling pathways, and lipid transport and storage compared to the wild-type. These findings were supported by increases in triacylglycerol, monounsaturated fatty acid, and arachidonic acid levels. The transcriptome signatures significantly differ from those of other NAFLD mouse models supporting the concept of hepatic subphenotypes depending on the genetic background and diet. Comparative analyses of our data with previous studies allowed for the identification of common changes and genotype-specific components and pathways involved in obesity-associated NAFLD.

Effect of D-glucose feeding on mortality induced by sepsis

Sepsis is the life-threatening response to infection which can lead to tissue damage, organ failure, and death. In the current study, the effect of orally administered D-glucose on the mortality and the blood glucose level induced by D-Galactosamine (GaLN)/lipopolysaccharide (LPS)-induced sepsis was examined in ICR mice. After various amounts of D-glucose (from 1 to 8 g/kg) were orally fed, sepsis was induced by injecting intraperitoneally (i.p.) the mixture of GaLN /LPS. Oral pre-treatment with D-glucose dose-dependently increased the blood glucose level and caused a reduction of sepsis-induced mortality. The oral post-treatment with D-glucose (8 g/kg) up to 3 h caused an elevation of the blood glucose level and protected the mortality observed in sepsis model. However, D-glucose post-treated at 6, 9, or 12 h after sepsis induction did not affect the mortality and the blood glucose level induced by sepsis. Furthermore, the intrathecal (i.t.) pretreatment once with pertussis toxin (PTX; 0.1 µg/5 ml) for 6 days caused a reduction of D-glucose-induced protection of mortality and hyperglycemia. Furthermore, once the hypoglycemic state is continued up to 6 h after sepsis initiated, sepsis-induced mortality could not be reversed by D-glucose fed orally. Based on these findings, it is assumed that the hypoglycemic duration between 3 and 6 h after the sepsis induction may be a critical time of period for the survival. D-glucose-induced protective effect against sepsis-induced mortality appears to be mediated via activating PTX-sensitive G-proteins in the spinal cord. Finally, the production of hyperglycemic state may be critical for the survival against the sepsis-induced mortality.

Year in review 2009: Critical Care--shock

The research papers on shock that have been published in Critical Care throughout 2009 are related to four major subjects: first, alterations of heart function and, second, the role of the sympathetic central nervous system during sepsis; third, the impact of hemodynamic support using vasopressin or its synthetic analog terlipressin, and different types of fluid resuscitation; as well as, fourth, experimental studies on the treatment of acute respiratory distress syndrome. The present review summarizes the key results of these studies together with a brief discussion in the context of the relevant scientific and clinical background published both in this and other journals.

Vasopressin for hemorrhagic shock management: revisiting the potential value in civilian and combat casualty care

The evolution of trauma care is driven by a synergistic relationship between civilian and military medical systems. Although the characteristics of civilian injuries differ from those encountered on the battlefield, the pathophysiologic process of dying is the same and dominated by exsanguination and central nervous trauma. As such, therapies that interfere with the physiologic ability to compensate hemorrhage may play a key role to buy time until hemostatic surgery can be initiated. From a variety of remedies with the potential to prolong the compensation phase or to reverse the decompensation phase of shock, arginine vasopressin (AVP) is one of the most promising and best-evaluated drugs. Animal studies and various case report series provide some evidence that AVP may improve blood pressure even when conventional therapies fail, thus preventing hypovolemic cardiac arrest and enabling resuscitation from fatal hemorrhage. On the basis of this civilian experience, it seems reasonable to consider AVP for hypotensive resuscitation in the austere, resource-constrained battlefield environment. However, the significance of AVP as a rescue medication for life-threatening hemorrhage has yet to be proven.

Vasoplegic syndrome during liver transplantation

A 56-yr-old woman with chronic hepatitis B and decompensated hepatic cirrhosis was treated with liver transplantation. At the beginning of the neohepatic phase, her arterial blood pressure remained at 60/40 mm Hg for approximately 40 min and did not respond to vasoconstrictive drugs. Her other clinical and laboratory values remained normal, apart from a high cardiac output and low systemic vascular resistance. This patient was diagnosed with vasoplegic syndrome and was treated with i.v. infusion of methylene blue (0.5 mg/kg) and norepinephrine. This report has potential significance to treatment in patients who undergo orthotopic liver transplantation.