Liver dysfunction and phosphatidylinositol-3-kinase signalling in early sepsis: experimental studies in rodent models of peritonitis

Monocyte upregulation of podoplanin during early sepsis induces complement inhibitor release to protect liver function

Multiple organ failure in sepsis is a progressive failure of several interdependent organ systems. Liver dysfunction occurs early during sepsis and is directly associated with patient death; however, the underlying mechanism of liver dysfunction is unclear. Platelet transfusion benefits patients with sepsis, and inhibition of complement activation protects liver function in septic animals. Herein, we explored the potential link between platelets, complement activation, and liver dysfunction in sepsis. We found that deletion of platelet C-type lectin-like receptor 2 (CLEC-2) exacerbated liver dysfunction in early sepsis. Platelet CLEC-2-deficient mice exhibited higher complement activation, more severe complement attack in the liver, and lower plasma levels of complement inhibitors at early time points after E. coli infection. Circulating monocytes expressed the CLEC-2 ligand podoplanin in early sepsis, and podoplanin binding induced release of complement inhibitors from platelets. Injection of complement inhibitors released from platelets reduced complement attack and attenuated liver dysfunction in septic mice. These findings indicate a new function of platelets in the regulation of complement activation during sepsis.

Comparison of albumin dialysis devices molecular adsorbent recirculating system and ADVanced Organ Support system in critically ill patients with liver failure-A retrospective analysis

Extracorporeal albumin dialysis (ECAD) represents a supplemental therapy for patients with liver failure. Most experience was gained with the molecular adsorbent recirculating system (MARS). However, the ADVanced Organ Support (ADVOS) system was recently introduced. This study aims to compare effects of MARS and ADVOS on biochemical and clinical parameters in critically ill patients with liver failure using a retrospective analysis of ECAD at Jena University Hospital. Laboratory parameters, health scoring values, and need for transfusion were recorded before and after treatment. Generalized estimating equations were used to account for repeated measurements of multiple ECAD cycles per patient. Between 2012 and 2017, n = 75 MARS and n = 58 ADVOS cycles were evaluated. Although ADVOS runs significantly longer, both devices provided comparable reduction rates of bilirubin (MARS: -48 [-80.5 to -18.5] μmol/L vs ADVOS: -35 [-87.8 to -2.0] μmol/L, P = .194), a surrogate for detoxification capacity, while urea and lactate levels were more significantly lowered by the ADVOS system. In cycles with similar treatment times, both systems provided comparable reduction rates for bilirubin, renal replacement, coagulation, and metabolic parameters. Citrate was the preferred anticoagulant in case of bleeding. Neither bleeding tendency nor fibrinogen levels or platelets were altered by the type of anticoagulation. No adverse events were reported, but two sessions (one MARS and one ADVOS) were terminated early due to filter clotting. Experience is needed in the application of ADVOS and more prospective trials comparing the detoxification capacity of ECAD devices are needed to support and enlarge the findings of the current evaluation.

HSPA12A attenuates lipopolysaccharide-induced liver injury through inhibiting caspase-11-mediated hepatocyte pyroptosis via PGC-1α-dependent acyloxyacyl hydrolase expression

Liver dysfunction is strongly associated with poor survival of sepsis patients. Cytosolic lipopolysaccharide (LPS) sensing by Caspase-4/5/11 for pyroptosis activation is a major driver of the development of sepsis. Studies in macrophages and endothelial cells have demonstrated that LPS is inactivated by acyloxyacyl hydrolase (AOAH) and leading to desensitizing Caspase-4/5/11 to LPS. However, little is known about the cytosolic LPS-induced pyroptosis in hepatocytes during sepsis. Heat shock protein 12A (HSPA12A) is a novel member of the HSP70 family. Here, we report that LPS increased HSPA12A nuclear translocation in hepatocytes, while knockout of HSPA12A (Hspa12a^−/−) in mice promoted LPS-induced acute liver injury. We also noticed that the LPS-induced Caspase-11 activation and its cleavage of gasdermin D (GSDMD) to produce the membrane pore-forming GSDMD^Nterm (markers of pyroptosis) were greater in livers of Hspa12a^−/− mice compared with its wild type controls. Loss- and gain-of-function studies showed that HSPA12A deficiency promoted, whereas HSPA12A overexpression inhibited, cytosolic LPS accumulation, Caspase-11 activation and GSDMD^Nterm generation in primary hepatocytes following LPS incubation. Notably, LPS-induced AOAH expression was suppressed by HSPA12A deficiency, whereas AOAH overexpression reversed the HSPA12A deficiency-induced promotion of LPS-evoked and Caspase-11-mediated pyroptosis of hepatocytes. In-depth molecular analysis showed that HSPA12A interacted directly with peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α) and increased its nuclear translocation, thereby inducing AOAH expression for cytosolic LPS inactivation, which ultimately leading to inhibition of the Caspase-11 mediated pyroptosis of hepatocytes. Taken together, these findings revealed HSPA12A as a novel player against LPS-induced liver injury by inhibiting cytosolic LPS-induced hepatocyte pyroptosis via PGC-1α-mediated AOAH expression. Therefore, targeting hepatocyte HSPA12A represents a viable strategy for the management of liver injury in sepsis patients.

Part II: Minimum Quality Threshold in Preclinical Sepsis Studies (MQTiPSS) for Types of Infections and Organ Dysfunction Endpoints

Although the clinical definitions of sepsis and recommended treatments are regularly updated, a systematic review has not been done for preclinical models. To address this deficit, a Wiggers-Bernard Conference on preclinical sepsis modeling reviewed the 260 most highly cited papers between 2003 and 2012 using sepsis models to create a series of recommendations. This Part II report provides recommendations for the types of infections and documentation of organ injury in preclinical sepsis models. Concerning the types of infections, the review showed that the cecal ligation and puncture model was used for 44% of the studies while 40% injected endotoxin. Recommendation #8 (numbered sequentially from Part I): endotoxin injection should not be considered as a model of sepsis; live bacteria or fungal strains derived from clinical isolates are more appropriate. Recommendation #9: microorganisms should replicate those typically found in human sepsis. Sepsis-3 states that sepsis is life-threatening organ dysfunction caused by a dysregulated host response to infection, but the review of the papers showed limited attempts to document organ dysfunction. Recommendation #10: organ dysfunction definitions should be used in preclinical models. Recommendation #11: not all activities in an organ/system need to be abnormal to verify organ dysfunction. Recommendation #12: organ dysfunction should be measured in an objective manner using reproducible scoring systems. Recommendation #13: not all experiments must measure all parameters of organ dysfunction, but investigators should attempt to fully capture as much information as possible. These recommendations are proposed as "best practices" for animal models of sepsis.

GTS-21 ameliorates polymicrobial sepsis-induced hepatic injury by modulating autophagy through α7nAchRs in mice

BACKGROUND

Previous studies showed that GTS-21, a selective alpha 7 nAchR agonist, can trigger anti-inflammatory effects and improve the survival of septic animals. However, whether GTS-21 affects autophagy responses remains unclear. Here, we tested the hypothesis that GTS-21 ameliorates sepsis-induced hepatic injury by modulating autophagy in mice.

METHOD

C57BL/6 male mice were randomly separated and categorized into four groups: the sham group, and CLP group subjected to caecal ligation and puncture (CLP, a model of polymicrobial sepsis). The CLP + GTS-21 group was administered GTS-21 immediately after CLP challenge. α-Bungarotoxin (an alpha 7 nAchR antagonist) was injected before CLP was performed, and then, after CLP challenge, GTS-21 was administered to α-BGT + CLP + GTS-21 group. The hepatic tissue and blood samples were harvested 6 h after the operation.

RESULTS

CLP challenge increased TNF-α and IL-6 production, and hepatic enzyme alanine aminotransferase and aspartate transaminase levels. CLP also elevated the expression of hepatic LC3-II, sequestosome-1/p62, Atg7 and Atg5. The administration of GTS-21 inhibited pro-inflammatory cytokine production and hepatic enzymatic marker expression, promoted the expression of LC3-II, Atg7, Atg5, and decreased the expression of p62, which could be reversed by α-BGT treatment.

CONCLUSION

Our findings suggested that α7nAchR is involved in diminishing hepatic damage by inhibiting inflammatory responses and improving autophagy in mice with polymicrobial sepsis.

Liver Injury and Failure in Critical Illness

The frequency of acquired liver injury and failure in critical illness has been significantly increasing over recent decades. Currently, liver injury and failure are observed in up to 20% of patients in intensive care units and are associated with significantly increased morbidity and mortality. Secondary forms of liver injury in critical illness are divided primarily into cholestatic, hypoxic, or mixed forms. Therefore, sufficient knowledge of underlying alterations (e.g., hemodynamic, inflammatory, or drug induced) is key to a better understanding of clinical manifestations, prognostic implications, as well as diagnostic and therapeutic options of acquired liver injury and failure. This review provides a structured approach for the evaluation and treatment of acquired liver injury and failure in critically ill patients.

IL-27 is elevated in sepsis with acute hepatic injury and promotes hepatic damage and inflammation in the CLP model

BACKGROUND

Immuno-inflammation plays an important role in the pathophysiological process of sepsis-associated acute hepatic injury (AHI). Interleukin 27 (IL-27) is an important inflammatory regulator; however, its role in this condition is not clear.

METHODS

The clinical data and IL-27 serum levels in sepsis patients with or without AHI were analysed. Classical caecal ligation puncture (CLP) models were established in wild-type (WT) and IL-27 receptor (WSX-1)-deficient (IL-27R^-/-) mice. In addition, exogenous IL-27 was injected into these mice, and the levels of IL-27, IL-6, and tumour necrosis factor alpha (TNF-α) in the serum and liver were then measured by enzyme-linked immunoassay (ELISA), quantitative PCR, and Western blotting. The severity of liver damage was evaluated by haematoxylin and eosin staining of liver tissue, TUNEL assay and evaluation of alanine aminotransferase (ALT) and aspartate transaminase (AST) serum levels. Furthermore, the effects of IL-27 on the levels of phosphorylated c-Jun N-terminal kinase (JNK) in macrophages were assessed by Western blotting, and the effects of IL-27 on the expression of IL-6 and TNF-α in macrophages were assessed by ELISA.

RESULTS

IL-27 was elevated in sepsis patients with acute hepatic injury, which correlated with the Acute Physiologic Assessment and Chronic Health Evaluation II (APACHEII) scores, Sequential Organ Failure Assessment (SOFA) scores, and procalcitonin, C-reactive protein, IL-6, and TNF-α expression. In the CLP-WT group, IL-27 was highly expressed in the serum and liver, which correlated with the elevated content of ALT, AST, TNF-α, IL-6, and p-JNK in the serum and liver and the pathological injury of the liver. In CLP-IL-27R^-/- group, however, the levels of ALT, AST, TNF-α, IL-6, and p-JNK in the serum and liver and the pathological injury of the liver were decreased. Treatment with exogenous IL-27 led to a further increase in these cytokines in WT mice after CLP. IL-27 treatment and lipopolysaccharide stimulation in vitro increased the expression of p-JNK, IL-6, and TNF-α in macrophages, and these changes were decreased by a JNK signalling pathway inhibitor.

CONCLUSION

IL-27 is elevated in sepsis patients, especially those with acute hepatic injury. In addition, IL-27 can promote inflammatory reactions in the CLP-induced hepatic injury mice model.

Toll-like receptors 2 and 7 mediate coagulation activation and coagulopathy in murine sepsis

BACKGROUND

Sepsis is a life-threatening condition often manifested as marked inflammation and severe coagulopathy. Toll-like receptors (TLRs) play a pivotal role in inflammation, organ dysfunction and mortality in animal sepsis.

OBJECTIVES

To investigate the role of TLR signaling in mediating sepsis-induced coagulopathy (SIC) in a mouse model.

METHODS

Polymicrobial sepsis was created by cecal ligation and puncture (CLP) or fecal slurry peritoneal injection. To quantify global clotting function, two viscoelastic assays were performed with rotational thromboelastometry, and the results were presented as maximum clot firmness (MCF): (a) EXTEM to test tissue factor (TF)-initiated clot formation; and (b) FIBTEM to test EXTEM in the presence of a platelet inhibitor, cytochalasin D. Plasma coagulation factors were quantified with ELISA. TF gene expression and protein expression were determined with real-time quantitative reverse transcription PCR and flow cytometry, respectively.

RESULTS

Between 4 and 24 hours after CLP surgery, wild-type mice showed significant MCF reduction in both EXTEM and FIBTEM tests. This was accompanied by marked thrombocytopenia and a significant increase in the levels of plasminogen activator inhibitor-1, plasma TF, and D-dimer. In comparison, TLR2-/- and TLR7-/- CLP mice showed preserved MCF and platelet counts, and near-normal plasma TF levels. Bone marrow-derived macrophages treated with a TLR2 agonist Pam3cys-Ser-(Lys)4 (Pam3cys) or a TLR7 agonist (R837) showed marked increases in TF gene expression and protein expression. MicroRNA-146a, a newly identified proinflammatory mediator that is upregulated during sepsis, induced TF production via a TLR7-dependent mechanism.

CONCLUSIONS

Murine sepsis leads to an increased procoagulant response, thrombocytopenia, and global coagulopathy. TLR2 and TLR7 play an important role in procoagulant production and in SIC.

On the Role of Illness Duration and Nutrient Restriction in Cholestatic Alterations that Occur During Critical Illness

Supplemental Digital Content is available in the text

Background and Aims:

Elevated markers of cholestasis are common in response to critical illness, and associated with adverse outcome. The role of illness duration and of nutrient restriction on underlying molecular pathways of such cholestatic responses have not been thoroughly investigated.

Methods:

In a mouse model of surgery- and sepsis-induced critical illness, molecular pathways of cholestasis were investigated up to 7 days. To assess which changes are explained by illness-induced lack of feeding, nutrient-restricted healthy mice were studied and compared with ad libitum fed healthy mice. Furthermore, serum bile acid (BA) concentrations were quantified in 1,114 human patients with either short or long intensive care unit (ICU) stay, matched for type and severity of illness, up to ICU-day-7.

Results:

In critically ill mice, either evoked by surgery or sepsis, circulating and hepatic BA-levels progressively increased with time from day-3 onward, preceded by unsuppressed or upregulated CYP7A1 and CYP27A1 protein expression. From 30 h onward, nuclear farnesoid-X-receptor-retinoid-X-receptor staining was significantly suppressed in both critically ill groups, followed from day-3 onward by decreased gene expression of the apical exporter BA-specific export pump and increased expression of basolateral exporters multidrug resistance-associated protein 3 (MRP3) and MRP4. Nutrient restriction in healthy mice only partly mirrored illness-induced alterations in circulating BA and BA-transporters, without changing nuclear receptors or synthesis markers expression. Also in human critically ill patients, serum BA increased with time in long-stay patients only, similarly for patients with or without sepsis.

Conclusions:

Circulating BA concentrations rose days after onset of sepsis- and surgery-induced, critical illness, only partially explained by lack of feeding, preceded by suppressed nuclear feedback-sensors and ongoing BA synthesis. Expression of transporters suggested ongoing reversed BA-flow toward the blood.

Identification of Metabolic Changes in Ileum, Jejunum, Skeletal Muscle, Liver, and Lung in a Continuous I.V. Pseudomonas aeruginosa Model of Sepsis Using Nontargeted Metabolomics Analysis

Sepsis is a multiorgan disease affecting the ileum and jejunum (small intestine), liver, skeletal muscle, and lung clinically. The specific metabolic changes in the ileum, jejunum, liver, skeletal muscle, and lung have not previously been investigated. Live Pseudomonas aeruginosa, isolated from a patient, was given via i.v. catheter to pigs to induce severe sepsis. Eighteen hours later, ileum, jejunum, medial gastrocnemius skeletal muscle, liver, and lung were analyzed by nontargeted metabolomics analysis using gas chromatography/mass spectrometry. The ileum and the liver demonstrated significant changes in metabolites involved in linoleic acid metabolism: the ileum and lung had significant changes in the metabolism of valine/leucine/isoleucine; the jejunum, skeletal muscle, and liver had significant changes in arginine/proline metabolism; and the skeletal muscle and lung had significant changes in aminoacyl-tRNA biosynthesis, as analyzed by pathway analysis. Pathway analysis also identified changes in metabolic pathways unique for different tissues, including changes in the citric acid cycle (jejunum), β-alanine metabolism (skeletal muscle), and purine metabolism (liver). These findings demonstrate both overlapping metabolic pathways affected in different tissues and those that are unique to others and provide insight into the metabolic changes in sepsis leading to organ dysfunction. This may allow therapeutic interventions that focus on multiple tissues or single tissues once the relationship of the altered metabolites/metabolism to the underlying pathogenesis of sepsis is determined.

Effect of landiolol on sex-related transcriptomic changes in the myocardium during sepsis

Objectives

The aims of this study are to better understand phenotypic differences between male and female rats during sepsis, to characterise the contribution of the beta1-adrenergic blocker landiolol to septic cardiomyopathy and to determine why landiolol induces divergent effects in males and females.

Methods

The myocardial transcriptional profiles in male and female Wistar rats were assessed after the induction of sepsis by cecal ligation and puncture and addition of landiolol.

Results

Our results showed major differences in the biological processes activated during sepsis in male and female rats. In particular, a significant decrease in processes related to cell organisation, contractile function, ionic transport and phosphoinositide-3-kinase/AKT (PI3K/AKT) signalling was observed only in males. The transcript of ATPase sarcoplasmic/endoplasmic reticulum Ca²⁺ transporting 3 (SERCA3) was sex-differently regulated. In males, landiolol reversed several signalling pathways dysregulated during sepsis. The expression level of genes encoding tubulin alpha 8 (TUBA8) and myosin heavy chain 7B (MYH7) contractile proteins, phosphatase 2 catalytic subunit alpha (PPP2CA), G protein-coupled receptor kinase 5 (GRK5) and A-kinase anchoring protein 6 (AKAP6) returned to their basal levels. In contrast, in females, landiolol had limited effects.

Conclusion

In males, landiolol reversed the expression of many genes that were deregulated in sepsis. Conversely, sepsis-induced deregulation of gene expression was less pronounced in females than in males, and was maintained in the landiolol-treated females. These findings highlight important sex-related differences and confirm previous observations on the important benefit of landiolol intake on cardiac function in male rats.

Electronic supplementary material

The online version of this article (10.1186/s40635-019-0263-0) contains supplementary material, which is available to authorized users.

Protective role of thymoquinone in sepsis-induced liver injury in BALB/c mice

Sepsis increases the risk of developing liver injury. Previous studies have demonstrated that thymoquinone (TQ) exhibits hepatoprotective properties in vivo as well as in vitro. The present study aimed to investigate the underlying mechanisms of the protective effects of TQ against liver injury in septic BALB/c mice. Male BALB/c mice (age, 8 weeks) were randomly divided into four groups, namely, the control, TQ (50 mg/kg/day) treatment, cecal ligation and puncture (CLP), and TQ + CLP groups. CLP was performed following gavage of TQ for 2 weeks. At 48 h post-CLP, the histopathological alterations in the liver tissue (LT) and plasma levels of serum alanine aminotransferase (ALT), aspartate aminotransferase (AST) and alkaline phosphatase (ALP) were assessed. The present study evaluated microtubule-associated protein light chain 3 (LC3), sequestosome-1 (p62) and beclin 1 protein expression by western blotting and immunostaining, as well as interleukin (IL)-6, IL-1β, IL-10, monocyte chemoattractant protein-1 (MCP-1) and tumor necrosis factor-α (TNF-α) mRNA expression by RT-qPCR. The results of the present study indicated that administration of TQ to mice reduced the histological alterations caused by CLP in LT. TQ inhibited the plasma levels of ALT, AST and ALP in the CLP group. TQ significantly inhibited the elevation of p62, IL-1β, IL-6, MCP-1 and TNF-α levels as well as increased the LC3, beclin 1 and IL-10 levels in LT. PI3K expression in the TQ + CLP group was significantly decreased compared with that in the CLP group. TQ treatment effectively modulated the expression levels of p62, LC3, beclin 1, PI3K and proinflammatory cytokines, and may be an important agent for the treatment of sepsis-induced liver injury.

CAAP48, a New Sepsis Biomarker, Induces Hepatic Dysfunction in an in vitro Liver-on-Chip Model

Sepsis is a leading cause of mortality in the critically ill, characterized by life-threatening organ dysfunctions due to dysregulation of the host response to infection. Using mass spectrometry, we identified a C-terminal fragment of alpha-1-antitrypsin, designated CAAP48, as a new sepsis biomarker that actively participates in the pathophysiology of sepsis. It is well-known that liver dysfunction is an early event in sepsis-associated multi-organ failure, thus we analyzed the pathophysiological function of CAAP48 in a microfluidic-supported in vitro liver-on-chip model. Hepatocytes were stimulated with synthetic CAAP48 and several control peptides. CAAP48-treatment resulted in an accumulation of the hepatocyte-specific intracellular enzymes aspartate- and alanine-transaminase and impaired the activity of the hepatic multidrug resistant-associated protein 2 and cytochrome P450 3A4. Moreover, CAAP48 reduced hepatic expression of the multidrug resistant-associated protein 2 and disrupted the endothelial structural integrity as demonstrated by reduced expression of VE-cadherin, F-actin and alteration of the tight junction protein zonula occludens-1, which resulted in a loss of the endothelial barrier function. Furthermore, CAAP48 induced the release of adhesion molecules and pro- and anti-inflammatory cytokines. Our results show that CAAP48 triggers inflammation-related endothelial barrier disruption as well as hepatocellular dysfunction in a liver-on-chip model emulating the pathophysiological conditions of inflammation. Besides its function as new sepsis biomarker, CAAP48 thus might play an important role in the development of liver dysfunction as a consequence of the dysregulated host immune-inflammatory response in sepsis.

Microphysiological systems meet hiPSC technology - New tools for disease modeling of liver infections in basic research and drug development

Complex cell culture models such as microphysiological models (MPS) mimicking human liver functionality in vitro are in the spotlight as alternative to conventional cell culture and animal models. Promising techniques like microfluidic cell culture or micropatterning by 3D bioprinting are gaining increasing importance for the development of MPS to address the needs for more predictivity and cost efficiency. In this context, human induced pluripotent stem cells (hiPSCs) offer new perspectives for the development of advanced liver-on-chip systems by recreating an in vivo like microenvironment that supports the reliable differentiation of hiPSCs to hepatocyte-like cells (HLC). In this review we will summarize current protocols of HLC generation and highlight recently established MPS suitable to resemble physiological hepatocyte function in vitro. In addition, we are discussing potential applications of liver MPS for disease modeling related to systemic or direct liver infections and the use of MPS in testing of new drug candidates.

The Systemic Alterations of Lipids, Alanine-Glucose Cycle and Inter-Organ Amino Acid Metabolism in Swine Model Confirms the Role of Liver in Early Phase of Septic Shock

Septic shock is a medical emergency and is one of the main causes of mortality in critically ill patients. Given the pathophysiological complexity of sepsis spectrum and progression in clinical settings, animal models become essential tools to improve patient care, and to understand key mechanisms that may remain masked from the heterogeneity of clinical practice. Our aim was to verify whether the metabolic constellations we previously reported for septic shock patients appear also in our septic shock swine model as systemic markers of early disturbances in energy metabolism and hepatic homeostasis. Septic shock was induced in anesthetized, instrumented, and ventilated adult swines by polymicrobial peritonitis. Hemodynamic and serial measurements of arterial and mixed venous blood gasses were made. Laboratory measurements and mass spectrometry-based targeted quantitative plasma metabolomics were performed in blood samples collected at baseline, at shock and at fully resuscitation after fluids and vasopressors administration. Data elaboration was performed by multilevel and multivariate analysis. Changes in hemodynamic, blood chemistry, and inflammatory markers were in line with a septic shock phenotype. Time course alteration of systemic metabolites were characterized by marked decreased in phosphatidylcholines and lysophosphatidylcholines species, altered alanine-glucose cycle and inter-organ amino acid metabolism, pointing toward an early hepatic impairment similarly to what we previously reported for septic shock. This is the first study in which an experimental swine model of septic shock recapitulates the main metabolic derangements reported in a clinical setting of shock. These events occur within hours from infections and may act as early metabolic features to assist in evaluating subclinical hepatic alterations and pave the way to improve the management of septic shock.

Acid Sphingomyelinase Inhibition Stabilizes Hepatic Ceramide Content and Improves Hepatic Biotransformation Capacity in a Murine Model of Polymicrobial Sepsis

Liver dysfunction during sepsis is an independent risk factor leading to increased mortality rates. Specifically, dysregulation of hepatic biotransformation capacity, especially of the cytochrome P450 (CYP) system, represents an important distress factor during host response. The activity of the conserved stress enzyme sphingomyelin phosphodiesterase 1 (SMPD1) has been shown to be elevated in sepsis patients, allowing for risk stratification. Therefore, the aim of the present study was to investigate whether SMPD1 activity has an impact on expression and activity of different hepatic CYP enzymes using an animal model of polymicrobial sepsis. Polymicrobial sepsis was induced in SMPD1 wild-type and heterozygous mice and hepatic ceramide content as well as CYP mRNA, protein expression and enzyme activities were assessed at two different time points, at 24 h, representing the acute phase, and at 28 days, representing the post-acute phase of host response. In the acute phase of sepsis, SMPD1^+/+ mice showed an increased hepatic C16- as well as C18-ceramide content. In addition, a downregulation of CYP expression and activities was detected. In SMPD1^+/- mice, however, no noticeable changes of ceramide content and CYP expression and activities during sepsis could be observed. After 28 days, CYP expression and activities were normalized again in all study groups, whereas mRNA expression remained downregulated in SMPD^+/+ animals. In conclusion, partial genetic inhibition of SMPD1 stabilizes hepatic ceramide content and improves hepatic monooxygenase function in the acute phase of polymicrobial sepsis. Since we were also able to show that the functional inhibitor of SMPD1, desipramine, ameliorates downregulation of CYP mRNA expression and activities in the acute phase of sepsis in wild-type mice, SMPD1 might be an interesting pharmacological target, which should be further investigated.

The role of bile acids in nutritional support

Nutritional support continues to receive much attention as a possible intervention to prevent loss of lean tissue mass, promote recovery and re-establish proper immune function in critical care patients. Yet there remains much controversy regarding the clinical efficacy of such interventions. In addition to the direct effect of nutrition in terms of micro- and macronutrient content, nutritional formulations may exert an effect via the physiological response to feeding. Here, we highlight the key role of postprandial reabsorbed bile acids in attenuating both the inflammatory response and autophagy. These observations suggest that not all patients would benefit from aggressive nutritional support.

Emodin Attenuates Lipopolysaccharide-Induced Acute Liver Injury via Inhibiting the TLR4 Signaling Pathway in vitro and in vivo

Aims: Emodin is an anthraquinone with potential anti-inflammatory properties. However, the possible molecular mechanisms and protective effects of emodin are not clear. The objective of this study was to investigate the possible molecular mechanisms and protective effects of emodin on lipopolysaccharide (LPS)-induced acute liver injury (ALI) via the Toll-like receptor 4 (TLR4) signaling pathway in the Raw264.7 cell line and in Balb/c mice. Methods: This study established an inflammatory cellular model and induced an ALI animal model. TLR4 was overexpressed by lentivirus and downregulated by small interfering RNA (siRNA) technology. The mRNA and protein levels of TLR4 and downstream molecules were detected in cells and liver tissue. The tumor necrosis factor-α (TNF-α) and interleukin (IL)-6 levels in supernatant and serum were determined by ELISA. The distribution and expression of mannose receptor C type 1 (CD206) and arginase 1 (ARG1) in the liver were tested by immunofluorescence. Mouse liver function and histopathological observations were assessed. Results: Administration of emodin reduced the protein and/or mRNA levels of TLR4 and its downstream molecules following LPS challenge in Raw264.7 cells and in an animal model. Additionally, emodin suppressed the expression of TNF-α and IL-6 in cell culture supernatant and serum. The inhibitory effect of emodin was also confirmed in RAW264.7 cells, in which TLR4 was overexpressed or knocked down. Additionally, ARG1 and CD206 were elevated in the emodin groups. Emodin also decreased serum ALT and AST levels and alleviated the liver histopathological damage induced by LPS. Conclusion: Emodin showed excellent hepatoprotective effects against LPS-induced ALI, possibly by inhibiting TLR4 signaling pathways.

Deterioration of Organ Function As a Hallmark in Sepsis: The Cellular Perspective

Development of organ dysfunction discriminates sepsis from uncomplicated infection. The paradigm shift implicated by the new sepsis-3 definition holds that initial impairment of any organ can pave the way for multiple organ dysfunction and death. Moreover, the role of the systemic inflammatory response, central element in previous sepsis definitions, has been questioned. Most strikingly, a so far largely underestimated defense mechanism of the host, i.e., "disease tolerance," which aims at maintaining host vitality without reducing pathogen load, has gained increasing attention. Here, we summarize evidence that a dysregulation of critical cellular signaling events, also in non-immune cells, might provide a conceptual framework for sepsis-induced dysfunction of parenchymal organs in the absence of significant cell death. We suggest that key signaling mediators, such as phosphoinositide 3-kinase, mechanistic target of rapamycin, and AMP-activated protein kinase, control the balance of damage and repair processes and thus determine the fate of affected organs and ultimately the host. Therapeutic targeting of these multifunctional signaling mediators requires cell-, tissue-, or organ-specific approaches. These novel strategies might allow stopping the domino-like damage to further organ systems and offer alternatives beyond the currently available strictly supportive therapeutic options.

Molecular signatures of liver dysfunction are distinct in fungal and bacterial infections in mice

Rationale: The liver is a central organ not only for metabolism but also immune function. Life-threatening infections of both bacterial and fungal origin can affect liver function but it is yet unknown whether molecular changes differ depending on the pathogen. We aimed to determine whether the hepatic host response to bacterial and fungal infections differs in terms of hepatic metabolism and liver function. Methods: We compared murine models of infection, including bacterial peritoneal contamination and infection (PCI), intraperitoneal and systemic C. albicans infection, at 6 and 24 h post-infection, to sham controls. The molecular hepatic host response was investigated by the detection of regulatory modules based on large-scale protein-protein interaction networks and expression data. Topological analysis of these regulatory modules was used to reveal infection-specific biological processes and molecular mechanisms. Intravital microscopy and immunofluorescence microscopy were used to further analyze specific aspects of pathophysiology such as cholestasis. Results: Down-regulation of lipid catabolism and bile acid synthesis was observed after 6 h in all infection groups. Alterations in lipid catabolism were characterized by accumulation of long chain acylcarnitines and defective beta-oxidation, which affected metabolism by 6 h. While PCI led to an accumulation of unconjugated bile acids (BA), C. albicans infection caused accumulation of conjugated BA independent of the route of infection. Hepatic dye clearance and transporter expression revealed reduced hepatic uptake in fungal infections vs. defects in secretion following polybacterial infection. Conclusion: Molecular phenotypes of lipid accumulation and cholestasis allow differentiation between pathogens as well as routes of infection at early stages in mice. Targeted metabolomics could be a useful tool for the profiling of infected/septic patients and the type of pathogen, with subsequent customization and targeting of therapy.

Delayed activation of PPAR-β/δ improves long-term survival in mouse sepsis: effects on organ inflammation and coagulation

Activation of peroxisome proliferator-activated receptor (PPAR)-β/δ reduces tissue injury in murine endotoxemia. We hypothesized that the PPAR-β/δ-agonist GW0742 improves long-term outcome after sepsis caused by cecal ligation and puncture (CLP). Fifty-one CD-1 female mice underwent CLP and received either vehicle (control), GW0742 (0.03 mg/kg/injection; five post-CLP i.v. injections), GSK0660 (PPAR-β/δ-antagonist) or both and were monitored for 28 d. Another 20 CLP mice treated with GW0742 and vehicle were sacrificed 24 h post-CLP to assess coagulopathy. Compared to vehicle, survival of CLP-mice treated with GW0742 was higher by 35% at d 7 and by 50% at d 28. CLP mice treated with GW0742 had 60% higher IFN-γ but circulating monocyte chemoattractant protein-1 and chemokine ligand were lower at 48 h post-CLP. Compared to vehicle, CLP mice treated with GW0742 exhibited a 50% reduction in the circulating plasminogen activator inhibitor-1 associated with an increase in platelet number at 24 h post-CLP (but no changes occurred in anti-thrombin-III, plasminogen, fibrinogen and clotting-times). CLP mice treated with GW0742 exhibited a similar increase in most of the biochemical markers of organ injury/dysfunction (lactate dehydrogenase, alanine aminotransferase, creatine kinase, creatinine, blood urea nitrogen, and triglycerides) measured. Treatment with GW0742 consistently improved long-term survival in septic CD-1 mice by partially modulating the post-CLP systemic cytokine response and coagulation systems.

Identification of genes related to consecutive trauma-induced sepsis via gene expression profiling analysis

We aimed to identify crucial genes relevant to the development of consecutive trauma-induced sepsis.A microarray dataset was used to identify genes differentially expressed between peripheral blood samples from consecutive traumatized patients complicated with sepsis and not complicated with sepsis. The dataset GSE12624 was obtained from Gene Expression Omnibus, containing 34 peripheral blood samples from consecutive traumatized patients complicated by sepsis and 36 consecutive traumatized controls. The differentially expressed genes (DEGs) were identified using Linear Models for Microarray Data package. Then, gene ontology (GO) enrichment analysis for DEGs was performed by Onto-Express. Subsequently, the protein-protein interaction (PPI) network was constructed and pathway enrichment analysis was performed by Search Tool for the Retrieval of Interacting Genes (STRING). Furthermore, protein complexes in the PPI network were predicted by ClusterONE and validated through GO and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analyses, and protein domain analysis.Totally, 446 upregulated and 447 downregulated DEGs were identified. Some DEGs were related to acyl-CoA binding (eg, ACBD6), chromosome, and centromeric region (eg, CENPN). In the PPI network, some DEGs were enriched in renin-angiotensin system (RAS, eg, AGTR1 and AGTR2). Three predicted protein complexes were validated in the PPI network. Some genes composing protein complex A were associated with cell proliferation (eg, CDC20, CCNB1, MCM4, RPA2, and PRIM2), and several genes composing protein complex F were implicated in regulation of actin cytoskeleton (eg, PFN2, ARPC2, and WASL).The results suggest that those DEGs may be crucial in the etiology of consecutive trauma-induced sepsis, and they are expected to be therapeutic targets.

Rare variants in drug target genes contributing to complex diseases, phenome-wide

The DrugBank database consists of ~800 genes that are well characterized drug targets. This list of genes is a useful resource for association testing. For example, loss of function (LOF) genetic variation has the potential to mimic the effect of drugs, and high impact variation in these genes can impact downstream traits. Identifying novel associations between genetic variation in these genes and a range of diseases can also uncover new uses for the drugs that target these genes. Phenome Wide Association Studies (PheWAS) have been successful in identifying genetic associations across hundreds of thousands of diseases. We have conducted a novel gene based PheWAS to test the effect of rare variants in DrugBank genes, evaluating associations between these genes and more than 500 quantitative and dichotomous phenotypes. We used whole exome sequencing data from 38,568 samples in Geisinger MyCode Community Health Initiative. We evaluated the results of this study when binning rare variants using various filters based on potential functional impact. We identified multiple novel associations, and the majority of the significant associations were driven by functionally annotated variation. Overall, this study provides a sweeping exploration of rare variant associations within functionally relevant genes across a wide range of diagnoses.

FC-99 ameliorates sepsis-induced liver dysfunction by modulating monocyte/macrophage differentiation via Let-7a related monocytes apoptosis

Background

The liver is a vital target for sepsis-related injury, leading to inflammatory pathogenesis, multiple organ dysfunction and high mortality rates. Monocyte-derived macrophage transformations are key events in hepatic inflammation. N¹-[(4-methoxy)methyl]-4-methyl-1,2-benzenediamine (FC-99) previously displayed therapeutic potential on experimental sepsis. However, the underlying mechanism of this protective effect is still not clear.

Results

FC-99 treatment attenuated the liver dysfunction in septic mice that was accompanied with reduced numbers of pro-inflammatory Ly6C^hi monocytes in the peripheral blood and CD11b⁺F4/80^lo monocyte-derived macrophages in the liver. These effects were attributed to the FC-99-induced apoptosis of CD11b⁺ cells. In PMA-differentiated THP-1 cells, FC-99 repressed the expression of CD11b, CD14 and caspase3 and resulted in a high proportion of Annexin V⁺ cells. Moreover, let-7a-5p expression was abrogated upon CLP stimulation in vivo, whereas it was restored by FC-99 treatment. TargetScan analysis and luciferase assays indicated that the anti-apoptotic protein BCL-XL was targeted by let-7a-5p. BCL-XL was inhibited by FC-99 in order to induce monocyte apoptosis, leading to the impaired monocyte-to-macrophage differentiation.

Materials and Methods

Murine acute liver failure was generated by caecal ligation puncture surgery after FC-99 administration; Blood samples and liver tissues were collected to determine the monocyte/macrophage subsets and the induction of apoptosis. Human acute monocytic leukemia cell line (THP-1) cells were pretreated with FC-99 followed by phorbol-12-myristate-13-acetate (PMA) stimulation, in order to induce monocyte-to-macrophage differentiation. The target of FC-99 and the mechanistic analyses were conducted by microarrays, qRT-PCR validation, TargetScan algorithms and a luciferase report assay.

Conclusions

FC-99 exhibits potential therapeutic effects on CLP-induced liver dysfunction by restoring let-7a-5p levels.

Photonic monitoring of treatment during infection and sepsis: development of new detection strategies and potential clinical applications

Despite the strong decline in the infection-associated mortality since the development of the first antibiotics, infectious diseases are still a major cause of death in the world. With the rising number of antibiotic-resistant pathogens, the incidence of deaths caused by infections may increase strongly in the future. Survival rates in sepsis, which occurs when body response to infections becomes uncontrolled, are still very poor if an adequate therapy is not initiated immediately. Therefore, approaches to monitor the treatment efficacy are crucially needed to adapt therapeutic strategies according to the patient's response. An increasing number of photonic technologies are being considered for diagnostic purpose and monitoring of therapeutic response; however many of these strategies have not been introduced into clinical routine, yet. Here, we review photonic strategies to monitor response to treatment in patients with infectious disease, sepsis, and septic shock. We also include some selected approaches for the development of new drugs in animal models as well as new monitoring strategies which might be applicable to evaluate treatment response in humans in the future. Figure Label-free probing of blood properties using photonics.

Obeticholic acid protects mice against lipopolysaccharide-induced liver injury and inflammation

BACKGROUND

Cholestasis, as a main manifestation, induces liver injury during sepsis. The farnesoid X receptor (FXR) plays an important role in regulating bile acid homeostasis. Whether FXR activation by its agonist obeticholic acid (OCA) is contributed to improve sepsis-induced liver injury remains unknown.

OBJECTIVE

The aim of the present study was to investigate the effect of OCA on lipopolysaccharide (LPS)-induced acute liver injury in mice.

RESULTS

8-week old male C57BL/6J mice were randomly divided into control group, LPS group, oral OCA group and LPS plus oral OCA (LPS + OCA) group. The serum and livers were collected for further analysis. Serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), total bile acid (TBA) and total bilirubin (TBIL) were measured at indicated time after LPS administration. Liver sections were stained with hematoxylin & eosin (H&E). Orally OCA pretreatment stimulated the expression of FXR and BSEP in livers and protected mice from LPS-induced hepatocyte apoptosis and inflammatory infiltration. Consistently, LPS-induced higher serum levels of ALT, AST, TBA and TBIL were significantly reversed by OCA administration. Meanwhile, the mRNA levels of interleukin 1β (IL-1β), tumor necrosis factor α (TNF-α) and IL-6 were decreased in livers of mice in LPS + OCA group compared with LPS group. Further investigation indicated that the higher expression of ATF4 and LC3II/I were associated with the protective effect of OCA on LPS-induced liver injury.

CONCLUSION

Orally OCA pretreatment protects mice from LPS-induced liver injury possibly contributed by improved bile acid homeostasis, decreased inflammatory factors and ATF4-mediated autophagy activity in hepatocytes.

Fast simultaneous assessment of renal and liver function using polymethine dyes in animal models of chronic and acute organ injury

Simultaneous assessment of excretory liver and kidney function is still an unmet need in experimental stress models as well as in critical care. The aim of the study was to characterize two polymethine-dyes potentially suitable for this purpose in vivo. Plasma disappearance rate and elimination measurements of simultaneously injected fluorescent dyes DY-780 (hepato-biliary elimination) and DY-654(renal elimination) were conducted using catheter techniques and intravital microscopy in animals subjected to different organ injuries, i.e. polymicrobial sepsis by peritoneal contamination and infection, ischemia-reperfusion-injury and glycerol-induced acute kidney-injury. DY-780 and DY-654 showed organ specific and determined elimination routes in both healthy and diseased animals. They can be measured simultaneously using near-infrared imaging and spectrophotometry. Plasma-disappearance rates of DY-780 and DY-654 are superior to conventional biomarkers in indicating hepatic or kidney dysfunction in different animal models. Greatest impact on liver function was found in animals with polymicrobial sepsis whereas glomerular damage due to glycerol-induced kidney-injury had strongest impact on DY-654 elimination. We therefore conclude that hepatic elimination and renal filtration can be assessed in rodents measuring plasma-disappearance rates of both dyes. Further, assessment of organ dysfunction by polymethine dyes correlates with, but outperforms conventional biomarkers regarding sensitivity and the option of spatial resolution if biophotonic strategies are applied. Polymethine-dye clearance thereby allows sensitive point-of-care assessment of both organ functions simultaneously.

Acid Sphingomyelinase Inhibition Prevents Development of Sepsis Sequelae in the Murine Liver

The molecular mechanisms of maladaptive response in liver tissue with respect to the acute and post-acute phase of sepsis are not yet fully understood. Long-term sepsis survivors might develop hepatocellular/hepatobiliary injury and fibrosis. Here, we demonstrate that acid sphingomyelinase, an important regulator of hepatocyte apoptosis and hepatic stellate cell (HSC) activation, is linked to the promotion of liver dysfunction in the acute phase of sepsis as well as to fibrogenesis in the long-term. In both phases, we observed a beneficial effect of partial genetic sphingomyelinase deficiency in heterozygous animals (smpd1^+/−) on oxidative stress levels, hepatobiliary function, macrophage infiltration and on HSC activation. Strikingly, similar to heterozygote expression of SMPD1, either preventative (p-smpd1^+/+) or therapeutic (t-smpd1^+/+) pharmacological treatment strategies with desipramine – a functional inhibitor of acid sphingomyelinase (FIASMA) – significantly improved liver function and survival. The inhibition of sphingomyelinase exhibited a protective effect on liver function in the acute-phase, and the reduction of HSC activation diminished development of sepsis-associated liver fibrosis in the post-acute phase of sepsis. In summary, targeting sphingomyelinase with FDA-approved drugs is a novel promising strategy to overcome sepsis-induced liver dysfunction.

Metabolomic findings in sepsis as a damage of host-microbial metabolism integration

Metabolomics globally evaluates the totality of the endogenous metabolites in patient's body, at the same time reflecting gene function, enzyme activity and degree of organ dysfunction in sepsis. The authors performed the analysis of the main chemical classes of low molecular weight compounds (amino acids, polyols, fatty acids, hydroxy acids, amines, nucleotides and their derivatives) that quantitatively distinguish patients with sepsis from healthy ones. The following keywords were used to find papers published in the Scopus and Web of Science databases from 2008 to 2015: (marker OR biomarker) AND (sepsis OR critical ill OR pneumonia OR hypoxia). Key words for the search were the following: metabolomics, metabolic profiling, sepsis, metabolism, biomarkers, critically ill patients, multiple organ failure. Several metabolomic findings in sepsis are still waiting for an explanation. When assessing metabolomic analysis results in patients with sepsis we should take into account the intervention of microbial metabolism. Among the low molecular weight compounds detected in septic patient blood, a special attention should be paid to the molecules which could be attributed to "common metabolites" of man and bacteria. The genomic region overlap and the production of enzymes which are similar in function and final products could be a possible reason for this phenomenon. For example, microbial biodegradation products of aromatic compounds are increased many times in blood of patients with sepsis. On the one hand, it shows a high metabolic activity of the bacteria. On the other hand, these molecules are intermediates in the metabolism of aromatic amino acids such as tyrosine and phenylalanine in human body. It is important that there are many clinical studies, which confirmed the diagnostic and prognostic significance of series of aromatic metabolites, including those with intrinsic biological activity. We can't exclude the presence of signaling pathways, cell receptors, transmembrane transporters and others which are common for a human and bacteria and their direct participation in mechanisms of organ dysfunction and hypotension in sepsis. Thus, today, we should not limit ourselves studying eukaryotic cells while searching for new molecular mechanisms of sepsis-associated organ failure and septic shock. We should take into account and simulate in the experiments the changes of a human internal environment, which occur during the radical microbiome "restructuring" in critically ill patients. This approach opens up new prospects for an objective monitoring of diseases, carrying out an assessment of the integral metabolic profile in a given time on common metabolites (particularly aromatic), and in future will provide new targets for therapeutic effects.

Cholestatic Alterations in the Critically Ill: Some New Light on an Old Problem

Liver dysfunction and jaundice are traditionally viewed as late features of sepsis and other critical illnesses and are associated with a complicated ICU stay. However, study results suggest that cholestatic alterations occur early in the course of critical illnesses, perceived only as minor abnormalities in routinely used biochemical liver tests. Inflammation-induced alterations in the transport of bile acids (BAs) appear to drive BAs and bilirubin toward the systemic circulation. Ongoing BA synthesis with an, at least partial, loss of feedback inhibition further contributes to elevated circulating BAs and bilirubin. To what extent these changes reflect a biochemical epiphenomenon, true illness-induced liver dysfunction, or a beneficial and adaptive response to illness should be investigated further. Because of the lack of specificity of standard laboratory tests, especially in the context of a complex systemic condition such as critical illness, identifying true cholestatic liver dysfunction remains a great challenge. However, high levels of cholestatic markers that are sustained in patients with prolonged critical illness almost always indicate a complicated illness course and should be monitored closely. Preventing cholestatic liver dysfunction comprises minimizing inflammation and hypoxia in the liver and preventing hyperglycemia, avoiding early use of parenteral nutrition, and reducing the administration of avoidable drugs. Future research on the effects of BAs and on modulating underlying drivers of cholestasis induced by critical illness is warranted as this could open perspectives for a targeted diagnostic approach and ultimately for novel therapies to improve outcome.

Impact of higher-order heme degradation products on hepatic function and hemodynamics

BACKGROUND & AIMS

Biliverdin and bilirubin were previously considered end products of heme catabolism; now, however, there is evidence for further degradation to diverse bioactive products. Z-BOX A and Z-BOX B arise upon oxidation with unknown implications for hepatocellular function and integrity. We studied the impact of Z-BOX A and B on hepatic functions and explored their alterations in health and cholestatic conditions.

METHODS

Functional implications and mechanisms were investigated in rats, hepatocytic HepG2 and HepaRG cells, human immortalized hepatocytes, and isolated perfused livers. Z-BOX A and B were determined by liquid chromatography-tandem mass spectrometry (LC-MS/MS) in acute and acute-on-chronic liver failure and hereditary unconjugated hyperbilirubinemia.

RESULTS

Z-BOX A and B are found in similar amounts in humans and rodents under physiological conditions. Serum concentrations increased ∼20-fold during cholestatic liver failure in humans (p<0.001) and in hereditary deficiency of bilirubin glucuronidation in rats (p<0.001). Pharmacokinetic studies revealed shorter serum half-life of Z-BOX A compared to its regio-isomer Z-BOX B (p=0.035). While both compounds were taken up by hepatocytes, Z-BOX A was enriched ∼100-fold and excreted in bile. Despite their reported vasoconstrictive properties in the brain vasculature, BOXes did not affect portal hemodynamics. Both Z-BOX A and B showed dose-dependent cytotoxicity, affected the glutathione redox state, and differentially modulated activity of Rev-erbα and Rev-erbβ. Moreover, BOXes-triggered remodeling of the hepatocellular cytoskeleton.

CONCLUSIONS

Our data provide evidence that higher-order heme degradation products, namely Z-BOX A and B, impair hepatocellular integrity and might mediate intra- and extrahepatic cytotoxic effects previously attributed to hyperbilirubinemia.

LAY SUMMARY

Degradation of the blood pigment heme yields the bile pigment bilirubin and the oxidation products Z-BOX A and Z-BOX B. Serum concentrations of these bioactive molecules increase in jaundice and can impair liver function and integrity. Amounts of Z-BOX A and Z-BOX B that are observed during liver failure in humans have profound effects on hepatic function when added to cultured liver cells or infused into healthy rats.

Dynamic changes of plasma metabolites in pigs with GalN-induced acute liver failure using GC-MS and UPLC-MS

Metabolomics facilitates investigation of the mechanisms of disease and screening for biomarkers. Here, a gas chromatography-mass spectrometry (GC-MS) and ultra-performance liquid chromatography-mass spectrometry (UPLC-MS)-based metabolomics approach was employed to identify plasma biomarkers of acute liver failure (ALF) in pigs. Blood was collected from pigs at 12h intervals during ALF. Hepatic injury was quantified by determining liver function and histopathology. Based on a multivariate data matrix and pattern recognition, two upregulated metabolites, namely, amino acids and conjugated bile acids, and two downregulated metabolites, lysophosphatidylcholines (LPCs) and phosphatidylcholines (PCs), were identified. All of these metabolites showed a strong relationship with the extent of liver injury. Amino acids were biomarkers of the severity of liver impairment, conjugated bile acids were predictive of early stage liver damage, and LPCs and PCs were related to the prognosis of liver injury. In conclusion, our results demonstrated the occurrence of marked metabolic disturbances during ALF and that integrated metabolomics analysis facilitates identification of biomarkers of disease.

Sepsis-3 on the Block: What Does It Mean for Preclinical Sepsis Modeling?

To effectively improve outcomes of septic patients, we first need to elucidate the multifaceted pathogenesis of sepsis syndromes and related inflammatory conditions. In fulfillment of such needs, in February 2016, new definitions for sepsis and septic shock were published under the acronym Sepsis-3. Although aimed at the clinical area, Sepsis-3 will have an inevitable influence upon the field of translational research as well. Sepsis-3 brings a considerable shift regarding the experimental focal point: from inflammatory states (SIRS/CARS) to organ failure (single and multiple) as the decisive factor. This shift exposes several shortcomings of the current in vivo sepsis modeling including lack of uniform scoring system for sepsis severity and organ dysfunction/failure; high variability of organ dysfunction phenotypes among animal species/strains; difficulty in reproducing severe, intensive care unit grade of organ dysfunction due to high resistance of experimental animals and others. It is intuitive that clinical Sepsis-3 should also serve as an incentive for developing a global standardized approach in sepsis modeling to maximize its translational potential. This could be achieved, for example, by generating consensus guidelines that would support scientists in their study design and optimal sepsis modeling decision-making. An implementation of such hypothetical "Minimum Quality Threshold in Preclinical Sepsis Studies" guidelines across different species has a strong potential for making sepsis studies more reliable and transpolatable. We strongly believe that an internationally coordinated standardization effort in sepsis modeling will certainly serve the above purposes well.

Circulating bile acids predict outcome in critically ill patients

Background

Jaundice and cholestatic hepatic dysfunction are frequent findings in critically ill patients associated with increased mortality. Cholestasis in critically ill patients is closely associated with stimulation of pro-inflammatory cytokines resulting in impaired bile secretion and subsequent accumulation of bile acids.

Aim of this study was to evaluate the clinical role of circulating bile acids in critically ill patients.

Methods

Total and individual serum bile acids were assessed via high-performance liquid chromatography in 320 critically ill patients and 19 controls.

Results

Total serum bile acids were threefold higher in septic than cardiogenic shock patients and sixfold higher than in post-surgical patients or controls (p < 0.001). Elevated bile acid levels correlated with severity of illness, renal dysfunction and inflammation (p < 0.05). Total bile acids predicted 28-day mortality independently of sex, age, serum bilirubin and severity of illness (HR 1.041, 95% CI 1.013–1.071, p < 0.005). Best prediction of mortality of total bile acids was seen in patients suffering from septic shock.

Conclusions

Individual and total BAs are elevated by various degrees in different shock conditions. BAs represent an early predictor of short-term survival in a mixed cohort of ICU patients and may serve as marker for early risk stratification in critically ill patients. Future studies should elucidate whether modulation of BA metabolism and signalling influences the clinical course and outcome in critically ill patients.

Electronic supplementary material

The online version of this article (doi:10.1186/s13613-017-0272-7) contains supplementary material, which is available to authorized users.

Adjustment of Dysregulated Ceramide Metabolism in a Murine Model of Sepsis-Induced Cardiac Dysfunction

Cardiac dysfunction, in particular of the left ventricle, is a common and early event in sepsis, and is strongly associated with an increase in patients’ mortality. Acid sphingomyelinase (SMPD1)—the principal regulator for rapid and transient generation of the lipid mediator ceramide—is involved in both the regulation of host response in sepsis as well as in the pathogenesis of chronic heart failure. This study determined the degree and the potential role to which SMPD1 and its modulation affect sepsis-induced cardiomyopathy using both genetically deficient and pharmacologically-treated animals in a polymicrobial sepsis model. As surrogate parameters of sepsis-induced cardiomyopathy, cardiac function, markers of oxidative stress as well as troponin I levels were found to be improved in desipramine-treated animals, desipramine being an inhibitor of ceramide formation. Additionally, ceramide formation in cardiac tissue was dysregulated in SMPD1^+/+ as well as SMPD1^−/− animals, whereas desipramine pretreatment resulted in stable, but increased ceramide content during host response. This was a result of elevated de novo synthesis. Strikingly, desipramine treatment led to significantly improved levels of surrogate markers. Furthermore, similar results in desipramine-pretreated SMPD1^−/− littermates suggest an SMPD1-independent pathway. Finally, a pattern of differentially expressed transcripts important for regulation of apoptosis as well as antioxidative and cytokine response supports the concept that desipramine modulates ceramide formation, resulting in beneficial myocardial effects. We describe a novel, protective role of desipramine during sepsis-induced cardiac dysfunction that controls ceramide content. In addition, it may be possible to modulate cardiac function during host response by pre-conditioning with the Food and Drug Administration (FDA)-approved drug desipramine.

Farnesoid X Receptor Regulation of the NLRP3 Inflammasome Underlies Cholestasis-Associated Sepsis

Cholestasis is a common complication of sepsis, and the increased plasma levels of bile acids are predictive of sepsis-associated mortality. However, the exact mechanism by which cholestasis aggravates sepsis development remains elusive. Here, we show that bile acids are danger-associated molecular patterns (DAMPs) that can activate both signal 1 and 2 of the NLRP3 inflammasome in inflammatory macrophages. Mechanistically, bile acids induce a prolonged calcium influx and activate the NLRP3 inflammasome synergistically with ATP. Experimental cholestasis sensitizes, while cholestyramine, a bile acid sequestrant, protects mice from LPS-induced sepsis. FXR negatively regulates the NLRP3 inflammasome via physical interaction with NLRP3 and caspase 1. Fxr-null mice are more sensitive, while FXR-overexpressing mice are more resistant, to endoxemia shock. These findings suggest that bile acids and FXR play pivotal roles in sepsis via controlling the NLRP3 inflammasome, and that targeting FXR may represent a therapeutic strategy for cholestasis-associated sepsis.

Serum bile acids as marker for acute decompensation and acute-on-chronic liver failure in patients with non-cholestatic cirrhosis

BACKGROUND & AIMS

Retention of bile acids (BAs) plays a central role in hepatic damage and disturbed BA signalling in liver disease. However, there is lack of data regarding the association of BAs with clinical complications, acute decompensation (AD) and acute-on-chronic liver failure (ACLF). Thus, we aimed to evaluate the impact of circulating serum BAs for complications in patients with cirrhosis.

METHODS

One hundred and forty-three patients with cirrhosis were included in this prospective cohort-type observational study. Total serum BAs and individual BA composition were assessed in all patients on admission via high-performance liquid chromatography. Clinical complications with respect to AD, ACLF and 1-year transplant-free survival were recorded.

RESULTS

Total BAs and individual serum BAs were significantly higher in patients with bacterial infection, AD and ACLF (P<.001) and correlated significantly with model of end-stage liver disease (MELD) and hepatic venous pressure gradient (P<.001). Total BAs predicted new onset of AD or ACLF during follow-up (OR 1.025, 95% CI: 1.012-1.038, P<.001). Best cut-off predicting new onset of AD/ACLF and survival during course of time was total BAs ≥36.9 μmol/L.

CONCLUSIONS

Serum total and individual BAs are associated with AD and ACLF in patients with cirrhosis. Assessment of total BAs could serve as additional marker for risk stratification in cirrhotic patients with respect to new onset of AD and ACLF.

Liver - guardian, modifier and target of sepsis

Sepsis and septic shock are characterized by life-threatening organ dysfunction caused by a dysregulated host response to infection. The liver has a central role during sepsis, and is essential to the regulation of immune defence during systemic infections by mechanisms such as bacterial clearance, acute-phase protein or cytokine production and metabolic adaptation to inflammation. However, the liver is also a target for sepsis-related injury, including hypoxic hepatitis due to ischaemia and shock, cholestasis due to altered bile metabolism, hepatocellular injury due to drug toxicity or overwhelming inflammation, as well as distinct pathologies such as secondary sclerosing cholangitis in critically ill patients. Hence, hepatic dysfunction substantially impairs the prognosis of sepsis and serves as a powerful independent predictor of mortality in the intensive care unit. Sepsis is particularly problematic in patients with liver cirrhosis (who experience increased bacterial translocation from the gut and impaired microbial defence) as it can trigger acute-on-chronic liver failure - a syndrome with high short-term mortality. Here, we review the importance of the liver as a guardian, modifier and target of sepsis, the factors that contribute to sepsis in patients with liver cirrhosis and new therapeutic strategies.

Monocyte-induced recovery of inflammation-associated hepatocellular dysfunction in a biochip-based human liver model

Liver dysfunction is an early event in sepsis-related multi-organ failure. We here report the establishment and characterization of a microfluidically supported in vitro organoid model of the human liver sinusoid. The liver organoid is composed of vascular and hepatocyte cell layers integrating non-parenchymal cells closely reflecting tissue architecture and enables physiological cross-communication in a bio-inspired fashion. Inflammation-associated liver dysfunction was mimicked by stimulation with various agonists of toll-like receptors. TLR-stimulation induced the release of pro- and anti-inflammatory cytokines and diminished expression of endothelial VE-cadherin, hepatic MRP-2 transporter and apolipoprotein B (ApoB), resulting in an inflammation-related endothelial barrier disruption and hepatocellular dysfunction in the liver organoid. However, interaction of the liver organoid with human monocytes attenuated inflammation-related cell responses and restored MRP-2 transporter activity, ApoB expression and albumin/urea production. The cellular events observed in the liver organoid closely resembled pathophysiological responses in the well-established sepsis model of peritoneal contamination and infection (PCI) in mice and clinical observations in human sepsis. We therefore conclude that this human liver organoid model is a valuable tool to investigate sepsis-related liver dysfunction and subsequent immune cell-related tissue repair/remodeling processes.

Genipin alleviates sepsis-induced liver injury by restoring autophagy

BACKGROUND AND PURPOSE

Autophagy is an essential cytoprotective system that is rapidly activated in response to various stimuli including inflammation and microbial infection. Genipin, an aglycon of geniposide found in gardenia fruit, is well known to have anti-inflammatory, antibacterial and antioxidative properties. This study examined the protective mechanisms of genipin against sepsis, with particular focus on the autophagic signalling pathway.

EXPERIMENTAL APPROACH

Mice were subjected to sepsis by caecal ligation and puncture (CLP). Genipin (1, 2.5 and 5 mg·kg(-1) ) or vehicle (saline) was injected i.v. immediately (0 h) after CLP, and chloroquine (60 mg·kg(-1) ), an autophagy inhibitor, was injected i.p. 1 h before CLP. Blood and liver tissues were isolated 6 h after CLP.

KEY RESULTS

Genipin improved survival rate and decreased serum levels of aminotransferases and pro-inflammatory cytokines after CLP; effects abolished by chloroquine. The liver expression of autophagy-related protein (Atg)12-Atg5 conjugate increased after CLP, and this increase was enhanced by genipin. CLP decreased Atg3 protein liver expression, and genipin attenuated this decrease. CLP impaired autophagic flux, as indicated by increased liver expression of microtubule-associated protein-1 light chain 3-II and sequestosome-1/p62 protein; this impaired autophagic flux was restored by genipin, and chloroquine abolished this effect. Genipin also attenuated the decreased expression of lysosome-associated membrane protein-2 and Rab7 protein and increased expression of calpain 1 protein induced by CLP in the liver.

CONCLUSIONS AND IMPLICATIONS

Our findings suggest that genipin protects against septic injury by restoring impaired autophagic flux. Therefore, genipin might be a potential therapeutic agent for the treatment of sepsis.

Molecular adsorbent recirculating system and single-pass albumin dialysis in liver failure--a prospective, randomised crossover study

Background

The aim of extracorporeal albumin dialysis (ECAD) is to reduce endogenous toxins accumulating in liver failure. To date, ECAD is conducted mainly with the Molecular Adsorbents Recirculating System (MARS). However, single-pass albumin dialysis (SPAD) has been proposed as an alternative. The aim of this study was to compare the two devices with a prospective, single-centre, non-inferiority crossover study design with particular focus on reduction of bilirubin levels (primary endpoint) and influence on paraclinical and clinical parameters (secondary endpoints) associated with liver failure.

Methods

Patients presenting with liver failure were screened for eligibility and after inclusion were randomly assigned to be started on either conventional MARS or SPAD (with 4 % albumin and a dialysis flow rate of 700 ml/h). Statistical analyses were based on a linear mixed-effects model.

Results

Sixty-nine crossover cycles of ECAD in 32 patients were completed. Both systems significantly reduced plasma bilirubin levels to a similar extent (MARS: median −68 μmol/L, interquartile range [IQR] −107.5 to −33.5, p = 0.001; SPAD: −59 μmol/L, −84.5 to +36.5, p = 0.001). However, bile acids (MARS: −39 μmol/L, −105.6 to −8.3, p < 0.001; SPAD: −9 μmol/L, −36.9 to +11.4, p = 0.131), creatinine (MARS: −24 μmol/L, −46.5 to −8.0, p < 0.001; SPAD: −2 μmol/L, −9.0 to +7.0/L, p = 0.314) and urea (MARS: −0.9 mmol/L, −1.93 to −0.10, p = 0.024; SPAD: −0.1 mmol/L, −1.0 to +0.68, p = 0.523) were reduced and albumin-binding capacity was increased (MARS: +10 %, −0.8 to +20.9 %, p < 0.001; SPAD: +7 %, −7.5 to +15.5 %, p = 0.137) only by MARS. Cytokine levels of interleukin (IL)-6 and IL-8 and hepatic encephalopathy were altered by neither MARS nor SPAD.

Conclusions

Both procedures were safe for temporary extracorporeal liver support. While in clinical practice routinely assessed plasma bilirubin levels were reduced by both systems, only MARS affected other paraclinical parameters (i.e., serum bile acids, albumin-binding capacity, and creatinine and urea levels). Caution should be taken with regard to metabolic derangements and electrolyte disturbances, particularly in SPAD using regional citrate anti-coagulation.

Trial registration

German Clinical Trials Register (www.drks.de) DRKS00000371. Registered 8 April 2010.

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-015-1159-3) contains supplementary material, which is available to authorized users.