Liver Perfusion And Hepatocellular Inflammatory Response In Sepsis

Prognostic value of indocyanine green elimination assessed with LiMON in septic patients

BACKGROUND

Sepsis is the most frequent infection with high mortality rates in intensive care units (ICUs), and the prediction of outcome is important in the decision-making process.

OBJECTIVE

To assess the value of the Acute Physiology and Chronic Health Evaluation II (APACHE II) and indocyanin green (ICG) plasma disappearance rate (ICG-PDR) in septic patients.

DESIGN

Retrospective analysis.

MEASUREMENTS AND RESULTS

We analyzed 40 septic patients (17 female and 23 male; age range, 20-89 years) who were treated in our ICU. The ICG-PDR measurement and APACHE II score measurement were made within 24 hours after admission to the ICU. Indocyanine green elimination tests were conducted concurrently using the noninvasive liver function monitoring system (LiMON, Pulsion Medical Systems, Munich, Germany). A dose of 0.3 mg/kg ICG was given through a cubital fossa vein as a bolus.

RESULTS

Statistical analysis showed that ICG-PDR was significantly lower in nonsurvivors (n = 18) than in survivors (n = 22) (mean, 12.1% +/- 7.6%/min; median, 9%/min, vs mean, 21.2% +/- 10.1%/min; median, 20%/min, respectively [P = .004]). The area under the curve as a measure of accuracy was 0.765 for ICG-PDR and 0.692 for APACHE II. Mortality was 80% in patients with ICG-PDR below 8% per minute, and survival was approximately 89% in patients with ICG-PDR above 24% per minute.

CONCLUSION

The results suggest that ICG-PDR, assessed with a user-friendly noninvasive bedside LiMON device, is a good predictor of survival in septic patients. Sensitivity and specificity of the noninvasive measurement of ICG-PDR on ICU admission was comparable to that obtained by APACHE II scores.

Hepatic gene expression during endotoxemia

PURPOSE

During the course of sepsis, endotoxins and cytokines activate Kupffer cells, induce the liberation and synthesis of adhesion molecules, and damage hepatocytes, which leads to septic liver failure. The interaction of the different hepatic cell types during these processes is not completely understood and may be clarified by microarray technology.

MATERIALS AND METHODS

Seven Sprague Dawley rats received either an intraperitoneal injection of lipopolysaccharides (LPS) of 3 mg/kg body weight (n = 4) or sodium chloride (SC) 0.9% (n = 3). Animals were sacrificed 24 h after LPS or SC injection. RNA from liver tissue was isolated and hybridized on GeneChips (RAE 230A; Affymetrix, Santa Clara, CA). Expression of interleukin-1beta, tumor necrosis factor-alpha, and signal transducer and activator of transcription 3 was controlled by reverse transcription-polymerase chain reaction analysis. Immunohistochemical staining for intercellular adhesion molecule-1 of liver tissue was performed.

RESULTS

We detected 508 differentially expressed genes between LPS and SC. Two hundred forty-eight genes were up-regulated and 260 genes were down-regulated in the LPS versus the SC group. Mainly genes involved in immune response and receptor activity were up-regulated in the LPS group. Genes enrolled in catalytic, transferase activity, and metabolisms were down-regulated in the LPS group. The microarray findings could be verified by reverse transcription-polymerase chain reaction analysis and immunohistochemical staining.

CONCLUSIONS

The contemporaneous differential regulation of genes involved in metabolism, hepatocellular synthesis, and immune response reflect the liver's central role as immune organ during the course of sepsis. A switch from metabolic to immunological activity is obvious, which aggravates the hepatic damage. The functional interaction of the single genes identified during this process must be further clarified.

Isoflurane improves survival and protects against renal and hepatic injury in murine septic peritonitis

We have demonstrated that volatile anesthetics reduce inflammation after renal ischemia/reperfusion injury in vivo. As hyperactive uncontrolled inflammation can lead to mortality and morbidity during early sepsis, we questioned whether the volatile anesthetic isoflurane could reduce mortality and protect against sepsis induced renal and hepatic dysfunction. Mice were anesthetized with isoflurane or with pentobarbital and subjected to cecal ligation and puncture (CLP) to induce septic peritonitis. Mice were anesthetized for an additional 3 h after CLP with either isoflurane or pentobarbital. Renal and hepatic function was assessed 24 h later and survival after CLP was assessed for 7 days. To determine if isoflurane protects by reducing inflammation, we quantified renal tubular expression of pro-inflammatory (intercellular adhesion molecule 1, tumor necrosis factor alpha [TNF-alpha], and interleukin [IL] 1beta) messenger RNA with reverse transcriptase-polymerase chain reaction. We also measured the plasma levels of the pro-inflammatory cytokines TNF-alpha, keratinocyte-derived chemokine (KC), and IL-6 and an anti-inflammatory cytokine IL-10. Renal cortical apoptosis was also assessed 24 h after CLP. Twenty-four hours after the septic insult, isoflurane-treated mice had significantly improved renal and hepatic function compared with mice anesthetized with pentobarbital. Renal cortices of isoflurane-treated mice had significantly reduced expression of intercellular adhesion molecule 1, TNF-alpha, and IL-1beta messenger RNA and showed less apoptosis. Isoflurane-treated mice had lower plasma levels of TNF-alpha, KC, and IL-6. Isoflurane-anesthetized mice also had significantly prolonged and increased survival compared with pentobarbital-anesthetized mice. Therefore, isoflurane anesthesia conferred significant protection against renal and hepatic dysfunction and death after septic peritonitis and attenuated renal inflammation and apoptosis compared with pentobarbital anesthesia.

Intravenous glycine after cecal ligation and puncture has no effect on impaired hepatic microperfusion, leukocyte adhesion, and mortality in septic rats

Recent studies indicated that prefeeding of a glycine supplemented diet reduces the hepatic inflammatory response and liver damage in sepsis. We investigated the effect of a glycine-enriched infusion on hepatic microcirculatory disturbances and mortality in a rat model of sepsis after the onset of the disease. Male Wistar rats (240 +/- 13 g) underwent cecal ligation and puncture (CLP) or laparotomy (LAP). A glycine (CLP + Gly, n = 24), valine (CLP + Val, n = 24), or sodium chlorid (CLP + Sc, n = 24) infusion was started 2 h after CLP. The LAP group received sodium chloride intravenously (LAP + Sc, n = 18 ). Five hours, 10 h, and 20 h after CLP or LAP intravital microscopy (IVM) was performed to investigate leukocyte-endothelial interaction (LEI) and mean erythrocyte velocity in liver sinusoids (sMEV) and postsinosoidal venules (vMEV). The portal blood flow (PBF), hepatic enzyme liberation, and glycine values in blood were measured. Immunohistochemical staining for ICAM-1 in liver tissue was performed and survival was observed. Glycine values were significantly elevated in the CLP + Gly vs. the CLP + Val and the CLP + Sc group at every timepoint of investigation. Glycine infusion had no beneficial effects on sMEV, vMEV, LEI, hepatic enzyme liberation, and survival. Heart rate and mean arterial pressure remained stable but PBF decreased significantly in all groups 20 h after CLP. Although glycine reduces the hepatic inflammatory response and liver damage in pretreatment of septic rats, there was no effect of intravenous glycine after the onset of sepsis in our experiments. Our animal model does not support the use of glycine in patients.

C1-inhibitor reduces hepatic leukocyte-endothelial interaction and the expression of VCAM-1 in LPS-induced sepsis in the rat

INTRODUCTION

Increased leukocyte-endothelial interaction (LEI) leading to hepatic microperfusion disorders is proposed as major contributor for hepatic failure during sepsis. Recently it has been demonstrated that complement inhibition by C1-inhibitor (C1-INH) is an effective treatment against microcirculatory disturbances in various diseases. The purpose of this study was to investigate the influence of C1-INH on microcirculation and LEI in the liver in a rat model of sepsis.

MATERIALS AND METHODS

Rats received lipopolysaccharides (LPS) from Escherichia coli intravenously. Controls received Ringer solution only. Ninety minutes after LPS infusion some animals were treated with C1-INH intravenously (LPS + C1-INH). Others (LPS + SC) and controls (Ringer + SC) received sodium chloride (SC). Hepatic LEI and mean erythrocyte velocity (MEV) were quantified by intravital microscopy (IVM) 90 min after LPS or Ringer infusion (0) and 30, 60, 90 and 120 min following treatment. VCAM-1 m-RNA in hepatic tissue, C3a, TNF-alpha and hepatic enzyme liberation in blood was analysed.

RESULTS

Leukocyte sticking to the endothelial wall in postsinusoidal venules was significantly reduced in the LPS + C1-INH vs. the LPS + SC group 30, 60, 90 and 120 min after treatment. VCAM-1 m-RNA expression in the hepatic tissue was markedly and C3a levels in plasma were significantly reduced in the LPS + C1-INH vs. the LPS + SC group. No differences in TNF-alpha levels were detected between these two groups. MEV was improved in the LPS + C1-INH vs. the LPS + SC group.

CONCLUSIONS

Our results indicate that even upon delayed treatment hepatic adhesion molecule expression and LEI can be reduced by C1-INH. The multifunctional regulator may reduce hepatic microcirculatory disturbances during sepsis under clinical conditions.

Nitric oxide in liver diseases: friend, foe, or just passerby?

Research on the free radical gas, nitric oxide (NO), during the past twenty years is one of the most rapid growing areas in biology. NO seems to play a part in almost every organ and tissue. However, there is considerable controversy and confusion in understanding its role. The liver is one organ that is clearly influenced by NO. Acute versus chronic exposure to NO has been associated with distinct patterns of liver disease. In this paper we review and discuss the involvement of NO in various liver diseases collated from observations by various researchers. Overall, the important factors in determining the beneficial versus harmful effects of NO are the amount, duration, and site of NO production. A low dose of NO serves to maximize blood perfusion, prevent platelet aggregation and thrombosis, and neutralize toxic oxygen radicals in the liver during acute sepsis and reperfusion events. NO also demonstrates antimicrobial and antiapoptosis properties during acute hepatitis infection and other inflammatory processes. However, in the setting of chronic liver inflammation, when a large sustained amount of NO is present, NO might become genotoxic and lead to the development of liver cancer. Additionally, during prolonged ischemia, high levels of NO may have cytotoxic effects leading to severe liver injury. In view of the various possible roles that NO plays, the pharmacologic modulation of NO synthesis is promising in the future treatment of liver diseases, especially with the emergence of selective NO synthase inhibitors and cell-specific NO donors.

Pivotal role of signal transducer and activator of transcription (Stat)4 and Stat6 in the innate immune response during sepsis

Signal transducer and activator of transcription (Stat)4 and Stat6 are transcription factors that provide type 1 and type 2 response, respectively. Here, we explored the role of Stat4 and Stat6 in innate immunity during septic peritonitis. Stat4-/- and Stat6-/- mice were resistant to the lethality compared with wild-type (WT) mice. At the mechanistic level, bacterial levels in Stat6-/- mice were much lower than in WT mice, which was associated with increased peritoneal levels of interleukin (IL)-12, tumor necrosis factor (TNF)-alpha, macrophage-derived chemokine (MDC), and C10, known to enhance bacterial clearance. In Stat4-/- mice, hepatic inflammation and injury during sepsis were significantly ameliorated without affecting local responses. This event was associated with increased hepatic levels of IL-10 and IL-13, while decreasing those of macrophage inflammatory protein (MIP)-2 and KC. Sepsis-induced renal injury was also abrogated in Stat4-/- mice, which was accompanied by decreased renal levels of MIP-2 and KC without altering IL-10 and IL-13 levels. Thus, Stat6-/- and Stat4-/- mice appeared to be resistant to septic peritonitis by enhancing local bacterial clearance and modulating systemic organ damage, respectively, via balancing cytokine responses. These results clearly highlight an important role of local type 1 and systemic type 2 cytokine response in protective immunity during sepsis, which can be regulated by Stat proteins.