IL-6 modulates sepsis-induced decreases in transcription of hepatic organic anion and bile acid transporters

Immunosuppressive effects of circulating bile acids in human endotoxemia and septic shock: patients with liver failure are at risk

BACKGROUND

Sepsis-induced immunosuppression is a frequent cause of opportunistic infections and death in critically ill patients. A better understanding of the underlying mechanisms is needed to develop targeted therapies. Circulating bile acids with immunosuppressive effects were recently identified in critically ill patients. These bile acids activate the monocyte G-protein coupled receptor TGR5, thereby inducing profound innate immune dysfunction. Whether these mechanisms contribute to immunosuppression and disease severity in sepsis is unknown. The aim of this study was to determine if immunosuppressive bile acids are present in endotoxemia and septic shock and, if so, which patients are particularly at risk.

METHODS

To induce experimental endotoxemia in humans, ten healthy volunteers received 2 ng/kg E. coli lipopolysaccharide (LPS). Circulating bile acids were profiled before and after LPS administration. Furthermore, 48 patients with early (shock onset within < 24 h) and severe septic shock (norepinephrine dose > 0.4 μg/kg/min) and 48 healthy age- and sex-matched controls were analyzed for circulating bile acids. To screen for immunosuppressive effects of circulating bile acids, the capability to induce TGR5 activation was computed for each individual bile acid profile by a recently published formula.

RESULTS

Although experimental endotoxemia as well as septic shock led to significant increases in total bile acids compared to controls, this increase was mild in most cases. By contrast, there was a marked and significant increase in circulating bile acids in septic shock patients with severe liver failure compared to healthy controls (61.8 µmol/L vs. 2.8 µmol/L, p = 0.0016). Circulating bile acids in these patients were capable to induce immunosuppression, as indicated by a significant increase in TGR5 activation by circulating bile acids (20.4% in severe liver failure vs. 2.8% in healthy controls, p = 0.0139).

CONCLUSIONS

Circulating bile acids capable of inducing immunosuppression are present in septic shock patients with severe liver failure. Future studies should examine whether modulation of bile acid metabolism can improve the clinical course and outcome of sepsis in these patients.

Co-Targeting IL-6 and EGFR signaling for the treatment of schwannomatosis and associated pain

Patients with Schwannomatosis (SWN) overwhelmingly present with intractable, debilitating chronic pain. There are no effective therapies to treat SWN. The drivers of pain response and tumor progression in SWN are not clear. The pain is not proportionally linked to tumor size and is not always relieved by tumor resection, suggesting that mechanisms other than mechanical nerve compression exist to cause pain. SWN research is limited by the lack of clinically-relevant models. Here, we established novel patient-derived xenograft (PDX) models, dorsal root ganglia (DRG) imaging model, and combined with single-cell resolution intravital imaging and RNASeq, we discovered: i) schwannomas on the peripheral nerve cause macrophage influx into the DRG, via secreting HMGB1 to directly stimulate DRG neurons to express CCL2, the key macrophage chemokine, ii) once recruited, macrophages cause pain response via overproduction of IL-6, iii) IL-6 blockade in a therapeutic setting significantly reduces pain but has modest efficacy on tumor growth, iv) EGF signaling is a potential driver of schwannoma growth and escape mechanism from anti-IL6 treatment, and v) combined IL-6 and EGFR blockade simultaneously controlled pain and tumor growth in SWN models. Our findings prompted the initiation of phase II clinical trial ( NCT05684692 ) for pain relief in patients with SWN.

CP-25 enhances OAT1-mediated absorption of methotrexate in synoviocytes of collagen-induced arthritis rats

Organic anion transporter 1 (OAT1) plays a major role in mediating the absorption, distribution and excretion of drugs and other xenobiotics in the human body. In this study we explored the OAT1 status in rheumatoid arthritis (RA) patients and arthritic animals and its role in regulating the anti-arthritic activity of methotrexate (MTX). We showed that OAT1 expression was significantly downregulated in synovial tissues from RA patients compared with that in the control patients. In collagen-induced arthritis (CIA) rats, synovial OAT1 expression was significantly decreased compared with the control rats. In synoviocytes isolated from CIA rats, PGE2 (0.003-1.75 μM) dose-dependently downregulated OAT1 expression, resulting in decreased absorption of MTX. Silencing OAT1 in synoviocytes caused a 43.7% reduction in the uptake of MTX. Furthermore, knockdown of OAT1 impaired MTX-induced inhibitory effects on the viability and migration of synoviocytes isolated from CIA rats. Moreover, injection of OAT1-shRNA into articular cavity of CIA rats significantly decreased synovial OAT1 expression and impaired the anti-arthritic action of MTX, while injection of lentivirus containing OAT1 sequences led to the opposite results. Interestingly, we found that paeoniflorin-6'-O-benzene sulfonate (CP-25) upregulated OAT1 expression both in vitro and in vivo and promoted MTX uptake by synoviocytes via regulating OAT1 expression and function. Taken together, OAT1 plays a major role in regulating MTX uptake by synoviocytes and the anti-arthritic activity of MTX. OAT1 is downregulated in RA and CIA rats, which can be improved by CP-25.

T cell activation and IFNγ modulate organ dysfunction in LPS-mediated inflammation

LPS challenge is used to model inflammation-induced organ dysfunction. The effects of T cell activation on LPS-mediated organ dysfunction and immune responses are unknown. We studied these interactions through in vivo administration of anti-CD3ε (CD3) T cell activating antibody and LPS. Mortality in response to high-dose LPS (LPSHi; 600 μg) was 60%; similar mortality was observed with a 10-fold reduction in LPS dose (LPSLo; 60 μg) when administered with CD3 (CD3LPSLo). LPSHi and CD3LPSLo cohorts suffered severe organ dysfunction. CD3LPSLo led to increased IFNγ and IL12p70 produced by T cells and dendritic cells (cDCs) respectively. CD3LPSLo caused cDC expression of CD40 and MHCII and prevented PD1 expression in response to CD3. These interactions led to the generation of CD4 and CD8 cytolytic T cells. CD3LPSLo responded to IFNγ or IL12p40 blockade, in contrast to LPSHi. The combination of TCR activation and LPS (CD3LPSLo) dysregulated T cell activation and increased LPS-associated organ dysfunction and mortality through T cell and cDC interactions.

Incidence, Clinical Characteristics and Outcomes of Early Hyperbilirubinemia in Critically Ill Patients: Insights From the MARS Study

OBJECTIVE

To investigate the incidence, clinical characteristics and outcomes of early hyperbilirubinemia in critically ill patients.

DESIGN AND SETTING

This is a post hoc analysis of a prospective multicenter cohort study.

PATIENTS

Patients with measured bilirubin levels within the first 2 days after ICU admission were eligible. Patients with liver cirrhosis were excluded.

ENDPOINTS

The primary endpoint was the incidence of early hyperbilirubinemia, defined as bilirubin ≥33 μmol/L within 2 days after ICU admission. Secondary endpoints included clinical characteristics of patients with versus patients without early hyperbilirubinemia, and outcomes up to day 30.

RESULTS

Of 4,836 patients, 559 (11.6%) patients had early hyperbilirubinemia. Compared to patients without early hyperbilirubinemia, patients with early hyperbilirubinemia presented with higher severity of illness scores, and higher incidences of sepsis and organ failure. After adjustment for confounding variables, early hyperbilirubinemia remained associated with mortality at day 30 (odds ratio, 1.31 [95%-confidence interval 1.06-1.60]; P = 0.018). Patients with early hyperbilirubinemia and thrombocytopenia (interaction P-value = 0.005) had a higher likelihood of death within 30 days (odds ratio, 2.61 [95%-confidence interval 2.08-3.27]; P < 0.001) than patients with early hyperbilirubinemia and a normal platelet count (odds ratio, 1.09 [95%-confidence interval 0.75-1.55]; P = 0.655).

CONCLUSIONS

Early hyperbilirubinemia occurs frequently in the critically ill, and these patients present with higher disease severity and more often with sepsis and organ failures. Early hyperbilirubinemia has an association with mortality, albeit this association was only found in patients with concomitant thrombocytopenia.

Use of Organ Dysfunction as a Primary Outcome Variable Following Cecal Ligation and Puncture: Recommendations for Future Studies

Outcomes variables for research on sepsis have centered on mortality and changes in the host immune response. However, a recent task force (Sepsis-3) revised the definition of sepsis to "life-threatening organ dysfunction caused by a dysregulated host response to infection." This new definition suggests that human studies should focus on organ dysfunction. The appropriate criteria for organ dysfunction in either human sepsis or animal models are, however, poorly delineated, limiting the potential for translation. Further, in many systems, the difference between "dysfunction" and "injury" may not be clear. In this review, we identify criteria for organ dysfunction and/or injury in human sepsis and in rodents subjected to cecal ligation and puncture (CLP), the most commonly used animal model of sepsis. We further examine instances where overlap between human sepsis and CLP is sufficient to identify translational endpoints. Additional verification may demonstrate that these endpoints are applicable to other animals and to other sepsis models, for example, pneumonia. We believe that the use of these proposed measures of organ dysfunction will facilitate mechanistic studies on the pathobiology of sepsis and enhance our ability to develop animal model platforms to evaluate therapeutic approaches to human sepsis.

The Surviving Sepsis Campaign: Basic/Translational Science Research Priorities

Objectives:

Expound upon priorities for basic/translational science identified in a recent paper by a group of experts assigned by the Society of Critical Care Medicine and the European Society of Intensive Care Medicine.

Data Sources:

Original paper, search of the literature.

Study Selection:

By several members of the original task force with specific expertise in basic/translational science.

Data Extraction:

None.

Data Synthesis:

None.

Conclusions:

In the first of a series of follow-up reports to the original paper, several members of the original task force with specific expertise provided a more in-depth analysis of the five identified priorities directly related to basic/translational science. This analysis expounds on what is known about the question and what was identified as priorities for ongoing research. It is hoped that this analysis will aid the development of future research initiatives.

The effects of drug transporters on the efficacy of methotrexate in the treatment of rheumatoid arthritis

The ATP-binding cassette (ABC) and solute carrier (SLC) transporter families consist of common drug transporters that mediate the efflux and uptake of drugs, respectively, and play an important role in the absorption, distribution, metabolism and excretion of drugs in vivo. Rheumatoid arthritis (RA) is an autoimmune disease characterized by erosive arthritis, and there are many RA patients worldwide. Methotrexate (MTX), the first-choice treatment for RA, can reduce the level of inflammation, prevent joint erosion and functional damage, and greatly reduce pain in RA patients. However, many patients show resistance to MTX, greatly affecting the efficacy of MTX. Many factors, such as irrational drug use and heredity, are associated with drug resistance. Considering the effect of drug transporters on drugs, many studies have compared the expression of drug transporters in drug-resistant and drug-sensitive patients, and abnormal transporter expression and transport activity have been found in patients with MTX resistance. Thus, drug transporters are involved in drug resistance. This article reviews the effects of transporters on the efficacy of MTX in the treatment of RA.

CD4 and CD8 T Cell Memory Interactions Alter Innate Immunity and Organ Injury in the CLP Sepsis Model

The role of T cell memory in sepsis is poorly understood. Recent work has demonstrated that mice exposed to frequent antigenic stimulation, in contrast to laboratory mice, better recapitulate the human T cell repertoire. This difference may profoundly alter responses to inflammatory insults. We induced isolated T cell memory by inoculating C57Bl/6 mice with an anti-CD3ϵ activating antibody, a process we term “immune education.” These mice were subjected to the cecal ligation and puncture (CLP) model of sepsis and responses were compared to those of isotype-treated controls. CLP-induced increases in 1) CD4 T cell production and serum levels of IFNγ, 2) CD8 T cell granzyme B levels, and 3) innate cell function were all more pronounced in educated mice than in control mice. Immune education increased CLP-induced liver injury and decreased survival. The differences in responses to CLP were not recapitulated in mice with either isolated CD4 or isolated CD8 T cell memory. Relative to controls, CLP in educated CD8^−/− mice (isolated CD4 memory) increased monocyte-derived dendritic cells. Combined CD4 and CD8 memory did not increase monocyte-derived dendritic cells; this combination recapitulated increases in neutrophil and inflammatory monocyte numbers in educated wild-type mice. Induction of T cell memory prior to CLP alters immune responses, organ function, and survival. Both CD4 and CD8 memory T cells play important and independent roles in this response. These findings have profound implications for the development of murine models of human inflammatory disorders such as infection and sepsis.

The surviving sepsis campaign: basic/translational science research priorities

Objectives

Expound upon priorities for basic/translational science identified in a recent paper by a group of experts assigned by the Society of Critical Care Medicine and the European Society of Intensive Care Medicine.

Data sources

Original paper, search of the literature.

Study selection

This study is selected by several members of the original task force with specific expertise in basic/translational science. Data extraction and data synthesis are not available.

Conclusions

In the first of a series of follow-up reports to the original paper, several members of the original task force with specific expertise provided a more in-depth analysis of the five identified priorities directly related to basic/translational science. This analysis expounds on what is known about the question and what was identified as priorities for ongoing research. It is hoped that this analysis will aid the development of future research initiatives.

Spirogyra neglecta Aqueous Extract Attenuates LPS-Induced Renal Inflammation

Spirogyra neglecta (SN), commonly named "Tao" in Thai, is a genus of filamentous green macroalgae. SN contains polyphenols such as isoquercetin, catechin, hydroquinone and kaempferol. These constituents exhibit beneficial effects including anti-oxidant, anti-gastric ulcer, anti-hyperglycaemia and anti-hyperlipidaemia in both in vitro and in vivo models. Whether SN extract (SNE) has an anti-inflammatory effect in vivo remains unclear. This study examined the effect of SNE on renal function and renal organic transport in lipopolysaccharide (LPS)-induced renal inflammation in rats. Rats were randomised and divided into normal saline (NS), NS supplemented with 1000 mg/kg body weight (BW) of SNE (NS + SNE), intraperitoneally injected with 12 mg/kg BW of LPS and LPS treated with 1000 mg/kg BW of SNE (LPS + SNE). Biochemical parameters in serum and urine, lipid peroxidation concentration, kidney function and renal organic anion and cation transports were determined. LPS-injected rats developed renal injury and inflammation by increasing urine microalbumin, total malondialdehyde (MDA) and inflammatory cytokines, tumor necrosis factor (TNF)-α and interleukin (IL)-1β protein expression, respectively. In addition, uptake of renal organic anion, [³H]-oestrone sulphate (ES), was reduced in LPS-injected rats together with increased expression of organic anion transporter 3 (Oat3). However, the renal injury and inflammation, as well as impaired Oat3 function and protein expression, were restored in LPS + SNE rats. Accordingly, SNE could be developed as nutraceutical product to prevent inflammation-induced nephrotoxicity.

Metabolomics Reveals the Efficacy of Caspase Inhibition for Saikosaponin D-Induced Hepatotoxicity

Saikosaponin d (SSd) is a major hepatoprotective component of saikosaponins derived from Radix Bupleuri, which was also linked to hepatotoxicity. Previous studies have demonstrated that caspases play a key role in SSd-induced liver cell death. Our in vitro and in vivo studies also showed that treatment with caspase inhibitor z-VAD-fmk could significantly reduce the L02 hepatocyte cells death and lessen the degree of liver damage in mice caused by SSd. In order to further reveal the underlying mechanisms of caspase inhibition in SSd-induced hepatotoxicity, mass spectrometry based untargeted metabolomics was conducted. Significant alterations in metabolic profiling were observed in SSd-treated group, which could be restored by caspase inhibition. Bile acids and phospholipids were screened out to be most significant by spearman correlation analysis, heatmap analysis and S-Plot analysis. These findings were further confirmed by absolute quantitation of bile acids via targeted metabolomics approach. Furthermore, cytokine profiles were analyzed to identify potential associations between inflammation and metabolites. The study could provide deeper insight into the hepatotoxicity of SSd and the efficacy of caspase inhibition.

Association of STAT-3 rs1053004 and VDR rs11574077 With FOLFIRI-Related Gastrointestinal Toxicity in Metastatic Colorectal Cancer Patients

Pharmacogenomics has largely been applied to the personalization of irinotecan-based treatment, focusing mainly on the study of genetic variants in adsorption, distribution, metabolism, and excretion (ADME) genes. The transcriptional control of ADME gene expression is mediated by a set of nuclear factors responding to cancer-related inflammation, which could have pharmacological implications. The aim of the present study was to uncover novel genetic predictors of neutropenia and gastrointestinal toxicity risk among 246 haplotype-tagging polymorphisms in 22 genes encoding inflammation-related cytokines and transcriptional regulators of ADME genes. The study comprised overall more than 400 metastatic colorectal cancer (mCRC) patients treated with first-line FOLFIRI, grouped in a discovery and a replication cohorts. A concordant protective effect of STAT-3 rs1053004 polymorphism against the risk of grade 3–4 gastrointestinal toxicity was observed in both the cohorts of patients (OR = 0.51, p = 0.045, q = 0.521 and OR = 0.39, p = 0.043, respectively). VDR rs11574077 polymorphism was demonstrated to affect both irinotecan biliary index (BI) and glucuronidation ratio (GR) by a pharmacokinetic analysis. This effect was consistent with an increased risk of grade 3–4 gastrointestinal toxicity in the discovery cohort (OR = 4.46, p = 0.010, q = 0.305). The association was not significant in the replication cohort (OR = 1.44, p = 0.601). These findings suggest an effect of STAT-3 and VDR polymorphisms on FOLFIRI-related gastrointestinal toxicity. If prospectively validated as predictive markers, they could be used to improve the clinical management of mCRC.

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.

Trafficking and other regulatory mechanisms for organic anion transporting polypeptides and organic anion transporters that modulate cellular drug and xenobiotic influx and that are dysregulated in disease

Organic anion transporters (OATs) and organic anion-transporting polypeptides (OATPs), encoded by a number of solute carrier (SLC)22A and SLC organic anion (SLCO) genes, mediate the absorption and distribution of drugs and other xenobiotics. The regulation of OATs and OATPs is complex, comprising both transcriptional and post-translational mechanisms. Plasma membrane expression is required for cellular substrate influx by OATs/OATPs. Thus, interest in post-translational regulatory processes, including membrane targeting, endocytosis, recycling and degradation of transporter proteins, is increasing because these are critical for plasma membrane expression. After being synthesized, transporters undergo N-glycosylation in the endoplasmic reticulum and Golgi apparatus and are delivered to the plasma membrane by vesicular transport. Their expression at the cell surface is maintained by de novo synthesis and recycling, which occurs after clathrin- and/or caveolin-dependent endocytosis of existing protein. Several studies have shown that phosphorylation by signalling kinases is important for the internalization and recycling processes, although the transporter protein does not appear to be directly phosphorylated. After internalization, transporters that are targeted for degradation undergo ubiquitination, most likely on intracellular loop residues. Epigenetic mechanisms, including methylation of gene regulatory regions and transcription from alternate promoters, are also significant in the regulation of certain SLC22A/SLCO genes. The membrane expression of OATs/OATPs is dysregulated in disease, which affects drug efficacy and detoxification. Several transporters are expressed in the cytoplasmic subcompartment in disease states, which suggests that membrane targeting/internalization/recycling may be impaired. This article focuses on recent developments in OAT and OATP regulation, their dysregulation in disease and the significance for drug therapy.

The role of interleukin-6 signaling in nervous tissue

The cytokine interleukin-6 (IL-6) plays a critical role in the pathogenesis of inflammatory disorders and in the physiological homeostasis of neural tissue. Profound neuropathological changes, such as multiple sclerosis (MS), Parkinson's and Alzheimer's disease are associated with increased IL-6 expression in brain. Increased nocturnal concentrations of serum IL-6 are found in patients with impaired sleep whereas IL-6-deficient mice spend more time in rapid eye movement sleep associated with dreaming. IL-6 is crucial in the differentiation of oligodendrocytes, regeneration of peripheral nerves and acts as a neurotrophic factor. It exerts its cellular effects through two distinct pathways which include the anti-inflammatory pathway involving the membrane-bound IL-6 receptor (IL-6R) expressed on selective cells, including microglia, in a process known as classical signaling that is also critical for bacterial defense. In classical signaling binding of IL-6 to the membrane-bound IL-6R activates the β-receptor glycoprotein 130 (gp130) and subsequent down-stream signaling. The alternative, rather pro-inflammatory pathway, shown to mediate neurodegeneration in mice, termed trans-signaling, depends on a soluble form of the IL-6R that is capable of binding IL-6 to stimulate a response on distal cells that express gp130. A naturally occurring soluble form of gp130 (sgp130) has been identified that can specifically bind and neutralize the IL-6R/IL-6 complex. Thus, trans-signaling is blocked but classical signaling is completely unaffected. A modified, recombinant dimerized version of sgp130 (sgp130Fc) has successfully been used to block inflammatory processes in mice and may also be used in the clarification of IL-6 trans-signaling in neurological diseases.

Selective and cytokine-dependent regulation of hepatic transporters and bile acid homeostasis during infectious colitis in mice

Various disease models have been shown to alter hepatic drug-metabolizing enzyme (DME) and transporter expression and to induce cholestasis through altered enzyme and transporter expression. Previously, we detailed the regulation of hepatic DMEs during infectious colitis caused by Citrobacter rodentium infection. We hypothesized that this infection would also modulate hepatic drug transporter expression and key genes of bile acid (BA) synthesis and transport. Mice lacking Toll-like receptor 4 (TLR4), interleukin-6 (IL-6), or interferon-gamma (IFNγ) and appropriate wild-type animals were orally infected with C. rodentium and sacrificed 7 days later. In two wild-type strains, drug transporter mRNA expression was significantly decreased by infection for Slc22a4, Slco1a1, Slco1a4, Slco2b1, and Abcc6, whereas the downregulation of Abcc2, Abcc3, and Abcc4 were strain-dependent. In contrast, mRNA expressions of Slco3a1 and Abcb1b were increased in a strain-dependent manner. Expression of Abcb11, Slc10a1, the two major hepatic BA transporters, and Cyp7a1, the rate-limiting enzyme of BA synthesis, was also significantly decreased in infected animals. None of the above effects were caused by bacterial lipopolysaccharide, since they still occurred in the absence of functional TLR4. The downregulation of Slc22a4 and Cyp7a1 was absent in IFNγ-null mice, and the downregulation of Slco1a1 was abrogated in IL-6-null mice, indicating in vivo roles for these cytokines in transporter regulation. These data indicate that C. rodentium infection modulates hepatic drug processing through alteration of transporter expression as well as DMEs. Furthermore, this infection downregulates important genes of BA synthesis and transport and may increase the risk for cholestasis.

Orexinergic activity modulates altered vital signs and pituitary hormone secretion in experimental sepsis

OBJECTIVES

Sepsis is a common, lethal poorly understood disorder affecting nearly a million Americans annually. The syndrome is characterized by altered cardiodynamics, respiration, metabolism, pituitary function, arousal, and impaired interaction among organ systems. The immunologic and endocrine systems, which are in part responsible for organ-organ communication, have been studied extensively in sepsis. However, little is known about sepsis-induced changes in central nervous system activity.

HYPOTHESIS

A defect in hypothalamic neurons secreting the neurotransmitter orexin modulates physiologic derangements in sepsis.

DESIGN

Animal study.

SETTING

University Research Laboratory.

INTERVENTIONS

Male C57Bl6 mice were made septic using cecal ligation and puncture. Data were collected 24 or 48 hours later, blood was collected, animals were killed, and brain tissue was harvested, fixed, and sectioned. Hypothalamic sections were subjected to immunohistochemistry using antibodies to orexin and c-Fos, a marker of neuronal activity. In a separate cohort of mice, cannulas were placed in the right lateral cerebral ventricle. Cecal ligation and puncture was performed 1 week later. At 24 or 48 hours post-cecal ligation and puncture, vital signs were measured, and1 µL of saline with or without 3 nmol orexin-A was infused. Vital signs were repeated at 25 or 49 hours post-cecal ligation and puncture, blood was collected, animals were killed, and brains were removed, fixed, sectioned, and stained.

MEASUREMENTS AND MAIN RESULTS

Orexinergic activity decreased six-fold following cecal ligation and puncture. This change was associated with decreases in arousal, temperature, and heart and respiratory rates. Levels of selected pituitary hormones increased 24 hours post-cecal ligation and puncture but were significantly lower than baseline at 48 hours. Injection of orexin-A increased vital signs to baseline levels. Hormone levels were unaffected at 25 hours but increased to supranormal levels at 49 hours.

CONCLUSIONS

Sepsis-induced changes in activity, vital signs, and pituitary hormones are modulated by the orexinergic system. This finding implicates central nervous system dysfunction in the pathogenesis of sepsis, suggesting further study of neurological dysfunction to identify novel approaches to management.

Impaired hepatocellular regeneration in murine sepsis is dependent on regulatory protein levels

Sepsis is a poorly understood syndrome. Therefore, we examined the mechanisms underlying failed regeneration in sham-operated (SO), mildly septic (cecal ligation and single puncture [CLP]), and severely septic (cecal ligation with two punctures [2CLP]) C57Bl6 mice. Relative to no operation (T0) or SO, CLP, but not 2CLP, increased the number of cells staining for proliferating cell nuclear antigen, a marker for cell division. Levels of the retinoblastoma protein (pRb) were detected at T0 and after SO. CLP increased pRb abundance, whereas 2CLP decreased it. Changes in phosphorylated pRb were similar but more profound. The abundance of the transcription factor E2F was unaltered by SO, CLP, or 2CLP. However, E2F DNA binding activity, although unchanged after SO, increased after CLP and decreased after 2CLP. The abundance of cyclin D1 in nuclear fractions increased following CLP but decreased after 2CLP. Neither SO nor 2CLP altered the abundance of the cyclin-dependent kinase (cdk) 4. However, cdk-4 abundance increased after CLP. Finally, CLP increased the steady-state abundance of the mRNAs encoding thymidine kinase, DNA polymerase α, and dihydrofolate reductase, all required for DNA replication. No changes were noted after 2CLP. We conclude that 2CLP impaired hepatocyte proliferation following 2CLP in part via impaired cyclin D1/cdk-4-induced phosphorylation of pRb, maintaining the association between pRb and E2F and inhibited E2F transcriptional activity.

An Improved Acute Gouty Arthritis Rat Model and Therapeutic Effect of Rhizoma Dioscoreae Nipponicae on Acute Gouty Arthritis Based on the Protein-Chip Methods

Rhizoma Dioscoreae Nipponicae (RDN) is an herbal medicine. In the theories of Traditional Chinese Medicine (TCM), the function of RDN is to expel wind and remove dampness. Inflammatory mechanisms play an important role in the pathological process and prognosis of acute gouty arthritis (AGA). The aim of this study was to determine the specially expressed proteins through testing the proteins of the synovium in rats with AGA. The animal model of AGA was set up by Monosodium urate crystal (MSU) combined with hypoxanthine (HX), which was ameliorated in our previous experiment. Blood samples for measurement of serum uric acid were collected prior to sacrifice. Outcomes were assessed (two days after injection) by histological stain and protein quantitation. Three chips of RayBioⓇHuman Label-based Antibody Array I were applied to detect 90 proteins in the synovium tissue of AGA rats. 14 differently expressed proteins were found in the synovium of AGA rats, and nine of them were first found in this model. There were seven up-regulated and seven down-regulated proteins, both TRAIL and Neuropilin-2 could be identified as key contributors to the pathomechanism of AGA.

Pathophysiologic role of hepatocyte nuclear factor 6

Hepatocyte nuclear factor 6 (HNF6) is one of liver-enriched transcription factors. HNF6 utilizes the bipartite onecut-homeodomain sequence to localize the HNF6 protein to the nuclear compartment and binds to specific DNA sequences of numerous target gene promoters. HNF6 regulates an intricate network and mediates complex biological processes that are best known in the liver and pancreas. The function of HNF6 is correlated to cell proliferation, cell cycle regulation, cell differentiation and organogenesis, cell migration and cell-matrix adhesion, glucose metabolism, bile homeostasis, inflammation and so on. HNF6 controls the transcription of its target genes in different ways. The details of the regulatory pathways and their mechanisms are still under investigation. Future study will explore HNF6 novel functions associated with apoptosis, oncogenesis, and modulation of the inflammatory response. This review highlights recent progression pertaining to the pathophysiologic role of HNF6 and summarizes the potential mechanisms in preclinical animal models. HNF6-mediated pathways represent attractive therapeutic targets for the treatment of the relative diseases such as cholestasis.

Targeting blood-brain barrier changes during inflammatory pain: an opportunity for optimizing CNS drug delivery

The blood-brain barrier (BBB) is the most significant obstacle to effective CNS drug delivery. It possesses structural and biochemical features (i.e., tight-junction protein complexes and, influx and efflux transporters) that restrict xenobiotic permeation. Pathophysiological stressors (i.e., peripheral inflammatory pain) can alter BBB tight junctions and transporters, which leads to drug-permeation changes. This is especially critical for opioids, which require precise CNS concentrations to be safe and effective analgesics. Recent studies have identified molecular targets (i.e., endogenous transporters and intracellular signaling systems) that can be exploited for optimization of CNS drug delivery. This article summarizes current knowledge in this area and emphasizes those targets that present the greatest opportunity for controlling drug permeation and/or drug transport across the BBB in an effort to achieve optimal CNS opioid delivery.

Injury-induced changes in liver specific transcription factors HNF-1α and HNF-4α

BACKGROUND

The hepatic acute phase response(APR) is an organ-specific response to a diverse array of insults and is largely under transcriptional control. Liver-specific transcription factors, hepatic nuclear factors (HNFs)-1α and 4α play important roles in maintenance of liver phenotype and function and their binding activity changes early after injury. However, their roles in modulation of the liver's response over time are not defined.

MATERIALS AND METHODS

C57/BL6 mice were anesthetized and exposed to 95°C water for 10 s to create a 15% body surface area full-thickness burn. At specific time points, the mice were sacrificed. An ELISA for IL-6 was performed on serum and hepatic mRNA levels for fibrinogen-γ and serum amyloid A(SAA)-3 were obtained through polymerase chain reaction (PCR). Transcriptional factor binding activity was assessed with electrophoretic mobility shift assays.

RESULTS

Serum IL-6 levels peaked at 3 h and fibrinogen-γ and SAA mRNA levels increased more than 6-fold at 12 h before returning to control levels at 48 h. The binding activity of HNF-4α and HNF-1α rapidly declined after injury (1.5 h) but recovered to near control level at 24 and 6 h, respectively.

CONCLUSIONS

Changes in HNF-4α and HNF-1α binding occurred before changes in acute phase protein mRNA levels and were preceded by the peak in IL-6 levels. The rapid suppression and reconstitution of liver-specific transcription factor binding after injury may represent a mechanism that allows the normal liver phenotype to change and an injury-response phenotype to prevail. This mechanism in the liver's adaptive response to injury suggests a central role for both HNF-4α and HNF-1α in transcriptional regulation of the hepatic APR.

Injury-induced changes in liver specific transcription factors HNF-1α and HNF-4α

BACKGROUND

The hepatic acute phase response(APR) is an organ-specific response to a diverse array of insults and is largely under transcriptional control. Liver-specific transcription factors, hepatic nuclear factors (HNFs)-1α and 4α play important roles in maintenance of liver phenotype and function and their binding activity changes early after injury. However, their roles in modulation of the liver's response over time are not defined.

MATERIALS AND METHODS

C57/BL6 mice were anesthetized and exposed to 95°C water for 10 s to create a 15% body surface area full-thickness burn. At specific time points, the mice were sacrificed. An ELISA for IL-6 was performed on serum and hepatic mRNA levels for fibrinogen-γ and serum amyloid A(SAA)-3 were obtained through polymerase chain reaction (PCR). Transcriptional factor binding activity was assessed with electrophoretic mobility shift assays.

RESULTS

Serum IL-6 levels peaked at 3 h and fibrinogen-γ and SAA mRNA levels increased more than 6-fold at 12 h before returning to control levels at 48 h. The binding activity of HNF-4α and HNF-1α rapidly declined after injury (1.5 h) but recovered to near control level at 24 and 6 h, respectively.

CONCLUSIONS

Changes in HNF-4α and HNF-1α binding occurred before changes in acute phase protein mRNA levels and were preceded by the peak in IL-6 levels. The rapid suppression and reconstitution of liver-specific transcription factor binding after injury may represent a mechanism that allows the normal liver phenotype to change and an injury-response phenotype to prevail. This mechanism in the liver's adaptive response to injury suggests a central role for both HNF-4α and HNF-1α in transcriptional regulation of the hepatic APR.

Interleukin-6 plays a protective role in development of cisplatin-induced acute renal failure through upregulation of anti-oxidative stress factors

AIMS

Cisplatin, a major chemotherapeutic agent, accumulates in proximal tubules of the kidneys and causes acute renal failure dose-dependently. We previously reported that cisplatin induced more severe renal dysfunction in interleukin-6 (IL-6) knockout (IL-6(-/-)) mice than in wild-type (WT) mice. Expression of a pro-apoptotic protein was significantly increased with cisplatin in IL-6(-/-) mice compared to that in WT mice. IL-6, locally expressed in renal tubular cells after cisplatin administration, prevents the development of renal dysfunction at an early stage. In the present study, we focused on downstream signals of IL-6 and oxidative stress induced by cisplatin in order to evaluate the protective role of IL-6 in the development of acute renal failure.

MAIN METHODS

WT and IL-6(-/-) mice were given either cisplatin (30 mg/kg) or saline intraperitoneally. Blood and kidney samples were collected at 24h and 72 h after cisplatin administration. The changes in expression of 4-hydroxy-2-nonenal protein (4-HNE, oxidative stress marker) and cyclooxygenase-2 (cox-2), activities of superoxide dismutases and caspase-3, and phosphorylation of extracellular signal-regulated kinase (ERK) were examined.

KEY FINDINGS

Cisplatin increased the expression of 4-HNE and cox-2, and phosphorylation of ERK in IL-6(-/-) mice than in WT mice. On the other hand, activity of superoxide dismutase, an anti-oxidative enzyme, was significantly decreased in the kidney obtained from IL-6(-/-) mice after cisplatin administration.

SIGNIFICANCE

Our findings suggest that IL-6 plays a protective role in the development of cisplatin-induced acute renal failure through upregulation of anti-oxidative stress factors.

Interleukin-6 in surgery, trauma, and critical care part II: clinical implications

A variety of cytokines play a role in the inflammatory response. Interleukin-6 (IL-6)-type cytokines are released in response to tissue injury or an inflammatory stimulus, and act locally and systemically to generate a variety of physiologic responses. Interleukin-6 concentrations are elevated after surgery, trauma, and critical illness. The magnitude of IL-6 elevation correlates with the extent of tissue trauma/injury severity. Furthermore, there is an association between IL-6 elevation and adverse outcome. Interleukin-6 levels can also be used to stratify patients for therapeutic intervention.

Interleukin-6 in surgery, trauma, and critical care part II: clinical implications

A variety of cytokines play a role in the inflammatory response. Interleukin-6 (IL-6)-type cytokines are released in response to tissue injury or an inflammatory stimulus, and act locally and systemically to generate a variety of physiologic responses. Interleukin-6 concentrations are elevated after surgery, trauma, and critical illness. The magnitude of IL-6 elevation correlates with the extent of tissue trauma/injury severity. Furthermore, there is an association between IL-6 elevation and adverse outcome. Interleukin-6 levels can also be used to stratify patients for therapeutic intervention.

Analytic review: Interleukin-6 in surgery, trauma, and critical care: part I: basic science

A variety of cytokines play a role in the response to an inflammatory stimulus. The interleukin-6 (IL-6)-type cytokines are released in response to tissue injury or an inflammatory stimulus. They act locally and systemically to generate a variety of physiologic responses, principal among them is the acute phase response. The IL-6 type cytokines demonstrate pleiotropy and redundancy of actions. This is made possible by the distinctive characteristics of the IL-6 receptor complex, which contains an ubiquitous subunit that is shared by most IL-6-type cytokines, as well as a cytokine-specific subunit.

Differential transcriptional characteristics of small and large biliary epithelial cells derived from small and large bile ducts

Biliary epithelial cells (BEC) are morphologically and functionally heterogeneous. To investigate the molecular mechanism for their diversities, we test the hypothesis that large and small BEC have disparity in their target gene response to their transcriptional regulator, the biliary cell-enriched hepatocyte nuclear factor HNF6. The expression of the major HNF (HNF6, OC2, HNF1b, HNF1a, HNF4a, C/EBPb, and Foxa2) and representative biliary transport target genes that are HNF dependent were compared between SV40-transformed BEC derived from large (SV40LG) and small (SV40SM) ducts, before and after treatment with recombinant adenoviral vectors expressing HNF6 (AdHNF6) or control LacZ cDNA (AdLacZ). Large and small BEC were isolated from mouse liver treated with growth hormone, a known transcriptional activator of HNF6, and the effects on selected target genes were examined. Constitutive Foxa2, HNF1a, and HNF4a gene expression were 2.3-, 12.4-, and 2.6-fold, respectively, higher in SV40SM cells. This was associated with 2.7- and 4-fold higher baseline expression of HNF1a- and HNF4a-regulated ntcp and oatp1 genes, respectively. Following AdHNF6 infection, HNF6 gene expression was 1.4-fold higher (P = 0.02) in AdHNF6 SV40SM relative to AdHNF6 SV40LG cells, with a corresponding higher Foxa2 (4-fold), HNF1a (15-fold), and HNF4a (6-fold) gene expression in AdHNF6-SV40SM over AdHNF6-SV40LG. The net effects were upregulation of HNF6 target gene glucokinase and of Foxa2, HNF1a, and HNF4a target genes oatp1, ntcp, and mrp2 over AdLacZ control in both cells, but with higher levels in AdH6-SV40SM over AdH6-SV40LG of glucokinase, oatp1, ntcp, and mrp2 (by 1.8-, 3.4-, 2.4-, and 2.5-fold, respectively). In vivo, growth hormone-mediated increase in HNF6 expression was associated with similar higher upregulation of glucokinase and mrp2 in cholangiocytes from small vs. large BEC. Small and large BEC have a distinct profile of hepatocyte transcription factor and cognate target gene expression, as well as differential strength of response to transcriptional regulation, thus providing a potential molecular basis for their divergent function.

The hepatic response to FGF19 is impaired in patients with nonalcoholic fatty liver disease and insulin resistance

Intestinal FGF19 has emerged as a novel endocrine regulator of hepatic bile salt and lipid metabolism. In patients with nonalcoholic fatty liver disease (NAFLD) hepatic lipid metabolism is deranged. A possible role of FGF19 in NAFLD has not been reported yet. In this study, we assessed intestinal FGF19 production and the hepatic response to FGF19 in NAFLD patients with and without insulin resistance [homeostasis model of assessment (HOMA) score > or =2.5 (n = 12) and HOMA score <2.5 (n = 8), respectively]. To this end, NAFLD patients received a standardized oral fat challenge. Postprandial excursions of triglycerides, bile salts, and FGF19 were monitored, and plasma levels of a marker for bile salt synthesis (7alpha-hydroxy-4-cholesten-3-one) were determined. Fasted FGF19 levels were comparable in a control group of healthy volunteers (n = 15) and in NAFLD patients (0.26 +/- 0.28 vs. 0.18 +/- 0.09 ng/ml, respectively, P = 0.94). Postprandial FGF19 levels in both controls and NAFLD patients peaked between 3-4 h and were three times higher than baseline levels. The areas under the postprandial FGF19 curve were similar in controls and in the HOMA score-based NAFLD subgroups. In NAFLD patients with HOMA score <2.5, the postprandial increase in plasma FGF19 was accompanied by a lowering of plasma levels of 7alpha-hydroxy-4-cholesten-3-one (-30%, P = 0.015). This anticipated decline was not observed in insulin-resistant NAFLD patients (+10%, P = 0.22). In conclusion, patients with NAFLD show an unimpaired intestinal FGF19 production. However, the hepatic response to FGF19 is impaired in NAFLD patients with insulin resistance (HOMA score > or =2.5). This impaired hepatic response to FGF19 may contribute to the dysregulation of lipid homeostasis in NAFLD.

Retinoid X receptor alpha participation in dexamethasone-induced rat bile acid coenzyme A-amino acid N-acyltransferase expression in septic liver

To test the hypothesis that dexamethasone (Dex) treatment would restore rat hepatic bile acid coenzyme A-amino acid N-acyltransferase (rBAT) expression in septic rats after cecal ligation and puncture by increasing expression of retinoic acid X receptor alpha (RXRalpha), we assessed survival rate and bile and bile salt concentration in the Dex-treated septic group and compared these results with those for a nontreated septic group, a Dex-treated nonseptic group, and a sham group. Dexamethasone treatment (0.01 mg/kg) significantly improved the survival rate and increased the bile and bile salt concentration in the bile ducts of septic rats (P = <0.05). In our assessment of bile salt-related genes, during sepsis, there were decreases in protein and mRNA expression of rBAT and cholesterol 7 alpha-hydroxylase (CYP7A1). Treatment with Dex restored expression of rBAT and RXR[alpha] but not CYP7A1, bile salt export pump, or multidrug resistance associated protein 2 (MRP2). Na+-taurocholate cotransport protein and organic anion transporting polypeptide 1 were unchanged. In addition, treatment with Dex also restored the DNA-binding activity of RXR/farnesoid-X receptor to rBAT promoter containing inverted repeat 1 sequence. In an experiment to confirm our findings, RXR[alpha] siRNA was found to significantly block Dex-induced increases in expression of rBAT in hepatocytes taken from septic rats (P < 0.01).

CONCLUSION

Dex restored the expression of rBAT in septic rats by enhancing RXR[alpha], a process that might explain the mechanism underlying Dex's anticholestatic effect.

Hepatic nuclear factor 1-alpha: inflammation, genetics, and atherosclerosis

PURPOSE OF REVIEW

Increased plasma levels of C-reactive protein (CRP), a hepatic acute phase reactant, predict risk for coronary heart disease. There has been interest in identifying genetic determinants of CRP as a means of better understanding its regulation and its relation to coronary heart disease. We here review recent findings that have linked plasma CRP levels to single nucleotide polymorphisms in hepatic nuclear factor (HNF) 1-alpha, a transcription factor with a wide range of functions, including many involved in cholesterol, bile acid, and lipoprotein metabolism.

RECENT FINDINGS

Two genome-wide association studies have identified single nucleotide polymorphisms in several genes that are strongly related to plasma CRP levels, including several on chromosome 12 in the vicinity of the HNF1A gene. The CRP gene promoter has two HNF1-alpha-binding sites. Recently, it has been demonstrated that HNF1-alpha is required for cytokine-driven CRP expression and that this involves formation of a complex with STAT3 and c-Fos.

SUMMARY

Based on the recent genetic findings as well as delineation of the role of HNF1-alpha in regulating the expression of the CRP gene, it appears that this transcription factor may play a key role in linking metabolic and inflammatory pathways underlying the pathogenesis of coronary heart disease.

Expression of bile acid transporting proteins in Barrett's esophagus and esophageal adenocarcinoma

OBJECTIVES

Barrett's esophagus (BE) is a metaplastic lesion characterized by replacement of the normal squamous epithelium by columnar intestinal epithelium containing goblet cells. It is speculated that this process is an adaptation to protect cells from components of refluxate, such as gastric acid and bile acids. In contrast to the normal squamous epithelium, enterocytes of the distal ileum are adapted to transport bile acids from the intestinal lumen. Several bile acid transporters are utilized for effective removal of bile acids, including the apical sodium-dependent bile acid transporter (ASBT), the ileal bile acid-binding protein (IBABP), and the multidrug-resistant protein 3 (MRP3). We hypothesized that one of the possible functions of newly arising metaplastic epithelium, in the esophagus, is to transport bile acids. Our major goal was to evaluate the expression of bile acid transporters in normal squamous epithelium, BE with different grades of dysplasia, and esophageal adenocarcinoma (EAC).

METHODS

A total of 101 patients were included in this study. Immunohistochemistry (IHC) and reverse transcriptase (RT)-PCR were used to detect the expression of these transporters at the mRNA and protein levels.

RESULTS

Our immunohistochemical studies showed that all three bile acid transporters are expressed in BE glands, but not in squamous epithelium. ASBT was found in the apical border in BE biopsies. The highest frequency of ASBT expression was in patients with nondysplastic BE (9 of 15, 60%), and a progressive loss of ASBT was observed through the stages of dysplasia. ASBT was not detected in EAC (0 of 15). IBABP staining was observed in the cytoplasm of BE epithelial surface cells. Expression of IBABP was found in 100% of nondysplastic BE (14 of 14), in 93% of low-grade dysplasia (LGD, 15 of 16), in 73% of high-grade dysplasia (HGD, 10 of 14), and in 33% of EAC (5 of 15). MRP3 was expressed in the basolateral membrane in 93% of nondysplastic BE (13 of 14), in 60% of LGD (10 of 16), and in 86% of HGD (11 of 13). Only weak MRP3 staining was detected in EAC biopsies (5 of 15, 33%). In addition, RT-PCR studies showed increased expression of mRNA coding for ASBT (6.1x), IBABP (9.1x), and MRP3 (2.4x) in BE (N=13) compared with normal squamous epithelium (N=15). Significantly increased mRNA levels of IBABP (10.1x) and MRP3 (2.5x) were also detected in EAC (N=21) compared with normal squamous epithelium.

CONCLUSIONS

We found that bile acid transporters expression is increased in BE tissue at the mRNA and protein levels and that expression of bile acid transporter proteins decreased with progression to cancer.