Cellular and molecular mechanisms regulating the hepatic erythropoietin expression during acute-phase response: a role for IL-6

L-arabinose Attenuates LPS-Induced Intestinal Inflammation and Injury through Reduced M1 Macrophage Polarization

BACKGROUND

L-arabinose has anti-inflammatory and metabolism-promoting properties, and macrophages participate in the alleviation of inflammation; however, the mechanism by which they contribute to the anti-inflammatory effects of L-arabinose is unknown.

OBJECTIVES

To investigate the involvement of macrophages in the mitigation of L-arabinose in an intestinal inflammation model induced by lipopolysaccharide (LPS).

METHODS

Five-week-old male C57BL/6 mice were divided into 3 groups: a control and an LPS group that both received normal water supplementation, and an L-arabinose (ARA+LPS) group that received 5% L-arabinose supplementation. Mice in the LPS and ARA+LPS groups were intraperitoneally injected with LPS (10 mg/kg body weight), whereas the control group was intraperitoneally injected with the same volume of saline. Intestinal morphology, cytokines, tight junction proteins, macrophage phenotypes, and microbial communities were profiled at 6 h postinjection.

RESULTS

L-arabinose alleviated LPS-induced damage to intestinal morphology. L-arabinose down-regulated serum tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, and IL-6, and messenger RNA (mRNA) levels of TNF-α, IL-1β, interferon-γ (IFN-γ), and toll-like receptor-4 in jejunum and colon compared with those of the LPS group (P < 0.05). The mRNA and protein levels of occludin and claudin-1 were significantly increased by L-arabinose (P < 0.05). Interferon regulatory factor-5 (IRF-5) and signal transducer and activator of transcription-1 (STAT-1), key genes characterized by M1 macrophages, were elevated in the jejunum and colon of LPS mice (P < 0.05) but decreased in the ARA+LPS mice (P < 0.05). In vitro, L-arabinose decreased the proportion of M1 macrophages and inhibited mRNA levels of TNF-α, IL-1β, IL-6, IFN-γ, as well as IRF-5 and STAT-1 (P < 0.01). Moreover, L-arabinose restored the abundance of norank_f__Muribaculaceae, Faecalibaculum, Dubosiella, Prevotellaceae_UCG-001, and Paraasutterella compared with those of LPS (P < 0.05) and increased the concentration of short-chain fatty acids (P < 0.05).

CONCLUSION

The anti-inflammatory effects of L-arabinose are achieved by reducing M1 macrophage polarization, suggesting that L-arabinose could be a candidate functional food or nutritional strategy for intestinal inflammation and injury.

Interleukin-6-Production Is Responsible for Induction of Hepatic Synthesis of Several Chemokines as Acute-Phase Mediators in Two Animal Models: Possible Significance for Interpretation of Laboratory Changes in Severely Ill Patients

Simple Summary

The release of acute-phase proteins and cytokine storms are considered critical parameters for the progression of COVID-19 disease. The increase in the serum levels of cytokines such as IL6 and IL8 observed in patients primarily infected with the SARS-CoV-2 virus has been used to determine the severity of clinical conditions resulting from infection and for prognostic purposes. Animal models have been used to understand the mechanisms of the changes in homeostasis observed under pathological conditions. In the present study, we therefore report the changes in serum levels and hepatic gene expression of cytokines and chemokines in two different animal models of acute-phase responses. The acute-phase response is a transient emergency response aimed at preserving life and bringing about the changes necessary to reduce and repair tissue damage after the removal of damaging noxious agents. Our data suggest that the liver may be responsible for the increase in the serum levels of cytokines and chemokines as part of the body’s defense response to tissue damage. It is therefore doubtful that inhibiting this response at any stage after infection could improve the prognosis of patients. These results may help to interpret the laboratory changes observed in critically ill patients, as may be the case following SARS-CoV-2 infection.

Abstract

A mild to moderate increase in acute-phase proteins (APPs) and a decrease in serum albumin levels are detected in hospitalized COVID-19 patients. A similar trend is also observed for acute-phase cytokines (APC), mainly IL6, besides chemokines (e.g., CXCL8 and CCL2). However, the source of the chemokines in these patients at different stages of disease remains to be elucidated. We investigated hepatic gene expression of CXC- and CC-chemokines in a model of a localized extrahepatic aseptic abscess and in a model of septicemia produced by the intramuscular injection of turpentine oil (TO) into each hindlimb or lipopolysaccharide (LPS) intraperitoneally (i.p.) in rats and mice (wild-type (WT) and IL6-KO). Together with a striking increase in the serum IL6 level, strong serum CXCL2 and CXCL8 concentrations were detected. Correspondingly, rapid (2 h) upregulation of CXCL1, CXCL2, CXCL5, and CXCL8 was observed in rat liver after intramuscular TO injection. The induction of the gene expression of CXCL1 and CXCL8 was the fastest and strongest. The hepatic CXC-chemokines behaved like positive APPs that depend on IL6 production by activated macrophages recruited to extrahepatic damaged tissue. Chemokine upregulation was greatly reduced in IL6-KO mice. However, IL6 was dispensable in the LPS–APR model, as massive induction of hepatic chemokines studied was measured in IL6-KO mice.

GDF11 rapidly increases lipid accumulation in liver cancer cells through ALK5-dependent signaling

Hepatocellular carcinoma (HCC) is one of the fastest-growing causes of cancer-related mortalities worldwide and this trend is mimicked by the surge of non-alcoholic fatty liver disease (NAFLD). Altered hepatic lipid metabolism promotes HCC development through inflammation and activation of oncogenes. GDF11 is a member of the TGF-β superfamily and recent data have implicated GDF11 as an anti-aging factor that can alleviate high-fat diet induced obesity, hyperglycemia, insulin resistance and NAFLD. However, its role in hepatic lipid metabolism is still not fully delineated. The aim of the present study was to characterize the role of GDF11 in hepatic and HCC cells lipid accumulation. To achieve this, we performed imaging, biochemical, lipidomic, and transcriptomic analyses in primary hepatocytes and in HCC cells treated with GDF11 to study the GDF11-activated signaling pathways. GDF11 treatment rapidly triggered ALK5-dependent SMAD2/3 nuclear translocation and elevated lipid droplets in HCC cells, but not in primary hepatocytes. In HCC cells, ALK5 inhibition hampered GDF11-mediated SMAD2/3 signaling and attenuated lipid accumulation. Using ultra-high-performance liquid chromatography/mass spectrometry, we detected increased accumulation of longer acyl-chain di/tri-acylglycerols and glycerophospholipids. Unbiased transcriptomic analysis identified TGF-β and PI3K-AKT signaling among the top pathways/cellular processes activated in GDF11 treated HCC cells. In summary, GDF11 supplementation promotes pro-lipogenic gene expression and lipid accumulation in HCC cells. Integration of our "omics" data pointed to a GDF11-induced upregulation of de novo lipogenesis through activation of ALK5/SMAD2/3/PI3K-AKT pathways. Thus, GDF11 could contribute to metabolic reprogramming and dysregulation of lipid metabolism in HCC cells, without effects on healthy hepatocytes.

Hepcidin and Iron Metabolism in Experimental Liver Injury

The liver plays a pivotal role in the regulation of iron metabolism through its ability to sense and respond to iron stores by release of the hormone hepcidin. Under physiologic conditions, regulation of hepcidin expression in response to iron status maintains iron homeostasis. In response to tissue injury, hepcidin expression can be modulated by other factors, such as inflammation and oxidative stress. The resulting dysregulation of hepcidin is proposed to account for alterations in iron homeostasis that are sometimes observed in patients with liver disease. This review describes the effects of experimental forms of liver injury on iron metabolism and hepcidin expression. In general, models of acute liver injury demonstrate increases in hepcidin mRNA and hypoferremia, consistent with hepcidin's role as an acute-phase reactant. Conversely, diverse models of chronic liver injury are associated with decreased hepcidin mRNA but with variable effects on iron status. Elucidating the reasons for the disparate impact of different chronic injuries on iron metabolism is an important research priority, as is a deeper understanding of the interplay among various stimuli, both positive and negative, on hepcidin regulation. Future studies should provide a clearer picture of how dysregulation of hepcidin expression and altered iron homeostasis impact the progression of liver diseases and whether they are a cause or consequence of these pathologies.

Catalpol ameliorates doxorubicin-induced inflammation and oxidative stress in H9C2 cells through PPAR-γ activation

Drug-induced cardiomyopathy is a severe disease that leads to refractory heart disease at late stages, with increasing detrimental effects. DOX-induced cell damage is primarily induced via cellular oxidative stress. The present study investigated the effects of catalpol on doxorubicin (DOX)-induced H9C2 cardiomyocyte inflammation and oxidative stress. The Cell Counting Kit-8 assay was performed to detect cell viability, and western blotting was performed to detect the expression of peroxisome proliferator-activated receptor (PPAR)-γ in H9C2 cells. The expression levels of tumor necrosis factor-α (TNF-α), interleukin (IL)-1β and IL-6 were measured using ELISAs. Furthermore, the oxidative stress kit was used to detect the levels of malondialdehyde, superoxide dismutase and glutathione peroxidase. A reactive oxygen species (ROS) kit and DCF-DA staining were used to detect ROS levels. The results indicated that DOX treatment inhibited H9C2 cell expression of PPAR-γ and decreased H9C2 cell viability. Various concentrations of catalpol exhibited a less potent effect on H9C2 cell viability compared with DOX; however, catalpol increased the viability of DOX-induced H9C2 cells. Catalpol treatment also significantly decreased the expression levels of inflammatory factors (TNF-α, IL-1β and IL-6) in DOX-induced H9C2 cells, which was reversed by transfections with short hairpin RNA targeting PPAR-γ. Results from the present study indicated that catalpol ameliorated DOX-induced inflammation and oxidative stress in H9C2 cardiomyoblasts by activating PPAR-γ.

Modulation of Chemokine- and Adhesion-Molecule Gene Expression and Recruitment of Neutrophil Granulocytes in Rat and Mouse Liver after a Single Gadolinium Chloride or Zymosan Treatment

Kupffer cells are professional phagocytes of the liver clearing bacteria from portal blood. Their clearance capacity, however, can be overwhelmed, transforming them into critical mediators of hepatic-injury. We investigated the consequences of selective Kupffer cell-overload by intraperitoneally administering pyrogen-free gadolinium chloride (GdCl₃) or Zymosan into rats and into endotoxin-resistant mice (C3H/HeJ). The number of myeloperoxidase-positive (MPO⁺) cells increased at 3 h mainly around the portal vessel after both GdCl₃ and Zymosan treatment. Simultaneously, GdCl₃ administration reduced detectability of ED-1⁺ (but not ED-2) cells near the portal vessel. Serum chemokine (C-X-C motif) ligand 1 (CXCL-1), CXCL-2 and chemokine (C-C motif) ligand 2 (CCL-2) showed a peak at 3 h after both treatment regimens although at a higher extent after Zymosan administration. Accordingly, CXCL-1, CXCL-5 and CCL-2 gene expression in the liver was up-regulated after GdCl₃ treatment at 3 h. After Zymosan administration a significant up-regulation of CXCL-1, CXCL-2, CXCL-10, CCL-2, CCL-3 and CCL-20 gene expression in liver at 3 h was observed. After Zymosan administration intracellular adhesion molecule 1 (ICAM-1) and vascular cell adhesion molecule 1 (VCAM-1) gene expression was up-regulated in rat liver tissue. In C3H/HeJ mice both treatment regimens up-regulated CCL-2 and ICAM-1 gene expression after 3 h and down-regulated platelet endothelial cell adhesion molecule 1 (PECAM-1) gene expression. In conclusion, phagocytosis overload of Kupffer cells causes induction of several CXC, CC-chemokines, upregulation of "positive" adhesion molecule gene expression, down-regulation of the "negative" adhesion molecule PECAM-1 and a recruitment of neutrophil granulocytes in the portal area of the liver of treated rats and mice mainly in close contact to the liver macrophages.

Kupffer Cells Survive Plasmodium berghei Sporozoite Exposure and Respond with a Rapid Cytokine Release

The liver stage of the Plasmodium life cycle features sporozoite traversal of the liver sinusoidal barrier through Kupffer cells (KCs) followed by invasion of hepatocytes. Little is known about the interaction of Plasmodium sporozoites with KCs, the liver-resident macrophages. Previous reports suggest KCs do not mount a pro-inflammatory response and undergo cell death following this interaction. Our work explores this interaction using primary rat KCs (PRKCs) and Plasmodium berghei sporozoites. We analyzed PRKC culture supernatants for markers of an immunological response through cytokine arrays. Additionally, cell wounding and death were assessed by monitoring lactate dehydrogenase (LDH) levels in these supernatants and by live/dead cell imaging. We found that PRKCs mount an immunological response to P. berghei sporozoites by releasing a diverse set of both pro- and anti-inflammatory cytokines, including IFNγ, IL-12p70, Mip-3α, IL-2, RANTES, IL-1α, IL-4, IL-5, IL-13, EPO, VEGF, IL-7, and IL-17α. We also observed no difference in LDH level or live/dead staining upon sporozoite exposure, suggesting that the KCs are not deeply wounded or dying. Overall, our data suggest that sporozoites may be actively modulating the KC's reaction to their presence and altering the way the innate immune system is triggered by KCs.

Respiratory virus infection up-regulates TRPV1, TRPA1 and ASICS3 receptors on airway cells

Receptors implicated in cough hypersensitivity are transient receptor potential vanilloid 1 (TRPV1), transient receptor potential cation channel, Subfamily A, Member 1 (TRPA1) and acid sensing ion channel receptor 3 (ASIC3). Respiratory viruses, such as respiratory syncytial virus (RSV) and measles virus (MV) may interact directly and/or indirectly with these receptors on sensory nerves and epithelial cells in the airways. We used in vitro models of sensory neurones (SHSY5Y or differentiated IMR-32 cells) and human bronchial epithelium (BEAS-2B cells) as well as primary human bronchial epithelial cells (PBEC) to study the effect of MV and RSV infection on receptor expression. Receptor mRNA and protein levels were examined by qPCR and flow cytometry, respectively, following infection or treatment with UV inactivated virus, virus-induced soluble factors or pelleted virus. Concentrations of a range of cytokines in resultant BEAS-2B and PBEC supernatants were determined by ELISA. Up-regulation of TRPV1, TRPA1 and ASICS3 expression occurred by 12 hours post-infection in each cell type. This was independent of replicating virus, within the same cell, as virus-induced soluble factors alone were sufficient to increase channel expression. IL-8 and IL-6 increased in infected cell supernatants. Antibodies against these factors inhibited TRP receptor up-regulation. Capsazepine treatment inhibited virus induced up-regulation of TRPV1 indicating that these receptors are targets for treating virus-induced cough.

Stress-activated miR-21/miR-21* in hepatocytes promotes lipid and glucose metabolic disorders associated with high-fat diet consumption

OBJECTIVE

miR-21 is an oncomir highly upregulated in hepatocellular carcinoma and in early stages of liver diseases characterised by the presence of steatosis. Whether upregulation of miR-21 contributes to hepatic metabolic disorders and their progression towards cancer is unknown. This study aims at investigating the role of miR-21/miR-21* in early stages of metabolic liver disorders associated with diet-induced obesity (DIO).

DESIGN

Constitutive miR-21/miR-21* knockout (miR21KO) and liver-specific miR-21/miR-21* knockout (LImiR21KO) mice were generated. Mice were then fed with high-fat diet (HFD) and alterations of the lipid and glucose metabolism were investigated. Serum and ex vivo explanted liver tissue were analysed.

RESULTS

Under normal breeding conditions and standard diet, miR-21/miR-21* deletion in mice was not associated with any detectable phenotypic alterations. However, when mice were challenged with an obesogenic diet, glucose intolerance, steatosis and adiposity were improved in mice lacking miR-21/miR-21*. Deletion of miR-21/miR-21* specifically in hepatocytes led to similar improvements in mice fed an HFD, indicating a crucial role for hepatic miR-21/miR-21* in metabolic disorders associated with DIO. Further molecular analyses demonstrated that miR-21/miR-21* deletion in hepatocytes increases insulin sensitivity and modulates the expression of multiple key metabolic transcription factors involved in fatty acid uptake, de novo lipogenesis, gluconeogenesis and glucose output.

CONCLUSIONS

Hepatic miR-21/miR-21* deficiency prevents glucose intolerance and steatosis in mice fed an obesogenic diet by altering the expression of several master metabolic regulators. This study points out miR-21/miR-21* as a potential therapeutic target for non-alcoholic fatty liver disease and the metabolic syndrome.

Haemoglobin mass alterations in healthy humans following four-day head-down tilt bed rest

NEW FINDINGS

What is the central question of this study? Is haemoglobin mass (Hbmass) decreased following 4 days of head-down tilt bed rest (HDTBR), and does increased red blood cell (RBC) destruction mediate this adaptation? What is the main finding and its importance? Haemoglobin mass was increased immediately following HDTBR, before decreasing below baseline 5 days after return to normal living conditions. The transient increase in Hbmass might be the result of decreased RBC destruction, but it is also possible that spleen contraction after HDTBR contributed to this adaptation. Our data suggest that the decreased Hbmass 5 days following HDTBR resulted from decreased RBC production, not increased RBC destruction. Rapid decreases in haemoglobin mass (Hbmass) have been reported in healthy humans following spaceflight and descent from high altitude. It has been proposed that a selective increase in the destruction of young red blood cells (RBCs) mediates these decreases, but conclusive evidence demonstrating neocytolysis in humans is lacking. Based on the proposed triggers and time course of adaptation during spaceflight, we hypothesized that Hbmass would be reduced after 4 days of -6 deg head-down tilt bed rest (HDTBR) and that this would be associated with evidence for increased RBC destruction. We assessed Hbmass in seven healthy, recreationally active men before (PRE), 5 h after (POST) and 5 days after (POST5) 4 days of HDTBR. The concentration of erythropoietin decreased from 7.1 ± 1.8 mIU ml(-1) at PRE to 5.2 ± 2.8 mIU ml(-1) at POST (mean ± SD; P = 0.028). Contrary to our hypothesis, Hbmass was increased from 817 ± 135 g at PRE to 849 ± 141 g at POST (P = 0.014) before decreasing below PRE to 789 ± 139 g at POST5 (P = 0.027). From PRE to POST, the concentration of haptoglobin increased from 0.54 ± 0.32 to 0.68 ± 0.28 g l(-1) (P = 0.013) and the concentration of bilirubin decreased from 0.50 ± 0.24 to 0.32 ± 0.11 mg dl(-1) (P = 0.054), suggesting that decreased RBC destruction might have contributed to the increased Hbmass. However, it is possible that spleen contraction following HDTBR also played a role in the increase in Hbmass at POST, but as the transient increase in Hbmass was unexpected, we did not collect data that would provide direct evidence for or against spleen contraction. From PRE to POST5, the concentration of soluble transferrin receptor decreased from 20.7 ± 3.9 to 17.1 ± 3.3 nmol l(-1) (P = 0.018) but the concentrations of ferritin, haptoglobin and bilirubin were not significantly altered, suggesting that the decrease in Hbmass was mediated by decreased RBC production rather than increased RBC destruction. Peak oxygen uptake decreased by 0.31 ± 0.16 l min(-1) from PRE to POST (P = 2 × 10(-4) ) but was not significantly altered at POST5 compared with PRE. Overall, these findings indicate that 4 days of HDTBR does not increase RBC destruction and that re-examination of the time course and mechanisms of Hbmass alterations following short-term spaceflight and simulated microgravity is warranted.

Induction of Lipocalin2 in a Rat Model of Lung Irradiation

Previously, we showed that lipocalin2 (LCN2) serum levels increased after liver irradiation and during acute-phase conditions. Here, we evaluate LCN2 expression and serum levels after single-dose lung irradiation with 25 Gy, percutaneously administered to the lung of randomly-paired male Wistar rats. Due to the concave anatomy of the lung recesses, the irradiation field included the upper part of the liver. No rat died due to irradiation. In control tissue, lung immunohistochemistry showed a high constitutive expression of LCN2+ granulocytes. LCN2 mRNA levels in lung tissue increased up to 24 h (9 ± 2.3-fold) after irradiation. However, serum LCN2 levels remained undetectable after lung irradiation. LCN2 expression in the upper part of the liver increased up to 4.2-fold after lung irradiation, but the lower liver showed an early decrease. Acute-phase cytokines (IL-1β and TNF-α) showed a significant increase on transcript level in both lung and upper liver, whilst the lower liver did not show any considerable increase. In conclusion, constitutive expression of LCN2 in local immune cells demonstrates its local role during stress conditions in the lung. The absence of LCN2 in the serum strengthens our previous findings that the liver is the key player in secreting LCN2 during stress conditions with liver involvement.

Hypoxia-independent upregulation of placental hypoxia inducible factor-1α gene expression contributes to the pathogenesis of preeclampsia

Accumulation of hypoxia inducible factor-1α (HIF-1α) is commonly an acute and beneficial response to hypoxia, whereas chronically elevated HIF-1α is associated with multiple disease conditions, including preeclampsia, a serious hypertensive disease of pregnancy. However, the molecular basis underlying the persistent elevation of placental HIF-1α in preeclampsia and its role in the pathogenesis of preeclampsia are poorly understood. Here we report that Hif-1α mRNA and HIF-1α protein were elevated in the placentas of pregnant mice infused with angiotensin II type I receptor agonistic autoantibody, a pathogenic factor in preeclampsia. Knockdown of placental Hif-1α mRNA by specific siRNA significantly attenuated hallmark features of preeclampsia induced by angiotensin II type I receptor agonistic autoantibody in pregnant mice, including hypertension, proteinuria, kidney damage, impaired placental vasculature, and elevated maternal circulating soluble fms-like tyrosine kinase-1 levels. Next, we discovered that Hif-1α mRNA levels and HIF-1α protein levels were induced in an independent preeclampsia model with infusion of the inflammatory cytokine tumor necrosis factor superfamily member 14 (LIGHT). SiRNA knockdown experiments also demonstrated that elevated HIF-1α contributed to LIGHT-induced preeclampsia features. Translational studies with human placentas showed that angiotensin II type I receptor agonistic autoantibody or LIGHT is capable of inducing HIF-1α in a hypoxia-independent manner. Moreover, increased HIF-1α was found to be responsible for angiotensin II type I receptor agonistic autoantibody or LIGHT-induced elevation of Flt-1 gene expression and production of soluble fms-like tyrosine kinase-1 in human villous explants. Overall, we demonstrated that hypoxia-independent stimulation of HIF-1α gene expression in the placenta is a common pathogenic mechanism promoting disease progression. Our findings reveal new insight to preeclampsia and highlight novel therapeutic possibilities for the disease.

Clinical and pathological features of Nerium oleander extract toxicosis in wistar rats

BACKGROUND

Nerium oleander has been widely studied for medicinal purposes for variety of maladies. N. oleander has also been reported having noxious effects because of its number of components that may show signs of toxicity by inhibiting plasma lemma Na+, K+-ATPase. The present study was performed to scrutinize the toxic effect of N. oleander leaves extract and its clinical and pathological features in wistar rats.

RESULTS

Hematological analysis showed significant variations in RBCs count (P = 0.01), Hb (P = 0.001), Hct (P = 0.0003), MCV (P = 0.013), lymphocyte count (P = 0.015), neutrophil count (P = 0.003), monocyte count (P = 0.012) and eosinophil count (P = 0.006). Histopathological studies have shown that in T1 group noticeable infiltration of inflammatory cells was found with low level of vascular damage. In T2 group, increased proportion of binucleated and inflammatory cells, hepatic necrosis, widening of sinusoidal spaces and mild level of vascular damage was observed.

CONCLUSION

Taken together these findings we can conclude that N. oleander leaves extract significantly affects on experimental animals due to its toxicity. Efforts must be exerted to purify different chemical components from extract with no inflammation as this plant is utilized in folk medicine with narrow therapeutic indices.

Elevated serum erythropoietin in a patient with polycythaemia vera presenting with Budd-Chiari syndrome

Polycythaemia vera (PV) is a clonal disorder of bone marrow stem cells characterised by erythrocytosis. Diagnosis of PV requires exclusion of secondary causes of polycythaemia. It has been held that an elevated erythropoietin (Epo) level strongly indicates secondary erythrocytosis and excludes PV diagnosis, to the extent that the reduced serum Epo level is currently listed as a minor criterion in the WHO classification scheme for PV. However, patients with PV who co-present with Budd-Chiari syndrome have been documented with elevated serum Epo levels. For these patients, identification of the Janus kinase 2 (JAK2) V617F point mutation along with the transient nature of the Epo elevation provides certainty of PV diagnosis, as illustrated by the proband. In this case report, the patient's positive response to cytoreductive therapy (hydroxyurea 500 mg daily) and phlebotomy (750 mL over three phlebotomies) further supports validity of PV diagnosis with elevated Epo. The patient remains on rivaroxaban (Xarelto) for treatment of her portal vein thrombosis.

Endogenous erythropoietin varies significantly with inflammation-related proteins in extremely premature newborns

INTRODUCTION

Erythropoietin, a pluripotent glycoprotein essential for erythropoiesis, fetal growth, and development, has recently been implicated in innate immune regulation. Data from the ELGAN Study allowed us to evaluate relationships between endogenous erythropoietin and 25 inflammation-related proteins in extremely premature newborns.

METHODS

We measured the concentrations of 25 inflammation-related proteins and of erythropoietin in blood spots collected on postnatal days 1, 7, and 14 from 936 infants born before 28 weeks gestation. We calculated the odds that infants with an inflammation-related protein in the highest quartile for gestational age and collection day had an erythropoietin concentration in the highest or lowest quartile.

RESULTS

The proportion of children with inflammation-associated protein concentrations in the top quartile tended to increase monotonically with increasing quartile of EPO concentrations on 2 of the 3 days assessed. To a large extent, on each of the 3 days assessed, the odds ratios for an erythropoietin concentration in the top quartile were significantly elevated among those with an inflammation-related protein concentration in the top quartile.

CONCLUSIONS

Our findings suggest that in very preterm newborns, circulating levels of endogenous erythropoietin vary significantly with circulating levels of inflammation-related proteins. Elevation of endogenous erythropoietin might not be an epiphenomenon, but instead might contribute to subsequent events, by either promoting or reducing inflammation, or by promoting an anti-injury or repair capability.

Potential roles played by IL-6 in hepatitis B infection

ABSTRACT: 

Hepatitis B is a main disorder of the liver, which is induced by HBV. Hepatitis B can induce liver diseases, such as inflammation, cirrhosis and hepatocellular carcinoma (HCC). Recent studies demonstrated that several patients are unable to eradicate the virus from hepatocytes and develop chronic hepatitis B infections. The main mechanisms responsible for development of chronic hepatitis B and its related cirrhosis as well as HCC are yet to be identified. IL-6 is a proinflammatory cytokine that participates in stimulation of immune responses against viral infections. In addition, it has been documented that IL-6 can play key roles in induction of fibrosis and cancers. Therefore, the aim of this article is to clarify the main roles of IL-6 in stimulation of appropriate immune responses against hepatitis B virus and induction of hepatitis B-dependent cirrhosis as well as HCC.

Ferritin L is the sole serum ferritin constituent and a positive hepatic acute-phase protein

Ferritin L (FTL) and ferritin H (FTH) subunits are responsible for intracellular iron storage. Serum ferritin levels are not only dependant on body iron stores. Aims of the present study are to demonstrate nature, source, and major regulatory mediators of serum ferritin in an animal model of acute-phase (AP) response. Animals (rats, wild-type [WT] mice, and interleukin [IL]-6ko mice) were injected with turpentine oil (TO) intra-muscularity to induce a sterile abscess and sacrificed at different time points afterward. Rat hepatocytes were isolated for cell culture and, after reaching confluence, stimulated with major AP cytokines to induce AP conditions. We found a significantly increased expression of both ferritin subunits in liver at mRNA and protein levels during AP response. In the serum of both control and TO-injected rats, only FTL was detectable by Western blotting, whereas no increase in serum FTL was measured by Western blot or enzyme-linked immunosorbent assay. An increase in protein expression of FTL and FTH was observed in lysates of rat hepatocytes after treatment with IL-6, IL-1β, and tumor necrosis factor-α; however, only FTL was increasingly released into supernatant. In both TO-injected rats and WT mice, a dramatic increase in serum IL-6 levels was observed, along with an increased amount of hepatic ferritin subunits. However, an increase of hepatic FTL but not of FTH protein expression was observed in IL-6ko mice after TO injection. Our data demonstrate that FTL is the only rat serum ferritin whose release into circulation from the hepatocytes is increased by the effect of AP cytokines (e.g., IL-6). In contrast, FTH expression is intracellular in both under physiological and AP conditions.

Sustained exposure to cytokines and hypoxia enhances excitability of oxygen-sensitive type I cells in rat carotid body: correlation with the expression of HIF-1α protein and adrenomedullin

Recent studies in our laboratory demonstrated that chronic hypoxia (CH) induces a localized inflammatory response in rat carotid body that is characterized by macrophage invasion and increased expression of inflammatory cytokines. Moreover, CH-induced increased hypoxic sensitivity is blocked by concurrent treatment with the common anti-inflammatory drugs, ibuprofen and dexamethasone. The present study examines the hypothesis that selected cytokines enhance the excitability of oxygen-sensitive type I cells in the carotid body, and that downstream effects of cytokines involve upregulation of the transcription factor, hypoxia inducible factor-1α (HIF-1α). Cultured type I cells were exposed for 24 h to hypoxia and/or a cocktail of cytokines consisting of interleukin-1β, interleukin-6, and tumor necrosis factor-α. Subsequent evaluation of hypoxia-evoked intracellular Ca(2+)-responses showed that previous exposure to cytokines plus hypoxia resulted in a 110% (p<0.001) increase in cell excitability, whereas exposure to cytokines or hypoxia alone elicited smaller increases of 22% (not significant) and 35% (p<0.01), respectively. These changes were correlated with increased immunostaining for HIF-1α in similarly treated type I cells, where exposure to cytokines plus hypoxia promoted the nuclear translocation of the transcription factor. Moreover, treatment with cytokines and/or hypoxia elevated the expression of the HIF-1-regulated gene, adrenomedullin. These in vitro results are supported by studies which show that elevated type I cell sensitivity following in vivo CH is blocked by concurrent treatment with ibuprofen. The data suggest that CH-induced adaptation in arterial chemoreceptors may in part be mediated by cytokine/hypoxia-induced upregulation of HIF-1α, and consequent enhanced expression of specific hypoxia-sensitive genes in type I cells.

Spontaneous onset of nonalcoholic steatohepatitis and hepatocellular carcinoma in a mouse model of metabolic syndrome

Metabolic syndrome is a worldwide healthcare issue and a dominant risk factor for the development of incurable diseases that affect the entire body. The hepatic manifestations of this syndrome include nonalcoholic fatty liver disease (NAFLD) and its progressive variant nonalcoholic steatohepatitis (NASH). The basic pathogenesis of NAFLD/NASH remains controversial because it is difficult to clarify the disease process of NASH on the basis of metabolic syndrome alone. To determine the pathogenesis and effective treatment, an excellent animal model of NASH is required. Tsumura Suzuki obese diabetes (TSOD) male mice spontaneously develop diabetes mellitus, obesity, glucosuria, hyperglycemia, and hyperinsulinemia without any special treatments such as gene manipulation. In this study, we examined the histopathological characteristics of visceral fat and liver of 56 male TSOD mice aged 4-17 months and 9 male Tsumura Suzuki non-obesity (control) mice aged 6-12 months. In the visceral fat, enlargement of adipocytes and perivascular and pericapsular CD8-positive lymphoid aggregation were observed in 4-month-old mice. Abnormal expression of tumor necrosis factor-α, interleukin-6, and lipid peroxidation endo products was observed in macrophages. In the liver, microvesicular steatosis, hepatocellular ballooning, and Mallory bodies were observed in 4-month-old mice, with severity worsening with increasing time. These pathological findings in the liver mimic those seen in patients with NASH. Interestingly, small liver nodules with high cellularity and absence of portal tracts were frequently observed after 12 months. Most of them showed nuclear and structural atypia, and mimicked human hepatocellular carcinoma. The degree of steatosis in the non-tumor portions of the liver improved when the liver nodules developed. These findings were not observed in control mice. Here, we report that TSOD male mice spontaneously developed NAFLD without any special treatment, and that these mice are a valuable model for assessing NASH and NASH carcinogenesis owing to metabolic syndrome.

Characterization of the erythropoietin/erythropoietin receptor axis in a rat model of liver damage and cholangiocarcinoma development

It has been recently shown that the biological effects of erythropoietin (EPO) are not limited to the hematopoietic compartment but, as pleiotropic glycoprotein, this hormone can exert pro-angiogenic and tissue-protective functions also in a wide range of non-hematopoietic organs. The role of EPO and the effective functionality of its receptor in solid tumors are still a controversial point of debate. In the present work we analyzed the gene expression of EPO and its cognate receptor (EpoR) in a rat model of thioacetamide-induced damage and tumor. An analysis of the EPO/EpoR axis was also performed on human cholangiocarcinoma (CC) cell lines. A progressive increase of EPO and EpoR mRNA can already be observed during the fibrotic–cirrhotic development with a peak of expression rising at tumor formation (24.7 ± 9.9-fold increase and 15.5 ± 1.1-fold increase, respectively, for the two genes). Co-localization studies by immunofluorescence revealed hepatocytes in the regenerative cirrhotic nodules (Hep Par-1⁺) and in the dysplastic bile duct cells (CK19⁺) as the major EPO producers in this specific condition. The same cell populations, together with endothelial cells, exhibited an increased expression of EpoR, although all the non-parenchymal cell populations in the liver exhibited modest basal mRNA levels. Challenging human CC cells, Mz-Cha-2, with a combination of EPO and SCF resulted in a synergistic effect on the gene expression of EPO, CyclinD1 and PCNA. This study suggests that the autocrine and paracrine release of endogenous EPO in the microenvironment may contribute to the development and maintenance of the CC possibly in cooperation with other signaling pathways.

Ferroportin-1 is a 'nuclear'-negative acute-phase protein in rat liver: a comparison with other iron-transport proteins

Liver is the central organ of iron metabolism. During acute-phase-response (APR), serum iron concentration rapidly decreases. The current study aimed to compare expression and localization of iron transport protein ferroportin-1 (Fpn-1) and of other iron import proteins after experimental tissue damage induced by injecting turpentine oil in the hind limbs of rats and mice. Serum and spleen iron concentration decreased with an increase in total liver, cytoplasmic and nuclear iron concentration. In liver, mRNA amount of Fpn-1, Fpn-1a, Fpn-1b, HFE, hemojuvelin (HJV) and hephaestin (heph) genes showed a rapid decrease. Hepcidin, divalent metal transporter-1 (DMT-1), transferrin (Tf) and Tf-receptor-1 (TfR1), TfR-2 (TfR2) gene expression was increased. Western blot analysis of liver tissue lysate confirmed the changes observed at mRNA level. In spleen, a rapid decrease in gene expression of Fpn-1, Fpn-1a, Fpn-1b, DMT-1, Tf, TfR1 and TfR2, and an increase in hepcidin was observed. Immunohistochemistry of DMT-1 and TfR2 were mainly detected in the nucleus of rat liver and spleen, whereas TfR1 was clearly localized in the plasma membrane. Fpn-1 was mostly found in the nuclei of liver cells, whereas in spleen, the protein was mainly detected in the cell membrane. Western blot analysis of liver fractions confirmed immunohistochemical results. In livers of wild-type mice, gene expression of Fpn-1, Fpn-1a and Fpn-1b was downregulated, whereas hepcidin gene expression was increased. In contrast, these changes were less pronounced in IL-6ko-mice. Cytokine (IL-6, IL-1b and TNF-a) treatment of rat hepatocytes showed a downregulation of Fpn-1, Fpn-1a and Fpn-1b, and upregulation of hepcidin gene expression. Moreover, western blot analysis of cell lysate of IL-6-treated hepatocytes detected, as expected, an increase of a2-macroglobulin (positive acute-phase protein), whereas albumin (negative acute-phase protein) and Fpn-1 were downregulated. Our results demonstrate that liver behaves as a 'sponge' for iron under acute-phase conditions, and Fpn-1 behaves as a negative acute-phase protein in rat hepatocytes mainly, but not exclusively, because of the effect of IL-6. These changes could explain iron retention in the cytoplasm and in the nucleus of hepatocytes during APR.

LIPOCALIN-2 is a major acute-phase protein in a rat and mouse model of sterile abscess

Lipocalin-2 (LCN-2) is a 25-kDa secretory protein currently used as a biomarker for renal injury and inflammation. Its source and cause of the increased serum levels are unclear. The current study compares LCN-2 gene expression with known major acute-phase proteins in the liver in a rat and mouse model of turpentine oil-induced sterile abscess. Serum LCN-2 concentrations increased dramatically up to 200-fold (20 μg/mL) at 48 h after turpentine oil injection. A strong elevation of LCN-2 mRNA in rat liver was observed starting from 4 h up to 48 h after injection, with a maximum (8,738 ± 2,104-fold) at 24 h, which was further confirmed by Western blot analysis. In contrast, the increases in gene expression of α₂-macroglobulin, the major acute-phase protein, and hemoxygenase 1, a positive acute-phase protein, were only 1,025 ± 505-fold and 47 ± 12-fold, respectively, during acute-phase reaction (APR). No considerable change was observed in LCN-2 mRNA in rat kidney and other organs as compared with liver. Using wild-type mice, a massive increase in gene expression of LCN-2, with a maximum of 2,498 ± 84-fold in liver, which is similar to that for serum amyloid A (2,825 ± 233-fold), a major mouse acute-phase protein. However, such an increase was significantly inhibited in interleukin 6 knockout mice during APR. Interleukin 6-treated rat hepatocytes induced a significant time-dependent upregulation of LCN-2.Lipocalin-2 is the major acute-phase protein in rat as compared with α₂-macroglobulin and hemoxygenase 1 and comparable with serum amyloid A in mouse whose gene expression is mainly controlled by interleukin 6. The liver is the main source of serum LCN-2 in the case of APR. ABBREVIATIONS-LCN-2-lipocalin-2-α₂M-α₂-macroglobulin-HO-1-hemoxygenase 1-IL-6-interleukin 6-SAA-serum amyloid A-TO-turpentine oil-APR-acute-phase reaction.

Functional regulation of HIF-1α under normoxia--is there more than post-translational regulation?

The hypoxia-inducible factor-1 (HIF-1) is an oxygen-regulated transcriptional activator playing a pivotal role in mammalian physiology and disease pathogenesis, e.g., HIF-1 is indispensable in a broad range of developmental stages in different tumors. Its post-translational regulation via PHDs under the influence of hypoxia is widely investigated and accepted. Different non-hypoxic stimuli such as lipopolysaccharides (LPS), thrombin, and angiotensin II (Ang II), have been proven to enhance HIF-1 levels through activation of regulative mechanisms distinct from protein stabilization. Some of these stimuli specifically regulate HIF-1α at the transcriptional, post-transcriptional, or translational level, whereas others additionally influence post-translational modifications. Thus, it is difficult for the investigators to discern the impact of the different mechanisms leading to functional HIF-1 protein. Nevertheless, profound knowledge of additional regulatory networks appears to depict new therapeutic opportunities and thus is an interesting and important field for further investigations.

Melanocortin receptors in rat liver cells: change of gene expression and intracellular localization during acute-phase response

MCRs are known to be expressed predominantly in the brain where they mediate metabolic and anti-inflammatory functions. Leptin plays an important role in appetite and energy regulation via signaling through melanocortin receptors (MCRs) in the brain. As serum levels of MCR ligands are elevated in a clinical situation [acute-phase response (APR)] to tissue damage, where the liver is responsible for the metabolic changes, we studied hepatic gene expression of MCRs in a model of muscle tissue damage induced by turpentine oil (TO) injection in rats. A significant increase in gene expression of all five MCRs (MC4R was the highest) in liver at the RNA and protein level was detected after TO injection. A similar pattern of increase was also found in the brain. Immunohistology showed MC4R in the cytoplasm, but also in the nucleus of parenchymal and non-parenchymal liver cells, whereas MC3R-positivity was mainly cytoplasmic. A time-dependent migration of MC4R protein from the cytoplasm into the nucleus was observed during APR, in parallel with an increase in α-MSH and leptin serum levels. An increase of MC4R was detected at the protein level in wild-type mice, while such an increase was not observed in IL-6ko mice during APR. Moreover, treatment of isolated liver cells with melanocortin agonists (α-MSH and THIQ) inhibited the endotoxin-induced upregulation of the acute-phase cytokine (IL-6, IL1β and TNF-α) gene expression in Kupffer cells and of chemokine gene expression in hepatocytes. MCRs are expressed not only in the brain, but also in liver cells and their gene expression in liver and brain tissue is upregulated during APR. Due to the presence of specific ligands in the serum, they may mediate metabolic changes and exert a protective effect on liver cells.

The pleiotropic effects of erythropoietin in infection and inflammation

Erythropoietin (EPO) is a multi-functional cytokine, which exerts erythropoietic effects but also carries anti-apoptotic and immune-modulatory activities upon binding to two distinct receptors which are expressed on erythroid, parenchymal and immune cells, respectively. Whereas EPO ameliorates hemolytic anemia in malaria or trypanosomiasis and improves the course of autoimmune diseases such as inflammatory bowel disease or autoimmune encephalomyelitis, it deleteriously inhibits macrophage functions in Salmonella infection in animal models. Thus, the specific modulation of extra-erythropoietic EPO activity forms an attractive therapeutic target in infection and inflammation.

Changes of hepatic lactoferrin gene expression in two mouse models of the acute phase reaction

Lactoferrin (Ltf), an iron binding glycoprotein, is a pleiotropic molecule whose serum concentration increases under acute phase conditions. The physiological roles of this protein have been well elucidated, but the source and serum regulation of Ltf gene expression have not been investigated in detail as part of the acute phase reaction (APR). In the current work, the changes in hepatic Ltf-gene-expression during turpentine oil- (TO-) or LPS-induced APR were investigated. Ltf was upregulated at both the mRNA and protein levels in the liver of TO- and LPS-treated wild type (WT) mice. The pattern of induction however was different in both animal models indicating distinctive signalling patterns resulting in an acute phase reaction. Cytokines are the core regulators of APR. Among the major cytokines, IL-6 is an important signalling molecule, which also regulates iron homeostasis in response to an inflammatory situation. In this study, the administration of IL-6 induced Ltf gene expression in the liver of WT mice, in murine hepatocytes and in hepa 1-6 cells. Ltf-gene-expression was upregulated also in the liver of TO- and LPS-treated IL-6 knockout (KO) mice. The increase in serum Ltf after LPS injection was greater than after TO-injection both in WT and IL-6-KO mice. To evaluate the contribution of other acute phase cytokines in the regulation of Ltf-gene-expression in the liver, both in vitro and in vivo studies with IL-1β, TNF-α, or IFN-γ were performed. The results demonstrate that TNF-α and IFN-γ also upregulated Ltf-gene-expression, while IL-1β has no role in the regulation of Ltf-gene-expression.

Erythropoietin increases survival and attenuates fulminant hepatic failure injury induced by D-galactosamine/lipopolysaccharide in mice

BACKGROUND

Liver transplantation is the only therapy of proven benefit in fulminant hepatic failure (FHF). Lipopolysaccharide (LPS), d-galactosamine (GalN)-induced FHF is a well-established model of liver injury in mice. Erythropoietin has a powerful tissue-protective effect in animal models. The aim of this study was to investigate the effect and mechanism of recombinant human erythropoietin (rhEPO) administration in FHF mice.

METHODS

C57BL/6 (n=42) mice were studied in vivo in a fulminant model induced by GalN/LPS. rhEPO was administered 30 min after the induction of FHF. Serum liver enzymes and hepatic tumor necrosis factor (TNF)-α and interleukin (IL)-1β levels were determined. Histologic analysis was performed, and apoptotic cells were identified by immunohistochemistry for caspase-3. Nuclear factor (NF)-κB and c-Jun-N-terminal kinase (JNK) activation were studied using Western blot analysis.

RESULTS

After the induction of FHF, all control mice died within 12 hr of GalN/LPS administration. However, 83% of mice that were administered rhEPO were alive 2 weeks later, and overall survival improved (Kaplan-Meier, P<0.001). The serum liver enzymes, hepatic TNF-α and IL-1β levels, liver histologic injury, and apoptotic hepatocytes were significantly reduced in FHF mice that were administered rhEPO compared with untreated mice. A significant decrease in hepatic NF-κB and JNK activation was noted in FHF rhEPO-treated mice compared with FHF untreated mice.

CONCLUSIONS

The administration of rhEPO brought about increased survival and attenuation of the hepatic injury. This was associated with decreased hepatic NF-κB and JNK activation and thus TNF-α and IL-1β levels. These findings have important implications for the potential use of rhEPO in FHF.

Prognostic significance of erythropoietin in pancreatic adenocarcinoma

BACKGROUND

Erythropoietin (Epo) administration has been reported to have tumor-promoting effects in anemic cancer patients. We investigated the prognostic impact of endogenous Epo in patients with pancreatic ductal adenocarcinoma (PDAC).

METHODOLOGY

The clinico-pathological relevance of hemoglobin (Hb, n = 150), serum Epo (sEpo, n = 87) and tissue expression of Epo/Epo receptor (EpoR, n = 104) was analyzed in patients with PDAC. Epo/EpoR expression, signaling, growth, invasion and chemoresistance were studied in Epo-exposed PDAC cell lines.

RESULTS

Compared to donors, median preoperative Hb levels were reduced by 15% in both chronic pancreatitis (CP, p<0.05) and PDAC (p<0.001), reaching anemic grade in one third of patients. While inversely correlating to Hb (r = -0.46), 95% of sEPO values lay within the normal range. The individual levels of compensation were adequate in CP (observed to predicted ratio, O/P = 0.99) but not in PDAC (O/P = 0.85). Strikingly, lower sEPO values yielding inadequate Epo responses were prominent in non-metastatic M0-patients, whereas these parameters were restored in metastatic M1-group (8 vs. 13 mU/mL; O/P = 0.82 vs. 0.96; p<0.01)--although Hb levels and the prevalence of anemia were comparable. Higher sEpo values (upper quartile ≥ 16 mU/ml) were not significantly different in M0 (20%) and M1 (30%) groups, but were an independent prognostic factor for shorter survival (HR 2.20, 10 vs. 17 months, p<0.05). The pattern of Epo expression in pancreas and liver suggested ectopic release of Epo by capillaries/vasa vasorum and hepatocytes, regulated by but not emanating from tumor cells. Epo could initiate PI3K/Akt signaling via EpoR in PDAC cells but failed to alter their functions, probably due to co-expression of the soluble EpoR isoform, known to antagonize Epo.

CONCLUSION/SIGNIFICANCE

Higher sEPO levels counteract anemia but worsen outcome in PDAC patients. Further trials are required to clarify how overcoming a sEPO threshold ≥16 mU/ml by endogenous or exogenous means may predispose to or promote metastatic progression.

Hemoglobin, erythropoietin and systemic inflammation in exacerbations of chronic obstructive pulmonary disease

BACKGROUND

Systemic inflammation may represent a possible cause of anemia. Previous data support that anemic patients with COPD present high erythropoietin (EPO) levels, suggestive of EPO resistance, possibly mediated through inflammatory mechanisms.

OBJECTIVES

We aimed to determine whether systemic inflammation, which is usually up-regulated during exacerbations of COPD (ECOPD) is associated with low hemoglobin levels expressing erythropoietin resistance.

METHODS

Hemoglobin (Hb), EPO and serum biomarkers of systemic inflammation [CRP, TNF-α, fibrinogen and IL-6] were assessed at three time points (admission, resolution and stable phases) in a selected cohort of 93 COPD patients.

RESULTS

Hemoglobin levels were significantly lower on admission compared to resolution and stable phases (median 12.1 g/dl [interquartile ranges 11.2-12.7], vs 13.5 [12.4-14.3] vs 13.4 [12.7-14.08], respectively p=0.002), whereas EPO was significantly higher on admission compared to resolution and stable phases. A negative association between Hb and IL-6 and a positive association between EPO and IL-6 were observed only during the acute phase of exacerbation. EPO and Hb were negatively associated during the acute phase, whereas they were positively associated during discharge and stable phase.

CONCLUSIONS

In this observational study we have shown that during admission for ECOPD Hb levels are decreased and EPO levels are increased. We have also identified a negative association between Hb and EPO. The above association is mainly related to increased IL-6 levels, indicating a possible EPO resistance through the mechanism of increased systemic inflammatory process.