Regulation of iron uptake in primary culture rat hepatocytes: the role of acute-phase cytokines. Shock. 2014;41:337-345. [PMID: 24365882 DOI: 10.1097/shk.0000000000000107]

Molecular mechanism of interleukin-17A regulating airway epithelial cell ferroptosis based on allergic asthma airway inflammation

Interleukin-17A (IL-17A) levels are elevated in patients with asthma. Ferroptosis has been identified as the non-apoptotic cell death type associated with asthma. Data regarding the relation of ferroptosis with asthma and the effect of IL-17A on modulating ferroptosis in asthma remain largely unclear. The present work focused on investigating the role of IL-17A in allergic asthma-related ferroptosis and its associated molecular mechanisms using public datasets, clinical samples, human bronchial epithelial cells, and an allergic asthma mouse model. We found that IL-17A was significantly upregulated within serum in asthma cases. Adding IL-17A significantly increased ferroptosis within human bronchial epithelial cells (BEAS-2B). In ovalbumin (OVA)-induced allergic asthmatic mice, IL-17A regulated and activated lipid peroxidation induced ferroptosis, whereas IL-17A knockdown effectively inhibited ferroptosis in vivo by protection of airway epithelial cells via the xCT-GSH-GPX4 antioxidant system and reduced airway inflammation. Mouse mRNA sequencing results indicated that the tumor necrosis factor (TNF) pathway was the differential KEGG pathway in the OVA group compared to healthy controls and the OVA group compared to the IL-17A knockout OVA group. We further used N-acetylcysteine (TNF inhibitor) to inhibit the TNF signaling pathway, which was found to protect BEAS-2B cells from IL-17A induced lipid peroxidation and ferroptosis damage. Our findings reveal a novel mechanism for the suppression of ferroptosis in airway epithelial cells, which may represent a new strategy for the use of IL-17A inhibitors against allergic asthma.

Hematological Normality, Serum Biochemistry, and Acute Phase Proteins in Healthy Beef Calves in the Brazilian Savannah

The Brazilian savannah region, characterized by high average temperatures, well-defined rainy and dry seasons, soil with low productive potential, and high pressure for parasitic diseases, is home to the highest percentage of the beef herd, which is the world's largest commercial beef producer. Therefore, breeds that present rusticity combined with productivity are the focus of research in cattle breeding in the region. Considering their geographic particularities and their effects on the animals' blood parameters, the objective was to study the behavior of hematological variables, serum biochemistry, and acute phase proteins in beef calves at weaning age. Jugular blood samples were collected in a single day from 30 weaning calves (about eight months old and 200 kg of body weight) from the following breeds: Nellore, Senepol, Nellore × Aberdeen Angus cross, Nellore × Senepol cross, and Nellore × Aberdeen Angus × Senepol cross. Hematological data were obtained using an automatic cell counter, serum biochemical measurements were obtained using commercial kits, and the electrophoretogram was obtained using the SDS-page technique. In general, the results were consistent with data already published in similar situations regarding health status, age, and level of metabolic activity. However, differences observed between groups can be explained by differences observed in other concurrent variables like temperament. The pure zebu breed was more reactive than pure taurine. While crossbreds showed intermediate values, and parasitic infestation, the pure taurine breed with higher parasite infestation, while the zebu breed had lower values, which produced effects in some laboratory tests, and generated differences between breeds. In conclusion, the reference intervals available for healthy animals can be routinely used without interference from the geographic region for animals produced without nutritional failures as long as changes are recorded in pathological, infectious, metabolic, or nutritional deficiency situations. However, it is suggested that a study covering a larger number of herds may demonstrate a greater geographic effect on the studied variables.

Iron promotes breast cancer cell migration via IL-6/JAK2/STAT3 signaling pathways in a paracrine or autocrine IL-6-rich inflammatory environment

Iron overload can act as catalyst for the formation of free radicals, which may promote oxidant-mediated breast carcinogenesis. However, the association between iron and breast cancer has not been comprehensively elucidated. In this study, we found that iron overload upregulated the inflammatory cytokine interleukin-6 (IL-6) expression to activate Janus Kinases 2/Signal Transducer and Activator of Transcription 3 (JAK2/STAT3) signaling in triple negative breast cancer (TNBC) MDA-MB-231 cell lines, resulting in epithelial-mesenchymal transition (EMT) and cancer cell migration, but it had no effects on the estrogen receptor (ER)-positive breast cancer MCF-7 cells. However, in the presence of exogenous IL-6, iron overload could also dramatically induce an autocrine IL-6 loop in ER-positive MCF-7 cells to active IL-6/JAK2/STAT3 signaling, resulting in enhanced EMT and cell motility. In vivo animal studies also identified that iron overload promoted the progression of low metastatic breast cancer tumorigenicity and lung metastasis following the addition of exogenous IL-6. This study suggested that iron overload could result in inducible IL-6 expression leading to promote malignant transformation of breast cancer cells in an paracrine or autocrine IL-6-rich inflammatory environment. Anti-inflammation and iron depletion therapy would be an effective therapeutic/preventive strategy for suppressing breast cancer progression.

Crucial role for lung iron level and regulation in the pathogenesis and severity of asthma

Accumulating evidence highlights links between iron regulation and respiratory disease. Here, we assessed the relationship between iron levels and regulatory responses in clinical and experimental asthma.We show that cell-free iron levels are reduced in the bronchoalveolar lavage (BAL) supernatant of severe or mild-moderate asthma patients and correlate with lower forced expiratory volume in 1 s (FEV₁). Conversely, iron-loaded cell numbers were increased in BAL in these patients and with lower FEV₁/forced vital capacity (FVC) ratio. The airway tissue expression of the iron sequestration molecules divalent metal transporter 1 (DMT1) and transferrin receptor 1 (TFR1) are increased in asthma, with TFR1 expression correlating with reduced lung function and increased Type-2 (T2) inflammatory responses in the airways. Furthermore, pulmonary iron levels are increased in a house dust mite (HDM)-induced model of experimental asthma in association with augmented Tfr1 expression in airway tissue, similar to human disease. We show that macrophages are the predominant source of increased Tfr1 and Tfr1⁺ macrophages have increased Il13 expression. We also show that increased iron levels induce increased pro-inflammatory cytokine and/or extracellular matrix (ECM) responses in human airway smooth muscle (ASM) cells and fibroblasts ex vivo and induce key features of asthma in vivo, including airway hyper-responsiveness (AHR) and fibrosis, and T2 inflammatory responses.Together these complementary clinical and experimental data highlight the importance of altered pulmonary iron levels and regulation in asthma, and the need for a greater focus on the role and potential therapeutic targeting of iron in the pathogenesis and severity of disease.

Immunosuppressant-Induced Oxidative Stress and Iron: A Paradigm Shift from Systemic to Intrahepatic Abnormalities

Immunosuppressants are used clinically to lower rejection rates in transplant patients. Unfortunately, the adverse side effects of these immunosuppressants can be severe, which is one of the rationales that life expectancy of individuals after transplant still significantly falls short of that of the general population. The current experimental setup was designed to analyze the tacrolimus-induced hepatic iron overload in Wistar rats. Four experimental groups were orally given 1 ml of aqueous suspension of tacrolimus (12 mg/kg) through oral gavage, and rats were sacrificed after 6, 12, 24, and 48 h of tacrolimus dose. Hepatic hepcidin expression was found to be significantly augmented along with the upregulation of Tf and TfR1, Ferritin-L, Ferritin-H, TNF-α, and HO-1 gene expression at 6 and 12 h, and downregulation of Fpn-1, Hjv, and Heph at 6 h was detected. Significant downregulation of IL-6, IFN-α, IFN-β, and IFN-γ at all study time points was also observed. Serum iron level was decreased while serum hepcidin level was found to be significantly increased. Iron staining showed blue-stained hemosiderin granules within the hepatocytes, sinusoidal spaces, and portal areas at 12 and 24 h time points and remarkable fall of iron contents in the splenic red pulp. These results suggest that the use of tacrolimus leads to the onset of an intrahepatic acute-phase response-like reaction and causes iron overload in hepatic cells by altering the expression of key proteins involved in iron metabolism.

Does Ceruloplasmin Defend Against Neurodegenerative Diseases?

Ceruloplasmin (CP) is the major copper transport protein in plasma, mainly produced by the liver. Glyco-sylphosphatidylinositol-linked CP (GPI-CP) is the predominant form expressed in astrocytes of the brain. A growing body of evidence has demonstrated that CP is an essential protein in the body with multiple functions such as regulating the home-ostasis of copper and iron ions, ferroxidase activity, oxidizing organic amines, and preventing the formation of free radicals. In addition, as an acute-phase protein, CP is induced during inflammation and infection. The fact that patients with genetic disorder aceruloplasminemia do not suffer from tissue copper deficiency, but rather from disruptions in iron metabolism shows essential roles of CP in iron metabolism rather than copper. Furthermore, abnormal metabolism of metal ions and ox-idative stress are found in other neurodegenerative diseases, such as Wilson’s disease, Alzheimer’s disease and Parkinson’s disease. Brain iron accumulation and decreased activity of CP have been shown to be associated with neurodegeneration. We hypothesize that CP may play a protective role in neurodegenerative diseases. However, whether iron accumulation is a cause or a result of neurodegeneration remains unclear. Further research on molecular mechanisms is required before a con-sensus can be reached regarding a neuroprotective role for CP in neurodegeneration. This review article summarizes the main physiological functions of CP and the current knowledge of its role in neurodegenerative diseases.

Reabsorption of iron into acutely damaged rat liver: A role for ferritins

AIM

To studied iron metabolism in liver, spleen, and serum after acute liver-damage, in relation to surrogate markers for liver-damage and repair.

METHODS

Rats received intraperitoneal injection of the hepatotoxin thioacetamide (TAA), and were sacrificed regularly between 1 and 96 h thereafter. Serum levels of transaminases and iron were measured using conventional laboratory assays. Liver tissue was used for conventional histology, immunohistology, and iron staining. The expression of acute-phase cytokines, ferritin light chain (FTL), and ferritin heavy chain (FTH) was investigated in the liver by qRT-PCR. Western blotting was used to investigate FTL and FTH in liver tissue and serum. Liver and spleen tissue was also used to determine iron concentrations.

RESULTS

After a short initial decrease, iron serum concentrations increased in parallel with serum transaminase (aspartate aminotransferase and alanine aminotransferase) levels, which reached a maximum at 48 h, and decreased thereafter. Similarly, after 48 h a significant increase in FTL, and after 72h in FTH was detected in serum. While earliest morphological signs of inflammation in liver were visible after 6 h, increased expression of the two acute-phase cytokines IFN-γ (1h) and IL-1β (3h) was detectable earlier, with maximum values after 12-24 h. Iron concentrations in liver tissue increased steadily between 1 h and 48 h, and remained high at 96 h. In contrast, spleen iron concentrations remained unchanged until 48 h, and increased mildly thereafter (96 h). Although tissue iron staining was negative, hepatic FTL and FTH protein levels were strongly elevated. Our results reveal effects on hepatic iron concentrations after direct liver injury by TAA. The increase of liver iron concentrations may be due to the uptake of a significant proportion of the metal by healthy hepatocytes, and only to a minor extent by macrophages, as spleen iron concentrations do not increase in parallel. The temporary increase of iron, FTH and transaminases in serum is obviously due to their release by damaged hepatocytes.

CONCLUSION

Increased liver iron levels may be the consequence of hepatocyte damage. Iron released into serum by damaged hepatocytes is obviously transported back and stored via ferritins.

Copper chelation and interleukin-6 proinflammatory cytokine effects on expression of different proteins involved in iron metabolism in HepG2 cell line

Background

In vertebrates, there is an intimate relationship between copper and iron homeostasis. Copper deficiency, which leads to a defect in ceruloplasmin enzymatic activity, has a strong effect on iron homeostasis resulting in cellular iron retention. Much is known about the mechanisms underlying cellular iron retention under “normal” conditions, however, less is known about the effect of copper deficiency during inflammation.

Results

We show that copper deficiency and the inflammatory cytokine interleukin-6 have different effects on the expression of proteins involved in iron and copper metabolism such as the soluble and glycosylphosphtidylinositol anchored forms of ceruloplasmin, hepcidin, ferroportin1, transferrin receptor1, divalent metal transporter1 and H-ferritin subunit. We demonstrate, using the human HepG2 cell line, that in addition to ceruloplasmin isoforms, copper deficiency affects other proteins, some posttranslationally and some at the transcriptional level. The addition of interleukin-6, moreover, has different effects on expression of ferroportin1 and ceruloplasmin, in which ferroportin1 is decreased while ceruloplasmin is increased. These effects are stronger when a copper chelating agent and IL-6 are used simultaneously.

Conclusions

These results suggest that copper chelation has effects not only on ceruloplasmin but also on other proteins involved in iron metabolism, sometimes at the mRNA level and, in inflammatory conditions, the functions of ferroportin and ceruloplasmin may be independent.

The value of acute phase reactants in predicting preterm delivery

OBJECTIVE

We aimed to determine the potential value of maternal serum levels of acute phase reactants in the prediction of preterm delivery in women with threatened preterm labor (TPL).

METHODS

Ninety-one pregnant women diagnosed with TPL and 83 healthy pregnant women as a control group were included in this prospective controlled study. All the pregnant women were followed until delivery and obstetric data and the serum levels of acute phase reactants were recorded for each participant. The study group was further divided into two groups according to the gestational age at delivery, which include women delivering prematurely and the ones who gave birth at term.

RESULTS

Serum albumin levels were significantly lower and mean serum ferritin levels were significantly higher in the study groups when compared the control group.

CONCLUSION

Although an association between decreased serum albumin level and TPL, also between increased serum ferritin levels and preterm birth and low birth weight were demonstrated, more extensive studies are needed to clarify the potential use of the acute phase reactants in the prediction of preterm birth.

Dietary fructose as a risk factor for non-alcoholic fatty liver disease (NAFLD)

Glucose is a major energy source for the entire body, while fructose metabolism occurs mainly in the liver. Fructose consumption has increased over the last decade globally and is suspected to contribute to the increased incidence of non-alcoholic fatty liver disease (NAFLD). NAFLD is a manifestation of metabolic syndrome affecting about one-third of the population worldwide and has progressive pathological potential for liver cirrhosis and cancer through non-alcoholic steatohepatitis (NASH). Here we have reviewed the possible contribution of fructose to the pathophysiology of NAFLD. We critically summarize the current findings about several regulators, and their potential mechanisms, that have been studied in humans and animal models in response to fructose exposure. A novel hypothesis on fructose-dependent perturbation of liver regeneration and metabolism is advanced. Fructose intake could affect inflammatory and metabolic processes, liver function, gut microbiota, and portal endotoxin influx. The role of the brain in controlling fructose ingestion and the subsequent development of NAFLD is highlighted. Although the importance for fructose (over)consumption for NAFLD in humans is still debated and comprehensive intervention studies are invited, understanding of how fructose intake can favor these pathological processes is crucial for the development of appropriate noninvasive diagnostic and therapeutic approaches to detect and treat these metabolic effects. Still, lifestyle modification, to lessen the consumption of fructose-containing products, and physical exercise are major measures against NAFLD. Finally, promising drugs against fructose-induced insulin resistance and hepatic dysfunction that are emerging from studies in rodents are reviewed, but need further validation in human patients.

Ceruloplasmin and other copper binding components of blood plasma and their functions: an update

We know that blood plasma contains many proteins and also other components that bind copper. The largest contributor to copper in the plasma is ceruloplasmin, which accounts for 40-70 percent. Apart from ceruloplasmin and albumin, most of these components have not been studied extensively, and even for ceruloplasmin and albumin, much remains to be discovered. New components with new functions, and new functions of known components are emerging, some warranting reconsideration of earlier findings. The author's laboratory has been actively involved in research on this topic. This review summarizes and updates our knowledge of the nature and functions of ceruloplasmin and the other known and emerging copper-containing molecules (principally proteins) in this fluid, to better understand how they contribute to copper homeostasis and consider their potential significance to health and disease.

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.

Expression of hemopexin in acute rejection of rat liver allograft identified by serum proteomic analysis

Acute rejection (AR) and acceptance of allograft after liver transplantation (LTx) remain critical issues that need addressing to improve prognosis. We therefore performed rat orthotopic LTx and proteomic analyses to screen for immune response-related biomarkers in sera. Markers identified were validated at the mRNA and/or protein levels, and the molecules of interest were functionally explored. Compared with syngeneic controls, signs of AR as well as spontaneous acceptance were observed in hematoxylin and eosin-stained sections of liver allografts. In accordance with the severity of AR, 30 protein spots displaying significant changes in abundance were identified using two-dimensional differential gel electrophoresis. Ultimately, 14 serum proteins were sequenced and five spots of interest were identified as hemopexin (HPX). Expression of HPX was significantly and inversely associated with the severity of AR at both the mRNA and protein levels. In vitro, Mt-1, Ho-1, Fth, Ifn-γ, and Il-17 transcripts were significantly upregulated in lysates of lymphocytes stimulated with HPX, whereas Il-10 markedly was remarkably downregulated. Interferon-γ, IL-10, and IL-17 proteins in the supernatant of HPX-stimulated lymphocytes were significantly altered in keeping with the mRNA level. Our data facilitated the generation of a proteomic profile to enhance the understanding of rat liver AR. In view of finding that the HPX serum level is negatively associated with the severity of AR of rat liver allograft, we propose that in vitro treatment with HPX regulates cytokine expression in rat lymphocytes.

Combination of alcohol and fructose exacerbates metabolic imbalance in terms of hepatic damage, dyslipidemia, and insulin resistance in rats

Although both alcohol and fructose are particularly steatogenic, their long-term effect in the development of a metabolic syndrome has not been studied in vivo. Consumption of fructose generally leads to obesity, whereas ethanol can induce liver damage in the absence of overweight. Here, Sprague-Dawley rats were fed ad libitum for 28 days on five diets: chow (control), liquid Lieber-DeCarli (LDC) diet, LDC +30%J of ethanol (L-Et) or fructose (L-Fr), and LDC combined with 30%J ethanol and 30%J fructose (L-EF). Body weight (BW) and liver weight (LW) were measured. Blood and liver samples were harvested and subjected to biochemical tests, histopathological examinations, and RT-PCR. Alcohol-containing diets substantially reduced the food intake and BW (≤3^rd week), whereas fructose-fed animals had higher LW than controls (P<0.05). Additionally, leukocytes, plasma AST and leptin levels were the highest in the fructose-administered rats. Compared to the chow and LDC diets, the L-EF diet significantly elevated blood glucose, insulin, and total-cholesterol levels (also vs. the L-Et group). The albumin and Quick-test levels were the lowest, whereas ALT activity was the highest in the L-EF group. Moreover, the L-EF diet aggravated plasma triglyceride and reduced HDL-cholesterol levels more than 2.7-fold compared to the sum of the effects of the L-Et and L-Fr diets. The decreased hepatic insulin clearance in the L-EF group vs. control and LDC groups was reflected by a significantly decreased C-peptide:insulin ratio. All diets except the control caused hepatosteatosis, as evidenced by Nile red and H&E staining. Hepatic transcription of insulin receptor substrate-1/2 was mainly suppressed by the L-Fr and L-EF diets. The L-EF diet did not enhance the mitochondrial β-oxidation of fatty acids (Cpt1α and Ppar-α expressions) compared to the L-Et or L-Fr diet. Together, our data provide evidence for the coaction of ethanol and fructose with a high-fat-diet on dyslipidemia and insulin resistance-accompanied liver damage.