Identification and expression of iron regulators in human synovium: evidence for upregulation in haemophilic arthropathy compared to rheumatoid arthritis, osteoarthritis, and healthy controls.

Recurrent joint bleeding is the most common manifestation of severe haemophilia resulting in haemophilic arthropathy (HA). Iron plays a central role in the pathogenesis of the two main features of HA: synovitis and cartilage destruction. The aim of this study was to investigate the synovial presence of the iron regulator proteins ferroportin (FPN), hepcidin, haemoglobin scavenger receptor CD163 (CD163), feline leukaemia virus subgroup C (FLVCR), and heme carrier protein 1 (HCP-1). A comparison of the expression in HA with rheumatoid arthritis (RA), osteoarthritis (OA), and healthy controls (HC) is made. Synovial expression of iron regulators was investigated by immunohistochemistry in human synovial tissue and in a murine haemophilia model. We demonstrate for the first time the synovial presence of the investigated iron regulator proteins. Expression of the iron regulator proteins FPN, CD163, FLVCR, and HCP-1 was enhanced in HA in comparison to RA, OA, and HC synovium. In addition, in a murine haemophilia model of acute joint bleeding, synovial expression of FPN, CD163, and HCP-1 was increased. In both human and murine experiment, synovial expression of hepcidin was not altered. These findings indicate the presence of iron regulator proteins in the synovium, demonstrate an enhanced expression of FPN, CD163, FLVCR, and HCP-1 in HA, and suggest a synovial adaptation mechanism to maintain synovial iron homeostasis in HA.

Iron enhances endothelial cell activation in response to Cytomegalovirus or Chlamydia pneumoniae infection.

BACKGROUND: Chronic inflammation has been implemented in the pathogenesis of inflammatory diseases like atherosclerosis. Several pathogens like Chlamydia pneumoniae (Cp) and cytomegalovirus (CMV) result in inflammation and thereby are potentially artherogenic. Those infections could trigger endothelial activation, the starting point of the atherogenic inflammatory cascade. Considering the role of iron in a wide range of infection processes, the presence of iron may complicate infection-mediated endothelial activation. MATERIALS AND METHODS: Endothelial intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1) and endothelial selectin (E-selectin) expression were measured using flow cytometry, as an indication of endothelial activation. Cytotoxicity was monitored using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Immunostaining was applied to measure Cp and CMV infectivity to endothelial cells. RESULTS: An increased number of infected endothelial cells in a monolayer population leads to a raised expression of adhesion molecules of the whole cell population, suggesting paracrine interactions. Iron additively up-regulated Cp-induced VCAM-1 expression, whereas synergistically potentiated Cp-induced ICAM-1 expression. Together with CMV, iron also enhanced ICAM-1 and VCAM-1 expression. These iron effects were observed without modulation of the initial infectivity of both microorganisms. Moreover, the effects of iron could be reversed by intracellular iron chelation or radical scavenging, conforming modulating effects of iron on endothelial activation after infections. CONCLUSIONS: Endothelial response towards chronic infections depends on intracellular iron levels. Iron status in populations positive for Cp or CMV infections should be considered as a potential determinant for the development of atherosclerosis.

Effects of rosuvastatin on postprandial leukocytes in mildly hyperlipidemic patients with premature coronary sclerosis.

We investigated whether pro-inflammatory aspects of the postprandial phase can be modulated by rosuvastatin in premature coronary artery disease (CAD) patients. Herefore standardized 8 h oral fat loading tests were performed off-treatment and after rosuvastatin 40 mg/d in 20 male CAD patients (50 +/- 4 years). The expression of leukocyte activation markers CD11a, CD11b, CD62L and CD66b was studied using flowcytometry. Migration of isolated neutrophils towards chemoattractants was determined in a fluorescence-based assay. Rosuvastatin did not affect baseline leukocyte counts nor the postprandial neutrophil increment (maximum mean increase +10% pre- and +14% post-treatment, P < 0.01 for each). Rosuvastatin reduced baseline platelets (from 266 +/- 78 to 225 +/- 74 x 10(9) cells/L, P < 0.001) and blunted the postprandial platelet count change (maximum mean increase +6%, P = 0.01, and 0%, respectively). The baseline expression of CD11a, CD11b and CD62L increased on most types of leukocytes by rosuvastatin, whereas the postprandial responses were unaffected. Pretreatment, postprandial neutrophil migration increased dose-dependently, but there were no postprandial changes after rosuvastatin. The latter effect was unrelated to changes in lipoprotein concentrations. In conclusion, in CAD patients postprandial pro-inflammatory and pro-coagulant changes can be modified by rosuvastatin. These apparently lipid-lowering independent effects may render protection against atherosclerosis.

Postprandial leukocyte increase in healthy subjects.

Atherosclerosis is an inflammatory disorder involving leukocytes and lipids. To study the relationship between leukocytes and lipids in vivo, leukocyte changes were determined in 14 healthy males (age, 23 +/- 3 years; body mass index [BMI], 21.9 +/- 1.5 kg/m(2)) after an 8-hour oral fat load (50 g/m(2)) and after water. The postprandial triglyceride (TG) increment after fat was paralleled by a leukocyte increment, due to an increase in neutrophils in the first 2 hours (142% +/- 69% higher than baseline, P =.04). Neutrophil counts did not return to baseline at the end of the test. Water ingestion did not induce significant neutrophil changes. Blood lymphocytes increased gradually in both tests (142% +/- 30% higher than baseline, P <.001 after fat, and 128% +/- 36%, P =.02 after water). The total leukocyte increment after fat ingestion was related to the postprandial TG increase (Spearman's r = 0.73, P =.003). An early postprandial, lipid-specific, neutrophil increment is a new characteristic of the postprandial phase. Future studies will elucidate the role of postprandial leukocyte changes in the pathogenesis of atherosclerosis.

Iron chelation and hydroxyl radical scavenging reduce the inflammatory response of endothelial cells after infection with Chlamydia pneumoniae or influenza A.

BACKGROUND: Chronic low-grade inflammation is associated with increased risk of vascular diseases. The source of inflammation is unknown but may well be chronic and/or repetitive infections with microorganisms. Direct infection of endothelial cells (ECs) may also be a starting point for atherogenesis by initiating endothelial procoagulant activity, increased monocyte adherence and increased cytokine production. We hypothesized that iron-mediated intracellular hydroxyl radical formation after infection is a key event in triggering the production of interleukin-6 (IL-6) by ECs in vitro. METHODS: Cultured ECs were incubated with Fe(II) and Fe(III) or infected with Chlamydia pneumoniae or influenza A/H1N1/Taiwan/1/81 for 48 and 24 h, respectively. To determine the role of iron and reactive oxygen species, cells were coincubated with the H2O2 scavenger N-acetyl-l-cysteine, with the iron chelator deferoxamine (DFO) or with the intracellular hydroxyl radical scavenger dimethylthiourea (DMTU). After the incubation periods, supernatants were harvested for IL-6 determination. RESULTS: Incubating ECs with Fe(II) and Fe(III) resulted in increased IL-6 production. Similarly, infection with C. pneumoniae and influenza A also induced an IL-6 response. Coincubating ECs with DFO or DMTU blocked this response. Nuclear factor-kappaB activity was increased after infection and blocked by coincubation with DFO or DMTU. CONCLUSION: Cultured ECs respond to infection and iron incubation with increased production of IL-6. Iron, the generation of intracellular hydroxyl radical and NF-kappaB activity are essential in cellular activation, suggesting that reactive oxygen species generated in the Haber-Weiss reaction are essential in invoking an immunological response to infection by ECs.

Human immunodeficiency virus type 1 replication inhibition by the bidentate iron chelators CP502 and CP511 is caused by proliferation inhibition and the onset of apoptosis.

BACKGROUND: The iron chelators deferoxamine (DF) and deferiprone (CP20) have been shown to inhibit human immunodeficiency virus type 1 (HIV-1) replication in human peripheral blood lymphocytes (PBL). The orally active bidentate chelators CP502 and CP511, which also belong to the 3-hydroxypyridin-4-one family, but with higher affinities for iron than CP20, were monitored for their antiviral properties by checking for p24 antigen production and nuclear factor (NF)-kappaB activation, and their ability to induce apoptosis. MATERIALS AND METHODS: Human PBLs were isolated from HIV-1 seronegative donors and subsequently infected with HIV-1(Ba-L) for 2 h. After 5 days' incubation, HIV-1 replication was monitored by p24 antigen production. Cellular proliferation as well as caspase-3 activity were monitored in uninfected cells after a period of 5 days and after 1 day infection, respectively. NF-kappaB activity was also monitored by electromobility shift assays (EMSA) performed on nuclear extracts of Jurkat cells treated with the different chelators for 4 h. RESULTS: CP502 and CP511 decrease HIV-1 replication by decreasing cellular proliferation in a similar manner to DF and CP20. CP511 seemed to be more potent than either CP502 or CP20. Due to the reduction in cellular proliferation, there was an increase in caspase-3 activity after 24 h incubation. NF-kappaB activity was not affected by any of the chelators. CONCLUSIONS: Iron chelators with high affinities for iron, which are under development for the treatment of iron overload, could contribute to the reduction of HIV-1 replication in infected patients by cellular proliferation inhibition rather than by a direct antiviral action.

The chemotherapeutic agent bleomycin in a two-drug combination with zidovudine, ritonavir or indinavir synergistically inhibits HIV Type-1 replication in peripheral blood lymphocytes.

It has been suggested that the combination of cancer chemotherapy with antiviral therapy is helpful for the containment of lymphomas in HIV-infected patients. Since we have recently shown that the nucleic acid binding chemotherapeutic agent bleomycin in itself has antiviral properties, we looked to see if there was any possible synergy with current anti-HIV agents. Combinations of zidovudine, indinavir or ritonavir with bleomycin, synergistically inhibited HIV-1(AT) replication in stimulated peripheral blood lymphocytes (combination index at 50% virus inhibition was 0.427, 0.604 and 0.535, respectively) and this synergism was not accompanied by any synergistic effects on cytotoxicity. We conclude from these data that further studies to investigate the clinical efficacy of combinations of antiviral and cancer chemotherapeutic agents are warranted in relation to viral load improvement.

Chemiluminescence in inflammatory bowel disease patients: a parameter of inflammatory activity.

BACKGROUND: Reactive oxygen species (ROS) are produced in excess in the inflamed mucosa and peripheral blood of patients with inflammatory bowel disease. These species have emerged as a common pathway of tissue injury in a wide variety of inflammatory and other disease processes. The present study was conducted to assess ROS production and to correlate this with parameters of inflammatory activity. METHODS: In 25 patients with Crohn's disease (CD), 20 patients with ulcerative colitis (UC) and 65 age- and sex-matched healthy volunteers ROS production was measured using the whole blood luminol enhanced chemiluminescence assay (LECA). Disease activity was assessed using the Crohn's disease activity index and the Ulcerative Colitis Symptoms Score (UCSS) for CD and UC, respectively. Furthermore, the effect of various scavengers, enzymes and enzyme inhibitors on LECA was studied to assess the contribution of different ROS. RESULTS: LECA was significantly higher in CD and UC patients compared with healthy controls (7.1+/-4.7 and 9.8+/-6 vs. 5.2+/-2.8 x 10(3) counts per minute (cpm), p<0.05 and <0.001). In CD, relative LECA (patient/control) was correlated with the Crohn's disease activity index and C-reactive protein (CRP) (r=0.54, p=0.001 and r=0.51, p=0.01). In UC, CRP but not LECA was correlated with the Ulcerative Colitis Symptoms Score (C-reactive protein: r=0.42, p=0.01). Addition of azide, superoxide dismutase, deferoxamine and dimethylthiourea resulted in a decrease of LECA values. CONCLUSION: Whole blood LECA is increased in patients with CD and UC. This parameter is correlated with disease activity in CD. The observed chemiluminescence is probably due to generation of superoxide and the hydroxyl radical.

Glutathione and alpha-lipoate in diabetic rats: nerve function, blood flow and oxidative state.

BACKGROUND: Increased oxidative stress is considered to be a causal factor in the development of diabetic complications, among which peripheral neuropathy. The pathophysiology of nerve dysfunction in diabetes has been explained both by reduced endoneurial microcirculation and alterations in endoneurial metabolism. It is unclear whether antioxidants primarily improve nerve blood flow or normalise systemic or endoneurial oxidative metabolism. Therefore, we evaluated the effects of the antioxidants glutathione and alpha-lipoic acid on both nerve microcirculation and the antioxidative capacity and lipid peroxidation in experimentally diabetic rats. MATERIALS AND METHODS: Streptozotocin-diabetic rats were treated with different doses of alpha-lipoic acid, reduced glutathione or placebo, and were compared with nondiabetic controls. We measured systemic and endoneurial antioxidants, malondialdehyde and whole blood hydrogen peroxide. Furthermore, we evaluated sciatic and tibial motor and sensory nerve conduction velocity, caudal nerve conduction velocity, and assessed sciatic nerve blood flow and vascular resistance by Laser-Doppler flowmetry. RESULTS: We observed a rise in erythrocyte glutathione by 27 % (P < 0.05), and a trend towards decreased plasma malondialdehyde in alpha-lipoic acid, but not in glutathione-treated animals in comparison with the placebo group. Simultaneously, sciatic nerve blood flow and vascular resistance were improved by daily alpha-lipoic acid administration by 38% (P < 0.05). Peripheral nerve conduction velocity and endoneurial glutathione were not significantly influenced by antioxidant treatment. CONCLUSIONS: Only minor beneficial effects of alpha-lipoic acid on nerve blood flow and oxidative state occur at the given doses; these effects were insufficient to improve nerve conduction deficits.

Effect of corticosteroids on nuclear factor-kappaB activation and hemodynamics in late septic shock.

OBJECTIVE: To describe the underlying pathophysiologic mechanisms of the effect of corticosteroids in a patient with late septic shock. DESIGN: Case report. SETTING: The medical intensive care unit at University Medical Center Utrecht. PATIENT: An 86-yr-old female patient with late septic shock requiring mechanical ventilation and vasopressive agents. INTERVENTIONS: Administration of hydrocortisone, 300 mg daily. MEASUREMENTS AND MAIN RESULTS: Within 3 days of corticosteroid treatment, the patient could be weaned of vasopressive agents and mechanical ventilation. Serum C-reactive protein levels normalized. Nuclear factor-kappaB activation in unstimulated and in vitro lipopolysaccharide-stimulated peripheral blood mononuclear cells decreased to background level within 5 days. Repeated functional tests of the hypothalamic-pituitary-adrenal axis were normal. CONCLUSION: Our data suggest that the pathophysiologic mechanism behind the clinical effects of supraphysiologic doses of corticosteroids in late septic shock is directly related to the inhibition of nuclear factor-kappaB in peripheral blood mononuclear cells.

Iron and inflammatory bowel disease.

Both anaemia of iron deficiency and anaemia of chronic disease are frequently encountered in inflammatory bowel disease. Anaemia of iron deficiency is mostly due to inadequate intake or loss of iron. Anaemia of chronic disease probably results from decreased erythropoiesis, secondary to increased levels of proinflammatory cytokines, reactive oxygen metabolites and nitric oxide. Assessment of the iron status in a condition associated with inflammation, such as inflammatory bowel disease, is difficult. The combination of serum transferrin receptor with ferritin concentrations, however, allows a reliable assessment of the iron deficit. The best treatment for anaemia of chronic disease is the cure of the underlying disease. Erythropoietin reportedly may increase haemoglobin levels in some of these patients. The anaemia of iron deficiency is usually treated with oral iron supplements. Iron supplementation may lead to an increased inflammatory activity through the generation of reactive oxygen species. To date, data from studies in animal models of inflammatory bowel disease support the theoretical disadvantage of iron supplementation in this respect. The results, however, cannot easily be extrapolated to the human situation, because the amount of supplemented iron in these experiments was much higher than the dose used in patients with iron deficiency.

Anti-HIV effect of iron chelators: different mechanisms involved.

BACKGROUND: Drugs for the treatment of AIDS have been directed to specific events in the human immunodeficiency virus (HIV-1) life cycle, aimed to stop viral replication by inhibition of reverse transcriptase or protease activity. Studies showing that oxidative stress and iron may be important in the activation of HIV-1 have focused attention on the potential therapeutic use of iron chelators. OBJECTIVES: The goal of this review is to describe several possibilities as to how iron is involved in the replication of HIV and how iron chelation may interfere in this process. STUDY DESIGN: First some physico-chemical properties of iron concerning solubility, oxidation-reduction potential, catalysis, and chelation will be discussed. In the second part, the role of iron in various biochemical systems is explained. RESULTS: Nuclear factor kappa B (NF-kappaB) activation, regulating proviral transcription, can be influenced by iron through the production of reactive oxygen species. A second route by which iron chelation could influence HIV replication, is by inhibition of DNA synthesis through inactivation of iron-dependent ribonucleotide reductase. Another strategy which can be employed in targeting iron chelators against HIV-1, is direct oxidative viral RNA/DNA attack. This could be achieved by bleomycin, a cytostatic agent with the ability to form a complex with DNA and RNA. CONCLUSION: Chelation may withhold iron from viral metabolism but on the other hand may also favor catalysis of reactive oxygen species directed to viral constituents. In combination with existing antivirals, iron chelation could add to improve the treatment of HIV-disease.

Iron supplementation affects the production of pro-inflammatory cytokines in IL-10 deficient mice.

BACKGROUND: Iron supplements may increase disease activity in inflammatory bowel disease through the production of the hydroxyl radical because of its catalytic activity in the Fenton reaction. The purpose of this study was to assess the effect of dietary and locally administered iron in the IL-10 knock-out (-/-) mouse, a model of chronic inflammatory bowel disease. MATERIALS AND METHODS: IL10-/- and wild-type mice received a standard or a high-iron diet (35 mg kg(-1) ferrosulphate vs. 500 mg kg(-1) ferrosulphate) after weaning. After 4 weeks the mice were sacrificed. Furthermore, a group of adult IL-10 knock-out mice was given three iron-containing enema's (0.2 mL of 1 mM ferrous-ammonium sulphate) or phosphate buffered saline. These mice were sacrificed after 1 week. Production of pro-inflammatory cytokines by colon tissue cultures, haematological parameters and histology was determined to assess inflammatory activity. RESULTS: Oral as well as rectal administration of iron resulted in increased pro-inflammatory cytokine production in IL-10-/- mice. Neutrophil counts in IL10-/- on a high iron diet increased as well. No enhanced colonic inflammation was noted on histology after iron supplementation. CONCLUSION: We conclude that dietary or topical administered iron increases pro-inflammatory cytokine production in the colon of IL10-/- mice. No significant increase of histological intestinal inflammation was observed.

Pressure-induced skin lesions in pigs: reperfusion injury and the effects of vitamin E.

The pathogenesis of the development of pressure ulcers is still unclear. The aim of this study was to investigate the role of ischaemia and reperfusion in pressure-induced tissue necrosis in the trochanteric region in pigs. Pressure application was achieved with a newly developed computer-controlled pressure device. Histological examination showed damage in the subcutis and muscle tissue comparable with inflammation, extending in a vascular pattern beyond the area of pressure application. Electron-microscopic studies revealed neutrophil adherence to the capillary endothelium, which showed signs of injury. These observations were manifest two hours after the cessation of pressure. Pre-treatment with 500 mg vitamin E per day resulted in significantly less tissue damage compared with untreated animals. Pressure alone caused a significant decrease in reduced glutathione and total glutathione, suggesting oxidative stress. After pressure release there was a significant increase in hydrogen peroxide concentration, suggesting a decreased antioxidant protection. After pre-treatment with vitamin E, however, there was no increase of hydrogen peroxide. It is concluded that the early signs of necrosis after pressure application are concordant with typical ischaemia-reperfusion damage and this can be prevented in part by treatment with vitamin E. Prophylactic administration of vitamin E may influence the occurrence of pressure ulcers in humans undergoing elective surgery.

Inhibition of human immunodeficiency virus type 1 replication in human mononuclear blood cells by the iron chelators deferoxamine, deferiprone, and bleomycin.

Replication of human immunodeficiency virus type 1 (HIV-1) can be influenced by iron. Hence, decreasing the availability of iron may inhibit HIV-1 replication. Deferoxamine and deferiprone, both forming catalytically inactive iron-chelator complexes, and bleomycin, by use of which iron catalyzes oxidative nucleic acid destruction, were investigated. Expression of p24 antigen in human monocyte-derived macrophages and peripheral blood lymphocytes (PBL) was reduced by all 3 iron chelators. In PBL, p24 reduction was mirrored by a decrease in proliferation after incubation with deferoxamine or deferiprone, suggesting that viral inhibition is closely linked to a decrease in cellular proliferation. In contrast, clinically relevant bleomycin concentrations reduced p24 levels by approximately 50% without affecting proliferation. When deferoxamine and the nucleoside analogue dideoxyinosine were used in combination, they acted synergistically in inhibiting HIV-1 replication. These observations suggest that iron chelators with different mechanisms of action could be of additional benefit in antiretroviral combination therapy.

Potential role of CCR5 polymorphism in the development of AIDS dementia complex.

The chemokine receptor CCR5 and to a lesser extent CCR2b and CCR3 have been shown to serve as coreceptors for HIV-1 entry into macrophages. Individuals that are homozygous for a defective CCR5 allele (DeltaCCR5) are highly, but not fully, resistant to infection with HIV-1. Here, we want to emphasize the importance of DeltaCCR5 in in vitro as well as in vivo studies. We provide data that suggest that CCR5 polymorphism may affect the onset of AIDS dementia complex in vivo and data that show that HIV-1 replication is influenced by the DeltaCCR5 allele in vitro. Knowing the CCR5 genotype of an individual will help to better interpret research results and may even provide new information about mechanisms of disease.