[Effects of plasma Hcy on the contents of CO and HO-2 in the corpus cavernosum of ED rats with hyperhomocysteinemia]

OBJECTIVE

To study the changes in the activities of carbon monoxide (CO) and heme oxygenase 2 (HO-2) in ED rats with hyperhomocysteinemia (HHcy).

METHODS

This study included 40 male Wistar rats weighing 280 - 310 g, 10 as normal controls (group A). HHcy models were made in the other 30 by giving 3% methionine for 4 weeks, and then divided into groups B, C and D. The rats in group B continued to be fed with 3% methionine, those in group C were treated with betaine hydrochloride, and those in group D were given zinc porphyrin IX at 45 micromol per kg per d. Penile erections of the rats were recorded, and 4 weeks later, all were killed for determination of the levels of homocysteine (Hcy) in the blood plasma and the activities of CO and HO-2 in the corpus cavernosum of the penis.

RESULTS

The level of plasma Hcy, penile erection frequency and the content of CO in the corpus cavernosum were (12.55 +/- 0.82) micromol/L, (1.88 +/- 0.05) times and (10.55 +/- 1.73) micromol/L in group A, the Hcy level significantly higher while the penile erection frequency and CO content remarkably lower than in group B ([25.01 +/- 0.94] micromol/L, [0.70 +/- 0.05] times and [9.51 +/- 1.52] micromol/L, P < 0.05 or P < 0.01), with a negative correlation between the level of Hcy and that of CO and HO-2 (P < 0.01). Compared with group B, the three parameters were all significantly increased in C ([14.37 +/- 0.47] micromol/L, [1.18 +/- 0.08] times and [10.36 +/- 1.56] micromol/L, all P < 0.05 or P < 0.01).

CONCLUSION

Decreased expressions of CO and HO-2 in the corpus cavernosum of the penis may result in ED in HHcy rats. Betaine can reduce the Hcy level in the blood plasma and CO content in the corpus cavernosum, which might be one of the mechanisms of its action on ED with HHcy.

High levels of iron status and oxidative stress in patients with metabolic syndrome

Studies concerning oxidative stress (OxE) parameters have increased, mainly because of its important role in cardiovascular diseases and diabetes complications. The main objective of this study was to evaluate iron nutrition status and oxidative stress parameters in subjects that had developed metabolic syndrome (MetS). Subjects from the Research Program of Risk Factors for Cardiovascular Disease (n = 155) were studied (ages ranging from 45 to 65 years old) and classified according to the Adult Treatment Panel III criterion. A blood sample was taken after a 12-h fasting period, and basal glucose, insulin, thiobarbituric acid reactive substances (TBARS), oxidized LDL (oxLDL), heme oxygenase (HO) activity, lipid profile, and iron nutrition status were determined. Eighty-five subjects were classified as MetS, and 70 non-MetS. Individuals with MetS showed higher Fe storage (high levels of ferritin, total body iron and low transferrin receptor), oxLDL, TBARS, and homeostatic model assessment for insulin resistance levels. The MetS group showed high levels of oxidative stress parameters (HO activity, oxLDL, and TBARS). The presence of MetS showed an association with LDL oxidation risk (multiple lineal regression according to sex and age, p < 0.001). High levels of triglycerides (p < 0.001) and waist circumference (p < 0.012) were associated with oxLDL levels, as well as an association between TBARS and oxLDL with ferritin levels. Through logistic regression analyses, the highest quartile of ferritin was associated with a threefold risk of developing MetS compared to the lowest quartile; also, TBARS showed a 21-fold risk for the development of MetS. Finally, elevated levels of oxidative stress parameters such us oxLDL, TBARS, HO, and Fe storage were associated to MetS.

Rapid clearance of circulating haptoglobin from plasma during acute pulmonary embolism in rats results in HMOX1 up-regulation in peripheral blood leukocytes

BACKGROUND

Acute pulmonary embolism (PE) causes pulmonary hypertension (PH) via several mechanisms including pulmonary vasospasm. We hypothesize that PE with associated PH leads to alterations in plasma protein concentrations indicative of disease severity and prognosis.

OBJECTIVE

To identify plasma proteins altered in abundance by PE in rats.

METHODS

Plasma samples were obtained from rats at 2, 6 and 18 h after experimental PE produced with intrajugular injection of polystyrene beads at three different levels of severity (mild, moderate and severe). Total plasma protein was separated using two-dimensional sodium dodecylsulfate-polyacrylamide gel electrophoresis (2D SDS-PAGE) and candidate protein spots altered in expression by PE were identified by mass spectroscopy. Haptoglobin identity and amount was verified by western blot analysis.

RESULTS

The PE model produced a dose-dependent increase in right ventricular systolic pressure (RVSP) (mmHg) at 2 h: mild 39+/-1.7, moderate 40+/-1.8 and severe 51+/-1.3 mmHg, coincident with significant increases in free plasma (hemoglobin). Combined 2D SDS-PAGE and Western blot analysis indicated time- and dose-dependant loss of plasma haptoglobin levels in response to acute PE. Haptoglobin (HP) was essentially absent from plasma within 2 h of severe PE. Clearance of HP from plasma was accompanied by increased expression of heme oxygenase-1 (hmox1) in peripheral blood leukocytes and in HMOX1 enzyme activity in the liver.

CONCLUSIONS

PE that causes pulmonary hypertension is associated with haptoglobin depletion and up-regulation of HMOX1 enzyme.

[Effect of L-arginine on pro- and antioxidant status of the rat vessels and lungs in experimental rhabdomyolysis]

The glycerol administration was found to cause accumulation of the total heme in rat blood serum, vessels and lungs that are accompanied by increase of TBA-reactive products and protein carbonyl derivates contents. A decrease of superoxide dismutase activity and an increase of reduced glutathione in lung were observed. Heme entering the vessels and lungs is accompanied by elevation in heme oxygenase activity. Pretreatment by L-arginine (0.5 h before glycerol administration) didn't affect blood serum and vessels changes caused by glycerol injection. However, in lungs, L-arginine prevents TBA-reactive products and protein carbonyl derivates accumulation, the decrease ofsuperoxide dismutase activity and causes the ealier heme oxygenase induction. Prooxidant effects of heme in tissues studied and possible mechanisms of L-arginine protective action in lung under experimental rhabdomyolysis are discussed.

A simple and rapid fluorimetric method for simultaneous determination of protoporphyrin IX and zinc protoporphyrin IX in whole blood

Derivative variable-angle synchronous fluorescence (DVASF) spectrometry improves the spectral resolution and selectivity of the fluorescence method. The feasibility of DVASF spectrometry for the simultaneous determination of protoporphyrin IX (PP) and zinc protoporphyrin IX (ZnPP) was investigated. PP and ZnPP were distinguished from each other simultaneously and rapidly by the DVASF method. The spectra were resolved well, and the two components were determined in a single scan, avoiding the spectral compensation factor for PP and chromatographic separation. The linear range of the calibration curve for PP was from 0.190 to 152 nmol/L and for ZnPP was from 0.383 to 230 nmol/L. The detection limits of PP and ZnPP were 0.098 nmol/L and 0.088 nmol/L, respectively. The within-run imprecision (RSD, n = 5) for PP was 4.1%, and for ZnPP was 4.2%. Mean recoveries (SD) of PP and ZnPP added to a blood sample were 86.4 (7.3)% and 72.9 (6.6)%, respectively. This method should be a potential tool in the rapid routine screening of large quantities of samples.

[Heme oxygenase activity in the tissues of the vessels and heart of rats under co-administration of NO-synthase inhibitor and hemin chloride]

The administration of hemin chloride in a dose of 1.5 mg/100 g of the body weight was found to cause accumulation of the total heme and TBA-reactive products in the rat blood serum and vessels. Pretreatment by N(omega)-nitro-L-arginine (0.5 h before hemin chloride administration) did not affect the dynamics of the total heme and TBA-reacting products accumulation. The increase of heme oxygenase activity was observed in the vessels after hemin chloride administration. This effect was strengthened by N(omega)-nitro-L-arginine pretreatment. The changes of heme oxygenase activity and the total heme level in heart were not observed at any periods studied. The increase of the TBA-reactive products level in the heart after exogenous hemin injection was accompanied by an increase of nitrites content and blocked by pretreatment of NOS inhibitor. The N(omega)-nitro-L-arginine alone caused the accumulation of the total heme, TBA-reacting products and the increase of heme oxygenase activity in the vessels. The role of heme and NO in regulation of the heme oxygenase activity is discussed.

Haem oxygenase-1 expression and coronary heart disease--association between levels of haem oxygenase-1 expression and angiographic morphology as well as the quantity of coronary lesions

OBJECTIVE

The aim of this paper was to investigate the association between levels of HO-1 expression and angiographic morphology as well as the quantity of coronary lesions in patients with coronary heart disease (CHD).

METHODS

110 patients with CHD were diagnosed by coronary angiography which contained coronary lesions in some way. Firstly, the patients were divided into 3 groups according to the angiographic morphology of their coronary lesions: type I (smooth borders) group (n1= 36), type II (irregular borders) group (n2= 48) and type III (long and irregular lesions) group (n3= 26). Secondly, the patients were split into a further 3 groups, named: single-vessel group (SV, 38 cases), double-vessel group (DV, 44 cases) and multi-vessel group (MV, 28 cases) according to the number of coronary lesions. Another 30 patients with normal coronary arteries (diagnosed by coronary angiography) were selected as the control group. The levels of HO-1 protein expression in monocytes and lymphocytes from the subjects were tested by immunohistochemistry and Western blot. A computer picture analysing system was also used to measure the levels of HO-1 protein expression.

RESULTS

HO-1 protein was located in cell plasma and the levels of HO-1 protein expression in patients with CHD were significantly higher than in those without CHD (p < 0.01). There were significant differences of HO-1 expression among patients with CHD. Patients with type III lesions had the highest levels, followed by those with type II lesions and the lowest levels were found in patients with type I lesions (p < 0.01). Also, levels of HO-1 protein expression in patients with multi-vessel disease and double-vessel disease were significantly higher than in those with single-vessel disease (p < 0.01).

CONCLUSIONS

There is a higher expression of HO-1 in patients with CHD and the levels of HO-1 protein are associated with severity of CHD angiographically.

Characterization of Heme Oxygenase in Adult Rodent Platelets

Thromboembolism--and its involvement with tissue infarction and ischemic necrosis--continues to be of major importance in the area of vascular biology that affects all areas of clinical medicine. Activated platelets and their aggregations are key initiators in the formation of the thrombus. Several mechanisms have been described to modulate thrombus formation in the circulation, such as prostacyclins and endothelium-derived relaxing factors (the most studied being nitric oxide). Similar to nitrous oxide (NO), carbon monoxide (CO) can modulate guanylate cyclase and has been associated with anti-inflammatory and anti-apoptotic activities. Heme oxygenase (HO), in addition to being the rate-limiting enzyme of CO generation, degrades heme, which is a pro-oxidant/pro-inflammatory and generates the antioxidant molecules biliverdin and bilirubin. HO-2 is generally considered to be enriched in the brain. Here, by studying mouse platelets, we showed that it is highly present in wildtype (WT) animals and not detectable in HO-2 knockout mice. A similar finding was observed in female rats. We also investigated whether modification of estrogen levels (naturally occurring, with age, or surgically) and estrogen replacement would affect intraplatelet HO levels. Under these chronic conditions, HO-1 was barely detectable, while HO-2 was consistently stably expressed at high levels. Further investigation into the functional properties of HO itself, heme degradation, and heme bioactive metabolites remains to be conducted to determine the role of HO on platelet dynamics and on microvasculature.

Does Carboxy-hemoglobin Serve as a Stress-induced Inflammatory Marker Reflecting Surgical Insults?

Endogenous carbon monoxide (CO) production has been recently observed to be an index of the inflammatory response, reflecting various insults in critically ill patients. Major surgery is supposed to modulate the production of CO by transcriptional regulation of heme oxygenase (HO). CO is easy to measure as carboxyhemoglobin (CO-Hb) by spectrophotometry; however, whether CO-Hb can be used as an index reflecting surgical insults is unknown. We investigated changes in CO generation during coronary artery bypass graft by measuring CO-Hb concentrations and the expression of HO in circulating blood as well as the expressions of tumor necrosis factor-alpha (TNF-alpha) and interleukin-1 beta (IL-1 beta). The expression ratios of heme oxygenase-1 (HO-1), TNF-alpha, and IL-1 beta significantly increased after surgery, and these values correlated significantly with one another. CO-Hb concentrations significantly increased after surgery; however, many of those values during artificial ventilation with high inspired oxygen fraction were within normal limits. Furthermore, changes in CO-Hb concentrations were small when preoperative values were high. On the whole, CO-Hb concentrations significantly but weakly correlated with the expression ratios of the inflammatory mediators. However, they did not correlate in the patients who showed higher preoperative CO-Hb concentrations. These data indicate that CO-Hb concentrations can, in general, reflect the inflammatory response induced by surgical insult; however, CO-Hb measurement may not be a useful form of clinical monitoring because of the limited degree of changes, the variation of baseline values, and the necessity for the management under fixed conditions.

Role of heme oxygenase and bilirubin in oxidative stress in preterm infants

In a previous study, it was found that the decrease in the total plasma bilirubin level (Btot) in preterm infants was associated with the decrease in oxidative stress. We hypothesized that this occurs as a result of a pro-oxidant effect of heme oxygenase (HO), which outcompetes with the antioxidant properties of bilirubin. In this study we studied 12 preterm infants in whom the plasma levels of Btot, total hydroperoxide (TH), protein SH groups, HO activity, non-transferrin-bound iron (NTBI), and erythrocyte CuZn superoxide dismutase (CuZn SOD) activity were concurrently measured when the Btot was >220 microM and after a Btot drop of >34 microM. The Btot decrease was concurrent with the TH decrease, protein SH groups increase, and the HO and CuZn SOD activity increase and was not associated with an NTBI increase. We concluded that 1) Btot does not exert a meaningful antioxidant effect in vivo; 2) HO does not exert a pro-oxidant effect involving an NTBI increase and that, on the contrary, it could exert an antioxidant effect; and 3) the concurrent HO and CuZn SOD activity increase could indicate a synergic antioxidant effect of the two enzymes.

Heme oxygenase-1 messenger RNA expression is induced in peripheral blood mononuclear cells of pediatric cancer patients with systemic inflammatory response syndrome

OBJECTIVE

To determine whether heme oxygenase-1 messenger RNA expression in peripheral blood mononuclear cells is induced in pediatric cancer patients with the systemic inflammatory response syndrome (SIRS) and whether this expression correlates with the heme oxygenase-1 products, bilirubin and carboxyhemoglobin.

DESIGN

Prospective, controlled study.

SETTING

A tertiary care pediatric oncology hospital.

PATIENTS

Fourteen patients admitted to the intensive care unit with a diagnosis of SIRS by American College of Chest Physicians/Society for Critical Care Medicine consensus criteria and 17 control patients (off therapy, no acute illness).

INTERVENTIONS

Blood for bilirubin, carboxyhemoglobin, and heme oxygenase-1 messenger RNA expression was collected at study entry. SIRS patients continued to have samples collected every 12 hrs for 1 wk or until intensive care unit discharge. Heme oxygenase-1, bilirubin, and carboxyhemoglobin levels of SIRS patients were compared with controls, and correlation between heme oxygenase-1 and products was assessed.

MEASUREMENTS AND MAIN RESULTS

Within 48 hrs of study entry, maximum heme oxygenase-1 expression for all SIRS patients compared with controls was 5.5 +/- 1.0 vs. 1.1 +/- 0.1 (p < .0006). Maximum expression was > or =2.3-fold in 13 of 14 SIRS patients. Maximum heme oxygenase-1 expression also differed from minimum (5.5 +/- 1.0 vs. 1.6 +/- 0.3, p < .003). Maximum bilirubin and carboxyhemoglobin levels within 48 hrs of study entry differed between SIRS patients and controls (3.0 +/- 0.8 vs. 0.3 +/- 0.1, p = .006; and 1.2 +/- 0.2 vs. 0.6 +/- 0.1, p = .001, respectively). Bilirubin, but not carboxyhemoglobin, correlated with heme oxygenase-1 expression (p = .0013).

CONCLUSIONS

Heme oxygenase-1 messenger RNA, bilirubin, and carboxyhemoglobin levels were increased within 48 hrs of admission in pediatric cancer patients with SIRS. Heme oxygenase-1 expression correlated with serum bilirubin levels. The increase in heme oxygenase-1 expression may add to the understanding of the increase in serum bilirubin observed in patients with SIRS/sepsis. These findings support a role for heme oxygenase-1 in the physiologic response to inflammatory stress.

[Therapy with NO donors-antiatherogenic and antioxidant actions]

Nitric acid esters such as glyceryl trinitrate were introduced into therapy more than a century ago and are still widely used for the treatment of myocardial ischemia and its main symptom angina pectoris. The basic mechanisms responsible for the vasodilatory and anti-ischemic action of organic nitrates involve bioactivation of, and nitric oxide (NO) release from, these compounds which have therefore been termed NO donors. The organic nitrate pentaerythritol tetranitrate (PETN) is known to possess antioxidant properties that are thought to be the underlying cause for its specific pharmacological profile. In contrast to other long-acting nitrates, PETN induces tolerance- free vasodilation in humans and was reported to prevent endothelial dysfunction as well as atherogenesis in cholesterol- fed rabbits. However, the exact nature of the vasoprotective signaling pathways triggered by PETN has remained obscure. The present study demonstrates that the active PETN metabolite PETriN stimulates protein expression of the antioxidant defense protein heme oxygenase-1 (HO-1; Figures 1 and 2). Additionally, PETriN enhanced the enzymatic activity of HO-1 measured as formation of the HO-1 metabolites bilirubin (Figure 3) and carbon monoxide (Figure 4) in lysates from endothelial cells. HO-1 induction subsequently led to a marked increase in protein expression of a second antioxidant protein, ferritin, via the HO-1-dependent release of free iron from endogenous heme sources (Figures 1 and 5). Pretreatment of endothelial cells with PETriN was followed by increased cellular resistance to oxidant injury mediated by hydrogen peroxide (Figure 6). Endothelial protection by PETriN was mimicked by exogenous bilirubin which led to an almost complete reversal of hydrogen peroxide-induced toxicity (Figure 8). Increased HO-1 and ferritin expression as well as endothelial protection occurred at micromolar concentrations of PETriN which are well within the range of plasma or tissue levels that can be expected during oral therapy. The capacity to protect the endothelium in vitro may translate into and explain the previously observed antiatherogenic actions of PETN in vivo. In this study, another long-acting nitrate, isosorbide dinitrate (ISDN), did not protect endothelial cells from oxidant damage (Figure 6). The absence of significant cytoprotection in the presence of ISDN was paralleled by a lack of HO-1 and ferritin stimulatory capacity (Figures 2 and 5). ISDN had no significant effect on carbon monoxide release or bilirubin formation (Figures 3 and 4). These observations are in agreement with results demonstrating small or nondetectable amounts of NO released from ISDN and its active metabolite isosorbide mononitrate (ISMN) measured as cyclic GMP formation in RFL-6 reporter cells (Figure 7). Interestingly and in contrast to PETN, isosorbide nitrates are known to induce tolerance to their cardiovascular effects, presumably via oxidant stress. Moreover, in earlier investigations aimed at assessing the antiatherogenic potential of nitrates, PETN but not isosorbide nitrates prevented plaque formation and endothelial dysfunction in animal models of atherosclerosis. Thus, the ability to activate HO-1 induction and associated antioxidant pathways apparently distinguishes PETN from other long-acting nitrates and may explain their different patterns of action in vivo (Figure 9).

Neutrophil activation, antioxidant supplements and exercise-induced oxidative stress

Neutrophils produce free radicals known as reactive oxygen species (ROS), which assist in the clearance of damaged host tissue. Tissue damage may occur during exercise due to muscle damage, thermal stress and ischaemia/reperfusion. When produced in excess, neutrophil-derived ROS may overwhelm the body's endogenous antioxidant defence mechanisms, and this can lead to oxidative stress. There is increasing evidence for links between oxidative stress and a variety of pathological disorders such as cardiovascular diseases, cancer, chronic inflammatory diseases and post-ischaemic organ injury. A small number of studies have investigated whether there is a link between neutrophil activation and oxidative stress during exercise. In this review, we have summarised the findings of these studies. Exercise promotes the release of neutrophils into the circulation, and some evidence suggests that neutrophils mobilised after exercise have an enhanced capacity to generate some forms of ROS when stimulated in vitro. Neutrophil activation during exercise may challenge endogenous antioxidant defence mechanisms, but does not appear to increase lipid markers of oxidative stress to any significant degree, at least in the circulation. Antioxidant supplements such as N-acetylcysteine are effective at attenuating increases in the capacity of neutrophils to generate ROS when stimulated in vitro, whereas vitamin E reduces tissue infiltration of neutrophils during exercise. Free radicals generated during intense exercise may lead to DNA damage in leukocytes, but it is unknown if this damage is the result of neutrophil activation. Exercise enhances the expression of inducible haem (heme)-oxygenase (HO-1) in neutrophils after exercise, however, it is uncertain whether oxidative stress is the stimulus for this response.

[Effects of hypoxia on heme oxygenase/carbon monoxide and type I collagen in pulmonary artery smooth muscle cells of rats]

OBJECTIVE

To explore changes of expression of heme oxygenase (HO) and production of endogenous carbon monoxide in hypoxic pulmonary artery smooth muscle cells (PASMCs) of rats and study their effects on type I collagen under hypoxia.

METHODS

PASMCs of rats were cultured in vitro and incubated under hypoxic condition for 24 hours. The relative content of CO released into medium by PASMCs was detected using spectrophotometry. Western blot was applied to assay the expressions of HO-1 and transforming growth factor-beta(3) (TGF-beta(3)). The expressions of HO-1, TGF-beta(3) and type I collagen were detected by immunohistochemical assay. The expressions of procollagen type I were detected by in situ hybridization.

RESULTS

Hypoxia induced the expression of TGF-beta(3), type I collagen and mRNA in rat PASMCs, elevated the expression of HO-1 and CO content compared to controls by 67.45% (P<0.01) and 35.41% (P<0.05), respectively. In the hypoxic PASMCs treated with protoporphyrin-IX (ZnPP)(10 micromol x L(-1)), an inhibitor of HO, the expression of HO-1 and the CO content were 23.9%(P<0.05), 7.88% (P<0.01) lower than those of hypoxic PASMCs, respectively. ZnPP promoted the expression of TGF-beta(3) (393%,P<0.01), type I collagen protein and mRNA in hypoxic PASMCs. Hemin (20 micromol x L(-1)), an inducer of HO, caused an increase in the expression of HO-1 and CO content in hypoxic rat PASMCs by 105% (P<0.05), 8.83% (P<0.01) compared to hypoxic PASMCs, respectively. Hemin inhibited the expression of TGF-beta(3) by 68.12% (P<0.01), and type I collagen protein and mRNA in hypoxic PASMCs.

CONCLUSION

HO/CO system is up-regulated by hypoxia and endogenous CO may play an important role in decreasing collagen synthesis and inhibiting the expression of TGF-beta(3) in hypoxic rat PASMCs.

Comparison of m-RNA expression for inflammatory mediators in leukocytes between on-pump and off-pump coronary artery bypass grafting

OBJECTIVE

Coronary artery bypass grafting (CABG) with cardiopulmonary bypass (CPB) is associated with a systemic inflammatory response. This is mainly attributed to cytokine release caused by CPB and global myocardial ischemia. Coronary artery bypass grafting without cardiopulmonary bypass (off-pump CABG, OPCAB) is now accepted as a less invasive technique than conventional CABG. This study was designed to compare the inflammatory response at the m-RNA level of proinflammatory cytokines and adhesion molecules before and after operation in patients undergoing CABG with and without CPB.

METHODS

Twenty patients who underwent isolated CABG with CPB (on-pump group, n=10) or without CPB (off-pump group, n=10) were studied. By utilizing a semiquantitative reverse transcription polymerase chain reaction (RT-PCR) technique, gene expression of cytokines, adhesion molecules, and vasoactive substances in leukocytes of peripheral blood were evaluated before and six hours after surgery.

RESULTS

Postoperative expression of m-RNA for interleukin (IL)-1, -8, and -10, tumor necrosis factor (TNF)-alpha, heme oxygenase (HO)-1, platelet endothelial cellular adhesion molecule (PECAM) and Mac-1 increased significantly in the on-pump group but not in the off-pump group (p<0.05).

CONCLUSIONS

In view of the m-RNA level of proinflammatory cytokines and adhesion molecules, it can be concluded that OPCAB is a less invasive technique than on-pump CABG. Direct contact of circulating blood with the synthetic surfaces of the CPB system may be the main cause of the systemic inflammation.

Heme oxygenase activity and some indices of antioxidant protection in rat liver and kidney in glycerol model of rhabdomyolysis

Activity of heme oxygenase, superoxide dismutase, and catalase, the content of reduced glutathione and total heme in the liver and kidneys, and serum absorption spectrum in the Soret band were studied in rats with glycerol-induced rhabdomyolysis. Glycerol increased the content of heme-containing metabolites in the serum and the total heme content in the liver and kidneys, and decreased the content of reduced glutathione and catalase activity in the examined organs. Superoxide dismutase activity increased in the liver and decreased in the kidneys. Heme oxygenase activity increased in the liver and kidneys 2 and 6 h postinjection, respectively. The effects of heme delivered to the liver and kidneys from the vascular bed on the antioxidant defense and heme oxygenase activity were studied.

[Heme oxygenase activity in rat organs during cadmium chloride administration]

Heme oxygenase activity, the level of spontaneous and ascorbat-induced LPO in the liver, kidney and spleen homogenates of rats and blood serum absorption spectrum in the Soret region in different periods both after CdCl2 and prior alpha-tocopherol administration were studied. The increase in the hemolysis products content in the serum was observed in 15 min after CdCl2 injection and remained during 24 h. Heme oxygenase activity in the liver and kidney increased after 6 h and stayed at the same level 24 h after CdCl2 administration. The level of spontaneous LPO in the spleen increased after 6 h, and in the liver and kidney the level of spontaneous and ascorbat-induced LPO increased in 24 h after CdCl2 injection. The preliminary alpha-tocopherol administration did not prevent the accumulation of hemolysis products in the serum and the increase of heme oxygenase activity in the liver and kidney caused by CdCl2 administration. However, the increase in the ascorbat-induced LPO in these organs was completely blocked. The role of heme and LPO in the heme oxygenase induction by CdCl2 are discussed.

Oxidative stress and TGFbeta in kidney-transplanted patients with cyclosporin-induced hypertension. Effect of carvedilol and nifedipine

Cyclosporin is a powerful stimulator of oxidative stress signaling, leading to TGFbeta production, NO degradation, endothelial dysfunction, hypertension and post-transplant nephropathy. Carvedilol, alpha1-beta-blocker with strong antioxidant activity, may interfere with this chain of events. Therefore, we measured monocyte ecNOS, TGFbeta and heme oxygenase-1 (HO-1) mRNA level and plasma nitrite/nitrate, 3-nitrotyrosine, an estimate of peroxynitrite, and total plasma antioxidant power in kidney-transplanted patients with post-transplant hypertension, before and after treatment with carvedilol, 25 - 50 mg o.d. orally for 4 months (n = 15). The dihydropyridine calcium channel blocker nifedipine (n = 10) was used as comparator antihypertensive drug. Blood pressure fell to a similar extent with both drugs. Carvedilol increased plasma antioxidant power and HO-1 mRNA and reduced 3-nitrotyrosine and TGFbeta mRNA levels, while the same was not observed with nifedipine. Monocyte ec NOS mRNA levels and plasma nitrite/nitrate were higher in the patients than in a normotensive healthy control group and were unaffected by either treatment. In conclusion, carvedilol reduces the oxidative stress and corrects the altered cellular signaling mediated by oxidative stress in CsA-induced post-transplant hypertension. Therefore, it may prevent long-term complications, such as endothelial dysfunction, fibrogenesis and post-transplant nephropathy by decreasing NO degradation and production of TGFbeta, a key fibrogenic cytokine, and by activating HO-1 production.

Evaluation of heme oxygenase-1 as a systemic biological marker of sporadic AD

BACKGROUND

Heme oxygenase-1 (HO-1) is a 32-kDa stress protein that catalyzes the degradation of heme to biliverdin. HO-1 immunoreactivity is greatly increased in neurons and astrocytes of the hippocampus and cerebral cortex of individuals with AD and colocalizes to senile plaques and neurofibrillary tangles.

METHODS

We investigated whether systemic HO-1 regulation is also deranged in AD patients and whether blood HO-1 measurements provide a peripheral biomarker of the disease. Plasma HO-1 protein levels were measured by competitive ELISA and lymphocyte HO-1 mRNA levels were determined by Northern analysis in patients with early probable sporadic AD, normal elderly controls (NEC), normal younger controls, individuals with age-associated cognitive decline (AACD) not meeting AD criteria, and patients with non-Alzheimer dementia, nondementing neurologic illness, and chronic medical disorders. CSF HO-1 protein concentrations were also determined by ELISA in pathologically confirmed AD and control cases.

RESULTS

Mean plasma HO-1 protein concentrations were significantly lower in AD patients (0.85 +/- 0.14 microg/mL) compared with NEC (1.77 +/- 0.34 microg/mL; p < 0.05) and control patients. The AACD group exhibited plasma HO-1 concentrations (1.06 +/- 0.33 microg/mL) intermediate between, but not different from, those of the AD patients and NEC. Lymphocyte HO-1 mRNA levels were lower in the AD cohort relative to NEC (p < 0.001) and individuals with AACD, non-Alzheimer dementia, nondementing neurologic illness, and chronic medical conditions. Lymphocyte HO-1 mRNA levels were also lower in the AACD group relative to NEC (p < 0.05). In comparison with all groups excluding AACD, the sensitivity and specificity of lymphocyte HO-1 mRNA measurement for diagnosis of early sporadic AD are 88% and 75%. Mean CSF HO-1 protein concentrations were lower (p < 0.01) in AD cases (19.07 ng/mL) relative to control values (32.48 ng/mL).

CONCLUSIONS

Plasma and CSF HO-1 protein and lymphocyte HO-1 mRNA levels are decreased in subjects with sporadic AD. Quantitative assay for lymphocyte HO-1 mRNA expression may serve as a useful biologic marker in early sporadic AD.

Expression of the antioxidant stress protein heme oxygenase-1 (HO-1) in human leukocytes

Inducible heme oxygenase (HO-1) is an antioxidant stress protein, that is mainly induced by reactive oxygen species (ROS), cytokines and hyperthermia. By using flow cytometry the present investigation demonstrated a rise in the cytoplasmic expression of HO-1 in lympho- (L), mono- (M) and granulocytes (G) of 9 endurance-trained male subjects after a half marathon run. The expression was more pronounced in M (median: 98.3% HO-1 positive cells/4.31 mfc) and G (94.8%/1.93 mfc) than in L (80.1%/1.51 mfc) when measured 3 h post-exercise. Additionally the exercise protocol caused a rise in the plasma levels of myeloperoxidase, TNF alpha and interleukin-8 (IL-8), indicating an inflammatory response. We could detect a correlation between IL-8 and HO-1, directly after exercise, that was apparent in G (r = 0.67, p < .05) and L (r = 0.80, p < .05), but did not reach significance in M (r = 0.65, p = 0.06). An additional detection of HO-1 at rest in 12 untrained subjects showed a higher baseline expression of HO-1 compared to the athletes. The regulatory pathways leading to an increased expression of HO-1 after endurance exercise are not completely clear, but a causal involvement of a cytokine-mediated generation of ROS must be discussed. We supposed that the down-regulation of the baseline expression of HO-1 in athletes reflects an adaptional mechanism to regular exercise training.

Iron release from human monocytes after erythrophagocytosis in vitro: an investigation in normal subjects and hereditary hemochromatosis patients

This study investigated the release of erythrocyte-derived iron from purified human monocytes obtained from healthy volunteers and hereditary hemochromatosis (HH) patients. After erythrophagocytosis of 59Fe-labeled erythrocytes, a complete transfer of iron from hemoglobin (Hb) to ferritin was observed within 24 hours in both control and HH monocytes. The iron was released from the monocytes in the form of ferritin, Hb, and as nonprotein bound low molecular weight iron (LMW-Fe). During the initial rapid phase (<1.5 hours), iron release mostly consisted of Hb and LMW-Fe, while in the later phase (>1.5 hours), it was composed of ferritin and LMW-Fe. The kinetics of iron release were identical for HH monocytes. A high percentage of the total amount of iron was released as Hb both by viable normal and HH monocytes, suggesting that iron release as Hb is a physiologic process, which may occur whenever the erythrocyte-processing capacity of macrophages is exceeded. Most remarkably, HH monocytes released twice as much iron in a LMW form as control cells. Iron released in the form of LMW-Fe readily binds to plasma transferrin and may contribute to the high transferrin saturation and the occurrence of circulating nontransferrin-bound iron observed in HH patients.

Induction of heme oxygenase-1 during endotoxemia is downregulated by transforming growth factor-beta1

Heme oxygenase (HO)-1 generates CO, a gas with vasodilatory properties, during heme metabolism. HO-1 is expressed highly in vascular tissue after endotoxin stimulation, and generation of CO through the HO-1 pathway contributes to the hemodynamic compromise of endotoxic shock. Shock related to endotoxemia is an immune-mediated process that involves the generation of proinflammatory cytokines such as interleukin (IL)-1beta. Because transforming growth factor (TGF)-beta1 is a modulator of immune-mediated inflammatory responses and it blocks the hypotension of endotoxic shock, we determined whether TGF-beta1 could be used to reduce expression of HO-1 in vascular tissue and smooth muscle cells. In a rat model of endotoxic shock, lipopolysaccharide-induced HO-1 mRNA and protein expression was reduced by TGF-beta1 in highly vascularized tissue, such as heart and lung, by Northern and Western analysis. Furthermore, TGF-beta1 downregulated HO-1 mRNA after its induction by IL-1beta in vascular smooth muscle cells in culture. TGF-beta1 also decreased HO-1 but not HO-2 protein expression in these cells. TGF-beta1 decreased HO enzyme activity induced in IL-1beta treated vascular smooth muscle cells to a level not different from that in vehicle-treated cells. These studies suggest that this downregulation of HO-1 mRNA and protein expression and decrease in IL-1beta-induced HO enzyme activity may contribute to the beneficial effect of TGF-beta1 on endotoxic shock.

Effect of aluminum on hematopoiesis after intraperitoneal exposure in rats

The experiments were performed on female Wistar rats that received aluminum chloride every day intraperitoneally, 4 mg Al/kg for 3 weeks. In the blood selected morphological factors and delta-aminolevulinic acid dehydratase activity (ALA-D) were investigated. In the kidney and liver ALA-D, delta-aminolevulinic acid synthase (ALA-S), and heme oxygenase activity were also determined. After aluminum chloride administration the most sensitive indicator was an increase of heme oxygenase activity in the liver and a decrease in iron levels in the serum of rats. Aluminum also increased ALA-S activity in the kidney and liver of rats. No changes of ALA-D activity in the liver, the kidney, and the blood were observed. The decreasing of hemoglobin, hematocrit, mean corpuscular hemoglobin mass, and mean corpuscular hemoglobin concentration was noted after 3 weeks of exposure.

Tissue distribution of synthetic heme analogues: studies with tin, chromium, and zinc mesoporphyrins

The uptake in tissue of Sn-mesoporphyrin (SnMP), Cr-mesoporphyrin (CrMP) and Zn-mesoporphyrin (ZnMP) administered at doses ranging from 1 to 10 mu mol/kg BW and the effects of these compounds on heme oxygenase activity were examined in both adult and neonatal rats. SnMP and CrMP, but not ZnMP, were rapidly cleared from blood and taken up by liver, spleen and kidney where marked inhibition of heme oxygenase activity was demonstrated. None of the metalloporphyrins were detectable in brain, and no inhibition of heme oxygenase activity was demonstrable in this tissue after administration of the compounds to both adult and neonatal rats. These results demonstrate that SnMP, CrMP and ZnMP do not cross the blood brain barrier, a fact of interest in relation to the potential use of these compounds clinically.

Elevated levels of heme oxygenase-1 activity and mRNA in peripheral blood adherent cells of acquired immunodeficiency syndrome patients

Patients with the acquired immunodeficiency syndrome (AIDS) commonly develop hematological abnormalities, including anemia, leukopenia, and thrombocytopenia. Heme synthesis and heme degradation are critical to the maintenance of cellular heme homeostasis and to hematopoietic differentiation. We examined heme oxygenase activity and expression of the heme oxygenase gene in adherent cells (monocytes-macrophages) obtained from the peripheral blood of AIDS patients and normal controls. Heme oxygenase activity in normal control cells was 43 +/- 16 pmol bilirubin formed/4 x 10(5) cells/hr as compared to 133 +/- 30 pmol bilirubin formed/4 x 10(5) cells/hr in the AIDS patients. Via blot hybridization analysis with human heme oxygenase cDNA, heme oxygenase mRNA levels in cells of the normal and the AIDS patients were compared. Total RNA from normal cells displayed only weak hybridization with the cDNA probe. In contrast, cells from peripheral blood of the AIDS patients displayed marked increases over normal levels in heme oxygenase mRNA. Heme oxygenase activity could be substantially suppressed by the competitive inhibitor of the enzyme, Sn-mesoporphyrin. Elevated heme oxygenase activity in cells of AIDS patients could produce a decrease in cellular heme needed for transductional signalling for the growth factor network, which regulates the hematopoietic microenvironment, and for other metabolic purposes. Suppression of heme catabolism by inhibitors of this enzyme may thus be useful in potentiating erythropoietic responses in this disorder.

Heme metabolism and in vitro erythropoiesis in anemia associated with hypochromic microcytosis

Heme metabolism and in vitro erythropoietic growth (CFU-E, BFU-E) were examined in bone marrow cells taken from two siblings with apparent familial hypochromic microcytic anemia. Bone marrow cells from both patients grew adequate numbers of CFU-E and BFU-E colonies in culture in the presence of erythropoietin. In addition, small numbers of endogenous CFU-E were seen in 7-day cultures. Assays on bone marrow cells taken from both patients revealed that baseline delta-aminolevulinic synthase activity was considerably reduced, but increased six to seven fold (to normal levels) when patients' cells were exposed to pyridoxal phosphate (PLP). In both cases, ferrochelatase and delta-aminolevulinic acid dehydratase activities were normal. Bone marrow heme oxygenase showed no significant differences in activities between normals and patients values in the absence or presence of PLP. In contrast, heme synthesis by patients' bone marrow was less than that of normals. This study demonstrates that bone marrow cells from patients with this rare disorder have some disturbances in heme metabolism, whereas erythropoiesis appeared to be normal when cultured with adequate nutrients in vitro.

Control of heme oxygenase and plasma levels of bilirubin by a synthetic heme analogue, tin-protoporphyrin

The catalytic site of heme oxygenase recognizes metalloporphyrins with central metal atoms other than iron; it favors some of these metalloporphyrins over heme as a potential substrate sometimes by a large factor, permitting the synthetic heme analogue to serve as a potent competitive inhibitor of the heme oxygenase reaction. Since these synthetic metalloporphyrins do not bind molecular oxygen, they are not metabolically degraded by ring rupture and do not add to the body pool of bile pigment. One possible consequence of this competitive inhibition of heme degradation is suppression of bile pigment formation to such a degree that excessive plasma levels of bilirubin may be diminished. That the latter phenomenon occurs was shown for the first time by our study in 1981 (6), and by subsequent investigations in rats, mice, monkeys and man. The compound does not appear to affect the metabolic disposition of preformed bilirubin but inhibits biliary bilirubin excretion derived from the metabolism of endogenous or exogenous heme. Whether some of the effect of Sn-protoporphyrin on naturally occurring or experimentally induced jaundice in animals reflects diversion of heme to nonheme oxygenase-dependent pathways of heme metabolism or whether a pathway which is normally latent becomes activated concurrent with heme oxygenase inhibition is not known. Sn-protoporphyrin is remarkably innocuous in the newborn rat and may prove so in man.(ABSTRACT TRUNCATED AT 250 WORDS)

Phagocytosis of senescent erythrocytes by autologous monocytes: requirement of membrane-specific autologous IgG for immune elimination of aging red blood cells

The role of membrane-bound IgG present on the membrane of senescent erythrocytes in immune eliminations of aging red cells was investigated. Phagocytosis of populations of red blood cells (RBC) of different ages by autologous monocytes was assessed both by direct phagocytosis and by induction of microsomal heme oxygenase. Removal of IgG from older RBCs inhibited their phagocytosis; in contrast, preincubation of neuraminidase-treated young or in vitro aged RBCs with IgG eluted from old cells led to phagocytosis of RBCs treated by autologous monocytes. It was also found that the Fc portion of membrane-bound IgG is essential for the elimination of senescent cells; less than 15% of old heat-inactivated RBCs coated with F(ab)2 fragment of membrane-bound IgG were phagocytosed. In contrast, more than 50% of old heat-inactivated RBCs coated with heat-eluted IgG were phagocytosed by autologous monocytes. A possible mechanism of elimination of aged cells is discussed.