Intravenous Hemin, a potential heme oxygenase-1 activator, does not protect from post-ERCP acute pancreatitis in humans: Results of a randomized multicentric multinational placebo-controlled trial

OBJECTIVE

Hemin, a heme oxygenase 1 activator has shown efficacy in the prevention and treatment of acute pancreatitis in mouse models. We conducted a randomized controlled trial (RCT) to assess the protective effect of Hemin administration to prevent post-endoscopic retrograde cholangiopancreatography (ERCP) pancreatitis (PEP) in patients at risk.

METHODS

In this multicenter, multinational, placebo-controlled, double-blind RCT, we assigned patients at risk for PEP to receive a single intravenous dose of Hemin (4 mg/kg) or placebo immediately after ERCP. Patients were considered to be at risk on the basis of validated patient- and/or procedure-related risk factors. Neither rectal NSAIDs nor pancreatic stent insertion were allowed in randomized patients. The primary outcome was the incidence of PEP. Secondary outcomes included lipase elevation, mortality, safety, and length of stay.

RESULTS

A total of 282 of the 294 randomized patients had complete follow-up. Groups were similar in terms of clinical, laboratory, and technical risk factors for PEP. PEP occurred in 16 of 142 patients (11.3%) in the Hemin group and in 20 of 140 patients (14.3%) in the placebo group (p = 0.48). Incidence of severe PEP reached 0.7% and 4.3% in the Hemin and placebo groups, respectively (p = 0.07). Significant lipase elevation after ERCP did not differ between groups. Length of hospital stay, mortality and severe adverse events rates were similar between groups.

CONCLUSION

We failed to detect large improvements in PEP rate among participants at risk for PEP who received IV hemin immediately after the procedure compared to placebo.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov number, NCT01855841).

A Versatile G-Quadruplex (G4)-Coated Upconverted Metal-Organic Framework for Hypoxic Tumor Therapy

Given the complexity of the tumor microenvironment, multiple strategies are being explored to tackle hypoxic tumors. The most efficient strategies combine several therapeutic modalities and typically requires the development of multifunctional nanocomposites through sophisticated synthetic procedures. Herein, the G-quadruplex (G4)-forming sequence AS1411-A (d[(G2 T)4 TG(TG2 )4 A]) is used for both its anti-tumor and biocatalytic properties when combined with hemin, increasing the production of O2 ca. two-fold as compared to the parent AS1411 sequence. The AS1411-A/hemin complex (GH) is grafted on the surface and pores of a core-shell upconverted metal-organic framework (UMOF) to generate a UMGH nanoplatform. Compared with UMOF, UMGH exhibits enhanced colloidal stability, increased tumor cell targeting and improved O2 production (8.5-fold) in situ. When irradiated by near-infrared (NIR) light, the UMGH antitumor properties are bolstered by photodynamic therapy (PDT), thanks to its ability to convert O2 into singlet oxygen (1 O2 ). Combined with the antiproliferative activity of AS1411-A, this novel approach lays the foundation for a new type of G4-based nanomedicine.

EXPLORE B: A prospective, long-term natural history study of patients with acute hepatic porphyria with chronic symptoms

One-year data from EXPLORE Part A showed high disease burden and impaired quality of life (QOL) in patients with acute hepatic porphyria (AHP) with recurrent attacks. We report baseline data of patients who enrolled in EXPLORE Part B for up to an additional 3 years of follow-up. EXPLORE B is a long-term, prospective study evaluating disease activity, pain intensity, and QOL in patients with AHP with ≥1 attack in the 12 months before enrollment or receiving hemin or gonadotropin-releasing hormone prophylaxis. Data were evaluated in patients with more (≥3 attacks or on prophylaxis treatment) or fewer (<3 attacks and no prophylaxis treatment) attacks. Patients in the total population (N = 136), and more (n = 110) and fewer (n = 26) attack subgroups, reported a median (range) of 3 (0-52), 4 (0-52), and 1 (0-2) acute attacks, respectively, in the 12 months prior to the baseline visit. Pain, mood/sleep, digestive/bladder, and nervous system symptoms were each experienced by ≥80% of patients; most received hemin during attacks. Almost three-quarters of patients reported chronic symptoms between attacks, including 85% of patients with fewer attacks. Pain intensity was comparable among both attack subgroups; most patients required pain medication. All groups had diminished QOL on the EuroQol visual analog scale and the European Organisation for Research and Treatment of Cancer Quality-of-life Questionnaire Core 30 versus population norms. Patients with AHP with recurrent attacks, even those having fewer attacks, experience a high disease burden, as evidenced by chronic symptoms between attacks and impaired QOL.

Hemin as a novel candidate for treating COVID-19 via heme oxygenase-1 induction

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative agent of the coronavirus disease-19 (COVID-19). More than 143 million cases of COVID-19 have been reported to date, with the global death rate at 2.13%. Currently, there are no licensed therapeutics for controlling SARS-CoV-2 infection. The antiviral effects of heme oxygenase-1 (HO-1), a cytoprotective enzyme that inhibits the inflammatory response and reduces oxidative stress, have been investigated in several viral infections. To confirm whether HO-1 suppresses SARS-CoV-2 infection, we assessed the antiviral activity of hemin, an effective and safe HO-1 inducer, in SARS-CoV-2 infection. We found that treatment with hemin efficiently suppressed SARS-CoV-2 replication (selectivity index: 249.7012). Besides, the transient expression of HO-1 using an expression vector also suppressed the growth of the virus in cells. Free iron and biliverdin, which are metabolic byproducts of heme catalysis by HO-1, also suppressed the viral infection. Additionally, hemin indirectly increased the expression of interferon-stimulated proteins known to restrict SARS-CoV-2 replication. Overall, the findings suggested that HO-1, induced by hemin, effectively suppressed SARS-CoV-2 in vitro. Therefore, HO-1 could be potential therapeutic candidate for COVID-19.

Self-Assembling Porphyrins as a Single Therapeutic Agent for Synergistic Cancer Therapy: A One Stone Three Birds Strategy

Combining photodynamic therapy (PDT), chemodynamic therapy (CDT), and ferroptosis is a valuable means for an enhanced anticancer effect. However, traditional combination of PDT/CDT/ferroptosis faces several hurdles, including excess glutathione (GSH) neutralization and preparation complexity. In this work, a versatile multifunctional nanoparticle (HCNP) self-assembled from two porphyrin molecules, chlorin e6 and hemin, is developed. The as-constructed HCNPs exhibit a peroxidase-mimic catalytic activity, which can lead to the in situ generation of endogenous O2, thereby enhancing the efficacy of PDT. Furthermore, the generation of hydroxyl radicals (•OH) in the tumor environment in reaction to the high level of H2O2 and the simultaneous disruption of intracellular GSH endow the HCNPs with the capacity of enhanced CDT, resulting in a more effective therapeutic outcome in combination with PDT. More importantly, GSH depletion further leads to the inactivation of GSH peroxide 4 and induced ferroptosis. Both in vitro and in vivo results showed that the combination of PDT/CDT/ferroptosis realizes highest antitumor efficacy significantly under laser irradiation. Therefore, by integrating the superiorities of O2 and •OH generation capacity, GSH-depletion effect, and bioimaging into a single nanosystem, the HCNPs are a promising single therapeutic agent for tumor PDT/CDT/ferroptosis combination therapy.

Real-world annualized healthcare utilization and expenditures among insured US patients with acute intermittent porphyria (AIP) treated with hemin

Background and aims: Patients with acute intermittent porphyria (AIP) may suffer from acute non-specific attacks that often result in hospitalizations or emergency room (ER) visits. Prior to the recent approval of givosiran (November 2019), hemin was the only FDA-approved therapy for AIP attacks in the US. Our aim was to estimate the annual healthcare utilization and expenditures for AIP patients treated with hemin using real-world data.Methods: Patients with ≥1 hemin claim and confirmed AIP diagnosis - 1 inpatient claim or 2 outpatient claims ≥30 d apart for AIP (2015-2017) or acute porphyria (prior to 2015) - were identified in MarketScan administrative claims dataset between 2007 and 2017. Continuous enrolment for ≥6 months from confirmed diagnosis was required. A secondary analysis ("active disease population") limited the sample to adult patients with ≥3 attacks or 10 months of prophylactic use of hemin within a 12-month pre-index period. AIP-related care was defined by hemin use during an attack (daily glucose and/or hemin use) or prophylaxis (non-attack hemin use). Outcomes were annualized and expenditures were inflated to 2017.Results: Across 10 years, patients with a confirmed AIP diagnosis (N = 8,877) and ≥1 hemin claim (N = 164) were restricted by ≥6 months continuous follow-up (N = 139). AIP patients were mostly female (N = 112; 81%), had median age of 40 and 3 years average follow-up. Annualized average total expenditures for AIP-related care were $113,477. Annualized average all-cause (any diagnosis) hospitalizations were statistically significantly lower for patients treated with hemin prophylaxis vs. acute treatment (1.0 vs. 2.1; p < .001). In the secondary analysis (N = 27), annualized average total expenditures for AIP-related care were higher ($187,480).Conclusions: For AIP patients treated with hemin, patients treated for acute attacks may use a greater number of resources compared to patients treated prophylactically.

Paediatric porphyria and human hemin: a treatment challenge in a lower middle income country

Here, we report a case of a 15-year-old girl who presented to the emergency department with symptoms of abdominal pain, nausea, vomiting and seizures. She was diagnosed with acute intermittent porphyria. Treatment was started by removing all porphogenic drugs, providing high glucose intake (oral and intravenous), which initially resulted in good clinical outcomes. However, she deteriorated again and also developed neurological manifestation (paraplegia) for which she required mechanical ventilation because of acute respiratory failure. This time she was initiated on human hemin for four consecutive days. After 2 days of therapy, her porphobilinogen levels decreased to 50% of the initial raised value. Increased lactic acid and blood urea nitrogen were the two side effects observed after the treatment, with no apparent signs of acute kidney injury. To the best of our knowledge, in paediatric population, this is the first reported case of treatment of acute intermittent porphyria with human hemin in Pakistan.

Oral DhHP-6 for the Treatment of Type 2 Diabetes Mellitus

Type 2 diabetes mellitus (T2DM) is associated with pancreatic β-cell dysfunction which can be induced by oxidative stress. Deuterohemin-βAla-His-Thr-Val-Glu-Lys (DhHP-6) is a microperoxidase mimetic that can scavenge reactive oxygen species (ROS) in vivo. In our previous studies, we demonstrated an increased stability of linear peptides upon their covalent attachment to porphyrins. In this study, we assessed the utility of DhHP-6 as an oral anti-diabetic drug in vitro and in vivo. DhHP-6 showed high resistance to proteolytic degradation in vitro and in vivo. The degraded DhHP-6 product in gastrointestinal (GI) fluid retained the enzymatic activity of DhHP-6, but displayed a higher permeability coefficient. DhHP-6 protected against the cell damage induced by H₂O₂ and promoted insulin secretion in INS-1 cells. In the T2DM model, DhHP-6 reduced blood glucose levels and facilitated the recovery of blood lipid disorders. DhHP-6 also mitigated both insulin resistance and glucose tolerance. Most importantly, DhHP-6 promoted the recovery of damaged pancreas islets. These findings suggest that DhHP-6 in physiological environments has high stability against enzymatic degradation and maintains enzymatic activity. As DhHP-6 lowered the fasting blood glucose levels of T2DM mice, it thus represents a promising candidate for oral administration and clinical therapy.

A Novel Peroxidase Mimics and Ameliorates Alzheimer's Disease-Related Pathology and Cognitive Decline in Mice

Alzheimer's disease (AD) is the most common neurodegenerative disorder in the elderly, which is characterized by the accumulation of amyloid β (Aβ) plaques, oxidative stress, and neuronal loss. Therefore, clearing Aβ aggregates and reducing oxidative stress could be an effective therapeutic strategy for AD. Deuterohemin-AlaHisThrValGluLys (DhHP-6), a novel deuterohemin-containing peptide mimetic of the natural microperoxidase-11 (MP-11), shows higher antioxidant activity and stability compared to the natural microperoxidases. DhHP-6 possesses the ability of extending lifespan and alleviating paralysis in the Aβ1-42 transgenic Caenorhabditis elegans CL4176 model of AD, as shown in our previous study. Therefore, this study was aimed at exploring the neuroprotective effect of DhHP-6 in the APPswe/PSEN1dE9 transgenic mouse model of AD. DhHP-6 reduced the diameter and fiber structure of Aβ1-42 aggregation in vitro, as shown by dynamic light scattering and transmission electron microscope. DhHP-6 exerted its neuroprotective effect by inhibiting Aβ aggregation and plaque formation, and by reducing Aβ1-42 oligomers-induced neurotoxicity on HT22 (mouse hippocampal neuronal) and SH-SY5Y (human neuroblastoma) cells. In the AD mouse model, DhHP-6 significantly ameliorated cognitive decline and improved spatial learning ability in behavioral tests including the Morris water maze, Y-maze, novel object recognition, open field, and nest-building test. Moreover, DhHP-6 reduced the deposition of Aβ plaques in the cerebral cortex and hippocampus. More importantly, DhHP-6 restored the morphology of astrocytes and microglia, and significantly reduced the levels of pro-inflammatory cytokines. Our findings provide a basis for considering the non-toxic, peroxidase mimetic DhHP-6 as a new candidate drug against AD.

[INTENSIVE CARE OF COMPLICATED ACUTE PORPHYRIA]

The experience of anesthesia and intensive care departments of Hematological center Russia for intensive care management in 13 patients with acute porphyria, from 1996 till 2013 was summarized ion this pape4: Main causes of life-threatening complications of acute porphyria and its frequency were revealed Advantages of mechanical lung ventilation in respiratory failure, algorithms of clinical nutrition, correction of water-electrolyte disorders were represented. Importance of kinesiotherapy in successful treatment in these category of patients was revealed. It is shown that the whole complex of intensive care methods with the specific pathogenetical therapy brings success in 84,6 % of patients.

Hemin therapy improves kidney function in male streptozotocin-induced diabetic rats: role of the heme oxygenase/atrial natriuretic peptide/adiponectin axis

Diabetic nephropathy is characterized by elevated macrophage infiltration and inflammation. Although heme-oxygenase (HO) is cytoprotective, its role in macrophage infiltration and nephropathy in type 1 diabetes is not completely elucidated. Administering the HO inducer, hemin, to streptozotocin-diabetic rats suppressed renal proinflammatory macrophage-M1 phenotype alongside several proinflammatory agents, chemokines, and cytokines including macrophage inflammatory protein 1α (MIP-1α), macrophage-chemoattractant protein-1 (MCP-1), TNF-α, IL-1β, IL-6, nuclear factor-κB (NF-κB), and aldosterone, a stimulator of the inflammatory/oxidative transcription factor, NF-κB. Similarly, hemin therapy attenuated extracellular matrix/profibrotic proteins implicated in renal injury including fibronectin, collagen-IV, and TGF-β1 and reduced several renal histopathological lesions such as glomerulosclerosis, tubular necrosis, tubular vacuolization, and interstitial macrophage infiltration. Furthermore, hemin reduced markers of kidney dysfunction like proteinuria and albuminuria but increased creatinine clearance, suggesting improved kidney function. Correspondingly, hemin significantly enhanced the antiinflammatory macrophage-M2 phenotype, IL-10, adiponectin, HO-1, HO activity, and atrial natriuretic-peptide (ANP), a substance that abates TNF-α, IL-6, and IL-1β, with parallel increase of urinary cGMP, a surrogate marker of ANP. Contrarily, coadministering the HO inhibitor, chromium-mesoporphyrin with the HO-inducer, hemin nullified the antidiabetic and renoprotective effects, whereas administering chromium-mesoporphyrin alone abrogated basal HO activity, reduced basal adiponectin and ANP levels, aggravated hyperglycemia, and further increased MCP-1, MIP-1α, aldosterone, NF-κB, TNF-α, IL-6, IL-1β, proteinuria/albuminuria, and aggravated creatinine clearance, thus exacerbating renal dysfunction, suggesting the importance of the basal HO-adiponectin-ANP axis in renoprotection and kidney function. Collectively, these data suggest that hemin ameliorates diabetic nephropathy by selectively enhancing the antiinflammatory macrophage-M2 phenotype and IL-10 while concomitantly abating the proinflammatory macrophage-M1 phenotype and suppressing extracellular matrix/profibrotic factors with reduction of renal lesions including interstitial macrophage infiltration. Because aldosterone stimulate NF-κB, which activates cytokines like TNF-α, IL-6, IL-1β that in turn stimulate chemokines such as MCP-1 and MIP-1α to promote macrophage-M1 infiltration, the hemin-dependent potentiation of the HO-adiponectin-ANP axis may account for reduced macrophage infiltration and inflammatory insults in streptozotocin-diabetic rats.

Hemin therapy suppresses inflammation and retroperitoneal adipocyte hypertrophy to improve glucose metabolism in obese rats co-morbid with insulin-resistant type-2 diabetes

AIM

Visceral adiposity and impaired glucose metabolism are common patho-physiological features in patients co-morbid with obesity and type-2 diabetes. We investigated the effects of the heme-oxygenase (HO) inducer hemin and the HO blocker stannous-mesoporphyrin (SnMP) on glucose metabolism, adipocyte hypertrophy and pro-inflammatory cytokines/mediators in Zucker diabetic fatty (ZDF) rats, a model characterized by obesity and type-2 diabetes.

METHODS

Histological, morphological/morphometrical, Western immunoblotting, enzyme immunoassay, ELISA and spectrophotometric analysis were used.

RESULTS

Treatment with hemin enhanced HO-1, HO activity and cGMP, but suppressed retroperitoneal adiposity and abated the elevated levels of macrophage-chemoattractant protein-1 (MCP-1), ICAM-1, tumour necrosis factor-alpha (TNF-α), interleukin 6 (IL-6), IL-1β, NF-κB, c-Jun-NH2-terminal-kinase (JNK) and activating-protein (AP-1), with parallel reduction of adipocyte hypertrophy. Correspondingly, important proteins of lipid metabolism and insulin-signalling such as lipoprotein lipase (LPL), insulin-receptor substrate-1 (IRS-1), GLUT4, PKB/Akt, adiponectin, the insulin-sensitizing and anti-inflammatory protein and adenosine-monophosphate-activated protein kinase (AMPK) were significantly enhanced in hemin-treated ZDF rats.

CONCLUSION

Elevated retroperitoneal adiposity and the high levels of MCP-1, ICAM-1, TNF-α, IL-6, IL-1β, NF-κB, JNK and AP-1 in untreated ZDF are patho-physiological factors that exacerbate inflammatory insults, aggravate adipocyte hypertrophy, with corresponding reduction of adiponectin and deregulation of insulin-signalling and lipid metabolism. Therefore, the suppression of MCP-1, ICAM-1, TNF-α, IL-6, IL-1β, NF-κB, JNK, AP-1 and adipocyte hypertrophy, with the associated enhancement of LPL, adiponectin, AMPK, IRS-1, GLUT4, PKB/Akt and cGMP in hemin-treated ZDF are among the multifaceted mechanisms by which the HO system combats inflammation to potentiate insulin signalling and improve glucose and lipid metabolism. Thus, HO inducers may be explored in the search of novel remedies against the co-morbidities of obesity, dysfunctional lipid metabolism and impaired glucose metabolism.

The heme oxygenase system selectively suppresses the proinflammatory macrophage m1 phenotype and potentiates insulin signaling in spontaneously hypertensive rats

BACKGROUND

The mechanisms by which heme oxygenase (HO) improves glucose metabolism in essential hypertension are not completely understood. Because dysfunctional insulin signaling is associated with elevated inflammation and high cholesterol and triglycerides, we investigated the effects of HO on the proinflammatory macrophage M1 phenotype and the anti-inflammatory macrophage M2 phenotype in spontaneously hypertensive rats (SHRs). SHRs are a model of human essential hypertension with features of metabolic syndrome, including impaired glucose metabolism.

METHODS

Spectrophotometric analysis, enzyme immunoassay, enzyme-linked immunosorbent assay, and Western immunoblotting were used. HO was enhanced with hemin or inhibited with chromium-mesoporphyrin (CrMP).

RESULTS

Hemin suppressed inflammation by abating proinflammatory macro phage M1 phenotype (ED1) and chemokines such as macrophage chemoattractant protein 1 (MCP-1) and macrophage inflammatory protein 1 alpha (MIP-1α) while enhancing anti-inflammatory macrophage M2 phenotype by potentiating ED2, CD206, and CD14. Similarly, hemin improved insulin signaling by enhancing insulin receptor substrate 1 (IRS-1), IRS-2, phosphatidylinositol 3 kinase (PI3K), and glucose transporter 4 (GLUT4) but reduced total cholesterol and triglycerides. These effects were accompanied by increased HO-1, HO activity, and cyclic guanosine monophosphate (cGMP), whereas the HO inhibitor CrMP nullified the hemin effects. Importantly, the effects of the HO system on ED1, ED2, CD206, and CD14 in SHRs are novel.

CONCLUSIONS

Hemin abated inflammation in SHRs by selectively enhancing the anti-inflammatory macrophage M2 phenotype that dampens inflammation while suppressing the pronflammatory macrophage M1 phenotype and related chemokines such as MCP-1 and MIP-1α. Importantly, the reduction of inflammation, total cholesterol, and triglycerides was accompanied by the enhancement of important proteins implicated in insulin signaling, including IRS-1, IRS-2, PI3K, and GLUT4. Thus, the concomitant reduction of inflammation, total cholesterol and triglycerides and the corresponding potentiation of insulin signaling are among the multifaceted mechanisms by which the HO system improves glucose metabolism in essential hypertension.

Hemin, heme oxygenase-1 inducer, attenuates immobilization-induced skeletal muscle atrophy in mice

AIMS

The present study examined the effect of the heme oxygenase (HO)-1 inducer hemin on skeletal muscle atrophy induced by single limb immobilization in mice.

MAIN METHODS

Immobilization was conducted in the left hindlimb of C57BL/6 mice for 1 week and the right hindlimb was used as a control. Hemin (30 mg/kg) was administered intraperitoneally once a day during the immobilization period. Gastrocnemius muscles were used for analysis. Muscle weight was measured to quantify degree of atrophy, and exhaustion treadmill test was performed to assess muscle function.

KEY FINDINGS

Immobilization increased HO-1 protein levels in skeletal muscle, which was further increased by hemin treatment. Immobilization induced weight loss and a functional reduction in skeletal muscle, which were attenuated by hemin treatment. Gene expression and protein levels of MuRF1 and atrogin-1 were increased by immobilization and hemin treatment attenuated the increment. The phosphorylation of mTOR and p70S6k was decreased by immobilization in skeletal muscle and hemin had no effect on mTOR and p70S6k phosphorylation. Gene expression of the antioxidants superoxide dismutase and glutathione peroxidase 1 in skeletal muscle was reduced by immobilization and hemin treatment recovered the reduction. Immobilization increased levels of carbonylated protein and nitrotyrosine in skeletal muscle, which was reversed by hemin treatment. Gene expression of inflammatory cytokines was increased by immobilization and was normalized as a result of hemin treatment.

SIGNIFICANCE

These results suggest that hemin attenuates immobilization-induced skeletal muscle atrophy through the suppression of protein degradation via its anti-oxidant and anti-inflammatory properties.

Hemin exerts multiple protective mechanisms and attenuates dextran sulfate sodium-induced colitis

OBJECTIVE

Inflammatory bowel disease (IBD) is characterized by recurrent and severe gastrointestinal inflammation. Activation of inflammatory cells, such as TH17 lymphocytes, and/or deficiency of regulatory T cells (Treg) are responsible for the pathogenesis of IBD. As an acute phase reactant, heme oxygenase-1 (HO-1) has been shown to play an anti-inflammatory and immunomodulatory role in many disease processes. In this study, we used a dextran sulfate sodium (DSS)-induced murine colitis model to investigate the effect of upregulating HO-1 by hemin on the development of colonic inflammation.

MATERIALS AND METHODS

The mice were enterically challenged with 4% DSS. In addition, some mice were intraperitoneally administered with hemin or Sn-protoporphyrin (SnPP) on days 0, 1, and 6 after DSS treatment. The severity of colitis was evaluated by daily monitoring of weight change and diarrhea. At the end of the experiment, the colon, spleen, and mesenteric lymph nodes were harvested for histology and various immunological assays.

RESULTS

Compared to control groups, DSS challenge markedly induced HO-1 expression in the colon epithelium. Upregulation of HO-1 by hemin was further correlated with attenuation of DSS-induced colitis. In contrast, inhibition of endogenous HO-1 by SnPP aggravated the colitis. To further assess the anti-inflammatory mechanisms, we examined whether hemin enhanced the proliferation of Treg cells and suppressed the production of interleukin (IL)-17. Flow cytometry analysis revealed that hemin markedly expanded the CD4 + CD25 + Foxp3+ Treg population. Moreover, hemin attenuated IL-17 and TH17-related cytokines. This inhibition coincided with the attenuation of DSS-induced colitis. Finally, terminal deoxynucleotidyl transferase deoxyuridine triphosphate nick end-labeling assay showed that hemin treatment markedly reduced programmed cell death of colonic epithelium, indicating that hemin exerts a modulatory effect on the induction of Treg, IL-17, and apoptosis.

CONCLUSIONS

These results demonstrate that upregulation of HO-1 by hemin ameliorated experimental colitis. Moreover, our study suggests a broader protective mechanism of hemin.

Up-regulating the hemeoxygenase system enhances insulin sensitivity and improves glucose metabolism in insulin-resistant diabetes in Goto-Kakizaki rats

Insulin-mediated signal transduction is positively correlated to adiponectin, adenosine monophosphate-activated protein kinase (AMPK), and glucose-transporter-4 (GLUT4) but negatively to oxidative/inflammatory mediators such as nuclear factor-kappaB, activating-protein (AP)-1, AP-2, and c-Jun-N-terminal-kinase. Although hemeoxygenase (HO) suppresses oxidative insults, its effects on insulin-sensitizing agents like AMPK and GLUT4 remains unclear and were investigated using Goto-Kakizaki rats (GK), a nonobese insulin-resistant type-2 diabetic model. HO was induced with hemin or inhibited with chromium mesoporphyrin (CrMP). The application of hemin to GK rats evoked a 3-month antidiabetic effect, whereas the HO-inhibitor, CrMP, exacerbated hyperglycemia and nullified insulin-signaling/glucose metabolism. Interestingly, the antidiabetic was accompanied by a paradoxical increase of insulin alongside the potentiation of insulin-sensitizing agents such as adiponectin, AMPK, and GLUT4 in the gastrocnemius muscle. Furthermore, hemin enhanced mediators/regulators of insulin signaling like cGMP and cAMP and suppressed oxidative insults by up-regulating HO-1, HO activity, superoxide dismutase, catalase, and the total antioxidant capacity in the gastrocnemius muscle. Accordingly, oxidative markers/mediators including nuclear factor-kappaB, AP-1, AP-2, c-Jun-N-terminal-kinase, and 8-isoprostane were abated, whereas CrMP annulled the cytoprotective and antidiabetic effects of hemin. Correspondingly, ip glucose tolerance, insulin tolerance, and homeostasis model assessment insulin resistance analyses revealed improved glucose tolerance, reduced insulin intolerance, enhanced insulin sensitivity, and reduced insulin resistance in hemin-treated GK rats. In contrast, CrMP, abolished the insulin-sensitizing effects and restored and/or exacerbated insulin resistance. Our study unveils a 3-month enduring antidiabetic effect of hemin and unmasks the synergistic interaction among the HO system, adiponectin, AMPK, and GLUT4 that could be explored to enhance insulin signaling and improve glucose metabolism in insulin-resistant diabetes.

The heme oxygenase system abates hyperglycemia in Zucker diabetic fatty rats by potentiating insulin-sensitizing pathways

Emerging evidence indicates that aldosterone causes oxidative stress by stimulating proinflammatory/oxidative mediators, including nuclear factor-kappaB, activating protein (AP-1), and c-Jun N-terminal kinase. Thus, in insulin-resistant type 2 diabetes (T2D), oxidative stress generated by hyperglycemia and aldosterone would potentiate the oxidative destruction of tissue and important regulators of glucose metabolism like adiponectin and insulin. Although heme oxygenase (HO)-1 is cytoprotective, its effects on T2D have not been fully characterized. Here we report an enduring antidiabetic effect of the HO inducer, hemin, on Zucker diabetic-fatty rat (ZDF), a model of insulin-resistant T2D. Chronically applied hemin to ZDF reduced and maintained significantly low fasting and postprandial hyperglycemia for 4 months after therapy. The antidiabetic effect was accompanied by enhanced HO activity, catalase, cyclic GMP, bilirubin, ferritin, total antioxidant capacity, and insulin. In contrast, reduced aldosterone alongside markers/mediators of oxidative stress, including 8-isoprostane, c-Jun N-terminal kinase, nuclear factor-kappaB, AP-1, and AP-2 were observed. Interestingly, in hemin-treated ZDF, inhibitory proteins of insulin-signaling, such as glycogen synthase kinase-3 and protein-tyrosine phosphatase-1B were reduced, whereas agents that promote insulin signaling including adiponectin, cAMP, AMP-activated protein kinase, aldolase-B, and glucose transporter-4 (GLUT4), were robustly increased. Correspondingly, hemin improved ip glucose tolerance, reduced insulin intolerance, and lowered insulin resistance (homeostasis model assessment of insulin resistance), and the inability of insulin to enhance GLUT4 was overturned. These results suggest that the suppression of hyperglycemia and aldosterone-induced oxidative stress alongside the potentiation of insulin-sensitizing pathways may account for the 4-month enduring antidiabetic effect. The synergistic interaction between the HO system, aldolase-B, adiponectin, AMP-activated protein kinase, and GLUT4 may be explored for novel strategies against postprandial/fasting hyperglycemia and insulin-resistant T2D.

Transitory renal failure following rapid administration of a relatively large amount of hematin in a patient with acute intermittent porphyria in clinical remission

Transitory renal failure occurred in a patient with acute intermittent porphyria in clinical remission following i.v. administration of 1 000 mg hematin. The clinical and biochemical picture suggested "acute tubular necrosis", which was followed by a prompt and complete return of renal function without any late sequelae. The renal failure is thought to have resulted from the presence of circulating free hematin, formed as a result of rapid administration of such a relatively large amount. Such a complication has not occurred in patients given hematin for acute porphyric relapse, in whom much smaller amounts have been infused.

Heme oxygenase system enhances insulin sensitivity and glucose metabolism in streptozotocin-induced diabetes

Hyperglycemia-induced oxidative stress is a common phenomenon in diabetes. Since oxidative stress depletes adiponectin and insulin levels, we investigated whether an upregulated heme oxygenase (HO) system would attenuate the oxidative destruction of adiponectin/insulin and improve insulin sensitivity and glucose metabolism in streptozotocin (STZ)-induced type 1 diabetes. HO was upregulated with hemin (15 mg/kg ip) or inhibited with chromium mesoporphyrin (CrMP, 4 micromol/kg ip). Administering hemin to STZ-diabetic rats reduced hyperglycemia and improved glucose metabolism, whereas the HO inhibitor CrMP annulled the antidiabetic effects and/or exacerbated fasting/postprandial hyperglycemia. Interestingly, the antidiabetic effects of hemin lasted for 2 mo after termination of therapy and were accompanied by enhanced HO-1 and HO activity of the soleus muscle, along with potentiation of plasma antioxidants like bilirubin, ferritin, and superoxide dismutase, with corresponding elevation of the total antioxidant capacity. Importantly, hemin abated c-Jun NH2-terminal kinase (JNK), a substance known to inhibit insulin biosynthesis, and suppressed markers/mediators of oxidative stress including 8-isoprostane, nuclear-factor (NF)-kappaB, activating protein (AP)-1, and AP-2 of the soleus muscle. Furthermore, hemin therapy significantly attenuated pancreatic histopathological lesions including acinar cell necrosis, interstitial edema, vacuolization, fibrosis, and mononuclear cell infiltration. Correspondingly, hemin increased plasma insulin and potentiated agents implicated in insulin sensitization and insulin signaling such as adiponectin, adenosine monophosphate-activated protein kinase (AMPK), cAMP, cGMP, and glucose transporter (GLUT)4, a protein required for glucose uptake. These were accompanied by improved glucose tolerance [intraperitoneal glucose tolerance text (IPGTT)], decreased insulin intolerance [intraperitoneal insulin tolerance test (IPITT)], and reduced insulin resistance [homeostasis model assessment of insulin resistance (HOMA-IR) index], whereas CrMP nullified the hemin-dependent antidiabetic and insulin-sensitizing effects. In conclusion, by concomitantly enhancing insulin and paradoxically potentiating insulin sensitivity, this study unveils a novel, unique, and long-lasting antidiabetic characteristic of upregulating HO with hemin that could be exploited against insulin-resistant and insulin-dependent diabetes.

[Effect of hemin on severe acute pancreatitis-associated lung injury in rats and its mechanism]

OBJECTIVE

To investigate the effect of hemin on lung injury following severe acute pancreatitis (SAP) in rats and to explore its rudimentary mechanism.

METHODS

Thirty-six rats were randomly divided into 3 groups: a control group, a SAP model group, and a hemin-pretreated group. Rats were sacrificed 12 hours after inducing SAP model. The pathological changes of the pancreas and lungs were observed under light microscope. Expression of heme oxygenase (HO-1) mRNA was detected by reverse transcription-polymerase chain reaction (RT-PCR), NF-kappaB activity in the lung tissues was detected by enzyme linked immunosorbent assay (ELISA), and the serum levels of TNF-alpha and IL-6 were measured by ELISA.

RESULTS

HO-1 was induced during experimental SAP, NF-kappaB activity in the lung tissues was elevated after the induction of SAP and the serum levels of TNF-alpha and IL-6 were significantly elevated. Hemin further upregulated the expression of HO-1 mRNA, decreased NF-kappaB activity drastically, and inhibited the serum levels of TNF-alpha and IL-6 significantly (P < 0.05). Hemin could treat SAP by alleviating the pancreatic and lung injury.

CONCLUSION

Hemin moderates the inflammatory reaction and decreases the lung injury following SAP, the mechanism of which may be closely related to the upregulation of expression of HO-1 mRNA, the inhibitory effect on NF-kappaB, and adjustment of cytokines.

Protective effects of hemin pretreatment combined with ulinastatin on septic shock in rats

BACKGROUND

Urinary trypsin inhibitor inhibits the enhanced production of pro-inflammatory molecules. Hemeoxygenase-1 induction protects against ischemia/reperfusion injury, oxidative stress, inflammation, transplant rejection, apoptosis, and other conditions. However, it is unknown if a combined hemin and ulinastatin pretreatment could result in protective effects for septic shock. In this study, we investigated the role of hemin pretreatment combined with ulinastatin on septic shock in rats.

METHODS

Eighty healthy, male Sprague-Dawley rats were randomly divided into four groups: group S, group H, group U and group HU. Groups S and U received 1 ml normal saline intraperitoneally, while groups H and HU both received 1 ml (100 mg /kg) hemin. Twenty-four hours later, 0.5 ml (10 mg/kg) E. coli lipopolysaccharide was injected intravenously to replicate the experimental model of septic shock. After an initial 25% decrease in the mean arterial pressure, corresponding to time point 0, groups HU and U received 0.5 ml 10 000 U/kg ulinastatin intravenously, and the others received 0.5 ml normal saline.

RESULTS

The number of deaths in groups H and U was lower than that in the group S (P < 0.05), and was higher than that in group HU (all P < 0.05) respectively. The mean arterial pressure (MAP) in the group S was significantly greater than that in group H (P < 0.05), and was lower than that in group HU and group U (P < 0.05). The plasma levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), creatinine (Cr) and blood urea nitrogen (BUN), the malondial-dehyde (MDA) of liver, kidney and lung, and the lung Evans blue (EB) contents in groups H and U, were greater than that in group HU (all P < 0.05), and were lower than that in group S (all P < 0.05). In contrast, the plasma levels of CO in groups H and HU were higher than that in groups S and U (all P < 0.05), and SOD of liver, kidney and lung in groups H and U were higher than that in group S, and were lower than that in group HU (all P < 0.05). The levels of TNF-alpha, IL-6, IL-8 and beta-glucuronidase (GCD) activity of plasma in groups U and HU were lower than those in groups H and S, all having a P < 0.05, while there were no significant differences between group H and group S, or between group HU and group U (all P > 0.05). The HO-1 mRNA and HO-1 protein levels from hepatic, renal, and pulmonary tissue in groups S and U were lower than those in groups H and HU (all P < 0.05), but there were no significant differences between groups S and U, or between groups H and HU (all P > 0.05). The HO-2 mRNA and HO-2 protein were not significantly different among the four groups (all P > 0.05).

CONCLUSIONS

Combined pretreatment with hemin and ulinastatin in septic shock rats results in an improved response by the upregulation of HO-1 protein followed by increasing CO with resistance to increased oxidative stress, restraining the release of inflammatory mediators, and inhibiting beta-GCD activity.

Heme oxygenase-1 inducer hemin prevents vascular thrombosis

Hemin is a heme oxygenase-1 (HO-1) inducer which provides endogenous carbon monoxide known for playing roles in cell proliferation, inflammation or aggregation process. The objective of the current study was to examine the effect of prophylactic treatment with hemin in a thrombosis vascular model. Three groups of Wistar rats, control (n = 6), hemin (n = 6) and hemin + HO-1 inhibitor (n = 6), were used for this study. Hemin-treated animals received hemin (50 mg/kg/d; I.P.) for seven days and HO-1 inhibitor group received hemin at the same dose and SnPP IX (60 mg/kg/d; I.P.). All animals were exposed to electric stimulation of the left carotid according to Kawasaki's procedure to induce reproducible thrombus formation. The hemin treatment did not induce blood pressure disturbance. Effects of hemin on vascular thrombosis were quantified by histopathology and its influence on haemostasis was assessed by measuring prothrombin time (PT), activated partial thromboplastin time (APTT) and blood parameters at the end of treatment. The HO-1 mRNA and protein level variation were also checked out. Results showed that chronic treatment with hemin significantly (p < 0.01) reduced the vascular occlusion degree when compared to control and hemin SnPP groups with 7.2 +/- 4.6 vs. 71.1 +/- 14.7 and 74.0 +/- 8.8%, respectively. Moreover, we observed significant (p < 0.05) perturbations of blood parameters in hemin-treated and hemin-SnPP treated rats. Interestingly, hemin treatment did not significantly increase both PT and APTT. Finally, the HO-1 mRNA and protein levels were increased in hemin-treated carotid artery. In conclusion, hemin by inducing HO-1 expression may be a preventive agent against clinical disorders associated to an increased risk of thrombosis events and may limit haemorrhagic risks.

Liver transplantation for porphyria: who, when, and how?

Porphyrias are a heterogenous group of diseases that may result in disabling or life threatening neurovisceral symptoms and/or cutaneous photosensitivity. In acute intermittent porphyria, the clinical features, particularly neurological symptoms, may be life-threatening and disabling. Conventional treatment with human hemin, though effective in reducing symptoms, does not reverse neuropathy when structural nerve damage has occurred and may cause intense phlebitis. Liver transplantation (LT) may be considered as treatment for those with repeated life-threatening acute attacks resulting in poor quality of life, requirement of ventilatory support, and progressive loss of venous access due to hemin infusion. Patients with variegate porphyria (VP) present after puberty with neurovisceral symptoms and skin manifestations. LT resolved VP in the 1 patient reported in the literature. Aminolaevulinic acid dehydratase deficient porphyria is a rare autosomal recessive disorder and a child who presented with failure to thrive and required transfusions and parenteral nutrition did not improve with LT. In erythropoietic protoporphyria (EPP), there is excessive production of protoporphyrin in the bone marrow. Protoporphyrin is hepatotoxic and pigment loading of hepatocytes and bile canalicular sludging may result in progressive cholestasis and cirrhosis. LT is beneficial for such patients with end-stage liver disease. Perioperative management includes use of filters on operative lights to prevent skin burns and intestinal perforation. Other concerns include development of neuropathy, biliary complications, and recurrent liver disease. This review addresses the rationale, patient selection, evaluation, management issues, and technique of performing LT in various types of porphyria.

Hemin, an Inducer of Heme Oxygenase-1, Lowers Intraocular Pressure in Rabbits

AIM

Carbon monoxide (CO) generated from heme may induce vasodilation and exert cyto-protective properties in the eye. This study was undertaken to investigate the effects of hemin, a potent inducer of heme oxygenase-1 (HO-1), on models of ocular hypertension in rabbits.

METHODS

Ocular hypertension was induced by injecting alpha-chymotrypsin in both eyes under local anesthesia. Only rabbits with an intraocular pressure (IOP) of 25 mmHg or more were used. The dose-response study of the hemin effect on IOP was made by an intravenous injection of the drug (50, 75, and 100 mg/kg) and subsequent IOP monitoring every 6 h. A separate set of animals was pretreated with the HO-1 inhibitor, zinc protoporphyrin-IX (ZnPP-IX, 0.1 mg/kg) 6 h before the vehicle or a 100-mg/kg hemin injection. Ocular hypertension was also obtained by the subconjunctival injection of betamethasone 21-phosphate disodium (4 mg/mL) in both eyes every week for 4 weeks. Only animals with an IOP of 30 mmHg or more were included in the experimental session. A group of these animals was pretreated with ZnPP-IX (0.1 mg/kg) 6 h before the vehicle or a 100-mg/kg hemin injection, and IOP was assessed every 6 hours.

RESULTS

Hemin caused a significant dose-related reduction of IOP in rabbits with alpha-chymotrypsin-induced ocular hypertension. No significant effect was observed in the normotensive eyes of the control animals or on pupil diameter. Pretreatment with the HO-1 inhibitor, ZnPP-IX, abolished the decrease of IOP that was induced by the maximum dose of hemin (100 mg/kg). A similar reduction in IOP was observed in those rabbits with betamethasone-induced ocular hypertension who were treated with 100 mg/kg of hemin. Furthermore, pretreatment with ZnPP-IX prevented the hemin effect on IOP.

CONCLUSIONS

The induction of HO-1 by hemin leads to a reduction of IOP in the alpha-chymotrypsin and betamethasone models of ocular hypertension. These results suggest an involvement of CO in the regulation of ocular pressure in rabbits.

Effect of NO donor sodium nitroprusside on lipopolysaccharide induced acute lung injury in rats

Nitric oxide (NO) donor-sodium nitroprusside (SNP) mitigates acute lung injury (ALI), but the mechanism of this protection is incompletely known. We investigated the effect of SNP on lipopolysaccharide (LPS)-induced ALI in rats. Forty-eight male Wistar rats were randomly assigned into six groups: the sham-operation group (S group), the LPS instillation group (LPS group), the haemin, a haeme oxygenase-1 (HO-1) inducer, pretreatment group (HM group), the haemin pretreatment plus LPS instillation group (HM+LPS group), the SNP alone and SNP plus LPS treatment groups. Macroscopic and histopathological examinations and immunohistochemistry analysis were performed for the lung specimens 8h after LPS instillation. Intratracheal administration of LPS induced significant expressions of the inducible isoform of NO synthase (iNOS) and HO-1, while both haemin pretreatment and SNP treatment increased the expression of HO-1 and prevented the expression of iNOS. In the LPS group, the wet-dry weight ratio (W/D), bronchoalveolar lavage fluid (BALF) protein, and lung malondialdehyde (MDA) content were significantly higher than those in the sham-operation group, which were reversed by the pretreatment with haemin or administration of SNP. These results suggest that HO-1 plays a protective role against LPS-induced acute lung injury, which may be achieved at least in part, via inactivating the iNOS/NO system that is involved in the pathophysiological process of LPS-induced acute lung injury. The nitric oxide (NO) donor-SNP ameliorates LPS-induced ALI, which may be related to the induction of HO-1 and the subsequent inhibition of iNOS.

Protective effects of heme-oxygenase expression against endotoxic shock: inhibition of tumor necrosis factor-alpha and augmentation of interleukin-10

BACKGROUND

Heme-oxygenase (HO)-1 acts as an inducible defense against oxidative stress and could play an important role in inflammation models, providing protection against oxidative stress and systemic inflammatory response. The objective of this study was to improve the role of HO-1 on systemic inflammatory response in an endotoxic shock model.

METHODS

Five groups of animals were used: control group; lipopolysaccharide (LPS) group, animals received LPS 5 mg/kg; hemin + LPS group, animals received pretreatment with hemin, used to induce HO-1 expression; Zn-PP group, animals received Zn-PP, a specific inhibitor of HO-1 activity and hemin group. At the end of the experiment, tissue and blood samples were isolated for the measurement of HO-1 mRNA expression, biochemical measurements, and cytokine measurements.

RESULTS

HO-1 messenger RNA expression and protein were induced to a larger extent in LPS group in distal organs. Hemin pretreatment induced a significant decrease oxidative stress and tumor necrosis factor-alpha plasma levels with a significant increase of interleukin-10 plasma levels. Pulmonary injury was markedly limited after hemin. Onset of lethality in LPS group occurred at H6, and was delayed until H10 with hemin. Inhibition of HO-1 activity by Zn-PP administration abolished the beneficial effect of hemin-pretreatment.

CONCLUSIONS

Early HO-1 expression may modulate systemic inflammatory response and limit end-organ injury in endotoxic shock model.

[Protective effect of heme oxygenase-1 and its reaction product, carbon monoxide on acute liver injury induced by carbon tetrachloride in rats]

OBJECTIVE

To investigate the protective role of heme oxygenase-1 and its reaction product, carbon monoxide against acute liver injury induced by carbon tetrachloride in rats.

METHODS

Thirty male Sprague-Dawley rats were randomly divided into six groups with five in each. The control group received a single dose of corn oil injection. Carbon tetrachloride was injected intraperitoneally (i.p) to establish acute liver injury models in rats. Hemin(50 micromol/kg) was administered i.p. 12 hours before CCl(4) treatment, with an aim to induce HO-1 protein expression in the liver of rats. Carbon monoxide was injected i.p. 12 hours prior to CCl(4) injection, resulting in about 8%-12% carboxyhemoglobin concentration in vivo. The expression of HO-1 in the liver of hemin-treated rats was determined by western blot method at different time points. At 24 h after carbon tetrachloride administration, all rats were sacrificed to collect blood samples for the examination of ALT, AST levels and to remove liver tissues for analysis of MDA concentration, SOD activity and caspase-3 activity as well as TNF-alpha contents. In addition, histopathological changes were investigated and hepatocyte apoptosis was detected by TUNEL method.

RESULTS

The administration of carbon tetrachloride to rats caused a marked hepatic damage, characterized by significant elevation of serum ALT, AST levels(2 136.3+/-163.4 U, 1 422.7+/-221.7 U) and liver MDA content(5.28+/-0.93 micromol/g), caspase-3 activity (optical density value 4.69+/-1.02) and TNF-alpha level(256.3+/-27.3 ng/L) combined with a remarkable reduction in liver SOD activity (45.9+/-14.8 U/mg) as compared with the control rats. Histopathological observations revealed severe damage in the liver and prominent hepatocyte apoptosis took place in CCl(4) -treated rats. However, pretreatment with hemin could induce high expression of HO-1 protein and exert potent protective effects against liver injury, as demonstrated by a significant decrease in ALT, AST levels(287.1+/-24.3 U, 246.2+/- 21.7 U) and MDA concentration(3.27+/-1.34 micromol/g), reduction in caspase-3 activity(optical density value 2.49+/-1.47) and TNF-alpha level(132.6+/-19.5 ng/L), as compared with the CCl(4) -treated rats. Moreover, hepatocyte apoptosis and liver injury were both attenuated remarkably in the liver of rats pretreated with hemin. In contrast to hemin administration, single injection of exogenous CO produced the same protective effects, as indicated by the remarkable reduction of ALT, AST levels and caspase-3 activity and TNF-alpha levels.

CONCLUSION

The above results suggest that HO-1/CO system has a potent protective effect on acute liver injury induced by carbon tetrachloride in rats. Induction of HO-1 expression and low concentration of CO can inhibit the progress of hepatic damage, which might be due to the alleviation of lipid peroxidation and reduction of caspase-3 activity or inhibition of TNF-alpha level.

Open-label study of hemin for acute porphyria: clinical practice implications

BACKGROUND

The acute porphyrias are rare inherited diseases characterized by acute episodes of life-threatening symptoms. Hemin was approved for treating these disorders in 1983. This open-label study of hemin therapy, conducted to demonstrate the safety of hemin manufactured in a new facility, is the largest to date and provides an overview of the use of hemin in clinical practice in the United States.

METHODS

During 8 months when hemin was available only through study participation, 130 patients with a clinical diagnosis of acute porphyria received hemin as regularly prescribed by their doctor. Laboratory information and data on use of hemin for acute and prophylactic treatment were analyzed from case report forms.

RESULTS

Hemin was administered to 111 patients for treatment of 305 acute attacks and to 40 patients for prophylaxis (usually by weekly or biweekly infusions). Diagnostic laboratory findings reported for 69 patients were confirmatory in only 26. Hemin was regarded as effective for all attacks in 73% of patients. Doses for acute attacks were less than the recommended 3-4 mg/kg/day in 20% of patients. Among 31 patients who received hemin prophylaxis for >1 month, 68% did not require subsequent hemin treatment for acute attacks. Most adverse events were attributed to porphyria and not treatment, and were more common in patients treated for acute attacks rather than prophylaxis.

CONCLUSIONS

Safety and perceived efficacy of hemin were consistent with previous studies. Physician education is needed regarding use of diagnostic tests and recommended dosing. Preventive regimens are common and deserve further study.

Sustained normalization of high blood pressure in spontaneously hypertensive rats by implanted hemin pump

Treatment of established hypertension, especially for prolonged control of this pathogenic process, represents a great challenge. To upregulate the expression of heme oxygenase (HO) to lower blood pressure (BP) of spontaneously hypertensive rats (SHRs), we administered hemin to 12-week-old adult SHRs through subcutaneously implanted osmotic minipumps for 3 consecutive weeks (the hemin protocol). Systolic BP of SHRs was normalized 123+/-2 mm Hg (n=20; P<0.001) and this normalization maintained for 9 months after the removal of hemin pumps. At the end of the hemin protocol, HO-1 expression, HO activity, soluble guanylyl cyclase expression, and cGMP content were all increased, but phosphodiesterase-5 expression was downregulated in the mesenteric arteries. The hemin protocol also reversed SHR-featured arterial eutrophic inward remodeling and decreased expression levels of vascular endothelial growth factor. These changes lasted 9 months after the hemin protocol. Our study, thus, formulates a novel hemin protocol that will not only normalize BP in SHRs with established hypertension but, more importantly, will also provide long-lasting antihypertension protection. Sustained upregulation of HO-1-linked signaling pathways and reversal of vascular remodeling in peripheral blood vessels mediate likely the antihypertensive effect of the hemin protocol.

Long-term effect of heme oxygenase (HO)-1 induction in glomerular immune injury

In a rat model of macrophage-dependent glomerular immune injury induced by administration of antibody against the glomerular basement membrane (anti-GBM), the authors assessed the anti-proteinuric effect of Heme Oxygenase-1 (HO-1) induction. Rats received anti-GBM antibody alone, anti-GBM antibody and treatment with the HO-1 inducer, hemin, or non-immune serum (controls). Urine protein, creatinine, and nitrite/nitrate excretion were measured on days 5, 7, and 14 after administration of the anti-GBM antibody. In hemin-treated animals with anti-GBM antibody-induced immune injury, HO-1 immunolocalized in macrophages infiltrating glomeruli and in tubular epithelial cells. In these animals, proteinuria was decreased. There was also a decrease in blood urea nitrogen (BUN) levels without a change in serum creatinine or systemic blood pressure. The observations establish the anti-proteinuric effect of hemin induction. This effect could be mechanistically linked to blunting of the ability of infiltrating macrophages to cause injury or to changes in tubular handling of filtered protein.

Hemin prevents cardiac and diaphragm mitochondrial dysfunction in sepsis

Free radical-mediated mitochondrial dysfunction may play a role in the genesis of sepsis-induced multiorgan failure. Several cellular defenses protect against free radicals, including heme oxygenase. No previous study has determined if measures that increase heme oxygenase levels reduce mitochondrial dysfunction following endotoxin. The purpose of the present study was to determine if mitochondrial dysfunction following endotoxin (LPS) administration can be attenuated by administration of hemin, a pharmacological inducer of heme oxygenase. Blood pressure, heart rate, cardiac and diaphragm mitochondrial function, plasma nitrite/nitrate levels, and tissue markers of free radical generation were compared among rats given saline, LPS, hemin, or a combination of hemin and LPS. Endotoxin (LPS) administration produced large reductions in mitochondrial function (e.g., ATP production rate decreased in both tissues, P < 0.001). Administration of hemin increased tissue heme oxygenase levels, ablated LPS-induced alterations in mitochondrial function, attenuated LPS-induced increases in plasma nitrite/nitrate levels, and prevented LPS-mediated increases in tissue markers of free radical generation. These data indicate that tissue heme oxygenase levels modulate the degree of LPS-induced mitochondrial dysfunction. Measures that increase heme oxygenase levels may provide a means of reducing sepsis-induced mitochondrial dysfunction and tissue injury.

Monitoring circulatory heme level in hemin therapy for lowering blood pressure in rats

Hemin and other heme derivatives, e.g. heme-L-lysinate (HLL) and heme-L-arginate, have been used extensively to upregulate expression of heme oxygenase and production of endogenous carbon monoxide. Hemin administration has been shown to markedly decrease high blood pressure in spontaneously hypertensive rats (SHR), but not in normotensive Wistar-Kyoto or Sprague Dawley (SD) rats. While methodology to measure serum heme levels has been established long ago, metabolism of the injected hemin or heme derivatives when used to lower blood pressure has not been investigated. In this study, metabolism of hemin or HLL after injected into the rat was monitored by measuring changes in circulatory heme levels. SHR (12-20 weeks old) had significantly higher blood pressure than age-matched SD rats. In both strains, serum heme level was negligible. Hemin or HLL injection (15 mg/kg/day, i.p.) for 5-13 days significantly lowered blood pressure of 12-weeks SHR. High blood pressure was not lowered in SHR older than 20 weeks until hemin or HLL injection period was beyond 5 days. This anti-hypertensive effect of hemin and HLL was synchronized with an increase in serum heme level, from undetectable to 4.3 micromol/l. On the other hand, hemin or HLL had no effect on blood pressure of age-matched SD rats, despite serum heme level rose to the same extent as in the treated SHR. There was no significant difference between hemin and HLL injections in terms of changes in blood pressure and serum heme level in all rats. Our study for the first time correlated changes in serum heme levels with blood pressure levels after injection of hemin or HLL in SHR and SD rats. Hemin and HLL had similar effects on blood pressure change and serum heme level. By determining serum heme levels following the administration of hemin or HLL, we can better understand mechanisms for the blood pressure lowering effect of hemin therapy. Application of this heme monitoring technology will also pave the way for clinical application of hemin therapy in treatment of different types of hypertension pathologies.

Influence of heme-based solutions on stress protein expression and organ failure after hemorrhagic shock

OBJECTIVE

Hemoglobin-based oxygen carriers (e.g., diaspirin-cross-linked hemoglobin [DCLHb] and hemoglobin glutamer-200 [HbG]) may have potential in the treatment of hemorrhagic shock. The nitric oxide scavenging and direct vasoconstrictive side effects of free hemoglobin of currently available preparations may increase organ injury after shock in contrast to non-oxygen-carrying heme solutions (e.g., hemin arginate [HAR]). However, both classes of substances might induce the protective enzyme heme oxygenase (HO)-1, particularly in the liver. The aim of the study was to assess the role of pretreatment with DCLHb, HbG, or HAR on HO-1 expression and organ injury after hemorrhagic shock.

DESIGN

Prospective controlled laboratory study.

SETTING

Animal research laboratory at a university hospital.

SUBJECTS

Male Sprague-Dawley rats (200-300 g body weight, n = 5-12/group).

INTERVENTIONS

Twenty-four hours after different doses of DCLHb, HbG (each 1, 2, or 3 g/kg of body weight), or HAR (5, 25, or 75 mg/kg of body weight), the protein expression of HO-1 and heat shock protein-70 in liver, kidney, heart, lungs, and aorta was determined. Twenty-four hours after pretreatment with DCLHb, HbG, or HAR, rats were subjected to hemorrhage (mean arterial blood pressure, 35-40 mm Hg for 1 or 2 hrs)/resuscitation (5 or 4 hrs, respectively). Animals treated with Ringer's solution (30 mL/kg of body weight) served as controls. In additional experiments, HO activity was blocked with tin mesoporphyrin-IX.

MEASUREMENTS AND MAIN RESULTS

DCLHb, HbG, and HAR dose-dependently induced HO-1 protein but not heat shock protein-70. Pretreatment with DCLHb or HbG shortened the onset of decompensation in shock (DCLHb, 40 +/- 11 mins; HbG, 36 +/- 4 mins) compared with vehicle (68 +/- 4 mins, p < .05) and HAR pretreatment (81 +/- 7 mins, p < .05). High doses of DCLHb pretreatment increased mortality (2 hrs of shock, 80%; p < .05 vs. vehicle or HAR). Pretreatment with HAR led to higher shed blood volumes (p < .05) and higher hepatocellular ATP levels (2 hrs of shock, p < .05 vs. DCLHb and HbG). Blockade of HO activity by tin mesoporphyrin-IX abolished the protection mediated by HAR.

CONCLUSIONS

Although DCLHb, HbG, and HAR induce HO-1 in the absence of an unspecific stress response, only HAR pretreatment protects against shock-induced organ failure. Although the underlying mechanisms of positive HAR priming are not completely understood, the induction of HO-1 expression and the lack of nitric oxide scavenging through HAR may play an important role.

Recommendations for the diagnosis and treatment of the acute porphyrias

The acute porphyrias, 4 inherited disorders of heme biosynthesis, cause life-threatening attacks of neurovisceral symptoms that mimic many other acute medical and psychiatric conditions. Lack of clinical recognition often delays effective treatment, and inappropriate diagnostic tests may lead to misdiagnosis and inappropriate treatment. We review the clinical manifestations, pathophysiology, and genetics of the acute porphyrias and provide recommendations for diagnosis and treatment on the basis of reviews of the literature and clinical experience. An acute porphyria should be considered in many patients with unexplained abdominal pain or other characteristic symptoms. The diagnosis can be rapidly confirmed by demonstration of a markedly increased urinary porphobilinogen level by using a single-void urine specimen. This specimen should also be saved for quantitative measurement of porphobilinogen, 5-aminolevulinic acid, and total porphyrin levels. Intravenous hemin therapy, started as soon as possible, is the most effective treatment. Intravenous glucose alone is appropriate only for mild attacks (mild pain, no paresis or hyponatremia) or until hemin is available. Precipitating factors should be eliminated, and appropriate supportive and symptomatic therapy should be initiated. Prompt diagnosis and treatment greatly improve prognosis and may prevent development of severe or chronic neuropathic symptoms. We recommend identification of at-risk relatives through enzymatic or gene studies.

Acute intermittent porphyria presenting as a diffuse encephalopathy

Although acute intermittent porphyria presents with dramatic neurological findings, the diagnosis is difficult. An 18-year-old woman had a clinical picture of porphyric encephalopathy. Magnetic resonance (MR) imaging demonstrated multiple large contrast-enhancing subcortical white matter lesions, which regressed with glucose and hematin infusions. Diffusion-weighted MR imaging was normal, and MR spectroscopy excluded acute demyelination or tissue necrosis. MR findings of acute intermittent porphyria can differ from those in posterior reversible encephalopathy syndrome by virtue of intense contrast enhancement. Because diffusion-weighted MR imaging and spectroscopy were normal, the lesions are likely caused by reversible vasogenic edema and transient breakdown of the blood-brain barrier.

Hemin induces heme oxygenase-1 in spinal cord vasculature and attenuates barrier disruption and neutrophil infiltration in the injured murine spinal cord

Heme oxygenase-1 (HO-1) has been shown to alter vascular function in part by attenuating inflammation. We induced HO-1 in blood vessels in the spinal cord by systemic administration of hemin. Twenty-four hours later, immediately prior to euthanasia, fluorescence conjugated Lycopersicon esculentum (tomato) lectin was given intravenously to label the vasculature. HO-1 was induced in blood vessels, particularly in the white matter, as evidenced by the immunolocalization of HO-1 in lectin positive vessels. Western blots confirmed the hemin-mediated induction of HO-1 in the uninjured spinal cord. We next examined the extent to which treatment with hemin or vehicle, 24 h prior to a moderate contusion injury, influenced early vascular dysfunction in the injured cord. All animals were euthanized 24 h after injury. Luciferase, a marker of barrier integrity, was given intravenously 30 min prior to euthanasia. The spinal cord was either prepared for quantification of luciferase activity or fixed by vascular perfusion and prepared for the immunolocalization of neutrophils. There was a significant attenuation of barrier permeability to luciferase and a significant reduction in the number of neutrophils in hemin treated animals as compared to the vehicle treated group. Together, these findings demonstrate that vascular induction of HO-1 modulates barrier function and neutrophil infiltration and suggest that this protein may be useful for limiting the early vascular dysfunction and inflammation that occurs in the acutely injured spinal cord.

[False surgical acute abdomen with intermittent acute porphyria]

This article presents a case of acute intermittent porphyria admitted to the Surgery Department of C.F. Craiova Hospital between 18.08.2003-26.08.2003 then transferred to the Colentina Hospital in Bucharest for diagnosis confirmation and adequate treatment. The purpose of this paper is to bring attention on a rare metabolic inherited disease that, due to its non-specific and often noisy symptoms and limited possibilities of biochemical, enzymatic and genetic diagnosis, could generate potential serious confusions. The presentes case illustrates the fact that sometimes the acute attack may be mistaken for an acute surgical affection which requires an emergency operation with all the aggravating consequences and delay in the real diagnosis. About 1% of acute attacks of porphyria may be fatal. Only the drugs known as safe should be prescribed. Basic treatment consists in oral and intravenous glucose and hematin administration.

Differential induction of heme oxygenase-1 in macrophages and hepatocytes during acetaminophen-induced hepatotoxicity in the rat: effects of hemin and biliverdin

Heme oxygenase-1 (HO-1), also known as heat shock protein 32, has been shown to protect against oxidant-induced tissue injury. In the present studies, we analyzed expression of this enzyme in macrophages and hepatocytes following acetaminophen administration and its potential role in hepatotoxicity. Treatment of rats with a hepatotoxic dose of acetaminophen (1 g/kg, ip) resulted in a time-dependent induction of HO-1 in the liver. This was observed within 6 h of acetaminophen administration in both hepatocytes and macrophages. Hepatocytes were found to be more sensitive than macrophages to the effects of acetaminophen on HO-1. Up regulation of HO-1 in the liver following acetaminophen administration correlated with induction of ferritin and manganese superoxide dismutase (MnSOD). To determine if HO-1 was hepatoprotective, rats were pretreated with hemin (30 micromol/kg, ip), a potent inducer of the enzyme. Following hemin treatment, we observed a time-dependent increase in HO-1 protein in the liver and in serum bilirubin levels. Pretreatment of rats with hemin was found to prevent acetaminophen-induced hepatotoxicity, as measured histologically and biochemically by decreased serum transaminase levels. This was correlated with more rapid increases in expression of hepatic ferritin and MnSOD. Heme metabolism via HO-1 generates biliverdin, which is rapidly converted to bilirubin by biliverdin reductase. Pretreatment of rats with biliverdin (40 micromol/kg, ip) was also found to block acetaminophen-induced injury. These data suggest that HO-1 is an important component of antioxidant defense during acetaminophen-induced hepatotoxicity.

Treatment of recurrent allograft dysfunction with intravenous hematin after liver transplantation for erythropoietic protoporphyria

Erythropoietic protoporphyria (EPP) is a rare inherited disorder of the heme biosynthetic pathway in which toxic levels of protoporphyrins often precipitate in the liver, leading to cirrhosis, liver failure, and the need for liver transplantation (OLT). Because the underlying enzyme defect in EPP is bone marrow derived, the risk for recurrent EPP allograft dysfunction is high. Although plasmapheresis may ameliorate acute allograft disease, strategies to maintain disease remission are needed. A 59-year-old man who underwent OLT for hepatic EPP experienced increased bilirubin and aminotransferases on postoperative day 700. Allograft biopsy demonstrated recurrent EPP. He was managed initially with plasmapheresis, hypertransfusion, and infusions of i.v. hematin. After normalization of liver tests, the hematin infusions have been given intermittently, are well tolerated, and associated with normal allograft function for nearly 2 years. This is the first case of the use of hematin given post-OLT to help achieve and maintain remission of allograft EPP disease.

Hemin, inducer of heme-oxygenase 1, improves functional recovery from myocardial stunning in conscious dogs

OBJECTIVE

To examine the effects of pretreatment with hemin, an inducer of the potential antioxidative enzyme heme-oxygenase 1 (HO-1) or heat-shock protein 32, on myocardial stunning.

DESIGN

Randomized animal study.

SETTING

Animal laboratory of a university hospital.

PARTICIPANTS

Chronically instrumented mongrel dogs (n = 44).

INTERVENTIONS

Dogs underwent chronic instrumentation for measurement of hemodynamics and myocardial wall thickening fraction (WTF). Experiments with 12 dogs were performed on separate days in a crossover fashion: (1) 10 minutes of left anterior descending (LAD) coronary artery occlusion after application of hemin (9 mg/kg/d) for 1 week and (2) 10 minutes of LAD coronary artery occlusion without hemin pretreatment. In control experiments (n = 32), the reversible induction of HO-1, using gel electrophoresis and Western blotting, was determined.

MEASUREMENTS AND MAIN RESULTS

WTF was measured as a baseline value before hemin administration and at predetermined time points until complete recovery from stunning. LAD artery occlusion caused a significant reduction in the WTF in the LAD-perfused area with and without hemin, without significant hemodynamic changes. At all time points, after 1 minute of reperfusion, the WTF as percentage of baseline values was significantly higher after hemin pretreatment (p < 0.05). Baseline WTF values were reached after 24 hours with and after >48 hours without hemin pretreatment (p < 0.05).

CONCLUSION

Hemin pretreatment attenuates myocardial stunning in conscious dogs.

Artemether administered together with haemin damages schistosomes in vitro

We conducted experiments in vitro to assess the effect of artemether in combination with haemin on adult Schistosoma japonicum, S. mansoni and S. haematobium. When schistosomes were maintained in a medium containing artemether at concentrations of 20 micrograms/mL or less for 72 h, no apparent effect on the schistosomes was seen. When the medium contained 50 or 100 micrograms/mL haemin as well as artemether, the schistosomes showed decreased motor activity 2-24 h after exposure, which was followed by the staining of the whole worm body a reddish-yellow colour, dilatation of the intestine, and extensive vesiculation of the tegument. Some of the schistosomes died 24 h after exposure, and almost all died within 48-72 h. When schistosomes were exposed to the same concentrations of haemin alone, they were stained a light yellow colour but there was no apparent effect on their survival. Our findings suggest that artemether interacts with haemin to exert a toxic effect on the worms, which might be of importance in the further elucidation of the mechanism of action of artemether on schistosomes.