A Pharmacologic "Stress Test" for Assessing Select Antioxidant Defenses in Patients with CKD.

BACKGROUND AND OBJECTIVES: Oxidative stress is a hallmark and mediator of CKD. Diminished antioxidant defenses are thought to be partly responsible. However, there is currently no way to prospectively assess antioxidant defenses in humans. Tin protoporphyrin (SnPP) induces mild, transient oxidant stress in mice, triggering increased expression of select antioxidant proteins (e.g., heme oxygenase 1 [HO-1], NAD[P]H dehydrogenase [quinone] 1 [NQO1], ferritin, p21). Hence, we tested the hypothesis that SnPP can also variably increase these proteins in humans and can thus serve as a pharmacologic "stress test" for gauging gene responsiveness and antioxidant reserves. DESIGN: , setting, participants, & measurementsA total of 18 healthy volunteers and 24 participants with stage 3 CKD (n=12; eGFR 30-59 ml/min per 1.73 m2) or stage 4 CKD (n=12; eGFR 15-29 ml/min per 1.73 m2) were injected once with SnPP (9, 27, or 90 mg). Plasma and/or urinary antioxidant proteins were measured at baseline and for up to 4 days post-SnPP dosing. Kidney safety was gauged by serial measurements of BUN, creatinine, eGFR, albuminuria, and four urinary AKI biomarkers (kidney injury molecule 1, neutrophil gelatinase-associated lipocalin, cystatin C, and N-acetyl glucosaminidase). RESULTS: Plasma HO-1, ferritin, p21, and NQO1 were all elevated at baseline in CKD participants. Plasma HO-1 and urine NQO1 levels each inversely correlated with eGFR (r=-0.85 to -0.95). All four proteins manifested statistically significant dose- and time-dependent elevations after SnPP injection. However, marked intersubject differences were observed. p21 responses to high-dose SnPP and HO-1 responses to low-dose SnPP were significantly suppressed in participants with CKD versus healthy volunteers. SnPP was well tolerated by all participants, and no evidence of nephrotoxicity was observed. CONCLUSIONS: SnPP can be safely administered and, after its injection, the resulting changes in plasma HO-1, NQO1, ferritin, and p21 concentrations can provide information as to antioxidant gene responsiveness/reserves in subjects with and without kidney disease. CLINICAL TRIAL REGISTRY NAME AND REGISTRATION NUMBER: A Study with RBT-1, in Healthy Volunteers and Subjects with Stage 3-4 Chronic Kidney Disease, NCT0363002 and NCT03893799.

Potential for a novel manganese porphyrin compound as adjuvant canine lymphoma therapy.

PURPOSE: Manganese porphyrins are redox-active drugs and superoxide dismutase mimics, which have been shown to chemosensitize lymphoma, a cancer which frequently occurs in dogs. This study aimed to identify critical information regarding the pharmacokinetics and toxicity of Mn(III) meso-tetrakis (N-n-butoxyetylpyridium-2-yl) porphyrin, (MnTnBuOE-2-PyP5+, MnBuOE) in dogs as a prelude to a clinical trial in canine lymphoma patients. METHODS: A single-dose pharmacokinetic (PK) study in normal dogs was performed to determine the plasma half-life (t 1/2) of MnBuOE. A dose reduction study was performed to establish the maximum tolerated dose (MTD) of MnBuOE. The safety and PK of a multi-dosing protocol was assessed. RESULTS: Peak plasma drug concentration occurred 30 min post-injection. The t 1/2 was defined as 7 h. MnBuOE induced an anaphylactic reaction and prolonged tachycardia. The MTD was defined as 0.25 mg/kg. The dogs were given MTD 3×/week for 2-3 weeks. The highest recorded tissue drug levels were in the lymph nodes (4-6 µM), followed by kidney and liver (2.5, 2.0 uM, respectively). CONCLUSIONS: We obtained critical information regarding the PK and toxicity of MnBuOE in dogs. The acute drug reaction and tachycardia post-injection have not been described in other species and may be specific to canines. The high tissue drug levels in lymph nodes have not been previously reported. MnBuOE accumulation in lymph nodes has important implications for the utility of adjuvant MnBuOE to treat lymphoma. With MnBuOE lymph node accumulation, reduction in the dose and/or administration frequency could be possible, leading to reduced toxicity.

Pre-clinical therapeutic development of a series of metalloporphyrins for Parkinson's disease.

Reactive oxygen species are a well-defined therapeutic target for Parkinson's disease (PD) and pharmacological agents that catalytically scavenge reactive species are promising neuroprotective strategies for treatment. Metalloporphyrins are synthetic catalytic antioxidants that mimic the body's own antioxidant enzymes i.e. superoxide dismutases and catalase. The goal of this study was to determine if newly designed metalloporphyrins have enhanced pharmacodynamics including oral bioavailability, longer plasma elimination half-lives, penetrate the blood brain barrier, and show promise for PD treatment. Three metalloporphyrins (AEOL 11216, AEOL 11203 and AEOL 11114) were identified in this study as potential candidates for further pre-clinical development. Each of these compounds demonstrated blood brain barrier permeability by the i.p. route and two of three compounds (AEOL 11203 and AEOL 11114) were orally bioavailable. All of these compounds protected against 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced neurotoxicity, including dopamine depletion in the striatum, dopaminergic neuronal loss in the substantial nigra, and increased oxidative/nitrative stress indices (glutathione disulfide and 3-nitrotyrosine) in the ventral midbrain of the mice without inhibiting MPTP metabolism. Daily therapeutic dosing of these metalloporphyrins were well tolerated without accumulation of brain manganese levels or behavioral alterations assessed by open field and rotarod tests. The study identified two orally active metalloporphyrins and one injectable metalloporphyrin as clinical candidates for further development in PD.

Clinical trial of tin mesoporphyrin to prevent neonatal hyperbilirubinemia.

OBJECTIVE: To assess the efficacy of the heme oxygenase inhibitor, tin mesoporphyrin (SnMP), to reduce total bilirubin (TB) levels. STUDY DESIGN: Masked, SnMP (4.5 mg kg(-1)), placebo-controlled, multicenter trial of single intramuscular injection to newborns ⩾35 weeks gestational age whose predischarge screening transcutaneous bilirubin (TcB) was >75th percentile. RESULTS: Two hundred and thirteen newborns (median age 30 h) were randomized to treatment with SnMP (n=87) or 'sham' (n=89). We found that the duration of phototherapy was halved. Within 12 h of SnMP administration, the natural TB trajectory was reversed. At age 3 to 5 days, TB in the SnMP-treated group was +8% but sixfold lower than the 47% increase in the sham-treated group (P<0.001). At age 7 to 10 days, mean TB declined 18% (P<0.001) compared with a 7.1% increase among controls. No short-term adverse events from SnMP treatment were noted other than photoreactivity due to inadvertent exposure to white light phototherapy. CONCLUSION: Early, predischarge SnMP administration decreased the duration of phototherapy, reversed TB trajectory and reduced the severity of subsequent hyperbilirubinemia.

Respiratory plasticity after perinatal hyperoxia is not prevented by antioxidant supplementation.

Perinatal hyperoxia attenuates the hypoxic ventilatory response in rats by altering development of the carotid body and its chemoafferent neurons. In this study, we tested the hypothesis that hyperoxia elicits this plasticity through the increased production of reactive oxygen species (ROS). Rats were born and raised in 60% O(2) for the first two postnatal weeks while treated with one of two antioxidants: vitamin E (via milk from mothers whose diet was enriched with 1000 IU vitamin E kg(-1)) or a superoxide dismutase mimetic, manganese(III) tetrakis (1-methyl-4-pyridyl) porphyrin pentachloride (MnTMPyP; via daily intraperitoneal injection of 5-10 mg kg(-1)); rats were subsequently raised in room air until studied as adults. Peripheral chemoreflexes, assessed by carotid sinus nerve responses to cyanide, asphyxia, anoxia and isocapnic hypoxia (vitamin E experiments) or by hypoxic ventilatory responses (MnTMPyP experiments), were reduced after perinatal hyperoxia compared to those of normoxia-reared controls (all P<0.01); antioxidant treatment had no effect on these responses. Similarly, the carotid bodies of hyperoxia-reared rats were only one-third the volume of carotid bodies from normoxia-reared controls (P <0.001), regardless of antioxidant treatment. Protein carbonyl concentrations in the blood plasma, measured as an indicator of oxidative stress, were not increased in neonatal rats (2 and 8 days of age) exposed to 60% O(2) from birth. Collectively, these data do not support the hypothesis that perinatal hyperoxia impairs peripheral chemoreceptor development through ROS-mediated oxygen toxicity.

Low molecular weight catalytic metalloporphyrin antioxidant AEOL 10150 protects lungs from fractionated radiation.

The objective of this study was to determine whether administration of a catalytic antioxidant, Mn(III) tetrakis(N,N'-diethylimidazolium-2-yl) porphyrin, AEOL10150, reduces the severity of long-term lung injury induced by fractionated radiation (RT). Fisher 344 rats were randomized into five groups: RT+AEOL10150 (2.5 mg/kg BID), AEOL10150 (2.5 mg/kg BID) alone, RT+ AEOL10150 (5 mg/kg BID), AEOL10150 (5 mg/kg BID) alone and RT alone. Animals received five 8 Gy fractions of RT to the right hemithorax. AEOL10150 was administered 15 min before RT and 8 h later during the period of RT treatment (5 days), followed by subcutaneous injections for 30 days, twice daily. Lung histology at 26 weeks revealed a significant decrease in lung structural damage and collagen deposition in RT+AEOL10150 (5 mg/kg BID) group, in comparison to RT alone. Immunohistochemistry studies revealed a significant reduction in tissue hypoxia (HIF1alpha, CAIX), angiogenic response (VEGF, CD-31), inflammation (ED-1), oxidative stress (8-OHdG, 3-nitrotyrosine) and fibrosis pathway (TGFbeta1, Smad3, p-Smad2/3), in animals receiving RT+ AEOL10150 (5 mg/kg BID). Administration of AEOL10150 at 5 mg/kg BID during and after RT results in a significant protective effect from long-term RT-induced lung injury. Low dose (2.5 mg/kg BID) delivery of AEOL10150 has no beneficial radioprotective effects.

The use of riboflavin and metalloporphyrins in cytochrome P-450 content in Wistar rats.

Phototherapy is commonly used for the treatment of neonatal jaundice. Riboflavin is a photosensitizer that generates singlet oxygen, which promotes bilirubin photodecomposition. Metalloporphyrins are also effective photosensitizers. The effect of a combined dosing regimen of riboflavin and metalloporphyrins was studied, with the aim of increasing the efficiency of the phototherapeutic treatment of hyperbilirubinemia. It was envisaged that riboflavin and the metalloporphyrins, by promoting the photodecomposition of bilirubin, would thereby lead to a reduction of the toxic side effects associated with phototherapy. The results shows that a phototherapeutic treatment, in which riboflavin and metalloporphyrins were co-administered, was effective in reducing Heme Oxygenase activity. However, a comprehensive study of the possible side effects of metalloporphyrin treatment in the wavelength under consideration is essential prior to utilizing these compounds for any clinical applications.

In vivo evaluation of the boronated porphyrin TABP-1 in U-87 MG intracerebral human glioblastoma xenografts.

Boron neutron capture therapy (BNCT) is an adjuvant therapy that has the potential to control local tumor growth. A selective delivery of sufficient amounts of boron to individual tumor cells, compared to surrounding normal tissues, is the key for successful BNCT. We have designed and synthesized a new highly water-soluble boronated porphyrin, TABP-1, as a possible BNCT agent. When we injected the maximum tolerated dose (MTD: 15 mg/kg) of TABP-1 systemically into the tail vein of athymic rats bearing intracerebral (i.c.) human glioblastoma U-87 MG xenografts, the compound accumulated preferentially in brain tumors compared to normal brain; however, the level of boron in the tumors was less than the 30 microg/g of tissue that is generally considered necessary for BNCT. We next investigated whether convection-enhanced delivery (CED) could improve the boron distribution. The compound was administered directly into i.c. tumors using an osmotic minipump attached to a brain-infusion cannula. TABP-1 doses from 0.25 to 1.0 mg infused locally over 24 h produced tumor boron concentrations greater than those obtained by systemic administration at the MTD. For example, CED administration of 0.5 mg of TABP-1 produced a tumor boron level of 65.4 microg/g of tumor, whereas the serum level was only 0.41 microg/g (tumor to serum ratio of approximately 160:1). CED also produced relatively high tumor to normal brain ratios of approximately 5:1 for ipsilateral brain and approximately 26:1 for contralateral brain tissues at the 0.5 mg dose. Thus, we may be able to achieve therapeutic BNCT efficacy with minimal systemic toxicity or radiation-induced damage to normal tissue by administering TABP-1 using CED.

Phase I drug and light dose-escalation trial of motexafin lutetium and far red light activation (phototherapy) in subjects with coronary artery disease undergoing percutaneous coronary intervention and stent deployment: procedural and long-term results.

BACKGROUND: Motexafin lutetium (MLu; Antrin) is a photosensitizer that is taken up by atherosclerotic plaque and concentrated within macrophages and vascular smooth muscle cells. After photoactivation with far red light, MLu facilitates production of cytotoxic oxygen radicals that mediate apoptosis. We assessed the safety and tolerability of phototherapy (PT) with MLu in patients undergoing percutaneous coronary intervention with stent deployment. METHODS AND RESULTS: An open-label, phase I, drug and light dose-escalation clinical trial of MLu PT enrolled 80 patients undergoing de novo coronary stent deployment. MLu was administered to 79 patients by intravenous infusion 18 to 24 hours before procedure, and photoactivation was performed after balloon predilatation and before stent deployment. Clinical evaluation, serial quantitative angiography, and intravascular ultrasound were performed periprocedurally and at 6 months follow-up. MLu PT was well tolerated without serious dose-limiting toxicities, and side effects (paresthesia and rash) were minor. No adverse angiographic outcomes were attributed to phototherapy. CONCLUSIONS: This study demonstrates that coronary MLu PT seems safe, and the maximum well-tolerated MLu dose and range of tolerated light doses were identified. These data can be used in phase II efficacy trials of MLu PT for the treatment of coronary atherosclerosis or vulnerable plaque.

Part II: beneficial effects of the peroxynitrite decomposition catalyst FP15 in murine models of arthritis and colitis.

BACKGROUND: Peroxynitrite is a reactive oxidant species produced from nitric oxide and superoxide, which has been indirectly implicated in the pathogenesis of many inflammatory conditions including arthritis and colitis. Here, using a novel peroxynitrite decomposition catalyst, FP15, we directly investigate the role of peroxynitrite in the pathogenesis of arthritis and colitis in rodent models. METHODS: Arthritis was induced in mice by intradermal collagen injection; incidence and severity of arthritis was monitored using a macroscopic scoring system. At the end of the experiment paws were taken for determination of neutrophil infiltration (myeloperoxidase [MPO] activity), oxidative stress (malondialdehyde [MDA] level), and cytokine/chemokine levels. Colitis was induced in mice by 5% dextran sodium sulfate (DSS) in their drinking water. Colitis symptoms were assessed 10 days later, the parameters determined included body weight, rectal bleeding, colon length, colonic MPO and MDA levels, and colon histologic damage. RESULTS: Treatment with FP15 significantly reduced the inflammation and oxidative stress in arthritis and colitis. FP15 reduced both the incidence and severity of arthritis in mice and this was associated with reduced paw MPO and MDA levels. Similarly, in colitis, FP15 reduced colon damage, and this was associated with reduced colon neutrophil infiltration and oxidative stress. CONCLUSIONS: The protective effect of FP15 suggests that peroxynitrite plays a significant pathogenetic role in arthritis and colitis in the currently employed rodent models. Further work is needed to determine whether neutralization of peroxynitrite also represents a promising strategy to treat human inflammatory diseases such as arthritis and colitis.

[Pharmacologic treatment of neonatal jaundice. A new approach]. / Traitement pharmacologique de l'ictère du nouveau-né. Un nouvel essor.

Pharmacological treatment of neonatal jaundice is again topical. At the beginning of the eighties, clofibrate was added to phenobarbital which was difficult to use and inefficient. Clofibrate is a better enhancer of glucuronosyl transferase induction than phenobarbital and causes 100% increase of hepatic bilirubin clearance within 6 hours. In the treatment of early jaundice in full term neonate, it significantly reduces bilirubinemia in 16 hours, and decreases the intensity and duration of jaundice and also phototherapy requirement. At the end of the eighties, new molecules inhibiting hepatic production of heme to bilirubin, like metalloporphyrins, were introduced. These molecules block the transformation of heme to biliverdin and bilirubin. Among them, the Sn-mesoporphyrin seems to have the best efficacy when used prophylactically in premature infants between 30 and 36 weeks of gestational age, and also curatively in full-term neonates, with minimal side effects. However the product is not yet manufactured and can not be used in pediatrics practice. Therefore clofibrate represents the only pharmacological treatment of neonatal jaundice actually available.