minocycline and 6-hydroxy-2-5-7-8-tetramethylchroman-2-carboxylic-acid

Polymorphisms in the MHC class 1-like gene known as HFE have been proposed as genetic modifiers of neurodegenerative diseases that include neuroinflammation as part of the disease process. Variants of HFE are relatively common in the general population and are most commonly associated with iron overload, but can promote subclinical cellular iron loading even in the absence of clinically identified disease. The effects of the variants as well as the resulting cellular iron dyshomeostasis potentially impact a number of disease-associated pathways. We tested the hypothesis that the two most common HFE variants, H63D and C282Y, would affect cellular secretion of cytokines and trophic factors.. We screened a panel of cytokines and trophic factors using a multiplexed immunoassay in human neuroblastoma SH-SY5Y cells expressing different variants of HFE. The influence of cellular iron secretion on the potent chemokine monocyte chemoattractant protein-1 (MCP-1) was assessed using ferric ammonium citrate and the iron chelator, desferroxamine. Additionally, an antioxidant, Trolox, and an anti-inflammatory, minocycline, were tested for their effects on MCP-1 secretion in the presence of HFE variants.. Expression of the HFE variants altered the labile iron pool in SH-SY5Y cells. Of the panel of cytokines and trophic factors analyzed, only the release of MCP-1 was affected by the HFE variants. We further examined the relationship between iron and MCP-1 and found MCP-1 secretion tightly associated with intracellular iron status. A potential direct effect of HFE is considered because, despite having similar levels of intracellular iron, the association between HFE genotype and MCP-1 expression was different for the H63D and C282Y HFE variants. Moreover, HFE genotype was a factor in the effect of minocycline, a multifaceted antibiotic used in treating a number of neurologic conditions associated with inflammation, on MCP-1 secretion.. Our results demonstrate that HFE polymorphisms influence the synthesis and release of MCP-1. The mechanism of action involves cellular iron status but it appears there could be additional influences such as ER stress. Finally, these data demonstrate a pharmacogenetic effect of HFE polymorphisms on the ability of minocycline to inhibit MCP-1 secretion.

Topics: Animals; Anti-Inflammatory Agents; Antioxidants; Cell Line, Tumor; Chemokine CCL2; Chromans; Deferoxamine; Ferric Compounds; Gene Expression; Heat-Shock Proteins; Hemochromatosis Protein; Histocompatibility Antigens Class I; Humans; Iron; Iron Chelating Agents; Membrane Proteins; Mice; Microglia; Minocycline; Neurons; NF-kappa B; Polymorphism, Single Nucleotide; Quaternary Ammonium Compounds; RNA, Messenger

The neuroprotective effects of minocycline-which is broadly protective in neurologic-disease models featuring cell death and is being evaluated in clinical trials-were investigated both in vitro and in vivo. For the in vivo study, focal cerebral ischemia was induced by permanent middle cerebral artery occlusion in mice. Minocycline at 90 mg/kg intraperitoneally administered 60 min before or 30 min after (but not 4 h after) the occlusion reduced infarction, brain swelling, and neurologic deficits at 24 h after the occlusion. For the in vitro studies, we used cortical-neuron cultures from rat fetuses in which neurotoxicity was induced by 24-h exposure to 500 microM glutamate. Furthermore, the effects of minocycline on oxidative stress [such as lipid peroxidation in mouse forebrain homogenates and free radical-scavenging activity against diphenyl-p-picrylhydrazyl (DPPH)] were evaluated to clarify the underlying mechanism. Minocycline significantly inhibited glutamate-induced cell death at 2 microM and lipid peroxidation and free radical scavenging at 0.2 and 2 microM, respectively. These findings indicate that minocycline has neuroprotective effects in vivo against permanent focal cerebral ischemia and in vitro against glutamate-induced cell death and that an inhibition of oxidative stress by minocycline may be partly responsible for these effects.

Topics: Animals; Antioxidants; Benzimidazoles; Benzoxazoles; Biphenyl Compounds; Brain Edema; Brain Infarction; Cell Death; Cell Survival; Cells, Cultured; Cerebral Cortex; Chromans; Dose-Response Relationship, Drug; Drug Interactions; Embryo, Mammalian; Fluorescent Dyes; Glutamic Acid; Hydrazines; Infarction, Middle Cerebral Artery; Inhibitory Concentration 50; Ischemia; Lipid Peroxidation; Male; Mice; Minocycline; Neurons; Neuroprotective Agents; Oxidative Stress; Picrates; Quinolinium Compounds; Saponins; Tetrazolium Salts; Time Factors

Minocycline is neuroprotective in animal models of a number of acute CNS injuries and neurodegenerative diseases. While anti-inflammatory and anti-apoptotic effects of minocycline have been characterized, the molecular basis for the neuroprotective effects of minocycline remains unclear. We report here that minocycline and a number of antioxidant compounds protect mixed neuronal cultures in an oxidative stress assay. To evaluate the role of minocycline's direct antioxidant properties in neuroprotection, we determined potencies for minocycline, other tetracycline antibiotics, and reference antioxidant compounds using a panel of in vitro radical scavenging assays. Data from in vitro rat brain homogenate lipid peroxidation and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assays show that minocycline, in contrast to tetracycline, is an effective antioxidant with radical scavenging potency similar to vitamin E. Our findings suggest that the direct antioxidant activity of minocycline may contribute to its neuroprotective effects in some cell-based assays and animal models of neuronal injury.

Topics: Animals; Antioxidants; Antipyrine; Benzothiazoles; Cell Death; Cells, Cultured; Cerebral Cortex; Chromans; Deoxyribose; Dizocilpine Maleate; Dose-Response Relationship, Drug; Drug Interactions; Edaravone; Embryo, Mammalian; Free Radical Scavengers; Free Radicals; Glutamic Acid; Inhibitory Concentration 50; L-Lactate Dehydrogenase; Lipid Peroxidation; Minocycline; Neurons; Neuroprotective Agents; Oxidative Stress; Phenethylamines; Rats; Rats, Sprague-Dawley; Sulfonic Acids; Vitamin E