Interleukin 1-beta modulates the effects of hypoxia in neuronal culture

AP-1 (Activated Protein-1) Transcription Factor JunD Regulates Ischemia/Reperfusion Brain Damage via IL-1β (Interleukin-1β)

Background and Purpose- Inflammation is a major pathogenic component of ischemia/reperfusion brain injury, and as such, interventions aimed at inhibiting inflammatory mediators promise to be effective strategies in stroke therapy. JunD-a member of the AP-1 (activated protein-1) family of transcription factors-was recently shown to regulate inflammation by targeting IL (interleukin)-1β synthesis and macrophage activation. The purpose of the present study was to assess the role of JunD in ischemia/reperfusion-induced brain injury. Methods- WT (wild type) mice randomly treated with either JunD or scramble (control) siRNA were subjected to 45 minutes of transient middle cerebral artery occlusion followed by 24 hours of reperfusion. Stroke size, neurological deficit, plasma/brain cytokines, and oxidative stress determined by 4-hydroxynonenal immunofluorescence staining were evaluated 24 hours after reperfusion. Additionally, the role of IL-1β was investigated by treating JunD siRNA mice with an anti-IL-1β monoclonal antibody on reperfusion. Finally, JunD expression was assessed in peripheral blood monocytes isolated from patients with acute ischemic stroke. Results- In vivo JunD knockdown resulted in increased stroke size, reduced neurological function, and increased systemic inflammation, as confirmed by higher neutrophil count and lymphopenia. Brain tissue IL-1β levels were augmented in JunD siRNA mice as compared with scramble siRNA, whereas no difference was detected in IL-6, TNF-α (tumor necrosis factor-α), and 4-hydroxynonenal levels. The deleterious effects of silencing of JunD were rescued by treating mice with an anti-IL-1β antibody. In addition, JunD expression was decreased in peripheral blood monocytes of patients with acute ischemic stroke at 6 and 24 hours after onset of stroke symptoms compared with sex- and age-matched healthy controls. Conclusions- JunD blunts ischemia/reperfusion-induced brain injury via suppression of IL-1β.

The Novel C5aR Antagonist DF3016A Protects Neurons Against Ischemic Neuroinflammatory Injury

The central nervous system (CNS) constitutively expresses complement (C) membrane receptors and complement proteins, including the component C5a. This is a crucial terminal effector of the C cascade, mostly involved in pain and neuroinflammatory conditions. Aberrant activation of C5a protein and its receptor C5aR has been reported to play a critical role in neurodegenerative diseases, with important clinical consequences. Here we have investigated the effects of DF3016A, a novel selective C5aR antagonist, able to penetrate the blood-brain barrier (BBB), on cortical neurons exposed to oxygen-glucose deprivation-reoxygenation (OGD/R), a neuroinflammation-related process. We demonstrated that a mild ischemic insult induces an early upregulation of C5aR associated with the over-production of pro-inflammatory cytokines and the over-expression of the transcriptional regulatory factor miR-181. Furthermore, we report the first experimental evidence of the effect of DF3016A, modulating complement component C5a, on neurons in a model of injury. Interestingly, DF3016A protects neuronal viability by restoring intracellular calcium levels, thus opposing the increase in pro-inflammatory cytokine levels and miR-181 expression. Based on our results, we suggest that DF3016A is a novel C5aR antagonist promoting protective effects against OGD/R-induced damage that could be a new therapeutic approach to controlling CNS neuroinflammatory conditions.

Hypoxia modulation of peroxisome proliferator-activated receptors (PPARs) in human glioblastoma stem cells. Implications for therapy

Gliobastoma (GB), the most common adult brain tumor, infiltrates normal brain area rendering impossible the complete surgical resection, resulting in a poor median survival (14-15 months), despite the aggressive multimodality treatments post-surgery, such as radiation and chemo-therapy. GB is characterized by hypoxic and necrotic regions due to a poorly organized tumor vascularization, leading to inadequate blood supply and consequently to hypoxic and necrotic areas. We have previously shown that, under hypoxia GB primary cells increased the expression of stemness markers as well as the expression of the nuclear receptor peroxisome proliferator-activated receptor α (PPARα) and also the crucial role played by PPARs in mouse neural stem cells maintenance and differentiation. Due to the importance of lipid signaling in cell proliferation and differentiation, in this work, we analyzed the expression of PPARs in GB neurospheres both in normoxic and hypoxic conditions. The results obtained suggest a differential regulation of the three PPARs by hypoxia, thus indicating a possible therapeutic strategy to counteract GB recurrencies.

Methylglyoxal causes strong weakening of detoxifying capacity and apoptotic cell death in rat hippocampal neurons

The hippocampus is known to play a crucial role in learning and memory. Recent data from literature show that cognitive problems, common to aged or diabetic patients, may be related to accumulation of toxic alpha-oxoaldehydes such as methylglyoxal. Thus, it is possible that methylglyoxal could be, at least in part, responsible for the impairment of cognitive functions, and the knowledge of the mechanisms through which this compound elicits neuronal toxicity could be useful for the development of possible therapeutic strategies. We previously reported a high susceptibility of hippocampal neurons to methylglyoxal, through an oxidation-dependent mechanism. In the present study, we extend our investigation on the molecular mechanisms which underlie methylglyoxal toxicity, focusing on possible effects on expression and activity of glyoxalases, its main detoxifying enzymes, and glutathione peroxidase, as well as on the levels of reduced glutathione. We also investigate methylglyoxal-induced modulation of brain derived neurotrophic factor and proinflammatory cytokines. Our results show that methylglyoxal causes a dramatic depletion of reduced glutathione and a significant inhibition of both glyoxalase and glutathione peroxidase activities. Furthermore, methylglyoxal treatment seems to affect the expression of inflammatory cytokines and survival factors. In conclusion, our findings suggest that methylglyoxal-induced neurotoxicity occurs through the impairment of detoxification pathway and depletion of reduced glutathione. This, in turn, triggers widespread apoptotic cell death, occurring through the convergence of both mitochondrial and Fas-receptor pathways.

Impact of 17beta-estradiol on cytokine-mediated apoptotic effects in primary hippocampal and neocortical cell cultures

Estrogens are developmental regulators of mitochondrial apoptotic pathway in the central nervous system, but little is known about their involvement in cytokine-induced apoptosis. In the present study, we evaluated effects of 17beta-estradiol on pro-inflammatory cytokine- and staurosporine-mediated activation of caspase-3 and LDH-release in primary neuronal/glial cell cultures of mouse hippocampal and neocortical cells at different stages of their development in vitro. Enzyme activities were determined with colorimetric methods 6 h, 14 h, 24 h, and 48 h after exposure to the apoptotic agents. Biochemical data were supported at the cellular level by Hoechst 33342 and MAP-2 stainings, which were carried out 48 h after the treatment. Cytokines (co-treatment with Il-1beta and TNFalpha; 1 ng/ml) increased caspase-3 activity in the hippocampal and neocortical cells up to over 200% of control values, and these effects were mostly observed on 2 and 7 days in vitro (DIV). Moderate, but significant cytokine-mediated increase in LDH-release was demonstrated in both tissues, especially on 7 and 12 DIV. Estradiol (100 nM) inhibited the activation of caspase-3 at early stage of development (2 DIV) in the hippocampal, but not in the neocortical cultures. The cytokine-induced activation of caspase-3 and LDH-release was inhibited by estradiol in estrogen receptor-independent way. These data point to a possible role of estrogens as non-estrogen receptor-related inhibitors of cytokine-activated apoptotic pathway in the developing central nervous system.

Methylglyoxal induces oxidative stress-dependent cell injury and up-regulation of interleukin-1β and nerve growth factor in cultured hippocampal neuronal cells

Methylglyoxal (MG) is one of the most powerful glycating agents of proteins and other important cellular components and has been shown to be toxic to cultured cells. Under hyperglycaemic conditions, an increase in the concentration of MG has been observed in human body fluids and tissues that seems to be responsible for diabetic complications. Recent data suggest that diabetes may cause impairment of cognitive processes, according to a mechanism involving both oxidative stress and advanced glycation end product (AGE) formation. In this work, we explored the molecular mechanism underlying MG toxicity in neural cells, by investigating the effect of MG on both the interleukin-1beta (IL-1beta), as the major inducer of the acute phase response, and the nervous growth factor (NGF) expression. Experiments were performed on cultured neural cells from rat hippocampus, being this brain region mostly involved in cognitive processes and, therefore, possible target of diabetes-mediated impairment of cognitive abilities. Results show that MG treatment causes in hippocampal neural cells extensive, oxidative stress-mediated cell death, in consequence of a strong catalase enzymatic activity and protein inhibition. MG also causes a very significant increase in both transcript and protein expression of the NGF as well as of the pro-inflammatory cytokine IL-1beta. MG co-treatment with the antioxidant N-acetylcysteine (NAC) completely abrogates the observed effects. Taken together, these data demonstrate that hippocampal neurons are strongly susceptible to MG-mediated oxidative stress.

Involvement of interleukin-1beta in systemic morphine effects on paw oedema in a mouse model of acute inflammation

Recent studies suggest that peripheral morphine may represent a valuable treatment in acute inflammatory painful diseases through peripheral or central mechanisms. In the present study, anti-inflammatory effects of systemic morphine on carrageenan-induced hind paw oedema were examined in a model of peripheral acute oedema in mice. Carrageenan induced a time-dependent inflammation that was maximal 3 h after administration. While intraperitoneal administration of morphine sulfate at a low dose (1 mg/kg) increased carrageenan-induced hind paw oedema, intraperitoneal injection of morphine sulfate at a high dose (7 mg/kg) resulted in significant anti-inflammatory effects on carrageenan-induced hind paw oedema. These anti-inflammatory effects were blocked by pretreatment with naloxone. Measuring the serum levels of interleukin-1beta revealed that increases in serum levels of this cytokine were involved in morphine anti-inflammatory effects. Pretreatment with naloxone decreased interleukin-1beta serum levels near to those of control group. In conclusion, these data demonstrate that morphine produced pro- or anti-inflammatory effects in a dose-dependent manner through peripheral or central mechanisms. The observed anti-inflammatory effects may be due to an increase in the cytokine production and/or release by host immune systems.

The vitamin-E analog trolox and the NMDA antagonist MK-801 protect pyramidal neurons in hippocampal slice cultures from IL-1beta-induced neurodegeneration

The neurotoxic effect of the pro-inflammatory cytokine interleukin (IL)-1beta was studied in monolayer cultures, obtained using roller-drum incubation of hippocampal slices from neonatal Sprague Dawley rats. Following exposure to recombinant rat IL-1beta for four days, a concentration dependent loss was observed in the number of NMDAR1 receptor subunit immunoreactive pyramidal neurons in the cultures, reaching significance at 10 ng/ml rIL-1beta. Also incubation with recombinant mouse IL-1beta caused a loss of pyramidal neurons, with a significant effect at a concentration of 30 pg/ml. The vitamin E analog trolox (30 microM) was found to exert a protective effect against the rIL-1beta induced neuronal degeneration. A neuroprotective action against rIL-1beta was also found after co-incubation with the NMDA antagonist dizocilpine (MK-801; 30 microM), while no protection was found with the GABAA mimetic clomethiazole. Hence, the pro-inflammatory cytokine IL-1beta is neurotoxic to hippocampal pyramidal neurons when studied in an in vitro system with advanced phenotypic characteristics. The neuroprotective effects exerted by trolox and MK-801 suggest that free radicals and NMDA receptor-mediated processes are involved in IL-1beta -induced neurodegeneration.

Correlation between ERG changes and FGF2 mRNA Up-regulation in patients with choroidal melanoma

To study electroretinographic (ERG) response to light flashes in patients with choroidal melanoma and to define possible factors involved in the modification of both a- and b-wave.ISCEV standard flash-ERG was recorded from both affected and control eyes on 24 patients before surgical operation (local excision or enucleation). The choroidal melanomatous mass ranged from 33 to 2880mm(3). Tissues from both melanomatous retina-choroid complex and areas far from the melanoma (unaffected) were taken from 13 enucleated eyes to measure the level of FGF2 mRNA, utilizing the technique of semiquantitative reverse transcription-polymerase chain reaction (RT-PCR). Tissues from 10 normal eyes were used as control. The majority of patients showed a marked a- and b-wave attenuation in the affected eye with respect to the fellow eye. In 10 retinal specimens, the expression of FGF2 mRNA showed an increase in retinal regions far from the melanoma compared to control eyes. Many patients present an increase in the expression of FGF2 mRNA in the unaffected part of the retina and a clear attenuation in both a- and b-ERG components. The size of melanoma does not predict the amount of reduction in the ERG response, at least for sizes less than 1000mm(3). We suggest that the melanoma triggers a process leading to an up-regulation of FGF2 in the human eye and this up-regulation might be responsible for the ERG attenuation.