Limits...
The PPAR-γ agonist pioglitazone protects cortical neurons from inflammatory mediators via improvement in peroxisomal function.

Gray E, Ginty M, Kemp K, Scolding N, Wilkins A - J Neuroinflammation (2012)

Bottom Line: To assess the influence of peroxisomal activation on nitric oxide mediated neurotoxicity, we investigated the effects of the peroxisomal proliferator activated receptor (PPAR) gamma agonist, pioglitazone in primary cortical neurons that were either exposed to a nitric oxide donor or co-cultured with activated microglia.Moreover, cortical neurons treated with this compound showed a significant increase in the protein and gene expression of PPAR-gamma, which was associated with a concomitant increase in the enzymatic activity of catalase.In addition, the protection of neurons and axons against hydrogen peroxide-induced toxicity afforded by pioglitazone appeared to be dependent on catalase.

View Article: PubMed Central - HTML - PubMed

Affiliation: Multiple Sclerosis and Stem Cell Group, Burden Centre, Institute of Clinical Neurosciences, Frenchay Hospital, University of Bristol, Bristol BS16 1JB, UK. elizabeth.gray@bristol.ac.uk

ABSTRACT

Background: Inflammation is known to play a pivotal role in mediating neuronal damage and axonal injury in a variety of neurodegenerative disorders. Among the range of inflammatory mediators, nitric oxide and hydrogen peroxide are potent neurotoxic agents. Recent evidence has suggested that oligodendrocyte peroxisomes may play an important role in protecting neurons from inflammatory damage.

Methods: To assess the influence of peroxisomal activation on nitric oxide mediated neurotoxicity, we investigated the effects of the peroxisomal proliferator activated receptor (PPAR) gamma agonist, pioglitazone in primary cortical neurons that were either exposed to a nitric oxide donor or co-cultured with activated microglia.

Results: Pioglitazone protected neurons and axons against both nitric-oxide donor-induced and microglia-derived nitric oxide-induced toxicity. Moreover, cortical neurons treated with this compound showed a significant increase in the protein and gene expression of PPAR-gamma, which was associated with a concomitant increase in the enzymatic activity of catalase. In addition, the protection of neurons and axons against hydrogen peroxide-induced toxicity afforded by pioglitazone appeared to be dependent on catalase.

Conclusions: Collectively, these observations provide evidence that modulation of PPAR-gamma activity and peroxisomal function by pioglitazone attenuates both NO and hydrogen peroxide-mediated neuronal and axonal damage suggesting a new therapeutic approach to protect against neurodegenerative changes associated with neuroinflammation.

Show MeSH

Related in: MedlinePlus

Effect of pioglitazone on microglial-induced neuronal and axonal loss in transwell co-culture. (a) Effect of pioglitazone (Pio; 1 and 10 μM) on nitrite production by microglial cultures either in the absence (MIN) or presence of LPS and IFN-γ (MIN LPS IFN). Cultures were exposed to IFN and LPS for 48 hours and nitrite levels measured in the culture supernatant (μM nitrite, **P < 0.01 compared to MIN; statistical significance was obtained by one-way ANOVA followed by Bonferroni post-hoc test. (b) Effect of pioglitazone (Pio; 1 and 10 μM) on nitrite production by neuron-microglia transwell co-cultures either in the absence (MIN) or presence of LPS and IFN-γ (MIN LPS IFN). Cultures were exposed to IFN and LPS for 48 hours and nitrite levels measured in the culture supernatant (μM nitrite, **P < 0.01 compared to MIN; statistical significance was obtained by one-way ANOVA followed by Bonferroni post-hoc test). (c) Effect of pre-treatment with pioglitazone (1 and 10 μM) on cortical neuronal survival in the presence of LPS and IFN-γ activated microglia in transwell co-culture (number of β-III tubulin cells per field) (**P < 0.01 compared to MIN LPS IFN, Student's t-test). (d) Effect of pre-treatment with pioglitazone (1 and 10 μM) on total axon length (**P < 0.01 compared to MIN LPS IFN, Student's t-test) in the presence of LPS and IFN-γ activated microglia in transwell co-culture (length of SMI-312 axons per field). Photomicrographs showing immunoreactivity for β-III tubulin (red) and DAPI (blue) in neuron-microglia transwell co-cultures in the presence of MIN LPS and IFN-γ (MIN LPS IFN) (e) and (f) MIN LPS IFN-γ and pioglitazone (10 μM) (MIN LPS IFN Pio 10 μM). ANOVA, analysis of variance; DAPI, 4',6-diamidino-2-phenylindole; IFN, interferon; LPS, Lipopolysaccharide. Microglial derived-nitric oxide has been shown to mediate significant neuronal and axonal loss in vitro. We examined the influence of pioglitazone pre-treatment on neuronal survival and axonal morphology in neuronal-microglial transwell co-cultures. Co-cultures were fixed and stained for βIII tubulin, SMI312 and the nuclear marker DAPI. Pre-treatment with pioglitazone (10 μM) conferred a neuroprotective effect with a significant increase in neuronal (Figure 2c) and total axon survival (Figure 2d) in transwell co-cultures of neurons and activated microglia. These data suggest that pioglitazone provides protection for cortical neurons in neuron-microglia co-cultures through mechanisms which may be independent of its effects on nitrite reduction and that cell-to-cell contact is not required for this to occur.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC3368767&req=5

Figure 2: Effect of pioglitazone on microglial-induced neuronal and axonal loss in transwell co-culture. (a) Effect of pioglitazone (Pio; 1 and 10 μM) on nitrite production by microglial cultures either in the absence (MIN) or presence of LPS and IFN-γ (MIN LPS IFN). Cultures were exposed to IFN and LPS for 48 hours and nitrite levels measured in the culture supernatant (μM nitrite, **P < 0.01 compared to MIN; statistical significance was obtained by one-way ANOVA followed by Bonferroni post-hoc test. (b) Effect of pioglitazone (Pio; 1 and 10 μM) on nitrite production by neuron-microglia transwell co-cultures either in the absence (MIN) or presence of LPS and IFN-γ (MIN LPS IFN). Cultures were exposed to IFN and LPS for 48 hours and nitrite levels measured in the culture supernatant (μM nitrite, **P < 0.01 compared to MIN; statistical significance was obtained by one-way ANOVA followed by Bonferroni post-hoc test). (c) Effect of pre-treatment with pioglitazone (1 and 10 μM) on cortical neuronal survival in the presence of LPS and IFN-γ activated microglia in transwell co-culture (number of β-III tubulin cells per field) (**P < 0.01 compared to MIN LPS IFN, Student's t-test). (d) Effect of pre-treatment with pioglitazone (1 and 10 μM) on total axon length (**P < 0.01 compared to MIN LPS IFN, Student's t-test) in the presence of LPS and IFN-γ activated microglia in transwell co-culture (length of SMI-312 axons per field). Photomicrographs showing immunoreactivity for β-III tubulin (red) and DAPI (blue) in neuron-microglia transwell co-cultures in the presence of MIN LPS and IFN-γ (MIN LPS IFN) (e) and (f) MIN LPS IFN-γ and pioglitazone (10 μM) (MIN LPS IFN Pio 10 μM). ANOVA, analysis of variance; DAPI, 4',6-diamidino-2-phenylindole; IFN, interferon; LPS, Lipopolysaccharide. Microglial derived-nitric oxide has been shown to mediate significant neuronal and axonal loss in vitro. We examined the influence of pioglitazone pre-treatment on neuronal survival and axonal morphology in neuronal-microglial transwell co-cultures. Co-cultures were fixed and stained for βIII tubulin, SMI312 and the nuclear marker DAPI. Pre-treatment with pioglitazone (10 μM) conferred a neuroprotective effect with a significant increase in neuronal (Figure 2c) and total axon survival (Figure 2d) in transwell co-cultures of neurons and activated microglia. These data suggest that pioglitazone provides protection for cortical neurons in neuron-microglia co-cultures through mechanisms which may be independent of its effects on nitrite reduction and that cell-to-cell contact is not required for this to occur.

Mentions: To determine the effect of pioglitazone on microglial NO generation, the levels of nitrite production were measured in microglia cultured alone or in transwell co-cultures with cortical neurons (allowing for the exchange of factors between microglia and neurons, but no direct cell-cell contact). Two different doses of pioglitazone (1 μM and 10 μM) were administered to neuronal-microglial transwell cultures and microglia cultured alone, 1 hour before LPS (1 μg/ml) and IFN (100 U/ml) treatment. LPS and IFN induced a significant increase in NO generation after 48 hours (Figure 2a and 2b). However, pre-treatment with pioglitazone failed to elicit a significant reduction in nitrite production by microglia cultured alone (Figure 2a) or in transwell co-cultures (Figure 2b).


The PPAR-γ agonist pioglitazone protects cortical neurons from inflammatory mediators via improvement in peroxisomal function.

Gray E, Ginty M, Kemp K, Scolding N, Wilkins A - J Neuroinflammation (2012)

Effect of pioglitazone on microglial-induced neuronal and axonal loss in transwell co-culture. (a) Effect of pioglitazone (Pio; 1 and 10 μM) on nitrite production by microglial cultures either in the absence (MIN) or presence of LPS and IFN-γ (MIN LPS IFN). Cultures were exposed to IFN and LPS for 48 hours and nitrite levels measured in the culture supernatant (μM nitrite, **P < 0.01 compared to MIN; statistical significance was obtained by one-way ANOVA followed by Bonferroni post-hoc test. (b) Effect of pioglitazone (Pio; 1 and 10 μM) on nitrite production by neuron-microglia transwell co-cultures either in the absence (MIN) or presence of LPS and IFN-γ (MIN LPS IFN). Cultures were exposed to IFN and LPS for 48 hours and nitrite levels measured in the culture supernatant (μM nitrite, **P < 0.01 compared to MIN; statistical significance was obtained by one-way ANOVA followed by Bonferroni post-hoc test). (c) Effect of pre-treatment with pioglitazone (1 and 10 μM) on cortical neuronal survival in the presence of LPS and IFN-γ activated microglia in transwell co-culture (number of β-III tubulin cells per field) (**P < 0.01 compared to MIN LPS IFN, Student's t-test). (d) Effect of pre-treatment with pioglitazone (1 and 10 μM) on total axon length (**P < 0.01 compared to MIN LPS IFN, Student's t-test) in the presence of LPS and IFN-γ activated microglia in transwell co-culture (length of SMI-312 axons per field). Photomicrographs showing immunoreactivity for β-III tubulin (red) and DAPI (blue) in neuron-microglia transwell co-cultures in the presence of MIN LPS and IFN-γ (MIN LPS IFN) (e) and (f) MIN LPS IFN-γ and pioglitazone (10 μM) (MIN LPS IFN Pio 10 μM). ANOVA, analysis of variance; DAPI, 4',6-diamidino-2-phenylindole; IFN, interferon; LPS, Lipopolysaccharide. Microglial derived-nitric oxide has been shown to mediate significant neuronal and axonal loss in vitro. We examined the influence of pioglitazone pre-treatment on neuronal survival and axonal morphology in neuronal-microglial transwell co-cultures. Co-cultures were fixed and stained for βIII tubulin, SMI312 and the nuclear marker DAPI. Pre-treatment with pioglitazone (10 μM) conferred a neuroprotective effect with a significant increase in neuronal (Figure 2c) and total axon survival (Figure 2d) in transwell co-cultures of neurons and activated microglia. These data suggest that pioglitazone provides protection for cortical neurons in neuron-microglia co-cultures through mechanisms which may be independent of its effects on nitrite reduction and that cell-to-cell contact is not required for this to occur.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3368767&req=5

Figure 2: Effect of pioglitazone on microglial-induced neuronal and axonal loss in transwell co-culture. (a) Effect of pioglitazone (Pio; 1 and 10 μM) on nitrite production by microglial cultures either in the absence (MIN) or presence of LPS and IFN-γ (MIN LPS IFN). Cultures were exposed to IFN and LPS for 48 hours and nitrite levels measured in the culture supernatant (μM nitrite, **P < 0.01 compared to MIN; statistical significance was obtained by one-way ANOVA followed by Bonferroni post-hoc test. (b) Effect of pioglitazone (Pio; 1 and 10 μM) on nitrite production by neuron-microglia transwell co-cultures either in the absence (MIN) or presence of LPS and IFN-γ (MIN LPS IFN). Cultures were exposed to IFN and LPS for 48 hours and nitrite levels measured in the culture supernatant (μM nitrite, **P < 0.01 compared to MIN; statistical significance was obtained by one-way ANOVA followed by Bonferroni post-hoc test). (c) Effect of pre-treatment with pioglitazone (1 and 10 μM) on cortical neuronal survival in the presence of LPS and IFN-γ activated microglia in transwell co-culture (number of β-III tubulin cells per field) (**P < 0.01 compared to MIN LPS IFN, Student's t-test). (d) Effect of pre-treatment with pioglitazone (1 and 10 μM) on total axon length (**P < 0.01 compared to MIN LPS IFN, Student's t-test) in the presence of LPS and IFN-γ activated microglia in transwell co-culture (length of SMI-312 axons per field). Photomicrographs showing immunoreactivity for β-III tubulin (red) and DAPI (blue) in neuron-microglia transwell co-cultures in the presence of MIN LPS and IFN-γ (MIN LPS IFN) (e) and (f) MIN LPS IFN-γ and pioglitazone (10 μM) (MIN LPS IFN Pio 10 μM). ANOVA, analysis of variance; DAPI, 4',6-diamidino-2-phenylindole; IFN, interferon; LPS, Lipopolysaccharide. Microglial derived-nitric oxide has been shown to mediate significant neuronal and axonal loss in vitro. We examined the influence of pioglitazone pre-treatment on neuronal survival and axonal morphology in neuronal-microglial transwell co-cultures. Co-cultures were fixed and stained for βIII tubulin, SMI312 and the nuclear marker DAPI. Pre-treatment with pioglitazone (10 μM) conferred a neuroprotective effect with a significant increase in neuronal (Figure 2c) and total axon survival (Figure 2d) in transwell co-cultures of neurons and activated microglia. These data suggest that pioglitazone provides protection for cortical neurons in neuron-microglia co-cultures through mechanisms which may be independent of its effects on nitrite reduction and that cell-to-cell contact is not required for this to occur.
Mentions: To determine the effect of pioglitazone on microglial NO generation, the levels of nitrite production were measured in microglia cultured alone or in transwell co-cultures with cortical neurons (allowing for the exchange of factors between microglia and neurons, but no direct cell-cell contact). Two different doses of pioglitazone (1 μM and 10 μM) were administered to neuronal-microglial transwell cultures and microglia cultured alone, 1 hour before LPS (1 μg/ml) and IFN (100 U/ml) treatment. LPS and IFN induced a significant increase in NO generation after 48 hours (Figure 2a and 2b). However, pre-treatment with pioglitazone failed to elicit a significant reduction in nitrite production by microglia cultured alone (Figure 2a) or in transwell co-cultures (Figure 2b).

Bottom Line: To assess the influence of peroxisomal activation on nitric oxide mediated neurotoxicity, we investigated the effects of the peroxisomal proliferator activated receptor (PPAR) gamma agonist, pioglitazone in primary cortical neurons that were either exposed to a nitric oxide donor or co-cultured with activated microglia.Moreover, cortical neurons treated with this compound showed a significant increase in the protein and gene expression of PPAR-gamma, which was associated with a concomitant increase in the enzymatic activity of catalase.In addition, the protection of neurons and axons against hydrogen peroxide-induced toxicity afforded by pioglitazone appeared to be dependent on catalase.

View Article: PubMed Central - HTML - PubMed

Affiliation: Multiple Sclerosis and Stem Cell Group, Burden Centre, Institute of Clinical Neurosciences, Frenchay Hospital, University of Bristol, Bristol BS16 1JB, UK. elizabeth.gray@bristol.ac.uk

ABSTRACT

Background: Inflammation is known to play a pivotal role in mediating neuronal damage and axonal injury in a variety of neurodegenerative disorders. Among the range of inflammatory mediators, nitric oxide and hydrogen peroxide are potent neurotoxic agents. Recent evidence has suggested that oligodendrocyte peroxisomes may play an important role in protecting neurons from inflammatory damage.

Methods: To assess the influence of peroxisomal activation on nitric oxide mediated neurotoxicity, we investigated the effects of the peroxisomal proliferator activated receptor (PPAR) gamma agonist, pioglitazone in primary cortical neurons that were either exposed to a nitric oxide donor or co-cultured with activated microglia.

Results: Pioglitazone protected neurons and axons against both nitric-oxide donor-induced and microglia-derived nitric oxide-induced toxicity. Moreover, cortical neurons treated with this compound showed a significant increase in the protein and gene expression of PPAR-gamma, which was associated with a concomitant increase in the enzymatic activity of catalase. In addition, the protection of neurons and axons against hydrogen peroxide-induced toxicity afforded by pioglitazone appeared to be dependent on catalase.

Conclusions: Collectively, these observations provide evidence that modulation of PPAR-gamma activity and peroxisomal function by pioglitazone attenuates both NO and hydrogen peroxide-mediated neuronal and axonal damage suggesting a new therapeutic approach to protect against neurodegenerative changes associated with neuroinflammation.

Show MeSH
Related in: MedlinePlus