Formyl-methionyl-leucyl-phenylalanine-induced dopaminergic neurotoxicity via microglial activation: A mediator between peripheral infection and neurodegeneration?

Xi Gao, Xiaoming Hu, Li Qian, Sufen Yang, Wei Zhang, Dan Zhang, Xuefei Wu, Alison Fraser, Belinda Wilson, Patrick M. Flood, Michelle Block, Jau Shyong Hong

Research output: Contribution to journalArticle

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Abstract

Background: Parkinson disease (PD), a chronic neurodegenerative disease, has been proposed to be a multifactorial disorder resulting from a combination of environmental mechanisms (chemical, infectious, and traumatic), aging, and genetic deficits. Microglial activation is important in the pathogenesis of PD. Objectives: We investigated dopaminergic (DA) neurotoxicity and the underlying mechanisms of formyl-methionyl-leucyl-phenylalanine (fMLP), a bacteria-derived peptide, in relation to PD. Methods: We measured DA neurotoxicity using a DA uptake assay and immunocytochemical staining (ICC) in primary mesencephalic cultures from rodents. Microglial activation was observed via ICC, flow cytometry, and superoxide measurement. Results: fMLP can cause selective DA neuronal loss at concentrations as low as 10-13 M. Further, fMLP (10-13 M) led to a significant reduction in DA uptake capacity in neuron/glia (N/G) cultures, but not in microglia-depleted cultures, indicating an indispensable role of microglia in fMLP-induced neurotoxicity. Using ICC of a specific microglial marker, OX42, we observed morphologic changes in activated microglia after fMLP treatment. Microglial activation after fMLP treatment was confirmed by flow cytometry analysis of major histocompatibility antigen class II expression on a microglia HAPI cell line. Mechanistic studies revealed that fMLP (10-13 M)-induced increase in the production of extracellular superoxide from microglia is critical in mediating fMLP-elicited neurotoxicity. Pharmacologic inhibition of NADPH oxidase (PHOX) with diphenylene-iodonium or apocynin abolished the DA neurotoxicity of fMLP. N/G cultures from PHOX-deficient (gp91PHOX-/-) mice were also insensitive to fMLP-induced DA neurotoxicity. Conclusion: fMLP (10-13 M) induces DA neurotoxicity through activation of microglial PHOX and subsequent production of superoxide, suggesting a role of fMLP in the central nervous system inflammatory process.

Original languageEnglish (US)
Pages (from-to)593-598
Number of pages6
JournalEnvironmental Health Perspectives
Volume116
Issue number5
DOIs
StatePublished - May 2008
Externally publishedYes

Fingerprint

methionyl-leucyl-phenylalanine
Chemical activation
Infection
Microglia
flow cytometry
Superoxides
Parkinson Disease
Flow cytometry
Staining and Labeling
nervous system
neurotoxicity
infection
antigen
Flow Cytometry
peptide
rodent
Neurodegenerative diseases
assay
NADPH Oxidase
Histocompatibility Antigens Class II

Keywords

  • FMLP
  • Inflammation
  • Microglia
  • NADPH oxidase
  • Neurotoxicity

ASJC Scopus subject areas

  • Environmental Science(all)
  • Environmental Chemistry
  • Public Health, Environmental and Occupational Health

Cite this

Formyl-methionyl-leucyl-phenylalanine-induced dopaminergic neurotoxicity via microglial activation : A mediator between peripheral infection and neurodegeneration? / Gao, Xi; Hu, Xiaoming; Qian, Li; Yang, Sufen; Zhang, Wei; Zhang, Dan; Wu, Xuefei; Fraser, Alison; Wilson, Belinda; Flood, Patrick M.; Block, Michelle; Hong, Jau Shyong.

In: Environmental Health Perspectives, Vol. 116, No. 5, 05.2008, p. 593-598.

Research output: Contribution to journalArticle

Gao, Xi ; Hu, Xiaoming ; Qian, Li ; Yang, Sufen ; Zhang, Wei ; Zhang, Dan ; Wu, Xuefei ; Fraser, Alison ; Wilson, Belinda ; Flood, Patrick M. ; Block, Michelle ; Hong, Jau Shyong. / Formyl-methionyl-leucyl-phenylalanine-induced dopaminergic neurotoxicity via microglial activation : A mediator between peripheral infection and neurodegeneration?. In: Environmental Health Perspectives. 2008 ; Vol. 116, No. 5. pp. 593-598.
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abstract = "Background: Parkinson disease (PD), a chronic neurodegenerative disease, has been proposed to be a multifactorial disorder resulting from a combination of environmental mechanisms (chemical, infectious, and traumatic), aging, and genetic deficits. Microglial activation is important in the pathogenesis of PD. Objectives: We investigated dopaminergic (DA) neurotoxicity and the underlying mechanisms of formyl-methionyl-leucyl-phenylalanine (fMLP), a bacteria-derived peptide, in relation to PD. Methods: We measured DA neurotoxicity using a DA uptake assay and immunocytochemical staining (ICC) in primary mesencephalic cultures from rodents. Microglial activation was observed via ICC, flow cytometry, and superoxide measurement. Results: fMLP can cause selective DA neuronal loss at concentrations as low as 10-13 M. Further, fMLP (10-13 M) led to a significant reduction in DA uptake capacity in neuron/glia (N/G) cultures, but not in microglia-depleted cultures, indicating an indispensable role of microglia in fMLP-induced neurotoxicity. Using ICC of a specific microglial marker, OX42, we observed morphologic changes in activated microglia after fMLP treatment. Microglial activation after fMLP treatment was confirmed by flow cytometry analysis of major histocompatibility antigen class II expression on a microglia HAPI cell line. Mechanistic studies revealed that fMLP (10-13 M)-induced increase in the production of extracellular superoxide from microglia is critical in mediating fMLP-elicited neurotoxicity. Pharmacologic inhibition of NADPH oxidase (PHOX) with diphenylene-iodonium or apocynin abolished the DA neurotoxicity of fMLP. N/G cultures from PHOX-deficient (gp91PHOX-/-) mice were also insensitive to fMLP-induced DA neurotoxicity. Conclusion: fMLP (10-13 M) induces DA neurotoxicity through activation of microglial PHOX and subsequent production of superoxide, suggesting a role of fMLP in the central nervous system inflammatory process.",
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author = "Xi Gao and Xiaoming Hu and Li Qian and Sufen Yang and Wei Zhang and Dan Zhang and Xuefei Wu and Alison Fraser and Belinda Wilson and Flood, {Patrick M.} and Michelle Block and Hong, {Jau Shyong}",
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T1 - Formyl-methionyl-leucyl-phenylalanine-induced dopaminergic neurotoxicity via microglial activation

T2 - A mediator between peripheral infection and neurodegeneration?

AU - Gao, Xi

AU - Hu, Xiaoming

AU - Qian, Li

AU - Yang, Sufen

AU - Zhang, Wei

AU - Zhang, Dan

AU - Wu, Xuefei

AU - Fraser, Alison

AU - Wilson, Belinda

AU - Flood, Patrick M.

AU - Block, Michelle

AU - Hong, Jau Shyong

PY - 2008/5

Y1 - 2008/5

N2 - Background: Parkinson disease (PD), a chronic neurodegenerative disease, has been proposed to be a multifactorial disorder resulting from a combination of environmental mechanisms (chemical, infectious, and traumatic), aging, and genetic deficits. Microglial activation is important in the pathogenesis of PD. Objectives: We investigated dopaminergic (DA) neurotoxicity and the underlying mechanisms of formyl-methionyl-leucyl-phenylalanine (fMLP), a bacteria-derived peptide, in relation to PD. Methods: We measured DA neurotoxicity using a DA uptake assay and immunocytochemical staining (ICC) in primary mesencephalic cultures from rodents. Microglial activation was observed via ICC, flow cytometry, and superoxide measurement. Results: fMLP can cause selective DA neuronal loss at concentrations as low as 10-13 M. Further, fMLP (10-13 M) led to a significant reduction in DA uptake capacity in neuron/glia (N/G) cultures, but not in microglia-depleted cultures, indicating an indispensable role of microglia in fMLP-induced neurotoxicity. Using ICC of a specific microglial marker, OX42, we observed morphologic changes in activated microglia after fMLP treatment. Microglial activation after fMLP treatment was confirmed by flow cytometry analysis of major histocompatibility antigen class II expression on a microglia HAPI cell line. Mechanistic studies revealed that fMLP (10-13 M)-induced increase in the production of extracellular superoxide from microglia is critical in mediating fMLP-elicited neurotoxicity. Pharmacologic inhibition of NADPH oxidase (PHOX) with diphenylene-iodonium or apocynin abolished the DA neurotoxicity of fMLP. N/G cultures from PHOX-deficient (gp91PHOX-/-) mice were also insensitive to fMLP-induced DA neurotoxicity. Conclusion: fMLP (10-13 M) induces DA neurotoxicity through activation of microglial PHOX and subsequent production of superoxide, suggesting a role of fMLP in the central nervous system inflammatory process.

AB - Background: Parkinson disease (PD), a chronic neurodegenerative disease, has been proposed to be a multifactorial disorder resulting from a combination of environmental mechanisms (chemical, infectious, and traumatic), aging, and genetic deficits. Microglial activation is important in the pathogenesis of PD. Objectives: We investigated dopaminergic (DA) neurotoxicity and the underlying mechanisms of formyl-methionyl-leucyl-phenylalanine (fMLP), a bacteria-derived peptide, in relation to PD. Methods: We measured DA neurotoxicity using a DA uptake assay and immunocytochemical staining (ICC) in primary mesencephalic cultures from rodents. Microglial activation was observed via ICC, flow cytometry, and superoxide measurement. Results: fMLP can cause selective DA neuronal loss at concentrations as low as 10-13 M. Further, fMLP (10-13 M) led to a significant reduction in DA uptake capacity in neuron/glia (N/G) cultures, but not in microglia-depleted cultures, indicating an indispensable role of microglia in fMLP-induced neurotoxicity. Using ICC of a specific microglial marker, OX42, we observed morphologic changes in activated microglia after fMLP treatment. Microglial activation after fMLP treatment was confirmed by flow cytometry analysis of major histocompatibility antigen class II expression on a microglia HAPI cell line. Mechanistic studies revealed that fMLP (10-13 M)-induced increase in the production of extracellular superoxide from microglia is critical in mediating fMLP-elicited neurotoxicity. Pharmacologic inhibition of NADPH oxidase (PHOX) with diphenylene-iodonium or apocynin abolished the DA neurotoxicity of fMLP. N/G cultures from PHOX-deficient (gp91PHOX-/-) mice were also insensitive to fMLP-induced DA neurotoxicity. Conclusion: fMLP (10-13 M) induces DA neurotoxicity through activation of microglial PHOX and subsequent production of superoxide, suggesting a role of fMLP in the central nervous system inflammatory process.

KW - FMLP

KW - Inflammation

KW - Microglia

KW - NADPH oxidase

KW - Neurotoxicity

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