CX3CL1 reduces neurotoxicity and microglial activation in a rat model of Parkinson's disease.
BACKGROUND
Parkinson's disease is characterized by a progressive loss of dopaminergic neurons in the substantia nigra. The cause of the neurodegeneration is unknown. Neuroinflammation has been clearly shown in Parkinson's disease and may be involved in the progressive nature of the disease. Microglia are capable of producing neuronal damage through the production of bioactive molecules such as cytokines, as well as reactive oxygen species (ROS), and nitric oxide (NO). The inflammatory response in the brain is tightly regulated at multiple levels. One form of immune regulation occurs via neurons. Fractalkine (CX3CL1), produced by neurons, suppresses the activation of microglia. CX3CL1 is constitutively expressed. It is not known if addition of exogenous CX3CL1 beyond otherwise physiologically normal levels could decrease microglia activation and thereby minimize the secondary neurodegeneration following a neurotoxic insult.


METHODS
The intrastriatal 6-hydroxydopamine (6-OHDA) rat model of Parkinson disease, was used to test the hypothesis that exogenous CX3CL1 could be neuroprotective. Treatment with recombinant CX3CL1 was delivered to the striatum by an osmotic minipump for 28 days beginning 7 days after the initial insult. Unbiased stereological methods were used to quantify the lesion size in the striatum, the amount of neuronal loss in the substantia nigra, and the amount of microglia activation.


RESULTS
As hypothesized, CX3CL1 was able to suppress this microglia activation. The reduced microglia activation was found to be neuroprotective as the CX3CL1 treated rats had a smaller lesion volume in the striatum and importantly significantly fewer neurons were lost in the CX3CL1 treated rats.


CONCLUSIONS
These findings demonstrated that CX3CL1 plays a neuroprotective role in 6-OHDA-induced dopaminergic lesion and it might be an effective therapeutic target for many neurodegenerative diseases, including Parkinson disease and Alzheimer disease, where inflammation plays an important role.
Department of Molecular Pharmacology and Physiology, University of South Florida, College of Medicine, Tampa, FL 33612, USA.
Mibel M
MM
Pabon
Adam D
AD
Bachstetter
Charles E
CE
Hudson
Carmelina
C
Gemma
Paula C
PC
Bickford
D000818:Animals; D054428:Chemokine CX3CL1 / Q000235:genetics / Q000494:pharmacology* / Q000633:toxicity*; D003342:Corpus Striatum / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D004195:Disease Models, Animal; D006801:Humans; D008297:Male; D017628:Microglia / Q000166:cytology / Q000187:drug effects* / Q000502:physiology*; D009410:Nerve Degeneration / Q000188:drug therapy / Q000473:pathology; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000473:pathology / Q000502:physiology; D016627:Oxidopamine / Q000494:pharmacology; D010300:Parkinson Disease / Q000188:drug therapy* / Q000473:pathology* / Q000503:physiopathology; D051381:Rats; D011916:Rats, Inbred F344; D013378:Substantia Nigra / Q000187:drug effects / Q000378:metabolism / Q000473:pathology
D054428:Chemokine CX3CL1; D016627:Oxidopamine
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