ABSTRACT
Whereas chemokines are well known for their ability to induce cell migration, only recently it became evident that chemokines also control a variety of other cell functions and are versatile messengers in the interaction between a diversity of cell types. In the central nervous system (CNS), chemokines are generally found under both physiological and pathological conditions. Whereas many reports describe chemokine expression in astrocytes and microglia and their role in the migration of leukocytes into the CNS, only few studies describe chemokine expression in neurons. Nevertheless, the expression of neuronal chemokines and the corresponding chemokine receptors in CNS cells under physiological and pathological conditions indicates that neuronal chemokines contribute to CNS cell interaction. In this study, we review recent studies describing neuronal chemokine expression and discuss potential roles of neuronal chemokines in neuron-astrocyte, neuron-microglia, and neuron-neuron interaction.
Subject(s)
Central Nervous System , Chemokines/metabolism , Animals , Astrocytes/metabolism , Calcium/metabolism , Cell Movement , Cell Proliferation , Central Nervous System/cytology , Central Nervous System/metabolism , Chemokines/classification , Chemokines/genetics , Humans , Microglia/metabolism , Neurons/metabolism , Receptors, Chemokine/metabolism , Synaptic Transmission/physiologyABSTRACT
Since activated microglia are able to phagocytose damaged cells and subsequently express major histocompatibility complex class II (MHC-II) and co-stimulatory proteins, they are considered to function as antigen presenting cells (APCs) in the central nervous system. The maturation and migratory potential of professional APCs is associated with the expression of chemokine receptor CCR7. We therefore investigated whether the immunological activation of microglia induces CCR7 expression. We here present that activation of cultured microglia by both the innate antigen lipopolysaccharide and protein antigen ovalbumin rapidly induces CCR7 expression, accompanied by increased MHC-II expression. Moreover, it is shown that CCR7 expression in IBA-1 positive cells is induced during the symptom onset and progression of experimental autoimmune encephalomyelitis, a rodent model for multiple sclerosis. These results suggest that microglia express CCR7 under specific inflammatory conditions, corroborating the idea that microglia develop into APCs with migratory potential toward lymphoid chemokines.
Subject(s)
Antigen Presentation/immunology , Antigen-Presenting Cells/immunology , Chemotaxis/immunology , Gliosis/immunology , Microglia/immunology , Receptors, Chemokine/immunology , Animals , Animals, Newborn , Antigens/immunology , Disease Models, Animal , Encephalitis/immunology , Encephalitis/physiopathology , Encephalomyelitis, Autoimmune, Experimental/immunology , Encephalomyelitis, Autoimmune, Experimental/physiopathology , Female , Histocompatibility Antigens Class II/immunology , Lipopolysaccharides/immunology , Mice , Mice, Inbred C57BL , Mice, Knockout , Ovalbumin/immunology , Phagocytosis/immunology , Receptors, CCR7 , Receptors, Chemokine/geneticsABSTRACT
Embryonic mouse neural stem cells (NSCs) were isolated from E14 mice, multiplied in medium containing epidermal growth factor (EGF) and basic fibroblast growth factor (bFGF) and plated in laminin-coated wells in basic serum-free neurobasal medium. After 7 days in vitro, approximately 20% of the embryonic mouse NSCs developed into morphologically and biochemically fully maturated neurons, with extensive dendrites and multiple synaptic contacts. However, even after 22 days of culture, none of these neurons developed voltage-dependent sodium-channels characteristic for a functional neuron. Apparently, the morphological differentiation and the electrophysiological maturation of an embryonic mouse NSC into a neuron are independently regulated.
Subject(s)
Cell Differentiation/physiology , Neurons/cytology , Stem Cells/cytology , Animals , Cells, Cultured , Electric Stimulation/methods , Embryo, Mammalian , Epidermal Growth Factor/physiology , Fibroblast Growth Factor 2/physiology , Glial Fibrillary Acidic Protein/physiology , Immunohistochemistry/methods , Membrane Potentials/physiology , Membrane Potentials/radiation effects , Mice , Mice, Inbred C57BL , Microtubule-Associated Proteins/metabolism , Neurons/physiology , Patch-Clamp Techniques/methods , Stem Cells/physiologyABSTRACT
Desferal free radical (DFFR) photogenerated from dye sensitization was studied by electron spin resonance. When irradiated at the visible maximum in the presence of O2, both rose bengal and riboflavin sensitized the oxidation of Desferal (DF) and generated the DFFR. The yield of DFFR was amplified by superoxide dismutase (SOD). The SOD enhancement was attributed to the inhibition of superoxide-induced DFFR destruction. Similar SOD enhancement was observed with dyes Rhodamine 123 and Gentian Violet. Our studies suggest that when Desferal is used as a chelating agent in the presence of SOD, systems involving O2- could face interference from DFFR even at concentrations as low as 10 microM DF. DFFR may interfere with the chain reaction of lipid peroxidation resulting in an apparent protective action which, in fact, has very little to do with chelating the catalytic iron.
