Anti-ICAM-1 (Ab-512) Antibody (A41240)

CD200-CD200R signaling holds microglia in a quiescent state. Parkinson disease (PD) neurodegeneration may be associated with impairment of CD200-CD200R-mediated microglia silencing in the substantia nigra (SN). In this study, an anti-CD200R blocking antibody (ACDR) selectively and significantly enhanced the susceptibility of dopaminergic neurons to neurotoxicity induced by rotenone (Rot) and iron (Ir) in mesencephalic neuron/glia cultures. Microglia were shown to mediate dopaminergic neurotoxicity induced by ACDR/Rot (combination of ACDR and Rot) and ACDR/Ir (combination of ACDR and Ir). ACDR significantly enhanced the microglial activation induced by Rot and Ir in neuron/glia cultures. NADPH oxidase-mediated superoxide generation was a key contributor to dopaminergic neurotoxicity induced by ACDR/Rot and ACDR/Ir. p38 MAPK contributed to NADPH oxidase activation induced by ACDR/Rot and ACDR/Ir. Interestingly, there were a decrease in CD200 expression (mRNA and protein) and an enhancement of microglial response (MHCII mRNA and ICAM-1 protein) in the rat SN with aging. ICAM-1 expression was significantly inversely correlated with CD200 expression. These results strongly indicate the participation of SN CD200-CD200R dysfunction in the etiopathogenesis of PD and provide a new insight into the molecular mechanisms underlying the involvement of aging in PD and help to elucidate the mechanisms of the combined involvement of immune/inflammatory factors, environmental substances, and aging in PD.

Astrocytes play an active role in the central nervous system and are critically involved in astrogliosis, a homotypic response of these cells to disease, injury, and associated neuroinflammation. Among the numerous molecules involved in these processes are the matrix metalloproteinases (MMPs), a family of zinc-dependent endopeptidases, secreted or membrane-bound, that regulate by proteolytic cleavage the extracellular matrix, cytokines, chemokines, cell adhesion molecules, and plasma membrane receptors. MMP activity is tightly regulated by the tissue inhibitors of MMPs (TIMPs), a family of secreted multifunctional proteins. Astrogliosis in vivo and astrocyte reactivity induced in vitro by proinflammatory cues are associated with modulation of expression and/or activity of members of the MMP/TIMP system. However, nothing is known concerning the intracellular distribution and secretory pathways of MMPs and TIMPs in astrocytes. Using a combination of cell biology, biochemistry, fluorescence and electron microscopy approaches, we investigated in cultured reactive astrocytes the intracellular distribution, transport, and secretion of MMP-2, MMP-9, TIMP-1, and TIMP-2. MMP-2 and MMP-9 demonstrate nuclear localization, differential intracellular vesicular distribution relative to the myosin V and kinesin molecular motors, and LAMP-2-labeled lysosomal compartment, and we show vesicular secretion for MMP-2, MMP-9, and their inhibitors. Our results suggest that these proteinases and their inhibitors use different pathways for trafficking and secretion for distinct astrocytic functions.