Publications by authors named "Ming F Johnson"

Diffuse axonal injury is recognized as a progressive and long-term consequence of traumatic brain injury. Axonal injury can have sustained negative consequences on neuronal functions such as anterograde and retrograde transport and cellular processes such as autophagy that depend on cytoarchitecture and axon integrity. These changes can lead to somatic atrophy and an inability to repair and promote plasticity.

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Cytokines such as TNFα can polarize microglia/macrophages into different neuroinflammatory types. Skewing of the phenotype towards a cytotoxic state is thought to impair phagocytosis and has been described in Alzheimer's Disease (AD). Neuroinflammation can be perpetuated by a cycle of increasing cytokine production and maintenance of a polarized activation state that contributes to AD progression.

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Autophagy is a fundamental cellular recycling process vulnerable to compromise in neurodegeneration. We now report that a cell-penetrating neurotrophic and neuroprotective derivative of the central nervous system (CNS) metabolite, lanthionine ketimine (LK), stimulates autophagy in RG2 glioma and SH-SY5Y neuroblastoma cells at concentrations within or below pharmacological levels reported in previous mouse studies. Autophagy stimulation was evidenced by increased lipidation of microtubule-associated protein 1 light chain 3 (LC3) both in the absence and presence of bafilomycin-A1 which discriminates between effects on autophagic flux versus blockage of autophagy clearance.

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Lanthionine ketimine ([LK] 3,4-dihydro-2H-1,4-thiazine-3,5-dicarboxylic acid) is the archetype for a family of naturally occurring brain sulfur amino acid metabolites, the physiologic function of which is unknown. Lanthionine ketimine and its synthetic derivatives have recently demonstrated neurotrophic, neuroprotective, and antineuroinflammatory properties in vitro through a proposed mechanism involving the microtubule-associated protein collapsin response mediator protein 2. Therefore, studies were undertaken to test the effects of a bioavailable LK ester in the 3 × Tg-AD mouse model of Alzheimer disease.

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Background: Myeloid derived suppressor cells (MDSC) are important regulators of immune responses. We evaluated the mechanistic role of MDSC depletion on antigen presenting cell (APC), NK, T cell activities and therapeutic vaccination responses in murine models of lung cancer.

Principal Findings: Individual antibody mediated depletion of MDSC (anti-Gr1 or anti-Ly6G) enhanced the antitumor activity against lung cancer.

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Background: Chronic neuroinflammation is an important component of Alzheimer's disease and could contribute to neuronal dysfunction, injury and loss that lead to disease progression. Multiple clinical studies implicate tumor necrosis factor-α as an inflammatory mediator of neurodegeneration in patients with Alzheimer's because of elevated levels of this cytokine in the cerebrospinal fluid, hippocampus and cortex. Current Alzheimer's disease interventions are symptomatic treatments with limited efficacy that do not address etiology.

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Numerous studies suggest a central role for the low-density lipoprotein receptor-related protein/transforming growth factor beta receptor V in Alzheimer's Disease. We continue our investigation of a ligand for this receptor, transforming growth factor beta2, which is also implicated in Alzheimer Disease pathogenesis, but whose mechanism(s) remain elusive. Confocal imaging reveals that transforming growth factor beta2 rapidly targets amyloid beta peptide to the lysosomal compartment in cortical neurons and induces cell death.

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