Correction: Mice Hemizygous for a Pathogenic Mitofusin-2 Allele Exhibit Hind Limb/Foot Gait Deficits and Phenotypic Perturbations in Nerve and Muscle.

[This corrects the article DOI: 10.1371/journal.pone.

Suppressing N-Acetyl-l-Aspartate Synthesis Prevents Loss of Neurons in a Murine Model of Canavan Leukodystrophy.

Unlabelled: Canavan disease is a leukodystrophy caused by aspartoacylase (ASPA) deficiency. The lack of functional ASPA, an enzyme enriched in oligodendroglia that cleaves N-acetyl-l-aspartate (NAA) to acetate and l-aspartic acid, elevates brain NAA and causes "spongiform" vacuolation of superficial brain white matter and neighboring gray matter. In children with Canavan disease, neuroimaging shows early-onset dysmyelination and progressive brain atrophy.

Mice Hemizygous for a Pathogenic Mitofusin-2 Allele Exhibit Hind Limb/Foot Gait Deficits and Phenotypic Perturbations in Nerve and Muscle.

Charcot-Marie-Tooth disease type 2A (CMT2A), the most common axonal form of hereditary sensory motor neuropathy, is caused by mutations of mitofusin-2 (MFN2). Mitofusin-2 is a GTPase required for fusion of mitochondrial outer membranes, repair of damaged mitochondria, efficient mitochondrial energetics, regulation of mitochondrial-endoplasmic reticulum calcium coupling and axonal transport of mitochondria. We knocked T105M MFN2 preceded by a loxP-flanked STOP sequence into the mouse Rosa26 locus to permit cell type-specific expression of this pathogenic allele.

Therapeutic depletion of monocyte-derived cells protects from long-term axonal loss in experimental autoimmune encephalomyelitis.

Studies in multiple sclerosis and its animal model experimental autoimmune encephalomyelitis (EAE) suggest that peripheral monocyte-derived cells (MDCs) are instrumental for disease initiation. MDCs, however, are plastic, and may exert various functions once in the central nervous system (CNS) for prolonged periods. Furthermore, the long-term effect of MDC depletion on continuing axon loss is not known.

Ablating N-acetylaspartate prevents leukodystrophy in a Canavan disease model.

Canavan disease is caused by inactivating ASPA (aspartoacylase) mutations that prevent cleavage of N-acetyl-L-aspartate (NAA), resulting in marked elevations in central nervous system (CNS) NAA and progressively worsening leukodystrophy. We now report that ablating NAA synthesis by constitutive genetic disruption of Nat8l (N-acetyltransferase-8 like) permits normal CNS myelination and prevents leukodystrophy in a murine Canavan disease model.

Deletion of astroglial CXCL10 delays clinical onset but does not affect progressive axon loss in a murine autoimmune multiple sclerosis model.

Multiple sclerosis (MS) is characterized by central nervous system (CNS) inflammation, demyelination, and axonal degeneration. CXCL10 (IP-10), a chemokine for CXCR3+ T cells, is known to regulate T cell differentiation and migration in the periphery, but effects of CXCL10 produced endogenously in the CNS on immune cell trafficking are unknown. We created floxed cxcl10 mice and crossed them with mice carrying an astrocyte-specific Cre transgene (mGFAPcre) to ablate astroglial CXCL10 synthesis.

Conditional ablation of astroglial CCL2 suppresses CNS accumulation of M1 macrophages and preserves axons in mice with MOG peptide EAE.

Current multiple sclerosis (MS) therapies only partially prevent chronically worsening neurological deficits, which are largely attributable to progressive loss of CNS axons. Prior studies of experimental autoimmune encephalomyelitis (EAE) induced in C57BL/6 mice by immunization with myelin oligodendrocyte glycoprotein peptide 35-55 (MOG peptide), a model of MS, documented continued axon loss for months after acute CNS inflammatory infiltrates had subsided, and massive astroglial induction of CCL2 (MCP-1), a chemokine for CCR2(+) monocytes. We now report that conditional deletion of astroglial CCL2 significantly decreases CNS accumulation of classically activated (M1) monocyte-derived macrophages and microglial expression of M1 markers during the initial CNS inflammatory phase of MOG peptide EAE, reduces the acute and long-term severity of clinical deficits and slows the progression of spinal cord axon loss.

Neuronopathy in the motor neocortex in a chronic model of multiple sclerosis.

We provide evidence of cortical neuronopathy in myelin oligodendrocyte glycoprotein peptide-induced experimental autoimmune encephalomyelitis, an established model of chronic multiple sclerosis. To investigate phenotypic perturbations in neurons in this model, we used apoptotic markers and immunohistochemistry with antibodies to NeuN and other surrogate markers known to be expressed by adult pyramidal Layer V somas, including annexin V, encephalopsin, and Emx1. We found no consistent evidence of chronic loss of Layer V neurons but detected both reversible and chronic decreases in the expression of these markers in conjunction with evidence of cortical demyelination and presynaptic loss.

Disruption of NMDA receptors in oligodendroglial lineage cells does not alter their susceptibility to experimental autoimmune encephalomyelitis or their normal development.

Pharmacological studies have suggested that oligodendroglial NMDA glutamate receptors (NMDARs) mediate white matter injury in a variety of CNS diseases, including multiple sclerosis (MS). We tested this hypothesis in experimental autoimmune encephalomyelitis (EAE), a model of human MS, by timed conditional disruption of oligodendroglial NR1, an essential subunit of functional NMDARs, using an inducible proteolipid protein (Plp) promoter-driven Cre-loxP recombination system. We found that selective ablation of oligodendroglial NR1 did not alter the clinical severity of EAE elicited in C57BL/6 mice by immunization with myelin oligodendrocyte glycoprotein peptide 35-55 (MOG-peptide), nor were there significant differences between the oligodendroglial NR1 KO and non-KO mice in numbers of axons lost in spinal cord dorsal funiculi or severity of spinal cord demyelination.

Macroglial plasticity and the origins of reactive astroglia in experimental autoimmune encephalomyelitis.

Accumulations of hypertrophic, intensely glial fibrillary acidic protein-positive (GFAP(+)) astroglia, which also express immunoreactive nestin and vimentin, are prominent features of multiple sclerosis lesions. The issues of the cellular origin of hypertrophic GFAP(+)/vimentin(+)/nestin(+) "reactive" astroglia and also the plasticities and lineage relationships among three macroglial progenitor populations-oligodendrocyte progenitor cells (OPCs), astrocytes and ependymal cells-during multiple sclerosis and other CNS diseases remain controversial. We used genetic fate-mappings with a battery of inducible Cre drivers (Olig2-Cre-ER(T2), GFAP-Cre-ER(T2), FoxJ1-Cre-ER(T2) and Nestin-Cre-ER(T2)) to explore these issues in adult mice with myelin oligodendrocyte glycoprotein peptide-induced experimental autoimmune encephalomyelitis (EAE).

Pyramidal neurons are generated from oligodendroglial progenitor cells in adult piriform cortex.

Previous studies have shown that oligodendroglial progenitor cells (OPCs) can give rise to neurons in vitro and in perinatal cerebral cortex in vivo. We now report that OPCs in adult murine piriform cortex express low levels of doublecortin, a marker for migratory and immature neurons. Additionally, these OPCs express Sox2, a neural stem cell marker, and Pax6, a transcription factor characteristic of progenitors for cortical glutamatergic neurons.

Initiation and progression of axonopathy in experimental autoimmune encephalomyelitis.

Axonal loss is the principal cause of chronic disability in multiple sclerosis and experimental autoimmune encephalomyelitis (EAE). In C57BL/6 mice with EAE induced by immunization with myelin oligodendrocyte glycoprotein peptide 35-55, the first evidences of axonal damage in spinal cord were in acute subpial and perivascular foci of infiltrating neutrophils and lymphocytes and included intra-axonal accumulations of the endovesicular Toll-like receptor TLR8, and the inflammasome protein NAcht leucine-rich repeat protein 1 (NALP1). Later in the course of this illness, focal inflammatory infiltrates disappeared from the spinal cord, but there was persistent activation of spinal cord innate immunity and progressive, bilaterally symmetric loss of small-diameter corticospinal tract axons.

Pharmacokinetic characterization in xenografted mice of a series of first-generation mimics for HLA-DR antibody, Lym-1, as carrier molecules to image and treat lymphoma.

Unlabelled: Despite their large size, antibodies (Abs) are suitable carriers to deliver systemic radiotherapy, often molecular image-based, for lymphoma and leukemia. Lym-1 Ab has proven to be an effective radioisotope carrier, even in small amounts, for targeting human leukocyte antigen DR (HLA-DR), a surface membrane protein overexpressed on B-cell lymphoma. Pairs of molecules (referred to as ligands), shown by computational and experimental methods to bind to each of 2 sites within the Lym-1 epitopic region, have been linked to generate small (<2 kDa) molecules (referred to as selective high-affinity ligands [SHALs]) to mimic the targeting properties of Lym-1 Ab.

Thermal dosimetry predictive of efficacy of 111In-ChL6 nanoparticle AMF--induced thermoablative therapy for human breast cancer in mice.

Unlabelled: Antibody (mAb)-linked iron oxide nanoparticles (bioprobes) provide the opportunity to develop tumor specific thermal therapy (Rx) for metastatic cancer when inductively heated by an externally applied alternating magnetic field (AMF). To evaluate the potential of this Rx, in vivo tumor targeting, efficacy, and predictive radionuclide-based heat dosimetry were studied using (111)In-ChL6 bioprobes (ChL6 is chimeric L6) in a human breast cancer xenograft model.

Methods: Using carbodiimide, (111)In-DOTA-ChL6 (DOTA is dodecanetetraacetic acid) was conjugated to polyethylene glycol-iron oxide-impregnated dextran 20-nm particles and purified as (111)In-bioprobes.

Implantation of different malignant human cell lines in an athymic mouse does not alter success and growth rates of either xenograft.

Purpose: Human xenografts in athymic mice are frequently used as preclinical models of cancer to investigate the targeting of drugs. In order to distinguish specific from nonspecific targeting of the xenograft, the mice can be implanted with different malignant cell lines. We studied in xenograft success and growth rates after implantation of human lymphoma and breast cancer cells to begin an assessment of the validity of this approach for distinguishing specific from nonspecific targeting.

Does paclitaxel (Taxol) given after (111)In-labeled monoclonal antibodies increase tumor-cumulated activity in epithelial cancers?

Purpose: Paclitaxel synergized radiolabeled monoclonal antibodies, enhancing therapeutic effect in studies in mice with human xenografts. Paclitaxel was also observed to increase tumor uptake in imaging studies of (111)In-DOTA-Gly3Phe-m170 in patients with breast and prostate cancers. Further evaluations of tissue-cumulated activities, therapeutic indices, and pharmacokinetics were done using data for patients with breast and prostate cancer and for mice with human breast cancer xenografts.

Development of tumor targeting bioprobes ((111)In-chimeric L6 monoclonal antibody nanoparticles) for alternating magnetic field cancer therapy.

Objectives: (111)In-chimeric L6 (ChL6) monoclonal antibody (mAb)-linked iron oxide nanoparticle (bioprobes) pharmacokinetics, tumor uptake, and the therapeutic effect of inductively heating these bioprobes by externally applied alternating magnetic field (AMF) were studied in athymic mice bearing human breast cancer HBT 3477 xenografts. Tumor cell radioimmunotargeting of the bioprobes and therapeutic and toxic responses were determined.

Methods: Using 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide HCl, (111)In-7,10-tetra-azacyclododecane-N, N',N'',N'''-tetraacetic acid-ChL6 was conjugated to the carboxylated polyethylene glycol on dextran-coated iron oxide 20 nm particles, one to two mAbs per nanoparticle.

Preclinical evaluation of cathepsin-degradable peptide linkers for radioimmunoconjugates.

Purpose: Immunoglobulins are catabolized in the hepatocytes, primarily by cathepsins. The liver becomes the likely dose-limiting tissue for radiometals, like (90)Y, in radioimmunoconjugates (RICs) used for radioimmunotherapy in combination with bone marrow support. To assess whether in vitro cathepsin-degradable peptide linkers between the chelated radiometal and the antibody decreased hepatic radiation dose, cumulated activity was used as a surrogate for radiation dose.

Anti-CD22 ligand-blocking antibody HB22.7 has independent lymphomacidal properties and augments the efficacy of 90Y-DOTA-peptide-Lym-1 in lymphoma xenografts.

CD22 is a membrane glycophosphoprotein found on nearly all healthy B-lymphocytes and most B-cell lymphomas. Recent in vitro studies have identified several anti-CD22 monoclonal antibodies (mAbs) that block the interaction of CD22 with its ligand. One of these mAbs, HB22.

Cilengitide targeting of alpha(v)beta(3) integrin receptor synergizes with radioimmunotherapy to increase efficacy and apoptosis in breast cancer xenografts.

Although metastatic breast cancer is responsive to radioimmunotherapy (RIT), a systemic targeted radiation modality, complete and permanent remissions are not typical with single-modality treatment. Antiangiogenic agents, which target normal, proliferating endothelial cells, have the potential to provide relatively nontoxic continuous inhibition of tumor growth by blocking new blood vessel growth and may synergize with RIT to increase efficacy. This study was designed to determine whether, and how, the cyclic Arg-Gly-Asp peptide Cilengitide (EMD 121974), which targets the alpha(v)beta(3) integrin receptor expressed on neovasculature, could increase systemic RIT efficacy of therapy in a human breast cancer tumor model having mutant p53 and expressing bcl-2.

Combined modality radioimmunotherapy. Promise and peril.

Background: Single-agent radioimmunotherapy (RIT), although potentially useful for slowing solid tumor growth, has not been effective in curing aggressive tumors, such as breast cancer. These cancers typically have p53 mutations and are less susceptible to apoptosis, the apparent mechanism of cell death from low dose-rate radiation. Thus, synergistic or combined modality radioimmunotherapy (CMRIT) agents are needed to increase radiosensitivity for therapeutic enhancement without additive toxicity.

Combined modality radioimmunotherapy for human prostate cancer xenografts with taxanes and 90yttrium-DOTA-peptide-ChL6.

Background: Therapy for prostate cancer in the PC3 tumor-nude mouse model with 90yttrium-(90Y)-DOTA-peptide-ChL6 (5.55 MBq;150 microCi) has resulted in durable responses. To make radioimmunotherapy (RIT) more effective, the radiation-enhancing drugs Taxol (paclitaxel) and Taxotere (docetaxel) were tested for synergy with 90Y-DOTA-peptide-ChL6.