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BackgroundTIGIT, an inhibitory immune checkpoint, is a target of interest for immuno-oncology combination therapies. TIGIT is part of a complex molecular network containing four receptors (DNAM1, TIGIT, PVRIG and CD96) and two ligands (PVR and PVRL2). Here we describe Dual Signaling Protein 502 (DSP502), a novel, multi-functional IgG1-Fc-fusion protein targeting this molecular pathway in a unique way. DSP502, comprising the extracellular domains of TIGIT and PD1, is designed to simultaneously bind its two respective ligands, PVR and PD-L1, overexpressed on cancer and myeloid cells in the tumor microenvironment. DSP502 binds PVR preventing inhibitory signaling through TIGIT and CD96 and promoting DNAM1 costimulatory signaling on activated T- and NK-cells. DSP502's PD1 arm binds PD-L1 to unleash effector T-cells through checkpoint inhibition. In parallel, DSP502's IgG1-Fc delivers an immune-activating signal via Fc receptors. The net effect is enhanced anti-tumor immunity (figure 1).MethodsDSP502 heterodimer was successfully produced in a mammalian expression system. DSP502 was evaluated for binding to its cognate ligands on cells and in ELISA-based assays, with and without competing antibodies. NK and PBMC killing activity were evaluated against human K562 CML cells overexpressing PVR. Simultaneous binding of DSP502 to fluorescently-labeled tumor and NK-cells was evaluated by FACS. In vivo activity of DSP502 was evaluated in a humanized NSG A549 NSCLC xenograft mouse model.ResultsBoth DSP502 arms were shown to bind their cognate ligands in ELISA and on cell surface. DSP502 binding was dependent on the presence of both ligands on cells and was abolished by competing antibodies to the respective targets, demonstrating binding specificity and the 'AND-gate' phenomenon. Overexpression of PVR reduced the sensitivity of K562 cells to NK-cell mediated killing, while DSP502 treatment restored it as measured by target cell killing and granzyme-B secretion. Increased, dose-dependent, complexation of NK- and tumor cells was observed following DSP502 treatment and was abolished by both PVR and FcR antibodies. Treatment with DSP502 markedly inhibited tumor growth of A549-NSCLC xenograft in a humanized NSG mouse model, with all mice being tumor-free at the end of the experiment, compared to control PBMC-injected mice.ConclusionsHere we report the design and function of a novel immunotherapeutic fusion protein, DSP502, that offers multiple functionalities that can coordinately and synergistically drive anti-tumor immunity. Beyond targeting PVR and PDL1, DSP502 has the potential to additionally impact the TIGIT pathway through its effects on CD96 and DNAM1. DSP502 is currently in IND-enabling studies and CMC development.Ethics ApprovalThe study was conducted at the Authority of Biological and Preclinical Models, the Hebrew University of Jerusalem, Ein Kerem, Sharet Specific Pathogen-Free (SPF) Unit under the Hebrew university ethic committee board approval (number MD-19-15815-5).Abstract 790 Figure 1

2647 Background: DSP107 is a bi-functional, trimeric, fusion protein composed of sequences from the extracellular domain of SIRPα and 4-1BBL. The SIRPα arm targets CD47 overexpressed on tumor cells, blocking the “don’t eat me” checkpoint and triggering tumor cell phagocytosis. The trimeric 4-1BBL arm, once cross-presented and immobilized by SIRPα binding to CD47, interacts with 4-1BB expressed on activated immune cells, mainly T- and NK cells in the tumor microenvironment, and stimulates their proliferation and activation. Thereby, DSP107 triggers both an innate and an adaptive immune response. Here we describe data from the completed DSP107 monotherapy dose escalation portion of study NCT04440735. Methods: Adult patients with advanced solid tumors were treated with weekly intravenous DSP107 infusions (0.01 - 10 mg/kg) during 3-week treatment cycles. An accelerated dose escalation in single patient cohorts (dose levels 1-3) was followed by a standard 3 + 3 design. The primary objective was to determine safety, tolerability and pharmacokinetic (PK) parameters. Paired biopsies were obtained from 8 patients (screening, after cycle 2). Restaging imaging was performed every two months and evaluated by RECIST criteria. Results: In 23 patients, DSP107 demonstrated no treatment related hematologic or hepatic adverse events (AEs) and no dose limiting toxicities. Grade 1-2 treatment related AEs were observed in 70% of patients (16/23). The most frequent AEs included infusion related reaction (IRR; 26%), diarrhea (17%), fatigue (17%), nausea (13%) and constipation (9%). IRRs were managed during subsequent infusions by reducing the infusion rate and administering IV fluids. No significant systemic cytokine release was measured at any dose level using a 10-plex, pro-inflammatory panel. PK analysis revealed 100% CD47 receptor engagement on peripheral T and NK cells at doses of 3 mg/kg and above. DSP107 did not bind CD47 on red blood cells at any dose. Preliminary histologic assessment of paired biopsies by an independent, blinded pathologist demonstrated increased tumor necrosis compared to screening in 3 out of 4 patients associated with immune cell infiltration. Immuno-profiling of tumor by immunofluorescence is on-going. Stable disease as best response was observed in 11/22 patients with treatment duration up to 26 weeks. Conclusions: DSP107 is a novel, CD47 and 4-1BB targeting fusion protein with a differentiated safety, binding and pharmacodynamic profile compared to other CD47 and 4-1BB targeting agents. Clinical trial information: NCT04440735.

BackgroundTreatments that generate T cell-mediated immunity to a patient’s unique neoantigens are the current holy grail of cancer immunotherapy. In particular, treatments that do not require cumbersome and individualized ex vivo processing or manufacturing processes are especially sought after. Here we report that AGI-134, a glycolipid-like small molecule, can be used for coating tumor cells with the xenoantigen Galα1-3Galβ1-4GlcNAc (α-Gal) in situ leading to opsonization with pre-existing natural anti-α-Gal antibodies (in short anti-Gal), which triggers immune cascades resulting in T cell mediated anti-tumor immunity.MethodsVarious immunological effects of coating tumor cells with α-Gal via AGI-134 in vitro were measured by flow cytometry: (1) opsonization with anti-Gal and complement, (2) antibody-dependent cell-mediated cytotoxicity (ADCC) by NK cells, and (3) phagocytosis and antigen cross-presentation by antigen presenting cells (APCs). A viability kit was used to test AGI-134 mediated complement dependent cytotoxicity (CDC) in cancer cells. The anti-tumoral activity of AGI-134 alone or in combination with an anti-programmed death-1 (anti-PD-1) antibody was tested in melanoma models in anti-Gal expressing galactosyltransferase knockout (α1,3GT−/−) mice. CDC and phagocytosis data were analyzed by one-way ANOVA, ADCC results by paired t-test, distal tumor growth by Mantel–Cox test, C5a data by Mann–Whitney test, and single tumor regression by repeated measures analysis.ResultsIn vitro, α-Gal labelling of tumor cells via AGI-134 incorporation into the cell membrane leads to anti-Gal binding and complement activation. Through the effects of complement and ADCC, tumor cells are lysed and tumor antigen uptake by APCs increased. Antigen associated with lysed cells is cross-presented by CD8α+ dendritic cells leading to activation of antigen-specific CD8+ T cells. In B16-F10 or JB/RH melanoma models in α1,3GT−/−mice, intratumoral AGI-134 administration leads to primary tumor regression and has a robust abscopal effect, i.e., it protects from the development of distal, uninjected lesions. Combinations of AGI-134 and anti-PD-1 antibody shows a synergistic benefit in protection from secondary tumor growth.ConclusionsWe have identified AGI-134 as an immunotherapeutic drug candidate, which could be an excellent combination partner for anti-PD-1 therapy, by facilitating tumor antigen processing and increasing the repertoire of tumor-specific T cells prior to anti-PD-1 treatment.

The goal of this study was to compare the neuroprotective properties of the l -type Ca2+ channel blockers, nimodipine and nifedipine, using nerve growth factor (NGF)-differentiated PC12 neuronal cultures exposed to oxygen-glucose deprivation (OGD) and trophic withdrawal-induced cell death. Nimodipine (1–100 μM) conferred 65 ± 13% neuroprotection upon exposure to OGD and 35 ± 6% neuroprotection towards different trophic withdrawal-induced cell death measured by lactate dehydrogenase and caspase 3 activities. The time window of nimodipine conferred neuroprotection was detected during the first 5 h but not at longer OGD exposures. Nifedipine (1–100 μM), to a lower potency than nimodipine, conferred 30–55 ± 8% neuroprotection towards OGD in PC12 cells and 29 ± 5% in rat hypocampal slices, and 10 ± 3% neuroprotection at 100 μM towards trophic withdrawal-induced PC12 cell death. The ability to demonstrate that nimodipine conferred neuroprotection in a narrow therapeutic time-window indicates that the OGD PC12 model mimics the in vivo models and therefore suitable for neuroprotective drug discovery and development.

The tuftelin protein isoforms undergo post-translation modifications, and are ubiquitously expressed in various tissues in embryos, adults, and tumors. Developmental and pathological studies suggested an apparent correlation between oxygen deprivation and tuftelin expression. The aim of the study was therefore to investigate the effect of a pathological insult (hypoxia) and a physiological growth factor (NGF), which antagonistically regulate HIF1 expression, on tuftelin expression using the neuronal PC12 cell model. In the present study, we first demonstrated the expression of tuftelin in PC12 cells, providing an experimental system to investigate the pathophysiological role of tuftelin. Furthermore, we demonstrated the induction of tuftelin during hypoxia by oxygen deprivation and during chemical hypoxia by cobalt chloride. Down-regulation of HIF1α mRNA blocked hypoxia-induced HIF1α expression, and reduced by 89% hypoxia-induced tuftelin expression. In mice, intraperitoneal injection of cobalt chloride significantly induced tuftelin mRNA and protein expression in the brain. During NGF-mediated PC12 differentiation, tuftelin expression was significantly induced in correlation with neurite outgrowth. This induction was partially blocked by K252a, a selective antagonist of the NGF receptor TrkA, indicating the involvement of the TrkA-signaling pathways in tuftelin induction by NGF. Revealing the physiological role of tuftelin will clarify mechanisms related to the “hypoxic genome,” and NGF-induced neurotrophic and angiogenic effects. J. Cell. Physiol. 226: 165–172, 2010. © 2010 Wiley-Liss, Inc.

68 Background: AGI-134 is a fully synthetic alpha-Gal glycolipid for intratumoral (i.t.) treatment of solid tumors to induce a patient-specific anti-tumor immune response. AGI-134 recruits pre-existing anti-Gal antibodies to the injected lesion, leading to complement activation and enhanced tumor antigen processing. Using the B16.F10 murine melanoma model, we have previously demonstrated that AGI-134 evokes a robust abscopal anti-tumor effect, with treatment of a primary lesion protecting mice from the growth of distant lesions. In the current study, we investigated the response of injected tumors to AGI-134 administration. Methods: Tumors were induced by s.c. injection of B16.F10 or ovalbumin expressing B16 (B16.OVA) cells into the flank of α1,3galactosyltransferase knock out mice. After reaching a treatable size, the tumors were injected twice, 24 hrs apart, with PBS or 1-1.25 mg AGI-134, and tumor growth monitored for up to 32 days. In addition, to measure the activation of complement after treatment with AGI-134, tumors were processed 2 hours after treatment and the i.t. concentration of complement fragment C5a determined by ELISA. Results: Almost 50% of AGI-134-treated B16.F10 tumors fully regressed vs. 24% in the PBS controls. Moreover, AGI-134 treatment had a significant survival benefit, with 23% of AGI-134-treated mice dying or requiring euthanisia due to tumor mass by Day 27 post treatment vs. 43% in the PBS groups (p < 0.05, Mantel-Cox test). In the B16.OVA model, 67% of the AGI-134 treated tumors fully regressed vs. 0% in PBS-treated mice in two independent assays. Comparison of C5a levels in B16.F10 tumors 2 hrs after AGI-134 or PBS treatment demonstrated that AGI-134 induced significant complement activation within injected tumors. Conclusions: Having previously shown that AGI-134 induces an abscopal effect that protects mice from the development of secondary tumors, we now show that AGI-134 also induces regression of injected tumors: AGI-134-treatment induces the activation of complement within the tumor and leads to complete regression of the tumor in significantly more AGI-134-treated mice than PBS-treated. Clinical trials with AGI-134 are planned for 2018.

Neurodegenerative disorders and chronic disability due to stroke in the brain or spinal cord afflict a large sector of the population. To investigate the mechanism involved in ischemic stroke and to develop neuroprotective drugs/therapies, in vivo and in vitro, pharmacological models are needed. To investigate the cellular and molecular neuroprotective mechanisms of nerve growth factor (NGF), a member of the nervous system neurotrophin family of growth factors, under ischemia, we used an oxygen-glucose-deprivation (OGD) device and pheochromocytoma PC12 cells exposed to a paradigm of ischemic insult. Pretreatment of the cultures with 50 ng/mL of NGF, 18 h prior to OGD insult, conferred 30% of neuroprotection. Time-course experiments showed marked activation of the ERK, JNK, and p-38 MAPK isoforms during the OGD phase, but not during OGD reperfusion. Pretreatment of the cultures with 50 ng/mL of NGF, 18 h prior to OGD insult, resulted in 50% attenuation of OGD-induced activation of JNK 1, and 20% and 50% attenuation of OGD-induced activation of p-38 alpha and beta, respectively. The effect of NGF on gene expression in the PC12 ischemic model using Affymatrix Rat DNA-Microarray technology indicates that only 6% of the genes are differentially regulated (induced/suppressed) by OGD insult and/or NGF. These findings support the notion that pretreatment with NGF confers neuroprotection from OGD insult, a phenomenon coincidentally related to differential inhibition of MAPK stress kinase isoforms and differential gene expression. This ischemic model may be useful to investigate molecular mechanisms of OGD-induced neurotoxicity and NGF-induced neuroprotection, and to generate novel therapeutic concepts for stroke treatment.

PC12 clones are established neuronal models to investigate mechanisms involved in the cross-talk between the neurotrophins and drugs. Chronic treatment of PC12 cells with the glucocorticoid agonist drug, dexamethasone (Dex), elicited a 50% decrease in the selective binding of 125 I-NGF along with a reduction in the NGF receptor p75 NTR mRNA and protein levels, suggesting a transcriptional mechanism. This down regulation of p75 NTR was antagonized by the glu- cocorticoid type II receptor (GR-2), RU-38486 but not by the minerallocorticoid receptor, RU-28318, antagonists. This process was associated with increased autophosphorylation of the NGF receptor, TrkA. Chronic treatment of PC12 with Dex abolished the NGF-induced proliferation of the cells after 20 hours and inhibited by 45% the neurite elongation after 96 hours. RU-38486 blocked Dex-induced shift of PC12 cells from dopaminergic to noradrenergic phenotype. Dex- induced down regulation of p75 NTR receptor is mediated by GR-2 and is correlated with disruption of NGF induced prolif

The piperidine nitroxide tempamine (TMN) is a cell-permeable, stable radical having antioxidant, anticancer, and proapoptotic and/or pronecrotic activities, as was demonstrated by us in cell cultures. We also demonstrated synergism between TMN and doxorubicin in doxorubicin-sensitive and doxorubicin-resistant cell lines. Treatment of the C26 mouse colon carcinoma model in vivo also demonstrated synergism between TMN and doxorubicin in sterically stabilized liposomes (SSLs) containing TMN (SSL-TMN) and those containing doxorubicin. The above effects of TMN and SSL-TMN motivated us to develop and optimize the SSL-TMN formulation so that it will be able to reach the disease site with a sufficiently high TMN level and a release rate needed to achieve a therapeutic effect. Because TMN is an amphipathic weak base, it was remote loaded by an intraliposome high/extraliposome low transmembrane ammonium sulfate gradient. The kinetics and level of TMN loading were monitored by cyclic voltammetry (CV) and electron paramagnetic resonance (EPR); the latter also indicates TMN precipitation in the intraliposomal aqueous phase. The regeneration of the original CV and EPR signals by the ionophore nigericin indicates that TMN remained fully intact during loading and release. The cardinal role of the transmembrane ammonium ion gradient in the loading process was proven by the use of the selective ionophores nonactin (for NH4+) and nigericin (for H+). The anion of the ammonium salts affects loading stability and the rate of TMN release, both mediated through the TMN state of aggregation in the intraliposomal aqueous phase. The greater the TMN salt precipitation, the slower the TMN release rate. This was supported by measurement of osmolality, which is inversely related to TMN salt precipitate. Precipitation is in the order SO4(-2)>Cl-1>glucuronate-1. Liposome lipid composition, magnitude of the transmembrane ammonium ion gradient, and type of anion of the ammonium salt determine the amount of TMN loaded and its release rate.

Selegiline and rasagiline are selective and irreversible monoamine oxidase-B inhibitors that exert neuroprotective effects in various preclinical models. The aim of the present study was to examine the effect of selegiline and its major metabolite, L-methamphetamine in comparison to rasagiline and its major metabolite, 1-R-aminoindan on oxygen-glucose deprivation induced cell death in nerve growth factor (NGF)-differentiated pheochromocytoma (PC12) cells. Our results show that selegiline reduces oxygen-glucose deprivation induced cell death by 30%. When the cultures were treated with rasagiline at similar concentrations, cell death induced by oxygen-glucose deprivation was reduced by 45-55%. L-methamphetamine, a major selegiline metabolite, but not 1-R-aminoindan, the major rasagiline metabolite, enhanced oxygen-glucose deprivation-induced cell death by 70%. Under normoxic conditions, both metabolites lack neurotoxicity. Concomitant exposure of the cultures under oxygen-glucose deprivation, to a combination of either selegiline and L-methamphetamine or rasagiline and 1-R-aminoindan, indicated that L-methamphetamine, but not 1-R-aminoindan, blocked the neuroprotective effect of the parental drug. These results suggest there may be a neuroprotective advantage of rasagiline over selegiline.

Celiac disease (CD) is an autoimmune disorder in individuals that carry DQ2 or DQ8 MHC class II haplotypes, triggered by the ingestion of gluten. There is no current treatment other than a gluten-free diet (GFD). We have previously shown that the BL-7010 copolymer poly(hydroxyethyl methacrylate-co-styrene sulfonate) (P(HEMA-co-SS)) binds with higher efficiency to gliadin than to other proteins present in the small intestine, ameliorating gliadin-induced pathology in the HLA-HCD4/DQ8 model of gluten sensitivity. The aim of this study was to investigate the efficiency of two batches of BL-7010 to interact with gliadin, essential vitamins and digestive enzymes not previously tested, and to assess the ability of the copolymer to reduce gluten-associated pathology using the NOD-DQ8 mouse model, which exhibits more significant small intestinal damage when challenged with gluten than HCD4/DQ8 mice. In addition, the safety and systemic exposure of BL-7010 was evaluated in vivo (in rats) and in vitro (genetic toxicity studies). In vitro binding data showed that BL-7010 interacted with high affinity with gliadin and that BL-7010 had no interaction with the tested vitamins and digestive enzymes. BL-7010 was effective at preventing gluten-induced decreases in villus-to-crypt ratios, intraepithelial lymphocytosis and alterations in paracellular permeability and putative anion transporter-1 mRNA expression in the small intestine. In rats, BL-7010 was well-tolerated and safe following 14 days of daily repeated administration of 3000 mg/kg. BL-7010 did not exhibit any mutagenic effect in the genetic toxicity studies. Using complementary animal models and chronic gluten exposure the results demonstrate that administration of BL-7010 is effective and safe and that it is able to decrease pathology associated with gliadin sensitization warranting the progression to Phase I trials in humans. ISSN:1932-6203

Elevated serum leptin levels correlate with inflammation and predict changes in lean body mass in patients with CKD, and activation of the melanocortin system by leptin signaling mediates the pathophysiology of CKD-associated cachexia. We tested whether treatment with a pegylated leptin receptor antagonist (PLA) attenuates cachexia in mice with CKD. CKD and Sham mice received vehicle or PLA (2 or 7 mg/kg per day). At these doses, PLA did not influence serum leptin levels in mice. Treatment with 7 mg/kg per day PLA stimulated appetite and weight gain, improved lean mass and muscle function, reduced energy expenditure, and normalized the levels of hepatic TNF-α and IL-6 mRNA in mice with CKD. Furthermore, treatment with 7 mg/kg per day PLA attenuated the CKD-associated increase in the transcriptional and protein abundance of uncoupling proteins that mediates thermogenesis, and it normalized the molecular signatures of processes associated with muscle wasting in CKD, including proteolysis, myogenesis and muscle regeneration, and expression of proinflammatory muscle cytokines, such as IL-1α, -1β, and -6 and TNF-α. Our results suggest that leptin antagonism may represent a viable therapeutic strategy for cachexia in CKD.

Injectable biodegradable polymer poly(sebacic-co-ricinoleic acid), P(SA-RA) is currently under development for intratumoral (IT) delivery of drugs for treating solid tumors. This study presents formulation development, pharmacokinetic and efficacy studies of two anticancer drugs (cisplatin and paclitaxel) formulated with P(SA-RA) polymer. In pharmacokinetic study, systemic exposure and pharmacokinetic parameters of cisplatin/paclitaxel following single intravenous (IV) or subcutaneous (SC) doses of cisplatin/paclitaxel was compared with intramuscular (IM) or SC doses of cisplatin/paclitaxel formulated with P(SA-RA) polymer in male CD rat. Simultaneously, the tumor reduction effect and toxicity for these formulations were evaluated in human FaDu head and neck tumor xenograft subcutaneous nude mouse model. Pharmacokinetic data reflect the lower maximal concentrations and sustained release of polymer-cisplatin/paclitaxel formulations compared to standard cisplatin/paclitaxel administration. Regarding efficacy study, a single IT or near the tumor injection (NT) of polymer-paclitaxel or polymer-cisplatin formulation significantly reduced the tumor size, compared to the standard paclitaxel or cisplatin treatments. No death or toxicity and no effect on body weight as well as macroscopic and/or microscopic changes in or near the injected area were observed, proving biocompatibility and acceptability of polymer-formulations. In conclusion, the developed formulation demonstrated controlled release and significant efficacy in delivering these agents and exhibit potential for further clinical development.

The therapeutic effect of Glatiramer acetate, an immune modulating agent, was evaluated in the dy(2J)/dy(2J) mouse with merosin deficient congenital muscular dystrophy, which is a milder variant of the dy/dy mouse. The treated mice showed significant improvement in hind limb muscle strength measured by electronic grip strength meter and in motor performance quantified by video detection software. Glatiramer acetate treatment was associated with significantly increased expression of regeneration transcription factors MyoD and myogenin, and attenuation of the fibrosis markers vimentin and fibronectin. No effective treatment is currently available in congenital muscular dystrophy and Glatiramer acetate may present a new potential treatment for this disorder.

Human umbilical cord blood (HUCB) is a valuable source for cell therapy since it confers neuroprotection in stroke animal models. However, the responsible sub-populations remain to be established and the mechanisms involved are unknown. To explore HUCB neuroprotective properties in a PC12 cell-based ischemic neuronal model, we used an HUCB mononuclear-enriched population of collagen-adherent cells, which can be differentiated in vitro into a neuronal phenotype (HUCBNP). Upon co-culture with insulted-PC12 cells, HUCBNP conferred approximately 30% neuroprotection, as evaluated by decreased lactate dehydrogenase and caspase-3 activities. HUCBNP decreased by 95% the level of free radicals in the insulted-PC12 cells, in correlation with the appearance of antioxidants, as measured by changes in the oxidation-reduction potential of the medium using cyclic-voltammetry. An increased level of nerve growth factor (NGF), vascular endothelial growth factor and basic fibroblast growth factor in the co-culture medium was temporally correlated with a -medium neuroprotection effect, which was partially abolished by heat denaturation. HUCBNP-induced neuroprotection was correlated with changes in gene expression of these neurotrophic factors, while blocked by K252a, an antagonist of the TrkA/NGF receptor. These findings indicate that HUCBNP-induced neuroprotection involves antioxidant(s) and neurotrophic factors, which, by paracrine and/or autocrine interactions between the insulted-PC12 and the HUCBNP cells, conferred neuroprotection.

Nerve growth factor (NGF) differentiated pheochromocytoma PC12 cells exposed to 1-methyl-4-phenylpyridinium (MPP+) toxin were used as an in vitro pharmacological model of Parkinson's disease to examine the neuroprotective effects of 4-hydroxy-2,2,6,6-tetramethyl piperidine-n-oxyl (Tempol), a free radical scavenger and a superoxide dismutase-mimetic compound. MPP+-induced PC12 cell death was measured 72 h after exposure to 1.5 mM MPP+ by the release of lactate dehydrogenease, caspase-3 activation and stimulation of survival and stress mitogen-activated protein kinases. Exposure of PC12 cells to MPP+ activated ERK1 and ERK2 (forty-fold over control after 72 h), JNK1 and JNK2 (fourfold after 48 h) and p-38α (tenfold after 24 h). Pretreatment of PC12 cells with 500 μM Tempol, 1 h before induction of the MPP+ insult, reduced by 70% the release of LDH into the medium, inhibited caspase-3 activity by 30% and improved by 33% mitochondrial function, effects correlated with a 70% reduction in ERK1 and ERK2 phosphorylation activity. These findings support the neuroprotective effect of Tempol in the MPP+-induced PC12 cell death model and its use as a potential drug for treatment of Parkinson's disease.

We recently improved an in vitro ischemic model, using PC12 neuronal cultures exposed to oxygen-glucose deprivation (OGD) for 3 hr in a special device, followed by 18 hr of reoxygenation. The cell death induced in this ischemic model was evaluated by a series of markers: lactate dehydrogenase (LDH) release, caspase-3 activation, presence of cyclin D1, cytochrome c leakage from the mitochondria, BAX cellular redistribution, cleavage of poly (ADP-ribose) polymerase (PARP) to an 85-kDa apoptotic fragment, and DNA fragmentation. The OGD insult, in the absence of reoxygenation, caused a strong activation of the mitogen-activated protein kinase (MAPK) isoforms extracellular regulated kinase (ERK), c-Jun NH2-terminal kinase (JNK), and stress-activated protein kinase (SAPK), also known as p-38. The detection of apoptotic markers and activation of MAPKs during the ischemic insult strongly suggest that apoptosis plays an important role in the PC12 cell death. Homocarnosine, a neuroprotective histidine dipeptide, present in high concentrations in the brain, was found to provide neuroprotection, as expressed by a 40% reduction in LDH release and caspase-3 activity at 1 mM. Homocarnosine reduced OGD activation of ERK 1, ERK 2, JNK 1, and JNK 2 by 40%, 46%, 55%, and 30%, respectively. These results suggest that apoptosis is an important characteristic of OGD-induced neuronal death and that antioxidants, such as homocarnosine, may prevent OGD-induced neuronal death by inhibiting the apoptotic process and/or in relation to the differential attenuation of activity of MAPKs.

Inflammatory processes in the central nervous system (CNS) are considered neurotoxic, although recent studies suggest that they also can be beneficial and confer neuroprotection (neuroprotective autoimmunity). Cells from the immune system have been detected in CNS injury and found to produce and secrete a variety of neurotrophins such as NGF, BDNF, NT-3 and NT-4/5, and to express (similarly to neuronal cells), members of the tyrosine kinase (Trk) receptor family such as TrkA, TrkB and TrkC. Indeed, autocrine and paracrine interactions are observed at the site of CNS injury, resulting in a variety of homologic-heterologic modulations of immune and neuronal cell function. The end result of the inflammatory process, neurotoxicity and/or neuroprotection, is a function of the fine balance between the two cellular systems, i.e., of the complex signaling relationships between anti-inflammatory neuroprotective factors (neurotrophins and other chemical mediators) and proinflammatory neurotoxic factors (TNF, free radicals, certain cytokines, etc.). Autoimmune neuroprotection is a novel therapeutic approach aimed at shifting the balance between the immune and neuronal cells towards survival pathways in a variety of CNS injuries. This review focuses on data supporting this concept and its future therapeutical implications for optic nerve injury and multiple sclerosis.

Inflammatory processes in the central nervous system (CNS) are considered neurotoxic, although recent studies suggest that they also can be beneficial and confer neuroprotection (neuroprotective autoimmunity). Cells from the immune system have been detected in CNS injury and found to produce and secrete a variety of neurotrophins such as NGF, BDNF, NT-3 and NT-4/5, and to express (similarly to neuronal cells), members of the tyrosine kinase (Trk) receptor family such as TrkA, TrkB and TrkC. Indeed, autocrine and paracrine interactions are observed at the site of CNS injury, resulting in a variety of homologic-heterologic modulations of immune and neuronal cell function. The end result of the inflammatory process, neurotoxicity and/or neuroprotection, is a function of the fine balance between the two cellular systems, i.e., of the complex signaling relationships between anti-inflammatory neuroprotective factors (neurotrophins and other chemical mediators) and proinflammatory neurotoxic factors (TNF, free radicals, certain cytokines, etc.). Autoimmune neuroprotection is a novel therapeutic approach aimed at shifting the balance between the immune and neuronal cells towards survival pathways in a variety of CNS injuries. This review focuses on data supporting this concept and its future therapeutical implications for optic nerve injury and multiple sclerosis.

Parkinsonism (PD) is a neurodegenerative disorder of the brain resulting in dopamine deficiency caused by the progressive death of dopaminergic neurons. PD is characterized by a combination of rigidity, poverty of movement, tremor and postural instability. Selegiline is a selective and irreversible propargylamine type B monoamine oxidase (MAO-B) inhibitor. This drug, which inhibits dopamine metabolism, has been effectively used in the treatment of PD. However, its therapeutic effects are compromised by its many neurotoxic metabolites. To circumvent this obstacle, a novel MAO-B inhibitor, rasagiline, was developed. Paradoxically, the neuroprotective mechanism of propargylamines in different neuronal models appears to be independent of MAO-B inhibition. Recent investigations into the neuroprotective mechanism of propargylamines indicate that glyceraldehyde-3-phosphate dehydrogenase (GAPDH), MAO-B and/or other unknown proteins may represent pivotal proteins in the survival of the injured neurons. Delineation of the mechanism(s) involved in the neuroprotective effects exerted by MAO-B inhibitors may provide the key to preventive novel therapeutic modalities.

Neurotrophins such as nerve growth factor (NGF) are considered putative neuroprotective compounds in the central nervous system. To investigate the cellular and molecular neuroprotective mechanisms of NGF under ischemia, we used a unique oxygen and glucose deprivation (OGD) device. In this system we used pheochromocytoma PC12 cells to elucidate NGF neuroprotective effect. PC12 cells were exposed to OGD, followed by addition of glucose and oxygen (OGD reperfusion). Neuronal cell death induced in this model was measured by the release of lactate dehydrogenase (LDH), activation of caspase-3 and mitogen-activated protein kinases (MAPKs), measured with specific anti-phospho-antibodies. Pretreatment of the cultures with 50 ng/mL NGF, 18 h prior to OGD insult, conferred 30% neuroprotection. However, treatment of the cultures with NGF concomitantly with the OGD insult did not result in neuroprotection. Time-course experiments showed marked activation of extracellular signal-regulated protein kinase, c-Jun N-terminal kinase (JNK), and p38 MAPK isoforms during the OGD phase but not during OGD reperfusion. Pretreatment of the cultures with 50 ng/mL NGF, 18 h prior to OGD insult, resulted in 50% attenuation of OGD-induced activation of JNK1, and 20% and 50% attenuation of OGD-induced activation of p38alpha and beta, respectively. These findings support the notion that NGF confers neuroprotection from OGD insult, a phenomenon coincidentally related to differential inhibition of MAPK stress kinase isoforms, and provide the PC12 model as an in vitro OGD system to investigate molecular mechanisms of neurotoxicity and neuroprotection.

The development of neuroprotective drugs against ischemic insults is hampered by the lack of pharmacological in vitro models. We developed an ischemic model using PC12 cell cultures exposed to oxygen-glucose-deprivation (OGD) followed by reoxygenation (18 hr) under regular atmospheric oxygen level. The toxicity induced in this model, that is partially caused by generation of reactive oxygen species (ROS), was measured morphologically as well as by the release of lactate dehydrogenase (LDH) and the prostaglandin PGE(2) from the cells. Carnosine and homocarnosine, histidine dipeptides antioxidants, found in high concentration in the brain, have been suggested to provide neuroprotection. Using the OGD model we found that 5 mM carnosine and 1 mM homocarnosine provided maximal neuroprotection of about 50% against OGD insult. This neuroprotective effect was similar to that of a known antioxidant, 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl (tempol), and was not observed in a serum-deprivation toxicity model of PC12 cells, indicating that carnosine and homocarnosine may act as antioxidant-neuroprotective agents in the brain. Our ischemic model may provide a useful tool for investigating the mechanisms involved in the neuroprotection afforded by histidine dipeptides.

The purpose of this study was to characterize the effect of the K-252a family of protein kinase inhibitors with emphasis on staurosporine (ST), on stimulation of the inducible nitric oxide synthase activity in rat alveolar NR8383 macrophages. We found that ST, but not K-252a, K-252b, KT-5720, and KT-5823, selectively enhanced the basal or the lipopolysaccharide (LPS)-induced nitric oxide production. ST-induced NO production was blocked by L-NAME, K-252a, and phosphatase inhibitors and could not be mimicked by other protein kinase C (PKC) inhibitors such as calphostine. An additive effect between ST and PMA on NO production was observed. LPS and PMA but not ST induced PKCβ translocation from the cytosol to the membrane fraction. ST may induce and affect the state of phosphorylation of iNOS via PKC-independent mechanisms. ST provides an important pharmacological tool to investigate PKC-independent signal transduction pathways which regulate iNOS, induction, and activity in rat NR8383 macrophages.

Background Serum paraoxonase (PON1) is a high density lipoprotein (HDL)-associated enzyme involved in organophosphate (OP) degradation and prevention of atherosclerosis. PON1 comprises a potential candidate for in vivo therapeutics, as an anti-atherogenic agent, and for detoxification of pesticides and nerve agents. Because human PON1 exhibits limited stability, engineered, recombinant PON1 (rePON1) variants that were designed for higher reactivity, solubility, stability, and bacterial expression, are candidates for treatment. This work addresses the feasibility of in vivo administration of rePON1, and its HDL complex, as a potentially therapeutic agent dubbed BL-3050. Methods For stability studies we applied different challenges related to the in vivo disfunctionalization of HDL and PON1 and tested for inactivation of PON1's activity. We applied acute, repetitive administrations of BL-3050 in mice to assess its toxicity and adverse immune responses. The in vivo efficacy of recombinant PON1 and BL-3050 were tested with an animal model of chlorpyrifos-oxon poisoning. Results Inactivation studies show significantly improved in vitro lifespan of the engineered rePON1 relative to human PON1. Significant sequence changes relative to human PON1 might hamper the in vivo applicability of BL-3050 due to adverse immune responses. However, we observed no toxic effects in mice subjected to repetitive administration of BL-3050, suggesting that BL-3050 could be safely used. To further evaluate the activity of BL-3050 in vivo, we applied an animal model that mimics human organophosphate poisoning. In these studies, a significant advantages of rePON1 and BL-3050 (>87.5% survival versus Conclusion In vitro and in vivo data described here demonstrate the potential advantages of rePON1 and BL-3050 for treatment of OP toxicity and chronic cardiovascular diseases like atherosclerosis. The in vivo data also suggest that rePON1 and BL-3050 are stable and safe, and could be used for acute, and possibly repeated treatments, with no adverse effects.