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Biomedical subjects

Marcel Leist

Publications and source records attributed to Marcel Leist.

27 records · Page 2Linked to original sources
PubMed2004

Improvement of embryonic dopaminergic neurone survival in culture and after grafting into the striatum of hemiparkinsonian rats by CEP-1347.

Transplantation of embryonic nigral tissue ameliorates functional deficiencies in Parkinson's disease (PD). A main constraint of neural grafting is the poor survival of dopaminergic neurones grafted into patients. Studies in rats indicated that many grafted neurones die by apoptosis. CEP-1347 is a mixed-lineage-kinase (MLK) inhibitor with neuroprotective action in several in vitro and in vivo models of neuronal apoptosis. We studied the effect of CEP-1347 on the survival of embryonic rat dopaminergic neurones in culture, and after transplantation in hemiparkinsonian rats. CEP-1347 and the alternative MLK inhibitor CEP-11004 significantly increased the survival of dopaminergic neurones in primary cultures from rat ventral mesencephalon and in Mn2+-exposed PC12 cells, a surrogate model of dopaminergic lethal stress. Moreover, combined treatment of the grafting cell suspension and the host animal with CEP-1347 significantly improved the long-term survival of rat dopaminergic neurones transplanted into the striatum of hemiparkinsonian rats. Also, the protective effect of CEP-1347 resulted in an increase in total graft size and in enhanced fibre outgrowth. Thus, treatment with CEP-1347 improved dopaminergic cell survival under severe stress and might be useful to improve the positive outcome of transplantation therapy in PD and reduce the amount of human tissue required.

Animals↗
PubMed2004

Defined inflammatory states in astrocyte cultures: correlation with susceptibility towards CD95-driven apoptosis.

A complete cytokine mix (CCM) or its individual components tumour necrosis factor-alpha (TNF-alpha), interleukin-1beta (IL-1beta) and interferon-gamma (IFN-gamma) were used to switch resting murine astrocytes to reactive states. The transformation process was characterized by differential up-regulation of interleukin-6 (IL-6), cyclooxygenase-2 (COX-2) and inducible nitric oxide synthetase (iNOS) mRNA and protein and a subsequent release of prostaglandin E2, nitric oxide (NO) and IL-6. Both CD95L and anti-CD95 antibodies triggered caspase activation followed by apoptotic death in fully pro-inflammatory astrocytes, whereas resting cells were totally resistant. Two other death-inducing ligands, TNF and TNF-related apoptosis-inducing ligand (TRAIL) did not induce apoptosis in reactive astrocytes. The switch in astrocyte sensitivity was accompanied by up-regulation of caspase-8 and CD95 as well as the capacity to recruit Fas-associated death domain (FADD) to the activated death receptor complex. Neither CD95-mediated death, nor other inflammatory parameters were affected by inhibition of iNOS or COX, respectively. Accordingly, IFN-gamma was absolutely essential for up-regulation of iNOS, but not for the switch in apoptosis sensitivity. In contrast, p38 kinase activity was identified as an important controller of both the inflammatory reaction and apoptosis both in astrocytes stimulated with CCM and in glia exposed to TNF and IL-1 only.

Animals↗
PubMed2004

The nonerythropoietic asialoerythropoietin protects against neonatal hypoxia-ischemia as potently as erythropoietin.

Recently, erythropoietin (EPO) and the nonerythropoietic derivative asialoEPO have been linked to tissue protection in the nervous system. In this study, we tested their effects in a model of neonatal hypoxia-ischemia (HI) in 7-day-old rats (unilateral carotid ligation and exposure to 7.7% O(2) for 50 min). EPO (10 U/g body weight = 80 ng/g; n = 24), asialoEPO (80 ng/g; n = 23) or vehicle (phosphate-buffered saline with 0.1% human serum albumin; n = 24) was injected intraperitoneally 4 h before HI. Both drugs were protective, as judged by measuring the infarct volumes, neuropathological score and gross morphological score. The infarct volumes were significantly reduced by both EPO (52%) and asialoEPO (55%) treatment, even though the plasma levels of asialoEPO had dropped below the detection limit (1 pm) at the onset of HI, while those of EPO were in the nanomolar range. Thus, a brief trigger by asialoEPO before the insult appears to be sufficient for protection. Proteomics analysis after asialoEPO treatment alone (no HI) revealed at least one differentially up-regulated protein, synaptosome-associated protein of 25 kDa (SNAP-25). Activation (phosphorylation) of ERK was significantly reduced in asialoEPO-treated animals after HI. EPO and the nonerythropoietic asialoEPO both provided significant and equal neuroprotection when administered 4 h prior to HI in 7-day-old rats. The protection might be related to reduced ERK activation and up-regulation of SNAP-25.

Animals↗
PubMed2003

Asialoerythropoietin is a nonerythropoietic cytokine with broad neuroprotective activity in vivo.

Erythropoietin (EPO) is a tissue-protective cytokine preventing vascular spasm, apoptosis, and inflammatory responses. Although best known for its role in hematopoietic lineages, EPO also affects other tissues, including those of the nervous system. Enthusiasm for recombinant human erythropoietin (rhEPO) as a potential neuroprotective therapeutic must be tempered, however, by the knowledge it also enlarges circulating red cell mass and increases platelet aggregability. Here we examined whether erythropoietic and tissue-protective activities of rhEPO might be dissociated by a variation of the molecule. We demonstrate that asialoerythropoietin (asialoEPO), generated by total enzymatic desialylation of rhEPO, possesses a very short plasma half-life and is fully neuroprotective. In marked contrast with rhEPO, this molecule at doses and frequencies at which rhEPO exhibited erythropoiesis, did not increase the hematocrit of mice or rats. AsialoEPO appeared promptly within the cerebrospinal fluid after i.v. administration; intravenously administered radioiodine-labeled asialoEPO bound to neurons within the hippocampus and cortex in a pattern corresponding to the distribution of the EPO receptor. Most importantly, asialoEPO exhibits a broad spectrum of neuroprotective activities, as demonstrated in models of cerebral ischemia, spinal cord compression, and sciatic nerve crush. These data suggest that nonerythropoietic variants of rhEPO can cross the blood-brain barrier and provide neuroprotection.

Animals↗
PubMed2003

Overexpression of heat shock protein 70 in R6/2 Huntington's disease mice has only modest effects on disease progression.

Huntington's disease (HD) is a neurodegenerative disorder caused by expansion of a polyglutamine tract in a protein called huntingtin. The inducible form of heat shock protein 70 (Hsp70) has been shown to reduce polyglutamine-induced toxicity. To investigate if overexpression of Hsp70 can affect disease progression in a mouse model of HD, we crossed R6/2 mice, expressing exon 1 of the HD gene with an expanded CAG repeat, with mice overexpressing Hsp70 (both types of transgenic mice were of the CBAxC57BL/6 strain). The resulting R6/2-Hsp70 transgenics exhibited 5- to 15-fold increases in Hsp70 expression in neocortical, hippocampal and basal ganglia regions. This correlated with a delayed loss of body weight compared to R6/2 mice. However, the number or size of nuclear inclusions, the loss of brain weight, reduction of striatal volume, reduction in size of striatal projection neurons, downregulation of DARPP-32, development of paw clasping phenotype and early death of the mice were not affected by Hsp70 overexpression. Interestingly, the polyglutamine protein affected the potential rescuing agent, because in older R6/2-Hsp70 mice a large proportion of the Hsp70 protein was sequestrated in nuclear inclusions.

Animals↗
PubMed2002

Eradication of glioblastoma, and breast and colon carcinoma xenografts by Hsp70 depletion.

Heat shock protein 70 (Hsp70) is an antiapoptotic chaperone protein highly expressed in human tumors. Here we demonstrate that locoregional application of adenovirus expressing antisense Hsp70 cDNA (Ad.asHsp70) eradicates orthotopic xenografts of glioblastoma and breast carcinoma, as well as s.c. xenografts of colon carcinoma in immunodeficient mice. Ad.asHsp70-treated tumors showed massive apoptosis-like cell death and recruitment of macrophages. Human monocyte-derived macrophages effectively removed the corpses of Ad.asHsp70-treated tumor cells in vitro. Interestingly, both tumor cell death and phagocytosis were caspase-independent. Thus, Hsp70 appears as a promising target for the treatment of cancers resistant to classic caspase-mediated apoptosis.

Adenoviridae↗
PubMed2002

Mitogen-activated protein kinase-activated protein kinase 2-deficient mice show increased susceptibility to Listeria monocytogenes infection.

Mitogen-activated protein kinase-activated protein kinase 2 (MK2) is one of several kinases activated through direct phosphorylation by p38 mitogen-activated protein kinase. MK2 regulates LPS-induced TNF mRNA translation, and targeted mutation of the MK2 gene renders mice more resistant to D-galactosamine plus LPS-induced liver damage. In the present study, we investigated the role of MK2 in immune defense against Listeria monocytogenes infection. MK2-deficient mice displayed diminished resistance to L. monocytogenes due to impaired control of bacterial growth. The increase in bacterial load in MK2(-/-) mice was associated with normal levels of IL-1 beta, IL-6, and IFN-gamma, whereas TNF production was strongly attenuated. In line, MK2-deficient bone marrow-derived macrophages showed impaired release of TNF, but not of IL-1 beta, in response to various bacterial stimuli in addition to decreased phagocytosis of fluorescence-labeled bacteria. Furthermore, spleen cells from MK2(-/-) mice displayed diminished IFN-gamma synthesis after stimulation with L. monocytogenes. In contrast, MK2 deficiency had no effect on macrophage generation of NO or on oxidative burst activity in response to L. moocytogenes. These results indicate an essential role of MK2 in host defense against intracellular bacteria probably via regulation of TNF and IFN-gamma production required for activation of antibacterial effector mechanisms.

Animals↗
PubMedDate not supplied

Nonhematopoietic erythropoietin derivatives prevent motoneuron degeneration in vitro and in vivo.

Chronic treatment with asialo erythropoietin (ASIALO-EPO) or carbamylated erythropoietin (CEPO) improved motor behavior and reduced motoneuron loss and astrocyte and microglia activation in the cervical spinal cord of wobbler mice, an animal model of amyotrophic lateral sclerosis, but had no effect on hematocrit values. ASIALO-EPO and CEPO, like the parent compound EPO, protected primary motoneuron cultures from kainate-induced death in vitro. Both EPO receptor and the common CD131 beta chain were expressed in cultured motoneurons and in the anterior horn of wobbler mice spinal cord. Our results strongly support a role for the common beta chain CD131 in the protective effect of EPO derivatives on motoneuron degeneration. Thus CEPO, which does not bind to the classical homodimeric EPO receptor and is devoid of hematopoietic activity, could be effective in chronic treatment aimed at reducing motoneuron degeneration.

Animals↗