The Potential Role of Metalloproteinases in Neurogenesis in the Gerbil Hippocampus Following Global Forebrain Ischemia

BACKGROUND: Matrix metalloproteinases (MMPs) have recently been considered to be involved in the neurogenic response of adult neural stem/progenitor cells. However, there is a lack of information showing direct association between the activation of MMPs and the development of neuronal progenitor cells involving proliferation and/or further differentiation in vulnerable (Cornus Ammoni-CA1) and resistant (dentate gyrus-DG) to ischemic injury areas of the brain hippocampus. PRINCIPAL FINDINGS: We showed that dynamics of MMPs activation in the dentate gyrus correlated closely with the rate of proliferation and differentiation of progenitor cells into mature neurons. In contrast, in the damaged CA1 pyramidal cells layer, despite the fact that some proliferating cells exhibited antigen specific characteristic of newborn neuronal cells, these did not attain maturity. This coincides with the low, near control-level, activity of MMPs. The above results are supported by our in vitro study showing that MMP inhibitors interfered with both the proliferation and differentiation of the human neural stem cell line derived from umbilical cord blood (HUCB-NSCs) toward the neuronal lineage. CONCLUSION: Taken together, the spatial and temporal profiles of MMPs activity suggest that these proteinases could be an important component in neurogenesis-associated processes in post-ischemic brain hippocampus

Olfactory Stem Cells, a New Cellular Model for Studying Molecular Mechanisms Underlying Familial Dysautonomia

International audienceBackground: Familial dysautonomia (FD) is a hereditary neuropathy caused by mutations in the IKBKAP gene, the most common of which results in variable tissue-specific mRNA splicing with skipping of exon 20. Defective splicing is especially severe in nervous tissue, leading to incomplete development and progressive degeneration of sensory and autonomic neurons. The specificity of neuron loss in FD is poorly understood due to the lack of an appropriate model system. To better understand and modelize the molecular mechanisms of IKBKAP mRNA splicing, we collected human olfactory ecto-mesenchymal stem cells (hOE-MSC) from FD patients. hOE-MSCs have a pluripotent ability to differentiate into various cell lineages, including neurons and glial cells.Methodology/Principal Findings: We confirmed IKBKAP mRNA alternative splicing in FD hOE-MSCs and identified 2 novel spliced isoforms also present in control cells. We observed a significant lower expression of both IKBKAP transcript and IKAP/hELP1 protein in FD cells resulting from the degradation of the transcript isoform skipping exon 20. We localized IKAP/hELP1 in different cell compartments, including the nucleus, which supports multiple roles for that protein. We also investigated cellular pathways altered in FD, at the genome-wide level, and confirmed that cell migration and cytoskeleton reorganization were among the processes altered in FD. Indeed, FD hOE-MSCs exhibit impaired migration compared to control cells. Moreover, we showed that kinetin improved exon 20 inclusion and restores a normal level of IKAP/hELP1 in FD hOE-MSCs. Furthermore, we were able to modify the IKBKAP splicing ratio in FD hOE-MSCs, increasing or reducing the WT (exon 20 inclusion):MU (exon 20 skipping) ratio respectively, either by producing free-floating spheres, or by inducing cells into neural differentiation.Conclusions/Significance: hOE-MSCs isolated from FD patients represent a new approach for modeling FD to better understand genetic expression and possible therapeutic approaches. This model could also be applied to other neurological genetic diseases

Resuscitation of Newborn Piglets. Short-Term Influence of FiO2 on Matrix Metalloproteinases, Caspase-3 and BDNF

Perinatal hypoxia-ischemia is a major cause of mortality and cerebral morbidity, and using oxygen during newborn resuscitation may further harm the brain. The aim was to examine how supplementary oxygen used for newborn resuscitation would influence early brain tissue injury, cell death and repair processes and the regulation of genes related to apoptosis, neurodegeneration and neuroprotection.Anesthetized newborn piglets were subjected to global hypoxia and then randomly assigned to resuscitation with 21%, 40% or 100% O(2) for 30 min and followed for 9 h. An additional group received 100% O(2) for 30 min without preceding hypoxia. The left hemisphere was used for histopathology and immunohistochemistry and the right hemisphere was used for in situ zymography in the corpus striatum; gene expression and the activity of various relevant biofactors were measured in the frontal cortex. There was an increase in the net matrix metalloproteinase gelatinolytic activity in the corpus striatum from piglets resuscitated with 100% oxygen vs. 21%. Hematoxylin-eosin (HE) staining revealed no significant changes. Nine hours after oxygen-assisted resuscitation, caspase-3 expression and activity was increased by 30-40% in the 100% O(2) group (n = 9/10) vs. the 21% O(2) group (n = 10; p<0.04), whereas brain-derived neurotrophic factor (BDNF) activity was decreased by 65% p<0.03.The use of 100% oxygen for resuscitation resulted in increased potentially harmful proteolytic activities and attenuated BDNF activity when compared with 21%. Although there were no significant changes in short term cell loss, hyperoxia seems to cause an early imbalance between neuroprotective and neurotoxic mechanisms that might compromise the final pathological outcome

Tissue inhibitor of matrix metalloproteinases-1 loaded poly(lactic-co-glycolic acid) nanoparticles for delivery across the blood&ndash;brain barrier

Mayank Chaturvedi,1 Yves Molino,2 Bojja Sreedhar,3 Michel Khrestchatisky,4 Leszek Kaczmarek1 1Laboratory of Neurobiology, Nencki Institute, Warsaw, Poland; 2Vect-Horus, Marseille, France; 3Indian Institute of Chemical Technology, Hyderabad, India; 4Aix-Marseille Universit&eacute;, CNRS, NICN, UMR7259, Marseille, France Aim: The aim of this study was to develop poly(lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) for delivery of a protein &ndash; tissue inhibitor of matrix metalloproteinases 1 (TIMP-1) &ndash; across the blood&ndash;brain barrier (BBB) to inhibit deleterious matrix metalloproteinases (MMPs). Materials and methods: The NPs were formulated by multiple-emulsion solvent-evaporation, and for enhancing BBB penetration, they were coated with polysorbate 80 (Ps80). We compared Ps80-coated and uncoated NPs for their toxicity, binding, and BBB penetration on primary rat brain capillary endothelial cell cultures and the rat brain endothelial 4 cell line. These studies were followed by in vivo studies for brain delivery of these NPs. Results: Results showed that neither Ps80-coated nor uncoated NPs caused significant opening of the BBB, and essentially they were nontoxic. NPs without Ps80 coating had more binding to endothelial cells compared to Ps80-coated NPs. Penetration studies showed that TIMP-1 NPs + Ps80 had 11.21%&plusmn;1.35% penetration, whereas TIMP-1 alone and TIMP-1 NPs without Ps80 coating did not cross the endothelial monolayer. In vivo studies indicated BBB penetration of intravenously injected TIMP-1 NPs + Ps80. Conclusion: The study demonstrated that Ps80 coating of NPs does not cause significant toxic effects to endothelial cells and that it can be used to enhance the delivery of protein across endothelial cell barriers, both in vitro and in vivo. Keywords: PLGA nanoparticles, drug delivery, protein delivery, sustained release, brain delivery, BBB penetration, RBCEC cultur

Involvement of tissue inhibition of metalloproteinases-1 in learning and memory in mice.

Tissue inhibitor of metalloproteinases (TIMP-1) is one of the four-member family (TIMPs-1-4) of multifunctional proteins that inhibit matrix metalloproteinases (MMPs). Its expression in the hippocampus is neuronal-activity-dependent and dramatically induced by stimuli leading to long-term potentiation (LTP), suggesting that TIMP-1 is a candidate plasticity protein potentially involved in learning and memory processes. We tested this hypothesis in a hippocampus-dependent task using the new olfactory tubing maze, with mice carrying a null mutation for TIMP-1 (TIMP-1 KO) and mice overexpressing TIMP-1 (TIMP-1 (tg)). The TIMP-1 KO mice were significantly impaired in making correct odor-reward associations when compared with their respective wild type (WT) littermates, while TIMP-1 overexpressing mice performed better than their WT controls. Both genetically modified mice learned the paradigm and the timing of the task, like their respective WTs, and no olfactory dysfunctioning was observed. These data suggest that TIMP-1 is involved in learning and memory processes related to the hippocampus, and support the hypothesis that the MMP/TIMP ratio, and hence MMP activity, modulates neuronal plasticity in normal learning and memory processes, while altered proteolytic activity could impair cognitive functions

RAGE-TXNIP axis is required for S100B-promoted Schwann cell migration, fibronectin expression and cytokine secretion

During peripheral nerve injury, Schwann cells (SCs) adopt a migratory phenotype and remodel the extracellular matrix and provide a supportive activity for neuron regeneration. SCs synthesize neurotrophic factors and cytokines that are crucial for the repair of the injured nerve. The receptor for advanced glycation end products (RAGE) and its ligand S100B, which are secreted by SCs, are required for the repair of the injured peripheral nerve in vivo. However, the precise intracellular pathways involved have not been completely elucidated. Here, we show that RAGE-induced S100B secretion involves the recruitment of S100B in lipid rafts and caveolae. Moreover, we demonstrate for the first time that RAGE induces the expression of thioredoxin interacting protein (TXNIP) in SCs and the injured sciatic nerve in vivo. TXNIP is involved in the activation of p38 MAPK, CREB and NFkappaB in SCs. TXNIP silencing partially inhibits RAGE-induced SC migration and completely abolishes RAGE-induced fibronectin and IL-1betaexpression. Our results support a model in which TXNIP mediates in part RAGE-induced SC migration and is required for the expression of provisional ECM and pro-inflammatory IL-1beta. We provide new insight on the role of the SC RAGE–TXNIP axis in the repair of injured peripheral nerves