Rafael Fernandez-Montesinos

Chaperone proteostasis in Parkinson's disease: stabilization of the Hsp70/α-synuclein complex by Hip

The ATP‐dependent protein chaperone heat‐shock protein 70 (Hsp70) displays broad anti‐aggregation functions and has a critical function in preventing protein misfolding pathologies. According to in vitro and in vivo models of Parkinsons disease (PD), loss of Hsp70 activity is associated with neurodegeneration and the formation of amyloid deposits of α‐synuclein (αSyn), which constitute the intraneuronal inclusions in PD patients known as Lewy bodies. Here, we show that Hsp70 depletion can be a direct result of the presence of aggregation‐prone polypeptides. We show a nucleotide‐dependent interaction between Hsp70 and αSyn, which leads to the aggregation of Hsp70, in the presence of ADP along with αSyn. Such a co‐aggregation phenomenon can be prevented in vitro by the co‐chaperone Hip (ST13), and the hypothesis that it might do so also in vivo is supported by studies of a Caenorhabditis elegans model of αSyn aggregation. Our findings indicate that a decreased expression of Hip could facilitate depletion of Hsp70 by amyloidogenic polypeptides, impairing chaperone proteostasis and stimulating neurodegeneration.

Glial Innate Immunity Generated by Non-Aggregated Alpha-Synuclein in Mouse: Differences between Wild-type and Parkinson's Disease-Linked Mutants

Background Parkinsons disease (PD) is a progressive neurodegenerative disorder characterized pathologically by the presence in the brain of intracellular protein inclusions highly enriched in aggregated alpha-synuclein (α-Syn). Although it has been established that progression of the disease is accompanied by sustained activation of microglia, the underlying molecules and factors involved in these immune-triggered mechanisms remain largely unexplored. Lately, accumulating evidence has shown the presence of extracellular α-Syn both in its aggregated and monomeric forms in cerebrospinal fluid and blood plasma. However, the effect of extracellular α-Syn on cellular activation and immune mediators, as well as the impact of familial PD-linked α-Syn mutants on this stimulation, are still largely unknown. Methods and Findings In this work, we have compared the activation profiles of non-aggregated, extracellular wild-type and PD-linked mutant α-Syn variants on primary glial and microglial cell cultures. After stimulation of cells with α-Syn, we measured the release of Th1- and Th2- type cytokines as well as IP-10/CXCL10, RANTES/CCL5, MCP-1/CCL2 and MIP-1α/CCL3 chemokines. Contrary to what had been observed using cell lines or for the case of aggregated α-Syn, we found strong differences in the immune response generated by wild-type α-Syn and the familial PD mutants (A30P, E46K and A53T). Conclusions These findings might contribute to explain the differences in the onset and progression of this highly debilitating disease, which could be of value in the development of rational approaches towards effective control of immune responses that are associated with PD.

Alzheimer's disease beyond the genomic era: nuclear magnetic resonance (NMR) spectroscopy-based metabolomics

•  Introduction •  Rationale for metabolomics in Alzheimers disease •  Metabolomics of Alzheimers disease ‐  Studies in animal models of AD ‐  Human studies •  Methodology: NMR metabolomics at work •  Conclusions

Tiopronin monolayer-protected silver nanoparticles modulate IL-6 secretion mediated by Toll-like receptor ligands

AIMS Capped silver nanoparticles that can be coupled to a variety of molecules and biomolecules are of great interest owing to their potential applications in biomedicine. However, there are no data about their toxicity or functional effects on a key innate immune response, such as IL-6 secretion, after the engagement of the main group of pathogen-associated molecular patterns receptors, that is, the Toll-like receptors (TLRs). MATERIALS & METHODS N-(2-mercaptopropionyl)glycine (tiopronin)-capped silver (Ag@tiopronin) nanoparticles of a narrow sized distribution ( approximately 5 nm) were synthesized and characterized by transmission electron microscopy, Fourier transform infrared spectroscopy, Raman, (1)H-NMR and total correlation spectroscopy. Cytotoxicity was determined by lactate deshidrogenase and 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium assays in Raw 264.7 macrophages. IL-6 was measured by ELISA. RESULTS & DISCUSSION Ag@tiopronin nanoparticles have a narrow size distribution ( approximately 5 nm), high solubility and stability in aqueous environment with no cytotoxicity in terms of mitochondrial function or plasma-membrane integrity at concentrations as high as 200 microg/10(6) cells. Ag@tiopronin nanoparticles were not proinflammatory agents, but remarkably they specifically impaired the IL-6 secretion mediated by TLR2, TLR2/6, TLR3 or TLR9 stimulation in co-treatment experiments. However, in pretreatment experiments, nanoparticles enhanced the susceptibility of macrophages to inflammatory stimulation mediated by TLR2/1 and TLR2/6 specific ligands while severely impairing the IL-6 secretion activated by the TLR3 or TLR9 ligands. CONCLUSIONS Contrary to what is found for bare silver nanoparticles, Ag@tiopronin nanoparticles are noncytotoxic to macrophages. Ag@tiopronin nanoparticles showed differential effects on TLR signaling of a high degree of specificity, without proinflammatory effects by themselves. These effects have to be borne in mind when using bioconjugates of Ag@tiopronin nanoparticles for future medical applications.

Preconditioning of Microglia by α-Synuclein Strongly Affects the Response Induced by Toll-like Receptor (TLR) Stimulation

In recent years, it has become accepted that α-synuclein (αSyn) has a key role in the microglia-mediated neuroinflammation, which accompanies the development of Parkinson’s disease and other related disorders, such as Dementia with Lewy Bodies and Alzheimer’s disease. Nevertheless, the cellular and molecular mechanisms underlying its pathological actions, especially in the sporadic forms of the diseases, are not completely understood. Intriguingly, several epidemiological and animal model studies have revealed a link between certain microbial infections and the onset or progression of sporadic forms of these neurodegenerative disorders. In this work, we have characterized the effect of toll-like receptor (TLR) stimulation on primary murine microglial cultures and analysed the impact of priming cells with extracellular wild-type (Wt) αSyn on the subsequent TLR stimulation of cells with a set of TLR ligands. By assaying key interleukins and chemokines we report that specific stimuli, in particular Pam3Csk4 (Pam3) and single-stranded RNA40 (ssRNA), can differentially affect the TLR2/1- and TLR7-mediated responses of microglia when pre-conditioned with αSyn by augmenting IL-6, MCP-1/CCL2 or IP-10/CXCL10 secretion levels. Furthermore, we report a skewing of αSyn-primed microglia stimulated with ssRNA (TLR7) or Pam3 (TLR2/1) towards intermediate but at the same time differential, M1/M2 phenotypes. Finally, we show that the levels and intracellular location of activated caspase-3 protein change significantly in αSyn-primed microglia after stimulation with these particular TLR agonists. Overall, we report a remarkable impact of non-aggregated αSyn pre-sensitization of microglia on TLR-mediated immunity, a phenomenon that could contribute to triggering the onset of sporadic α-synuclein-related neuropathologies.

Protective role for plasmid DNA-mediated VIP gene transfer in non-obese diabetic mice.

Abstract:  Studies focused on the development of diabetes in NOD mice—a model for human type 1 diabetes—have revealed that an autoimmune inflammatory process is produced by the effect of Th1 cells and their secreted cytokines. DNA vaccination has been shown to be an effective method for modulating immunity in viral infections and experimental autoimmune diseases, including diabetes. VIPs immunomodulatory properties are partly mediated by skewing the pattern of cytokines from a proinflammatory response to an anti‐inflammatory response. Using gene delivery to express VIP, we interfered in the immune process leading to diabetes in prone, cyclophosphamide‐treated NOD mice. Our results extend the role of VIP in the control of immunoregulatory networks and open new perspectives for immunointervention through VIP‐based gene therapy.

NAP, a Peptide Derived from the Activity‐Dependent Neuroprotective Protein, Modulates Macrophage Function

Abstract:  NAP is an eight‐amino acid neuroprotective peptide NAPVSIPQ; it is the smallest active element derived from the recently cloned activity‐dependent neuroprotective protein (ADNP) . NAP readily enters the brain from the blood. It will be important to learn whether NAP, in addition to its neuroprotective activity, also might influence immune‐mediated inflammation. Here, we report that: (a) macrophages express ADNP; (b) expression of ADNP in macrophages responds to VIP; and (c) NAP downregulates the key inflammatory cytokines tumor necrosis factor (TNF‐α), interleukin‐16 (IL‐16), and IL‐12 in macrophages. These findings indicate that ADNP/NAP can play an important role in immune regulation as well as in neuroprotection, which may be mutually related processes.

Chemical synthesis and characterization of silver-protected vasoactive intestinal peptide nanoparticles

UNLABELLED We characterized a method to conjugate functional silver nanoparticles with vasoactive intestinal peptide (VIP), which could be used as a working model for further tailor-made applications based on VIP surface functionality. Despite sustained interest in the therapeutic applications of VIP, and the fact that its drugability could be largely improved by the attachament to functionalized metal nanoparticles, no methods have been described so far to obtain them. MATERIALS & METHODS VIP was conjugated to tiopronin-capped silver nanoparticles of a narrow size distribution, by means of proper linkers, to obtain VIP functionalized silver nanoparticles with two different VIP orientations (Ag-tiopronin-PEG-succinic-[His]VIP and Ag-tiopronin-PEG-VIP[His]). VIP intermediate nanoparticles were characterized by transmission-electron microscopy and Fourier transform infrared spectroscopy. VIP functionalized silver nanoparticles cytotoxicity was determined by lactate dehydrogenase release from mixed glial cultures prepared from cerebral cortices of 1-3 days-old C57/Bl mice. Cells were used for lipopolysaccharide stimulation at day 18-22 of culture. RESULTS Two different types of VIP-functionalized silver nanoparticles were obtained; both expose the C-terminal part of the neuropeptide, but in the first type VIP is attached to silver nanoparticle through its free amine terminus (Ag-tiopronin-PEG-succinic-[His]VIP), while in the second type, VIP N-terminus remains free (Ag-tiopronin-PEG-VIP[His]). VIP-functionalized silver nanoparticles did not compromise cellular viability and inhibited microglia-induced stimulation under inflammatory conditions. CONCLUSION The chemical synthesis procedure developed to obtain VIP-functionalized silver nanoparticles rendered functional products, in terms of biological activity. The two alternative orientations designed, reduced the constraints for chemical synthesis that depends on the nanosurface to be functionalized. Our study provides, for the first time, a proof of principle to enhance the therapeutic potential of VIP with the valuable properties of metal nanoparticles for imaging, targeting and drug delivery.

Toll-like receptor stimulation differentially regulates vasoactive intestinal peptide type 2 receptor in macrophages

Vasoactive intestinal peptide (VIP) was originally isolated as a vasodilator intestinal peptide, then as a neuropeptide. In the immune system, VIP is described as an endogenous macrophage‐deactivating factor. VIP exerts its immunological actions in a paracrine and/or autocrine manner, through specific receptors. However, very little is known about the molecular regulation of VIP type 2 receptor (VPAC2) in the immune system. We now report that different toll‐like receptor (TLR) ligands selectively regulate the VPAC2 receptor gene and show a gene repression system controlled by key protein kinase signalling cascades in macrophages. VPAC2 gene expression is regulated by gram‐positive (TLR2 ligands) and gram‐negative bacteria wall constituents (TLR4 ligands). Moreover, VPAC2 is tightly regulated: TLR2‐ or TLR2/6‐ but not TLR2/1‐mediated mechanisms are responsible for the induction of VPAC2. TLR stimulation by viral or bacterial nucleic acids did not modify the VPAC2 mRNA levels. Remarkably, imiquimod – a synthetic TLR7 ligand – led to a potent up‐regulation of VPAC2 gene expression. TLR5 stimulation by flagellin present in gram‐positive and gram‐negative bacteria did not affect VPAC2 mRNA. The p38 mitogen‐activated protein kinase (MAPK) activity accounted for the TLR4‐mediated induction of VPAC2 gene expression. Surprisingly, our data strongly suggest for the first time a tightly repressed control of VPAC2 mRNA induction by elements downstream of MAPK kinase 1/2, PI3K/Akt, and particularly Jun‐NH2‐terminal kinase signalling pathways.

Silver Nanoparticles Interactions with the Immune System: Implications for Health and Disease

Our immune system constantly interacts with our internal environment, protects us from our external environment and provides the inherent knowledge to sense the difference between friend and foe with important implications in human health and disease (Pozo, 2008). For these reasons, it is important to identify functional alteration of key immune responses as the number of silver nano-enabled products grows while the current data strongly suggest that other related nanomaterials, such as polymer nanoparticles, fullerenes, dendrimers and gold nanoparticles, interact with the immune system.