Amyloid beta and diabetic pathology cooperatively stimulate cytokine expression in an Alzheimer's mouse model

Background Diabetes is a risk factor for developing Alzheimer's disease (AD); however, the mechanism by which diabetes can promote AD pathology remains unknown. Diabetes results in diverse molecular changes in the brain, including dysregulation of glucose metabolism and loss of cerebrovascular homeostasis. Although these changes have been associated with increased A beta pathology and increased expression of glial activation markers in APPswe/PS1dE9 (APP/PS1) mice, there has been limited characterization, to date, of the neuroinflammatory changes associated with diabetic conditions. Methods To more fully elucidate neuroinflammatory changes associated with diabetes that may drive AD pathology, we combined the APP/PS1 mouse model with either high-fat diet (HFD, a model of pre-diabetes), the genetic db/db model of type 2 diabetes, or the streptozotocin (STZ) model of type 1 diabetes. We then used a multiplexed immunoassay to quantify cortical changes in cytokine proteins. Results Our analysis revealed that pathology associated with either db/db, HFD, or STZ models yielded upregulation of a broad profile of cytokines, including chemokines (e.g., MIP-1 alpha, MIP-1 beta, and MCP-1) and pro-inflammatory cytokines, including IL-1 alpha, IFN-gamma, and IL-3. Moreover, multivariate partial least squares regression analysis showed that combined diabetic-APP/PS1 models yielded cooperatively enhanced expression of the cytokine profile associated with each diabetic model alone. Finally, in APP/PS1xdb/db mice, we found that circulating levels of A beta 1-40, A beta 1-42, glucose, and insulin all correlated with cytokine expression in the brain, suggesting a strong relationship between peripheral changes and brain pathology. Conclusions Altogether, our multiplexed analysis of cytokines shows that Alzheimer's and diabetic pathologies cooperate to enhance profiles of cytokines reported to be involved in both diseases. Moreover, since many of the identified cytokines promote neuronal injury, A beta and tau pathology, and breakdown of the blood-brain barrier, our data suggest that neuroinflammation may mediate the effects of diabetes on AD pathogenesis. Therefore, strategies targeting neuroinflammatory signaling, as well as metabolic control, may provide a promising strategy for intervening in the development of diabetes-associated AD

Ctla-4, una molécula que inhibe la activación de los linfocitos T

Resumen CTLA-4 (Antígeno-4 asociado al Linfocito T Citotóxico) es una molécula expresada en la superficie de la mayoría de los linfocitos T activados. Su función es regular la homeostasis y la tolerancia peri- férica inmunológica inhibiendo la activación de los linfocitos T. Dos mecanismos han sido postulados para mediar la inhibición por CTLA-4 de la respuesta de los linfocitos T: Señalización negativa y antagonismo competitivo de la vía de coestimulación mediada por CD28/B7. Las diferentes moléculas que participan en la activación e inactivación de los linfocitos T han sido analizadas con el objetivo de diseñar estrategias terapéuticas de tolerancia inmunológica. Los progresos han estado basados en los mecanismos de activación linfocitaria, la coestimulación o la señalización por citocinas, pero ha sido difícil diseñar terapias de inhibición endógena. La molécula CTLA-4 ha sido el blanco de muchos estudios, los cuales han planteado diferentes estrategias novedosas para inducir inmunosupresión, algunos antígeno específicos, que se han convertido en nuevos pilares en el tratamiento de las enfer- medades autoinmunes y rechazo de transplantes. Palabras claves: Linfocito T, Ag-4 asociado al Linfocito T Citotóxico, tolerancia inmunológica, inmunosupresión, autoinmunidad, transplante / SALUD UNINORTE. Barranquilla (Col.) 2006; 22 (2): 168-181 Abstract CTLA-4 (Cytotoxic T lymphocyte-associated Ag-4) is a molecule expressed on the surface of acti- vated T lymphocytes, the function of CTLA-4 is regulate T cell homeostasis and peripheral immune tolerance, inhibiting T cell activation. Two mechanisms have been postulated to mediate CTLA-4 inhibition of T cell responses: Negative signaling and competitive antagonism of CD28:B7-medi- ated costimulation. The different participating molecules in T cell activation and T cell inactivation have been analyzed to design therapeutic strategies for immune tolerance. The progress has been based upon interference with lymphocyte activation, costimulation, or cytokine signals, but It has been very difficult to design therapeutic strategies that specifically enhance endogenous inhibitory pathways. CTLA-4 has been the target of several studies, that have brought forward different novel strategies to induce immunosuppression, some of them Ag-specific, that have become a new basis for the treatment of autoimmune disease and tissue transplantation rejection. Key words: T lymphocyte, Cytotoxic T lymphocyte-associated Ag-4, immune tolerance, immunosuppression, autoimmunity, transplan

Cell Signaling in Neuronal Stem Cells

The defining characteristic of neural stem cells (NSCs) is their ability to multiply through symmetric divisions and proliferation, and differentiation by asymmetric divisions, thus giving rise to different types of cells of the central nervous system (CNS). A strict temporal space control of the NSC differentiation is necessary, because its alterations are associated with neurological dysfunctions and, in some cases, death. This work reviews the current state of the molecular mechanisms that regulate the transcription in NSCs, organized according to whether the origin of the stimulus that triggers the molecular cascade in the CNS is internal (intrinsic factors) or whether it is the result of the microenvironment that surrounds the CNS (extrinsic factors)

The Role of Microglia in Glioblastoma

Glioblastoma (GB), the most aggressive malignant glioma, is made up of a large percentage of glioma-associated microglia/macrophages (GAM), suggesting that immune cells play an important role in the pathophysiology of GB. Under physiological conditions, microglia, the phagocytes of the central nervous system (CNS), are involved in various processes such as neurogenesis or axonal growth, and the progression of different conditions such as Alzheimer's disease. Through immunohistochemical studies, markers that enhance GB invasiveness have been shown to be expressed in the peritumoral area of the brain, such as Transforming Growth Factor alpha (TGF-alpha), Stromal Sell-Derived Factor 1 (SDF1/CXCL12), Sphingosine-1-Phosphate (S1P) and Neurotrophic Factor Derived from the Glial cell line (GDNF), contributing to the increase in tumor mass. Similarly, it has also been described 17 biomarkers that are present in hypoxic periarteriolar HSC niches in bone marrow and in hypoxic periarteriolar GSC niches in glioblastoma. Interestingly, microglia plays an important role in the microenvironment that supports GB progression, being one of the most important focal points in the study of therapeutic targets for the development of new drugs. In this review, we describe the altered signaling pathways in microglia in the context of GB. We also show how microglia interact with glioblastoma cells and the epigenetic mechanisms involved. Regarding the interactions between microglia and neurogenic niches, some authors indicate that glioblastoma stem cells (GSC) are similar to neural stem cells (NSC), common stem cells in the subventricular zone (SVZ), suggesting that this could be the origin of GB. Understanding the similarities between SVZ and the tumor microenvironment could be important to clarify some mechanisms involved in GB malignancy and to support the discovering of new therapeutic targets for the development of more effective glioblastoma treatments

The Role of Glycosyltransferases in Colorectal Cancer

Colorectal cancer (CRC) is one of the main causes of cancer death in the world. Posttranslational modifications (PTMs) have been extensively studied in malignancies due to its relevance in tumor pathogenesis and therapy. This review is focused on the dysregulation of glycosyltransferase expression in CRC and its impact in cell function and in several biological pathways associated with CRC pathogenesis, prognosis and therapeutic approaches. Glycan structures act as interface molecules between cells and their environment and in several cases facilitate molecule function. CRC tissue shows alterations in glycan structures decorating molecules, such as annexin-1, mucins, heat shock protein 90 (Hsp90), 1 integrin, carcinoembryonic antigen (CEA), epidermal growth factor receptor (EGFR), insulin-like growth factor-binding protein 3 (IGFBP3), transforming growth factor beta (TGF- ) receptors, Fas (CD95), PD-L1, decorin, sorbin and SH3 domain-containing protein 1 (SORBS1), CD147 and glycosphingolipids. All of these are described as key molecules in oncogenesis and metastasis. Therefore, glycosylation in CRC can affect cell migration, cell–cell adhesion, actin polymerization, mitosis, cell membrane repair, apoptosis, cell differentiation, stemness regulation, intestinal mucosal barrier integrity, immune system regulation, T cell polarization and gut microbiota composition; all such functions are associated with the prognosis and evolution of the disease. According to these findings, multiple strategies have been evaluated to alter oligosaccharide processing and to modify glycoconjugate structures in order to control CRC progression and prevent metastasis. Additionally, immunotherapy approaches have contemplated the use of neo-antigens, generated by altered glycosylation, as targets for tumor-specific T cells or engineered CAR (Chimeric antigen receptors) T cells

Immune modulation by the hepatitis C virus core protein

Hepatitis C virus (HCV) infection is currently the most important cause of chronic viral hepatitis in the world and one of the most frequent indications for liver transplantation. HCV uses different strategies to evade the innate and adaptive immune response, and this evasion plays a key role in determining viral persistence. Several HCV viral proteins have been described as immune modulators. In this review, we will focus on the effect of HCV nucleocapsid core protein in the function of immune cells and its correlation with the findings observed in HCV chronically infected patients. Effects on immune cell function related to both extracellular and intracellular HCV core localization will be considered. This review provides an updated perspective on the mechanisms involved in HCV evasion related to one single HCV protein, which could become a key tool in the development of new antiviral strategies able to control and/or eradicate HCV infection.Ministerio de Educación y Ciencia (España) (SAF2009-09449); Consejería de Salud de la Junta de Andalucía (SAS 111206

Preparation and characterization of fluorescent CdS quantum dots used for the direct detection of GsT fusion proteins

Advances in the life sciences are now closely linked to the availability of new experimental tools that allow for the manipulation of biomolecules and the study of biological processes at the molecular level. In this context, we have optimized a synthesis process to obtain glutathione-capped fluorescent CdS nanoparticles to specifically detect Glutathione S-Transferase (GST) -tagged proteins. Using our method, based on five different heating steps, brightly fluorescent and biocompatible CdS quantum dots of different sizes can be obtained. QD optical behaviour has been evaluated studying both absorbance and fluorescence. For all the samples, the excitonic absorption onset clearly shows a blue shift at 512nm in comparison with that of bulk CdS, due to the quantum confinement effect. At increased average sizes of the nanocrystal, the emission fluorescent band shows a red shift, from 440nm to 540nm. Among different QD solutions, we demonstrate an expansion of the emission range up to ~100 nm, thus improving their features as biomarkers. Moreover we show that optimized glutathione-capped quantum dots can directly bind GST blotted onto polyvinylidene difluoride (PVDF) membranes, and thus are suitable for the direct detection of GST fusion proteins.Proyectos del Ministerio de Innovación y Ciencia (PN/PETRI/PR/2007‐019) y Junta de Andalucía (P08‐CTS‐04348

Solvothermal synthesis and characterization of ytterbium/iron mixed oxide nanoparticles with potential functionalities for applications as multiplatform contrast agent in medical image techniques

A solvothermal route to prepare Glutathione capped hybrid ytterbium/iron oxide nanoparticles with potential applications as multiplatform contrast agent in medical image techniques has been developed. The influence of ytterbium/iron molar ratio used as precursor, as well as the degree of the autoclave filling on the structural and morphological characteristics of the obtained nanoparticles has been extensively studied. Although all nanoparticles present similar composition, with YbFeO3 being the majority phase, size and morphology of the as synthetized nanoparticles are highly influenced by the critical temperature and by the over -saturation reached during the solvothermal process. We have demonstrated that glutathione properly functionalizes the hybrid nanoparticles, increasing their colloidal stability and decreasing their cytotoxicity. Additionally, they show good imaging in magnetic resonance and X-ray computerized tomography, thereby indicating promising potential as a dual contrast agent. This work presents, for the first time, glutathione functionalized ytterbium/iron oxide nanoparticles with potential applications in Biomedicine.12 página

Ex situ and in situ functionalized Yb/Fe nanoparticles obtained by scanning pulsed laser ablation in liquids: A route to obtain biofunctionalized multiplatform contrast agents for MRI and CT imaging

Two distinct strategies were used to improve the colloidal properties of hybrid Yb/Fe oxide NPs previously prepared by the pulsed liquid laser ablation process for use as a contrast agent in medical imaging. First, an exhaustive optimization process of the laser ablation synthesis parameters was carried out to reduce the hydrodynamic diameters of the Yb/Fe NPs. The hydrodynamic size was successfully reduced to <200 nm, thereby decreasing the polydispertivity index. Second, ex situ and in situ functionalization processes using glutathione, cysteamine, or polyethylenimine as capping agents have been developed to increase their colloidal stability at physiological pH values. Transmission electron microscopy, dynamic light scattering, Z-potential measurements, and Fourier Transform Infrared spectroscopy were used to examine the structure, morphology, colloidal and surface properties of Yb/Fe NPs. Colloidal stability of the Yb/Fe NPs as well as the linkage mechanism of functionalization have been studied extensively. This last parameter provides a critical information for subsequently bioconjugations in biomedical applications. Additionally, the biocompatibility of the Yb/Fe NPs was evaluated by MTT (3-(4,5-dimethylthiazol- 2-yl)-2,5-diphenyltetrazolium bromide) experiments. These results indicate more appropriate colloidal characteristics and higher biocompatibility for ex situ-functionalized Yb/Fe NPs, especially when the capping agent is glutathione. Additionally, these Yb/Fe NPs show good magnetic resonance imaging and X-ray computerized tomography imaging abilities, thereby indicating promising potential as dual contrast agents

A Stretch of Negatively Charged Amino Acids of Linker for Activation of T-Cell Adaptor Has a Dual Role in T-Cell Antigen Receptor Intracellular Signaling

The adaptor protein linker for activation of T cells (LAT) has an essential role transducing activatory intracellular signals coming from the TCR/CD3 complex. Previous reports have shown that upon T-cell activation, LAT interacts with the tyrosine kinase Lck, leading to the inhibition of its kinase activity. LAT-Lck interaction seemed to depend on a stretch of negatively charged amino acids in LAT. Here, we have substituted this segment of LAT between amino acids 113 and 126 with a non-charged segment and expressed the mutant LAT (LAT-NIL) in J.CaM2 cells in order to analyze TCR signaling. Substitution of this segment in LAT prevented the activation-induced interaction with Lck. Moreover, cells expressing this mutant form of LAT showed a statistically significant increase of proximal intracellular signals such as phosphorylation of LAT in tyrosine residues 171 and 191, and also enhanced ZAP70 phosphorylation approaching borderline statistical significance (p = 0.051). Nevertheless, downstream signals such as Ca2+ influx or MAPK pathways were partially inhibited. Overall, our data reveal that LAT-Lck interaction constitutes a key element regulating proximal intracellular signals coming from the TCR/CD3 complex.Consejería de Salud de Andalucía, Junta de Andalucía (grants PI-0365-2013 and PI-0055-2017); Instituto de Salud Carlos III (grant PI16-00784 from the “Plan Estatal de I+D+I 2013–2016/FEDER”