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

Therapeutic Effect of a Latent Form of Cortistatin in Experimental Inflammatory and Fibrotic Disorders

Cortistatin is a cyclic neuropeptide that recently emerged as an attractive therapeutic factor for treating inflammatory, autoimmune, fibrotic, and pain disorders. Despite of its efficiency and apparent safety in experimental preclinical models, its short half-life in body fluids and its potential pleiotropic effects, due to its promiscuity for several receptors expressed in various cells and tissues, represent two major drawbacks for the clinical translation of cortistatin-based therapies. Therefore, the design of new strategies focused on increasing the stability, bioavailability, and target specificity of cortistatin are lately demanded by the industry. Here, we generated by molecular engineering a new cortistatin-based prodrug formulation that includes, beside the bioactive cortistatin, a molecular-shield provided by the latency-associated protein of the transforming growth factor-β1 and a cleavage site specifically recognized by metalloproteinases, which are abundant in inflammatory/fibrotic foci. Using different models of sepsis, inflammatory bowel disease, scleroderma, and pulmonary fibrosis, we demonstrated that this latent form of cortistatin was a highly effective protection against these severe disorders. Noteworthy, from a therapeutic point of view, is that latent cortistatin seems to require significantly lower doses and fewer administrations than naive cortistatin to reach the same efficacy. Finally, the metalloproteinase-cleavage site was essential for the latent molecule to exert its therapeutic action. In summary, latent cortistatin emerges as a promising innovative therapeutic tool for treating chronic diseases of different etiologies with difficult clinical solutions and as a starting point for a rational development of prodrugs based on the use of bioactive peptides.

EGFR-targeting antitumor therapy: Neuregulins or antibodies?

Malignancies such as lung, breast and pancreatic carcinomas are associated with increased expression of the epidermal growth factor receptor, EGFR, and its role in the pathogenesis and progression of tumors has made this receptor a prime target in the development of antitumor therapies. In therapies targeting EGFR, the development of resistance owing to mutations and single nucleotide polymorphisms, and the expression of the receptor ligands themselves are very serious issues. In this work, both the ligand neuregulin and a bispecific antibody fragment to EGFR are conjugated separately or together to the same drug-delivery system to find the most promising candidate. Camptothecin is used as a model chemotherapeutic drug and superparamagnetic iron oxide nanoparticles as a delivery system. Results show that the lowest LD50 is achieved by formulations conjugated to both the antibody and the ligand, demonstrating a synergy. Additionally, the ligand location in the nucleus favors the antitumor activity of Camptothecin. The high loading capacity and efficiency convert these systems into a good alternative for administering Camptothecin, a drug whose use is otherwise severely limited by its chemical instability and poor solubility. Our choice of targeting agents allows treating tumors that express ErbB2 (Her2+ tumors) as well as Her2- tumors expressing EGFR.

The influencing factors and functions of DNA G-quadruplexes

G‐quadruplexes form folded structures because of tandem repeats of guanine sequences in DNA or RNA. They adopt a variety of conformations, depending on many factors, including the type of loops and cations, the nucleotide strand number, and the main strand polarity of the G‐quadruplex. Meanwhile, the different conformations of G‐quadruplexes have certain influences on their biological functions, such as the inhibition of transcription, translation, and DNA replication. In addition, G‐quadruplex binding proteins also affect the structure and function of G‐quadruplexes. Some chemically synthesized G‐quadruplex sequences have been shown to have biological activities. For example, bimolecular G‐quadruplexes of AS1411 act as targets of exogenous drugs that inhibit the proliferation of malignant tumours. G‐quadruplexes are also used as vehicles to deliver nanoparticles. Thus, it is important to identify the factors that influence G‐quadruplex structures and maintain the stability of G‐quadruplexes. Herein, we mainly discuss the factors influencing G‐quadruplexes and the synthetic G‐quadruplex, AS1411.

Significance of the study

This review summarizes the factors that influence G‐quadruplexes and the functions of the synthetic G‐quadruplex, AS1411. It also discusses the use of G‐quadruplexes for drug delivery in tumour therapy.

A Clinical Approach for the Use of VIP Axis in Inflammatory and Autoimmune Diseases

The neuroendocrine and immune systems are coordinated to maintain the homeostasis of the organism, generating bidirectional communication through shared mediators and receptors. Vasoactive intestinal peptide (VIP) is the paradigm of an endogenous neuropeptide produced by neurons and endocrine and immune cells, involved in the control of both innate and adaptive immune responses. Exogenous administration of VIP exerts therapeutic effects in models of autoimmune/inflammatory diseases mediated by G-protein-coupled receptors (VPAC1 and VPAC2). Currently, there are no curative therapies for inflammatory and autoimmune diseases, and patients present complex diagnostic, therapeutic, and prognostic problems in daily clinical practice due to their heterogeneous nature. This review focuses on the biology of VIP and VIP receptor signaling, as well as its protective effects as an immunomodulatory factor. Recent progress in improving the stability, selectivity, and effectiveness of VIP/receptors analogues and new routes of administration are highlighted, as well as important advances in their use as biomarkers, contributing to their potential application in precision medicine. On the 50th anniversary of VIP's discovery, this review presents a spectrum of potential clinical benefits applied to inflammatory and autoimmune diseases.

Manganese doped-iron oxide nanoparticle clusters and their potential as agents for magnetic resonance imaging and hyperthermia

A simple, one pot method to synthesize water-dispersible Mn doped iron oxide colloidal clusters constructed of nanoparticles arranged into secondary flower-like structures was developed. This method allows the successful incorporation and homogeneous distribution of Mn within the nanoparticle iron oxide clusters. The formed clusters retain the desired morphological and structural features observed for pure iron oxide clusters, but possess intrinsic magnetic properties that arise from Mn doping. They show distinct performance as imaging contrast agents and excellent characteristics as heating mediators in magnetic fluid hyperthermia. It is expected that the outcomes of this study will open up new avenues for the exploitation of doped magnetic nanoparticle assemblies in biomedicine.

Assessing the hyperthermic properties of magnetic heterostructures: the case of gold-iron oxide composites

Gold-iron oxide composites were obtained by in situ reduction of an Au(III) precursor by an organic reductant (either potassium citrate or tiopronin) in a dispersion of preformed iron oxide ultrasmall magnetic (USM) nanoparticles. X-ray diffraction, transmission electron microscopy, chemical analysis and mid-infrared spectroscopy show the successful deposition of gold domains on the preformed magnetic nanoparticles, and the occurrence of either citrate or tiopronin as surface coating. The potential of the USM@Au nanoheterostructures as heat mediators for therapy through magnetic fluid hyperthermia was determined by calorimetric measurements under sample irradiation by an alternating magnetic field with intensity and frequency within the safe values for biomedical use. The USM@Au composites showed to be active heat mediators for magnetic fluid hyperthermia, leading to a rapid increase in temperature under exposure to an alternating magnetic field even under the very mild experimental conditions adopted, and their potential was assessed by determining their specific absorption rate (SAR) and compared with the pure iron oxide nanoparticles. Calorimetric investigation of the synthesized nanostructures enabled us to point out the effect of different experimental conditions on the SAR value, which is to date the parameter used for the assessment of the hyperthermic efficiency.

Targeted multifunctional tannic acid nanoparticles

Tannic acid nanoparticles targeted to the epidermal growth factor receptor allows selective delivery of this promising chemotherapeutic agent to tumoral cells.

'Smart' nanoparticles as drug delivery systems for applications in tumor therapy

INTRODUCTION

In the therapy of clinical diseases such as cancer, it is important to deliver drugs directly to tumor sites in order to maximize local drug concentration and reduce side effects. This objective may be realized by using 'smart' nanoparticles (NPs) as drug delivery systems, because they enable dramatic conformational changes in response to specific physical/chemical stimuli from the diseased cells for targeted and controlled drug release.

AREAS COVERED

In this review, we first briefly summarize the characteristics of 'smart' NPs as drug delivery systems in medical therapy, and then discuss their targeting transport, transmembrane and endosomal escape behaviors. Lastly, we focus on the applications of 'smart' NPs as drug delivery systems for tumor therapy.

EXPERT OPINION

Biodegradable 'smart' NPs have the potential to achieve maximum efficacy and drug availability at the desired sites, and reduce the harmful side effects for healthy tissues in tumor therapy. It is necessary to select appropriate NPs and modify their characteristics according to treatment strategies of tumor therapy.

PEGylated versus non-PEGylated magnetic nanoparticles as camptothecin delivery system

Camptothecin (CPT; (S)-(+)-4-ethyl-4-hydroxy-1H-pyrano[3',4':6,7]indolizino[1,2-b]quinoline-3,14-(4H,12H)-dione) is a highly cytotoxic natural alkaloid that has not yet found use as chemotherapeutic agent due to its poor water-solubility and chemical instability and, as a consequence, no effective administration means have been designed. In this work, camptothecin has been successfully loaded into iron oxide superparamagnetic nanoparticles with an average size of 14 nm. It was found that surface modification of the nanoparticles by polyethylene glycol enables loading a large amount of camptothecin. While the unloaded nanoparticles do not induce apoptosis in the H460 lung cancer cell line, the camptothecin-loaded nanoparticle formulations exhibit remarkable pro-apoptotic activity. These results indicate that camptothecin retains its biological activity after loading onto the magnetic nanoparticles. The proposed materials represent novel materials based on naturally occurring bioactive molecules loaded onto nanoparticles to be used as chemotherapeutic formulations. The procedure seems apt to be extended to other active molecules extracted from natural products. In addition, these materials offer the potential of being further implemented for combined imaging and therapeutics, as magnetic nanoparticles are known to be multifunctional tools for biomedicine.

Nanoporous silica microparticle interaction with toll-like receptor agonists in macrophages

Nanoporous silica microparticles (NSiO(2)-MP) are considered to be potential drug delivery systems and scaffolding platforms in tissue engineering. However, few biocompatibility studies regarding NSiO(2)-MP interaction with the immune system have been reported. Toll-like receptors (TLR) are involved in host defence as well as autoimmune and inflammatory diseases. The results show that NSiO(2)-MP up to 100μgml(-1) do not affect macrophage cell viability after 24h cell culture. Moreover, NSiO(2)-MP do not compromise the cell viability of TLR-activated Raw 264.7 cells, for either cell surface TLR (TLR1/TLR2/TLR4/TLR6) or endocytic compartment TLR (TLR3/TLR7/TLR9). Furthermore, Raw 264.7 cells do not respond to NSiO(2)-MP exposure in terms of IL-6 or IL-10 secretion. NSiO(2)-MP co-treatment in the presence of TLR ligands does not impair or enhance the secretion of the pro-inflammatory cytokine IL-6 or the regulatory cytokine IL-10. Thus, NSiO(2)-MP do not affect macrophage polarization towards a pro-inflammatory or immunosuppressive status, representing added value in terms of biocompatibility compared with other SiO(2)-based micro- and nanoparticles.

VPAC receptors: structure, molecular pharmacology and interaction with accessory proteins

The vasoactive intestinal peptide (VIP) is a neuropeptide with wide distribution in both central and peripheral nervous systems, where it plays important regulatory role in many physiological processes. VIP displays a large biological functions including regulation of exocrine secretions, hormone release, fetal development, immune responses, etc. VIP appears to exert beneficial effect in neuro-degenerative and inflammatory diseases. The mechanism of action of VIP implicates two subtypes of receptors (VPAC1 and VPAC2), which are members of class B receptors belonging to the super-family of GPCR. This article reviews the current knowledge regarding the structure and molecular pharmacology of VPAC receptors. The structure-function relationship of VPAC1 receptor has been extensively studied, allowing to understand the molecular basis for receptor affinity, specificity, desensitization and coupling to adenylyl cyclase. Those studies have clearly demonstrated the crucial role of the N-terminal ectodomain (N-ted) of VPAC1 receptor in VIP recognition. By using different approaches including directed mutagenesis, photoaffinity labelling, NMR, molecular modelling and molecular dynamic simulation, it has been shown that the VIP molecule interacts with the N-ted of VPAC1 receptor, which is itself structured as a 'Sushi' domain. VPAC1 receptor also interacts with a few accessory proteins that play a role in cell signalling of receptors. Recent advances in the structural characterization of VPAC receptor and more generally of class B GPCRs will lead to the design of new molecules, which could have considerable interest for the treatment of inflammatory and neuro-degenerative diseases.

The VPAC1 receptor: structure and function of a class B GPCR prototype

The class B G protein-coupled receptors (GPCRs) represents a small sub-family encompassing 15 members, and are very promising targets for the development of drugs to treat many diseases such as chronic inflammation, neurodegeneration, diabetes, stress, and osteoporosis. The VPAC1 receptor which is an archetype of the class B GPCRs binds Vasoactive Intestinal Peptide (VIP), a neuropeptide widely distributed in central and peripheral nervous system modulating many physiological processes including regulation of exocrine secretions, hormone release, foetal development, immune response … VIP appears to exert beneficial effect in neurodegenerative and inflammatory diseases. This article reviews the current knowledge regarding the structure and molecular pharmacology of VPAC1 receptors. Over the past decade, structure-function relationship studies have demonstrated that the N-terminal ectodomain (N-ted) of VPAC1 plays a pivotal role in VIP recognition. The use of different approaches such as directed mutagenesis, photoaffinity labeling, Nuclear Magnetic Resonance (NMR), molecular modeling, and molecular dynamic simulation has led to demonstrate that: (1) the central and C-terminal part of the VIP molecule interacts with the N-ted of VPAC1 receptor which is itself structured as a « Sushi » domain; (2) the N-terminal end of the VIP molecule interacts with the first transmembrane domain of the receptor where three residues (K(143), T(144), and T(147)) play an important role in VPAC1 interaction with the first histidine residue of VIP.

Targeting VIP and PACAP receptor signalling: new therapeutic strategies in multiple sclerosis

MS (multiple sclerosis) is a chronic autoimmune and neurodegenerative pathology of the CNS (central nervous system) affecting approx. 2.5 million people worldwide. Current and emerging DMDs (disease-modifying drugs) predominantly target the immune system. These therapeutic agents slow progression and reduce severity at early stages of MS, but show little activity on the neurodegenerative component of the disease. As the latter determines permanent disability, there is a critical need to pursue alternative modalities. VIP (vasoactive intestinal peptide) and PACAP (pituitary adenylate cyclase-activating peptide) have potent anti-inflammatory and neuroprotective actions, and have shown significant activity in animal inflammatory disease models including the EAE (experimental autoimmune encephalomyelitis) MS model. Thus, their receptors have become candidate targets for inflammatory diseases. Here, we will discuss the immunomodulatory and neuroprotective actions of VIP and PACAP and their signalling pathways, and then extensively review the structure–activity relationship data and biophysical interaction studies of these peptides with their cognate receptors.

Hybrid luminescent/magnetic nanostructured porous silicon particles for biomedical applications

This work describes a novel process for the fabrication of hybrid nanostructured particles showing intense tunable photoluminescence and a simultaneous ferromagnetic behavior. The fabrication process involves the synthesis of nanostructured porous silicon (NPSi) by chemical anodization of crystalline silicon and subsequent in pore growth of Co nanoparticles by electrochemically-assisted infiltration. Final particles are obtained by subsequent sonication of the Co-infiltrated NPSi layers and conjugation with poly(ethylene glycol) aiming at enhancing their hydrophilic character. These particles respond to magnetic fields, emit light in the visible when excited in the UV range, and internalize into human mesenchymal stem cells with no apoptosis induction. Furthermore, cytotoxicity in in-vitro systems confirms their biocompatibility and the viability of the cells after incorporation of the particles. The hybrid nanostructured particles might represent powerful research tools as cellular trackers or in cellular therapy since they allow combining two or more properties into a single particle.

Neuropeptides: keeping the balance between pathogen immunity and immune tolerance

Various neuropeptides have emerged recently as potent immunomodulatory factors with potential for their therapeutic use in immune disorders. Here we highlight the most recent data relevant in the field and we offer our opinion on how neuropeptide therapy might impact clinical immune diseases, and the challenges in this field that must be overcome before achieving medical progress. We also review recent reports describing the antimicrobial effects showed by some neuropeptides and the therapeutic, physiological, and evolutionary consequences of this new finding. Finally, we discuss how a physiologically functional neuropeptide system contributes to general health and how neuropeptides educate our immune system to be tolerant.

Studies on the biodistribution of dextrin nanoparticles

The characterization of biodistribution is a central requirement in the development of biomedical applications based on the use of nanoparticles, in particular for controlled drug delivery. The blood circulation time, organ biodistribution and rate of excretion must be well characterized in the process of product development. In this work, the biodistribution of recently developed self-assembled dextrin nanoparticles is addressed. Functionalization of the dextrin nanoparticles with a DOTA-monoamide-type metal chelator, via click chemistry, is described. The metal chelator functionalized nanoparticles were labelled with a gamma-emitting (153)Sm(3+) radioisotope and the blood clearance rate and organ biodistribution of the nanoparticles were obtained. The effect of PEG surface coating on the blood clearance rate and organ biodistribution of the nanoparticles was also studied.