Effects of local and systemic treatment with human natural killer-1 mimetic peptide (HNK-1) after ventral root avulsion and reimplantation in mice.

Background: Spinal ventral root injuries generate significant motoneuron degeneration, which hinders full functional recovery. The poor prognosis of functional recovery can be attributed to the use or combination of different therapeutic approaches. Several molecules have been screened as potential treatments in combination with surgical reimplantation of the avulsed roots, the gold standard approach for such injuries. Among the studied molecules, human natural killer-1 (HNK-1) stands out as it is related to the stimulation of motor axon outgrowth. Therefore, we aimed to comparatively investigate the effects of local administration of an HNK-1 mimetic peptide (mp-HNK-1) and systemic treatment with ursolic acid (UA), another HNK-1 mimetic, after ventral root avulsion and reimplantation with heterologous fibrin biopolymer (HFB). Methods: Female mice of the isogenic strain C57BL/6JUnib were divided into five experimental groups: Avulsion, Reimplantation, mp-HNK-1 (in situ), and UA (systemic treatment). Mice were evaluated 2 and 12 weeks after surgery. Functional assessment was performed every four days using the Catwalk platform. Neuronal survival was analyzed by cytochemistry, and glial reactions and synaptic coverage were evaluated by immunofluorescence. Results: Treatment with UA elicited long-term neuroprotection, accompanied by a decrease in microglial reactions, and reactive astrogliosis. The neuroprotective effects of UA were preceded by increased glutamatergic and GABAergic inputs in the ventral spinal cord two weeks after injury. However, a single application of mp-HNK-1 had no significant effects. Functional analysis showed that UA treatment led to an improvement in motor and sensory recovery. Conclusion: Overall, the results indicate that UA is neuroprotective, acting on glial cells and synaptic maintenance, and the combination of these findings led to a better functional recovery.

Immunodiagnostic of leprosy exploiting a photoelectrochemical platform based on a recombinant peptide mimetic of a Mycobacterium leprae antigen.

The first serum diagnosis of leprosy based on the detection of antibodies of patients using a recombinant mimetic peptide (PGL1M3R) as recognition element and exploiting a photoelectrochemical sensor is presented in this work. The photoeletrochemical platform consists of cadmium sulphide and nickel hydroxide electrodeposited on fluorine-doped tin oxide coated glass slide (CdS/Ni(OH)2/FTO). The optical band gap and flat band potential of the photoelectroactive materials were evaluated by UV-Vis spectroscopy and electrochemical impedance spectroscopy. The spatial photoelectrochemical response of the platform was evaluated by Scanning Electrochemical Microscopy and the morphology of the films was investigated by Scanning Electron Microscopy (SEM). The photoelectrochemical response of the CdS/Ni(OH)2/FTO platform was optimized by evaluating the effects of the kind, concentration, and pH of the buffer. Furthermore, the applied potential to the CdS/Ni(OH)2/FTO platform was also investigated. The CdS/Ni(OH)2/FTO photoelectrochemical platform was modified with a synthetic peptide by using glutaraldehyde as cross-linking reagent and chitosan (CS) for the covalent coupling of the peptide to the photoelectrochemical platform (PGL1M3R/CdS/Ni(OH)2/FTO). The photoelectrochemical immunosensor is able to distinguishing between positive and negative leprosy human sera samples diluted from 1:640 up to 1:10240. Furthermore, to test the specificity of the sensor, samples from tuberculosis and leishmaniasis patients were analyzed using the proposed photoelectrochemical immunosensor.

A novel peptide-based sensor platform for detection of anti-Toxoplasma gondii immunoglobulins.

Toxoplasma gondii is an intracellular protozoan parasite responsible for toxoplasmosis, which affects humans and animals. Serologic detection of anti-T. gondii immunoglobulins plays a crucial role in the clinical diagnosis of toxoplasmosis. In this work, a novel electrochemical immunosensor for detecting anti-T. gondii immunoglobulins is reported, based on immobilization of an in silico predicted peptide (PepB3), obtained from membrane protein of T. gondii, on the graphite electrode modified with poly(3-hydroxybenzoic acid). Indirect ELISA confirmed infection and binding specificity of peptide PepB3. Molecular modelling and simulations show this peptide binds to the T. gondii human Fab antibody in the surface antigen 1 (SAG1) binding site, remaining a stable complex during the molecular dynamic simulations, especially by hydrogen bonds and hydrophobic interactions. This electrochemical immunosensor was able to discriminate different periods of infection, using infected mouse serum samples, showing selectivity and discriminating infected and uninfected mouse serum.

Serological Electrodetection of Rheumatoid Arthritis Using Mimetic Peptide.

BACKGROUND: Rheumatoid arthritis is the most common inflammatory autoimmune disease in the world. Recently new targets for its detection were developed as alternatives to classic biomarkers, including the M-12 peptide, that mimics carbonic anhydrase III. Thus, the application of this peptide for the development of new detection devices is attractive. OBJECTIVE: Our goal was to construct a modified electrode for immobilization of M-12 peptide and detection of a rheumatoid arthritis biomarker in serum of patients. METHODS: 3-Hydroxybenzoic acid was electropolymerized onto graphite electrodes, and M-12 peptide was immobilized by adsorption. Negative and positive serum samples for rheumatoid arthritis were diluted and applied onto the electrode. Detection was carried in potassium ferrocyanide/ ferricyanide solution by differential pulse voltammetry. Atomic force microscopy and scanning electron microscopy were used to evaluate electrode surfaces. RESULTS: Cyclic voltammograms indicated the poly(3-hydroxybenzoic acid) formation and increase of electroactive area. Immobilization of M-12 probe increased current by 1.2 times, and negative serum addition caused no suitable difference. However, positive serum showed expressive decrease in the current signal of about 2.2 times, possibly due to steric hindrance when the anti-CA3 antibody interacts with the M-12 peptide, decreasing the electron transfer. Microscopies images corroborated with the electrochemical detection, showing evident changes in the morphology of the electrode surfaces. CONCLUSION: The bioelectrode was able to discriminate positive and negative serum samples of rheumatoid arthritis by a considerable decrease in the current signal value. Morphological analyses supported the electrochemical results. Thus, the constructed bioelectrode offers a new platform for detection of rheumatoid arthritis.

Peptide-based electrochemical biosensor for juvenile idiopathic arthritis detection.

Juvenile idiopathic arthritis (JIA) is a wide group of diseases, characterized by synovial inflammation and joint tissue damage. Due to the delay in the implementation of biomarkers into clinical practice and the association with severe sequels, there is an imperative need for new JIA diagnosis strategies. Electrochemical biosensors based on screen-printed electrodes and peptides are promising alternatives for molecular diagnosis. In this work, a novel biosensor for detecting juvenile idiopathic arthritis (JIA) was developed based on the immobilization of the PRF+1 mimetic peptide, as recognition biological element, on the surface of screen-printed carbon electrode. This biosensor was able to discriminate the JIA positive and negative serum samples from different individuals using differential pulse voltammetry, presenting limits of detection and quantification in diluted samples of 1:784 (v/v) and 1:235 (v/v), respectively. Evaluation by electrochemical impedance spectroscopy showed RCT 3 times higher for JIA positive sample than for a pool of human serum samples from healthy individuals. Surface analysis of the biosensor by atomic force microscopy, after contact with JIA positive serum, presented great globular clusters irregularly distributed. The long-term stability of the biosensor was evaluated, remaining functional for over 40 days of storage (after storage at 8°C). Therefore, a simple, miniaturized and selective biosensor was developed, being the first one based on mimetic peptide and screen-printed carbon electrode, aiming at the diagnosis of the juvenile idiopathic arthritis in real serum samples.

Papel protector de las lipoproteínas de alta densidad en sepsis: aspectos básicos e implicancias clínicas / Protective role of high density lipoproteins in sepsis: basic issues and clinical implications

High density lipoproteins (HDL) are responsible of reverse cholesterol transport and play an important antiatherogenic role. In recent years, several studies suggest that HDL have additional functions, including a possible anti-inflammatory activity in infectious conditions. Furthermore, available evidence indicates that the presence of lipopolysaccharide (LPS) within the circulation during infectious states induced by gram-negative bacteria may be involved in the decrease in HDL cholesterol levels and changes in lipoprotein composition, which have been associated with a higher mortality due to sepsis in animal models and in humans. In this article, we review this subject and also discuss possible mechanisms that explain the positive impact achieved by native HDL, reconstituted HDL, or HDL apolipoprotein peptides on the inflammatory response and mortality in models of endotoxemia. In this regard, it has been proposed that one of the mechanisms by which HDL protect against sepsis may be mediated by its binding ability and/or neutralizing capacity on LPS, avoiding an excessive response of the immune system. Thus, increasing blood levels of HDL and/or parenteral HDL administration may represent a new anti-inflammatory tool for managing septic states in humans.

Las lipoproteínas de alta densidad (HDL) son responsables del transporte reverso de colesterol y ejercen un importante papel anti-aterogénico. En los últimos años, diversos estudios indican que las HDL también tendrían otras funciones críticas, incluyendo una posible actividad anti-inflamatoria durante estados infecciosos. Además, la evidencia disponible sugiere que la presencia de lipopolisacárido (LPS) en la circulación durante estados infecciosos inducidos por bacterias gramnegativas podría estar involucrado en la disminución del colesterol HDL y los cambios en composición de esta clase lipoproteínas, lo cual se asociaría con una mayor tasa de mortalidad por sepsis en modelos animales y en humanos. En este trabajo, se revisan los antecedentes mencionados y además se discuten posibles mecanismos que explican la disminución de la respuesta inflamatoria y de la mortalidad que se logran en modelos de endotoxemia tratados con HDL o preparaciones similares. En este sentido, se ha propuesto que uno de los mecanismos protectores de las HDL estaría mediado por su capacidad de unión y/o neutralización del LPS, evitando una respuesta exacerbada del sistema inmune. De esta manera, el aumento de los niveles sanguíneos de HDL y/o su administración parenteral podrían constituir nuevas herramientas anti-inflamatorias para el manejo de estados sépticos en humanos.