Vitamin D-Regulated MicroRNAs: Are They Protective Factors against Dengue Virus Infection?

ABSTARCT: Over the last few years, an increasing body of evidence has highlighted the critical participation of vitamin D in the regulation of proinflammatory responses and protection against many infectious pathogens, including viruses. The activity of vitamin D is associated with microRNAs, which are fine tuners of immune activation pathways and provide novel mechanisms to avoid the damage that arises from excessive inflammatory responses. Severe symptoms of an ongoing dengue virus infection and disease are strongly related to highly altered production of proinflammatory mediators, suggesting impairment in homeostatic mechanisms that control the host's immune response. Here, we discuss the possible implications of emerging studies anticipating the biological effects of vitamin D and microRNAs during the inflammatory response, and we attempt to extrapolate these findings to dengue virus infection and to their potential use for disease management strategies

Activation and regulation of inflammasome NLRP3 in infectious diseases

ABSTRACT: Inflammation is an immune response to infectious agents and to signals that arise from host molecules in stress situations or after tissue damage. Many innate immune receptors take part in the inflammatory response and induce transcriptional activation leading to the production of a host of cytokines, chemokines and other inflammatory mediators. The IL-1β cytokines are exceptional in that they not only require transcriptional activation but also a proteolytic processing into biologically active cytokines. This activation step is mediated by caspase-1, which in turn is controlled by cytosolic multimolecular complexes named inflammasomes. The NLRP3 inflammasome responds to aggregated or crystalline material, as well as to microbes or pore-forming toxins, but activation mechanisms are not fully understood. The importance of this innate signaling complex is highlighted by the existence of several mechanisms that regulate NLRP3 activation at different levels. In this article we review such mechanisms.RESUMEN: La inflamación es una respuesta inmune frente a los agentes infecciosos y las señales moleculares de peligro, de estrés celular o que son producto del daño tisular. Muchos receptores de la inmunidad innata participan en la respuesta inflamatoria e inducen la activación transcripcional para la producción de una gran cantidad de citocinas, quimiocinas y otros mediadores inflamatorios. Sin embargo, las citocinas de la familia IL-1β son excepcionales, porque no solo requieren la activación transcripcional, sino también un procesamiento proteolítico para generar las citocinas con actividad biológica. Este paso es la activación mediada por la caspasa-1, que a su vez es controlada por varios complejos multimoleculares citosólicos denominados inflamasomas. El inflamasoma NLRP3 puede ser activado por material agregado o cristalino (partículas) y por varios microorganismos o toxinas derivadas de estos; sin embargo, aún no se entienden completamente sus mecanismos de activación. La importancia de este complejo de señalización innata se manifiesta por la existencia de varios mecanismos que regulan la activación de NLRP3 a diferentes niveles. En este artículo se revisan dichos mecanismos

Reconocimiento viral por el sistema inmune innato: papel de los receptores de reconocimiento de patrones

Pattern recognition receptors are the main sensors of the innate immune response. Their function is to recognize pathogenassociated molecular patterns, which are molecules essential for the survival of microbial pathogens, but are not produced by the host. The recognition of pathogen-associated molecular patterns by pattern recognition receptors leads to the expression of cytokines, chemokines, and co-stimulatory molecules that eliminate pathogens, such as viruses, for the activation of antigen presenting cells and for the activation of specific adaptive immunity. Among the most thoroughly studied pattern recognition receptors implicated in viral infections, there are the toll-like receptors (TLRs) and the RNA helicase-type retinoic acidinducible gene-1 receptors [or RIG-like receptors (RLRs)]. Moreover, other proteins such as PKR, 2’-5’ OAS, and ADAR also act as effector proteins in antiviral responses. The identification and characterization of pattern recognition receptors have contributed to our knowledge of the role of innate immunity in viral infections and has led us to better understand hostpathogen interactions. The most recent findings concerning the role of TLRs and RLRs in viral infections, the molecular mechanisms of viral ligand recognition through pattern recognition receptors, and the activation of their signaling pathways are discussed in this review. Los receptores de reconocimiento de patrones (PRR) son los principales sensores de la respuesta inmune innata. Su función es reconocer moléculas indispensables para la sobrevivencia de los patógenos, conocidas como patrones moleculares asociados a patógenos (PAMP). El reconocimiento de los PAMP por los PRR conlleva a la expresión de citoquinas, quimioquinas, y moléculas coestimuladoras implicadas en la eliminación de patógenos como virus, en la activación de células presentadoras de antígenos y en la inducción de una inmunidad adaptativa específica. Entre los PRR mejor descritos y con implicaciones en infecciones virales se encuentran los receptores tipo toll (TLR) y receptores tipo RNA helicasas inducibles por ácido retinoico (RLR); además las proteínas efectoras PKR, 2´- 5´ OAS y ADAR también participan activamente en la respuesta antiviral. La descripción y caracterización de los PRR ha contribuido enormemente al entendimiento del papel de la respuesta inmune innata en las infecciones virales y han sido usados para comprender mejor las interacciones hospederopatógenos. Se discuten en la presente revisión los más recientes conocimientos de los TLR y RLR, el mecanismo de reconocimiento de los virus vía PRRs y las vías de señalización activadas por dicho reconocimiento

Involvement of neutrophil hyporesponse and the role of toll-like receptors in human immunodeficiency virus 1 protection

ABSTARCT: Paracoccidioidomycosis (PCM) is a systemic granulomatous human mycosis caused by fungi of the genus Paracoccidioides, which is geographically restricted to Latin America. Inhalation of spores, the infectious particles of the fungus, is a common route of infection. The PCM treatment of choice is azoles such as itraconazole, but sulfonamides and amphotericin B are used in some cases despite their toxicity to mammalian cells. The current availability of treatments highlights the need to identify and characterize novel targets for antifungal treatment of PCM as well as the need to search for new antifungal compounds obtained from natural sources or by chemical synthesis. To this end, we evaluated the antifungal activity of a camphene thiosemicarbazide derivative (TSC-C) compound on Paracoccidioides yeast. To determine the response of Paracoccidioides spp. to TSC-C, we analyzed the transcriptional profile of the fungus after 8 h of contact with the compound. The results demonstrate that Paracoccidioides lutzii induced the expression of genes related to metabolism; cell cycle and DNA processing; biogenesis of cellular components; cell transduction/signal; cell rescue, defense and virulence; cellular transport, transport facilities and transport routes; energy; protein synthesis; protein fate; transcription; and other proteins without classification. Additionally, we observed intensely inhibited genes related to protein synthesis. Analysis by fluorescence microscopy and flow cytometry revealed that the compound induced the production of reactive oxygen species. Using an isolate with down-regulated SOD1 gene expression (SOD1-aRNA), we sought to determine the function of this gene in the defense of Paracoccidioides yeast cells against the compound. Mutant cells were more susceptible to TSC-C, demonstrating the importance of this gene in response to the compound. The results presented herein suggest that TSC-C is a promising candidate for PCM treatment

Papel de los receptores tipo toll en las infecciones virales: el VIH-1 como modelo

The toll-like receptors are an essential component of the innate and adaptive immune response. They are responsible for the recognition of different pathogens agents and trigger responses directed at eliminating the pathogens as well as the development of immunological long-term memory. During viral infections, several different toll-like receptors are activated. These generally induce a protective immune response, but at the same time, can also be part of the pathogenic mechanisms of the viral infection. One of the viral infections in which toll-like receptors participate is the HIV-1 infection. Here, several receptors are activated to develop antiviral responses mediated by interferon type I; however virus replication and spreading dissemination are also favoured by signals derived from stimulation of the toll-like receptors. Individuals co-infected with opportunistic microorganisms are particularly affected, promoting the progression of HIV-1 infection. An integral understanding of the behavior of toll-like receptors during viral infections will allow the design of prophylactic and/or therapeutic strategies, based on the modulation of the expression and function of these receptors. Agonists of these receptors can be used effectively to control these viral infections.Los receptores tipo toll son un componente esencial de la respuesta inmune innata y adaptativa, pues se encargan del reconocimiento de los diferentes agentes patógenos y desencadenan respuestas dirigidas a eliminarlos y a desarrollar memoria inmunológica. Durante las infecciones virales se activan diferentes receptores tipo toll que, generalmente, inducen una respuesta inmune protectora pero, también, pueden hacer parte de los mecanismos patogénicos del virus. Una de las infecciones virales en la que los receptores tipo toll participan de esta respuesta dual, es la infección por el VIH-1, en la cual varios de estos receptores se activan para desarrollar respuestas antivirales dirigidas por los interferones tipo 1; pero, la replicación y la diseminación del virus también se favorecen por las señales derivadas de la estimulación de dichos receptores, en particular, por las infecciones asociadas con microorganismos oportunistas, lo cual favorece la progresión de la infección por el VIH-1. Un entendimiento integral del comportamiento de estos receptores durante las infecciones virales, permitirá diseñar estrategias profilácticas o terapéuticas basadas en la modulación de su expresión y función, en particular, utilizando agonistas de estos receptores que sean eficaces en la lucha por el control de las infecciones virales. &nbsp

Efecto inmunomodulador de nanopartículas usadas en nanomedicina

ABSTRACT: Nanoparticles (NP) are structures with a size on the nanometer scale (1 x 10-9 m). Due to their characteristics, their potential use in the fields of biotechnology and biomedicine has grown in recent years with a wide range of applications, such as diagnosis, therapy and regenerative medicine. The immune system is responsible for defending the body against pathogenic organisms and other foreign agents, such as NP, which can be recognized by such system, interact with it and modulate its function inducing immunostimulatory or immunosuppressive effects. The latter could be used as anti-inflammatory therapeutic agents or to treat autoimmune diseases, and those that activate the immune system, as adjuvants in vaccination or enhancers of the immune response in cancer and other human diseases. However, their use in nanomedicine should be submitted to preliminary tests to determine their effects on the immune response before being applied to biological systems. For this reason it is important to know their composition, size and surface characteristics, as well as other physicochemical properties, directly involved in the effects on the immune system. We present an overview about the relationship between the physicochemical characteristics of NP candidates to be used in the biomedical and biotechnological fields and their immunomodulatory activity. Key words: Immunomodulation; Nanomedicine; Nanoparticles.RESUMEN: Las nanopartículas (NP) son estructuras con tamaño en la escala nanométrica (1 x 10-9 m). Por sus características, en los últimos años ha crecido su potencial para usarlas en los campos biotecnológico y biomédico en una amplia gama de aplicaciones, tales como el diagnóstico, la terapia y la medicina regenerativa. El sistema inmunológico es el responsable de la defensa del cuerpo ante organismos patógenos y otros agentes extraños, como las NP, que pueden ser reconocidas por dicho sistema, interactuar con él y modular su función induciendo efectos inmunosupresores o inmunoestimuladores. Las primeras se podrían utilizar como agentes terapéuticos antinflamatorios o para tratar las enfermedades autoinmunes, y las que activan el sistema inmune, como adyuvantes en vacunación o potenciadores de la respuesta inmune en cáncer y otras enfermedades humanas. Sin embargo, su uso en nanomedicina debe estar sujeto a ensayos previos que determinen su efecto en la respuesta inmune antes de aplicarlas a los sistemas biológicos. Por esta razón es importante conocer su composición, tamaño y características superficiales, entre otras propiedades fisicoquímicas, directamente implicadas en los efectos sobre el sistema inmune. Se presenta una visión general de la relación entre las propiedades fisicoquímicas de las NP candidatas para ser usadas en los campos biomédico y biotecnológico y su actividad inmunomoduladora

Nuclear Factor 90, a cellular dsRNA binding protein inhibits the HIV Rev-export function

BACKGROUND: The HIV Rev protein is known to facilitate export of incompletely spliced and unspliced viral transcripts to the cytoplasm, a necessary step in virus life cycle. The Rev-mediated nucleo-cytoplasmic transport of nascent viral transcripts, dependents on interaction of Rev with the RRE RNA structural element present in the target RNAs. The C-terminal variant of dsRNA-binding nuclear protein 90 (NF90ctv) has been shown to markedly attenuate viral replication in stably transduced HIV-1 target cell line. Here we examined a mechanism of interference of viral life cycle involving Rev-NF90ctv interaction. RESULTS: Since Rev:RRE complex formations depend on protein:RNA and protein:protein interactions, we investigated whether the expression of NF90ctv might interfere with Rev-mediated export of RRE-containing transcripts. When HeLa cells expressed both NF90ctv and Rev protein, we observed that NF90ctv inhibited the Rev-mediated RNA transport. In particular, three regions of NF90ctv protein are involved in blocking Rev function. Moreover, interaction of NF90ctv with the RRE RNA resulted in the expression of a reporter protein coding sequences linked to the RRE structure. Moreover, Rev influenced the subcellular localization of NF90ctv, and this process is leptomycin B sensitive. CONCLUSION: The dsRNA binding protein, NF90ctv competes with HIV Rev function at two levels, by competitive protein:protein interaction involving Rev binding to specific domains of NF90ctv, as well as by its binding to the RRE-RNA structure. Our results are consistent with a model of Rev-mediated HIV-1 RNA export that envisions Rev-multimerization, a process interrupted by NF90ctv

Silica nanoparticles induce NLRP3 inflammasome activation in human primary immune cells

RESUMEN: In recent years, the potential use of silica nanoparticles (SiNPs) among different biomedical fields has grown. A deep understanding of the physicochemical properties of nanoparticles (NPs) and their regulation of specific biological responses is crucial for the successful application of NPs. Exposure to NP physicochemical properties (size, shape, porosity, etc.) could result in deleterious effects on cellular functions, including a pro-inflammatory response mediated via activation of the NLRP3 inflammasome. The aim of this study was to evaluate the potential in vitro immunomodulatory effect of 12-nm and 200-nm SiNPs on the expression of pro-inflammatory cytokines and NLRP3 inflammasome components in human primary neutrophils and PBMCs. This study demonstrates that regardless of the size of the nanoparticles, SiNPs induce the production of pro-inflammatory cytokines in a dose-dependent manner. Induced IL-1β production after exposure to SiNPs suggests the involvement of NLRP3 inflammasome components participation in this process. In conclusion, SiNPs induce the production of pro-inflammatory cytokines in a dose-dependent manner. Furthermore, our data suggest that the production and release of IL-1β possibly occurs through the formation of the NLRP3 inflammasome

Stimulation of TLRs, Nod-like receptors and Dectin-1 in neutrophils induces the production of proinflammatory cytokines

ABSTRACT: To evaluate the expression and function of pattern recognition receptors such as Toll-like receptors, RIG-I/MDA5, NOD-like receptors, Dectin-1 and adaptor proteins, in human neutrophils. Methods: Neutrophils from peripheral blood of healthy individuals were purified and cultured in RPMI-1640, in the presence or absence of specific agonists of the receptor of interest. The expression of pattern recognition receptors was determined by RT-PCR and the secretion of proinflammatory cytokines, by ELISA. Results: We observed that neutrophils express diverse patterns recognition receptors and adaptor molecules. Stimulation of TLR4, TLR5 and TLR7/8 induces the production of IL-1β and IL-6, and activation of Dectin-1 leads to secretion of high levels of TNF-α, but low levels of IL-1β and IL-6. Conclusion: Neutrophils express a large number of pattern recognition receptors and their activation leads to the expression of proinflammatory cytokines.RESUMEN: Evaluar la expresión y la función de receptores de reconocimiento de patrones como los de tipo Toll y los de tipo NOD, RIG-I/MDA5, la dectina-1 y moléculas adaptadoras, en neutrófilos humanos. Métodos: a partir de sangre periférica de individuos sanos se purificaron y cultivaron neutrófilos en el medio RMPI-1640, en presencia o ausencia de los agonistas específicos de los receptores de interés. La expresión de los receptores de reconocimiento de patrones se determinó por RT-PCR y la secreción de citocinas proinflamatorias, por ELISA. Resultados: los neutrófilos expresan un amplio espectro de receptores de reconocimiento de patrones y de moléculas adaptadoras. La estimulación de TLR4, TLR5, TLR7/8 induce la secreción de IL-1β e IL-6; la activación de la dectina-1 induce una alta producción de TNF-α, pero bajos niveles de IL-1β e IL-6. Conclusión: los neutrófilos expresan un amplio número de receptores de reconocimiento de patrones y su activación lleva a la expresión de diferentes citocinas proinflamatorias

Immunomodulating effect of nanoparticles used in nanomedicine

RESUMEN: Las nanopartículas (NP) son estructuras con tamaño en la escala nanométrica (1 x 10-9 m). Por sus características, en los últimos años ha crecido su potencial para usarlas en los campos biotecnológico y biomédico en una amplia gama de aplicaciones, tales como el diagnóstico, la terapia y la medicina regenerativa. El sistema inmunológico es el responsable de la defensa del cuerpo ante organismos patógenos y otros agentes extraños, como las NP, que pueden ser reconocidas por dicho sistema, interactuar con él y modular su función induciendo efectos inmunosupresores o inmunoestimuladores. Las primeras se podrían utilizar como agentes terapéuticos antinflamatorios o para tratar las enfermedades autoinmunes, y las que activan el sistema inmune, como adyuvantes en vacunación o potenciadores de la respuesta inmune en cáncer y otras enfermedades humanas. Sin embargo, su uso en nanomedicina debe estar sujeto a ensayos previos que determinen su efecto en la respuesta inmune antes de aplicarlas a los sistemas biológicos. Por esta razón es importante conocer su composición, tamaño y características superficiales, entre otras propiedades fisicoquímicas, directamente implicadas en los efectos sobre el sistema inmune. Se presenta una visión general de la relación entre las propiedades fisicoquímicas de las NP candidatas para ser usadas en los campos biomédico y biotecnológico y su actividad inmunomoduladora.ABSTRACT: Nanoparticles (NP) are structures with a size on the nanometer scale (1 x 10-9 m). Due to their characteristics, their potential use in the fields of biotechnology and biomedicine has grown in recent years with a wide range of applications, such as diagnosis, therapy and regenerative medicine. The immune system is responsible for defending the body against pathogenic organisms and other foreign agents, such as NP, which can be recognized by such system, interact with it and modulate its function inducing immunostimulatory or immunosuppressive effects. The latter could be used as anti-inflammatory therapeutic agents or to treat autoimmune diseases, and those that activate the immune system, as adjuvants in vaccination or enhancers of the immune response in cancer and other human diseases. However, their use in nanomedicine should be submitted to preliminary tests to determine their effects on the immune response before being applied to biological systems. For this reason it is important to know their composition, size and surface characteristics, as well as other physicochemical properties, directly involved in the effects on the immune system. We present an overview about the relationship between the physicochemical characteristics of NP candidates to be used in the biomedical and biotechnological fields and their immunomodulatory activity