Single-Walled Carbon Nanohorns as Promising Nanotube-Derived Delivery Systems to Treat Cancer

Cancer has become one of the most prevalent diseases worldwide, with increasing incidence in recent years. Current pharmacological strategies are not tissue-specific therapies, which hampers their efficacy and results in toxicity in healthy organs. Carbon-based nanomaterials have emerged as promising nanoplatforms for the development of targeted delivery systems to treat diseased cells. Single-walled carbon nanohorns (SWCNH) are graphene-based horn-shaped nanostructure aggregates with a multitude of versatile features to be considered as suitable nanosystems for targeted drug delivery. They can be easily synthetized and functionalized to acquire the desired physicochemical characteristics, and no toxicological effects have been reported in vivo followed by their administration. This review focuses on the use of SWCNH as drug delivery systems for cancer therapy. Their main applications include their capacity to act as anticancer agents, their use as drug delivery systems for chemotherapeutics, photothermal and photodynamic therapy, gene therapy, and immunosensing. The structure, synthesis, and covalent and non-covalent functionalization of these nanoparticles is also discussed. Although SWCNH are in early preclinical research yet, these nanotube-derived nanostructures demonstrate an interesting versatility pointing them out as promising forthcoming drug delivery systems to target and treat cancer cells

Nanoparticles to Target and Treat Macrophages:The Ockham's Concept?

Nanoparticles are nanomaterials with three external nanoscale dimensions and an average size ranging from 1 to 1000 nm. Nanoparticles have gained notoriety in technological advances due to their tunable physical, chemical, and biological characteristics. However, the administration of functionalized nanoparticles to living beings is still challenging due to the rapid detection and blood and tissue clearance by the mononuclear phagocytic system. The major exponent of this system is the macrophage. Regardless the nanomaterial composition, macrophages can detect and incorporate foreign bodies by phagocytosis. Therefore, the simplest explanation is that any injected nanoparticle will be probably taken up by macrophages. This explains, in part, the natural accumulation of most nanoparticles in the spleen, lymph nodes, and liver (the main organs of the mononuclear phagocytic system). For this reason, recent investigations are devoted to design nanoparticles for specific macrophage targeting in diseased tissues. The aim of this review is to describe current strategies for the design of nanoparticles to target macrophages and to modulate their immunological function involved in different diseases with special emphasis on chronic inflammation, tissue regeneration, and cancer

Differential effect of amphetamine over the corticotropin-releasing factor CRF2 receptor, the orexin OX1 receptor and the CRF2-OX1 heteroreceptor complex

Stress is one of the factors underlying drug seeking behavior that often goes in parallel with loss of appetite. We here demonstrate that orexin 1 receptors (OX1R) may form complexes with the corticotropin releasing factor CRF2 receptor. Two specific features of the heteromer were a cross-antagonism and a blockade by CRF2 of OX1R signaling. In cells expressing one of the receptors, agonist-mediated signal transduction mechanisms were potentiated by amphetamine. Sigma 1 (σ1) and 2 (σ2) receptors are targets of drugs of abuse and, despite sharing a similar name, the two receptors are structurally unrelated and their physiological role is not known. We here show that σ1 receptors interact with CRF2 receptors and that σ2 receptors interact with OX1R. Moreover, we show that amphetamine effect on CRF2 receptors was mediated by σ1R whereas the effect on OX1 receptors was mediated by σ2R. Amphetamine did potentiate the negative cross-talk occurring within the CRF2-OX1 receptor heteromer context, likely by a macromolecular complex involving the two sigma receptors and the two GPCRs. Finally, in vivo microdialysis experiments showed that amphetamine potentiated orexin A-induced dopamine and glutamate release in the ventral tegmental area (VTA). Remarkably, the in vivo orexin A effects were blocked by a selective CRF2R antagonist. These results show that amphetamine impacts on the OX1R-, CRF2R- and OX1R/CRF2R-mediated signaling and that cross-antagonism is instrumental for in vivo detection of GPCR heteromers

Cocaine Effects on Dopaminergic Transmission Depend on a Balance between Sigma-1 and Sigma-2 Receptor Expression.

gma σ1 and σ2 receptors are targets of cocaine. Despite sharing a similar name, the two receptors are structurally unrelated and their physiological role is unknown. Cocaine increases the level of dopamine, a key neurotransmitter in CNS motor control and reward areas. While the drug also affects dopaminergic signaling by allosteric modulations exerted by σ1R interacting with dopamine D1 and D2 receptors, the potential regulation of dopaminergic transmission by σ2R is also unknown. We here demonstrate that σ2R may form heteroreceptor complexes with D1 but not with D2 receptors. Remarkably σ1, σ2, and D1 receptors may form heterotrimers with particular signaling properties. Determination of cAMP levels, MAP kinase activation and label-free assays demonstrate allosteric interactions within the trimer. Importantly, the presence of σ2R induces bias in signal transduction as σ2R ligands increase cAMP signaling whereas reduce MAP kinase activation. These effects, which are opposite to those exerted via σ1R, suggest that the D1 receptor-mediated signaling depends on the degree of trimer formation and the differential balance of sigma receptor and heteroreceptor expression in acute versus chronic cocaine consumption. Although the physiological role is unknown, the heteroreceptor complex formed by σ1, σ2, and D1 receptors arise as relevant to convey the cocaine actions on motor control and reward circuits and as a key factor in acquisition of the addictive habit. KEYWORDS: ERK1/2 phosphorylation; acute; addiction; cAMP; chronic; dopamine D1 and D2 receptors; label-free; signalin

Brief Research Report: Virus-Specific Humoral Immunity at Admission Predicts the Development of Respiratory Failure in Unvaccinated SARS-CoV-2 Patients

Erratum for Brief Research Report: Virus-Specific Humoral Immunity at Admission Predicts the Development of Respiratory Failure in Unvaccinated SARS-CoV-2 Patients. Tajuelo A, Carretero O, García-Ríos E, López-Siles M, Cano O, Vázquez M, Más V, Rodríguez-Goncer I, Lalueza A, López-Medrano F, Juan RS, Fernández-Ruiz M, Aguado JM, McConnell MJ, Pérez-Romero P. Front Immunol. 2022 Apr 25;13:878812. doi: 10.3389/fimmu.2022.878812. eCollection 2022. PMID: 35547738 Free PMC article.Introduction: There is robust evidence indicating that the SARS-CoV-2-specific humoral response is associated with protection against severe disease. However, relatively little data exist regarding how the humoral immune response at the time of hospital admission correlates with disease severity in unimmunized patients. Our goal was toidentify variables of the humoral response that could potentially serve as prognostic markers for COVID-19 progressionin unvaccinated SARS-CoV-2 patients. Methods: A prospective cross-sectional study was carried out in a cohort of 160 unimmunized, adult COVID-19 patients from the Hospital Universitario 12Octubre. Participants were classified into four clinical groups based on disease severity: non-survivors with respiratory failure (RF), RF survivors, patients requiring oxygen therapy and those not receiving oxygen therapy. Serum samples were taken on admission and IgM, IgG, IgG subclass antibody titers were determined by ELISA, and neutralizing antibody titersusing a surrogate neutralization assay. The differences in the antibody titers between groups and the association between the clinical and analytical characteristics of the patients and the antibody titers were analyzed. Results: Patients that developed RF and survived had IgM titers that were 2-fold higher than non-survivors (p = 0.001), higher levels of total IgG than those who developed RF and succumbed to infection (p< 0.001), and than patients who required oxygen therapy (p< 0.05), and had 5-fold higher IgG1 titers than RF non-survivors (p< 0.001) and those who needed oxygen therapy (p< 0.001), and 2-fold higher than patients that did not require oxygen therapy during admission (p< 0.05). In contrast, RF non-survivorshad the lowest neutralizing antibodylevels, which were significantly lower compared those with RF that survived (p = 0.03). A positive correlation was found between IgM, total IgG, IgG1 and IgG3 titers and neutralizing antibody titers in the total cohort (p ≤ 0.0036). Conclusions: We demonstrate that patients with RF that survived infection had significantly higher IgM, IgG, IgG1 and neutralizing titers compared to patients with RF that succumb to infection, suggesting that using humoral response variables could be used as a prognostic marker for guiding the clinical management of unimmunized patients admitted to the hospital for SARS-CoV-2 infection.This work was supported by Mutua Madrileña Foundation (2020/0056) “Plan Nacional de I+D+I” and Instituto de Salud Carlos III (COVID-19 Research Call COV20/00181 and COV20_00679), Subdirección General de Redes y Centros de Investigación Cooperativa, Spanish Ministry of Science and Innovation, Spanish Network for Research in Infectious Diseases (REIPI RD16/0016) - co-financed by the European Development Regional Fund (EDRF) and the European Social Fund (ESF) "A way to achieve Europe- The ESF invests in your future". Red de Enfermedades Infecciosas (CIBERINFEC), CB21/13/00079. EG-R is supported by the Sara Borrell Program (CD18CIII/00007), MLS is supported by the Sara Borrell Program (CD17CIIII/00017), Instituto de Salud Carlos III, Ministerio de Ciencia, Innovación y Universidades., and AT is supported by the Garantía Juvenil Program of the Comunidad Autonoma de Madrid. IRG holds a research training contract “Río Hortega” (CM19/00163) and MFR a research contract “Miguel Servet” (CP18/00073), both from the Instituto de Salud Carlos III, Spanish Ministry of Science and Innovation.S

Expert panel consensus recommendations for diagnosis and treatment of secondary osteoporosis in children

Background: Osteoporosis incidence in children is increasing due to the increased survival rate of patients suffering from chronic diseases and the increased use of drugs that can damage bones. Recent changes made to the definition of childhood osteoporosis, along with the lack of guidelines or national consensuses regarding its diagnosis and treatment, have resulted in a wide variability in the approaches used to treat this disease. For these reasons, the Osteogenesis Imperfecta and Childhood Osteoporosis Working Group of the Spanish Society of Pediatric Rheumatology has sounded the need for developing guidelines to standardize clinical practice with regard to this pathology. Methods: An expert panel comprised of 6 pediatricians and 5 rheumatologists carried out a qualitative literature review and provided recommendations based on evidence, when that was available, or on their own experience. The level of evidence was determined for each section using the Oxford Centre for Evidence-based Medicine (CEBM) system. A Delphi survey was conducted for those recommendations with an evidence level of IV or V. This survey was sent to all members of the SERPE. All recommendations that had a level of agreement higher or equal to 70% were included. Results: Fifty-one recommendations, categorized into eight sections, were obtained. Twenty-four of them presented an evidence level 4 or 5, and therefore a Delphi survey was conducted. This was submitted electronically and received a response rate of 40%. All recommendations submitted to the Delphi round obtained a level of agreement of 70% or higher and were therefore accepted. Conclusion: In summary, we present herein guidelines for the prevention, diagnosis and treatment of secondary childhood osteoporosis based on the available evidence and expert clinical experience. We believe it can serve as a useful tool that will contribute to the standardization of clinical practice for this pathology. Prophylactic measures, early diagnosis and a proper therapeutic approach are essential to improving bone health, not only in children and adolescents, but also in the adults they will become in the future

Significant role of the truncated Ghrelin Receptor GHS-1Rb in Ghrelin-induced signaling in neurons

The truncated non-signaling ghrelin receptor GHS-R1b has been suggested to simply exert a dominant negative role in the trafficking and signaling of the full and functional ghrelin receptor GHS-R1a. Here we reveal a more complex modulatory role of GHS-R1b. Differential co-expression of GHS-R1a and GHS-R1b, both in HEK-293T cells and in striatal and hippocampal neurons in culture, demonstrates that GHS-R1b acts as a dual modulator of GHS-R1a function: low relative GHS-R1b expression potentiates and high relative GHS-R1b expression inhibits GHS-R1a function by facilitating GHS-R1a trafficking to the plasma membrane and by exerting a negative allosteric effect on GHS-R1a signaling, respectively. We found a preferential Gi/o-coupling of the GHS-R1a-GHS-R1b complex in HEK-293T cells and, unexpectedly, a preferential Gs/olf coupling in both striatal and hippocampal neurons in culture. A dopamine D1 receptor (D1R) antagonist blocked ghrelin-induced cAMP accumulation in striatal but not hippocampal neurons, indicating the involvement of D1R in the striatal GHS-R1a-Gs/olf coupling. Experiments in HEK-293T demonstrated that D1R co-expression promotes a switch in GHS-R1a-G protein coupling, from Gi/o to Gs/olf, but only upon co-expression of GHS-R1b. Furthermore, resonance energy transfer experiments showed that D1R interacts with GHS-R1a, but only in the presence of GHS-R1b. Therefore, GHS-R1b not only determines the efficacy of ghrelin-induced GHS-R1a-mediated signaling, but also determines the ability of GHS-R1a to form oligomeric complexes with other receptors promoting profound qualitative changes in ghrelin-induced signaling

Singular Location and Signaling Profile of Adenosine A2A-Cannabinoid CB1 Receptor Heteromers in the Dorsal Striatum

The dorsal striatum is a key node for many neurobiological processes such as motor activity, cognitive functions, and affective processes. The proper functioning of striatal neurons relies critically on metabotropic receptors. Specifically, the main adenosine and endocannabinoid receptors present in the striatum, ie, adenosine A2A receptor (A2AR) and cannabinoid CB1 receptor (CB1R), are of pivotal importance in the control of neuronal excitability. Facilitatory and inhibitory functional interactions between striatal A2AR and CB1R have been reported, and evidence supports that this cross-talk may rely, at least in part, on the formation of A2AR-CB1R heteromeric complexes. However, the specific location and properties of these heteromers have remained largely unknown. Here, by using techniques that allowed a precise visualization of the heteromers in situ in combination with sophisticated genetically-modified animal models, together with biochemical and pharmacological approaches, we provide a high resolution expression map and a detailed functional characterization of A2AR-CB1R heteromers in the dorsal striatum. Specifically, our data unveil that the A2AR-CB1R heteromer (i) is essentially absent from corticostriatal projections and striatonigral neurons, and, instead, is largely present in striatopallidal neurons, (ii) displays a striking G protein-coupled signaling profile, where co-stimulation of both receptors leads to strongly reduced downstream signaling, and (iii) undergoes an unprecedented dysfunction in Huntington’s disease, an archetypal disease that affects striatal neurons. Altogether, our findings may open a new conceptual framework to understand the role of coordinated adenosine-endocannabinoid signaling in the indirect striatal pathway, which may be relevant in motor function and neurodegenerative diseases

Implicacion estructural y funcional de heterómeros de receptores acoplados a proteínas G de relevancia en adicción, enfermedad de Huntington y cáncer

[spa] La oligomerización es un proceso común en la biología de los receptores de membrana, compartida por los GPCRs. Los GPCRs constituyen aproximadamente un 45% de las dianas de los fármacos comercializados en la actualidad y siguen siendo el foco principal de la investigación biomédica y de los programas de desarrollo de nuevos fármacos. Aún así, el problema clave sigue siendo la falta de selectividad de los ligandos ortostéricos y la gran variedad de procesos que se ven modulados por la estimulación de un mismo GPCR dependiendo de su localización o interacción con otros receptores o proteínas. Los heterómeros de receptores se consideran un nuevo tipo de diana farmacológica por su posible especificidad de localización y por sus características bioquímicas y funcionales demostrablemente diferentes a las de sus componentes individuales, entre ellas las modulaciones alostéricas. El alosterismo puede ser debido a varias circunstancias entre las que destacan interacciones entre los protómeros del complejo y entre éstos y las proteínas G. Las consecuencias a nivel farmacológico y funcional son el reconocimiento diferencial de ligandos y la modulación del tráfico intracelular y del acoplamiento a proteínas G. El sistema orexinérgico es un buen ejemplo de sistema implicado en un amplio abanico de procesos fisiológicos y fisiopatológicos, desde el control de la ingesta y la regulación de los estados de sueño/vigilia a la regulación neuroendocrina y la participación en los mecanismos moleculares de adicción a drogas. La oligomerización de GPCRs constituye un proceso de regulación de orden superior poco explorado en el caso del receptor OX1 pero que se sugiere de gran relevancia para explicar los efectos moduladores de las orexinas. En esta Tesis se ha descrito por primera vez la formación de heterodímeros entre los receptores OX1, GHS-R1a y LEP y del heterotrímero LEP-GHS-R1a-OX1 en un sistema de expresión heteróloga, y se ha obtenido evidencia de la expresión del complejo heterotrimérico en neuronas hipotalámicas de rata. Estos resultados sugieren un papel importante de la oligomerización en la mediación de la respuesta combinada a señales orexigénicas y anorexigénicas originadas tanto a nivel central como periférico. En esta Tesis se describe también por primera vez la formación del heterómero de receptores CRF2-OX1 y su interacción con los receptores σ. El balance σ1/σ2 y la expresión de los heterómeros OX1/CRF2 en una célula determinada condicionan el efecto de la anfetamina y la señalización inducida por orexina y CRF. El sistema cannabinoide desempeña, asimismo, un marcado papel modulador en múltiples procesos fisiológicos y su desregulación se asocia con alteraciones patológicas, desde enfermedades neurodegenerativas a procesos de inflamación, desórdenes cardiovasculares y cáncer. La actividad neuroprotectora de los cannabinoides se ha descrito tanto in vivo como in vitro y hoy en día se investiga su gran potencial terapéutico en enfermedades neurodegenerativas. En esta Tesis se ha identificado una localización preferente del heterómero de receptores A2A-CB1 en proyecciones GABAérgicas del estriado dorsal, neuronas afectadas de manera paradigmática en la enfermedad de Huntington, y una disminución de la expresión del complejo en estadios avanzados de la enfermedad. Los resultados sugieren la importancia de funciones específicas asociadas a la formación de dicho complejo que se ven afectadas negativamente en estadios tardíos de la progresión de la enfermedad. La capacidad protectora de los cannabinoides se observa también en procesos oncogénicos. Los receptores CB2 y GPR55 se encuentran sobre-expresados en diversos tipos de tumores humanos y se ha descrito su implicación en el control del destino de las células tumorales. En esta Tesis se ha descrito la formación de heterodímeros de receptores CB2-GPR55 en células cancerígenas y cómo la modulación de estos complejos puede modificar la actividad anti-tumoral de los cannabinoides in vivo.[eng] The ‘receptor heteromer’ concept, in which receptors of the same and different gene families can combine among themselves to generate new and unique biochemical and functional characteristics, is becoming widely accepted for GPCRs and constitutes an emerging area in the field of GPCR cell signaling. Receptor heteromers must be understood as dimeric or higher order molecular entities that are the result of combinatorial evolution and they constitute novel therapeutic targets due to their possible specific location and their unique biochemical and functional properties, such as the allosteric modulations. Allosterism, as a result of interactions between individual protomers in the oligomer or between them and G proteins, can cause differential ligand binding and/or the modulation of intracellular trafficking and G protein coupling. In this context, the results here presented show the relevant role of GPCR oligomerization in different pathological processes such as addiction, Huntington’s disease and cancer, focusing on orexinergic and cannabinoid systems as modulatory systems involved in a wide range of physiological and pathophysiological processes. Here we describe for the first time the formation of heterodimers between LEP, GHS- R1A and OX1 receptors in a heterologous system, and the formation of heterotrimers involving the three receptors in hypothalamic primary cultures, suggesting an important role of these complexes in the response to a combination of different orexigenic and anorexigenic signals originated both centrally and peripherally. We demonstrate the formation of CRF2-OX1 receptor heteromers in a heterologous system and in the rat VTA. These receptors can interact also with sigma receptors, and the final balance between σ1/σ2 receptors and the expression of CRF2-OX1 receptor heteromers in a particular cell determines the effect of amphetamine and the signaling induced by orexin and CRF. Here we also identified the precise location of CB1-A2A receptor heteromers in the GABAergic projections in the dorsal striatum, that these complexes possess unique signaling properties and undergo an unprecedented dysfunction in Huntington’s disease, an archetypal disease that affects striatal neurons. Finally, we show that CB2R and GPR55 form receptor heteromers in cancer cells, that these structures possess unique signaling properties and that the modulation of these heteromers can modify the antitumoral activity of cannabinoids in vivo