Immunomodulatory Response of Toll-like Receptor Ligand-Peptide Conjugates in Food Allergy.

Covalent conjugation of allergens to toll-like receptor (TLR) agonists appears to be a powerful strategy for the development of safety compounds for allergen-specific immunomodulatory response toward tolerance in allergy. In this work, we have synthesized two family of ligands, an 8-oxoadenine derivative as a ligand for TLR7 and a pyrimido[5,4-b]indole as a ligand for TLR4, both conjugated with a T-cell peptide of Pru p 3 allergen, the lipid transfer protein (LTP) responsible for LTP-dependent food allergy. These conjugates interact with dendritic cells, inducing their specific maturation, T-cell proliferation, and cytokine production in peach allergic patients. Moreover, they increased the Treg-cell frequencies in these patients and could induce the IL-10 production. These outcomes were remarkable in the case of the TLR7 ligand conjugated with Pru p 3, opening the door for the potential application of these allergen-adjuvant systems in food allergy immunotherapy.

Peptide Glycodendrimers as Potential Vaccines for Olive Pollen Allergy.

Olive pollen is one of the most important causes of respiratory allergy, with Ole e 1 being the most clinically relevant sensitizing allergen. Peptide-based vaccines represent promising therapeutic approaches, but the use of adjuvants is required to strengthen the weak immunogenicity of small peptides. We propose the use of dendrimeric scaffolds conjugated to the T cell immunodominant epitope of Ole e 1 (OE109-130) for the development of novel vaccines against olive pollen allergy. Four dendrimeric scaffolds containing an ester/ether with nine mannoses, an ester succinimidyl linker with nine N-acetyl-glucosamine units or nine ethylene glycol units conjugated to OE109-130 peptide were designed, and their cytotoxicity, internalization pattern, and immunomodulatory properties were analyzed in vitro. None of the dendrimers exhibited cytotoxicity in humanized rat basophil (RBL-2H3), human bronchial epithelial Calu-3, and human mast LAD2 cell lines. Confocal images indicated that mannosylated glycodendropeptides exhibited lower colocalization with a lysosomal marker. Moreover, mannosylated glycodendropeptides showed higher transport tendency through the epithelial barrier formed by Calu-3 cells cultured at the air-liquid interface. Finally, mannosylated glycodendropeptides promoted Treg and IL10+Treg proliferation and IL-10 secretion by peripheral blood mononuclear cells from allergic patients. Mannosylated dendrimers conjugated with OE109-130 peptide from Ole e 1 have been identified as suitable candidates for the development of novel vaccines of olive pollen allergy.

Human dendritic cell activation induced by a permannosylated dendron containing an antigenic GM3-lactone mimetic.

Vaccination strategies based on dendritic cells (DCs) armed with specific tumor antigens have been widely exploited due the properties of these immune cells in coordinating an innate and adaptive response. Here, we describe the convergent synthesis of the bifunctional multivalent glycodendron 5, which contains nine residues of mannose for DC targeting and one residue of an immunogenic mimetic of a carbohydrate melanoma associated antigen. The immunological assays demonstrated that the glycodendron 5 is able to induce human immature DC activation in terms of a phenotype expression of co-stimulatory molecules expression and MHCII. Furthermore, DCs activated by the glycodendron 5 stimulate T lymphocytes to proliferate in a mixed lymphocytes reaction (MLR).

Glycofullerenes inhibit viral infection.

Water-soluble glycofullerenes based on a hexakis-adduct of [60]fullerene with an octahedral addition pattern are very attractive compounds providing a spherical presentation of carbohydrates. These tools have been recently described and they have been used to interact with lectins in a multivalent manner. Here, we present the use of these glycofullerenes, including new members with 36 mannoses, as compounds able to inhibit a DC-SIGN-dependent cell infection by pseudotyped viral particles. The results obtained in these experiments demonstrate for the first time that these glycoconjugates are adequate to inhibit efficiently an infection process, and therefore, they can be considered as very promising and interesting tools to interfere in biological events where lectins such as DC-SIGN are involved.

Multivalent glycoconjugates as anti-pathogenic agents.

Multivalency plays a major role in biological processes and particularly in the relationship between pathogenic microorganisms and their host that involves protein-glycan recognition. These interactions occur during the first steps of infection, for specific recognition between host and bacteria, but also at different stages of the immune response. The search for high-affinity ligands for studying such interactions involves the combination of carbohydrate head groups with different scaffolds and linkers generating multivalent glycocompounds with controlled spatial and topology parameters. By interfering with pathogen adhesion, such glycocompounds including glycopolymers, glycoclusters, glycodendrimers and glyconanoparticles have the potential to improve or replace antibiotic treatments that are now subverted by resistance. Multivalent glycoconjugates have also been used for stimulating the innate and adaptive immune systems, for example with carbohydrate-based vaccines. Bacteria present on their surfaces natural multivalent glycoconjugates such as lipopolysaccharides and S-layers that can also be exploited or targeted in anti-infectious strategies.

Glycodendritic structures: tools to interact with DC-SIGN

The key role of carbohydrates in many biological events has attracted the interest of the scientific community. This fact has demanded the access to new tools necessary to understand this role and the interaction of carbohydrates with their corresponding receptors, lectins. Glycodendrimers and glycodendritic structures in general, have demonstrated to be very efficient and interesting tools to intervene in those processes where carbohydrates participate. In this review, we discuss the different glycodendritic structures that have been used to interfere with DC-SIGN, a very attractive lectin involved in infection processes and in the regulation of the immune response.

O papel chave dos carboidratos em muitos eventos biológicos tem atraído interesse da comunidade científica. Este fato demonstrou o acesso de novas ferramentas para a compreensão da interação dos carboidratos com seus receptores correspondentes, lectinas. Glicodendrímeros e estruturas glicodendríticas, em geral, mostram-se como ferramentas muito eficientes e interessantes para intervir nos processos em que os carboidratos participam. Nesta revisão, discutimos diferentes estruturas glicodendríticas que têm sido úteis para interferir com DC-SIGN, uma lectina muito atraente envolvida em processos infecciosos e na regulação da resposta imune.

A glycomimetic compound inhibits DC-SIGN-mediated HIV infection in cellular and cervical explant models.

OBJECTIVE: Dendritic cell-specific intercellular adhesion molecule (ICAM)-3 grabbing nonintegrin (DC-SIGN) participates in the initial stages of sexually transmitted HIV-1 infection by recognizing highly mannosylated structures presented in multiple copies on HIV-1 gp120 and promoting virus dissemination. Inhibition of HIV interaction with DC-SIGN thus represents a potential therapeutic approach for viral entry inhibition at the mucosal level. DESIGN: Herein we evaluate the efficacy in inhibiting HIV-1 infection and the potential toxicity of a multimeric glycomimetic DC-SIGN ligand (Dendron 12). METHODS: The ability of Dendron 12 to block HIV-1 infection was assessed in cellular and human cervical explant models. Selectivity of Dendron 12 towards DC-SIGN and langerin was evaluated by surface plasmon resonance studies. ß chemokine production following stimulation with Dendron 12 was also analyzed. Toxicity of the compound was evaluated in cellular and tissue models. RESULTS: Dendron 12 averted HIV-1 trans infection of CD4(+) T lymphocytes in presence of elevated viral loads and prevented HIV-1 infection of human cervical tissues, under conditions mimicking compromised epithelial integrity, by multiple clades of R5 and X4 tropic viruses. Treatment with Dendron 12 did not interfere with the activity of langerin and also significantly elicited the production of the ß chemokines MIP-1α, MIP-1ß and RANTES. CONCLUSION: Dendron 12 thus inhibits HIV-1 infection by competition with binding of HIV to DC-SIGN and stimulation of ß-chemokine production. Dendron 12 represents a promising lead compound for the development of anti-HIV topical microbicides.

Targeting DC-SIGN with carbohydrate multivalent systems.

DC-SIGN (dendritic cell-specific intercellular adhesion molecule-3-grabbing nonintegrin), a C-type lectin mainly present at the surface of immature dendritic cells, plays a relevant role activating and tailoring adaptive immune responses against different pathogens. This lectin recognizes, in a multivalent and calcium-dependent manner, highly glycosylated proteins present at the surface of pathogens. Several groups have devoted remarkable efforts to develop carbohydrate multivalent compounds targeting this lectin to modulate its role in pathogen capture and in the generation of an immune response. Most of these approaches have been based on mannosylation of immunogenic proteins such as ovalbumin but new strategies have been envisaged to achieve these goals. Although mannosylated systems cannot provide the required selectivity for a specific lectin at dendritic cells, fucosylated compounds have overcome this problem specifically targeting DC-SIGN and avoiding interferences with other lectins, such as the mannose receptor. The use of these carbohydrate multivalent compounds to target DC-SIGN can be considered a promising strategy to inhibit pathogen entry and to develop new vaccines against pathogen infection or cancer. New studies are required to provide more insights into the complex immune pathway involving DC-SIGN.

Analysis of recent pediatric orthotopic liver transplantation outcomes indicates that allograft type is no longer a predictor of survivals.

Two strategies to increase the donor allograft pool for pediatric orthotopic liver transplantation (OLT) are deceased donor segmental liver transplantation (DDSLT) and living donor liver transplantation (LDLT). The purpose of this study is to evaluate outcomes after use of these alternative allograft types. Data on all OLT recipients between February 2002 and December 2004 less than 12 years of age were obtained from the United Network for Organ Sharing database. The impact of allograft type on posttransplant survivals was assessed. The number of recipients was 1260. Of these, 52% underwent whole liver transplantation (WLT), 33% underwent DDSLT, and 15% underwent LDLT. There was no difference in retransplantation rates. Immediate posttransplant survivals differed, with WLT patients having improved 30-day patient survivals compared to DDSLT and LDLT patients (P = 0.004). Although unadjusted 1-year patient survivals were better for WLT versus DDSLT (P = 0.01), after risk adjustment, 1-year patient survivals for WLT (94%), DDSLT (91%), and LDLT (93%) were similar (P values > 0.05). Unadjusted allograft survivals were better for WLT and LDLT in comparison with DDSLT (P = 0.009 and 0.018, respectively); however, after adjustment, these differences became nonsignificant (all P values > 0.05). For patients < or = 2 years of age (n = 833), the adjusted 1-year patient and allograft survivals were also similar (all P values > 0.05). In conclusion, in the current era of pediatric liver transplantation, WLT recipients have better immediate postoperative survivals. By 1 year, adjusted patient and allograft survivals are similar, regardless of the allograft type.

Doble choque eléctrico secuencial transtorácico para la fibrilación auricular refractaria / Double sequential electrical transthoracic shocks for refractory atrial fibrillation

Antecedentes: Estudios clínicos han mostrado que el éxito de la cardioversión transtorácica en fibrilación auricular depende de alcanzar un flujo de corriente adecuado al corazón y que es dependiente de la impedancia transtorácica. Cuando múltiples cardioversiones convencionales fallan para restaurar el ritmo sinusal en pacientes con fibrilación auricular el doble choque secuencial transtorácico puede ser una alternativa. Métodos y resultados: 21 pacientes consecutivos con fibrilación auricular paroxística o persistente refractaria al menos a dos choques monofásicos con energía inicial alta 360 J ó 200-300 y 360 J recibieron choques secuenciales con 720 J mediante dos desfibriladores. Edad media 64 ± 11 años y peso medio 97 ± 19 kg (intervalos, 49 a 112). La evolución de la fibrilación auricular fue < 3 meses en el 76%. La hipertensión presente en 38% y ausencia de cardiopatía en 33%. El tamaño medio de la aurícula izquierda fue 4.5 ± 0.7 cm (intervalos, 3.5 a 6.0). El ritmo sinusal se alcanzó en 19 (90.4%), incluyendo 2 casos refractarios a choques bifásicos con una mediana de 1,050 J (intervalos, 660 a 1,440 J) sin complicaciones mayores. El análisis multivariable identificó a la duración de la fibrilación auricular, > 90 días (RR 0.98, IC 0.95-0.98 p = 0.02) y al peso corporal, 101 ± 11 kg (RR 0.64, IC 0.46-0.90 p = 0.01) como variables independientes asociadas con el fracaso de la cardioversión. El peso corporal, p = 0.002 fue el predictor univariable de cardioversión no exitosa. La cardioversión de alta energía no causa daño miocárdico evidenciado por estimación con troponina T. Conclusión: Para la fibrilación auricular refractaria a la cardioversión eléctrica convencional el doble choque secuencial transtorásico representa una alternativa segura y altamente eficaz y puede tener una aplicabilidad general.

Background: Clinical studies have shown that transthoracic cardioversión of atrial fibrillation is dependent on achieving adequate current flow to the heart, which is dependent on transthoracic impedance. When multiple standard cardioversión fails to restore sinus rhythm in patients with atrial fibrillation the double sequential transthoracic shock may be an alternative. Methods and results: Twenty one consecutive patients with paroxysmal or persistent atrial fibrillation refractory to at least two initial high energy 360 J or 200-300 and 360 J monophasic shocks underwent double sequential shocks with 720 J by means two defibrillators. Mean age was 64 ± 11 years and mean weight 97 ± 19 kg (range, 49 to 112). Duration of atrial fibrillation was present < 3 months in 76%. Arterial hypertension was present in 38% and lone atrial fibrillation in 33%. Mean left atrial size was 4.5 ± 0.7 cm (range, 3.5 to 6.0). Sinus rhythm was achieved in 19 (90.4%). Two refractory to biphasic shocks with a median 1,050 J (range, 660 to 1,440 J) without major complications. Multivariate analysis identified duration of atrial fibrillation, > 90 days (RR 0.96, Cl 0.95-0.98 p = 0.02) and body weight, 101 ± 11 kg (RR 0.64, Cl 0.46-0.90 p = 0.01) variables independently associated with cardioversión unsuccessful. Patient weight, p = 0.002 was the univariate predictor of unsuccessful cardioversión. High energy cardioversión does not cause cardiac damage evidenced from cardiac troponin T estimation. Conclusion: For refractory atrial fibrillation to conventional cardioversión double sequential transthoracic shocks represents a safe and highly efficacious alternative and may have a general applicability.

Gold glyconanoparticles as new tools in antiadhesive therapy.

Gold glyconanoparticles (GNPs) have been prepared as new multivalent tools that mimic glycosphingolipids on the cell surface. GNPs are highly soluble under physiological conditions, stable against enzymatic degradation and nontoxic. Thereby GNPs open up a novel promising multivalent platform for biological applications. It has recently been demonstrated that specific tumor-associated carbohydrate antigens (glycosphingolipids and glycoproteins) are involved in the initial step of tumor spreading. A mouse melanoma model was selected to test glyconanoparticles as possible inhibitors of experimental lung metastasis. A carbohydrate-carbohydrate interaction is proposed as the first recognition step for this process. Glyconanoparticles presenting lactose (lacto-GNPs) have been used successfully to significantly reduce the progression of experimental metastasis. This result shows for the first time a clear biological effect of lacto-GNPs, demonstrating the potential application of this glyconanotechnology in biological processes.

Mannosyl glycodendritic structure inhibits DC-SIGN-mediated Ebola virus infection in cis and in trans.

We have designed a glycodendritic structure, BH30sucMan, that blocks the interaction between dendritic cell-specific intercellular adhesion molecule 3-grabbing nonintegrin (DC-SIGN) and Ebola virus (EBOV) envelope. BH30sucMan inhibits DC-SIGN-mediated EBOV infection at nanomolar concentrations. BH30sucMan may counteract important steps of the infective process of EBOV and, potentially, of microorganisms shown to exploit DC-SIGN for cell entry and infection.

Cardioversión Cardiológica con propafenona intravenosa en fibrilación auricular / Intravenous propafenone for the conversion of atrial fibrillation

La eficacia y seguridad de propafenona por vía intravenosa para la cardioversión de fibrilación auricular a ritmo sinusal de reciente inicio y/o crónica fueron evaluadas en 46 pacientes, 40 con fibrilación auricular con o sin cardiopatía estructural (edad media 63 + 14 años) y 6 pacientes con fibrilación auricular relacionada a síndrome de Wolff-Parkinson-White. (edad media 34.8 +13 años). El tratamiento con propafenona intravenosa fue administrado a razón de 2 mg/kg en 15 minutos con monitoreo electrocardiográfico continuo. En 28 de 32 (87.5 por ciento) pacientes con fibritación auricular paroxística y/o de reciente inicio se restauró un ritmo sinusal estable dentro de la primera hora (media 17 + 11 minutos) y en sólo 3 de 8 (37.5 por ciento) de los casos con fibrilación auricular crónica (p<0.05). La conversión a ritmo sinusal se obtuvo en 5 de 6 (83.3 por ciento) pacientes con fibrilación auricular relacionada con preexcitación ventricular, tiempo medio de 21 + 12 minutos. La propafenona tuvo un efecto adicional al reducir la frecuencia ventricular media 141 + 21 a 102 + 15 latidos por minuto (p < 0.05) y una prolongación del intervalo R-R preexcitado más corto, media 231.6 + 27.8 a 355.8 + 37.2 milisegundos (p < 0.001) en los casos con preexcitación ventricular. Un paciente con valvulopatía mitral reumática y FE 40 por ciento desarrolló trastornos transitorios de conducción intraventricular, mareo e hipotensión arterial. La propafenona intravenosa es un agente efectivo y seguro para la cardioversión a ritmo sinusal de la fibrilación auricular paroxística y/o de reciente inicio y tiene una utilidad más limitada en la fibrilación auricular permanente.