Gerhild Angyalosi

Novel Hyperbranched Glycomimetics Recognized by the Human Mannose Receptor: Quinic or Shikimic Acid Derivatives as Mannose Bioisosteres

The mannose receptor mediates the internalization of a wide range of molecules or microorganisms in a pattern recognition manner. Therefore, it represents an attractive entry for specific drug, gene, or antigen delivery to macrophages and dendritic cells. In an attempt to design novel effective synthetic mannose receptor ligands, quinic and shikimic acid were selected as putative mannose mimics on the basis of X‐ray crystallographic data from the related rat mannose‐binding lectin. As the mannose receptor preferentially binds to molecules displaying several sugar residues, fluorescein‐labeled cluster quinic and shikimic acid derivatives with valencies of two to eight were synthesized. Their mannose receptor mediated uptake was assayed on monocyte‐derived human dendritic cells by cytofluorimetric analysis. Mannose‐receptor specificity was further assessed by competitive inhibition assays with mannan, by confocal microscopy analysis, and by expression of the mannose receptor in transfected Cos‐1 cells. Constructs derived from both quinic and shikimic acid were efficiently recognized by the mannose receptor with an optimum affinity for the molecules with a valency of four. As a result, commercially available quinic and shikimic acids appear as stable mannose bioisosteres, which should prove valuable tools for specific cell delivery.

Grafting of synthetic mannose receptor-ligands onto onion vectors for human dendritic cells targetingElectronic supplementary information (ESI) available: full experimental details. See http://www.rsc.org/suppdata/cc/b2/b206980f/

A practical preparation of onion vesicles targeted to dendritic cells involves the grafting of mannose-mimetic clusters, bearing a hydrazino group, onto the surface of onion vesicles containing an aldehyde functionalized lipid.

Synthesis and mannose receptor-mediated uptake of clustered glycomimetics by human dendritic cells: Effect of charge

Effect of charge and shape of multivalent lysine-based cluster glycomimetics on their mannose receptor-mediated uptake by human dendritic cells has been evaluated: The capture is strongly affected by the shape of the ligands. The effect of charge is less pronounced although positive charges on the ligands seem to favor non-specific endocytosis capture.

HLA Class II Polymorphism Influences Onset and Severity of Pathology in Schistosoma mansoni-Infected Transgenic Mice

ABSTRACT Genetic factors that might influence susceptibility or resistance in naive individuals and early-stage pathology in schistosomiasis are difficult to study in clinical trials, since in areas where the disease is endemic the first contact with the parasite occurs most often at very early ages. Therefore, four strains (DR1.Aβ°, DR2.Aβ°, DQ8.Aβ°, and DQ6.Aβ°) of major histocompatibility complex class II-deficient mice (Aβ°), transgenic for different HLA alleles, have been used to evaluate the potential role of HLA class II polymorphism in the onset of the infection by Schistosoma mansoni. The survival rates and parasitological and immunological parameters after infection were evaluated and compared against the control values obtained with Aβ° mice. All four mouse strains used in this study were able to generate a specific immune response against S. mansoni antigens (cytokine production and antibody production). However, only mice expressing DR alleles survived until the chronic stage of the infection and were able to mount protective granulomatous response avoiding hepatic damage, presenting predominant gamma interferon production. In contrast, strains expressing DQ alleles revealed an impairment in generating effective granulomas, resulting in earlier death, which was associated with an impaired hepatic granulomatous response and liquefactic necrosis, reflecting the influence of HLA polymorphism in the establishment of protective response in the early stage of infection.

Evidences of conformational changes in class II Major Histocompatibility Complex molecules that affect the immunogenicity.

The N-terminal part of class II-associated invariant chain peptide (CLIP) is assumed to interact with an accessory peptide-binding site on the class II Major Histocompatibility Complex (MHC) molecule, and promote a conformational modification. We have linked this immunoregulatory segment (residues 81-88) to the N-terminus of the influenza hemagglutinin (HA) 307-319 epitope in order to evaluate relationships between the MHC conformational changes and their implication in immune responses. Our chimeric peptide, named CLIP-HA, bind with the same affinity to class II HLA-DR1 molecules as the HA peptide, and is normally recognized by HA-specific T cells. Interestingly, the presence of the N-terminal CLIP region enhances the rate of association to soluble DR1 molecules but prevents the formation of SDS-resistant complexes. These features suggest the existence of HLA-DR1 conformational changes induced by the chimeric peptide. Furthermore, while in vitro HA and CLIP-HA peptides associated to DR1 could not be differentiated based on T-cell recognition, in vivo the CLIP residues strongly impaired the immunogenicity of HA epitope as assessed in HLA-DR1 transgenic mice. Our study demonstrates for the first time that MHC conformational changes, revealed at molecular level, may influence the immunogenicity.