Biophysical characterization and stability of modified IgG1 antibodies with different hexamerization propensities

The hexamerization of natural, human IgG antibodies after cell surface antigen binding can induce activation of the classical complement pathway. Mutations stimulating Fc domain-mediated hexamerization can potentiate complement activation and induce the clustering of cell surface receptors, a finding that was applied to different clinically investigated antibody therapeutics. Here, we biophysically characterized how increased self-association of IgG1 antibody variants with different hexamerization propensity may impact their developability, rather than functional properties. Self-Interaction Chromatography, Dynamic Light Scattering and PEG-induced precipitation showed that IgG variant self-association at neutral pH increased in the order wild type (WT) < E430G < E345K < E345R < E430G-E345R-S440Y, consistent with functional activity. Self-association was strongly pH-dependent, and single point mutants were fully monomeric at pH 5. Differential Scanning Calorimetry and Fluorimetry showed that mutation E430G decreased conformational stability. Interestingly, heat-induced unfolding facilitated by mutation E430G was reversible at 60°C, while a solvent-exposed hydrophobic mutation caused irreversible aggregation. Remarkably, neither increased dynamic self-association propensity at neutral pH nor decreased conformational stability substantially affected the stability of concentrated variants E430G or E345K during storage for two years at 2-8°C. We discuss how these findings may inform the design and development of IgG-based therapeutics

Biophysical characterization and stability of modified IgG1 antibodies with different hexamerization propensities

The hexamerization of natural, human IgG antibodies after cell surface antigen binding can induce activation of the classical complement pathway. Mutations stimulating Fc domain-mediated hexamerization can potentiate complement activation and induce the clustering of cell surface receptors, a finding that was applied to different clinically investigated antibody therapeutics. Here, we biophysically characterized how increased self-association of IgG1 antibody variants with different hexamerization propensity may impact their developability, rather than functional properties. Self-Interaction Chromatography, Dynamic Light Scattering and PEG-induced precipitation showed that IgG variant self-association at neutral pH increased in the order wild type (WT) < E430G < E345K < E345R < E430G-E345R-S440Y, consistent with functional activity. Self-association was strongly pH-dependent, and single point mutants were fully monomeric at pH 5. Differential Scanning Calorimetry and Fluorimetry showed that mutation E430G decreased conformational stability. Interestingly, heat-induced unfolding facilitated by mutation E430G was reversible at 60°C, while a solvent-exposed hydrophobic mutation caused irreversible aggregation. Remarkably, neither increased dynamic self-association propensity at neutral pH nor decreased conformational stability substantially affected the stability of concentrated variants E430G or E345K during storage for two years at 2-8°C. We discuss how these findings may inform the design and development of IgG-based therapeutics

Arte, conhecimento geográfico e leitura de imagens: O geógrafo, de Vermeer Art, geographical knowledge and image reading: Vermeer's "Geographer"

O quadro O geógrafo, do pintor holandês Johannes Vermeer, é uma imagem freqüentemente escolhida para capas de livros em geografia. Desenhada na segunda metade do século XVII, a pintura não apenas pode ser considerada um retrato de como pensar e fazer geografia naquela época, mas também representa uma obra de arte com forte carga simbólica para estimular uma discussão metodológica sobre a leitura geográfica de imagens. Neste texto, objetiva-se refletir sobre as linguagens deste quadro dentro do seu contexto sociocultural, econômico e político e em relação aos diversos processos de construir conhecimento geográfico.<br>The painting The Geographer by the Dutch artist Johannes Vermeer is an image that is frequently selected as a cover for geography books. Drawn in the second half of the 17th century, the picture must not only be considered as a portrait of how to think and do geography at that time; it can also be seen as a piece of art with a heavy symbolic load to stimulate a methodological debate on geographic readings of images. The present text aims to reflect about the languages of this painting, considering its sociocultural, economic and political contexts and its relation to the different processes of constructing geographic knowledge

L’expérimentation animale reste indispensable (OPINION)

Trop fréquemment, l’expérimentation animale est présentée comme une pratique archaïque. Elle a bien changé. Et 100 % des patients traités le sont grâce aux concepts et techniques développés grâce à elle