Jiří Ledvinka

ZUSAMMENFASSUNG: Die dynamische Glykan‐Schicht, die menschliche und mikrobielle Zellen umgibt, spielt eine wesentliche Rolle für die Fähigkeit des Immunsystems, Immuntoleranz und Gleichgewicht aufrechtzuerhalten sowie Krankheitserreger und Krebs zu bekämpfen. Endogene Anti‐Glykan‐Antikörper sind ein unverzichtbarer Bestandteil der Immunüberwachung, da sie abnormale mikrobielle Glykane, virale Glykoproteine und veränderte tumorassoziierte Kohlenhydratantigene identifizieren. Diese Glykane dienen wiederum als attraktive Ziele für passive und aktive Immunisierungsstrategien bei einer Reihe von Erkrankungen des Menschen. Das volle medizinische Potenzial der Glykane konnte bisher nicht voll ausgeschöpft werden, da sie eine enorme Komplexität und strukturelle Vielfalt aufweisen. Jüngste Fortschritte in der Glykansynthese, darunter automatisierte Glykansynthese, chemoenzymatische Strategien und Ein‐Topf‐Verfahren, ermöglichten einen beispiellosen Zugang zu genau definierten, homogenen Strukturen. Somit ebnen synthetische Glykane mit zunehmender struktureller Komplexität den Weg für eine Reihe von Anwendungen, von der Profilierung endogener Antikörperrepertoires zur Entdeckung von Biomarkern bis hin zur Entwicklung therapeutischer Antikörper und zum Impfstoffdesign. Hier fassen wir die Strategien zur Nutzung synthetischer Glykane für die Antikörperentwicklung und deren Anwendung in der Grundlagenforschung und der translationalen Medizin zusammen. Wir skizzieren, wie Anti‐Glykan‐Antikörper für diagnostische und therapeutische Zwecke eingesetzt werden, betonen dabei die Leistungsfähigkeit synthetischer Glykane und heben ihr Potenzial in der personalisierten Medizin hervor.

The dynamic glycan layer that surrounds human and microbial cells plays an essential role in the immune system's capacity to maintain immune tolerance and equilibrium, fight pathogens and cancer. Endogenous anti‐glycan antibodies are an indispensable part of immune surveillance, identifying abnormal microbial glycans, viral glycoproteins, and altered tumor‐associated carbohydrate antigens. These glycans serve in turn as attractive targets for passive and active immunization strategies in a range of human diseases. The enormous complexity and structural diversity of glycans has made it very difficult to unlock their full biomedical potential. Recent advances in glycan synthesis, including automated solid‐phase assembly, chemoenzymatic strategies, and one‐pot approaches, enabled unprecedented access to well‐defined, homogenous structures. Hence, synthetic glycans of increasing structural complexity pave the way for a range of applications, from profiling endogenous antibody repertoires for biomarker discovery to therapeutic antibody development and vaccine design. Here, we summarize the strategies to utilize synthetic glycans for antibody development and their application in basic research and translational medicine. We outline how anti‐glycan antibodies are utilized for diagnostic and therapeutic purposes, while emphasizing the power of synthetic glycans and highlighting their potential in personalized medicine.

Fluorescence detection of DNA and RNA G‐quadruplexes (G4s) is a very efficient strategy to assess not only the existence and prevalence of cellular G4s but also their relevance as targets for therapeutic interventions. Among the fluorophores used to this end, turn‐on probes are the most interesting since their fluorescence is triggered only upon interaction with their G4 targets, which ensures a high sensitivity and selectivity of detection. We reported on a series of twice‐as‐smart G4 probes, which are both smart G4 ligands (whose structure is reorganized upon interaction with G4s) and smart fluorescent probes (whose fluorescence is turned on upon interaction with G4s). The fine mechanistic details behind the excellent properties of the best prototype N‐TASQ remain to be deciphered: to investigate this, we report here on the synthesis and studies of two analogues, ^TzN‐TASQ and ^AlkN‐TASQ, and on a careful analysis of their G4‐interacting properties, investigated both in vitro and in silico. Our results show that fine‐tuning their constitutive structural elements allows for increasing the efficiency of both their ‘off’ (i. e., a conformation with a low fluorescence) and ‘on’ states (i. e., a conformation with a high fluorescence), which opens interesting ways for the design of more efficient fluorogenic G4 probes.

DC-SIGN (dendritic cell-specific intercellular adhesion molecule-3-grabbing non-integrin) is a pattern recognition receptor expressed on immune cells and involved in the recognition of carbohydrate signatures present on various pathogens, including HIV, Ebola, and SARS-CoV-2. Therefore, developing inhibitors blocking the carbohydrate-binding site of DC-SIGN could generate a valuable tool to investigate the role of this receptor in several infectious diseases. Herein, we performed a fragment-based ligand design using 4-quinolone as a scaffold. We synthesized a library of 61 compounds, performed a screening against DC-SIGN using an STD reporter assay, and validated these data using protein-based ¹H-¹⁵N HSQC NMR. Based on the structure-activity relationship data, we demonstrate that ethoxycarbonyl or dimethylaminocarbonyl in position 2 or 3 is favorable for the DC-SIGN binding activity, especially in combination with fluorine, ethoxycarbonyl, or dimethylaminocarbonyl in position 7 or 8. Furthermore, we demonstrate that these quinolones can allosterically modulate the carbohydrate binding site, which offers an alternative approach toward this challenging protein target.