Tailoring Toll-like Receptor 8 Ligands for Balancing Immune Response and Inflammation

Toll-like receptors (TLRs) play a central role in innate immunity by recognising invading pathogens and host-derived danger signals and initiating the inflammatory response. Aberrant TLR response is involved in the pathogenesis of cancers, infections, autoimmune disorders and allergic diseases. Therefore, TLRs represent attractive targets for novel therapeutic agents. The PhD project's main research aim is to discover novel small molecule modulators of Toll-like receptor 8 (TLR8) and understand their mechanisms of action using computational approaches. TLR8 crystal structure is solved, and several modulators are known from previous drug screens. Therefore, TLR8 is a promising target for rational computer-aided development of novel drug candidates. In the initial phase of the project, the main goal was to study relevant structural features in available crystal structures of TLR8. The focus was on the dimerisation interface because of its role in the binding of ligands and subsequent activation of the receptor. Additionally, we studied the conservation of the relevant structural features across the closely related TLRs. The second part shifts the focus to the binding of the small molecules to TLR8. We investigated interactions between the known ligands and TLR8 and used it to develop the most plausible 3D pharmacophore model. Subsequently, we employed the developed 3D pharmacophore model in virtual screening to identify novel modulators of TLR8. We identified a pyrimidine-based compound that inhibits TLR8-mediated signalling in the micromolar concentration range. The potent anti-inflammatory and dose-dependent response has been confirmed in a series of derivatives of this initial virtual hit, which allowed for a detailed elucidation of structure-activity relationships (SAR) and more precise description of the binding mode. Conclusively, we have developed a novel and promising pyrimidine-based TLR8 inhibitors in silico and confirmed their biological activity, selectivity and low cytotoxicity in vitro. Results from the study on TLR8 represent a solid basis for the future design of small molecule TLR modulators as novel therapeutic agents for modulating immune response and inflammation.Toll-like Rezeptoren (TLRs) spielen eine zentrale Rolle in angeborenen Immunsystem, indem sie eindringende Pathogene sowie endogene Gefahrensignale erkennen und Entzündungsreaktionen einleiten. TLRs sind an der Pathogenese von Krebserkrankungen, Infektionen, Autoimmunerkrankungen und allergischen Erkrankungen beteiligt. Aus diesem Grund stellen TLRs attraktive Ziele für neue, niedermolekulare Wirkstoffe dar. Das Hauptziel dieses Promotionsprojekts ist die Entdeckung neuer niedermolekularer Modulatoren des Toll-like-Rezeptors 8 (TLR8) und das Verständnis ihrer Wirkmechanismen mit Hilfe computergestützter Ansätze. Die Kristallstruktur von TLR8 ist verfügbar und mehrere Modulatoren sind aus früheren Wirkstoffscreens bekannt. Daher ist TLR8 ein vielversprechendes Ziel für die rationale computergestützte Entwicklung neuer Wirkstoffkandidaten. Am Beginn des Projekts bestand das Hauptziel darin, relevante strukturelle Merkmale in den verfügbaren Kristallstrukturen von TLR8 zu untersuchen. Der Fokus lag dabei auf dem Dimerisierungsbereich, da dieser eine wichtige Rolle bei der Bindung von Liganden und der anschließenden Aktivierung des Rezeptors spielt. Zusätzlich untersuchten wir die Konservierung der relevanten Strukturmerkmale über die eng verwandten TLRs hinweg. Der zweite Teil verlagert den Fokus auf die Bindung kleiner Moleküle an TLR8. Wir untersuchten die Interaktionen zwischen den bekannten Liganden und TLR8 und entwickelten daraus systemtisch ein 3D-Pharmakophormodell. Anschließend setzten wir das entwickelte 3D-Pharmakophormodell im virtuellen Screening ein, um neuartige Modulatoren des TLR8 zu identifizieren. Wir identifizierten ein Pyrimidin-Analogon, das die TLR8- vermittelte Signalweiterleitung im mikromolaren Konzentrationsbereich hemmt. Die potente entzündungshemmende und dosisabhängige Wirkung wurde in einer kleinen Serie von Analoga bestätigt. Schließlich optimierten wir die identifizierten Pyrimidinverbindungen weiter, was eine detailliertere Struktur-Aktivitäts-Analyse und eine genauere Aufklärung des Bindungsmodus ermöglichte. Zusammenfassend haben wir neuartige und vielversprechende TLR8-Inhibitoren auf Pyrimidinbasis in silico entwickelt und ihre in vitro biologische Aktivität, Selektivität und geringe Zytotoxizität bestätigt. Die Ergebnisse der Studie zu TLR8 helfen uns, die Prozesse zu verstehen, die für ein erfolgreiches Wirkstoffdesign auch bei anderen TLR notwendig sind und stellen eine gute Ausgangsbasis dar, um in Zukunft optimierte, niedermolekulare TLR- Modulatoren zu entwickeln und damit Entzündung und die Immunreaktion effizient zu modulieren

Genome assembly of endemic cave sponge (Eunapius subterraneus) using data obtained by nanopore sequencing technology

Koljeno Porifera iz carstva životinja (Metazoa) obuhvaća preko 8000 znanstveno opisanih vrsta spužvi. Zbog svoje jednostavne građe spužve imaju važnu ulogu u razumijevanju rane evolucije i odnosa između ostalih koljena iz carstva Metazoa. Spužve su i dobri modelni organizmi za razumijevanje bioloških procesa u višim životinjama. Uz morfološke podatke, sve važniju ulogu imaju i genomski podaci. Za složeniju funkcionalnu genomiku Porifera potrebni su nam genomi više predstavnika koljena, međutim, sekvenciranje i sklapanje čitavog genoma spužvi i dalje predstavlja izazov. Ogulinska špiljska spužvica Eunapius subterraneus zbog svojih osobitosti predstavlja zanimljiv modelni organizam. Pomoću dostupnih genomskih knjižnica sklopila sam, a potom i procijenila kvalitetu sklopljenog genoma ogulinske špiljske spužvice. Pritom sam koristila algoritme temeljene na de Bruijnovim grafovima i metodi preklapanje-raspored-konsenzus te primijenila hibridni pristup pri sklapanju genoma pomoću dugačkih sljedova dobivenih sekvenciranjem na uređaju The Oxford Nanopore Technologies MinION. Korištenjem hibridnog pristupa pomoću sljedova dobivenih na uređaju Oxford Nanopore Technologies MinION nije primijećeno poboljšanje u sklopljenom genomu. Moguće poteškoće u sastavljanju genoma predstavljaju onečišćenja, repetitivne sekvence i visoka heterozigotnost. Potrebna su daljnja istraživanja na području genomike Porifera.Porifera, a phylum within the Kingdom Animalia (Metazoa), consists of more than 8000 species of sponges. Owing to their simple morphology, sponges have an important role in understanding the early evolution and relationship between different phyla within the kingdom Animalia. Furthermore, sponges represent good models for biological processes in higher animals. Morphological features are becoming insufficient and we need more genomic data from different species within Porifera. However, the entire process of genome sequencing and assembly of Porifera still remains the challenge. Endemic cave sponge Eunapius subterraneus is an interesting model organism due to its unusual characteristics. Using various genomic libraries I conducted genome assembly and subsequent evaluation of the assembled genome of Eunapius subterraneus. I used various approaches based on both de Bruijn graphs and the Overlap-Layout-Consensus and conducted hybrid assembly using long reads obtained from the Oxford Nanopore Technologies MinION device. The hybrid assembly did not yield any improvement. Low assembly quality could be consequence of potential contamination, repetitive sequences and high heterozigosity rate. Further research of Porifera genomic is needed

Next generation 3D pharmacophore modeling

3D pharmacophore models are three‐dimensional ensembles of chemically defined interactions of a ligand in its bioactive conformation. They represent an elegant way to decipher chemically encoded ligand information and have therefore become a valuable tool in drug design. In this review, we provide an overview on the basic concept of this method and summarize key studies for applying 3D pharmacophore models in virtual screening and mechanistic studies for protein functionality. Moreover, we discuss recent developments in the field. The combination of 3D pharmacophore models with molecular dynamics simulations could be a quantum leap forward since these approaches consider macromolecule–ligand interactions as dynamic and therefore show a physiologically relevant interaction pattern. Other trends include the efficient usage of 3D pharmacophore information in machine learning and artificial intelligence applications or freely accessible web servers for 3D pharmacophore modeling. The recent developments show that 3D pharmacophore modeling is a vibrant field with various applications in drug discovery and beyond

Identification and characterization of a novel chemotype for human TLR8 inhibitors

The endosomal Toll-like receptor 8 (TLR8) recognizes single-stranded RNA and initiates early inflammatory responses. Despite the importance of endosomal TLRs for human host defense against microbial pathogens, extensive activation may contribute to autoimmune and inflammatory diseases. In contrast to the recent progress made in the development of modulators of plasma membrane-bound TLRs, little is known about endosomal TLR modulation and very few TLR8 inhibitors have been reported. In this study, we discovered and validated novel small-molecule TLR8 inhibitors. Fourteen potential TLR8 modulators were experimentally validated in HEK293T cells stably overexpressing human TLR8 and THP-1 macrophages. Five compounds inhibited TLR8-mediated signaling, representing a hit rate of 36%. The three most potent compounds neither cause cellular toxicity nor inhibition of TLR signaling induced by other receptor subtypes. Conclusively, we experimentally confirm novel and selective, pyrimidine-based TLR8 inhibitors with low cytotoxicity that are relevant candidates for lead optimization and further mechanistic studies