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To diagnose diseases correctly requires not only trained and skilled personnel, but also cost-intensive and complex equipment. Rapid tests can help with the initial evaluation, but result generation can also take up to several hours, depending on the test system. At this point, novel bioresponsive diagnostic systems are used, responding to the disease related shift of biological processes. They monitor changes in the biological environment and can react to them e.g. with the release of substances. This can be used in drug delivery formulations but can also help to diagnose diseases occurring in the oral cavity and inform patients of their state of health. The tongue is herein used as a 24/7 available detector.
In section I of this work, the foundation for the development of these diagnostic systems was laid. A suitable flavoring agent was found, which is stable, can be coupled to the N-terminus of peptides and has a strongly conceivable taste. For the optimization of the protease-sensitive linker (PSL), an analytical system was established (PICS assay), which determines protease-specific cleavable amino acid sequences. In order to replace the PMMA particles previously required, an acetyl protecting group was introduced N-terminally as it protects peptides and proteins in the human body from degradation by human aminopeptidase. The new synthesized flavor was examined with a NIH cell line for cytotoxicity and with an electronic tongue setup for its bitterness.
Section II deals with the structure of a system which detects severe inflammations in the oral cavity, e.g. PA. The established PICS assay was used to confirm the previously used PSL sequence in its application. Using solid phase peptide synthesis, 3 linkers were synthesized which respond to the elevated MMP concentrations present in inflammation. The resulting peptides were acetylated and coupled with HATU/DIPEA to the modified denatonium. Cutting experiments with MMPs over different concentration and time ranges confirmed the response of the diagnostic sensor to these enzymes. The obtained construct was examined for cell toxicity by WST assay. The masked bitterness of the sensors was confirmed by an electronic tongue setup.
To address non-human proteases (and thereby infections), section III focuses on the establishment of detection system of a cysteine protease SpeB expressed by Streptococcus pyogenes. The in-house expression of SpeB using E. coli cells was established for this purpose. An analysis of the SpeB cleavage sites was performed using a PICS assay setup. Four constructs with different PSL were synthesized analogous to section II. Cleavage experiments with the expressed and purified SpeB showed a response of two constructs to the protease. In addition, a system was established to quantify the concentration of SpeB in human saliva using western blot technique with subsequent quantification.
In section IV a compound was synthesized which can now be coupled to a flavor. The final coupled construct is able to detect present NA activity specifically from influenza A and B. The market for existing influenza diagnostics was explored to determine the need for such a system. A neuraminic acid was modified in positions 4 and 7 and protected in such a way that subsequent coupling via the hydroxy-group in position 2 was selectively possible.
In summary, this results in a diagnostic platform that can be used anywhere, by anyone and at any time. This represents a new dimension in the rapid diagnosis of inflammations and bacterial or viral infections.
Schimmelpilze können in Abhängigkeit des Immunstatus und der Vorerkrankungen betroffener Patienten unterschiedliche Krankheitsbilder wie Hypersensitivitäts-erkrankungen oder lebensbedrohliche invasive Infektionen hervorrufen. Da die Diagnosestellung dieser Erkrankungen mitunter komplex und insensitiv ist, sollten im Rahmen dieser Arbeit unterschiedliche Ansätze neuer diagnostischer Assays untersucht werden.
In den letzten Jahren wurden Assays entwickelt, die auf Basis durchflusszytometrisch quantifizierter Pilz-spezifischer T-Zellen aus peripherem Blut einen supportiven Biomarker zur Diagnostik invasiver Mykosen liefern könnten. Da die hierfür isolierten T-Zellen anfällig gegenüber präanalytischer Lagerzeiten und immunsuppressiver Medikation sind, wurden hier Protokolloptimierungen vorgenommen, um anhand eines Vollblut-basierten Assays mit zusätzlicher CD49d-Kostimulation diesen Limitationen entgegen zu wirken. In einer Studie an gesunden Probanden konnte dabei gezeigt werden, dass die Kombination der Durchflusszytometrie mit ausgewählten Zytokin-Messungen (IL-5, IL-10 und IL-17) zu einer verbesserten Erkennung vermehrt Schimmelpilz-exponierter Personen beitragen könnte. Neben Infektionen könnten dabei im umwelt- und arbeitsmedizinischen Kontext Polarisationen der T-Zell-Populationen detektiert werden, welche mit Sensibilisierungen und Hypersensitivität assoziiert werden.
Zusätzlich wurde ein in vitro Transwell® Alveolarmodell zur Simulation pulmonaler Pilzinfektionen für Erreger der Ordnung Mucorales adaptiert, durch Reproduktion wichtiger Merkmale der Pathogenese von Mucormykosen validiert, und für Untersuchungen der Immunpathologie und Erreger-Invasion verwendet. Das Modell wurde anschließend zur in vitro Evaluation von radioaktiv markiertem Amphotericin B mit 99mTc oder 68Ga als nuklearmedizinischen Tracer verwendet. Die untersuchten Schimmelpilze zeigten dabei eine zeit- und dosis-abhängige Aufnahme der Tracer, während bakteriell infizierte Proben nicht detektiert wurden. Die erhobenen Daten dokumentieren ein vielversprechendes Potenzial von Amphotericin B-basierten Tracer, das in zukünftigen in vivo Studien weiter evaluiert werden sollte.