Signal-amplifying biomarkers for the diagnosis of invasive fungal infections.

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DESCRIPTION (provided by applicant): We are proposing to develop bioanalytical techniques to identify and characterize signal- amplifying biomarkers that improve the diagnosis and monitoring of invasive pulmonary aspergillosis. An additional goal is the creation of a reliable bioanalytical tool for patient prognosis during severe fungal infections. Fungal proteases are released in the lungs of infected patients, causing the proteolytic degradation of proteins contained in pulmonary secretions. A single protease molecule can cleave multiple substrate molecules resulting in a natural signal amplification effect. This will be exploited by 1) detecting specific proteolytic products using hypothesis-driven mass spectrometry and 2) through biochemical methods such as in-vitro cleavage of fluorogenic substrates. Our strategy will utilize immunochemical enrichment techniques for both fungal proteases and cleavage products, using enrichment matrices containing monoclonal antibodies. We have demonstrated an immunoprotective role of an intracellular fungal protein that becomes accessible to the human immune system after cell-wall degradation by pulmonary enzymes such as chitinases. Based on this finding, we will test the hypothesis that human chitinases may be induced during fungal infections, and that the level of chitinase (and other lytic activity), varies from patient to patient and depends on genetic and pathophysiological conditions. In accordance with an approved clinical protocol, we propose to obtain a set of clinical bronchoalveolar lavage fluids, blood, and urine samples from patients with suspected fungal infections. These samples will be used for the development and evaluation of signal-amplifying biomarker assays for invasive pulmonary aspergillosis. The results of this research are expected to enable translation into novel clinical applications for better diagnosis, prognosis, monitoring and ultimately control of invasive fungal infections. The research proposed here is designed to identify signal-amplifying biomarkers that will be useful for the rapid and sensitive diagnosis of invasive fungal infections. Invasive fungal infections, such as invasive pulmonary aspergillosis, present a major problem during cancer therapy, following organ transplantation, for AIDS patients and other severe diseases that weaken the human immune defenses. The results of this exploratory study should enable translation into clinical applications that will improve the diagnosis of invasive fungal infections, which has the potential to save the lives of several thousand Americans and tens of thousands patients worldwide per year.