ADAMTS-13 regulates neutrophil recruitment in a mouse model of invasive pulmonary aspergillosis

Von Willebrand factor (VWF) is secreted as an acute phase protein during inflammation. ADAMTS-13 regulates the size and prothrombotic activity of VWF by it’s specific proteolytic activity. To determine the relevance of this regulatory pathway for the innate inflammatory response by polymorphonuclear neutrophils (PMN), we employed a mouse model of invasive pulmonary aspergillosis (IPA) where PMN functionality is crucial for fungal clearance and survival. IPA was induced by intratracheal application of Aspergillus fumigatus (A. fumigatus) conidia in wildtype (129/Sv/Pas) or ADAMTS-13 deficient (Adamts13 (−/−)) mice. While neutropenic mice developed lethal IPA, all wildtype mice survived the infection. In contrast to wildtype or VWF deficient mice, Adamts13 (−/−) mice displayed more severe signs of disease with a lethal course in 24% with an increased fungal burden and signs of acute lung injury. Histology sections demonstrated a more pronounced perivascular leukocyte infiltration in support of a dysregulated inflammatory response in Adamts13 (−/−) mice. Importantly, we observed no general defect in the activation of neutrophil functions in response to conidia or hyphae in vitro. Therefore, we conclude that the proteolytic regulation of VWF by ADAMTS-13 or ADAMTS-13 by itself is an important mechanism to control PMN recruitment in acute inflammatory processes, such as fungal pneumonias.