Effects of Aspergillus fumigatus culture filtrate on antifungal activity of human phagocytes in vitro

Temporary remission of autoimmune pulmonary alveolar proteinosis after infectious episodes

Pulmonary alveolar proteinosis (PAP) is a rare disease of unknown aetiology. Although resolution occurs in about 30% of autoimmune PAP (APAP) cases, its pathogenesis is not yet sufficiently understood. Two APAP cases at our institute showed remission following infectious episodes. Case 1: a 40-year-old female APAP patient suffered from herpes encephalitis and was treated with an antiviral drug. Her symptoms and radiological results resolved within two months of her recovery from the encephalitis. Case 2: A 53-year-old male current-smoker APAP patient was admitted for pneumonia. After treatment with antibiotics, his radiological results and symptoms improved. He experienced a similar resolution of APAP after another infectious episode two years later. Remission of APAP may occur following viral or bacterial infection. We hypothesise that remission of APAP is triggered by the induction of granulocyte-macrophage colony-stimulating factor (GM-CSF) following viral or bacterial infection. Further studies of APAP remission, and especially of the effects of GM-CSF induction, are needed. (Sarcoidosis Vasc Diffuse Lung Dis 2017; 34: 85-90).

Autoimmune Pulmonary Alveolar Proteinosis Following Pulmonary Aspergillosis

A 59-year-old man, ex-smoker, was diagnosed with pulmonary aspergillosis according to chest radiography findings of a fungus ball and Aspergillus fumigatus detection in the bronchial lavage fluid. Two years after anti-fungal therapy, he was diagnosed with autoimmune pulmonary alveolar proteinosis (APAP) according to a crazy paving pattern in computed tomography scans of the chest, milky bronchoalveolar lavage effluent, and positive anti-granulocyte-macrophage colony-stimulating factor (GM-CSF) autoantibody in the serum. The patient ultimately died of respiratory failure caused by APAP four months after GM-CSF therapy commenced. Aspergillus infection may thus be associated with the onset and progression of APAP and tolerance to GM-CSF therapy.

Influence of amphotericin B and amphotericin B colloidal dispersion on the functions of human phagocytes in defence against Aspergillus species

This study investigated the in vitro effects of amphotericin B and amphotericin B colloidal dispersion (ABCD) on phagocytosis and inhibition of germination of clinical isolates of Aspergillus spp. by monocyte-derived macrophages (MDMs). Both amphotericin B and ABCD caused significant reductions in uptake of conidia of Aspergillus spp. by MDMs (p < 0.01). The inhibition of germination was superior with conidia of Aspergillus fumigatus, Aspergillus niger and Aspergillus terreus isolates. Aspergillus flavus growth was significantly less inhibited of either antimycotic as compared to A. fumigatus and A. terreus (p < 0.01).We demonstrate that amphotericin B or ABCD acts as a potent inhibitor of Aspergillus germination. By contrast, treatment of MDMs with these antimycotics diminished phagocytosis of conidia in vitro.

Intracellular oxidative response of human monocytes and granulocytes to different strains of Aspergillus fumigatus

Aspergillus fumigatus is one of the most prevalent airborne fungal pathogens, causing severe and often fatal infections. Its fungal virulence factors have not been clearly identified. Reactive oxygen species produced by phagocytic cells are potent fungicides for A. fumigatus. The aim of this study was to examine the influence of conidia pigmentation, fungal development stage and genotype strain on human leucocytes oxidative response. Various A. fumigatus strains were used and the oxidative response was analysed by flow cytometry. A significant difference was observed between live- and killed-conidia. A pigmentless strain gave an important intracellular oxidative response compared with pigmented strains. But no difference was observed between strains isolated from patients with invasive aspergillosis (IA) and bronchial colonisation. The modification of healthy phagocytes' oxidative response caused by A. fumigatus components is not sufficient to explain the virulence of fungus and to predict an evolution of patients with IA.

Toll-like receptors: Recent advances, open questions and implications for aspergillosis control

Aspergillus fumigatus is a pathogenic mould that can cause severe and life-threatening infections in immunocompromised patients. Apart from novel and improved antifungals, additional strategies are required to protect patients at risk from developing invasive aspergillosis. Given the problems in diagnosis of this disease, important perspectives lie in attempts to elicit and strengthen a protective immunity. The innate immune system is the first line of defence against A. fumigatus. Phagocytes engulf and kill inhaled conidia, but also closely communicate with the adaptive immune system. Recognition of invading microbes is mediated by pattern recognition receptors (PRRs), and Toll-like receptors (TLR) 2 and TLR4 have been implicated in the immune response to A. fumigatus. The analysis of this process is hampered by the fact that A. fumigatus infections are inevitably coupled to germination resulting in the appearance of different fungal morphotypes, like conidia and hyphae. While conflicting data still exist on the relative importance of TLR2 and 4 in recognition of distinct A. fumigatus morphotypes, recent evidence suggests that certain TLR agonists can be used to divert the immune response towards an optimal fungicidal activity in the absence of detrimental inflammatory consequences.

Spore diffusate isolated from some strains of Aspergillus fumigatus inhibits phagocytosis by murine alveolar macrophages

Aspergillus fumigatus is a ubiquitous fungus that grows in decaying organic matter. It can cause disease in both immunodeficient and immunocompetent patients by using virulence factors to escape the host defenses. Some of these factors, such as a diffusate, released from the spores of A. fumigatus, have previously been described. This diffusate was demonstrated to inhibit oxidative burst and phagocytosis of coated red blood cells. The present study has shown that this substance can inhibit the phagocytosis of A. fumigatus spores by murine alveolar macrophages (MALU) and evaluated the action of this substance. We quantified phagocytosis by MALU cells with and without diffusate and evaluated the inhibition of phagocytosis by testing diffusates from different strains. We conclude that the spore diffusate of some strains of A. fumigatus can reversibly decrease the ability of alveolar macrophages to ingest A. fumigatus spores.