Intracellular and extracellular growth of<i>Aspergillus fumigatus</i>

Wasylnka, Julie A.; Hissen, A. H. T.; Wan, Adrian; Moore, Margo M.

doi:10.1080/13693780400029247

Cited by 35 publications

(35 citation statements)

References 24 publications

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“…Aspergillus fumigatus is an opportunistic pathogen responsible for a number of respiratory diseases in normal hosts and severe invasive infections in immunocompromised patients (Latgé & Calderone, 2002). Although in this instance alveolar macrophages and neutrophils are known to phagocytose and kill Aspergillus conidia, a small percentage may be able to survive within these cells; moreover, it has been reported that fungal conidia may attempt to escape from professional phagocytes by invading epithelial and endothelial cells (Ibrahim-Granet et al, 2003;Wasylnka & Moore, 2003;Wasylnka et al, 2005). Furthermore, Aspergillus infections can cause significant cell injury during invasion, producing tissue damage that can induce host cell defences, with escape into normally nonphagocytic host cells by induction of fungal cell uptake serving as a mechanism to avoid such defences (Lopes Bezerra & Filler, 2004;Filler & Sheppard, 2006).…”

Section: Discussionmentioning

confidence: 99%

Intracellular infection of tick cell lines by the entomopathogenic fungus Metarhizium anisopliae

Kurtti

Keyhani

2008

Microbiology

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Several fungal pathogens are able to enter and persist within eukaryotic cells as part of their infectious life cycle. Metarhizium anisopliae is a saprophytic entomopathogenic fungus virulent towards numerous tick species, including those within the genera Ixodes and Amblyomma. Infection of the target organism by this fungus proceeds via several steps, including adhesion and penetration of the host cuticle, proliferation within tissues and the haemolymph, and eventual eruption through the host cadaver. To determine whether M. anisopliae could enter and persist within tick cells, we examined the uptake of wild-type and green fluorescent protein (GFP)-expressing fungal strains into two different tick cells lines, IDE12 and AAE2, derived from Ixodes scapularis and Amblyomma americanum, respectively. Uptake by tick cells was monitored by confocal fluorescent microscopy, as well as by scanning and transmission electron microscopy. M. anisopliae-specific antibodies were used to discriminate between extracellular and internalized fungal cells and to quantify the rate of uptake. Both cell lines internalized fungal conidia, and quantitative studies using the AAE2 cell line indicated that almost 70 % of the AAE2 cells contained internalized conidia after 6 h incubation. Internalization of conidia by AAE2 cells was time and temperature dependent and could be inhibited by 80 % with 1 mM cytochalasin D. Internalized conidia remained viable within the AAE2 cells, where they were able to germinate and grow, eventually erupting from the host cells. These data provide evidence that M. anisopliae conidia can be internalized, survive and grow within phagocytic cells in vitro and indicate that phagocytosis may serve as an alternative invasion route facilitating fungal nutrient acquisition, immune system evasion and dissemination throughout the host.

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Section: Discussionmentioning

confidence: 99%

Intracellular infection of tick cell lines by the entomopathogenic fungus Metarhizium anisopliae

Kurtti

Keyhani

2008

Microbiology

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“…42 Irrespective of whether IDO itself may contribute to the antimicrobial innate function of ECs, our data indicate an important role for the MyD88 pathway in ECs in the control of fungal growth, a finding suggesting the possible antifungal effector activity of ECs. In this regard, despite the fact that airways ECs phagocytose Aspergillus conidia, 16,17 the ability of conidia to survive in ECs 17 was taken to indicate airways ECs as a possible fungus reservoir. More recently, ECs were found to respond to Aspergillus conidia via MyD88-dependent and -independent pathways 18 and by upregulating antimicrobial peptides 43,44 endowed with antifungal activity.…”

Section: Discussionmentioning

confidence: 99%

“…This has lent to the credence that ECs may serve as reservoirs for immune evasion. 16,17 However, respiratory ECs also sense germinating conidia through MyD88-dependent and -independent pathways. 18 Of interest, IDO overexpression from the airway ECs was found to restrain CD4 1 T-cell activation to the fungus, an activity that was nevertheless dispensable in the presence of IDO-expressing DCs.…”

Section: Dendritic Cells (Dcs) Orchestrate the Adaptive Immune Responmentioning

confidence: 99%

Non-hematopoietic cells contribute to protective tolerance to Aspergillus fumigatus via a TRIF pathway converging on IDO

et al. 2010

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Innate responses combine with adaptive immunity to generate the most effective form of anti-Aspergillus immune resistance. Whereas the pivotal role of dendritic cells in determining the balance between immunopathology and protective immunity to the fungus is well established, we determined that epithelial cells (ECs) also contributes to this balance. Mechanistically, EC-mediated protection occurred through a Toll-like receptor 3/Toll/IL-1 receptor domain-containing adaptor-inducing interferon (TLR3/TRIF)-dependent pathway converging on indoleamine 2,3-dioxygenase (IDO) via non-canonical nuclear factor-kB activation. Consistent with the high susceptibility of TRIF-deficient mice to pulmonary aspergillosis, bone marrow chimeric mice with TRIF unresponsive ECs exhibited higher fungal burdens and inflammatory pathology than control mice, underexpressed the IDO-dependent T helper 1/regulatory T cell (Th1/Treg) pathway and overexpressed the Th17 pathway with massive neutrophilic inflammation in the lungs. Further studies with interferon (IFN)-c, IDO or IL-17R unresponsive cells confirmed the dependency of immune tolerance to the fungus on the IFN-c/IDO/ Treg pathway and of immune resistance on the MyD88 pathway controlling the fungal growth. Thus, distinct immune pathways contribute to resistance and tolerance to the fungus, to which the hematopoietic/non-hematopoietic compartments contribute through distinct, yet complementary, roles.

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“…is not well defined, and the clinical relevance of antifungal ELF concentrations is unknown. In vitro studies demonstrate a propensity for the conidiae and hyphae of Aspergillus fumigatus to invade and germinate in human pneumocytes (6,17). Thus, the sites of pulmonary aspergillosis likely include not only the ELF but also alveolar macrophages, pulmonary epithelial cells, and the interstitial fluid of lung tissue.…”

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confidence: 99%

Intrapulmonary Penetration of Voriconazole in Patients Receiving an Oral Prophylactic Regimen

Capitano

Potoski

Husain

et al. 2006

Antimicrob Agents Chemother

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Voriconazole penetrated well into the pulmonary epithelial lining fluid (ELF) in lung transplant patients receiving oral prophylaxis. The ELF concentrations exceeded those of the plasma, with an average ELF-toplasma ratio of 11 (؎8). A strong association between plasma and ELF concentrations (r 2 ‫؍‬ 0.95) was noted.Adequate drug penetration to the infection site is crucial for antimicrobial therapeutic optimization. The lungs are the most common site of primary infection in cases of invasive aspergillosis (9,14). Voriconazole has become a preferred agent for the treatment of invasive aspergillosis (3). Despite its widespread use in the management of pulmonary aspergillosis, the intrapulmonary penetration of voriconazole has not been reported in humans. Voriconazole is used routinely as antifungal prophylaxis in some lung transplant centers; this offers an opportunity to study the intrapulmonary penetration of the drug, since lung transplant recipients routinely undergo surveillance bronchoscopy (5, 7).This was a prospective observational pilot study. The subjects were lung transplant patients, Ն18 years of age, who had received at least six oral doses of voriconazole prior to a scheduled bronchoscopy. The Institutional Review Board approved the study, and all patients provided written informed consent prior to participation.Voriconazole treatment (6 mg/kg of body weight intravenously every 12 h for 2 doses followed by 200 mg orally twice daily) was initiated immediately after transplant and continued for approximately 4 months as standard clinical care. Bronchoalveolar lavage (BAL) was performed at 2, 4, and 8 weeks posttransplant in all patients during the voriconazole prophylaxis period. A blood sample and an aliquot of pooled BAL supernatant were acquired for study purposes during one of these procedures.Total (free and protein-bound) voriconazole concentrations were measured in the plasma and BAL supernatant by a modified high-performance liquid chromatography-electrospray ionization mass spectrometry technique (13, 18). Authentic voriconazole (UK-109,496) and an internal standard (UK-103,446) were provided by Pfizer Global Research and Development (Sandwich, United Kingdom). The standard curves were linear (r 2 ϭ 0.99) over a concentration range of 0.05 to 6.0 g/ml for the plasma and 0.001 to 0.5 g/ml for the BAL. Interday coefficients of variation were Ͻ12.6%. The concentrations of urea in the serum and BAL supernatant were measured, separately, by a colorimetric method (serum, Vitros 950 [Ortho Clinical Diagnostics, Rochester, NY]; BAL, Urea Nitrogen Reagent [Teco Diagnostics, Anaheim, CA], respectively). The volume of epithelial lining fluid (ELF) recovered in the BAL aspirate and the concentration of voriconazole in the ELF were calculated based on the urea dilution method as previously reported (1, 2, 12). A two-tailed Spearman's rank correlation test was applied to test for a relationship between plasma and ELF concentrations.Twelve patients were enrolled in the study, with BAL and blood samples succ...

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Intracellular and extracellular growth ofAspergillus fumigatus

Cited by 35 publications

References 24 publications

Intracellular infection of tick cell lines by the entomopathogenic fungus Metarhizium anisopliae

Intracellular infection of tick cell lines by the entomopathogenic fungus Metarhizium anisopliae

Non-hematopoietic cells contribute to protective tolerance to Aspergillus fumigatus via a TRIF pathway converging on IDO

Intrapulmonary Penetration of Voriconazole in Patients Receiving an Oral Prophylactic Regimen

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