Aspergillus fumigatus-sensitive IgE is associated with bronchial hypersensitivity in a murine model of neutrophilic airway inflammation

The Emerging Role of Mast Cells in Response to Fungal Infection

Mast cells (MCs) have been considered as the core effector cells of allergic diseases. However, there are evidence suggesting that MCs are involved in the mechanisms of fungal infection. MCs are mostly located in the border between host and environment and thus may have easy contact with the external environmental pathogens. These cells express receptors which can recognize pathogen-associated molecular patterns such as Toll-like receptors (TLR2/4) and C-type Lectins receptors (Dectin-1/2). Currently, more and more data indicate that MCs can be interacted with some fungi (Candida albicans, Aspergillus fumigatus and Sporothrix schenckii). It is demonstrated that MCs can enhance immunity through triggered degranulation, secretion of cytokines and chemokines, neutrophil recruitment, or provision of extracellular DNA traps in response to the stimulation by fungi. In contrast, the involvement of MCs in some immune responses may lead to more severe symptoms, such as intestinal barrier function loss, development of allergic bronchial pulmonary aspergillosis and increased area of inflammatory in S. schenckii infection. This suggests that MCs and their relevant signaling pathways are potential treatment regimens to prevent the clinically unwanted consequences. However, it is not yet possible to make definitive statements about the role of MCs during fungal infection and/or pathomechanisms of fungal diseases. In our article, we aim to review the function of MCs in fungal infections from molecular mechanism to signaling pathways, and illustrate the role of MCs in some common host-fungi interactions.

Factors Contributing to Sex Differences in Mice Inhaling Aspergillus fumigatus

Aspergillus fumigatus is a respiratory fungal pathogen and an allergen, commonly detected in flooded indoor environments and agricultural settings. Previous studies in Balb/c mice showed that repeated inhalation of live and dry A. fumigatus spores, without any adjuvant, elevated allergic immune response and airway remodeling. Sex-specific differences can influence host-pathogen interactions and allergic-asthma related outcomes. However, the effect of host sex on immune response, in the context of A. fumigatus exposure, remains unknown. In this study, we quantified the multivariate and univariate immune response of C57BL/6J mice to live, dry airborne A. fumigatus spores. Our results corroborate previous results in Balb/c mice that repeated inhalation of live A. fumigatus spores is sufficient to induce mucus production and inflammation by day 3 post last challenge, and antibody titers and collagen production by day 28 post-challenge. Principal Component Analysis (PCA) showed that females exhibited significantly higher levels of immune components than males did. Taken together, our data indicate that host-sex is an important factor in shaping the immune response against A. fumigatus, and must be considered when modeling disease in animals, in designing diagnostics and therapeutics for A. fumigatus-associated diseases or while drafting evidence-based guidelines for safe mold levels.

Neutrophil Adaptations upon Recruitment to the Lung: New Concepts and Implications for Homeostasis and Disease

Neutrophils have a prominent role in all human immune responses against any type of pathogen or stimulus. The lungs are a major neutrophil reservoir and neutrophilic inflammation is a primary response to both infectious and non-infectious challenges. While neutrophils are well known for their essential role in clearance of bacteria, they are also equipped with specific mechanisms to counter viruses and fungi. When these defense mechanisms become aberrantly activated in the absence of infection, this commonly results in debilitating chronic lung inflammation. Clearance of bacteria by phagocytosis is the hallmark role of neutrophils and has been studied extensively. New studies on neutrophil biology have revealed that this leukocyte subset is highly adaptable and fulfills diverse roles. Of special interest is how these adaptations can impact the outcome of an immune response in the lungs due to their potent capacity for clearing infection and causing damage to host tissue. The adaptability of neutrophils and their propensity to influence the outcome of immune responses implicates them as a much-needed target of future immunomodulatory therapies. This review highlights the recent advances elucidating the mechanisms of neutrophilic inflammation, with a focus on the lung environment due to the immense and growing public health burden of chronic lung diseases such as cystic fibrosis (CF) and chronic obstructive pulmonary disease (COPD), and acute lung inflammatory diseases such as transfusion-related acute lung injury (TRALI).