Airway and Lung Epithelium Models

In order to investigate the adhesion and invasion of pathogenic fungi to airway epi-thelia, either human nasal or tracheal cell lines have been employed. Human nasal ciliated epithelium is obtained from healthy volunteers. Functional integrity of the cells can be measured by quantifying the beat frequency of cilia by a photometric technique (Amitani et al., 1995).

The primary culture of human nasal epithelial cells (HNEC) in air-liquid interface led to a useful model for the interaction of A. fumigatus with an airway epithelium (Botterel et al., 2002). HNEC formed a pseudostratified epithelium with typical airway epithelium characteristics. A similar approach was followed by Shin et al. (2006) using nasal polyp epithelial cells.

Due to the relative simplicity by which hamster tracheal epithelium (HTE) cells can be isolated and cultivated, these cells are a popular model for respiratory epithelia (Goldman & Baseman, 1980). In a biphasic chamber system they develop the epithelial-typical polarity, differentiating cilia and secreting mucin-like molecules on the apical side (Whitcutt et al., 1988). HTE cells have been used for example to analyse the persistence of the intracellular pathogen H. capsulatum in non-professionally phagocytic host cells (Eissenberg et al., 1997).

At the distal end of the respiratory pathway, lung epithelial cells are components of the respiratory tissue barrier. The most commonly used lung epithelial cell line is A549, a type II pneumocyte of bronchoalveolar carcinoma origin. Several studies have investigated the interaction of A. fumigatus with A549 cells either by scanning electron microscopy (SEM), transmission electron microscopy (TEM), or immunofluorescence-confocal microcroscopy of a GFP expressing strain (DeHart et al., 1997; Paris et al., 1997; Wasylnka & Moore, 2002, 2003). This lead to the conclusion that A. fumigatus conidia adhere to and are engulfed by lung epithelial cells in which they differentiate to the barrier-breaking hyphal form (Filler & Sheppard, 2006). Also C. neoformans adheres to and is internalized by lung epithelial cells (Merkel & Scofield, 1997). The A549 in vitro model enabled the identification of the capsule structure glucuronoxylo-mannan (GMX) and phospholipase B (PLB1) as important fungal factors for this process (Barbosa et al., 2006; Ganendren et al., 2006).

An improved and more physiological model consists of A549 cells grown in a two-chamber system. Here the monolayer is not immersed in medium but exposed to the air, and only separated by a thin surfactant layer produced by the polar pneumocytes (Blank et al., 2006). In three-dimensional models epithelial cells were supplemented with macrophages, monocytes, and dendritic cells (DC) at their corresponding natural apical or basal location (Radyuk et al., 2003; Rothen-Rutishauser et al., 2005). Two-layer systems that model the functional barrier of the alveolar wall include epithelial and microvascular EC (Hermanns et al., 2004). The traversal of microorganisms through the barrier could be investigated in further detail by adding monocytes to the system (Bermudez et al., 2002).

Cure Your Yeast Infection For Good

Cure Your Yeast Infection For Good

The term vaginitis is one that is applied to any inflammation or infection of the vagina, and there are many different conditions that are categorized together under this ‘broad’ heading, including bacterial vaginosis, trichomoniasis and non-infectious vaginitis.

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