Cilia are roughly 10 _m long hair-like protrusions of the cell membrane. In the airways of higher organisms, their coordinated oscillatory beating movements causes directed motion of the mucosal fluid, cleaning the airways from adhering inhaled particles and harmful substances.
It is obvious that in order to achieve efficient directed transport, the ciliary motions must be, at least locally coordinated. Immotile cilia or lack of coordination are made responsible for different severe diseases, such as primary ciliary dyskinesia, therefore there is a demand for reliable diagnostic techniques. The key to every diagnosis is a sound knowledge of the healthy system. To achieve this goal, we focus on two complementary lines of action:
- We have developed a setup for the investigation and characterization of various aspects and parameters of mucociliary transport in an inter-species comparative study involving cow, sheep, pig, rabbit and turkey. In a collaboration with the clinic for zoo animals, exotic pets and wildlife (Univ. of Zurich), we have investigated the mucociliary clearance in snakes infected with boid inclusion body disease (BIBD). In BIBD-a_ected snakes amphophilic perinuclear inclusion bodies are found in the respiratory epithelium (see Figure), whose consequence to the mucociliary function has not been evaluated before. As pneumonia is commonly seen in BIBD-infected snakes, BIBD is suspected to impair mucociliary clearance in the respiratory tract.
- We have developed a theoretical model for explaining the self-organization that leads to mucociliary transport, based on interpreting ciliated cells as oscillating boolean actuators and their interactions as logical functions. Interactions between cells are triggered by virtual mucus lumps, which establish the network’s topology. This simple model exhibits the emergence of spatio-temporal patterns, that are accompanied by self-organized transport. The co-evolution of the network’s state and its topology allows to understand the mucociliary dynamics in the context of adaptive networks. Based on the study of a range of various model parameters, our main conclusion is that unciliated cells may improve the robustness of the spatio-temporal organization on ciliated epithelia, as they introduce a degree of modularity into the network’s topology. This provides a reasonable understanding of the observed patch-work character in the tracheal mucociliary system, which may be the expression of a modular mucocilairy network.
