Annie Viallat (CNRS Aix-Marseille University): How do millions of microscopic active cilia self-organize to protect our airways?

Title: How do millions of microscopic active cilia self-organize to protect our airways?

Speaker: Annie Viallat, CNRS Aix-Marseille University

Hosted by: Gregg Duncan

Abstract:

The respiratory tract is protected by mucus, a complex fluid transported along the epithelial surface by the coordinated beating
of millions of microscopic cilia, hence the name of mucociliary clearance. Its impairment is associated with all severe chronic
respiratory diseases. Yet, the relationship between ciliary density and the spatial scale of mucus transport, as well as the mechanisms
that drive ciliary-beat orientations are much debated. Here, we show on polarized human bronchial epithelia that mucus
swirls and circular orientational order of the underlying ciliary beats emerge and grow during ciliogenesis, until a macroscopic
mucus transport is achieved for physiological ciliary densities. By establishing that the macroscopic ciliary-beat order is lost
and recovered by removing and adding mucus, respectively, we demonstrate that cilia–mucus hydrodynamic interactions govern
the collective dynamics of ciliary-beat directions. We propose a two-dimensional model that predicts a phase diagram of
mucus transport in accordance with the experiments.