Anna Ermund,corresponding author1 Lauren N. Meiss,1 Brendan Dolan,1 Florian Jaudas,2 Lars Ewaldsson,3 Andrea Bähr,2 Nikolai Klymiuk,2 and Gunnar C. Hansson1


"1Department of Medical Biochemistry and Cell Biology, University of Gothenburg, PO Box 440, 405 30 Gothenburg, Sweden
2Institute of Molecular Animal Breeding and Biotechnology, Gene Center, Ludwig-Maximilians-University Munich, Munich, Germany
3Experimental Biomedicine, University of Gothenburg, Gothenburg, Sweden
Anna Ermund, Email: [email protected]
corresponding authorCorresponding author."


Medical Research


The mucociliary clearance system driven by beating cilia protects the airways from inhaled microbes and particles. Large particles are cleared by mucus bundles made in submucosal glands by parallel linear polymers of the MUC5B mucins. However, the structural organization and function of the mucus generated in surface goblet cells are poorly understood.

The origin and characteristics of different mucus structures were studied on live tissue explants from newborn wild-type (WT), cystic fibrosis transmembrane conductance regulator (CFTR) deficient (CF) piglets and weaned pig airways using video microscopy, Airyscan imaging and electron microscopy. Bronchoscopy was performed in juvenile pigs in vivo.

We have identified a distinct mucus formation secreted from the surface goblet cells with a diameter less than two micrometer. This type of mucus was named mucus threads. With time mucus threads gathered into larger mucus assemblies, efficiently collecting particles. The previously observed Alcian blue stained mucus bundles were around 10 times thicker than the threads. Together the mucus bundles, mucus assemblies and mucus threads cleared the pig trachea from particles.

These results demonstrate that normal airway mucus is more complex and has a more variable structural organization and function than was previously understood. These observations emphasize the importance of studying young objects to understand the function of a non-compromised lung.

Supplementary Information
The online version contains supplementary material available at 10.1186/s12931-021-01898-3.

Keywords: Mucins, Respiratory tract, Mucus bundle, Goblet cells, Trachea, Bronchi

DOI: 10.1186/s12931-021-01898-3


Time-lapse recordings were acquired through an SMZ18 stereo microscope (Nikon, Tokyo, Japan) and white light (Photonics, Pittsfield, MA) or a CoolLED pE-300ultra light source (CoolLED, Andover, UK) using a 5.0-megapixel color CCD camera (DS-Fi2 or DS-Fi3, Nikon, Tokyo, Japan) or a monochrome cooled CCD camera (DS-Qi1, Nikon, Tokyo, Japan) and NIS elements software (RRID:SCR_014329, Nikon, Tokyo, Japan).

Product Associated Features

The broad spectrum pE-300ultra offers TTL triggering, individual channel control and software integration. This makes it ideal for fast pulsing at differing durations and irradiance, such as in these optogenetic protocols.

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Respiratory research

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