Particulate matter in cigarette smoke increases ciliary axoneme beating through mechanical stimulation

Area of Science:

• Cellular Biology
• Nanotechnology
• Respiratory Medicine

Background:

• The lung's mucociliary elevator clears foreign particles, protecting against irritants and microbes.
• Cigarette smoke (CS) and nanoparticles (NPs) are known to affect mucociliary clearance.
• The precise impact of CS and NPs on ciliary beating at the axonemal level remains unclear.

Purpose of the Study:

• To investigate how cigarette smoke extract (CSE) and NPs of varying sizes and surface chemistries affect ciliary motility.
• To determine if NP-induced alterations in ciliary beat frequency (CBF) are dependent on particle size and surface properties.

Main Methods:

• A cell-free model using isolated bovine tracheal axonemes was employed.
• Axonemes were exposed to adenosine triphosphate (ATP) to induce motility.
• CBF was measured in response to 5% CSE, CSE filtrate, and various sizes (40-500 nm) and surface chemistries (COOH, SO(4), PEG) of polystyrene NPs.

Main Results:

• CSE (5%) significantly stimulated CBF; filtration attenuated this effect.
• Sulphate-modified NPs (~300 nm) increased CBF, similar to CSE.
• Larger COOH-modified NPs (>300 nm) significantly increased CBF and motile points, while PEG-coated or smaller COOH-modified NPs had no effect.

Conclusions:

• Nanoparticles, including those in CSE, mechanically stimulate axonemes in a size- and surface chemistry-dependent manner.
• Physicochemical properties of NPs influence ciliary motility.
• These findings are relevant to understanding inhalational lung injury and optimizing respirable drug delivery.