Smoking effect on the ultrastructural properties of cultured lung myofibroblasts

ABSTRACT

This study aimed at an ultrastructural characterization of myofibroblasts cultured from different compartments of lung from never-smokers and smokers with or without COPD. In addition, we evaluated the expression of alpha smooth muscle actin (α-SMA), a marker for myofibroblasts, and contractile properties. Stromal cells cultured from central and corresponding peripheral or only from peripheral lung of never-smokers, smokers without COPD and COPD patients were analyzed by transmission electron microscopy (TEM), immunoelectron microscopy (IEM), Western analysis and/or by collagen gel contraction assay. TEM revealed that myofibroblasts cultured from smokers and COPD had less prominent intracellular actin filaments. We also examined fibronexus (FNX), which is a typical ultrastructural feature of myofibroblasts, and observed that patients with COPD more frequently had tandem-like FNX as compared to other samples. Western analysis showed that the samples derived from the central lung of never-smokers expressed higher levels of α-SMA than those of smokers and COPD patients. Cells from central lung were less contractile than those from peripheral lung. We conclude that myofibroblasts have variable ultrastructural and functional properties based on their localization in the lung and, moreover, these properties are affected by both smoking history and COPD.

KEYWORDS:

• Fibronexus
• actin
• contraction
• COPD

Acknowledgments

The authors thank Raija Sormunen PhD and the Biocenter Oulu EM laboratory staff for their valuable assistance in performing the electron microscopy.

Disclosure statement

The authors report no conflict of interest.

Additional information

Funding

This study was supported by Foundation of the Finnish Anti-Tuberculosis Association, the Jalmari and Rauha Ahokas Foundation, the Väinö and Laina Kivi Foundation, the Research Foundation of the Pulmonary Diseases, a state subsidy of the Oulu University Hospital, Academy of Finland, the Health Care Foundation of North Finland and the Swedish Heart-Lung Foundation.