Myofibroblasts in interstitial lung diseases show diverse electron microscopic and invasive features

Abstract

The characteristic features of myofibroblasts in various lung disorders are poorly understood. We have evaluated the ultrastructure and invasive capacities of myofibroblasts cultured from small volumes of diagnostic bronchoalveolar lavage (BAL) fluid samples from patients with different types of lung diseases. Cells were cultured from samples of BAL fluid collected from 51 patients that had undergone bronchoscopy and BAL for diagnostic purposes. The cells were visualized by transmission electron microscopy and immunoelectron microscopy to achieve ultrastructural localization of alphasmooth muscle actin (a-SMA) and fibronectin. The levels of a-SMA protein and mRNA and fibronectin mRNA were measured by western blot and quantitative real-time reverse transcriptase polymerase chain reaction. The invasive capacities of the cells were evaluated. The cultured cells were either fibroblasts or myofibroblasts. The structure of the fibronexus, and the amounts of intracellular actin, extracellular fibronectin and cell junctions of myofibroblasts varied in different diseases. In electron and immunoelectron microscopy, cells cultured from interstitial lung diseases (ILDs) expressed more actin filaments and a-SMA than normal lung. The invasive capacity of the cells obtained from patients with idiopathic pulmonary fibrosis was higher than that from patients with other type of ILDs. Cells expressing more actin filaments had a higher invasion capacity. It is concluded that electron and immunoelectron microscopic studies of myofibroblasts can reveal differential features in various diseases. An analysis of myofibroblasts cultured from diagnostic BAL fluid samples may represent a new kind of tool for diagnostics and research into lung diseases.

3D pulmospheres serve as a personalized and predictive multicellular model for assessment of antifibrotic drugs

“…Myofibroblasts are a hallmark of fibrotic disorders (12,13). Immunostaining of control and IPF lung pulmospheres with α-SMA affirmed the presence of myofibroblasts in IPF pulmospheres.…”

“…The ability of fibroblasts to invade has been recently recognized in IPF (13,26). Lamellipodia protrude from the leading edge of normally migrating cells.…”

The current position of surgical lung biopsy in the diagnosis of idiopathic pulmonary fibrosis

“…According to the current statement, BAL or TBB are no longer required for the diagnosis of IPF. A new BAL guideline has been recently published [69] as has as a new BAL cell culture technique for diagnostic samples [70]. Hopefully, BAL and TBB will gain greater acceptance in IPF diagnostics in the future with the development of more standardized techniques and innovative methodologies.…”

Fibrogenic Lung Injury Induces Non–Cell-Autonomous Fibroblast Invasion

“…The increased ability of fibroblasts to invade through extracellular matrix in IPF has recently been recognized as well. Compared with normal lung fibroblasts, which are poorly invasive, lung fibroblasts from patients with IPF have previously been demonstrated to have a robust capacity to invade through extracellular matrix (7,10,26). Fibroblast invasiveness may contribute to other fibrotic conditions as well, such as remodeling of the airways in asthma and remodeling of the joints in rheumatoid arthritis.…”