'Proliferative' and 'synthetic' airway smooth muscle cells are overlapping populations

• Published in: Immunology and cell biology 2004-10, Vol.82 (5), p.471-478
• Main Authors: Sukkar, Maria B, Stanley, Anthony J, Blake, Anita E, Hodgkin, Philip D, Johnson, Peter R A, Armour, Carol L, Hughes, J Margaret
• Format: Article
• Language: English
• Subjects: airway smooth muscle; asthma; Bronchi - cytology; Cell Cycle; Cell Proliferation; Cells, Cultured; CFSE; Cytokines - biosynthesis; Flow Cytometry; GM‐CSF production; Granulocyte-Macrophage Colony-Stimulating Factor - biosynthesis; Humans; Interleukin-1 - pharmacology; Myocytes, Smooth Muscle - cytology; Myocytes, Smooth Muscle - metabolism; Myocytes, Smooth Muscle - secretion; Phenotype; proliferation; Tumor Necrosis Factor-alpha - pharmacology
• ISSN: 0818-9641; 1440-1711
• DOI: 10.1111/j.0818-9641.2004.01275.x

The extension of airway smooth muscle cell (ASMC) functions, from just contractile, to synthetic and/or proliferative states, is an important component of airway remodelling and inflammation in asthma. Whereas all these functions have been demonstrated in ASM, currently, it is not known whether ASMC can be differentiated on the basis of their proliferative and synthetic functions. We used flow‐cytometric techniques to determine, first, whether human ASMC are phenotypically heterogenous with regard to their secretory function, and second, the proliferative status of secretory cells. ASMC were induced to synthesize GM‐CSF by stimulation with IL‐1β and TNF‐α followed by 10% human serum. Flow‐cytometric detection of intracellular GM‐CSF revealed that only a proportion of cells in culture (∼ 20–60%) synthesize GM‐CSF. To determine the proliferative status of GM‐CSF producing cells, ASMC were pretreated with 5,6‐carboxyfluorescein diacetate succinimidyl ester (CFSE), a fluorescein based dye used to track cell division, prior to cytokine/serum stimulation. Simultaneous analysis of intracellular GM‐CSF and CFSE revealed that GM‐CSF producing cells were present in both the divided and undivided ASMC populations. Thus, cytokine production and proliferation occurred in overlapping ASMC populations and prior progression through the cell cycle was not essential for ASMC cytokine production.