Published ahead of print on October 20, 2009 Am. J. Respir. Cell Mol. Biol. 2009, doi:10.1165/rcmb.2008-0373OC
Submitted on October 3, 2008 Expression of TRPC6 Channels in Human Lung MacrophagesTricia K Finney-Hayward1,1 Airways Disease, National Heart and Lung Institute, Faculty of Medicine, Imperial College London, London, United Kingdom, 2 Respiratory Diseases Area, Novartis Institutes for BioMedical Research, West Sussex, United Kingdom, 3 Histopathology, National Heart and Lung Institute, Faculty of Medicine, Imperial College London, London, United Kingdom, 4 Chest Clinic, King Edward King VII Hospital, Berkshire, United Kingdom, 5 Chest and Allergy Clinic, St Mary’s Hospital, Imperial College Healthcare NHS Trust, London, United Kingdom, 6 National Heart and Lung Institute and Imperial College London, London, United Kingdom * To whom correspondence should be addressed. E-mail: p.j.barnes{at}imperial.ac.uk.
Chronic obstructive pulmonary disease (COPD) is associated with pulmonary inflammation with increased numbers of macrophages located in the parenchyma. These macrophages have the capacity to mediate the underlying pathophysiology of COPD therefore a better understanding of their function in chronic inflammation associated with this disease is vital. Ion channels regulate many cellular functions; however their role in macrophages is unclear. This study examined the expression and function of transient receptor potential (TRP) channels in human macrophages. Human alveolar macrophages and lung tissue macrophages expressed increased mRNA and protein for TRPC6 when compared with monocytes and monocyte-derived-macrophages. Moreover, TRPC6 mRNA expression was significantly elevated in alveolar macrophages from COPD patients compared to control subjects. There were no differences in mRNA for TRPC3 or TRPC7. Although mRNA for TRPM2 and TRPV1 was detected in these cells, protein expression could not be determined. Fractionation of lung derived-macrophages demonstrated that TRPC6 protein was more highly expressed by smaller macrophages compared with larger macrophages. Using whole-cell patch clamp electrophysiology, TRPC6-like currents were measured in both macrophage sub-populations with appropriate biophysical and basic pharmacological profiles. These currents were active under basal conditions in the small macrophages. These data suggest that TRPC6-like channels are functional on human lung macrophages and may be associated with COPD. Key words: human monocytes/macrophages cell surface molecules Inflammation
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