Differential induction of CD38 expression by TNF- in asthmatic airway smooth muscle cells

Jude JA, Solway J, Panettieri RA Jr, Walseth TF, Kannan MS. Differential induction of CD38 expression by TNFin asthmatic airway smooth muscle cells. Am J Physiol Lung Cell Mol Physiol 299: L879–L890, 2010. First published August 6, 2010; doi:10.1152/ajplung.00021.2010.—The ADP-ribosyl cyclase activity of CD38, a membrane protein expressed in human airway smooth muscle (ASM) cells, generates cyclic ADP-ribose (cADPR), a Ca mobilizing agent. cADPR-mediated Ca responses to agonists are augmented in human ASM cells by TNF. CD38-deficient mice fail to develop airway hyperresponsiveness following intranasal TNFor IL-13 challenge, suggesting a role in asthma. The role of CD38 in human asthma remains unknown. We hypothesized that CD38 expression will be elevated in ASM cells from asthmatic donors (ASMA cells). CD38 mRNA and ADP-ribosyl cyclase activity were measured in cells maintained in growth-arrested conditions and exposed to vehicle or TNF(10–40 ng/ml). TNF-induced induction of CD38 expression was greater in ASMA than in ASM cells from nonasthmatic donors (ASMNA). In four of the six donors, basal and TNF-induced ERK and p38 MAPK activation were higher in ASMA than ASMNA cells. JNK MAPK activation was lower in ASMA than ASMNA cells. Nuclear NFB (p50 subunit) and phosphorylated c-Jun were comparable in cells from both groups, although nuclear c-Fos (part of the AP-1 complex) levels were lower in ASMA than ASMNA cells. NFB or AP-1 binding to their consensus sequences was comparable in ASMNA and ASMA cells, as are the decay kinetics of CD38 mRNA. The findings suggest that the differential induction of CD38 by TNFin ASMA cells is due to increased transcriptional regulation involving ERK and p38 MAPK activation and is independent of changes in NFB or AP-1 activation. The findings suggest a potential role for CD38 in the pathophysiology of asthma.