IL-4 and IL-13 act on human lung fibroblasts through specific receptors dif
fering in their composition. Indeed, the gammac chain is constitutively exp
ressed in tumor lung myofibroblast but not in normal cells, Here, we have a
nalysed the signal transduction induced by IL-4 and IL-13 in both cell type
s, in order to better understand the molecular mechanisms underlying tumor
stromal development. The IL-4R alpha chain is constitutively phosphorylated
and pre-associated with the JAK1 protein in both cell types. In normal cel
ls, we detected the activation of the classic IRS-2 or JAK1/STAT6 pathways,
the phosphorylation of JAK2, while Tyk2 was constitutively phosphorylated
and not modified by both cytokines, In addition to these pathways, in lung
tumor myofibroblasts, IL-4 and IL-13 induced the phosphorylation of JAK3 an
d increased the phosphorylation of Tyk2, Interestingly, in both cell types
IL-4 and IL-13 triggered an unusual pattern of STAT1 and STAT3 activation.
These events probably correspond to a tissue-specific signaling important f
or the immunoregulatory functions of airways fibroblasts, Indeed, the infla
mmatory-like pattern of STATs signaling triggered by IL-4 and IL-13 in thes
e cells may favor the homing of inflammatory and/or metastatic cells. In lu
ng myofibroblasts, these properties could be modified through the different
pattern of JAK activation.