ERBIN deficiency links STAT3 and TGF-β pathway defects with atopy in humans.

Nonimmunological connective tissue phenotypes in humans are common among some congenital and acquired allergic diseases. Several of these congenital disorders have been associated with either increased TGF-beta activity or impaired STAT3 activation, suggesting that these pathways might intersect and that their disruption may contribute to atopy. In this study, we show that STAT3 negatively regulates TGF-beta signaling via ERBB2-interacting protein (ERBIN), a SMAD anchor for receptor activation and SMAD2/3 binding protein. Individuals with dominant-negative STAT3 mutations (STAT3(mut)) or a loss-of-function mutation in ERBB2IP (ERBB2IP(mut)) have evidence of deregulated TGF-beta signaling with increased regulatory T cells and total FOXP3 expression. These naturally occurring mutations, recapitulated in vitro, impair STAT3-ERBIN-SMAD2/3 complex formation and fail to constrain nuclear pSMAD2/3 in response to TGF-beta. In turn, cell-intrinsic deregulation of TGF-beta signaling is associated with increased functional IL-4R alpha expression on naive lymphocytes and can induce expression and activation of the IL-4/IL-4R alpha/GATA3 axis in vitro. These findings link increased TGF-beta pathway activation in ERBB2IP(mut) and STAT3(mut) patient lymphocytes with increased T helper type 2 cytokine expression and elevated IgE.