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

Lyons et al. show that STAT3 negatively regulates TGF-β signaling via ERBIN and that cell-intrinsic deregulation of TGF-β pathway activation promotes the IL-4/IL-4Rα/GATA3 axis to support atopic phenotypes 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-β 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-β 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-β 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-β. In turn, cell-intrinsic deregulation of TGF-β signaling is associated with increased functional IL-4Rα expression on naive lymphocytes and can induce expression and activation of the IL-4/IL-4Rα/GATA3 axis in vitro. These findings link increased TGF-β pathway activation in ERBB2IP^mut and STAT3^mut patient lymphocytes with increased T helper type 2 cytokine expression and elevated IgE.

Dendritic cell and T cell responses in children with food allergy

BACKGROUND

Food allergy (FA) and eosinophilic oesophagitis (EE) are increasingly common clinical problems. Dendritic cells (DCs) are key regulators of the sensitization and effector phases of allergic immune responses, but their role in these diseases is largely unknown.

OBJECTIVE

To evaluate for alterations in the phenotype and function of DCs in children with IgE-mediated milk allergy or EE compared with their non-affected siblings.

METHODS

Plasmacytoid DCs (pDCs) and myeloid DCs (mDCs) were prepared from peripheral blood of children with milk allergy (FA), EE, and non-affected siblings (CON). Purified pDCs and mDCs were cultured alone or with autologous CD4(+) lymphocytes. Cytokine levels in plasma, or culture supernatants following stimulation, were measured using multiplex array immunoassay. Cell-surface molecule expression was determined by flow cytometry.

RESULTS

DCs from FA subjects produced greater levels of pro-inflammatory cytokines (IL-6, TNF-α), granulocyte macrophage-colony forming factor, and mDC-derived IL-10 compared with controls following allergen exposure. T(H) 2 but not T(H) 1 cytokines were spontaneously produced in DC-CD4(+) T cell co-cultures from children with FA and were not significantly increased after stimulation with milk extract, suggesting an ongoing activation in vivo. This hypothesis was further supported by evidence for elevated IL-5 and IL-13 protein in the plasma of children with both FA and EE. The only significant DC phenotypic differences were: (1) reduced levels of CD80 in EE subjects and (2) FcɛRI expression that correlated with serum IgE levels in both groups of subjects.

CONCLUSION

This study suggests that DCs from children with FA and EE produce more pro-inflammatory cytokines, and that their CD4(+) T cells are spontaneously activated to produce T(H) 2 cytokines in the presence of FcɛRI-bearing DCs.