TGFβ1, an epidermal controller of skin dendritic cell homeostasis.

Transforming growth factor-β1 (TGFβ1) is generally regarded as an anti-inflammatory cytokine. However, previous studies suggest that TGFβ1 can promote immune responses under certain conditions. In this issue, Mohammed et al. report that epidermal keratinocyte-derived TGFβ1 alone can alter homeostasis of multiple cutaneous dendritic cell (DC) subsets, which may enhance skin inflammation. These findings may provide a better understanding of the pathogenesis of inflammatory skin disorders such as psoriasis, although how keratinocyte-derived TGFβ1 regulates cutaneous DCs under physiological and inflammatory conditions should be further addressed.