Transducin-like enhancer of split-1 is expressed and functional in human macrophages.

Macrophages display heterogeneous phenotypes, including the classical M1 proinflammatory and the alternative M2 anti-inflammatory polarization states. The transducin-like enhancer of split-1 (TLE1) is a transcriptional corepressor whose functions in macrophages have not been studied yet. We report that TLE1 is highly expressed in human alternative macrophages in vitro and in atherosclerotic plaques as well as in adipose tissue M1/M2 mixed macrophages. TLE1 silencing in alternative macrophages decreases the expression of the M2 markers IL-1Ra and IL-10, while it exacerbates TNFα and CCL3 induction by lipopolysaccharide. Hence, TLE1 is expressed in human macrophages where it has potential anti-inflammatory and alternative phenotype promoting properties.