LAUSR

We thank Schymik et al.[1] for their interest in our article published in the July 2021 issue.[2] They raised several interesting points that we would like to address. First, the concern “in human monocyte-derived macrophages (HMDMs) treated with bacterial lipopolysaccharide (LPS) for up to 24 h, result in a significant reduction in insulin-like growth factor 2 mRNA-binding protein 2 (IGF2BP2) mRNA expression, while protein levels were not changed” is a very interesting consideration, which is different from what we claimed in the mouse bone marrow-derived macrophages (BMDMs). In order to understand why LPS regulates macrophage polarization differently between murine and human, we first performed similar experiments with what Schymik et al. did.[1] Short-time LPS treatment slightly induced the expression of IGF2BP2 mRNA (Figure 1A), while IGF2BP2 protein levels did not change (Figure 1B,C). Interestingly, the mRNA (Figure 1A) and protein (Figure 1D,E) levels of IGF2BP2 were significantly enhanced by LPS treatment for 36 and 48 h, which is consistent with mouse BMDMs. Notably, the plastic adhesion method was used instead of magnetic bead sorting to extract human monocytes, which might cause different phenotypes of HMDMs[3] by LPS treatment we got compared to Schymik et al. To exploit whether isolation and differentiation procedures result in a different activation pro-