As IL-33 is well known to induce the polarisation of alternatively activated (M2-like) macrophages in diseases such as asthma [30] and obesity [31], and M2-like microglia cells contribute to neuroprotection [32], expression of ST2 by microglia cells therefore may suggest that IL-33 plays an important role in MS development through modulating the polarisation of microglia cells in the CNS. This evidence concerns the gene IL33 and obesity due to melanocortin 4 receptor deficiency.