miR-34a derived from adipocyte exosomes is delivered to macrophages and inhibits the expression of Krüppel-like factor 4 (KLF4) to prevent M2 polarisation, thus aggravating metabolic inflammation and insulin resistance induced by obesity.243 Of interest, exosomes from adipose tissue could promote adipogenesis and exacerbate obesity. This evidence concerns the gene KLF4 and obesity due to melanocortin 4 receptor deficiency.