IL1R1 and obesity due to melanocortin 4 receptor deficiency: Prabhakara R et al (20) found that in obesity, the inflammatory mediator IL-1 β reaches the bone marrow through IL-1R and stimulates the growth of hematopoietic progenitor cells in vitro through experiments measuring the proliferation of BM progenitor cells in a mouse model, resulting in the production of more monocytes.