This suggests that the adipose tissue IL-18R/IL-18 expression is increased in obesity with insulin resistance [57], probably due to the action of leptin, which increases IL-18 secretion in human monocytes via modulation of the caspase-1 inflammasome, without affecting the IL-18 and IL-1β mRNA levels, or IL-1β secretion. This evidence concerns the gene IL18R1 and obesity due to melanocortin 4 receptor deficiency.