Recent studieshave shown steroidal compounds such as 25-hydroxycholesterol(compound 4, Figure 1) are generated by macrophages to regulate an anti-inflammatorycircuit that maintains mitochondrial integrity and prevents DNA sensorprotein Absent In Melanoma 2 (AIM2) inflammasome activation.42 The study found that increasing the macrophagecholesterol content is sufficient to trigger type I interferon restrainsinterleukin-1β (IL-1β) release in a AIM2-dependent manner,indicating compound 4 can regulate inflammation in chronicdiseases like obesity and metabolic syndrome. The gene discussed is AIM2; the disease is obesity due to melanocortin 4 receptor deficiency.