I wonder if this study has implication for HIV research? People with HIV sometimes have a condition called lypodystrophy which results in a loss of yellow fat and a disproportionate increase in brown fat located mainly around the neck and in the upper back. Macrophages attack HIV which is a virus that targets the immune system. I wonder if maybe the fact that Macrophages are found in brown fat confers a level of protection allowing these cells to be less affected by the HIV infection. Maybe they are directly involved in the fight against HIV.