Such an elegant finding. I only wish they did slightly more to validate the result further. Depleting all macrophages is a fairly drastic step. Heck, you dont even know what other tissue this affected. Theres no correlation that only liver macrophages or their iron or neuronal connections were the responsible system for the disruption observed.
one of the articles lines is more generally interesting 'In mammals, neurons in the spleen can communicate with macrophages, and in both mammals and birds, these neurons also connect to the central nervous system.'.