FADS2 and Granuloma: In our study, we noted that infection of BMM with HN878 up-regulated the expression of a larger number of host lipid metabolism genes, including Acsl1, Dhcr24, Acat2, Scd1 and Fads2. Recent studies from others and our laboratory have shown that infection by Mtb induces lipid droplet formation in human macrophages [43], and that elevated host lipid metabolism correlates with caseation in human TB granulomas [7,17].