Epigenetic reprogramming of myeloid cells by infection or vaccination, termed trained immunity, confers non-specific protection from secondary infections. We characterized genome-wide transcriptome and histone modification profiles of human monocytes trained with β-glucan and identified induced expression of genes involved in glucose metabolism. Trained monocytes display high glucose consumption, lactate production, and NAD+/NADH ratio, reflecting a shift in the metabolism of trained monocytes with an increase in glycolysis dependent on the activation of mammalian target of rapamycin (mTOR) through a dectin-1/Akt/HIF1α pathway. Inhibition of Akt, mTOR, or HIF1α blocked monocyte induction of trained immunity, whereas the AMPK activator metformin inhibited the innate immune response to fungal infection. Finally, mice with a myeloid cell-specific defect in HIF1α were unable to mount trained immunity against bacterial sepsis. In conclusion, Akt/mTOR/HIF1α-dependent induction of aerobic glycolysis represents the metabolic basis of trained immunity.

Candidemia is the fourth most common cause of bloodstream infection, with a high mortality rate of up to 40%. Identification of host genetic factors that confer susceptibility to candidemia may aid in designing adjunctive immunotherapeutic strategies. We hypothesized that variation in immune genes may predispose to candidemia. We analyzed 118,989 SNPs across 186 loci known to be associated with immune-mediated diseases in the largest candidemia cohort to date of 217 patients of European ancestry and a group of 11,920 controls. The significant associations were validated by comparison with a disease-matched control group. We observed significant association between candidemia and SNPs in the CD58 (P = 1.97×10−11; OR = 4.68), LCE4A-C1orf68 (P = 1.98×10−10; OR = 4.25) and TAGAP (P = 1.84×10−8; OR = 2.96) loci. Individuals carrying two or more risk alleles had an increased risk for candidemia of 19.4-fold compared to individuals carrying no risk allele. While latent cornified envelope (LCE) genes contribute to mucosal integrity, the role of CD58 and TAGAP in host defense is unknown. Studies using transcriptomics, pathway analysis, and immunological validation showed that CD58 plays a role in the recognition and phagocytosis of Candida by macrophages, while TAGAP was involved in Candida-induced cytokine production. TAGAP-deficient mice were more susceptible to systemic Candida infection. We identified three novel genetic risk factors for candidemia, which we subsequently validated for their role in antifungal host defense.