Impaired signaling pathways on Berardinelli-Seip congenital lipodystrophy macrophages during Leishmania infantum infection.

Berardinelli-Seip congenital lipodystrophy (CGL), a rare autosomal recessive disorder, is characterized by a lack of adipose tissue. Infections are one of the major causes of CGL individuals' premature death. The mechanisms that predispose to infections are poorly understood. We used Leishmania infantum as an in vitro model of intracellular infection to explore mechanisms underlying the CGL infection processes, and to understand the impact of host mutations on Leishmania survival, since this pathogen enters macrophages through specialized membrane lipid domains. The transcriptomic profiles of both uninfected and infected monocyte-derived macrophages (MDMs) from CGL (types 1 and 2) and controls were studied. MDMs infected with L. infantum showed significantly downregulated expression of genes associated with infection-response pathways (MHC-I, TCR-CD3, and granzymes). There was a transcriptomic signature in CGL cells associated with impaired membrane trafficking and signaling in response to infection, with concomitant changes in the expression of membrane-associated genes in parasites (e.g. δ-amastins). We identified pathways suggesting the lipid storage dysfunction led to changes in phospholipids expression and impaired responses to infection, including immune synapse (antigen presentation, IFN-γ signaling, JAK/STAT); endocytosis; NF-kappaB signaling; and phosphatidylinositol biosynthesis. In summary, lipid metabolism of the host plays an important role in determining antigen presentation pathways.