0050 The Nemuri Antimicrobial Peptide Promotes Lipid Remodeling During Sickness Sleep

Abstract Introduction Sleep deprivation, aseptic injury, and infection activate the innate immune response and promote recovery sleep, or “sickness” sleep. In Drosophila, two NFκB genes, Dif and Relish, are required for promoting sleep following sleep deprivation and infection, respectively. nemuri, a sleep promoting antimicrobial peptide, is also induced by sleep deprivation and infection, and dependent on Dif and Relish, respectively, for its induction. NFκBs contribute to synthesis of membrane phospholipids through an IRE1/xbp1-dependent mechanism, possibly due to lipid bilayer stress caused by massive induction of antimicrobial peptides. We have observed that upregulation of nemuri in the brain severely reduces lipid droplets throughout the fly. Using lipidomics we tested whether upregulation of nemuri disrupts lipid homeostasis and thereby promotes sickness sleep. Methods Female flies over expressing nemuri (elavC155-Gal4>UAS-nemuri) and parental controls (elavC155-Gal4/+ and +/UAS-nemuri) were collected at ZT 2 and 14. Flies from different time points were pooled to eliminate circadian effects. Lipids isolated from heads were subjected to lipid profiling (n=4 samples per group) using Desi-Mass spectrometry. Positive and negative mode lipidomics data were subjected to multivariate orthogonal partial least squares-discriminant analysis (OPLSDA). Multivariate analysis was used to guide the classification of samples. Individual lipids were compared using non-parametric tests. Results Untargeted high resolution mass spectrometric lipid profiling of these flies indicated significant increases in lipids detected in both positive and negative modes with glycerophospholipids and sphingolipids comprising over 60% of those affected. Other lipid types that were increased included acylcarnitines, fatty acids, and glycerolipids. Cardiolipins in particular were uniquely increased by upregulation of nemuri, suggesting a disruption of mitochondrial function. Reducing lipid bilayer stress reduced excessive sleep in nemuri over-expressing flies. Conclusion These findings indicate an effect of nemuri on lipid remodeling in plasma membranes. Addressing disruption of lipid homeostatic factors could resolve excess sleepiness or fatigue that occurs with chronic illness. Support (if any) NIH R01NS124698 "Interactions between the immune response and lipid homeostasis in regulating sleep during sickness"