CD14 regulates the metabolomic profiles of distinct macrophage subsets under steady and activated states.

Macrophages play pivotal roles during homeostasis and inflammation. They sense exogenous and endogenous molecular patterns via surface and intracellular receptors, which trigger innate immune responses. CD14 is a co-receptor for lipopolysaccharide (LPS), but also drives macrophage responses to Tityus serrulatus scorpion venom (TsV). Cellular activation is tightly coupled with metabolism that sustain their polarization and generate antimicrobial and signaling molecules. Macrophage's origin and nature of stimulus are critical for their responses, but whether these factors impact macrophage metabolism is unknown. Moreover, the regulation of intracellular metabolism by CD14 has not been assessed. Using an untargeted metabolomics approach, we determined the longitudinal metabolic responses of peritoneal (PMs) and bone marrow derived macrophages (BMDMs) stimulated with LPS and TsV for 12 h. These data revealed alterations on the relative levels of several metabolites and pathways related to amino acids, nucleotides, lipids, and vitamins. Our data suggest activation of selenoamino acid metabolism and increased abundance of selenomethionine in both cell subsets stimulated with LPS. Moreover, the results suggest a differential activity of vitamin B3 metabolism pathway in response to TsV stimulus, with differences on regulation of the relative levels of nicotinamide mononucleotide and deamino-NAD+. CD14 deficiency affects the metabolome of both cell subsets at steady state. Moreover, CD14 was required for arginine consumption in PMs stimulated with LPS, but not TsV or by BMDMs stimulated by both stimuli. Importantly, the data suggest that CD14 mediates the accumulation of lipids in both macrophage subsets stimulated with LPS, providing insights into the potential role of CD14 for the development of metabolic diseases. We conclude that macrophages acquire a spectrum of metabolic profiles that depend on the origin of these cells, the nature of the stimuli and signaling by innate immune receptors.