Project description:Proving functionality in the host environment is a crucial step in antimicrobial development pipelines. Antibiotics targeting fatty acid synthesis (FASII) of the major pathogen Staphylococcus aureus actively inhibit FASII but do not prevent in vivo growth, as bacteria compensate the FASII block by using environmental fatty acids. We used proteomics and phosphoproteomics to elucidate S. aureus responses to anti-FASII in host-relevant conditions. S. aureus responded to anti-FASII treatment in serum by massive reprogramming. A striking inverse correlation was observed in anti-FASII-adapted S. aureus, between amounts of stress response proteins that increase, and virulence factors that decrease. These findings suggest that anti-FASII adapted cells might be better prepared for survival and less equipped to damage the host. Infection by anti-FASII-adapted versus non-treated S. aureus was challenged in the Galleria mellonella model. Time to mortality was longer in insects infected by anti-FASII-treated bacteria compared to those infected by non-treated S. aureus. However, bacterial counts in infected dead insects were comparable for both groups. These results support the hypothesis that higher stress response and lower virulence factor expression, as shown here in FASII-antibiotic-adapted bacteria, may set the stage for persistent infection
Project description:Circulating trimethylamine N-oxide (TMAO) participates in the pathogenesis of cardio-metabolic diseases, with hepatic flavin-containing monooxygenase 3 (FMO3) originally regarded as the primary source of TMAO production. Here, we demonstrate that white adipose tissue (WAT) expressed FMO3 and its derived metabolic product TMAO causatively contribute to the systemic elevation of TMAO levels, WAT dysfunction, and metabolic diseases in ageing. We showed that FMO3 expression and TMAO levels are upregulated in WAT of naturally ageing animals and human subjects, as well as in a DNA damage-induced senescent adipocyte model, but not in the liver. This upregulation is due to p53 activation in mice and could be mitigated by calorie restriction in humans. Adipocyte-specific ablation of FMO3 attenuates TMAO accumulation in WAT and circulation, leading to enhanced glucose metabolism, energy homeostasis, and lipid regulation in aged and high-fat diet-induced obese mice. Transcriptomic and histological analysis link these metabolic improvements to reduced senescence, fibrosis, and inflammation in WAT as well as a decrease in adipose-resident macrophages. LiP-small molecule mapping (LiP-SMap) analysis identified numerous novel TMAO-interacting proteins implicated in inflammasome activation within white adipocytes and macrophages. Mechanistically, TMAO facilitates inflammasome activation by binding to the inflammasome adaptor protein apoptosis-associated speck-like protein containing A CARD (ASC), thereby inducing its expression, caspase-1 activation, and subsequent interleukin-1β (IL-1β) production. Our findings uncover a pivotal role for adipocyte FMO3 in modulating TMAO production and WAT dysfunction by promoting inflammasome activation in ageing via an autocrine and paracrine manner.