Influenza is a significant health concern worldwide. Viral infection induces local and systemic activation of the immune system causing attendant changes in metabolism. High-resolution metabolomics (HRM) uses advanced mass spectrometry and computational methods to measure thousands of metabolites inclusive of most metabolic pathways. We used HRM to identify metabolic pathways and clusters of association related to inflammatory cytokines in lungs of mice with H1N1 influenza virus infection. Infected mice showed progressive weight loss, decreased lung function, and severe lung inflammation with elevated cytokines [interleukin (IL)-1β, IL-6, IL-10, tumor necrosis factor (TNF)-α, and interferon (IFN)-γ] and increased oxidative stress via cysteine oxidation. HRM showed prominent effects of influenza virus infection on tryptophan and other amino acids, and widespread effects on pathways including purines, pyrimidines, fatty acids, and glycerophospholipids. A metabolome-wide association study (MWAS) of the aforementioned inflammatory cytokines was used to determine the relationship of metabolic responses to inflammation during infection. This cytokine-MWAS (cMWAS) showed that metabolic associations consisted of distinct and shared clusters of 396 metabolites highly correlated with inflammatory cytokines. Strong negative associations of selected glycosphingolipid, linoleate, and tryptophan metabolites with IFN-γ contrasted strong positive associations of glycosphingolipid and bile acid metabolites with IL-1β, TNF-α, and IL-10. Anti-inflammatory cytokine IL-10 had strong positive associations with vitamin D, purine, and vitamin E metabolism. The detailed metabolic interactions with cytokines indicate that targeted metabolic interventions may be useful during life-threatening crises related to severe acute infection and inflammation.

Manganese (Mn) is an abundant redox-active metal with well-characterized mitochondrial accumulation and neurotoxicity due to excessive exposures. Mn is also an essential co-factor for the mitochondrial antioxidant protein, superoxide dismutase-2 (SOD2), and the range for adequate intake established by the Institute of Medicine Food and Nutrition Board is 20% of the interim guidance value for toxicity by the Agency for Toxic Substances and Disease Registry, leaving little margin for safety. To study toxic mechanisms over this critical dose range, we treated human neuroblastoma SH-SY5Y cells with a series of MnCl2 concentrations (from 0 to 100 μM) and measured cellular content to compare to human brain Mn content. Concentrations ≤10 μM gave cellular concentrations comparable to literature values for normal human brain, whereas concentrations ≥50 μM resulted in values comparable to brains from individuals with toxic Mn exposures. Cellular oxygen consumption rate increased as a function of Mn up to 10 μM and decreased with Mn dose ≥50 μM. Over this range, Mn had no effect on superoxide production as measured by aconitase activity or MitoSOX but increased H2O2 production as measured by MitoPY1. Consistent with increased production of H2O2, SOD2 activity, and steady-state oxidation of total thiol increased with increasing Mn. These findings have important implications for Mn toxicity by re-directing attention from superoxide anion radical to H2O2-dependent mechanisms and to investigation over the entire physiologic range to toxicologic range. Additionally, the results show that controlled Mn exposure provides a useful cell manipulation for toxicological studies of mitochondrial H2O2 signaling.

The retinal pigment epithelium (RPE) is a particularly vulnerable tissue to age‐dependent degeneration. Over the life span, the RPE develops an expanded endo‐lysosomal compartment to maintain the high efficiency of phagocytosis and degradation of photoreceptor outer segments (POS) necessary for photoreceptor survival. As the assembly and activation of the mechanistic target of rapamycin complex 1 (mTORC1) occur on the lysosome surface, increased lysosome mass with aging leads to higher mTORC1 activity. The functional consequences of hyperactive mTORC1 in the RPE are unclear. In the current study, we used integrated high‐resolution metabolomic and genomic approaches to examine mice with RPE‐specific deletion of the tuberous sclerosis 1 ( Tsc1 ) gene which encodes an upstream suppressor of mTORC1. Our data show that RPE cells with constitutively high mTORC1 activity were reprogramed to be hyperactive in glucose and lipid metabolism. Lipolysis was suppressed, mitochondrial carnitine shuttle was inhibited, while genes involved in fatty acid (FA) biosynthesis were upregulated. The metabolic changes occurred prior to structural changes of RPE and retinal degeneration. These findings have revealed cellular events and intrinsic mechanisms that contribute to lipid accumulation in the RPE cells during aging and age‐related degeneration.