Search

Although DNA damage is intricately linked to metabolism, the metabolic alterations that occur in response to DNA damage are not well understood. We use a DNA repair–deficient model of ERCC1-XPF in Caenorhabditis elegans to gain insights on how genotoxic stress drives aging. Using multi-omic approach, we discover that nuclear DNA damage promotes mitochondrial β-oxidation and drives a global loss of fat depots. This metabolic shift to β-oxidation generates acetyl–coenzyme A to promote histone hyperacetylation and an associated change in expression of immune-effector and cytochrome genes. We identify the histone acetyltransferase MYS-1, as a critical regulator of this metabolic-epigenetic axis. We show that in response to DNA damage, polyunsaturated fatty acids, especially arachidonic acid (AA) and AA-related lipid mediators, are elevated and this is dependent on mys-1 . Together, these findings reveal that DNA damage alters the metabolic-epigenetic axis to drive an immune-like response that can promote age-associated decline.

Apolipoprotein E4 (APOE) is the strongest genetic risk factor for Alzheimer’s disease (AD). Our lipidomic analysis identified a common phospholipid signature with a high level of correlation between APOEε3/3 and APOEε4/4 AD postmortem brain samples and native lipoproteins isolated from astrocyte conditioned media of mice expressing human APOE3 or APOE4. Behavioral testing demonstrated that native E3 lipoproteins were more effective than E4 at ameliorating the harmful effects of Aβ on cognition. We posit that APOE isoform-specific differences in the phospholipid composition of native lipoproteins prompt a differential microglial response. Using time-lapse in vivo two-photon imaging we compared the effect of E3 or E4 infused with Aβ and determined that E3 lipoproteins induced a faster microglial migration towards Aβ. To determine how E3 and E4 lipoproteins affect microglial transcriptome in response to Aβ we performed bulk and single cell RNA-seq of WT and Trem2ko mice. We show that compared to E4, cortical infusion of E3 lipoproteins upregulated a higher proportion of genes associated with an activated immune response accompanied by a downregulation of homeostatic genes. scRNA-seq identified microglia-specific clusters affected by Trem2 deficiency suggesting that lack of Trem2 impairs the transition of microglia from homeostatic to an activated state. Compared to E3, E4-expressing microglia showed a reduced Aβ uptake that was additionally aggravated by Trem2 deficiency. Together, our findings have elucidated unique phenotypic and transcriptional differences in the microglial response to Aβ in the presence of E3 or E4 lipoproteins which could impact AD pathogenesis.

Polymorphonuclear myeloid derived suppressor cells (PMN-MDSC) are critically important for the regulation of immune responses in cancer, promotion of tumor progression, and metastases. PMN-MDSC contribute to the failure of cancer therapies and their presence in cancer patients correlates with a poor prognosis. However, despite the recent advances in understanding of the PMN-MDSC biology, the mechanisms responsible for their suppressive functions are not well defined. The understanding of these mechanisms is critical important for the development of therapeutic strategies for the specific targeting of PMN-MDSC in cancer. Here, we report a massive accumulation of lipids in PMN-MDSC from tumor bearing mice and from cancer patients, compared to normal neutrophils from tumor free mice and healthy donors, respectively. The content of lipids was much higher in PMN-MDSC infiltrating the tumor. The accumulation of lipids was mediated by the exclusive up-regulation of the fatty acid transporter 2 (FATP2) in PMN-MDSC. The deletion of FATP2 abrogated the suppressive activity of PMN-MDSC in spleens and tumors. The selective pharmacological inhibition of FATP2 altered the activity of PMN-MSC and delayed tumor progression in mice. Importantly, FATP2 inhibition in PMN-MDSC favored tumor regression in mice when combined with checkpoint inhibitors. In conclusion, we show that FATP2 regulates the immune suppressive activity of PMN-MDSC and may represent a new target to selectively inhibit the functions of PMN-MDSC and to improve the effect of immunotherapy.

Increased ventilation is a general response to shock that may help to maintain cardiac output by improving venous return to the heart. The central stimulus for this increase in ventilation involves the production of S-nitroso-L-cysteine from more ubiquitous precursor S-nitrothiols in the medulla of the brain. Changes in dietary nitrite and nitrate have been shown to increase tissue levels of S-nitrosothiols and to improve survival in models of myocardial infarction. We hypothesize that increased dietary intake of nitrite or nitrate will enhance the ventilatory response in hemorrhage and thereby increase the time of survival. The goal of this project was to adequate methodology for the detection of S-nitrosylated proteins in tissues. A sensitive and specific method for the detection of S-nitrosylated proteins in tissues based on photolysis/immuno-spin-trapping analysis of DMPO thioethers has been developed. The applicability of the method for the quantitative assessments of Snitrosylated proteins in tissues has been tested and confirmed. The ability of dihydrolipoic acid and lipoic acid (LA) plus lipoamide dehydrogenase and NADH to denitrosate S-nitrosocaspase 3 (CASP-SNO) and regulate apoptosis in HepG2 cells has been established.

this study evaluated esophageal radioprotection by the Gramicidin S (GS) derived-nitroxide, JP4-039, a mitochondrial targeting peptide-isostere covalently-linked to 4-amino-Tempo, delivered in a novel swallowed oil-based (F15) formulation.C57BL/6HNsd female mice received intraesophageal F15 formulation containing JP4-039 (4 mg/ml in 100 microl volumes) 10 minutes before 28 or 29 Gy upper body irradiation compared to MnSOD-PL (100 microl containing 100 microg plasmid) 24 hours prior to irradiation. Subgroups received 1 × 10(7) C57BL/6HNsd, GFP(+) male bone marrow cells intravenously 5 days after irradiation.JP4-039/F15 or MnSOD-PL increased survival compared to irradiated controls (p0.0001 for either). Marrow injection further increased survival (p=0.0462 and 0.0351, respectively). Esophagi removed at 1, 3, 7, 14, 24, or 60 days showed bone marrow-derived cells in the esophagi.intraesophageal GS-nitroxide radioprotection is mediated primarily through recovery of endogenous esophageal progenitor cells.

Ionizing irradiation-induced cellular and tissue damage is mediated in part by resultant radiochemical reactions and resultant oxidative stress. Irradiation-induced reactive oxygen and nitrogen species include: superoxide, nitric oxide, hydroxyl radical and hydrogen peroxide. The biochemical combination of superoxide and nitric oxide radicals forms peroxynitrite, a potent oxidant known to induce lipid peroxidation.The antioxidant capacity and lipid peroxidation of the esophagus were determined following irradiation.In the present studies, measurements of total antioxidant capacity did not change in the esophagus of control irradiated or control plasmid pNGVL3-PL intraesophageally-injected mice. In contrast, manganese superoxide dismutase-plasmid/liposome (MnSOD-PL) intraesophageally-treated mice showed a significant increase in antioxidant capacity persisting for seven days. Lipid peroxidative changes induced in the control irradiated mouse esophagus decreased over seven days after irradiation of C3H/HeNHsd mice exposed to 37 Gy in a single fraction. MnSOD-PL radioprotective gene therapy administered intraorally 24 hours prior to irradiation did not significantly reduce the kinetics of induction of total peroxidated lipids over the first seven days after irradiation but did decrease lipid peroxidation at days 14 and 21.These studies demonstrate the antioxidant function of MnSOD-PL gene therapy to the esophagus, which is detectable as a reduction in irradiation-induced lipid peroxidation.