PPARα-independent effects of nitrate supplementation on skeletal muscle metabolism in hypoxia

Hypoxia is a feature of many disease states where convective oxygen delivery is impaired, and is known to suppress oxidative metabolism. Acclimation to hypoxia thus requires metabolic remodelling, however hypoxia tolerance may be aided by dietary nitrate supplementation. Nitrate improves tissue oxygenation and has been shown to modulate skeletal muscle tissue metabolism via transcriptional changes, including through the activation of peroxisome proliferator- activated receptor alpha (PPARα), a master regulator of fat metabolism. Here we investigated whether nitrate supplementation protects skeletal muscle mitochondrial function in hypoxia and whether PPARα is required for this effect. Wild-type and PPARα knockout (PPARα-/-) mice were supplemented with sodium nitrate via the drinking water or sodium chloride as control, and exposed to environmental hypoxia (10% O2) or normoxia for 4 weeks. Hypoxia suppressed mitochondrial respiratory function in mouse soleus, an effect partially alleviated through nitrate supplementation, but occurring independently of PPARα. Specifically, hypoxia resulted in 26% lower mass specific fatty acid-supported LEAK respiration and 23% lower pyruvate-supported oxidative phosphorylation capacity. Hypoxia also resulted in 24% lower citrate synthase activity in mouse soleus, possibly indicating a loss of mitochondrial content. These changes were not seen, however, in hypoxic mice when supplemented with dietary nitrate, indicating a nitrate dependent preservation of mitochondrial function. Moreover, this was observed in both wild-type and PPARα-/- mice. Our results support the notion that nitrate supplementation can aid hypoxia tolerance and indicate that nitrate can exert effects independently of PPARα.This work was supported by King’s College London, the Biotechnology and Biological Sciences Research Councils [grant number: BB/F016581/1] and the Research Councils UK [grant number: EP/E500552/1]

Inorganic nitrate, hypoxia, and the regulation of cardiac mitochondrial respiration-probing the role of PPARα.

Dietary inorganic nitrate prevents aspects of cardiac mitochondrial dysfunction induced by hypoxia, although the mechanism is not completely understood. In both heart and skeletal muscle, nitrate increases fatty acid oxidation capacity, and in the latter case, this involves up-regulation of peroxisome proliferator-activated receptor (PPAR)α expression. Here, we investigated whether dietary nitrate modifies mitochondrial function in the hypoxic heart in a PPARα-dependent manner. Wild-type (WT) mice and mice without PPARα (Ppara-/-) were given water containing 0.7 mM NaCl (control) or 0.7 mM NaNO3 for 35 d. After 7 d, mice were exposed to normoxia or hypoxia (10% O2) for the remainder of the study. Mitochondrial respiratory function and metabolism were assessed in saponin-permeabilized cardiac muscle fibers. Environmental hypoxia suppressed mass-specific mitochondrial respiration and additionally lowered the proportion of respiration supported by fatty acid oxidation by 18% (P < 0.001). This switch away from fatty acid oxidation was reversed by nitrate treatment in hypoxic WT but not Ppara-/- mice, indicating a PPARα-dependent effect. Hypoxia increased hexokinase activity by 33% in all mice, whereas lactate dehydrogenase activity increased by 71% in hypoxic WT but not Ppara-/- mice. Our findings indicate that PPARα plays a key role in mediating cardiac metabolic remodeling in response to both hypoxia and dietary nitrate supplementation.-Horscroft, J. A., O'Brien, K. A., Clark, A. D., Lindsay, R. T., Steel, A. S., Procter, N. E. K., Devaux, J., Frenneaux, M., Harridge, S. D. R., Murray, A. J. Inorganic nitrate, hypoxia, and the regulation of cardiac mitochondrial respiration-probing the role of PPARα

Epitope-engineered human hematopoietic stem cells are shielded from CD123-targeted immunotherapy

Targeted eradication of transformed or otherwise dysregulated cells using monoclonal antibodies (mAb), antibody-drug conjugates (ADC), T cell engagers (TCE), or chimeric antigen receptor (CAR) cells is very effective for hematologic diseases. Unlike the breakthrough progress achieved for B cell malignancies, there is a pressing need to find suitable antigens for myeloid malignancies. CD123, the interleukin-3 (IL-3) receptor alpha-chain, is highly expressed in various hematological malignancies, including acute myeloid leukemia (AML). However, shared CD123 expression on healthy hematopoietic stem and progenitor cells (HSPCs) bears the risk for myelotoxicity. We demonstrate that epitope-engineered HSPCs were shielded from CD123-targeted immunotherapy but remained functional, while CD123-deficient HSPCs displayed a competitive disadvantage. Transplantation of genome-edited HSPCs could enable tumor-selective targeted immunotherapy while rebuilding a fully functional hematopoietic system. We envision that this approach is broadly applicable to other targets and cells, could render hitherto undruggable targets accessible to immunotherapy, and will allow continued posttransplant therapy, for instance, to treat minimal residual disease (MRD)

Search for CP Violation in the Decay Z -> b (b bar) g

About three million hadronic decays of the Z collected by ALEPH in the years 1991-1994 are used to search for anomalous CP violation beyond the Standard Model in the decay Z -> b \bar{b} g. The study is performed by analyzing angular correlations between the two quarks and the gluon in three-jet events and by measuring the differential two-jet rate. No signal of CP violation is found. For the combinations of anomalous CP violating couplings, ${\hat{h}}_b = {\hat{h}}_{Ab}g_{Vb}-{\hat{h}}_{Vb}g_{Ab}$ and $h^{\ast}_b = \sqrt{\hat{h}_{Vb}^{2}+\hat{h}_{Ab}^{2}}$, limits of \hat{h}_b < 0.59$and$h^{\ast}_{b} < 3.02$ are given at 95\% CL.Comment: 8 pages, 1 postscript figure, uses here.sty, epsfig.st

Phosphatidylserine Targets Single-Walled Carbon Nanotubes to Professional Phagocytes In Vitro and In Vivo

Broad applications of single-walled carbon nanotubes (SWCNT) dictate the necessity to better understand their health effects. Poor recognition of non-functionalized SWCNT by phagocytes is prohibitive towards controlling their biological action. We report that SWCNT coating with a phospholipid “eat-me” signal, phosphatidylserine (PS), makes them recognizable in vitro by different phagocytic cells - murine RAW264.7 macrophages, primary monocyte-derived human macrophages, dendritic cells, and rat brain microglia. Macrophage uptake of PS-coated nanotubes was suppressed by the PS-binding protein, Annexin V, and endocytosis inhibitors, and changed the pattern of pro- and anti-inflammatory cytokine secretion. Loading of PS-coated SWCNT with pro-apoptotic cargo (cytochrome c) allowed for the targeted killing of RAW264.7 macrophages. In vivo aspiration of PS-coated SWCNT stimulated their uptake by lung alveolar macrophages in mice. Thus, PS-coating can be utilized for targeted delivery of SWCNT with specified cargoes into professional phagocytes, hence for therapeutic regulation of specific populations of immune-competent cells

Search for R-Parity Violating Decays of Supersymmetric Particles in e+e−e^{+}e^{-} Collisions at Centre-of-Mass Energies near 183 GeV

Searches for pair-production of supersymmetric particles under the assumption that R-parity is violated via a single dominant $LL{\bar E}$, $LQ{\bar D}$ or ${\bar U} {\bar D} {\bar D}$ coupling are performed using the data collected by the \ALEPH\ collaboration at centre-of-mass energies of 181--184~\gev. The observed candidate events in the data are in agreement with the Standard Model expectations. Upper limits on the production cross-sections and lower limits on the masses of charginos, sleptons, squarks and sneutrinos are de rived