Biology subjects

Cartwright, D.

Publications and source records attributed to Cartwright, D..

3 recordsLinked to original sources

bioRxiv2019

Nicotinamide riboside augments the human skeletal muscle NAD+ metabolome and induces transcriptomic and anti-inflammatory signatures in aged subjects: a placebo-controlled, randomized trial

NAD+ is modulated by conditions of metabolic stress and has been reported to decline with aging, but human data are sparse. Nicotinamide riboside (NR) supplementation ameliorates metabolic dysfunction in rodents. We aimed to establish whether oral NR supplementation in aged participants can increase the skeletal muscle NAD+ metabolome, and questioned if tissue NAD+ levels are depressed with aging. We supplemented 12 aged men with NR 1g per day for 21-days in a placebo-controlled, randomized, double-blind, crossover trial. Targeted metabolomics showed that NR elevated the muscle NAD+ metabolome, evident by increased nicotinic acid adenine dinucleotide and nicotinamide clearance products. Muscle RNA sequencing revealed NR-mediated downregulation of energy metabolism and mitochondria pathways. NR also depressed levels of circulating inflammatory cytokines. In an additional study, 31P magnetic resonance spectroscopy-based NAD+ measurement in muscle and brain showed no difference between young and aged individuals. Our data establish that oral NR is available to aged human muscle and identify anti-inflammatory effects of NR, while suggesting that NAD+ decline is not associated with chronological aging per se in human muscle or brain.

clinical trials↗

bioRxiv2019

Induction of the nicotinamide riboside kinase NAD+ salvage pathway in skeletal muscle of H6PDH KO mice

BackgroundHexose-6-Phosphate Dehydrogenase (H6PDH) is a generator of NADPH in the Endoplasmic/Sarcoplasmic Reticulum (ER/SR). Interaction of H6PDH with 11{beta}-hydroxysteroid dehydrogenase type 1 provides NADPH to support oxo-reduction of inactive to active glucocorticoids, but the wider understanding of H6PDH in ER/SR NAD(P)(H) homeostasis is incomplete. Muscle specific lack of H6PDH results in a deteriorating skeletal myopathy, altered glucose homeostasis, ER stress and activation of the unfolded protein response. Here we further assess muscle responses to H6PDH deficiency to delineate pathways that may underpin myopathy and link SR redox status to muscle wide metabolic adaptation.\n\nMethodsWe analysed skeletal muscle from H6PDH knockout (H6PDKO), H6PDH and NRK2 double knockout (DKO) and wild-type (WT) mice. H6PDKO mice were supplemented with the NAD+ precursor nicotinamide riboside. Skeletal muscle samples were subject to biochemical analysis including NAD(H) measurement, LC/MS based metabolomics, Western immunoblotting, and high resolution mitochondrial respirometry. Genetic and supplement models were assessed for degree of myopathy compared to H6PDKO.\n\nResultsH6PDKO skeletal muscle showed adaptations in the routes regulating nicotinamide and NAD+ biosynthesis, with significant activation of the Nicotinamide Riboside Kinase 2 (NRK2) pathway. Associated with changes in NAD+ biosynthesis H6PDKO muscle had impaired mitochondrial respiratory capacity with altered mitochondrial acylcarnitine and acetyl CoA metabolism. Boosting NAD+ levels through the NRK2 pathway using the precursor nicotinamide riboside had no effect to mitigate ER stress and dysfunctional mitochondrial respiratory capacity or Acetyl-CoA metabolism. Similarly, H6PDKO/NRK2 double KO mice did not display an exaggerated timing or severity of myopathy or overt change in mitochondrial metabolism despite depression of NAD+ availability.\n\nConclusionsThese findings suggest a complex metabolic response to changes to muscle SR NADP(H) redox status that result in impaired mitochondrial energy metabolism and activation of cellular NAD+ salvage pathways. It is possible that SR can sense and signal perturbation in NAD(P)(H) that cannot be rectified in the absence of H6PDH. Whether NRK2 pathway activation is a direct response to changes in SR NAD(P)(H) availability or adaptation to deficits in metabolic energy availability remains to be resolved.

physiology↗

bioRxiv2018

Broad spectrum capture of clinical pathogens using engineered Fc-Mannose-Binding Lectin (FcMBL) enhanced by antibiotic treatment

FcMBL, an engineered version of the blood opsonin mannose-binding lectin (MBL) that contains the carbohydrate recognition domain (CRD) and flexible neck regions of MBL fused to the Fc portion of human IgG1, has been shown to bind various microbes and pathogen-associated molecular patterns (PAMPs). FcMBL also has been used to create an enzyme-linked lectin sorbent assay (ELLecSA) for use as a rapid (< 1 hr) diagnostic of bloodstream infections. Here we extended this work by using the ELLecSA to test FcMBLs ability to bind to more than 200 different isolates from over 100 different pathogen species. FcMBL bound to 86% of the isolates and 110 of the 122 (90%) different pathogen species tested, including bacteria, fungi, viruses, and parasites. It also bound to PAMPs including, lipopolysaccharide endotoxin (LPS) and lipoteichoic acid (LTA) from Gram-negative and Gram-positive bacteria, as well as lipoarabinomannan (LAM) and phosphatidylinositol mannoside 6 (PIM6) from Mycobacterium tuberculosis. The efficiency of pathogen detection and variation between binding of different strains of the same species also could be improved by treating the bacteria with antibiotics prior to FcMBL capture to reveal previously concealed binding sites within the bacterial cell wall. As FcMBL can bind to pathogens and PAMPs in urine as well as blood, its broad-binding capability could be leveraged to develop a variety of clinically relevant technologies, including infectious disease diagnostics, therapeutics, and vaccines.

immunology↗