Aging is associated with chronic innate immune activation and dysregulation of monocyte phenotype and function

Chronic inflammation in older individuals is thought to contribute to inflammatory, age‐related diseases. Human monocytes are comprised of three subsets (classical, intermediate and nonclassical subsets), and despite being critical regulators of inflammation, the effect of age on the functionality of monocyte subsets remains to be fully defined. In a cross‐sectional study involving 91 healthy male (aged 20–84 years, median 52.4) and 55 female (aged 20–82 years, median 48.3) individuals, we found age was associated with an increased proportion of intermediate and nonclassical monocytes (P = 0.002 and 0.04, respectively) and altered phenotype of specific monocyte subsets (e.g. increased expression of CD11b and decreased expression of CD38, CD62L and CD115). Plasma levels of the innate immune activation markers CXCL10, neopterin (P < 0.001 for both) and sCD163 (P = 0.003) were significantly increased with age. Whilst similar age‐related changes were observed in both sexes, monocytes from women were phenotypically different to men [e.g. lower proportion of nonclassical monocytes (P = 0.002) and higher CD115 and CD62L but lower CD38 expression] and women exhibited higher levels of CXCL10 (P = 0.012) and sCD163 (P < 0.001) but lower sCD14 levels (P < 0.001). Monocytes from older individuals exhibit impaired phagocytosis (P < 0.05) but contain shortened telomeres (P < 0.001) and significantly higher intracellular levels of TNF both at baseline and following TLR4 stimulation (P < 0.05 for both), suggesting a dysregulation of monocyte function in the aged. These data show that aging is associated with chronic innate immune activation and significant changes in monocyte function, which may have implications for the development of age‐related diseases.     

Genomewide landscape of gene–metabolome associations in Escherichia coli

Metabolism is one of the best‐understood cellular processes whose network topology of enzymatic reactions is determined by an organism's genome. The influence of genes on metabolite levels, however, remains largely unknown, particularly for the many genes encoding non‐enzymatic proteins. Serendipitously, genomewide association studies explore the relationship between genetic variants and metabolite levels, but a comprehensive interaction network has remained elusive even for the simplest single‐celled organisms. Here, we systematically mapped the association between > 3,800 single‐gene deletions in the bacterium Escherichia coli and relative concentrations of > 7,000 intracellular metabolite ions. Beyond expected metabolic changes in the proximity to abolished enzyme activities, the association map reveals a largely unknown landscape of gene–metabolite interactions that are not represented in metabolic models. Therefore, the map provides a unique resource for assessing the genetic basis of metabolic changes and conversely hypothesizing metabolic consequences of genetic alterations. We illustrate this by predicting metabolism‐related functions of 72 so far not annotated genes and by identifying key genes mediating the cellular response to environmental perturbations.     

Proteomic profiling of cardiomyopathic tissue from the aged mdx model of Duchenne muscular dystrophy reveals a drastic decrease in laminin,nidogen and annexin

The majority of patients afflicted with Duchenne muscular dystrophy develop cardiomyopathic complications, warranting large‐scale proteomic studies of global cardiac changes for the identification of new protein markers of dystrophinopathy. The aged heart from the X‐linked dystrophic mdx mouse has been shown to exhibit distinct pathological aspects of cardiomyopathy. In order to establish age‐related alterations in the proteome of dystrophin‐deficient hearts, cardiomyopathic tissue from young versus aged mdx mice was examined by label‐free LC‐MS/MS. Significant age‐dependent alterations were established for 67 proteins, of which 28 proteins were shown to exhibit a lower abundance and 39 proteins were found to be increased in their expression levels. Drastic changes were demonstrated for 17 proteins, including increases in Ig chains and transferrin, and drastic decreases in laminin, nidogen and annexin. An immunblotting survey of young and old wild‐type versus mdx hearts confirmed these proteomic findings and illustrated the effects of natural aging versus dystrophin deficiency. These proteome‐wide alterations suggest a disintegration of the basal lamina structure and cytoskeletal network in dystrophin‐deficient cardiac fibres, increased levels of antibodies in a potential autoimmune reaction of the degenerating heart, compensatory binding of excess iron and a general perturbation of metabolic pathways in dystrophy‐associated cardiomyopathy.     

Comparative mitochondrial genome analysis reveals the evolutionary rearrangement mechanism in Brassica

The genus Brassica has many species that are important for oil, vegetable and other food products. Three mitochondrial genome types (mitotype) originated from its common ancestor. In this paper, a B. nigra mitochondrial main circle genome with 232,407 bp was generated through de novo assembly. Synteny analysis showed that the mitochondrial genomes of B. rapa and B. oleracea had a better syntenic relationship than B. nigra. Principal components analysis and development of a phylogenetic tree indicated maternal ancestors of three allotetraploid species in Us triangle of Brassica. Diversified mitotypes were found in allotetraploid B. napus, in which napus‐type B. napus was derived from B. oleracea, while polima‐type B. napus was inherited from B. rapa. In addition, the mitochondrial genome of napus‐type B. napus was closer to botrytis‐type than capitata‐type B. oleracea. The sub‐stoichiometric shifting of several mitochondrial genes suggested that mitochondrial genome rearrangement underwent evolutionary selection during domestication and/or plant breeding. Our findings clarify the role of diploid species in the maternal origin of allotetraploid species in Brassica and suggest the possibility of breeding selection of the mitochondrial genome.     

Association of the CPT1B Gene with Skeletal Muscle Fat Infiltration in Afro‐Caribbean Men

Skeletal muscle fat is greater in African ancestry individuals compared with whites, is associated with diabetes, and is a heritable polygenic trait. However, specific genetic factors contributing to skeletal muscle fat in humans remain to be defined. Muscle carnitine palmitoyltransferase‐1B (CPT1B) is a key enzyme in the regulation of skeletal muscle mitochondrial β‐oxidation of long‐chain fatty acids, and as such is a reasonable biological candidate gene for skeletal muscle fat accumulation. Therefore, we examined the association of three nonsynonymous coding variants in CPT1B (G531L, I66V, and S427C; a fourth, A320G, could not be genotyped) and quantitative computed tomography measured tibia skeletal muscle composition and BMI among 1,774 Afro‐Caribbean men aged ≥40, participants of the population‐based Tobago Health Study. For all variants, no significant differences were observed for BMI or total adipose tissue. Among individuals who were homozygous for the minor allele at G531L or I66V, intermuscular adipose tissue (IMAT) was 87% (P = 0.03) and 54% lower (P = 0.03), respectively. In contrast, subcutaneous adipose tissue (SAT) was 11% (P = 0.017) and 7% (P = 0.049) higher, respectively, than among individuals without these genotypes. These associations were independent of age, body size, and muscle area. Finally, no individuals with type 2 diabetes were found among those who were homozygous for the minor allele of either at G531L and I66V whereas 14–18% of men with the major alleles had type 2 diabetes (P = 0.03 and 0.007, respectively). Our results suggest a novel association between common nonsynonymous coding variants in CPT1B and ectopic skeletal muscle fat among middle‐aged and older African ancestry men.     

Simultaneous monitoring of intracellular ATP and oxygen levels in chondrogenic differentiation using a dual‐color bioluminescence reporter

A number of assay methods which measure cellular metabolic activity have only measured intracellular ATP levels because it has been speculated that ATP production and oxygen consumption are obligatorily coupled to each other under normal conditions. However, there exist many cases in which ATP production and oxygen consumption are uncoupled. Therefore, measurement of only intracellular ATP levels has a limit for understanding the overall metabolic states during various cellular functions. Here, we report a novel system for simultaneously monitoring intracellular ATP and oxygen levels using a red‐emitting Phrixothrix hirtus luciferase (PxRe) and a blue‐emitting Renilla luciferase (Rluc). Using this system, we monitored the dynamic changes in both intracellular ATP and oxygen levels during chondrogenesis. We found that the oxygen level oscillated at twice the frequency of ATP in chondrogenesis and the oxygen oscillations have an antiphase mode to the ATP oscillations; we also found an independent mode for the ATP oscillations. This result indicates that both mitochondrial and non‐mitochondrial respiration oscillate and thus play a role in chondrogenesis. This dual‐color monitoring system is useful for studying metabolic regulations that underlie diverse cellular processes. Copyright © 2013 John Wiley & Sons, Ltd.     

The real‐time quantification of autofluorescence spectrum shape for the monitoring of mitochondrial metabolism

The cellular proportion of free and protein‐bound NADH complexes is increasingly recognized as a metabolic indicator and biomarker. Because free and bound forms exhibit different fluorescence spectra, we consider whether autofluorescence shape sufficiently correlates with mitochondrial metabolism to be useful for monitoring in cellular suspensions. Several computational approaches for rapidly quantifying spectrum shape are used to detect Saccharomyces cereviseae response to oxygenation, and to the addition of mitochondrial functional modifiers and metabolic substrates. Observed changes appear consistent with previous studies probing free/protein‐bound proportions, making this a potentially useful approach for the real‐time monitoring of metabolism. (© 2015 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)     

Long‐term restricted feeding alters circadian expression and reduces the level of inflammatory and disease markers

The circadian clock in peripheral tissues can be entrained by restricted feeding (RF), a regimen that restricts the duration of food availability with no calorie restriction (CR). However, it is not known whether RF can delay the occurrence of age‐associated changes similar to CR. We measured circadian expression of clock genes, disease marker genes, metabolic factors and inflammatory and allergy markers in mouse serum, liver, jejunum and white adipose tissue (WAT) after long‐term RF of 4 months. We found that circadian rhythmicity is more robust and is phase advanced in most of the genes and proteins tested under RF. In addition, average daily levels of some disease and inflammatory markers were reduced under RF, including liver Il‐6 mRNA, tumour necrosis factor (TNF)‐α and nuclear factor κB (NF‐κB) protein; jejunum Arginase, Afp, Gadd45β, Il‐1α and Il‐1β mRNA, and interleukin (IL)‐6 and TNF‐α protein and WAT Il‐6, Il‐1β, Tnfα and Nfκb mRNA. In contrast, the anti‐inflammatory cytokine Il‐10 mRNA increased in the liver and jejunum. Our results suggest that RF may share some benefits with those of CR. As RF is a less harsh regimen to follow than CR, the data suggest it could be proposed for individuals seeking to improve their health.