Metabolomics--a novel window into inflammatory disease

Inflammation is an important component of normal responses to infection and injury. However, chronic activation of the immune system, perhaps due to aberrant responses to normal stimuli, can lead to the establishment of a chronic inflammatory state. Such inflammatory conditions are often debilitating, and are associated with a number of important co-morbidities including cardiovascular disease. Resting non-proliferative tissues have distinctive metabolic activities and requirements, which differ considerably from those in infiltrating immune cells, which are undergoing proliferation and differentiation. Immune responses in tissues may therefore be modulated by the relative abundance of substrates in the inflamed site. In turn immune cell activity can feed back and affect metabolic behaviour of the tissues, as most clearly demonstrated in cachexia - the loss of cellular mass driven by tumour necrosis factor-alpha (TNF-α) a key mediator of the inflammatory response. Here we discuss the potential for metabolomic analysis to clarify the interactions between inflammation and metabolic changes underlying many diseases. We suggest that an increased understanding of the interaction between inflammation and cellular metabolism, energy substrate use, tissue breakdown markers, the microbiome and drug metabolites, may provide novel insight into the regulation of inflammatory diseases

Leishmania donovani populations in Eastern Sudan: temporal structuring and a link between human and canine transmission.

BACKGROUND: Visceral leishmaniasis (VL), caused by the members of the Leishmania donovani complex, has been responsible for devastating VL epidemics in the Sudan. Multilocus microsatellite and sequence typing studies can provide valuable insights into the molecular epidemiology of leishmaniasis, when applied at local scales. Here we present population genetic data for a large panel of strains and clones collected in endemic Sudan between 1993 and 2001. METHODS: Genetic diversity was evaluated at fourteen microsatellite markers and eleven nuclear sequence loci across 124 strains and clones. RESULTS: Microsatellite data defined six genetic subpopulations with which the nuclear sequence data were broadly congruent. Pairwise estimates of FST (microsatellite) and KST (sequence) indicated small but significant shifts among the allelic repertoires of circulating strains year on year. Furthermore, we noted the co-occurrence of human and canine L. donovani strains in three of the six clusters defined. Finally, we identified widespread deficit in heterozygosity in all four years tested but strong deviation from inter-locus linkage equilibrium in two years. CONCLUSIONS: Significant genetic diversity is present among L. donovani in Sudan, and minor population structuring between years is characteristic of entrenched, endemic disease transmission. Seasonality in vector abundance and transmission may, to an extent, explain the shallow temporal clines in allelic frequency that we observed. Genetically similar canine and human strains highlight the role of dogs as important local reservoirs of visceral leishmaniasis

Do differentiated macrophages display distinct metabolic profiles reflecting their different functions?

Macrophages are key players in both regulatory and inflammatory immune responses. They are implicated in the pathogenesis of rheumatoid arthritis (RA) where they accumulate in the synovium and produce pro-inflammatory cytokines including TNFα and IL-6. The rheumatoid synovium is metabolically distinctive, with low oxygen perfusion and high concentrations of lactate and reactive oxygen species (ROS). Macrophages are known to respond to metabolic signals, therefore we wanted to explore whether metabolic phenotypes of differentiated macrophages could play a role in the persistence of RA. We used an in vitro model of pro-inflammatory “classically activated” and “alternatively activated” macrophages to study macrophage behaviour using metabolomic and transcriptomic techniques. Differentiation with GMCSF and M-CSF produced macrophages with distinctive profiles. GM-CSF macrophages were metabolically active, metabolising glucose, glutamine and fatty acids, while M-CSF macrophages utilised fatty acid β-oxidation alone. Activation of macrophages with LPS, LPS+IFNγ or IL-4 produced metabolic changes, however, differences between MCSF groups were modest. LPS activation of GM-CSF macrophages drove both depletion of intracellular metabolites and transcriptional downregulation. In contrast, IL-4 activation of M-CSF macrophages was metabolically activating. We propose that the metabolic adaptability of GM-CSF macrophages may put them at an energetic advantage in the hypoxic, ROS-enriched rheumatoid synovium

Metabolomics in the Analysis of Inflammatory Diseases

Most infections and traumatic injuries are cleared or repaired relatively rapidly and metabolic homoeostasis is soon restored. However, there is a broad range of inflammatory diseases which involve chronic activation of the immune system and, as a result, chronic persistent inflammation. We have been studying the metabolic consequences of chronic inflammatory diseases with the aim of identifying metabolic fingerprints which may provide clues about why the localised tissue disease persists

Erratum: "Observation of tearing mode deceleration and locking due to eddy currents induced in a conducting shell" [Phys. Plasmas <b>11</b>, 2156 (2004)]

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Endocrine regulation of final oocyte maturation and sex differentiation in salmonids

Sexual maturation and sex differentiation comprise facets of a common theme: reproduction. The endocrine system regulates many of the critical physiological processes necessary for reproduction and offers a framework within which technologies can be developed for controlling sexual maturation and sex differentiation. The studies described in this thesis were undertaken to improve the understanding of the endocrine control of these critical stages of development in salmonids. Final ovarian maturation in salmon is accompanied by dynamic changes in plasma hormone levels. Ovulation can be accelerated through the use of hormones such as gonadotropin releasing hormone or its analogs (GnRHa). The effectiveness of GnRHa often depends on the timing of treatment. To determine if plasma concentrations of steroids can be used to predict the sensitivity of adult female coho salmon (Oncorhynchus kisutch) to GnRHa, circulating levels of testosterone, 17α,20β-dihydroxyprogesterone (DHP), and estradiol were measured before and after injection with GnRHa to accelerate ovulation. We found that high levels of testosterone were predictive of early response of coho salmon to GnRHa treatment. The correlation between testosterone and ovulatory response to GnRHa suggested a possible functional relation. However. implantation or injection of testosterone. 17α-methyltestosterone (MT), or the antiandrogen, cyproterone acetate (CA), before or with GnRHa treatment did not affect the ovulatory response of coho or chinook salmon ( 0. tshawytscha) to GnRHa. Chinook salmon treated with MT alone had accelerated ovulation in comparison to controls. If steroids are involved in sex differentiation. steroids must be produced early in development. In vitro production of steroids in both coho salmon and rainbow trout (0. mykiss) was assessed from hatch through sex differentiation. Cortisol, androstenedione, testosterone, and estradiol were produced just after hatching by tissue explants that contained anterior kidneys and gonads of coho salmon. To circumvent the problem of not knowing the sex of individuals until after sex differentiation, single-sex populations of rainbow trout were produced by gynogenesis or androgenesis. Tissue explants produced more androstenedione than testosterone or estradiol. More androgens were produced by testes and more estradiol was produced by ovaries within 6 to 10 weeks of hatching. Dietary treatment with estradiol or MT inhibited gonadal steroid secretion. Electrophoresis of gonadal homogenates from salmonids revealed several sex-specific bands. In particular, a prominent band of about 50,000 daltons was apparent in ovaries but not testes. Production of sex-specific proteins may be affected by dietary steroid treatment

A facile quantitative assay for viral particle genesis reveals cooperativity in virion assembly and saturation of an antiviral protein

Conventional assays of viral particle assembly and release are time consuming and laborious. We have developed an enzymatic virus-like particle (VLP) genesis assay that rapid and quantitative and is also versatile and applicable to diverse viruses including HIV-1 and Ebola virus. Using this assay, which has a dynamic range of several orders of magnitude, we show that the efficiency of VLP assembly and release, i.e., the fraction of the expressed protein that is assembled into extracellular particles, is dependent on the absolute level of expression of either HIV-1 Gag or Ebola virus VP40. We also demonstrate that the activity of the antiviral factor tetherin is dependent on the level of HIV-1 Gag expression and the numbers of VLPs generated, and appears to become saturated as these parameters are increased

Physical properties of interstellar filaments

We analyze the physical parameters of interstellar filaments that we describe by an idealized model of isothermal self-gravitating infinite cylinder in pressure equilibrium with the ambient medium. Their gravitational state is characterized by the ratio f_cyl of their mass line density to the maximum possible value for a cylinder in a vacuum. Equilibrium solutions exist only for f_cyl < 1. This ratio is used in providing analytical expressions for the central density, the radius, the profile of the column density, the column density through the cloud centre, and the fwhm. The dependence of the physical properties on external pressure and temperature is discussed and directly compared to the case of pressure-confined isothermal self-gravitating spheres. Comparison with recent observations of the fwhm and the central column density N_H(0) show good agreement and suggest a filament temperature of ~10 K and an external pressure p_ext/k in the range 1.5x10^4 K/cm^3 to 5x10^4 K/cm^3. Stability considerations indicate that interstellar filaments become increasingly gravitationally unstable with mass line ratio f_cyl approaching unity. For intermediate f_cyl>0.5 the instabilities should promote core formation through compression, with a separation of about five times the fwhm. We discuss the nature of filaments with high mass line densities and their relevance to gravitational fragmentation and star formation.Comment: 18 pages, 12 figures accepted for publication (13/4/2012