Nutrient digestibility and prediction of metabolizable energy in total mixed rations for ruminants

The aim of the present study was to determine equations that predict ME in total mixed rations (TMR) based on routine methods. The ME content of 30 TMR for dairy cows was determined based on digestible crude nutrients obtained with wether sheep. Concentrations in the TMR (in g/kg DM) varied between 118 and 234 for crude protein, 26 and 48 for crude lipid, 131 and 250 for crude fibre, 281 and 488 for NDF, and 173 and 304 for ADF. Gas production ranged from 40.7 to 54.1 ml/200 mg DM, and enzymatically degraded organic matter from 652 to 800 g/kg DM. Digestibility [%] ranged from 68.6 to 84.0 for organic matter, from 55.6 to 84.3 for crude lipid, from 55.0 to 77.8 for crude fibre, from 57.6 to 77.0 for NDF and from 53.1 to 79.6 for ADF. ME ranged from 9.6 to 11.9 MJ/kg DM, and NEL from 5.7 to 7.4 MJ/kg DM. ME content was highly correlated with the concentration of both crude fibre and enzymatically degradable organic matter as well as with organic matter digestibility. A multiple regression equation based on crude fibre and crude lipid predicted ME with a reasonable goodness of fit (r² = 0.81; s_y.x = 2.4%). The inclusion of other nutrients, of neutral and acid detergent fibre, neither of gas production did improve the goodness of fit. The best prediction was achieved with inclusion of enzymatically degraded organic matter (r² = 0.90; s_y.x = 1.7%).     

TWEAK: a novel biomarker for lupus nephritis?

Renal involvement is common in systemic lupus erythematosus. Early diagnosis of lupus nephritis (LN), allowing the instigation of appropriate therapy, remains an important clinical challenge. Current biomarkers in clinical practice are less than ideal, lacking both sensitivity and specificity. In the previous issue of Arthritis Research & Therapy, Schwartz and colleagues demonstrated the potential value of urinary TNF-like weak inducer of apoptosis (uTWEAK) as a biomarker for LN. They showed that uTWEAK is elevated in subjects with LN at diagnosis compared with those with systemic lupus erythematosus but no renal disease, and correlates with the degree of clinical disease activity. These data are thought-provoking and provide the platform for future longer-term studies.     

Congenital Sensorineural Deafness in Dalmatian Dogs Associated with Quantitative Trait Loci

A genome-wide association study (GWAS) was performed for 235 Dalmatian dogs using the canine Illumina high density bead chip to identify quantitative trait loci (QTL) associated with canine congenital sensorineural deafness (CCSD). Data analysis was performed for all Dalmatian dogs and in addition, separately for brown-eyed and blue-eyed dogs because of the significant influence of eye colour on CCSD in Dalmatian dogs. Mixed linear model analysis (MLM) revealed seven QTL with experiment-wide significant associations (-log₁₀P>5.0) for CCSD in all Dalmatian dogs. Six QTL with experiment-wide significant associations for CCSD were found in brown-eyed Dalmatian dogs and in blue-eyed Dalmatian dogs, four experiment-wide significant QTL were detected. The experiment-wide CCSD-associated SNPs explained 82% of the phenotypic variance of CCSD. Five CCSD-loci on dog chromosomes (CFA) 6, 14, 27, 29 and 31 were in close vicinity of genes shown as causative for hearing loss in human and/or mouse.     

Circulating IgM Requires Plasma Membrane Disruption to Bind Apoptotic and Non-Apoptotic Nucleated Cells and Erythrocytes

Autoimmunity is associated with defective phagocytic clearance of apoptotic cells. IgM deficient mice exhibit an autoimmune phenotype consistent with a role for circulating IgM antibodies in apoptotic cell clearance. We have extensively characterised IgM binding to non-apoptotic and apoptotic mouse thymocytes and human Jurkat cells using flow cytometry, confocal imaging and electron microscopy. We demonstrate strong specific IgM binding to a subset of Annexin-V (AnnV)⁺PI (Propidium Iodide)⁺ apoptotic cells with disrupted cell membranes. Electron microscopy studies indicated that IgM⁺AnnV⁺PI⁺ apoptotic cells exhibited morphologically advanced apoptosis with marked plasma membrane disruption compared to IgM^-AnnV⁺PI⁺ apoptotic cells, suggesting that access to intracellular epitopes is required for IgM to bind. Strong and comparable binding of IgM to permeabilised non-apoptotic and apoptotic cells suggests that IgM bound epitopes are ''apoptosis independent'' such that IgM may bind any cell with profound disruption of cell plasma membrane integrity. In addition, permeabilised erythrocytes exhibited significant IgM binding thus supporting the importance of cell membrane epitopes. These data suggest that IgM may recognize and tag damaged nucleated cells or erythrocytes that exhibit significant cell membrane disruption. The role of IgM in vivo in conditions characterized by severe cell damage such as ischemic injury, sepsis and thrombotic microangiopathies merits further exploration.     

Unique expression of suppressor of cytokine signaling 3 is essential for classical macrophage activation in rodents in vitro and in vivo

On infiltrating inflamed tissue, macrophages respond to the local microenvironment and develop one of two broad phenotypes: classically activated (M1) macrophages that cause tissue injury and alternatively activated macrophages that promote repair. Understanding how this polarization occurs in vivo is far from complete, and in this study, using a Th1-mediated macrophage-dependent model of acute glomerulonephritis, nephrotoxic nephritis, we examine the role of suppressor of cytokine signaling (SOCS)1 and SOCS3. Macrophages in normal kidneys did not express detectable SOCS proteins but those infiltrating inflamed glomeruli were rapidly polarized to express either SOCS1 (27 +/- 6%) or SOCS3 (54 +/- 12%) but rarely both (10 +/- 3%). Rat bone marrow-derived macrophages incubated with IFN-gamma or LPS expressed SOCS1 and SOCS3, whereas IL-4 stimulated macrophages expressed SOCS1 exclusively. By contrast, incubation with IFN-gamma and LPS together suppressed SOCS1 while uniquely polarizing macrophages to SOCS3 expressing cells. Macrophages in which SOCS3 was knocked down by short interfering RNA responded to IFN-gamma and LPS very differently: they had enhanced STAT3 activity; induction of macrophage mannose receptor, arginase and SOCS1; restoration of IL-4 responsiveness that is inhibited in M1 macrophages; and decreased synthesis of inflammatory mediators (NO and IL-6) and costimulatory molecule CD86, demonstrating that SOCS3 is essential for M1 activation. Without it, macrophages develop characteristic alternatively activated markers when exposed to classical activating stimuli. Lastly, increased glomerular IL-4 in nephrotoxic nephritis inhibits infiltrating macrophages from expressing SOCS3 and was associated with attenuated glomerular injury. Consequently, we propose that SOCS3 is essential for development of M1 macrophages in vitro and in vivo.     

Combinatorial model of chemokine involvement in glomerular monocyte recruitment: role of CXC chemokine receptor 2 in infiltration during nephrotoxic nephritis

A sequential model involving chemokines has been proposed for leukocyte extravasation into areas of inflammation; however, site-specific aspects remain to be elucidated. Hence, we studied the role of chemokines produced by mesangial (MC) or glomerular endothelial cells (GEC) and their receptors in glomerular recruitment of monocytes. Stimulation of MC with TNF-alpha up-regulated mRNA and protein of CC and CXC chemokines but not constitutive expression of the CX(3)C chemokine fractalkine. While growth-related activity (GRO)-alpha was immobilized to MC proteoglycans, monocyte chemotactic protein (MCP)-1 was secreted into the soluble phase. Firm adhesion and sequestration of monocytes on activated MC was supported by the GRO-alpha receptor CXCR2 and to a lesser extent by CX(3)CR, whereas the MCP-1 receptor CCR2 contributed to their transendothelial chemotaxis toward activated MC. In contrast, fractalkine mRNA and protein was induced by TNF-alpha in transformed rat GEC, and both CXCR2 and CX(3)CR mediated monocyte arrest on GEC in shear flow. The relevance of these mechanisms was confirmed in a rat nephrotoxic nephritis model where acute glomerular macrophage recruitment was profoundly inhibited by blocking CXCR2 or CCR2. In conclusion, our results epitomize a combinatorial model in which chemokines play specialized roles in driving glomerular monocyte recruitment and emphasize an important role for CXCR2 in macrophage infiltration during early phases of nephrotoxic nephritis.     

Macrophages transfected with adenovirus to express IL-4 reduce inflammation in experimental glomerulonephritis

Nephrotoxic nephritis (NTN) is characterized by acute macrophage-dependent inflammation and serves as a model of human glomerulonephritis. In this study we have transfected rat macrophages with recombinant adenovirus expressing IL-4 (Ad-IL4) and demonstrated that these transfected macrophages develop fixed properties as a result of transfection, as shown by reduced NO production in response to IFN-gamma and TNF. Ad-IL4-transfected macrophages localized with enhanced efficiency to inflamed glomeruli after renal artery injection in rats with NTN compared with adenovirus expressing beta-galactosidase (Ad-beta gal)-transfected macrophages and produced elevated levels of the cytokine in glomeruli in vivo for up to 4 days. The delivery of IL-4-expressing macrophages produced a marked reduction in the severity of albuminuria (day 2 albuminuria, 61 +/- 15 mg/24 h) compared with unmodified NTN (day 2 albuminuria, 286 +/- 40 mg/24 h; p < 0.01), and this was matched by a reduction in the number of ED1-positive macrophages infiltrating the glomeruli. Interestingly, the injection of IL-4-expressing macrophages into single kidney produced a marked reduction in the numbers of ED1-positive macrophages in the contralateral noninjected kidney, an effect that could not be mimicked by systemic delivery of IL-4-expressing macrophages. This implies that the presence of IL-4-expressing macrophages in a single kidney can alter the systemic development of the inflammatory response. Macrophage transfection and delivery provide a valuable system to study and modulate inflammatory disease and highlight the feasibility of macrophage-based gene therapy.     

Vitamin E: underestimated as an antioxidant

Some 80 years after its discovery, vitamin E has experienced a renaissance which is as surprising as it is trivial. Although vitamin E is essential for reproduction, in rats at least, and deficiency causes neurological disorders in humans, the main interest in the last decades has concentrated on its antioxidant functions. This focus has highly underestimated the biological importance of vitamin E, which by far exceeds the need for acting as a radical scavenger. Only recently has it become clear that vitamin E can regulate cellular signaling and gene expression. Out of the eight different tocols included in the term vitamin E, alpha-tocopherol often exerts specific functions, which is also reflected in its selective recognition by proteins such as the alpha-tocopherol transfer protein and alpha-tocopherol-associated proteins. Vitamin E forms other than alpha-tocopherol are very actively metabolised, which explains their low biopotency. In vivo, metabolism may also attenuate the novel functions of gamma-tocopherol and tocotrienols observed in vitro. On the other hand, metabolites derived from individual forms of vitamin E have been shown to exert effects by themselves. This article focuses on the metabolism and novel functions of vitamin E with special emphasis on differential biological activities of individual vitamin E forms.