HSP70 expression and its role in preeclamptic stress

Preeclampsia, a hypertensive pregnancy-specific disorder, has long been analyzed for its association with cellular stress. It still remains one of the most serious complications of pregnancy. It is a multi-system disorder that affects maternal vascular function and fetal growth. The physiopathology of preeclampsia is still unclear, but an imbalance between reactive oxygen species (ROS) and antioxidants, appears to be an important contributing factor. Oxidative stress has been increasingly postulated as a major contributor to endothelial dysfunction in preeclampsia (PE). The ROS promotes lipid oxidation and are known to induce stress proteins, such as hemeoxygenase 1 (HO-1) and heat-shock protein 70 (HSP70). Embryonic and placental cells are highly sensitive to oxidative stress due to their proliferate nature. Endothelial cell dysfunction is suggested to be a part of wider maternal inflammatory reaction responsible for the clinical syndrome of preeclampsia. Part of the dysfunction in endothelial cell and trophoblast is attributed to oxidative stress developed during pregnancy. The disequilibrium in compensatory antioxidant control is proposed as a causative mechanism in the pathophysiology of preeclampsia. HSP70 acts as the secondary line of defense in systems with compromised antioxidant function. This article reviews the differential expression of HSP70 and the effect of mint-tea therapy to modulate preeclamptic oxidative damage.     

AP endonuclease-independent DNA base excision repair in human cells

The paradigm for repair of oxidized base lesions in genomes via the base excision repair (BER) pathway is based on studies in Escherichia coli, in which AP endonuclease (APE) removes all 3' blocking groups (including 3' phosphate) generated by DNA glycosylase/AP lyases after base excision. The recently discovered mammalian DNA glycosylase/AP lyases, NEIL1 and NEIL2, unlike the previously characterized OGG1 and NTH1, generate DNA strand breaks with 3' phosphate termini. Here we show that in mammalian cells, removal of the 3' phosphate is dependent on polynucleotide kinase (PNK), and not APE. NEIL1 stably interacts with other BER proteins, DNA polymerase beta (pol beta) and DNA ligase IIIalpha. The complex of NEIL1, pol beta, and DNA ligase IIIalpha together with PNK suggests coordination of NEIL1-initiated repair. That NEIL1/PNK could also repair the products of other DNA glycosylases suggests a broad role for this APE-independent BER pathway in mammals.     

Mycobacterium tuberculosis induces differential cytokine production from dendritic cells and macrophages with divergent effects on naive T cell polarization

Th1-mediated cellular responses are important for protection in tuberculosis. However, the mechanisms and APC types responsible for initiating Th1 responses are not well understood. These studies show that macrophages and dendritic cells, albeit both being APC, respond differently following Mycobacterium tuberculosis infection and thereby have different consequences for the development of naive T cells. We report that M. tuberculosis-infected dendritic cells bias the polarization of OVA peptide-specific naive transgenic T cells to the Th1 phenotype, and, in contrast, in the presence of infected macrophages naive T cells do not develop a Th1 phenotype. Comparison of the cytokine profile expressed by the infected dendritic cells and macrophages revealed several differences, the most striking being that infected macrophages did not express the Th1-promoting cytokine IL-12. These studies also show that IL-10 is responsible for the failure of IL-12 production by M. tuberculosis-infected macrophages, and that the effects of IL-10 can be overcome by IFN-gamma priming. We speculate that the observed difference in response of the two APC types to M. tuberculosis infection may be a reflection of their respective roles in immune initiation and granuloma regulation.     

Modulation of Human Valve Interstitial Cell Phenotype and Function Using a Fibroblast Growth Factor 2 Formulation

Valve interstitial cells (VICs) are fibroblastic in nature however in culture it is widely accepted that they differentiate into a myofibroblastic phenotype. This study assessed a fibroblast culture media formulation for its ability to maintain the phenotype and function of VICs as in the intact healthy valve. Normal human VICs were cultured separately in standard DMEM and in fibroblast media consisting of FGF2 (10ng/ml), insulin (50ng/ml) and 2% FCS for at least a week. Cell morphology, aspect ratio, size, levels and distribution of protein expression, proliferation, cell cycle, contraction and migration were assessed. Some VICs and some valve endothelial cells expressed FGF2 in valve tissue and this expression was increased in calcified valves. VICs in DMEM exhibited large, spread cells whereas VICs in fibroblast media were smaller, elongated and spindly. Aspect ratio and size were both significantly higher in DMEM (p<0.01). The level of expression of α-SMA was significantly reduced in fibroblast media at day 2 after isolation (p<0.01) and the expression of α-SMA, SM22 and EDA-fibronectin was significantly reduced in fibroblast media at days 7 and 12 post-isolation (p<0.01). Expression of cytoskeletal proteins, bone marker proteins and extracellular matrix proteins was reduced in fibroblast media. Proliferation of VICs in fibroblast media was significantly reduced at weeks 1 (p<0.05) and 2 (p<0.01). Collagen gel contraction was significantly reduced in fibroblast media (p<0.05). VICs were found to have significantly fewer and smaller focal adhesions in fibroblast media (p<0.01) with significantly fewer supermature focal adhesions in fibroblast media (p<0.001). Ultrastructurally, VICs in fibroblast media resembled native VICs from intact valves. VICs in fibroblast media demonstrated a slower migratory ability after wounding at 72 hours (p<0.01). Treatment of human VICs with this fibroblast media formulation has the ability to maintain and to dedifferentiate the VICs back to a fibroblastic phenotype with phenotypic and functional characteristics ascribed to cells in the intact valve. This methodology is fundamental in the study of normal valve biology, pathology and in the field of tissue engineering.     

Mitochondrial reactive oxygen species signal hepatocyte steatosis by regulating the phosphatidylinositol 3-kinase cell survival pathway

Abnormal dietary intake of macronutrients is implicated in the development of obesity and fatty liver disease. Steatosis develops in cultured hepatocytes exposed to medium containing either a high concentration of long chain free fatty acids (HFFA) or medium deficient in methionine and choline (MCD). This study examined the mitochondrial reactive oxygen species (ROS)-dependent regulation of the phosphoinositol (PI) 3-kinase pathway in steatosis induced by exposure of AML-12 mouse hepatocytes to MCD or HFFA medium. Exposure to either MCD or HFFA medium resulted in increased production of superoxide anions and H(2)O(2), transduction of the PI 3-kinase pathway and steatosis. Inhibition of PI 3-kinase with LY294002 prevented steatosis. Pharmacologically inhibiting electron transport chain complex III production of ROS prevented activation of PI 3-kinase during macronutrient perturbation, whereas pharmacologically promoting electron transport chain complex III ROS production activated PI 3-kinase independent of nutrient input. The data suggest that H(2)O(2) is the ROS species involved in signal transduction; promoting the rapid conversion of superoxide to H(2)O(2) does not inhibit PI 3-kinase pathway activation during nutrient perturbation, and exogenous H(2)O(2) activates it independent of nutrient input. In addition to transducing PI 3-kinase, the ROS-dependent signal cascade amplifies the PI 3-kinase signal by maintaining phosphatase and tensin homolog in its inactive phosphorylated state. Knockdown of phosphatase and tensin homolog by small interfering RNA independently activated the PI 3-kinase pathway. Our findings suggest a common path for response to altered nutrition involving mitochondrial ROS-dependent PI 3-kinase pathway regulation, leading to steatosis.     

Distribution and reproduction strategies of krill (Euphausiacea) on the Norwegian shelf

Meganyctiphanes norvegica and Thysanoessa inermis were the dominant krill species that were observed on the Norwegian shelf. T. inermis and M. norvegica were found in abundances of up to 14 and 22 no. m^?2, respectively, on the mid Norwegian shelf (Møre plateau, Halten, Sklinna, Træna banks) and up to the Lofoten area. The main distribution of the krill indicates that they are mostly restricted to the Atlantic waters of the shelf region in April and little krill was observed south of 62°N. The two dominant krill species appeared to have different strategies for the timing of spawning, thus avoiding direct overlap of spawning products. The majority of the T. inermis females were in the spawning condition in April. Meganyctiphanes norvegica appeared to spawn at least a month later. The sizes of the first time spawners of T. inermis were around 11–16 mm, and they were approximately 1 year old. The sizes of the second time spawners were around 17–22 mm. The spawning of krill on the Norwegian shelf coincides with the blooming of the spring phytoplankton in this region . Advection of eggs and larvae of krill, as well as other plankton, is important not only to the shelf and slope region, but also for the functioning of the wider Norwegian Sea ecosystem and the adjacent areas.     

Resolvin E1 metabolome in local inactivation during inflammation-resolution

Resolvin E1 (RvE1; 5S,12R,18R-trihydroxy-6Z,8E,10E,14Z,16E-eicosapentaenoic acid) is a potent anti-inflammatory and proresolving mediator derived from the omega-3 eicosapentaenoic acid. In this study, we report the RvE1 metabolome, namely, the metabolic products derived from RvE1. RvE1 was converted to several novel products by human polymorphonuclear leukocytes and whole blood as well as in murine inflammatory exudates, spleen, kidney, and liver. The potential activity of each of the newly identified products was directly compared with that of RvE1. The new RvE1 products elucidated included 19-hydroxy-RvE1, 20-carboxy-RvE1, and 10,11-dihydro-RvE1. Metabolomic profiles of RvE1 were species-, tissue-, and cell type-specific. Direct comparisons of the bioactions between isolated RvE1 metabolic products indicated that 10,11-dihydro-RvE1, 18-oxo-RvE1, and 20-carboxy-RvE1 displayed reduced bioactivity in vivo. At concentrations as low as 1 nM, RvE1 enhanced macrophage phagocytosis, a proresolving activity that was reduced by metabolic inactivation. These results document novel metabolic products of RvE1 that impact its actions and that both omega-1 hydroxylation and reduction of conjugated double bonds in RvE1 are new pathways of four main routes of RvE1 metabolism in mammalian tissues. Together, these findings indicate that, during inflammation and its controlled resolution, specific tissues inactivate proresolving signals, i.e., RvE1, to permit the coordinated return to homeostasis. Moreover, the RvE1 metabolome may serve as a biomarker of these processes.