Adaptive responses by mouse early embryos to maternal diet protect fetal growth but predispose to adult onset disease

Poor maternal nutrition during pregnancy can alter postnatal phenotype and increase susceptibility to adult cardiovascular and metabolic diseases. However, underlying mechanisms are largely unknown. Here, we show that maternal low protein diet (LPD), fed exclusively during mouse preimplantation development, leads to offspring with increased weight from birth, sustained hypertension, and abnormal anxiety-related behavior, especially in females. These adverse outcomes were interrelated with increased perinatal weight being predictive of later adult overweight and hypertension. Embryo transfer experiments revealed that the increase in perinatal weight was induced within blastocysts responding to preimplantation LPD, independent of subsequent maternal environment during later pregnancy. We further identified the embryo-derived visceral yolk sac endoderm (VYSE) as one mediator of this response. VYSE contributes to fetal growth through endocytosis of maternal proteins, mainly via the multiligand megalin (LRP2) receptor and supply of liberated amino acids. Thus, LPD maintained throughout gestation stimulated VYSE nutrient transport capacity and megalin expression in late pregnancy, with enhanced megalin expression evident even when LPD was limited to the preimplantation period. Our results demonstrate that in a nutrient-restricted environment, the preimplantation embryo activates physiological mechanisms of developmental plasticity to stablize conceptus growth and enhance postnatal fitness. However, activation of such responses may also lead to adult excess growth and cardiovascular and behavioral diseases. © 2008 by the Society for the Study of Reproduction, Inc.

The molecular biology of senile plaques and neurofibrillary tangles in Alzheimer’s disease

Since the earliest descriptions of the disease, senile plaques (SP) and neurofibrillary tangles (NFT) have been regarded as the pathological 'hallmarks' of Alzheimer's disease (AD). Whether or not SP and NFT are sufficient cause to explain the neurodegeneration of AD is controversial. The major molecular constituents of these lesions, viz., beta-amyloid (Ass) and tau, have played a defining role both in the diagnosis of the disease and in studies of pathogenesis. The molecular biology of SP and NFT, however, is complex with many chemical constituents. An individual constituent could be the residue of a pathogenic gene mutation, result from cellular degeneration, or reflect the acquisition of new proteins by diffusion and molecular binding. This review proposes that the molecular composition of SP and NFT is largely a consequence of cell degeneration and the later acquisition of proteins. Such a conclusion has implications both for the diagnosis of AD and in studies of disease pathogenesis.

Persistence of apoptotic cells without autoimmune disease or inflammation in CD14-/- mice

Interaction of macrophages with apoptotic cells involves multiple steps including recognition, tethering, phagocytosis, and anti-inflammatory macrophage responses. Defective apoptotic cell clearance is associated with pathogenesis of autoimmune disease. CD14 is a surface receptor that functions in vitro in the removal of apoptotic cells by human and murine macrophages, but its mechanism of action has not been defined. Here, we demonstrate that CD14 functions as a macrophage tethering receptor for apoptotic cells.Significantly, CD14-/- macrophages in vivo are defective in clearing apoptotic cells in multiple tissues, suggesting a broad role for CD14 in the clearance process. However, the resultant persistence of apoptotic cells does not lead to inflammation or increased autoantibody production, most likely because, as we show, CD14-/- macrophages retain the ability to generate anti-inflammatory signals in response to apoptotic cells. We conclude that CD14 plays a broad tethering role in apoptotic cell clearance in vivo and that apoptotic cells can persist in the absence of proinflammatory consequences.

Can the biology of VEGF and haem oxygenases help solve pre-eclampsia?

Pre-eclampsia, a pregnancy-specific multi-organ syndrome characterized by widespread endothelial damage, is a new risk factor for cardiovascular disease. No therapies exist to prevent or treat this condition, even to achieve a modest improvement in pregnancy length or birth weight. Co-administration of soluble VEGFR-1 [VEGF (vascular endothelial growth factor) receptor-1; more commonly known as sFlt-1 (soluble Fms-like tyrosine kinase-1)] and sEng (soluble endoglin) to pregnant rats elicits severe pre-eclampsia-like symptoms. These two anti-angiogenic factors are increased dramatically prior to the clinical onset of pre-eclampsia and are quite possibly the 'final common pathway' responsible for the accompanying signs of hypertension and proteinuria as they can be reversed by VEGF administration in animal models. HO-1 (haem oxygenase-1), an anti-inflammatory enzyme, and its metabolite, CO (carbon monoxide), exert protective effects in several organs against oxidative stimuli. In a landmark publication, we showed that the HO-1 pathway inhibits sFlt-1 and sEng in cultured cells and human placental tissue explants. Both CO and NO (nitric oxide) promote vascular homoeostasis and vasodilatation, and activation of VEGFR-1 or VEGFR-2 induced eNOS (endothelial nitric oxide synthase) phosphorylation, NO release and HO-1 expression. Our studies established the HO-1/CO pathway as a negative regulator of cytokine-induced sFlt-1 and sEng release and eNOS as a positive regulator of VEGF-mediated vascular morphogenesis. These findings provide compelling evidence for a protective role of HO-1 in pregnancy and identify it as a target for the treatment of pre-eclampsia. Any agent that is known to up-regulate HO-1, such as statins, may have potential as a therapy. Any intervention achieving even a modest prolongation of pregnancy or amelioration of the condition could have a significant beneficial health impact worldwide.

Luminescent techniques for studying free radical production and cell viability in relation to cardiovascular disease and HRT

Epidemiological studies have suggested that hormone replacement therapy (HRT) offers protection from atherosclerosis, a precursor of cardiovascular disease (CVD), in postmenopausal women. There is good evidence that oxidation of low-density lipoprotein (LDL) by leucocyte-derived reactive oxygen species plays a key role in development of an atherosclerotic plaque. Therefore we have investigated whether the possible protection against CVD by HRT could be due to immunomodulation, specifically of free radical production. The study involves 2 approaches: I) analysing the production of free radicals by leucocytes from women on HRT, 2) investigating the effect of I7p-oestradiol and progesterone on cultured myeloid cells (HL60 and U937). Free radical production by leucocytes was determined using a recently developed bioluminescent assay. In the assay, Pholasin® emits light in the presence of free radicals produced by the NADPH oxidase system of leucocytes stimulated with PMA or fMLP. Cell viability was also investigated using a bioluminescent assay (Cell Titer-Glo®) in which cytosolic ATP levels were measured by the production of luminescence in the presence of Luciferin/Luciferase reagent. Studies of leucocytes from HRT patients showed considerable variation in free radical production, which appeared to be dependent on HRT regime. Studies on the cultured cells showed that there was no cell proliferation at low hormone concentrations, while high concentrations caused cytotoxicity. The effect of hormones on free radical production in this in vitro model system is currently being investigated. The results show that the effects of the hormones on cells of the immune system are very dose dependent, and that both beneficial and adverse effects may occur. In conclusion, luminescent techniques offer a valuable and sensitive approach to studying inflammatory and oxidative processes both in vivo and in vitro.

Thiol redox homeostasis in neurodegenerative disease

This review provides an overview of the biochemistry of thiol redox couples and the significance of thiol redox homeostasis in neurodegenerative disease. The discussion is centred on cysteine/cystine redox balance, the significance of the xc- cystine-glutamate exchanger and the association between protein thiol redox balance and neurodegeneration, with particular reference to Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis and glaucoma. The role of thiol disulphide oxidoreductases in providing neuroprotection is also discussed.

Mapping nitro-tyrosine modifications in fibrinogen by mass spectrometry as a biomarker for inflammatory disease

There is a growing awareness that inflammatory diseases have an oxidative pathology, which can result in specific oxidation of amino acids within proteins. It is known that patients with inflammatory disease have higher levels of plasma protein nitro-tyrosine than healthy controls. Fibrinogen is an abundant plasma protein, highly susceptible to such oxidative modifications, and is therefore a potential marker for oxidative protein damage. The aim of this study was to map tyrosine nitration in fibrinogen under oxidative conditions and identify susceptible residues. Fibrinogen was oxidised with 0.25mM and 1mM SIN-1, a peroxynitrite generator, and methionine was used to quench excess oxidant in the samples. The carbonyl assay was used to confirm oxidation in the samples. The carbonyl levels were 2.3, 8.72 and 11.5nmol/mg protein in 0, 0.25mM and 1mM SIN-1 samples respectively. The samples were run on a SDS-PAGE gel and tryptically digested before analysis by HPLC MS-MS. All 3 chains of fibrinogen were observed for all treatment conditions. The overall sequence coverage for fibrinogen determined by Mascot was between 60-75%. The oxidised samples showed increases in oxidative modifications in both alpha and beta chains, commonly methionine sulfoxide and tyrosine nitration, correlating with increasing SIN-1 treatment. Tyrosines that were most susceptible were Tyr135 (tryptic peptide YLQEIYNSNNQK) and Tyr277 (tryptic peptide GGSTSYGTGSETESPR), but several other nitrated tyrosines were also identified with high confidence. Identification of these susceptible peptides will allow design of sequences-specific biomarkers of oxidative and nitrative damage to plasma protein in inflammatory conditions.