Tuire Salonurmi

Overexpression of TIMP-1 under the MMP-9 promoter interferes with wound healing in transgenic mice

We have generated transgenic mice harboring the murine matrix metalloproteinase 9 (MMP-9) promoter cloned in front of human TIMP-1 cDNA. The transgenic mice were viable and fertile and exhibited normal growth and general development. During wound healing the mice were shown to express human TIMP-1 in keratinocytes that normally express MMP-9. However, the healing of skin wounds was significantly retarded with slow migration of keratinocytes over the wound in transgenic mice. In situ zymography carried out on wound tissues revealed total blockage of gelatinolytic activity (i.e., MMP-9 and MMP-2). The results confirm studies with MMP-9 knockout mice showing that MMP-9 is not essential for general development, but they also demonstrate an important role of keratinocyte MMP-9, as well that of other keratinocyte MMPs that are inhibited by TIMP-1, in wound healing. The transgenic mice generated in this study provide a model for the role of MMPs in MMP-9-producing cells in other challenging situations such as bone fracture recovery and cancer invasion.

Elevated messenger RNA expression and plasma protein levels of osteopontin and matrix metalloproteinase types 2 and 9 in patients with ascending aortic aneurysms

OBJECTIVE Ascending aortic aneurysms result from a degenerative process in the aortic wall, characterized by the loss of smooth muscle cells and elastic fibers. We hypothesized that there would be changes in plasma protein and aortic tissue messenger RNA levels of osteopontin, matrix metalloproteinase type 2, matrix metalloproteinase type 9, and tissue inhibitor of matrix metalloproteinases type 1 in ascending aortic aneurysm samples. METHODS Plasma, aortic tissue, and aortic mRNA samples were collected from patients with an ascending aortic aneurysm or an abdominal aortic aneurysm and from control individuals. Plasma protein levels of osteopontin, matrix metalloproteinase (MMP) types 2 and 9, and tissue inhibitor of matrix metalloproteinases type 1 were determined by quantitative sandwich enzyme-linked immunosorbent assay. Aortic mRNA levels of these same proteins were analyzed with the quantitative real-time polymerase chain reaction (RT-PCR) method and protein levels from the aortic tissues were assayed by immunostaining. Quantitative RT-PCR results were estimated by the normalized expression method (ΔΔCt). RESULTS Plasma protein levels were significantly elevated for osteopontin, MMP-2, and MMP-9 in the samples of ascending and abdominal aortic aneurysm group compared with controls. Plasma protein levels of MMP-9 were higher in the nonoperated compared with the operated ascending aortic aneurysm group. Aortic osteopontin, MMP-2, and MMP-9 mRNA levels were increased for ascending aortic aneurysm samples. CONCLUSIONS This study reveals an important role of osteopontin, MMP-2 and MMP-9 in the development of ascending and abdominal aortic aneurysm.

Programming effects of FTO in the development of obesity

It is becoming increasingly recognized that early‐life nutritional, metabolic and environmental factors can have a long‐term impact on the early onset of obesity, type 2 diabetes and cardiovascular diseases. Numerous experimental and epidemiological observations support the concept that an individuals response to their adult lifestyle and nutritional environment depends not only on their genetic susceptibility but also on their previous early‐life experiences. The current research challenge is to determine the primary pathways contributing to ‘non‐ or epi‐genetic’ causes of excess adult weight gain and adiposity. Evidence from the fields of genetic epidemiology, life course modelling and diet‐induced foetal programming all support a role for the FTO gene in this complex biological interaction. It may provide a missing link in the developmental regulation of energy metabolism. Our review therefore considers the role of the FTO gene in the early‐life determination of body weight, body composition and energy balance. We will summarize current knowledge on FTO biology combining human genetic epidemiology, molecular models and findings from animal studies. Notably, we will focus on the role of FTO in energy balance in humans, the importance of FTO polymorphisms in childhood growth and the impact of foetal nutrition. Ultimately, we propose a new hypothesis for future research designed to understand the role of FTO in setting gene expression in metabolically active tissues.

Fat mass- and obesity-associated gene Fto affects the dietary response in mouse white adipose tissue

Common variants of human fat mass- and obesity-associated gene Fto have been linked with higher body mass index, but the biological explanation for the link has remained obscure. Recent findings suggest that these variants affect the homeobox protein IRX3. Here we report that FTO has a role in white adipose tissue which modifies its response to high-fat feeding. Wild type and Fto-deficient mice were exposed to standard or high-fat diet for 16 weeks after which metabolism, behavior and white adipose tissue morphology were analyzed together with adipokine levels and relative expression of genes regulating white adipose tissue adipogenesis and Irx3. Our results indicate that Fto deficiency increases the expression of genes related to adipogenesis preventing adipocytes from becoming hypertrophic after high-fat diet. In addition, we report a novel finding of increased Irx3 expression in Fto-deficient mice after high-fat feeding indicating a complex link between FTO, IRX3 and fat metabolism.

Alcohol-induced premature permeability in mouse placenta-yolk sac barriers in vivo

OBJECTIVE Acute alcohol exposure induces malformation and malfunction of placenta-yolk sac tissues in rodents, reducing the labyrinth zone in the placenta and altering the permeability and fluidity of the cell membrane. During normal mouse placentation the cells line up in an optimal way to form a hemotrichorial placenta where layers II and III are connected through gap junctions. These act as molecular sieves that limit the passage of large molecules. PlGF is a developmentally regulated protein that controls the passage of molecules in the vasculosyncytial membranes and media of large blood vessels in the placental villi. In addition to the chorioallontoic placenta, rodents also have another type of placenta that consists of Reicherts membrane within the trophoblast cell layer on the maternal side and the parietal endodermal cells on the embryonic site. This forms a separate materno-fetal transport system. We study here whether alcohol affects these two placental barriers, leading to placental malfunction that in turn diminishes the nutrient supply to the embryo. STUDY DESIGN CD-1 mice received two intraperitoneal injections of 3 g/kg ethanol at 4 h intervals at 8.75 days post coitum (dpc). The placentas were collected on 9.5, 11.5 and 14.5 dpc and used for histopathological protein studies. Hemotrichorial cell layer structure interactions through connective tissue and gap junction were analyzed by electron microscopy. The permeability of the feto-maternal barrier was visualized with Evans Blue. RESULTS VEGF, a permeability inducer, was found to be up-regulated in the mouse placenta after acute alcohol exposure, and permeability was also affected by altered structures in the barriers that separate the feto-maternal blood circulation which destroyed the gap junctions in the hemotrichorial cell layer, reduced the thickness of Reicherts membrane and interfered with with Reicherts trophoblast/Reicherts parietal interaction. These defects together could have caused the permeability malfunction of the placenta-yolk sac tissues as visualized and quantified here by Evans Blue leakage. CONCLUSIONS An altered PlGF/VEGF ratio together with barrier malformation may contribute to placental malfunction by altering the permeability of the feto-maternal barriers. Further studies are needed in order to show whether premature permeability is involved in the intrauterine growth restriction observed in human FAS embryos.

Everyday health information literacy among young men compared with adults with high risk for metabolic syndrome - a cross-sectional population-based study

This cross-sectional population-based study aims at identifying differences in the aspects of everyday health information literacy among young healthy men and adults with an increased risk for metabolic syndrome. Data were collected with a self-assessment-based 10-item screening tool administered at the Finnish Defence Force’s call-ups (n=2507, response rate 59%) and at health intervention study (n=571, response rate 98%). Adults with increased risk for metabolic syndrome seemed to value health information but had more difficulty in knowing who to believe in health issues and understanding the terminology used. The difficulties applied especially to respondents 35 years old or over. Men, and especially young men, had lower motivation than women to seek health information. Although the results are indicative, the everyday health information literacy screening tool seems to be useful in revealing areas that health communication should be focused on among different populations.

Plasma levels of antibodies against oxidized LDL are inherited but not associated with HDL-cholesterol level in families with early coronary heart disease.

OBJECTIVE Oxidized low-density lipoproteins (oxLDL) and antibodies against them (anti-oxLDLs) are thought to play a central role in atherosclerosis. One proposed antiatherosclerotic mechanism for HDL is to prevent oxidation of LDL. This study examined whether plasma HDL-cholesterol (HDL-C) is related to plasma anti-oxLDL levels. METHODS We collected families based on probands with low HDL-C and premature coronary heart disease (CHD). Antibody levels were determined in samples from 405 subjects. Immunoglobulin G, M and A levels against two in vitro models of oxLDL, malondialdehyde-acetaldehyde-modified LDL (MAA-LDL) and copper oxidized LDL (CuOx-LDL), were measured by ELISA. We carried out heritability estimation of antibody traits and bivariate analyses between HDL-C, LDL-C and antibody traits. RESULTS All the antibody levels were significantly inherited (p < 0.001), heritability estimates ranging from 0.28 to 0.65. HDL-C exhibited no environmental or genetic cross-correlations with antibody levels. Significant environmental correlations were detected between LDL-C and both IgG levels (ρ(E) = 0.40, p = 0.046 and ρ(E) = 0.39, p < 0.001). There were no differences in antibody levels between subjects with normal and low HDL-C, or between CHD-affected and non-affected subjects. CONCLUSION In this study, low HDL-C level displayed no significant associations with the anti-oxLDL levels measured. The heritability of the anti-oxLDL levels was a novel and interesting finding.

Ethanol-induced impairment of polyamine homeostasis--a potential cause of neural tube defect and intrauterine growth restriction in fetal alcohol syndrome.

INTRODUCTION Polyamines play a fundamental role during embryogenesis by regulating cell growth and proliferation and by interacting with RNA, DNA and protein. The polyamine pools are regulated by metabolism and uptake from exogenous sources. The use of certain inhibitors of polyamine synthesis causes similar defects to those seen in alcohol exposure e.g. retarded embryo growth and endothelial cell sprouting. METHODS CD-1 mice received two intraperitoneal injections of 3 g/kg ethanol at 4 h intervals 8.75 days post coitum (dpc). The fetal head, trunk, yolk sac and placenta were collected at 9.5 and 12.5 dpc and polyamine concentrations were determined. RESULTS No measurable quantity of polyamines could be detected in the embryo head at 9.5 dpc, 12 h after ethanol exposure. Putrescine was not detectable in the trunk of the embryo at that time, whereas polyamines in yolk sac and placenta were at control level. Polyamine deficiency was associated with slow cell growth, reduction in endothelial cell sprouting, an altered pattern of blood vessel network formation and consequently retarded migration of neural crest cells and growth restriction. DISCUSSION Our results indicate that the polyamine pools in embryonic and extraembryonic tissues are developmentally regulated. Alcohol administration, at the critical stage, perturbs polyamine levels with various patterns, depending on the tissue and its developmental stage. The total absence of polyamines in the embryo head at 9.5 dpc may explain why this stage is so vulnerable to the development of neural tube defect, and growth restriction, the findings previously observed in fetal alcohol syndrome.

Metabolic adaptation allows Amacr-deficient mice to remain symptom-free despite low levels of mature bile acids

Bile acids play multiple roles in the physiology of vertebrates; they facilitate lipid absorption, serve as signaling molecules to control carbohydrate and lipid metabolism, and provide a disposal route for cholesterol. Unexpectedly, the α-methylacyl-CoA racemase (Amacr) deficient mice, which are unable to complete the peroxisomal cleavage of C27-precursors to the mature C24-bile acids, are physiologically asymptomatic when maintained on a standard laboratory diet. The aim of this study was to uncover the underlying adaptive mechanism with special reference to cholesterol and bile acid metabolism that allows these mice to have a normal life span. Intestinal cholesterol absorption in Amacr-/- mice is decreased resulting in a 2-fold increase in daily cholesterol excretion. Also fecal excretion of bile acids (mainly C27-sterols) is enhanced 3-fold. However, the body cholesterol pool remains unchanged, although Amacr-deficiency accelerates hepatic sterol synthesis 5-fold. Changes in lipoprotein profiles are mainly due to decreased phospholipid transfer protein activity. Thus Amacr-deficient mice provide a unique example of metabolic regulation, which allows them to have a normal lifespan in spite of the disruption of a major metabolic pathway. This metabolic adjustment can be mainly explained by setting cholesterol and bile acid metabolism to a new balanced level in the Amacr-deficient mouse.

Fto-Deficiency Affects the Gene and MicroRNA Expression Involved in Brown Adipogenesis and Browning of White Adipose Tissue in Mice

Genetic variants in the fat mass- and obesity-associated gene Fto are linked to the onset of obesity in humans. The causal role of the FTO protein in obesity is supported by evidence obtained from transgenic mice; however, the underlying molecular pathways pertaining to the role of FTO in obesity have yet to be established. In this study, we investigate the Fto gene in mouse brown adipose tissue and in the browning process of white adipose tissue. We analyze distinct structural and molecular factors in brown and white fat depots of Fto-deficient mice under normal and obesogenic conditions. We report significant alterations in the morphology of adipose tissue depots and the expression of mRNA and microRNA related to brown adipogenesis and metabolism in Fto-deficient mice. Furthermore, we show that high-fat feeding does not attenuate the browning process of Fto-deficient white adipose tissue as observed in wild-type tissue, suggesting a triggering effect of the FTO pathways by the dietary environment.