Kaarin Mäkikallio

Inactivation of the Lysyl Oxidase Gene Lox Leads to Aortic Aneurysms, Cardiovascular Dysfunction, and Perinatal Death in Mice

Background—The lysyl oxidases are extracellular copper enzymes that initiate the crosslinking of collagens and elastin, 5 human isoenzymes having been characterized so far. The crosslinks formed provide the tensile strength and elastic properties for various extracellular matrices, including vascular walls. We studied the role of the first described isoenzyme Lox by inactivating its gene in mice. Methods and Results—Murine Lox gene was disrupted by routine methods. Lox−/− mice died at the end of gestation or as neonates, necropsy of the live-born pups revealing large aortic aneurysms. In light microscopy, hazy and unruffled elastic lamellae in the Lox−/− aortas were observed, and electron microscopy of the aortic walls of the Lox−/− fetuses showed highly fragmented elastic fibers and discontinuity in the smooth muscle cell layers in Lox−/− fetuses. The wall of the aorta in the Lox−/− fetuses was significantly thicker, and the diameter of the aortic lumen was significantly smaller than that in the Lox+/+ aortas. In Lox−/− fetuses, Doppler ultrasonography revealed increased impedance in the umbilical artery, descending aorta, and intracranial artery blood velocity waveforms, decreased mean velocities across cardiac inflow and outflow regions, and increased pulsatility in ductus venosus blood velocity waveforms. Conclusions—Lox has an essential role in the development and function of the cardiovascular system. Inactivation of the Lox gene causes structural alterations in the arterial walls, leading to abnormalities in the cardiovascular functions. Alterations in LOX activity may also play a critical role in certain human cardiovascular diseases.

Ultrasonographic and Biochemical Markers of Human Fetal Cardiac Dysfunction in Placental Insufficiency

Background— Placental insufficiency may lead to fetal cardiovascular compromise. We sought to determine whether ultrasonographic parameters of fetal cardiovascular function correlate with umbilical arterial levels of biochemical markers of myocardial dysfunction and damage in placental insufficiency. Methods and Results— In 48 fetuses with placental insufficiency, umbilical artery blood was obtained at delivery for assessment of N-terminal peptide of proatrial natriuretic peptide (NT-proANP) and cardiac troponin-T (cTnT). Group 1 fetuses (n=12) had normal NT-proANP and cTnT serum concentrations. Group 2 fetuses (n=25) showed increased NT-proANP (>1145 pmol/L) and normal cTnT values. Group 3 fetuses (n=11) had increased NT-proANP and cTnT (>0.10 ng/mL) levels. The ultrasonographic parameters of fetal cardiovascular function were compared between the groups. Pulsatility indices for veins of the ductus venosus, left hepatic vein, and inferior vena cava correlated significantly with NT-proANP levels. In group...

Retrograde aortic isthmus net blood flow and human fetal cardiac function in placental insufficiency

Retrograde aortic isthmus (AoI) net blood flow has been associated with diminished oxygen delivery to cerebral circulation. This study was designed to characterize the cardiac function in human fetuses with retrograde AoI net blood flow in pregnancies complicated by placental insufficiency.

Human fetal cardiovascular profile score and neonatal outcome in intrauterine growth restriction

To determine whether low cardiovascular profile (CVP) score has prognostic value for predicting neonatal mortality and severe morbidity in human fetuses with growth restriction.

Human fetal cardiac function during the first trimester of pregnancy

Objective: To investigate first trimester human fetal cardiac function in relation to cardiac volume blood flow, and peripheral arterial and venous blood flow patterns. Methods: Transvaginal Doppler ultrasonography was performed in 16 uncomplicated pregnancies at 6+, 7+, 8+, 9+, and 10+ gestational weeks. The shape of the inflow waveform and the presence of atrioventricular valve regurgitation (AVVR) were noted. The outflow mean velocity (Vmean) was calculated. The proportions of the isovolumetric relaxation (IRT%) and contraction times (ICT%) of the cardiac cycle were defined. Ductus venosus and umbilical artery pulsatility indices (PI) were obtained. Results: Every inflow waveform was monophasic before 9+ weeks. At 9+ weeks 11 of 16 and at 10+ weeks all waveforms were biphasic. At 7+ and 8+ weeks AVVR was documented in one case. At 9+ and 10+ weeks AVVR was present in four and seven fetuses, respectively. Mean (SD) outflow Vmean increased between 6+ and 8+ weeks from 3.6 (1.5) to 8.4 (3.0) cm/s (p < 0.05). IRT% decreased significantly from 6+ to 7+ weeks (39.8 (2.6) to 19.2 (6.2), p < 0.001). ICT% decreased between 8+ and 9+ weeks from 13.2 (4.0) to 8.5 (2.5) (p < 0.05). Ductus venosus PIs were unchanged. Umbilical artery Vmean increased between 7+ and 10+ weeks from 1.59 (0.51) to 5.06 (1.06) cm/s (p < 0.001) and PIs remained unchanged. Conclusions: The first trimester of pregnancy is characterised by significant improvements in cardiac diastolic and systolic function with a concomitant increase in cardiac volume blood flow. At 10+ weeks AVVR is a common finding. Placental volume blood flow increases significantly with no change in the placental vascular impedance.

Cardiovascular hemodynamics and umbilical artery N-terminal peptide of proB-type natriuretic peptide in human fetuses with growth restriction.

To test our hypothesis that human fetal N‐terminal peptide of proB‐type natriuretic peptide (NT‐proBNP) secretion is increased in proportion to the severity of fetal cardiovascular compromise in intrauterine growth restriction.

Intra-amniotic lipopolysaccharide leads to fetal cardiac dysfunction. A mouse model for fetal inflammatory response.

OBJECTIVE Intrauterine infection is associated with increased lipopolysaccharide (LPS) and proinflammatory cytokines in amniotic fluid. We hypothesized that intra-amniotic LPS launches a fetal inflammatory response leading to cardiac dysfunction. METHODS A mouse model was established. At 15-16 days of gestation, 52 fetuses of nine dams received LPS and 46 fetuses of nine dams vehicle intra-amniotically. Five dams underwent a sham operation. Echocardiography was performed before and 6 h after the injection to obtain inflow and outflow blood velocity waveforms. Outflow mean velocity (V(mean)) and the proportions of isovolumetric relaxation (IRT%) and contraction (ICT%) times of the cardiac cycle were calculated. Pulsatility indices (PI) were calculated from the umbilical and intracranial arteries and the descending aorta. Pulsatility indices for veins (PIV) were obtained from ductus venosus. Toll-like receptor-4 (TLR4) and several other inflammatory mediators were determined using ELISA, immunohistochemistry, or ribonuclease protection assay. RESULTS In the LPS group, outflow V(mean) was significantly lower, and ICT% and IRT% longer than in the other groups. LPS increased PIs, except in the intracranial arteries, which showed a decrease in PIs. In ductus venosus, PIVs were increased after LPS. LPS increased interleukin (IL)-6 in amniotic fluid and induced the expression of proinflammatory cytokines in placenta and fetal membranes, but not in lung. In fetal myocardium, TLR4 was constitutional. LPS induced the expression of IL-1beta and tumor necrosis factor (TNF)-alpha mRNA in myocardium, whereas inducible nitric oxide synthase (NOS2) protein and nitrotyrosine remained undetectable. CONCLUSIONS As a response to endotoxin in amniotic fluid, fetal myocardium acutely generates cytokines and severe fetal cardiovascular compromise develops. These two may be linked through a mechanism that does not include NO.

Uteroplacental Hemodynamics during Early Human Pregnancy: A Longitudinal Study

Background: To determine normal physiologic changes in the uteroplacental hemodynamics during early placental development in the first trimester of pregnancy. Methods: Sixteen normal singleton pregnancies were included in this longitudinal study. Transvaginal Doppler ultrasonographic examinations of uterine, arcuate, radial and spiral arteries were performed at the 5th, 7th, 8th and 10th completed gestational weeks. Peak systolic velocity (PSV), time-averaged maximum velocity (TAMXV) and the pulsatility index (PI) were measured. Results: Uterine artery PSV, TAMXV and PI remained unchanged from the 5th to the 8th week of gestation. From the 8th to the 10th week, PSV (p = 0.02) and TAMXV (p = 0.005) increased and PI decreased (p = 0.006). Changes in the arcuate arteries were similar to those in uterine arteries. No significant changes in PSV, TAMXV or PI of the radial artery were noticed. Spiral artery PSV (p = 0.02) and TAMXV (p = 0.02) increased from the 5th to the 7th week. Thereafter they remained unchanged. Spiral artery PI decreased from the 5th to the 10th week, (p = 0.004). Throughout the study period, the PSV, TAMXV and PI values were significantly higher in the uterine artery than in the arcuate artery, and in the arcuate artery compared with the radial artery. At the 5th gestational week, no differences in PSV and TAMXV were found between radial and spiral arteries. From the 7th gestational week onwards, PSV and TAMXV were significantly lower in the radial artery than in the spiral artery. However, the PI values in the radial artery were significantly higher compared with those in the spiral artery during the whole study period. Conclusions: Spiral artery impedance decreases and blood flow velocities increase as early as between the 5th and the 7th weeks of gestation. During that period, the uterine and arcuate artery hemodynamics remain unchanged. In the uterine and arcuate arteries, decreases in impedance and increases in absolute velocities are detected after the 8th week of gestation. This delay between the changes in the spiral and uterine arteries may represent the magnitude of the increase of placental volume and spiral arterial involvement which is needed to affect uterine hemodynamics.

Increased fetal cardiac natriuretic peptide secretion in type-1 diabetic pregnancies

Background. We hypothesised that human fetal cardiac natriuretic peptide secretion is increased in type‐1 diabetic pregnancies with normal placental hemodynamics, and this increase is related to the first trimester maternal glycemic control. Methods. Thirty‐two neonates of type‐1 diabetic mothers and 60 neonates born after uncomplicated pregnancy and labour (control group) were included in this study. Diabetic pregnancies were divided into two subgroups based on the first trimester HbA1c value. Group 1 pregnancies (n =22) had a good glycemic control (HbA1c <7.5%) and Group 2 pregnancies (n =10) had a poor glycemic control (HbA1c ≥7.5%). At delivery, an umbilical artery (UA) blood sample was obtained for assessment of N‐terminal peptide of proatrial (NT‐proANP) and proB‐type (NT‐proBNP) natriuretic peptide levels. In diabetic pregnancies, each fetus had normal UA Doppler velocimetry for gestational age. Results. The newborn UA NT‐proANP and NT‐proBNP concentrations were significantly higher in type‐1 diabetic pregnancies than in the control group. Group 2 fetuses with poor glycemic control showed significantly higher UA NT‐proANP levels than Group 1 fetuses. UA NT‐proANP levels correlated significantly with maternal HbA1c values in the first, second and third trimesters, while UA NT‐proBNP levels did not correlate with maternal HbA1c values. Conclusions. In type‐1 diabetic pregnancies, fetal cardiac natriuretic peptide secretion is increased, even in the presence of good glycemic control and normal placental hemodynamics. In addition, fetal NT‐proANP levels are already related to maternal glycemic control in the first trimester of pregnancy.

Umbilical artery chemokine CCL16 is associated with preterm preeclampsia and fetal growth restriction.

BACKGROUND Cytokines and growth factors synthesized by placental trophoblasts are suggested to induce endothelial and vascular smooth muscle cell apoptosis and affect angiogenesis. OBJECTIVE To investigate cord blood and placental immunoproteins in order to find new clues on pathogenetic factors of preterm preeclampsia. METHODS Cord blood samples were collected on 163 consecutive preterm deliveries prior to 32 gestational weeks. Placental function, clinical risk factors and 107 umbilical artery immunoproteins were analyzed. Classification and regression trees analysis was used to detect associations between the immunoproteins, clinical parameters and preterm preeclampsia. Placental expression of the immunoproteins and their receptors were subsequently investigated. RESULTS Preeclampsia complicated 34% of the pregnancies in this preterm cohort. Umbilical artery CCL16, CCL24, and CCL23 were associated with preeclampsia, CCL16 showing the strongest relationship with an OR (95% CI) of 24.5 (5.4-112.0). High umbilical artery CCL16 was also characteristic to fetuses with severe growth restriction (<3rd percentile). CCL16, CCL24 and their receptors, CCR1 and CCR3 were expressed in preeclamptic placentas. CONCLUSIONS High umbilical artery CCL16 is prominently detected in preterm preeclamptic pregnancies with severe growth restriction. A link to compensatory proangiogenic mechanisms has to be considered.