Transthyretin Is Dysregulated in Preeclampsia,and Its Native Form Prevents the Onset of Disease in a Preclinical Mouse Model

Preeclampsia is a major pregnancy complication with potential short- and long-term consequences for both mother and fetus. Understanding its pathogenesis and causative biomarkers is likely to yield insights for prediction and treatment. Herein, we provide evidence that transthyretin, a transporter of thyroxine and retinol, is aggregated in preeclampsia and is present at reduced levels in sera of preeclamptic women, as detected by proteomic screen. We demonstrate that transthyretin aggregates form deposits in preeclampsia placental tissue and cause apoptosis. By using in vitro approaches and a humanized mouse model, we provide evidence for a causal link between dysregulated transthyretin and preeclampsia. Native transthyretin inhibits all preeclampsia-like features in the humanized mouse model, including new-onset proteinuria, increased blood pressure, glomerular endotheliosis, and production of anti-angiogenic factors. Our findings suggest that a focus on transthyretin structure and function is a novel strategy to understand and combat preeclampsia.Preeclampsia occurs in 5% to 8% of pregnancies worldwide and is a major cause of fetal and maternal morbidity and mortality.^1–3 It is a heterogeneous disease with varied presentations from mild self-limited hypertension and proteinuria to severe forms with significant end-organ dysfunction and HELLP syndrome (hemolysis, elevated liver enzymes, and low platelets).³ Although the cause of preeclampsia and its appropriate treatment remain elusive, this syndrome has been proposed to reflect at least two stages of complications during pregnancy. These begin with preclinical manifestations at the maternal-fetal interface, followed by systemic clinical symptoms.^1,2 Hypertension, proteinuria, and edema, with a variable degree of fetal growth restriction, are the cardinal features of preeclampsia.³ Because the placenta is the nutritional and immunological gateway to normal fetal development and pregnancy outcome, placenta-related events are believed to be central to the pathogenesis of this disease. Evidence exists for the release of disease-initiating molecules into maternal circulation that triggers the clinical symptoms.^1,4 Placental and systemic anomalies reflected by circulating placental debris, inflammation, impaired remodeling of spiral arteries, placental hypoxia/ischemia, excess production of anti-angiogenic factors [soluble fms-like tyrosine kinase-1 (sFlt-1)], and soluble endoglin (sEng), and angiotensin receptor autoantibodies have all emerged as contributors to the pathophysiological characteristics of preeclampsia.^2,4–14Preeclampsia has remained enigmatic because of lack of well-defined etiology and animal models. Although normal mice do not develop preeclampsia spontaneously, mouse models have been judged to be particularly useful to uterine diseases and pregnancy complications because many similarities in female reproduction and placentation have been identified between the two species.¹⁵ Moreover, their tractable genetics provide an effective way to probe mechanisms more deeply than many other species.^15–17 We recently showed that sera from preeclamptic women could function as a source of novel causative factors that induced hypertension, proteinuria, and kidney pathological characteristics, as well as intrauterine growth restriction (IUGR), in IL-10^−/− mice in a pregnancy-specific manner.¹⁸ IL-10 functions as a potent vascular and anti-inflammatory cytokine and has been shown to be present at significantly reduced levels in preeclampsia placental tissue.^19,20 Preeclampsia serum (PES) was found to disrupt endovascular cross talk between trophoblasts and endothelial cells and to induce placental hypoxia and excess production of sFlt-1 and sEng,¹⁸ soluble factors known to precipitate maternal symptoms.^21,22 These results from our serum-based humanized mouse model suggest that the pathophysiological characteristics of preeclampsia are more complex than previously thought and are likely to involve interactions and dysregulation of multiple factors. By using serum proteomic screening by surface-enhanced laser-desorption ionization-time-of-flight (SELDI-TOF), our results suggest that PES contains a reduced abundance of transthyretin, a plasma transport protein for the thyroid hormone, thyroxine, and retinol-binding protein.²³ More important, transthyretin has been widely studied for its role in amyloid diseases associated with protein misfolding and aggregation, resulting in deposits of toxic, fibrillar aggregates in specific organs.^24–26 Dysregulated or reduced transthyretin has also been implicated in Alzheimer disease, and overexpression of a wild-type human transthyretin transgene has been shown to ameliorate the disease in the transgenic murine model of human Alzheimer disease.^27,28 Transthyretin in its native form assumes a homotetrameric quaternary configuration (approximately 14 kDa per monomer). Post-translational modifications of the monomer result in detection of several isoforms.²⁹ Circulating transthyretin is also a validated marker of malnutrition and has a putative role in oocyte maturation and inflammation.^30–32 Although the presence of transthyretin during implantation in mice and in the placenta and trophoblasts in humans has been reported,^33,34 its functional role in normal pregnancy or adverse pregnancy outcomes has not been recognized. We hypothesize that transthyretin in preeclampsia is structurally and functionally dysregulated and contributes to the onset of this serious pregnancy complication. Herein, we present complementary in vitro and in vivo approaches, which show that endogenously altered transthyretin is a preeclampsia-causing agent and that native transthyretin has the ability to block the onset of preeclampsia-like features.     

The dangers of ambidexterity: The origins of handedness

Handedness remains an enigmatic phenomenon. There is no definitive explanation as to why man should have single rather than dual handedness. Intuitively it would seem advantageous in almost every context to have the benefit of equally dextrous hands. Either in context of warfare or hunting, using two hands equally as effectively would appear to be a favourable adaptation over single dexterity. No satisfactory explanation has been offered as to why and how single-handedness evolved.     

Long‐term outcome of belatacept therapy in de novo kidney transplant recipients – a case‐match analysis

While belatacept has shown favorable short‐ and midterm results in kidney transplant recipients, only projections exist regarding its potential impact on long‐term outcome. Therefore, we performed a retrospective case‐match analysis of the 14 belatacept patients originally enrolled in the phase II multicenter trial at our center. Fifty six cyclosporine (CyA)‐treated patients were matched according to age at transplantation, first/retransplant, and donor type. Ten years after kidney transplantation, kidney function remained superior in belatacept‐treated patients compared with the CyA control group. Moreover, none of the belatacept‐treated patients had donor‐specific antibodies ≥10 years post‐transplantation compared with 38.5% of tested CyA‐treated subject (0/10 vs. 5/13; P = 0.045). Notably, however, patient and graft survival was virtually identical in both groups (71.4% vs. 71.3%; P = 0.976). In the present single‐center study population, patients treated with belatacept demonstrated a patient and graft survival at 10 years post‐transplant which was comparable to that of similarly selected CNI‐treated patients. Larger studies with sufficient statistical power are necessary to definitively determine long‐term graft survival with belatacept.     

Total Reconstitution of Functionally Active 50S Ribosomal Subunits from Escherichia coli

Total reconstitution of 50S subunits from E. coli was achieved by a two-step incubation procedure. In the first step, 23S RNA, 5S RNA, and the total proteins from 50S subunits were incubated for 20 min at 40 degrees in the presence of 4 mM Mg(++) and 400 mM NH(4)Cl. In the second step, the Mg(++) concentration was raised to 20 mM and the incubation was performed for 90 min at 50 degrees . No requirement for 30S subunits or other components (e.g., polyamine) was found. The reconstituted particle has the same sedimentation coefficient as the native 50S subunit and is highly active in protein synthesis with natural (R17 RNA) and artificial [poly(U)] messengers as well as in tests for peptidyltransferase (fragment assay) and for binding of antibiotics (chloramphenicol).     

Mutations of p53 Tumor Suppressor Gene, Apoptosis, and Proliferation in Intrahepatic Cholangiocellular Carcinoma of the Liver

This study was performed to examine the correlation between mutations of the p53 tumor suppressor gene, the occurrence of apoptosis, and proliferation in cholangiocellular carcinoma of the liver. The results obtained were compared with pathohistological stage (according to UICC) and grade and with disease related survival rate. In 41 curatively (R0–) resected intrahepatic cholangiocellular carcinomas, the status of the p53 gene was determined by direct sequencing of exons 4–9 and immunohistochemically. Apoptosis was assessed using the in situ end labeling (ISEL) technique in combination with morphological criteria. Proliferation was analyzed by immunohistochemistry of MIB-1 (Ki-67), Proliferating cell nuclear antigen (PCNA), and silver-stained nucleolar organizer regions (AgNOR). The results obtained were compared with pathohistological stage (according to UICC), grade, several other histopathological factors, and survival rate. Mutations of p53 were detected in 15/41 carcinomas examined (37%). The most common change was a GC and CT transition, changing the hot spot amino acid determined by exons 4–8. Of these 15 tumors, 14 were also p53-positive by immunohistochemistry. In each carcinoma examined, we could demonstrate MIB-1, PCNA, and AgNOR dots and also apoptotic cells in variable proportions. The proliferation markers showed a significant correlation among themselves. In univariate survival analysis, the extent of the primary tumor, lymph node status, grade, and p53 were significant factors influencing patient survival. Performing multivariate Cox regression survival analysis, however, only the extent of primary tumor and lymph node status had an independent prognostic impact. Apoptosis was not related to patient prognosis or to other parameters examined. In conclusion, these results indicated that p53 could serve as an additional prognostic parameter that could provide auxiliary information for patient outcome. However, tumor stage and lymph node involvement were the strongest prognostic factors. We failed to establish apoptosis or other pathological parameters as factors predicting the prognosis of patients with cholangiocellular carcinoma.     

Hypertension-Related Morbidity and Mortality in African Americans—Why We Need to Do Better

Almost one third of adults in the United States have hypertension. Prevalence data among different racial or ethnic groups indicate that a disproportionate number of African Americans have hypertension compared with non-Hispanic whites and Mexican Americans. Earlier onset of high blood pressure and greater severity of hypertension contribute to a greater burden of hypertensive target organ damage in African Americans and may be a factor in the shorter life expectancy of this population compared with white Americans. There is a clear need for improved management of hypertension in African Americans via therapeutic lifestyle interventions and pharmacotherapy. While there is some evidence that particular antihypertensive agent classes provide blood pressure-lowering advantages over others, there is no support for withholding agents of any one class. When given as monotherapy, diuretics and calcium channel blockers may be relatively more effective in lowering blood pressure in African Americans than β blockers, angiotensin-converting enzyme inhibitors, and angiotensin II receptor blockers. However, when combined with a diuretic, African Americans respond as well to these agents as other racial groups. Combination therapy using antihypertensive agents with differing modes of action provides additive antihypertensive efficacy and is well tolerated. Recent guidelines recommend combination therapy as the standard of care for patients with significant blood pressure elevation, especially those with diabetes mellitus and renal disease. These comorbidities are more common in African Americans and indicate the potential need for initial therapy with more than one agent or a combination of agents in one pill.     

Efficacy and safety of fixed combinations of irbesartan/hydrochlorothiazide in older vs younger patients with hypertension uncontrolled with monotherapy

Subgroup analysis of the Irbesartan/Hydrochlorothiazide Blood Pressure Reductions in Diverse Patient Populations (INCLUSIVE) trial evaluated the efficacy and safety of irbesartan/hydrochlorothiazide (HCTZ) fixed combinations in patients aged 65 years or older with uncontrolled systolic blood pressure (SBP) after >or= 4 weeks of antihypertensive monotherapy. The INCLUSIVE trial was a prospective, open-label, single-arm trial carried out in 119 sites. Of 844 patients completing placebo treatment, 212 were aged 65 years or older. Participants received treatment with placebo (4-5 weeks), HCTZ 12.5 mg (2 weeks), irbesartan/HCTZ 150/12.5 mg (8 weeks), and then irbesartan/HCTZ 300/25 mg (8 weeks). From baseline to week 18 (n=184, intent-to-treat population), mean change in SBP was -23.0+/-13.3 mm Hg (P<.001) and diastolic BP (DBP) was -10.9+/-7.7 mm Hg (P<.001). Mean SBP/DBP at study end was 134.0+/-14.7/75.1+/-8.4 mm Hg, and SBP, DBP, and SBP/DBP goal was achieved in 73%, 96%, and 72% of patients, respectively. Irbesartan/HCTZ combination therapy allowed SBP goal attainment in 73% of patients aged 65 years or older whose hypertension was previously uncontrolled with antihypertensive monotherapy.