Integrative analysis of hepatic transcriptional profiles reveals genetic regulation of atherosclerosis in hyperlipidemic Diversity Outbred-F1 mice

Atherogenesis is an insipidus but precipitating process leading to serious consequences of many cardiovascular diseases (CVD). Numerous genetic loci contributing to atherosclerosis have been identified in human genome-wide association studies, but these studies have limitations in the ability to control environmental factors and to decipher cause/effect relationships. To assess the power of hyperlipidemic Diversity Outbred (DO) mice in facilitating quantitative trait loci (QTL) analysis of complex traits, we generated a high-resolution genetic panel of atherosclerosis susceptible (DO-F1) mouse cohort by crossing 200 DO females with C57BL/6J males carrying two human genes: encoding apolipoprotein E3-Leiden and cholesterol ester transfer protein. We examined atherosclerotic traits including plasma lipids and glucose in the 235 female and 226 male progeny before and after 16 weeks of a high-fat/cholesterol diet, and aortic plaque size at 24 weeks. We also assessed the liver transcriptome using RNA-sequencing. Our QTL mapping for atherosclerotic traits identified one previously reported female-specific QTL on Chr10 with a narrower interval of 22.73 to 30.80 Mb, and one novel male-specific QTL at 31.89 to 40.25 Mb on Chr19. Liver transcription levels of several genes within each QTL were highly correlated with the atherogenic traits. A majority of these candidates have already known atherogenic potential in humans and/or mice, but integrative QTL, eQTL, and correlation analyses further pointed Ptprk as a major candidate of the Chr10 QTL, while Pten and Cyp2c67 of the Chr19 QTL in our DO-F1 cohort. Finally, through additional analyses of RNA-seq data we identified genetic regulation of hepatic transcription factors, including Nr1h3, contributes to atherogenesis in this cohort. Thus, an integrative approach using DO-F1 mice effectively validates the influence of genetic factors on atherosclerosis in DO mice and suggests an opportunity to discover therapeutics in the setting of hyperlipidemia.

Flavan-3-ols and Cardiometabolic Health: First Ever Dietary Bioactive Guideline

Guideline recommendation for a plant bioactive such as flavan-3-ols is a departure from previous recommendations because it is not based on deficiencies but rather improvement in health outcomes. Nevertheless, there is a rapidly growing body of clinical data reflecting benefits of flavan-3-ol intake that outweigh potential harms. Thus, the objective of the Expert Panel was to develop an intake recommendation for flavan-3-ols and cardiometabolic outcomes to inform multiple stakeholders including clinicians, policymakers, public health entities, and consumers. Guideline development followed the process set forth by the Academy of Nutrition and Dietetics, which includes use of the Evidence to Decision Framework. Studies informing this guideline (157 randomized controlled trials and 15 cohort studies) were previously reviewed in a recently published systematic review and meta-analysis. Quality and strength-of-evidence along with risk-of-bias in reporting was reviewed. In drafting the guideline, data assessments and opinions by authoritative scientific bodies providing guidance on the safety of flavan-3-ols were considered. Moderate evidence supporting cardiometabolic protection resulting from flavan-3-ol intake in the range of 400-600 mg/d was supported in the literature. Further, increasing consumption of dietary flavan-3-ols can help improve blood pressure, cholesterol concentrations, and blood sugar. Strength of evidence was strongest for some biomarkers (i.e., systolic blood pressure, total cholesterol, HDL cholesterol, and insulin/glucose dynamics). It should be noted that this is a food-based guideline and not a recommendation for flavan-3-ol supplements. This guideline was based on beneficial effects observed across a range of disease biomarkers and endpoints. Although a comprehensive assessment of available data has been reviewed, evidence gaps identified herein can inform scientists in guiding future randomized clinical trials.

The Role of Histone Acetylation and the Microbiome in Phytochemical Efficacy for Cardiovascular Diseases

Cardiovascular diseases (CVD) are the main cause of death worldwide and create a substantial financial burden. Emerging studies have begun to focus on epigenetic targets and re-establishing healthy gut microbes as therapeutic options for the treatment and prevention of CVD. Phytochemicals, commonly found in fruits and vegetables, have been shown to exert a protective effect against CVD, though their mechanisms of action remain incompletely understood. Of interest, phytochemicals such as curcumin, resveratrol and epigallocatechin gallate (EGCG) have been shown to regulate both histone acetylation and microbiome re-composition. The purpose of this review is to highlight the microbiome-epigenome axis as a therapeutic target for food bioactives in the prevention and/or treatment of CVD. Specifically, we will discuss studies that highlight how the three phytochemicals above alter histone acetylation leading to global changes in gene expression and CVD protection. Then, we will expand upon these phytochemicals to discuss the impact of phytochemical-microbiome-histone acetylation interaction in CVD.

Dietary natural products as epigenetic modifiers in aging-associated inflammation and disease

Covering: up to 2020Chronic, low-grade inflammation is linked to aging and has been termed "inflammaging". Inflammaging is considered a key contributor to the development of metabolic dysfunction and a broad spectrum of diseases or disorders including declines in brain and heart function. Genome-wide association studies (GWAS) coupled with epigenome-wide association studies (EWAS) have shown the importance of diet in the development of chronic and age-related diseases. Moreover, dietary interventions e.g. caloric restriction can attenuate inflammation to delay and/or prevent these diseases. Common themes in these studies entail the use of phytochemicals (plant-derived compounds) or the production of short chain fatty acids (SCFAs) as epigenetic modifiers of DNA and histone proteins. Epigenetic modifications are dynamically regulated and as such, serve as potential therapeutic targets for the treatment or prevention of age-related disease. In this review, we will focus on the role for natural products that include phytochemicals and short chain fatty acids (SCFAs) as regulators of these epigenetic adaptations. Specifically, we discuss regulators of methylation, acetylation and acylation, in the protection from chronic inflammation driven metabolic dysfunction and deterioration of neurocognitive and cardiac function.

Emodin and emodin-rich rhubarb inhibits histone deacetylase (HDAC) activity and cardiac myocyte hypertrophy

Pathological cardiac hypertrophy is a classical hallmark of heart failure. At the molecular level, inhibition of histone deacetylase (HDAC) enzymes attenuate pathological cardiac hypertrophy in vitro and in vivo. Emodin is an anthraquinone that has been implicated in cardiac protection. However, it is not known if the cardio-protective actions for emodin are mediated through HDAC-dependent regulation of gene expression. Therefore, we hypothesized that emodin would attenuate pathological cardiac hypertrophy via inhibition of HDACs, and that these actions would be reflected in an emodin-rich food like rhubarb. In this study, we demonstrate that emodin and Turkish rhubarb containing emodin inhibit HDAC activity in vitro, with fast-on, slow-off kinetics. Moreover, we show that emodin increased histone acetylation in cardiomyocytes concomitant to global changes in gene expression; gene expression changes were similar to the well-established pan-HDAC inhibitor trichostatin A (TSA). We additionally present evidence that emodin inhibited phenylephrine (PE) and phorbol myristate acetate (PMA)-induced hypertrophy in neonatal rat ventricular myocytes (NRVMs). Lastly, we demonstrate that the cardioprotective actions of emodin are translated to an angiotensin II (Ang) mouse model of cardiac hypertrophy and fibrosis and are linked to HDAC inhibition. These data suggest that emodin blocked pathological cardiac hypertrophy, in part, by inhibiting HDAC-dependent gene expression changes.

HDAC1/2-mediated regulation of JNK and ERK phosphorylation in bovine mammary epithelial cells in response to TNF-α

Bovine mammary epithelial cells (MAC-Ts) are a common cell line for the study of mammary epithelial inflammation; these cells are used to mechanistically elucidate molecular underpinnings that contribute to bovine mastitis. Bovine mastitis is the most prevalent form of disease in dairy cattle that culminates in annual losses of two billion dollars for the US dairy industry. Thus, there is an urgent need for improved therapeutic strategies. Histone deacetylase (HDAC) inhibitors are efficacious in rodent models of inflammation, yet their role in bovine mammary cells remain unclear. HDACs have traditionally been studied in the regulation of nucleosomal DNA, in which deacetylation of histones impact chromatin accessibility and gene expression. Using MAC-T cells stimulated with tumor necrosis factor α (TNF-α) as a model for mammary cell inflammation, we report that inhibition of HDACs1 and 2 (HDAC1/2) attenuated TNF-α-mediated inflammatory gene expression. Of note, we report that HDAC1/2-mediated inflammatory gene expression was partly regulated by c-Jun N-terminal kinase (JNK) and extracellular signal-regulated kinase (ERK) phosphorylation. Here, we report that HDAC1/2 inhibition attenuated JNK and ERK activation and thus inflammatory gene expression. These data suggest that HDACs1 and 2 regulate inflammatory gene expression via canonical (i.e., gene expression) and noncanonical (e.g., signaling dependent) mechanisms. Whereas, further studies using primary cell lines and animal models are needed. Our combined data suggest that HDAC1/2-specific inhibitors may prove efficacious for the treatment of bovine mastitis.

Food Bioactive HDAC Inhibitors in the Epigenetic Regulation of Heart Failure

Approximately 5.7 million U.S. adults have been diagnosed with heart failure (HF). More concerning is that one in nine U.S. deaths included HF as a contributing cause. Current HF drugs (e.g., β-blockers, ACEi) target intracellular signaling cascades downstream of cell surface receptors to prevent cardiac pump dysfunction. However, these drugs fail to target other redundant intracellular signaling pathways and, therefore, limit drug efficacy. As such, it has been postulated that compounds designed to target shared downstream mediators of these signaling pathways would be more efficacious for the treatment of HF. Histone deacetylation has been linked as a key pathogenetic element for the development of HF. Lysine residues undergo diverse and reversible post-translational modifications that include acetylation and have historically been studied as epigenetic modifiers of histone tails within chromatin that provide an important mechanism for regulating gene expression. Of recent, bioactive compounds within our diet have been linked to the regulation of gene expression, in part, through regulation of the epi-genome. It has been reported that food bioactives regulate histone acetylation via direct regulation of writer (histone acetyl transferases, HATs) and eraser (histone deacetylases, HDACs) proteins. Therefore, bioactive food compounds offer unique therapeutic strategies as epigenetic modifiers of heart failure. This review will highlight food bio-actives as modifiers of histone deacetylase activity in the heart.

Natural product inhibitors of acetyl-lysine erasers in the prevention and treatment of heart failure

Background: Heart failure (HF) is a major public health concern, with five-year mortality rates following first admission for HF being approximately 50%, thereby stressing the need for novel therapeutic approaches. Histone deacetylases (HDACs) govern lysine acetylation of histone tails that regulates nucleosmal DNA. HDAC inhibitors have emerged as efficacious therapies in pre-clinical models of HF. Interest in diet-gene interactions has given rise to the study of ‘food bioactives’ as epigenetic regulators of gene expression that control human health and disease. These reports demonstrate that bioactive food compounds regulate epigenetic marks that link diet to gene regulation. In fact, others have also shown that bioactive compounds can target HDACs for inhibition; accordingly, bioactive food compounds offer unique opportunities for therapeutic intervention and prevention of heart failure.  Lastly, there is emerging interest into how these food bioactives function together or as additives within foods ‘functional foods’ to regulate epigenetic disease. This review will highlight bioactive compound HDAC inhibitors and their role in the heart.Keywords: acetylation, bioactive compounds, dietary HDAC inhibitors, HDACs, histone deacetylases    

Use of Saliva Biomarkers to Monitor Efficacy of Vitamin C in Exercise-Induced Oxidative Stress

Saliva is easily obtainable for medical research and requires little effort or training for collection. Because saliva contains a variety of biological compounds, including vitamin C, malondialdehyde, amylase, and proteomes, it has been successfully used as a biospecimen for the reflection of health status. A popular topic of discussion in medical research is the potential association between oxidative stress and negative outcomes. Systemic biomarkers that represent oxidative stress can be found in saliva. It is unclear, however, if saliva is an accurate biospecimen as is blood and/or plasma. Exercise can induce oxidative stress, resulting in a trend of antioxidant supplementation to combat its assumed detriments. Vitamin C is a popular antioxidant supplement in the realm of sports and exercise. One potential avenue for evaluating exercise induced oxidative stress is through assessment of biomarkers like vitamin C and malondialdehyde in saliva. At present, limited research has been done in this area. The current state of research involving exercise-induced oxidative stress, salivary biomarkers, and vitamin C supplementation is reviewed in this article.

Transforming growth factor-beta 1, activin and follistatin in patients with hepatocellular carcinoma and patients with alcoholic cirrhosis

BACKGROUND

Transforming growth factor-beta 1 (TGF-beta1) exerts an inhibitory effect on DNA synthesis in hepatocytes. Activin, through different mechanisms, also exhibits an apoptotic effect on hepatocytes. Follistatin antagonizes the actions of activin.

METHODS

Patients with hepatocellular carcinoma (HCC, n = 20), patients with alcoholic cirrhosis (n = 12), patients with cirrhosis due to other causes (n = 5) and normal controls (n = 19) were studied. TGF-beta1, activin and follistatin concentrations in blood and ascites were measured by ELISA.

RESULTS

All three groups of patients had significantly higher serum levels of total TGF-beta1, activin and follistatin compared to those of controls. In patients with HCC, the total TGF-beta1 level correlated negatively with tumour size (r = -0.644, P = 0.001). The activin level correlated with alkaline phosphatase (ALP) level (r = 0.374, P = 0.046). The follistatin level correlated with the ALP level (r = 0.404, P = 0.026), and the glutamyl transpeptidase level (r = 0.457, P = 0.01). In patients with alcoholic cirrhosis, serum activin correlated with the Child-Pugh score (r = 0.601, P = 0.01). The levels of the cytokines in ascites (n = 16) did not correlate with the corresponding levels in serum.

CONCLUSIONS

Serum levels of total TGF-beta1, activin and follistatin were elevated in patients with hepatocellular carcinoma and in patients with alcoholic cirrhosis. Apoptosis of tumour cells may be reduced by a subsequent decrease in serum TGF-beta1 levels when the tumours expand in size. Activin and follistatin were associated with tumour activity, as both correlated with ALP and/or GGT levels. Further studies are required to define the exact relationships between these cytokines, the dynamics of tumour growth and their significance in cirrhosis.

Characterization of serum activin-A and follistatin and their relation to virological and histological determinants in chronic viral hepatitis

BACKGROUND/METHODS

Hepatocyte proliferation in viral hepatitis is regulated by a number of growth factors. Activin-A inhibits hepatocyte DNA synthesis while follistatin, a potent activin-A antagonist, promotes liver regeneration. We report the first study of activin-A and follistatin in human viral hepatitis. Sera from 15 normal subjects, 22 hepatitis B and 47 hepatitis C patients were analysed for activin-A and follistatin and correlated with serological and histological markers of liver injury and with specific immunohistochemistry.

RESULTS

All groups showed immunoreactivity for activin with hepatocyte localisation. Serum activin-A was significantly increased in viral hepatitis patients compared to controls, was greater in hepatitis B compared to hepatitis C, and correlated with serum aminotransferase and hepatitis B viral replication. A concurrent rise in serum follistatin was not observed in either group, but serum follistatin correlated inversely with hepatitis B DNA levels. Although hepatocyte apoptosis in hepatitis C and proliferation in both groups was significantly elevated compared to controls, there was no correlation with serum activin-A or follistatin.

CONCLUSIONS

Activin-A and follistatin are constitutively expressed in human liver and serum concentrations are increased in viral hepatitis. Dysregulation of the activin/follistatin axis may be linked to hepatitis B replication but does not correlate with hepatocyte apoptosis.

Serum inhibin, activin and follistatin in postmenopausal women with epithelial ovarian carcinoma

OBJECTIVE

To investigate the role of serum inhibin A, inhibin pro-alphaC immunoreactivity, activin A, and follistatin in postmenopausal women with epithelial ovarian cancer.

DESIGN

Case-control study.

SAMPLE

e Serum samples from 27 postmenopausal women with epithelial ovarian cancer and 54 controls from the general population participating in an ovarian cancer screening trial.

RESULTS

Women with epithelial ovarian cancer had significantly higher serum levels of pro-alphaC immunoreactivity (P = 0.03), activin A (P = 0.004) and follistatin (P = 0.04), but not inhibin A (P = 0.13). Using the 90th centile in the control group as the cut off, pro-alphaC levels were elevated in 41% of women with epithelial ovarian cancer, while inhibin A was elevated in only 15%. Using the 95th centile as the cut off, serum pro-alphaC was elevated in only 11% of women with epithelial ovarian cancer (3/27), while activin A was elevated in 48% (11/23). Follicle stimulating hormone levels were significantly lower in women with epithelial ovarian cancer (P = 0.01). Although, inhibin-related peptides can modulate follicle stimulating hormone levels, there was no correlation between inhibin A, pro-alphaC immunoreactivity, activin A or follistatin and follicle stimulating hormone.

CONCLUSION

These data demonstrate that though there is preferential secretion of precursor forms of the alpha subunit rather than dimeric inhibin A by epithelial ovarian cancer, pro-alphaC is unlikely to be a useful tumour marker. Activin A is more commonly elevated in postmenopausal women with epithelial ovarian cancer and its role as a tumour marker in the diagnosis and screening of epithelial ovarian cancer warrants further evaluation.

Regulation of activin A, inhibin A, and follistatin production in human amnion and choriodecidual explants by inflammatory mediators

OBJECTIVE

To determine the effects of inflammatory mediators on the production of activin A, inhibin A, and the binding protein follistatin in term amnion and choriodecidual tissues.

METHODS

The effects of interleukin-1 beta (IL-1 beta; 1 ng/mL), tumor necrosis factor-alpha (TNF-alpha; 10 ng/mL), and bacterial lipopolysaccharide (LPS; 5 microg/mL) on production rates of activin A, inhibin A, and follistatin by term choriodecidual and amnion membranes in explant culture were determined using specific enzyme-linked immunoabsorbent assays.

RESULTS

All explants (n = 6 placentas) produced detectable amounts of activin A, inhibin A, and follistatin under basal conditions; choriodecidual production rates were more than tenfold higher than amnion rates. In amnion explants, activin A production was stimulated by IL-1 beta and TNF-alpha to 450 +/- 155.4% and 531 +/- 170.8% of control, respectively (mean +/- standard error of the mean; P <.05 by analysis of variance), whereas production of inhibin and follistatin was stimulated to a much more modest extent. Similar responses were observed in the choriodecidual explants. Lipopolysaccharide had no significant effect on amnion activin A production, but stimulated choriodecidual production to 290 +/- 34% of control. Lipopolysaccharide exerted only limited effects on inhibin A and follistatin production.

CONCLUSIONS

Treatment with proinflammatory mediators resulted in a preferential increase in activin A production compared with that of inhibin A or follistatin. These findings suggest that inflammation of the gestational membranes could result in increased local activin A production and bioactivity.

Maternal serum total activin A and follistatin in pregnancy and parturition

OBJECTIVE

To examine changes in maternal serum levels of activin A and follistatin during pregnancy and labour.

DESIGN

In three cross sectional and three longitudinal studies venous blood was collected from women during pregnancy, spontaneous labour, labour induction and prior to elective caesarean section for the measurement of activin A and follistatin.

SETTING

Monash Medical Centre, Clayton, Victoria, Australia.

POPULATION

One hundred and twenty-three women participated in a cross sectional study in pregnancy, 18 women in two longitudinal pregnancy studies, 36 women in a cross sectional labour study, nine women in a longitudinal study of labour induction. Ten women undergoing elective caesarean section were also studied.

METHODS

Activin A and follistatin were measured using two sensitive and specific enzyme-linked immunosorbent assays.

RESULTS

In the cross sectional study of pregnancy, mean (SEM) maternal serum activin A and follistatin levels increased towards term (2.4 ng/mL (0.3) and 1.8 ng/mL (0.3) in first trimester to 18.9 ng/mL (3.8) and 5.3 ng/mL (0.9) at term, respectively), but the longitudinal study revealed that levels plateau in the last three weeks of pregnancy (16.0 ng/mL (2.6) and 6.2 ng/mL (1.4) at 37 weeks and 16.6 ng/mL (3.5) and 6.2 ng/mL (0.5) before labour for activin A and follistatin, respectively). There was no difference in levels of activin A and follistatin between women delivered by caesarean section and labouring women at term (14.9 ng/mL (2.8) vs 11.0 ng/mL (0.93) and 5.95 ng/mL (0.67) vs 5.71 ng/mL (0.63), respectively) and levels of both proteins did not alter throughout spontaneous or induced labour.

CONCLUSIONS

We believe that these data argue against activin A playing an acute role in the initiation or regulation of human parturition.

Changes in serum inhibin, activin and follistatin concentrations during puberty in girls

Serum concentrations of inhibin A, inhibin B, activin A and follistatin were determined using two-site enzyme-linked immunosorbent assays (ELISA) during pubertal ovarian development in 28 girls and five follicular phase women. Blood obtained every 15 to 20 min overnight was pooled for peptide determination. Serum inhibin A concentrations increased in mid puberty, exhibiting positive correlations with bone age (r = 0.527, P = 0.0016) and oestradiol concentrations (r = 0.581, P = 0.0005). Inhibin B concentrations peaked in mid puberty and declined thereafter, but remained greater than concentrations seen in prepubertal girls, and correlating positively with oestradiol (r = 0.362, P = 0.046) and follicle stimulating hormone (FSH) concentrations (r = 0.369, P = 0.038). Total activin A concentrations did not vary significantly across pubertal stages. Total follistatin concentrations, determined by radioimmunoassay, decreased with advancing puberty, exhibiting negative correlations with bone age (r = -0.634, P = 0.0001) and oestradiol concentration (r = -0.687, P = 0.0001). Follistatin concentrations determined by an ELISA specific for follistatin 288 were greatest in mid-pubertal girls, but concentrations in late puberty were less than those in early puberty. The free follistatin assay indicated that all circulating follistatin was activin-bound. These results suggest that significant changes in serum concentrations of FSH-regulatory peptides accompany the onset of puberty.

Increased maternal serum activin A but not follistatin levels in pregnant women with hypertensive disorders

Activin A levels are elevated in maternal serum of pregnant women with hypertensive disturbances. Because follistatin is a circulating binding protein for activin A, the present study was designed to evaluate whether serum follistatin and activin A levels also change in patients with hypertensive disorders in the last gestational trimester. The study design was a controlled survey performed in the setting of an academic prenatal care unit. Healthy pregnant women (controls, n=38) were compared with patients suffering from pregnancy-induced hypertension (PIH, n=18) or pre-eclampsia (n=16). In addition, the study included a subset of patients with pre-eclampsia associated with intrauterine growth restriction (IUGR, n=5). Maternal blood samples were withdrawn at the time of diagnosis (patients) or in a random prenatal visit (controls), and serum was assayed for follistatin and activin A levels using specific enzyme immunoassays. Hormone concentrations were corrected for gestational age by conversion to multiples of median (MoM) of the healthy controls of the same gestational age. Follistatin levels were not different between controls and patients, while activin A levels were significantly increased in patients with PIH (1.8 MoM), pre-eclampsia (4.6 MoM), and pre-eclampsia+IUGR (3.2 MoM, P<0.01, ANOVA). The ratio between activin A and follistatin was significantly increased in patients with PIH (1.5 MoM) and was further increased in patients with pre-eclampsia (4.5 MoM) and in the group with pre-eclampsia+IUGR (2.6 MoM). Follistatin levels were positively correlated with gestational age in control subjects (r=0. 36, P<0.05) and in patients with PIH (r=0.46, P<0.05) or pre-eclampsia (r=0.61, P<0.01), while activin A correlated with gestational age only in the healthy control group (r=0.69, P<0.0001). The finding of apparently normal follistatin and high activin A levels in patients with PIH and pre-eclampsia suggests that unbound, biologically active, activin A is increased in women with these gestational diseases.

Expression of activin A and follistatin core proteins by human prostate tumor cell lines

Activin and follistatin (FS) messenger RNA and protein are expressed and localized to human prostate tissue from men with high grade cancer and to human prostate tumor cell lines LNCaP, DU145, and PC3. Although activin A induces apoptosis and inhibits cell proliferation in LNCaP cells, PC3 cells are insensitive to the effect of exogenous addition of activin A. The results of this study show that activin A and FS are produced and can be measured by specific enzyme-linked immunosorbent assays in PC3 cells and media but are not detectable in LNCaP cells. Over 10 days in culture, the production of activin A by PC3 cells declines and is inversely correlated (r = -0.779) to FS288 production, which steadily increases and is significantly elevated compared with Day 1 of culture. The presence of FS288 and FS315 proteins was confirmed by immunocytochemistry and showed that only PC3 cells produced the FS288 isoform. Western blotting of PC3 cell media confirmed the presence of the FS288 isoform. Blockade of FS288 activity with a neutralizing antibody rendered PC3 cells responsive to activin A, as measured by inhibition of proliferation. Collectively, these results suggest that PC3 tumor cells are insensitive to activin A because they produce measurable amounts of activin ligand and FS288 protein, which is capable of blocking the autocrine response of these cells to activin A.

Overexpression of activin A in the skin of transgenic mice reveals new activities of activin in epidermal morphogenesis, dermal fibrosis and wound repair

Recently we demonstrated a strong induction of activin expression after skin injury, suggesting a function of this transforming growth factor-beta family member in wound repair. To test this possibility, we generated transgenic mice that overexpress the activin betaA chain in the epidermis under the control of a keratin 14 promoter. The transgenic mice were significantly smaller than control littermates, and they had smaller ears and shorter tails. In their skin, the fatty tissue was replaced by connective tissue and a severe thickening of the epidermis was found. The spinous cell layer was significantly increased, and the epidermal architecture was highly disorganized. These histological abnormalities seem to result from increased proliferation of the basal keratinocytes and abnormalities in the program of keratinocyte differentiation. After skin injury, a significant enhancement of granulation tissue formation was detected in the activin-overexpressing mice, possibly as a result of premature induction of fibronectin and tenascin-C expression. These data reveal novel activities of activin in the regulation of keratinocyte proliferation and differentiation as well as in dermal fibrosis and cutaneous wound repair.

Concentrations of activin A, inhibin A and follistatin in human amnion, choriodecidual and placental tissues at term and preterm

To investigate labour-associated changes in production of activin and related hormones by gestational tissues we prepared extracts from amnion, choriodecidual and placental tissues delivered at term before labour (TNL; n=15), at term after spontaneous labour (TSL; n=15) or preterm (PTD; n=31) and measured concentrations of inhibin A, activin A and follistatin by ELISA. Activin concentrations in placental tissues were significantly (Mann-Whitney U-test; P<0.05) elevated with term labour (pg/mg protein, median; 1313 vs 2591), but in the PTD tissues concentrations were lower than those delivered spontaneously at term (3650 vs 2649). Inhibin concentrations also increased with term labour in the placenta (480 vs 686), but paradoxically decreased in amnion (188 vs 64) and choriodecidua (657 vs 358). Little or no significant changes in follistatin concentrations were observed. Concentrations of all three proteins were significantly correlated between amnion and choriodecidual tissues, and were significantly correlated with each other in most tissues (Spearman's ranked correlation; P<0.05). The activin:inhibin ratio in term amnion and choriodecidual tissues was increased 2 to 3-fold (P<0.0005 by Mann-Whitney U-test) after term labour, with similar trends also observed in the activin:follistatin ratio in placental tissue. These data suggest that a modest increase in placental activin and inhibin production may occur with labour at term. In addition, an increase in activin bioactivity may occur with labour, potentiating any paracrine effects of activin during parturition. The data, however, do not support an association between increased intrauterine activin biosynthesis and preterm delivery.

Maternal serum activin A and follistatin levels in pregnancies with Down syndrome

Inhibin A is now an established second-trimester maternal serum marker of Down syndrome. Since activin A has a common beta-subunit to inhibin A we evaluated this substance and its binding protein, follistatin, as potential markers. We studied 30 affected and 199 unaffected pregnancies at 13-16 weeks' gestation. There was a statistically significant increase in activin A level among the cases with 8 (27 per cent) exceeding the 90th centile in the controls, and 6 (20 per cent) above the 95th centile. However, the extent of overlap was too great to be of value in screening. There was a small decrease in follistatin levels among cases but it did not reach statistical significance.

Amniotic fluid concentrations of dimeric inhibins, activin A and follistatin in pregnancy

OBJECTIVE

The feto-placental unit is the major source of circulating concentrations of inhibin A and activin A in human pregnancy. The aim of this study was to measure the amniotic fluid concentrations of inhibin A, inhibin B, activin A and follistatin in pregnancies bearing male and female fetuses.

DESIGN AND METHOD

Amniotic fluid samples collected by amniocentesis were stored at -20 degrees C. Dimeric inhibins, 'total' activin A and 'total' follistatin were measured using specific two-site enzyme immunoassays. Samples were assayed blindly and the information on fetal sex was obtained from the cytogenetics laboratory.

RESULTS

Data show that amniotic fluid concentrations of inhibin A, inhibin B and activin A gradually increase with gestation whilst concentrations of follistatin are similar between weeks 15 and 20 of pregnancy. Mean amniotic fluid levels of inhibin A and inhibin B at 16 and 17 weeks gestation and mean activin A levels at 15 and 16 weeks gestation are considerably lower in pregnancies with male (n=24) compared with female (n=28) fetuses. Levels of follistatin are not different in the male and female fetal pregnancies at any studied gestation.

CONCLUSIONS

The results indicate that amniotic fluid contains high concentrations of inhibins (A and B), activin A and follistatin in early pregnancy suggesting that these hormones are produced by the fetal membranes and may be involved in the development of the fetus.

Amniotic fluid levels of dimeric inhibins, pro-alpha C inhibin, activin A and follistatin in Down's syndrome

OBJECTIVE

In the second trimester of pregnancy, inhibin A is significantly increased in maternal serum and decreased in amniotic fluid in Down's syndrome pregnancies compared to normal. We wished to further evaluate the levels of inhibin A, inhibin B, pro-alpha C inhibin, activin A and the binding protein follistatin in amniotic fluid in Down's syndrome and control pregnancies.

DESIGN

Case-matched control study.

PATIENTS

29 Down's syndrome and 290 chromosomally normal control pregnancies were identified from records and amniotic fluid, collected at second trimester amniocentesis, retrieved from routine storage for analysis.

MEASUREMENTS

Inhibin A, inhibin B, pro-alpha C inhibin, total activin A and follistatin were measured using sensitive and specific enzyme linked immunosorbent assays.

RESULTS

The median (10th-90th percentiles) amniotic fluid inhibin A level in the control pregnancies increased from 334 (122-553) ng/l at 14 weeks' to 695 (316-1475) ng/l at 19 weeks' gestation. The corresponding figures for inhibin B and the alpha-subunit precursor inhibin pro-alpha C were 632 (185-1354) and 2062 (1237-3381) ng/l, respectively at 14 weeks' and 2439 (748-5307) and 3115 (2021-6567) ng/l, respectively at 19 weeks' gestation. Total activin A increased from 3795 (1554-5296) at 14 weeks' to 5086 (3059-8224) at 18 weeks' gestation. Expressed as multiples of the median (MoM) the median (95% CI) amniotic fluid levels of inhibin A, inhibin B, pro-alpha C inhibin and acitivin A in the Down's syndrome samples were 0.77 (0.59-0.85), 0.94 (0.63-1.23), 0.77 (0.49-0.84) and 0.77 (0.53-0.87), respectively. Compared to controls the levels of inhibin A, pro-alpha C inhibin and activin A were significantly lower in Down's syndrome pregnancies (P < 0.01, Mann-Whitney U test). Follistatin levels in the controls declined slightly from 2106 (1421-3538) ng/l at 14 weeks' to 1600 (1281-2543) ng/l at 18 weeks' gestation. Levels in the Downs' syndrome pregnancies were similar to controls.

CONCLUSIONS

The data suggest that the production, secretion or metabolism of the inhibin alpha- and beta A-subunits is altered in Down's syndrome pregnancies in the second trimester.

Follistatin and activin A production by the male reproductive tract

Follistatin is a binding protein for the activin and inhibin family of hormones, regulating their biological activity. In the male reproductive tract, the interaction of these factors is likely to be involved in the regulation of the proliferation of several cell types. We have investigated the presence of follistatin and activin A in seminal plasma using specific immunoassays and have localized follistatin and activin/inhibin subunits in the adult human testis, prostate and seminal vesicle to establish their likely sources. High concentrations of immunoreactive follistatin were present in seminal plasma in normal men (mean 97.9 ng/ml; 1.43 ng/ml in peripheral plasma) and were similar in men with oligo/azoospermia and following vasectomy. Follistatin immunoreactivity was localized to both Leydig and Sertoli cells of the testis, and to epithelial cells of the prostate gland and seminal vesicle, which are likely to be the predominant sources of the hormone in seminal plasma. Activin A was also present in seminal plasma in normal men but was undetectable following vasectomy, thus deriving from the testis. Consistent with this finding, the betaA-subunit was immunolocalized in Sertoli and Leydig cells but was not present in seminal vesicle or prostate gland. The functional significance of the high concentrations of follistatin secreted into seminal plasma by the prostate gland and/or seminal vesicle is uncertain, but they may regulate the biological activity of testis-derived activin A and inhibin B.

A longitudinal study of maternal serum inhibin-A, inhibin-B, activin-A, activin-AB, pro-alphaC and follistatin during pregnancy

Maternal serum concentrations of inhibin-A, inhibin-B, activin-A, activin-AB, pro-alphaC-related inhibin forms, total follistatin, steroids and gonadotrophins were measured longitudinally in six normal singleton pregnancies. Maternal venous blood was collected randomly during a spontaneous follicular phase prior to donor insemination, at 5, 7, 9, 11, 16, 20, 24, 28, 32 and 36 weeks after the first missed menses and in the early puerperium. Steroid and gonadotrophin profiles conformed to previous reports. While at week 5 of gestation inhibin-A, activin-A and follistatin concentrations were similar to those at the follicular phase, all three increased progressively (P < 0.001) to maximal concentrations in week 36: approximately 48-fold (3740 +/- 1349 ng inhibin-A/ml), approximately 22-fold (6109 +/- 1443 ng activin-A/ml) and approximately 10-fold (3563 +/- 418 ng follistatin/ml) higher. Pro-alphaC concentrations reached a maximum in weeks 5 (approximately 5-fold, P < 0.001) and 36 (1027 +/- 174 pg/ml, P < 0.01). Inhibin-B (71 +/- 23 pg/ml prior to pregnancy) was undetectable (<12 pg/ml) between week 5-16 of gestation but increased slightly in the third trimester (26 +/- 7 pg/ml in week 36). Activin-AB was undetectable throughout pregnancy. Post-partum concentrations of inhibin-A (41 +/- 12 ng/ml), inhibin-B (<12 pg/ml), activin-A (950 +/- 149 pg/ml), pro-alphaC (128 +/- 22 pg/ml) and follistatin (990 +/- 79 ng/ml) were substantially lower than at week 36 of gestation. The activin-A:follistatin ratio increased from 0.5 in week 5 to 1.8 in week 36, suggesting that more free activin-A is available in the maternal circulation during late pregnancy.

Follistatin and activin A in extra-embryonic coelomic and amniotic fluids and maternal serum in early pregnancy

Follistatin is a specific binding protein which controls bioavailability of activins and inhibins which have an important role in fetal development. In the first trimester of pregnancy bioactive dimeric inhibins are found at high concentrations in the extra-embryonic coelomic fluid, but the distribution of follistatin and activins is not known. We have used recently developed immunoassays for follistatin, activin A and activin AB to determine their presence in the intrauterine compartments during early pregnancy. Follistatin was present in highest concentrations in the extra-embryonic coelomic fluid (11.72 +/- 1.70 ng/ml; median +/- SEM), with less in maternal serum (6.35 +/- 4.58) and lowest amounts in amniotic fluid (0.97 +/- 0.52). Follistatin concentrations in extra-embryonic coelomic fluid were highly correlated with both dimeric inhibin isoforms. Activin A was present in only barely detectable amounts in some samples of extra-embryonic coelomic fluid (41% of samples) and maternal serum (26%) and was undetectable in all amniotic fluid samples. Activin AB was undetectable in all compartments. The presence of follistatin in the amniotic and extra-embryonic coelomic fluids may regulate the availability of bioactive activins and inhibins which are released into the intrauterine compartments during the development of the fetus and placenta in early pregnancy.

Effects of active immunization of sheep against an amino terminal peptide of the inhibin alpha C subunit on intrafollicular levels of activin A, inhibin A and follistatin

Active immunization of ewes against inhibin (IMM) consistently increases ovulation rate but this response is not always accompanied by the expected rise in plasma FSH. Inhibin-related molecules also have local auto/paracrine effects within the ovary and the ovulatory response to IMM could be due to neutralization of one of these effects, independent of changing FSH levels. To investigate this, ovaries were collected from long-term IMM (n = 6) and control (CON; n = 8) ewes killed 48 h after progestagen withdrawal (late follicular phase) and all follicles > or = 3 mm were recovered to determine intrafollicular levels of inhibin A, activin A and follistatin by specific two-site immunoassay and oestradiol and testosterone by radioimmunoassay. Blood samples were collected to assess plasma FSH, oestradiol and inhibin antibody titres. Although plasma FSH levels were similar in IMM and CON ewes, IMM ewes had approximately 3-fold more follicles > or = 3 mm (P < 0.0001) and approximately 3-fold more oestrogenic follicle (P < 0.001) than CON ewes. Compared with CON ewes, follicles from IMM ewes had much higher concentrations of activin A (approximately 6-fold; P < 0.001) and inhibin A (approximately 3-fold; P < 0.001) but only slightly more follistatin (approximately 1.4-fold; not significant). The activin A:follistatin ratio in follicles from IMM ewes (approximately 1:1) was significantly higher (P < 0.001) than in follicles from CON ewes (approximately 0.3:1). Levels of inhibin antibody measured in follicular fluid (FF) from IMM ewes were similar to plasma levels. Given that activin A has been shown previously to up-regulate FSH receptors and aromatase activity in rat granulosa cells, the increase in intrafollicular activin A, unaccompanied by a rise in the concentration of its binding protein (follistatin), could explain how long-term IMM enhances follicle development and ovulation rate without necessarily promoting a sustained increase in FSH secretion.

Development, validation and application of an ultra-sensitive two-site enzyme immunoassay for human follistatin

Recent studies have found follistatin to be an important regulator of activin bioactivity. Whilst a number of assay formats have been described, all are of limited sensitivity and require the use of isotopes. Many use polyclonal antibodies. Furthermore, a wide range of follistatin preparations have been used as standards, complicating inter-laboratory comparison. We now describe an ultra-sensitive two-site enzyme immunoassay using a pair of mouse monoclonal antibodies raised against follistatin 288. The presence of sodium deoxycholate and Tween 20 in the diluent gave results for total (free and activin-dissociated) follistatin. The assay had a detection limit of <19 pg/ml and recovery of spiked follistatin 288 from amniotic fluid, serum seminal plasma, human follicular fluid and granulosa cell conditioned medium averaged 100.7 +/- 7.5%, 89.1 +/- 5.5%, 98 +/- 4.9%, 96 +/- 7.2% and 123.9 +/- 11% respectively. The intra- and interplate coefficients of variation were < 5%. An excess of activin-A (50 ng/ml) prior to assay did not affect follistatin recovery. Inhibin-A, inhibin-B, activin-A, activin-B and activin-AB had minimal cross-reactivity (<0.3%). However, follistatin 315 had a significant cross-reaction (9.9%). Serially diluted human samples gave dose-response curves parallel to the standard. Pooled human follicular fluid contained high concentrations of follistatin (approximately 242 ng/ml). Follistatin was also found in maternal serum during pregnancy (first trimester approximately 0.8 ng/ml, third trimester approximately 2.8 ng/ml), normal male serum (approximately 0.45 ng/ml), amniotic fluid (sixteen week approximately 3.63 ng/ml, term approximately 0.89 ng/ml), seminal plasma (2.4-30 ng/ml) and human granulosa cell conditioned media (approximately 0.44 ng/ml). Serial serum samples taken throughout the menstrual cycle of ten women showed fluctuating follistatin concentrations (approximately 0.62 ng/ml) with no apparent relationship to the stage of the cycle. Interestingly, pooled serum from postmenopausal women appeared to have higher follistatin levels than any of the normal women (approximately 1.4 ng/ml). The possible presence in certain samples of mixtures of follistatin isoforms with different immunoreactivities poses major problems of interpretation in this and all other current follistatin immunoassays. Further work is needed to identify the major immunoreactive forms in different tissues and fluids. Nevertheless, the new assay has a number of advantages over previous assays and should prove a useful tool for various clinical and physiological studies.

Expression and localization of activin subunits and follistatins in tissues from men with high grade prostate cancer

Activins are growth and differentiation factors that have growth inhibitory effects on LNCaP and DU145, but not PC3, human prostate tumor cell lines. Activin-binding proteins, follistatins, block the inhibitory actions of exogenously added activins on LNCaP and DU145 tumor cell lines. Based on these in vitro observations using human prostate tumor cell lines, the aims of this study were to determine whether activins and follistatins are expressed in the human prostate in tissues from men with high grade prostate cancer. The expression and cellular localization of these proteins in malignant and nonmalignant regions of these tissues were compared to determine whether any changes occur with progression to malignancy. The results demonstrate that activins and follistatins are synthesized in tissues from men with high grade prostate cancer, and that messenger ribonucleic acid (mRNA) and protein for the activin beta A- and beta B-subunits and follistatin is expressed and localized to poorly differentiated tumor cells. In the nonmalignant regions, activin beta A and beta B subunit mRNA and proteins are predominantly localized to the epithelium. Follistatin mRNA was expressed in the basal epithelial cells and in the fibroblastic stroma; however, the localization of follistatin proteins using two specific antisera demonstrated a difference between the follistatin isoforms expressed in basal cells and the stroma. In the progression to malignancy, the colocalization of follistatin and activins to the tumor cells in vivo implies that resistance to the growth inhibitory effects of activin may be conferred by follistatins.

Development, validation and application of a two-site enzyme-linked immunosorbent assay for activin-AB

Monoclonal antibodies, specific for the beta A and beta B subunits of activin, were used to develop a new two-site ELISA for activin-AB. The assay had a detection limit of 0.19 ng/ml. High concentrations of activin-AB were found in bovine, ovine and porcine follicular fluids (FF), with less in human FF (1310, 1730, 688 and 7 ng/ml respectively). Recovery of spiked activin-AB standard from human, bovine and ovine FFs and from homogenized human placental extracts averaged 91%, 115%, 115% and 94% respectively. Within-plate coefficients of variation for different concentration of activin-AB were between 1.3% and 2.67%. The between-plate coefficient of variation was 5.5%. Cross-reactivity experiments showed the high specificity of the assay for activin-AB, with inhibin-A, inhibin-B, follistatin, activin-A and activin-B all cross-reacting < 0.2%. Incubation with high concentrations of follistatin (500 ng/ml) prior to assay did not affect the recovery of activin-AB. Samples of bovine, porcine, ovine and human FF gave dose responses parallel to that of the standard, as did bovine granulosa cell-conditioned media. In human and porcine FF, levels of activin-A and activin-AB were similar whereas, in bovine and ovine FF, activin-A levels were approximately threefold higher than activin-A, nearly all of the endogenous activin-AB in bovine FF was detected in the eluate from gel permeation chromatography with an M(r) of > 700000 indicating its association with higher molecular weight binding protein(s). By contrast, after denaturation, immunoreactive activin-AB was detected with an M(r) of approximately 25000 consistent with the complete dissociation from binding proteins. Activin-A was detected in relatively high concentrations in human FF (approximately 5 ng/ml), homogenized placental extracts (4.35-95.5 ng/g), sera from pregnant women (> 4 ng/ml) and amniotic fluid (3-13 ng/ml), and in much lower concentrations in postmenopausal serum (500 pg/ ml), normal cycle serum (100-200 pg/ml), serum from gonadotrophin-treated women (200 pg/ml), and normal adult male serum (225 pg/ml). Activin-A was also found in the culture media from explants of human amnion, chorion, maternal decidua and placenta. In marked contrast, activin-AB was undetectable (< 0.19 ng/ml) in all of these samples with the exception of human FF (approximately 7 ng/ml). In conclusion, we have developed a sensitive and specific ELISA to measure total (bound+free) activin-AB. Preliminary results show a more restricted distribution of this isoform compared with activin-A. The presence of high levels of both activin-A and activin-AB in FF suggests a function for both isoforms in the developing ovarian follicle.

Adrenergic mechanisms in the hindlimb circulation of baboons

The effects of the adrenergic agonists norepinephrine, epinephrine, isoproterenol, and phenylephrine upon femoral arterial blood flow were measured in baboons before and after alpha (phenoxybenzamine) and beta (propranolol) adrenergic receptor blockade. Flow was measured with an electromagnetic flowmeter. Arterial and venous pressures were recorded simultaneously. Femoral vascular resistance was calculated from these data. Catecholamines were injected intra-arterially (10(-3)--10(0) mug, base, kg.(-1) and intravenously (1.0 mug kg.(-1) in a randomized sequence. All four adrenergic amines were vasodilators at low dose (10(-3) mug kg.(-1), intra-arterially) and this effect was abolished during beta adrenergic receptor blockade. Intra-arterial isoproterenol elicited dose-dependent increases in femoral flow; the other amines were vasoconstrictors at high doses. Alpha adrenergic blockade "reversed" the vasoconstrictor effects of these three amines. At the same dose isoproterenol increased flow more through the intra-arterial than the intravenous route. Conversely, norepinephrine and epinephrine were potent femoral vasodilators when injected intravenously. The findings indicate that the classical adrenergic amines are all vasodilators of the subhuman primate hindlimb at low doses due to their interaction with beta receptor sites. The fact that epinephrine and norepinephrine exert a greater increase in flow when given intravenously than when given intra-arterially is presumably secondary to increased arterial pressure, in turn due to the vasoconstrictor effects of these agents on other regional circulations.

Contractility of renal cortex following complete ureteral obstruction

Contractility of strips of renal cortex obtained from rabbit kidneys obstructed by complete ureteral ligation for 8 and 32 days was tested and compared with control tissue. Concentration-response data were obtained for norepinephrine, angiotensin, and 5-hydroxytrypamine, and were expressed as mg tension/cm of tissue. Control tissue tested simultaneously revealed minimal responses, but obstructed tissue containing modified interstital cells revealed statistically significant evidence of contraction in response to all three drugs studied. The response to norepinephrine could be blocked by the alpha adrenergic antagonist, phenoxybenzamine, but this drug did not significantly affect the response to angiotensin or 5-hydroxytryptamine. The findings are related to similar observations reported in stimulated fibroblasts of granulation tissue and are discussed in terms of the possible role this phenomenon may play in the pathogenesis of renal interstitial injury.