Insulin-like growth factor and insulin receptors in intestinal mucosa of neonatal calves

Intestinal development is modified by age and nutrition, mediated in part by insulin-like growth factors (IGF-I, IGF-II) and insulin. We have investigated whether expression of IGF-I, IGF-II and insulin receptors (IGF-IR, IGF-IIR and IR; measured by real-time RT-PCR) and binding capacity (Bmax) of IGF-IR, IGF-IIR and IR in the mucosa of the small and large intestine of neonatal calves are modified by age and different feeding regimes. In experiment 1, pre-term (GrP) and full-term (GrN) calves (after 277 and 290 days of pregnancy respectively) were killed immediately after birth before being fed; a further group of full-term calves were fed for 7 days and killed on day 8 of life (GrC(1-3)). In experiment 2, full-term calves were killed on day 8 after being fed first-colostrum for 7 days (GrCmax), colostrum of the first six milkings for 3 days (GrC(1-3)) or milk-based formula for 3 days (GrF(1-3)). Intestinal sites differed with respect to expression levels of IGF-IR (duodenum>jejunum in GrC(1-3); ileum>colon, duodenum> or = jejunum in GrF(1-3)), IGF-IIR (colon>duodenum and ileum in GrN), and IR (lowest in ileum in GrP and CrN; highest in colon in GrC(1-3) and GrCmax). They also differed with respect to Bmax of IGF-IR (ileum and colon>duodenum and jejunum in GrP; ileum and colon>jejunum in GrN; colon>jejunum in GrC(1-3); lowest in jejunum in GrF(1-3)), IGF-IIR (duodenum and colon>jejunum and ileum in GrP; duodenum>ilem and colon>jejunum in GrN; duodenum, jejunum and colon>ileum in GrCmax, GrC(1-3), and GrF(1-3)) and IR (ileum>duodenum, jejunum and colon in GrCmax, GrC(1-3), and GrF(1-3)). There were significant differences between groups in the expression of IGF-IR (GrF(1-3)> GrCmax and GrC(1-3) in ileum), IGF-IIR (GrN>GrP and GrC(1-3) in colon; GrN>GrC(1-3) in jejunum and total intestine), and IR (GrCmax>GrF(1-3) in colon) and in the Bmax of IGF-IR (GrP>GrN in colon; GrCmax>GrF(1-3) in jejunum), IGF-IIR (GrN>GrP in duodenum, ileum and total intestine; GrN>GrC(1-3) in duodenum, ileum, colon and total intestine) and IR (GrN>GrP in total intestine; GrC(1-3)>GrN in ileum and total intestine). In addition, Bmax values of IGF-IR, IGF-IIR and IR were correlated with villus circumference, villus height/crypt depth and proliferation rate of crypt cells at various intestinal sites. There were marked differences in Bmax of IGF-IR, IGF-IIR and IR dependent on mRNA levels, indicating that differences in Bmax were the consequence of differences in posttranslational control and of receptor turnover rates. In conclusion IGF-IR, IGF-IIR and IR expressions and Bmax in intestinal mucosa were different at different intestinal sites and were variably affected by age, but not significantly affected by differences in nutrition. Receptor densities were selectively associated with intestinal mucosa growth.

Identification of genes responsive to intracellular zinc depletion in the human colon adenocarcinoma cell line HT-29

Zinc is essential for the structural and functional integrity of cells and plays a pivotal role in the control of gene expression. To identify genes with altered mRNA expression level after zinc depletion, we employed oligonucleotide arrays with approximately 10,000 targets and used the human colon adenocarcinoma epithelial cell line HT-29 as a model. A low intracellular zinc concentration caused alterations in the steady-state mRNA levels of 309 genes at a threshold factor of 2.0. Northern blot analysis and/or real-time RT-PCR confirmed the array results for 12 of 14 selected targets. Genes identified as regulated based on microarray data encode mainly proteins involved in central pathways of intermediary metabolism (79 genes) including protein metabolism (21). We also identified five groups of genes important for basic cellular functions such as signaling (30), cell cycle control and growth (15), vesicular trafficking (15), cell-cell interaction (13), cytoskeleton (10) and transcription control (19). The latter group comprises several zinc finger-containing transcription factors of which the Kruppel-like factor 4 showed the most pronounced changes. Western blot analysis confirmed the increased expression level of this protein in cells grown under low zinc conditions. Our findings in a homogeneous cell population demonstrate that the molecular mechanisms by which cellular functions are altered at a low zinc status, occur via pleiotropic effects on gene expression. In conclusion, the pattern of zinc-affected genes may represent a reference for further studies to define the zinc regulon in mammalian cells.

Quantification of insulin-like growth factor-1 (IGF-1) mRNA: development and validation of an internally standardised competitive reverse transcription-polymerase chain reaction

To investigate the role of local IGF-1 mRNA expression in various tissues, we developed and validated a method which allows for a specific, sensitive and reliable quantification of IGF-1 mRNA: an internally standardised Reverse Transcription-Polymerase Chain Reaction (RT-PCR). A synthetic competitive template IGF-I standard cRNA (IGF-1 cRNA) was designed, which contains the same flanking primer sequences used to amplify the wild type IGF-1 mRNA, but differs by 56 bp in length. To obtain the IGF-1 mRNA concentration present in tissue RNA samples, series of 250 ng total-RNA were spiked with three known quantities of the standard IGF-1 cRNA, incubated for competitive RT-PCR reactions and the two amplificates obtained (184 bp from IGF-1 cRNA and 240 bp from the wild type IGF-I mRNA) were subsequently separated and quantified by HPLC-UV. For every individual tissue RNA sample, the ratio R (R = competitor PCR product / wild type PCR product) was plotted against the number of starting molecules of the competitor IGF-1 cRNA. The initial amount of IGF-1 mRNA present in the sample can then be read off where R = 1. The validated assay had a detection limit of 1600 IGF-1 cRNA molecules/reaction, the intra-assay variation was 7.4% (n = 5) and linearity (r = 0.997) was given between 140 ng to 840 ng total-RNA input. The present method was first applied to study the effect of long term castration on the IGF-1 expression rates in bovine tissues. The hepatic IGF-1 mRNA concentrations were well correlated (r = 0.81) with the plasma concentrations as quantified by RIA and were higher in intact than in castrated animals. In two skeletal muscles (m. splenius and m. gastrocnemius) IGF-1 mRNA concentrations were 20- and 35- times lower than in liver, respectively, without any differences between steers and bulls. In bulls, the IGF-1 mRNA expression was higher in m. splenius (p < 0.01) than m. gastrocnemius, indicating that locally produced IGF-1 might be important for sexually dimorphic muscle growth patterns.

Quantification of insulin-like growth factor-1 (IGF-1) mRNA: modulation of growth intensity by feeding results in inter- and intra-tissue-specific differences of IGF-1 mRNA expression in steers

The effect of constant and compensating body growth velocities on IGF-1 mRNA expression was studied in various tissues of growing steers. Twenty-six steers were allocated to three groups in which the average daily gains were kept either constantly high on intensive feeding, low on pasture feeding or were accelerated to compensatory growth after feed restriction. All animals were slaughtered at 570+/-2.6 kg and samples were collected from liver, heart, kidney and from 4 different muscles (m. splenius, m. soleus, m. cutaneus truncii and m. semispinalis capitis), which were selected in order to include maximal differences in fibre composition as well as in growth impetus. IGF-1 mRNA was quantified by a validated internally standardised RT-PCR method. The amount of RNA extracted from the various tissues investigated was constant within each type of tissue and showed no differences between treatment groups. As indicated by a constant ratio between the amount of RNA extracted and the DNA concentrations, there was no effect of the feeding on total transcriptional activity. The order of IGF-1 mRNA abundance per g tissue was liver > > kidney > heart > skeletal muscle. The different feeding regimen resulted in significant differences of IGF-1 mRNA expression rates in all organs showing different patterns between organs. IGF-1 mRNA concentrations showed muscle specific differences and also divergent reactions in response to the differing growth rates. These results support that the liver is the main IGF-1 producing tissue; above that they indicate that skeletal muscle, in particular when taking its absolute mass into account, might considerably contribute to the IGF-1 levels in blood. Our findings demonstrate that IGF-1 mRNA expression is regulated tissue specifically not only between different organs but also within musculature.

Influence of Oral Application of Mycophenolic Acid on the Clinical Health Status of Sheep

Mycophenolic acid (MPA) is an immunosuppressive metabolite of various fungi, especially of Penicillium roqueforti, and can be found in considerable amounts in mouldy silage. The aim of this study was to investigate the effect of MPA on sheep. Thirty-six castrated male sheep aged 7 +/- 1 months were randomly divided into four groups of nine sheep. Different dosages of MPA were administered orally to all groups (group 1/2/3/4: 0/10/70/300 mg MPA/animal daily) for a period of 44 days. Throughout the trial, the sheep were examined daily. Jugular vein blood was taken twice weekly to analyse haematological and biochemical parameters. No significant influence was observed on the number of erythrocytes, thrombocytes, leucocytes (including differentiation), packed cell volume, haemoglobin-, glucose- and bilirubin-concentration, activity of alanine amino transferase, aspartate amino transferase and glutamate dehydrogenase. Even an oral application of up to 300 mg MPA/animal daily, which is equivalent to 5.4 mg/kg body weight, did not affect the sheep's general state of health and weight gain significantly. Mycophenolic acid and its glucuronide were analysed in plasma samples of groups treatments from day 1 on with mean concentrations up to 0.29 +/- 0.13 microg/ml (MPA) and 11.0 +/- 2.9 microg/ml (MPA glucuronide) respectively (group 4). There were no indications for a ruminal reduction of MPA. The postmortem dissection revealed minor alterations in lung, spleen, liver and kidneys, unrelated to the MPA dosage. The results of the study indicate that MPA concentrations occurring naturally in silage have no obvious impact on sheep health.

Apoptosis of human trabecular meshwork cells induced by transforming growth factor-beta2 in vitro

Whether transforming growth factor-beta2 (TGF-beta2) induces apoptosis of human trabecular meshwork cells was investigated in vitro. Cultured 3-5 passage human trabecular meshwork cells were treated with 0 (control), 0.32, 1, 3.2 ng/ml TGF-beta2 for 48 h and divided into control group and experimental group. The apoptosis of human trabecular meshwork cells was examined by transmission electron microscopy, TUNEL technique and flow cytometry. The results showed characteristic morphologic changes of apoptotic cells were observed under transmission electron microscopy. DNA fragmentation of human trabecular meshwork cells was found by TUNEL technique. Quantitative analysis of flow cytometry showed that percentages of apoptotic human trabecular meshwork cells were (2.79 +/- 0.44)%, (4.43 +/- 1.17)% and (9.60 +/- 2.05)% respectively with different concentrations [1 ng/ml (P<0.05), 3.2 ng/ml (P<0.01)] of TGF-beta2 with the difference being significant between experimental group and control group [(1.41 +/- 0.34)%]. It was concluded that TGF-beta2 can induce apoptosis of human trabecular meshwork cells in vitro and may be involved in the decrease of trabecular meshwork cells in the patients with primary open angle glaucoma and aging of normal people.

Effects of dexamethasone and colostrum intake on the somatotropic axis in neonatal calves

Glucocorticoids and colostrum feeding influence postnatal maturation of the somatotropic axis. We have tested the hypothesis that dexamethasone (Dexa) affects the somatotropic axis in neonatal calves dependent on colostrum intake. Calves were fed either with colostrum or with a milk-based formula (n = 14/group), and, in each feeding group, one-half of the calves were treated with Dexa (30 micro g. kg body wt-1. day-1). Pre- and postprandial blood samples were taken on days 1, 2, 4, and 5, and liver samples were taken on day 5 of life. Dexa increased insulin-like growth factor (IGF)-I, but decreased growth hormone (GH) and IGF-binding protein (IGFBP)-1 and -2 plasma concentrations and increased GH receptor (GHR) mRNA levels in liver. Dexa increased IGF-I mRNA levels only in formula-fed calves and increased hepatic GHR binding capacity, but only in colostrum-fed calves. Colostrum feeding decreased IGFBP-1 and -2 plasma concentrations and hepatic IGFBP-2 and -3 mRNA levels. In conclusion, Dexa and colostrum feeding promoted maturation of the somatotropic axis. Dexa effects partly depended on whether colostrum was fed or not.

Morphological Findings in Lymphatic Tissues of Sheep Following Oral Application of the Immunosuppressive Mycotoxin Mycophenolic Acid

Mycophenolic acid (MPA) is applied in immunosuppressive therapy after organ transplantation. As a common contaminant in silage, this substance is also frequently fed to sheep unintentionally. In this study, the effect of MPA on the immune system of sheep was examined. Four groups of 9 sheep each were fed 0, 0.5, 1.2, or 5 mg of MPA per kg body weight per day for 6 weeks. Then, the animals were slaughtered and various organs were examined macroscopically, histologically, and immunohistochemically. No effect of MPA on general health was detected. With increasing dose of MPA, germinal centres in the retropharyngeal lymph nodes displayed an activated morphology with numerous centroblasts. In the highest dose group, the sheep showed shrinkage of thymic lobules. The numbers of IgG or IgM positive plasma cells decreased in the ileum with increasing MPA-doses. These results suggest, that MPA in a high concentration may affect the morphology of immune organs of sheep.

Water and sediment microbiota diversity in response to temporal variation at the outlet of the Ibrahim River (Lebanon)

Bacterial diversity is an important factor controlling the functioning of aquatic ecosystems. With the critical sensitivity of the microbial community towards chemical and/or physical factors, this study aims to identify for the first time the microbiota of the Lebanese coastal Ibrahim River. Water and sediment samples were collected at the outlet of the river, between May 2016 and April 2017, covering a hydrological year. The main microbiological parameters were tested: total germs, total coliforms, fecal coliforms, Escherichia coli, and Enterococcus. A DNA extraction followed by NGS analysis was applied on both water and sediment samples, in order to investigate the bacterial diversity and the habitat specificity. The link between this microbial composition and seasonal variations was then investigated. Results showed fourteen different bacterial phyla, among which were major microorganisms, including a wide variety of pathogenic and commensal ones, frequently available in the aquatic ecosystem. Most of the detected water microbiota were mostly correlated to other freshwater samples, with the main dominance of 5 common phyla: Proteobacteria, Actinobacteria, Firmicutes, Bacteroidetes, and Acidobacteria with the average of 43%, 13%, 16%, 10%, and 4% respectively. Despite this overall similarity, multiple patterns were visible, confirming the influence of the temporal variations and the discharge influence on taxonomic diversity. Sediment samples contained the highest relative abundance of Proteobacteria, Firmicutes, and Bacteroidetes: with an average of 31%, 44%, and 22% respectively. Our study showed that the Ibrahim River outlet has a specific habitat clustering. The among-compartment bacterial community variation, which responded to changing environmental factors, approved the existence of a meaningful temporal heterogeneity.

Expression of estrogen and androgen receptor in the bovine gastrointestinal tract

Reproductive and maturational nutritive needs are examples for situations in which alterations in circulating concentrations of sex steroids are associated with changes in gastrointestinal function. In order to investigate whether there is a causal relationship between sex steroids and gastrointestinal function, we aimed to investigate the responsiveness for androgens and for estrogens of the bovine gastrointestinal tract. Using Northern blot analysis, estrogen receptor (ER) mRNA was detected in rumen tissue. Comparing the ER expression in rumen from females of different reproductive stages, we found that no differences related to cycle stage, pregnancy or parturition could be detected. In contrast, the ER expression rates in the uterus of the respective animals showed the same dependency of reproductive stage as demonstrated earlier for the ER protein, indicating that there might be a tissue specific regulation of ER. By in-situ hybridization of rumen tissue sections the expression of ER was localized in the epithelium of the papillae. In the muscular layer no positive signals for ER mRNA were observed. Above rumen, the presence of ER and androgen receptor (AR) mRNA was determined in various intestinal tissues using reverse transcription (RT) and polymerase chain reaction (PCR). Primers were selected from the bovine androgen and estrogen receptor sequence to amplify parts of the sequence coding for the hormone binding part of the respective receptor. The PCR amplifies were subsequently electrophoresed on 1% agarose gels and visualized by ethidium bromide staining. ER mRNA expression was demonstrated in reticulum, omasum, abomasum, duodenum, jejunum, ileum, caecum and colon. AR mRNA expression was not determined in the forestomaches, but was present in all intestinal segments investigated.(ABSTRACT TRUNCATED AT 250 WORDS)

Extracellular vesicle miRNAs drive aberrant macrophage responses in NSAID-exacerbated respiratory disease

BACKGROUND

Extracellular vesicles (EVs) have been implicated in the pathogenesis of asthma, however, how EVs contribute to immune dysfunction and type 2 airway inflammation remains incompletely understood. We aimed to elucidate roles of airway EVs and their miRNA cargo in the pathogenesis of NSAID-exacerbated respiratory disease (N-ERD), a severe type 2 inflammatory condition.

METHODS

EVs were isolated from induced sputum or supernatants of cultured nasal polyp or turbinate tissues of N-ERD patients or healthy controls by size-exclusion chromatography and characterized by particle tracking, electron microscopy and miRNA sequencing. Functional effects of EV miRNAs on gene expression and mediator release by human macrophages or normal human bronchial epithelial cells (NHBEs) were studied by RNA sequencing, LC-MS/MS and multiplex cytokine assays.

RESULTS

EVs were highly abundant in secretions from the upper and lower airways of N-ERD patients. N-ERD airway EVs displayed profoundly altered immunostimulatory capacities and miRNA profiles compared to airway EVs of healthy individuals. Airway EVs of N-ERD patients, but not of healthy individuals induced inflammatory cytokine (GM-CSF and IL-8) production by NHBEs. In macrophages, N-ERD airway EVs exhibited an impaired potential to induce cytokine and prostanoid production, while enhancing M2 macrophage activation. Let-7 family miRNAs were highly enriched in sputum EVs from N-ERD patients and mimicked suppressive effects of N-ERD EVs on macrophage activation.

CONCLUSION

Aberrant airway EV miRNA profiles may contribute to immune dysfunction and chronic type 2 inflammation in N-ERD. Let-7 family miRNAs represent targets for correcting aberrant macrophage activation and mediator responses in N-ERD.

Insulin-like growth factor-I gene cloning and protein expression in bovine trabecular meshwork tissue and cells

Whether cultured bovine trabecular meshwork cells and trabecular tissue ex vivo express insulin-like growth factor-I (IGF-I) messenger RNA (mRNA) and protein was investigated. Total RNA of cultured bovine trabecular meshwork cells as well as trabecular meshwork tissue freshly excised from bovine eyes was extracted, and reverse transcriptase-polymerase chain reaction (RT-PCR) was used to detect IGF-I mRNA. RT-PCR product was verified by sequencing. Immunohistochemical stain was used to detect IGF-I protein. The results showed that a single PCR amplified product was obtained, and the sequence was homologous to the known sequence.. IGF-I immunostain was positive in the cytoplasm of trabecular meshwork cells. It was concluded that trabecular meshwork cells produce IGF-I and contribute to the presence of IGF-I in trabecular meshwork microenvironment as well as aqueous humor. Trabecular meshwork cells were affected by IGF-I not only through paracrine, but also autocrine action. Whether abnormal down-regulations in IGF-I production may contribute to the pathogenesis of primary open-angle glaucoma and the possibility of promoting the autocrine action of IGF-I by trabecular meshwork cells to treat the disease is worth further investigation.