Inhibition of collagen synthesis by interleukin-1 in three-dimensional collagen lattice cultures of fibroblasts

Interleukin-1 (Il-1) was added to collagen lattice cultures of human skin fibroblasts. No cell division was induced, the ability of fibroblasts to contract the lattices was decreased and a dose-related inhibition of collagen synthesis without effect on non-collagen proteins was found. Indomethacin had no influence on these effects.     

The growth of human fibroblasts and A431 epidermoid carcinoma cells on gamma-irradiated human amnion collagen substrata

Summary Human fibroblasts and A431 human epidermoid carcinoma cells were cultured on gamma-irradiated human amnion collagen as well as on plastic dishes and non-irradiated collagen coated dishes. The morphology, attachment, growth and short-term cytotoxicity of these culture conditions have been determined. Both irradiated and non-irradiated amnion collagen enhanced the attachment and proliferation of fibroblasts as compared to the plastic dishes. No differences in these properties were observed for A431 cells cultured on irradiated collagen when compared with culture on non-irradiated collagen substrates. Cytotoxicity assays showed that irradiated and non-irradiated collagens were not cytotoxic for either fibroblasts or A431 cells. The results demonstrated that amnion collagen irradiated at doses of 0.25–2.0 Mrads is optimal for cell growth.     

ACTH response induced by interleukin-1 is mediated by CRF secretion stimulated by hypothalamic PGE

Summary We investigated whether hypothalamic prostaglandin E₂ (PGE₂) and corticotropin releasing factor (CRF) are responsible for the development of the adrenocorticotropic hormone (ACTH) response induced by interleukin-1 (IL-1). The present results show that ACTH responses induced by intravenous injection of IL-1 were suppressed by systemic pretreatment with indomethacin and that intrahypothalamic injection of PGE₂ stimulates the secretion of ACTH. Furthermore, systemic pretreatment with anti-CRF antibody significantly suppressed the ACTH response induced by intrahypothalamic injection of PGE₂. These data suggest that the ACTH response induced by IL-1 is mediated by CRF secretion stimulated by hypothalamic PGE₂.     

Reduced collagen biosynthesis in oral mucosa of beige (Chediak-Higashi) mice

Summary Oral mucosa of beige (Chediak-Higashi) mice had decreased levels of collagen synthesis and prolyl hydroxylase activity compared with normal animals. No significant difference was observed in non-collagen protein synthesis between the two groups. These results suggest that decreased collagen biosynthesis in oral tissues may be partially involved in the increased incidence of periodontal disease in the Chediak-Higashi syndrome.     

Effects of gamma irradiation on dermal equivalents in vitro

Summary Dermal equivalents (DE), collagen lattices, were produced in vitro and used as a model for studying the possible role of a pure population of fibroblasts in post-radiotherapeutic dermal fibrosis. Single doses of gamma irradiation induced a partial inhibition of the collagen lattice retraction and of protein synthesis. The collagen production was less inhibited than was synthesis of non-collagen protein, which resulted in an increase of the relative amount of collagen synthesized by irradiated fibroblasts. These data suggest that gamma irradiation might be able to select some fibroblast clones able to produce increasing amounts of collagen. This selection process could be involved in the development of tissue fibrosis after therapeutic radiation.     

Serum-induced stimulation of snRNA synthesis in mouse 3T3 fibroblasts

Summary Small nuclear RNAs (snRNAs) from quiescent and serum-stimulated 3T3 cultures, labeled with [³H]uridine ([³H]U), were electrophoresed in polyacrylamide-urea slab gels and revealed by staining with ethidium bromide and by fluorography, Judged by labeling with [³H]U, synthesis of 7S and U1-U6 RNAs was very low or absent in quiescent cultures. The serum-induced transition of 3T3 cells from a resting to a growing state was accompanied by an early, apparently sequential stimulation of snRNA synthesis; stimulated synthesis of 7S, U1, U2, U3, U4 and U6 RNAs coincided in time with serum-induced stimulation of 45S pre-ribosomal RNA (pre-rRNA) and heterogeneous nuclear RNA (hnRNA) synthesis.     

Inhibition of in vitro RNA synthesis by hycanthone,oxamniquine and praziquantel

Summary The schistosomicides, hycanthone, oxamniquine and praziquantel, were found to inhibit the in vitro RNA synthesis using isolated hamster liver nuclei. Preincubation of the nuclei with these drugs revealed that the inhibitory effect of oxamniquine was irreversible and progressed with time, whereas that of hycanthone and parziquantel was reversible. On the other hand, hycanthone and praziquantel have a high affinity for DNA but oxamniquine does not. The data indicate that the mechanism of inhibition by oxamniquine is different from that of hycanthone and praziquantel.     

Inhibition of virus multiplication and alteration of cyclic AMP level in cell cultures by flavonoids

Summary The inhibitory effect of four flavonoid compounds on virus multiplication and their influence on the intracellular cyclic AMP (cAMP) level were studied in cell cultures. Quercetin and quercitrin reduced the yields ofHuman (alpha) herpesvirus 1 (HSV-1) andSuid (alpha) herpesvirus 1 (pseudorabies virus), but hesperidin and rutin had no effect. Further, quercetin and quercitrin elevated the intracellular level of cAMP, whereas hesperidin and rutin did not alter the cAMP level. Both antiviral activity and cAMP-enhancing effect were dependent on the concentrations of the flavonoids, and these effects turned out to be parallel.This study suggests that a relation exists between the antiviral effect and the cAMP-enhancing activity of flavonoids.     

Differential regulation of collagen types I and III expression in cardiac fibroblasts by AGEs through TRB3/MAPK signaling pathway

Advanced glycation end products (AGEs) play an important role in collagen deposition in diabetic cardiomyopathy. TRB3, a mammalian homolog of Drosophila tribbles, functions to increase glucose intolerance and regulates cell proliferation. We demonstrated that AGEs induce collagen type I expression but inhibit collagen type III expression, accompanied by increased TRB3 expression. Furthermore, the collagen type I induced byAGEs was down-regulated after inhibition of ERK and p38-MAPK, the collagen type III reduced by AGEs was up-regulated after inhibition of ERK. The expression of collagen types I and III regulated by AGEs through MAPK was partly reversed after treatment with TRB3 siRNA. It suggests that the TRB3/MAPK signaling pathway participates in the regulation of collagen types I and III by AGEs and may provide new therapeutic strategies for diabetic cardiomyopathy. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. Received 08 May 2008; received after revision 25 June 2008; accepted 22 July 2008 M. Tang, M. Zhong: These two authors contributed equally to this work.     

Stabilisation of collagen by betel nut polyphenols as a mechanism in oral submucous fibrosis

Summary Treatment of reconstituted collagen fibrils and pieces of rat dermis with the crude extract, purified tannins or (+)-catechin from betel nut (Areca catechu) increases their resistance to both human and bacterial collagenases in a concentration-dependent manner. These tanning agents may stabilise collagen in vivo following damage to the oral epithelium and promote the sub-epithelial fibrosis which occurs in betel nut chewers.     

Effects of isaxonine phosphate and analogs on fibroblast metabolism in culture

Summary Human skin fibroblasts in confluent cultures were incubated for 24 h in the presence of isaxonine phosphate (Nerfactor) and several related factors. The incorporation of¹⁴C-proline into secreted proteins and the release of collagen into the medium were inhibited. When the cells incubated for an additional period of 24 h after thorough washing, protein and collagen syntheses were found to be identical to those of controls, demonstrating that the inhibition of protein synthesis was independent of any toxic effect. When cells were incubated in the presence of both isaxonine and colchicine, the secretion of collagen was more inhibited than by colchicine alone, and proteins accumulated in the cells.     

Interleukin 1 modulates collagen accumulation by rat granulation tissue cells both in vivo and in vitro

Summary In in vivo studies 0.5 U human interleukin 1 (IL-1) was incoculated daily into a subcutaneously implanted viscose cellulose sponge. IL-1 significantly decreased the dry weight (7.8%) and the hydroxyproline content (24.2%) of granulomas. When the cultured rat granulation tissue cells were exposed to IL-1 (0.5–2.0 U/ml) their collagen production decreased to 80% of that in controls. No effect on cell proliferation was detected.     

ERKs are the point of divergence of PKA and PKC activation by PTHrP in human skin fibroblasts

Parathyroid hormone-related peptide (PTHrP) receptors, coupled to trimeric G proteins, operate in most target cells through at least three different transduction routes: Gαs-mediated stimulation of adenylylcyclase (AC), Gαq-mediated activation of phospholipase Cβ (PLC) and mitogen-activated protein kinase (MAPK) activation. In this study we investigated the relative role of different pathways in human skin fibroblast prolifera-tion. Using chemical inhibitors and activators of signal transduction, we demonstrated that: (i) AC/cAMP and PLC/1,4,5 inositol triphosphate/diacylglycerol second-messenger systems are simultaneously activated following PTHrP binding to its receptors; (ii) the mitogenic response to PTHrP derives from a balance between two counteracting pathways – an activating route mediated by protein kinase C (PKC) and an inhibitory route mediated by protein kinase A (PKA); (iii) PTHrP mitogenic effects are largely dependent on MAPKs, whose activity can be modulate d by both PKA and PKC. Our results indicate that MAPKs are common targets of both transduction routes and, at the same time, their point of divergence in mediating PTHrP dual and opposite mitogenic effects. Received 2 August 2002; received after revision 10 September 2002; accepted 18 October 2002 RID="*" ID="*"Corresponding author.     

刚地弓形虫培养上清抑制THP-1细胞增殖及诱导凋亡的研究

摘要：目的提取弓形虫体外细胞共培养上清,并研究上清对人急性单核细胞白血病细胞THP-1增殖及凋亡的影响。方法收集对数生长期的THP-1细胞以5X10^7／ml细胞浓度接种于不同培养瓶中,对照组加入含10％胎牛血清的RPMll640,实验组加入相同体积不同数量（2×10^7／ml、4X10^7／ml、8×10^7／m1）弓形虫速殖子培养上清,采用四甲基氮噻唑蓝（MTY）法检测吸光度（A490值）并计算THP-1细胞增殖抑制率;倒置显微镜下观察细胞形态变化;Annexin-V-FITC／PI染色细胞后上流式细胞仪检测各个时间点细胞凋亡率变化,以Western印迹方法分析凋亡相关蛋白Bax、Bcl-2的表达或活性。结果MTY法检测结果弓形虫培养上清呈时间剂量依赖性抑制THP-1细胞株增殖,倒置显微镜下观察处理组细胞有发泡现象和凋亡小体出现。流式细胞仪检测弓形虫感染后的THP-1细胞凋亡率较对照组有升高趋势（P〈0．05）,呈量效依赖性,Westernblot检测刚地弓形虫培养上清作用于THP-l细胞48h后实验组的Bax、Bcl-2蛋白表达较对照组的比值分别有明显的升高与降低（P〈0．05）。结论刚地弓形虫速殖子培养上清对体外培养THP-l细胞增殖有明显的抑制作用,并可诱导THP-1细胞凋亡。     

Inhibition of cholesterol synthesis ex vivo and in vivo by fluvastatin,a new inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A reductase

The inhibitory effect of fluvastatin sodium (fluvastatin), a new type of 3-hydroxy-3-methylglutaryl (HMG) coenzyme A inhibitor, on de novo cholesterol synthesis was investigated and compared with that of pravastatin. Fluvastatin at a concentration of 12.5 mg/kg inhibited sterol synthesis ex vivo from [¹⁴C]acetate in rat liver and ileum by 97–99% with respect to the control, while the inhibition in kidney was 55%. The inhibition by fluvastatin in the liver and ileum persisted for approximately 9 h after administration. Significant differences between fluvastatin also had an inhibitory effect on cholesterol synthesis in vivo in various tissues of rats given [¹⁴C]acetate intraperitoneally. Sterol synthesis in the liver, ileum and kidney was inhibited by over 95% 3 h after administration of 6.25 mg/kg of fluvastatin. Significant differences between fluvastatin and pravastatin were found in the liver and ileum. Fluvastatin was more potent than pravastatin in inhibiting both ex vivo and in vivo sterol synthesis in the ileum (but not in kidney) and liver.     

Inhibition of TSH-stimulated thyroid hormone release and potentiation of TRH-stimulated TSH release by indomethacin in perifusion systems of rat thyroids and pituitaries

Summary Using indomethacin (Ind), a prostaglandin, synthesis inhibitor, in vivo experiments in rats and in vitro experiments with perifusion systems of rat thyroids and pituitaries were conducted. After 35 days of intragastric infusion of Ind, serum TSH levels were markedly increased, the thyroid was swollen and, as a consequence, T₃ and T₄ levels were normal. The T₃ release from perifused rat thyroids under continuous stimulation with 10 mU/ml TSH was inhibited significantly (p<0.01) by 1.0×10^–6 M Ind. On the other hand, the TSH release from perifused rat pituitaries under TRH stimulation was enhanced conspicuously by Ind. It was concluded that Ind decelerated thyroid hormone release from the thyroid and accelerated TSH release from the pituitary in perifusion systems.     

Stimulation of histamine synthesis in rat mast cells by compound 48/80 in vitro

Summary The histamine content of rat peritoneal fluid cells is doubled within 20 min by 0.5 g/ml of compound 48/80. Histamine catabolism inhibitors do not reproduce this effect; cells pre-incubated with -fluoromethylhistidine are unresponsive to compound 48/80 which therefore activates pre-formed histidine decarboxylase rather than inducing it. Non-mast cells showed no change after treatment with compound 48/80.