Glucocorticoids decrease the bioavailability of TGF-beta which leads to a reduced TGF-beta signaling in hepatic stellate cells

A Comparative Genome-Wide Transcriptome Analysis of Glucocorticoid Responder and Non-Responder Primary Human Trabecular Meshwork Cells

Aim: To investigate genes and pathways involved in differential glucocorticoid (GC) responsiveness in human trabecular meshwork (HTM) cells using RNA sequencing. Methods: Using paired human donor eyes, human organ-cultured anterior segment (HOCAS) was established in one eye to characterize GC responsiveness based on intra ocular pressure (IOP) change and, in the other eye, primary HTM cell culture was established. For RNA sequencing, total RNA extracted from GC-responder (GC-R) and non-responder (GC-NR) cells after dexamethasone (DEX) or ethanol (ETH) treatment for 7d was used. Differentially expressed genes (DEGs) were compared among five groups and validated. Results: In total, 616 and 216 genes were identified as significantly dysregulated in Group #1 and #2 (#1: ETH vs. DEX-treated GC-R; #2: ETH vs. DEX-treated GC-NR), respectively. Around 80 genes were commonly dysregulated in Group #3 (overlapping DEGs between #1 and #2), whereas 536 and 136 genes were uniquely expressed in GC-R (#4) and GC-NR HTM (#5) cells, respectively. Pathway analysis revealed that WNT signaling, drug metabolism cytochrome p450, cell adhesion, TGF-β signaling, and MAPK signaling were associated with GC responsiveness. Conclusion: This is the first study reporting distinct gene signatures and their associated pathways for GC-R and GC-NR HTM cells. WNT and MAPK signaling are potential therapeutic targets for the management of GC-induced glaucoma.

Molecular Mechanisms and Potential New Therapeutic Drugs for Liver Fibrosis

Liver fibrosis is the pathological process of excessive extracellular matrix deposition after liver injury and is a precursor to cirrhosis, hepatocellular carcinoma (HCC). It is essentially a wound healing response to liver tissue damage. Numerous studies have shown that hepatic stellate cells play a critical role in this process, with various cells, cytokines, and signaling pathways engaged. Currently, the treatment targeting etiology is considered the most effective measure to prevent and treat liver fibrosis, but reversal fibrosis by elimination of the causative agent often occurs too slowly or too rarely to avoid life-threatening complications, especially in advanced fibrosis. Liver transplantation is the only treatment option in the end-stage, leaving us with an urgent need for new therapies. An in-depth understanding of the mechanisms of liver fibrosis could identify new targets for the treatment. Most of the drugs targeting critical cells and cytokines in the pathogenesis of liver fibrosis are still in pre-clinical trials and there are hardly any definitive anti-fibrotic chemical or biological drugs available for clinical use. In this review, we will summarize the pathogenesis of liver fibrosis, focusing on the role of key cells, associated mechanisms, and signaling pathways, and summarize various therapeutic measures or drugs that have been trialed in clinical practice or are in the research stage.

Nuclear Receptors in Liver Fibrosis

Nuclear receptors are ligand-activated transcription factors that regulate gene expression of a variety of key molecular signals involved in liver fibrosis. The primary cellular driver of liver fibrogenesis are activated hepatic stellate cells. Different NRs regulate the hepatic expression of pro-inflammatory and pro-fibrogenic cytokines that promote the transformation of hepatic stellate cells into fibrogenic myofibroblasts. Importantly, nuclear receptors regulate gene expression circuits that promote hepatic fibrogenesis and/or allow liver fibrosis regression. In this review, we highlight the direct and indirect influence of nuclear receptors on liver fibrosis, with a focus on hepatic stellate cells, and discuss potential therapeutic effects of nuclear receptor modulation in regard to anti-fibrotic and anti-inflammatory effects. Further research on nuclear receptors-related signaling may lead to the clinical development of effective anti-fibrotic therapies for patients with liver disease.

AP Collagen Peptides Prevent Cortisol-Induced Decrease of Collagen Type I in Human Dermal Fibroblasts

Cortisol is an endogenous glucocorticoid (GC) and primary stress hormone that regulates a wide range of stress responses in humans. The adverse effects of cortisol on the skin have been extensively documented but the underlying mechanism of cortisol-induced signaling is still unclear. In the present study, we investigate the effect of cortisol on collagen type I expression and the effect of AP collagen peptides, collagen tripeptide-rich hydrolysates containing 3% glycine-proline- hydroxyproline (Gly-Pro-Hyp, GPH) from the fish skin, on the cortisol-mediated inhibition of collagen type I and the cortisol-induced signaling that regulates collagen type I production in human dermal fibroblasts (HDFs). We determine that cortisol downregulates the expression of collagen type I. AP collagen peptides or GC receptor (GR) inhibitors recover the cortisol-mediated inhibition of collagen type I and GR activation. AP collagen peptides or GR inhibitors also prevent the cortisol-dependent inhibition of transforming growth factor (TGF)-β signaling. AP collagen peptides or GR inhibitors are effective in the prevention of collagen type I inhibition mediated by cortisol in senescent HDFs and reconstituted human skin models. Taken together, GR signaling might be responsible for the cortisol-mediated inhibition of TGF-β. AP collagen peptides act as GR-mediated signaling blockers, preventing the cortisol-dependent inhibition of collagen type I. Therefore, AP collagen peptides have the potential to improve skin health.

Effects of dexamethasone on hepatic macrophages in normal livers and thioacetamide-induced acute liver lesions in rats

Resident and infiltrative macrophages play important roles in the development of pathological lesions. M1/M2 macrophage polarization with respective CD68 and CD163 expression remains unclear in chemically induced liver injury. This study was aimed at investigating the influence of macrophages on normal and chemically induced liver injury. For this, dexamethasone (DX), an immunosuppressive drug, was administered in normal rats and thioacetamide (TAA)-treated rats. Liver samples were collected and analyzed with immunohistochemical methods. Repeated injections of DX (0.5 or 1.0 mg/kg BW) for 3, 7 and 11 days reduced the number of CD163 positive hepatic resident macrophages (Kupffer cells) in normal livers, while increasing AST and ALT levels. In TAA (300 mg/kg BW)-treated rats injected with DX (0.5 mg/kg BW) pretreatment, the number of M1 and M2 macrophages showed a significant decrease compared with that of TAA-treated rats without DX treatment. Additionally, reparative fibrosis resulting from hepatocyte injury induced by TAA injection was suppressed by DX pretreatment. Our data suggested that macrophages could influence not only normal hepatic homeostasis (reflected by AST and ALT levels) but also chemically induced hepatic lesion development (reduced reparative fibrosis).

Corticosteroid inhibits differentiation of palmar fibromatosis-derived stem cells (FSCs) through downregulation of transforming growth factor-β1 (TGF-β1)

Treatment for musculoskeletal fibromatosis remains challenging. Surgical excision for fibromatosis is the standard therapy but recurrence remains high. Corticosteroids, an anti-fibrogenic compound, have been used to treat early stage palmar fibromatosis, but the mechanism is unknown. We investigated the inhibitory mechanism effect of corticosteroids in the murine model of fibromatosis nodule as well as in cultured FSCs. Quantitative reverse transcription/polymerase chain reaction (PCR) analysis and immunofluorescence (IF) staining for markers of myofibroblasts (α-smooth muscle actin and type III collagen) were used to examine the effect of dexamethasone on myofibroblasic differentiation of FSCs both in vitro and in vivo. Transforming growth factor-β1 (TGF-β1) signaling and its downstream targets were examined using western blot analysis. TGF-β1 expression in FSCs before and after dexamethasone treatment was compared. In addition, inhibition of TGF-β1 expression was examined using RNA interference (RNAi) on FSCs, both in vitro and in vivo. Treating FSCs with dexamethasone inhibited FSCs’ myofibroblastic differentiation in vitro. Treating FSCs with dexamethasone before or after implantation further inhibited formation of fibromatosis nodules. Dexamethasone suppressed expression of TGF-β1 and pSmad2/3 by FSCs in vitro. TGF-β1 knockdown FSCs showed reducing myofibroblastic differentiation both in vitro and in vivo. Finally, addition of TGF-β1 abolished dexamethasone-mediated inhibition of myofibroblastic differentiation. Dexamethasone inhibits the myofibroblastic differentiated potential of FSCs both in vitro and in vivo through inhibition of TGF-β1 expression in FSCs. TGF-β1 plays a key role in myofibroblastic differentiation.

Transforming growth factor β2 (TGFβ2) signaling plays a key role in glucocorticoid-induced ocular hypertension

Elevation of intraocular pressure (IOP) is a serious adverse effect of glucocorticoid (GC) therapy. Increased extracellular matrix (ECM) accumulation and endoplasmic reticulum (ER) stress in the trabecular meshwork (TM) is associated with GC-induced IOP elevation. However, the molecular mechanisms by which GCs induce ECM accumulation and ER stress in the TM have not been determined. Here, we show that a potent GC, dexamethasone (Dex), activates transforming growth factor β (TGFβ) signaling, leading to GC-induced ECM accumulation, ER stress, and IOP elevation. Dex increased both the precursor and bioactive forms of TGFβ2 in conditioned medium and activated TGFβ-induced SMAD signaling in primary human TM cells. Dex also activated TGFβ2 in the aqueous humor and TM of a mouse model of Dex-induced ocular hypertension. We further show that Smad3^-/- mice are protected from Dex-induced ocular hypertension, ER stress, and ECM accumulation. Moreover, treating WT mice with a selective TGFβ receptor kinase I inhibitor, LY364947, significantly decreased Dex-induced ocular hypertension. Of note, knockdown of the ER stress-induced activating transcription factor 4 (ATF4), or C/EBP homologous protein (CHOP), completely prevented Dex-induced TGFβ2 activation and ECM accumulation in TM cells. These observations suggested that chronic ER stress promotes Dex-induced ocular hypertension via TGFβ signaling. Our results indicate that TGFβ2 signaling plays a central role in GC-induced ocular hypertension and provides therapeutic targets for GC-induced ocular hypertension.

11Beta-hydroxysteroid dehydrogenase-1 deficiency or inhibition enhances hepatic myofibroblast activation in murine liver fibrosis

A hallmark of chronic liver injury is fibrosis, with accumulation of extracellular matrix orchestrated by activated hepatic stellate cells (HSCs). Glucocorticoids limit HSC activation in vitro, and tissue glucocorticoid levels are amplified by 11beta-hydroxysteroid dehydrogenase-1 (11βHSD1). Although 11βHSD1 inhibitors have been developed for type 2 diabetes mellitus and improve diet-induced fatty liver in various mouse models, effects on the progression and/or resolution of liver injury and consequent fibrosis have not been characterized. We have used the reversible carbon tetrachloride-induced model of hepatocyte injury and liver fibrosis to show that in two models of genetic 11βHSD1 deficiency (global, Hsd11b1-/- , and hepatic myofibroblast-specific, Hsd11b1fl/fl /Pdgfrb-cre) 11βHSD1 pharmacological inhibition in vivo exacerbates hepatic myofibroblast activation and liver fibrosis. In contrast, liver injury and fibrosis in hepatocyte-specific Hsd11b1fl/fl /albumin-cre mice did not differ from that of controls, ruling out 11βHSD1 deficiency in hepatocytes as the cause of the increased fibrosis. In primary HSC culture, glucocorticoids inhibited expression of the key profibrotic genes Acta2 and Col1α1, an effect attenuated by the 11βHSD1 inhibitor [4-(2-chlorophenyl-4-fluoro-1-piperidinyl][5-(1H-pyrazol-4-yl)-3-thienyl]-methanone. HSCs from Hsd11b1-/- and Hsd11b1fl/fl /Pdgfrb-cre mice expressed higher levels of Acta2 and Col1α1 and were correspondingly more potently activated. In vivo [4-(2-chlorophenyl-4-fluoro-1-piperidinyl][5-(1H-pyrazol-4-yl)-3-thienyl]-methanone administration prior to chemical injury recapitulated findings in Hsd11b1-/- mice, including greater fibrosis.

CONCLUSION

11βHSD1 deficiency enhances myofibroblast activation and promotes initial fibrosis following chemical liver injury; hence, the effects of 11βHSD1 inhibitors on liver injury and repair are likely to be context-dependent and deserve careful scrutiny as these compounds are developed for chronic diseases including metabolic syndrome and dementia. (Hepatology 2018;67:2167-2181).

Application of Monte Carlo cross-validation to identify pathway cross-talk in neonatal sepsis

To explore genetic pathway cross-talk in neonates with sepsis, an integrated approach was used in this paper. To explore the potential relationships between differently expressed genes between normal uninfected neonates and neonates with sepsis and pathways, genetic profiling and biologic signaling pathway were first integrated. For different pathways, the score was obtained based upon the genetic expression by quantitatively analyzing the pathway cross-talk. The paired pathways with high cross-talk were identified by random forest classification. The purpose of the work was to find the best pairs of pathways able to discriminate sepsis samples versus normal samples. The results found 10 pairs of pathways, which were probably able to discriminate neonates with sepsis versus normal uninfected neonates. Among them, the best two paired pathways were identified according to analysis of extensive literature. Impact statement To find the best pairs of pathways able to discriminate sepsis samples versus normal samples, an RF classifier, the DS obtained by DEGs of paired pathways significantly associated, and Monte Carlo cross-validation were applied in this paper. Ten pairs of pathways were probably able to discriminate neonates with sepsis versus normal uninfected neonates. Among them, the best two paired pathways ((7) IL-6 Signaling and Phospholipase C Signaling (PLC); (8) Glucocorticoid Receptor (GR) Signaling and Dendritic Cell Maturation) were identified according to analysis of extensive literature.

Dexamethasone induced apoptosis of A549 cells via the TGF-β1/Smad2 pathway

Lung cancers are the most commonly diagnosed malignant tumors, and are one of the leading causes of morbidity and mortality worldwide. Dexamethasone (DEX) serves an important function in the regulation of lung cancer cell proliferation; however, the mechanisms involved still remain unknown. In the present study, the effects of DEX on A549 cell proliferation and apoptosis were examined, in addition to the potential downstream regulatory mechanisms underlying these effects. A549 cells were treated with different concentrations of DEX at 12, 24 and 48 h time points, followed by the addition of SB431542, an inhibitor of the TGF-β1 receptor, to block the TGF-β1 signaling pathway. Cell proliferation was analyzed using a 3-(4,5-diethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium, inner salt. The apoptosis rate was measured by Hoechst 33342 and Annexin V/propidium iodide staining and the expression of transforming growth factor (TGF)-β1, Smad family member 2 (Smad2) and caspase-3 were assessed by western blot. The results from the present study demonstrated that the proliferation of A549 cells decreased and the apoptosis rate significantly increased following DEX treatment (P<0.05). Furthermore, the expression of TGF-β1, Smad2 and caspase-3 were significantly increased following DEX stimulation (P<0.05), the effects of which were abrogated by the addition of the TGF-β1 receptor inhibitor, SB431542 (P<0.05). DEX-induced apoptosis in A549 cells, and this effect was abrogated by SB431542, an inhibitor of TGF-β1 receptor signaling, which indicated that the TGF-β1/Smad2 pathway may be associated with this process and SB431542 may function as an antitumor drug in the future.

Glucocorticoids Improve Myogenic Differentiation In Vitro by Suppressing the Synthesis of Versican, a Transitional Matrix Protein Overexpressed in Dystrophic Skeletal Muscles

In Duchenne muscular dystrophy (DMD), a dysregulated extracellular matrix (ECM) directly exacerbates pathology. Glucocorticoids are beneficial therapeutics in DMD, and have pleiotropic effects on the composition and processing of ECM proteins in other biological contexts. The synthesis and remodelling of a transitional versican-rich matrix is necessary for myogenesis; whether glucocorticoids modulate this transitional matrix is not known. Here, versican expression and processing were examined in hindlimb and diaphragm muscles from mdx dystrophin-deficient mice and C57BL/10 wild type mice. V0/V1 versican (Vcan) mRNA transcripts and protein levels were upregulated in dystrophic compared to wild type muscles, especially in the more severely affected mdx diaphragm. Processed versican (versikine) was detected in wild type and dystrophic muscles, and immunoreactivity was highly associated with newly regenerated myofibres. Glucocorticoids enhanced C2C12 myoblast fusion by modulating the expression of genes regulating transitional matrix synthesis and processing. Specifically, Tgfβ1, Vcan and hyaluronan synthase-2 (Has2) mRNA transcripts were decreased by 50% and Adamts1 mRNA transcripts were increased three-fold by glucocorticoid treatment. The addition of exogenous versican impaired myoblast fusion, whilst glucocorticoids alleviated this inhibition in fusion. In dystrophic mdx muscles, versican upregulation correlated with pathology. We propose that versican is a novel and relevant target gene in DMD, given its suppression by glucocorticoids and that in excess it impairs myoblast fusion, a process key for muscle regeneration.

Influence of the Polymorphism C-509T in the TGFB1 Gene Promoter on the Response to Montelukast

Transforming growth factor beta 1 (TGFB1) is a multifunctional cytokine with a key role in asthma airway inflammation and remodeling. Since elevated levels of this cytokine in airways might be associated with response to asthma therapy, the aim of this study was to investigate whether the presence of the polymorphism C-509T in the promoter of the TGFB1 gene is associated with response to montelukast. A group of 102 asthmatic patients was genotyped for the presence of the C-509T polymorphism by DNA sequencing and subjected to induced sputum sampling. Cells from sputum samples and BEAS 2B cells were treated with montelukast and endogenous TGFB1 expression was measured by quantitative real-time polymerase chain reaction. The promoter activity was analyzed by luciferase assays in BEAS 2B cells transfected with constructs carrying variants -509C and -509T of the TGFB1 gene promoter. After treatment with montelukast, the decrease in TGFB1 gene expression was greater for the -509TT genotype (58.9%) than for the -509CC and -509CT genotypes (49.6% and 31.8%, respectively) (P = 0.071). In BEAS 2B cells, expression of endogenous TGFB1 was reduced by about 27% after montelukast treatment, while luciferase activity of both promoter variants was increased after montelukast treatment (-509C allele: 48.3%, P = 0.060; and -509T allele: 100.5%, P = 0.062). A more intensive response was registered in the promoter containing the -509T allele, which had 135% higher activity than the -509C variant (P = 0.035). This study showed that the presence of the -509T allele in the TGFB1 promoter might modulate effects of montelukast on TGFB1 gene expression, but future studies are necessary, taking into consideration other genetic and nongenetic factors. It is of potential importance for clinical management of asthma to clarify the influence of the C-509T polymorphism on the response to treatment with montelukast.

Effects of Acute Confinement Stress-induced Hypothalamic-Pituitary Adrenal Axis Activation and Concomitant Peripheral and Central Transforming Growth Factor-β1 Measures in Nonhuman Primates

Transforming growth factor-β1 (TGF-β1) is a multifunctional cytokine with anti-inflammatory, immunosuppressive, and neuroprotective properties. The hypothalamic-pituitary-adrenal axis and immune system exert bidirectional influences on each other, via cortisol and TGF-β1, but the exact nature of the interaction is not well characterized. The current study examined the effects, in bonnet macaques (Macaca radiata), of two consecutive acute confinement stress periods in an unfamiliar room while mildly restrained, first without and then with dexamethasone pretreatment (0.01 mg/kg intramuscular). Preceding the confinement studies, a non-stress control condition obtained contemporaneous levels of cortisol and TGF-β1 in both plasma and cerebrospinal fluid to match the confinement stress studies. Subjects were reared under either normative or variable foraging demand conditions. Since there were no rearing effects at baseline or for any of the conditions tested—either for cortisol or TGF-β—the study analyses were conducted on the combined rearing groups. The stress condition increased both plasma and cerebrospinal fluid cortisol levels whereas dexamethasone pretreatment decreased cortisol concentrations to below baseline levels despite stress. The stress condition decreased TGF-β1 concentrations only in cerebrospinal fluid but not in serum. Together, the data suggested that stress-induced reductions of a centrally active neuroprotective cytokine occur in the face of hypothalamic-pituitary-adrenal axis activation, potentially facilitating glucocortoid-induced neurotoxicity. Stress-induced reductions of neuroprotective cytokines prompt exploration of protective measures against glucocorticoid-induced neurotoxicity.

Decoding the role of the nuclear receptor SHP in regulating hepatic stellate cells and liver fibrogenesis

The small heterodimer partner (SHP) is an orphan nuclear receptor that lacks the DNA binding domain while conserves a putative ligand-binding site, thought that endogenous ligands for this receptor are unknown. Previous studies have determined that SHP activation protects against development of liver fibrosis a process driven by trans-differentiation and activation of hepatic stellate cells (HSCs), a miofibroblast like cell type, involved in extracellular matrix (ECM) deposition. To dissect signals involved in this activity we generated SHP-overexpressing human and rat HSCs. Forced expression of SHP in HSC-T6 altered the expression of 574 genes. By pathway and functional enrichment analyses we detected a cluster of 46 differentially expressed genes involved in HSCs trans-differentiation. Using a isoxazole scaffold we designed and synthesized a series of SHP agonists. The most potent member of this group, ISO-COOH (EC₅₀: 9 μM), attenuated HSCs trans-differentiation and ECM deposition in vitro, while in mice rendered cirrhotic by carbon tetrachloride (CCl₄) or α-naphthyl-isothiocyanate (ANIT), protected against development of liver fibrosis as measured by morphometric analysis and expression of α-SMA and α1-collagen mRNAs. In aggregate, present results identify SHP as a counter-regulatory signal for HSCs transactivation and describe a novel class of SHP agonists endowed with anti-fibrotic activity.

Computational Model of Secondary Palate Fusion and Disruption

Morphogenetic events are driven by cell-generated physical forces and complex cellular dynamics. To improve our capacity to predict developmental effects from chemical-induced cellular alterations, we built a multicellular agent-based model in CompuCell3D that recapitulates the cellular networks and collective cell behavior underlying growth and fusion of the mammalian secondary palate. The model incorporated multiple signaling pathways (TGFβ, BMP, FGF, EGF, and SHH) in a biological framework to recapitulate morphogenetic events from palatal outgrowth through midline fusion. It effectively simulated higher-level phenotypes (e.g., midline contact, medial edge seam (MES) breakdown, mesenchymal confluence, and fusion defects) in response to genetic or environmental perturbations. Perturbation analysis of various control features revealed model functionality with respect to cell signaling systems and feedback loops for growth and fusion, diverse individual cell behaviors and collective cellular behavior leading to physical contact and midline fusion, and quantitative analysis of the TGF/EGF switch that controls MES breakdown-a key event in morphogenetic fusion. The virtual palate model was then executed with theoretical chemical perturbation scenarios to simulate switch behavior leading to a disruption of fusion following chronic (e.g., dioxin) and acute (e.g., retinoic acid) chemical exposures. This computer model adds to similar systems models toward an integrative "virtual embryo" for simulation and quantitative prediction of adverse developmental outcomes following genetic perturbation and/or environmental disruption.

Targeting Hepatic Fibrosis in Autoimmune Hepatitis

Hepatic fibrosis develops or progresses in 25 % of patients with autoimmune hepatitis despite corticosteroid therapy. Current management regimens lack reliable noninvasive methods to assess changes in hepatic fibrosis and interventions that disrupt fibrotic pathways. The goals of this review are to indicate promising noninvasive methods to monitor hepatic fibrosis in autoimmune hepatitis and identify anti-fibrotic interventions that warrant evaluation. Laboratory methods can differentiate cirrhosis from non-cirrhosis, but their accuracy in distinguishing changes in histological stage is uncertain. Radiological methods include transient elastography, acoustic radiation force impulse imaging, and magnetic resonance elastography. Methods based on ultrasonography are comparable in detecting advanced fibrosis and cirrhosis, but their performances may be compromised by hepatic inflammation and obesity. Magnetic resonance elastography has excellent performance parameters for all histological stages in diverse liver diseases, is uninfluenced by inflammatory activity or body habitus, has been superior to other radiological methods in nonalcoholic fatty liver disease, and may emerge as the preferred instrument to evaluate fibrosis in autoimmune hepatitis. Promising anti-fibrotic interventions are site- and organelle-specific agents, especially inhibitors of nicotinamide adenine dinucleotide phosphate oxidases, transforming growth factor beta, inducible nitric oxide synthase, lysyl oxidases, and C-C chemokine receptors types 2 and 5. Autoimmune hepatitis has a pro-fibrotic propensity, and noninvasive radiological methods, especially magnetic resonance elastography, and site- and organelle-specific interventions, especially selective antioxidants and inhibitors of collagen cross-linkage, may emerge to strengthen current management strategies.

Glucocorticoids Have Opposing Effects on Liver Fibrosis in Hepatic Stellate and Immune Cells

Liver fibrosis is a reversible wound-healing process that is protective in the short term, but prolonged fibrotic responses lead to excessive accumulation of extracellular matrix components that suppresses hepatocyte regeneration, resulting in permanent liver damage. Upon liver damage, nonparenchymal cells including immune cells and hepatic stellate cells (HSCs) have crucial roles in the progression and regression of liver fibrosis. Here, we report differential roles of the glucocorticoid receptor (GR), acting in immune cells and HSCs, in liver fibrosis. In the carbon tetrachloride hepatotoxin-induced fibrosis model, both steroidal and nonsteroidal GR ligands suppressed expression of fibrotic genes and decreased extracellular matrix deposition but also inhibited immune cell infiltration and exacerbated liver injury. These counteracting effects of GR ligands were dissociated in mice with conditional GR knockout in immune cells (GR(LysM)) or HSC (GR(hGFAP)): the impacts of dexamethasone on immune cell infiltration and liver injury were totally blunted in GR(LysM) mice, whereas the suppression of fibrotic gene expression was diminished in GR(hGFAP) mice. The effect of GR activation in HSC was further confirmed in the LX-2 HSC cell line, in which antifibrotic effects were mediated by GR ligand inhibition of Sma and mad-related protein 3 (SMAD3) expression. We conclude that GR has differential roles in immune cells and HSCs to modulate liver injury and liver fibrosis. Specific activation of HSC-GR without alteration of GR activity in immune cells provides a potential therapeutic approach to treatment of hepatic fibrosis.

Prevention of trauma-induced cochlear fibrosis using intracochlear application of anti-inflammatory and antiproliferative drugs

Cochlear fibrosis is a common finding following cochlear implantation. Evidence suggests that cochlear fibrosis could be triggered by inflammation and epithelial-to-mesenchymal cell transition (EMT). In this study, we investigate the mechanisms of cochlear fibrosis and the risk/benefit ratio of local administration of the anti-inflammatory drug dexamethasone (DEX) and antimitotic drug aracytine (Ara-C). Cochlear fibrosis was evaluated in cochlear fibrosis models of rat cochlear slices in vitro and in KLH-induced immune labyrinthitis and platinum wire cochlear implantation-induced fibrosis in vivo. Cochleae were invaded with tissue containing fibroblastic cells expressing α-SMA (alpha smooth muscle actin), which along with collagen I, fibronectin, and laminin in the extracellular matrix, suggests the involvement of a fibrotic process triggered by EMT in vitro and in vivo. After perilymphatic injection of an adenoviral vector expressing GFP in vivo, we demonstrated that the fibroblastic cells derived from the mesothelial cells of the scalae tympani and vestibuli. Activation of inflammatory and EMT pathways was further assessed by ELISA analysis of the expression of IL-1β and TGF-β1. Both markers were elevated in vitro and in vivo, and DEX and Ara-C were able to reduce IL-1β and TGF-β1 production. After 5days of culture in vitro, quantification of calcein-positive cells revealed that Ara-C was 30-fold more efficient in preventing fibrosis, and provoked less sensory hair cell loss, than DEX. In KLH-induced immune labyrinthitis and platinum wire-implanted models, Ara-C was more efficient in preventing proliferation of fibrosis with less side effects on hair cells and neurons than DEX. In conclusion, DEX and Ara-C both prevent fibrosis in the cochlea. Analysis of the risk/benefit ratio favors the use of Ara-C for preventing cochlear fibrosis.

Hepatic inflammation and progressive liver fibrosis in chronic liver disease

Chronic liver inflammation drives hepatic fibrosis, and current immunosuppressive, anti-inflammatory, and anti-viral therapies can weaken this driver. Hepatic fibrosis is reversed, stabilized, or prevented in 57%-79% of patients by conventional treatment regimens, mainly by their anti-inflammatory actions. Responses, however, are commonly incomplete and inconsistently achieved. The fibrotic mechanisms associated with liver inflammation have been clarified, and anti-fibrotic agents promise to improve outcomes as adjunctive therapies. Hepatitis C virus and immune-mediated responses can activate hepatic stellate cells by increasing oxidative stress within hepatocytes. Angiotensin can be synthesized by activated hepatic stellate cells and promote the production of reactive oxygen species. Anti-oxidants (N-acetylcysteine, S-adenosyl-L-methionine, and vitamin E) and angiotensin inhibitors (losartin) have had anti-fibrotic actions in preliminary human studies, and they may emerge as supplemental therapies. Anti-fibrotic agents presage a new era of supplemental treatment for chronic liver disease.

A retrospective study of oral prednisolone treatment in canine chronic hepatitis

BACKGROUND

Only one study reports prednisone to prolong survival in dogs with chronic hepatitis irrespective of the causative agent. The aim of this retrospective study was to investigate the effects of prednisolone treatment on survival, clinicopathological variables, and histological grade and stage of idiopathic chronic hepatitis in 36 dogs.

ANIMALS AND METHODS

Medical records were reviewed of 36 prednisolone-treated dogs (median age: 8.6 years; range: 2.0-14.6 years) with chronic hepatitis not associated with primary copper accumulation. Clinicopathological results were analyzed pair-wise for 20 dogs, before and after oral prednisolone administration (1 mg/kg BW/day). Dogs were treated for at least 6 weeks, and for an additional 6 weeks if hepatitis was still present at rebiopsy. Follow-up data pertaining to clinical outcome and survival time (Kaplan-Meier estimate procedure) were analyzed.

RESULTS

At the follow-up, 11 dogs were in complete remission, 8 dogs had recurrent clinical signs, and 17 dogs had residual disease. Despite treatment, 20 dogs died of hepatitis-related causes. Dogs without cirrhosis survived significantly longer than dogs with cirrhosis. Prednisolone treatment normalized coagulopathies associated with chronic idiopathic hepatitis within one week in all 10 dogs that had coagulopathies at initial diagnosis.

CONCLUSIONS

Our findings suggest that prednisolone has, in part, beneficial effects on hepatic inflammation and that it may, at least in some cases, limit the progression of fibrosis, which emphasizes the importance of early diagnosis and treatment. We did not see any benefit of prednisolone treatment for dogs with cirrhosis. We could document a highly favorable effect of prednisolone treatment on the coagulopathy associated with canine chronic idiopathic hepatitis.

American Cocker Spaniel chronic hepatitis in Japan

BACKGROUND

American Cocker Spaniels are predisposed to chronic hepatitis.

OBJECTIVE

To describe the clinical and histological features of chronic hepatitis in Japanese American Cocker Spaniels.

ANIMALS

Thirteen cases examined from 2003 to 2009.

METHODS

Retrospective study. Medical records were searched for American Cocker Spaniels with chronic liver diseases. History, physical examination, clinicopathologic features, hepatic ultrasonographic findings, hepatic histopathology, and immunohistochemistry were evaluated.

RESULTS

The median age was 4.6 (1.9-10.7) years. Clinical signs included inappetence (11/13), ascites (11/13), lethargy (9/13), diarrhea (7/13), and melena (2/13). Only 1/13 dogs was jaundiced. Clinicopathological abnormalities were increased liver enzymes (gamma-glutamyl transpeptidase: 9/12, aspartate aminotransferase: 7/10, alanine aminotransferase: 6/13, alkaline phosphatase: 6/13), increased total serum bile acid concentrations (10/12), and hypoalbuminemia (10/13). The liver had an irregular surface in all dogs and acquired portosystemic collaterals were verified in 11/13 dogs by abdominal ultrasound (2), laparoscopy (4), or both (5). Liver histology revealed severe fibrosis and cirrhosis in all cases, subdivided in lobular dissecting hepatitis (7), periportal fibrosis (1), micronodular cirrhosis (3), and macronocular cirrhosis (2). Inflammatory activity was low to mild. Immunohistochemical stains showed ductular proliferation. The median survival time was 913 (range: 63-1981) days.

CONCLUSION AND CLINICAL IMPORTANCE

Hepatitis in Japanese American Cocker Spaniels is clinically silent until an advanced stage and is associated with severe hepatic fibrosis leading to cirrhosis, extensive ductular/putative hepatic progenitor cell proliferation, portal hypertension, and acquired portosystemic collateral shunting, but relatively long survival times. Lobular dissecting hepatitis seems more prevalent than in previously reported cases from other countries.

Effects of dexamethasone on the TGF-β1-induced epithelial-to-mesenchymal transition in human peritoneal mesothelial cells

The epithelial-to-mesenchymal transition (EMT) is known to have a role in appropriate embryonic development, the physiological response to injury and pathological events such as organ fibrosis and cancer progression. Glucocorticoid (GC), one of the most commonly used anti-inflammatory drugs, inhibits the deposition of extracellular matrix independent of its anti-inflammatory effect. The EMT of human peritoneal mesothelial cells (HPMCs) is a key mechanism of peritoneal fibrosis; however, it has not yet been investigated whether GC imposes any effect on the EMT of HPMCs. To investigate the therapeutic potential of GC on preserving peritoneal membrane function, we studied the effect of dexamethasone (DEXA), a synthetic GC, on the transforming growth factor-β1 (TGF-β1)-induced EMT in HPMCs. As assessed by changes in cell morphology, the expression of epithelial and mesenchymal cell markers (such as E-cadherin, ZO-1 and α-SMA, α-smooth muscle actin) and cell migration, DEXA inhibited the TGF-β1-induced EMT. RU486, a glucocorticoid receptor (GR) antagonist, blocked the effect of DEXA on the TGF-β1-induced EMT. Importantly, DEXA also induced the mesenchymal-to-epithelial transition of TGF-β1-stimulated HPMCs. The beneficial effect of DEXA on the TGF-β1-induced EMT was mediated through the amelioration of ERK and p38 mitogen-activated protein kinase (MAPK) phosphorylation; however, this effect was not related to the TGF-β1-induced activation of Smad2/3 signaling. DEXA inhibited glycogen synthase kinase-3β (GSK-3β) phosphorylation and the Snail upregulation induced by TGF-β1, which were also ameliorated by inhibitors of MAPK. In conclusion, this is the first study demonstrating the protective effect of DEXA on the EMT in TGF-β1-stimulated HPMCs by inhibiting MAPK activation, GSK-3β phosphorylation and Snail upregulation.

Current status of novel antifibrotic therapies in patients with chronic liver disease

Fibrosis accumulation is a dynamic process resulting from a wound-healing response to acute or chronic liver injury of all causes. The cascade starts with hepatocyte necrosis and apoptosis, which instigate inflammatory signaling by chemokines and cytokines, recruitment of immune cell populations, and activation of fibrogenic cells, culminating in the deposition of extracellular matrix. These key elements, along with pathways of transcriptional and epigenetic regulation, represent fertile therapeutic targets. New therapies include drugs specifically designed as antifibrotics, as well as drugs already available with well-established safety profiles, whose mechanism of action may also be antifibrotic. At the same time, the development of noninvasive fibrogenic markers, and techniques (e.g. fibroscan), as well as combined scoring systems incorporating serum and clinical features will allow improved assessment of therapy response. In aggregate, the advances in the elucidation of the biology of fibrosis, combined with improved technologies for assessment will provide a comprehensive framework for design of antifibrotics and their analysis in well-designed clinical trials. These efforts may ultimately yield success in halting the progression of, or reversing, liver fibrosis.

S-Nitroso-N-acetylcysteine induces de-differentiation of activated hepatic stellate cells and promotes antifibrotic effects in vitro

Nitric oxide (NO) has been shown to act as a potent antifibrogenic agent by decreasing myofibroblast differentiation. S-Nitroso-N-acetylcysteine (SNAC), a NO donor, attenuates liver fibrosis in rats, but the cellular and molecular mechanisms on liver myofibroblast-like phenotype still remain unknown. Here, we investigate the antifibrotic effects of SNAC on hepatic stellate cells, the major fibrogenic cell type in the liver. A murine GRX cell line was incubated with SNAC (100μM) or vehicle (control group) for 72h. Cell viability was measured by MTT colorimetric assay and the conversion of myofibroblast into quiescent fat-storing cell phenotype was evaluated by Oil-Red-O staining. TGFβ-1, TIMP-1, and MMP-13 levels were measure in the supernatant by ELISA. Profibrogenic- and fibrolytic-related gene expression was quantified using real-time qPCR. SNAC induced phenotype conversion of myofibroblast-like phenotype into quiescent cells. SNAC decreased gene and protein expression of TGFβ-1 and MMP-2 compared to control groups. Besides, SNAC down-regulated profibrogenic molecules and up-regulated MMP-13 gene expression, which plays a key role in the degradation of interstitial collagen in liver fibrosis. In conclusion, these findings demonstrate that SNAC efficiently can modulate the activation and functionality of murine hepatic stellate cells and could be considered as an antifibrotic treatment to human liver fibrosis.

Nanoscale hepatoprotective herbal decoction attenuates hepatic stellate cell activity and chloroform-induced liver damage in mice

BACKGROUND

San-Huang-Xie-Xin-Tang (SHXXT) decoction, a traditional Chinese medicine containing Rhei rhizome, Coptidis rhizome, and Scutellariae radix, is widely used in hepatoprotective therapy. However, preparation of the decoction requires addition of boiling water that causes loss of numerous effective components.

METHODS

To improve the bioavailability of the decoction, nanoscale SHXXT was developed. Chloroform-induced liver injury and hepatic stellate cell activity in mice were used to demonstrate the hepatoprotective characteristics of nanoscale SHXXT decoction.

RESULTS

Liver/body weight ratio and serum aspartate and alanine aminotranferase levels were recovered by the nanoscale SHXXT. TIMP-1 gene expression was inhibited and MMP-2 gene expression was accelerated in activated hepatic stellate cells.

CONCLUSION

Nanoscale SHXXT decoction prepared in room temperature water could have preserved hepatoprotective ability. The results of this study indicate that nanoscale SHXXT could be extracted easily. The simple preparation of this herbal decoction is more convenient and energy-efficient.

Perioperative conditions affect long-term hypertrophic scar formation

Corticosteroids are widely used as treatment for excessive scarring by intralesional injection with variable success rates. It is conceivable that systemically administered corticosteroids affect a wider range of inflammatory processes that influence wound healing and may be more successful in preventing hypertrophic scar formation. To study this presumption, we have used a standardized model of presternal scars caused by cardiothoracic surgery through a median sternotomy incision. During cardiac surgery with cardiopulmonary bypass, 1 mg/kg dexamethasone was administered preoperatively, and 0.5 mg/kg 8 hours postoperatively. The presternal scars were evaluated prospectively 2, 4, 6, 12, and 52 weeks postoperatively at standardized measuring points. The height and width of the scars were measured 12 and 52 weeks postoperatively using both a slide caliper and a 7.5-MHz ultrasound probe. Cardiopulmonary bypass was used in 31 of the 43 participants. Eleven patients (35%) in the dexamethasone group developed clinical hypertrophic scars compared with 4 patients (33%) in the control group. These differences were not statistically significant. However, cranial scars became significantly wider in the dexamethasone group compared with the control group (P = 0.04). Twelve weeks postoperatively scars were significantly higher in the dexamethasone group, both cranial (P = 0.05) and caudal (P = 0.03). The differences in scar width and height were mainly present in patients that developed hypertrophic scars. The present results suggest that administration of high-dose perioperative dexamethasone does not prevent hypertrophic scar formation. Its use together with the cardiopulmonary bypass, however, did affect scar dimensions negatively up to 52 weeks after surgery. These findings contribute to the concept of the involvement of perioperative immunologic responses in the etiology of hypertrophic scar formation.

Immunohistochemical localization of transforming growth factor β-1 and its relationship with collagen expression in advanced liver fibrosis due to biliary atresia

PURPOSE

Biliary atresia (BA) is the most common indication of liver transplantation in children. Pathogenesis of hepatic fibrosis, which is a prominent feature of BA, remains obscure. The purpose of this work was to determine the cellular sources of transforming growth factor beta-1 (TGFβ1) and establish the relationship between TGFβ1-producing cells and extracellular matrix producing myofibroblasts (MFBs) in advanced BA.

METHODS

Trichrome staining and immunohistochemistry were carried out to determine the expression pattern of collagen and TGFβ1 protein in explant liver specimens from patients with BA. The intensities of portal and lobular TGFβ1 expressions were compared. Immunofluorescence technique was carried out to determine the relationship between α-smooth muscle actin (α-SMA)-positive-MFB and TGFβ1-positve cells.

RESULTS

Lobular TGFβ1 protein expression was significantly higher than portal (89 ± 6 versus 10 ± 1 arbitrary units, P ≤ 0.05), whereas no difference was noted in livers used as control (10 ± 1.6 versus 19 ± 5 arbitrary units, P = 0.11). TGFβ1 expression was more in the center of nodules versus MFB in surrounding fibrous septa. Contrary to TGFβ1 expression, α1-SMA was mostly expressed in the portal structures and the adjacent fibrous septa enacting lobulation of the parenchyma. The results obtained by coimmunofluorescence staining showed no colocalization of α-SMA and TGFβ1.

CONCLUSIONS

TGFβ1 protein expression is mostly localized to hepatocytes in advanced BA. These findings suggest a paracrine mechanisms of TGFβ1-driven fibrogenesis in advanced BA.

Liver fibrosis in biliary atresia

Biliary atresia (BA) is the most common cholestatic liver disorder requiring liver transplantation in children. Hepatic fibrosis is not only a universal and prominent feature of BA, it is also the most important predictor of outcome following portoenterostomy (PE). Without PE, the progression of hepatic fibrosis is quite dramatic, such that liver cirrhosis is established within a few weeks after birth. Etiologies and molecular networks underpinning such an expeditious fibrogenic process have not been well established. However, immune and nonimmune factors implicated in the pathogenesis of BA, and the resultant cholestasis and oxidative stress, appear to be the main triggers of hepatic fibrosis in BA. Owing to a lack of validated noninvasive tools to monitor liver fibrosis, current prognostic models of BA entail clinical and biochemical variables reflecting liver dysfunction rather than hepatic fibrogenesis. Further work is necessary to validate the results of preliminary studies indicating a good relationship between liver fibrosis determined by transient elastography and other clinical and routinely performed biochemical parameters in pediatric patients. Although a prime candidate for a number of antifibrotic therapies on the horizon, owing to poor understanding of molecular mechanisms, a clear framework of antifibrotic targets has not been outlined in BA. Similarly, specific antifibrotic therapies have not yet been incorporated in clinical practice, limiting these measures to prompt diagnosis and PE operation, prevention and treatment of cholangitis and optimal nutritional support including the administration of fat-soluble vitamins.

Molecular profiling of CD3-CD4+ T cells from patients with the lymphocytic variant of hypereosinophilic syndrome reveals targeting of growth control pathways

The clonal CD3(-)CD4(+) T-cell population characterizing lymphocytic variant hypereosinophilic syndrome (L-HES) persists for years, with a subgroup of patients ultimately progressing to T lymphoma. The molecular changes associated with the premalignant clone and the emergence of malignant subclones are unknown, precluding the development of targeted therapy for this HES variant. In this study, we used whole genome arrays to examine gene expression in the CD3(-)CD4(+) T cells and found that 850 genes were differentially regulated during chronic disease compared with CD3(+)CD4(+) T cells from healthy donors. Changes in the expression of 349 genes were altered in association with the clinical progression from chronic L-HES to T lymphoma in 1 patient, with 87 of 349 genes representing further changes in genes whose expression was altered in all chronic disease patients (87 of 850). Array analysis after CD2/CD28-mediated activation revealed that the major gene expression changes observed in the CD3(-)CD4(+) T cells do not reflect activation induced alterations but rather pathways involved in T-cell homeostasis, including transforming growth factor-beta signaling, apoptosis, and T-cell maturation, signaling, and migration. Examination of microRNA expression in the CD3(-)CD4(+) T cells from patients with chronic disease identified 23 microRNAs that changed significantly, among which miR-125a further decreased in association with one patient's evolution to T lymphoma.

Noninvasive assessment of liver fibrosis: serum markers, imaging, and other modalities

Liver fibrosis is a common pathway of injury after chronic insult to the liver. The evolution of liver fibrosis to cirrhosis has many clinical implications, including bleeding, infection, hepatocellular carcinoma, and death. The reference standard for diagnosing liver fibrosis is currently histologic assessment of tissue obtained through liver biopsy. Although this provides valuable information, it has limitations, including its invasiveness, sampling error, observer variability, and the use of categorical scoring systems. This article outlines the various noninvasive markers, including blood tests, imaging, and novel technologies. It examines the principles behind their development, their diagnostic accuracy, and their evolution.

Absorption and tissue distribution of an immunomodulatory alpha-D-glucan after oral administration of Tricholoma matsutake

Alpha-D-glucan (MPG-1) separated from Tricholoma matsutake (CM6271) has been reported to show immunomodulatory activities. In this study, the plasma concentration and tissue distribution of MPG-1 after CM6271 oral administration were investigated as part of the action mechanism analysis. When CM6271 was orally administered in a single dose to mice, MPG-1 was absorbed via the intestinal tract, appeared in plasma after 16 h, was gradually excreted from the blood, and fell to background level after 48 h. The time course analysis of MPG-1 in plasma showed the following pharmacokinetic parameters of MPG-1: tmax = 24 h; Cmax = 161.1 ng/mL; AUC(0-infinity) = 2559.7 ng x h/mL. Moreover, MPG-1 was confirmed to localize in Peyer's patches, mesenteric lymph nodes (MLN), and the spleen and to promote IL-12 p70 production and NK cell activity. These results suggest that MPG-1 stimulated the intestinal immune system through Peyer's patches; moreover, it was taken into the blood and stimulated the systemic immune system.

Targeting liver myofibroblasts: a novel approach in anti-fibrogenic therapy

Chronic liver disease results in a liver-scarring response termed fibrosis. Excessive scarring leads to cirrhosis, which is associated with high morbidity and mortality. The only treatment for liver cirrhosis is liver transplantation; therefore, much attention has been directed toward therapies that will slow or reverse fibrosis. Although anti-fibrogenic therapies have been shown to be effective in experimental animal models, licensed therapies have yet to emerge. A potential problem for any anti-fibrogenic therapy in the liver is the existence of the body’s major drug metabolising cell (the hepatocyte) adjacent to the primary fibrosis-causing cell, the myofibroblast. This article reviews the development of a human recombinant single-chain antibody (scAb) that binds to the surface of myofibroblasts. This antibody binds specifically to myofibroblasts in fibrotic mouse livers. When conjugated with a compound that stimulates myofibroblast apoptosis, the antibody directs the specific apoptosis of myofibroblasts with greater specificity and efficacy than the free compound. The antibody also reduces the adverse effect of liver macrophage apoptosis and—in contrast to the free compound—reversed fibrosis in the sustained injury model used. These data suggest that specifically stimulating the apoptosis of liver myofibroblasts using a targeting antibody has potential in the treatment of liver fibrosis.

Neonatal dexamethasone administration causes progressive renal damage due to induction of an early inflammatory response

Glucocorticoids (GCs) are widely used to prevent chronic lung disease in immature newborns. Emerging evidence indicates that GC exposure in early life may interfere with kidney function and is associated with hypertension in later life. In this study, we have investigated the effect of neonatal dexamethasone (DEX) administration on renal function in rats. Male rats were treated with DEX in the first 3 days after birth, controls received saline (SAL). Severe renal damage associated with premature death was found at 50 wks upon DEX treatment, while renal function and morphology were normal in controls. A subsequent time-course study was performed from 2 days to 32 wks. Compared with controls, neonatal DEX administration led to significant and persistent growth retardation. Progressive proteinuria and increased systolic blood pressure were found from 8 wks onwards in DEX-treated animals. Renal α-SMA gene expression was elevated from wk 24 onwards and morphological fibrosis was noted at 32 wks of age following DEX treatment. Markedly increased renal gene expression of TNF-α and MCP-1 in DEX -treated rats was observed at day 7, probably contributing to the permanent increase in interstitial macrophage numbers that started at 14 days. Permanently elevated renal TGF-β gene expression was induced by DEX administration from 4 wks onwards. Our data indicate that neonatal DEX administration in rats leads to renal failure in later life, presumably due to an early inflammatory trigger that elicits a persistent pro-fibrotic process that eventually results in progressive renal deterioration.

Glucocorticoids play a key role in circadian cell cycle rhythms

Clock output pathways play a pivotal role by relaying timing information from the circadian clock to a diversity of physiological systems. Both cell-autonomous and systemic mechanisms have been implicated as clock outputs; however, the relative importance and interplay between these mechanisms are poorly understood. The cell cycle represents a highly conserved regulatory target of the circadian timing system. Previously, we have demonstrated that in zebrafish, the circadian clock has the capacity to generate daily rhythms of S phase by a cell-autonomous mechanism in vitro. Here, by studying a panel of zebrafish mutants, we reveal that the pituitary–adrenal axis also plays an essential role in establishing these rhythms in the whole animal. Mutants with a reduction or a complete absence of corticotrope pituitary cells show attenuated cell-proliferation rhythms, whereas expression of circadian clock genes is not affected. We show that the corticotrope deficiency is associated with reduced cortisol levels, implicating glucocorticoids as a component of a systemic signaling pathway required for circadian cell cycle rhythmicity. Strikingly, high-amplitude rhythms can be rescued by exposing mutant larvae to a tonic concentration of a glucocorticoid agonist. Our work suggests that cell-autonomous clock mechanisms are not sufficient to establish circadian cell cycle rhythms at the whole-animal level. Instead, they act in concert with a systemic signaling environment of which glucocorticoids are an essential part.

To guarantee normal growth and to avoid tumor formation, the timing of cell division must be under strict control. Remarkably, cells, from bacteria to man, often divide only at certain times of day, suggesting the influence of internal biological clocks. A central pacemaker structure in the brain controls diurnal rhythms of behavior and hormone release. However, biological clocks are also encountered in almost every cell type (so-called “peripheral” clocks), in which they regulate daily changes in cell biology, including cell division. Very little is known to date about how the two clock systems interact. Here, by examining zebrafish strains with defects in hormone production, we find that peripheral clocks require the steroid hormone cortisol to generate daily rhythms of cell proliferation. Interestingly, the daily changes in cortisol levels observed in normal zebrafish are not required to achieve this control; treating the cortisol-deficient strains with constant levels of a drug that mimics the effects of cortisol restores normal cell-division rhythms. Thus, it appears that internal cell timers cooperate with hormonal signals to regulate the timing of cell division.

To establish circadian cell cycle rhythms, cell-autonomous clock mechanisms act in concert with a systemic signaling environment of which glucocorticoids are an essential part.

Glucocorticoids activate TGF-beta induced PAI-1 and CTGF expression in rat hepatocytes

Background

In addition to the activation of hepatic stellate cells TGF-β govern apoptosis and growth control of hepatocytes in liver injury. In non-parenchymal cells, TGF-β induces plasminogen activator inhibitor 1 (PAI-1) and connective tissue growth factor (CTGF) expression, which are involved in extra cellular matrix formation. Both genes were also regulated by glucocorticoids, which in certain cases showed antagonistic effects to the TGF-β-Smad 3 pathway. The purpose of our work was to investigate the influence of TGF-β and dexamethasone on PAI-1 and CTGF expression and secretion in primary hepatocytes.

Results

By examining PAI-1 and CTGF mRNA and protein expression in cell lysates and cell-conditioned media under the influence of TGF-β and dexamethasone, we analysed signalling pathways controlling their expression. TGF-β and dexamethasone significantly co-induce PAI-1 and CTGF protein expression. On the other hand, we showed that TGF-β diminished a glucocorticoid receptor dependent luciferase reporter signal in Hep-G2. Inhibition of Erk downstream activation decreased TGF-β induced CTGF and PAI-1 expression to a basal level. PAI-1 was directly secreted by hepatocytes, whereas secretion of CTGF was retarded.

Conclusion

The data provide evidence that beside the TGF-β-Smad 3 pathway CTGF and PAI-1 expression is additionally dependent on Erk activity in hepatocytes giving new insights into regulation of the profibrogenic proteins.

Transcriptional regulation of stellate cell activation

The identification of activated hepatic stellate cells and related cell types as key fibrogenic effectors during liver injury has led to intense evaluation of transcriptional events underlying their behavior. While initial studies focused on characterizing interactions between transcription factors and regulatory regions within gene promoters, epigenetic mechanisms have emerged as major determinants of gene activation and repression, in particular histone acetylation and promoter methylation, as well as other complex conditional interactions that underlie global changes in gene expression. Three examples are provided that illustrate how stellate cell activation may be controlled by widely divergent regulatory pathways, including alternative splicing of a growth inhibitory transcription factor (Kruppel-like factor-6), epigenetic regulation of a factor regulating stellate cell survival (nuclear factor kappaB), and regulation of a transcription factor whose expression maintains stellate cell quiescence (LIM homeobox gene 2 [Lhx2]). These complex cascades illustrate how clarifying the finely tuned interdependent layers of transcriptional, translational, post-translational and epigenetic gene regulation in stellate cells is raising new prospects for therapy of hepatic fibrosis.

Administration of prednisolone phosphate?liposomes reduces wound contraction in a rat partial-thickness wound model

Macrophages play an important role in the inflammatory phase of wound healing and their activity regulates fibroblasts and keratinocytes. Modulation of macrophage function may result in improvement of the wound healing process. Prednisolone phosphate (PLP) encapsulated into liposomes was administered to partial-thickness wounds in rats. A single dose of 75 microg/kg, applied directly after wounding, resulted in up to a 30% reduction of wound contraction at 28 days after wounding. This effect could not be achieved in the group that was administered free PLP or liposomes containing phosphate-buffered saline to the wound. The number of myofibroblasts was up to 50% lower in wounds treated with the liposomal PLP at 4 days after wounding. The number of macrophages present in the wounds was not statistically different between groups. Most probably, the production of cytokines and growth factors by macrophages is altered after phagocytosing the liposomes, resulting in reduced wound contraction.

Anti-fibrotic effects of theophylline on lung fibroblasts

Theophylline has been used in the management of bronchial asthma and chronic obstructive pulmonary disease for over 50 years. It has not only a bronchodilating effect, but also an anti-inflammatory one conducive to the inhibition of airway remodeling, including subepithelial fibrosis. To date however, whether theophylline has a direct inhibitory effect on airway fibrosis has not been established. To clarify this question, we examined whether theophylline affected the function of lung fibroblasts. Theophylline suppressed TGF-beta-induced type I collagen (COL1) mRNA expression in lung fibroblasts and also inhibited fibroblast proliferation stimulated by FBS and TGF-beta-induced alpha-SMA protein. A cAMP analog also inhibited TGF-beta-induced COL1 mRNA expression in lung fibroblasts. A PKA inhibitor reduced the inhibitory effect of theophylline on TGF-beta-induced COL1 mRNA expression. These results indicate that theophylline exerts anti-fibrotic effects, at least partly, through the cAMP-PKA pathway.

Rationale for combination therapies for choroidal neovascularization

PURPOSE

To provide a conceptual framework for the development and use of combination therapies for choroidal neovascularization secondary to age-related macular degeneration.

DESIGN

Literature review, integration of data, and creation of hypothesis.

METHODS

An assessment of angiogenesis, cancer therapy, and inflammation was performed as they may pertain to choroidal neovascularization. A conceptual framework was created in which therapies for choroidal neovascularization could be evaluated alone or in combination.

RESULTS

Angiogenesis occurs because cells produce angiogenic stimuli to encourage blood vessels to develop. This growth of vessels involves an orchestrated interaction among many mediators offering opportunity to modulate or inhibit the entire process. A two-component model for choroidal neovascularization is proposed. The vascular component of choroidal neovascularization is comprised of vascular endothelial cells, endothelial cell precursors, and pericytes. The extravascular component, which by histopathology appears to be both the source of angiogenic stimuli and often the largest component volumetrically, is comprised of inflammatory, glial and retinal pigment epithelial cells, and fibroblasts. Tissue damage can be caused by either component. Each component can be targeted through as variety of monotherapies. Combination therapies offer the possibility of attacking one component in more than one way or by attacking both components simultaneously.

CONCLUSIONS

The two-component model of choroidal neovascularization can be used to evaluate the mechanism of action and possible interactions of these agents in a conceptual framework. Extension of these ideas can help guide development of new treatment agents and approaches.

Isolation and characterization of a novel immunomodulatory alpha-glucan-protein complex from the mycelium of Tricholoma matsutake in basidiomycetes

Tricholoma matsutake, a high-class edible mushroom in Japan, has been reported to have excellent biological activities, but difficulty in cultivating the fruit bodies and limited bulk availability have restricted detailed studies. We have developed a method of culturing in tanks, enabling the bulk supply of the mycelia. The preparation (CM6271) exerts modulative effects on the immune competence of mice and rats. In this study, a sodium hydroxide extract of CM6271 was defatted followed by fractionation with a combination of ion exchange chromatography and gel filtration in order to identify the components involved in the expression of the activity, and a single peak fraction (MPG-1) was obtained with reversed phase chromatography. MPG-1 was a glycoprotein (sugar:protein ratio, 94.3:5.7) with a relative molecular mass of 360 kDa, and the sugar moiety contained about 90% glucose. NMR spectra and methylation analysis revealed that the alpha-1,4-linkage was the predominant glucan linkage with alpha-1,6- and alpha-1,2-linkages in the minority. The amino acid composition in the protein moiety was rich in glutamine, alanine, asparagine, leucine, glycine, valine, serine, threonine, isoleucine, and proline. MPG-1 was resistant to degradation with amylase or protease. The oral administration of MPG-1 promoted, in a dose-dependent manner, the recovery of the mouse natural killer cell activity and serum IL-12 level that had been reduced by the loading of restraint stress. The dose of MPG-1 (25 mg/kg) required for the expression of the effect decreases to 1/12 of that of CM6271 (300 mg/kg). Furthermore, MPG-1 formed a complex with TGF-beta1 in vitro, modulating the biological activity of TGF-beta1 by binding to its active form. These results indicate that the mycelium of T. matsutake contains a novel alpha-glucan-protein complex with immunomodulatory activities.