A selective ROCK inhibitor, Y27632, prevents dimethylnitrosamine-induced hepatic fibrosis in rats

Prenatal exposure to dibutyl phthalate contributes to erectile dysfunction in offspring male rats by activating the RhoA/ROCK signalling pathway

Prenatal exposure to dibutyl phthalate (DBP) has been reported to cause erectile dysfunction (ED) in adult offspring rats. However, its underlying mechanisms are not fully understood. Previously, we found that DBP activates the RhoA/ROCK pathway in the male reproductive system. This study investigated how prenatal exposure to DBP activates the RhoA/ROCK signalling pathway, leading to ED in male rat offspring. Pregnant rats were stratified into DBP-exposed and NC groups, with the exposed group receiving 750 milligrams per kilogram per day (mg/kg/day) of DBP through gavage from days 14-18 of gestation. DBP exposure activated the RhoA/ROCK pathway in the penile corpus cavernosum (CC) of descendants, causing smooth muscle cell contraction, fibrosis, and apoptosis, all of which contribute to ED. In vitro experiments confirmed that DBP induces apoptosis and RhoA/ROCK pathway activation in CC smooth muscle cells. Treatment of DBP-exposed offspring with the ROCK inhibitor Y-27632 for 8 weeks significantly improved smooth muscle cell condition, erectile function, and reduced fibrosis. Thus, prenatal DBP exposure induces ED in offspring through RhoA/ROCK pathway activation, and the ROCK inhibitor Y-27632 shows potential as an effective treatment for DBP-induced ED.

Mechanical homeostasis imbalance in hepatic stellate cells activation and hepatic fibrosis

Chronic liver disease or repeated damage to hepatocytes can give rise to hepatic fibrosis. Hepatic fibrosis (HF) is a pathological process of excessive sedimentation of extracellular matrix (ECM) proteins such as collagens, glycoproteins, and proteoglycans (PGs) in the hepatic parenchyma. Changes in the composition of the ECM lead to the stiffness of the matrix that destroys its inherent mechanical homeostasis, and a mechanical homeostasis imbalance activates hepatic stellate cells (HSCs) into myofibroblasts, which can overproliferate and secrete large amounts of ECM proteins. Excessive ECM proteins are gradually deposited in the Disse gap, and matrix regeneration fails, which further leads to changes in ECM components and an increase in stiffness, forming a vicious cycle. These processes promote the occurrence and development of hepatic fibrosis. In this review, the dynamic process of ECM remodeling of HF and the activation of HSCs into mechanotransduction signaling pathways for myofibroblasts to participate in HF are discussed. These mechanotransduction signaling pathways may have potential therapeutic targets for repairing or reversing fibrosis.

Urea Transporter Inhibitor 25a Reduces Ascites in Cirrhotic Rats

Ascites is a typical symptom of liver cirrhosis that is caused by a variety of liver diseases. Ascites severely affects the life quality of patients and needs long-term treatment. 25a is a specific urea transporter inhibitor with a diuretic effect that does not disturb the electrolyte balance. In this study, we aimed to determine the therapeutic effect of 25a on ascites with a dimethylnitrosamine (DMN)-induced cirrhotic rat model. It was found that 100 mg/kg of 25a significantly increased the daily urine output by 60% to 97% and reduced the daily abdominal circumference change by 220% to 260% in cirrhotic rats with a water intake limitation. The 25a treatment kept the serum electrolyte levels within normal ranges in cirrhotic rats. The H&E and Masson staining of liver tissue showed that 25a did not change the cirrhotic degree. A serum biochemical examination showed that 25a did not improve the liver function in cirrhotic rats. A Western blot analysis showed that 25a did not change the expression of fibrosis-related marker protein α-SMA, but significantly decreased the expressions of type I collagen in the liver of cirrhotic rats, indicating that 25a did not reverse cirrhosis, but could slow the cirrhotic progression. These data indicated that 25a significantly reduced ascites via diuresis without an electrolyte imbalance in cirrhotic rats. Our study provides a proof of concept that urea transporter inhibitors might be developed as novel diuretics to treat cirrhotic ascites.

Regulators, functions, and mechanotransduction pathways of matrix stiffness in hepatic disease

The extracellular matrix (ECM) provides physical support and imparts significant biochemical and mechanical cues to cells. Matrix stiffening is a hallmark of liver fibrosis and is associated with many hepatic diseases, especially liver cirrhosis and carcinoma. Increased matrix stiffness is not only a consequence of liver fibrosis but is also recognized as an active driver in the progression of fibrotic hepatic disease. In this article, we provide a comprehensive view of the role of matrix stiffness in the pathological progression of hepatic disease. The regulators that modulate matrix stiffness including ECM components, MMPs, and crosslinking modifications are discussed. The latest advances of the research on the matrix mechanics in regulating intercellular signaling and cell phenotype are classified, especially for hepatic stellate cells, hepatocytes, and immunocytes. The molecular mechanism that sensing and transducing mechanical signaling is highlighted. The current progress of ECM stiffness's role in hepatic cirrhosis and liver cancer is introduced and summarized. Finally, the recent trials targeting ECM stiffness for the treatment of liver disease are detailed.

ADSCs-derived exosomes ameliorate hepatic fibrosis by suppressing stellate cell activation and remodeling hepatocellular glutamine synthetase-mediated glutamine and ammonia homeostasis

Background

Hepatic fibrosis is a common pathologic stage in chronic liver disease development, which might ultimately lead to liver cirrhosis. Accumulating evidence suggests that adipose-derived stromal cells (ADSCs)-based therapies show excellent therapeutic potential in liver injury disease owing to its superior properties, including tissue repair ability and immunomodulation effect. However, cell-based therapy still limits to several problems, such as engraftment efficiency and immunoreaction, which impede the ADSCs-based therapeutics development. So, ADSCs-derived extracellular vesicles (EVs), especially for exosomes (ADSC-EXO), emerge as a promise cell-free therapeutics to ameliorate liver fibrosis. The effect and underlying mechanisms of ADSC-EXO in liver fibrosis remains blurred.

Methods

Hepatic fibrosis murine model was established by intraperitoneal sequential injecting the diethylnitrosamine (DEN) for two weeks and then carbon tetrachloride (CCl₄) for six weeks. Subsequently, hepatic fibrosis mice were administrated with ADSC-EXO (10 μg/g) or PBS through tail vein infusion for three times in two weeks. To evaluate the anti-fibrotic capacity of ADSC-EXO, we detected liver morphology by histopathological examination, ECM deposition by serology test and Sirius Red staining, profibrogenic markers by qRT-PCR assay. LX-2 cells treated with TGF-β (10 ng/ml) for 12 h were conducted for evaluating ADSC-EXO effect on activated hepatic stellate cells (HSCs). RNA-seq was performed for further analysis of the underlying regulatory mechanisms of ADSC-EXO in liver fibrosis.

Results

In this study, we obtained isolated ADSCs, collected and separated ADSCs-derived exosomes. We found that ADSC-EXO treatment could efficiently ameliorate DEN/CCl₄-induced hepatic fibrosis by improving mice liver function and lessening hepatic ECM deposition. Moreover, ADSC-EXO intervention could reverse profibrogenic phenotypes both in vivo and in vitro, including HSCs activation depressed and profibrogenic markers inhibition. Additionally, RNA-seq analysis further determined that decreased glutamine synthetase (Glul) of perivenous hepatocytes in hepatic fibrosis mice could be dramatically up-regulated by ADSC-EXO treatment; meanwhile, glutamine and ammonia metabolism-associated key enzyme OAT was up-regulated and GLS2 was down-regulated by ADSC-EXO treatment in mice liver. In addition, glutamine synthetase inhibitor would erase ADSC-EXO therapeutic effect on hepatic fibrosis.

Conclusions

These findings demonstrated that ADSC-derived exosomes could efficiently alleviate hepatic fibrosis by suppressing HSCs activation and remodeling glutamine and ammonia metabolism mediated by hepatocellular glutamine synthetase, which might be a novel and promising anti-fibrotic therapeutics for hepatic fibrosis disease.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-022-03049-x.

Endostatin in fibrosis and as a potential candidate of anti-fibrotic therapy

Fibrotic diseases pose significant clinical challenges due to their broadness and complexity. Thus, a better understanding of fibrogenesis and the development of more effective treatments is imperative. Recent evidence suggests a significant antifibrotic potential of an endogenous glycoprotein, endostatin. While endostatin has been widely studied for its role as an anticancer adjuvant by inhibiting tumor angiogenesis, its possible implication in fibrosis remains largely unclear. Here, we review the role of endostatin in various cellular processes and highlight its antifibrotic activity. We hypothesize that endostatin conveys a homeostatic function in the process of fibrosis by regulating (a) TGF-β1 and its downstream signaling; (b) RhoA/ROCK pathway; (c) NF-κB signaling pathway; (d) expression of EGR-1; (e) PDGF/PDGFR pathway; (f) autophagy-related pathways; (g) pathways associated with cell proliferation and apoptosis. Finally, we propose a schematic model of the antifibrotic roles and mechanisms of endostatin; also, we outline future research directions of endostatin and aim to present a potential therapeutic approach for fibrosis.

Rho-Kinase as a Therapeutic Target for Nonalcoholic Fatty Liver Diseases

Nonalcoholic fatty liver disease (NAFLD) is a major public health problem and the most common form of chronic liver disease, affecting 25% of the global population. Although NAFLD is closely linked with obesity, insulin resistance, and type 2 diabetes mellitus, knowledge on its pathogenesis remains incomplete. Emerging data have underscored the importance of Rho-kinase (Rho-associated coiled-coil-containing kinase [ROCK]) action in the maintenance of normal hepatic lipid homeostasis. In particular, pharmacological blockade of ROCK in hepatocytes or hepatic stellate cells prevents the progression of liver diseases such as NAFLD and fibrosis. Moreover, mice lacking hepatic ROCK1 are protected against obesity-induced fatty liver diseases by suppressing hepatic de novo lipogenesis. Here we review the roles of ROCK as an indispensable regulator of obesity-induced fatty liver disease and highlight the key cellular pathway governing hepatic lipid accumulation, with focus on de novo lipogenesis and its impact on therapeutic potential. Consequently, a comprehensive understanding of the metabolic milieu linking to liver dysfunction triggered by ROCK activation may help identify new targets for treating fatty liver diseases such as NAFLD.

Reversine and herbal Xiang-Sha-Liu-Jun-Zi decoction ameliorate thioacetamide-induced hepatic injury by regulating the RelA/NF-κB/caspase signaling pathway

This study investigated the anti-fibrotic effects of reversine and Chinese medicine Xiang–Sha–Liu–Jun–Zi decoction (XSLJZD) on thioacetamide (TAA)-induced hepatic injury. Sprague-Dawley rats were intraperitoneally administered with TAA, then injected with reversine intraperitoneally, and/or orally provided with XSLJZD. TAA resulted in liver injury with increases in the liver index and levels of serum aspartate aminotransferase (AST) and alanine aminotransferase. Reversine alleviated the liver index and AST level and improved TAA-induced pathological changes but decreased TAA-induced collagen deposition, and α-smooth muscle actin and transforming growth factor-β1 expression. Reversine also modulated the mRNA levels of inflammatory cytokines, such as RelA, interleukin (IL)-17A, IL-22, IL-1β, IL-6, NLR family pyrin domain containing 3, platelet-derived growth factor, and monocyte chemoattractant protein, and suppressed nuclear factor (NF)-κB (p65) phosphorylation and caspase 1 activation. Meanwhile, XSLJZD protected TAA-injured liver without increasing fibrosis and enhanced the regulating effect of reversine on RelA, IL-17A, IL-1β, and MCP-1 cytokines. In conclusion, reversine ameliorates liver injury and inhibits inflammation reaction by regulating NF-κB, and XSLJZD protects the liver through its synergistic effect with reversine on regulating inflammatory cytokines.

Activation of the RhoA/ROCK pathway contributes to renal fibrosis in offspring rats induced by maternal exposure to di-n-butyl phthalate

Maternal exposure to di-n-butyl phthalate (DBP) can cause renal fibrosis in adult offspring rats. However, its underlying mechanisms have not yet been fully understood. In this study, we investigated whether the RhoA/ROCK pathway plays an important role in offspring renal fibrosis induced by maternal exposure to DBP. Our results showed that maternal exposure to DBP (850 mg/kg/day orally feeding during gestational days 14-18) activated the RhoA/ROCK pathway and induced epithelial-mesenchymal transition (EMT) in kidneys of offspring rats. Compared with the control group treated with normal saline, EMT in the kidneys of offspring rats undergoing 8 weeks of ROCK inhibitor Y-27632 treatment (at a dose of 30 mg/kg) was significantly inhibited, the degree of renal fibrosis was significantly reduced, and the renal function was significantly improved. DBP (10 μmol/L) activated the RhoA/ROCK pathway and induced EMT in NRK-52E cells in vitro. Both 5 μM and 10 μM Y-27632, a ROCK inhibitor, significantly reduced the EMT of NRK-52E cells. Taken together, our findings suggest that the RhoA/ROCK pathway plays an important role in the pathogenesis of renal fibrosis in offspring rats induced by maternal exposure to DBP via promoting EMT of renal tubular epithelial cells.

Integrin: Basement membrane adhesion by corneal epithelial and endothelial cells

Integrins mediate adhesion of cells to substrates and maintain tissue integrity by facilitating mechanotransduction between cells, the extracellular matrix, and gene expression in the nucleus. Changes in integrin expression in corneal epithelial cells and corneal endothelial cells impacts their adhesion to the epithelial basement membrane (EpBM) and Descemet's membrane, respectively. Integrins also play roles in assembly of basement membranes by both activating TGFβ1 and other growth factors. Over the past two decades, this knowledge has been translated into methods to grow corneal epithelial and endothelial cells in vitro for transplantation in the clinic thereby transforming clinical practice and quality of life for patients. Current knowledge on the expression and function of the integrins that mediate adhesion to the basement membrane expressed by corneal epithelial and endothelial cells in health and disease is summarized. This is the first review to discuss similarities and differences in the integrins expressed by both cell types.

Reduction in SNAP-23 Alters Microfilament Organization in Myofibrobastic Hepatic Stellate Cells

Hepatic stellate cells (HSC) are critical effector cells of liver fibrosis. In the injured liver, HSC differentiate into a myofibrobastic phenotype. A critical feature distinguishing myofibroblastic from quiescent HSC is cytoskeletal reorganization. Soluble NSF attachment receptor (SNARE) proteins are important in trafficking of newly synthesized proteins to the plasma membrane for release into the extracellular environment. The goals of this project were to determine the expression of specific SNARE proteins in myofibroblastic HSC and to test whether their alteration changed the HSC phenotype in vitro and progression of liver fibrosis in vivo. We found that HSC lack the t-SNARE protein, SNAP-25, but express a homologous protein, SNAP-23. Downregulation of SNAP-23 in HSC induced reduction in polymerization and disorganization of the actin cytoskeleton associated with loss of cell movement. In contrast, reduction in SNAP-23 in mice by monogenic deletion delayed but did not prevent progression of liver fibrosis to cirrhosis. Taken together, these findings suggest that SNAP-23 is an important regular of actin dynamics in myofibroblastic HSC, but that the role of SNAP-23 in the progression of liver fibrosis in vivo is unclear.

ROCK1 inhibitor stabilizes E-cadherin and improves barrier function in experimental necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is a devastating gastrointestinal disease of newborns. Although incompletely understood, NEC is associated with intestinal barrier dysfunction. E-cadherin, an adherens junction, is a protein complex integral in maintaining normal barrier homeostasis. Rho-associated protein kinase-1 (ROCK1) is a kinase that regulates the E-cadherin complex, and p120-catenin is a subunit of the E-cadherin complex that has been implicated in stabilizing the cadherin complex at the plasma membrane. We hypothesized that E-cadherin is decreased in NEC and that inhibition of ROCK1 would protect against adherens junction disruption. To investigate this, a multimodal approach was used: In vitro Caco-2 model of NEC (LPS/TNFα), rap pup model (hypoxia + bacteria-containing formula), and human intestinal samples. E-cadherin was decreased in NEC compared with controls, with relocalization from the cell border to an intracellular location. ROCK1 exhibited a time-dependent response to disease, with increased early expression in NEC and decreased expression at later time points and disease severity. Administration of ROCK1 inhibitor (RI) resulted in preservation of E-cadherin expression at the cell border, preservation of intestinal villi on histological examination, and decreased apoptosis. ROCK1 upregulation in NEC led to decreased association of E-cadherin to p120 and increased intestinal permeability. RI helped maintain the stability of the E-cadherin-p120 complex, leading to improved barrier integrity and protection from experimental NEC.NEW & NOTEWORTHY This paper is the first to describe the effect of ROCK1 on E-cadherin expression in the intestinal epithelium and the protective effects of ROCK inhibitor on E-cadherin stability in necrotizing enterocolitis.

Effects of losartan and atorvastatin on the development of early posttraumatic joint stiffness in a rat model

BACKGROUND

After a trauma, exuberant tissue healing with fibrosis of the joint capsule can lead to posttraumatic joint stiffness (PTJS). Losartan and atorvastatin have both shown their antifibrotic effects in different organ systems.

OBJECTIVE

The purpose of this study was the evaluation of the influence of losartan and atorvastatin on the early development of joint contracture. In addition to joint angles, the change in myofibroblast numbers and the distribution of bone sialoprotein (BSP) were assessed.

STUDY DESIGN AND METHODS

In this randomized and blinded experimental study with 24 rats, losartan and atorvastatin were compared to a placebo. After an initial joint injury, rat knees were immobilized with a Kirschner wire. Rats received either losartan, atorvastatin or a placebo orally daily. After 14 days, joint angle measurements and histological assessments were performed.

RESULTS

Losartan increased the length of the inferior joint capsule. Joint angle and other capsule length measurements did not reveal significant differences between both drugs and the placebo. At cellular level both losartan and atorvastatin reduced the total number of myofibroblasts (losartan: 191±77, atorvastatin: 98±58, placebo: 319±113 per counting field, p<0.01) and the percentage area of myofibroblasts (losartan: 2.8±1.8% [p<0.05], atorvastatin: 2.5±1.7% [p<0.01], vs control [6.4±4%], respectively). BSP was detectable in equivalent amounts in the joint capsules of all groups with only a trend toward a reduction of the BSP-stained area by atorvastatin.

CONCLUSION

Both atorvastatin and losartan reduced the number of myofibroblasts in the posterior knee joint capsule of rat knees 2 weeks after trauma and losartan increased the length of the inferior joint capsule. However, these changes at the cellular level did not translate an increase in range of motion of the rats´ knee joints during early contracture development.

Vitamin A-coupled liposomal Rho-kinase inhibitor ameliorates liver fibrosis without systemic adverse effects

AIM

Rho-kinase (ROCK) inhibitor could ameliorate liver fibrosis by suppressing hepatic stellate cell (HSC) activation. However, because systemic administration of ROCK inhibitor causes serious adverse effects, we developed a drug delivery system selectively delivering ROCK inhibitor to HSCs. Here, we examined whether our developed vitamin A (VA)-coupled liposomal ROCK inhibitor reduced liver fibrosis in rats without causing systemic adverse effects.

METHODS

LX-2 HSCs were analyzed for morphological changes and the expression of profibrotic proteins. The inhibitory effects of VA-coupled liposomal ROCK inhibitor on liver fibrosis were confirmed in a rat model of liver fibrosis induced by i.p. injection of carbon tetrachloride. The degree of liver fibrosis, biochemical changes, and survival rates were also investigated.

RESULTS

Vitamin A-coupled liposomal ROCK inhibitor had an effect at approximately 1/100 the amount of the free ROCK inhibitor for inhibiting the activation of LX-2 cells and caused significant decreases in the expression levels of α-smooth muscle actin (SMA) and transforming growth factor (TGF)-β1. The degree of liver fibrosis was suppressed by treatment with VA-coupled liposomal ROCK inhibitor, and the expression of α-SMA and TGF-β1 in liver tissues was also significantly suppressed. In addition, serum levels of alanine aminotransferase and hyaluronic acid were significantly reduced, and there was no decline in kidney function, which has been noted as a systemic adverse effect of ROCK inhibitor. Furthermore, VA-coupled liposomal ROCK inhibitor improved survival rates in rats with liver fibrosis.

CONCLUSION

Vitamin A-coupled liposomal ROCK inhibitor efficiently suppressed liver fibrosis without causing systemic adverse effects.

Rap1 regulates hepatic stellate cell migration through the modulation of RhoA activity in response to TGF‑β1

Although the migration of hepatic stellate cells (HSCs) is important for hepatic fibrosis, the regulation of this migration is poorly understood. Notably, transforming growth factor (TGF)‑β1 induces monocyte migration to sites of injury or inflammation during the early phase, but inhibits cell migration during the late phase. In the present study, the role of transforming protein RhoA signaling in TGF‑β1‑induced HSC migration was investigated. TGF‑β1 was found to increase the protein and mRNA levels of smooth muscle actin and collagen type I in HSC‑T6 cells. The level of RhoA‑GTP in TGF‑β1‑stimulated cells was significantly higher than that in control cells. Furthermore, the phosphorylation of cofilin and formation of filamentous actin (F‑actin) were more marked in TGF‑β1‑stimulated cells than in control cells. Additionally, TGF‑β1 induced the activation of nuclear factor‑κB, and the expression of extracellular matrix proteins and several cytokines in HSC‑T6 cells. The active form of Rap1 (Rap1 V12) suppressed RhoA‑GTP levels, whereas the dominant‑negative form of Rap1 (Rap1 N17) augmented RhoA‑GTP levels. Therefore, the data confirmed that Rap1 regulated the activation of RhoA in TGF‑β1‑stimulated HSC‑T6 cells. These findings suggest that TGF‑β1 regulates Rap1, resulting in the suppression of RhoA, activation of and formation of F‑actin during the migration of HSCs.

The antifibrotic potential of a sustained release formulation of a PDGFβ-receptor targeted rho kinase inhibitor

Rho kinase activity in hepatic stellate cells (HSCs) is associated with activation, transformation and contraction of these cells, leading to extracellular matrix production and portal hypertension in liver cirrhosis. Inhibition of rho kinase activity can reduce these activities, but may also lead to side effects, for instance systemic hypotension. This can be circumvented by liver-specific delivery of a rho kinase inhibitor to effector cells. Therefore, we targeted the rho kinase inhibitor Y27632 to the key pathogenic cells in liver fibrosis, i.e. myofibroblasts including activated HSCs that highly express the PDGFβ-receptor, using the drug carrier pPB-MSA. This carrier consists of mouse serum albumin (MSA) covalently coupled to several PDGFβR-recognizing moieties (pPB). We aimed to create a prolonged release system of such a targeted construct, by encapsulating pPB-MSA-Y27632 in biodegradable polymeric microspheres, thereby reducing short-lasting peak concentrations and the need for frequent administrations. Firstly, we confirmed the vasodilating potency of PDGFβ-receptor targeted Y27632 in vitro in a contraction assay using HSCs seeded on a collagen gel. We subsequently demonstrated the in vivo antifibrotic efficacy of pPB-MSA-Y27632-loaded microspheres in the Mdr2-/- mouse model of progressive biliary liver fibrosis. A single subcutaneous microsphere administration followed by organ harvest one week later clearly attenuated liver fibrosis progression and significantly suppressed the expression of fibrosis related genes, such as several collagens, profibrotic cytokines and matrix metalloproteinases. In conclusion, we demonstrate that polymeric microspheres are suitable as drug delivery system for the sustained systemic delivery of targeted protein constructs with antifibrotic potential, such as pPB-MSA-Y27632. This formulation appears suitable for the sustained treatment of liver fibrosis and possibly other chronic diseases.

Rho-kinase inhibitor coupled to peptide-modified albumin carrier reduces portal pressure and increases renal perfusion in cirrhotic rats

Rho-kinase (ROCK) activation in hepatic stellate cells (HSC) is a key mechanism promoting liver fibrosis and portal hypertension (PTH). Specific delivery of ROCK-inhibitor Y-27632 (Y27) to HSC targeting mannose-6-phosphate-receptors reduces portal pressure and fibrogenesis. In decompensated cirrhosis, presence of ascites is associated with reduced renal perfusion. Since in cirrhosis, platelet-derived growth factor receptor beta (PDGFRβ) is upregulated in the liver as well as the kidney, this study coupled Y27 to human serum albumin (HSA) substituted with PDGFRβ-recognizing peptides (pPB), and investigated its effect on PTH in cirrhotic rats. In vitro collagen contraction assays tested biological activity on LX2 cells. Hemodynamics were analyzed in BDL and CCl₄ cirrhotic rats 3 h, 6 h and 24 h after i.v. administration of Y27pPBHSA (0.5/1 mg/kg b.w). Phosphorylation of moesin and myosin light chain (MLC) assessed ROCK activity in liver, femoral muscle, mesenteric artery, kidney and heart. Three Y27 molecules were coupled to pPBHSA as confirmed by HPLC/MS, which was sufficient to relax LX2 cells. In vivo, Y27pPBHSA-treated rats exhibited lower portal pressure, hepatic vascular resistance without effect on systemic vascular resistance, but a tendency towards lower cardiac output compared to non-treated cirrhotic rats. Y27pPBHSA reduced intrahepatic resistance by reduction of phosphorylation of moesin and MLC in Y27pPBHSA-treated cirrhotic rats. Y27pPBHSA was found in the liver of rats up to 6 hours after its injection, in the HSC demonstrated by double-immunostainings. Interestingly, Y27pPBHSA increased renal arterial flow over time combined with an antifibrotic effect as shown by decreased renal acta2 and col1a1 mRNA expression. Therefore, targeting the ROCK inhibitor Y27 to PDGFRβ decreases portal pressure with potential beneficial effects in the kidney. This unique approach should be tested in human cirrhosis.

Hypoxia‑inducible factor 1α and ROCK1 regulate proliferation and collagen synthesis in hepatic stellate cells under hypoxia

Hypoxia serves a critical role in the pathogenesis of liver fibrosis. Hypoxia‑inducible factor 1α (HIF1‑α) is induced when cells are exposed to low O2 concentrations. Recently, it has been suggested that Rho‑associated coiled‑coil‑forming kinase 1 (ROCK1) may be an important HIF1‑α regulator. In the present study, it was analyzed whether crosstalk between HIF1‑α and ROCK1 regulates cell proliferation and collagen synthesis in hepatic stellate cells (HSCs) under hypoxic conditions. For this purpose, a rat hepatic HSC line (HSC‑T6) was cultured under hypoxic or normoxic conditions, and HIF1‑α and ROCK1 expression was measured at different time points. Additionally, HSC‑T6 cells were transfected with HIF1‑α small interfering RNA (siHIF1‑α), and measured protein expression and mRNA transcript levels of α‑smooth muscle actin, collagen 1A1 and ROCK1. Collagen 3A1 secretion was also measured by ELISA. Cell proliferation was assessed by the MTT assay under these hypoxic conditions. The results indicated that a specific ROCK inhibitor, Y‑27632, increased HIF1‑α and ROCK1 expression over time in HSC‑T6 cells in response to hypoxia. In addition, knockdown of HIF1‑α inhibited HSC‑T6 proliferation, suppressed collagen 1A1 expression, decreased collagen 3A1 secretion and attenuated ROCK1 expression. Notably, ROCK1 inhibition caused HSC‑T6 quiescence, suppressed collagen secretion and downregulated HIF1‑α expression. Collectively, these findings indicated that the interplay between HIF1‑α and ROCK1 may be a critical factor that regulates cell proliferation and collagen synthesis in rat HSCs under hypoxia.

Syndecan-2 Attenuates Radiation-induced Pulmonary Fibrosis and Inhibits Fibroblast Activation by Regulating PI3K/Akt/ROCK Pathway via CD148

Radiation-induced pulmonary fibrosis is a severe complication of patients treated with thoracic irradiation. We have previously shown that syndecan-2 reduces fibrosis by exerting alveolar epithelial cytoprotective effects. Here, we investigate whether syndecan-2 attenuates radiation-induced pulmonary fibrosis by inhibiting fibroblast activation. C57BL/6 wild-type mice and transgenic mice that overexpress human syndecan-2 in alveolar macrophages were exposed to 14 Gy whole-thoracic radiation. At 24 weeks after irradiation, lungs were collected for histological, protein, and mRNA evaluation of pulmonary fibrosis, profibrotic gene expression, and α-smooth muscle actin (α-SMA) expression. Mouse lung fibroblasts were activated with transforming growth factor (TGF)-β1 in the presence or absence of syndecan-2. Cell proliferation, migration, and gel contraction were assessed at different time points. Irradiation resulted in significantly increased mortality and pulmonary fibrosis in wild-type mice that was associated with elevated lung expression of TGF-β1 downstream target genes and cell death compared with irradiated syndecan-2 transgenic mice. In mouse lung fibroblasts, syndecan-2 inhibited α-SMA expression, cell contraction, proliferation, and migration induced by TGF-β1. Syndecan-2 attenuated phosphoinositide 3-kinase/serine/threonine kinase/Rho-associated coiled-coil kinase signaling and serum response factor binding to the α-SMA promoter. Syndecan-2 attenuates pulmonary fibrosis in mice exposed to radiation and inhibits TGF-β1-induced fibroblast-myofibroblast differentiation, migration, and proliferation by down-regulating phosphoinositide 3-kinase/serine/threonine kinase/Rho-associated coiled-coil kinase signaling and blocking serum response factor binding to the α-SMA promoter via CD148. These findings suggest that syndecan-2 has potential as an antifibrotic therapy in radiation-induced lung fibrosis.

Drugs and Targets in Fibrosis

Fibrosis contributes to the development of many diseases and many target molecules are involved in fibrosis. Currently, the majority of fibrosis treatment strategies are limited to specific diseases or organs. However, accumulating evidence demonstrates great similarities among fibroproliferative diseases, and more and more drugs are proved to be effective anti-fibrotic therapies across different diseases and organs. Here we comprehensively review the current knowledge on the pathological mechanisms of fibrosis, and divide factors mediating fibrosis progression into extracellular and intracellular groups. Furthermore, we systematically summarize both single and multiple component drugs that target fibrosis. Future directions of fibrosis drug discovery are also proposed.

Myofibroblast repair mechanisms post-inflammatory response: a fibrotic perspective

INTRODUCTION

Fibrosis is a complex chronic disease characterized by a persistent repair response. Its pathogenesis is poorly understood but it is typically the result of chronic inflammation and maintained with the required activity of transforming growth factor-β (TGFβ) and extracellular matrix (ECM) tension, both of which drive fibroblasts to transition into a myofibroblast phenotype.

FINDINGS

As the effector cells of repair, myofibroblasts migrate to the site of injury to deposit excessive amounts of matrix proteins and stimulate high levels of contraction. Myofibroblast activity is a decisive factor in whether a tissue is properly repaired by controlled wound healing or rendered fibrotic by deregulated repair. Extensive studies have documented the various contributing factors to an abrogated repair response. Though these fibrotic factors are known, very little is understood about the opposing antifibrotic molecules that assist in a successful repair, such as prostaglandin E2 (PGE₂) and ECM retraction. The following review will discuss the general development of fibrosis through the transformation of myofibroblasts, focusing primarily on the prominent profibrotic pathways of TGFβ and ECM tension and antifibrotic pathways of PGE₂ and ECM retraction.

CONCLUSIONS

The idea is to understand the ways in which the cell, after an injury and inflammatory response, normally controls its repair mechanisms through its homeostatic regulators so as to mimic them therapeutically to control abnormal pathways.

Physiological ranges of matrix rigidity modulate primary mouse hepatocyte function in part through hepatocyte nuclear factor 4 alpha

Matrix rigidity has important effects on cell behavior and is increased during liver fibrosis; however, its effect on primary hepatocyte function is unknown. We hypothesized that increased matrix rigidity in fibrotic livers would activate mechanotransduction in hepatocytes and lead to inhibition of liver-specific functions. To determine the physiologically relevant ranges of matrix stiffness at the cellular level, we performed detailed atomic force microscopy analysis across liver lobules from normal and fibrotic livers. We determined that normal liver matrix stiffness was around 150 Pa and increased to 1-6 kPa in areas near fibrillar collagen deposition in fibrotic livers. In vitro culture of primary hepatocytes on collagen matrix of tunable rigidity demonstrated that fibrotic levels of matrix stiffness had profound effects on cytoskeletal tension and significantly inhibited hepatocyte-specific functions. Normal liver stiffness maintained functional gene regulation by hepatocyte nuclear factor 4 alpha (HNF4α), whereas fibrotic matrix stiffness inhibited the HNF4α transcriptional network. Fibrotic levels of matrix stiffness activated mechanotransduction in primary hepatocytes through focal adhesion kinase. In addition, blockade of the Rho/Rho-associated protein kinase pathway rescued HNF4α expression from hepatocytes cultured on stiff matrix.

CONCLUSION

Fibrotic levels of matrix stiffness significantly inhibit hepatocyte-specific functions in part by inhibiting the HNF4α transcriptional network mediated through the Rho/Rho-associated protein kinase pathway. Increased appreciation of the role of matrix rigidity in modulating hepatocyte function will advance our understanding of the mechanisms of hepatocyte dysfunction in liver cirrhosis and spur development of novel treatments for chronic liver disease. (Hepatology 2016;64:261-275).

Rho Kinases and Cardiac Remodeling

Hypertensive cardiac remodeling is characterized by left ventricular hypertrophy and interstitial fibrosis, which can lead to heart failure with preserved ejection fraction. The Rho-associated coiled-coil containing kinases (ROCKs) are members of the serine/threonine protein kinase family, which mediates the downstream effects of the small GTP-binding protein RhoA. There are 2 isoforms: ROCK1 and ROCK2. They have different functions in different types of cells and tissues. There is growing evidence that ROCKs contribute to the development of cardiovascular diseases, including cardiac fibrosis, hypertrophy, and subsequent heart failure. Recent experimental studies using ROCK inhibitors, such as fasudil, have shown the benefits of ROCK inhibition in cardiac remodeling. Mice lacking each ROCK isoform also exhibit reduced myocardial fibrosis in a variety of pathological models of cardiac remodeling. Indeed, clinical studies with fasudil have suggested that ROCKs could be potential novel therapeutic targets for cardiovascular diseases. In this review, we summarize the current understanding of the roles of ROCKs in the development of cardiac fibrosis and hypertrophy and discuss their therapeutic potential for deleterious cardiac remodeling. (Circ J 2016; 80: 1491-1498).

Opportunity and challenge for diagnosis and treatment of hepatic fibrosis

Hepatic fibrosis is a wound-healing response to all kinds of chronic liver injuries, which is characterized by extracellular matrix remodeling. Hepatic fibrosis ultimately leads to cirrhosis and even hepatic cell carcinoma. Thus, diagnosis and treatment of hepatic fibrosis are important for the management of chronic liver diseases. Recently, the study of hepatic fibrogenesis has witnessed tremendous progress, with many new diagnostic and therapeutic options emerging. This article mainly discusses the opportunity and challenge for diagnosis and treatment of hepatic fibrosis.

Dissecting fibrosis: therapeutic insights from the small-molecule toolbox

Fibrosis, which leads to progressive loss of tissue function and eventual organ failure, has been estimated to contribute to ~45% of deaths in the developed world, and so new therapeutics to modulate fibrosis are urgently needed. Major advances in our understanding of the mechanisms underlying pathological fibrosis are supporting the search for such therapeutics, and the recent approval of two anti-fibrotic drugs for idiopathic pulmonary fibrosis has demonstrated the tractability of this area for drug discovery. This Review examines the pharmacology and structural information for small molecules being evaluated for lung, liver, kidney and skin fibrosis. In particular, we discuss the insights gained from the use of these pharmacological tools, and how these entities can inform, and probe, emerging insights into disease mechanisms, including the potential for future drug combinations.

Sodium Ferulate Reduces Portal Pressure Through Inhibition of RhoA/Rho-Kinase and Activation of Endothelial Nitric Oxide Synthase in Cirrhotic Rats

BACKGROUND AND AIMS

Recent studies have demonstrated that increased RhoA/Rho-kinase activity and reduced nitric oxide activity have the necessary machinery to induce cirrhosis. However, it is unclear whether this regulates the functions of hepatic stellate cells (HSCs). In this study, we used sodium ferulate (SF) in a cirrhotic rat model and examined its roles in regulating RhoA activation in HSCs and the subsequent effects on contraction of HSCs.

METHODS

Bile duct ligation method was used to induce cirrhosis in rats. Intrahepatic resistance was investigated in in situ perfused livers. Hepatic RhoA, Rho-kinase and eNOS expressions were studied by RT-PCR and Western blot. RhoA pull-down assay and collagen gel contraction assay of HSCs were performed by incubation with SF in the absence or presence of GGPP.

RESULTS

We showed that in cirrhotic liver, SF can efficiently affect RhoA activation via lowering the synthesis of GGPP in HSCs. These actions effectively reduced basal intrahepatic resistance in cirrhotic rats. Our study further suggested that SF effectively decreased Rho-kinase activity and increased activity of eNOS at both the mRNA and protein levels. SF treatment of HSCs reduced RhoA GTP without affecting the total RhoA protein level, and GGPP had the ability to block SF-induced protein expression. Furthermore, SF inhibited the contraction of activated HSCs and this inhibition was efficiently reversed by addition of GGPP.

CONCLUSIONS

SF inhibits hepatic RhoA/Rho-kinase signaling and activates the NO/PKG pathway in cirrhotic rats. This may serve as a mechanism for reducing the contraction of activated HSCs upon SF treatment.

The Rho kinases: critical mediators of multiple profibrotic processes and rational targets for new therapies for pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is characterized by progressive lung scarring, short median survival, and limited therapeutic options, creating great need for new pharmacologic therapies. IPF is thought to result from repetitive environmental injury to the lung epithelium, in the context of aberrant host wound healing responses. Tissue responses to injury fundamentally involve reorganization of the actin cytoskeleton of participating cells, including epithelial cells, fibroblasts, endothelial cells, and macrophages. Actin filament assembly and actomyosin contraction are directed by the Rho-associated coiled-coil forming protein kinase (ROCK) family of serine/threonine kinases (ROCK1 and ROCK2). As would therefore be expected, lung ROCK activation has been demonstrated in humans with IPF and in animal models of this disease. ROCK inhibitors can prevent fibrosis in these models, and more importantly, induce the regression of already established fibrosis. Here we review ROCK structure and function, upstream activators and downstream targets of ROCKs in pulmonary fibrosis, contributions of ROCKs to profibrotic cellular responses to lung injury, ROCK inhibitors and their efficacy in animal models of pulmonary fibrosis, and potential toxicities of ROCK inhibitors in humans, as well as involvement of ROCKs in fibrosis in other organs. As we discuss, ROCK activation is required for multiple profibrotic responses, in the lung and multiple other organs, suggesting ROCK participation in fundamental pathways that contribute to the pathogenesis of a broad array of fibrotic diseases. Multiple lines of evidence therefore indicate that ROCK inhibition has great potential to be a powerful therapeutic tool in the treatment of fibrosis, both in the lung and beyond.

Quantitative phosphoproteomic analysis of signaling downstream of the prostaglandin e2/g-protein coupled receptor in human synovial fibroblasts: potential antifibrotic networks

The Prostaglandin E2 (PGE2) signaling mechanism within fibroblasts is of growing interest as it has been shown to prevent numerous fibrotic features of fibroblast activation with limited evidence of downstream pathways. To understand the mechanisms of fibroblasts producing tremendous amounts of PGE2 with autocrine effects, we apply a strategy of combining a wide-screening of PGE2-induced kinases with quantitative phosphoproteomics. Our large-scale proteomic approach identified a PKA signal transmitted through phosphorylation of its substrates harboring the R(R/X)X(S*/T*) motif. We documented 115 substrates, of which 72 had 89 sites with a 2.5-fold phosphorylation difference in PGE2-treated cells than in untreated cells, where approximately half of such sites were defined as being novel. They were compiled by networking software to focus on highlighted activities and to associate them with a functional readout of fibroblasts. The substrates were associated with a variety of cellular functions including cytoskeletal structures (migration/motility), regulators of G-protein coupled receptor function, protein kinases, and transcriptional/translational regulators. For the first time, we extended the PGE2 pathway into an elaborate network of interconnecting phosphoproteins, providing vital information to a once restricted signalosome. These data provide new insights into eicosanoid-initiated cell signaling with regards to the regulation of fibroblast activation and the identification of new targets for evidenced-based pharmacotherapy against fibrosis.

Rho/Rock cross-talks with transforming growth factor-β/Smad pathway participates in lung fibroblast-myofibroblast differentiation

The differentiation of fibroblasts, which are promoted by transforming growth factor-β (TGF-β)/Smad, is involved in the process of pulmonary fibrosis. The Rho/Rho-associated coiled-coil-forming protein kinase (Rock) pathway may regulate the fibroblast differentiation and myofibroblast expression of α-smooth muscle actin (α-SMA), however, the mechanism is not clear. The aim of the present study was to evaluate the role of Rho/Rock and TGF-β/Smad in TGF-β1-induced lung fibroblasts differentiation. Human embryonic lung fibroblasts were stimulated by TGF-β1, Y-27632 (inhibitor of Rho/Rock signaling) and staurosporine (inhibitor of TGF-β/Smad signaling). The α-SMA expression, cell cycle progression, content of the extracellular matrix (ECM) in cell culture supernatants and the expression of RhoA, RhoC, Rock1 and Smad2 were detected. The results demonstrated that α-SMA-positive cells significantly increased following TGF-β1 stimulation. Rho/Rock and TGF-β/Smad inhibitors suppressed TGF-β1-induced lung fibroblast differentiation. The inhibitors increased G₀/G₁ and decreased S and G₂/M percentages. The concentrations of the ECM proteins in the supernatant were significantly increased by TGF-β1 stimulation, whereas they were decreased by inhibitor stimulation. RhoA, RhoC, Rock1, Smad2 and tissue inhibitor of metalloproteinase-1 were upregulated by TGF-β1 stimulation. The Rho/Rock inhibitor downregulated Smad2 expression and the TGF-β/Smad inhibitor downregulated RhoA, RhoC and Rock1 expression. Therefore, the Rho/Rock pathway and Smad signaling were involved in the process of lung fibroblasts transformation, induced by TGF-β1, to myofibroblasts. The two pathways may undergo cross-talk in the lung fibroblasts differentiation in vitro.

Therapeutic effect of collagenase Ⅱ against rat liver cirrhosis

AIM: To explore the therapeutic effect of an adenovirus-HBV chimeric vector expressing collagenase Ⅱ against cirrhosis in a rat model.

METHODS: Rat liver cirrhosis was induced with 0.03% thioacetamide in drinking water for 16 wk. Ad-CH-tMMP8 and Ad-C-MMP8 were constructed using an adenovirus shuttle plasmid and a HBV chimeric vector expressing truncated and full-length collagenase Ⅱ gene. Ad-CH-RFP2 expressing red fluorescent protein was used as a negative control. Liver cirrhosis rats were injected with the three plasmids through the tail vein.

RESULTS: Compared with the model group and negative control group, fibrosis was dramatically attenuated four weeks after the infection. HE staining and picric acid-Sirius red staining showed that hepatocyte steatosis, necrosis and inflammation were significantly milder in the treatment group, along with hepatocyte proliferation, recovery of hepatic lobule structure, and diminished content of HYP (28.97 µg/g ± 2.36 µg/g vs 17.04 µg/g ± 0.61 µg/g, 17.62 µg/g ± 1.30 µg/g, P < 0.05), whereas the fibrosis in Ad-CH-RFP2-treated rats persisted.

CONCLUSION: Adenovirus-HBV chimeric vector expressing collagenase Ⅱ effectively reduces the degree of liver fibrosis in rats.

Recent insights into the molecular pathophysiology of lipid droplet formation in hepatocytes

Triacyglycerols are a major energy reserve of the body and are normally stored in adipose tissue as lipid droplets (LDs). The liver, however, stores energy as glycogen and digested triglycerides in the form of fatty acids. In stressed condition such as obesity, imbalanced nutrition and drug induced liver injury hepatocytes accumulate excess lipids in the form of LDs whose prolonged storage leads to disease conditions most notably non-alcoholic fatty liver disease (NAFLD). Fatty liver disease has become a major health burden with more than 90% of obese, nearly 70% of overweight and about 25% of normal weight patients being affected. Notably, research in recent years has shown LD as highly dynamic organelles for maintaining lipid homeostasis through fat storage, protein sorting and other molecular events studied in adipocytes and other cells of living organisms. This review focuses on the molecular events of LD formation in hepatocytes and the importance of cross talk between different cell types and their signalling in NAFLD as to provide a perspective on molecular mechanisms as well as possibilities for different therapeutic intervention strategies.

Tolvaptan, an orally active non-peptide arginine vasopressin V2 receptor antagonist, reduces ascites in rats with chronic liver injury

AIM

This is a non-clinical, proof of concept study, showing that tolvaptan has efficacy in reducing ascites in chronic liver injury, using a rat model induced by repeated dimethylnitrosamine (DMNA) injection.

METHODS

A rat model of chronic liver injury was induced by 10 mg/kg of repeated i.p. injection with DMNA for 6-9 weeks. Tolvaptan was administrated to rats that showed obvious and stable ascites, and abdominal circumference was evaluated as a surrogate marker of ascites volume. Rats were placed in metabolic cages with free access to food and water to collect urine over a 24-h period.

RESULTS

Oral tolvaptan (1 and 3 mg/kg) promoted a remarkable diuretic effect, decreasing bodyweight and abdominal circumference in a dose-dependent manner. Plasma sodium concentration was increased by tolvaptan due to the large amount of free-water excretion following tolvaptan administration.

CONCLUSION

Tolvaptan had therapeutic efficacy in the reduction of ascites in rats with chronic liver injury. These results are consistent with the clinical data showing tolvaptan has therapeutic implications in the reduction of ascites in patients with decompensated cirrhosis.

Antagonism of sphingosine 1-phosphate receptor 2 causes a selective reduction of portal vein pressure in bile duct-ligated rodents

Sinusoidal vasoconstriction, in which hepatic stellate cells operate as contractile machinery, has been suggested to play a pivotal role in the pathophysiology of portal hypertension. We investigated whether sphingosine 1-phosphate (S1P) stimulates contractility of those cells and enhances portal vein pressure in isolated perfused rat livers with Rho activation by way of S1P receptor 2 (S1P(2) ). Rho and its effector, Rho kinase, reportedly contribute to the pathophysiology of portal hypertension. Thus, a potential effect of S1P(2) antagonism on portal hypertension was examined. Intravenous infusion of the S1P(2) antagonist, JTE-013, at 1 mg/kg body weight reduced portal vein pressure by 24% without affecting mean arterial pressure in cirrhotic rats induced by bile duct ligation at 4 weeks after the operation, whereas the same amount of S1P(2) antagonist did not alter portal vein pressure and mean arterial pressure in control sham-operated rats. Rho kinase activity in the livers was enhanced in bile duct-ligated rats compared to sham-operated rats, and this enhanced Rho kinase activity in bile duct-ligated livers was reduced after infusion of the S1P(2) antagonist. S1P(2) messenger RNA (mRNA) expression, but not S1P(1) or S1P(3) , was increased in bile duct-ligated livers of rats and mice and also in culture-activated rat hepatic stellate cells. S1P(2) expression, determined in S1P 2LacZ/+ mice, was highly increased in hepatic stellate cells of bile duct-ligated livers. Furthermore, the increase of Rho kinase activity in bile duct-ligated livers was observed as early as 7 days after the operation in wildtype mice, but was less in S1P 2-/- mice.

CONCLUSION

S1P may play an important role in the pathophysiology of portal hypertension with Rho kinase activation by way of S1P(2) . The S1P(2) antagonist merits consideration as a novel therapeutic agent for portal hypertension.

Fibroproliferative disorders and their mechanobiology

Benign and malignant fibroproliferative disorders (FPDs) include idiopathic pulmonary fibrosis, hepatic cirrhosis, myelofibrosis, systemic sclerosis, Dupuytren's contracture, hypertrophic scars, and keloids. They are characterized by excessive connective tissue accumulation and slow but continuous tissue contraction that lead to progressive deterioration in the normal structure and function of affected organs. In recent years, research in diverse fields has increasingly highlighted the potential role of mechanobiology in the molecular mechanisms of fibroproliferation. Mechanobiology, the heart of which is mechanotransduction, is the process whereby cells sense mechanical forces and transduce them, thereby changing the intracellular biochemistry and gene expression. Understanding mechanosignaling may provide new insights into the convergent roles played by interrelated molecules and overlapping signaling pathways during the inflammatory, proliferative, and fibrotic cellular activities that are the hallmarks of fibroproliferation. The main cellular players in FPDs are fibroblasts and myofibroblasts. Consequently, this article discusses integrins and the roles they play in cellular-extracellular matrix interactions. Also described are the signaling pathways that are known to participate in mechanosignaling: these include the transforming growth factor-β/Smad, mitogen-activated protein kinase, RhoA/ROCK, Wnt/β-catenin, and tumor necrosis factor-α/nuclear factor kappa-light-chain-enhancer of activated B cells pathways. Also outlined is the progress in our understanding of the cellular-extracellular matrix interactions that are associated with fibroproliferative mechanosignaling through matricellular proteins. The tensegrity and tensional homeostasis models are also discussed. A better understanding of the mechanosignaling pathways in the FPD microenvironment will almost certainly lead to the development of novel interventions that can prevent, reduce, or even reverse FPD formation and/or progression.

Wound contraction is attenuated by fasudil inhibition of Rho-associated kinase

BACKGROUND

Dermal scarring and scar contracture result in restriction of movement. There are no effective drugs to prevent scarring. RhoA and Rho-associated kinase have emerged as regulators of fibrosis and contracture. Fasudil, a Rho-associated kinase inhibitor, has been demonstrated to have antifibrotic effects in models of liver, renal, and cardiac fibrosis. The role of fasudil in preventing dermal scarring and contractures has not been studied. The authors used a rat model of dermal wound healing to assess the effects of fasudil with regard to the prevention of scarring.

METHODS

Human scar tissue and surrounding normal skin were immunostained for RhoA and Rho-associated kinase. Full-thickness wounds were created on Wistar-Han rats, and fasudil (30 mg/kg/day) or saline was continuously delivered subcutaneously. Wound contraction was measured by gravitational planimetry. After 21 days, tissue was harvested for Masson's trichrome, hematoxylin and eosin, Ki-67, and CD31 staining. Fibroblast-populated collagen lattices were used to assess the mechanistic effects of fasudil on contractility. Myofibroblast formation was assessed in the presence of fasudil.

RESULTS

Human scar tissue in the remodeling phase of repair showed increased expression of RhoA and Rho-associated kinase in scar tissue compared with surrounding normal tissue. Fasudil inhibited wound contraction as compared with controls. Hematoxylin and eosin and Masson's trichrome were similar between groups. Fasudil did not alter angiogenesis or proliferation. Fasudil inhibited fibroblast contractility and myofibroblast formation in vitro.

CONCLUSIONS

There is growing evidence that the RhoA/Rho-associated kinase pathway plays an important role in wound healing and scar contracture. The authors present data showing that inhibition of Rho-associated kinase hinders fibroblast contractility and may be beneficial in preventing scar contracture.

Specific delivery of kinase inhibitors in nonmalignant and malignant diseases

INTRODUCTION

Kinase inhibitors have been hailed as a breakthrough in the treatment of cancer. Extensive research is now being devoted to the development of kinase inhibitors as a treatment for many nonmalignant diseases. However, the use of kinase inhibitors in both malignant and nonmalignant diseases is also associated with side effects and the development of resistance. It may be worthwhile to explore whether cell-specific delivery of kinase inhibitors improves therapeutic efficacy and reduces side effects.

AREAS COVERED

This review aims to provide an overview of the preclinical studies performed to examine the specific targeting of kinase inhibitors in vitro and in vivo. It gives an introduction to kinase signaling pathways induced during disease, along with the possible problems associated with their inhibition. It also discusses the studies on specific delivery and shows that altering the specificity of kinase inhibitors by targeting methods improves their effectivity and safety.

EXPERT OPINION

Compared with the delivery of cytotoxic compounds, the specific delivery of kinase inhibitors has not yet been studied extensively. The studies discussed in this review provide an insight into methods used to target kinase inhibitors to different organs. The targeting of different kinase inhibitors has improved their therapeutic possibilities, but many questions still remain to be studied.

Amelioration of albuminuria in ROCK1 knockout mice with streptozotocin-induced diabetic kidney disease

BACKGROUND

Although blockade of Rho kinase with pharmacologic inhibitors ameliorates renal fibrosis and diabetic kidney disease (DKD), the underlined mechanisms remain largely unclear. The present study tested the hypothesis that ROCK1 may regulate the early development of albuminuria via the megalin/cubilin-dependent mechanism.

METHODS

A DKD model was induced in ROCK1 knockout and wild-type mice by streptozotocin (STZ). The effect of deleted ROCK1 on urinary albumin excretion and the expression of megalin/cubilin were examined. In addition, the effect of blocking ROCK activities with an inhibitor (Y-27632) on tubular albumin reabsorption was tested in a normal rat tubular epithelial cell line (NRK52E) under high-glucose conditions. Expression of transforming growth factor (TGF)-β1, interleukin-1β and collagen-1 was also been examined.

RESULTS

Urinary albumin excretion was significantly increased in ROCK1 WT mice at 8 weeks after STZ injection. In contrast, mice lacking ROCK1 gene were protected against the development of albuminuria. This was associated with the protection against the loss of megalin/cubilin and an increase in TGF-β(1), IL-1β, and fibrosis in the kidney. In vitro, we also found that blockade of Rho kinase with inhibitor Y-27632 prevented high-glucose-induced loss of megalin expression and an increase of TGF-β(1), thereby increasing the absorption rate of FITC-labeled albumin by tubular epithelial cells.

CONCLUSION

ROCK1 may play a role in the development of albuminuria in DKD by downregulating the endocytosis receptors complex - megalin/cubilin.

Increased liver uptake and reduced hepatic stellate cell activation with a cell-specific conjugate of the Rho-kinase inhibitor Y27632

Purpose

Rho-kinase regulates activation of hepatic stellate cells (HSC) during liver fibrosis, but the ubiquitous presence of this kinase may hinder examination of its exact role and the therapeutic use of inhibitors. We therefore coupled the Rho-kinase inhibitor Y27632 to a drug carrier that binds the mannose-6-phosphate insulin-like growth factor II (M6P/IGFII)-receptor which is upregulated on activated HSC.

Methods

Y27632 was coupled to mannose-6-phosphate human serum albumin (M6PHSA), and in vitro experiments were performed on primary rat HSC. Biodistribution and effect studies were performed in an acute CCl₄ model in mice.

Results

Y27-conjugate remained stable in serum, while drug was efficiently released in liver homogenates. Receptor-blocking studies revealed that it was specifically taken up through the M6P/IGFII-receptor on fibroblasts, and it inhibited expression of fibrotic markers in activated HSC. In vivo, liver drug levels were significantly higher after injection of Y27-conjugate as compared to Y27632, and the conjugate accumulated specifically in HSC. After acute CCl₄-induced liver injury, Y27-conjugate reduced the local activation of HSC, whereas an equimolar dose of free drug did not.

Conclusions

We conclude that specific targeting of a Rho-kinase inhibitor to HSC leads to enhanced accumulation of the drug in HSC, reducing early fibrogenesis in the liver.

Electronic Supplementary Material

The online version of this article (doi:10.1007/s11095-011-0430-9) contains supplementary material, which is available to authorized users.

Prevention of in vitro hepatic stellate cells activation by the adenosine derivative compound IFC305

We have previously shown that adenosine and the aspartate salt of adenosine (IFC305) reverse pre-established CCl(4)-induced cirrhosis in rats. However, their molecular mechanism of action is not clearly understood. Hepatic stellate cells (HSC) play a pivotal role in liver fibrogenesis leading to cirrhosis, mainly through their activation, changing from a quiescent adipogenic state to a proliferative myofibrogenic condition. Therefore, we decided to investigate the effect of IFC305 on primary cultured rat HSC. Our results reveal that this compound suppressed the activation of HSC, as demonstrated by the maintenance of a quiescent cell morphology, including lipid droplets content, inhibition of α-smooth muscle actin (α-SMA) and collagen α1(I) expression, and up-regulation of MMP-13, Smad7, and PPARγ expression, three key antifibrogenic genes. Furthermore, IFC305 was able to repress the platelet-derived growth factor (PDGF)-induced proliferation of HSC. This inhibition was independent of adenosine receptors stimulation; instead, IFC305 was incorporated into cells by adenosine transporters and converted to AMP by adenosine kinase. On the other hand, addition of pyrimidine ribonucleoside as uridine reversed the suppressive effect of IFC305 on the proliferation and activation of HSC, suggesting that intracellular pyrimidine starvation would be involved in the molecular mechanism of action of IFC305. In conclusion, IFC305 inhibits HSC activation and maintains their quiescence in vitro; these results could explain in part the antifibrotic liver beneficial effect previously described for this compound on the animal model.

Dietary olive oil prevents carbon tetrachloride-induced hepatic fibrosis in mice

AIM

The specific purpose of this study was to investigate the effects of dietary olive oil on hepatic fibrosis induced by chronic administration of carbon tetrachloride (CCl(4)) in the mouse. In addition, the effects of oleic acid, a major component of olive oil, on activation of hepatic stellate cells (HSCs) were investigated in vitro.

METHODS

Mice were fed liquid diets containing either corn oil (control, AIN-93) or olive oil (6.25 g/L) throughout experiments. Animals were treated with CCl(4) for 4 weeks intraperitoneally. The mRNA expression of TGF-beta1 and collagen 1alpha2 (col1alpha2) in the liver was assessed by reverse transcriptase-polymerase chain reaction (RT-PCR). The HSCs were isolated from mice, and co-cultured with either oleic acid (100 microM) or linoleic acid (100 microM) for 2 days. The expression of alpha-smooth muscle actin (alpha-SMA) was assessed by immunohistochemistry. In addition, the production of hydroxyproline was determined.

RESULTS

Serum alanine aminotransferase levels and the mRNA expression of TGF-beta and collalpha2 were significantly reduced by treatment of olive oil. Dietary olive oil blunted the expression of alpha-SMA in the liverand liver injury and hepatic fibrosis were prevented by treatment of olive oil. The number of alpha-SMA positive cells was significantly lower in HSCs co-cultured with oleic acid than in those co-cultured with linoleic acid. Concentration of hydroxyproline in culture medium was significantly lower in cells co-cultured with oleic acid than in the control.

CONCLUSIONS

Dietary olive oil prevents CCl(4)-induced tissue injury and fibrosis in the liver. Since oleic acid inhibited activation of HSCs, oleic acid may play a key role on this mechanism.

Blebbistatin inhibits contraction and accelerates migration in mouse hepatic stellate cells

BACKGROUND AND PURPOSE

Blebbistatin, an inhibitor of myosin-II-specific ATPase, has been used to inhibit contraction of invertebrate and mammalian muscle preparations containing non-muscle myosin. Activated hepatic stellate cells have contractile properties and play an important role in the pathophysiology of liver fibrosis and portal hypertension. Therefore, hepatic stellate cells are considered as therapeutic target cells. In the present study, we studied the effect of blebbistatin during the transition of mouse hepatic stellate cells into contractile myofibroblasts.

EXPERIMENTAL APPROACH

Effects of blebbistatin on cell morphology were evaluated by phase contrast microscopy. Cell stress fibres and focal adhesions were investigated by dual immunofluorescence staining and visualized using fluorescence microscopy. Contractile force generation was examined by silicone wrinkle formation assays and collagen gel contraction assays. Intracellular Ca(2+) release in response to endothelin-1 was measured by using Fluo-4. Cell migration was measured by wound healing experiments.

KEY RESULTS

In culture-activated hepatic stellate cells, blebbistatin was found to change both cell morphology and function. In the presence of blebbistatin, stellate cells became smaller, acquired a dendritic morphology and had less myosin IIA-containing stress fibres and vinculin-containing focal adhesions. Moreover, blebbistatin impaired silicone wrinkle formation, reduced collagen gel contraction and blocked endothelin-1-induced intracellular Ca(2+) release. Finally, it promoted wound-induced cell migration.

CONCLUSIONS AND IMPLICATIONS

By inhibiting myosin II ATPase, blebbistatin has profound effects on the morphology and function of activated hepatic stellate cells. Our data suggest that myosin II could be a therapeutic target in the treatment of liver fibrosis and portal hypertension.

Suppression of hepatitis C virus replication by protein kinase C-related kinase 2 inhibitors that block phosphorylation of viral RNA polymerase

Hepatitis C virus (HCV) infection is a serious threat to human health worldwide. In spite of the continued search for specific and effective anti-HCV therapies, the rapid emergence of drug-resistance variants has been hampering the development of anti-HCV drugs designed to target viral enzymes. Targeting host factors has therefore emerged as an alternative strategy offering the potential to circumvent the ever-present complication of drug resistance. We previously identified protein kinase C-related kinase 2 (PRK2) as a cellular kinase that phosphorylates the HCV RNA-dependent RNA polymerase (RdRp). Here, we report the anti-HCV activity of HA1077, also known as fasudil, and Y27632, which blocks HCV RdRp phosphorylation by suppressing PRK2 activation. Treatment of a Huh7 cell line, stably expressing a genotype 1b HCV subgenomic replicon RNA, with 20 microm each of HA1077 and Y27632 reduced the HCV RNA level by 55% and 30%, respectively. A combination of the inhibitors with 100 IU/mL interferon alpha (IFN-alpha) significantly potentiated the anti-HCV drug activities resulting in approximately a 2-log(10) viral RNA reduction. We also found that IFN-alpha does not activate PRK2 as well as its upstream kinase PDK1 in HCV-replicating cells. Furthermore, treatment of HCV-infected cells with 20 microm each of HA1077 and Y27632 reduced the levels of intracellular viral RNA by 70% and 92%, respectively. Taken together, the results identify PRK2 inhibitors as potential antiviral drugs that act by suppressing HCV replication via inhibition of viral RNA polymerase phosphorylation.

Sorafenib targets dysregulated Rho kinase expression and portal hypertension in rats with secondary biliary cirrhosis

BACKGROUND AND PURPOSE

Extrahepatic vasodilation and increased intrahepatic vascular resistance represent attractive targets for the medical treatment of portal hypertension in liver cirrhosis. In both dysfunctions, dysregulation of the contraction-mediating Rho kinase plays an important role as it contributes to altered vasoconstrictor responsiveness. However, the mechanisms of vascular Rho kinase dysregulation in cirrhosis are insufficiently understood. They possibly involve mitogen-activated protein kinase/extracellular signal-regulated kinase (ERK)-dependent mechanisms in extrahepatic vessels. As the multikinase inhibitor sorafenib inhibits ERK, we tested the effect of sorafenib on haemodynamics and dysregulated vascular Rho kinase in rats with secondary biliary cirrhosis.

EXPERIMENTAL APPROACH

Secondary biliary cirrhosis was induced by bile duct ligation (BDL). Sorafenib was given orally for 1 week (60 mg.kg(-1).d(-1)). Messenger RNA levels were determined by quantitative real time polymerase chain reaction, protein expressions and protein phosphorylation by Western blot analysis. Aortic contractility was studied by myographic measurements, and intrahepatic vasoregulation by using livers perfused in situ. In vivo, haemodynamic parameters were assessed invasively in combination with coloured microspheres.

KEY RESULTS

In BDL rats, treatment with sorafenib decreased portal pressure, paralleled by decreases in hepatic Rho kinase expression and Rho kinase-mediated intrahepatic vascular resistance. In aortas from BDL rats, sorafenib caused up-regulation of Rho kinase and an improvement of aortic contractility. By contrast, mesenteric Rho kinase remained unaffected by sorafenib.

CONCLUSIONS AND IMPLICATIONS

Intrahepatic dysregulation of vascular Rho kinase expression is controlled by sorafenib-sensitive mechanisms in rats with secondary biliary cirrhosis. Thus, sorafenib reduced portal pressure without affecting systemic blood pressure.

Effects of salidroside on expression of ROCK in rats with liver fibrosis

AIM: To observe the effects of salidroside on the expression of ROCK in liver tissue of CCl₄-induced liver fibrosis in rats, and to explore its probable mechanism.

METHODS: Ninety healthy SD rats were randomly divided into 3 groups: control group (n = 10), salidroside group (n = 40) and liver fibrosis group (n = 40). Experimental liver fibrosis was induced by (with the concentration of 300 mL/L soluted in liquid paraffin) subcutaneous injection of CCl₄ (at the dosage of 3 mL/kg, twice per wk, 8 wks). The salidroside was injected into the peritoneal cavity at the dosage of 5 mg/kg, twice per week for 8 weeks. Liver tissues from each group were stained with Masson and HE staining to observe the collagen deposition. Expressions of ROCKⅠand ROCKⅡ in the liver tissue were detected with in situ hybridization (ISH) and immunohistochemistry (IH) respectively. All the figures were scanned with electronic computer, and the data were analyzed with Image-Plus software.

RESULTS: A significant collagen deposition and rearrangement of the parenchyma were noted in liver tissue of CCl₄-treated rats. There were lots of pseudolobule in liver tissue. The semiquantitative histological scores and average area of collagen were significantly increased when compared with control rats (2.1 ± 0.3 vs 3.6 ± 0.8, 74.82 ± 21.51 μm²vs 290.86 ± 89.37 μm², both P < 0.05). Compared with control group, the expressions of ROCKⅠ, ROCKⅡ and ROCKⅠmRNA, ROCKⅡmRNA were decreased significantly in salidroside group (0.203 ± 0.068 vs 0.357 ± 0.182, 0.237 ± 0.056 vs 0.394 ± 0.238; 0.197 ± 0.019 vs 0.394 ± 0.238, 0.185 ± 0.031 vs 0.279 ± 0.112, P < 0.05 or 0.01).

CONCLUSION: The expressions of ROCKⅠand ROCKⅡ in liver tissues are inhibited significantly with salidroside treatment. Salidroside could interfere with the signal transduction of Rho-ROCK pathway and then inhibit liver fibrosis in rats.

Rho GTPases in hepatocellular carcinoma

Rho GTPases are major regulators of signal transduction pathways and play key roles in processes including actin dynamics, cell cycle progression, cell survival and gene expression, whose deregulation may lead to tumorigenesis. A growing number of in vitro and in vivo studies using tumor-derived cell lines, primary tumors and animal cancer models strongly suggest that altered Rho GTPase signaling plays an important role in the initiation as well as in the progression of hepatocellular carcinoma (HCC), one of the deadliest human cancers in the world. These alterations can occur at the level of the GTPases themselves or of one of their regulators or effectors. The participation into the tumorigenic process can occur either through the over-expression of one of these components which presents an oncogenic activity as illustrated with RhoA and C or through the attenuation of the expression of a component presenting tumor suppressor activity as for Cdc42 or the RhoGAP, DLC-1. Consequently, these observations reflect the heterogeneity and the complexity of liver carcinogenesis. Recently, pharmacological approaches targeting Rho GTPase signaling have been used in HCC-derived models with relative success but remain to be validated in more physiologically relevant systems. Therefore, therapeutic approaches targeting Rho GTPase signaling may provide a novel alternative for anti-HCC therapy.

Advances in antifibrotic therapy

Sustained progress in defining the molecular pathophysiology of hepatic fibrosis has led to a comprehensive framework for developing antifibrotic therapies. Indeed, the single greatest limitation in bringing new drugs to the clinical setting is a lack of clarity regarding clinical trial and treatment end points, not a lack of promising agents. A range of treatments, including those developed for other indications, as well as those specifically developed for hepatic fibrosis, are nearing or in clinical trials. Most are focused on attacking features of either hepatic injury and/or activated stellate cells and myofibroblasts, which are the primary sources of extracellular matrix (scar) proteins. Thus, features of injury and stellate cell activation provide a useful template for classifying these emerging agents and point to a new class of therapies for patients with fibrosing liver disease.

Leptin induces phagocytosis of apoptotic bodies by hepatic stellate cells via a Rho guanosine triphosphatase-dependent mechanism

Leptin, a profibrogenic cytokine, plays an important role in the development of non-alcoholic steatohepatitis. Leptin also regulates immune responses, including macrophage phagocytic activity. Stellate cells are key elements in liver fibrogenesis, and previously we have demonstrated that phagocytosis of apoptotic bodies by stellate cells is profibrogenic. To study the effects of leptin on the phagocytic activity of hepatic stellate cells, we exposed both LX-2 cells and primary stellate cells to leptin, and we have observed increased phagocytic activity. In stellate cells isolated from Zucker (fa/fa) rats, the rate of phagocytosis was significantly decreased. To investigate the mechanism by which leptin induces phagocytosis, we focused on the role of Rho-guanosine triphosphate (GTP)-ases. We found that leptin induced the PI3K-dependent activation of Rac1, and that nicotinamide adenine dinucleotide phosphate, reduced form (NADPH) oxidase activation was also implicated in this process. Leptin also induced RhoA activation and translocation to the phagosomes. Expression of the constitutive active Rac1 and RhoA both increased the phagocytic rate, whereas inhibition of the Rho-dependent kinase decreased the phagocytic activity.

CONCLUSION

We describe a novel role of leptin in the fibrogenic process, the induction of phagocytosis of apoptotic bodies by hepatic stellate cells. The data provide strong evidence of a Rho-GTPase-mediated regulation of the cytoskeleton during stellate cell phagocytosis. Leptin-mediated phagocytic activity of stellate cells therefore could be an important mechanism responsible for progression of fibrosis in non-alcoholic steatohepatitis.