Effects of losartan on hepatic expression of nonphagocytic NADPH oxidase and fibrogenic genes in patients with chronic hepatitis C

The role of angiotensin receptor blocker (losartan) on decreasing fibrotic process of corpora cavernosa in priapism model of wistar rats

Background

Priapism induces regulation of Transforming Growth Factor-β1 (TGF-β1) expression and collagen-type-1 deposition. This will replace the normal corpora cavernosa with fibrotic tissue which eventually resulted in erectile dysfunction. It is also known that the fibrosis process of corpora cavernosa is related to Renin-Angiotensin II System (RAS). Angiotensin II receptor blockers (ARB), especially losartan, inhibit the inflammation process and fibrotic tissue formation. This study evaluated the effect of losartan in reducing fibrosis in priapism by evaluating TGF-β1 and collagen-type-1 in cavernous tissue and determined the effect of losartan in preventing fibrosis in priapism model of Wistar rats assessed by the metavir score.

Methods

A total of eighteen male Wistar rats mean were divided into five groups. For the priapism models, we applied negative pressure on the penis to make an artificial erection to mimic the priapism process. The control groups were observed and the treatment groups were orally given losartan 15 mg/kg/day. Corpora cavernosa was harvested for TGF-β1 and collagen-type-1 measurement using an enzyme-linked immunosorbent assay (ELISA). The fibrotic tissue of each rat was then collected and assessed histopathologically with the metavir scoring system.

Results

Penile TGF-β1 concentration in the losartan-treated group was not significantly different on day 10 and day 28 of observation (p10=0,30; p28=0,17). Meanwhile, collagen-type-1 concentration was significantly lower compared to control group (p10=0,002; p28=0,01). There was a significant difference in metavir scores in rats that received losartan and those who did not (p<0,05).

Conclusion

Losartan could suppress the fibrosis process in the priapism model. It could decrease the collagen type 1 deposition during corpora cavernosa tissue regeneration. Based on the metavir score, the group receiving losartan therapy was better than the control group.

Dapagliflozin attenuates renal fibrosis by suppressing angiotensin II/TGFβ signaling in diabetic mice

AIMS

Diabetic nephropathy (DN) complicates diabetes Mellitus and intimately relates to intrarenal renin-angiotensin system (RAS) activity. Dapagliflozin, a selective inhibitor of sodium-glucose cotransporter 2 (SGLT2), has been validated to improve renal outcomes in diabetic patients from clinical research by elusive mechanisms. This study explored the presumption that the eagerness activity of intrarenal RAS in DN generated oxidative stress to promote renal fibrosis, and the process can be interrupted by dapagliflozin.

METHODS

A streptozotocin-induced DN model was established in male C57BL/6J mice. Mice were treated with dapagliflozin or losartan for 14 weeks. Biochemical data, renal fibrosis, oxidative stress, and RAS were measured.

RESULTS

DN mice were characterized by overtly low body weight, high levels of blood glucose, and renal injury. Interrupting SGLT2 and RAS significantly improved renal dysfunction and pathological lesions in DN mice. Consistent with these favorable effects, dapagliflozin revoked the local RAS/oxidative stress and the succeeding transforming growth factor beta (TGFβ) signaling.

CONCLUSIONS

This research clarifies that intrarenal RAS activity triggers renal injury in DN, and dapagliflozin attenuates renal fibrosis by suppressing Angiotensin II/TGFβ signaling. It unravels a novel insight into the role of prevention and treatment of SGLT2 inhibitors to DN.

HIGH-DENSITY LIPOPROTEIN CHOLESTEROL AND SYSTEMIC ARTERIAL HYPERTENSION ARE ASSOCIATED WITH HEPATIC NECROINFLAMMATORY ACTIVITY IN PATIENTS WITH CHRONIC HEPATITIS C

•HDL cholesterol levels <60 mg/dL were independently associated with necroinflammatory activity in chronic hepatitis C (CHC). •CHC patients with hypertension are at an increased risk of developing necroinflammatory activity. •In patients with CHC, liver fibrosis was independently associated with old age, steatosis, and HDL-C <60 mg/dL. •Triglycerides levels ≥150 mg/dL were associated with lobular inflammatory activity in patients with CHC. Background - Approximately 71 million people are chronically infected with hepatitis C virus (HCV) worldwide. A significant number of these individuals will develop liver cirrhosis and/or hepatocellular carcinoma. Beyond the liver, there is a sizeable body of scientific evidence linking cardiovascular disease and chronic hepatitis C (CHC); however, the biological mechanisms behind the concurrence of these conditions have not been completely clarified yet. Objective - To evaluate associations between hepatic histology, clinical comorbidities and lipid profile in patients with CHC. To investigate associations between liver histology and demographic, nutritional, biochemical and virological parameters. Methods - Eight-five patients with CHC prospectively underwent hepatic biopsy. Liver fragments were obtained from each patient by percutaneous route using a Menghini needle. Fibrosis was evaluated according to the METAVIR scoring system, as follows: F0, no fibrosis; F1, fibrous portal expansion; F2, fibrous portal widening with few septa; F3, bridging fibrosis with architectural distortion; and F4, liver cirrhosis. The activity was classified based on the degree of lymphocyte infiltration and hepatocyte necrosis, from A0 to A3. The diagnosis of liver disease was based on clinical, biochemical, histological, and radiological methods. The data were analyzed by logistic regression models. Results - This cross-sectional study included 85 outpatients followed at the tertiary care ambulatory centre with a mean age of 57.2±10.7 years and 45 (52.9%) were females. There were 10 patients with cirrhosis. Patients with a METAVIR F3-F4 were significantly older (P=0.02) and had higher levels of ALT (P=0.0006), AST (P<0.0001), γ-GT (P=0.03) and bilirubin (P=0.001) and higher prothrombin time than patients with F0-F2 score. Albumin levels (P=0.01) were significantly lower in METAVIR F3-F4. Age (OR=1.09; 95%CI=1.02-1.16; P=0.02), steatosis (OR=4.03; 95%CI=1.05-15.45; P=0.04) and high-density lipoprotein cholesterol (HDL-C) <60 mg/dL (OR=7.67; 95%CI=1.71-34.49; P=0.008) were independently associated with fibrosis. Hypertension (OR=6.36; 95%CI=1.31-30.85; P=0.02) and HDL-C <60 mg/dL (OR=9.85; 95%CI=2.35-41.39; P=0.002) were independently associated with necroinflammatory activity. Hypertension (OR=6.94; 95%CI=1.92-25.05; P=0.003) and HDL-C <60 mg/dL (OR=3.94; 95%CI=1.27-12.3; P=0.02) were associated with interface inflammatory activity. Triglycerides (TG ≥150 mg/dL) remained associated with lobular inflammatory activity. Conclusion - cholesterol levels <60 mg/dL were independently associated with necroinflammatory activity in chronic hepatitis C. Patients with hypertension are at an increased risk of developing necroinflammatory activity.

Endotoxemia and Gastrointestinal Cancers: Insight into the Mechanisms Underlying a Dangerous Relationship

Lipopolysaccharide (LPS), also known as endotoxin, is a component of the membrane of gram-negative bacteria and a well-recognized marker of sepsis. In case of disruption of the intestinal barrier, as occurs with unhealthy diets, alcohol consumption, or during chronic diseases, the microbiota residing in the gastrointestinal tract becomes a crucial factor in amplifying the systemic inflammatory response. Indeed, the translocation of LPS into the bloodstream and its interaction with toll-like receptors (TLRs) triggers molecular pathways involved in cytokine release and immune dysregulation. This is a critical step in the exacerbation of many diseases, including metabolic disorders and cancer. Indeed, the role of LPS in cancer development is widely recognized, and examples include gastric tumor related to Helicobacter pylori infection and hepatocellular carcinoma, both of which are preceded by a prolonged inflammatory injury; in addition, the risk of recurrence and development of metastasis appears to be associated with endotoxemia. Here, we review the mechanisms that link the promotion and progression of tumorigenesis with endotoxemia, and the possible therapeutic interventions that can be deployed to counteract these events.

Ganoderma lucidum: Current advancements of characteristic components and experimental progress in anti-liver fibrosis

Ganoderma lucidum (G. lucidum, Lingzhi) is a well-known herbal medicine with a variety of pharmacological effects. Studies have found that G. lucidum has pharmacological effects such as antioxidant, antitumor, anti-aging, anti-liver fibrosis, and immunomodulation. The main active components of G. lucidum include triterpenoids, polysaccharides, sterols, peptides and other bioactive components. Among them, the triterpenoids and polysaccharide components of G. lucidum have a wide range of anti-liver fibrotic effects. Currently, there have been more reviews and studies on the antioxidant, antitumor, and anti-aging properties of G. lucidum. Based on the current trend of increasing number of liver fibrosis patients in the world, we summarized the role of G.lucidum extract in anti-liver fibrosis and the effect of G. lucidum extract on liver fibrosis induced by different pathogenesis, which were discussed and analyzed. Research and development ideas and references are provided for the subsequent application of G. lucidum extracts in anti-liver fibrosis treatment.

NOX as a Therapeutic Target in Liver Disease

The nicotinamide adenine dinucleotide phosphate hydrogen oxidase (NADPH oxidase or NOX) plays a critical role in the inflammatory response and fibrosis in several organs such as the lungs, pancreas, kidney, liver, and heart. In the liver, NOXs contribute, through the generation of reactive oxygen species (ROS), to hepatic fibrosis by acting through multiple pathways, including hepatic stellate cell activation, proliferation, survival, and migration of hepatic stellate cells; hepatocyte apoptosis, enhancement of fibrogenic mediators, and mediation of an inflammatory cascade in both Kupffer cells and hepatic stellate cells. ROS are overwhelmingly produced during malignant transformation and hepatic carcinogenesis (HCC), creating an oxidative microenvironment that can cause different and various types of cellular stress, including DNA damage, ER stress, cell death of damaged hepatocytes, and oxidative stress. NOX1, NOX2, and NOX4, members of the NADPH oxidase family, have been linked to the production of ROS in the liver. This review will analyze some diseases related to an increase in oxidative stress and its relationship with the NOX family, as well as discuss some therapies proposed to slow down or control the disease's progression.

Current strategies for targeted therapy of liver fibrosis

Liver fibrosis (LF) is an unfavorable event in the natural course of chronic liver diseases (CLD), therefore, early implementation and widespread use of antifibrotic therapy methods is a pressing issue in hepatology. The aim of the review was to describe current approaches to targeted therapy of LF.

PubMed database, Google Scholar search engine, Cochrane Database of Systematic Reviews, eLIBRARY.RU scientific electronic library, as well as reference lists of articles were used to search for scientific articles. The publications that corresponded to the aim of the study were selected for the period from 1998 to 2021 by the terms “liver fibrosis”, “pathogenesis”, and “treatment”. Inclusion criteria were restricted to targeted therapy of LF.

Despite the growing evidence for reversibility of LF, there are currently no effective or clinically approved regimens for its specific therapy. However, taking into account the relevance of the issue, scientific research in this area is necessary. Multiple drugs with a good safety profile have been studied, which, though intended for other purposes, can have a positive effect on LF. In addition, a number of innovative approaches that differ from pharmacotherapy inspire optimism about finding a solution to this problem. It is obvious that studies focused on well-characterized groups of patients with confirmed histologic, elastography, clinical, and radiological parameters are required. This is a challenging task, since the key point will be stratification of risk based on ethnicity, etiology, and clinical status, and very large samples will be required for a reliable assessment. Nevertheless, the solution will increase efficiency of treatment for patients with CLD, improve their prognosis and quality of life, and significantly reduce the need for liver transplantation, a demand for which remains extremely high worldwide.

Recent Advancements in Antifibrotic Therapies for Regression of Liver Fibrosis

Cirrhosis is a severe form of liver fibrosis that results in the irreversible replacement of liver tissue with scar tissue in the liver. Environmental toxicity, infections, metabolic causes, or other genetic factors including autoimmune hepatitis can lead to chronic liver injury and can result in inflammation and fibrosis. This activates myofibroblasts to secrete ECM proteins, resulting in the formation of fibrous scars on the liver. Fibrosis regression is possible through the removal of pathophysiological causes as well as the elimination of activated myofibroblasts, resulting in the reabsorption of the scar tissue. To date, a wide range of antifibrotic therapies has been tried and tested, with varying degrees of success. These therapies include the use of growth factors, cytokines, miRNAs, monoclonal antibodies, stem-cell-based approaches, and other approaches that target the ECM. The positive results of preclinical and clinical studies raise the prospect of a viable alternative to liver transplantation in the near future. The present review provides a synopsis of recent antifibrotic treatment modalities for the treatment of liver cirrhosis, as well as a brief summary of clinical trials that have been conducted to date.

Combination therapy based on targeted nano drug co-delivery systems for liver fibrosis treatment: A review

Liver fibrosis is the hallmark of liver disease and occurs prior to the stages of cirrhosis and hepatocellular carcinoma. Any type of liver damage or inflammation can result in fibrosis. Fibrosis does not develop overnight, but rather as a result of the long-term action of injury factors. At present, however, there are no good treatment methods or specific drugs other than removing the pathogenic factors. Drug application is still limited, which means that drugs with good performance in vitro cannot achieve good therapeutic effects in vivo, owing to various factors such as poor drug targeting, large side effects, and strong hydrophobicity. Hepatic stellate cells (HSC) are the primary effector cells in liver fibrosis. The nano-drug delivery system is a new and safe drug delivery system that has many advantages which are widely used in the field of liver fibrosis. Drug resistance and side effects can be reduced when two or more drugs are used in combination drug delivery. Combination therapy of drugs with different targets has emerged as a novel approach to treating liver fibrosis, and the nano co-delivery system enhances the benefits of combination therapy. While nano co-delivery systems can maximize benefits while avoiding drug side effects, this is precisely the advantage of the nano co-delivery system. This review briefly described the pathogenesis and current treatment strategies, the different co-delivery systems of combination drugs in the nano delivery system, and targeting strategies for nano delivery systems on liver fibrosis therapy. Because of their superior performance, nano delivery systems and targeting drug delivery systems have received a lot of attention in the new drug delivery system. The new delivery systems offer a new pathway in the treatment of liver fibrosis, and it is believed that it can be a new treatment for fibrosis in the future. Nano co-delivery system of combination drugs and targeting strategies has proven the effectiveness of anti-fibrosis at the experimental level.

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.

Liver Fibrosis: Therapeutic Targets and Advances in Drug Therapy

Liver fibrosis is an abnormal wound repair response caused by a variety of chronic liver injuries, which is characterized by over-deposition of diffuse extracellular matrix (ECM) and anomalous hyperplasia of connective tissue, and it may further develop into liver cirrhosis, liver failure or liver cancer. To date, chronic liver diseases accompanied with liver fibrosis have caused significant morbidity and mortality in the world with increasing tendency. Although early liver fibrosis has been reported to be reversible, the detailed mechanism of reversing liver fibrosis is still unclear and there is lack of an effective treatment for liver fibrosis. Thus, it is still a top priority for the research and development of anti-fibrosis drugs. In recent years, many strategies have emerged as crucial means to inhibit the occurrence and development of liver fibrosis including anti-inflammation and liver protection, inhibition of hepatic stellate cells (HSCs) activation and proliferation, reduction of ECM overproduction and acceleration of ECM degradation. Moreover, gene therapy has been proved to be a promising anti-fibrosis method. Here, we provide an overview of the relevant targets and drugs under development. We aim to classify and summarize their potential roles in treatment of liver fibrosis, and discuss the challenges and development of anti-fibrosis drugs.

Quantitative Susceptibility Mapping versus R2*-based Histogram Analysis for Evaluating Liver Fibrosis: Preliminary Results

PURPOSE

The staging of liver fibrosis is clinically important, and a less invasive method is preferred. Quantitative susceptibility mapping (QSM) has shown a great potential in estimating liver fibrosis in addition to R2* relaxometry. However, few studies have compared QSM analysis and liver fibrosis. We aimed to evaluate the feasibility of estimating liver fibrosis by using QSM and R2*-based histogram analyses by comparing it with ultrasound-based transient elastography and the stage of histologic fibrosis.

METHODS

Fourteen patients with liver disease were enrolled. Data sets of multi-echo gradient echo sequence with breath-holding were acquired on a 3-Tesla scanner. QSM and R2* were reconstructed by water-fat separation method, and ROIs were analyzed for these images. Quantitative parameters with histogram features (mean, variance, skewness, kurtosis, and 1st, 10th, 50th, 90th, and 99th percentiles) were extracted. These data were compared with the elasticity measured by ultrasound transient elastography and histological stage of liver fibrosis (F0 to F4, based on the new Inuyama classification) determined by biopsy or hepatectomy. The correlation of histogram parameters with intrahepatic elasticity and histologically confirmed fibrosis stage was examined. Texture parameters were compared between subgroups divided according to fibrosis stage. Receiver operating characteristic (ROC) analysis was also performed. P < 0.05 indicated statistical significance.

RESULTS

The six histogram parameters of both QSM and R2*were significantly correlated with intrahepatic elasticity. In particular, three parameters (variance, percentiles [90th and 99th]) of QSM showed high correlation (r = 0.818-0.844), whereas R2* parameters showed a moderate correlation with elasticity. Four parameters of QSM were significantly correlated with fibrosis stage (ρ = 0.637-0.723) and differentiated F2-4 from F0-1 fibrosis and F3-4 from F0-2 fibrosis with areas under the ROC curve of > 0.8, but those of R2* did not.

CONCLUSION

QSM may serve as a promising surrogate indicator in detecting liver fibrosis.

Synergistic effects of sitagliptin and losartan against fipronil-induced hepatotoxicity in rats

Background and Aim

Fipronil (FPN) is a potent pesticide that is heavily used around the world in agriculture. However, its irrational use could potentially have deleterious effects on animals and humans. The present study aimed to investigate the ability of sitagliptin (Sit) and losartan (LOS), when used both individually or concurrently, to guard rat liver against the acute hepatotoxicity caused by FPN.

Materials and Methods

Forty-two adult male Wistar rats were equally divided into seven groups (6/group). Group I (control) received normal saline (0.5 mL/rat, vehicle for all treatments) by gavage once daily for 10 days. Group II received oral Sit (10 mg/kg body weight [BW]) daily for 10 days and Group III received oral LOS (5 mg/kg BW) daily for 10 days. Group IV received oral FPN (19.4 mg/kg BW; 1/5 of the oral LD₅₀) for the past 5 days of the study. Groups V and VI received oral Sit (10 mg/kg BW) and LOS (5 mg/kg BW) daily, respectively, 5 days prior and 5 days during FPN administration (19.4 mg/kg BW). Group VII received oral Sit (10 mg/kg BW) and LOS (5 mg/kg BW) for 10 days with daily FPN during the past 5 days. After the end of the treatment period, the rats were humanely sacrificed and blood and liver tissue samples were collected for biochemical analysis and histopathological and immunohistochemical investigations.

Results

FPN administration resulted in elevated alanine aminotransferase, aspartate aminotransferase, and alkaline phosphatase serum concentrations as well as increased malondialdehyde levels and reduced catalase, superoxide dismutase, glutathione peroxidase, and glutathione activity. The histopathological investigation showed disorganization of the hepatic cords and focal necrosis of the hepatocytes in FPN-intoxicated rats. Furthermore, the immunohistochemical examination showed that hepatic caspase-3 was overexpressed in the FPN-treated rats. The administration of Sit and LOS before and alongside FPN markedly mitigated the alterations caused by FPN and the hepatoprotective effects were more prominent in the combination group.

Conclusion

Sit and LOS, both individually or in combination, confers considerable hepatoprotection against FPN-induced hepatotoxicity.

Fluorofenidone protects liver against inflammation and fibrosis by blocking the activation of NF-κB pathway

Despite the increasing understanding of the pathophysiology of hepatic fibrosis, the therapies to combat it remain inadequate. Fluorofenidone (AKF-PD) is a novel pyridone agent able to ameliorate hepatic fibrosis in an experimental hepatic fibrosis model induced by dimethylnitrosamine. However, the underlying mechanism remains to be further elucidated. In light of the critical role of the NF-κB pathway in inflammation and hepatic fibrosis, together with the preliminary finding that AKF-PD decreases the release of proinflammatory cytokines in the endotoxemia and unilateral ureteral occlusion model, the aim of this study was to explore whether AKF-PD exerts an antifibrotic effect in hepatic fibrosis by inhibiting inflammation and suppressing the activation of the NF-κB pathway in vivo and in vitro. To test this possibility, the effect of AKF-PD on hepatic fibrosis models induced by both carbon tetrachloride (CCL₄ ) and porcine serum (PS) was investigated. Our results showed that AKF-PD treatment ameliorated hepatic injury and fibrosis in both models. Furthermore, the administration of AKF-PD induced a robust anti-inflammatory reaction revealed by the downregulation of the proinflammatory cytokines as well as the suppression of the infiltration of inflammatory cells in the fibrotic liver. The analysis of the mechanism of action demonstrated that the attenuation of the production of proinflammatory cytokines and chemokines mediated by AKF-PD in vivo and in vitro were accompanied by the suppression in the activation of the NF-κB signaling pathway. In conclusion, AKF-PD might be considered as an antifibrotic agent attenuating hepatic inflammation and fibrosis potentially through the suppression of the NF-κB pathway.

COVID-19, ferrosenescence and neurodegeneration, a mini-review

Exacerbation of cognitive, motor and nonmotor symptoms have been described in critically ill COVID-19 patients, indicating that, like prior pandemics, neurodegenerative sequelae may mark the aftermath of this viral infection. Moreover, SARS-CoV-2, the causative agent of COVID-19 disease, was associated with hyperferritinemia and unfavorable prognosis in older individuals, suggesting virus-induced ferrosenescence. We have previously defined ferrosenescence as an iron-associated disruption of both the human genome and its repair mechanisms, leading to premature cellular senescence and neurodegeneration. As viruses replicate more efficiently in iron-rich senescent cells, they may have developed the ability to induce this phenotype in host tissues, predisposing to both immune dysfunction and neurodegenerative disorders. In this mini-review, we summarize what is known about the SARS-CoV-2-induced cellular senescence and iron dysmetabolism. We also take a closer look at immunotherapy with natural killer cells, angiotensin II receptor blockers ("sartans"), iron chelators and dipeptidyl peptidase 4 inhibitors ("gliptins") as adjunct treatments for both COVID-19 and its neurodegenerative complications.

Liver Disease: Induction, Progression, Immunological Mechanisms, and Therapeutic Interventions

The liver is an organ with impressive regenerative potential and has been shown to heal sizable portions after their removal. However, certain diseases can overstimulate its potential to self-heal and cause excessive cellular matrix and collagen buildup. Decompensation of liver fibrosis leads to cirrhosis, a buildup of fibrotic ECM that impedes the liver’s ability to efficiently exchange fluid. This review summarizes the complex immunological activities in different liver diseases, and how failure to maintain liver homeostasis leads to progressive fibrotic tissue development. We also discuss a variety of pathologies that lead to liver cirrhosis, such as alcoholic liver disease and chronic hepatitis B virus (HBV). Mesenchymal stem cells are widely studied for their potential in tissue replacement and engineering. Herein, we discuss the potential of MSCs to regulate immune response and alter the disease state. Substantial efforts have been performed in preclinical animal testing, showing promising results following inhibition of host immunity. Finally, we outline the current state of clinical trials with mesenchymal stem cells and other cellular and non-cellular therapies as they relate to the detection and treatment of liver cirrhosis.

Strategies Targeting the Innate Immune Response for the Treatment of Hepatitis C Virus-Associated Liver Fibrosis

Direct-acting antivirals eliminate hepatitis C virus (HCV) in more than 95% of treated individuals and may abolish liver injury, arrest fibrogenesis, and reverse fibrosis and cirrhosis. However, liver regeneration is usually a slow process that is less effective in the late stages of fibrosis. What is more, fibrogenesis may prevail in patients with advanced cirrhosis, where it can progress to liver failure and hepatocellular carcinoma. Therefore, the development of antifibrotic drugs that halt and reverse fibrosis progression is urgently needed. Fibrosis occurs due to the repair process of damaged hepatic tissue, which eventually leads to scarring. The innate immune response against HCV is essential in the initiation and progression of liver fibrosis. HCV-infected hepatocytes and liver macrophages secrete proinflammatory cytokines and chemokines that promote the activation and differentiation of hepatic stellate cells (HSCs) to myofibroblasts that produce extracellular matrix (ECM) components. Prolonged ECM production by myofibroblasts due to chronic inflammation is essential to the development of fibrosis. While no antifibrotic therapy is approved to date, several drugs are being tested in phase 2 and phase 3 trials with promising results. This review discusses current state-of-the-art knowledge on treatments targeting the innate immune system to revert chronic hepatitis C-associated liver fibrosis. Agents that cause liver damage may vary (alcohol, virus infection, etc.), but fibrosis progression shows common patterns among them, including chronic inflammation and immune dysregulation, hepatocyte injury, HSC activation, and excessive ECM deposition. Therefore, mechanisms underlying these processes are promising targets for general antifibrotic therapies.

Efficacy and safety of anti-hepatic fibrosis drugs

Recent progress in our understanding of the pathways linked to progression from hepatic insult to cirrhosis has led to numerous novel therapies being investigated as potential cures and inhibitors of hepatic fibrogenesis. Liver cirrhosis is the final result of prolonged fibrosis, which is an intimate balance between fibrogenesis and fibrinolysis. A number of these complex mechanisms are shared across the various etiologies of liver disease. Thankfully, investigation has yielded some promising results in regard to reversal of fibrosis, particularly the indirect benefits associated with antiviral therapy for the treatment of hepatitis B and C and the farnesoid receptor agonist for the treatment of primary biliary cholangitis and metabolic associated fatty liver disease. A majority of current clinical research is focused on targeting metabolic associated fatty liver disease and its progression to metabolic steatohepatitis and ultimately cirrhosis, with some hope of potential standardized therapeutics in the near future. With our ever-evolving understanding of the underlying pathophysiology, these therapeutics focus on either controlling the primary disease (the initial trigger of fibrogenesis), interrupting receptor ligand interactions and other intracellular communications, inhibiting fibrogenesis, or even promoting resolution of fibrosis. It is imperative to thoroughly test these potential therapies with the rigorous standards of clinical therapeutic trials in order to ensure the highest standards of patient safety. In this article we will briefly review the key pathophysiological pathways that lead to liver fibrosis and present current clinical and experimental evidence that has shown reversibility of liver fibrosis and cirrhosis, while commenting on therapeutic safety.

"Let my liver rather heat with wine" - a review of hepatic fibrosis pathophysiology and emerging therapeutics

Cirrhosis is characterized by extensive hepatic fibrosis, and it is the 14th leading cause of death worldwide. Numerous contributing conditions have been implicated in its development, including infectious etiologies, medication overdose or adverse effects, ingestible toxins, autoimmunity, hemochromatosis, Wilson’s disease and primary biliary cholangitis to list a few. It is associated with portal hypertension and its stigmata (varices, ascites, hepatic encephalopathy, combined coagulopathy and thrombophilia), and it is a major risk factor for hepatocellular carcinoma. Currently, orthotopic liver transplantation has been the only curative modality to treat cirrhosis, and the scarcity of donors results in many people waiting years for a transplant. Identification of novel targets for pharmacologic therapy through elucidation of key mechanistic components to induce fibrosis reversal is the subject of intense research. Development of robust models of hepatic fibrosis to faithfully characterize the interplay between activated hepatic stellate cells (the principal fibrogenic contributor to fibrosis initiation and perpetuation), hepatocytes and extracellular matrix components has the potential to identify critical components and mechanisms that can be exploited for targeted treatment. In this review, we will highlight key cellular pathways involved in the pathophysiology of fibrosis from extracellular ligands, effectors and receptors, to nuclear receptors, epigenetic mechanisms, energy homeostasis and cytokines. Further, molecular pathways of hepatic stellate cell deactivation are discussed, including apoptosis, senescence and reversal or transdifferentiation to an inactivated state resembling quiescence. Lastly, clinical evidence of fibrosis reversal induced by biologics and small molecules is summarized, current compounds under clinical trials are described and efforts for treatment of hepatic fibrosis with mesenchymal stem cells are highlighted. An enhanced understanding of the rich tapestry of cellular processes identified in the initiation, perpetuation and resolution of hepatic fibrosis, driven principally through phenotypic switching of hepatic stellate cells, should lead to a breakthrough in potential therapeutic modalities.

Targeting Oxidative Stress for the Treatment of Liver Fibrosis

Oxidative stress is a reflection of the imbalance between the production of reactive oxygen species (ROS) and the scavenging capacity of the antioxidant system. Excessive ROS, generated from various endogenous oxidative biochemical enzymes, interferes with the normal function of liver-specific cells and presumably plays a role in the pathogenesis of liver fibrosis. Once exposed to harmful stimuli, Kupffer cells (KC) are the main effectors responsible for the generation of ROS, which consequently affect hepatic stellate cells (HSC) and hepatocytes. ROS-activated HSC undergo a phenotypic switch and deposit an excessive amount of extracellular matrix that alters the normal liver architecture and negatively affects liver function. Additionally, ROS stimulate necrosis and apoptosis of hepatocytes, which causes liver injury and leads to the progression of end-stage liver disease. In this review, we overview the role of ROS in liver fibrosis and discuss the promising therapeutic interventions related to oxidative stress. Most importantly, novel drugs that directly target the molecular pathways responsible for ROS generation, namely, mitochondrial dysfunction inhibitors, endoplasmic reticulum stress inhibitors, NADPH oxidase (NOX) inhibitors, and Toll-like receptor (TLR)-affecting agents, are reviewed in detail. In addition, challenges for targeting oxidative stress in the management of liver fibrosis are discussed.

Liver fibrosis: Pathophysiology, pathogenetic targets and clinical issues. Mol Aspects Med. 2019;65:37-55. [PMID: 30213667 DOI: 10.1016/j.mam.2018.09.002]

The progression of chronic liver diseases (CLD), irrespective of etiology, involves chronic parenchymal injury, persistent activation of inflammatory response as well as sustained activation of liver fibrogenesis and wound healing response. Liver fibrogenesis, is a dynamic, highly integrated molecular, cellular and tissue process responsible for driving the excess accumulation of extracellular matrix (ECM) components (i.e., liver fibrosis) sustained by an eterogeneous population of hepatic myofibroblasts (MFs). The process of liver fibrogenesis recognizes a number of common and etiology-independent mechanisms and events but it is also significantly influenced by the specific etiology, as also reflected by peculiar morphological patterns of liver fibrosis development. In this review we will analyze the most relevant established and/or emerging pathophysiological issues underlying CLD progression with a focus on the role of critical hepatic cell populations, mechanisms and signaling pathways involved, as they represent potential therapeutic targets, to finally analyze selected and relevant clinical issues.

Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (NOX) and liver fibrosis: A review

Nicotinamide adenine dinucleotide phosphate (NADPH) oxidases (NOXs) are key producer of reactive oxygen species in liver cells. Hepatic stellate cells (HSCs) and Kupffer cells (KCs) are the two key cells for expression of NOX in liver. KCs produce only NOX2, while HSCs produce NOX1, 2, and 4, all of which play essential roles in the process of fibrogenesis within liver. These NOX subtypes are contributed to induction of liver fibrosis by acting through multiple pathways including induction of HSC activation, proliferation, survival and migration, stimulation of hepatocyte apoptosis, enhancement of fibrogenic mediators, and mediation of an inflammatory cascade in both KCs and HSCs.

SIGNIFICANCE

KCs and HSCs are two key cells for production of NOX in liver in relation to the pathology of liver fibrosis. NOX subtypes 1, 2, and 4 are inducers of fibrogenesis in liver. NOX activation favors hepatocyte apoptosis, HSC activation, and KC-mediated inflammatory cascade in liver, all of which are responsible for generation of liver fibrosis.

Emerging therapeutic biomarkers of autoimmune hepatitis and their impact on current and future management

Autoimmune hepatitis lacks a quantifiable biomarker that is close to its pathogenic mechanisms and that accurately reflects inflammatory activity, correlates with treatment response, and ensures inactive disease before treatment withdrawal. Areas covered: Micro-ribonucleic acids, programmed death-1 protein and its ligands, macrophage migration inhibitory factor, soluble CD163, B cell activating factor, and metabolite patterns in blood were considered the leading candidates as therapeutic biomarkers after search of PubMed from August 1981 to August 2017 using the search words 'biomarkers of autoimmune hepatitis'. Expert commentary: Each of the candidate biomarkers is close to the putative pathogenic mechanisms of autoimmune hepatitis, and each has attributes that support its potential role as a surrogate marker of inflammatory activity that can be monitored during treatment. Future studies must demonstrate the superiority of each biomarker to conventional indices of inflammatory activity and validate their correlation with treatment response and outcome. A reliable therapeutic biomarker would facilitate the individualization of current management algorithms, ensure that pathogenic mechanisms were disrupted or eliminated prior to treatment withdrawal, and reduce the frequency of relapse or unnecessary protracted therapy. The biomarker might also prove to be a target of next-generation therapies.

Role of the renin-angiotensin system in hepatic fibrosis and portal hypertension

The renin-angiotensin system (RAS) is an important regulator of cirrhosis and portal hypertension. As hepatic fibrosis progresses, levels of the RAS components angiotensin (Ang) II, Ang-(1-7), angiotensin-converting enzyme (ACE), and Ang II type 1 receptor (AT1R) are increased. The primary effector Ang II regulates vasoconstriction, sodium homoeostasis, fibrosis, cell proliferation, and inflammation in various diseases, including liver cirrhosis, through the ACE/Ang II/AT1R axis in the classical RAS. The ACE2/Ang-(1-7)/Mas receptor and ACE2/Ang-(1-9)/AT2R axes make up the alternative RAS and promote vasodilation, antigrowth, proapoptotic, and anti-inflammatory effects; thus, countering the effects of the classical RAS axis to reduce hepatic fibrogenesis and portal hypertension. Patients with portal hypertension have been treated with RAS antagonists such as ACE inhibitors, Ang receptor blockers, and aldosterone antagonists, with very promising hemodynamic results. In this review, we examine the RAS, its roles in hepatic fibrosis and portal hypertension, and current therapeutic approaches based on the use of RAS antagonists in patients with portal hypertension.

Autoimmune hepatitis

Autoimmune hepatitis (AIH) is a severe liver disease that affects children and adults worldwide. The diagnosis of AIH relies on increased serum transaminase and immunoglobulin G levels, presence of autoantibodies and interface hepatitis on liver histology. AIH arises in genetically predisposed individuals when a trigger, such as exposure to a virus, leads to a T cell-mediated autoimmune response directed against liver autoantigens; this immune response is permitted by inadequate regulatory immune control leading to a loss of tolerance. AIH responds favourably to immunosuppressive treatment, which should be started as soon as the diagnosis is made. Standard regimens include fairly high initial doses of corticosteroids (prednisone or prednisolone), which are tapered gradually as azathioprine is introduced. For those patients who do not respond to standard treatment, second-line drugs should be considered, including mycophenolate mofetil, calcineurin inhibitors, mechanistic target of rapamycin (mTOR) inhibitors and biologic agents, which should be administered only in specialized hepatology centres. Liver transplantation is a life-saving option for those who progress to end-stage liver disease, although AIH can recur or develop de novo after transplantation. In-depth investigation of immune pathways and analysis of changes to the intestinal microbiota should advance our knowledge of the pathogenesis of AIH and lead to novel, tailored and better tolerated therapies.

Chymase Inhibitor as a Novel Therapeutic Agent for Non-alcoholic Steatohepatitis

Non-alcoholic steatohepatitis (NASH) is characterized by inflammation and fibrosis, in addition to steatosis, of the liver, but no therapeutic agents have yet been established. The mast cell protease chymase can generate angiotensin II, matrix metalloproteinase-9 and transforming growth factor-β, all of which are associated with liver inflammation or fibrosis. In animal models of NASH, augmented chymase has been observed in the liver. In histological analysis, chymase inhibitor prevented hepatic steatosis, inflammation, and fibrosis. Chymase inhibitor also attenuated the augmentation of angiotensin II, matrix metalloproteinase-9, and transforming growth factor-β observed in the liver of NASH. Oxidative stress, inflammatory markers, and collagen were attenuated by chymase inhibition. Moreover, chymase inhibitor showed a mitigating effect on established NASH, and survival rates were significantly increased by treatment with chymase inhibitor. In this review, we propose that chymase inhibitor has potential as a novel therapy for NASH.

Hepatic Fibrosis in Dogs

Hepatic fibrosis is commonly diagnosed in dogs, often as a sequela to chronic hepatitis (CH). The development of fibrosis is a crucial event in the progression of hepatic disease that is of prognostic value. The pathophysiology of hepatic fibrosis in human patients and rodent models has been studied extensively. Although less is known about this process in dogs, evidence suggests that fibrogenic mechanisms are similar between species and that activation of hepatic stellate cells is a key step. Diagnosis and staging of hepatic fibrosis in dogs requires histopathological examination of a liver biopsy specimen. However, performing a liver biopsy is invasive and assessment of fibrotic stage is complicated by the absence of a universally accepted staging scheme in veterinary medicine. Serum biomarkers that can discriminate among different fibrosis stages are used in human patients, but such markers must be more completely evaluated in dogs before clinical use. When successful treatment of its underlying cause is feasible, reversal of hepatic fibrosis has been shown to be possible in rodent models and human patients. Reversal of fibrosis has not been well documented in dogs, but successful treatment of CH is possible. In human medicine, better understanding of the pathomechanisms of hepatic fibrosis is leading to the development of novel treatment strategies. In time, these may be applied to dogs. This article comparatively reviews the pathogenesis of hepatic fibrosis, its diagnosis, and its treatment in dogs.

Review article: next-generation transformative advances in the pathogenesis and management of autoimmune hepatitis

BACKGROUND

Advances in autoimmune hepatitis that transform current concepts of pathogenesis and management can be anticipated as products of ongoing investigations driven by unmet clinical needs and an evolving biotechnology.

AIM

To describe the advances that are likely to become transformative in autoimmune hepatitis, based on the direction of current investigations.

METHODS

Pertinent abstracts were identified in PubMed by multiple search terms. Full-length articles were selected for review, and a secondary bibliography was developed. The discovery process was repeated, and a tertiary bibliography was identified. The number of abstracts reviewed was 2830, and the number of full-length articles reviewed exceeded 150.

RESULTS

Risk-laden allelic variants outside the major histocompatibility complex (rs3184504, r36000782) are being identified by genome-wide association studies, and their gene products are potential therapeutic targets. Epigenetic changes associated with environmental cues can enhance the transcriptional activity of genes, and chromatin re-structuring and antagonists of noncoding molecules of ribonucleic acid are feasible interventions. The intestinal microbiome is a discovery field for microbial products and activated immune cells that may translocate to the periphery and respond to manipulation. Epidemiological studies and controlled interview-based surveys may implicate environmental and xenobiotic factors that warrant evidence-based changes in lifestyle, and site-directed molecular and cellular interventions promise to change the paradigm of treatment from one of blanket immunosuppression.

CONCLUSIONS

Advances in genetics, epigenetics, pathophysiology, epidemiology, and site-directed molecular and cellular interventions constitute the next generation of transformative advances in autoimmune hepatitis.

Serum angiotensin-converting enzyme level for evaluating significant fibrosis in chronic hepatitis B

AIM

To evaluate the diagnostic performance of angiotensin-converting enzyme (ACE) on significant liver fibrosis in patients with chronic hepatitis B (CHB).

METHODS

In total, 100 patients with CHB who underwent liver biopsy in our hospital were enrolled, and 70 patients except for 30 patients with hypertension, fatty liver or habitual alcoholic consumption were analyzed. We compared histological liver fibrosis and serum ACE levels and evaluated the predictive potential to diagnose significant liver fibrosis by comparison with several biochemical marker-based indexes such as the aspartate aminotransferase (AST)-to-platelet ratio index (APRI), the fibrosis index based on four factors (FIB-4), the Mac-2 binding protein glycosylation isomer (M2BPGi) level and the number of platelets (Plt).

RESULTS

Serum ACE levels showed moderately positive correlation with liver fibrotic stages (R² = 0.181). Patients with significant, advanced fibrosis and cirrhosis (F2-4) had significantly higher serum ACE levels than those with early-stage fibrosis and cirrhosis (F0-1). For significant fibrosis (≥ F2), the 12.8 U/L cut-off value of ACE showed 91.7% sensitivity and 75.0% specificity. The receiver-operating characteristic (ROC) curves analysis revealed that the area under the curve (AUC) value of ACE was 0.871, which was higher than that of APRI, FIB-4, M2BPGi and Plt.

CONCLUSION

The serum ACE level could be a novel noninvasive, easy, accurate, and inexpensive marker of significant fibrosis stage in patients with CHB.

Candesartan, rather than losartan, improves motor dysfunction in thioacetamide-induced chronic liver failure in rats

Minimal hepatic encephalopathy is more common than the acute syndrome. Losartan, the first angiotensin-II receptor blocker (ARB), and candesartan, another widely-used ARB, have protected against developing fibrogenesis, but there is no clear data about their curative antifibrotic effects. The current study was designed to examine their effects in an already-established model of hepatic fibrosis and also their effects on the associated motor dysfunction. Low-grade chronic liver failure (CLF) was induced in 3-month old Sprague-Dawley male rats using thioacetamide (TAA, 50 mg·kg-1·day-1) intraperitoneally for 2 weeks. The TAA-CLF rats were randomly divided into five groups (n=8) treated orally for 14 days (mg·kg-1·day-1) as follows: TAA (distilled water), losartan (5 and 10 mg/kg), and candesartan (0.1 and 0.3 mg/kg). Rats were tested for rotarod and open-field tests. Serum and hepatic biochemical markers, and hepatic histopathological changes were evaluated by H&E and Masson's staining. The TAA-CLF rats showed significant increases of hepatic malondialdehyde, hepatic expression of tumor necrosis factor-α (TNF-α), and serum ammonia, alanine aminotransferase, γ-glutamyl transferase, TNF-α, and malondialdehyde levels as well as significant decreases of hepatic and serum glutathione levels. All treatments significantly reversed these changes. The histopathological changes were moderate in losartan-5 and candesartan-0.1 groups and mild in losartan-10 and candesartan-0.3 groups. Only candesartan significantly improved TAA-induced motor dysfunction. In conclusion, therapeutic antifibrotic effects of losartan and candesartan in thioacetamide-induced hepatic fibrosis in rats are possibly through angiotensin-II receptor blocking, antioxidant, and anti-inflammatory activities. Improved motor dysfunction by candesartan could be attributed to better brain penetration and slower "off-rate" from angiotensin-II receptors. Clinical trials are recommended.

Novel treatment options for portal hypertension

Portal hypertension is most frequently associated with cirrhosis and is a major driver for associated complications, such as variceal bleeding, ascites or hepatic encephalopathy. As such, clinically significant portal hypertension forms the prelude to decompensation and impacts significantly on the prognosis of patients with liver cirrhosis. At present, non-selective β-blockers, vasopressin analogues and somatostatin analogues are the mainstay of treatment but these strategies are far from satisfactory and only target splanchnic hyperemia. In contrast, safe and reliable strategies to reduce the increased intrahepatic resistance in cirrhotic patients still represent a pending issue. In recent years, several preclinical and clinical trials have focused on this latter component and other therapeutic avenues. In this review, we highlight novel data in this context and address potentially interesting therapeutic options for the future.

Reversal of liver fibrosis: From fiction to reality

In chronic liver diseases, an ongoing hepatocellular injury together with inflammatory reaction results in activation of hepatic stellate cells (HSCs) and increased deposition of extracellular matrix (ECM) termed as liver fibrosis. It can progress to cirrhosis that is characterized by parenchymal and vascular architectural changes together with the presence of regenerative nodules. Even at late stage, liver fibrosis is reversible and the underlying mechanisms include a switch in the inflammatory environment, elimination or regression of activated HSCs and degradation of ECM. While animal models have been indispensable for our understanding of liver fibrosis, they possess several important limitations and need to be further refined. A better insight into the liver fibrogenesis resulted in a large number of clinical trials aiming at reversing liver fibrosis, particularly in patients with non-alcoholic steatohepatitis. Collectively, the current developments demonstrate that reversal of liver fibrosis is turning from fiction to reality.

Reversal of liver cirrhosis: current evidence and expectations

In the past, liver cirrhosis was considered an irreversible phenomenon. However, many experimental data have provided evidence of the reversibility of liver fibrosis. Moreover, multiple clinical studies have also shown regression of fibrosis and reversal of cirrhosis on repeated biopsy samples. As various etiologies are associated with liver fibrosis via integrated signaling pathways, a comprehensive understanding of the pathobiology of hepatic fibrogenesis is critical for improving clinical outcomes. Hepatic stellate cells play a central role in hepatic fibrogenesis upon their activation from a quiescent state. Collagen and other extracellular material components from activated hepatic stellate cells are deposited on, and damage, the liver parenchyma and vascular structures. Hence, inactivation of hepatic stellate cells can lead to enhancement of fibrolytic activity and could be a potential target of antifibrotic therapy. In this regard, continued efforts have been made to develop better treatments for underlying liver diseases and antifibrotic agents in multiple clinical and therapeutic trials; the best results may be expected with the integration of such evidence. In this article, we present the underlying mechanisms of fibrosis, current experimental and clinical evidence of the reversibility of liver fibrosis/cirrhosis, and new agents with therapeutic potential for liver fibrosis.

Stromal microenvironment in type VII collagen-deficient skin: The ground for squamous cell carcinoma development

Recessive dystrophic epidermolysis bullosa (RDEB) is a skin fragility disease caused by mutations that affect the function and/or the amount of type VII collagen (C7), the major component of anchoring fibrils. Hallmarks of RDEB are unremitting blistering and chronic wounds leading to tissue fibrosis and scarring. Nearly all patients with severe RDEB develop highly metastatic squamous cell carcinomas (SCC) which are the main cause of death. Accumulating evidence from a murine RDEB model and human RDEB cells demonstrates that lack of C7 also directly alters the wound healing process. Non-healing RDEB wounds are characterized by increased inflammation, high transforming growth factor-β1 (TGF-β1) levels and activity, and are heavily populated by myofibroblasts responsible for enhanced fibrogenesis and matrix stiffness. These changes make the RDEB stroma a microenvironment prone to cancer initiation, where cells with features of cancer-associated fibroblasts are found. Here, we discuss recent knowledge on microenvironment alterations in RDEB, highlighting possible therapeutic targets to prevent and/or delay fibrosis and SCC development.

Diagnosis and Management of Autoimmune Hepatitis: Current Status and Future Directions

Autoimmune hepatitis is characterized by autoantibodies, hypergammaglobulinemia, and interface hepatitis on histological examination. The features lack diagnostic specificity, and other diseases that may resemble autoimmune hepatitis must be excluded. The clinical presentation may be acute, acute severe (fulminant), or asymptomatic; conventional autoantibodies may be absent; centrilobular necrosis and bile duct changes may be present; and the disease may occur after liver transplantation or with features that suggest overlapping disorders. The diagnostic criteria have been codified, and diagnostic scoring systems can support clinical judgment. Nonstandard autoantibodies, including antibodies to actin, α-actinin, soluble liver antigen, perinuclear antineutrophil antigen, asialoglycoprotein receptor, and liver cytosol type 1, are tools that can support the diagnosis, especially in patients with atypical features. Prednisone or prednisolone in combination with azathioprine is the preferred treatment, and strategies using these medications in various doses can ameliorate treatment failure, incomplete response, drug intolerance, and relapse after drug withdrawal. Budesonide, mycophenolate mofetil, and calcineurin inhibitors can be considered in selected patients as frontline or salvage therapies. Molecular (recombinant proteins and monoclonal antibodies), cellular (adoptive transfer and antigenic manipulation), and pharmacological (antioxidants, antifibrotics, and antiapoptotic agents) interventions constitute future directions in management. The evolving knowledge of the pathogenic pathways and the advances in technology promise new management algorithms.

Antifibrotics in chronic liver disease: tractable targets and translational challenges

Chronic liver disease prevalence is increasing globally. Iterative liver damage, secondary to any cause of liver injury, results in progressive fibrosis, disrupted hepatic architecture, and aberrant regeneration, which are defining characteristics of liver cirrhosis. Liver transplantation is an effective treatment for end-stage liver disease; however, demand greatly outweighs donor organ supply, and in many parts of the world liver transplantation is unavailable. Hence, effective antifibrotic therapies are urgently required. In the past decade, rapid progress has been made in our understanding of the pathophysiology of liver fibrosis and a large number of potential cellular and molecular antifibrotic targets have been identified. This has led to numerous clinical trials of antifibrotic agents in patients with chronic liver disease. However, none of these have resulted in a robust and reproducible effect on fibrosis. It is therefore imperative that the ongoing translational challenges are addressed, to convert scientific discoveries into potent antifibrotics and enable bridging of the translational gap between putative therapeutic targets and effective treatments for patients with chronic liver disease.

Clinical Advancements in the Targeted Therapies against Liver Fibrosis

Hepatic fibrosis, characterized by excessive accumulation of extracellular matrix (ECM) proteins leading to liver dysfunction, is a growing cause of mortality worldwide. Hepatocellular damage owing to liver injury leads to the release of profibrotic factors from infiltrating inflammatory cells that results in the activation of hepatic stellate cells (HSCs). Upon activation, HSCs undergo characteristic morphological and functional changes and are transformed into proliferative and contractile ECM-producing myofibroblasts. Over recent years, a number of therapeutic strategies have been developed to inhibit hepatocyte apoptosis, inflammatory responses, and HSCs proliferation and activation. Preclinical studies have yielded numerous targets for the development of antifibrotic therapies, some of which have entered clinical trials and showed improved therapeutic efficacy and desirable safety profiles. Furthermore, advancements have been made in the development of noninvasive markers and techniques for the accurate disease assessment and therapy responses. Here, we focus on the clinical developments attained in the field of targeted antifibrotics for the treatment of liver fibrosis, for example, small molecule drugs, antibodies, and targeted drug conjugate. We further briefly highlight different noninvasive diagnostic technologies and will provide an overview about different therapeutic targets, clinical trials, endpoints, and translational efforts that have been made to halt or reverse the progression of liver fibrosis.

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.

The renin angiotensin system, oxidative stress and mitochondrial function in obesity and insulin resistance

Obesity is a complex disease characterized by excessive expansion of adipose tissue and is an important risk factor for chronic diseases such as cardiovascular disorders, hypertension and type 2 diabetes. Moreover, obesity is a major contributor to inflammation and oxidative stress, all of which are key underlying causes for diabetes and insulin resistance. Specifically, adipose tissue secretes bioactives molecules such as inflammatory hormone angiotensin II, generated in the Renin Angiotensin System (RAS) from its precursor angiotensinogen. Accumulated evidence suggests that RAS may serve as a strong link between obesity and insulin resistance. Dysregulation of RAS also occurs in several other tissues including those involved in regulation of glucose and whole body homeostasis as well as insulin sensitivity such as muscle, liver and pancreas and heart. Here we review the scientific evidence for these interactions and potential roles for oxidative stress, inflammation and mitochondrial dysfunction in these target tissues which may mediate effects of RAS in metabolic diseases. This article is part of a Special Issue entitled: Oxidative Stress and Mitochondrial Quality in Diabetes/Obesity and Critical Illness Spectrum of Diseases - edited by P. Hemachandra Reddy.

Liver regeneration - mechanisms and models to clinical application

Liver regeneration has been studied for many decades and the mechanisms underlying regeneration of the normal liver following resection or moderate damage are well described. A large number of factors extrinsic (such as bile acids and circulating growth factors) and intrinsic to the liver interact to initiate and regulate liver regeneration. Less well understood, and more clinically relevant, are the factors at play when the abnormal liver is required to regenerate. Fatty liver disease, chronic scarring, prior chemotherapy and massive liver injury can all inhibit the normal programme of regeneration and can lead to liver failure. Understanding these mechanisms could enable the rational targeting of specific therapies to either reduce the factors inhibiting regeneration or directly stimulate liver regeneration. Although animal models of liver regeneration have been highly instructive, the clinical relevance of some models could be improved to bridge the gap between our in vivo model systems and the clinical situation. Likewise, modern imaging techniques such as spectroscopy will probably improve our understanding of whole-organ metabolism and how this predicts the liver's regenerative capacity. This Review describes briefly the mechanisms underpinning liver regeneration, the models used to study this process, and discusses areas in which failed or compromised liver regeneration is clinically relevant.

Losartan may inhibit the progression of liver fibrosis in chronic HCV patients

BACKGROUND

Abundant experimental evidence indicates overproduction of angiotensin II in the injured liver, and a role in stimulation of hepatic stellate cell (HSC) activation and fibrogenesis thereby, representing an attractive antifibrotic target. The aim of this study was to examine the antifibrotic effect of losartan on histopathologic level in chronic HCV patients.

METHODS

A prospective study on fifty patients with chronic HCV and liver fibrosis proved by liver biopsy was conducted. They included patients who did not respond (n=36) or comply (n=2) or receive therapy due to established cirrhosis (n=10), or refused to receive (n=2) combined interferon and ribavirin therapy. They were divided randomly into 2 groups. The 1(st) group (n=25) was given losartan 50 mg OD for 1 year and the 2(nd) group (25 patients) was given silymarin, 140 mg t.i.d., (silymarin group). Liver biopsy was done at baseline and 1 year from the onset of treatment (end of study).

RESULTS

In the second liver biopsy after 1 year, the decrease in fibrosis stage was significantly different between losartan group and silymarin group (a decrease of 1.88±0.96 (50.9%) vs. 0.45±0.93 (11.7%), respectively; P<0.01). In patients treated with losartan, regression in fibrosis stage was observed in 14/16 patients vs. 2/11 in silymarin group (P<0.01). No differences were observed in inflammation grades in both groups. A significant increase in albumin and prothrombin levels and a decrease in systolic blood pressure were found in losartan but not in silymarin group (P=0.009, 0.001 & 0.018 respectively and P=0.158, 0.603 & 0.288, respectively).

CONCLUSIONS

Histopathological scores showed that losartan had an inhibitory effect on progression and even led to regression of fibrosis stage but had no effect on the grade of inflammation.

Losartan ameliorates dystrophic epidermolysis bullosa and uncovers new disease mechanisms

Genetic loss of collagen VII causes recessive dystrophic epidermolysis bullosa (RDEB)—a severe skin fragility disorder associated with lifelong blistering and disabling progressive soft tissue fibrosis. Causative therapies for this complex disorder face major hurdles, and clinical implementation remains elusive. Here, we report an alternative evidence-based approach to ameliorate fibrosis and relieve symptoms in RDEB. Based on the findings that TGF-β activity is elevated in injured RDEB skin, we targeted TGF-β activity with losartan in a preclinical setting. Long-term treatment of RDEB mice efficiently reduced TGF-β signaling in chronically injured forepaws and halted fibrosis and subsequent fusion of the digits. In addition, proteomics analysis of losartan- vs. vehicle-treated RDEB skin uncovered changes in multiple proteins related to tissue inflammation. In line with this, losartan reduced inflammation and diminished TNF-α and IL-6 expression in injured forepaws. Collectively, the data argue that RDEB fibrosis is a consequence of a cascade encompassing tissue damage, TGF-β-mediated inflammation, and matrix remodeling. Inhibition of TGF-β activity limits these unwanted outcomes and thereby substantially ameliorates long-term symptoms.

[Aspects of pathogenetc pharmacotherapy for portal hypertension in liver cirrhosis]

The review of literature considers the principles of medical treatment for portal hypertension in liver cirrhosis, which are based on the current views of its development mechanisms. It describes both current pharmacotherapy methods for portal hypertension and drugs, the efficacy of which is being investigated.

International Union of Basic and Clinical Pharmacology. XCIX. Angiotensin Receptors: Interpreters of Pathophysiological Angiotensinergic Stimuli [corrected]

The renin angiotensin system (RAS) produced hormone peptides regulate many vital body functions. Dysfunctional signaling by receptors for RAS peptides leads to pathologic states. Nearly half of humanity today would likely benefit from modern drugs targeting these receptors. The receptors for RAS peptides consist of three G-protein-coupled receptors—the angiotensin II type 1 receptor (AT1 receptor), the angiotensin II type 2 receptor (AT2 receptor), the MAS receptor—and a type II trans-membrane zinc protein—the candidate angiotensin IV receptor (AngIV binding site). The prorenin receptor is a relatively new contender for consideration, but is not included here because the role of prorenin receptor as an independent endocrine mediator is presently unclear. The full spectrum of biologic characteristics of these receptors is still evolving, but there is evidence establishing unique roles of each receptor in cardiovascular, hemodynamic, neurologic, renal, and endothelial functions, as well as in cell proliferation, survival, matrix-cell interaction, and inflammation. Therapeutic agents targeted to these receptors are either in active use in clinical intervention of major common diseases or under evaluation for repurposing in many other disorders. Broad-spectrum influence these receptors produce in complex pathophysiological context in our body highlights their role as precise interpreters of distinctive angiotensinergic peptide cues. This review article summarizes findings published in the last 15 years on the structure, pharmacology, signaling, physiology, and disease states related to angiotensin receptors. We also discuss the challenges the pharmacologist presently faces in formally accepting newer members as established angiotensin receptors and emphasize necessary future developments.