Matrix metalloproteinase inhibitor, CTS-1027, attenuates liver injury and fibrosis in the bile duct-ligated mouse

Snakebite drug discovery: high-throughput screening to identify novel snake venom metalloproteinase toxin inhibitors

Snakebite envenoming results in ∼100,000 deaths per year, with close to four times as many victims left with life-long sequelae. Current antivenom therapies have several limitations including high cost, variable cross-snake species efficacy and a requirement for intravenous administration in a clinical setting. Next-generation snakebite therapies are being widely investigated with the aim to improve cost, efficacy, and safety. In recent years several small molecule drugs have shown considerable promise for snakebite indication, with oral bioavailability particularly promising for community delivery rapidly after a snakebite. However, only two such drugs have entered clinical development for snakebite. To offset the risk of attrition during clinical trials and to better explore the chemical space for small molecule venom toxin inhibitors, here we describe the first high throughput drug screen against snake venom metalloproteinases (SVMPs)-a pathogenic toxin family responsible for causing haemorrhage and coagulopathy. Following validation of a 384-well fluorescent enzymatic assay, we screened a repurposed drug library of 3,547 compounds against five geographically distinct and toxin variable snake venoms. Our drug screen resulted in the identification of 14 compounds with pan-species inhibitory activity. Following secondary potency testing, four SVMP inhibitors were identified with nanomolar EC50s comparable to the previously identified matrix metalloproteinase inhibitor marimastat and superior to the metal chelator dimercaprol, doubling the current global portfolio of SVMP inhibitors. Following analysis of their chemical structure and ADME properties, two hit-to-lead compounds were identified. These clear starting points for the initiation of medicinal chemistry campaigns provide the basis for the first ever designer snakebite specific small molecules.

Serum matrix metalloproteinase-7 levels in infants with cholestasis and biliary atresia

Background

The aim of this study was to evaluate the serum level of matrix metalloproteinase 7 (MMP7) in infants with cholestasis and the diagnostic values of this biomarker to differentiate biliary atresia (BA) from other causes of cholestasis.

Methods

This multi-center study is conducted during 2 years in Mofid children’s hospital and Children’s Medical Center, Pediatrics Center of Excellence Tehran, Iran. 54 infants with cholestasis were enrolled in this study with a control group consists of 41 healthy infants with the same age. Serum samples were taken from all these patients to assess serum levels of MMP7, Gamma-glutamyl Transferase (GGT). For each biomarker, we calculated the sensitivity and specificity and other statistical characteristics.

Results

There were 89 subjects, 22 patients with BA, 32 patients with non-BA cholestasis and 41 subjects as control group. The mean serum MMP7 levels in BA, non-BA cholestasis and control group was 15.91 ng/ml ± 6.64, 4.73 ng/ml ± 2.59 and 0.49 ng/ml ± 0.33, respectively. The best cut-off point is calculated 7.8 ng/ml for MMP7 and 434.5 U/L for GGT. The area under curve (AUC) for these two markers are 0.988 ± 0.008 and 0.854 ± 0.052, respectively. The sensitivity and specificity of MMP7 to differentiate biliary atresia from nonbiliary atresia cholestasis in our study was 95.5% and 94.5%, respectively. The sensitivity and specificity of GGT was 77.3% and 77.8%, respectively. These results show that the MMP7 has more sensitivity and specificity in differentiation.

Conclusion

MMP7 demonstrated good accuracy to differentiate biliary atresia from other causes of cholestasis.

Identification of Zinc-Binding Inhibitors of Matrix Metalloproteinase-9 to Prevent Cancer Through Deep Learning and Molecular Dynamics Simulation Approach

The overexpression of matrix metalloproteinase-9 (MMP-9) is associated with tumor development and angiogenesis, and hence, it has been considered an attractive drug target for anticancer therapy. To assist in drug design endeavors for MMP-9 targets, an in silico study was presented to investigate whether our compounds inhibit MMP-9 by binding to the catalytic domain, similar to their inhibitor or not. For that, in the initial stage, a deep-learning algorithm was used for the predictive modeling of the CHEMBL321 dataset of MMP-9 inhibitors. Several regression models were built and evaluated based on R2, MAE MSE, RMSE, and Loss. The best model was utilized to screen the drug bank database containing 9,102 compounds to seek novel compounds as MMP-9 inhibitors. Then top high score compounds were selected for molecular docking based on the comparison between the score of the reference molecule. Furthermore, molecules having the highest docking scores were selected, and interaction mechanisms with respect to S1 pocket and catalytic zinc ion of these compounds were also discussed. Those compounds, involving binding to the catalytic zinc ion and the S1 pocket of MMP-9, were considered preferentially for molecular dynamics studies (100 ns) and an MM-PBSA (last 30 ns) analysis. Based on the results, we proposed several novel compounds as potential candidates for MMP-9 inhibition and investigated their binding properties with MMP-9. The findings suggested that these compounds may be useful in the design and development of MMP-9 inhibitors in the future.

Matrix metalloproteinase-9 inhibition or deletion attenuates portal hypertension in rodents

Liver cirrhosis and portal hypertension are accompanied by hyperdynamic circulation, angiogenesis and portosystemic collaterals. Matrix metalloproteinases (MMPs) participate in fibrogenesis and angiogenesis, however, whether they can be targeted in cirrhosis treatment is unclear. Therefore, we performed three series of experiments to investigate this issue. Liver cirrhosis was induced by common bile duct ligation (BDL) in Sprague‐Dawley rats. Sham‐operated rats served as controls. Rats were randomly allocated to receive vehicle, minocycline (a nonselective MMP inhibitor) or SB‐3CT (MMP‐2 and −9 inhibitor) for 28 days in the first and second series, respectively. MMP‐9 knockout mice were used in the third series. The results showed that minocycline ameliorated portal hypertension, hemodynamic abnormalities, reduced collateral shunting, mesenteric vascular density, plasma VEGF level and alleviated liver fibrosis. SB‐3CT attenuated portal hypertension, hemodynamic derangements, reduced shunting, mesenteric vascular density, mesenteric VEGF protein expression, and liver fibrosis. Knockout BDL mice had significantly alleviated portal hypertension, liver fibrosis, liver α‐SMA and mesenteric eNOS protein expressions compared to wild‐type BDL mice. Liver SMAD2 phosphorylation was down‐regulated in all series with MMP inhibition or knock‐out. In conclusion, MMP‐9 inhibition or deletion ameliorated the severity of cirrhosis, portal hypertension, and associated derangements. MMP‐9 may be targeted in the treatment of liver cirrhosis.

The impact of sterile inflammation in acute liver injury

BACKGROUND

The liver has a number of functions in innate immunity. These functions predispose the liver to innate immune-mediated liver injury when inflammation goes unchecked. Significant progress has been made in the last 25 years on sterile inflammatory liver injury in a number of models; however, a great deal of controversy and many questions about the nature of sterile inflammation still exist.

AIM

The goal of this article is to review sterile inflammatory liver injury using both a basic approach to what constitutes the inflammatory injury, and through examination of current models of liver injury and inflammation. This information will be tied to human patient conditions when appropriate.

RELEVANCE FOR PATIENTS

Inflammation is one of the most critical factors for managing in-patient liver disease in a number of scenarios. More information is needed for both scientists and clinicians to develop rational treatments.

Protective effects of Ginsenoside Rg1 against carbon tetrachloride-induced liver injury in mice through suppression of inflammation

BACKGROUND

AMP-activated protein kinase (AMPK) is one of the principal cellular energy sensors participating in maintenance of energy balance but recent evidences also suggested that AMPK might be involved in the regulation of inflammation.

STUDY DESIGN/METHODS

Ginsenoside Rg1 (Rg1) was used to investigate the potential roles of AMPK in carbon tetrachloride (CCl4)-induced hepato-toxicity. The experimental data indicated that treatment with Rg1 significantly decreased the elevation of plasma aminotransferases and alleviated hepatic histological abnormalities in CCl4-exposed mice. Treatment with Rg1 also inhibited the increase of myeloperoxidase (MPO) and malondialdehyde (MDA), the induction of TNF-α, IL-6, inducible nitric oxide synthase (iNOS), nitric oxide and the upregulation of matrix metalloproteinase 2 (MMP-2), MMP-3 and MMP-9 in mice exposed to CCl4. These effects were associated with suppressed nuclear accumulation of NF-κB p65.

CONCLUSION

These results indicated that Rg1 effectively suppressed the inflammatory responses and alleviated liver damage induced by CCl4, implying that AMPK activation might be beneficial for ameliorating inflammation-based liver damage.

Role of matrix metalloproteinases in cholestasis and hepatic ischemia/reperfusion injury: A review

Matrix metalloproteinases (MMPs) are a family of proteases using zinc-dependent catalysis to break down extracellular matrix (ECM) components, allowing cell movement and tissue reorganization. Like many other proteases, MMPs are produced as zymogens, an inactive form, which are activated after their release from cells. Hepatic ischemia/reperfusion (I/R) is associated with MMP activation and release, with profound effects on tissue integrity: their inappropriate, prolonged or excessive expression has harmful consequences for the liver. Kupffer cells and hepatic stellate cells can secrete MMPs though sinusoidal endothelial cells are a further source of MMPs. After liver transplantation, biliary complications are mainly attributable to cholangiocytes, which, compared with hepatocytes, are particularly susceptible to injury and ultimately a major cause of increased graft dysfunction and patient morbidity. This paper focuses on liver I/R injury and cholestasis and reviews factors and mechanisms involved in MMP activation together with synthetic compounds used in their regulation. In this respect, recent data have demonstrated that the role of MMPs during I/R may go beyond the mere destruction of the ECM and may be much more complex than previously thought. We thus discuss the role of MMPs as an important factor in cholestasis associated with I/R injury.

Mechanisms of microRNAs in regulation of apoptosis in non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) has become a common liver disease in Western developed countries, and the prevalence is also continuously increasing in developing countries. NAFLD comprises a spectrum of disease stages, in which simple steatosis is a benign course and steatohepatitis can progress to liver fibrosis, cirrhosis and even hepatocellular carcinoma. The pathogenesis of NAFLD has not been fully understood. As noncoding RNA molecules, microRNAs (miRNAs) regulate the pathophysiological processes including development, metabolism, cell proliferation, differentiation, apoptosis and carcinogenesis, as well as the pathogenesis of NAFLD. miRNAs extensively participate in insulin resistance, lipid metabolic disorder, endoplasmic injury and cell apoptosis in NAFLD. This review highlights the roles of miRNAs in cell apoptosis in NAFLD.

Strategies to prevent and reverse liver fibrosis in humans and laboratory animals

Liver fibrosis results from chronic damage to the liver in conjunction with various pathways and is mediated by a complex microenvironment. Based on clinical observations, it is now evident that fibrosis is a dynamic, bidirectional process with an inherent capacity for recovery and remodeling. The major mechanisms involved in liver fibrosis include the repetitive injury of hepatocytes, the activation of the inflammatory response after injury stimulation, and the activation and proliferation of hepatic stellate cells (HSCs), which represents the major extracellular matrix (ECM)-producing cells, stimulated by hepatocyte injury and inflammation. The microenvironment in the liver is synergistically regulated abnormal ECM deposition, scar formation, angiogenesis, and fibrogenesis. Moreover, recent studies have clarified novel mechanism in fibrosis such as epigenetic regulation of HSCs, the leptin and PPARγ pathways, the coagulation system, and even autophagy. Uncovering the mechanisms of liver fibrogenesis provides a basis to develop potential therapies to reverse and treat the fibrotic response, thereby improving the outcomes of patients with chronic liver disease. Although both scientific and clinical challenges remain, emerging studies attempt to reveal the ideal anti-fibrotic drug that could be easily delivered to the liver with high specificity and low toxicity. This review highlights the mechanisms, including novel pathways underlying fibrogenesis that may be translated into preventive and treatment strategies, reviews both current and novel agents that target specific pathways or multiple targets, and discusses novel drug delivery systems such as nanotechnology that can be applied in the treatment of liver fibrosis. In addition, we also discuss some current treatment strategies that are being applied in animal models and in clinical trials.

The matrix metalloproteinase inhibitor RS-130830 attenuates brain injury in experimental pneumococcal meningitis

Background

Pneumococcal meningitis (PM) is characterized by high mortality and morbidity including long-term neurofunctional deficits. Neuropathological correlates of these sequelae are apoptosis in the hippocampal dentate gyrus and necrosis in the cortex. Matrix metalloproteinases (MMPs) play a critical role in the pathophysiology of PM. RS-130830 (Ro-1130830, CTS-1027) is a potent partially selective inhibitor of MMPs of a second generation and has been evaluated in clinical trials as an anti-arthritis drug. It inhibits MMPs involved in acute inflammation but has low activity against MMP-1 (interstitial collagenase), MMP-7 (matrilysin) and tumour necrosis factor α converting enzyme (TACE).

Methods

A well-established infant rat model of PM was used where live Streptococcus pneumoniae were injected intracisternally and antibiotic treatment with ceftriaxone was initiated 18 h post infection (hpi). Treatment with RS-130830 (75 mg/kg bis in die (bid) i.p., n = 40) was started at 3 hpi while control littermates received the vehicle (succinylated gelatine, n = 42).

Results

Cortical necrosis was significantly attenuated in animals treated with RS-130830, while the extent of hippocampal apoptosis was not influenced. At 18 hpi, concentrations of interleukin (IL)-1β and IL-10 were significantly lower in the cerebrospinal fluid of treated animals compared to controls. RS-130830 significantly reduced weight loss and leukocyte counts in the cerebrospinal fluid of survivors of PM.

Conclusion

This study identifies MMP inhibition, specifically with RS-130830, as an efficient strategy to attenuate disease severity and cortical brain injury in PM.

5-Aminoimidazole-4-carboxamide-1-β-d-ribofuranoside alleviated carbon tetrachloride-induced acute hepatitis in mice

AMP-activated protein kinase (AMPK) is one of the principal cellular energy sensors participating in maintenance of energy balance but recent evidences also suggested that AMPK might be involved in the regulation of inflammation. In the present study, the AMPK activator 5-aminoimidazole-4-carboxamide-1-β-d-ribofuranoside (AICAR) was used to investigate the potential roles of AMPK in carbon tetrachloride (CCl4)-induced acute hepatitis. The experimental data indicated that treatment with AICAR significantly decreased the elevation of plasma aminotransferases and alleviated hepatic histological abnormalities in CCl4-exposed mice. Treatment with AICAR also inhibited the increase of myeloperoxidase (MPO), the induction of TNF-α, IL-6, inducible nitric oxide synthase (iNOS), nitric oxide and the upregulation of matrix metalloproteinase 2 (MMP-2), MMP-3 and MMP-9 in mice exposed to CCl4. These effects were associated with suppressed nuclear accumulation of NF-κB p65. These results indicated that the AMPK activator AICAR effectively suppressed the inflammatory responses and alleviated liver damage induced by CCl4, implying that AMPK activation might be beneficial for ameliorating inflammation-based liver damage.

The potential protective effect of Physalis peruviana L. against carbon tetrachloride-induced hepatotoxicity in rats is mediated by suppression of oxidative stress and downregulation of MMP-9 expression

The active constituent profile in Cape gooseberry (Physalis peruviana L.) juice was determined by GC-MS. Quercetin and kaempferol were active components in the juice. In this study we have evaluated its potential protective effect on hepatic injury and fibrosis induced by carbon tetrachloride (CCl4). Twenty-eight rats divided into 4 groups: Group I served as control group, and Group II received weekly i.p. injection of 2 mL CCl4/kg bwt for 12 weeks. Group III were supplemented with Physalis juice via the drinking water. The animals of Group IV received Physalis juice as Group III and also were intraperitoneally injected weekly with 2 mL CCl4/kg bwt for 12 weeks. Hepatoprotective effect was evaluated by improvement in liver enzymes serum levels, reduction in collagen areas, downregulation in expression of the fibrotic marker MMP-9, reduction in the peroxidative marker malonaldehyde and the inflammatory marker nitric oxide, and restoration of the activity of antioxidant enzymatic and nonenzymatic systems, namely, glutathione content, superoxide dismutase, catalase, glutathione-S-transferase, glutathione peroxidase, and glutathione reductase activities. The results show that the potential hepatoprotective effects of Physalis peruviana may be due to physalis acts by promotion of processes that restore hepatolobular architecture and through the inhibition of oxidative stress pathway.

Osteopontin is an initial mediator of inflammation and liver injury during obstructive cholestasis after bile duct ligation in mice

Osteopontin (OPN) is a chemotactic factor which can be cleaved to the pro-inflammatory form by matrix metalloproteinases (MMPs). To test the hypothesis that OPN can modulate inflammatory liver injury during cholestasis, wild-type (WT) C57BL/6 and OPN knockout (OPN-KO) mice underwent bile duct ligation (BDL). OPN-KO mice showed significant reduction in liver injury (plasma ALT and necrosis) and neutrophil recruitment compared with WT animals at 24h but not 72h after BDL. In WT mice, a 4-fold increase in hepatic MMP-3 mRNA and elevated MMP activities and cleaved OPN levels were observed in bile. WT mice subjected to BDL in the presence of the MMP inhibitor BB-94 showed reduced liver injury, less neutrophil extravasation and diminished levels of cleaved OPN in bile. Thus, during obstructive cholestasis, OPN released from biliary epithelial cells could be cleaved by MMPs in bile. When the biliary system leaks, cleaved OPN enters the parenchyma and attracts neutrophils. In the absence of OPN, other chemoattractants, e.g. chemokines, mediate a delayed inflammatory response and injury. Taken together, our data suggest that OPN is the pro-inflammatory mediator that initiates the early neutrophil-mediated injury phase during obstructive cholestasis in mice.

Selective inhibition of tumor necrosis factor-α converting enzyme attenuates liver toxicity in a murine model of concanavalin A induced auto-immune hepatitis

Emerging evidence suggest that tumor necrosis factor (TNF)-α plays a major role in pathogenesis of auto-immune hepatitis (AIH) induced liver injury. Blockade of TNF-α synthesis or bio-activity protects against experimental AIH. TNF-α converting enzyme (TACE) is a member of the ADAM (a disintegrin and metalloproteinase) family which processes precursor TNF-α to release soluble TNF-α. We hypothesized that selective inhibition of TACE might protect AIH. To investigate this, we studied the effects of a selective TACE inhibitor DPC-333 on murine model of liver injury and fibrosis induced with concanavalin A (Con A). Pre-treatment with DPC-333 significantly suppressed plasma alanine transaminase, aspartate transaminase and cytokines such as TNF-α, interferon (IFN)-γ, interleukin (IL)-2 and IL-6 levels due to acute Con A challenge. Interestingly; DPC-333 inhibited liver poly (ADP-ribose) polymerase (PARP)-1 activity which was associated with reduced number of necrotic hepatocytes in histological examination and mortality associated with Con A. In fibrosis study, repeated Con A administration significantly up-regulated liver collagen deposition as assessed by measurement of hydroxyproline content which was further confirmed in liver histology with Masson's trichrome staining. Treatment with 30mg/kg of DPC-333 was able to suppress liver hydroxyproline and fibrous tissue proliferation which corroborated well with inhibition in expression of pro-fibrotic genes such as tissue inhibitor of metalloproteinase (TIMP)-1 and transforming growth factor (TGF)-β1. These observations suggest that selective TACE inhibition is an effective approach for the treatment of both immune mediated hepatic inflammation and fibrosis.

Hepatoprotective effect of MMP-19 deficiency in a mouse model of chronic liver fibrosis

Liver fibrosis is characterized by the deposition and increased turnover of extracellular matrix. This process is controlled by matrix metalloproteinases (MMPs), whose expression and activity dynamically change during injury progression. MMP-19, one of the most widely expressed MMPs, is highly expressed in liver; however, its contribution to liver pathology is unknown. The aim of this study was to elucidate the role of MMP-19 during the development and resolution of fibrosis by comparing the response of MMP-19-deficient (MMP19KO) and wild-type mice upon chronic liver CCl(4)-intoxication. We show that loss of MMP-19 was beneficial during liver injury, as plasma ALT and AST levels, deposition of fibrillar collagen, and phosphorylation of SMAD3, a TGF-ß1 signaling molecule, were all significantly lower in MMP19KO mice. The ameliorated course of the disease in MMP19KO mice likely results from a slower rate of basement membrane destruction and ECM remodeling as the knockout mice maintained significantly higher levels of type IV collagen and lower expression and activation of MMP-2 after 4 weeks of CCl(4)-intoxication. Hastened liver regeneration in MMP19KO mice was associated with slightly higher IGF-1 mRNA expression, slightly increased phosphorylation of Akt kinase, decreased TGF-ß1 mRNA levels and significantly reduced SMAD3 phosphorylation. In addition, primary hepatocytes isolated from MMP19KO mice showed impaired responsiveness towards TGF-ß1 stimulation, resulting in lower expression of Snail1 and vimentin mRNA. Thus, MMP-19-deficiency improves the development of hepatic fibrosis through the diminished replacement of physiological extracellular matrix with fibrotic deposits in the beginning of the injury, leading to subsequent changes in TGF-ß and IGF-1 signaling pathways.

Role of stress-induced NKG2D ligands in liver diseases

Cell death by apoptosis is a prominent feature in a variety of liver diseases. It is likely that apoptosis is the initial cellular response to hepatocyte and biliary injury, which then leads to the initiation of cellular and cytokine cascades culminating in hepatocyte death with subsequent fibrosis and cirrhosis. This sequence of events is of paramount clinical importance. Recently, soluble forms of the major histocompatibility complex class I-related chains A and closely related B (MIC A and B) were reported to be increased in patients with a variety of liver diseases. MIC A and B are cell surface glycoproteins that function as indicators for cellular stress and thus activate circulating cytotoxic natural killer (NK) cells. The interaction between MIC A and B with their cognate receptor natural killer group 2 member D (NKG2D) culminates in enhanced liver cell death, which is mediated in part by apoptotic mechanisms. The present overview focuses on the role of the stress-induced NKG2D ligands MIC A and B in diverse liver diseases. Critical insights into these complex relations may help to promote rationally based therapies in liver diseases. Importantly, we hope that this overview will help to stimulate further studies into mechanisms by which stress ligands mediate cell death and its sequale.

Apoptosis in nonalcoholic fatty liver disease: diagnostic and therapeutic implications

Pathological increases in cell death in the liver as well as in peripheral tissues has emerged as an important mechanism involved in the development and progression of nonalcoholic fatty liver disease (NAFLD). An increase in hepatocyte cell death by apoptosis is typically present in patients with NAFLD and in experimental models of steatohepatitis, while an increase in adipocyte cell death in visceral adipose tissue may be an important mechanism triggering insulin resistance and hepatic steatosis. The two fundamental pathways of apoptosis, the extrinsic (death receptor-mediated) and intrinsic (organelle-initiated) pathways, are both involved. This article summarizes the current knowledge related to the distinct molecular and biochemical pathways of cell death involved in NAFLD pathogenesis. In particular, it will highlight the efforts for the development of both novel diagnostic and therapeutic strategies based on this knowledge.

Hepatocyte death: a clear and present danger

The hepatocyte is especially vulnerable to injury due to its central role in xenobiotic metabolism including drugs and alcohol, participation in lipid and fatty acid metabolism, its unique role in the enterohepatic circulation of bile acids, the widespread prevalence of hepatotropic viruses, and its existence within a milieu of innate immune responding cells. Apoptosis and necrosis are the most widely recognized forms of hepatocyte cell death. The hepatocyte displays many unique features regarding cell death by apoptosis. It is quite susceptible to death receptor-mediated injury, and its death receptor signaling pathways involve the mitochondrial pathway for efficient cell killing. Also, death receptors can trigger lysosomal disruption in hepatocytes which further promote cell and tissue injury. Interestingly, hepatocytes are protected from cell death by only two anti-apoptotic proteins, Bcl-x(L) and Mcl-1, which have nonredundant functions. Endoplasmic reticulum stress or the unfolded protein response contributes to hepatocyte cell death during alterations of lipid and fatty acid metabolism. Finally, the current information implicating RIP kinases in necrosis provides an approach to more fully address this mode of cell death in hepatocyte injury. All of these processes contributing to hepatocyte injury are discussed in the context of potential therapeutic strategies.

Broad-spectrum matrix metalloproteinase inhibition curbs inflammation and liver injury but aggravates experimental liver fibrosis in mice

Background

Liver fibrosis is characterized by excessive synthesis of extracellular matrix proteins, which prevails over their enzymatic degradation, primarily by matrix metalloproteinases (MMPs). The effect of pharmacological MMP inhibition on fibrogenesis, however, is largely unexplored. Inflammation is considered a prerequisite and important co-contributor to fibrosis and is, in part, mediated by tumor necrosis factor (TNF)-α-converting enzyme (TACE). We hypothesized that treatment with a broad-spectrum MMP and TACE-inhibitor (Marimastat) would ameliorate injury and inflammation, leading to decreased fibrogenesis during repeated hepatotoxin-induced liver injury.

Methodology/Principal Findings

Liver fibrosis was induced in mice by repeated carbon tetrachloride (CCl4) administration, during which the mice received either Marimastat or vehicle twice daily. A single dose of CCl₄ was administered to investigate acute liver injury in mice pretreated with Marimastat, mice deficient in Mmp9, or mice deficient in both TNF-α receptors. Liver injury was quantified by alanine aminotransferase (ALT) levels and confirmed by histology. Hepatic collagen was determined as hydroxyproline, and expression of fibrogenesis and fibrolysis-related transcripts was determined by quantitative reverse-transcription polymerase chain reaction. Marimastat-treated animals demonstrated significantly attenuated liver injury and inflammation but a 25% increase in collagen deposition. Transcripts related to fibrogenesis were significantly less upregulated compared to vehicle-treated animals, while MMP expression and activity analysis revealed efficient pharmacologic MMP-inhibition and decreased fibrolysis following Marimastat treatment. Marimastat pre-treatment significantly attenuated liver injury following acute CCl₄-administration, whereas Mmp9 deficient animals demonstrated no protection. Mice deficient in both TNF-α receptors exhibited an 80% reduction of serum ALT, confirming the hepatoprotective effects of Marimastat via the TNF-signaling pathway.

Conclusions/Significance

Inhibition of MMP and TACE activity with Marimastat during chronic CCl₄ administration counterbalanced any beneficial anti-inflammatory effect, resulting in a positive balance of collagen deposition. Since effective inhibition of MMPs accelerates fibrosis progression, MMP inhibitors should be used with caution in patients with chronic liver diseases.

An update on cholangiocarcinoma associated with primary sclerosing cholangitis

PURPOSE OF REVIEW

Primary sclerosing cholangitis (PSC) is being diagnosed with increasing frequency. The most feared complication is the presence or development of cholangiocarcinoma (CCA). The present review summarizes recent data with regards to diagnosis, pathobiology and treatment.

RECENT FINDINGS

Several investigations have focused on aspects of the molecular biology of CCA in general; such data should be explored now in the context of PSC-related CCA to yield new diagnostic markers and approaches for therapy.

SUMMARY

CCA has to be suspected in any new PSC patient presenting with jaundice. Exploration should include carbohydrate antigen19-9 and two imaging techniques. Endoscopic cholangioscopy might become very rewarding. Important progress has been achieved in liver transplantation by the use of preoperative radio-chemotherapy. Molecular biology points to inflammation-induced cytokines with mutagenic action and to the relevance of extracellular matrix proteins for invasion but also for proliferation. Micro-RNAs prove to be very important in the control of cell proliferation, differentiation and apoptosis. Mutated p53, cyclins, wnt/beta-catenin signaling, proliferation indices, mucins, carbohydrate antigen19-9, CRP and aneuploidy appear to hold significant potential as predictors of outcome in CCA. It is expected that the further unraveling of these molecular processes will ultimately lead to development of tests allowing early diagnosis and to development of medical approaches to retard tumor formation or recurrence following surgical interventions.

Major histocompatibility complex class I-related chains A and B (MIC A/B): a novel role in nonalcoholic steatohepatitis

Stress-induced soluble major histocompatibility complex class I-related chains A/B (MIC A/B) are increased in chronic liver diseases and hepatocellular malignancy. We investigated the impact of these molecules on liver injury, apoptosis, and fibrosis in nonalcoholic steatohepatitis (NASH). Blood and liver tissue were obtained from 40 patients with NASH undergoing bariatric surgery for obesity. The control group consisted of 10 healthy individuals. We also investigated 10 patients with nonalcoholic fatty liver (NAFL). Polymerase chain reaction was used to measure messenger RNA (mRNA) transcripts of MIC A/B, natural killer cell receptor G2D (NKG2D), CD95/Fas, and tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-death receptor 5 (DR5). Apoptosis was quantified by way of terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) (intrahepatic) and M30/M65 (systemic). Liver injury was assessed histopathologically and serologically (alanine aminotransferase/aspartate aminotransferase). Fibrosis was identified by Sirius red staining, quantitative morphometry, and alpha-smooth muscle actin and collagen 1alpha transcripts. Compared with controls, patients with NASH revealed significant increases in (1) NKG2D mRNA (13.1-fold) and MIC A/B mRNA (3.6-fold and 15.8-fold, respectively); (2) TRAIL-DR5 and CD95/Fas mRNA (2.7-fold and 3.6-fold, respectively); (3) TUNEL-positive hepatocytes (4.0-fold); and (4) M30 and M65 levels (4.6-fold and 3.4-fold, respectively). We found relevant correlations between MIC protein expression rates and NAS and fibrosis stages. In contrast, NKG2D and MIC A/B transcripts were attenuated in patients with NAFL compared with NASH. Histopathologically, NASH patients revealed increased NAS scores, an accumulation of natural killer cells, and 2.7-fold increased hepatic fibrosis by quantitative morphometry.

CONCLUSION

Our findings suggest an important role for MIC A/B in liver injury. Therapeutic intervention aimed at reducing MIC A/B levels may beneficially affect the progression of NASH.