Arsenite induced oxidative damage in mouse liver is associated with increased cytokeratin 18 expression

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.

Serum cytokeratin-18 and its relation to liver fibrosis and steatosis diagnosed by FibroScan and controlled attenuation parameter in nonalcoholic fatty liver disease and hepatitis C virus patients

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) has emerged as the most common cause of chronic liver disease worldwide. Multiple diagnostic noninvasive methods for NAFLD were studied (both serological and imaging), either single or combined. Attention has been focused on cytokeratin-18 (CK18) as a novel serological marker for the diagnosis of steatosis/fibrosis in NAFLD and hepatitis C virus (HCV) patients.

AIM

The aim of this study was to evaluate serum CK18 in NAFLD and HCV fibrosis/steatosis and also to correlate its performance with the diagnostic accuracy of transient elastography (TE) and controlled attenuation parameter (CAP) in the diagnosis of fibrosis/steatosis in these patients.

PATIENTS AND METHODS

Three equal groups of participants were enrolled (n=135): group I included patients with chronic HCV, group II included NAFLD patients, and group III included control participants. For all groups, TE/CAP and labs including serum CK18 were performed. Liver biopsy was performed for the NAFLD group.

RESULTS

Serum CK18 was significantly higher in the NAFLD group (19.01±3.49 ng/ml) versus the HCV group (8.95±1.06 ng/ml) and the control group (4.83±1.6 ng/ml) (P<0.001). The CK18 levels in biopsy stages (steatosis, ballooning, inflammation, and fibrosis) and FibroScan/CAP degrees showed that CK18 increased significantly with steatosis and fibrosis stages (biopsy or FibroScan/CAP), but did not reach significance with ballooning or inflammation grades. CK18 was significantly different in nonalcoholic steatohepatitis versus non-nonalcoholic steatohepatitis patients (P=0.041). The best CK18 cutoff to detect steatosis (S≥2) in NAFLD and HCV was 11.65 and 6.84 ng/ml, respectively with an overall sensitivity and specificity over 97%. The CK18 cutoff for significant fibrosis (F≥2) by FibroScan in the NAFLD/HCV groups was 9.115 ng/ml, with 62.5%/69.2% sensitivity/specificity (P=0.031). However, inflammation had a cutoff with a marginal P value (P=0.080), and a reliable cutoff for ballooning was not attained (P=0.386). There was a positive correlation between CK18 and fibrosis (by FibroScan) in the NAFLD and HCV groups (P<0.05). The correlation between CK18 and steatosis in CAP and the nonalcoholic fatty liver disease activity score was very good (P<0.001).

CONCLUSION

Serum CK18 is related strongly to the development/progression of NAFLD and HCV-related fibrosis/steatosis. TE was correlated highly with liver biopsy results. The combination of CK18 with other noninvasive modalities increases the diagnostic yield of these tests.

Association Between Serum CK-18 Levels and the Degree of Liver Damage in Fructose-Induced Metabolic Syndrome

BACKGROUND

The pathogenesis of nonalcoholic fatty liver disease as a component of metabolic syndrome (MetS) involves the activation of apoptosis in steatotic hepatocytes. Caspase-generated fragments such as cytokeratin-18 (CK-18) in patients with various hepatic impairments are investigated as markers for diagnosis and assessment of disease severity. The goal of the study was to capture early biomarkers of apoptosis and elucidate their role in assessing the presence and extent of hepatic damage in a MetS model.

MATERIALS AND METHODS

We used male Wistar rats, divided into two groups (n = 7): control and high-fructose drinking (HFD) (35% fructose corn syrup for 16 weeks). Metabolic disorders and liver damage were studied by histochemistry (hematoxylin and eosin), immunohistochemical, immunological, and biochemical testing.

RESULTS

Our results showed significant increase in liver and serum levels of CK-18 and pro/antiapoptotic Bax/Bcl2 ratio, and decreased levels of HMGB1 (marker of necrosis) in the HFD group when compared with the control. All HFD rats developed obesity, hyperglycemia, hepatomegaly, microvesicular steatosis, an imbalance in hepatic antioxidative defense by measuring malondialdehyde and sulfhydryl groups (SH) with no inflammation and fibrosis, elevated serum levels of triglycerides, tumor necrosis factor alpha (TNF-α), and C-reactive protein without changes in serum aminotransferase levels relative to the control group. As a result of the applied regression analysis, we have determined that the variables TNF-α (0.92) and SH (0.659) have a strong complex effect on hepatic CK-18 levels with predicted value of the model R = 0.9.

CONCLUSION

The elevated CK-18 serum levels in the HFD group and their association with the histological changes in the liver and biochemical indicators demonstrate the key role of apoptosis in the pathogenesis of HFD-induced liver damage and the reliability of CK-18 as a biomarker for noninvasive assessment of liver damages in MetS.

ABCA1 Is Coordinated with ABCB1 in the Arsenic-Resistance of Human Cells

Arsenic is one of the most widespread global environmental toxicants associated with endemic poisoning. ATP-binding cassette (ABC) proteins are transmembrane channels that transport and dispose of lipids and metabolic products across the plasma membrane. The majority of ABC family members (including ABCB1 and ABCC1) are reported to play a role in the development of arsenic and drug resistance in mammals. Previously, we established a human arsenic-resistant ECV-304 (AsRE) cell line and identified ABCA1 as a novel arsenic resistance gene. In the current study, we further investigated the potential contribution of ABCA1, ABCB1, and ABCC1 to arsenic resistance through measurement of survival rates and arsenic accumulation in AsRE cells with RNA interference. The arsenic resistance capacity of ABCC1 was the strongest among the three genes, while those of ABCA1 and ABCB1 were similar. Double or triple gene knockdown of ABCA1, ABCB1, and ABCC1 via RNA interference led to a decrease significant in arsenic resistance when ABCA1/ABCB1 or ABCB1/ABCC1 were simultaneously silenced. Interestingly, no differences were evident between cells with ABCA1/ABCC1 and ABCC1 only knockdown. Our findings suggest that ABCA1 and ABCB1 proteins display similar arsenic resistance capabilities and possibly coordinate to promote arsenic resistance in AsRE cells.

In vitro and in vivo study of the application of volvox spheres to co-culture vehicles in liver tissue engineering

Volvox sphere is a biomimetic concept of a natural Volvox, wherein a large outer sphere contains smaller inner spheres, which can encapsulate cells and provide a double-layer three-dimensional environment for culturing cells. This study simultaneously encapsulated rat mesenchymal stem cells (MSCs) and AML12 hepatocytes in volvox spheres and extensively evaluated the effects of various culturing modes on cell functions and fates. The results showed that compared with a static flask culture, MSCs encapsulated in volvox spheres differentiated into hepatocyte-like cells with a 2-fold increase in albumin (ALB) expression and a 2.5-fold increase in cytokeratin 18 expression in a dynamic bioreactor. Moreover, the restorative effects of volvox spheres encapsulating cells on retrorsine-exposed CCl₄-induced liver injuries in rats were evaluated. The data presented significant reductions in AST and ALT levels after the implantation of volvox spheres encapsulating both MSCs and AML12 hepatocytes in vivo. In contrast to the negative control group, histopathological analysis demonstrated liver repair and formation of the new liver tissue in groups implanted with volvox spheres containing cells. These results demonstrate that liver cells implanted with volvox spheres encapsulating both MSCs and AML12 hepatocytes promote liver repair and liver tissue regeneration in liver failure caused by necrotizing agents such as retrorsine and CCl₄. Hence, volvox spheres encapsulating MSCs and liver cells can be a promising and clinically effective therapy for liver injury.

STATEMENT OF SIGNIFICANCE

In this study, we used a volvox sphere, which is a unique design that mimics the natural Volvox, that consists of a large outer sphere that contains smaller inner spheres, which provide a three-dimensional environment to culture cells. The purpose of this study is to co-culture mesenchymal stem cells (MSCs) and AML12 liver cells in volvox spheres and evaluate two different culture methods, dynamic bioreactor and static culture flask,on the cultured cells. In addition, we aimed to evaluate the restorative effects of volvox spheres encapsulating MSCs and/or AML12 liver cells on rats with retrorsine-exposed CCl₄-induced liver injuries. The results showed that MSCs encapsulated in volvox spheres differentiated into hepatocyte-like cells with a 2-fold increase in albumin expression and a 2.5-fold increase in cytokeratin 18 expression ina dynamic bioreactor. Moreover, the data presented significant reductions in AST and ALT levels after the implantation of volvox spheres encapsulating both MSCs and AML12 hepatocytes in vivo. In contrast to the negative control group, histopathological analysis demonstrated liver repair and formation of new liver tissue in groups implanted with volvox spheres containing cells. These results demonstrate that liver cells implanted with volvox spheres encapsulating both MSCs and AML12 hepatocytes promote liver repair and liver tissue regeneration in liver failure caused by necrotizing agents such as retrorsine and CCl₄. Hence, volvox spheres encapsulating MSCs and liver cells can be a promising and clinically effective therapy for liver injury.

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.

Dioscin, a natural steroid saponin, shows remarkable protective effect against acetaminophen-induced liver damage in vitro and in vivo

The aim of the study was to investigate the protective effect of dioscin against APAP-induced hepatotoxicity. In the in vitro tests, HepG2 cells were given APAP pretreatment with or without dioscin. In the in vivo experiments, mice were orally administrated dioscin for five days and then given APAP. Some biochemical and morphology parameters were assayed and the possible mechanism was investigated. Dioscin improved AST release, mitochondrial dysfunction, apoptosis and necrosis of HepG2 cells induced by APAP. Following administration of dioscin, APAP-induced hepatotoxicity in mice was significantly attenuated. Furthermore, the liver cell apoptosis and necrosis, and hepatic mitochondrial edema were also prevented. Fifteen differentially expressed proteins were found by using proteomics, and six of them, Suox, Krt18, Rgn, Prdx1, MDH and PNP were validated. These proteins may be involved in the hepatoprotective effect of dioscin and might cooperate with the levels of Ca(2+) in mitochondria, decreased expression of ATP2A2, and decreased mitochondrial cardiolipin. In addition, dioscin inhibited APAP-induced activation and expression of CYP2E1, up-regulated the expression of Bcl-2 and Bid, and inhibited the expression of Bax, Bak and p53. Dioscin showed a remarkable protective effect against APAP-induced hepatotoxicity by adjusting mitochondrial function. These results indicated that dioscin has the capability on the treatment of liver injury.

Proteome profiling reveals potential toxicity and detoxification pathways following exposure of BEAS-2B cells to engineered nanoparticle titanium dioxide

Oxidative stress is known to play important roles in engineered nanomaterial-induced cellular toxicity. However, the proteins and signaling pathways associated with the engineered nanomaterial-mediated oxidative stress and toxicity are largely unknown. To identify these toxicity pathways and networks that are associated with exposure to engineered nanomaterials, an integrated proteomic study was conducted using human bronchial epithelial cells, BEAS-2B and nanoscale titanium dioxide. Utilizing 2-DE and MS, we identified 46 proteins that were altered at protein expression levels. The protein changes detected by 2-DE/MS were verified by functional protein assays. These identified proteins include some key proteins involved in cellular stress response, metabolism, adhesion, cytoskeletal dynamics, cell growth, cell death, and cell signaling. The differentially expressed proteins were mapped using Ingenuity Pathway Analyses™ canonical pathways and Ingenuity Pathway Analyses tox lists to create protein-interacting networks and proteomic pathways. Twenty protein canonical pathways and tox lists were generated, and these pathways were compared to signaling pathways generated from genomic analyses of BEAS-2B cells treated with titanium dioxide. There was a significant overlap in the specific pathways and lists generated from the proteomic and the genomic data. In addition, we also analyzed the phosphorylation profiles of protein kinases in titanium dioxide-treated BEAS-2B cells for a better understanding of upstream signaling pathways in response to the titanium dioxide treatment and the induced oxidative stress. In summary, the present study provides the first protein-interacting network maps and novel insights into the biological responses and potential toxicity and detoxification pathways of titanium dioxide.

Serum fragmented cytokeratin 18 levels reflect the histologic activity score of nonalcoholic fatty liver disease more accurately than serum alanine aminotransferase levels

BACKGROUND AND GOALS

Reliable noninvasive biomarkers to assess the histologic activity of nonalcoholic fatty liver disease (NAFLD) have not been established. As the frequency of Mallory bodies is known to be closely associated with the disease severity, we hypothesized that serum levels of Mallory body-related proteins were correlated with NAFLD histologic activity and evaluated this possibility.

STUDY

Serum levels of total and fragmented cytokeratin (CK) 18, heat shock protein (Hsp) 70, Hsp90alpha, ubiquitin+1, and p38alpha at the time of liver biopsy were measured in 118 NAFLD patients and their association with histologic findings and NAFLD histologic activity score (NAS) was investigated.

RESULTS

Serum levels of both forms of CK18 and Hsp90alpha were markedly higher in patients having nonalcoholic steatohepatitis (NASH) compared with non-NASH ones. Both forms of CK18 significantly correlated with degree of steatosis, lobular inflammation, and ballooning, and showed stronger positive correlations with NAS than serum aspartate and alanine aminotransferase (AST and ALT). Multiple regression analysis further revealed that fragmented CK18 and AST were effective predictors of NAS, with the former being the more definitive of the two (P<0.001 vs. 0.005). In 20 NAFLD patients who received a follow-up biopsy, changes in fragmented CK18 levels, but not AST or ALT levels, closely paralleled those in NAS.

CONCLUSIONS

These results establish the usefulness of fragmented CK18 measurement for assessing and monitoring the histologic activity of NAFLD.

Intermediate filaments take the heat as stress proteins

Intermediate filament (IF) proteins and heat shock proteins (HSPs) are large multimember families that share several features, including protein abundance, significant upregulation in response to a variety of stresses, cytoprotective functions, and the phenocopying of several human diseases after IF protein or HSP mutation. We are now coming to understand that these common elements point to IFs as important cellular stress proteins with some roles akin to those already well-characterized for HSPs. Unique functional roles for IFs include protection from mechanical stress, whereas HSPs are characteristically involved in protein folding and as chaperones. Shared IF and HSP cytoprotective roles include inhibition of apoptosis, organelle homeostasis, and scaffolding. In this report, we review data that corroborate the view that IFs function as highly specialized cytoskeletal stress proteins that promote cellular organization and homeostasis.

Aberrant cytokeratin expression during arsenic-induced acquired malignant phenotype in human HaCaT keratinocytes consistent with epidermal carcinogenesis

Inorganic arsenic is a known human skin carcinogen. Chronic arsenic exposure results in various human skin lesions, including hyperkeratosis and squamous cell carcinoma (SCC), both characterized by distorted cytokeratin (CK) production. Prior work shows the human skin keratinocyte HaCaT cell line, when exposed chronically for >25 weeks to a low level of inorganic arsenite (100nM) results in cells able to produce aggressive SCC upon inoculation into nude mice. In the present study, CK expression analysis was performed in arsenic-exposed HaCaT cells during the progressive acquisition of this malignant phenotype (0-20 weeks) to further validate this model as relevant to epidermal carcinogenesis induced by arsenic in humans. Indeed, we observed clear evidence of acquired cancer phenotype by 20 weeks of arsenite exposure including the formation of giant cells, a >4-fold increase in colony formation in soft agar and a approximately 2.5-fold increase in matrix metalloproteinase-9 secretion, an enzyme often secreted by cancer cells to help invade through the local extra-cellular matrix. During this acquired malignant phenotype, various CK genes showed markedly altered expression at the transcript and protein levels in a time-dependent manner. For example, CK1, a marker of hyperkeratosis, increased up to 34-fold during arsenic-induced transformation, while CK13, a marker for dermal cancer progression, increased up to 45-fold. The stem cell marker, CK15, increased up to 7-fold, particularly during the later stages of arsenic exposure, indicating a potential emergence of cancer stem-like cells with arsenic-induced acquired malignant phenotype. The expression of involucrin and loricrin, markers for keratinocyte differentiation, increased up to 9-fold. Thus, during arsenic-induced acquired cancer phenotype in human keratinocytes, dramatic and dynamic alterations in CK expression occur which are consistent with the process of epidermal carcinogenesis helping validate this as an appropriate model for the study of arsenic-induced skin cancer.

Hepatocarcinogenic Susceptibility of Fenofibrate and Its Possible Mechanism of Carcinogenicity in a Two-Stage Hepatocarcinogenesis Model of rasH2 Mice

Fenofibrate (FF) has previously been shown to induce hepatocellular neoplasia in a conventional mouse bioassay (NDA 1993), but there has been no report to examine the carcinogenic susceptibility of rasH2 mice to this chemical. In the present study, male rasH2 mice were subjected to a two-thirds partial hepatectomy (PH), followed by an N-diethylnitrosamine (DEN) initiation twenty-four hours after PH, and given a diet containing 0, 1200, or 2400 ppm FF for seven weeks. The incidences of preneoplastic foci were significantly increased in mice from the FF-treated groups. Immunohistochemistry revealed that significant increases in proliferating cell nuclear antigen (PCNA)-positive cells and cytokeratin 8/18 positive foci were observed in FF-treated groups. In addition, the transgene and several downstream molecules such as c- myc, c- jun, activating transcription factor 3 (ATF3), and cyclin D1 were overexpressed in these groups. These results suggest that the hepatocarcinogenic activity of rasH2 mice to FF can be detected in this hepatocarcinogenesis model and that up-regulation of genes for the ras/MAPK pathway and cell cycle was probably involved in the hepatocarcinogenic mechanism of rasH2 mice.

Arsenic-induced suicidal erythrocyte death

Environmental exposure to arsenic has been associated with anemia, which could result from suicidal erythrocyte death or eryptosis, characterized by cell shrinkage and phosphatidylserine exposure at the erythrocyte surface. Eryptosis is triggered by increase in cytosolic Ca2+ concentration, ceramide and energy depletion. The present experiments explored, whether arsenic stimulates eryptosis. According to annexin V-binding, arsenic trioxide (7 microM) within 48 h significantly increased phosphatidylserine exposure of human erythrocytes without inducing hemolysis. According to forward scatter, arsenic trioxide (7 microM) significantly decreased cell volume. Moreover, Fluo3-fluorescence showed that arsenic (10 microM) significantly increased cytosolic Ca2+ concentration. According to binding of respective fluorescent antibodies, arsenic trioxide (10 microM) significantly increased ceramide formation. Arsenic (10 microM) further lowered the intracellular ATP concentration. Removal of extracellular Ca2+ or inhibition of the Ca2+-permeable cation channels with amiloride blunted the effects of arsenic on annexin V-binding and cell shrinkage. In conclusion, arsenic triggers suicidal erythrocyte death by increasing cytosolic Ca2+ concentration, by stimulating the formation of ceramide and by decreasing ATP availability.