Hepatic Ischemia and Reperfusion Injury in the Absence of Myeloid Cell-Derived COX-2 in Mice

Cyclooxygenase-2 (COX-2) is a mediator of hepatic ischemia and reperfusion injury (IRI). While both global COX-2 deletion and pharmacologic COX-2 inhibition ameliorate liver IRI, the clinical use of COX-2 inhibitors has been linked to increased risks of heart attack and stroke. Therefore, a better understanding of the role of COX-2 in different cell types may lead to improved therapeutic strategies for hepatic IRI. Macrophages of myeloid origin are currently considered to be important sources of the COX-2 in damaged livers. Here, we used a Cox-2^flox conditional knockout mouse (COX-2^−M/−M) to examine the function of COX-2 expression in myeloid cells during liver IRI. COX-2^−M/−M mice and their WT control littermates were subjected to partial liver ischemia followed by reperfusion. COX-2^−M/−M macrophages did not express COX-2 upon lipopolysaccharide stimulation and COX-2^−M/−M livers showed reduced levels of COX-2 protein post-IRI. Nevertheless, selective deletion of myeloid cell-derived COX-2 failed to ameliorate liver IRI; serum transaminases and histology were comparable in both COX-2^−M/−M and WT mice. COX-2^−M/−M livers, like WT livers, developed extensive necrosis, vascular congestion, leukocyte infiltration and matrix metalloproteinase-9 (MMP-9) expression post-reperfusion. In addition, myeloid COX-2 deletion led to a transient increase in IL-6 levels after hepatic reperfusion, when compared to controls. Administration of celecoxib, a selective COX-2 inhibitor, resulted in significantly improved liver function and histology in both COX-2^−M/−M and WT mice post-reperfusion, providing evidence that COX-2-mediated liver IRI is caused by COX-2 derived from a source(s) other than myeloid cells. In conclusion, these results support the view that myeloid COX-2, including myeloid-macrophage COX-2, is not responsible for the hepatic IRI phenotype.     

Deficiency of inducible nitric oxide synthase exacerbates hepatic fibrosis in mice fed high-fat diet

The role of inducible nitric oxide synthase (iNOS) in the progression of fibrosis during nonalcoholic steatohepatitis remains to be elucidated. This study examined the role of iNOS in the progression of fibrosis during steatohepatitis by comparing iNOS knockout (iNOS^−/−) and wild-type (iNOS^+/+) mice that were fed a high-fat diet. Severe fatty metamorphosis developed in the liver of iNOS^+/+ and iNOS^−/− mice. Fibrotic changes were marked in iNOS^−/− mice. Gelatin zymography showed that pro MMP-2 and pro MMP-9 protein expressions were more highly induced in iNOS^+/+ mice than in iNOS^−/− mice. Active forms of MMP-2 and MMP-9 were clearly present only in the liver tissue of iNOS^+/+ mice. In situ zymography showed strong gelatinolytic activities in the liver tissue of iNOS^+/+ mice, but only spotty activity in iNOS^−/−mice. iNOS may attenuate the progression of liver fibrosis in steatohepatitis, in part by inducing MMP-2 and MMP-9 expression and augmenting their activity.     

Solvent-partitioned fractions from <Emphasis Type="Italic">Ishige okamurae</Emphasis> extract inhibit MMP-2 and MMP-9 activities in human fibrosarcoma cells in vitro

Matrix metalloproteinases (MMPs) are endopeptidases that take significant roles in extracellular matrix degradation and therefore linked with several complications such as metastasis of cancer progression, oxidative stress, and hepatic fibrosis. Ishige okamurae, a brown alga, has been reported to possess various bioactivities including but not limited to antiviral, antimicrobial, and anti-inflammatory. In this study, the potential of I. okamurae against cancer cell invasion was evaluated through MMP inhibitory effect in HT1080 fibrosarcoma cells in vitro. I. okamurae crude extract was fractionated with organic solvents, namely water (H₂O), n-butanol (n-BuOH), 85% aqueous methanol (85% aq. MeOH), and n-hexane (n-Hex). The non-toxicity of fractions was confirmed by MTT assay. All fractions inhibited the enzymatic activities of MMP-2 and MMP-9 according to gelatin zymography assay. Cell migration was also inhibited by 85% aq. MeOH fraction, significantly. In addition, both gene and protein expressions of MMP-2 and MMP-9, and tissue inhibitor of MMPs (TIMPs) were evaluated by RT-PCR and Western blotting, respectively. Fractions suppressed the mRNA and protein levels of MMP-2 and MMP-9 while elevating the TIMP-1 and TIMP-2, H₂O fraction being the least effective while 85% aq. MeOH fraction the most. Collectively, 85% aq. MeOH fraction from brown algae could be a potential inhibitor of MMPs, suggestively considering presence of poly-unsaturated fatty acids in high amounts.     

Deletion of PARP-2 induces hepatic cholesterol accumulation and decrease in HDL levels

Poly(ADP-ribose) polymerase-2 (PARP-2) is acknowledged as a DNA repair enzyme. However, recent investigations have attributed unique roles to PARP-2 in metabolic regulation in the liver. We assessed changes in hepatic lipid homeostasis upon the deletion of PARP-2 and found that cholesterol levels were higher in PARP-2^−/− mice as compared to wild-type littermates. To uncover the molecular background, we analyzed changes in steady-state mRNA levels upon the knockdown of PARP-2 in HepG2 cells and in murine liver that revealed higher expression of sterol-regulatory element binding protein (SREBP)-1 dependent genes. We demonstrated that PARP-2 is a suppressor of the SREBP1 promoter, and the suppression of the SREBP1 gene depends on the enzymatic activation of PARP-2. Consequently, the knockdown of PARP-2 enhances SREBP1 expression that in turn induces the genes driven by SREBP1 culminating in higher hepatic cholesterol content. We did not detect hypercholesterolemia, higher fecal cholesterol content or increase in serum LDL, although serum HDL levels decreased in the PARP-2^−/− mice. In cells and mice where PARP-2 was deleted we observed decreased ABCA1 mRNA and protein expression that is probably linked to lower HDL levels. In our current study we show that PARP-2 impacts on hepatic and systemic cholesterol homeostasis. Furthermore, the depletion of PARP-2 leads to lower HDL levels which represent a risk factor to cardiovascular diseases.     

Dennd5b-Deficient Mice are Resistant to PCSK9-Induced Hypercholesterolemia and Diet-Induced Hepatic Steatosis

Dennd5b plays a pivotal role in intestinal absorption of dietary lipids in mice and is associated with body mass index in humans. This study examined the impact of whole-body Dennd5b deletion on plasma lipid concentrations, atherosclerosis, and hepatic lipid metabolism in mice. Hypercholesterolemia was induced in Dennd5b^?/? mice by infection with an adeno-associated virus expressing the proprotein convertase subtilisin/kexin type 9 serine protease (PCSK9) gain-of-function mutation (PCSK9D377Y) and feeding a Western diet for 12 weeks. Body weight and plasma lipid concentrations were monitored over 12 weeks, and then aortic atherosclerosis and hepatic lipid content were quantified. Compared to Dennd5b^+/+ mice, Dennd5b^?/? mice were resistant to diet-induced weight gain and PCSK9-induced hypercholesterolemia. Atherosclerosis quantified by en face analysis and in aortic root sections, revealed significantly smaller lesions in Dennd5b^?/? compared to Dennd5b^+/+ mice. Additionally, Dennd5b^?/? mice had significantly less hepatic lipid content (triglyceride and cholesterol) compared to Dennd5b^+/+ mice. To gain insight into the basis for reduced hepatic lipids, quantitative PCR was used to measure mRNA abundance of genes involved in hepatic lipid metabolism. Key genes involved in hepatic lipid metabolism and lipid storage were differentially expressed in Dennd5b^?/? liver including Pparg, Cd36, and Pnpla3. These findings demonstrate a significant impact of Dennd5b on plasma and hepatic lipid concentrations and resistance to PCSK9-induced hypercholesterolemia in the absence of Dennd5b.     

Deletion of Nardilysin Prevents the Development of Steatohepatitis and Liver Fibrotic Changes

Nonalcoholic steatohepatitis (NASH) is an inflammatory form of nonalcoholic fatty liver disease that progresses to liver cirrhosis. It is still unknown how only limited patients with fatty liver develop NASH. Tumor necrosis factor (TNF)-α is one of the key molecules in initiating the vicious circle of inflammations. Nardilysin (N-arginine dibasic convertase; Nrd1), a zinc metalloendopeptidase of the M16 family, enhances ectodomain shedding of TNF-α, resulting in the activation of inflammatory responses. In this study, we aimed to examine the role of Nrd1 in the development of NASH. Nrd1^+/+ and Nrd1^−/− mice were fed a control choline-supplemented amino acid-defined (CSAA) diet or a choline-deficient amino acid-defined (CDAA) diet. Fatty deposits were accumulated in the livers of both Nrd1^+/+ and Nrd1^−/− mice by the administration of the CSAA or CDAA diets, although the amount of liver triglyceride in Nrd1^−/− mice was lower than that in Nrd1^+/+ mice. Serum alanine aminotransferase levels were increased in Nrd1^+/+ mice but not in Nrd1^−/− mice fed the CDAA diet. mRNA expression of inflammatory cytokines were decreased in Nrd1^−/− mice than in Nrd1^+/+ mice fed the CDAA diet. While TNF-α protein was detected in both Nrd1^+/+ and Nrd1^−/− mouse livers fed the CDAA diet, secretion of TNF-α in Nrd1^−/− mice was significantly less than that in Nrd1^+/+ mice, indicating the decreased TNF-α shedding in Nrd1^−/− mouse liver. Notably, fibrotic changes of the liver, accompanied by the increase of fibrogenic markers, were observed in Nrd1^+/+ mice but not in Nrd1^−/− mice fed the CDAA diet. Similar to the CDAA diet, fibrotic changes were not observed in Nrd1^−/− mice fed a high-fat diet. Thus, deletion of nardilysin prevents the development of diet-induced steatohepatitis and liver fibrogenesis. Nardilysin could be an attractive target for anti-inflammatory therapy against NASH.     

The DNA damage checkpoint protein ATM promotes hepatocellular apoptosis and fibrosis in a mouse model of non-alcoholic fatty liver disease

Steatoapoptosis is a hallmark of non-alcoholic fatty liver disease (NAFLD) and is an important factor in liver disease progression. We hypothesized that increased reactive oxygen species resulting from excess dietary fat contribute to liver disease by causing DNA damage and apoptotic cell death, and tested this by investigating the effects of feeding mice high fat or standard diets for 8 weeks. High fat diet feeding resulted in increased hepatic H₂O₂, superoxide production, and expression of oxidative stress response genes, confirming that the high fat diet induced hepatic oxidative stress. High fat diet feeding also increased hepatic steatosis, hepatitis and DNA damage as exemplified by an increase in the percentage of 8-hydroxyguanosine (8-OHG) positive hepatocytes in high fat diet fed mice. Consistent with reports that the DNA damage checkpoint kinase Ataxia Telangiectasia Mutated (ATM) is activated by oxidative stress, ATM phosphorylation was induced in the livers of wild type mice following high fat diet feeding. We therefore examined the effects of high fat diet feeding in Atm-deficient mice. The prevalence of apoptosis and expression of the pro-apoptotic factor PUMA were significantly reduced in Atm-deficient mice fed the high fat diet when compared with wild type controls. Furthermore, high fat diet fed Atm^−/− mice had significantly less hepatic fibrosis than Atm^+/+ or Atm^+/− mice fed the same diet. Together, these data demonstrate a prominent role for the ATM pathway in the response to hepatic fat accumulation and link ATM activation to fatty liver-induced steatoapoptosis and fibrosis, key features of NAFLD progression.     

Molecular Design of a Highly Selective and Strong Protein Inhibitor against Matrix Metalloproteinase-2 (MMP-2)

Synthetic inhibitors of matrix metalloproteinases (MMPs), designed previously, as well as tissue inhibitors of metalloproteinases (TIMPs) lack enzyme selectivity, which has been a major obstacle for developing inhibitors into safe and effective MMP-targeted drugs. Here we designed a fusion protein named APP-IP-TIMP-2, in which the ten amino acid residue sequence of APP-derived MMP-2 selective inhibitory peptide (APP-IP) is added to the N terminus of TIMP-2. The APP-IP and TIMP-2 regions of the fusion protein are designed to interact with the active site and the hemopexin-like domain of MMP-2, respectively. The reactive site of the TIMP-2 region, which has broad specificity against MMPs, is blocked by the APP-IP adduct. The recombinant APP-IP-TIMP-2 showed strong inhibitory activity toward MMP-2 (K_i^app = 0.68 pm), whereas its inhibitory activity toward MMP-1, MMP-3, MMP-7, MMP-8, MMP-9, or MT1-MMP was six orders of magnitude or more weaker (IC₅₀ > 1 μm). The fusion protein inhibited the activation of pro-MMP-2 in the concanavalin A-stimulated HT1080 cells, degradation of type IV collagen by the cells, and the migration of stimulated cells. Compared with the decapeptide APP-IP (t_½ = 30 min), APP-IP-TIMP-2 (t_½ ≫ 96 h) showed a much longer half-life in cultured tumor cells. Therefore, the fusion protein may be a useful tool to evaluate contributions of proteolytic activity of MMP-2 in various pathophysiological processes. It may also be developed as an effective anti-tumor drug with restricted side effects.     

Hepatocyte Produced Matrix Metalloproteinases Are Regulated by CD147 in Liver Fibrogenesis

Background

The classical paradigm of liver injury asserts that hepatic stellate cells (HSC) produce, remodel and turnover the abnormal extracellular matrix (ECM) of fibrosis via matrix metalloproteinases (MMPs). In extrahepatic tissues MMP production is regulated by a number of mechanisms including expression of the glycoprotein CD147. Previously, we have shown that CD147 is expressed on hepatocytes but not within the fibrotic septa in cirrhosis [1]. Therefore, we investigated if hepatocytes produce MMPs, regulated by CD147, which are capable of remodelling fibrotic ECM independent of the HSC.

Methods

Non-diseased, fibrotic and cirrhotic livers were examined for MMP activity and markers of fibrosis in humans and mice. CD147 expression and MMP activity were co-localised by in-situ zymography. The role of CD147 was studied in-vitro with siRNA to CD147 in hepatocytes and in-vivo in mice with CCl₄ induced liver injury using ãCD147 antibody intervention.

Results

In liver fibrosis in both human and mouse tissue MMP expression and activity (MMP-2, -9, -13 and -14) increased with progressive injury and localised to hepatocytes. Additionally, as expected, MMPs were abundantly expressed by activated HSC. Further, with progressive fibrosis there was expression of CD147, which localised to hepatocytes but not to HSC. Functionally significant in-vitro regulation of hepatocyte MMP production by CD147 was demonstrated using siRNA to CD147 that decreased hepatocyte MMP-2 and -9 expression/activity. Further, in-vivo α-CD147 antibody intervention decreased liver MMP-2, -9, -13, -14, TGF-β and α-SMA expression in CCl₄ treated mice compared to controls.

Conclusion

We have shown that hepatocytes produce active MMPs and that the glycoprotein CD147 regulates hepatocyte MMP expression. Targeting CD147 regulates hepatocyte MMP production both in-vitro and in-vivo, with the net result being reduced fibrotic matrix turnover in-vivo. Therefore, CD147 regulation of hepatocyte MMP is a novel pathway that could be targeted by future anti-fibrogenic agents.     

Inhibitory Effect of Aqueous Extracts from Marine Sponges on the Activity and Expression of Gelatinases A (MMP-2) and B (MMP-9) in Rat Astrocyte Cultures

The aim of this study was to evaluate whether water soluble compounds present in aqueous extracts from seven Mediterranean demosponges exert biological activity towards matrix metalloproteinases (MMPs), which represent important pathogenic factors of human diseases. Aqueous extracts were tested on LPS-activated cultured rat astrocytes, and levels and expression of MMP-2 and MMP-9 were assessed by zymography and RT-PCR, respectively. Our results demonstrated that the studied extracts contain water soluble compounds able to inhibit MMP-2 and MMP-9 activity and expression. We also compared the anti-MMP activities present in aqueous extracts from wild and reared specimens of Tethya aurantium and T. citrina. The results obtained revealed that the reared sponges maintain the production of bioactive compounds with inhibitory effect on MMP-2 and MMP-9 for all the duration of the rearing period. Taken together, our results indicate that the aqueous extracts from the selected Mediterranean demosponges possess a variety of water-soluble bioactive compounds, which are able to inhibit MMPs at different levels. The presence of biological activity in aqueous extracts from reared specimens of T. aurantium and T. citrina strongly encourage sponge aquaculture as a valid option to supply sponge biomass for drug development on a large scale.     

Nrf2 Activates Augmenter of Liver Regeneration (ALR) via Antioxidant Response Element and Links Oxidative Stress to Liver Regeneration

Liver regeneration can be impaired by permanent oxidative stress and activation of nuclear factor erythroid 2–related factor 2 (Nrf2), known to regulate the cellular antioxidant response, and has been shown to improve the process of liver regeneration. A variety of factors regulate hepatic tissue regeneration, among them augmenter of liver regeneration (ALR), attained great attention as being survival factors for the liver with proproliferative and antiapoptotic properties. Here we determined the Nrf2/antioxidant response element (ARE) regulated expression of ALR and show ALR as a target gene of Nrf2 in vitro and in vivo. The ALR promoter comprises an ARE binding site and, therefore, ALR expression can be induced by ARE-activator tertiary butylhydroquinone (tBHQ) in hepatoma cells and primary human hepatocytes (PHH). Promoter activity and expression of ALR were enhanced after cotransfection of Nrf2 compared with control and dominant negative mutant of Nrf2. Performing partial hepatectomy in livers from Nrf2^+/+ mice compared with Nrf2^−/− knock-out (KO) mice, we found increased expression of ALR in addition to known antioxidant ARE-regulated genes. Furthermore, we observed increased ALR expression in hepatitis B virus (HBV) compared with hepatitis C virus (HCV) positive hepatoma cells and PHH. Recently, it was demonstrated that HBV infection activates Nrf2 and, now, we add results showing increased ALR expression in liver samples from patients infected with HBV. ALR is regulated by Nrf2, acts as a liver regeneration and antioxidative protein and, therefore, links oxidative stress to hepatic regeneration to ensure survival of damaged cells.     

Delineation of crosstalk between HSP27 and MMP-2/MMP-9: A synergistic therapeutic avenue for glioblastoma management

BackgroundEpithelial to mesenchymal transition (EMT) and extracellular matrix (ECM) remodeling, are the two elemental processes promoting glioblastoma (GBM). In the present work we propose a mechanistic modelling of GBM and in process establish a hypothesis elucidating critical crosstalk between heat shock proteins (HSPs) and matrix metalloproteinases (MMPs) with synergistic upregulation of EMT-like process and ECM remodeling.MethodsThe interaction and the precise binding site between the HSP and MMP proteins was assayed computationally, in-vitro and in GBM clinical samples.ResultsA positive crosstalk of HSP27 with MMP-2 and MMP-9 was established in both GBM patient tissues and cell-lines. This association was found to be of prime significance for ECM remodeling and promotion of EMT-like characteristics. In-silico predictions revealed 3 plausible interaction sites of HSP27 interacting with MMP-2 and MMP-9. Site-directed mutagenesis followed by in-vitro immunoprecipitation assay (IP) with 3 mutated recombinant HSP27, confirmed an interface stretch containing residues 29–40 of HSP27 to be a common interaction site for both MMP-2 and MMP-9. This was further validated with in-vitro IP of truncated (sans AA 29–40) recombinant HSP27 with MMP-2 and MMP-9.ConclusionThe association of HSP27 with MMP-2 and MMP-9 proteins along with the identified interacting stretch has the potential to contribute towards drug development to inhibit GBM infiltration and migration.General significanceCurrent findings provide a novel therapeutic target for GBM opening a new horizon in the field of GBM management.     

Absence of adipose differentiation related protein upregulates hepatic VLDL secretion,relieves hepatosteatosis,and improves whole body insulin resistance in leptin-deficient mice

We previously showed that adipose differentiation related protein (Adfp)-deficient mice display a 60% reduction in hepatic triglyceride (TG) content. In this study, we investigated the role of ADFP in lipid and glucose homeostasis in a genetic obesity model, Lep^ob/ob mice. We bred Adfp^−/− mice with Lep^ob/ob mice to create Lep^ob/ob/Adfp^−/− and Lep^ob/ob/Adfp^+/+ mice and analyzed the hepatic lipids, lipid droplet (LD) morphology, LD protein composition and distribution, lipogenic gene expression, and VLDL secretion, as well as insulin sensitivity of the two groups of mice. Compared with Lep^ob/ob/Adfp^+/+ mice, Lep^ob/ob/Adfp^−/− mice displayed an increased VLDL secretion rate, a 25% reduction in hepatic TG associated with improvement in fatty liver grossly and microscopically with a change of the size of LDs in a proportion of the hepatocytes and a redistribution of major LD-associated proteins from the cytoplasmic compartment to the LD surface. There was no detectable change in lipogenic gene expression. Lep^ob/ob/Adfp^−/− mice also had improved glucose tolerance and insulin sensitivity in both liver and muscle. The alteration of LD size in the liver of Lep^ob/ob/Adfp^−/− mice despite the relocation of other LDPs to the LD indicates a nonredundant role for ADFP in determining the size and distribution of hepatic LDs.     

Salvianolic acid A,a matrix metalloproteinase-9 inhibitor of Salvia miltiorrhiza,attenuates aortic aneurysm formation in apolipoprotein E-deficient mice

Aortic aneurysm (AA) is a life-threatening vascular disease in defect of effective pharmaceutical therapy. Matrix metalloproteinase-9 (MMP-9) is implicated in the development of chronic vascular diseases including aneurysm, but the effective MMP-9 inhibitors are far from development. To develop new candidate for AA therapy, we evaluated the efficiency of salvianolic acid A (SalA), a novel MMP-9 inhibitor, on AA progression in a mouse model and characterized the mechanism of action. SalA is a water soluble compound of the herbal drug Rhizoma Salviae miltiorrhizae (Danshen) which in China is widely used for the treatment of hypertension, coronary artery diseases and myocardial infarction. MMPs activity was evaluated by enzyme kinetic analysis in vitro and in-gel gelatin zymography in vivo. SalA showed selectivity on gelatinase (MMP-2 and MMP-9) than on collagenase (MMP-8 and MMP-13) in vitro, and specificity on MMP-9 than MMP-2 in vivo. Aortic aneurysm was induced by angiotension II (AngII) in apolipoprotein E-deficient (ApoE^−/−) mice. Aortic structure was evaluated by hematoxylin and eosin, picrosirius red, orein stain. Macrophage infiltration was detected by immunohistochemistry in vivo and transwell in vitro. Comparing with doxycycline (Dox), a well-known MMPs inhibitor, SalA showed similar efficiency against AA progression. SalA significantly decreased aortic diameter and aneurysm severity, ameliorated integrity of vascular structure, inhibited elastin fragmentation and macrophage infiltration. Furthermore, SalA showed greater safety than Dox based on hepatotoxicity evaluation. Our results demonstrated that SalA held great potential for AA therapy.     

The C57BL/6J Niemann–Pick C1 mouse model with decreased gene dosage has impaired glucose tolerance independent of body weight

The human Niemann–Pick C1 (NPC1) gene has been found to be associated with extreme (early-onset and morbid-adult) obesity and type 2 diabetes independent of body weight. We previously performed growth studies using BALB/cJ Npc1 normal (Npc1^+/+) and Npc1 heterozygous (Npc1^+/−) mice and determined that decreased Npc1 gene dosage interacts with a high-fat diet to promote weight gain and adiposity. The present study was performed using both BALB/cJ and C57BL/6J Npc1^+/+ and Npc1^+/− mice to determine if decreased Npc1 gene dosage predisposes to metabolic features associated with type 2 diabetes. The results indicated that C57BL/6J Npc1^+/− mice, but not BALB/cJ Npc1^+/− mice, have impaired glucose tolerance when fed a low-fat diet and independent of body weight. The results also suggest that an accumulation of liver free fatty acids and hepatic lipotoxicity marked by an elevation in the amount of plasma alanine aminotransferase (ALT) may be responsible for hepatic insulin resistance and impaired glucose tolerance. Finally, the peroxisome-proliferator activated receptor α (PPARα) and sterol regulatory element-binding protein-1 (SREBP-1) pathways known to have a central role in regulating free fatty acid metabolism were downregulated in the livers, but not in the adipose or muscle, of C57BL/6J Npc1^+/− mice compared to C57BL/6J Npc1^+/+ mice. Therefore, decreased Npc1 gene dosage among two different mouse strains interacts with undefined modifying genes to manifest disparate yet often related metabolic diseases.     

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 CCl₄-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 CCl₄-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.     

The Inhibitory Effect of C-phycocyanin Containing Protein Extract (C-PC Extract) on Human Matrix Metalloproteinases (MMP-2 and MMP-9) in Hepatocellular Cancer Cell Line (HepG2)

Spirulina platensis :have been studied for several biological activities. In the current study C-phycocyanin containing protein extract (C-PC extract) of Spirulina platensis have been studied for its effect on human matrix metalloproteinases (MMP-1, MMP-2 and MMP-9) and tissue inhibitors of MMPs (TIMP-1 and TIMP-2). In the present study, breast cancer cell line (MDA-MB 231) and hepatocellular cancer cell line (HepG2) were examined for inhibition of MMPs at different levels of expression after C-PC extract treatment. Herein, we have demonstrated that C-PC extract significantly reduced activity of MMP-2 by 55.13% and MMP-9 by 57.9% in HepG2 cells at 15 μg concentration. Additionally, the treatment has reduced mRNA expression of MMP-2 and MMP-9 at 20 μg concentration by 1.65-folds and 1.66-folds respectively. The C-PC extract treatment have also downregulated a mRNA expression of TIMP-2 by 1.12 folds at 20 μg concentration in HepG2 cells. Together, these results indicate that C-PC, extract successfully inhibited MMP-2 and -9 at different levels of expression and TIMP-2 at a mRNA expression level; however, extract did not have any effect on MMP-1 expressed in MDA-MB231 and TIMP-1 expressed in HepG2 cells as well as the exact mechanism of inhibition of MMP-2, MMP-9 and TIMP-2 remained unclear.