Enhanced Collagen Degradation Research Articles

Abstract PR006: The racial disparity-linked gene CRYβB2 alters cell adhesion and tumor microenvironment to promote proliferation and invasion in triple-negative breast cancer

Abstract Background: Clinical and epidemiological data showed that African American (AA) women suffer higher incidence and mortality rates due to triple-negative breast cancer (TNBC) compared to European American (EA) women. These disparate disease outcomes are attributed to multiple factors including socioeconomic status, access to health care, and earlier disease onset. However, a growing body of evidence also shows the existence of different gene expression signatures and tumor microenvironments between these patient racial groups. We and others identified CRYβB2 as a cancer racial disparity gene that has higher expression in AA patients with breast, colon, and prostate cancers. We previously demonstrated, via in vitro and in vivo studies, that CRYβB2 promotes proliferation, metastasis, and IL-6 signaling. The objective of the current research is to identify the cellular and molecular mechanisms downstream of CRYβB2 leading to its tumor-promoting phenotypes. Methods: CRISPR/Cas9 and lentiviral knock-in gene editing tools were used to create TNBC cell lines with CRYβB2 knockout and overexpression respectively. The functional consequences of CRYβB2 were assessed in vitro using colony formation, tumor spheroid invasion, and collagenase activity assays. Additionally, tumor spheroids were grown and RNA sequencing (RNA-seq) was performed to assess the effect of CRYβB2 on gene expression. Results: Herein, functional assays showed that CRYβB2 promotes proliferation and invasion in vitro in both AA and EA cell lines. RNA-seq and Gene Ontology enrichment analyses revealed that CRYβB2 alters key pathways such as cell adhesion and extracellular matrix (ECM) organization. RT-qPCR validation also showed that CRYβB2 inhibits the expression of a specific class of adhesion molecules known as protocadherins (PCDHs). Downregulation of PCDHs has been shown to enhance tumor progression and is a predictive marker for low survival in many cancer types. Indeed, data mining of publicly available data shows that three of the identified PCDHs (PCDHGB5, PCDHGB6 and PCDHGB7) have significantly lower expression levels in breast cancer compared to normal tissue and their low expression leads to low overall survival. Furthermore, RNA-seq data showed that CRYβB2 promotes the expression of multiple matrix metalloproteinase (MMP) genes. This was functionally validated using collagenase activity assay where CRYβB2 enhanced collagen degradation in vitro. Conclusions: Our findings provide a mechanistic explanation for the role of CRYβB2 in driving disparate clinical outcome among AA and EA TNBC patients. We demonstrate a paradigm where high CRYβB2 expression promotes tumor progression by suppressing cell adhesion molecules and increasing ECM degradation to enhance tumor growth, invasion, and metastasis. Disclaimer: This work was prepared while Jodie Fleming was employed at NCCU. The opinions expressed in this article are the author's own and do not reflect the view of the National Institutes of Health, the Department of Health and Human Services, or the United States government. Citation Format: Amr A. Waly, London Harper, Jodie M. Fleming, Lindsey M. Costantini. The racial disparity-linked gene CRYβB2 alters cell adhesion and tumor microenvironment to promote proliferation and invasion in triple-negative breast cancer [abstract]. In: Proceedings of the 15th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2022 Sep 16-19; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2022;31(1 Suppl):Abstract nr PR006.

17α-estradiol, a lifespan-extending compound, attenuates liver fibrosis by modulating collagen turnover rates in male mice.

Estrogen signaling is protective against chronic liver diseases, although men and a subset of women are contraindicated for chronic treatment with 17β-estradiol (17β-E2) or combination hormone replacement therapies. We sought to determine if 17α-estradiol (17α-E2), a naturally occurring diastereomer of 17β-E2, could attenuate liver fibrosis. We evaluated the effects of 17α-E2 treatment on collagen synthesis and degradation rates using tracer-based labeling approaches in male mice subjected to carbon tetrachloride (CCl4)-induced liver fibrosis. We also assessed the effects of 17α-E2 on markers of hepatic stellate cell (HSC) activation, collagen cross-linking, collagen degradation, and liver macrophage content and polarity. We found that 17α-E2 significantly reduced collagen synthesis rates and increased collagen degradation rates, which was mirrored by declines in transforming growth factor β1 (TGF-β1) and lysyl oxidase-like 2 (LOXL2) protein content in liver. These improvements were associated with increased matrix metalloproteinase 2 (MMP2) activity and suppressed stearoyl-coenzyme A desaturase 1 (SCD1) protein levels, the latter of which has been linked to the resolution of liver fibrosis. We also found that 17α-E2 increased liver fetuin-A protein, a strong inhibitor of TGF-β1 signaling, and reduced proinflammatory macrophage activation and cytokines expression in the liver. We conclude that 17α-E2 reduces fibrotic burden by suppressing HSC activation and enhancing collagen degradation mechanisms. Future studies will be needed to determine if 17α-E2 acts directly in hepatocytes, HSCs, and/or immune cells to elicit these benefits.

Carotid endarterectomy plaques of patients with elevated levels of lipoprotein(a) demonstrate increased intraplaque angiogenesis

Background and Aims : Elevated lipoprotein(a) [Lp(a)] levels have been demonstrated to be a causal risk factor for the development of cardiovascular disease. Previously, we described that patients with elevated Lp(a) levels have an increased risk of major adverse cardiovascular events (MACE), mostly stroke, 30 days after undergoing carotid endarterectomy (CEA). Aim: Unravelling the mechanism underlying this increase in MACE.Methods: We performed targeted plasma proteomics analysis using the proximity extension assay for 276 proteins on complete plasma from patients undergoing CEA with high levels (>195 mg/dl; N=39) and low levels (<7 mg/dl; N=73) of Lp(a).Results: Surprisingly, no differences were observed in the expression of systemic plasma proteins. Hence, we started to assess the local effects of Lp(a) on plaque morphology. Plaque phenotyping demonstrated that patients with high levels (>195 mg/dl; N=57) of Lp(a) had a 33% increase in mean vessel density compared to patients with low levels (<7 mg/dl; N=106), as attested by semi-quantitatively scoring of the plaques. This increase in neovascularization correlates with decreased plaque stability, as was indicated by increased intraplaque haemorrhage. In-vitro stimulation of Human Arterial Endothelial Cells with physiologically relevant levels of Lp(a) (100 mg/dl), results in enhanced collagen degradation capacity, hyper-sprouting in a 3D spheroid assay and increased blood vessel invasion using a 3D collagen-invasiveness assay. Currently, we are elucidating the signalling pathways underlying this Lp(a)-induced angiogenesis, which we strive to present at the EAS 2022.Conclusions: Lp(a)-induced intraplaque angiogenesis can contribute to the increased risk of major adverse cardiovascular events in patients with elevated levels of Lp(a). Background and Aims : Elevated lipoprotein(a) [Lp(a)] levels have been demonstrated to be a causal risk factor for the development of cardiovascular disease. Previously, we described that patients with elevated Lp(a) levels have an increased risk of major adverse cardiovascular events (MACE), mostly stroke, 30 days after undergoing carotid endarterectomy (CEA). Aim: Unravelling the mechanism underlying this increase in MACE. Methods: We performed targeted plasma proteomics analysis using the proximity extension assay for 276 proteins on complete plasma from patients undergoing CEA with high levels (>195 mg/dl; N=39) and low levels (<7 mg/dl; N=73) of Lp(a). Results: Surprisingly, no differences were observed in the expression of systemic plasma proteins. Hence, we started to assess the local effects of Lp(a) on plaque morphology. Plaque phenotyping demonstrated that patients with high levels (>195 mg/dl; N=57) of Lp(a) had a 33% increase in mean vessel density compared to patients with low levels (<7 mg/dl; N=106), as attested by semi-quantitatively scoring of the plaques. This increase in neovascularization correlates with decreased plaque stability, as was indicated by increased intraplaque haemorrhage. In-vitro stimulation of Human Arterial Endothelial Cells with physiologically relevant levels of Lp(a) (100 mg/dl), results in enhanced collagen degradation capacity, hyper-sprouting in a 3D spheroid assay and increased blood vessel invasion using a 3D collagen-invasiveness assay. Currently, we are elucidating the signalling pathways underlying this Lp(a)-induced angiogenesis, which we strive to present at the EAS 2022. Conclusions: Lp(a)-induced intraplaque angiogenesis can contribute to the increased risk of major adverse cardiovascular events in patients with elevated levels of Lp(a).

Matrix metalloproteinase-14 regulates collagen degradation and migration of mononuclear cells during infection with genotype VII Newcastle disease virus.

Upregulation of matrix metalloproteinase (MMP)-14, a major driven force of extracellular-matrix (ECM) remodelling and cell migration, correlates with ECM breakdown and pathologic manifestation of genotype VII Newcastle disease virus (NDV) in chickens. However, the functional relevance between MMP-14 and pathogenesis of genotype VII NDV remains to be investigated. In this study, expression, biofunction and regulation of MMP-14 induced by genotype VII NDV were analysed in chicken peripheral blood mononuclear cells (PBMCs). The results showed that JS5/05 significantly increased expression and membrane accumulation of MMP-14 in PBMCs, correlating to enhanced collagen degradation and cell migration. Specific MMP-14 inhibition significantly impaired collagen degradation and migration of JS5/05-infected cells, suggesting dependence of these features on MMP-14. In addition, MMP-14 upregulation correlated with activation of the extracellular signal-regulated kinase (ERK) pathway upon JS5/05 infection, and blockage of the ERK signalling significantly suppressed MMP-14-mediated collagen degradation and migration of JS5/05-infected cells. Using a panel of chimeric NDVs derived from gene exchange between genotype VII and IV NDV, the fusion and haemagglutinin-neuraminidase genes were identified as the major viral determinants for MMP-14 expression and activity. In conclusion, MMP-14 was defined as a critical regulator of collagen degradation and cell migration of chicken PBMCs infected with genotype VII NDV, which may contribute to pathology of the virus. Our findings add novel information to the body of knowledge regarding virus-host biology and NDV pathogenesis.

Pressure-induced collagen degradation in arterial tissue as a potential mechanism for degenerative arterial disease progression

Collagen fibre degradation is a strain-dependent process, whereby the magnitude of experienced strain dictates the rate of enzymatic cleavage. Studies have identified conflicting findings as to whether strain inhibits or enhances collagen degradation, which may be explained by the tissue type and tissue scale investigated, as well as the strain range considered. The aim of this study is to identify, for the first time, the strain-dependent degradation response of intact arterial vessels experiencing physiological pressures and apply these findings to a computational model to better understand degenerative arterial diseases, such as aneurysms.To achieve this, a series of quasi-static pressure inflation experiments were carried out on intact arteries in the presence of purified bacterial collagenase at physiologically relevant pressures to investigate collagen matrix degradation in the vascular wall. A complementary computational model was developed to explore the complex role of pressure, non-collagenous matrix contribution, and collagen fibre crimp in the ultimate degradation response of the vessel.Pressure induced inflation-degradation results identified an increased rate of vessel expansion and reduced time to failure with increasing pressure in the vessels. Interestingly, our computational model was able to capture this same response, including the elevated rates of degradation which occur at low pressures. These findings highlight the critical role of strain in collagen degradation, particularly in cases of arterial disease, such as aneurysm formation, whereby structural integrity may be compromised.

Focal adhesion kinase regulates tractional collagen remodeling, matrix metalloproteinase expression, and collagen structure, which in turn affects matrix-induced signaling.

Focal adhesion kinase (FAK) is critical for collagen expression but its regulation of collagen remodeling is not defined. We examined the role of FAK in the degradation and reorganization of fibrillar collagen. Compared with wild-type (WT) mouse embryonic fibroblasts, FAK null (FAK-/- ) fibroblasts generated twofold (p < .0001) higher levels of ¾ collagen I fragment and expressed up to fivefold more membrane-type matrix metalloproteinase (MMP). When plated on stiff collagen substrates, compared with WT, FAK-/- cells were smaller (threefold reduced cell surface area; p < .0001) and produced fivefold fewer cell extensions (p < .0001) that were 40% shorter (p < .001). When cultured on soft collagen gels (stiffness of ~100 Pa) for 6-48 hr, cell spreading and cell extension formation were reduced by greater than twofold (p < .05 and p < .0001, respectively) while collagen compaction and alignment were reduced by approximately 30% (p < .0001) in FAK-/- cells. Similar results were found after treatment with PF573228, a FAK inhibitor. Reconstitution of FAK-/- cells with FAK mutants showed that compared with WT, cell extension formation was reduced twofold (p < .0001) in the absence of the kinase domain and sixfold (p < .0001) with a Y397F mutant. Enhanced collagen degradation was exhibited by the mutants (~threefold increase; p < .0001 of ¾ collagen fragments without kinase domain or Y397F mutant; p < .01). Compared with FAK+/+ cells, matrices produced by FAK-/- cells generated higher levels of β1 integrin activation (p < 0.05), extracellular-signal-regulated kinase (ERK) phosphorylation, and production of ¾ collagen I fragment by human gingival fibroblasts. Collectively these data indicate that (a) the kinase activity of FAK enhances collagen remodeling by tractional forces but inhibits collagen degradation by MMPs; (b) FAK influences the biological activity of fibroblast-secreted extracellular matrices, which in turn impacts β1 integrin and ERK signaling, and collagen degradation.

CCL2/MCP-1 signaling drives extracellular matrix turnover by diverse macrophage subsets

Macrophage plasticity, cellular origin, and phenotypic heterogeneity are perpetual challenges for studies addressing the biology of this pivotal immune cell in development, homeostasis, and tissue remodeling/repair. Consequently, a myriad of macrophage subtypes has been described in these contexts. To facilitate the identification of functional macrophage subtypes in vivo, here we used a flow cytometry-based assay that allows for detailed phenotyping of macrophages engaged in extracellular matrix (ECM) degradation. Of the five macrophage subtypes identified in the remodeling dermis by using this assay, collagen degradation was primarily executed by Ly6C−CCR2+ and Ly6C−CCR2low macrophages via mannose receptor-dependent collagen endocytosis, while Ly6C+CCR2+ macrophages were the dominant fibrin-endocytosing cells. Unexpectedly, the CCL2/MCP1-CCR2 signaling axis was critical for both collagen and fibrin degradation, while collagen degradation was independent of IL-4Ra signaling. Furthermore, the cytokine GM-CSF selectively enhanced collagen degradation by Ly6C+CCR2+ macrophages. This study reveals distinct subsets of macrophages engaged in ECM turnover and identifies novel wound healing-associated functions for CCL2 and GM-CSF inflammatory cytokines.

Copper‐Induced Reversal of Fibrosis in Rat Model of Cardiac Hypertrophy is Associated with Enhanced Collagen Degradation by MMP‐2 Up‐Regulation

Our recent studies observed that trientine (TETA), a copper chelator, is capable of redistributing copper from plasma to the heart, leading to regression of cardiac fibrosis in rat model of pressure overload‐induced heart hypertrophy. The present study was undertaken to explore possible mechanisms by which copper repletion reverses cardiac fibrosis. Adult male Sprague‐Dawley rats were subjected to ascending aortic constriction (AAC) to induce pathological cardiac hypertrophy. Four months after the operation, cardiac hypertrophy along with fibrosis was fully developed as determined by pathological examination and Sirius red staining. At the same time, TETA at a dose of 4.38 mg/kg, twice a day, was administered orally for six weeks. At the end of the experiment, the expression and crosslinking of type I and III collagens were determined respectively by immunohistochemistry and Sircol collagen assay. Western blot was performed to detect the expressions of lysyl oxidase (LOX), MMP‐2 and MMP‐9. The results showed that the content and crosslinking of type I and III collagens were both significantly decreased after TETA treatment. The expression of MMP‐2 was up‐regulated, but the expressions of MMP‐9 and LOX were not changed. The data thus demonstrated that the reversal of cardiac fibrosis by TETA‐induced copper repletion is related at least in part to an enhanced collagen degradation process.Support or Funding InformationThis study is supported by National Science Foundation of China (81230004 and 81300109).

A single adenovirus-mediated relaxin delivery attenuates established liver fibrosis in rats.

Liver fibrosis is characterized by an excess accumulation and repressed degradation of extracellular matrix. Although methods of alleviating already established liver fibrosis have scarcely been reported, continuous relaxin (RLX) infusion has demonstrated some promising results. In the present study, we investigated whether a single adenoviral delivery of RLX would attenuate established liver fibrosis in rats. Rats were given thioacetamide (TAA) for 8 weeks and infected once with either RLX-expressing adenovirus (TAA + RLX) or control virus (TAA + Vector) via the tail vein. They were sacrificed either 3 days or 3 weeks after adenovirus infection. Morphometric analysis of picrosirius red stained area demonstrated that the TAA + RLX group had significantly decreased fibrosis at week 3 when liver fibrosis of the TAA + Vector group remained unchanged. Although the liver and serum RLX levels were elevated on day 3 and reversed by week 3, expression of RLX receptor (Rxfp1; relaxin-like family peptide receptor-1) in TAA + RLX rats was sustained and elevated. The production of tissue cyclic adenosine monophosphate, which is a second messenger of activated Rxfp1, was still enhanced in the TAA + RLX group by week 3. Expression of lysyl oxidase homolog 2, which contributes to collagen cross-linking and is up-regulated by TAA treatment, was significantly decreased by week 3 in the TAA + RLX group. Expression of tissue inhibitor of metalloprotiase-2 was alleviated in the TAA + RLX group at week 3, whereas that of TAA + Vector rats was still elevated. A single adenoviral delivery of RLX in the liver attenuated established hepatic fibrosis by suppressing collagen cross-linking and enhancing collagen degradation.

P0424 : Delivery of relaxin attenuates established liver fibrosis by suppressing collagen cross-link and enhancing collagen degradation

P0424 : Delivery of relaxin attenuates established liver fibrosis by suppressing collagen cross-link and enhancing collagen degradation

Zinc supplementation suppresses the progression of bile duct ligation-induced liver fibrosis in mice.

Metallothionein (MT) gene therapy leads to resolution of liver fibrosis in mouse model, in which the activation of collagenases is involved in the regression of liver fibrosis. MT plays a critical role in zinc sequestration in the liver suggesting its therapeutic effect would be mediated by zinc. The present study was undertaken to test the hypothesis that zinc supplementation suppresses liver fibrosis. Male Kunming mice subjected to bile duct ligation (BDL) resulted in liver fibrosis as assessed by increased α-smooth muscle actin (α-SMA) and collagen I production/deposition in the liver. Zinc supplementation was introduced 4 weeks after BDL surgery via intragastric administration once daily for 2 weeks resulting in a significant reduction in the collagen deposition in the liver and an increase in the survival rate. Furthermore, zinc suppressed gene expression of α-SMA and collagen I and enhanced the capacity of collagen degradation, as determined by the increased activity of total collagenases and elevated mRNA and protein levels of MMP13. Therefore, the results demonstrate that zinc supplementation suppresses BDL-induced liver fibrosis through both inhibiting collagen production and enhancing collagen degradation.

Effects of herbal compound 861 on collagen synthesis and degradation in rat mesangial cells exposed to high glucose

To investigate the effects of Herbal Compound 861 (Cpd 861) on collagen synthesis and degradation in rat mesangial cells exposed to high glucose. The third to fifth passage of rat mesangial cells were exposed to high glucose and Cpd 861 at a concentration of 0.25-4.00 g/L for 24, 48 and 72 h, respectively. Benazepril (10(-7)-10(-3) mmol/L) was selected as positive control. The methyl thiazolyl tetrazolium colorimetric assay was used to evaluate the effect of Cpd 861 on cell proliferation. After incubation with Cpd 861 at a concentration of 2.00 g/L for 48 h, the protein secretions of collagen type IV, matrix metallopeptidase 9 (MMP-9), tissue inhibitor of metalloproteinase-1 (TIMP-1), transforming growth factor beta 1 (TGF-β1), and hepatocyte growth factor (HGF) were detected by enzyme-linked immunosorbent assay method. And rat mesangial cells were harvested to determine MMP-9, TIMP-1, TGF-β1 and HGF mRNA expression by reverse transcription polymerase chain reaction. Cpd 861 inhibited cell proliferation induced by high glucose in a dose- and time-dependent manner. Compared with high glucose, collagen type IV production was decreased significantly by Cpd 861 (P<0.01). Cpd 861 increased the protein secretions and mRNA expressions of MMP-9 and HGF, whereas the protein secretions and mRNA expressions of TIMP-1 and TGF-β1 were reduced markedly (P<0.05). The ratio of MMP-9 to TIMP-1 was enhanced by Cpd 861 significantly. There was no significant difference in all above-mentioned effects between Cpd 861 (2.00 g/L) and benazepril (10(-5) mmol/L). The anti-glomerulosclerosis mechanisms of Cpd 861 were partly attributed to its effects of inhibiting mesangial cell proliferation, decreasing collagen synthesis and enhancing collagen degradation.

BAX inhibitor-1-associated V-ATPase glycosylation enhances collagen degradation in pulmonary fibrosis

Endoplasmic reticulum (ER) stress is considered one of the pathological mechanisms of idiopathic pulmonary fibrosis (IPF). Therefore, we examined whether an ER stress regulator, Bax inhibitor-1 (BI-1), regulates collagen accumulation, which is both a marker of fibrosis and a pathological mechanism of fibrosis. The presence of BI-1 inhibited the transforming growth factor-β1-induced epithelial–mesenchymal transition of epithelial pulmonary cells and bleomycin-induced pulmonary fibrosis in a mouse model by enhancing collagen degradation, most likely by enhanced activation of the lysosomal V-ATPase through glycosylation. We also found a correlation between post-translational glycosylation of the V-ATPase and its associated chaperone, calnexin, in BI-1-overexpressing cells. BI-1-induced degradation of collagen through lysosomal V-ATPase glycosylation and the involvement of calnexin were confirmed in a bleomycin-induced fibrosis mouse model. These results highlight the regulatory role of BI-1 in IPF and reveal for the first time the role of lysosomal V-ATPase glycosylation in IPF.

Effect of budesonide on fibroblast-mediated collagen gel contraction and degradation

BackgroundThe balance between production and degradation of extracellular matrix is crucial in maintaining normal tissue structure. This study was designed to investigate the effect of budesonide on fibroblast-mediated tissue repair and remodeling.MethodsUsing human fetal lung fibroblasts in a three-dimensional collagen gel culture system, we investigated the effect of budesonide (1-1000 nM) on collagen gel contraction and degradation in the presence or absence of Inflammatory cytokines (interleukin-1β and tumor necrosis factor α; 5 ng/mL each) and, in order to activate latent proteases, serine protease trypsin 0.25 μg/mL. The effects of budesonide on metalloproteinase production and activation were also investigated.ResultsInflammatory cytokines significantly inhibited collagen gel contraction mediated by lung fibroblasts. Budesonide counteracted the effect of cytokines in a concentration-dependent manner (to 50%, P< 0.01). Budesonide 100 nM almost completely inhibited the release and mRNA expression of metalloproteinase-1, metalloproteinase-3, and metalloproteinase-9 induced by the cytokines (P< 0.05). Exposure to the cytokines plus trypsin increased collagen degradation and conversion of the metalloproteinases to lower molecular weight forms corresponding to their active forms. Budesonide blocked both enhanced collagen degradation (P< 0.01) and suppressed trypsin-mediated conversion of cytokine-induced metalloproteinase-9 and metalloproteinase-3 to lower molecular weight forms. Similar effects were observed with dexamethasone 1 μM, suggesting a class effect.ConclusionThese findings demonstrate that budesonide directly modulates contraction of collagen gels and can decrease collagen degradation under Inflammatory conditions. The mechanism of this effect is through suppressing gene expression, release, and activation of metalloproteinases. By modulating the release and activity of metalloproteinases, inhaled budesonide may be able to modify airway tissue repair and remodeling.

Collagen remodeling by phagocytosis is determined by collagen substrate topology and calcium-dependent interactions of gelsolin with nonmuscle myosin IIA in cell adhesions

We examine how collagen substrate topography, free intracellular calcium ion concentration ([Ca(2+)]i, and the association of gelsolin with nonmuscle myosin IIA (NMMIIA) at collagen adhesions are regulated to enable collagen phagocytosis. Fibroblasts plated on planar, collagen-coated substrates show minimal increase of [Ca(2+)]i, minimal colocalization of gelsolin and NMMIIA in focal adhesions, and minimal intracellular collagen degradation. In fibroblasts plated on collagen-coated latex beads there are large increases of [Ca(2+)]i, time- and Ca(2+)-dependent enrichment of NMMIIA and gelsolin at collagen adhesions, and abundant intracellular collagen degradation. NMMIIA knockdown retards gelsolin recruitment to adhesions and blocks collagen phagocytosis. Gelsolin exhibits tight, Ca(2+)-dependent binding to full-length NMMIIA. Gelsolin domains G4-G6 selectively require Ca(2+) to interact with NMMIIA, which is restricted to residues 1339-1899 of NMMIIA. We conclude that cell adhesion to collagen presented on beads activates Ca(2+) entry and promotes the formation of phagosomes enriched with NMMIIA and gelsolin. The Ca(2+) -dependent interaction of gelsolin and NMMIIA in turn enables actin remodeling and enhances collagen degradation by phagocytosis.

Angiotensin-Converting Enzyme-2 Overexpression Improves Left Ventricular Remodeling and Function in a Rat Model of Diabetic Cardiomyopathy

The aim of this study was to test the hypothesis that angiotensin (Ang)-converting enzyme-2 (ACE2) overexpression may inhibit myocardial collagen accumulation and improve left ventricular (LV) remodeling and function in diabetic cardiomyopathy. Hyperglycemia activates the renin-Ang system, which promotes the accumulation of extracellular matrix and progression of cardiac remodeling and dysfunction. Ninety male Wistar rats were divided randomly into treatment (n = 80) and control (n = 10) groups. Diabetes was induced in the treatment group by a single intraperitoneal injection of streptozotocin. Twelve weeks after streptozotocin injection, rats in the treatment group were further divided into adenovirus-ACE2, adenovirus-enhanced green fluorescent protein, losartan, and mock groups (n = 20 each). LV volume; LV systolic and diastolic function; extent of myocardial fibrosis; protein expression levels of ACE2, Ang-converting enzyme, and Ang-(1-7); and matrix metalloproteinase-2 activity were evaluated. Cardiac myocyte and fibroblast culture was performed to assess Ang-II and collagen protein expression before and after ACE2 gene transfection. Four weeks after ACE2 gene transfer, the adenovirus-ACE2 group showed increased ACE2 expression, matrix metalloproteinase-2 activity, and LV ejection fractions and decreased LV volumes, myocardial fibrosis, and ACE, Ang-II, and collagen expression in comparison with the adenovirus-enhanced green fluorescent protein and control groups. ACE2 was superior to losartan in improving LV remodeling and function and reducing collagen expression. The putative mechanisms may involve a shift in balance toward an inhibited fibroblast-myocyte cross-talk for collagen and transforming growth factor-beta production and enhanced collagen degradation by matrix metalloproteinase-2. ACE2 inhibits myocardial collagen accumulation and improves LV remodeling and function in a rat model of diabetic cardiomyopathy. Thus, ACE2 provides a promising approach to the treatment of patients with diabetic cardiomyopathy.

TGF-β Signaling in Gingival Fibroblast-Epithelial Interaction

The underlying mechanism and the therapeutic regimen for the transition of reversible gingivitis to irreversible periodontitis are unclear. Since transforming growth factor (TGF)-β has been implicated in differentially regulated gene expression in gingival fibroblasts, we hypothesized that TGF-β signaling is activated in periodontitis-affected gingiva, along with enhanced collagen degradation, that is reversed by TGF-β inhibition. A novel three-dimensional (3D) gel-culture system consisting of primary human gingival fibroblasts (GF) and gingival epithelial (GE) cells in collagen gels was applied. GF populations from patients with severe periodontitis degraded collagen gels, which was reduced by TGF-β-receptor kinase inhibition. Up-regulation of TGF-β-responsive genes was evident in GF/GE co-cultures. Furthermore, the TGF-β downstream transducer Smad3C was highly phosphorylated in periodontitis-affected gingiva and 3D cultures. These results imply that TGF-β signaling is involved in fibroblast-epithelial cell interaction in periodontitis, and suggest that the 3D culture system is a useful in vitro model for therapeutic drug screening for periodontitis.

Arterial Stiffness and Hypertension

Arterial stiffness is increasingly recognized as an important prognostic index and potential therapeutic target in patients with hypertension. It is closely linked to, but by no means synonymous with, raised blood pressure, and its physiopathology is still not fully understood. Aortic stiffness and arterial pulse wave reflections are key determinants of elevated central systolic pressure and are associated with adverse cardiovascular outcomes, independent of blood pressure. Indeed, the 2003 European Society of Hypertension guidelines on the management of hypertension acknowledge the potential role of arterial stiffness measurement in clinical management1 and have prompted the publication of a consensus document on the measurement of central blood pressure and hemodynamics.2 A detailed expert consensus document has also been published on the methodologic and clinical issues around arterial stiffness.3 Broader implementation of these techniques into routine care seems inevitable. In this review, we have examined recent research in this field published in Hypertension , focusing on mechanistic work, methods for measuring stiffness, important clinical associations, and effects of treatment. ### Mechanisms and Causes of Arterial Stiffness Hypertension and arterial stiffness are closely associated with age.4 Degeneration of compliant elastin fibers, and deposition of stiffer collagen, is considered a key cause of age-related arterial stiffening. Moreover, blood pressure plays a significant role in determining vessel wall structure, with remodeling occurring to compensate for changes in wall stress. One potential mechanism is through matrix metalloproteinases, which modulate extracellular matrix proteins. When angiotensin II is given to mice, matrix metalloproteinase 9 activity is induced, resulting in enhanced collagen degradation. This improves the intrinsic distensibility of elastic arteries and, thus, blunts any blood pressure rise.5 Impairment of this compensatory mechanism may, therefore, contribute to increased stiffness. The organization of elastic fibers is also important. Inhibition of the vascular adhesion protein semicarbazide-sensitive amine oxidase in a rat model results in …

TGF-β1 + EGF-Initiated Invasive Potential in Transformed Human Keratinocytes Is Coupled to a Plasmin/MMP-10/MMP-1–Dependent Collagen Remodeling Axis: Role for PAI-1

The phenotypic switching called epithelial-to-mesenchymal transition is frequently associated with epithelial tumor cell progression from a comparatively benign to an aggressive, invasive malignancy. Coincident with the emergence of such cellular plasticity is an altered response to transforming growth factor-beta (TGF-beta) as well as epidermal growth factor (EGF) receptor amplification. TGF-beta in the tumor microenvironment promotes invasive traits largely through reprogramming gene expression, which paradoxically supports matrix-disruptive as well as stabilizing processes. ras-transformed HaCaT II-4 keratinocytes undergo phenotypic changes typical of epithelial-to-mesenchymal transition, acquire a collagenolytic phenotype, and effectively invade collagen type 1 gels as a consequence of TGF-beta1 + EGF stimulation in a three-dimensional physiologically relevant model system that monitors collagen remodeling. Enhanced collagen degradation was coupled to a significant increase in matrix metalloproteinase (MMP)-10 expression and involved a proteolytic axis composed of plasmin, MMP-10, and MMP-1. Neutralization of any one component in this cascade inhibited collagen gel lysis. Similarly, addition of plasminogen activator inhibitor type 1 (SERPINE1) blocked collagen degradation as well as the conversion of both proMMP-10 and proMMP-1 to their catalytically active forms. This study therefore identifies an important mechanism in TGF-beta1 + EGF-initiated collagen remodeling by transformed human keratinocytes and proposes a crucial upstream role for plasminogen activator inhibitor type 1-dependent regulation in this event.

Glutathione suppresses TGF-β-induced PAI-1 expression by inhibiting p38 and JNK MAPK and the binding of AP-1, SP-1, and Smad to the PAI-1 promoter

Transforming growth factor (TGF)-beta upregulates plasminogen activator inhibitor type 1 (PAI-1) in a variety of cell types, and PAI-1 is considered to be an essential factor for the development of fibrosis. Our previous studies demonstrated that TGF-beta decreased intracellular glutathione (GSH) content in murine embryonic fibroblasts (NIH/3T3 cells), whereas treatment of the cells with GSH, which restored intracellular GSH concentration, inhibited TGF-beta-induced collagen accumulation by blocking PAI-1 expression and enhancing collagen degradation. In the present study, we demonstrate that GSH blocks TGF-beta-induced PAI-1 promoter activity in NIH/3T3 cells, which is associated with an inhibition of TGF-beta-induced JNK and p38 phosphorylation. Interestingly, although exogenous GSH does not affect phosphorylation and/or nuclear translocation of Smad2/3 and Smad4, it completely eliminates TGF-beta-induced binding of transcription factors to not only AP-1 and SP-1 but also Smad cis elements in the PAI-1 promoter. Decoy oligonucleotides (ODN) studies further demonstrate that AP-1, SP-1, and Smad ODNs abrogate the inhibitory effect of GSH on TGF-beta-induced PAI-1 promoter activity and inhibit TGF-beta-induced expression of endogenous PAI-1. Furthermore, we show that GSH reduces TGF-beta-stimulated reactive oxygen species (ROS) signal. Blocking ROS production with diphenyleneiodonium or scavenging ROS with a superoxide dismutase and catalase mimetic MnTBaP dramatically reduces TGF-beta-induced p38 and JNK phosphorylation as well as PAI-1 gene expression. In composite, these findings suggest that GSH inhibits TGF-beta-stimulated PAI-1 expression in fibroblasts by blocking the JNK/p38 pathway, probably by reducing ROS, which leads to an inhibition of the binding of transcription factors to the AP-1, SP-1, and Smad cis elements in the PAI-1 promoter.