Milk fat globule-epidermal growth factor 8 (MFGE8) prevents intestinal fibrosis

OBJECTIVE

Intestinal fibrosis is considered an inevitable consequence of chronic IBD, leading to stricture formation and need for surgery. During the process of fibrogenesis, extracellular matrix (ECM) components critically regulate the function of mesenchymal cells. We characterised the composition and function of ECM in fibrostenosing Crohn's disease (CD) and control tissues.

DESIGN

Decellularised full-thickness intestinal tissue platforms were tested using three different protocols, and ECM composition in different tissue phenotypes was explored by proteomics and validated by quantitative PCR (qPCR) and immunohistochemistry. Primary human intestinal myofibroblasts (HIMFs) treated with milk fat globule-epidermal growth factor 8 (MFGE8) were evaluated regarding the mechanism of their antifibrotic response, and the action of MFGE8 was tested in two experimental intestinal fibrosis models.

RESULTS

We established and validated an optimal decellularisation protocol for intestinal IBD tissues. Matrisome analysis revealed elevated MFGE8 expression in CD strictured (CDs) tissue, which was confirmed at the mRNA and protein levels. Treatment with MFGE8 inhibited ECM production in normal control HIMF but not CDs HIMF. Next-generation sequencing uncovered functionally relevant integrin-mediated signalling pathways, and blockade of integrin αvβ5 and focal adhesion kinase rendered HIMF non-responsive to MFGE8. MFGE8 prevented and reversed experimental intestinal fibrosis in vitro and in vivo.

CONCLUSION

MFGE8 displays antifibrotic effects, and its administration may represent a future approach for prevention of IBD-induced intestinal strictures.

TMCO3, a Putative K+ :Proton Antiporter at the Golgi Apparatus, Is Important for Longitudinal Growth in Mice and Humans

Isolated short stature, defined as short stature without any other abnormalities, is a common heterogeneous condition in children. Exome sequencing identified the homozygous nonsense variant c.1832G>A/p.(Trp611*) in TMCO3 in two sisters with isolated short stature. Radiological studies, biochemical measurements, assessment of the skeletal status, and three-dimensional bone microarchitecture revealed no relevant skeletal and bone abnormalities in both sisters. The homozygous TMCO3 variant segregated with short stature in the family. TMCO3 transcript levels were reduced by ~50% in leukocyte-derived RNA of both sisters compared with controls, likely due to nonsense-mediated mRNA decay. In primary urinary cells of heterozygous family members, we detected significantly reduced TMCO3 protein levels. TMCO3 is functionally uncharacterized. We ectopically expressed wild-type TMCO3 in HeLa and ATDC5 chondrogenic cells and detected TMCO3 predominantly at the Golgi apparatus, whereas the TMCO3W611* mutant did not reach the Golgi. Coordinated co-expression of TMCO3W611* -HA and EGFP in HeLa cells confirmed intrinsic instability and/or degradation of the mutant. Tmco3 is expressed in all relevant mouse skeletal cell types. Highest abundance of Tmco3 was found in chondrocytes of the prehypertrophic zone in mouse and minipig growth plates where it co-localizes with a Golgi marker. Knockdown of Tmco3 in differentiated ATDC5 cells caused reduced and increased expression of Pthlh and Ihh, respectively. Measurement of long bones in Tmco3tm1b(KOMP)Wtsi knockout mice revealed significant shortening of forelimbs and hindlimbs. TMCO3 is a potential member of the monovalent cation:proton antiporter 2 (CPA2) family. By in silico tools and homology modeling, TMCO3 is predicted to have an N-terminal secretory signal peptide, forms a dimer localized to the membrane, and is organized in a dimerization and a core domain. The core domain contains the CPA2 motif essential for K+ binding and selectivity. Collectively, our data demonstrate that loss of TMCO3 causes growth defects in both humans and mice. © 2023 American Society for Bone and Mineral Research (ASBMR).

Molecular and Cellular Mechanisms of Delayed Fracture Healing in Mmp10 (Stromelysin 2) Knockout Mice

The remodeling of the extracellular matrix is a central function in endochondral ossification and bone homeostasis. During secondary fracture healing, vascular invasion and bone growth requires the removal of the cartilage intermediate and the coordinate action of the collagenase matrix metalloproteinase (MMP)-13, produced by hypertrophic chondrocytes, and the gelatinase MMP-9, produced by cells of hematopoietic lineage. Interfering with these MMP activities results in impaired fracture healing characterized by cartilage accumulation and delayed vascularization. MMP-10, Stromelysin 2, a matrix metalloproteinase with high homology to MMP-3 (Stromelysin 1), presents a wide range of putative substrates identified in vitro, but its targets and functions in vivo and especially during fracture healing and bone homeostasis are not well defined. Here, we investigated the role of MMP-10 through bone regeneration in C57BL/6 mice. During secondary fracture healing, MMP-10 is expressed by hematopoietic cells and its maximum expression peak is associated with cartilage resorption at 14 days post fracture (dpf). In accordance with this expression pattern, when Mmp10 is globally silenced, we observed an impaired fracture-healing phenotype at 14 dpf, characterized by delayed cartilage resorption and TRAP-positive cell accumulation. This phenotype can be rescued by a non-competitive transplant of wild-type bone marrow, indicating that MMP-10 functions are required only in cells of hematopoietic linage. In addition, we found that this phenotype is a consequence of reduced gelatinase activity and the lack of proMMP-9 processing in macrophages. Our data provide evidence of the in vivo function of MMP-10 during endochondral ossification and defines the macrophages as the lead cell population in cartilage removal and vascular invasion. © 2021 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Phosphorylation of Extracellular Bone Matrix Proteins and Its Contribution to Bone Fragility

Phosphorylation of bone matrix proteins is of fundamental importance to all vertebrates including humans. However, it is currently unknown whether increase or decline of total protein phosphorylation levels, particularly in hypophosphatemia-related osteoporosis, osteomalacia, and rickets, contribute to bone fracture. To address this gap, we combined biochemical measurements with mechanical evaluation of bone to discern fracture characteristics associated with age-related development of skeletal fragility in relation to total phosphorylation levels of bone matrix proteins and one of the key representatives of bone matrix phosphoproteins, osteopontin (OPN). Here for the first time, we report that as people age the total phosphorylation level declines by approximately 20% for bone matrix proteins and approximately 30% for OPN in the ninth decade of human life. Moreover, our results suggest that the decline of total protein phosphorylation of extracellular matrix (ECM) contributes to bone fragility, but less pronouncedly than glycation. We theorize that the separation of two sources of OPN negative charges, acidic backbone amino acids and phosphorylation, would be nature's means of assuring that OPN functions in both energy dissipation and biomineralization. We propose that total phosphorylation decline could be an important contributor to the development of osteoporosis, increased fracture risk and skeletal fragility. Targeting the enzymes kinase FamC20 and bone alkaline phosphatase involved in the regulation of matrix proteins' phosphorylation could be a means for the development of suitable therapeutic treatments. © 2018 American Society for Bone and Mineral Research.

Live Imaging of Type I Collagen Assembly Dynamics in Osteoblasts Stably Expressing GFP and mCherry-Tagged Collagen Constructs

Type I collagen is the most abundant extracellular matrix protein in bone and other connective tissues and plays key roles in normal and pathological bone formation as well as in connective tissue disorders and fibrosis. Although much is known about the collagen biosynthetic pathway and its regulatory steps, the mechanisms by which it is assembled extracellularly are less clear. We have generated GFPtpz and mCherry-tagged collagen fusion constructs for live imaging of type I collagen assembly by replacing the α2(I)-procollagen N-terminal propeptide with GFPtpz or mCherry. These novel imaging probes were stably transfected into MLO-A5 osteoblast-like cells and fibronectin-null mouse embryonic fibroblasts (FN-null-MEFs) and used for imaging type I collagen assembly dynamics and its dependence on fibronectin. Both fusion proteins co-precipitated with α1(I)-collagen and remained intracellular without ascorbate but were assembled into α1(I) collagen-containing extracellular fibrils in the presence of ascorbate. Immunogold-EM confirmed their ultrastuctural localization in banded collagen fibrils. Live cell imaging in stably transfected MLO-A5 cells revealed the highly dynamic nature of collagen assembly and showed that during assembly the fibril networks are continually stretched and contracted due to the underlying cell motion. We also observed that cell-generated forces can physically reshape the collagen fibrils. Using co-cultures of mCherry- and GFPtpz-collagen expressing cells, we show that multiple cells contribute collagen to form collagen fiber bundles. Immuno-EM further showed that individual collagen fibrils can receive contributions of collagen from more than one cell. Live cell imaging in FN-null-MEFs expressing GFPtpz-collagen showed that collagen assembly was both dependent upon and dynamically integrated with fibronectin assembly. These GFP-collagen fusion constructs provide a powerful tool for imaging collagen in living cells and have revealed novel and fundamental insights into the dynamic mechanisms for the extracellular assembly of collagen. © 2018 American Society for Bone and Mineral Research.

Crosstalk Between T Lymphocytes and Lung Fibroblasts: Generation of a Hyaluronan-Enriched Extracellular Matrix Adhesive for Monocytes

In immunity and inflammation, T cells are often associated with stromal mesenchymal cells such as fibroblasts. Hyaluronan and proteins that associate with hyaluronan such as versican and tumor necrosis factor-inducible gene-6 (TSG-6) are extracellular matrix (ECM) components that promote leukocyte adhesion, accumulation, and activation. However, the factors responsible for producing this specialized ECM and its impact on inflammatory events are not well understood. In this study, we explored the role of T cells in stimulating lung fibroblasts to produce an ECM that impacts monocyte adhesion. We found that CD3/CD28-activated human CD4+ T cells when co-cultured with human lung fibroblasts stimulated the expression of mRNA for hyaluronan synthase 2 (HAS2) and decreased the expression of hyaluronidase 2 (HYAL2). This led to an increase in the deposition of hyaluronan that formed cable-like structures within the ECM. Co-culturing activated T cells with fibroblasts also led to increased expression and accumulation of TSG-6. Surprisingly, addition of activated CD4+ T cells to the fibroblasts reduced the expression of mRNA for versican, and increased the expression of enzymes that degrade versican, such as ADAMTS4 and ADAMTS9 (a disintegrin and metalloproteinase with a thrombospondin type-1 motif) leading to a decrease in versican in the ECM of the co-cultures. Furthermore, addition of human monocytes to these co-cultures resulted in elevated monocyte adhesion to the cable-like structures in the ECM when compared to controls. These results illustrate the importance of crosstalk between T cells and fibroblasts in promoting the generation of a matrix that is adhesive for monocytes. J. Cell. Biochem. 118: 2118-2130, 2017. © 2016 Wiley Periodicals, Inc.

Src Homology 2 Domain-Containing Inositol 5'-Phosphatase Ameliorates High Glucose-Induced Extracellular Matrix Deposition via the Phosphatidylinositol 3-Kinase/Protein Kinase B Pathway in Renal Tubular Epithelial Cells

A typical hallmark of diabetic kidney disease (DKD) is an excessive deposition of extracellular matrix (ECM) in the glomerulus and renal tubulointerstitium, leading to glomerulosclerosis and tubular interstitial fibrosis. Src homology 2 domain-containing inositol 5'-phosphatase (SHIP) is a negative regulator of the phosphatidylinositol 3-kinase/protein kinase B (PI3K/Akt) signaling. Here, we investigated the effect of SHIP on ECM deposition in diabetic mice and high glucose-stimulated human renal tubular epithelial cells (HK2 cells). The decreased SHIP and increased phospho-Akt (Ser 473, Thr 308) were found in the renal tubular cells of diabetic mice, which were accompanied by overexpression of transforming growth factor-β1 (TGF-β1), α-smooth muscle actin (α-SMA), and secreted collagen type 3 (Col 3) and a low expression of E-cadherin compared to that in normal mice. In vitro research revealed that high glucose-attenuated SHIP expression accompanied the activation of the PI3K/Akt signaling and ECM production. Knocking down SHIP in HK2 cells caused an increase in the levels of phospho-Akt (Ser 473), phospho-Akt (Thr 308), TGF-β1, α-SMA, and secreted Col 3 and a decrease in E-cadherin. Again, either the M90-SHIP plasmid or the PI3K/Akt pathway inhibitor LY294002 could significantly prevent the high glucose-induced increase in TGF-β1, α-SMA, and secreted Col 3 and decreased E-cadherin. Furthermore, we confirmed that inhibition of the TGF-β1 pathway with SB431542 blocked the effect of SHIP knockdown on ECM production in HK2 cells. In summary, our study suggests that decreased SHIP mediates high glucose-induced TGF-β1 upregulation and ECM deposition through activation of the PI3K/Akt pathway in renal tubular cells. J. Cell. Biochem. 118: 2271-2284, 2017. © 2017 Wiley Periodicals, Inc.

hTERT promotes the invasion of gastric cancer cells by enhancing FOXO3a ubiquitination and subsequent ITGB1 upregulation

BACKGROUND AND AIMS

Human telomerase reverse transcriptase (hTERT) plays an important role in cancer invasion, but the relevant mechanism is not well known. This study aims to investigate the role and mechanism of hTERT in gastric cancer metastasis.

DESIGN

Proteomics analysis, qPCR and western blotting were used to screen for hTERT-regulated candidate molecules in gastric cancer invasion. Chromatin immunoprecipitation (ChIP) qPCR was performed to identify the binding sites of hTERT at the regulatory region of the integrin β1 (ITGB1) gene. ChIP assays were further applied to elucidate the transcription factors that bound to the regulatory region. The interactions between hTERT and the transcription factors were tested by co-immunoprecipitation (Co-IP) and glutathione S-transferase (GST) pull-down experiments. Moreover, the revealed pathway was verified in tumour-bearing nude mice and human gastric cancer tissues.

RESULTS

ITGB1 was identified as a downstream gene of hTERT, and there were two hTERT-binding regions within this gene. hTERT alleviated the binding of forkhead box O3 (FOXO3a) to FOXO3a binding element (+9972∼+9978), but it enhanced the binding of forkhead box M1 (FOXM1) to FOXM1 binding element (-1104∼-1109) in ITGB1 gene. Importantly, FOXO3a played a major role in hTERT-induced ITGB1 expression, and the hTERT/murine double minute 2 (MDM2) complex promoted the ubiquitin-mediated degradation of FOXO3a. Moreover, hTERT increased ITGB1 expression in xenograft gastric cancer, and the level of hTERT was positively correlated with that of ITGB1 in human gastric cancer tissues.

CONCLUSIONS

The hTERT/MDM2-FOXO3a-ITGB1 pathway markedly contributes to hTERT-promoted gastric cancer invasion, suggesting that this pathway might be a novel target for the prevention and treatment of gastric cancer metastasis.

Lentiviral Vector-Mediated FoxO1 Overexpression Inhibits Extracellular Matrix Protein Secretion Under High Glucose Conditions in Mesangial Cells

Diabetic nephropathy is characterized by inordinate secretion of extracellular matrix (ECM) proteins from mesangial cells (MCs), which is tightly associated with excessive activation of TGF-β signaling. The forkhead transcription factor O1 (FoxO1) protects mesangial cells from hyperglycemia-induced oxidative stress, which may be involved in ameliorating the redundant secretion of ECM proteins under high glucose conditions. Here, we reported that high glucose elevated the level of p-Akt to attenuate endogenous FoxO1 bioactivities in MCs, accompanied with decreases in the mRNA expressions of catalase (CAT) and superoxide dismutase 2 (SOD2). Meanwhile, the expressions of major ECM proteins-FN and Col I-increased under high glucose conditions, in consistent with the activation of TGF-β/Smad signaling. By contrast, overexpression of nucleus-localized FoxO1 (insensitive to Akt phosphorylation) directly up-regulated the expressions of anti-oxidative enzymes, accompanied with inactivation of TGF-β/Smad3 pathway, as well as decreases of extracellular matrix proteins. Moreover, similar to those MCs overexpressed of nucleus-localized FoxO1 in high glucose conditions, MCs with down-regulation of FoxO1 by small interference-RNA under normal glucose conditions showed increased FN level and activated TGF-β/Smad3 pathway. Our findings link the anti-oxidative activity of FoxO1 and the TGF-β-induced secretion of ECM proteins, indicating the novel role of FoxO1 in protecting MCs under high glucose conditions.

Myxoid variant epithelioid pleural mesothelioma defines a favourable prognosis group: an analysis of 191 patients with pleural malignant mesothelioma

Malignant pleural mesothelioma shows marked cytoarchitectural diversity. The aim of the study was to evaluate how morphological phenotype impacted upon overall survival. 191 cases of malignant pleural mesothelioma with available follow-up were identified, examined and classified according to histological types. The epithelioid mesotheliomas were further subdivided according to morphological subtypes: myxoid, microcystic, tubulopapillary, solid epithelioid, micropapillary and pleomorphic; biphasic mesotheliomas were divided into epithelioid component dominant and sarcomatoid component dominant; pure sarcomatoid mesotheliomas were divided into not otherwise specified, leiomyoid, desmoplastic and heterologous. All cases were confirmed by two experienced observers. Myxoid variant malignant pleural epithelioid mesothelioma was observed to have a favourable overall survival compared with pleomorphic form (p=0.00008). Pleomorphic phenotype had the worst overall survival. Morphological phenotype is an important histological factor that should be included in pathology reports to convey potential favourable prognostic subgroups of patients with mesothelioma.

Extracellularly Extruded Syntaxin-4 Binds to Laminin and Syndecan-1 to Regulate Mammary Epithelial Morphogenesis

Epithelial morphogenesis in the mammary gland proceeds as a consequence of complex cell behaviors including apoptotic cell death and epithelial-mesenchymal transition (EMT); the extracellular matrix (ECM) protein laminin is crucially involved. Syntaxins mediate intracellular vesicular fusion, yet certain plasmalemmal members have been shown to possess latent extracellular functions. In this study, the extracellular subpopulation of syntaxin-4, extruded in response to the induction of differentiation or apoptosis in mammary epithelial cells, was detected. Using a tetracycline-repressive transcriptional system and clonal mammary epithelial cells, SCp2, we found that the expression of cell surface syntaxin-4 elicits EMT-like cell behaviors. Intriguingly, these cells did not up-regulate key transcription factors associated with the canonical EMT such as snail, slug, or twist, and repressed translation of E-cadherin. Concurrently, the cells completely evaded the cellular aggregation/rounding triggered by a potent EMT blocker laminin-111. We found that the recombinant form of syntaxin-4 not only bound to laminin but also latched onto the glycosaminoglycan (GAG) side chains of syndecan-1, a laminin receptor that mediates epithelial morphogenesis. Thus, temporal extracellular extrusion of syntaxin-4 emerged as a novel regulatory element for laminin-induced mammary epithelial cell behaviors. J. Cell. Biochem. 118: 686-698, 2017. © 2016 Wiley Periodicals, Inc.

Transcriptomic Changes in Osteoblasts Following Endothelial Cell-Cocultivation Suggest a Role of Extracellular Matrix in Cellular Interaction

Vascularization is important for bone development, fracture healing and engineering of artificial bone tissue. In the context of bone tissue engineering, it was shown that coimplantation of human primary umbilical vein endothelial cells (HUVECs) and human osteoblasts (hOBs) results in the formation of functional blood vessels and enhanced bone regeneration. Implanted endothelial cells do not only contribute to blood vessel formation, but also support proliferation, cell survival and osteogenic differentiation of coimplanted hOBs. These effects are partially mediated by direct heterotypic cell contacts. In a previous report we could show that cocultivated hOBs strongly increase the expression of genes involved in extracellular matrix (ECM) formation in HUVECs, suggesting that ECM may be involved in the intercellular communication between hOBs and HUVECs. The present study aimed at investigating whether comparable changes occur in hOBs. We therefore performed a microarray analysis of hOBs cultivated in direct contact with HUVECs, revealing 1,004 differentially expressed genes. The differentially expressed genes could be assigned to the functional clusters ECM, proliferation, apoptosis and osteogenic differentiation. The microarray data could be confirmed by performing quantitative real time RT-PCR on selected genes. Furthermore, we could show that the ECM produced by HUVECs increased the expression of the osteogenic differentiation marker alkaline phosphatase (ALP) in hOBs. In summary, our data demonstrate that HUVECs provoke complex changes in gene expression patterns in cocultivated hOBs and that ECM plays and important role in this interaction. J. Cell. Biochem. 117: 1869-1879, 2016. © 2016 Wiley Periodicals, Inc.

Fibrillin-1 Regulates Skeletal Stem Cell Differentiation by Modulating TGFβ Activity Within the Marrow Niche

A full understanding of the microenvironmental factors that control the activities of skeletal stem cells (also known as mesenchymal stem cells [MSCs]) in the adult bone marrow holds great promise for developing new therapeutic strategies to mitigate age-related diseases of bone and cartilage degeneration. Bone loss is an understudied manifestation of Marfan syndrome, a multisystem disease associated with mutations in the extracellular matrix protein and TGFβ modulator fibrillin-1. Here we demonstrate that progressive loss of cancellous bone in mice with limbs deficient for fibrillin-1 (Fbn1(Prx1-/-) mice) is accounted for by premature depletion of MSCs and osteoprogenitor cells combined with constitutively enhanced bone resorption. Longitudinal analyses of Fbn1(Prx1-/-) mice showed incremental bone loss and trabecular microarchitecture degeneration accompanied by a progressive decrease in the number and clonogenic potential of MSCs. Significant paucity of marrow fat cells in the long bones of Fbn1(Prx1-/-) mice, together with reduced adipogenic potential of marrow stromal cell cultures, indicated an additional defect in MSC differentiation. This postulate was corroborated by showing that an Fbn1-silenced osteoprogenitor cell line cultured in the presence of insulin yielded fewer than normal adipocytes and exhibited relatively lower PPARγ levels. Consonant with fibrillin-1 modulation of TGFβ bioavailability, cultures of marrow stromal cells from Fbn1(Prx1-/-) limb bones showed improper overactivation of latent TGFβ. In line with this finding, systemic TGFβ neutralization improved bone mass and trabecular microarchitecture along with normalizing the number of MSCs, osteoprogenitor cells, and marrow adipocytes. Collectively, our findings show that fibrillin-1 regulates MSC activity by modulating TGFβ bioavailability within the microenvironment of marrow niches.

Progenitor cell expansion and impaired hepatocyte regeneration in explanted livers from alcoholic hepatitis

OBJECTIVE

In alcoholic hepatitis (AH), development of targeted therapies is crucial and requires improved knowledge of cellular and molecular drivers in liver dysfunction. The unique opportunity of using explanted livers from patients with AH having undergone salvage liver transplantation allowed to perform more in-depth molecular translational studies.

DESIGN

We studied liver explants from patients with AH submitted to salvage transplantation (n=16), from patients with alcoholic cirrhosis without AH (n=12) and fragments of normal livers (n=16). Hepatic cytokine content was quantified. Hepatocyte function and proliferation and the presence of hepatic progenitor cells (HPCs) were evaluated by immunohistochemistry, western blot or quantitative PCR. Mitochondrial morphology was evaluated by electron microscopy.

RESULTS

Livers from patients with AH showed decreased cytokine levels involved in liver regeneration (tumour necrosis factor α and interleukin-6), as well as a virtual absence of markers of hepatocyte proliferation compared with alcoholic cirrhosis and normal livers. Electron microscopy revealed obvious mitochondrial abnormalities in AH hepatocytes. Importantly, livers from patients with AH showed substantial accumulation of HPCs that, unexpectedly, differentiate only into biliary cells. AH livers predominantly express laminin (extracellular matrix protein favouring cholangiocyte differentiation); consequently, HPC expansion is inefficient at yielding mature hepatocytes.

CONCLUSIONS

AH not responding to medical therapy is associated with lack of expression of cytokines involved in liver regeneration and profound mitochondrial damage along with lack of proliferative hepatocytes. Expansion of HPCs is inefficient to yield mature hepatocytes. Manoeuvres aimed at promoting differentiation of HPCs into mature hepatocytes should be tested in AH.

Artificial matrices with high-sulfated glycosaminoglycans and collagen are anti-inflammatory and pro-osteogenic for human mesenchymal stromal cells

Bone healing has been described to be most efficient if the early inflammatory phase is resolved timely. When the inflammation elevates or is permanently established, bone healing becomes impaired and, moreover, bone destruction often takes place. Systemic disorders such as diabetes and bone diseases like arthritis and osteoporosis are associated with sustained inflammation and delayed bone healing. One goal of biomaterial research is the development of materials/surface modifications which support the healing process by inhibiting the inflammatory bone erosion and suppressing pro-inflammatory mediators and by that promoting the bone repair process. In the present study, the influence of artificial extracellular matrices (aECM) on the interleukin (IL)-1β-induced pro-inflammatory response of human mesenchymal stromal cells (hMSC) was studied. hMSC cultured on aECM composed of collagen I and high-sulfated glycosaminoglycan (GAG) derivatives did not secrete IL-6, IL-8, monocyte chemoattractant protein-1, and prostaglandin E2 in response to IL-1β. The activation and nuclear translocation of nuclear factor κBp65 induced by IL-1β, tumor necrosis factor-α or lipopolysaccharide was abrogated. Furthermore, these aECM promoted the osteogenic differentiation of hMSC as determined by an increased activity of tissue non-specific alkaline phosphatase (TNAP); however, the aECM had no effect on the IL-1β-induced TNAP activity. These data suggest that aECM with high-sulfated GAG derivatives suppress the formation of pro-inflammatory mediators and simultaneously promote the osteogenic differentiation of hMSC. Therefore, these aECM might offer an interesting approach as material/surface modification supporting the bone healing process.

Decreased Mechanical Strength and Collagen Content in SPARC-Null Periodontal Ligament Is Reversed by Inhibition of Transglutaminase Activity

The periodontal ligament (PDL) is a critical tissue that provides a physical link between the mineralized outer layer of the tooth and the alveolar bone. The PDL is composed primarily of nonmineralized fibrillar collagens. Expression of secreted protein acidic and rich in cysteine (SPARC/osteonectin), a collagen-binding matricellular protein, has been shown to be essential for collagen homeostasis in PDL. In the absence of SPARC, PDL collagen fibers are smaller and less dense than fibers that constitute WT PDL. The aim of this study was to identify cellular mechanisms by which SPARC affected collagen fiber assembly and morphology in PDL. Cross-linking of fibrillar collagens is one parameter that is known to affect insoluble collagen incorporation and fiber morphology. Herein, the reduction in collagen fiber size and quantity in the absence of SPARC expression was shown to result in a PDL with reduced molar extraction force in comparison to that of WT mice (C57Bl/6J). Furthermore, an increase in transglutaminase activity was found in SPARC-null PDL by biochemical analyses that was supported by immunohistochemical results. Specifically, collagen I was identified as a substrate for transglutaminase in PDL and transglutaminase activity on collagen I was found to be greater in SPARC-null tissues in comparison to WT. Strikingly, inhibition of transglutaminase activity in SPARC-null PDL resulted in increases in both collagen fiber thickness and in collagen content, whereas transglutaminase inhibitors injected into WT mice resulted in increases in collagen fiber thickness only. Furthermore, PDL treated with transglutaminase inhibitors exhibited increases in molar extraction force in WT and in SPARC-null mice. Thus, SPARC is proposed to act as a critical regulator of transglutaminase activity on collagen I with implications for mechanical strength of tissues.

A novel role of annexin A2 in human type I collagen gene expression

The fibrillar collagen scaffold of the extracellular matrix provides a structural framework for cells in tissues and regulates intercellular communication; its disregulation has been associated with tumour development and progression. Previous work has shown that expression of type I collagen, the most abundant mammalian extracellular matrix protein, is decreased in chemically or virally transformed cells. This negative regulation could be mapped to a proximal COL1A2 promoter element spanning a CME (Collagen Modulating Element) site in SV40‐transformed human fibroblasts (SV‐WI38) that binds an unknown repressing protein. By magnetic bead pull‐down, we observed a multi‐protein complex bound to the CME with preference for single‐stranded over conventional double‐stranded DNA. MALDI‐TOF mass spectrometry of the CME‐binding protein complex revealed involvement of nuclear annexin A2 (AnxA2) which was increased in SV40‐transformed cells. Further EMSA analysis demonstrated that AnxA2 did not directly bind to the DNA but stabilised the complex and led to an increase in protein binding to the CME in SV‐WI38 but not untransformed WI38 cells. Knockdown of AnxA2 by siRNA increased type I collagen production in both WI38 and SV‐WI38 cells; however, these effects were not mediated at the transcriptional level. Rather, our data indicate a novel functional role of AnxA2 in the negative post‐transcriptional regulation of type I collagen synthesis in human fibroblasts. In SV40‐transformed cells, AnxA2 is accumulated at the proximal COL1A2 promoter region, suggesting close association with the transcriptional machinery that possibly facilitates binding to the emerging mRNA, eventually contributing to overall repression of type I collagen protein synthesis. J. Cell. Biochem. 116: 408–417, 2015. © 2014 The Authors. Journal of Cellular Biochemistry published by Wiley Periodicals, Inc.

Fibulin-5 is a tumour suppressor inhibiting cell migration and invasion in ovarian cancer

AIMS

Fibulin-5 is an extracellular matrix (ECM) glycoprotein which has a role in the organisation and stabilisation of ECM structures and regulating cell proliferation and tumourigenesis. Here, the expression of fibulin-5 and its functional effects on the migration and invasion of ovarian cancer cells were assessed.

METHODS

Expression of fibulin-5 was detected in 44 ovarian tumour tissues by qRT-PCR, Western blotting and immunohistochemistry. We performed cell migration and invasion assays, and cell cycle analysis in fibulin-5 transfected SKOV3 (SKOV3-FBLN5) cells and the parental SKOV3 cells. We further examined the expression of three tissue inhibitors of metalloproteinases (TIMPs) and seven matrix metalloproteinases (MMPs) by RT-PCR.

RESULTS

mRNA and protein expression of fibulin-5 were down-regulated (0.05-fold and 0.1-fold) in ovarian carcinomas compared with control tissues (p<0.01 and p=0.022). In wound-healing and invasion assays, significantly fewer SKOV3-FBLN5 cells than SKOV3 control cells migrated and invaded (39.1%, p=0.046 and 70%, p=0.03, respectively), which was reversed by siRNA-treatment. Overexpression of fibulin-5 induced G2/M arrest and increased cyclin B1, CDC2 and CDC25C. Expression of TIMP-2 (0.56-fold), MMP-3 (0.43-fold) and MMP-13 (0.18-fold) was lower and MMP-9 expression (2.20-fold) was higher in SKOV3-FBLN5 cells than in control cells.

CONCLUSIONS

Fibulin-5 is significantly down-regulated in ovarian carcinoma and acts as a tumour suppressor by inhibiting the migration and invasion of ovarian cancer cells.

Plasma levels of matrix metalloproteinase-2 and -9 in male and female patients with cirrhosis of different aetiologies

BACKGROUND

Liver fibrosis and cirrhosis may be reversible in some circumstances. Reliable diagnostic tests are necessary for monitoring hepatic fibrogenesis. Matrix metalloproteinase (MMP)-2 and MMP-9 are two of the major MMPs in the circulation and may be most relevant to hepatic fibrosis. The behaviour of MMPs may be significantly different in men and women and may also differ in cases of cirrhosis of various aetiologies.

AIMS

To evaluate the manifestations of MMP-2 and MMP-9 in liver cirrhosis of different aetiologies in men and women and to compare these patterns with those of healthy controls.

METHODS

We measured MMP-2 and MMP-9 levels in plasma samples from 112 patients with cirrhosis and 112 age- and gender-matched healthy controls. We then correlated these MMP levels with gender and disease aetiology.

RESULTS

Plasma MMP-2 concentrations in patients showed a trend towards increasing values with cirrhosis severity and were markedly increased in patients regardless of gender and aetiology compared with healthy controls (p<0.0001). Plasma mean MMP-9 levels were comparable in patients with cirrhosis and controls, but increased with disease severity. They were significantly lower in patients (130.5 ng/mL), female patients (85.4 ng/mL) and male patients (150.4 ng/mL) with mild cirrhosis than in controls (163.2 ng/mL), female controls (162.5 ng/mL) and male controls (163.3 ng/mL) (p=0.001, 0.041 and 0.009, respectively). MMP-2 and MMP-9 concentrations were not significantly different between genders among controls and among various patient subgroups.

CONCLUSIONS

Plasma MMP-2 level may be a useful diagnostic marker for monitoring hepatic fibrogenesis in patients with disease of different aetiologies.

High-resolution molecular validation of self-renewal and spontaneous differentiation in clinical-grade adipose-tissue derived human mesenchymal stem cells

Improving the effectiveness of adipose-tissue derived human mesenchymal stromal/stem cells (AMSCs) for skeletal therapies requires a detailed characterization of mechanisms supporting cell proliferation and multi-potency. We investigated the molecular phenotype of AMSCs that were either actively proliferating in platelet lysate or in a basal non-proliferative state. Flow cytometry combined with high-throughput RNA sequencing (RNASeq) and RT-qPCR analyses validate that AMSCs express classic mesenchymal cell surface markers (e.g., CD44, CD73/NT5E, CD90/THY1, and CD105/ENG). Expression of CD90 is selectively elevated at confluence. Self-renewing AMSCs express a standard cell cycle program that successively mediates DNA replication, chromatin packaging, cyto-architectural enlargement, and mitotic division. Confluent AMSCs preferentially express genes involved in extracellular matrix (ECM) formation and cellular communication. For example, cell cycle-related biomarkers (e.g., cyclins E2 and B2, transcription factor E2F1) and histone-related genes (e.g., H4, HINFP, NPAT) are elevated in proliferating AMSCs, while ECM genes are strongly upregulated (>10-fold) in quiescent AMSCs. AMSCs also express pluripotency genes (e.g., POU5F1, NANOG, KLF4) and early mesenchymal markers (e.g., NES, ACTA2) consistent with their multipotent phenotype. Strikingly, AMSCs modulate expression of WNT signaling components and switch production of WNT ligands (from WNT5A/WNT5B/WNT7B to WNT2/WNT2B), while upregulating WNT-related genes (WISP2, SFRP2, and SFRP4). Furthermore, post-proliferative AMSCs spontaneously express fibroblastic, osteogenic, chondrogenic, and adipogenic biomarkers when maintained in confluent cultures. Our findings validate the biological properties of self-renewing and multi-potent AMSCs by providing high-resolution quality control data that support their clinical versatility.

Pathobiology of liver fibrosis: a translational success story

Reversibility of hepatic fibrosis and cirrhosis following antiviral therapy for hepatitis B or C has advanced the prospect of developing antifibrotic therapies for patients with chronic liver diseases, especially non-alcoholic steatohepatitis. Mechanisms of fibrosis have focused on hepatic stellate cells, which become fibrogenic myofibroblasts during injury through 'activation', and are at the nexus of efforts to define novel drug targets. Recent studies have clarified pathways of stellate cell gene regulation and epigenetics, emerging pathways of fibrosis regression through the recruitment and amplification of fibrolytic macrophages, nuanced responses of discrete inflammatory cell subsets and the identification of the 'ductular reaction' as a marker of severe injury and repair. Based on our expanded knowledge of fibrosis pathogenesis, attention is now directed towards strategies for antifibrotic therapies and regulatory challenges for conducting clinical trials with these agents. New therapies are attempting to: 1) Control or cure the primary disease or reduce tissue injury; 2) Target receptor-ligand interactions and intracellular signaling; 3) Inhibit fibrogenesis; and 4) Promote resolution of fibrosis. Progress is urgently needed in validating non-invasive markers of fibrosis progression and regression that can supplant biopsy and shorten the duration of clinical trials. Both scientific and clinical challenges remain, however the past three decades of steady progress in understanding liver fibrosis have contributed to an emerging translational success story, with realistic hopes for antifibrotic therapies to treat patients with chronic liver disease in the near future.

Is expression of rat breast matrix components influenced by estrogen, progestins and tibolone?

AIM

To study the effects of estrogen therapy, alone or combined with progestogens, and of tibolone on the expression of heparanase (HSPE), extracellular matrix metalloproteinases 2 and 9 (MMP-2 and MMP-9), perlecan and proliferating cell nuclear antigen (PCNA) in normal breast tissue.

METHODS

Thirty 250-day-old Wistar rats were castrated and 3 weeks later received one of the following treatments by gavage for 5 weeks: (1) estradiol benzoate; (2) estradiol benzoate + medroxyprogesterone acetate; (3) estradiol benzoate + norethisterone acetate; (4) estradiol benzoate + dydrogesterone; (5) tibolone; (6) placebo. Following treatment, the expressions of mRNA for HSPE, MMP-2 and MMP-9 were analyzed by real-time PCR and the protein expressions of HSPE, MMP-2, MMP-9, perlecan and PCNA were quantified by immunohistochemistry.

RESULTS

There was a statistically significant difference among the groups for the expression of HSPE mRNA due to high levels in the tibolone group. The groups differed in terms of PCNA, with lower levels found in the tibolone group followed by the estradiol benzoate + dydrogesterone group. A statistically significant positive correlation was observed for PCNA versus perlecan and MMP-9.

CONCLUSIONS

There was no difference in the effects of combinations of estradiol and different progestogens on extracellular matrix components, and breast cell proliferation was associated with increases in perlecan and MMP-9.

Effects of macitentan and its active metabolite on cultured human systemic sclerosis and control skin fibroblasts

OBJECTIVE

To investigate the effects of the endothelin 1 (ET-1) receptor antagonists (ETRA) macitentan, its active metabolite ACT-132577, and bosentan on myofibroblast activation and extracellular matrix production induced by ET-1 in cultured systemic sclerosis (SSc) and control skin fibroblasts.

METHODS

Fibroblasts were obtained from skin biopsies of 6 patients with SSc and 5 healthy subjects. Some cultured cells were untreated or treated with macitentan, ACT-132577, or bosentan alone (10 μM). Other cultured cells were treated with ET-1 alone (100 nM) or with ETRA, and after 1 h, also with ET-1. After 48 h of treatment, myofibroblast activation was investigated to evaluate the α-smooth muscle actin (α-SMA) expression by immunofluorescence; type I collagen (COL-1) and fibronectin (FN) were investigated by immunocytochemistry, Western blotting, and quantitative real-time PCR (qRT-PCR). Statistical analysis was performed by the nonparametric Mann-Whitney U test.

RESULTS

In cultured SSc skin fibroblasts, only the treatment with macitentan significantly reduced the basal level of α-SMA expression (p = 0.03 vs untreated cells). Macitentan also significantly reduced the basal level of COL-1 synthesis, similarly to bosentan (p < 0.05 vs untreated cells). Macitentan or ACT-132577 antagonized the ability of ET-1 to further induce α-SMA expression (p = 0.03), COL-1, and FN synthesis (p = 0.03, p = 0.005); bosentan showed similar effects. These results obtained by immunofluorescence and immunocytochemistry were confirmed by Western blotting and qRT-PCR. The downregulatory effects exerted by ETRA were observed also in cultured human control skin fibroblasts.

CONCLUSION

Macitentan and ACT-132577 seem to downregulate in vitro the profibrotic myofibroblast phenotype induced by ET-1 in cultured human SSc skin fibroblasts.

Bone regeneration with osteogenically enhanced mesenchymal stem cells and their extracellular matrix proteins

Although bone has remarkable regenerative capacity, about 10% of long bone fractures and 25% to 40% of vertebral fusion procedures fail to heal. In such instances, a scaffold is employed to bridge the lesion and accommodate osteoprogenitors. Although synthetic bone scaffolds mimic some of the characteristics of bone matrix, their effectiveness can vary because of biological incompatibility. Herein, we demonstrate that a composite prepared with osteogenically enhanced mesenchymal stem cells (OEhMSCs) and their extracellular matrix (ECM) has an unprecedented capacity for the repair of critical-sized defects of murine femora. Furthermore, OEhMSCs do not cause lymphocyte activation, and ECM/OEhMSC composites retain their in vivo efficacy after cryopreservation. Finally, we show that attachment to the ECM by OEhMSCs stimulates the production of osteogenic and angiogenic factors. These data demonstrate that composites of OEhMSCs and their ECM could be utilized in the place of autologous bone graft for complex orthopedic reconstructions.

Adiponectin mediated APPL1-AMPK signaling induces cell migration, MMP activation, and collagen remodeling in cardiac fibroblasts

Defects in adiponectin action have been implicated in the development of cardiac dysfunction in obesity and diabetes. Cardiac fibroblasts play an important role in regulating extracellular matrix remodeling yet little is known regarding the direct effects of adiponectin on cardiac fibroblasts. In this study, we first demonstrated temporal relocalization of cellular APPL1 in response to adiponectin in primary cardiac fibroblasts and that siRNA-mediated knockdown of APPL1 attenuated stimulation of AMPK by adiponectin. The cell surface content of MT1-MMP and activation of MMP2 were induced by adiponectin and these responses were dependent on AMPK signaling. Enhanced MMP activity facilitated increased fibroblast migration in response to adiponectin which was also prevented by inhibition of AMPK, with no change in cell proliferation observed. Collagen and elastin immunofluorescence demonstrated reorganization of the extracellular matrix in accordance with increased MMP activity, whereas quantitative mRNA analysis, (3) H-proline incorporation and picrosirius red assays showed no change in intracellular or extracellular total collagen levels in response to adiponectin. In summary, these data are the first to report the adiponectin stimulated APPL1-AMPK signaling axis in cardiac fibroblasts and characterize MT1-MMP translocation, MMP2 activity and cell migration as functional outcomes. These effects may be of significance in heart failure associated with obesity and diabetes.

Increased osteopontin contributes to inhibition of bone mineralization in FGF23-deficient mice

Excessive FGF23 has been identified as a pivotal phosphaturic factor leading to renal phosphate-wasting and the subsequent development of rickets and osteomalacia. In contrast, loss of FGF23 in mice (Fgf23(-/-) ) leads to high serum phosphate, calcium, and 1,25-vitamin D levels, resulting in early lethality attributable to severe ectopic soft-tissue calcifications and organ failure. Paradoxically, Fgf23(-/-) mice exhibit a severe defect in skeletal mineralization despite high levels of systemic mineral ions and abundant ectopic mineralization, an abnormality that remains largely unexplained. Through use of in situ hybridization, immunohistochemistry, and immunogold labeling coupled with electron microscopy of bone samples, we discovered that expression and accumulation of osteopontin (Opn/OPN) was markedly increased in Fgf23(-/-) mice. These results were confirmed by qPCR analyses of Fgf23(-/-) bones and ELISA measurements of serum OPN. To investigate whether elevated OPN levels were contributing to the bone mineralization defect in Fgf23(-/-) mice, we generated Fgf23(-/-) /Opn(-/-) double-knockout mice (DKO). Biochemical analyses showed that the hypercalcemia and hyperphosphatemia observed in Fgf23(-/-) mice remained unchanged in DKO mice; however, micro-computed tomography (µCT) and histomorphometric analyses showed a significant improvement in total mineralized bone volume. The severe osteoidosis was markedly reduced and a normal mineral apposition rate was present in DKO mice, indicating that increased OPN levels in Fgf23(-/-) mice are at least in part responsible for the osteomalacia. Moreover, the increased OPN levels were significantly decreased upon lowering serum phosphate by feeding a low-phosphate diet or after deletion of NaPi2a, indicating that phosphate levels contribute in part to the high OPN levels in Fgf23(-/-) mice. In summary, our results suggest that increased OPN is an important pathogenic factor mediating the mineralization defect and the alterations in bone metabolism observed in Fgf23(-/-) bones.