Proteomic characterization of human early pro-angiogenic cells.

Early pro-angiogenic cells (EPCs) have been shown to be involved in neovascularization, angiogenesis and re-endothelialization and cathepsin L inhibition blunted their pro-angiogenic effect. In the present study, we have analysed and mapped the proteome and secretome of human EPCs, utilizing a combination of difference in-gel electrophoresis (DIGE) and shotgun proteomics. A population of 206 protein spots were analysed, with 171 being identified in the cellular proteome of EPCs. 82 proteins were identified in their conditioned medium, including the alternative macrophage markers C-C motif chemokine 18 (CCL18) and the hemoglobin scavenger receptor CD163 as well as platelet factor 4 (CXCL4) and platelet basic protein (CXCL7) with "platelet alpha granule" being returned as the top category according to the Gene Ontology Annotation. Apart from cathepsin L, the cathepsin L inhibitor also attenuated the release of a wide range of other cathepsins and lysosomal proteins such as legumain, but stimulated the secretion of members of the S100 protein family. The data presented here are the most comprehensive characterization of protein expression and secretion in human EPCs to date and highlight the potential importance of cysteine proteases in the processing of platelet factors for their pro-angiogenic potential. This article is part of a special issue entitled, "Cardiovascular Stem Cells Revisited".

Antifibrotic properties of relaxin: in vivo mechanism of action in experimental renal tubulointerstitial fibrosis.

This study examined the efficacy and in vivo mechanism of action of the antifibrotic hormone, relaxin, in a mouse model of unilateral ureteric obstruction (UUO). Kidney fibrosis was assessed in recombinant human gene-2 relaxin-treated animals maintained for 3 and 9 d after UUO. Results were compared with untreated and unoperated animals (d 0). Total collagen, collagen subtypes (I, IV), TGF-ß2 production, mothers against decapentaplegic homolog 2 (Smad2) phosphorylation, myofibroblast differentiation, mitosis, and apoptosis were all progressively increased by UUO (all P<0.05 vs. d 0 group at d 3 and d 9), whereas TGF-ß1 production was increased and vascular endothelial growth factor expression (angiogenesis) decreased at d 9 (both P<0.05 vs. d 0). A progressive increase in matrix metalloproteinase (MMP)-2 after UUO suggested that it was reactive to the increased fibrogenesis. Conversely, MMP-9 was decreased at d 9, whereas its inhibitor tissue inhibitor of metalloproteinase-1 progressively decreased after UUO. Human gene-2 relaxin pretreatment of animals from 4 d prior to UUO ameliorated the increase in total collagen, collagen IV, Smad2 phosphorylation, and myofibroblasts at both time points (all P<0.05 vs. untreated groups) and inhibited TGF-ß2 production and cell proliferation (both P<0.05 vs. untreated groups) with a trend toward normalizing vascular endothelial growth factor expression at d 9, with no effect on TGF-ß1 production or apoptosis. The relaxin-mediated regulation of MMPs and tissue inhibitor of metalloproteinases in this model was not consistent with its antifibrotic properties. The beneficial effects of relaxin were lost when treatment was stopped. These findings establish that relaxin can inhibit both early and established phases of tubulointerstitial fibrosis, primarily by suppressing cell proliferation, myofibroblast differentiation, and collagen production. Not all of these effects paralleled changes to TGF-ß-Smad signaling.

Synthesis and biological evaluation of oxadiazole derivatives as inhibitors of soluble guanylyl cyclase.

Soluble guanylyl cyclase (sGC) is an ubiquitously expressed enzyme that generates the second messenger cGMP and hence, leads to a number of physiological responses including vasodilation, inhibition of platelet aggregation and neurotransmission. Whilst many activating and stimulating modulators of sGC were identified and studied in recent years, only two selective inhibitors are known: ODQ and NS 2028. Furthermore, a synthetic approach to these inhibitors has not been reported yet. Herein, we describe a novel and efficient synthesis of these inhibitors, as well as the preparation of three different classes of NS 2028 analogues. Biological evaluation of this library using rat aortic smooth muscle cells revealed four new compounds with good to moderate sGC inhibitory activity. Our experiments underline the major importance of the oxadiazole ring in ODQ and NS 2028 for the efficiency of this class of inhibitors.

Role of endothelin receptors on basal and endothelin-1-stimulated lung myofibroblast proliferation.

Proliferation of myofibroblasts (MYF) contributes to numerous lung disorders. Endothelin-1 (ET-1) production is increased in various lung diseases and could contribute to lung remodelling. The respective roles of ETA and ETB receptors (ETA-R, ETB-R) and the role of endogenous ET-1 production by lung MYF on proliferation of MYF remain uncertain. Rat lung MYF were isolated and 3H-thymidine and 3H-leucine incorporation assays were completed in the presence of a selective ETA-R antagonist, a selective ETB-R antagonist, or a combination of both. Receptor expression was evaluated by confocal imaging, and ET-1 levels were measured by ELISA. Confocal microscopy revealed abundant ETA-R and ETB-R expression on lung MYF. ET-1 (10 nmol/L) stimulated MYF proliferation and protein synthesis through PI3-kinase and p38 pathways. Although neither selective ETA-R blockade (BQ-123, 1 micromol/L) nor selective ETB-R blockade (BQ-788, 1 micromol/L) alone inhibited proliferation or protein synthesis, their combination almost completely abolished ET-1 mitogenic effect. Surprisingly, basal MYF proliferation was increased by selective blockade of either ETA-R or ETB-R alone, but not by dual blockade. ET-1 levels were not affected by the antagonists. Our findings indicate that both the ETA-R and the ETB-R regulate basal and stimulated lung MYF proliferation and suggest possible interactions between the receptors.

SM16, an orally active TGF-beta type I receptor inhibitor prevents myofibroblast induction and vascular fibrosis in the rat carotid injury model.

OBJECTIVE: TGF-beta plays a significant role in vascular injury-induced stenosis. This study evaluates the efficacy of a novel, small molecule inhibitor of ALK5/ALK4 kinase, in the rat carotid injury model of vascular fibrosis. METHODS AND RESULTS: The small molecule, SM16, was shown to bind with high affinity to ALK5 kinase ATP binding site using a competitive binding assay and biacore analysis. SM16 blocked TGF-beta and activin-induced Smad2/3 phosphorylation and TGF-beta-induced plasminogen activator inhibitor (PAI)-luciferase activity in cells. Good overall selectivity was demonstrated in a large panel of kinase assays, but SM16 also showed nanomolar inhibition of ALK4 and weak (micromolar) inhibition of Raf and p38. In the rat carotid injury model, SM16 dosed once daily orally at 15 or 30 mg/kg SM16 for 14 days caused significant inhibition of neointimal thickening and lumenal narrowing. SM16 also prevented induction of adventitial smooth muscle alpha-actin-positive myofibroblasts and the production of intimal collagen, but did not decrease the percentage of proliferative cells. CONCLUSIONS: These results are the first to demonstrate the efficacy of an orally active, small-molecule ALK5/ALK4 inhibitor in a vascular fibrosis model and suggest the potential therapeutic application of these inhibitors in vascular fibrosis.

Interleukin-31 stimulates production of inflammatory mediators from human colonic subepithelial myofibroblasts.

Interleukin (IL)-31 is mainly produced by CD4+ T cells, in particular T cells skewed toward a Th2 phenotype. Here we report for the first time that IL-31 stimulates secretion of proinflammatory cytokines, chemokines and matrix metalloproteinases (MMPs) from human colonic subepithelial myofibroblasts (SEMFs). The effects of IL-31 were investigated by cDNA microarrays, enzyme-linked immunosorbent assay, and real-time PCR. IL-31 effectively induced chemokines [IL-8, GRO-alpha (growth-related oncogene-alpha), MCP-3 (monocyte chemoattractant protein-3), CXCL3, CCL13 and CCL15], proinflammatory cytokines (IL-6, IL-16 and IL-32) and matrix metalloproteinases (MMP-1, MMP-3, MMP-25 and MMP-7). IL-31 dose-dependently induced secretion of IL-6, IL-8, GRO-alpha, MCP-3, MMP-1 and MMP-3. The effects of IL-31 were comparable to the effects of IL-17A. IL-31 and IL-17A showed additive effects on IL-6, IL-8, GRO-alpha, MCP-3, MMP-1 and MMP-3 secretion. In conclusion, we demonstrated that IL-31 is a potent inducer of proinflammatory mediators in human colonic SEMFs. IL-31 may function as a proinflammatory cytokine derived from Th2 cells.

The sphingosine 1-phosphate receptor S1P2 triggers hepatic wound healing.

Sphingosine 1-phosphate (S1P) is a bioactive sphingolipid produced by sphingosine kinase (SphK1 and 2). We previously showed that S1P receptors (S1P1, S1P2, and S1P3) are expressed in hepatic myofibroblasts (hMF), a population of cells that triggers matrix remodeling during liver injury. Here we investigated the function of these receptors in the wound healing response to acute liver injury elicited by carbon tetrachloride, a process that associates hepatocyte proliferation and matrix remodeling. Acute liver injury was associated with the induction of S1P2, S1P3, SphK1, and SphK2 mRNAs and increased SphK activity, with no change in S1P1 expression. Necrosis, inflammation, and hepatocyte regeneration were similar in S1P2-/- and wild-type (WT) mice. However, compared with WT mice, S1P2-/- mice displayed reduced accumulation of hMF, as shown by lower induction of smooth muscle alpha-actin mRNA and lower induction of TIMP-1, TGF-beta1, and PDGF-BB mRNAs, overall reflecting reduced activation of remodeling in response to liver injury. The wound healing response was similar in S1P3-/- and WT mice. In vitro, S1P enhanced proliferation of cultured WT hMF, and PDGF-BB further enhanced the mitogenic effect of S1P. In keeping with these findings, PDGF-BB up-regulated S1P2 and SphK1 mRNAs, increased SphK activity, and S1P2 induced PDGF-BB mRNA. These effects were blunted in S1P2-/- cells, and S1P2-/- hMF exhibited reduced mitogenic and comitogenic responses to S1P. These results unravel a novel major role of S1P2 in the wound healing response to acute liver injury by a mechanism involving enhanced proliferation of hMF.

Selective clearance of macrophages in atherosclerotic plaques by the protein synthesis inhibitor cycloheximide.

Macrophages are an essential component of unstable atherosclerotic plaques and play a pivotal role in the destabilization process. We have demonstrated previously that local delivery of the mammalian target of rapamycin (mTOR) inhibitor everolimus selectively clears macrophages in rabbit plaques. Because mTOR controls mRNA translation, inhibition of protein synthesis might induce selective macrophage cell death. We therefore investigated in the present study the effect of the protein synthesis inhibitor cycloheximide on macrophage and smooth muscle cell (SMC) viability. In vitro studies with cultured macrophages and SMCs showed that cycloheximide induced selective apoptosis of macrophages in a concentration- and time-dependent manner. Moreover, macrophages could be selectively depleted in rabbit carotid artery rings with collar-induced atherosclerotic plaques after in vitro treatment with cycloheximide. Local in vivo administration of cycloheximide via osmotic minipumps to rabbit carotid arteries with collar-induced atherosclerotic plaques significantly reduced the macrophage but not the SMC content. Cycloheximide-treated plaques showed signs of apoptosis (increased terminal deoxynucleotidyl transferase end labeling and fluorescein isothiocyanate-Val-Ala-dl-Asp(O-methyl)-fluoromethylketone labeling) that did not colocalize with SMCs. Organ chamber studies demonstrated that the functionality of SMCs and the endothelium were not influenced by cycloheximide treatment. All together, these findings demonstrate that cycloheximide decreases the macrophage load in atherosclerotic plaques by induction of apoptosis without changing SMC content or contractility.

Subepithelial myofibroblasts are novel nonprofessional APCs in the human colonic mucosa.

The human gastrointestinal mucosa is exposed to a diverse normal microflora and dietary Ags and is a common site of entry for pathogens. The mucosal immune system must respond to these diverse signals with either the initiation of immunity or tolerance. APCs are important accessory cells that modulate T cell responses which initiate and maintain adaptive immunity. The ability of APCs to communicate with CD4+ T cells is largely dependent on the expression of class II MHC molecules by the APCs. Using immunohistochemistry, confocal microscopy, and flow cytometry, we demonstrate that alpha-smooth muscle actin(+), CD90+ subepithelial myofibroblasts (stromal cells) constitutively express class II MHC molecules in normal colonic mucosa and that they are distinct from professional APCs such as macrophages and dendritic cells. Primary isolates of human colonic myofibroblasts (CMFs) cultured in vitro were able to stimulate allogeneic CD4+ T cell proliferation. This process was dependent on class II MHC and CD80/86 costimulatory molecule expression by the myofibroblasts. We also demonstrate that CMFs, engineered to express a specific DR4 allele, can process and present human serum albumin to a human serum albumin-specific and DR4 allele-restricted T cell hybridoma. These studies characterize a novel cell phenotype which, due to its strategic location and class II MHC expression, may be involved in capture of Ags that cross the epithelial barrier and present them to lamina propria CD4+ T cells. Thus, human CMFs may be important in regulating local immunity in the colon.

Regulation of amphiregulin and epiregulin expression in human colonic subepithelial myofibroblasts.

Amphiregulin and epiregulin belong to the epidermal growth factor (EGF) family, and act as mitogenic stimulators via binding to EGF receptors (EGFRs). Amphiregulin and epiregulin are thought to play a role in regenerative responses in the gastrointestinal tract. In this study, we investigated secretion of amphiregulin and epiregulin in human colonic subepithelial myofibroblasts (SEMFs). The mRNA expression and protein secretion of amphiregulin and epiregulin were evaluated by Northern blotting and Western blotting, respectively. The trophic effects of amphiregulin and epiregulin on SEMFs were analyzed by MTT assays. Amphiregulin and epiregulin mRNAs were not detected in unstimulated SEMFs. Among the various cytokines and growth factors, interleukin-1beta, tumor necrosis factor-alpha, and EGF strongly induced amphiregulin and epiregulin mRNA expression. These responses were markedly reduced by AG1478, a specific inhibitor of EGF receptor tyrosine kinases. Amphiregulin and epiregulin secretion were also detected at the protein level. MTT assays demonstrated that amphiregulin and epiregulin stimulate the proliferation of SEMFs. We demonstrated expression of amphiregulin and epiregulin in SEMFs. Amphiregulin and epiregulin may play an important role in the mechanism underlying wound healing in damaged colonic mucosa.

Nicotine inhibits myofibroblast differentiation in human gingival fibroblasts.

Cigarette smoking has been suggested as a risk factor for several periodontal diseases. It has also been found that smokers respond less favorably than non-smokers to periodontal therapy. Previous work in our lab has shown that nicotine inhibits human gingival cell migration. Since myofibroblasts play an important role in wound closure, we asked if nicotine affects gingival wound healing process by regulating myofibroblast differentiation. Human gingival fibroblasts (HGFs) from two patients were cultured in 10% fetal bovine serum cell culture medium. Cells were pretreated with different doses of nicotine (0, 0.01, 0.1, and 1 mM) for 2 h, and then incubated with transforming growth factor beta (TGF-beta1) (0, 0.25, 0.5, and 1 ng/ml) with or without nicotine for 30 h. The expression level of alpha-smooth muscle actin (alpha-SMA), a specific marker for myofibroblasts, was analyzed by Western blots, immunocytochemistry, and real-time polymerase chain reaction (real-time PCR). Phosphorylated p38 mitogen-activated protein kinase (Phospho-p38 MAPK) activity was analyzed by Western blots. TGF-beta1 induced an increase of alpha-SMA protein and mRNA expression, while nicotine (1 mM) inhibited the TGF-beta1-induced expression of alpha-SMA but not beta-actin. Nicotine treatment down-regulated TGF-beta1-induced p38 MAPK phosphorylation. Our results demonstrated for the first time that nicotine inhibits myofibroblast differentiation in human gingival fibroblasts in vitro; supporting the hypothesis that delayed wound healing in smokers may be due to decreased wound contraction by myofibroblasts.

Butyrate blocks interferon-gamma-inducible protein-10 release in human intestinal subepithelial myofibroblasts.

BACKGROUND: Interferon (IFN)-gamma-inducible protein (IP)-10 is a chemoattractant for CXCR 3-expressing T lymphocytes and monocytes. IP-10 has been reported to mediate chronic inflammation such as that in inflammatory bowel disease (IBD). However, the local secretion of IP-10 in the intestine remains unclear. In this study, we investigated IP-10 secretion in human colonic subepithelial myofibroblasts (SEMFs). METHODS: IP-10 secretion was determined by enzyme-linked immunosorbent assay (ELISA), and IP-10 mRNA expression was evaluated by Northern blotting. RESULTS: Interleukin (IL)-10 mRNA was not detected in unstimulated SEMFs. Interferon (IFN)-gamma strongly induced IP-10 mRNA expression. Tumor necrosis factor (TNF)-alpha also stimulated IP-10 mRNA expression, but this was much weaker than that induced by IFN-gamma. The effects of IFN-gamma and TNF-alpha were detected in a dose- and time-dependent manner. These responses were also observed at the protein levels. The IFN-gamma-induced IP-10 secretion was not affected by acetate or propionate, but was significantly reduced by butyrate. Trichostatin A, a specific inhibitor of histone deacetylase, also blocked the IFN-gamma- and TNF-alpha-induced IP-10 mRNA expression, but the effects of trichostatin A were weaker than those of butyrate. The inhibitory effect of butyrate on IFN-gamma-induced IP-10 release was not associated with STAT (signaling transducer and activator of transcription)-1alpha activation. CONCLUSIONS: We demonstrated that human colonic SEMFs are the local site for the secretion IP-10. The regulation of IP-10 release by IFN-gamma and butyrate may play an important role in controlling chronic mucosal inflammation in pathological entities such as IBD.

Ingrowth of aorta wall into stent grafts impregnated with basic fibroblast growth factor: a porcine in vivo study of blood vessel prosthesis healing.

OBJECTIVE: Endovascular aneurysm repair is an alternative treatment of abdominal aortic aneurysm. The procedure is less invasive, and morbidity and most probably mortality are reduced. However, some problems, such as endoleakage, are yet to be resolved. Endoleakage can occur after graft migration, as a result of insufficient fixation of the stent graft. One cause is deficient healing between the aortic neck and the stent graft. We hypothesize that better healing, achieved by induction of vascular cell ingrowth into the graft material, results in better graft fixation. Previously we demonstrated ingrowth of neointima into the graft material if the stent graft is impregnated with a coat of basic fibroblast growth factor (bFGF), heparin, and collagen. In this study we evaluated healing with bFGF-heparin-collagen-coated stent grafts in vivo. METHODS: In 4 pigs, 32 endovascular stent grafts, manufactured from standard Dacron and Gianturco Z-stents, were placed in the aorta. The stent grafts were impregnated with either bFGF-heparin containing collagen (n=16) or control collagen (n=16). After 4 and 8 weeks animals were killed, and ingrowth and healing of the stent grafts were macroscopically and electron microscopically evaluated. RESULTS: After 8 weeks all bFGF-impregnated stent grafts demonstrated ingrowth of tissue and healing between the graft and the aorta, whereas the control nonimpregnated stent grafts showed no ingrowth. Microscopic evaluation demonstrated alpha-smooth muscle actin-positive cells, most probably smooth muscle cells or myofibroblasts, growing from the vascular wall through the graft material. CONCLUSION: A Dacron prosthesis impregnated with collagen, heparin, and bFGF induced graft healing in an in vivo pig model, in contrast to nonimpregnated stent grafts. This in vivo study confirms our previous findings in vitro. These results indicate that healing between Dacron and the aorta can be achieved, and suggest that type I endoleakage may be resolved by inducing healing between the aortic wall and the prosthesis with graft material containing growth factor.

The effect of myofibroblast on contracture of hypertrophic scar.

Wound contraction in humans has both positive and negative effects. It is beneficial to wound healing by narrowing the wound margins, but the formation of undesirable scar contracture brings cosmetic and even functional problems. The entire mechanism of wound healing and scar contracture is not clear yet, but it is at least considered that both the fibroblasts and the myofibroblasts are responsible for contraction in healing wounds. The myofibroblast is a cell that possesses all the morphologic and biochemical characteristics of both a fibroblast and a smooth muscle cell. Normally, the myofibroblasts appear in the initial wound healing processes and generate contractile forces to pull both edges of an open wound until it disappears by apoptosis. But as an altered regulation of myofibroblast disappearance, they remain in the dermis and continuously contract the scar, eventually causing scar contracture. In this research, to compare and directly evaluate the influence on scar contracture of the myofibroblast versus the fibroblast, dermal tissues were taken from 10 patients who had highly contracted hypertrophic scars. The myofibroblasts were isolated and concentrated from the fibroblasts using the magnetic activating cell-sorting column to obtain the myofibroblast group, which contained about 28 to 41 percent of the myofibroblasts, and the fibroblast group, which contained less than 0.9 percent of the myofibroblasts. Each group was cultured in the fibroblast-populated collagen lattice for 13 days, and the contraction of the collagen gel was measured every other day. In addition, they were selectively treated with tranilast [N-(3',4'-dimethoxycinnamoyl) anthranilic acid] to evaluate the influence on the contraction of the collagen gel lattice. During the culture, the myofibroblast group, compared with the fibroblast group, showed statistically significant contraction of the collagen gel lattice day by day, except on the first day, and only the myofibroblast group was affected by tranilast treatment, showing significant inhibition of gel contraction. By utilizing an in vitro model, the authors have demonstrated that myofibroblasts play a more important role in the contracture of the hypertrophic scar.