Expression of thrombospondin-2 as a marker in proliferative diabetic retinopathy

PURPOSE

To determine the expression of the endogenous anti-angiogenic and pro-fibrotic matricellular protein thrombospondin (TSP)-2 and its receptors CD36 and CD47 in proliferative diabetic retinopathy (PDR). In addition, we examined the expression of TSP-2 in the retinas of diabetic rats.

METHODS

Epiretinal membranes from 14 patients with PDR and nine patients with proliferative vitreoretinopathy were studied by immunohistochemistry. Vitreous samples from 30 PDR and 25 nondiabetic patients were studied by enzyme-linked immunosorbent assay. Vitreous samples and retinas of rats were examined by Western blotting.

RESULTS

In epiretinal membranes, vascular endothelial cells and myofibroblasts expressed TSP-2, CD36 and CD47. In PDR membranes, significant correlations were observed between numbers of blood vessels expressing the panendothelial cell marker CD34 and numbers of blood vessels and stromal cells expressing TSP-2, CD36 and CD47. The numbers of blood vessels and stromal cells expressing CD34, TSP-2, CD36 and CD47 were significantly higher in membranes with active neovascularization when compared with those with quiescent disease. Thrombospondin-2 levels in vitreous samples from PDR patients were significantly higher than those in control patients without diabetes (p < 0.001). Western blot analysis revealed a significant increase in the expression of intact and cleaved TSP-2 in vitreous samples from PDR patients and in the retinas of diabetic rats compared to nondiabetic controls.

CONCLUSIONS

Upregulation of TSP-2 may be a protective mechanism against inflammation and angiogenesis associated with PDR.

[Inhibitory effects of doxycycline on argyrophilic nucleolar organizing regions and a-smooth muscle actin expression in proliferative bovine corneal myofibroblasts in vitro]

OBJECTIVE

To investigate the effect of doxycycline on the nucleolar organizing regions and a-smooth muscle actin expression in bovine corneal myofibroblasts in vitro and assess its contribution to ocular surface repair mechanisms.

METHODS

Cell culture and identification: bovine corneal fibroblasts were cultured after the stroma was incubated in 1.0 and 2.0 g/L type I collagenase in two stages.Isolated cells were plated at mantaryay culture flask in 10% of BSA RPMI-1640. Vimentin and alpha-smooth muscle actin (α-SMA) organization were evaluated by immunocytochemistry. The cells staining positive for Vimentin and α-SMA indicated the presence of corneal myofibroblasts. Bovine corneal myofibroblasts were treated with different concentrations of doxycycline (10, 20, 40, 60, 80 mg/L) , a bland control group and the dexamethasone group (120 mg/L) were set up, each group had 30 cases. The argyrophilic nucleolar organizing regions (AgNOR) staining and the immunohistochemistry for α-SMA were performed when the cells were treated for 24 hours and 48 hours. The AgNOR count (Ag-c), AgNOR area (Ag-a) and the expression of α-SMA in the bovine corneal myofibroblasts among each experiment group and control group were compared using one-way ANOVA, further pairwise comparisons using Independent-Samples t test.

RESULTS

Cell culture techniques were successfully used to establish a method for the isolation and culture of bovine corneal myofibroblasts. Microscopic examination and immunohistochemical staining confirmed that the cells cultured were bovine corneal myofibroblasts. The Ag-c and Ag-a of bovine corneal myofibroblasts progressively decreased as the concentrations of doxycycline was increase. 24 h:bland control group Ag-c was 6.40 ± 0.6, 60 mg/L doxycycline group Ag-c was 2.23 ± 0.43;bland control group Ag-a was (34.80 ± 2.36) µm(2), 60 mg/L doxycycline hormone group Ag-a was (19.91 ± 2.15) µm(2). 48 h: bland control group Ag-c was 7.27 ± 0.6,60 mg/L doxycycline hormone group Ag-c was 2.80 ± 0.76, bland control group Ag-a was (36.27 ± 1.99) µm(2), 60 mg/L doxycycline group Ag-a was (13.75 ± 2.09) µm(2). The differences were statistically significant: in the same time intervention (FAg-c 24 h = 252.55, FAg-a 24 h = 202.16, P < 0.05, FAg-c 48 h = 169.38, FAg-a 48 h = 853.23, P < 0.05), in the same concentrations intervention (tAg-c = 6.98, tAg-a = 11.62, P < 0.05). And 60 mg/L of doxycycline had an obviously inhibitory action as 120 mg/L dexamethasone in the same treated hours (dexamethasone group Ag-a 24 h = 30.56 ± 3.66, dexamethasone group Ag-a 48 h = 28.35 ± 1.23 ),the differences were not statistically significant (tAg-a 24h = 1.182, P = 0.242,tAg-a 48 h = 0.21, P = 0.832). As the concentrations investigated, doxycycline can inhibit the expression of α-SMA in the bovine corneal myofibroblasts (189.90 ± 7.48, 140.20 ± 7.79, 113.20 ± 8.98, 98.00 ± 3.50, 85.50 ± 4.99), the difference was statistically significant (F = 761.79, P = 0.00). While dexamethasone had no significant role in the expression of α-SMA (bland control group was 225.10 ± 6.74, the dexamethasone group was 228.50 ± 7.12), and the statistically difference was not obvious (t = 1.096, P = 0.287).

CONCLUSIONS

As the concentrations of doxycycline was increased from 10 mg/L to 80 mg/L, the AgNOR count and AgNOR area of bovine corneal myofibroblasts can be significantly reduced in vitro. Compared with dexamethasone, doxycycline significantly suppressed the expression of α-SMA in bovine corneal myofibroblasts in a dose-dependent positive trend.

Imbalance of desmoplastic stromal cell numbers drives aggressive cancer processes

Epithelial tissues have sparse stroma, in contrast to their corresponding tumours. The effect of cancer cells on stromal cells is well recognized. Increasingly, stromal components, such as endothelial and immune cells, are considered indispensable for cancer progression. The role of desmoplastic stroma, in contrast, is poorly understood. Targeting such cellular components within the tumour is attractive. Recent evidence strongly points towards a dynamic stromal cell participation in cancer progression that impacts patient prognosis. The role of specific desmoplastic stromal cells, such as stellate cells and myofibroblasts in pancreatic, oesophageal and skin cancers, was studied in bio-engineered, physiomimetic organotypic cultures and by regression analysis. For pancreatic cancer, the maximal effect on increasing cancer cell proliferation and invasion, as well as decreasing cancer cell apoptosis, occurs when stromal (pancreatic stellate cells) cells constitute the majority of the cellular population (maximal effect at a stromal cell proportion of 0.66-0.83), accompanied by change in expression of key molecules such as E-cadherin and β-catenin. Gene-expression microarrays, across three tumour types, indicate that stromal cells consistently and significantly alter global cancer cell functions such as cell cycle, cell-cell signalling, cell movement, cell death and inflammatory response. However, these changes are mediated through cancer type-specific alteration of expression, with very few common targets across tumour types. As highlighted by these in vitro data, the reciprocal relationship of E-cadherin and polymeric immunoglobulin receptor (PIGR) expression in cancer cells could be shown, in vivo, to be dependent on the stromal content of human pancreatic cancer. These studies demonstrate that context-specific cancer-stroma crosstalk requires to be precisely defined for effective therapeutic targeting. These data may be relevant to non-malignant processes where epithelial cells interact with stromal cells, such as chronic inflammatory and fibrotic conditions.

Telmisartan plus propranolol improves liver fibrosis and bile duct proliferation in the PSC-like Abcb4-/- mouse model

BACKGROUND

Primary sclerosing cholangitis (PSC) is a chronic cholestatic liver disease leading to cirrhosis and cholangiocellular carcinoma. Inhibitors of the renin-angiotensin system or the sympathetic nervous system delay liver fibrogenesis in animal models.

AIMS

We investigated the antifibrotic potential of telmisartan, an angiotensin II type 1 receptor antagonist, and the β-adrenoceptor blocker propranolol in the PSC-like Abcb4 knockout mouse model.

METHODS

Sixty-five Abcb4 (-/-) mice were treated with telmisartan for 3 or 5 months (T) and with telmisartan plus propranolol for 3, 5, or 8 months (TP), or for 2 or 5 months starting with a delay of 3 months (TP delayed). Liver hydroxyproline content, inflammation, fibrosis, and bile duct proliferation were assessed; fibrosis-related molecules were analyzed by real-time polymerase chain reaction and Western blotting.

RESULTS

Compared to controls, telmisartan monotherapy had no significant influence on hydroxyproline; however, telmisartan plus propranolol reduced hydroxyproline (TP 3 months, p = 0.008), fibrosis score (TP 3 months and TP 8 months, p = 0.043 and p = 0.008, respectively; TP delayed 8 months, p < 0.0005), bile duct proliferation (TP 8 months and TP delayed 8 months, p = 0.006 and p < 0.0005, respectively), and procollagen α1(I), endothelin-1, TIMP-1 and MMP3 mRNA as well as α-SMA, CK-19, and TIMP-1 protein.

CONCLUSIONS

Telmisartan plus propranolol reduces liver fibrosis and bile duct proliferation in the PSC-like Abcb4 (-/-) mouse model, even when started at late stages of fibrosis, and may thus represent a novel therapeutic option for cholestatic liver diseases such as PSC.

[Conivaptan inhibites cell proliferation and collagen production of cardiac fibroblasts induced by arginine vasopressin]

OBJECTIVE

To investigate the effects of arginine vasopressin (AVP) and its receptor antagonist conivaptan (CON) on the proliferation of cardiac fibroblasts (CFs) and the production of collagen I and III.

METHODS

CFs were isolated by collagenase II method and purified with differential attachment and detachment methods. The cell viability of CFs after AVP and/or CON administration was assessed by cell counting kit-8 (CCK-8). The expressions of COL1A1 and COL3A1 mRNA were detected by RT-PCR, and the protein levels of (collagen type 1, alpha 1, COL1A1) and COL3A1 were assessed by Western blotting.

RESULTS

At 24 h after intervention, 10(-7); mol/L AVP promoted the proliferation of CFs in comparison with that in control group (P<0.01), and 10(-7); mol/L CON inhibited the effect significantly (P<0.01). At 12 h after intervention, 10(-7); mol/L AVP significantly enhanced the expressions of COL1A1 and COL3A1 at both mRNA and protein levels, and 10(-7); mol/L CON inhibited the effect again.

CONCLUSION

AVP promoted the proliferation of CFs and enhanced the COL1A1 and COL3A1 expressions at both mRNA and protein levels, while CON could restrain the AVP effects partially.

Proinflammatory cytokines induce crosstalk between colonic epithelial cells and subepithelial myofibroblasts: implication in intestinal fibrosis

BACKGROUND AND AIMS

Colonic epithelial cells and adjacent subepithelial myofibroblasts are important counterparts in the pathogenesis of intestinal inflammation and fibrosis. We investigated the possible crosstalk between them, whilst focusing on the mucosal inflammation pathways that potentially trigger intestinal fibrosis.

METHODS

We studied the effects of proinflammatory cytokines (IL-1α, TNF-α, IFN-γ) on human colonic epithelial cell lines and the effects of epithelial cell-conditioned media on primary human colonic subepithelial myofibroblasts isolated from normal controls or patients with inflammatory Crohn's disease along with the corresponding 18CO cell line. Readouts included production of TGF-β and TIMP-1, total collagen synthesis, matrix metalloproteinases MMP-2 and MMP-9 and myofibroblast migration/mobility.

RESULTS

Proinflammatory cytokines upregulated TGF-β and TIMP-1 in colonic epithelial cells. Conditioned medium from these epithelial cell cultures induced production of MMP-9 and collagen and inhibited the migration/mobility of subepithelial myofibroblasts. MMP-9 production depended on endothelin receptor A signalling on responding myofibroblasts. Collagen up-regulation was independent of TGF-β, CTGF, TF and endothelin. Subepithelial myofibroblasts isolated from Crohn's disease patients had similar responses to those isolated from normal controls, with the exception of higher basal collagen production.

CONCLUSIONS

Our study indicates that colonic epithelial cells may respond to an inflammatory milieu by inducing myofibroblast functions similar to those observed during intestinal fibrosis.

Macrophage depletion impairs corneal wound healing after autologous transplantation in mice

Purpose

Macrophages have been shown to play a critical role in the wound healing process. In the present study, the role of macrophages in wound healing after autologous corneal transplantation was investigated by depleting local infiltrated macrophages.

Methods

Autologous corneal transplantation model was used to induce wound repair in Balb/c mice. Macrophages were depleted by sub-conjunctival injections of clodronate-containing liposomes (Cl₂MDP-LIP). The presence of CD11b⁺ F4/80⁺ macrophages, α-smooth muscle actin⁺ (α-SMA⁺) myofibroblasts, CD31⁺ vascular endothelial cells and NG₂⁺ pericytes was examined by immunohistochemical and corneal whole-mount staining 14 days after penetrating keratoplasty. Peritoneal macrophages were isolated from Balb/c mice and transfused into conjunctiva to examine the recovery role of macrophages depletion on wound healing after autologous corneal transplantation.

Results

Sub-conjunctival Cl₂MDP-LIP injection significantly depleted the corneal resident phagocytes and infiltrated macrophages into corneal stroma. Compared with the mice injected with PBS-liposome, the Cl₂MDP-LIP-injected mice showed few inflammatory cells, irregularly distributed extracellular matrix, ingrowth of corneal epithelium into stroma, and even the detachment of donor cornea from recipient. Moreover, the number of macrophages, myofibroblasts, endothelial cells and pericytes was also decreased in the junction area between the donor and recipient cornea in macrophage-depleted mice. Peritoneal macrophages transfusion recovered the defect of corneal wound healing caused by macrophages depletion.

Conclusions

Macrophage depletion significantly impairs wound healing after autologous corneal transplantation through at least partially impacting on angiogenesis and wound closure.

[Progress in myofibroblast and its application in forensic medicine]

The myofibroblasts have dual characteristics of smooth muscle cells and fibroblasts. In repairing tissular wound, myofibroblasts are involved in fibrogenesis and remodeling the extracellular matrix of the fibrotic cascades reaction. The review describes the morphological characteristics and biological behaviors of myofibroblasts and the application of skin wound age determination, which may provide reference for research in forensic medicine.

Interaction between lung cancer cell and myofibroblast influenced by cyclic tensile strain

Using a cell culture chip with a deformable substrate driven by a hydraulic force, we investigated the motility of cancer cells affected by myofibroblasts undergoing cyclic tensile strain (CTS). CTS reduced both the expression of α-smooth muscle actin in the myofibroblast and the ability of the myofibroblast to accelerate cancer cell migration. However, with the treatment of a pro-inflammatory factor interleukin-1β on the myofibroblasts, the effects of CTS on the myofibroblast were diminished. This result suggests an antagonism between mechanical and chemical stimulations on mediating cancer metastasis by the stromal myofibroblast.

Intestinal myofibroblasts produce nitric oxide in response to combinatorial cytokine stimulation

Inflammatory bowel disease (IBD) patients display elevated levels of intraluminal nitric oxide (NO). NO can react with other molecules to form toxic compounds, which has led to the idea that NO may be an important mediator of IBD. However, the cellular source of NO and how its production is regulated in the intestine are unclear. In this study we aimed to determine if intestinal myofibroblasts produce NO in response to the IBD-associated cytokines IL-1β, TNFα, and IFNγ. Intestinal myofibroblasts were isolated from mice and found to express inducible nitric oxide synthase (iNOS) mRNA, but not endothelial NOS or neuronal NOS. Individual treatment of myofibroblasts with IL-1β, TNFα, or IFNγ had no effect on NO production, but stimulation with combinations of these cytokines synergistically increased iNOS mRNA and protein expression. Treatment with TNFα or IFNγ increased cell surface expression of IFNγRI or TNFRII, respectively, suggesting that these cytokines act in concert to prime NO production by myofibroblasts. Impairment of NF-κB activity with a small molecule inhibitor was sufficient to prevent increased expression of IFNγRI or TNFRII, and inhibition of Akt, JAK/STAT, or NF-κB blocked nearly all NO production induced by combinatorial cytokine treatment. These data indicate that intestinal myofibroblasts require stimulation by multiple cytokines to produce NO and that these cytokines act through a novel pathway involving reciprocal cytokine receptor regulation and signaling by Akt, JAK/STAT, and NF-κB.

Lubricin and smooth muscle α-actin-containing myofibroblasts in the pseudomembranes around loose hip and knee prostheses

The objective was to evaluate the presence and distribution of the lubricating and anti-adhesion glycoprotein lubricin and cells containing the contractile isoform smooth muscle α-actin (SMA) in pseudomembranes around loose hip prostheses. Periprosthetic tissue was obtained at revision arthroplasty of eight aseptic, loose hip implants, and for comparison three loose knee prostheses. Immunohistochemical analysis was performed in 3 zones: zone 1, within 300μm of the edge of the implant-tissue interface; zone 2, between zones 1 and 3; zone 3, within 300μm of the resected/trimmed edge. The presence of lubricin was extensive in all samples: (1) as a discrete layer at the implant-tissue interface; (2) within the extracellular matrix (ECM); (3) intracellularly. There was significantly more high grade (>50%) lubricin surface staining at the implant-tissue interface compared with the resected edge. While there was also a significant effect of location of high grade ECM lubricin staining, there was no significant effect of implant type (i.e. hip versus knee). All but two hip pseudomembrane samples showed the presence of many SMA-containing cells. There was a significant effect of location on the number of SMA-expressing cells, but not of implant type. These findings might explain why the management of loose prosthesis is so challenging.

IQGAP1 suppresses TβRII-mediated myofibroblastic activation and metastatic growth in liver

In the tumor microenvironment, TGF-β induces transdifferentiation of quiescent pericytes and related stromal cells into myofibroblasts that promote tumor growth and metastasis. The mechanisms governing myofibroblastic activation remain poorly understood, and its role in the tumor microenvironment has not been explored. Here, we demonstrate that IQ motif containing GTPase activating protein 1 (IQGAP1) binds to TGF-β receptor II (TβRII) and suppresses TβRII-mediated signaling in pericytes to prevent myofibroblastic differentiation in the tumor microenvironment. We found that TGF-β1 recruited IQGAP1 to TβRII in hepatic stellate cells (HSCs), the resident liver pericytes. Iqgap1 knockdown inhibited the targeting of the E3 ubiquitin ligase SMAD ubiquitination regulatory factor 1 (SMURF1) to the plasma membrane and TβRII ubiquitination and degradation. Thus, Iqgap1 knockdown stabilized TβRII and potentiated TGF-β1 transdifferentiation of pericytes into myofibroblasts in vitro. Iqgap1 deficiency in HSCs promoted myofibroblast activation, tumor implantation, and metastatic growth in mice via upregulation of paracrine signaling molecules. Additionally, we found that IQGAP1 expression was downregulated in myofibroblasts associated with human colorectal liver metastases. Taken together, our studies demonstrate that IQGAP1 in the tumor microenvironment suppresses TβRII and TGF-β dependent myofibroblastic differentiation to constrain tumor growth.

Matrix metalloproteinase-28 deletion exacerbates cardiac dysfunction and rupture after myocardial infarction in mice by inhibiting M2 macrophage activation

RATIONALE

Matrix metalloproteinase (MMP)-28 regulates the inflammatory and extracellular matrix responses in cardiac aging, but the roles of MMP-28 after myocardial infarction (MI) have not been explored.

OBJECTIVE

To determine the impact of MMP-28 deletion on post-MI remodeling of the left ventricle (LV).

METHODS AND RESULTS

Adult C57BL/6J wild-type (n=76) and MMP null (MMP-28((-/-)), n=86) mice of both sexes were subjected to permanent coronary artery ligation to create MI. MMP-28 expression decreased post-MI, and its cell source shifted from myocytes to macrophages. MMP-28 deletion increased day 7 mortality because of increased cardiac rupture post-MI. MMP-28(-/-) mice exhibited larger LV volumes, worse LV dysfunction, a worse LV remodeling index, and increased lung edema. Plasma MMP-9 levels were unchanged in the MMP-28((-/-)) mice but increased in wild-type mice at day 7 post-MI. The mRNA levels of inflammatory and extracellular matrix proteins were attenuated in the infarct regions of MMP-28(-/-) mice, indicating reduced inflammatory and extracellular matrix responses. M2 macrophage activation was impaired when MMP-28 was absent. MMP-28 deletion also led to decreased collagen deposition and fewer myofibroblasts. Collagen cross-linking was impaired as a result of decreased expression and activation of lysyl oxidase in the infarcts of MMP-28(-/-) mice. The LV tensile strength at day 3 post-MI, however, was similar between the 2 genotypes.

CONCLUSIONS

MMP-28 deletion aggravated MI-induced LV dysfunction and rupture as a result of defective inflammatory response and scar formation by suppressing M2 macrophage activation.

Genetically engineered excitable cardiac myofibroblasts coupled to cardiomyocytes rescue normal propagation and reduce arrhythmia complexity in heterocellular monolayers

Rationale and Objective

The use of genetic engineering of unexcitable cells to enable expression of gap junctions and inward rectifier potassium channels has suggested that cell therapies aimed at establishing electrical coupling of unexcitable donor cells to host cardiomyocytes may be arrhythmogenic. Whether similar considerations apply when the donor cells are electrically excitable has not been investigated. Here we tested the hypothesis that adenoviral transfer of genes coding Kir2.1 (I_K1), Na_V1.5 (I_Na) and connexin-43 (Cx43) proteins into neonatal rat ventricular myofibroblasts (NRVF) will convert them into fully excitable cells, rescue rapid conduction velocity (CV) and reduce the incidence of complex reentry arrhythmias in an in vitro model.

Methods and Results

We used adenoviral (Ad-) constructs encoding Kir2.1, Na_V1.5 and Cx43 in NRVF. In single NRVF, Ad-Kir2.1 or Ad-Na_V1.5 infection enabled us to regulate the densities of I_K1 and I_Na, respectively. At varying MOI ratios of 10/10, 5/10 and 5/20, NRVF co-infected with Ad-Kir2.1+ Na_V1.5 were hyperpolarized and generated action potentials (APs) with upstroke velocities >100 V/s. However, when forming monolayers only the addition of Ad-Cx43 made the excitable NRVF capable of conducting electrical impulses (CV = 20.71±0.79 cm/s). When genetically engineered excitable NRVF overexpressing Kir2.1, Na_V1.5 and Cx43 were used to replace normal NRVF in heterocellular monolayers that included neonatal rat ventricular myocytes (NRVM), CV was significantly increased (27.59±0.76 cm/s vs. 21.18±0.65 cm/s, p<0.05), reaching values similar to those of pure myocytes monolayers (27.27±0.72 cm/s). Moreover, during reentry, propagation was faster and more organized, with a significantly lower number of wavebreaks in heterocellular monolayers formed by excitable compared with unexcitable NRVF.

Conclusion

Viral transfer of genes coding Kir2.1, Na_V1.5 and Cx43 to cardiac myofibroblasts endows them with the ability to generate and propagate APs. The results provide proof of concept that cell therapies with excitable donor cells increase safety and reduce arrhythmogenic potential.

TGF-β1, released by myofibroblasts, differentially regulates transcription and function of sodium and potassium channels in adult rat ventricular myocytes

Cardiac injury promotes fibroblasts activation and differentiation into myofibroblasts, which are hypersecretory of multiple cytokines. It is unknown whether any of such cytokines are involved in the electrophysiological remodeling of adult cardiomyocytes. We cultured adult cardiomyocytes for 3 days in cardiac fibroblast conditioned medium (FCM) from adult rats. In whole-cell voltage-clamp experiments, FCM-treated myocytes had 41% more peak inward sodium current (I_Na) density at −40 mV than myocytes in control medium (p<0.01). In contrast, peak transient outward current (I_to) was decreased by ∼55% at 60 mV (p<0.001). Protein analysis of FCM demonstrated that the concentration of TGF-β1 was >3 fold greater in FCM than control, which suggested that FCM effects could be mediated by TGF-β1. This was confirmed by pre-treatment with TGF-β1 neutralizing antibody, which abolished the FCM-induced changes in both I_Na and I_to. In current-clamp experiments TGF-β1 (10 ng/ml) prolonged the action potential duration at 30, 50, and 90 repolarization (p<0.05); at 50 ng/ml it gave rise to early afterdepolarizations. In voltage-clamp experiments, TGF-β1 increased I_Na density in a dose-dependent manner without affecting voltage dependence of activation or inactivation. I_Na density was −36.25±2.8 pA/pF in control, −59.17±6.2 pA/pF at 0.1 ng/ml (p<0.01), and −58.22±6.6 pA/pF at 1 ng/ml (p<0.01). In sharp contrast, I_to density decreased from 22.2±1.2 pA/pF to 12.7±0.98 pA/pF (p<0.001) at 10 ng/ml. At 1 ng/ml TGF-β1 significantly increased SCN5A (Na_V1.5) (+73%; p<0.01), while reducing KCNIP2 (Kchip2; −77%; p<0.01) and KCND2 (K_V4.2; −50% p<0.05) mRNA levels. Further, the TGF-β1-induced increase in I_Na was mediated through activation of the PI3K-AKT pathway via phosphorylation of FOXO1 (a negative regulator of SCN5A). TGF-β1 released by myofibroblasts differentially regulates transcription and function of the main cardiac sodium channel and of the channel responsible for the transient outward current. The results provide new mechanistic insight into the electrical remodeling associated with myocardial injury.

Role of tumor necrosis factor-α in the pathogenesis of atrial fibrosis and development of an arrhythmogenic substrate

BACKGROUND

Although tumor necrosis factor-α (TNF-α) levels are increased in patients with atrial fibrillation (AF), its role in the pathogenesis of AF is unclear. We investigated whether direct delivery of TNF-α could induce atrial fibrosis.

METHODS AND RESULTS

TNF-α (4 μg/kg) was injected into the tail vein of 20 male Swiss albino mice (TNF group) and saline into 20 control mice (CON group). The dose was carefully chosen to avoid any significant decrease in left ventricular (LV) function. Animals were killed after 16 weeks and their atria examined for fibrosis. We found increased atrial fibrosis in the TNF group compared with the CON group [372.8±21.5 arbitrary units (a.u.) vs. 56.9±6.5 a.u., respectively, mean±SEM; P<0.0001] and decreased connexin-40 immunofluorescence [7.5±0.4 a.u vs. 40.4±1.9 a.u, respectively; P<0.0001]. Transforming growth factor-β [TGF-β: 95.6±1.8 a.u vs. 29.4±5.8 a.u; P<0.001], α-smooth muscle actin (α-SMA: 97.9±13.0 a.u vs. 50.1±18.5 a.u; P<0.05] and matrix metalloproteinase 2 (MMP-2)/GAPDH levels [157.3±26.4 a.u vs. 105.8±13.3 a.u; P<0.05] were also increased in the TNF group.

CONCLUSIONS

TNF-α is involved in the pathogenesis of atrial fibrosis and altered connexin-40 expression in mice through the TGF-β signaling pathway, activation of myofibroblasts and increased secretion of MMPs. Collectively, these changes may contribute to the arrhythmogenic substrate and development of AF. 

Molecular alterations in fibroblasts exposed to Helicobacter pylori: a missing link in bacterial inflammation progressing into gastric carcinogenesis?

Major human pathogen Helicobacter pylori (Hp) can colonize the gastric mucosa causing inflammation and being of potential risk for gastric cancer development but the contribution of fibroblasts to the pathogenesis of Hp in the stomach has been little studied. Normal stroma contains few fibroblasts, especially myofibroblasts, but their number rapidly increases in the reactive stroma surrounding inflammatory region and neoplastic tissue. We determined the effect of coincubation of cultured rat gastric fibroblasts with alive Hp on the transdifferentiation of fibroblasts into myofibroblasts associated with Hp-induced inflammation and neoplasia. Gastric mucosal samples were harvested from 8-week-old Spraque-Dowley rats and cultured to obtain the sub-confluent fibroblasts. The isolated fibroblasts were infected with 1 x 10(9) of live Hp (ATCC 700824, cagA+, vacA+) per dish and incubated in humidified atmosphere for 3, 24 and 48 hours. At respective times, fibroblasts were harvested and the expression of mRNA for α-smooth muscle actin (SMA), hypoxia inducible factor (HIF)-1α, collagen I, heat shock protein (HSP)-70, heme oxygenase (HO)-1, Bax and Ki67 transcripts was determined by RT-PCR with specific primers. Hp increased the transdifferentiation of fibroblasts into myofibroblasts as reflected by the time-dependent overexpression of mRNA for α-SMA. The increased expression of HIF-1α and collagen I was observed in fibroblasts co-cultured with Hp. The expression of HSP70 which was negligible in isolated fibroblasts incubated with vehicle (saline) showed time-dependent 2-3 fold increase in those incubated with Hp. The HO-1 mRNA was strongly expressed in rat gastric fibroblasts without or with the co-incubation with Hp. The mRNA for Bax was progressively downregulated within the time of incubation while no significant changes in expression of proliferation marker Ki67 were recorded. We conclude that Hp-induced transdifferentiation of fibroblasts into myofibroblasts involves an increased expression of the early carcinogenic marker HIF-1α, and inhibition of proapoptotic Bax expression, and 2) the overexpression of HSP70 and the unchanged expression HO-1 and Ki67 probably represent the enhanced protective activity of Hp-infected fibroblasts to maintain their own integrity under inflammatory action of this bacteria and its cytotoxins.

Long pentraxin PTX3 exacerbates pressure overload-induced left ventricular dysfunction

Background

Left ventricular hypertrophy is enhanced by an inflammatory state and stimulation of various cytokines. Pentraxin 3 (PTX3) is rapidly produced in response to inflammatory signals, and high plasma PTX3 levels are seen in patients with heart failure. This study aimed to examine the influence of PTX3 on cardiac hypertrophy and left ventricular dysfunction with respect to pressure overload.

Methods and Results

PTX3 systemic knockout (PTX3-KO) mice, transgenic mice with cardiac-specific overexpression of PTX3 (PTX3-TG), and the respective wild-type (WT) littermate mice were subjected to transverse aortic constriction (TAC) or a sham operation. Cardiac PTX3 expression increased after TAC in WT mice. In vitro, hydrogen peroxide induced the expression of PTX3 in both cardiac myocytes and cardiac fibroblasts. Recombinant PTX3 phosphorylated extracellular signal–regulated kinase 1/2 (ERK1/2) in cardiac fibroblasts. Phosphorylation of cardiac ERK1/2 and nuclear factor kappa-B after TAC was attenuated in the PTX3-KO mice but was enhanced in the PTX3-TG mice compared with WT mice. Interleukin-6 and connective tissue growth factor production was lower in the PTX3-KO mice than in the WT mice, but this was augmented in the PTX3-TG mice than in the WT mice. Echocardiography revealed that adverse remodeling with left ventricular dysfunction, as well as with increased interstitial fibrosis, was enhanced in PTX3-TG mice, while these responses were suppressed in PTX3-KO mice.

Conclusion

The local inflammatory mediator PTX3 directly modulates the hypertrophic response and ventricular dysfunction following an increased afterload.

The renal (myo-)fibroblast: a heterogeneous group of cells

Several studies have demonstrated that mesenchymal stem cells have the capacity to reverse acute and chronic kidney injury in different experimental models by paracrine mechanisms. This paracrine action may be accounted for, at least in part, by microvesicles (MVs) released from mesenchymal stem cells, resulting in a horizontal transfer of mRNA, microRNA and proteins. MVs, released as exosomes from the endosomal compartment, or as shedding vesicles from the cell surface, are now recognized as being an integral component of the intercellular microenvironment. By acting as vehicles for information transfer, MVs play a pivotal role in cell-to-cell communication. This exchange of information between the injured cells and stem cells has the potential to be bi-directional. Thus, MVs may either transfer transcripts from injured cells to stem cells, resulting in reprogramming of their phenotype to acquire specific features of the tissue, or conversely, transcripts could be transferred from stem cells to injured cells, restraining tissue injury and inducing cell cycle re-entry of resident cells, leading to tissue self-repair. Upon administration with a therapeutic regimen, MVs mimic the effect of mesenchymal stem cells in various experimental models by inhibiting apoptosis and stimulating cell proliferation. In this review, we discuss whether MVs released from mesenchymal stem cells have the potential to be exploited in novel therapeutic approaches in regenerative medicine to repair damaged tissues, as an alternative to stem cell-based therapy.

Smad mediated regulation of inhibitor of DNA binding 2 and its role in phenotypic maintenance of human renal proximal tubule epithelial cells

The basic-Helix-Loop-Helix family (bHLH) of transcriptional factors plays a major role in regulating cellular proliferation, differentiation and phenotype maintenance. The downregulation of one of the members of bHLH family protein, inhibitor of DNA binding 2 (Id2) has been shown to induce de-differentiation of epithelial cells. Opposing regulators of epithelial/mesenchymal phenotype in renal proximal tubule epithelial cells (PTEC), TGFβ1 and BMP7 also have counter-regulatory effects in models of renal fibrosis. We investigated the regulation of Id2 by these growth factors in human PTECs and its implication in the expression of markers of epithelial versus myofibroblastic phenotype. Cellular Id2 levels were reduced by TGFβ1 treatment; this was prevented by co-incubation with BMP7. BMP7 alone increased cellular levels of Id2. TGFβ1 and BMP7 regulated Id2 through Smad2/3 and Smad1/5 dependent mechanisms respectively. TGFβ1 mediated Id2 suppression was essential for α-SMA induction in PTECs. Although Id2 over-expression prevented α-SMA induction, it did not prevent E-cadherin loss under the influence of TGFβ1. This suggests that the loss of gate keeper function of E-cadherin alone may not necessarily result in complete EMT and further transcriptional re-programming is essential to attain mesenchymal phenotype. Although BMP7 abolished TGFβ1 mediated α-SMA expression by restoring Id2 levels, the loss of Id2 was not sufficient to induce α-SMA expression even in the context of reduced E-cadherin expression. Hence, a reduction in Id2 is critical for TGFβ1-induced α-SMA expression in this model of human PTECs but is not sufficient in it self to induce α-SMA even in the context of reduced E-cadherin.

PECAM1(+)/Sca1(+)/CD38(+) vascular cells transform into myofibroblast-like cells in skin wound repair

Skin injury induces the formation of new blood vessels by activating the vasculature in order to restore tissue homeostasis. Vascular cells may also differentiate into matrix-secreting contractile myofibroblasts to promote wound closure. Here, we characterize a PECAM1⁺/Sca1⁺ vascular cell population in mouse skin, which is highly enriched in wounds at the peak of neoangiogenesis and myofibroblast formation. These cells express endothelial and perivascular markers and present the receptor CD38 on their surface. PECAM1⁺/Sca1⁺/CD38⁺ cells proliferate upon wounding and could give rise to α-SMA⁺ myofibroblast-like cells. CD38 stimulation in immunodeficient mice reduced the wound size at the peak of neoangiogenesis and myofibroblast formation. In humans a corresponding cell population was identified, which was enriched in sprouting vessels of basal cell carcinoma biopsies. The results indicate that PECAM1⁺/Sca1⁺/CD38⁺ vascular cells could proliferate and differentiate into myofibroblast-like cells in wound repair. Moreover, CD38 signaling modulates PECAM1⁺/Sca1⁺/CD38⁺ cell activation in the healing process implying CD38 as a target for anti-angiogenic therapies in human basal cell carcinoma.

Effect of interleukin 6 deficiency on renal interstitial fibrosis

Our recent studies have shown that bone marrow-derived fibroblast precursors contribute significantly to the pathogenesis of renal fibrosis. However, the molecular mechanisms underlying the recruitment and activation of bone marrow-derived fibroblast precursors are incompletely understood. We found that interleukin 6 was induced in the kidney in a murine model of renal fibrosis induced by unilateral ureteral obstruction. Therefore, we investigated if interleukin 6 play a role in the recruitment and maturation of bone marrow-derived fibroblast precursors in the kidney during the development of renal fibrosis. Wild-type and interleukin 6 knockout mice were subjected to unilateral obstructive injury for up to two weeks. Interleukin 6 knockout mice accumulated similar number of bone marrow-derived fibroblast precursors and myofibroblasts in the kidney in response to obstructive injury compared to wild-type mice. Furthermore, IL-6 knockout mice expressed comparable α-SMA in the obstructed kidney compared to wild-type mice. Moreover, targeted disruption of Interleukin 6 did not affect gene expression of profibrotic chemokine and cytokines in the obstructed kidney. Finally, there were no significant differences in renal interstitial fibrosis or expression of extracellular matrix proteins between wild-type and interleukin 6 knockout mice following obstructive injury. Our results indicate that interleukin 6 does not play a significant role in the recruitment of bone marrow-derived fibroblast precursors and the development of renal fibrosis.

Paracrine Hedgehog signaling drives metabolic changes in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) typically develops in cirrhosis, a condition characterized by Hedgehog (Hh) pathway activation and accumulation of Hh-responsive myofibroblasts. Although Hh signaling generally regulates stromal-epithelial interactions that support epithelial viability, the role of Hh-dependent myofibroblasts in hepatocarcinogenesis is unknown. Here, we used human HCC samples, a mouse HCC model, and hepatoma cell/myofibroblast cocultures to examine the hypothesis that Hh signaling modulates myofibroblasts' metabolism to generate fuels for neighboring malignant hepatocytes. The results identify a novel paracrine mechanism whereby malignant hepatocytes produce Hh ligands to stimulate glycolysis in neighboring myofibroblasts, resulting in release of myofibroblast-derived lactate that the malignant hepatocytes use as an energy source. This discovery reveals new diagnostic and therapeutic targets that might be exploited to improve the outcomes of cirrhotic patients with HCCs.

Stellate cells from rat pancreas are stem cells and can contribute to liver regeneration

The identity of pancreatic stem/progenitor cells is still under discussion. They were suggested to derive from the pancreatic ductal epithelium and/or islets. Here we report that rat pancreatic stellate cells (PSC), which are thought to contribute to pancreatic fibrosis, have stem cell characteristics. PSC reside in islets and between acini and display a gene expression pattern similar to umbilical cord blood stem cells and mesenchymal stem cells. Cytokine treatment of isolated PSC induced the expression of typical hepatocyte markers. The PSC-derived hepatocyte-like cells expressed endodermal proteins such as bile salt export pump along with the mesodermal protein vimentin. The transplantation of culture-activated PSC from enhanced green fluorescent protein-expressing rats into wild type rats after partial hepatectomy in the presence of 2-acetylaminofluorene revealed that PSC were able to reconstitute large areas of the host liver through differentiation into hepatocytes and cholangiocytes. This developmental fate of transplanted PSC was confirmed by fluorescence in situ hybridization of chromosome Y after gender-mismatched transplantation of male PSC into female rats. Transplanted PSC displayed long-lasting survival, whereas muscle fibroblasts were unable to integrate into the host liver. The differentiation potential of PSC was further verified by the transplantation of clonally expanded PSC. PSC clones maintained the expression of stellate cell and stem cell markers and preserved their differentiation potential, which indicated self-renewal potential of PSC. These findings demonstrate that PSC have stem cell characteristics and can contribute to the regeneration of injured organs through differentiation across tissue boundaries.

[Mesenchymal stem cells implantation increases the myofibroblasts congregating in infarct region in a rat model of myocardial infarction]

OBJECTIVE

To investigate the modulation effects of mesenchymal stem cells (MSC) implantation on the myofibroblasts congregating in the infarct region after myocardial infarction (MI).

METHODS

MI was induced in SD rats by left anterior descending coronary artery ligation, and the experimental animals were assigned randomly into the sham group, MI + PBS group and MI + MSC group (myocardial injection of 0.1 ml 2×10(7)/ml in four locations in the infarct region). Echocardiography, hemodynamic examinations and Masson trichrome staining were performed. Implanted MSC differentiation and myofibroblasts congregating in infarct region were investigated by immunofluorescence staining. TGF-β(1)-Smad2 signaling pathway was examined by real-time RT-PCR and Western blot.

RESULTS

(1) Four weeks late, heart-weight/body-weight ratio [(3.04 ± 0.16) mg/g vs. (3.34 ± 0.14) mg/g, P < 0.01] and myocardial infarction size [(38.72 ± 2.38)% vs. (46.36 ± 2.81)%, P < 0.01] were significantly reduced in MI + MSC group than in MI + PBS group, while scar thickness of infarct region was thicker [(0.93 ± 0.17) mm vs. (0.65 ± 0.16) mm, P = 0.01], and LVEF was higher [LVEF: (32.5 ± 5.9)% vs. (26.5 ± 4.5)%, P = 0.03] in MI + MSC group than in MI + PBS group. (2) Myofibroblasts congregating in the infarct region was significantly enhanced in MI + MSC group compared with MI + PBS group [(196 ± 20) cells/mm(2) vs. (89 ± 25) cells/mm(2), P < 0.01], and part of implanted MSC expressed α-SMA(+). (3) TGF-β(1) expression and the phosphorylating of Smad2 in the infarct region were significantly upregulated in MI + MSC group compared with MI + PBS group (all P < 0.05).

CONCLUSIONS

MSC could improve myocardial function and promote myofibroblasts congregating in the infarct region via activating the TGF-β(1)-Smad2 signaling pathway in this model.

CXC-type chemokines promote myofibroblast phenoconversion and prostatic fibrosis

Recent studies from our group suggest that extracellular matrix (ECM) deposition and fibrosis characterize the peri-urethral prostate tissues of some men suffering from Lower Urinary Tract Symptoms (LUTS) and that fibrosis may be a contributing factor to the etiology of LUTS. Fibrosis can generally be regarded as an errant wound-healing process in response to chronic inflammation, and several studies have shown that the aging prostate tissue microenvironment is rich with inflammatory cells and proteins. However, it is unclear whether these same inflammatory proteins, particularly CXC-type chemokines, can mediate myofibroblast phenoconversion and the ECM deposition necessary for the development of prostatic tissue fibrosis. To examine this, immortalized and primary prostate stromal fibroblasts treated with TGF-β1, CXCL5, CXCL8, or CXCL12 were evaluated morphologically by microscopy, by immunofluorescence and qRT-PCR for αSMA, collagen 1, vimentin, calponin, and tenascin protein and transcript expression, and by gel contraction assays for functional myofibroblast phenoconversion. The results of these studies showed that that immortalized and primary prostate stromal fibroblasts are induced to express collagen 1 and 3 and αSMA gene transcripts and proteins and to undergo complete and functional myofibroblast phenoconversion in response to CXC-type chemokines, even in the absence of exogenous TGF-β1. Moreover, CXCL12-mediated myofibroblast phenoconversion can be completely abrogated by inhibition of the CXCL12 receptor, CXCR4. These findings suggest that CXC-type chemokines, which comprise inflammatory proteins known to be highly expressed in the aging prostate, can efficiently and completely mediate myofibroblast phenoconversion and may thereby promote fibrotic changes in prostate tissue architecture associated with the development and progression of male lower urinary tract dysfunction.

Cellular expression profile for interstitial cells of cajal in bladder - a cell often misidentified as myocyte or myofibroblast

BACKGROUND

Interstitial cells of Cajal (ICC) have been identified in urinary bladder of several species, but their presence in mice remains uncertain. Meanwhile, dozens of reports indicate that dysregulation of connexin 43 plays an important role in bladder overactivity, but its localization has not been clearly defined, with reports of expression in either the smooth muscle or in myofibroblasts. We recently identified a population of ectonucleoside triphosphate diphosphohydrolase 2 (NTPDase2) positive cells that resemble ICC and are distinct from smooth muscle, fibroblasts, myofibroblasts and neurons. Thus we sought to define more clearly the molecular signature of ICC and in doing so resolve some of these uncertainties.

PRINCIPLE FINDINGS

Immunofluorescent localization revealed that NTPDase2-positive cells lie closely adjacent to smooth muscle but are separate from them. NTPDase2 positive cells exhibited co-localization with the widely accepted ICC marker - c-kit. They were further shown to co-localize with other ICC markers CD34 and Ano1, but not with mast cell marker tryptase. Significantly, they show convincing co-localization with connexin 43, which was not present in smooth muscle. The identity of these cells as ICC was further confirmed by the presence of three mesenchymal markers - vimentin, desmin, and PDGFβ receptor, which indicates their mesenchymal origin. Finally, we observed for the first time, the presence of merlin/neurofibromin 2 in ICC. Normally considered a neuronal protein, the presence of merlin suggests ICC in bladder may have a role in neurotransmission.

CONCLUSIONS

NTPDase2 positive cells in mice bladder are ICC, which can be defined by the presence of c-Kit, CD34, Ano1, NTPDase2, connexin 43, vimentin, desmin, PDGFβ receptor and merlin/NF2. These data establish a definitive molecular expression profile, which can be used to assist in explorations of their functional roles, and the presence of NTPDase2 suggests that purinergic signaling plays a role in regulation of ICC function.

Platelet-derived growth factor (PDGF)-C neutralization reveals differential roles of PDGF receptors in liver and kidney fibrosis

Platelet-derived growth factors (PDGF) are key mediators of organ fibrosis. We investigated whether PDGF-C(-/-) mice or mice treated with neutralizing PDGF-C antibodies are protected from bile duct ligation-induced liver fibrosis, and we compared the effects with those of PDGF-C deficiency or neutralization on kidney fibrosis induced by unilateral ureteral obstruction. Unexpectedly, and in contrast to kidney fibrosis, PDGF-C deficiency or antagonism did not protect from liver fibrosis or functional liver impairment. Furthermore, the hepatic infiltration of monocytes/macrophages/dendritic cells and chemokine mRNA expression (CC chemokine ligand [CCL]5, CCL2, and CC chemokine receptor 2 [CCR2]) remained unchanged. Transcript expression of PDGF ligands increased in both liver and kidney fibrosis and was not affected by neutralization of PDGF-C. In kidney fibrosis, PDGF-C deficiency or antagonism led to reduced expression and signaling of PDGF-receptor (R)-α- and PDGFR-β-chains. In contrast, in liver fibrosis there was either no difference (PDGF-C(-/-) mice) or even an upregulation of PDGFR-β and signaling (anti-PDGF-C group). Finally, in vitro studies in portal myofibroblasts pointed to a predominant role of PDGF-B and PDGF-D signaling in liver fibrosis. In conclusion, our study revealed significant differences between kidney and liver fibrosis in that PDGF-C mediates kidney fibrosis, whereas antagonism of PDGF-C in liver fibrosis appears to be counteracted by significant upregulation and increased PDGFR-β signaling. PDGF-C antagonism, therefore, may not be effective to treat liver fibrosis.

Effects of 300 mT static magnetic field on IL-6 secretion in normal human colon myofibroblasts

Intestinal subepithelial myofibroblasts play crucial role in the growth and development of the intestine. Colitis, small bowel injury, gastric ulcer disease and inflammatory bowel disease (IBD) accompany the increase of number of activated myofibroblasts. In the last few years, the increasing production of electromagnetic (EMF) and static magnetic fields (SMF), due to the expanding use of electronic devices in everyday life, has led to a number of studies on the effects of these fields on living organisms. EMF therapy, because of its anti-inflammatory properties, may be used in medicine in IBD treatment. This mechanism has not been elucidated yet. In the present work normal human colon myofibroblasts CCD-18Co were exposed to SMF with a flux density of 300 mT. After 24 h incubation TNF-alpha-dependent IL-6 secretion was determined with ELISA kit (RandD Systems).The influence of magnetic field and its effect on cell proliferation were determined with TOX-2 (In Vitro Toxicology Assay Kit XTT Based, TOX-2, Sigma) and CyQUANT NF cell proliferation assay kit (Molecular Probes). It was shown that SMF inhibited TNF-alpha-dependent IL-6 secretion. The observed effects were statistically significant and depended on the time of incubation. Moreover, SMF triggered cell proliferation whereas it did not alter cell viability. IL-6 belongs to pro-inflammatory cytokines family and plays a crucial role in IBD. Inhibition of IL-6 secretion by SMF and lack of its cytotoxic effect seem to be advantageous whilst SMF is implicated in the treatment of inflammatory diseases associated by increase in number of activated myofibroblasts.

Phosphodiesterase type 5 inhibition reverts prostate fibroblast-to-myofibroblast trans-differentiation

Phosphodiesterase type 5 (PDE5) inhibitors have been demonstrated to improve lower urinary tract symptoms secondary to benign prostatic hyperplasia (BPH). Because BPH is primarily driven by fibroblast-to-myofibroblast trans-differentiation, this study aimed to evaluate the potential of the PDE5 inhibitor vardenafil to inhibit and reverse trans-differentiation of primary human prostatic stromal cells (PrSC). Vardenafil, sodium nitroprusside, lentiviral-delivered short hairpin RNA-mediated PDE5 knockdown, sodium orthovanadate, and inhibitors of MAPK kinase, protein kinase G, Ras homolog family member (Rho) A, RhoA/Rho kinase, phosphatidylinositol 3 kinase and protein kinase B (AKT) were applied to PrSC treated with basic fibroblast growth factor (fibroblasts) or TGFβ1 (myofibroblasts) in vitro, in chicken chorioallantoic membrane xenografts in vivo, and to prostatic organoids ex vivo. Fibroblast-to-myofibroblast trans-differentiation was monitored by smooth muscle cell actin and IGF binding protein 3 mRNA and protein levels. Vardenafil significantly attenuated TGFβ1-induced PrSC trans-differentiation in vitro and in chorioallantoic membrane xenografts. Enhancement of nitric oxide/cyclic guanosine monophosphate signaling by vardenafil, sodium nitroprusside, or PDE5 knockdown reduced smooth muscle cell actin and IGF binding protein 3 mRNA and protein levels and restored fibroblast-like morphology in trans-differentiated myofibroblast. This reversal of trans-differentiation was not affected by MAPK kinase, protein kinase G, RhoA, or RhoA/Rho kinase inhibition, but vardenafil attenuated phospho-AKT levels in myofibroblasts. Consistently, phosphatidylinositol 3 kinase or AKT inhibition induced reversal of trans-differentiation, whereas the tyrosine phosphatase inhibitor sodium orthovanadate abrogated the effect of vardenafil. Treatment of prostatic organoids with vardenafil ex vivo reduced expression of myofibroblast markers, indicating reverse remodeling of stroma towards a desired higher fibroblast/myofibroblast ratio. Thus, enhancement of the nitric oxide/cyclic guanosine monophosphate signaling pathway by vardenafil attenuates and reverts fibroblast-to-myofibroblast trans-differentiation, hypothesizing that BPH patients might benefit from long-term therapy with PDE5 inhibitors.

Aquaporin 3 expression is up-regulated by TGF-β1 in rat peritoneal mesothelial cells and plays a role in wound healing

Aquaporin 3 (AQP3) is expressed in many tissues including the peritoneum and kidney. In cultured mesothelial cells, glucose up-regulates AQP3, which may be important for water transport through the peritoneal membrane. However, there has been no research into the role of AQP3 in human peritoneal mesothelial cell (HPMC) migration or peritoneal fibrosis. We investigated the effects of transforming growth factor-β1 (TGF-β1) on AQP3 expression in HPMCs. We also investigated the role of AQP3 in the peritoneal wound healing process in rats. Chronic exposure to glucose-containing solution increased peritoneal myofibroblasts, with TGF-β1 and AQP3 expression in a model of long-term peritoneal dialysis. In vitro, TGF-β1 induced AQP3 expression in HPMCs. AQP3 knockdown by small-interfering RNA inhibited TGF-β1-induced AQP3 and α-smooth muscle actin expression and also slowed HPMC migration. AQP3 overexpression induced faster migration of HPMCs. Treatment with an extracellular signal-regulated kinase inhibitor and p38 kinase inhibitor attenuated TGF-β1-induced AQP3 expression in HPMCs. These data suggest that TGF-β1 induces AQP3 and that AQP3 has a critical role in TGF-β-induced HPMC migration. These findings provide evidence of a novel role for AQP3 in peritoneal fibrosis and wound healing. The effect of TGF-β1 on AQP3 expression in HPMCs is mediated, at least in part, by ERK and p38 signaling.

Encapsulated glucagon-like peptide-1-producing mesenchymal stem cells have a beneficial effect on failing pig hearts

Stem cell therapy is an exciting and emerging treatment option to promote post-myocardial infarction (post-MI) healing; however, cell retention and efficacy in the heart remain problematic. Glucagon-like peptide-1 (GLP-1) is an incretin hormone with cardioprotective properties but a short half-life in vivo. The effects of prolonged GLP-1 delivery from stromal cells post-MI were evaluated in a porcine model. Human mesenchymal stem cells immortalized and engineered to produce a GLP-1 fusion protein were encapsulated in alginate (bead-GLP-1 MSC) and delivered to coronary artery branches. Control groups were cell-free beads and beads containing unmodified MSCs (bead-MSC), n = 4-5 per group. Echocardiography confirmed left ventricular (LV) dysfunction at time of delivery in all groups. Four weeks after intervention, only the bead-GLP-1 MSC group demonstrated LV function improvement toward baseline and showed decreased infarction area compared with controls. Histological analysis showed reduced inflammation and a trend toward reduced apoptosis in the infarct zone. Increased collagen but fewer myofibroblasts were observed in infarcts of the bead-GLP-1 MSC and bead-MSC groups, and significantly more vessels per mm(2) were noted in the infarct of the bead-GLP-1 MSC group. No differences were observed in myocyte cross-sectional area between groups. Post-MI delivery of GLP-1 encapsulated genetically modified MSCs provided a prolonged supply of GLP-1 and paracrine stem cell factors, which improved LV function and reduced epicardial infarct size. This was associated with increased angiogenesis and an altered remodeling response. Combined benefits of paracrine stem cell factors and GLP-1 were superior to those of stem cells alone. These results suggest that encapsulated genetically modified MSCs would be beneficial for recovery following MI.

The origin and arrhythmogenic potential of fibroblasts in cardiac disease

Fibroblasts play a major role in normal cardiac physiology and in the response of the heart to injury and disease. Cardiac electrophysiological research has primarily focused on the mechanisms of remodeling that accompany cardiac disease with an emphasis on myocyte electrophysiology. Recently, there has been increasing interest in the potential role of fibroblasts in cardiac electrophysiology. This review focuses on the arrhythmia mechanisms involving interactions between myocytes and fibroblasts. We also discuss the available evidence supporting the contribution of intracardiac and extracardiac sources to the fibroblast and myofibroblast populations in diseased hearts.

Origin of developmental precursors dictates the pathophysiologic role of cardiac fibroblasts

Fibroblasts in the heart play a critical function in the secretion and modulation of extracellular matrix critical for optimal cellular architecture and mechanical stability required for its mechanical function. Fibroblasts are also intimately involved in both adaptive and nonadaptive responses to cardiac injury. Fibroblasts provide the elaboration of extracellular matrix and, as myofibroblasts, are responsible for cross-linking this matrix to form a mechanically stable scar after myocardial infarction. By contrast, during heart failure, fibroblasts secrete extracellular matrix, which manifests itself as excessive interstitial fibrosis that may mechanically limit cardiac function and distort cardiac architecture (adverse remodeling). This review examines the hypothesis that fibroblasts mediating scar formation and fibroblasts mediating interstitial fibrosis arise from different cellular precursors and in response to different autocoidal signaling cascades. We demonstrate that fibroblasts which generate scars arise from endogenous mesenchymal stem cells, whereas those mediating adverse remodeling are of myeloid origin and represent immunoinflammatory dysregulation.

The extracellular matrix modulates fibroblast phenotype and function in the infarcted myocardium

Cardiac fibroblasts are key cellular effectors of cardiac repair; their phenotype and function are modulated by interactions with extracellular matrix proteins. This review manuscript discusses the effects of the extracellular matrix on the inflammatory and reparative properties of fibroblasts in the infarcted myocardium. Early generation of matrix fragments in the infarct induces a pro-inflammatory and matrix-degrading fibroblast phenotype. Formation of a fibrin/fibronectin-rich provisional matrix serves as a conduit for migration of fibroblasts into the infarcted area. Induction of ED-A fibronectin and nonfibrillar collagens may contribute to myofibroblast transdifferentiation. Upregulation of matricellular proteins promotes transduction of growth factor and cytokine-mediated signals. As the scar matures, matrix cross-linking, clearance of matricellular proteins, and reduced growth factor signaling cause deactivation and apoptosis of reparative infarct fibroblasts. Understanding the effects of matrix components on infarct fibroblasts may guide the design of peptides that reproduce, or inhibit, specific matricellular functions, attenuating adverse remodeling.

Increased fibroblast telomerase expression precedes myofibroblast α-smooth muscle actin expression in idiopathic pulmonary fibrosis

OBJECTIVE

This study sought to identify the relationship between fibroblast telomerase expression, myofibroblasts, and telomerase-mediated regulatory signals in idiopathic pulmonary fibrosis.

METHODS

Thirty-four surgical lung biopsies, which had been obtained from patients with idiopathic pulmonary fibrosis and histologically classified as usual interstitial pneumonia, were examined. Immunohistochemistry was used to evaluate fibroblast telomerase expression, myofibroblast α-smooth muscle actin expression and the tissue expression of inter leu kin-4, transforming growth factor-β, and basic fibroblast growth factor. The point-counting technique was used to quantify the expression of these markers in unaffected, collapsed, mural fibrosis, and honeycombing areas. The results were correlated to patient survival.

RESULTS

Fibroblast telomerase expression and basic fibroblast growth factor tissue expression were higher in collapsed areas, whereas myofibroblast expression and interleukine-4 tissue expression were higher in areas of mural fibrosis. Transforming growth factor-β expression was higher in collapsed, mural fibrosis and honeycombing areas in comparison to unaffected areas. Positive correlations were found between basic fibroblast growth factor tissue expression and fibroblast telomerase expression and between interleukin-4 tissue expression and myofibroblast α-smooth muscle actin expression. Negative correlations were observed between interleukin-4 expression and basic fibroblast growth factor tissue expression in areas of mural fibrosis. Myofibroblast α-smooth muscle actin expression and interleukin-4 tissue expression in areas of mural fibrosis were negatively associated with patient survival.

CONCLUSION

Fibroblast telomerase expression is higher in areas of early remodeling in lung tissues demonstrating typical interstitial pneumonia, whereas myofibroblast α-smooth muscle actin expression predominates in areas of late remodeling. These events seem to be regulated by basic fibroblast growth factor and interleukin-4 tissue expression, respectively.

Investigating the role of substrate stiffness in the persistence of valvular interstitial cell activation

During heart valve remodeling and in many disease states, valvular interstitial cells (VICs) shift to an activated myofibroblast phenotype characterized by enhanced synthetic and contractile activity. Pronounced alpha smooth muscle actin (αSMA)-positive stress fibers, the hallmark of activated myofibroblasts, are also observed in VICs cultured on stiff substrates especially in the presence of transforming growth factor-beta1 (TGF-β1), however, the detailed relationship between stiffness and VIC phenotype has not been explored. The goal of this study was to characterize VIC activation as a function of substrate stiffness over a wide range of stiffness levels including that of diseased valves (stiff), normal valves (compliant), and hydrogels for heart valve tissue engineering (very soft). VICs obtained from porcine aortic valves were cultured on stiff tissue culture plastic to activate them, then, cultured on collagen-coated polyacrylamide substrates of predefined stiffness in a high-throughput culture system to assess the persistence of activation. Metrics extracted from regression analysis demonstrate that relative to a compliant substrate, stiff substrates result in higher cell numbers, more pronounced expression of αSMA-positive stress fibers, and larger spread area which is in qualitative agreement with previous studies. Our data also indicate that VICs require a much lower substrate stiffness level to "deactivate" them than previously thought. The high sensitivity of VICs to substrate stiffness demonstrates the importance of the mechanical properties of materials used for valve repair or for engineering valve tissue.

Mucosal healing and fibrosis after acute or chronic inflammation in wild type FVB-N mice and C57BL6 procollagen α1(I)-promoter-GFP reporter mice

Background

Injury and intestinal inflammation trigger wound healing responses that can restore mucosal architecture but if chronic, can promote intestinal fibrosis. Intestinal fibrosis is a major complication of Crohn’s disease. The cellular and molecular basis of mucosal healing and intestinal fibrosis are not well defined and better understanding requires well characterized mouse models.

Methods

FVB-N wild type mice and C57BL6 procollagen α1(I)-GFP reporter mice were given one (DSS1) or two (DSS2) cycles of 3% DSS (5 days/cycle) followed by 7 days recovery. Histological scoring of inflammation and fibrosis were performed at DSS1, DSS1+3, DSS1+7, DSS2, DSS2+3, and DSS2+7. Procollagen α1(I)-GFP activation was assessed in DSS and also TNBS models by whole colon GFP imaging and fluorescence microscopy. Colocalization of GFP with α-smooth muscle actin (α-SMA) or vimentin was examined. GFP mRNA levels were tested for correlation with endogenous collagen α1(I) mRNA.

Results

Males were more susceptible to DSS-induced disease and mortality than females. In FVB-N mice one DSS cycle induced transient mucosal inflammation and fibrosis that resolved by 7 days of recovery. Two DSS cycles induced transmural inflammation and fibrosis in a subset of FVB-N mice but overall, did not yield more consistent, severe or sustained fibrosis. In C57BL6 mice, procollagen α1(I)-GFP reporter was activated at the end of DSS1 and through DSS+7 with more dramatic and transmural activation at DSS2 through DSS2+7, and in TNBS treated mice. In DSS and TNBS models GFP reporter expression localized to vimentin⁺ cells and much fewer α-SMA⁺ cells. GFP mRNA strongly correlated with collagen α1(I) mRNA.

Conclusions

One DSS cycle in FVB-N mice provides a model to study mucosal injury and subsequent mucosal healing. The procollagen α1(I)-GFP transgenic provides a useful model to study activation of a gene encoding a major extracellular matrix protein during acute or chronic experimental intestinal inflammation and fibrosis.

TNFR1-activated reactive oxidative species signals up-regulate osteogenic Msx2 programs in aortic myofibroblasts

In LDLR(-/-) mice fed high-fat diabetogenic diets, osteogenic gene-regulatory programs are ectopically activated in vascular myofibroblasts and smooth muscle cells that promote arteriosclerotic calcium deposition. Msx2-Wnt signaling pathways previously identified as important for craniofacial skeletal development are induced in the vasculature by TNF, a prototypic cytokine mediator of the low-grade systemic inflammation of diabesity. To better understand this biology, we studied TNF actions on Msx2 in aortic myofibroblasts. TNF up-regulated Msx2 mRNA 4-fold within 3 h but did not regulate Msx1. Although IL-1β could also induce Msx2 expression, TNF-related apoptosis inducing ligand, receptor activator of nuclear factor-κB ligand, and IL-6 were inactive. Inhibition of nicotinamide adenine dinucleotide phosphate oxidase (Nox) activity and genetically induced Nox deficiency (p47phox(-/-)) reduced Msx2 induction, indicating contributions of reactive oxygen species (ROS) and redox signaling. Consistent with this, rotenone, an antagonist of mitochondrial complex I, inhibited TNF induction of Msx2 and Nox2, whereas pyruvate, an anapleurotic mitochondrial metabolic substrate, enhanced induction. Moreover, the glutathione peroxidase-mimetic ebselen abrogated this TNF response. Treatment of aortic myofibroblasts with hydrogen peroxide up-regulated Msx2 mRNA, promoter activity, and DNA-protein interactions. In vivo, SM22-TNF transgenic mice exhibit increased aortic Msx2 with no change in Msx1. Dosing SM22-TNF mice with either 20 ng/g Nox1 + 20 ng/g Nox2 antisense oligonucleotides or low-dose rotenone reduced arterial Msx2 expression. Aortic myofibroblasts from TNFR1(-/-) mice expressed levels of Msx2 that were 5% that of wild-type and were not inducible by TNF. Wnt7b and active β-catenin levels were also reduced. By contrast, TNF-inducible Msx2 expression was not reduced in TNFR2(-/-) cells. Finally, when cultured under mineralizing conditions, TNFR1(-/-) aortic myofibroblasts exhibited reduced calcification compared with wild-type and TNFR2(-/-) cells. Thus, ROS metabolism contributes to TNF induction of Msx2 and procalcific responses in myofibroblasts via TNFR1. Strategies that reduce vascular Nox- or mitochondrially activated ROS signals may prove useful in mitigating arteriosclerotic calcification.

[Release of HMGB1 by LPS-treated cardiac fibroblasts and its contribution to the production of collagen type I and III]

AIM

To investigate whether cardiac fibroblasts (CFs) treated by LPS can actively secrete high-mobility group box protein 1 (HMGB1) and to analyze the correlation between HMGB1 releasing and the accumulation of collagen type I , III .

METHODS

CFs were isolated from the heart of 7-14-day-old BALB/c mice and cultured in DMEM with 10% fetal bovine serum (FBS). We collected the CFs and cell supernatants after treated by LPS for 0, 6, 12, 24, 36, 48 h, respectively. The mRNA and protein expression levels of HMGB1, collagen 1a1 (col1a1) and collagen 3a1 (col3a1) in CFs after LPS stimulation were detected by RT-PCR and Western blotting, respectively. The intracellular localization of HMGB1 in treated CFs was investigated by immunofluorescence.

RESULTS

After 0-6 h of LPS stimulation, the mRNA levels of HMGB1, col1a1, col3a1 had no significant changes; but increased obviously at 12, 24, 36, 48 h. HMGB1 was found in the cell supernatant by Western blotting after 24 h LPS stimulation, and its expression decreased following the first rise in CFs. Meanwhile, immunofluorescence showed HMGB1 translocation from nucleus to cytoplasm. The levels of col1a1 and col3a1 were up-regulated in CFs after stimulation.

CONCLUSION

LPS can induce HMGB1 translocation from nucleus to cytoplasm and across cellular membrane to the outside of CFs at a time-dependent manner. Col1a1 and Col3a1, which are closely associated with myocardial fibrosis, were obviously up-regulated by LPS stimulation, which indicates that actively released HMGB1 might contribute to myocardial fibrosis following the endotoxin induced-sepsis.

Periostin facilitates skin sclerosis via PI3K/Akt dependent mechanism in a mouse model of scleroderma

Objective

Periostin, a novel matricellular protein, is recently reported to play a crucial role in tissue remodeling and is highly expressed under fibrotic conditions. This study was undertaken to assess the role of periostin in scleroderma.

Methods

Using skin from patients and healthy donors, the expression of periostin was assessed by immunohistochemistry and immunoblotting analyses. Furthermore, we investigated periostin^−/− (PN^−/−) and wild-type (WT) mice to elucidate the role of periostin in scleroderma. To induce murine cutaneous sclerosis, mice were subcutaneously injected with bleomycin, while untreated control groups were injected with phosphate-buffered saline. Bleomycin-induced fibrotic changes were compared in PN^−/− and WT mice by histological analysis as well as by measurements of profibrotic cytokine and extracellular matrix protein expression levels in vivo and in vitro. To determine the downstream pathway involved in periostin signaling, receptor neutralizing antibody and signal transduction inhibitors were used in vitro.

Results

Elevated expression of periostin was observed in the lesional skin of patients with scleroderma compared with healthy donors. Although WT mice showed marked cutaneous sclerosis with increased expression of periostin and increased numbers of myofibroblasts after bleomycin treatment, PN^−/− mice showed resistance to these changes. In vitro, dermal fibroblasts from PN^−/− mice showed reduced transcript expression of alpha smooth actin and procollagen type-I alpha 1 (Col1α1) induced by transforming growth factor beta 1 (TGFβ1). Furthermore, recombinant mouse periostin directly induced Col1α1 expression in vitro, and this effect was inhibited by blocking the αv integrin-mediated PI3K/Akt signaling either with anti-αv functional blocking antibody or with the PI3K/Akt kinase inhibitor LY294002.

Conclusion

Periostin plays an essential role in the pathogenesis of Bleomycin-induced scleroderma in mice. Periostin may represent a potential therapeutic target for human scleroderma.

Redirecting valvular myofibroblasts into dormant fibroblasts through light-mediated reduction in substrate modulus

Fibroblasts residing in connective tissues throughout the body are responsible for extracellular matrix (ECM) homeostasis and repair. In response to tissue damage, they activate to become myofibroblasts, which have organized contractile cytoskeletons and produce a myriad of proteins for ECM remodeling. However, persistence of myofibroblasts can lead to fibrosis with excessive collagen deposition and tissue stiffening. Thus, understanding which signals regulate de-activation of myofibroblasts during normal tissue repair is critical. Substrate modulus has recently been shown to regulate fibrogenic properties, proliferation and apoptosis of fibroblasts isolated from different organs. However, few studies track the cellular responses of fibroblasts to dynamic changes in the microenvironmental modulus. Here, we utilized a light-responsive hydrogel system to probe the fate of valvular myofibroblasts when the Young’s modulus of the substrate was reduced from ∼32 kPa, mimicking pre-calcified diseased tissue, to ∼7 kPa, mimicking healthy cardiac valve fibrosa. After softening the substrata, valvular myofibroblasts de-activated with decreases in α-smooth muscle actin (α-SMA) stress fibers and proliferation, indicating a dormant fibroblast state. Gene signatures of myofibroblasts (including α-SMA and connective tissue growth factor (CTGF)) were significantly down-regulated to fibroblast levels within 6 hours of in situ substrate elasticity reduction while a general fibroblast gene vimentin was not changed. Additionally, the de-activated fibroblasts were in a reversible state and could be re-activated to enter cell cycle by growth stimulation and to express fibrogenic genes, such as CTGF, collagen 1A1 and fibronectin 1, in response to TGF-β1. Our data suggest that lowering substrate modulus can serve as a cue to down-regulate the valvular myofibroblast phenotype resulting in a predominantly quiescent fibroblast population. These results provide insight in designing hydrogel substrates with physiologically relevant stiffness to dynamically redirect cell fate in vitro.

Mechanisms of fibrosis: therapeutic translation for fibrotic disease

Fibrosis is a pathological feature of most chronic inflammatory diseases. Fibrosis, or scarring, is defined by the accumulation of excess extracellular matrix components. If highly progressive, the fibrotic process eventually leads to organ malfunction and death. Fibrosis affects nearly every tissue in the body. Here we discuss how key components of the innate and adaptive immune response contribute to the pathogenesis of fibrosis. We also describe how cell-intrinsic changes in important structural cells can perpetuate the fibrotic response by regulating the differentiation, recruitment, proliferation and activation of extracellular matrix-producing myofibroblasts. Finally, we highlight some of the key mechanisms and pathways of fibrosis that are being targeted as potential therapies for a variety of important human diseases.

Genesis of the myofibroblast in lung injury and fibrosis

Tissue injury incites a repair response with a key mesenchymal component that provides the essential connective tissue for subsequent regeneration or pathological fibrosis. The fibroblast is the major mesenchymal cell type to be implicated in this connective tissue response, and it is in its activated or differentiated form that it participates in the repair process. The myofibroblast represents such an activated mesenchymal cell and is a key source of extracellular matrix and inflammatory/fibrogenic cytokines as well as participating in wound contraction. Although successful healing results in gradual disappearance of myofibroblasts, their persistence is associated with chronic and progressive fibrosis. Thus, elucidation of the mechanism involved in the genesis of the myofibroblast should provide insight into both pathogenesis of chronic fibrotic diseases and therapeutic strategies for their management and control. Although the fibroblast is a well-documented progenitor cell for the myofibroblast, recent studies have suggested additional precursor cells that have the potential to give rise to the myofibroblast. Many of the studies focused on mechanisms and factors that regulate induction of α-smooth muscle actin expression, a key and commonly used marker of the myofibroblast. These reveal complex and multifactorial mechanisms involving transcriptional and epigenetic regulation and implicating diverse cell-signaling pathways, including those activated by the potent fibrogenic cytokine transforming growth factor β. Despite these extensive studies, many aspects remain poorly understood, with the suggestion that additional novel mechanisms remain to be discovered. Future studies with the help of newly developed technical advancements should expedite discovery in this direction.

Low-grade myofibroblastic sarcoma of the maxillary region in a dog

A subcutaneous tumour was identified in the maxillary region of a 14-year-old mixed breed dog. This tumour had grown rapidly over 2 weeks. Microscopically, the tumour had ill-defined borders and was composed of bundles and whorls of atypical spindle cells accompanied by abundant collagen fibres. Immunohistochemically, neoplastic cells were immunoreactive for vimentin, α-smooth muscle actin and calponin and negative for S100 protein, von Willebrand factor, desmin and smoothelin. These results suggested that the neoplastic cells were derived from myofibroblasts and that the tumour was a low-grade myofibroblastic sarcoma.

Invasive breast cancer induces laminin-332 upregulation and integrin β4 neoexpression in myofibroblasts to confer an anoikis-resistant phenotype during tissue remodeling

INTRODUCTION

Although development of anoikis-resistant myofibroblasts during tissue remodeling is known to be associated with tumor invasion, the mechanism by which myofibroblasts become resistant to anoikis is unknown. We previously demonstrated laminin-332 upregulation in the fibrosis around invasive ductal carcinoma (IDC). Because laminin-332 promotes cell survival through binding to integrins, we hypothesized that invasive breast cancer cells confer an anoikis-resistant phenotype on myofibroblasts by upregulating laminin-332 expression during tissue remodeling. Here, we demonstrate that invasive breast cancer cells induce laminin-332 upregulation and integrin β4 neoexpression in myofibroblasts to confer an anoikis-resistant phenotype.

METHODS

Three types of fibroblasts were isolated from the tumor burden, the fibrosis, and normal tissue of patients with early stage IDC (less than 10 mm diameter), designated cancer-associated fibroblasts (CAFs), interface fibroblasts (InFs), and normal breast fibroblasts (NBFs), respectively. To investigate direct and indirect crosstalk with tumor cells, fibroblasts were co-cultured with invasive MDA-MB-231 or noninvasive MCF7 cells or in conditioned medium. Anoikis resistance of fibroblasts was measured by cell viability and caspase-3 activity after incubation on poly-HEMA coated plates for 72 hours. Involvement of laminin-332/integrin α3β1 or α6β4 signaling in anoikis resistance was confirmed by treatment with purified laminin-332 or blocking antibodies against laminin-332, integrin β1, or integrin β4.

RESULTS

MDA-MB-231 cells induced laminin-332 upregulation and integrin β4 neoexpression in fibroblasts, leading to anoikis resistance. InFs showed a higher endogenous level of laminin-332 than did CAFs and NBFs. After stimulation with MDA-MB-231-conditioned medium, laminin-332 expression of InFs was dramatically increased and maintained under anoikis conditions. Laminin-332 upregulation was also observed in CAFs and NBFs, but at a lower level than in InFs. Laminin-332 induced Akt (Ser473) phosphorylation by binding to integrin α3β1. Integrin β4 neoexpression induced laminin-332-independent Rac1 activation and promoted anoikis resistance in fibroblasts approximately twofold more effectively than did laminin-332, regardless of the type of fibroblast. In addition, integrin β4 expression suppressed fibroblast aggregation in conditions of anoikis.

CONCLUSION

Invasive breast cancer cells confer an anoikis-resistant phenotype on myofibroblasts during tissue remodeling by inducing laminin-332 upregulation and integrin β4 neoexpression. Interface fibroblasts appear to be the primary myofibroblasts that interact with invasive tumor cells during tissue remodeling.

Hierarchical formation of supramolecular transient networks in water: a modular injectable delivery system

A modular one-component supramolecular transient network in water, based on poly(ethylene glycol) and end-capped with four-fold hydrogen bonding units, is reported. Due to its nonlinear structural formation, this system allows active proteins to be added to the hydrogel during formation. Once implanted in vivo it releases the protein by erosion of both the protein and polymer via dissolution.