Smooth muscle alpha-actin expression and myofibroblast differentiation by TGFbeta are dependent upon MK2

Skin repair and infection control in diabetic, obese mice using bioactive laser-activated sealants

Conventional wound approximation devices, including sutures, staples, and glues, are widely used but risk of wound dehiscence, local infection, and scarring can be exacerbated in these approaches, including in diabetic and obese individuals. This study reports the efficacy and quality of tissue repair upon photothermal sealing of full-thickness incisional skin wounds using silk fibroin-based laser-activated sealants (LASEs) containing copper chloride salt (Cu-LASE) or silver nanoprisms (AgNPr-LASE), which absorb and convert near-infrared (NIR) laser energy to heat. LASE application results in rapid and effective skin sealing in healthy, immunodeficient, as well as diabetic and obese mice. Although lower recovery of epidermal structure and function was seen with AgNPr-LASE sealing, likely because of the hyperthermia induced by laser and presence of this material in the wound space, this approach resulted in higher enhancement in recovery of skin biomechanical strength compared to sutures and Cu-LASEs in diabetic, obese mice. Histological and immunohistochemical analyses revealed that AgNPr-LASEs resulted in significantly lower neutrophil migration to the wound compared to Cu-LASEs and sutures, indicating a more muted inflammatory response. Cu-LASEs resulted in local tissue toxicity likely because of effects of copper ions as manifested in the form of a significant epidermal gap and a 'depletion zone', which was a region devoid of viable cells proximal to the wound. Compared to sutures, LASE-mediated sealing, in later stages of healing, resulted in increased angiogenesis and diminished myofibroblast activation, which can be indicative of lower scarring. AgNPr-LASE loaded with vancomycin, an antibiotic drug, significantly lowered methicillin-resistant Staphylococcus aureus (MRSA) load in a pathogen challenge model in diabetic and obese mice and also reduced post-infection inflammation of tissue compared to antibacterial sutures. Taken together, these attributes indicate that AgNPr-LASE demonstrated a more balanced quality of tissue sealing and repair in diabetic and obese mice and can be used for combating local infections, that can result in poor healing in these individuals.

Resveratrol inhibits arecoline-induced fibrotic properties of buccal mucosal fibroblasts via miR-200a activation

Background/purpose

Oral submucous fibrosis (OSF) is a precancerous lesion in the oral cavity, commonly results from the Areca nut chewing habit. Arecoline, the main component of Areca nut, is known to stimulate the activation of myofibroblasts, which can lead to abnormal collagen I deposition. Meanwhile, Resveratrol is a non-flavonoid phenolic substance that can be naturally obtained from various berries and foods. Given that resveratrol has significant anti-fibrosis traits in other organs, but little is known about its effect on OSF, this study aimed to investigate the therapeutic impact of resveratrol on OSF and its underlying mechanism.

Materials and methods

The cytotoxicity of resveratrol was tested using normal buccal mucosal fibroblasts (BMFs). Myofibroblast phenotypes such as collagen contractile, enhanced migration, and wound healing capacities in dose-dependently resveratrol-treated fBMFs were examined.

Results

Current results showed that arecoline induced cell migration and contractile activity in BMFs as well as upregulated the expressions of α-SMA, type I collagen, and ZEB1 markers. Resveratrol intervention, on the other hand, was shown to inhibit arecoline-induced myofibroblast activation and reduce myofibroblast hallmarks and EMT markers. Additionally, resveratrol was also demonstrated to restore the downregulated miR-200a in the arecoline-stimulated cells.

Conclusion

In a nutshell, these findings implicate that resveratrol may have an inhibitory influence on arecoline-induced fibrosis via the regulation of miR-200a. Hence, resveratrol may be used as a therapeutic strategy for OSF intervention.

The Use of a Dehydrated Cellularized Collagen Matrix to Replace Fibrotic Vocal Fold Mucosa

OBJECTIVES

Fibrosis of the vocal fold lamina propria reduces vocal cord vibration resulting in a chronically hoarse voice. We describe a novel approach using umbilical cord-derived mesenchymal stem cells in a dehydrated collagen matrix (cellogen) to reconstruct the delicate balance of extracellular matrix within the vocal fold lamina propria whilst limiting the host inflammatory response to the implant.

METHODS

Human umbilical cord-derived mesenchymal stem-cells were embedded in bovine type I collagen hydrogel and dehydrated using the RAFT™ 3D culture system. The extracellular matrix, cellular viability and composition, paracrine profile, and genomic profile were assessed and the scaffold engrafted onto the hind muscle of NUDE mice.

RESULTS

The cells retained stem-cell markers following fabrication and secreted collagen III, fibronectin, and glycosaminoglycans within the scaffold. Electron microscopy showed the scaffold consisted of single strands of protein with interspersed bundles of a similar size to native vocal fold lamina propria. The use of the dehydration step improved cell viability and upregulated the expression of genes important in wound healing and matrix organization compared with unmodified collagen hydrogel carriers. The cells were shown to secrete exosomes and cytokines and, following engraftment within an immunocompromised mouse model, appeared to modulate the host inflammatory response compared with controls.

CONCLUSION

This article provides a scalable cell-protein scaffold that with further modifications could provide a replacement for lost or damaged vocal fold mucosa. Further investigations are required to assess the mechanical properties of the scaffold and inhibit the differentiation of the umbilical cord-derived stem-cells following implantation. Laryngoscope, 134:882-893, 2024.

The Incidence of Urgent Tube Shunt Surgery for Diabetic Neovascular Glaucoma at a Tertiary Academic Medical Center

Background

Diabetic neovascular glaucoma is a secondary glaucoma that may require immediate correction of elevated intraocular pressure to control pain and protect the optic nerve. While there is a seasonal trend to glucose levels, it is unknown if a seasonal trend exists for diabetic neovascular glaucoma.

Objective

This study evaluates the incidence of urgent glaucoma tube shunt implantation in diabetic neovascular glaucoma in a tertiary academic referral center in Southern California.

Methods

Electronic medical records were queried for urgent glaucoma tube shunt surgery from 2014 to 2021. The number of cases were separated by month of occurrence, and average hemoglobin A1c values were calculated per month. Data were analyzed via ANOVA tests and one-tailed t-tests.

Results

A total of 127 cases were identified. The months of March and April contained the most cases averaging 3 and 2.75 cases, respectively. April had statistically significant higher case numbers than that of other months (P = .041). ANOVA tests excluding April showed no statistically significant difference between the remaining months (P = .901). Average hemoglobin A1c values were highest in the months of April and March at 9.8 and 9.6%, respectively.

Conclusion

Emergency glaucoma tube shunt surgery for diabetic neovascular glaucoma occurs most frequently in April. This observation may provide insight into disease prevention through diabetes management and help improve surgical operations such that staffing and resources are allocated accordingly.

Cancer-associated fibroblasts: Mediators of head and neck tumor microenvironment remodeling

Cancer-associated fibroblasts (CAFs) are involved in critical aspects of head and neck squamous cell carcinoma (HNSCC) pathogenesis, such as the formation of a tumor-permissive extracellular matrix structure, angiogenesis, or immune and metabolic reprogramming of the tumor microenvironment (TME), with implications for metastasis and resistance to radiotherapy and chemotherapy. The pleiotropic effect of CAFs in TME is likely to reflect the heterogeneity and plasticity of their population, with context-dependent effects on carcinogenesis. The specific properties of CAFs provide many targetable molecules that could play an important role in the future therapy of HNSCC. In this review article, we will focus on the role of CAFs in the TME of HNSCC tumors. We will also discuss clinically relevant agents targeting CAFs, their signals, and signaling pathways, which are activated by CAFs in cancer cells, with the potential for repurposing for HNSCC therapy.

Associations of Tissue and Soluble LOX-1 with Human Abdominal Aortic Aneurysm

Background Indication for prophylactic surgical abdominal aortic aneurysm (AAA) repair depends on the maximal aortic diameter. The lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) is the major receptor for uptake of oxidized low-density lipoprotein cholesterol and is implicated in atherosclerosis. A soluble form of LOX-1 (sLOX-1) has been discussed as a novel biomarker in coronary artery disease and stroke. Herein, we assessed the regulation of aortic LOX-1 as well as the diagnostic and risk stratification potential of sLOX-1 in patients with AAA. Methods and Results Serum sLOX-1 was assessed in a case-control study in AAA (n=104) and peripheral artery disease (n=104). sLOX-1 was not statistically different between AAA and peripheral artery disease but was higher in AAA (β=1.28, P=0.04) after adjusting for age, atherosclerosis, type 2 diabetes, prescription of statins, β-blockers, ACE inhibitors, and therapeutic anticoagulation. sLOX-1 was not associated with the aortic diameter, AAA volume, or the thickness of the intraluminal thrombus. Aortic LOX-1 mRNA expression tended to be higher in AAA when compared with disease, and expression was positively associated with cleaved caspase-3, smooth muscle actin, collagen, and macrophage content. Conclusions In AAA, sLOX-1 was differently affected by age, cardiometabolic diseases, and corresponding medical therapies. Comparison with nonatherosclerotic disease would be beneficial to further elucidate the diagnostic potential of sLOX-1, although it was not useful for risk stratification. Aneurysmal LOX-1 mRNA expression was increased and positively associated with smooth muscle cells and collagen content, suggesting that LOX-1 is eventually not deleterious in human AAA and could counteract AAA rupture.

Combination of Niclosamide and Pirfenidone Alleviates Pulmonary Fibrosis by Inhibiting Oxidative Stress and MAPK/Nf-κB and STATs Regulated Genes

The pathogenesis of pulmonary fibrosis (PF) is extremely complex and involves numerous intersecting pathways. The successful management of PF may require combining multiple agents. There is a growing body of evidence that suggests the potential benefits of niclosamide (NCL), an FDA-approved anthelminthic drug, in targeting different fibrogenesis molecules. This study aimed at investigating the anti-fibrotic potential of NCL alone and in combination with pirfenidone (PRF), an approved drug for PF, in a bleomycin (BLM) induced PF experimental model. PF was induced in rats by intratracheal BLM administration. The effect of NCL and PRF individually and in combination on different histological and biochemical parameters of fibrosis was investigated. Results revealed that NCL and PRF individually and in combination alleviated the histopathological changes, extracellular matrix deposition and myofibroblastic activation induced by BLM. NCL and PRF either individually or in combination inhibited the oxidative stress and subsequent pathways. They modulated the process of fibrogenesis by inhibiting MAPK/NF-κB and downstream cytokines. They inhibited STATs and downstream survival-related genes including BCL-2, VEGF, HIF-α and IL-6. Combining both drugs showed significant improvement in the tested markers in comparison to the monotherapy. NCL, therefore, has a potential synergistic effect with PRF in reducing the severity of PF.

Phosphorylation of the small heat shock protein HspB1 regulates cytoskeletal recruitment and cell motility

The small heat shock protein HspB1, also known as Hsp25/27, is a ubiquitously expressed molecular chaperone that responds to mechanical cues. Uniaxial cyclic stretch activates the p38 mitogen-activated protein kinase (MAPK) signaling cascade and increases the phosphorylation of HspB1. Similar to the mechanosensitive cytoskeletal regulator zyxin, phospho-HspB1 is recruited to features of the stretch-stimulated actin cytoskeleton. To evaluate the role of HspB1 and its phosphoregulation in modulating cell function, we utilized CRISPR/Cas9-edited HspB1-null cells and determined they were altered in behaviors such as actin cytoskeletal remodeling, cell spreading, and cell motility. In our model system, expression of WT HspB1, but not nonphosphorylatable HspB1, rescued certain characteristics of the HspB1-null cells including the enhanced cell motility of HspB1-null cells and the deficient actin reinforcement of stretch-stimulated HspB1-null cells. The recruitment of HspB1 to high-tension structures in geometrically constrained cells, such as actin comet tails emanating from focal adhesions, also required a phosphorylatable HspB1. We show that mechanical signals activate posttranslational regulation of the molecular chaperone, HspB1, and are required for normal cell behaviors including actin cytoskeletal remodeling, cell spreading, and cell migration.

The extended effect of adsorbed damage-associated molecular patterns and Toll-like receptor 2 signaling on macrophage-material interactions

Implanted biomaterials elicit an immune-mediated foreign body reaction (FBR) that results in the fibrous encapsulation of the implant and can critically impact the performance of some implants. Consequently, understanding the molecular mechanisms that underpin cell-materials interactions that initiate biomaterial-induced inflammation and fibrosis is critical to improving the performance of biomaterial implants negatively impacted by the FBR. Damage-associated molecular patterns (DAMPs) are endogenous mediators of inflammation that are released upon tissue injury and induce sterile inflammation via Toll-like receptors (TLRs). However, the prevalence of DAMPs within the adsorbed protein layer on material surfaces and their role mediating cell-material interactions is unclear. Previously, our group demonstrated that molecules in fibroblast lysates adsorbed to various biomaterials and induced a potent TLR2-dependent inflammatory response in macrophages at 24 h. In this study, we examined the extended response of RAW-Blue reporter macrophages on lysate or serum-adsorbed Teflon™ AF surfaces to understand the potential role of adsorbed DAMPs in macrophage-material interactions at later time points. Lysate-conditioned surfaces maintained increased nuclear factor kappa B (NF-κB) and activator protein 1 (AP-1) transcription factor activity and increased expression Regulated upon Activation, Normal T Cell Expressed and Presumably Secreted (RANTES/CCL5) at 72 h and 120 h, compared to FBS-conditioned surfaces. In contrast, monocyte chemoattractant protein 1 (MCP-1/CCL2) was only elevated at 72 h in lysate conditions. Transforming growth factor beta 1 (TGF-β1) secretion was significantly increased on lysate-conditioned surfaces, while conditioned media from macrophages on lysate-conditioned surfaces induced alpha smooth muscle actin (αSMA) expression in 3T3 fibroblasts. TLR2 neutralizing antibody treatment significantly decreased NF-κB/AP-1 activity and attenuated TGF-β1 expression at both time points, and MCP-1 and RANTES at 72 h. Finally, multinucleated cells were observed on lysate-conditioned surfaces at 72 h, indicating adsorbed DAMPs induced a fusion permissive environment for adherent macrophages. This study demonstrates that adsorbed DAMPs continue to influence macrophage-material responses beyond the initial 24-h period and maintain a pro-inflammatory and fibrotic response that models aspects of the early FBR. Furthermore, the transient inhibition of TLR2 continued to exert an effect at these later time points, suggesting TLR2 may be a target for therapeutic interventions in FBR.

ADAM17, A Key Player of Cardiac Inflammation and Fibrosis in Heart Failure Development During Chronic Catecholamine Stress

Heart failure development is characterized by persistent inflammation and progressive fibrosis owing to chronic catecholamine stress. In a chronic stress state, elevated catecholamines result in the overstimulation of beta-adrenergic receptors (βARs), specifically β2-AR coupling with Gαi protein. Gαi signaling increases the activation of receptor-stimulated p38 mitogen-activated-protein-kinases (p38 MAPKs) and extracellular signal-regulated kinases (ERKs). Phosphorylation by these kinases is a common way to positively regulate the catalytic activity of A Disintegrin and Metalloprotease 17 (ADAM17), a metalloprotease that has grown much attention in recent years and has emerged as a chief regulatory hub in inflammation, fibrosis, and immunity due to its vital proteolytic activity. ADAM17 cleaves and activates proinflammatory cytokines and fibrotic factors that enhance cardiac dysfunction via inflammation and fibrosis. However, there is limited information on the cardiovascular aspect of ADAM17, especially in heart failure. Hence, this concise review provides a comprehensive insight into the structure of ADAM17, how it is activated and regulated during chronic catecholamine stress in heart failure development. This review highlights the inflammatory and fibrotic roles of ADAM17’s substrates; Tumor Necrosis Factor α (TNFα), soluble interleukin-6 receptor (sIL-6R), and amphiregulin (AREG). Finally, how ADAM17-induced chronic inflammation and progressive fibrosis aggravate cardiac dysfunction is discussed.

Engineered Fibroblast Extracellular Vesicles Attenuate Pulmonary Inflammation and Fibrosis in Bleomycin-Induced Lung Injury

Pulmonary fibrosis is a progressive disease for which no curative treatment exists. We have previously engineered dermal fibroblasts to produce extracellular vesicles with tissue reparative properties dubbed activated specialized tissue effector extracellular vesicles (ASTEX). Here, we investigate the therapeutic utility of ASTEX in vitro and in a mouse model of bleomycin-induced lung injury. RNA sequencing demonstrates that ASTEX are enriched in micro-RNAs (miRs) cargo compared with EVs from untransduced dermal fibroblast EVs (DF-EVs). Treating primary macrophages with ASTEX reduced interleukin (IL)6 expression and increased IL10 expression compared with DF-EV-exposed macrophages. Furthermore, exposure of human lung fibroblasts or vascular endothelial cells to ASTEX reduced expression of smooth muscle actin, a hallmark of myofibroblast differentiation (respectively). In vivo, intratracheal administration of ASTEX in naïve healthy mice demonstrated a favorable safety profile with no changes in body weight, lung weight to body weight, fibrotic burden, or histological score 3 weeks postexposure. In an acute phase (short-term) bleomycin model of lung injury, ASTEX reduced lung weight to body weight, IL6 expression, and circulating monocytes. In a long-term setting, ASTEX improved survival and reduced fibrotic content in lung tissue. These results suggest potential immunomodulatory and antifibrotic properties of ASTEX in lung injury.

Mitogen-activated protein kinase-activated protein kinase-2 (MK2) and its role in cell survival, inflammatory signaling, and migration in promoting cancer

Cancer and the immune system share an intimate relationship. Chronic inflammation increases the risk of cancer occurrence and can also drive inflammatory mediators into the tumor microenvironment enhancing tumor growth and survival. The p38 MAPK pathway is activated both acutely and chronically by stress, inflammatory chemokines, chronic inflammatory conditions, and cancer. These properties have led to extensive efforts to find effective drugs targeting p38, which have been unsuccessful. The immediate downstream serine/threonine kinase and substrate of p38 MAPK, mitogen-activated-protein-kinase-activated-protein-kinase-2 (MK2) protects cells against stressors by regulating the DNA damage response, transcription, protein and messenger RNA stability, and motility. The phosphorylation of downstream substrates by MK2 increases inflammatory cytokine production, drives an immune response, and contributes to wound healing. By binding directly to p38 MAPK, MK2 is responsible for the export of p38 MAPK from the nucleus which gives MK2 properties that make it unique among the large number of p38 MAPK substrates. Many of the substrates of both p38 MAPK and MK2 are separated between the cytosol and nucleus and interfering with MK2 and altering this intracellular translocation has implications for the actions of both p38 MAPK and MK2. The inhibition of MK2 has shown promise in combination with both chemotherapy and radiotherapy as a method for controlling cancer growth and metastasis in a variety of cancers. Whereas the current data are encouraging the field requires the development of selective and well tolerated drugs to target MK2 and a better understanding of its effects for effective clinical use.

Comparison of the Effects of Acellular Dermal Matrix and Montelukast on Radiation-Induced Peri-implant Capsular Formation in Rabbits

PURPOSE

Capsular contracture (CC) is a troublesome complication after breast surgery with breast implants, and the risk increases in breast cancer patients after radiotherapy. Studies investigating leukotriene antagonists (eg, montelukast, zafirlukast) found that the acellular dermal matrix (ADM) can help prevent CC. We aimed to compare the effects of ADM and montelukast on CC after irradiation.

METHODS

Eighteen New Zealand white rabbits were randomly divided into 3 groups of 6 each. Miniature cohesive gel implants were inserted into the pocket under the latissimus dorsi muscle. The lateral part was uncovered by the latissimus dorsi muscle. Six animals were included in the control group. In experimental group A (EG-A) (n = 6), the site was partially wrapped with ADM but not covered with muscle. Montelukast (Singulair, 0.2 mg/kg) was administered in experimental group B (EG-B) (n = 6) daily. Groups were irradiated at postoperative day 21 with Co-60 γ rays (25 Gy, single fraction) at the peri-implant area. Rabbits were sacrificed 12 weeks after surgery; implants with peri-implant capsule were harvested. Capsule thickness, collagen pattern, myofibroblast, and transforming growth factor (TGF) β1/2 levels in the peri-implant capsule were evaluated.

RESULTS

On histological evaluation, the capsule was thinner on the lateral aspect (covered with ADM) in EG-A (P = 0.004) and the entire capsule in EG-B (P = 0.004) than in the control group. However, there was no significant difference between EG-A and EG-B (P = 0.073). The collagen distribution pattern was more parallel with low density in the lateral capsular aspect in EG-A, but in the entire capsule in EG-B. The myofibroblast amount (EG-A, P = 0.031; EG-B, P = 0.016) and levels of TGF-β1 and TGF-β2 were reduced in the experimental groups (TGF-β1, EG-A, P = 0.019; TGF-β1, EG-B, P = 0.045; TGF-β2, EG-A, P = 0.018; TGF-β2, EG-B, P = 0.022). There was no significant difference between EG-A and EG-B (myofibroblast, P = 0.201; TGF-β1, P = 0.665; TGF-β2, P = 0.665).

CONCLUSIONS

Acellular dermal matrix and montelukast have a prophylactic effect for CC even when the breast is irradiated. There was no significant difference between ADM and montelukast in preventing capsular formation. The difference is that ADM will only have the effect of covering the capsular formation with ADM and montelukast can cause systemic effects or complications.

Cymbopogon winterianus Essential Oil Attenuates Bleomycin-Induced Pulmonary Fibrosis in a Murine Model

The essential oil of Cymbopogon winterianus (EOCW) is a natural product with antioxidant, anti-inflammatory, and antifibrotic properties. We studied the effect of EOCW in the progression of histological changes of pulmonary fibrosis (PF) in a rodent model. The oil was obtained by hydrodistillation and characterized using gas chromatography–mass spectrometry. Intratracheal instillation of bleomycin was performed in 30 rats to induce PF, while Sham animals were subjected to instillation of saline solution. The treatment was performed using daily oral administration of distilled water, EOCW at 50, 100, and 200 mg/kg, and deflazacort (DFC). After 28 days, hemogram and bronchoalveolar lavage fluid (BALF), tissue levels of malondialdehyde (MDA), superoxide dismutase (SOD), and catalase (CAT) were assayed. Histological grading of PF, immunohistochemical expression of α-smooth muscle actin (α-SMA), and transforming growth factor-β (TGF-β) were also analyzed. The EOCW major compounds were found to be citronellal, geraniol, and citronellol. EOCW significantly reduced inflammation in BALF, reduced MDA levels, and increased SOD activity. EOCW attenuated histological grading of PF and reduced immunohistochemical expression of α-SMA and TGF-β in a dose-dependent way, likely due to the reduction of oxidative stress, inflammation, and TGF-β-induced myofibroblast differentiation.

Characterization of a bovine intestinal myofibroblast cell line and stimulation using phytoglycogen-based nanoparticles bound to inosine monophosphate

The goal of the present study was to characterize a novel bovine intestinal myofibroblast (BT-IMF) cell line isolated from a fetal bovine intestine. This cell type is of importance as intestinal myofibroblasts play a key role in controlling intestinal epithelial cell proliferation, intestinal regulation, wound healing, epithelial cell turnover, and structural support. The present work demonstrates that BT-IMF cells could be successfully cryopreserved and thawed and cultured past 25 passages. Immunocytochemical staining of the BT-IMF cell line was positive for vimentin and smooth muscle actin (α-SMA) and negative for pancytokeratin, suggesting that the cells are myofibroblastic in type. Growth kinetic experiments demonstrate that hydrocortisone negatively impacts BT-IMF growth and non-essential amino acids enhance its proliferation. Inosine monophosphate (IMP) is a dietary nucleotide and is essential for supporting animal health. Stimulation with IMP bound to a novel phytoglycogen-based nanocarrier (IMP-NP) showed enhanced cell proliferation. BT-IMF provides a new tool for studying bovine cells in vitro and may be of particular interest for cultured meat manufacturing in the future.

Hypoxia Mesenchymal Stem Cells Accelerate Wound Closure Improvement by Controlling α-smooth Muscle actin Expression in the Full-thickness Animal Model

BACKGROUND: The active myofibroblast producing extracellular matrix deposition regarding wound closure is characterized by alpha-smooth muscle actin (α-SMA) expression. However, the persistence of α-SMA expression due to prolonged inflammation may trigger scar formation. A new strategy to control α-SMA expression in line with wound closure improvement uses hypoxic mesenchymal stem cells (HMSCs) due to their ability to firmly control inflammation for early initiating cell proliferation, including the regulation of α-SMA expression associated with wound closure acceleration. AIM: This study aimed to explore the role of HMSCs in accelerating the optimum wound closure percentages through controlling the α-SMA expression. MATERIALS AND METHODS: Twenty-four full-thickness rats wound model were randomly divided into four groups: Sham (Sh), Control (C) by NaCl administration only, and two treatment groups by HMSCs at doses of 1.5×106 cells (T1) and HMSCs at doses of 3×106 cells (T2). HMSCs were incubated under hypoxic conditions. The α-SMA expression was analyzed under immunohistochemistry staining assay, and the wound closure percentage was analyzed by ImageJ software. RESULTS: This study showed a significant increase in wound closure percentage in all treatment groups that gradually initiated on days 6 and 9 (p < 0.05). In line with the increase of wound closure percentages on day 9, there was also a significant decrease in α-SMA expression in all treatment groups (p < 0.05), indicating the optimum wound healing has preceded. CONCLUSION: HMSCs have a robust ability to accelerated wound closure improvement to the optimum wound healing by controlling α-SMA expression depending on wound healing phases.

The Dynamic Interplay Between Cardiac Inflammation and Fibrosis

Heart failure is a leading cause of death worldwide. While there are multiple etiologies contributing to the development of heart failure, all cause result in impairments in cardiac function that is characterized by changes in cardiac remodeling and compliance. Fibrosis is associated with nearly all forms of heart failure and is an important contributor to disease pathogenesis. Inflammation also plays a critical role in the heart and there is a large degree of interconnectedness between the inflammatory and fibrotic response. This review discusses the cellular and molecular mechanisms contributing to inflammation and fibrosis and the interplay between the two.

Human Cardiac Fibroblast Number and Activation State Modulate Electromechanical Function of hiPSC-Cardiomyocytes in Engineered Myocardium

Cardiac tissue engineering using hiPSC-derived cardiomyocytes is a promising avenue for cardiovascular regeneration, pharmaceutical drug development, cardiotoxicity evaluation, and disease modeling. Limitations to these applications still exist due in part to the need for more robust structural support, organization, and electromechanical function of engineered cardiac tissues. It is well accepted that heterotypic cellular interactions impact the phenotype of cardiomyocytes. The current study evaluates the functional effects of coculturing adult human cardiac fibroblasts (hCFs) in 3D engineered tissues on excitation and contraction with the goal of recapitulating healthy, nonarrhythmogenic myocardium in vitro. A small population (5% of total cell number) of hCFs in tissues improves tissue formation, material properties, and contractile function. However, two perturbations to the hCF population create disease-like phenotypes in engineered cardiac tissues. First, increasing the percentage of hCFs to 15% resulted in tissues with increased ectopic activity and spontaneous excitation rate. Second, hCFs undergo myofibroblast activation in traditional two-dimensional culture, and this altered phenotype ablated the functional benefits of hCFs when incorporated into engineered cardiac tissues. Taken together, the results of this study demonstrate that human cardiac fibroblast number and activation state modulate electromechanical function of hiPSC-cardiomyocytes and that a low percentage of quiescent hCFs are a valuable cell source to advance a healthy electromechanical response of engineered cardiac tissue for regenerative medicine applications.

Myofibroblasts and Fibrosis: Mitochondrial and Metabolic Control of Cellular Differentiation

Cardiac fibrosis is mediated by the activation of resident cardiac fibroblasts, which differentiate into myofibroblasts in response to injury or stress. Although myofibroblast formation is a physiological response to acute injury, such as myocardial infarction, myofibroblast persistence, as occurs in heart failure, contributes to maladaptive remodeling and progressive functional decline. Although traditional pathways of activation, such as TGFβ (transforming growth factor β) and AngII (angiotensin II), have been well characterized, less understood are the alterations in mitochondrial function and cellular metabolism that are necessary to initiate and sustain myofibroblast formation and function. In this review, we highlight recent reports detailing the mitochondrial and metabolic mechanisms that contribute to myofibroblast differentiation, persistence, and function with the hope of identifying novel therapeutic targets to treat, and potentially reverse, tissue organ fibrosis.

Novel Therapeutic Potential of Mitogen-Activated Protein Kinase Activated Protein Kinase 2 (MK2) in Chronic Airway Inflammatory Disorders

OBJECTIVE

The primary focus of this review is to highlight the current and emerging proinflammatory role of MK2 kinase signaling in p38MAPK pathway and to provide a detailed evaluation on the prospects of MK2 inhibition with special emphasis on the etiology of chronic inflammatory airway diseases, such as asthma, idiopathic pulmonary fibrosis, lung cancer, acute lung injury and acute respiratory distress syndrome.

BACKGROUND

MK2 belongs to serine-threonine kinase family and is activated directly by stress and inflammatory signal through p38MAPK phosphorylation in diverse inflammatory conditions through the Toll-like receptor signaling pathway. MK2 has been thought to be a critical factor involved in the regulation of synthesis and release of pro-inflammatory (TNF-α, IL-6 and IL-1β, etc.) proteins. Targeted inhibition of MK2 kinase has been shown to significantly reduce the production and release of these cytokine molecules. Therefore, MK2 has been identified as an effective strategy (alternative to p38MAPK) to block this pro-inflammatory signaling pathway.

RESULTS

The inhibition of MK2 may lead to similar or better efficacy as that of p38 inhibitors, and interestingly avoids the systemic toxicity shown by the p38 inhibitors. Thus, MK2 has been the focus of intense interdisciplinary research and its specific inhibition can be a novel and potential therapeutic strategy for the treatment of chronic airway inflammatory diseases.

CONCLUSION

Promising advancement in understanding and rigorous exploration of the role of MK2 kinase in inflammatory processes may contribute to the development of newer and safer therapy for the treatment of chronic airway inflammatory diseases in the future.

Mitogen-activated Protein Kinase-activated Protein Kinase 2 Inhibition Attenuates Fibroblast Invasion and Severe Lung Fibrosis

Severe pulmonary fibrosis such as idiopathic pulmonary fibrosis (IPF) is characterized by the accumulation of extracellular matrix and fibroblast activation. Targeting fibroblast activation has contributed to the development of antifibrotic therapeutics for patients with IPF. Mitogen-activated protein kinase-activated protein kinase 2 (MK2), downstream in the transforming growth factor-β/p38 mitogen-activated protein kinase pathway, has been implicated in inflammatory and fibrosing diseases. Increased concentrations of activated MK2 were expressed in IPF lung and in the mouse bleomycin model of lung fibrosis. The aim of the present study was to determine the role and the mechanisms of MK2 in fibroblast invasion and lung fibrosis. Our results showed that an MK2 inhibitor (MMI-0100) was able to inhibit the invasive capacity of lung fibroblasts isolated from patients with IPF, as well as fibroblasts isolated from both wild-type mice and mice with overexpressing hyaluronan synthase 2 (HAS2) in the myofibroblast compartment. We previously showed that hyaluronan and HAS2 regulate fibroblast invasion and lung fibrosis in vivo. The results of the present study showed that MMI-0100 reduced transforming growth factor-β-induced hyaluronan production in human and mouse fibroblasts in vitro and that HAS2 mediated MK2 activation, suggesting a feed-forward loop in fibroblast activation. More importantly, MK2 inhibition attenuated hyaluronan accumulation and reduced collagen content in bleomycin-injured mouse lungs in vivo. Conditional deletion of MK2 in fibroblasts attenuated bleomycin-induced lung fibrosis. These data provide evidence that MK2 has a role in fibroblast invasion and fibrosis and may be a novel therapeutic target in pulmonary fibrosis.

Cardiac Fibroblast p38 MAPK: A Critical Regulator of Myocardial Remodeling

The cardiac fibroblast is a remarkably versatile cell type that coordinates inflammatory, fibrotic and hypertrophic responses in the heart through a complex array of intracellular and intercellular signaling mechanisms. One important signaling node that has been identified involves p38 MAPK; a family of kinases activated in response to stress and inflammatory stimuli that modulates multiple aspects of cardiac fibroblast function, including inflammatory responses, myofibroblast differentiation, extracellular matrix turnover and the paracrine induction of cardiomyocyte hypertrophy. This review explores the emerging importance of the p38 MAPK pathway in cardiac fibroblasts, describes the molecular mechanisms by which it regulates the expression of key genes, and highlights its potential as a therapeutic target for reducing adverse myocardial remodeling.

An immortalized cell line derived from renal erythropoietin-producing (REP) cells demonstrates their potential to transform into myofibroblasts

The erythroid growth factor erythropoietin (Epo) is produced by renal interstitial fibroblasts, called REP (renal Epo-producing) cells, in a hypoxia-inducible manner. In chronic kidney disease (CKD), REP cells lose their Epo-production ability, leading to renal anaemia. Concurrently, REP cells are suggested to be transformed into myofibroblasts, which are the major player of renal fibrosis. Although establishment of cultured cell lines derived from REP cells has been a long-term challenge, we here successfully established a REP-cell-derived immortalized and cultivable cell line (Replic cells) by using a genetically modified mouse line. Replic cells exhibited myofibroblastic phenotypes and lost their Epo-production ability, reflecting the situation in renal fibrosis. Additionally, we found that cell-autonomous TGFβ signalling contributes to maintenance of the myofibroblastic features of Replic cells. Furthermore, the promoters of genes for Epo and HIF2α, a major activator of Epo gene expression, were highly methylated in Replic cells. Thus, these results strongly support our contention that REP cells are the origin of myofibroblasts in fibrotic kidneys and demonstrate that cell-autonomous TGFβ signalling and epigenetic silencing are involved in renal fibrosis and renal anaemia, respectively, in CKD. The Replic cell line is a useful tool to further investigate the molecular mechanisms underlying renal fibrosis.

Crosstalk between mitogen-activated protein kinase inhibitors and transforming growth factor-β signaling results in variable activation of human dermal fibroblasts

Fibroblast activation is a key step in the establishment of skin fibrosis induced by acute injury, and it is characterized by the differentiation of plastic resident tissue fibroblasts into contractile, extracellular matrix‑secreting myofibroblasts. As fibroblast activation must be regulated in vivo, fibroblasts receive signals from the surrounding environment that initiate their fibrotic program. Thus, the present study investigated the effects of mitogen‑activated protein kinase (MAPK) signaling pathways on fibroblast activation. It was demonstrated in primary human dermal fibroblasts that small molecule‑mediated inhibition of extracellular signal‑regulated kinase (ERK) and c‑Jun N‑terminal kinase (JNK) potentiated fibroblast activation, and that small molecule‑mediated inhibition of p38 antagonized fibroblast activation. ERK and JNK inhibition cooperatively enhanced fibroblast activation mediated by treatment with exogenous transforming growth factor (TGF)‑β1, and p38 inhibition antagonized ERK inhibitor‑mediated or JNK inhibitor‑mediated fibroblast activation. Transcript analysis demonstrated that ERK and JNK inhibitor‑mediated fibroblast activation was accompanied by distinct changes in the expression of TGF‑β‑associated ligands and receptors, and that p38 inhibitor‑mediated antagonism of fibroblast activation was accompanied by a distinct expression paradigm of TGF‑β‑associated genes, including upregulation of betaglycan. ERK inhibitor‑mediated and JNK inhibitor‑mediated fibroblast activation was partially antagonized by small molecule‑mediated inhibition of TGF‑β receptor (R)1, indicating that these mechanisms of fibroblast activation are partially dependent on TGF‑β/TGF‑βR signaling. These data collectively demonstrate and provide partial explanations of the varied effects and pathway dependencies of MAPK inhibitor‑mediated effects on fibroblast activation.

Mesenchymal MAPKAPK2/HSP27 drives intestinal carcinogenesis

Mesenchymal cells in the microenvironment of cancer exert important functions in tumorigenesis; however, little is known of intrinsic pathways that mediate these effects. MAPK signals, such as from MAPKAPK2 (MK2) are known to modulate tumorigenesis, yet their cell-specific role has not been determined. Here, we studied the cell-specific role of MK2 in intestinal carcinogenesis using complete and conditional ablation of MK2. We show that both genetic and chemical inhibition of MK2 led to decreased epithelial cell proliferation, associated with reduced tumor growth and invasive potential in the Apc^min/+ mouse model. Notably, this function of MK2 was not mediated by its well-described immunomodulatory role in immune cells. Deletion of MK2 in intestinal mesenchymal cells (IMCs) led to both reduced tumor multiplicity and growth. Mechanistically, MK2 in IMCs was required for Hsp27 phosphorylation and the production of downstream tumorigenic effector molecules, dominantly affecting epithelial proliferation, apoptosis, and angiogenesis. Genetic ablation of MK2 in intestinal epithelial or endothelial cells was less effective in comparison with its complete deletion, leading to reduction of tumor size via modulation of epithelial apoptosis and angiogenesis-associated proliferation, respectively. Similar results were obtained in a model of colitis-associated carcinogenesis, indicating a mesenchymal-specific role for MK2 also in this model. Our findings demonstrate the central pathogenic role of mesenchymal-specific MK2/Hsp27 axis in tumorigenesis and highlight the value of mesenchymal MK2 inhibition in the treatment of cancer.

Redox-sensitive MAPK and Notch3 regulate fibroblast differentiation and activation: a dual role of ERK1/2

Myofibroblastic transformation, characterized by upregulation of α-smooth muscle actin in response to profibrotic agents such as TGF-β1, is considered as a major event leading to fibrosis. The mechanistic basis linking myofibroblast differentiation to idiopathic pulmonary fibrosis and the disease treatment remain elusive. In this study, we studied roles of MAPK, Notch, and reactive oxygen species (ROS) during the differentiation of IMR-90 lung fibroblasts at basal level and induced by TGF-β1. Our results demonstrated that ROS-dependent activation of p38, JNK1/2 and Notch3 promoted basal and TGF-β1-induced differentiation and expression of extracellular matrix proteins. In stark contrast, ERK1/2 was suppressed by ROS and exhibited an inhibitory effect on the differentiation but showed a weak promotion on the expression of extracellular matrix proteins. TGF-β1-induced Notch3 expression depended on p38 and JNK1/2. Interestingly, Notch3 was also downstream of ERK1/2, suggesting a complex role of ERK1/2 in lung function. Our results suggest a novel ROS-mediated shift of dominance from the inhibitory ERK1/2 to the stimulatory p38, JNK1/2 and Notch3 during the pathological progression of IPF. Thus, targeting ERK1/2 signaling for activation and p38, JNK1/2 and Notch3 for inhibition may be of clinical potential against lung fibrosis.

Loss of MAPK-activated protein kinase 2 enables potent dendritic cell-driven anti-tumour T cell response

Maintaining dendritic cells (DC) in a state of dysfunction represents a key mechanism by which tumour cells evade recognition and elimination by the immune system. Limited knowledge about the intracellular mediators of DC dysfunction restricts success of therapies aimed at reactivating a DC-driven anti-tumour immune response. Using a cell type-specific murine knock-out model, we have identified MAPK-activated protein kinase 2 (MK2) as a major guardian of a suppressive DC phenotype in the melanoma tumour microenvironment. MK2 deletion in CD11c⁺ cells led to an expansion of stimulatory CD103⁺ DCs, mounting a potent CD8⁺ T cell response that resulted in elimination of highly aggressive B16-F10 tumours upon toll-like receptor (TLR) activation in the presence of tumour antigen. Moreover, tumour infiltration by suppressive myeloid cells was strongly diminished. These insights into the regulation of DC functionality reveal MK2 as a targetable pathway for DC-centred immunomodulatory cancer therapies.

MMI-0100 Inhibits Cardiac Fibrosis in a Mouse Model Overexpressing Cardiac Myosin Binding Protein C

Background

Cardiac stress can trigger production of a 40‐kDa peptide fragment derived from the amino terminus of the cardiac myosin‐binding protein C. Cardiac stress, as well as cMyBP‐C mutations, can trigger production of 1 such truncated protein fragment, a 40‐kDa peptide fragment derived from the amino terminus of cMyBP‐C. Genetic expression of this 40‐kDa fragment in mouse cardiomyocytes (cMyBP‐C^40k) leads to cardiac disease, fibrosis, and death within the first year. Fibrosis can occur in many cardiovascular diseases, and mitogen‐activated protein kinase––activated protein kinase‐2 signaling has been implicated in a variety of fibrotic processes. Recent studies demonstrated that mitogen‐activated protein kinase––activated protein kinase‐2 inhibition using the cell‐permeant peptide inhibitor MMI‐0100 is protective in the setting of acute myocardial infarction. We hypothesized that MMI‐0100 might also be protective in a chronic model of fibrosis, produced as a result of cMyBP‐C^40k cardiomyocyte expression.

Methods and Results

Nontransgenic and cMyBP‐C^40k inducible transgenic mice were given MMI‐0100 or PBS daily for 30 weeks. In control groups, long‐term MMI‐0100 was benign, with no measurable effects on cardiac anatomy, function, cell viability, hypertrophy, or probability of survival. In the inducible transgenic group, MMI‐0100 treatment reduced cardiac fibrosis, decreased cardiac hypertrophy, and prolonged survival.

Conclusions

Pharmaceutical inhibition of mitogen‐activated protein kinase––activated protein kinase‐2 signaling via MMI‐0100 treatment is beneficial in the context of fibrotic cMyBPC^40k disease.

FGF2-mediated attenuation of myofibroblast activation is modulated by distinct MAPK signaling pathways in human dermal fibroblasts

BACKGROUND

Previous human and animal studies have demonstrated the ability of exogenously administered basic fibroblast growth factor (FGF2) to act as an antifibrotic agent in the skin. Though the activity of FGF2 as an anti-scarring agent is well-established for fibrotic skin wounds, the mechanisms by which FGF2 exerts these actions are not entirely understood. Canonical FGF2 signaling proceeds in part via FGFR/MAPK pathways in human dermal fibroblasts, and FGF2 has been described to prevent or reverse the fibroblast-to-myofibroblast transition, which is driven by TGFβ signaling and understood to be an important step in the formation of a fibrotic scar in vivo. Thus, we set out to investigate the antagonistic effects of FGF2 on TGFβ signaling as well as the broader effects of MAPK inhibition on the TGFβ-mediated induction of myofibroblast gene expression.

OBJECTIVE

To better understand the effects of FGF2 signaling pathways on myofibroblastic gene expression and cell phenotypes.

METHODS

Human dermal fibroblasts were cultured in vitro in the presence of FGF2, TGFβ, and/or MAPK inhibitors, and the effects of these agents were investigated by molecular biology techniques including qRT-PCR, immunofluorescence, Western blot, and flow cytometry.

RESULTS

FGF2 inhibited TGFβ-mediated fibroblast activation, resulting in more rapidly proliferating, spindle-shaped cells, compared to the more slowly proliferating, flatter TGFβ-treated cells. Treatment with FGF2 also attenuated TGFβ-mediated increase in expression of myofibroblast markers smooth muscle α-actin, calponin, transgelin, connective tissue growth factor, ED-A fibronectin, and collagen I. FGF2-mediated antagonism of the TGFβ-mediated fibroblast-to-myofibroblast transition was reversed by small molecule inhibition of ERK or JNK, and it was potentiated by inhibition of p38. MAPK inhibition was demonstrated to have qualitatively similar effects even in the absence of exogenous FGF2, and small molecule inhibition of p38 MAPK was sufficient to attenuate TGFβ-mediated fibroblast activation.

CONCLUSIONS

Inhibition of select MAPK signaling pathways can reverse or potentiate anti-fibrotic FGF2 effects on human dermal fibroblasts, as well as exert their effects independently of exogenous FGF2 supplementation.

Mechanical signals activate p38 MAPK pathway-dependent reinforcement of actin via mechanosensitive HspB1

Mechanical force induces protein phosphorylations, subcellular redistributions, and actin remodeling. We show that mechanical activation of the p38 MAPK pathway leads to phosphorylation of HspB1 (hsp25/27), which redistributes to cytoskeletal structures, and contributes to the actin cytoskeletal remodeling induced by mechanical stimulation.

Despite the importance of a cell’s ability to sense and respond to mechanical force, the molecular mechanisms by which physical cues are converted to cell-instructive chemical information to influence cell behaviors remain to be elucidated. Exposure of cultured fibroblasts to uniaxial cyclic stretch results in an actin stress fiber reinforcement response that stabilizes the actin cytoskeleton. p38 MAPK signaling is activated in response to stretch, and inhibition of p38 MAPK abrogates stretch-induced cytoskeletal reorganization. Here we show that the small heat shock protein HspB1 (hsp25/27) is phosphorylated in stretch-stimulated mouse fibroblasts via a p38 MAPK-dependent mechanism. Phosphorylated HspB1 is recruited to the actin cytoskeleton, displaying prominent accumulation on actin “comet tails” that emanate from focal adhesions in stretch-stimulated cells. Site-directed mutagenesis to block HspB1 phosphorylation inhibits the protein’s cytoskeletal recruitment in response to mechanical stimulation. HspB1-null cells, generated by CRISPR/Cas9 nuclease genome editing, display an abrogated stretch-stimulated actin reinforcement response and increased cell migration. HspB1 is recruited to sites of increased traction force in cells geometrically constrained on micropatterned substrates. Our findings elucidate a molecular pathway by which a mechanical signal is transduced via activation of p38 MAPK to influence actin remodeling and cell migration via a zyxin-independent process.

TGF-β1 regulates the expression and transcriptional activity of TAZ protein via a Smad3-independent, myocardin-related transcription factor-mediated mechanism

Hippo pathway transcriptional coactivators TAZ and YAP and the TGF-β1 (TGFβ) effector Smad3 regulate a common set of genes, can physically interact, and exhibit multilevel cross-talk regulating cell fate-determining and fibrogenic pathways. However, a key aspect of this cross-talk, TGFβ-mediated regulation of TAZ or YAP expression, remains uncharacterized. Here, we show that TGFβ induces robust TAZ but not YAP protein expression in both mesenchymal and epithelial cells. TAZ levels, and to a lesser extent YAP levels, also increased during experimental kidney fibrosis. Pharmacological or genetic inhibition of Smad3 did not prevent the TGFβ-induced TAZ up-regulation, indicating that this canonical pathway is dispensable. In contrast, inhibition of p38 MAPK, its downstream effector MK2 (e.g. by the clinically approved antifibrotic pirferidone), or Akt suppressed the TGFβ-induced TAZ expression. Moreover, TGFβ elevated TAZ mRNA in a p38-dependent manner. Myocardin-related transcription factor (MRTF) was a central mediator of this effect, as MRTF silencing/inhibition abolished the TGFβ-induced TAZ expression. MRTF overexpression drove the TAZ promoter in a CC(A/T-rich)₆GG (CArG) box-dependent manner and induced TAZ protein expression. TGFβ did not act by promoting nuclear MRTF translocation; instead, it triggered p38- and MK2-mediated, Nox4-promoted MRTF phosphorylation and activation. Functionally, higher TAZ levels increased TAZ/TEAD-dependent transcription and primed cells for enhanced TAZ activity upon a second stimulus (i.e. sphingosine 1-phosphate) that induced nuclear TAZ translocation. In conclusion, our results uncover an important aspect of the cross-talk between TGFβ and Hippo signaling, showing that TGFβ induces TAZ via a Smad3-independent, p38- and MRTF-mediated and yet MRTF translocation-independent mechanism.

SMAD3 expression and regulation of fibroplasia in vocal fold injury

OBJECTIVE

Recent reports highlight the efficacy of small interfering RNA (siRNA) targeting SMAD3 to regulate transforming growth factor β (TGF-β)-mediated fibroplasia in vocal fold fibroblasts. The current study sought to investigate SMAD3 expression during wound healing in vivo and quantify the downstream transcriptional events associated with SMAD3 knockdown in vitro.

STUDY DESIGN

In vivo and in vitro.

METHODS

Unilateral vocal fold injury was created in a rabbit model. SMAD3 and SMAD7 mRNA expression was quantified at 1 hour and 1, 3, 7, 14, 30, 60, and 90 days following injury. In vitro, multi-gene analysis technology was employed in our immortalized human vocal-fold fibroblast cell line following TGF-β1 stimulation ± SMAD3 knockdown across time points.

RESULTS

SMAD3 mRNA expression increased following injury; upregulation was significant at 3 and 7 days compared to control (both P < 0.001). SMAD7 mRNA was also upregulated at 3, 7, and 14 days (P = 0.02, P < 0.001, and P < 0.001, respectively). In vitro, SMAD3 knockdown reduced the expression of multiple profibrotic, TGF-β signaling, and extracellular matrix metabolism genes at 6 and 24 hours following TGF-β1 stimulation.

CONCLUSION

Cumulatively, these data support SMAD3 as a potential master regulator of TGF-β-mediated fibrosis. SMAD3 transcription peaked 7 days following injury. Multi-gene analysis indicated that the therapeutic effectiveness of SMAD3 knockdown may be related to regulation of downstream mediators of fibroplasia and altered TGF-β signaling.

LEVEL OF EVIDENCE

NA. Laryngoscope, 127:E308-E316, 2017.

Pivotal Role of Mitogen-Activated Protein Kinase-Activated Protein Kinase 2 in Inflammatory Pulmonary Diseases

Mitogen-activated protein kinase (MAPK)-activated protein kinase (MK2) is exclusively regulated by p38 MAPK in vivo. Upon activation of p38 MAPK, MK2 binds with p38 MAPK, leading to phosphorylation of TTP, Hsp27, Akt, and Cdc25 that are involved in regulation of various essential cellular functions. In this review, we discuss current knowledge about molecular mechanisms of MK2 in regulation of TNF-α production, NADPH oxidase activation, neutrophil migration, and DNA-damage-induced cell cycle arrest which are involved in the molecular pathogenesis of acute lung injury, pulmonary fibrosis, and non-small-cell lung cancer. Collectively current and emerging new information indicate that developing MK2 inhibitors and blocking MK2-mediated signal pathways are potential therapeutic strategies for treatment of inflammatory and fibrotic lung diseases and lung cancer.

Normal endothelial but impaired arterial development in MAP-Kinase activated protein kinase 2 (MK2) deficient mice

Angiogenesis is a fundamental process during development and disease, and many details of the underlying molecular and cellular mechanisms are incompletely understood. Mitogen-activated protein kinase (MAPK)-activated protein kinase 2 (MK2), a major downstream target of p38 MAPK, has recently been identified as a regulator of Interleukin 1β dependent angiogenesis in vivo, and in vitro data suggest a role of MK2 for VEGF-dependent angiogenic processes in endothelial cells. We thus hypothesized that MK2 plays a role during physiological vascular development in vivo.

Vascular development was investigated in the retina of MK2-deficient mice. Retinal angiogenesis such as sprouting, branching and pruning was unchanged in MK2^-/- mice compared to wildtype littermates. Early arterial development was also comparable between genotypes. However, with further expansion of vascular smooth muscle cells (SMC) during maturation of the arterial network at later time points, the number of arterial branch points was significantly lower in MK2^-/- mice, resulting in a reduced total arterial area in adult mice. Isolated aortic smooth muscle cells from MK2^-/- mice showed a more dedifferentiated phenotype in vitro and downregulation of central SMC marker genes, consistent with the known impaired migration of MK2^-/- SMC.

In conclusion, MK2 is not required for physiological retinal angiogenesis. However, its loss is associated with an altered genetic profile of SMC and an impaired arterial network in adult mice, indicating a distinct and probably cell-specific role of MK2 in arteries.

Stress-dependent phosphorylation of myocardin-related transcription factor A (MRTF-A) by the p38(MAPK)/MK2 axis

Myocardin-related transcription factor A (MRTF-A) is a known actin-regulated transcriptional coactivator of serum response factor (SRF). Stimulation of actin polymerization activates MRTF-A by releasing it from G-actin and thus allowing it to bind to and activate SRF. Here, we compared protein phosphorylation in MK2/3-deficient cells rescued or not by ectopic expression of MK2 in two independent phosphoproteomic approaches using anisomycin-treated MEF cells and LPS-stimulated mouse macrophages, respectively. Two MRTF-A sites, Ser³⁵¹ (corresponding to Ser³¹² in human) and Ser³⁷¹ (Ser³³³ in human), showed significantly stronger phosphorylation (12-fold and 6-fold increase) in the cells expressing MK2. MRTF-A is phosphorylated at these sites in a stress-, but not in a mitogen-induced manner, and p38^MAPK/MK2 catalytic activities are indispensable for this phosphorylation. MK2-mediated phosphorylation of MRTF-A at Ser³¹² and Ser³³³ was further confirmed in an in vitro kinase assay and using the phospho-protein kinase-D (PKD)-consensus motif antibody (anti-LXRXXpS/pT), the p38^MAPK inhibitor BIRB-796, MK2/3-deficient cells and MRTF-A phospho-site mutants. Unexpectedly, dimerization, subcellular localization and translocation, interaction with actin, SRF or SMAD3 and transactivating potential of MRTF-A seem to be unaffected by manipulating the p38^MAPK/MK2-dependent phosphorylations. Hence, MRTF-A is stress-dependently phosphorylated by MK2 at Ser³¹² and Ser³³³ with so far undetected functional and physiological consequences.

Molecular networks underlying myofibroblast fate and fibrosis

Fibrotic remodeling is a hallmark of most forms of cardiovascular disease and a strong prognostic indicator of the advancement towards heart failure. Myofibroblasts, which are a heterogeneous cell-type specialized for extracellular matrix (ECM) secretion and tissue contraction, are the primary effectors of the heart's fibrotic response. This review is focused on defining myofibroblast physiology, its progenitor cell populations, and the core signaling network that orchestrates myofibroblast differentiation as a way of understanding the basic determinants of fibrotic disease in the heart and other tissues.

Class I HDACs specifically regulate E-cadherin expression in human renal epithelial cells

Epithelial‐mesenchymal transition (EMT) and renal fibrosis are closely involved in chronic kidney disease. Inhibition of histone deacetylase (HDAC) has an anti‐fibrotic effect in various diseases. However, the pathophysiological role of isoform‐specific HDACs or class‐selective HDACs in renal fibrosis remains unknown. Here, we investigated EMT markers and extracellular matrix (ECM) proteins in a human proximal tubular cell line (HK‐2) by using HDAC inhibitors or by knockdown of class I HDACs (HDAC1, 2, 3 and 8). Trichostatin A (TSA), MS275, PCI34051 and LMK235 inhibited ECM proteins such as collagen type I or fibronectin in transforming growth factor β1 (TGF‐β1)‐induced HK2 cells. However, restoration of TGF‐β1‐induced E‐cadherin down‐regulation was only seen in HK‐2 cells treated with TSA or MS275, but not with PCI34051, whereas TGF‐β1‐induced N‐cadherin expression was not affected by the inhibitors. ECM protein and EMT marker levels were prevented or restored by small interfering RNA transfection against HDAC8, but not against other class I HDACs (HDAC1, 2 and 3). E‐cadherin regulation is mediated by HDAC8 expression, but not by HDAC8 enzyme activity. Thus, class I HDACs (HDAC1, 2, 3 and 8) play a major role in regulating ECM and EMT, whereas class IIa HDACs (HDAC4 and 5) are less effective.

Antiadhesive effect of polyurethane foam packing in the guinea pig middle ear

CONCLUSIONS

No significant subepithelial healing differences were found between Gelfoam and polyurethane foam (PUF). However, levels of hyperplasia of the mucosal lining and inflammation were lower with PUF packing. PUF packing is not feasible as a middle ear packing material for abraded mucosa. Further studies are required before clinical application.

OBJECTIVE

To date, there have been few reports on the antiadhesive effect of PUF as a middle ear packing. The purpose of this study was to investigate the antiadhesive effect of PUF soaked with saline in an animal model of mucosal trauma.

METHODS

Bioresorbable PUF soaked with saline was placed over abraded mucosa in the experimental group (n = 7), and compressed Gelfoam soaked with saline was placed in the control group (n = 7). After measurement of auditory brainstem responses (ABRs), the animals were sacrificed 3 weeks after packing placement for histological observation.

RESULTS

The ABR results at postoperative week 3 showed no statistically significant difference between the preoperative and post-packing values. An adhesion pattern with subepithelial thickening was observed in the control group. Adhesion was not observed in the experimental group; however, subepithelial fibrous thickening was noted.

Fibroblasts in myocardial infarction: a role in inflammation and repair

Fibroblasts do not only serve as matrix-producing reparative cells, but exhibit a wide range of functions in inflammatory and immune responses, angiogenesis and neoplasia. The adult mammalian myocardium contains abundant fibroblasts enmeshed within the interstitial and perivascular extracellular matrix. The current review manuscript discusses the dynamic phenotypic and functional alterations of cardiac fibroblasts following myocardial infarction. Extensive necrosis of cardiomyocytes in the infarcted heart triggers an intense inflammatory reaction. In the early stages of infarct healing, fibroblasts become pro-inflammatory cells, activating the inflammasome and producing cytokines, chemokines and proteases. Pro-inflammatory cytokines (such as Interleukin-1) delay myofibroblast transformation, until the wound is cleared from dead cells and matrix debris. Resolution of the inflammatory infiltrate is associated with fibroblast migration, proliferation, matrix protein synthesis and myofibroblast conversion. Growth factors and matricellular proteins play an important role in myofibroblast activation during the proliferative phase of healing. Formation of a mature cross-linked scar is associated with clearance of fibroblasts, as poorly-understood inhibitory signals restrain the fibrotic response. However, in the non-infarcted remodeling myocardium, local fibroblasts may remain activated in response to volume and pressure overload and may promote interstitial fibrosis. Considering their abundance, their crucial role in cardiac inflammation and repair, and their involvement in myocardial dysfunction and arrhythmogenesis, cardiac fibroblasts may be key therapeutic targets in cardiac remodeling. This article is part of a Special Issue entitled Myocyte-Fibroblast Signalling in Myocardium.

Myofibroblasts: trust your heart and let fate decide

Cardiac fibrosis is a substantial problem in managing multiple forms of heart disease. Fibrosis results from an unrestrained tissue repair process orchestrated predominantly by the myofibroblast. These are highly specialized cells characterized by their ability to secrete extracellular matrix (ECM) components and remodel tissue due to their contractile properties. This contractile activity of the myofibroblast is ascribed, in part, to the expression of smooth muscle α-actin (αSMA) and other tension-associated structural genes. Myofibroblasts are a newly generated cell type derived largely from residing mesenchymal cells in response to both mechanical and neurohumoral stimuli. Several cytokines, chemokines, and growth factors are induced in the injured heart, and in conjunction with elevated wall tension, specific signaling pathways and downstream effectors are mobilized to initiate myofibroblast differentiation. Here we will review the cell fates that contribute to the myofibroblast as well as nodal molecular signaling effectors that promote their differentiation and activity. We will discuss canonical versus non-canonical transforming growth factor-β (TGFβ), angiotensin II (AngII), endothelin-1 (ET-1), serum response factor (SRF), transient receptor potential (TRP) channels, mitogen-activated protein kinases (MAPKs) and mechanical signaling pathways that are required for myofibroblast transformation and fibrotic disease. This article is part of a Special Issue entitled "Myocyte-Fibroblast Signalling in Myocardium ".

Peptide-mediated inhibition of mitogen-activated protein kinase-activated protein kinase-2 ameliorates bleomycin-induced pulmonary fibrosis

Mitogen-activated protein kinase-activated protein kinase-2 (MAPKAPK2, or MK2), a serine/threonine kinase downstream of p38 mitogen-activated protein kinase, has been implicated in inflammation and fibrosis. Compared with pathologically normal lung tissue, significantly higher concentrations of activated MK2 are evident in lung biopsies of patients with idiopathic pulmonary fibrosis (IPF). Expression is localized to fibroblasts and epithelial cells. In the murine bleomycin model of pulmonary fibrosis, we observed robust, activated MK2 expression on Day 7 (prefibrotic stage) and Day 14 (postfibrotic stage). To determine the effects of MK2 inhibition during the postinflammatory/prefibrotic and postfibrotic stages, C57BL/6 mice received intratracheal bleomycin instillation (0.025 U; Day 0), followed by PBS or the MK2 inhibitor (MK2i; 37.5 μg/kg), administered via either local (nebulized) or systemic (intraperitoneal) routes. MK2i or PBS was dosed daily for 14 days subsequent to bleomycin injury, beginning on either Day 7 or Day 14. Regardless of mode of administration or stage of intervention, MK2i significantly abrogated collagen deposition, myofibroblast differentiation and activated MK2 expression. MK2i also decreased circulating TNF-α and IL-6 concentrations, and modulated the local mRNA expression of profibrotic cytokine il-1β, matrix-related genes col1a2, col3a1, and lox, and transforming growth factor-β family members, including smad3, serpine1 (pai1), and smad6/7. In vitro, MK2i dose-dependently attenuated total MK2, myofibroblast differentiation, the secretion of collagen Type I, fibronectin, and the activation of focal adhesion kinase, whereas activated MK2 was attenuated at optimal doses. The peptide-mediated inhibition of MK2 affects both inflammatory and fibrotic responses, and thus may offer a promising therapeutic target for IPF.

The impact of TGF-β on lung fibrosis: from targeting to biomarkers

Transforming growth factor-β (TGF-β) is extensively involved in the development of fibrosis in different organs. Overproduction or potentiation of its profibrotic effects leads to an aberrant wound healing response during the initiation of fibrotic processes. Idiopathic pulmonary fibrosis (IPF) is a chronic, devastating disease, in which TGF-β\x{2013}induced disturbances of the homeostatic microenvironment are critical to promote cell activation, migration, invasion, or hyperplastic changes. In addition, excess extracellular matrix production contributes in a major way to disease pathogenesis. For this reason, this review will focus on discussing novel data and highlight growing interest in deepening the understanding of the profibrotic role of TGF-β and its direct or indirect targeting for disease modulation.

A TRPC6-dependent pathway for myofibroblast transdifferentiation and wound healing in vivo

After injury or cytokine stimulation, fibroblasts transdifferentiate into myofibroblasts, contractile cells that secrete extracellular matrix for wound healing and tissue remodeling. Here, a genome-wide screen identified TRPC6, a Ca(2+) channel necessary and sufficient for myofibroblast transformation. TRPC6 overexpression fully activated myofibroblast transformation, while fibroblasts lacking Trpc6 were refractory to transforming growth factor β (TGF-β) and angiotensin II-induced transdifferentiation. Trpc6 gene-deleted mice showed impaired dermal and cardiac wound healing after injury. The profibrotic ligands TGF-β and angiotensin II induced TRPC6 expression through p38 mitogen-activated protein kinase (MAPK) serum response factor (SRF) signaling via the TRPC6 promoter. Once induced, TRPC6 activates the Ca(2+)-responsive protein phosphatase calcineurin, which itself induced myofibroblast transdifferentiation. Moreover, inhibition of calcineurin prevented TRPC6-dependent transdifferentiation and dermal wound healing. These results demonstrate an obligate function for TRPC6 and calcineurin in promoting myofibroblast differentiation, suggesting a comprehensive pathway for myofibroblast formation in conjunction with TGF-β, p38 MAPK, and SRF.

Correlation of nuclear factor κB expression with α-SMA and collagen Ⅲ expression in hepatic fibrosis in rats

AIM: To investigate the correlation of expression of nuclear factor κB with that of α-smooth muscle actin (α-SMA) and collagen Ⅲ in hepatic fibrosis in rats.

METHODS: Thirty-two male SD rats of SPF grade were divided randomly into control group and model group. Hepatic fibrosis was induced in rats by injecting carbon tetrachloride. The mRNA and protein expression of NF-κB, α-SMA, and collagen Ⅲ was examined using reverse transcription-polymerase chain reaction (RT-PCR) and immunohistochemistry, respectively. The correlation of NF-κB expression with α-SMA and collagen Ⅲ expression was then analyzed.

RESULTS: NF-κB, α-SMA and collagen Ⅲ were lowly expressed in normal liver tissue. After injection of carbon tetrachloride, the expression of NF-κB, α-SMA and collagen Ⅲ mRNAs and proteins began to increase at week 2 and was significantly higher at weeks 4 and 6 (both P < 0.05), showing a gradually rising trend. There was a positive correlation between the expression of NF-κB and that of α-SMA and collagen Ⅲ (both P < 0.05).

CONCLUSION: NF-κB plays an important role in the pathogenesis of hepatic fibrosis.

Cysteine-rich protein 1 is regulated by transforming growth factor-β1 and expressed in lung fibrosis

Transforming growth factor-β (TGF-β) is a diverse cytokine regulating growth, apoptosis, differentiation, adhesion, invasion, and extracellular matrix production. Dysregulation of TGF-β is associated with fibrotic disorders and epithelial-mesenchymal transition, and has been linked with idiopathic pulmonary fibrosis (IPF). Cysteine-rich protein 1 (CRP1) is a small LIM-domain containing protein involved in smooth muscle differentiation. Here, we show that TGF-β1 increases the expression of CRP1 protein and that CRP1 levels increase in a biphasic fashion. A rapid transient (15-45 min) increase in CRP1 is followed by a subsequent, sustained increase in CRP1 a few hours afterwards that lasts several days. We find that TGF-β1 regulates the expression of CRP1 through Smad and non-conventional p38 MAPK signaling pathways in a transcription-independent manner and that the induction occurs concomitant with an increase in myofibroblast differentiation. Using CRP1 silencing by shRNA, we identify CRP1 as a novel factor mediating cell contractility. Furthermore, we localize CRP1 to fibroblastic foci in IPF lungs and find that CRP1 is significantly more expressed in IPF as compared to control lung tissue. The results show that CRP1 is a novel TGF-β1 regulated protein that is expressed in fibrotic lesions and may be relevant in the IPF disease.

Inhibition of Mitogen Activated Protein Kinase Activated Protein Kinase II with MMI-0100 reduces intimal hyperplasia ex vivo and in vivo

Vein graft intimal hyperplasia remains the leading cause of graft failure, despite many pharmacological approaches that have failed to translate to human therapy. We investigated whether local suppression of inflammation and fibrosis with MMI-0100, a novel peptide inhibitor of Mitogen Activated Protein Kinase Activated Protein Kinase II (MK2), would be an alternative strategy to reduce cell proliferation and intimal hyperplasia. The cell permeant peptide MMI-0100 was synthesized using standard Fmoc chemistry. Pharmacological doses of MMI-0100 induced minimal human endothelial and smooth muscle cell proliferation (30% and 12% respectively). MMI-0100 suppressed IL-6 expression to control levels, without effect on IL-8 expression. MMI-0100 caused sodium nitroprusside induced smooth muscle cell relaxation and inhibited intimal thickening in human saphenous vein rings in a dose-dependent fashion. In a murine aortic bypass model, MMI-0100 reduced intimal thickness in vein grafts by 72%, and there were fewer F4/80-reactive cells in vein grafts treated with MMI-0100. MMI-0100 prevents vein graft intimal thickening ex vivo and in vivo. These results suggest that inhibition of MK2 with the cell-permeant peptide MMI-0100 may be a novel strategy to suppress fibrotic processes such as vein graft disease.

Signaling mechanisms that regulate smooth muscle cell differentiation

Extensive studies over the last 30 years have demonstrated that vascular smooth muscle cell (SMC) differentiation and phenotypic modulation is controlled by a dynamic array of environmental cues. The identification of the signaling mechanisms by which these environmental cues regulate SMC phenotype has been more difficult because of our incomplete knowledge of the transcription mechanisms that regulate SMC-specific gene expression. However, recent advances in this area have provided significant insight, and the goal of this review is to summarize the signaling mechanisms by which extrinsic cues control SMC differentiation.