Periostin modulates myofibroblast differentiation during full-thickness cutaneous wound repair

Periostin accelerates human malignant melanoma progression by modifying the melanoma microenvironment

Given no reliable therapy for advanced malignant melanoma, it is important to elucidate the molecular mechanisms underlying the disease progression. Using a quantitative proteomics approach, the 'isobaric tags for relative and absolute quantitation (iTRAQ)' method, we identified that the extracellular matrix protein, periostin (POSTN), was highly expressed in invasive melanoma compared with normal skin. An immunohistochemical analysis showed that POSTN was expressed in all invasive melanoma (n = 20) and metastatic lymph node (n = 5) tissue samples, notably restricted in their stroma. In terms of the intercellular regulation of POSTN, we found that there was upregulation of POSTN when melanoma cells and normal human dermal fibroblasts (NHDFs) were cocultured, with restricted expression of TGF-β1 and TGF-β3. In a functional analyses, recombinant and NHDF-derived POSTN significantly accelerated melanoma cell proliferation via the integrin/mitogen-activated protein kinase (MAPK) signaling pathway in vitro. The size of implanted melanoma tumors was significantly suppressed in POSTN/Rag2 double knockout mice compared with Rag2 knock-out mice. These results indicate that NHDF-derived POSTN accelerates melanoma progression and might be a promising therapeutic target for malignant melanoma.

The wound healing, chronic fibrosis, and cancer progression triad

For decades tumors have been recognized as "wounds that do not heal." Besides the commonalities that tumors and wounded tissues share, the process of wound healing also portrays similar characteristics with chronic fibrosis. In this review, we suggest a tight interrelationship, which is governed as a concurrence of cellular and microenvironmental reactivity among wound healing, chronic fibrosis, and cancer development/progression (i.e., the WHFC triad). It is clear that the same cell types, as well as soluble and matrix elements that drive wound healing (including regeneration) via distinct signaling pathways, also fuel chronic fibrosis and tumor progression. Hence, here we review the relationship between fibrosis and cancer through the lens of wound healing.

The role of periostin in tissue remodeling across health and disease

Periostin, also termed osteoblast-specific factor 2, is a matricellular protein with known functions in osteology, tissue repair, oncology, cardiovascular and respiratory systems, and in various inflammatory settings. However, most of the research to date has been conducted in divergent and circumscribed areas meaning that the overall understanding of this intriguing molecule remains fragmented. Here, we integrate the available evidence on periostin expression, its normal role in development, and whether it plays a similar function during pathologic repair, regeneration, and disease in order to bring together the different research fields in which periostin investigations are ongoing. In spite of the seemingly disparate roles of periostin in health and disease, tissue remodeling as a response to insult/injury is emerging as a common functional denominator of this matricellular molecule. Periostin is transiently upregulated during cell fate changes, either physiologic or pathologic. Combining observations from various conditions, a common pattern of events can be suggested, including periostin localization during development, insult and injury, epithelial-mesenchymal transition, extracellular matrix restructuring, and remodeling. We propose mesenchymal remodeling as an overarching role for the matricellular protein periostin, across physiology and disease. Periostin may be seen as an important structural mediator, balancing appropriate versus inappropriate tissue adaption in response to insult/injury.

Periostin in allergic inflammation

Periostin, an extracellular matrix protein belonging to the fasciclin family, has been shown to play a critical role in the process of remodeling during tissue/organ development or repair. Periostin functions as a matricellular protein in cell activation by binding to their receptors on cell surface, thereby exerting its biological activities. After we found that periostin is a downstream molecule of interleukin (IL)-4 and IL-13, signature cytokines of type 2 immune responses, we showed that periostin is a component of subepithelial fibrosis in bronchial asthma, the first formal proof that periostin is involved in allergic inflammation. Subsequently, a great deal of evidence has accumulated demonstrating the significance of periostin in allergic inflammation. It is of note that in skin tissues, periostin is critical for amplification and persistence of allergic inflammation by communicating between fibroblasts and keratinocytes. Furthermore, periostin has been applied to development of novel diagnostics or therapeutic agents for allergic diseases. Serum periostin can reflect local production of periostin in inflamed lesions induced by Th2-type immune responses and also can predict the efficacy of Th2 antagonists against bronchial asthma. Blocking the interaction between periostin and its receptor, αv integrin, or down-regulating the periostin expression shows improvement of periostin-induced inflammation in mouse models or in in vitro systems. It is hoped that diagnostics or therapeutic agents targeting periostin will be of practical use in the near future.

Panx1 regulates cellular properties of keratinocytes and dermal fibroblasts in skin development and wound healing

Pannexin1 (Panx1), a channel-forming glycoprotein is expressed in neonatal but not in aged mouse skin. Histological staining of Panx1 knockout (KO) mouse skin revealed a reduction in epidermal and dermal thickness and an increase in hypodermal adipose tissue. Following dorsal skin punch biopsies, mutant mice exhibited a significant delay in wound healing. Scratch wound and proliferation assays revealed that cultured keratinocytes from KO mice were more migratory, whereas dermal fibroblasts were more proliferative compared with controls. In addition, collagen gels populated with fibroblasts from KO mice exhibited significantly reduced contraction, comparable to WT fibroblasts treated with the Panx1 blocker, probenecid. KO fibroblasts did not increase α-smooth muscle actin expression in response to TGF-β, as is the case for differentiating WT myofibroblasts during wound contraction. We conclude that Panx1 controls cellular properties of keratinocytes and dermal fibroblasts during early stages of skin development and modulates wound repair upon injury.

The niche component periostin is produced by cancer-associated fibroblasts, supporting growth of gastric cancer through ERK activation

Overexpression of periostin (POSTN), an extracellular matrix protein, has been observed in several cancers. We investigated the importance of POSTN in gastric cancer. Genome-wide gene expression analysis using publicly available microarray data sets revealed significantly high POSTN expression in cancer tissues from stage II-IV gastric cancer, compared with background normal tissues. The POSTN/vimentin mRNA expression ratio was highly associated with gene groups that regulate the cell cycle and cell proliferation. IHC showed that periglandular POSTN deposition, comprising linear deposition abutting the glandular epithelial cells in normal mucosa, disappeared during intestinal gastric cancer progression. Stromal POSTN deposition was also detected at the invasive front of intestinal-type and diffuse-type cancers. In situ hybridization confirmed POSTN mRNA in cancer-associated fibroblasts, but not in tumor cells themselves. POSTN enhanced the in vitro growth of OCUM-2MLN and OCUM-12 diffuse-type gastric cancer cell lines, accompanied by the activation of ERK. Furthermore, coinoculation of gastric cancer cells with POSTN-expressing NIH3T3 mouse fibroblast cells facilitated tumor formation. The OCUM-2MLN orthotopic inoculation model demonstrated that tumors of the gastric wall in Postn(-/-) mice were significantly smaller than those in wild-type mice. Ki-67 and p-ERK positive rates were both lower in Postn(-/-) mice. These findings suggest that POSTN produced by cancer-associated fibroblasts constitutes a growth-supportive microenvironment for gastric cancer.

Molecular composition and function of integrin-based collagen glues-introducing COLINBRIs

BACKGROUND

Despite detailed knowledge about the structure and signaling properties of individual collagen receptors, much remains to be learned about how these receptors participate in linking cells to fibrillar collagen matrices in tissues. In addition to collagen-binding integrins, a group of proteins with affinity both for fibrillar collagens and integrins link these two protein families together. We have introduced the name COLINBRI (COLlagen INtegrin BRIdging) for this set of molecules. Whereas collagens are the major building blocks in tissues and defects in these structural proteins have severe consequences for tissue integrity, the mild phenotypes of the integrin type of collagen receptors have raised questions about their importance in tissue biology and pathology.

SCOPE OF REVIEW

We will discuss the two types of cell linkages to fibrillar collagen (direct- versus indirect COLINBRI-mediated) and discuss how the parallel existence of direct and indirect linkages to collagens may ensure tissue integrity.

MAJOR CONCLUSIONS

The observed mild phenotypes of mice deficient in collagen-binding integrins and the relatively restricted availability of integrin-binding sequences in mature fibrillar collagen matrices support the existence of indirect collagen-binding mechanisms in parallel with direct collagen binding in vivo.

GENERAL SIGNIFICANCE

A continued focus on understanding the molecular details of cell adhesion mechanisms to collagens will be important and will benefit our understanding of diseases like tissue- and tumor fibrosis where collagen dynamics are disturbed. This article is part of a Special Issue entitled Matrix-mediated cell behaviour and properties.

Periostin responds to mechanical stress and tension by activating the MTOR signaling pathway

Current knowledge about Periostin biology has expanded from its recognized functions in embryogenesis and bone metabolism to its roles in tissue repair and remodeling and its clinical implications in cancer. Emerging evidence suggests that Periostin plays a critical role in the mechanism of wound healing; however, the paracrine effect of Periostin in epithelial cell biology is still poorly understood. We found that epithelial cells are capable of producing endogenous Periostin that, unlike mesenchymal cell, cannot be secreted. Epithelial cells responded to Periostin paracrine stimuli by enhancing cellular migration and proliferation and by activating the mTOR signaling pathway. Interestingly, biomechanical stimulation of epithelial cells, which simulates tension forces that occur during initial steps of tissue healing, induced Periostin production and mTOR activation. The molecular association of Periostin and mTOR signaling was further dissected by administering rapamycin, a selective pharmacological inhibitor of mTOR, and by disruption of Raptor and Rictor scaffold proteins implicated in the regulation of mTORC1 and mTORC2 complex assembly. Both strategies resulted in ablation of Periostin-induced mitogenic and migratory activity. These results indicate that Periostin-induced epithelial migration and proliferation requires mTOR signaling. Collectively, our findings identify Periostin as a mechanical stress responsive molecule that is primarily secreted by fibroblasts during wound healing and expressed endogenously in epithelial cells resulting in the control of cellular physiology through a mechanism mediated by the mTOR signaling cascade.

Periostin promotes the generation of fibrous membranes in proliferative vitreoretinopathy

Proliferative vitreoretinopathy (PVR) is a severe, vision-threatening disorder characterized by the fibrous membrane formation that leads to tractional retinal detachment. There has been no effective therapeutic approach other than vitreoretinal surgery. In this study, DNA microarray analysis of the fibrous membranes revealed significant up-regulation of periostin. We also found increased periostin expression in the vitreous and retinal pigment epithelial (RPE) cells from fibrous membranes of PVR patients. In vitro, periostin increased proliferation, adhesion, migration, and collagen production in RPE cells through integrin αV-mediated FAK and AKT phosphorylation. Periostin blockade suppressed migration and adhesion induced by TGFβ2 and PVR vitreous. In vivo, periostin inhibition had the inhibitory effect on progression of experimental PVR in rabbit eyes without affecting the viability of retinal cells. These results identified periostin as a pivotal molecule for fibrous membrane formation as well as a promising therapeutic target for PVR.

Nifedipine induces periostin expression in gingival fibroblasts through TGF-beta

Gingival enlargement is a fibrotic condition that can arise from systemic administration of the dihydropyridine calcium channel blocker nifedipine. Periostin, a transforming growth factor-beta (TGF-β)-inducible matricellular protein, has been associated with fibrosis in numerous tissues, but its expression has never been examined in nifedipine-influenced gingival enlargement (NIGE). The objective of this study was to assess if periostin up-regulation is associated with NIGE and whether nifedipine induces periostin expression in gingival fibroblasts. In NIGE tissue (n = 6), periostin is overexpressed in the gingival connective tissue compared with healthy control tissue (n = 6). The transcription factor p-SMAD2/3, which is associated with canonical TGF-β signaling, localizes to the nuclei in both HGFs and oral epithelial cells in NIGE tissues, but not in control healthy tissue. In vitro culture of HGFs with 30 and 100 ng/mL of nifedipine significantly increased periostin mRNA and protein levels, which correlated with increased levels of active TGF-β and increased phosphorylation and nuclear localization of SMAD3. Blocking of canonical TGF-β signaling through inhibition of the TGF-β receptor I with SB431542 significantly reduced nifedipine-induced SMAD3 phosphorylation and periostin expression. Our results demonstrate that nifedipine up-regulates periostin in HGFs in a TGF-β-dependent manner.

Interactions of the Extracellular Matrix and Progenitor Cells in Cutaneous Wound Healing

SIGNIFICANCE

Both chronic wounds and excessive scar formation after cutaneous injury create a formidable clinical problem resulting in considerable morbidity and healthcare expenditure. The deposition and remodeling of extracellular matrix (ECM) components are critical processes in cutaneous healing. Understanding the role of the ECM in directing progenitor and reparative cell fate and activities during wound repair is required to improve wound-care strategies.

RECENT ADVANCES

In addition to providing structural integrity, the ECM is recognized to play critical roles in regulating progenitor and reparative cell behaviors such as migration, differentiation, proliferation, and survival. The ECM dictates these activities through its binding of adhesion receptors as well as its ability to regulate growth factor bioavailability and signaling. More recently, a key role for mechanical control of cell fate through interaction with the ECM has emerged.

CRITICAL ISSUES

Despite significant advances in understanding the pathophysiology of cutaneous wound repair, problematic wounds remain a significant healthcare challenge. Regenerative medical strategies that either target endogenous stem cells or utilize applications of exogenous stem cell populations have emerged as promising approaches to pathologic wounds. However, the identification of smart biomaterials and matrices may allow for further optimization of such therapies.

FUTURE DIRECTIONS

An efficient and appropriate healing response in the skin postinjury is regulated by a fine balance of the quantity and quality of ECM proteins. A more complete understanding of ECM regulation of the cell fate and activities during cutaneous wound repair is vital for the development of novel treatment strategies for improvement of cutaneous healing.

Embryonic wound healing: a primer for engineering novel therapies for tissue repair

Scar is the default tissue repair used by the body in response to most injuries-a response that occurs in wounds ranging in seriousness from minor skin cuts to complete severance of the spinal cord. By contrast, before the third trimester of pregnancy embryonic mammals tend to heal without scarring due to a variety of mechanisms and factors that are uniquely in operation during development in utero. The goal of tissue engineering is to develop safe and clinically effective biological substitutes that restore, maintain, or improve tissue function in patients. This review provides a comparative overview of wound healing during development and maturation and seeks to provide a perspective on just how much the embryo may be able teach us in the engineering of new therapies for tissue repair.

Periostin downregulation is an early marker of inhibited neonatal murine lung alveolar septation

BACKGROUND

Extreme preterm birth exposes the saccular lung to multiple teratogens, which ultimately retard alveolar development. Specifically, therapeutic high level oxygen supplementation adversely affects the premature lungs and results in blunted alveolarization. Prolonged hyperoxic lung injury has previously been shown to upregulate the matricellular protein Periostin (Postn) and stimulate ectopic accumulation of alpha smooth muscle actin (αSMA) myofibroblasts. Therapies that promote lung septation are lacking largely due to a lack of reliable early biomarkers of injury. Thus, we determined if Postn expression correlated with the initial appearance of myofibroblasts in the saccular lung and was required for early alveolar development.

METHODS

Lung development in C57BL/6J mice following room-air (RA, 21%-O₂) or continuous hyperoxia (85%-O₂) from birth (P0) through postnatal day P14 was correlated with Postn and αSMA expression. Alveolarization in Postn knockout mice exposed to room-air, 60%-, and 85%-O₂ was also examined.

RESULTS

Postn was widely expressed in distal lung septa through P2 to P4 and peak expression coincided with accumulation of saccular myofibroblasts. Initially, 85%-O₂ prematurely downregulated Postn and αSMA expression and suppressed proliferation before the first evidence of distal lung simplification at P4. By P14, chronic 85%-O₂ resulted in secondary upregulation of Postn and αSMA in blunted septa. Myofibroblast differentiation and alveolar development was unaffected in Postn null mice and acute 85%-O₂ exposure equally inhibited septal formation in Postn null and wild-type littermates.

CONCLUSION

Postn expression is tightly correlated with the presence of αSMA-myofibroblasts and is a novel early biomarker of acutely inhibited alveolar septation during a crucial window of lung development.

Strategies Demonstrating Efficacy in Reducing Wound Contraction In Vivo

SIGNIFICANCE

Scarring continues to present a significant clinical problem. Wound contraction leads to scarring and is mediated by myofibroblasts and contractile forces across the wound bed. Contracture formation can have a significant impact on the quality of life of the patient, particularly where function and appearance are affected.

RECENT ADVANCES

Novel tissue-engineered matrices, cell-based therapies, and medicinal therapeutics have shown significant reduction in wound contraction in in-vivo models, particularly at early time points. These have been accompanied in many cases by reduced numbers of myofibroblasts, and in some by increased angiogenesis and improved neodermal architecture.

CRITICAL ISSUES

There are no animal models that replicate all aspects of wound healing as seen in patients. Therefore, information obtained from in vivo studies should be assessed critically. Additional studies, in particular those that seek to elucidate the mechanisms by which novel therapies reduce contraction, are needed to gain sufficient confidence to move into clinical testing.

FUTURE DIRECTIONS

The use of knockout mouse models in particular has generated significant advances in knowledge of the mechanisms behind myofibroblast conversion and other factors involved in generating tension across the wound. Medicinal therapeutics and tissue-engineering approaches that seek to disrupt/alter these pathways hold much promise for future development and translation to clinical practice.

Exploiting PI3K/mTOR signaling to accelerate epithelial wound healing

The molecular circuitries controlling the process of skin wound healing have gained new significant insights in recent years. This knowledge is built on landmark studies on skin embryogenesis, maturation, and differentiation. Furthermore, the identification, characterization, and elucidation of the biological roles of adult skin epithelial stem cells and their influence in tissue homeostasis have provided the foundation for the overall understanding of the process of skin wound healing and tissue repair. Among numerous signaling pathways associated with epithelial functions, the PI3K/Akt/mTOR signaling route has gained substantial attention with the generation of animal models capable of dissecting individual components of the pathway, thereby providing a novel insight into the molecular framework underlying skin homeostasis and tissue regeneration. In this review, we focus on recent findings regarding the mechanisms involved in wound healing associated with the upregulation of the activity of the PI3K/Akt/mTOR circuitry. This review highlights critical findings on the molecular mechanisms controlling the activation of mTOR, a downstream component of the PI3K-PTEN pathway, which is directly involved in epithelial migration and proliferation. We discuss how this emerging information can be exploited for the development of novel pharmacological intervention strategies to accelerate the healing of critical size wounds.

Tissue remodeling in eosinophilic esophagitis

Eosinophilic esophagitis (EoE) is a recently recognized, immune-mediated disease characterized clinically by symptoms of esophageal dysfunction and histologically by eosinophil-predominant inflammation. The chronic esophageal eosinophilia of EoE is associated with tissue remodeling that includes epithelial hyperplasia, subepithelial fibrosis, and hypertrophy of esophageal smooth muscle. This remodeling causes the esophageal rings and strictures that frequently complicate EoE and underlies the mucosal fragility that predisposes to painful mucosal tears in the EoE esophagus. The pathogenesis of tissue remodeling in EoE is not completely understood, but emerging studies suggest that secretory products of eosinophils and mast cells, as well as cytokines produced by other inflammatory cells, epithelial cells, and stromal cells in the esophagus, all contribute to the process. Interleukin (IL)-4 and IL-13, Th2 cytokines overproduced in allergic disorders, have direct profibrotic and remodeling effects in EoE. The EoE esophagus exhibits increased expression of transforming growth factor (TGF)-β1, which is a potent activator of fibroblasts and a strong inducer of epithelial-mesenchymal transition. In addition, IL-4, IL-13, and TGF-β all have a role in regulating periostin, an extracellular matrix protein that might influence remodeling by acting as a ligand for integrins, by its effects on eosinophils or by activating fibrogenic genes in the esophagus. Presently, few treatments have been shown to affect the tissue remodeling that causes EoE complications. This report reviews the potential roles of fibroblasts, eosinophils, mast cells, and profibrotic cytokines in esophageal remodeling in EoE and identifies potential targets for future therapies that might prevent EoE complications.

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.

Pharmacological blockade of adenosine A2A receptors diminishes scarring

Adenosine A2A receptor (A2AR) stimulation promotes wound healing and is required for the development of fibrosis in murine models of scleroderma and cirrhosis. Nonetheless, the role of A2AR in the formation of scars following skin trauma has not been explored. Here, we examined the effect of pharmacological blockade of A2AR, with the selective adenosine A2AR-antagonist ZM241385 (2.5 mg/ml), in a murine model of scarring that mimics human scarring. We found that application of the selective adenosine A2AR antagonist ZM241385 decreased scar size and enhanced the tensile strength of the scar. Within the scar itself, collagen alignment and composition (marked reduction in collagen 3), but not periostin, biglycan, or fibronectin accumulation, was improved by application of ZM241385. Moreover, A2AR blockade reduced the number of myofibroblasts and angiogenesis but not macrophage infiltration in the scar. Taken together, our work strongly suggests that pharmacological A2AR blockade can be used to diminish scarring while improving the collagen composition and tensile strength of the healed wound.

Functional significance of periostin in excisional skin repair: is the devil in the detail?

In the past year, three papers have been published exploring the role of the matricellular protein periostin in excisional skin repair. These papers all show a delay in wound closure and the kinetics of this delay are strikingly similar across the three reports. The similarities between these papers end, however, when each investigates the mechanism through which periostin influences skin repair. Three proposed mechanisms have been identified: (1) myofibroblast differentiation, (2) keratinocyte proliferation and (3) fibroblast proliferation and migration. The aim of this commentary is to compare and contrast the three studies performed to date in an attempt to decipher the role of periostin in the repair of full-thickness skin wounds.

Periostin promotes chronic allergic inflammation in response to Th2 cytokines

Allergic inflammation triggered by exposure of an allergen frequently leads to the onset of chronic inflammatory diseases such as atopic dermatitis (AD) and bronchial asthma. The mechanisms underlying chronicity in allergic inflammation remain unresolved. Periostin, a recently characterized matricellular protein, interacts with several cell surface integrin molecules, providing signals for tissue development and remodeling. Here we show that periostin is a critical mediator for the amplification and persistence of allergic inflammation using a mouse model of skin inflammation. Th2 cytokines IL-4 and IL-13 stimulated fibroblasts to produce periostin, which interacted with αv integrin, a functional periostin receptor on keratinocytes, inducing production of proinflammatory cytokines, which consequently accelerated Th2-type immune responses. Accordingly, inhibition of periostin or αv integrin prevented the development or progression of allergen-induced skin inflammation. Thus, periostin sets up a vicious circle that links Th2-type immune responses to keratinocyte activation and plays a critical role in the amplification and chronicity of allergic skin inflammation.