Identification and characterization of a novel protein, periostin, with restricted expression to periosteum and periodontal ligament and increased expression by transforming growth factor beta

Prognostic significance of periostin in colorectal cancer

Accumulating evidence suggests that periostin is frequently upregulated in tissue injury, inflammation, fibrosis and tumor progression. Periostin expression in cancer cells can promote metastatic potential of colorectal cancer (CRC) via activating PI3K/Akt signaling pathway. Moreover, periostin is observed mainly in tumor stroma and cytoplasm of cancer cells, which may facilitate aggressiveness of CRC. In this review, we summarize information regarding periostin to emphasize its role as a prognostic marker of CRC.

The attempt of spontaneous repair of rotator cuff tear: The role of periostin

The development of a periostin-rich microenvironment in areas associated with insult, orchestrating pathways of repair and rebuilding, is documented. Literature lacks information regarding the presence of periostin in the context of rotator cuff tear (RCT). 55 consecutive patients with RCT were enrolled. Immunohistochemical periostin detection was performed on tissue samples excised from tear margins. Our study documented the presence of periostin in the margins of RCT. It is plausible that, when a tear occurs, multiple stimuli, both mechanical and inflammatory, lead to the development of a periostin-rich microenvironment as an attempt to tendon healing.

Distinct expression pattern of periostin splice variants in chondrocytes and ligament progenitor cells

Periostin (POSTN), a secretory matricellular matrix protein, plays a multitude of biologic functions. Various splice variants of POSTN have been described; however, their expression pattern and functional implications are not completely understood. This study was undertaken to decipher the differential expression pattern of POSTN and its splice variants in various tissues and cell types. We show that POSTN was more highly expressed in anterior cruciate ligament (ACL) remnants compared with articular cartilage at the cellular and tissue level. Isoforms 1 and 8 were highly expressed only in articular chondrocytes, suggesting their splice-specific regulation in chondrocytes. To discern the role of total POSTN and full-length human POSTN isoform 1 (hPOSTN-001), we stably transfected human chondrosarcoma 1 (hCh-1) cell line with hPOSTN-001 using a pcDNA3.1-hPOSTN-001 construct. RNA-sequencing analysis of hCh-1 cells identified differentially expressed genes with a known role in chondrocyte function and osteoarthritis. Similar expression of a subset of candidate genes was revealed in ACL progenitor cells and chondrocytes as well as in ACL progenitor cells in which POSTN activity was altered by overexpression and by small interfering RNA gene knockdown. Cells expressing total POSTN, not isoform 1, exhibited increased cell adhesion potential. These findings suggest an important role for POSTN in the knee.-Cai, L., Brophy, R. H., Tycksen, E. D., Duan, X., Nunley, R. M., Rai, M. F. Distinct expression pattern of periostin splice variants in chondrocytes and ligament progenitor cells.

Self-Assembly of an Organized Cementum-Periodontal Ligament-Like Complex Using Scaffold-Free Tissue Engineering

A major challenge in regenerating periodontal tissues is emulating its complex structure containing both mineralized and soft tissues. In this study, scaffold-free tissue constructs engineered using periodontal ligament cells (PDLCs), which contain a population of adult stem/progenitor cells, self-assembled into an organized multi-tissue structure comprising a mineralized cementum-like core enclosed within a periodontal ligament (PDL)-like tissue. Scaffold-free engineered constructs were formed by culturing human PDLCs to form a cell sheet on six-well dishes containing two minutien pins placed 7 mm apart. The cell sheet was contracted by the cells to roll into the pins forming a cylindrical construct anchored on either end by the pins. These tissues were approximately 1 mm in diameter and 7 mm long and contained only the cells and their endogenous matrix. These scaffold-free engineered constructs exhibited two structurally distinct tissues, one in the center of the construct and another on the periphery. The center tissue was mineralized and expressed alkaline phosphatase and bone sialoprotein, similar to cementum. The peripheral tissue was not calcified and expressed periodontal ligament-associated protein-1 and periostin, which is characteristic of the periodontal ligament. This tissue organization was seen after in vitro culture and maintained in vivo following subcutaneous implantation in immunocompromised mice. These data demonstrate that scaffold-free tissue engineering facilitates PDLCs to self-assemble into an organized cementum-PDL-like complex. These engineered tissues could be used as implantable grafts to regenerate damaged periodontal tissues or as model systems to study PDLC biology and mechanisms driving organized tissue assembly within the periodontium.

Periostin and Inflammatory Disease: Implications for Chronic Rhinosinusitis

OBJECTIVE

To provide a comprehensive overview of the emerging role of periostin, an extracellular matrix protein, as a key component in the development, diagnosis, and treatment of patients with chronic rhinosinusitis.

DATA SOURCES

Medline database.

REVIEW METHODS

A state of the art review was performed targeting English-language studies investigating the role of periostin in cardiopulmonary, neoplastic, and inflammatory diseases, with emphasis on recent advances in the study of periostin in chronic rhinosinusitis.

CONCLUSIONS

Periostin has emerged as a novel biomarker and therapeutic target for numerous human pathologies, including cardiac, pulmonary, and neoplastic disease. The upregulation of periostin in chronic rhinosinusitis suggests the potential for similar roles among patients with sinonasal disease.

IMPLICATIONS FOR PRACTICE

Chronic rhinosinusitis is a widespread disease with major clinical and societal impact. A critical limitation in the current treatment of patients with chronic rhinosinusitis is the absence of clinically relevant biomarkers to guide diagnosis and treatment selection. A review of the literature supports a likely role of periostin as a biomarker of chronic rhinosinusitis, as well as a novel therapeutic target in the future treatment of patients with sinonasal disease.

Roles of Cyclic AMP Response Element Binding Activation in the ERK1/2 and p38 MAPK Signalling Pathway in Central Nervous System, Cardiovascular System, Osteoclast Differentiation and Mucin and Cytokine Production

There are many downstream targets of mitogen-activated protein kinase (MAPK) signalling that are involved in neuronal development, cellular differentiation, cell migration, cancer, cardiovascular dysfunction and inflammation via their functions in promoting apoptosis and cell motility and regulating various cytokines. It has been reported that cyclic AMP response element-binding protein (CREB) is phosphorylated and activated by cyclic AMP signalling and calcium/calmodulin kinase. Recent evidence also points to CREB phosphorylation by the MAPK signalling pathway. However, the specific roles of CREB phosphorylation in MAPK signalling have not yet been reviewed in detail. Here, we describe the recent advances in the study of this MAPK-CREB signalling axis in human diseases. Overall, the crosstalk between extracellular signal-related kinase (ERK) 1/2 and p38 MAPK signalling has been shown to regulate various physiological functions, including central nervous system, cardiac fibrosis, alcoholic cardiac fibrosis, osteoclast differentiation, mucin production in the airway, vascular smooth muscle cell migration, steroidogenesis and asthmatic inflammation. In this review, we focus on ERK1/2 and/or p38 MAPK-dependent CREB activation associated with various diseases to provide insights for basic and clinical researchers.

The role of sclerostin and dickkopf-1 in oral tissues - A review from the perspective of the dental disciplines

Wnt signaling is of high relevance in the development, homeostasis, and regeneration of oral tissues. Therefore, Wnt signaling is considered to be a potential target for therapeutic strategies. The action of Wnt is tightly controlled by the inhibitors sclerostin (SOST) and Dickkopf (DKK)-1. Given the impact of SOST and DKK-1 in hard tissue formation, related diseases and healing, it is of high relevance to understand their role in oral tissues. The clinical relevance of this knowledge is further underlined by systemic and local approaches which are currently in development for treating a variety of diseases such as osteoporosis and inflammatory hard tissue resorption. In this narrative review, we summarize the current knowledge and understanding on the Wnt signaling inhibitors SOST and DKK-1, and their role in physiology, pathology, and regeneration in oral tissues. We present this role from the perspective of the different specialties in dentistry, including endodontics, orthodontics, periodontics, and oral surgery.

The Structure of the Periostin Gene, Its Transcriptional Control and Alternative Splicing, and Protein Expression

Although many studies have described the role of periostin in various diseases, the functions of periostin derived from alternative splicing and proteinase cleavage at its C-terminus remain unknown. Further experiments investigating the periostin structures that are relevant to diseases are essential for an in-depth understanding of their functions, which would accelerate their clinical applications by establishing new approaches for curing intractable diseases. Furthermore, this understanding would enhance our knowledge of novel functions of periostin related to stemness and response to mechanical stress .

Periostin in Bone Biology

Periostin is specifically expressed in periosteum that functions in bone modeling and remodeling and bone repair, and is sensitive to mechanical stress. Thus periostin has been expected for controlling these crucial systems in bone. The results from periostin deficient mice demonstrate that periostin acts on bone remodeling though detailed mechanisms are unknown. Recent findings have revealed that periostin is essential for bone repair. In this chapter, I introduce expression and function of periostin in bone.

Periostin mediates epithelial-mesenchymal transition through the MAPK/ERK pathway in hepatoblastoma

Objective

The aim of the present study was to analyze the prognostic factors in patients with hepatoblastoma (HB) in our single center and to evaluate periostin (POSTN) expression in HB and its association with clinicopathological variables. In addition, the underlying mechanism of how POSTN promotes HB progression was discussed.

Methods

POSTN expression was investigated in HB tumors by immunohistochemistry (IHC), immunofluorescence (IF) and Western blot (WB). The association among POSTN expression, clinicopathological features and overall survival (OS) was also evaluated. The migration and adhesion ability of HB cells were measured using chemotaxis and cell-matrix adhesion assays, respectively. Epithelial-mesenchymal transition (EMT)-associated markers and activation of the ERK pathway were detected by WB.

Results

HB patients had poor prognosis which displayed lymph node metastasis, vascular invasion, POSTN and vimentin expression. POSTN expression was also associated with lymph node metastasis. Furthermore, overexpressed POSTN promoted migration and the adhesive ability of HB cells in vitro. In addition, we demonstrated that POSTN activated the MAPK/ERK pathway, upregulated the expression of Snail and decreased the expression of OVOL2. Finally, POSTN promoted the expression of EMT-associated markers.

Conclusions

POSTN might modulate EMT via the ERK signaling pathway, thereby promoting cellular migration and invasion. Our study also suggests that POSTN may serve as a therapeutic biomarker in HB patients.

Functions of Periostin in Dental Tissues and Its Role in Periodontal Tissue Regeneration

The goal of periodontal regeneration therapy is to reliably restore teeth's supporting periodontal tissue, while aiding the formation of new connective tissue attached to the periodontal ligament (PDL) fibers and new alveolar bone. Periostin is a matricellular protein, primarily expressed in the periosteum and PDL of adult mice. Its biological functions have been extensively studied in the fields of cardiovascular physiology and oncology. Despite being initially identified in bone and dental tissue, the function of Periostin in PDL and the pathophysiology associated with alveolar bone are scarcely studied. Recently, several studies have suggested that Periostin may be an important regulator of periodontal tissue formation. By promoting collagen fibrillogenesis and the migration of fibroblasts and osteoblasts, Periostin might play a key role in the regeneration of PDL and alveolar bone after periodontal surgery. In this chapter, the implications of Periostin in periodontal tissue biology and its potential use in periodontal tissue regeneration are reviewed.

Periostin and Human Teeth

Periostin is a secreted matricellular protein that primarily interacts with type I collagen and fibronectin extracellular matrix proteins, and is widely distributed in tissues rich in collagen-rich connective tissues, including the periodontal ligament. Its expression in these tissues is especially regulated by mechanical load. While the expression and regulation of periostin in the teeth of murine models and cell lines is well known, its presence in human teeth is poorly documented. Here we update and summarize the available data on the distribution of periostin in the human periodontal ligament, gingiva and dental pulp.

Periostin in the Kidney

Periostin is a matricellular protein that is expressed in several tissues during embryonic development; however, its expression in adults is mostly restricted to collagen-rich connective tissues. Periostin is expressed only briefly during kidney development, but it is not normally detected in the adult kidney. Recent evidence has revealed that periostin is aberrantly expressed in several forms of chronic kidney disease (CKD), and that its expression correlates with the degree of interstitial fibrosis and the decline in renal function. Polycystic kidney disease (PKD), a genetic disorder, is characterized by the formation of numerous fluid-filled cysts in the kidneys. Periostin is secreted by the cyst epithelial cells and accumulates within the extracellular matrix adjacent to the cysts. In PKD mice, periostin overexpression accelerates cyst growth and contributes to structural changes in the kidneys, including interstitial fibrosis. Recent evidence suggests that periostin is a tissue repair molecule; however, its role in repair following acute kidney injury has not been investigated. It is thought that persistent expression of this protein in CKD contributes importantly to tubulointerstitial fibrosis and the progressive decline in renal function. Future studies to define the diverse actions of periostin during kidney injury may lead to effective therapies to slow PKD progression and possibly prevent the development of CKD. This chapter reviews the current literature on the expression of periostin in PKD and other forms of CKD, mechanisms for periostin stimulated cyst growth, its potential role in extracellular matrix production and renal fibrosis, and the evidence for periostin as a novel biomarker for kidney disease.

Practical Application of Periostin as a Biomarker for Pathological Conditions

In physiological condition, periostin is expressed in limited tissues such as periodontal ligament, periosteum, and heart valves. Periostin protein is mainly localized on extracellular collagen bundles and in matricellular space. On the other hand, in pathological condition, expression of periostin is induced in disordered tissues of human patients. In tumor development and progression, periostin is elevated mainly in its microenvironment and stromal tissue rich in extracellular matrix. Tumor stromal fibroblasts highly express periostin and organize the tumor-surrounding extracellular matrix architecture. In fibrosis in lung, liver, and kidney, proliferating activated fibroblasts express periostin and replace normal functional tissues with dense connective tissues. In inflammation and allergy, inflammatory cytokines such as IL-4 and IL-13 induce expression of periostin that plays important roles in pathogenesis of these diseases. The elevated levels of periostin in human patients could be detected not only in tissue biopsy samples but also in peripheral bloods using specific antibodies against periostin, because periostin secreted from the disordered tissues is transported into blood vessels and circulates in the cardiovascular system. In this chapter, I introduce the elevated expression of periostin in pathological conditions, and discuss how periostin could be utilized as a biomarker in disease diagnosis.

Regulatory mechanisms of sclerostin expression during bone remodeling

Osteocytes are embedded in bone matrices and are connected to each other to respond to mechanical loading on bone. Recent studies have demonstrated the roles of mechanical loading in bone accrual. Bone responds to mechanical loading by decreasing the expression of sclerostin, an inhibitor of Wnt/β-catenin signals, in osteocytes. This increases bone mass because the activation of Wnt/β-catenin signals in bone microenvironments promotes bone formation and suppresses bone resorption. Thus, in recent years, sclerostin have attracted increasing attention in bone metabolism. However, the regulatory mechanism of sclerostin expression during bone remodeling has not been fully elucidated. In this review, we summarized the regulation of bone formation and resorption by Wnt signals, a Wnt/β-catenin signal inhibitor sclerostin, and molecular mechanisms by which the expression of sclerostin is suppressed by mechanical loading and parathyroid hormone. We also discuss a possibility that osteoclasts suppress the expression of sclerostin during bone remodeling, which in turn, promote bone formation. The effectiveness of an anti-sclerostin antibody with anti-dickkopf-1 antibody for increasing bone mass was discussed.

Naming, History, Future

The history of periostin and the mechanism of periostin in fibrillogenesis are described. Periostin is a matricellular protein and involved in incurable diseases.

Periostin in Bone Regeneration

Bone regeneration is an efficient regenerative process depending on the recruitment and activation of skeletal stem cells that allow cartilage and bone formation leading to fracture consolidation. Periosteum, the tissue located at the outer surface of bone is now recognized as an essential player in the bone repair process and contains skeletal stem cells with high regenerative potential. The matrix composition of the periosteum defines its roles in bone growth, in cortical bone modeling and remodeling in response to mechanical strain, and in bone repair. Periostin is a key extracellular matrix component of the periosteum involved in periosteum functions. In this chapter, we summarize the current knowledge on the bone regeneration process, the role of the periosteum and skeletal stem cells, and Periostin functions in this context. The matricellular protein Periostin has several roles through all stages of bone repair: in the early days of repair during the initial activation of stem cells within periosteum, in the active phase of cartilage and bone deposition in the facture callus, and in the final phase of bone bridging and reconstitution of the stem cell pool within periosteum.

New Therapies for the Treatment of Renal Fibrosis

Renal fibrosis is the common pathway for progression of chronic kidney disease (CKD) to end stage of renal disease. It is now widely accepted that the degree of renal fibrosis correlates with kidney function and CKD stages. The key cellular basis of renal fibrosis includes activation of myofibroblasts, excessive production of extracellular matrix components, and infiltration of inflammatory cells. Many cellular mechanisms responsible for renal fibrosis have been identified, and some antifibrotic agents show a greater promise in slowing down and even reversing fibrosis in animal models; however, translating basic findings into effective antifibrotic therapies in human has been limited. In this chapter, we will discuss the effects and mechanisms of some novel antifibrotic agents in both preclinical studies and clinical trials.

Periostin Mediates Right Ventricular Failure through Induction of Inducible Nitric Oxide Synthase Expression in Right Ventricular Fibroblasts from Monocrotaline-Induced Pulmonary Arterial Hypertensive Rats

Pulmonary arterial hypertension (PAH) leads to lethal right ventricular failure (RVF). Periostin (POSTN) mRNA expression is increased in right ventricles (RVs) of monocrotaline (MCT)-induced PAH model rats. However, the pathophysiological role of POSTN in RVF has not been clarified. We investigated the effects of POSTN on inducible nitric oxide (NO) synthase (iNOS) expression and NO production, which causes cardiac dysfunction, in right ventricular fibroblasts (RVFbs). Male Wistar rats were intraperitoneally injected with MCT (60 mg/kg) or saline. Three weeks after injection, RVFbs were isolated from RVs of MCT- or saline-injected rats (MCT-RVFb or CONT-RVFb). In MCT-RVFb, iNOS expression and phosphorylation of extracellular signal-regulated kinase 1/2 (ERK1/2), c-Jun N-terminal kinase (JNK) and nuclear factor-kappa B (NF-κB) were higher than those in CONT-RVFb. Recombinant POSTN increased iNOS expression and NO production, which were prevented by a pharmacological inhibition of ERK1/2, JNK or NF-κB in RVFbs isolated from normal rats. Culture medium of POSTN-stimulated RVFbs suppressed Ca²⁺ inflow through l-type Ca²⁺ channel (LTCC) in H9c2 cardiomyoblasts. We demonstrated that POSTN enhances iNOS expression and subsequent NO production via ERK1/2, JNK, and NF-κB signaling pathways in RVFbs. POSTN might mediate RVF through the suppression of LTCC activity of cardiomyocytes by producing NO from RVFbs in PAH model rats.

Gelatin-assisted conglutination of aligned polycaprolactone nanofilms into a multilayered fibre-guiding scaffold for periodontal ligament regeneration

The repair or regeneration of well-aligned periodontal ligaments (PDL) remains a challenging clinical task in reconstructive surgeries and regenerative medicine. Topographical cell guidance has been utilized as a tissue-engineering bionic technique and facilitates the geometric design of composite materials. In this investigation, we manufactured multilayered scaffolds by cementing aligned polycaprolactone (PCL) electrospun films together using gelatin; the fibre-guiding scaffold mimicked the natural structure of periodontal ligaments and was aimed at promoting the growth of functionally oriented ligamentous fibres in vivo. Experiments in vitro demonstrated that this scaffold could provide good attachment and tissue-mimicking microenvironments for "seeding cells", that is, human periodontal ligament mesenchyme cells (PDLSCs). Histological and immunofluorescence results indicated that a three-dimensional aligned construct could significantly enhance the angulation of new-born PDL-like tissue and facilitate collagen formation and maturation at periodontal fenestration defects compared to an amorphous PCL embedded scaffold. Multilayered fibre-guiding scaffold made of PCL and gelatin was demonstrated to be applicable for oriented neogenesis of periodontium, and it may represent an important potential application for dental stem cell delivery for periodontal regenerative medicine.

Periostin induces kidney fibrosis after acute kidney injury via the p38 MAPK pathway

Periostin plays a crucial role in fibrosis, and acute kidney injury results in a high risk of progression to chronic kidney disease. Therefore, we hypothesized that periostin was involved in the progression of acute kidney injury to kidney fibrosis. Unilateral ischemia-reperfusion injury (UIRI) was induced in 7- to 8-wk-old male wild-type and periostin-null mice, and the animals were observed for 6 wk. In vitro, human kidney-2 cells and primary-cultured human tubular epithelial cells were incubated under hypoxic conditions (5% O₂, 5% CO₂, and 90% N₂) for 5 days. The cells were also cultured with recombinant periostin (rPeriostin) and a p38 mitogen-activated protein kinase (MAPK) inhibitor in a hypoxic incubator. At 6 wk after UIRI, interstitial fibrosis/tubular atrophy was significantly alleviated in periostin-null mice compared with wild-type controls. In addition, periostin-null mice had attenuated expression of fibrosis/apoptosis markers and phosphorylated-p38 MAPK compared with wild-type controls. In vitro, hypoxic injury increased the expression of fibrosis markers, periostin, and phosphorylated-p38 MAPK, which was comparable to or substantially greater than their expression levels following treatment with recombinant transforming growth factor-β1 under normoxic conditions. Furthermore, rPeriostin treatment under hypoxic conditions enhanced fibrosis/apoptosis markers and phosphorylated-p38 MAPK. In contrast, p38 MAPK inhibition ameliorated hypoxia-induced fibrosis, and the addition of the p38 MAPK inhibitor to rPeriostin significantly ameliorated the changes induced by rPeriostin. In conclusion, periostin promotes kidney fibrosis via the p38 MAPK pathway following acute kidney injury triggered by a hypoxic or ischemic insult. Periostin ablation may protect against chronic kidney disease progression.

[Progress relationship between periostin and periodontitis]

Periostin, a kind of matricellular protein highly expressed in periodontal ligament and periosteum, is an important regulator of the integrity of periodontal ligament and periodontitis processes. Periostin has been shown to play a positive role in the recovery of periodontitis. This paper reviews relevant literature about the role of periostin in periodontal tissue and periodontitis.

Periostin overexpression in collecting ducts accelerates renal cyst growth and fibrosis in polycystic kidney disease

In polycystic kidney disease (PKD), persistent activation of cell proliferation and matrix production contributes to cyst growth and fibrosis, leading to progressive deterioration of renal function. Previously, we showed that periostin, a matricellular protein involved in tissue repair, is overexpressed by cystic epithelial cells of PKD kidneys. Periostin binds α_Vβ₃-integrins and activates integrin-linked kinase (ILK), leading to Akt/mammalian target of rapamycin (mTOR)-mediated proliferation of human PKD cells. By contrast, periostin does not stimulate the proliferation of normal human kidney cells. This difference in the response to periostin is due to elevated expression of α_Vβ₃-integrins by cystic cells. To determine whether periostin accelerates cyst growth and fibrosis, we generated mice with conditional overexpression of periostin in the collecting ducts (CDs). Ectopic CD expression of periostin was not sufficient to induce cyst formation or fibrosis in wild-type mice. However, periostin overexpression in pcy/pcy ( pcy) kidneys significantly increased mTOR activity, cell proliferation, cyst growth, and interstitial fibrosis; and accelerated the decline in renal function. Moreover, CD-specific overexpression of periostin caused a decrease in the survival of pcy mice. These pathological changes were accompanied by increased renal expression of vimentin, α-smooth muscle actin, and type I collagen. We also found that periostin increased gene expression of pathways involved in repair, including integrin and growth factor signaling and ECM production, and it stimulated focal adhesion kinase, Rho GTPase, cytoskeletal reorganization, and migration of PKD cells. These results suggest that periostin stimulates signaling pathways involved in an abnormal tissue repair process that contributes to cyst growth and fibrosis in PKD.

Schwann cell-derived periostin promotes autoimmune peripheral polyneuropathy via macrophage recruitment

Chronic inflammatory demyelinating polyneuropathy (CIDP) and Guillain-Barre syndrome (GBS) are inflammatory neuropathies that affect humans and are characterized by peripheral nerve myelin destruction and macrophage-containing immune infiltrates. In contrast to the traditional view that the peripheral nerve is simply the target of autoimmunity, we report here that peripheral nerve Schwann cells exacerbate the autoimmune process through extracellular matrix (ECM) protein induction. In a spontaneous autoimmune peripheral polyneuropathy (SAPP) mouse model of inflammatory neuropathy and CIDP nerve biopsies, the ECM protein periostin (POSTN) was upregulated in affected sciatic nerves and was primarily expressed by Schwann cells. Postn deficiency delayed the onset and reduced the extent of neuropathy, as well as decreased the number of macrophages infiltrating the sciatic nerve. In an in vitro assay, POSTN promoted macrophage chemotaxis in an integrin-AM (ITGAM) and ITGAV-dependent manner. The PNS-infiltrating macrophages in SAPP-affected nerves were pathogenic, since depletion of macrophages protected against the development of neuropathy. Our findings show that Schwann cells promote macrophage infiltration by upregulating Postn and suggest that POSTN is a novel target for the treatment of macrophage-associated inflammatory neuropathies.

Periostin and Dipeptidyl Peptidase-4: Potential Biomarkers of Interleukin 13 Pathway Activation in Asthma and Allergy

Periostin and dipeptidyl peptidase-4 (DPP-4) are proteins induced by type 2 cytokines interleukin (IL)-4 and IL-13 and show increased expression in asthma and diseases with type 2 inflammation, including atopic dermatitis and chronic rhinosinusitis. Both proteins can also be induced by other stimuli, such as profibrotic factors, which may confound their specificity as biomarkers of IL-13 pathway activation and type 2-driven disease. DPP-4 is important in glucose metabolism; therefore, serum concentrations may be confounded by the presence of concomitant metabolic disease. This review evaluates the potential of these biomarkers for anti-IL-13-directed therapy in asthma and diseases with type 2 inflammation.

Periostin expression in neoplastic and non-neoplastic diseases of bone and joint

BACKGROUND

Periostin is a matricellular protein that is expressed in bone and joint tissues. To determine the expression of periostin in primary bone tumours and to assess whether it plays a role in tumour progression, we carried out immunohistochemistry and ELISA for periostin in a range of neoplastic and non-neoplastic bone and joint lesions.

METHODS

140 formalin-fixed paraffin-embedded sections of bone tumours and tumour-like lesions were stained by an indirect immunoperoxidase technique with a polyclonal anti-periostin antibody. Periostin expression was also assessed in rheumatoid arthritis (RA) and non-inflammatory osteoarthritis (OA) synovium and synovial fluid immunohistochemistry and ELISA respectively.

RESULTS

Periostin was most strongly expressed in osteoid/woven bone of neoplastic and non-neoplastic bone-forming lesions, including osteoblastoma, osteosarcoma, fibrous dysplasia, osteofibrous dysplasia, fracture callus and myositis ossificans, and mineralised chondroid matrix/woven bone in chondroblastoma and clear cell chondrosarcoma. Reactive host bone at the edge of growing tumours, particularly in areas of increased vascularity and fibrosis, also stained strongly for periostin. Vascular elements in RA synovium strongly expressed periostin, and synovial fluid levels of periostin were higher in RA than OA.

CONCLUSIONS

In keeping with its known role in modulating the synthesis of collagen and other extracellular matrix proteins in bone, strong periostin expression was noted in benign and malignant lesions forming an osteoid or osteoid-like matrix. Periostin was also noted in other bone tumours and was found in areas of reactive bone and increased vascularity at the edge of growing tumours, consistent with its involvement in tissue remodelling and angiogenesis associated with tumour progression.

Aptamers: Uptake mechanisms and intracellular applications

The structural flexibility and small size of aptamers enable precise recognition of cellular elements for imaging and therapeutic applications. The process by which aptamers are taken into cells depends on their targets but is typically clathrin-mediated endocytosis or macropinocytosis. After internalization, most aptamers are transported to endosomes, lysosomes, endoplasmic reticulum, Golgi apparatus, and occasionally mitochondria and autophagosomes. Intracellular aptamers, or “intramers,” have versatile functions ranging from intracellular RNA imaging, gene regulation, and therapeutics to allosteric modulation, which we discuss in this review. Immune responses to therapeutic aptamers and the effects of G-quadruplex structure on aptamer function are also discussed.

NRF2 Activation Inhibits Both TGF-β1- and IL-13-Mediated Periostin Expression in Fibroblasts: Benefit of Cinnamaldehyde for Antifibrotic Treatment

Systemic fibrosing or sclerotic disorders are life-threatening, but only very limited treatment modalities are available for them. In recent years, periostin (POSTN), a major extracellular matrix component, was established by several studies as a novel key player in the progression of systemic fibrotic disease. In this research, we revealed the involvement of oxidative stress in the expression of POSTN induced by TGF-β1 and IL-13 in dermal fibroblasts. We found that the antioxidant cinnamaldehyde activated the NRF2/HMOX1 pathway. Cinnamaldehyde also alleviated TGF-β1- and IL-13-mediated production of reactive oxygen species and subsequent POSTN upregulation in dermal fibroblasts. In contrast, NRF2 silencing abolished the cinnamaldehyde-mediated downregulation of POSTN. These results suggest that cinnamaldehyde is a broad inhibitor of POSTN expression covering both TGF-β1 and IL-13 signaling. Cinnamaldehyde may thus be beneficial for the treatment of systemic fibrotic diseases.

Periostin is a negative prognostic factor and promotes cancer cell proliferation in non-small cell lung cancer

Periostin is a matricellular protein that is secreted by fibroblasts and interacts with various cell-surface integrin molecules. Although periostin is known to support tumor development in human malignancies, little is known about its effect on lung-cancer progression. We here demonstrate that periostin is a negative prognostic factor that increases tumor proliferation through ERK signaling in non-small cell lung carcinoma. We classified 189 clinical specimens from patients with non-small cell lung-cancer according to high or low periostin expression, and found a better prognosis for patients with low rather than high periostin, even in cases of advanced-stage cancer. In a syngenic implantation model, murine Ex3LL lung-cancer cells formed smaller tumor nodules in periostin^−/− mice than in periostin^+/+ mice, both at the primary site and at metastatic lung sites. An in vitro proliferation assay showed that stimulation with recombinant periostin increased Ex3LL-cell proliferation. We also found that periostin promotes ERK phosphorylation, but not Akt or FAK activation. These findings suggest that periostin represents a potential target in lung-cancer tumor progression.

Serum periostin levels following small bone fractures, long bone fractures and joint replacements: an observational study

BACKGROUND

In asthma, serum periostin may potentially be used as a biomarker in the management of patients with Type-2 eosinophilic airway inflammation. However, serum periostin may be influenced by factors other than Type 2 inflammation, potentially confounding its interpretation. We aimed to measure change in periostin following bone injury.

METHODS

102 adults without asthma were recruited into three groups: joint replacement surgery, long bone fracture, short bone fracture. Participants underwent seven measurements of serum periostin over 26 weeks after bone injury, and prior to surgery in the joint replacement group. Differences in periostin were measured using a ratio of geometric mean (RGM), with comparison made with pre-surgery (joint replacement) or 26 week (long and short fracture) reference measurements.

RESULTS

In the joint replacement group, periostin fell within 48 h (RGM 0.80, 95% CI 0.75-0.86), then increased to a maximum at 8 weeks (RGM 1.89, 1.77-2.02) and by 26 weeks remained above the reference measurement (RGM 1.27, 1.19-1.36). In the long bone fracture group, periostin was reduced at 48 h (RGM 0.76, 0.71-0.83) and then progressively increased to a maximum at 8 weeks (RGM 1.15, 1.06-1.23) compared with the reference measurement. In the short bone fracture group, periostin was reduced at 48 h (RGM 0.9, 0.85-0.95) but was not different from after week 1 compared with the reference measurement.

CONCLUSIONS

Serum periostin levels are influenced by bone injury. The timing and extent of bone injury needs consideration if periostin is used as a biomarker in the management of eosinophilic asthma.Trial registration This trial was prospectively registered with the Australia New Zealand Trials Registry on Feb 7 2014, (ACTRN12614000151639: https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=363881).

Periostin contributes to the maturation and shape retention of tissue-engineered cartilage

Traditional tissue-engineered cartilage applied in clinical practice consists of cell suspensions or gel-form materials for which it is difficult to maintain their shapes. Although biodegradable polymer scaffolds are used for shape retention, deformation after transplantation can occur. Here, we showed that periostin (PN), which is abundantly expressed in fibrous tissues, contributes to the maturation and shape retention of tissue-engineered cartilage through conformational changes in collagen molecules. The tissue-engineered cartilage transplanted in an environment lacking PN exhibited irregular shapes, while transplants originating from chondrocytes lacking PN showed limited regeneration. In the in vitro assay, PN added to the culture medium of chondrocytes failed to show any effects, while the 3D culture embedded within the collagen gel premixed with PN (10 μg/mL) enhanced chondrogenesis. The PN-mediated collagen structure enhanced the mechanical strength of the surrounding fibrous tissues and activated chondrocyte extracellular signaling by interstitial fibrous tissues.

Sca-1+ cardiac fibroblasts promote development of heart failure

The causative effect of GM-CSF produced by cardiac fibroblasts to development of heart failure has not been shown. We identified the pathological GM-CSF-producing cardiac fibroblast subset and the specific deletion of IL-17A signaling to these cells attenuated cardiac inflammation and heart failure. We describe here the CD45^- CD31^- CD29⁺ mEF-SK4⁺ PDGFRα⁺ Sca-1⁺ periostin⁺ (Sca-1⁺ ) cardiac fibroblast subset as the main GM-CSF producer in both experimental autoimmune myocarditis and myocardial infarction mouse models. Specific ablation of IL-17A signaling to Sca-1⁺ periostin⁺ cardiac fibroblasts (Postn^Cre Il17ra^fl/fl ) protected mice from post-infarct heart failure and death. Moreover, Postn^Cre Il17ra^fl/fl mice had significantly fewer GM-CSF-producing Sca-1⁺ cardiac fibroblasts and inflammatory Ly6C^hi monocytes in the heart. Sca-1⁺ cardiac fibroblasts were not only potent GM-CSF producers, but also exhibited plasticity and switched their cytokine production profiles depending on local microenvironments. Moreover, we also found GM-CSF-positive cardiac fibroblasts in cardiac biopsy samples from heart failure patients of myocarditis or ischemic origin. Thus, this is the first identification of a pathological GM-CSF-producing cardiac fibroblast subset in human and mice hearts with myocarditis and ischemic cardiomyopathy. Sca-1⁺ cardiac fibroblasts direct the type of immune cells infiltrating the heart during cardiac inflammation and drive the development of heart failure.

Amniotic ectoderm expansion in mouse occurs via distinct modes and requires SMAD5-mediated signalling

Upon gastrulation, the mammalian conceptus transforms rapidly from a simple bilayer into a multilayered embryo enveloped by its extra-embryonic membranes. Impaired development of the amnion, the innermost membrane, causes major malformations. To clarify the origin of the mouse amnion, we used single-cell labelling and clonal analysis. We identified four clone types with distinct clonal growth patterns in amniotic ectoderm. Two main types have progenitors in extreme proximal-anterior epiblast. Early descendants initiate and expand amniotic ectoderm posteriorly, while descendants of cells remaining anteriorly later expand amniotic ectoderm from its anterior side. Amniogenesis is abnormal in embryos deficient in the bone morphogenetic protein (BMP) signalling effector SMAD5, with delayed closure of the proamniotic canal, and aberrant amnion and folding morphogenesis. Transcriptomics of individual Smad5 mutant amnions isolated before visible malformations and tetraploid chimera analysis revealed two amnion defect sets. We attribute them to impairment of progenitors of the two main cell populations in amniotic ectoderm and to compromised cuboidal-to-squamous transition of anterior amniotic ectoderm. In both cases, SMAD5 is crucial for expanding amniotic ectoderm rapidly into a stretchable squamous sheet to accommodate exocoelom expansion, axial growth and folding morphogenesis.

Targeting TGFβ Signaling to Address Fibrosis Using Antisense Oligonucleotides

Fibrosis results from the excessive accumulation of extracellular matrix in chronically injured tissue. The fibrotic process is governed by crosstalk between many signaling pathways. The search for an effective treatment is further complicated by the fact that there is a degree of tissue-specificity in the pathways involved, although the process is not completely understood for all tissues. A plethora of drugs have shown promise in pre-clinical models, which is not always borne out translationally in clinical trial. With the recent approvals of two antisense oligonucleotides for the treatment of the genetic diseases Duchenne muscular dystrophy and spinal muscular atrophy, we explore here the potential of antisense oligonucleotides to knockdown the expression of pro-fibrotic proteins. We give an overview of the generalized fibrotic process, concentrating on key players and highlight where antisense oligonucleotides have been used effectively in cellular and animal models of different fibrotic conditions. Consideration is given to the advantages antisense oligonucleotides would have as an anti-fibrotic therapy alongside factors that would need to be addressed to improve efficacy. A prospective outlook for the development of antisense oligonucleotides to target fibrosis is outlined.

Hydraulic Transcrestal Sinus Lift: Different Patterns of Elevation in Pig Sinuses

PURPOSE

The aim of this study was to evaluate different patterns of sinus membrane elevation in pig jaws.

MATERIALS AND METHODS

A total of 30 pig jaws (60 sinuses) were used for the present investigation. The hydraulic Crestal Approach Sinus kit was used to elevate sinus membrane, and different elevation patterns were recorded.

RESULTS

There were 4 different scenarios of membrane separation patterns: center dome-shaped elevation, off-center dome-shaped elevation, horizontally spreading membrane elevation, and perforation. The incidence of each different type was 35.0% (n = 21) in center dome-shaped separation, 51.7% (n = 31) in off-center dome-shaped separation, 10.0% (n = 6) in horizontally spreading separation, and 3.3% (n = 2) in membrane perforation.

CONCLUSION

Different patterns of membrane elevations are observed in pig sinuses and introduced in this study. The off-center dome-shaped elevation was the most common pattern followed by the center dome-shaped elevation and horizontally spreading elevation, respectively.

Periostin: A Matricellular Protein With Multiple Functions in Cancer Development and Progression

Tumor microenvironment is considered nowadays as one of the main players in cancer development and progression. Tumor microenvironment is highly complex and consists of non-tumor cells (i.e., cancer-associated fibroblast, endothelial cells, or infiltrating leukocytes) and a large list of extracellular matrix proteins and soluble factors. The way that microenvironment components interact among them and with the tumor cells is very complex and only partially understood. However, it is now clear that these interactions govern and modulate many of the cancer hallmarks such as cell proliferation, the resistance to death, the differentiation state of tumor cells, their ability to migrate and metastasize, and the immune response against tumor cells. One of the microenvironment components that have emerged in the last years with strength is a heterogeneous group of multifaceted proteins grouped under the name of matricellular proteins. Matricellular proteins are a family of non-structural matrix proteins that regulate a variety of biological processes in normal and pathological situations. Many components of this family such as periostin (POSTN), osteopontin (SPP1), or the CNN family of proteins have been shown to regulate key aspect of tumor biology, including proliferation, invasion, matrix remodeling, and dissemination to pre-metastatic niches in distant organs. Matricellular proteins can be produced by tumor cells themselves or by tumor-associated cells, and their synthesis can be affected by intrinsic and/or extrinsic tumor cell factors. In this review, we will focus on the role of POSTN in the development and progression of cancer. We will describe their functions in normal tissues and the mechanisms involved in their regulation. We will analyze the tumors in which their expression is altered and their usefulness as a biomarker of tumor progression. Finally, we will speculate about future directions for research and therapeutic approaches targeting POSTN.

Loss of periostin ameliorates adipose tissue inflammation and fibrosis in vivo

Recent evidence suggests that the accumulation of macrophages as a result of obesity-induced adipose tissue hypoxia is crucial for the regulation of tissue fibrosis, but the molecular mechanisms underlying adipose tissue fibrosis are still unknown. In this study, we revealed that periostin (Postn) is produced at extraordinary levels by adipose tissue after feeding with a high-fat diet (HFD). Postn was secreted at least from macrophages in visceral adipose tissue during the development of obesity, possibly due to hypoxia. Postn-/- mice had lower levels of crown-like structure formation and fibrosis in adipose tissue and were protected from liver steatosis. These mice also showed amelioration in systemic insulin resistance compared with HFD-fed WT littermates. Mice deficient in Postn in their hematopoietic compartment also had lower levels of inflammation in adipose tissue, in parallel with a reduction in ectopic lipid accumulation compared with the controls. Our data indicated that the regulation of Postn in visceral fat could be beneficial for the maintenance of healthy adipose tissue in obesity.

Fascinating Fasciclins: A Surprisingly Widespread Family of Proteins that Mediate Interactions between the Cell Exterior and the Cell Surface

The Fasciclin 1 (FAS1) domain is an ancient structural motif in extracellular proteins present in all kingdoms of life and particularly abundant in plants. The FAS1 domain accommodates multiple interaction surfaces, enabling it to bind different ligands. The frequently observed tandem FAS1 arrangement might both positively and negatively regulate ligand binding. Additional protein domains and post-translational modifications are partially conserved between different evolutionary clades. Human FAS1 family members are associated with multiple aspects of health and disease. At the cellular level, mammalian FAS1 proteins are implicated in extracellular matrix structure, cell to extracellular matrix and cell to cell adhesion, paracrine signaling, intracellular trafficking and endocytosis. Mammalian FAS1 proteins bind to the integrin family of receptors and to protein and carbohydrate components of the extracellular matrix. FAS1 protein encoding plant genes exert effects on cellulosic and non-cellulosic cell wall structure and cellular signaling but to establish the modes of action for any plant FAS1 protein still requires biochemical experimentation. In fungi, eubacteria and archaea, the differential presence of FAS1 proteins in closely related organisms and isolated biochemical data suggest functions in pathogenicity and symbiosis. The inter-kingdom comparison of FAS1 proteins suggests that molecular mechanisms mediating interactions between cells and their environment may have evolved at the earliest known stages of evolution.

Structural characterizations of human periostin dimerization and cysteinylation

Human periostin plays a multifaceted role in remodeling the extracellular matrix milieu by interacting with other proteins and itself in both a heterophilic and homophilic manner. However, the structural mechanism for its extensive interactions has remained elusive. Here, we report the crystal structures of human periostin (EMI-Fas1^I-IV ) and its Cys60Ala mutant. In combination with multi-angle light-scattering analysis and biochemical assays, the crystal structures reveal that periostin mainly exists as a dimer in solution and its homophilic interaction is mainly mediated by the EMI domain. Furthermore, Cys60 undergoes cysteinylation as confirmed by mass spectroscopy, and this site hardly affects the homophilic interaction. Also, the structures yield insights into how periostin forms heterophilic interactions with other proteins under physiological or pathological conditions.

Vitamin K‑dependent proteins involved in bone and cardiovascular health (Review)

In postmenopausal women and elderly men, bone density decreases with age and vascular calcification is aggravated. This condition is closely associated with vitamin K2 deficiency. A total of 17 different vitamin K-dependent proteins have been identified to date. Vitamin K-dependent proteins are located within the bone, heart and blood vessels. For instance, carboxylated osteocalcin is beneficial for bone and aids the deposition of calcium into the bone matrix. Carboxylated matrix Gla protein effectively protects blood vessels and may prevent calcification within the vascular wall. Furthermore, carboxylated Gla-rich protein has been reported to act as an inhibitor in the calcification of the cardiovascular system, while growth arrest-specific protein-6 protects endothelial cells and vascular smooth muscle cells, resists apoptosis and inhibits the calcification of blood vessels by inhibiting the apoptosis of vascular smooth muscle cells. In addition, periostin may promote the differentiation, aggregation, adhesion and proliferation of osteoblasts. Periostin also occurs in the heart and may be associated with the reconstruction of heart function. These vitamin K-dependent proteins may exert their functions following γ-carboxylation with vitamin K, and different vitamin K-dependent proteins may exhibit synergistic effects or antagonistic effects on each other. In the cardiovascular system with vitamin K antagonist supplement or vitamin K deficiency, calcification occurs in the endothelium of blood vessels and vascular smooth muscle cells are transformed into osteoblast-like cells, a phenomenon that resembles bone growth. Both the bone and cardiovascular system are closely associated during embryonic development. Thus, the present study hypothesized that embryonic developmental position and tissue calcification may have a certain association for the bone and the cardiovascular system. This review describes and briefly discusses several important vitamin K-dependent proteins that serve an important role in bone and the cardiovascular system. The results of the review suggest that the vascular calcification and osteogenic differentiation of vascular smooth muscle cells may be associated with the location of the bone and cardiovascular system during embryonic development.

The Role of Periostin in Capsule Formation on Silicone Implants

Although silicone implants are widely used in breast and other reconstructive surgeries, the limited biocompatibility of these materials leads to severe complications, including capsular contracture. Here, we aimed to clarify the relationship between periostin and the process of capsule formation after in vivo implantation. Seven-week-old wild-type (WT) C57BL/6 mice and periostin-deficient mice were used. Round silicone implants were inserted into a subcutaneous pocket on the dorsum of the mice. After 8 weeks, the fibrous capsule around the implant was harvested and histologically examined to estimate capsular thickness and the number of inflammatory cells. Additionally, immunohistochemical analysis (periostin, α-SMA, and collagen type I) and western blotting (CTGF, TGF-β, VEGF, and MPO) were performed for a more detailed analysis of capsule formation. The capsules in periostin-knockout mice (PN-KO) were significantly thinner than those in WT mice. PN-KO mice showed significantly lower numbers of inflammatory cells than WT mice. Fibrous tissue formation markers (α-SMA, periostin, collagen type I, and CTGF) were significantly reduced in PN-KO mice. We also confirmed that inflammatory reaction and angiogenesis indicators (TGF-β, MPO, and VEGF) had lower expression in PN-KO mice. Inhibition of periostin could be important for suppressing capsule formation on silicone implants after in vivo implantation.

Cross-talk between ovarian cancer cells and macrophages through periostin promotes macrophage recruitment

Tumor‐associated macrophages (TAMs) contribute to tumor progression, but it is not clear how they are recruited to tumor sites. Here we showed that periostin (POSTN) was present at high levels in ovarian cancer ascetic fluids and was correlated with CD163⁺TAMs. The high POSTN level and macrophage infiltration were inversely associated with relapse‐free survival for ovarian cancer patients. In vitro studies showed that coculture with macrophages significantly increased POSTN production in ovarian cancer cells. Further investigation found that POSTN production in ovarian cancer cells was promoted by transforming growth factor‐β generated by macrophages. Moreover, siRNA of POSTN and POSTN neutralizing antibody treatment showed that ovarian cancer cell‐derived POSTN promoted the recruitment of macrophages and modulated their cytokine secretion profile. Collectively, these data indicated that POSTN was an important factor for macrophage recruitment in the tumor microenvironment and is involved in the interactions between macrophages and ovarian cancer cells.

Periostin attenuates tumor growth by inducing apoptosis in colitis-related colorectal cancer

Inflammatory bowel diseases, which are multifactorial autoimmune colitis diseases, are occurring with increasing prevalence. One of the most serious complications of these diseases is colorectal cancer. Here we investigated the role of periostin (Postn), a matricellular protein that interacts with various integrin molecules on the cell surface, in colitis-induced colorectal cancer. Immunohistochemistry of mouse and human colorectal cancer samples revealed that Postn was expressed in the stroma and was upregulated in close proximity to the cancer cells. The colonic tumorigenesis in an inflammation-related colon carcinogenesis mouse model was increased in Postn knock-out (Postn^−/−) mice compared to Postn^+/+ mice. Although no difference was found in the degree of colitis between Postn^+/+ and Postn^−/− mice, Postn inhibited tumor growth and induced the apoptosis of mouse rectal cancer cells in vitro. Furthermore, fewer apoptotic colorectal cancer cells were observed in Postn^−/− than in Postn^+/+ mice. These data suggested that Postn has an anti-tumor effect on colitis-induced colorectal cancer.

Serum periostin levels serve as a biomarker for both eosinophilic airway inflammation and fixed airflow limitation in well-controlled asthmatics

OBJECTIVE

Periostin, a matricellular protein, is produced from airway epithelial cells and lung fibroblasts by IL-13. It has been suggested that periostin is involved in allergic inflammation and fibrosis. However, the usefulness of serum periostin measurement in the assessment of airway inflammation and remodeling and management of asthmatic patients is still debated. We aimed to determine whether serum periostin levels reflect eosinophilic airway inflammation and airway remodeling in asthma.

METHODS

We examined the relationship of serum periostin levels with clinical features, biomarkers for eosinophilic airway inflammation, fraction of exhaled nitric oxide (FeNO) levels and blood eosinophil counts, and pulmonary functions in 235 well-controlled asthmatic patients on inhaled corticosteroids (ICS) treatment.

RESULTS

Serum periostin levels were positively correlated with blood eosinophil counts (%) and age (r = 0.36 and 0.23, respectively), and were negatively correlated with body weight and FEV₁/FVC (%) (r = -0.24 and - 0.23, respectively) in well-controlled asthmatic patients on ICS treatment (daily dose of 453 µg equivalent to fluticasone propionate). Blood eosinophil counts and serum periostin levels were similarly associated with increased FeNO levels (≥40 ppb) in the asthmatics. Serum periostin levels were better associated with fixed airflow limitation (FEV₁/FVC ratio <70%) than FeNO levels, blood eosinophil counts or total IgE levels in the asthmatics. Multivariate analysis showed that fixed airflow limitation was significantly associated with high serum periostin levels (≥97 ng/ml) (Odds ratio 3.2).

CONCLUSIONS

Serum periostin levels serve as a biomarker for both eosinophilic airway inflammation and fixed airflow limitation in well-controlled asthmatics on ICS treatment.

1H, 13C, and 15N resonance assignments of FAS1-IV domain of human periostin, a component of extracellular matrix proteins

Periostin, an extracellular matrix protein, is secreted by fibroblasts and is overexpressed in various types of cancers. The four internal repeat fasciclin 1 (FAS1) domains of human periostin play crucial roles in promoting tumor metastasis and progression via interaction with cell surface integrins. Among four FAS1 domains of human periostin, the fourth FAS1 domain (FAS1-IV) was prepared for NMR study, since only FAS1-IV was highly soluble, and showed a well-dispersed 2D ¹H-¹⁵N HSQC spectrum. Here, we report nearly complete backbone and side chain resonance assignments and a secondary structural analysis of the FAS1-IV domain as first steps toward the structure determination of FAS1-IV of human periostin.

Molecular influence of anterior cruciate ligament tear remnants on chondrocytes: a biologic connection between injury and osteoarthritis

OBJECTIVE

Anterior cruciate ligament (ACL) injury initiates a cascade of events often leading to osteoarthritis (OA). ACL reconstruction does not alter the course of OA, suggesting that heightened OA risk is likely due to factors in addition to the joint instability. We showed that torn ACL remnants express periostin (POSTN) in the acute phase of injury. Considering that ACL injury predisposes to OA and that POSTN is associated with cartilage metabolism, we hypothesize that ACL injury affects chondrocytes via POSTN.

DESIGN

Cartilage was obtained from osteoarthritic patients and ACL remnants were collected from patients undergoing ACL reconstruction. Crosstalk between ACL remnants and chondrocytes was studied in a transwell co-culture system. Expression of POSTN and other anabolic and catabolic genes was assessed via real-time polymerase chain reaction (PCR). Immunostaining for periostin was performed in human and mouse cartilage. The impact of exogenous periostin and siRNA-mediated ablation of periostin on matrix metabolism and cell migration was examined. Furthermore, the effect of anabolic (transforming growth factor beta 1 [TGF-β1]) and catabolic (interleukin 1 beta [IL-1β]) factors on POSTN expression was investigated.

RESULTS

ACL remnants induced expression of POSTN, MMP13 and ADAMTS4. Periostin levels were significantly higher in osteoarthritic compared to normal cartilage. Exogenous periostin induced MMP13 expression and cell migration, and repressed COL1A1 expression while POSTN knockdown inhibited expression of both anabolic and catabolic genes and impeded cell migration. TGF-β1 and IL-1β treatment did not alter POSTN expression but influenced chondrocyte metabolism as determined by quantification of anabolic and catabolic genes via real-time PCR.

CONCLUSIONS

ACL remnants can exert paracrine effects on cartilage, altering cellular homeostasis. Over time, this metabolic imbalance could contribute to OA development.