Fibronectin Synthesis Research Articles

Abstract 6219: Type V collagen promotes lung adenocarcinoma metastasis by regulating tumor mechanical stress and the implication for prognosis and therapeutic strategies

Abstract Introduction: The mechanical environment of the human body influences physiological and pathological processes, and understanding these biomechanical aspects holds promise for medical research. Tumor microenvironment changes, including extracellular matrix (ECM) alterations, result the changing of mechanical characteristics of the tissue, play a crucial role in cancer progression and metastasis, including lung adenocarcinoma (LUAD), one of a major histology type of lung cancer. This study focuses on elucidating how mechanical characteristics, especially those related to the ECM, influence LUAD and the signaling pathways involved. Methods: Cell culture, transfection, Western blot, immunofluorescence, immunohistochemistry, Transwell assay, scratch wound-healing assay were used to investigate the behavior changes of LUAD cells under different treatment. Bioinformatics analyses, and machine learning-based integrative approaches were employed to build the SVM_Score, which was built with relevant base membrane (BM) genes. Patient-derived tumor organoids, myofibroblasts, and co-culture systems were established. Sorafenib, which can inhibited collagen and fibronectin synthesis, was used to explore the proliferation and migration changing of lung cancer cells co-cultured with myofibroblasts. Results: Mechanical stress, simulated by matrix application, enhanced LUAD cell migration and invasion, correlating with ECM alterations and EMT pathway activation. SVM_Score predicted LUAD patient prognosis and EMT propensity across multiple datasets, revealing its robust prognostic capabilities. Lower SVM_Scores were associated with worse survival outcomes, increased cancer-related pathways, higher Tumor Mutation Burden and altered immune microenvironment characteristics. SVM_Score was also linked to myofibroblast-secreted COL5A1, a key marker for mechanical stress. Patient tissues with low SVM_Scores exhibited higher COL5A1 expression, enhanced EMT propensity, and increased internal mechanical stress. Sorafenib, by inhibiting COL5A1 secretion, attenuated the pro-tumor effects of myofibroblasts, inhibiting proliferation and migration of LUAD cells, and rendering LUAD cells more sensitive to chemotherapy. Conclusion: This comprehensive study unveils the intricate relationship between mechanical stress, ECM alterations, and LUAD progression. SVM_Score emerges as a potent prognostic tool, reflects tumor mechanical characteristics. Sorafenib intervention targeting COL5A1 secretion provides a potential therapeutic strategy to mitigate LUAD aggressiveness. These findings contribute to a deeper understanding of the biomechanical aspects of LUAD, offering insights for future research and clinical applications. Citation Format: Guangsheng Zhu, Yanan Wang, Yingjie Wang, Chen, Yongwen Li, Hongyu Liu, Jun Chen. Type V collagen promotes lung adenocarcinoma metastasis by regulating tumor mechanical stress and the implication for prognosis and therapeutic strategies [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6219.

Phytohormones affect the differentiation of human dermal fibroblasts via UPR activation

Normalization of secretory activity and the level of differentiation of mesenchymal cells, including fibroblasts, is the important biomedical problem. One of the plausible solutions to this problem is to affect the unfolded protein response (UPR) signaling cascade, which is activated during fibroblast differentiation. In the present study, the effect of phytohormones on the secretory activity and differentiation of cultured human dermal fibroblasts was investigated. By analyzing the expression level of genes encoding UPR markers in these cells, we found that phytohormone abscisic acid (ABA) upregulated the expression of GRP78 and ATF4 genes, while phytohormone gibberellic acid (GA) upregulated the expression of CHOP. Evaluation of the biosynthetic activity of fibroblasts showed that ABA elevated the level of secretion and synthesis of procollagen I and the level of fibronectin synthesis, as well as total production of collagen and non-collagen proteins of extracellular matrix. ABA also stimulated the synthesis of smooth muscle actin α (α-SMA) and increased the number of myofibroblasts in cell population. On the contrary, GA increased the level of fibronectin secretion, but decreased the level of procollagen I synthesis, and reduced the total production of collagen proteins of extracellular matrix. Concomitantly, in these conditions we observed the decreased level of α-SMA synthesis and the number of myofibroblasts in the cell population. Our results suggest that phytohormones are the modulators of the biosynthetic activity of fibroblasts and affect their differentiation status.

Phytohormones Affect Differentiation Status of Human Skin Fibroblasts via UPR Activation.

Normalization of secretory activity and differentiation status of mesenchymal cells, including fibroblasts, is an important biomedical problem. One of the possible solutions is modulation of unfolded protein response (UPR) activated during fibroblast differentiation. Here, we investigated the effect of phytohormones on the secretory activity and differentiation of cultured human skin fibroblasts. Based on the analysis of expression of genes encoding UPR markers, abscisic acid (ABA) upregulated expression of the GRP78 and ATF4 genes, while gibberellic acid (GA) upregulated expression of CHOP. Evaluation of the biosynthetic activity of fibroblasts showed that ABA promoted secretion and synthesis of procollagen I and synthesis of fibronectin, as well as the total production of collagen and non-collagen proteins of the extracellular matrix (ECM). ABA also stimulated the synthesis of smooth muscle actin α (α-SMA), which is the marker of myofibroblasts, and increased the number of myofibroblasts in the cell population. On the contrary, GA increased the level of fibronectin secretion, but reduced procollagen I synthesis and the total production of the ECM collagen proteins. GA downregulated the synthesis of α-SMA and decreased the number of myofibroblasts in the cell population. Our results suggest that phytohormones modulate the biosynthetic activity of fibroblasts and affect their differentiation status.

Modulating tumor-stromal crosstalk via a redox-responsive nanomedicine for combination tumor therapy.

Interaction between carcinoma-associated fibroblasts (CAFs) and tumor cells leads to the invasion and metastasis of breast cancer. Herein, we prepared a redox-responsive chondroitin sulfate (CS)-based nanomedicine, in which hydrophobic cabazitaxel (CTX) was conjugated to the backbone of CS via glutathione (GSH)-sensitive dithiomaleimide (DTM) to form an amphipathic CS-DTM-CTX (CDC) conjugate, and dasatinib (DAS) co-assembled with the CDC conjugate to obtain DAS@CDC. After CD44 receptor-mediated internalization by CAFs, the nanomedicine could reverse CAFs to normal fibroblasts, blocking their crosstalk with tumor cells and reducing synthesis of major tumor extracellular matrix proteins, including collagen and fibronectin. Meanwhile, the nanomedicine internalized by tumor cells could effectively inhibit tumor proliferation and metastasis, leading to shrinkage of the tumor volume and inhibition of lung metastasis in a subcutaneous 4 T1 tumor model with low side effects. Collectively, the nanomedicine showed a remarkably synergistic therapy effect against breast cancer by modulating tumor-stromal crosstalk.

Astrocyte-associated fibronectin promotes the proinflammatory phenotype of astrocytes through β1 integrin activation

Astrocytes are key players in neuroinflammation. In response to central nervous system (CNS) injury or disease, astrocytes undergo reactive astrogliosis, which is characterized by increased proliferation, migration, and glial fibrillary acidic protein (GFAP) expression. Activation of the transcription factor nuclear factor-κB (NF-κB) and upregulation of downstream proinflammatory mediators in reactive astrocytes induce a proinflammatory phenotype in astrocytes, thereby exacerbating neuroinflammation by establishing an inflammatory loop. In this study, we hypothesized that excessive fibronectin (FN) derived from reactive astrocytes would induce this proinflammatory phenotype in astrocytes in an autocrine manner. We exogenously treated astrocytes with monomer FN, which can be incorporated into the extracellular matrix (ECM), to mimic plasma FN extravasated through a compromised blood–brain barrier in neuroinflammation. We also induced de novo synthesis and accumulation of astrocyte-derived FN through tumor necrosis factor-α (TNF-α) stimulation. The excessive FN deposition resulting from both treatments initiated reactive astrogliosis and triggered NF-κB signaling in the cultured astrocytes. In addition, inhibition of FN accumulation in the ECM by the FN inhibitor pUR4 strongly attenuated the FN- and TNF-α-induced GFAP expression, NF-κB activation, and proinflammatory mediator production of astrocytes by interrupting FN–β1 integrin coupling and thus the inflammatory loop. In an in vivo experiment, intrathecal injection of pUR4 considerably ameliorated FN deposition, GFAP expression, and NF-κB activation in inflamed spinal cord, suggesting the therapeutic potential of pUR4 for attenuating neuroinflammation and promoting neuronal function restoration.

Fibronectin in hyperglycaemia and its potential use in the treatment of diabetic foot ulcers: A review.

Metabolism of fibronectin, the protein that plays a key role in the healing of wounds, is changed in the patients with diabetes mellitus. Fibronectin can interact with other proteins and proteoglycans and organise them to form the extracellular matrix, the basis of the granulation tissue in healing wounds. However, diabetic foot ulcers (DFUs) suffer from inadequate deposition of this protein. Degradation prevails over fibronectin synthesis in the proteolytic inflammatory environment in the ulcers. Because of the lack of fibronectin in the wound bed, the assembly of the extracellular matrix and the deposition of the granulation tissue cannot be started. A number of methods have been designed that prevents fibronectin degradation, replace lacking fibronectin or support its formation in non-healing wounds in animal models of diabetes. The aim of this article is to review the metabolism of fibronectin in DFUs and to emphasise that it would be useful to pay more attention to fibronectin matrix assembly in the ulcers when laboratory methods are translated to clinical practice.

Role of pericytes in the development of cerebral cavernous malformations.

Cerebral cavernous malformation (CCM) is caused by loss-of-function mutations in CCM1, CCM2, or CCM3 genes of endothelial cells. It is characterized by pericyte deficiency. However, the role of pericytes in CCMs is not yet clarified. We found pericytes in Cdh5Cre ERT2 ;Ccm1 fl/fl (Ccm1 ECKO ) mice had a high expression of PDGFRβ. The inhibition of pericyte function by CP-673451 aggravated the CCM lesion development. RNA-sequencing analysis revealed the molecular traits of pericytes, such as highly expressed ECM-related genes, especially Fn1. Furthermore, KLF4 coupled with phosphorylated SMAD3 (pSMAD3) promoted the transcription of fibronectin in the pericytes of CCM lesions. RGDS peptide, an inhibitor of fibronectin, decreased the lesion area in the cerebella and retinas of Ccm1 ECKO mice. Also, human CCM lesions had abundant fibronectin deposition, and pSMAD3- and KLF4-positive pericytes. These findings indicate that pericytes are essential for CCM lesion development, and fibronectin intervention may provide a novel target for therapeutic intervention in such patients.

Expression and significance of TGF-β1 in infant asthma model

This article aimed to study the expression and role of TGF-β1 in young rat asthma. The experimental method in this paper is to replicate the asthma model by aerosolization of egg protein. The young rats with asthma were sacrificed after 2, 4 and 8 weeks. Reverse transcription polymerase chain reaction (RT-PCR) was used to detect the mRNA of TGF-β1 and α-SMA. The expression level was detected by the immunohistochemical staining method to detect the protein expression of TGF-β1, α-SMA, Smad3, Smad4 and Smad7 in bronchopulmonary tissues. At the same time, the image analysis method was used to measure the airway morphological parameters of young rats. The experimental results showed that the expression of TGF-β1 in the lung tissue of young rats in the asthma group was increased after two weeks of the challenge. Compared with the control group, the difference was significant (P<0.05); the expression of TGF-β1, α-SMA and mRNA in the 4-week group was significantly higher, compared with the control group and the 2-week challenge group, the difference was significant (P<0.05). Therefore, the change of asthma airway remodeling is a dynamic process. The TGF-β1 pathway presents a dynamic process in the airway remodeling model of young asthmatic rats. Among them, TGF-β1 induces the division and proliferation of airway fibroblasts and promotes fibroblasts. The cells transform into myofibroblasts and increase the synthesis of fibronectin and collagen, suggesting that it plays an important role in asthma inflammation and pulmonary fibrosis.

The brown alga Laminaria ochroleuca: Charming shell pickers of the strait of Messina, fanciful sirens, and treating war wounds and scars in prostitutes

Sir, In one of his precious masterpieces, Portuguese novelist José Saramago narrates in detail the lives of the rice weeders who used to work in this land and, after a day of work, soak their bare feet in a bath with hot water, salt, mallow, and chamomile in order to restore their ankles, swollen and inflated for the alga native to these particular paddy fields, Laminaria ochroleuca (Bachelot de la Pylaie), extremely rich in fucose and alginates, provoking an accelerated and paroxistic synthesis of elastin, fibronectin, and collagen. This brown alga may be retrieved from the waters of France, Spain, Scotland, and the Shetland Islands, yet even in the Azores Islands and Morocco (Alboran Sea) [1–4]. The authors of this paper selected a special Laminaria from the Strait of Messina (Nereocystis luetkeana), a heterokont that is able to grow half a meter per day reaching the surprising and amazing height of 260 ft.). The legend has it that shell collectors, chiefly young girls, day after day, saw their legs together to create the tail of a siren, a cartilaginous appendage rich in collagen and elastin becoming scaly and squamous owing to the seawater. The authors created a dermocosmetic emulsion with high concentrations of acetolyte from Laminaria ochroleuca (12%) and other nourishing active ingredients (obviously, the chief components were petrolatum and lanolin, as per the pharmaceutical art of preparing the cold cream of Galenus). Hence, this golden alga is able to support the skin by providing antioxidants to fight free radicals, supporting the health of collagen and elastin, which helps the skin retain elasticity and radiance, reducing fine lines and wrinkles and helping to moisturize the skin while boosting its barrier. Some researchers [5] claimed that this alga could be useful to build a skin equivalent, as fucoidan significantly stimulates the proliferation of CCD-25Sk human fibroblasts. Also, western blot analysis demonstrates that fucoidan markedly increases the expression of cyclin D1 and decreases the expression of p27. Fucoidan was practically used to reconstruct SE. Immunohistochemical staining reveals that the addition of fucoidan to dermal equivalents increases the expression of proliferating cell nuclear antigen (PCNA) and p63. In addition, the expression of a6-integrin is significantly increased by fucoidan, whereas the expression of b1-integrin, type 1 collagen, elastin, and fibronectin does not markedly change. In the light of the above, the authors may assert that fucoidan shows positive effects on epidermal reconstruction and is, therefore, beneficial in the reconstruction of all types of skin damage. The authors recruited a panel of eight people: 2 veterans from Iraq and Afghanistan (a-b) presenting old war wounds with no chance to cure these after years of treatments and a myriad of surgical operations; 2 elders (one male and one female, 87 and 89 yrs. old, respectively, c-d) presenting severe bedsores; 2 older ladies (e-f) who, in the past, underwent unsuccessful aesthetical operations, presenting puckers, seams, furrows and deep wrinkles; 2 girls (two ex-prostitutes, one black and one white, g-h) who were scarred with a razor by their enemies.

Biomimetic Full-Thickness Skin-on-a-Chip Based on a Fibroblast-Derived Matrix

Current commercially available in vitro skin models do not fully reproduce the structure and function of the native human skin, mainly due to their use of animal-derived collagen and their lack of a dynamic flow system. In this study, a full-thickness skin-on-a-chip (SoC) system that reproduces key aspects of the in vivo cellular microenvironment is presented. This approach combines the production of a fibroblast-derived matrix (FDM) with the use of an inert porous scaffold for the long-term, stable cultivation of a human skin model. The culture of a dermal compartment under fluid flow results in the increased synthesis and deposition of major FDM proteins, collagen I, and fibronectin, compared to tissues cultured under static conditions. The developed SoC includes a fully differentiated epidermal compartment with increased thickness and barrier function compared to the controls. Contrary to other SoC platforms that include a collagen-based matrix, the described model presents superior stability and physiological relevance. Finally, the skin barrier function was quantitatively evaluated via in situ transepithelial electrical resistance (TEER) measurements and in situ permeation tests. The SoC model presents a significantly higher TEER and lower permeability to FITC-dextran. In the future, this innovative low-cost platform could provide a new in vitro tissue system compatible with long-term studies to study skin diseases and evaluate the safety and efficacy of novel drugs and technologies.

Mast Cells Tryptase Promotes Intestinal Fibrosis in Natural Decellularized Intestinal Scaffolds.

Standard two-dimensional (2D) culture has confirmed the mechanism of mast cells (MCs) in the pathogenesis of inflammatory bowel disease(IBD), but the regulation of signaling responses of MCs may well differ in three-dimensional (3D) microenvironments. The aim of the study was to develop a 3D culture model based on decellularized intestinal scaffolds (DIS) and verify how MCs influenced fibroblasts phenotype in the 3D model. DIS were achieved using the detergent technique and extracellular matrix (ECM) components were verified by histologic analysis, quantification and scanning electron microscope. After human colon fibroblasts recellularized into the scaffolds and activated by MCs tryptase and TGFβ1, the changes in genes and signaling pathways during fibroblasts activation in 3D were studied and compared with the changes in 2D cell culture on plastic plates. Decellularization process effectively removed native cell debris while retaining natural ECM components and structure. The engrafted fibroblasts could penetrate into the scaffolds and maintain its phenotype. No matter whether fibroblasts were cultured in 2D or 3D, MCs tryptase and transforming growth factor β1 (TGF-β1) could promote the differentiation of fibroblasts into fibrotic-phenotype myofibroblasts through Akt and Smad2/3 signaling pathways. Furthermore, the pro-collagen1α1 and fibronectin synthesis of myofibroblasts in 3D was higher than in 2D culture. Our results demonstrated that the DIS can be used as a bioactive microenvironment for the study of intestinal fibrosis, providing an innovative platform for future intestinal disease modeling and screening of genes and signaling pathways.

Novel synthesis of fibronectin derived photoluminescent carbon dots for bioimaging applications.

Fibronectin (FN) derived from human plasma has been used for the first time as the carbon precursor in the top-down, microwave-assisted hydrothermal synthesis of nitrogen doped carbon dots (CDs). FN is a large glycoprotein primarily known for its roles in cell adhesion and cell growth. Due to these properties FN can be over expressed in the extracellular matrix (ECM) of some cancers allowing FN to be used as an indicator for the detection of cancerous cells over non-cancerous cells. These FN derived CDs display violet photoluminescence with UV excitation and appear to possess similar functional groups on their surface to their carbon precursor (-COOH and -NH2). This is believed to be due to the self-passivation of the CDs' nitrogen-containing surface functional groups during the heating process. These CDs were then used to stain MCF-7 and MDA-231 breast cancer cells and were observed to interact primarily with the cell membrane rather than intercalating into the cell like the many other types of CDs. This led to the hypothesis that the CDs are selectively binding to the FN overexpressed within the cancer cells' ECM via amide linkages. This is in agreement with the EDX and FTIR spectra of the FN CDs which indicate the presence of -COOH and nitrogen containing surface groups like -NH3. The inherent selectivity of the CDs combined with their ability to photoluminesce enables their use as a fluorophore for bioimaging applications.

Sulfated alginate/polycaprolactone double-emulsion nanoparticles for enhanced delivery of heparin-binding growth factors in wound healing applications

Diabetic foot ulcers (DFUs) that are not effectively treated could lead to partial or complete lower limb amputations. The lack of connective tissue growth factor (CTGF) and insulin-like growth factor (IGF-I) in DFUs results in limited matrix deposition and poor tissue repair. To enhance growth factor (GF) availability in DFUs, heparin (HN)-mimetic alginate sulfate/polycaprolactone (AlgSulf/PCL) double emulsion nanoparticles (NPs) with high affinity and sustained release of CTGF and IGF-I were synthesized. The NPs size, encapsulation efficiency (EE), cytotoxicity, cellular uptake and wound healing capacity in immortalized primary human adult epidermal cells (HaCaT) were assessed. The sonication time and amplitude used for NPs synthesis enabled the production of particles with a minimum of 236 ± 25 nm diameter. Treatment of HaCaT cells with up to 50 μg mL−1 of NPs showed no cytotoxic effects after 72 h. The highest bovine serum albumin EE (94.6 %, P = 0.028) and lowest burst release were attained with AlgSulf/PCL. Moreover, cells treated with AlgSulf/CTGF (250 ng mL−1) exhibited the most rapid wound closure compared to controls while maintaining fibronectin synthesis. Double-emulsion NPs based on HN-mimetic AlgSulf represent a novel approach which can significantly enhance diabetic wound healing and can be expanded for applications requiring the delivery of other HN-binding GFs.

Antifibrotic effects of eupatilin on TGF-β1-treated human vocal fold fibroblasts.

Vocal fold scarring is a major cause of dysphonia. Vocal fold fibroblasts (VFFs) and the TGF-β signaling pathway play important roles in scar formation. Eupatilin, a chromone derivative of the Artemisia species, is a traditional folk remedy for wound healing. However, until recently, few studies investigated the therapeutic effects of eupatilin. We investigated the antifibrogenic effects of eupatilin on TGF-β1-treated human vocal fold fibroblasts (hVFFs). The optimal concentration of eupatilin was determined by a cell viability assay. Western blotting was used to measure the expression of alpha-smooth muscle actin during myofibroblast differentiation, fibronectin (FN), collagen type I (Col I), and collagen type III (Col III) extracellular matrix proteins, and Smad2, Smad3, and p38 in the fibrotic pathway. Measurements were made before and after eupatilin treatment. Eupatilin at 100 nM was shown to be safe for use in hVFFs. TGF-β1 induced hVFFs to proliferate and differentiate into myofibroblasts and increased Col III and FN synthesis in a time- and dose-dependent manner. Eupatilin suppressed TGF-β1-induced hVFF proliferation and differentiation into myofibroblasts through the Smad and p38 signaling pathways. Furthermore, eupatilin inhibited TGF-β1-induced FN, Col I, and Col III synthesis in hVFFs. Our in vitro findings show that eupatilin effectively suppressed TGF-β1-induced fibrotic changes in hVFFs via the Smad and p38 signaling pathways. Thus, eupatilin may be considered a novel therapeutic agent for the treatment of vocal fold fibrosis.

Changes in basement membrane components in an experimental model of skeletal muscle degeneration and regeneration induced by snake venom and myotoxic phospholipase A2

Skeletal muscle regeneration is impaired after myonecrosis induced by viperid snake venoms, but the mechanisms behind such poor regenerative outcome are not fully understood. This study compared the changes in basement membrane (BM) components in mouse skeletal muscle in two different scenarios of muscle injury: (a) injection of Bothrops asper venom, as a model of poor regeneration, and (b) injection of a myotoxic fraction (Mtx) isolated from this venom, as a model of successful regeneration. The degradation and reposition of laminin, type IV collagen and fibronectin were assessed over time by a combination of immunohistochemistry, Western blot, and real time polymerase chain reaction. Both treatments induced degradation of laminin and type IV collagen in areas of muscle necrosis since day one, however, there were differences in the pattern of degradation and reposition of these proteins along time. Overall, Mtx induced a higher synthesis of fibronectin and higher degradation of laminin at intermediate time points, together with higher levels of transcripts for the chains of the three proteins. Instead, venom induced a higher degradation of laminin and type IV collagen at early time intervals, followed by a reduced recovery of type IV collagen by 15 days. These differences in extracellular matrix degradation and remodeling between the two models could be associated to the poor muscle regeneration after myonecrosis induced by B. asper venom.

Uvaol Improves the Functioning of Fibroblasts and Endothelial Cells and Accelerates the Healing of Cutaneous Wounds in Mice.

Uvaol is a natural pentacyclic triterpene that is widely found in olives and virgin olive oil, exerting various pharmacological properties. However, information remains limited about how it affects fibroblasts and endothelial cells in events associated with wound healing. Here, we report the effect of uvaol in the in vitro and in vivo healing process. We show the positive effects of uvaol on migration of fibroblasts and endothelial cells in the scratch assay. Protein synthesis of fibronectin and laminin (but not collagen type I) was improved in uvaol-treated fibroblasts. In comparison, tube formation by endothelial cells was enhanced after uvaol treatment. Mechanistically, the effects of uvaol on cell migration involved the PKA and p38-MAPK signaling pathway in endothelial cells but not in fibroblasts. Thus, the uvaol-induced migratory response was dependent on the PKA pathway. Finally, topical treatment with uvaol caused wounds to close faster than in the control treatment using experimental cutaneous wounds model in mice. In conclusion, uvaol positively affects the behavior of fibroblasts and endothelial cells, potentially promoting cutaneous healing.

Periostin and matrix stiffness combine to regulate myofibroblast differentiation and fibronectin synthesis during palatal healing

Although the matricellular protein periostin is prominently upregulated in skin and gingival healing, it plays contrasting roles in myofibroblast differentiation and matrix synthesis respectively. Palatal healing is associated with scarring that can alter or restrict maxilla growth, but the expression pattern and contribution of periostin in palatal healing is unknown. Using periostin-knockout (Postn−/−) and wild-type (WT) mice, the contribution of periostin to palatal healing was investigated through 1.5 mm full-thickness excisional wounds in the hard palate. In WT mice, periostin was upregulated 6 days post-wounding, with mRNA levels peaking at day 12. Genetic deletion of periostin significantly reduced wound closure rates compared to WT mice. Absence of periostin reduced mRNA levels of pivotal genes in wound repair, including α-SMA/acta2, fibronectin and βigh3. Recruitment of fibroblasts and inflammatory cells, as visualized by immunofluorescent staining for fibroblast specific factor-1, vimentin, and macrophages markers Arginase-1 and iNOS was also impaired in Postn−/−, but not WT mice. Palatal fibroblasts isolated from the hard palate of mice were cultured on collagen gels and prefabricated silicon substrates with varying stiffness. Postn−/− fibroblasts showed a significantly reduced ability to contract a collagen gel, which was rescued by the exogenous addition of recombinant periostin. As the stiffness increased, Postn−/− fibroblasts increasingly differentiated into myofibroblasts, but not to the same degree as the WT. Pharmacological inhibition of Rac rescued the deficient myofibroblastic phenotype of Postn−/− cells. Low stiffness substrates (0.2 kPa) resulted in upregulation of fibronectin in WT cells, an effect which was significantly reduced in Postn−/− cells. Quantification of immunostaining for vinculin and integrinβ1 adhesions revealed that Periostin is required for the formation of focal and fibrillar adhesions in mPFBs. Our results suggest that periostin modulates myofibroblast differentiation and contraction via integrinβ1/RhoA pathway, and fibronectin synthesis in an ECM stiffness dependent manner in palatal healing.

AMPK Activation by 5-Amino-4-Imidazole Carboxamide Riboside-1-β-D-Ribofuranoside Attenuates Alkali Injury-Induced Corneal Fibrosis.

PurposeIncreased TGF-β1 synthesis after corneal alkali injury is implicated in corneal fibrosis, as it promotes transdifferentiation of keratocytes into myofibroblasts. The activation of 5′-adenosine monophosphate-activated protein kinase (AMPK) by 5-amino-4-imidazole carboxamide riboside-1-β-d-ribofuranoside (AICAR) inhibits TGF-β1-induced fibrosis in other cell types. We investigated the antifibrotic effect of AICAR in corneal fibroblasts after alkali injury.MethodsMouse models of corneal alkali burn, produced by placing 2-mm-diameter filter paper soaked in 0.1-N NaOH on the right cornea for 30 seconds, were treated with the test drugs 4× daily for 21 days. The central cornea was scanned by optical coherence tomography (OCT). Corneal tissues were obtained and processed for western blotting and immunohistochemistry. For in vitro analysis, primary human corneal fibroblasts were treated directly with TGF-β1 to induce fibrosis, with or without AICAR pretreatment. Myofibroblast activation and extracellular matrix (ECM) protein synthesis were detected by western blotting, real-time PCR, and collagen gel contraction assay. Signaling proteins were analyzed by western blotting.ResultsAlkali injury induced the upregulation of TGF-β1 expression, which led to increased α-smooth muscle actin (α-SMA) and fibronectin synthesis and myofibroblast differentiation. AMPK activation by AICAR significantly suppressed TGF-β1 and ECM protein expression. The antifibrotic effect of AICAR was AMPK dependent, as treatment with the AMPK inhibitor Compound C attenuated the antifibrotic response.ConclusionsAMPK activation by AICAR suppresses the myofibroblast differentiation and ECM synthesis that occur after alkali injury in corneal fibroblasts.

AB0168 NINTEDANIB (TYROSINE-KINASE INHIBITOR) INHIBITS THE TRANSITION OF CIRCULATING FIBROCYTES ISOLATED FROM SYSTEMIC SCLEROSIS PATIENTS INTO MYOFIBROBLASTS: AN IN VITROSTUDY

Background:Systemic sclerosis (SSc) is a chronic connective disease characterized by microvascular alterations, dysregulated immune response and fibrosis [1,2]. Myofibroblasts are alpha-smooth muscle actin (alphaSMA)+cells and play a crucial role in fibrosis, through the excessive synthesis and deposition of extracellular matrix (ECM) proteins, in particular fibronectin (FN) and type I collagen (COL1) [3]. Despite myofibroblasts primarily derive from resident fibroblasts transition and differentiation, another important source is represented by circulating fibrocytes [4]. Nintedanib is a tyrosine kinase inhibitor approved for the treatment of idiopathic pulmonary fibrosis that interferes with the signalling pathways involved in the pathogenesis of fibrosis [5].Objectives:To investigate the possible effects of nintedanib in contrasting the ability of cultured mature fibrocytes from SSc patients to differentiate into profibrotic myofibroblasts.Methods:Circulating fibrocytes were obtained from peripheral blood mononuclear cells isolated from 5 limited cutaneous SSc patients (mean age 68 +/- 10 years) and then plated on FN-coated tissue culture dishes in growth medium (DMEM at 20% of fetal bovine serum, 1% of penicillin-streptomycin and 1% L-glutamine), to allow the adhesion of fibrocyte precursors. Adherent cells were maintained in growth medium for 8 days in order to allow their differentiation into fibrocytes. Differentiated fibrocytes were treated with nintedanib at the concentrations of 100nM and 1000nM for 3 and 24 hours (hrs) or maintained in growth medium without any treatment. The differentiation of fibrocytes into myofibroblasts was determined evaluating the gene expression of alphaSMA, fibroblast specific protein-1 (S100A4) COL1, FN and CXCR4 by quantitative real-time polymerase chain reaction, and the protein synthesis of alphaSMA, COL1 and FN by western blotting.Results:Nintedanib inhibited alphaSMA and S100A4 gene expression already at the concentration of 100nM in cultured fibrocytes and after 3 hrs of treatment, when compared with untreated cells. Furthermore, both concentrations of nintedanib (100nM and 1000nM) reduced the gene expression of COL1 and FN, whereas only 100nM downregulated the CXCR4 gene expression. At protein level, nintedanib 100nM and 1000nM reduced the synthesis of alphaSMA and COL1 after 24 hrs of treatment, whereas FN synthesis was reduced only by the nintedanib concentration of 1000nM.Conclusion:The preliminary results show that nintedanib may inhibit thein vitrotransition of SSc fibrocytes into myofibroblasts and their profibrotic activity, through the reduction of specific myofibroblast phenotype markers and ECM protein production. The results seem to suggest fibrocytes as further possible target of the antifibrotic action of nintedanib in SSc.

Pirfenidone: Molecular Mechanisms and Potential Clinical Applications in Lung Disease.

Pirfenidone (PFD) is a pharmacological compound with therapeutic efficacy in idiopathic pulmonary fibrosis. It has been chiefly characterized as an antifibrotic agent, although it was initially developed as an antiinflammatory compound because of its ability to diminish the accumulation of inflammatory cells and cytokines. Despite recent studies that have elucidated key mechanisms, the precise molecular activities of PFD remain incompletely understood. PFD modulates fibrogenic growth factors, thereby attenuating fibroblast proliferation, myofibroblast differentiation, collagen and fibronectin synthesis, and deposition of extracellular matrix. This effect is mediated by suppression of TGF-β1 (transforming growth factor-β1) and other growth factors. Here, we appraise the impact of PFD on TGF-β1 production and its downstream pathways. Accumulating evidence indicates that PFD also downregulates inflammatory pathways and therefore has considerable potential as a viable and innovative antiinflammatory compound. We examine the effects of PFD on inflammatory cells and the production of pro- and antiinflammatory cytokines in the lung. In this context, recent evidence that PFD can target inflammasome pathways and ensuing lung inflammation is highlighted. Finally, the antioxidant properties of PFD, such as its ability to inhibit redox reactions and regulate oxidative stress-related genes and enzymes, are detailed. In summary, this narrative review examines molecular mechanisms underpinning PFD and its recognized benefits in lung fibrosis. We highlight preclinical data that demonstrate the potential of PFD as a nonsteroidal antiinflammatory agent and outline areas for future research.