Spray-dried microparticles of encapsulated gefitinib for slow-release localized treatment of periodontal disease.

Periodontal disease (PD) can be prevented by local or systemic application of epidermal growth factor receptor inhibitors (EGFRIs) that stabilize αvβ6 integrin levels in the periodontal tissue, leading to an increase in the expression of anti-inflammatory cytokines, such as transforming growth factor-β1. Systemic EGFRIs have side effects and, therefore, local treatment of PD applied into the periodontal pockets would be preferrable. Thus, we have developed slow-release three-layered microparticles of gefitinib, a commercially available EGFRI.

Gingival epithelial cell-derived microvesicles activate mineralization in gingival fibroblasts.

Soft tissue calcification occurs in many parts of the body, including the gingival tissue. Epithelial cell-derived MVs can control many functions in fibroblasts but their role in regulating mineralization has not been explored. We hypothesized that microvesicles (MVs) derived from gingival epithelial cells could regulate calcification of gingival fibroblast cultures in osteogenic environment.

Altered composition of the oral microbiome in integrin beta 6-deficient mouse.

In periodontal disease (PD), bacterial biofilms suppress β6 integrin expression transforming growth factor-β1 signaling, resulting in gingival inflammation and bone loss. β6 integrin-null ( ) mice develop spontaneous PD. The aim of this study was to unravel potential differences in oral microbiome in wild-type (WT) and FVB mice.

Leucocyte- and platelet-rich fibrin regulates expression of genes related to early wound healing in human gingival fibroblasts.

Background: Leucocyte- and platelet-rich fibrin (L-PRF) is a blood-derived biomaterial rich in leucocytes and platelets embedded in a high-density fibrin network that can be compressed into a membrane and used in surgical applications to stimulate tissue regeneration and wound healing, especially in oral cavity. This study aimed to determine the combined effects of the growth factors and cells present in L-PRF on fibroblasts that directly face the L-PRF membranes placed during surgical procedures.

Methods: The effect of L-PRF from six donors on the expression of 84 key wound healing genes in normal human gingival fibroblasts was tested by RT-qPCR.

Epidermal growth factor receptor signaling suppresses αvβ6 integrin and promotes periodontal inflammation and bone loss.

In periodontal disease (PD), bacterial biofilms cause gingival inflammation, leading to bone loss. In healthy individuals, αvβ6 integrin in junctional epithelium maintains anti-inflammatory transforming growth factor-β1 (TGF-β1) signaling, whereas its expression is lost in individuals with PD. Bacterial biofilms suppress β6 integrin expression in cultured gingival epithelial cells (GECs) by attenuating TGF-β1 signaling, leading to an enhanced pro-inflammatory response.

Inflammasome and cytokine expression profiling in experimental periodontitis in the integrin β6 null mouse.

Epithelial αvβ6 integrin participates in immune surveillance in many organs, including the gastrointestinal track. Expression of αvβ6 integrin is reduced in the junctional epithelium of the gingiva in periodontal diseases, and mutations in the ITGB6 gene are associated with these diseases in humans and mice. The aim of this study was to unravel potential differences in the inflammatory responses in the periodontal tissues of FVB wild-type (WT) and β6 integrin-null (Itgb6) mice, using a ligature-induced periodontitis model and assessing inflammation, bone loss and expression profiles of 34 genes associated with periodontal disease.

Integrin αvβ6: Structure, function and role in health and disease.

Integrins are cell surface receptors that traditionally mediate cell-to-extracellular matrix and cell-to-cell adhesion. They can, however, also bind a large repertoire of other molecules. Integrin αvβ6 is exclusively expressed in epithelial cells where it can, for example, serve as a fibronectin receptor.

Suppression of αvβ6 Integrin Expression by Polymicrobial Oral Biofilms in Gingival Epithelial Cells.

Periodontal diseases manifest by the formation of deep pockets between the gingiva and teeth where multispecies bacterial biofilms flourish, causing inflammation and bone loss. Epithelial cell receptor αvβ6 integrin that regulates inflammation by activating the anti-inflammatory cytokine transforming growth factor-β1, is highly expressed in healthy junctional epithelium that connects the gingiva to the tooth enamel. However, its expression is attenuated in human periodontal disease.

Elevated CD26 Expression by Skin Fibroblasts Distinguishes a Profibrotic Phenotype Involved in Scar Formation Compared to Gingival Fibroblasts.

Compared to skin, wound healing in oral mucosa is faster and produces less scarring, but the mechanisms involved are incompletely understood. Studies in mice have linked high expression of CD26 to a profibrotic fibroblast phenotype, but this has not been tested in models more relevant for humans. We hypothesized that CD26 is highly expressed by human skin fibroblasts (SFBLs), and this associates with a profibrotic phenotype distinct from gingival fibroblasts (GFBLs).

Epithelial Microvesicles Promote an Inflammatory Phenotype in Fibroblasts.

Microvesicles (MVs) are extracellular vesicles secreted by various cell types that are involved in intercellular communication. We hypothesized that in human periodontal disease, the pocket epithelium releases MVs, which then modulate gene expression in the underlying fibroblasts to control periodontal inflammation. MVs were isolated from culture medium of gingival epithelial cells (GECs) treated with oral bacterial biofilm extract or left untreated.

Keratinocyte Microvesicles Regulate the Expression of Multiple Genes in Dermal Fibroblasts.

Extracellular vesicles released from cells regulate many normal and pathological conditions. Little is known about the role of epidermal keratinocyte microvesicles (KC-MVs) in epithelial-stromal interaction that is essential for wound healing. We investigated, therefore, whether MV-like structures are present in human wounds and whether they affect wound healing-associated gene expression in dermal fibroblasts.

Integrins in Wound Healing.

Regulation of cell adhesions during tissue repair is fundamentally important for cell migration, proliferation, and protein production. All cells interact with extracellular matrix proteins with cell surface integrin receptors that convey signals from the environment into the nucleus, regulating gene expression and cell behavior. Integrins also interact with a variety of other proteins, such as growth factors, their receptors, and proteolytic enzymes.

Integrins in periodontal disease.

Cell surface integrin receptors mediate cell adhesion, migration and cellular signaling in all nucleated cells. They are activated by binding to extracellular ligands or by intracellular proteins, such as kindlins that engage with their cytoplasmic tails. Cells in the periodontal tissues express several integrins with overlapping ligand-binding capabilities.

Critical role for αvβ6 integrin in enamel biomineralization.

Tooth enamel has the highest degree of biomineralization of all vertebrate hard tissues. During the secretory stage of enamel formation, ameloblasts deposit an extracellular matrix that is in direct contact with the ameloblast plasma membrane. Although it is known that integrins mediate cell-matrix adhesion and regulate cell signaling in most cell types, the receptors that regulate ameloblast adhesion and matrix production are not well characterized.

Epithelial integrins with special reference to oral epithelia.

Adhesion of epithelium to the extracellular matrix is crucial for the maintenance of systemic and oral health. In the oral cavity, teeth or artificial dental implants penetrate the soft tissue of the gingiva. In this interface, gingival soft tissue needs to be well attached via the epithelial seal to the tooth or implant surface to maintain health.

Localization and potential function of kindlin-1 in periodontal tissues.

Kindlin-1 is an intracellular focal adhesion protein that regulates the actin cytoskeleton. Patients suffering from Kindler syndrome have a homologous mutation of the kindlin-1 gene and develop skin blisters, periodontal disease, and intestinal complications because of deficient adhesion of the basal epithelial cells. We investigated kindlin-1 localization in periodontal tissue and its functions in cultured keratinocytes and showed that kindlin-1 co-localizes with migfilin and paxillin in the basal epithelial cells of oral mucosa and in cultured keratinocytes.

Absence of alphavbeta6 integrin is linked to initiation and progression of periodontal disease.

Integrin alphavbeta6 is generally not expressed in adult epithelia but is induced in wound healing, cancer, and certain fibrotic disorders. Despite this generalized absence, we observed that alphavbeta6 integrin is constitutively expressed in the healthy junctional epithelium linking the gingiva to tooth enamel. Moreover, expression of alphavbeta6 integrin was down-regulated in human periodontal disease, a common medical condition causing tooth loss and also contributing to the development of cardiovascular diseases by increasing the total systemic inflammatory burden.

Expression of Endo180 is spatially and temporally regulated during wound healing.

Aims: Interactions of cells with the extracellular matrix are important for normal wound healing and may play a role in scar formation. Remarkably, wound healing in human gingiva does not result in scar formation and serves as a model for wound regeneration. Endo180 (CD280) is a cell surface receptor that has novel functions to regulate cell migration and bind and internalize collagens that are key processes in wound healing.

HaCaT keratinocyte migration is dependent on epidermal growth factor receptor signaling and glycogen synthase kinase-3alpha.

After epithelial disruption by tissue injury, keratinocytes migrate from the wound edge into a provisional matrix. This process is stimulated by growth factors that signal through epidermal growth factor (EGF) receptor, including EGF, heparin-binding EGF-like growth factor (HB-EGF) and transforming growth factor-alpha (TGF-alpha), and by for example keratinocyte growth factor (KGF) and TGF-beta1 that function through different receptors. We have previously shown that keratinocyte migration induced by EGF or staurosporine is dependent on the activity of glycogen synthase kinase-3 (GSK-3).

Bacterial heat shock protein 60 may increase epithelial cell migration through activation of MAP kinases and inhibition of alpha6beta4 integrin expression.

Exogenous heat shock proteins may modify cell behavior of infected epithelium. The effect of heat shock protein 60 (hsp60) of Actinobacillus actinomycetemcomitans and Escherichia coli, and human recombinant hsp60 on migration of HaCaT skin keratinocytes was studied using the Boyden chamber assay. Hsp60 from different species increased cell migration by two- to fivefold and this effect was inhibited by ERK inhibitor PD 98059, p38 inhibitor SB 203580, and a function-blocking epidermal growth factor receptor (EGFR) antibody.

Glycogen synthase kinase-3 regulates cytoskeleton and translocation of Rac1 in long cellular extensions of human keratinocytes.

Wound keratinocytes form long cellular extensions that facilitate their migration from the wound edge into provisional matrix. We have previously shown that similar extensions can be induced by a long-term exposure to EGF or rapidly by staurosporine in cultured cells. This morphological change depends on the activity of glycogen synthase kinase-3 (GSK-3).

Increased expression of beta6-integrin in skin leads to spontaneous development of chronic wounds.

Integrin alphavbeta6 is an epithelial cell-specific receptor that is not normally expressed by resting epithelium but its expression is induced during wound healing. The function of alphavbeta6-integrin in wound repair is not clear. In the present study, we showed that beta6-integrin expression was strongly up-regulated in the epidermis in human chronic wounds but not in different forms of skin fibrosis.

Glycogen synthase kinase-3 regulates formation of long lamellipodia in human keratinocytes.

During wound healing, keratinocytes initiate migration from the wound edge by extending lamellipodia into a fibronectin-rich provisional matrix. While lamellipodia-like structures are also found in cultured keratinocytes exposed to epidermal growth factor (EGF), the signaling pathway that regulates the formation of these structures is not defined. In cultured human keratinocytes seeded on fibronectin, we found that protein-serine/threonine kinase inhibitors including staurosporine, induced concentration-dependent formation of extended lamellipodia (E-lams).

An improved method for culture of epidermal keratinocytes from newborn mouse skin.

Reproducible isolation and long term culture of epidermal keratinocytes from transgenic mouse lines is critically needed but most techniques have been unsuccessful. In this report we describe in detail a simplified method to isolate putative keratinocyte stem cells from newborn mouse skin and to maintain them for long term in culture. The cell cultures were established by enzymatically separating keratinocytes from newborn mouse skin.

Integrins alpha5beta1, alphavbeta1, and alphavbeta6 collaborate in squamous carcinoma cell spreading and migration on fibronectin.

The expression of alphavbeta6 fibronectin/tenascin receptor integrin is induced in malignant transformation of oral epithelium. In this study, we demonstrate the contribution of alphavbeta6 as well as other fibronectin receptor integrins in squamous cell carcinoma (SCC) cell adhesion and migration. Of 11 SCC cell lines isolated from the head and neck area, 8 (73%) expressed alphavbeta6 integrin on the cell surface.