Regulation of fibroblast-induced collagen gel contraction by interleukin-1beta

Malva sylvestris Inhibits Inflammatory Response in Oral Human Cells. An In Vitro Infection Model

The aim of this study was to investigate the in vitro anti-inflammatory activity of Malva sylvestris extract (MSE) and fractions in a co-culture model of cells infected by Aggregatibacter actinomycetemcomitans. In addition, we evaluated the phytochemical content in the extract and fractions of M. sylvestris and demonstrated that polyphenols were the most frequent group in all samples studied. An in vitro dual-chamber model to mimic the periodontal structure was developed using a monolayer of epithelial keratinocytes (OBA-9) and a subepithelial layer of fibroblasts (HGF-1). The invasive periodontopathogen A. actinomycetemcomitans (D7S-1) was applied to migrate through the cell layers and induce the synthesis of immune factors and cytokines in the host cells. In an attempt to analyze the antimicrobial properties of MSE and fractions, a susceptibility test was carried out. The extract (MIC 175 μg/mL, MBC 500μg/mL) and chloroform fraction (MIC 150 μg/mL, MBC 250 μg/mL) were found to have inhibitory activity. The extract and all fractions were assessed using a cytotoxicity test and results showed that concentrations under 100 μg/mL did not significantly reduce cell viability compared to the control group (p > 0.05, viability > 90%). In order to analyze the inflammatory response, transcriptional factors and cytokines were quantified in the supernatant released from the cells. The chloroform fraction was the most effective in reducing the bacterial colonization (p< 0.05) and controlling inflammatory mediators, and promoted the down-regulation of genes including IL-1beta, IL-6, IL-10, CD14, PTGS, MMP-1 and FOS as well as the reduction of the IL-1beta, IL-6, IL-8 and GM-CSF protein levels (p< 0.05). Malva sylvestris and its chloroform fraction minimized the A. actinomycetemcomitans infection and inflammation processes in oral human cells by a putative pathway that involves important cytokines and receptors. Therefore, this natural product may be considered as a successful dual anti-inflammatory-antimicrobial candidate.

Distinct phenotype and therapeutic potential of gingival fibroblasts

Gingiva of the oral mucosa provides a practical source to isolate fibroblasts for therapeutic purposes because the tissue is easily accessible, tissue discards are common during routine clinical procedures and wound healing after biopsy is fast and results in complete wound regeneration with very little morbidity or scarring. In addition, gingival fibroblasts have unique traits, including neural crest origin, distinct gene expression and synthetic properties and potent immunomodulatory functions. These characteristics may provide advantages for certain therapeutic approaches over other more commonly used cells, including skin fibroblasts, both in intraoral and extra-oral sites. However, identity and phenotype of gingival fibroblasts, like other fibroblasts, are still not completely understood. Gingival fibroblasts are phenotypically heterogeneous, and these…fibroblast subpopulations may play different roles in tissue maintenance, regeneration and pathologies. The purpose of this review is to summarize what is currently known about gingival fibroblasts, their distinct potential for tissue regeneration and their potential therapeutic uses in the future.

Alternatives for animal wound model systems

In this chapter a review of animal model systems already being utilized to study normal and pathologic wound healing is provided. We also go into details on alternatives for animal wound model systems. The case is made for limitations in the various approaches. We also discuss the benefits/limitations of in vitro/ex vivo systems bringing everything up to date with our current work on developing a cell-based reporter system for diabetic wound healing.

Small cytoskeleton-associated molecule, fibroblast growth factor receptor 1 oncogene partner 2/wound inducible transcript-3.0 (FGFR1OP2/wit3.0), facilitates fibroblast-driven wound closure

Wounds created in the oral cavity heal rapidly and leave minimal scarring. We have examined a role of a previously isolated cDNA from oral wounds encoding wound inducible transcript-3.0 (wit3.0), also known as fibroblast growth factor receptor 1 oncogene partner 2 (FGFR1OP2). FGFR1OP2/wit3.0 was highly expressed in oral wound fibroblasts without noticeable up-regulation of alpha-smooth muscle actin. In silico analyses, denaturing and nondenaturing gel Western blot, and immunocytology together demonstrated that FGFR1OP2/wit3.0 were able to dimerize and oligomerize through coiled-coil structures and appeared to associate with cytoskeleton networks in oral wound fibroblasts. Overexpression of FGFR1OP2/wit3.0 increased the floating collagen gel contraction of naïve oral fibroblasts to the level of oral wound fibroblasts, which was in turn attenuated by small-interfering RNA knockdown. The FGFR1OP2/wit3.0 synthesis did not affect the expression of collagen I as well as procontractile peptides such as alpha-smooth muscle actin, and transforming growth factor-beta1 had no effect on FGFR1OP2/wit3.0 expression. Fibroblastic cells derived from embryonic stem cells carrying FGFR1OP2/wit3.0 (+/-) mutation showed significant retardation in cell migration. Thus, we postulate that FGFR1OP2/wit3.0 may regulate cell motility and stimulate wound closure. FGFR1OP2/wit3.0 was not up-regulated during skin wound healing; however, when treated with FGFR1OP2/wit3.0 -expression vector, the skin wound closure was significantly accelerated, resulting in the limited granulation tissue formation. Our data suggest that FGFR1OP2/wit3.0 may possess a therapeutic potential for wound management.

Substance P expression by human dental pulp fibroblasts: a potential role in neurogenic inflammation

Neurogenic inflammation describes the local release of neuropeptides, notably substance P (SP), from afferent neurons and might play a role in the pathogenesis of pulpal disease. The fibroblast is the most numerous cell type in the dental pulp, and recent work has suggested that it is involved in the inflammatory response. Primary pulp fibroblast cell populations were isolated by enzymatic digestion. Whole pulp tissue was obtained from freshly extracted sound (n = 35) and carious (n = 39) teeth. Expression of SP and neurokinin-1 receptor (NK-1) mRNA by pulp fibroblasts was determined by reverse transcriptase polymerase chain reaction (RT-PCR). SP was expressed by pulpal fibroblasts at both mRNA and protein levels. In addition, NK-1 mRNA and protein expression was detected in fibroblast cultures by RT-PCR and Western blotting, respectively. SP levels, determined by radioimmunoassay, were significantly greater (P < .05) in carious compared with sound teeth. These findings suggest that pulp fibroblasts play a role in neurogenic inflammation in pulpal disease.

Fetal Dermal Fibroblasts Retain a Hyperactive Migratory and Contractile Phenotype Under 2-and 3-Dimensional Constraints Compared to Normal Adult Fibroblasts

Fetal dermal fibroblasts participate in a dramatically different wound healing process compared to their adult counterparts, and it is thought that their intrinsic phenotype contributes to the unique properties of fetal repair. In particular, fibroblast migratory and contractile properties have been shown to be important in the development or lack of fibrosis/scarring. Despite extensive study to date, and multiple experimental techniques utilized by various laboratories, the precise differences between fetal and adult dermal fibroblasts remain unclear. We characterized the migratory and contractile dynamics of fetal dermal fibroblasts at the individual cell and population levels under both 2-dimensional (2D) and 3-dimensional (3D) constraints. Data indicate that (1) individual fetal fibroblasts attach and locomote quicker than adult fibroblasts, resulting in faster migration at the population level; (2) use of a 2D bioactive matrix (collagen) dramatically speeds up the transition from attachment to locomotion; and (3) fetal fibroblasts compact 2D collagen matrices faster than adult fibroblasts. These characteristics are maintained inside of a novel 3D construct, which approximates some in vivo tissue repair dynamics. Specifically, fetal fibroblasts invade this construct faster than adult fibroblasts, likely through more dynamic interactions with surrounding collagen fibers. In conclusion, the hyperactive migratory and contractile dynamics of fetal fibroblasts are qualitatively and quantitatively conserved despite transitions from individual cells to whole populations and from 2D to 3D constraints. We conclude that fetal fibroblasts display a robust phenotype, which is only partially altered by changes in substrate and geometric constraints. This phenotype likely is important in dictating the dynamics of fetal tissue repair.

Phenotypic differences between oral and skin fibroblasts in wound contraction and growth factor expression

Wounds of the oral mucosa heal in an accelerated fashion with reduced scarring compared with cutaneous wounds. The differences in healing outcome between oral mucosa and skin could be because of phenotypic differences between the respective fibroblast populations. This study compared paired mucosal and dermal fibroblasts in terms of collagen gel contraction, alpha-smooth muscle actin expression (alpha-SMA), and production of the epithelial growth factors: keratinocyte growth factor (KGF) and hepatocyte growth factor/scatter factor (HGF). The effects of transforming growth factor -beta1 and -beta3 on each parameter were also determined. Gel contraction in floating collagen lattices was determined over a 7-day period. alpha-SMA expression by fibroblasts was determined by Western blotting. KGF and HGF expression were determined by an enzyme-linked immunosorbent assay. Oral fibroblasts induced accelerated collagen gel contraction, yet surprisingly expressed lower levels of alpha-SMA. Oral cells also produced significantly greater levels of both KGF and HGF than their dermal counterparts. Transforming growth factor-beta1 and -beta3, over the concentration range of 0.1-10 ng/mL, had similar effects on cell function, stimulating both gel contraction and alpha-SMA production, but inhibiting KGF and HGF production by both cell types. These data indicate phenotypic differences between oral and dermal fibroblasts that may well contribute to the differences in healing outcome between these two tissues.

The fibroblast-populated collagen matrix as a model of wound healing: a review of the evidence

The fibroblast-populated collagen matrix (FPCM) has been utilized as an in vitro model of wound healing for more than 2 decades. It offers a reasonable approximation of the healing wound during the phases of established granulation tissue and early scar. The gross and microscopic morphology of the FPCM and the healing wound are similar at analogous phases. The processes of proliferation, survival/apoptosis, protein synthesis, and contraction act in similar directions in these two models, and the response to exogenous agents also is consistent between them. If its limitations are respected, then the FPCM can be used as a model of the healing wound.

Oral fibroblast expression of wound-inducible transcript 3.0 (wit3.0) accelerates the collagen gel contraction in vitro

Wounds of the oral mucosa show faster closure with less scar formation than skin wounds in other areas. A differentially expressed cDNA, wound-inducible transcript 3.0 (wit3.0), was isolated from oral mucosal wound in rats (Sukotjo, C., Abanmy, A. A., Ogawa, T., and Nishimura, I. (2002) J. Dent. Res. 81, 229-235). The purpose of this study was to characterize the wit3.0 gene structure and the function of its deduced peptide. Human and rat genome databases revealed that the gene for wit3.0 was located in human chromosome 12p11.23 and rat chromosome 4q44. Its human and rat gene structures were well conserved, composed of 7 exons spread over 20 kb. Exon 5 was alternatively spliced generating two transcripts encoding deduced peptides of 215 and 253 amino acids (wit3.0 alpha and wit3.0 beta, respectively). The protein families data base of alignments (Pfam) analysis suggested the wit3.0 peptide sequence shared similarity with a portion of the myosin II coiled-coil domain consensus sequence. Fibroblasts isolated from the rat oral wound up-regulated wit3.0 expression and exhibited greater ability to contract collagen gel in vitro than fibroblasts isolated from untreated oral mucosa/gingiva. NIH3T3 and rat oral fibroblasts transfected with expression vector containing the coding sequences of wit3.0 alpha or wit3.0 beta increased in vitro collagen gel contraction. When treated with TGF beta-1, NIH3T3 fibroblast expression of wit3.0 showed no significant change, whereas alpha smooth muscle actin was increased in a dose-dependent manner. These data suggest that there may be a novel wound healing pathway involving wit3.0 underlying the favorable early wound closure characteristics of oral mucosa.

Construction of large area organotypical cultures of oral mucosa and skin

BACKGROUND

Skin and oral mucosal keratinocytes grown in vitro usually lose their normal patterns of differentiation, unless grown as organotypical cultures that are constructed by allowing collagen gels containing fibroblasts to contract before they are plated with keratinocytes and raised to the air/medium interface. However, the contraction process tends to produce small irregular cultures.

METHODS

To generate uniformly differentiating large cultures, we have investigated several aspects of the factors involved in the culture construction. By adjusting the number of fibroblasts used and by plating the matrices with keratinocytes prior to contraction, cultures of up to 72 cm2 were constructed.

RESULTS

The cultures retained almost the full surface areas of the original matrices and showed uniform patterns of epithelial plating and differentiation. Immunostaining for cytokeratins and integrins indicated restoration of in vitro phenotypes similar to those of the epithelial tissues of origin.

CONCLUSIONS

These methods successfully generate cultures required for certain types of investigations and tissues that are suitable for clinical use as grafts.

Differences in mesenchymal tissue repair

Variations in certain mesenchymal tissue healing processes are not widely recognized. The current review summarizes key differences in healing mechanisms and healing potential after injury to soft tissues having different healing outcomes.

Secretory leukocyte protease inhibitor is a novel inhibitor of fibroblast-mediated collagen gel contraction

Cultured epithelial cells, including those from the oral epithelium, have been successfully applied in the promotion of scarless wound healing. Factors released from the epithelial cells are thought to contribute significantly to the beneficial effects. In the conditioned medium of human oral epithelial cells, we found a factor that inhibited fibroblast-mediated collagen gel contraction, an in vitro model of wound healing and scar formation. Biochemical analysis identified the factor to be human secretory leukocyte protease inhibitor (SLPI). Fibroblasts transfected with SLPI cDNA showed reduced gel-contracting activity. SLPI purified from the conditioned medium inhibited gel contraction in a dose-dependent manner, and anti-SLPI antibody counteracted this activity. Upon SLPI treatment, human skin fibroblasts in collagen gel became shorter in length and were inhibited in pseudopodia extension. Furthermore, after SLPI treatment, alpha(1)-integrin immunoreactivity decreased, and cyclic AMP levels increased. Excessive gel contraction was observed when fibroblasts treated with TGF-beta1 and fibroblasts from hypertrophic and from keloid scar tissue were cultured in collagen gel. SLPI was also effective in inhibiting gel contraction in the above three models of scar formation. These results suggest that SLPI may be useful in promoting scarless wound healing.