Different growth properties in response to epidermal growth factor and interleukin-6 of primary keratinocytes derived from normal and psoriatic lesional skin

Topical cell-free conditioned media harvested from adipose tissue-derived stem cells promote recovery from corneal epithelial defects caused by chemical burns

Corneal chemical burns can lead to blindness following serious complications. As most of these complications are caused by failure of reepithelization during the acute phase, treatment at this stage is critical. Although there have been some studies on corneal injury recovery using adipose tissue-derived stem cells (ADSCs), none has reported the effect of topical cell-free conditioned culture media (CM) derived from ADSCs on corneal epithelial regeneration. Here, the best conditions for CM were selected and used for in vitro and in vivo experiments. Corneal burn in rats was induced using 100% alcohol. The chosen CM was administered to corneal burn rats (CM-treated [CT] group) four times a day for three days and this group was compared with the normal control and corneal burn (CB) groups. Biomicroscopic fluorescence images and the actual physical corneas were taken over time and used for analysis. mRNA levels of hepatocyte growth factor and epidermal growth factor (EGF) were significantly increased, whereas those of vascular endothelial growth factor, interleukin (IL)-1β, IL-6, IL-10, and matrix metalloproteinase-9 were significantly decreased in the CT group compared with those in the CB group. The numbers of proliferating cell nuclear antigen- and zonular occludens-1-positive cells in the CT group were significantly higher than those in the CB group. The macrophage-infiltrating corneas in the CT group expressed significantly more of the M2 marker arginase than corneas in the CB group. Optimal CM (× 0.5 concentration) treatment significantly accelerated the migration of corneal epithelial cells and induced upregulation of the expression of IL-6, EGF, and C-X-C chemokine receptor type 4 mRNAs. Overall, in this study, topical administration of cell-free CM promoted regeneration of the corneal epithelium after induction of chemical burns.

Cell Interactions with Vascular Regenerative MAA-Based Materials in the Context of Wound Healing

In diabetic patients the development of chronic non-healing wounds is a common complication. A methacrylic acid-based biomaterial is a vascular regenerative material that enhances diabetic healing without the use of cells or growth factors. The bioactive nature of this material is thought to be associated with its anionic charge or surface chemistry. Contact between the methacrylic acid-based biomaterial and tissue begins with protein (including complement) adsorption and is followed by interaction of the biomaterial with resident and infiltrating cells in the wound bed (e.g., macrophages and endothelial cells). This results in changes to their surface receptors to activate phosphorylation cascades that lead to differential activation of signalling pathways such as those involving osteopontin and sonic hedgehog. These changes modulate the phenotype of the cells in the wound bed, eventually improving vessel formation and wound healing. Understanding the molecular and cellular mechanisms will have broad implications for biomaterials, not just the methacrylic acid-based material, and will facilitate the advancement of regenerative biomaterials for diverse applications.

[Psoriasis: physiopathology and immunogenetics]

Psoriasis is a multifactorial disease that involves genetic, immunological and environmental factors. During the last decade, several studies by genome scan on families or cases/controls helped to highlight more than ten loci "PSORS" located on different chromosomes and containing several candidate genes. Psoriasis appears as a genetic disease that follows the mixed model with the involvement of a major gene (PSORS1) and a set of minor genes with a variable penetrance depending on the locus. Genetic data have focused on the involvement of the immune system in the pathogenesis of psoriasis. It is now accepted that psoriasis is an immunological disease involving the response profiles TH1 and TH17. Much remains to be done to better elucidate the mechanisms involved in the genesis of psoriatic lesions to find new therapeutic targets.

CELL PROLIFERATION AND CYTOKINE INDUCTION BY TNF-alpha OF PSORIATIC KERATINOCYTES ARE NOT DIFFERENT FROM NORMAL KERATINOCYTES IN VITRO

BACKGROUND

Recent studies indicate that various cytokines including tumor necrosis factor-alpha (TNF-alpha) play an essential role in the induction and maintenance of psoriatic lesion.

AIMS

To compare the cell proliferation of keratinocytes by various cytokines and TNF-alpha-induced cytokine secretion among normal keratinocytes, uninvolved, and involved keratinocytes.

METHODS

The keratinocytes from normal skin, uninvolved, and involved psoriasis were cultured in the presence of IL-6, IL-8, epidermal growth factor (EGF), hepatocyte growth factor (HGF), transforming growth factor-alpha (TGF-alpha) epiregulin, amphiregulin, and TNF-alpha and then MTT assay for keratinocytes proliferation was performed. Furthermore, TNF-alpha-induced secretion of IL-6, IL-8, EGF, HGF, TGF-alpha, epiregulin, and amphiregulin were compared among these keratinocytes.

RESULTS

IL-6, IL-8, EFG, TGF-alpha, epiregulin, and amphiregulin, but not TNF-alpha increased keratinocyte proliferation of normal, psoriatic uninvolved, and involved skin. The increased cell proliferation by these cytokines and growth factors were not different among the keratinocytes derived from normal skin, uninvolved, and involved psoriasis. The significant induction of TNF-alpha increased IL-6, IL-8, EGF, HGF, TGF-alpha, epiregulin, and amphiregulin, but the increase in these cytokines and growth factors were not different among normal skin, uninvolved, and involved psoriasis.

CONCLUSION

Cell proliferation by various cytokines and growth factors and TNF-alpha-induced cytokine secretion are not different between normal and psoriatic keratinocytes.

The Development and Characterization of an In Vitro Model of Psoriasis

In this study, the phenotype of psoriatic keratinocytes and fibroblasts in reconstructed skin models was compared to those constructed from normal cells. Characterization of this model by immunohistochemistry showed that classical markers of keratinocyte differentiation exhibited similar patterns of distribution in the psoriatic models to those derived from normal cells and generally reflected in vivo observations. Some crucial differences, however, were observed between normal and psoriatic models when pro-inflammatory gene expression and keratinocyte proliferation were investigated. Notably, the chemokine receptor CXCR2 was overexpressed in the psoriatic models, and, moreover, was localized to the granular layer of keratinocytes as seen in psoriasis in vivo. Pro-inflammatory genes (tumor necrosis factor alpha [TNF-alpha], interferon gamma [IFN-gamma], and interleukin 8 [IL-8]) were expressed at high levels in the psoriatic models, but were only minimally expressed in the normal models. Models derived from uninvolved psoriatic skin showed the same gene expression profile as those derived from involved skin along with an increased proliferation rate when compared to normal models. These results suggest that psoriatic individuals possess an inherent predisposition to develop the disease phenotype even in the absence of T cells. This study represents a comprehensive characterization of psoriatic human skin reconstructed in vitro, and demonstrates the potential of this model as a valuable tool in drug discovery.

Estrogen Suppression Induces Papillary Gingival Overgrowth in Pregnant Baboons

BACKGROUND

Alterations in sex steroids during pregnancy are associated with the development and exacerbation of reactive lesions involving the gingiva. Currently, few experimental animal models similar to humans are available to examine regulatory pathways involving sex steroids and the periodontium.

METHODS

In the present study, we used the baboon as a novel experimental model for the study of the regulatory actions of estrogen on the periodontium during pregnancy. Pregnant baboons (N = 5) were administered the potent, highly specific aromatase inhibitor CGS 20267 (2 mg/day subcutaneously) daily on days 60 through 165 of gestation (term = 184). Untreated females (N = 10) and females (5) concomitantly administered aromatase inhibitor and estradiol benzoate (2.0 mg/day each subcutaneously) served as controls. Gingival biopsies were taken between days 145 and 165 of gestation.

RESULTS

Administration of CGS 20267 in all females suppressed maternal serum concentrations of estradiol by 95% and induced the development of an exuberant papillomatous enlargement of the gingiva by gestational day 110, with the most prominent development involving the labial aspects of the anterior sextants. None of the untreated pregnant controls or females concomitantly administered aromatase inhibitor and estradiol benzoate developed gingival overgrowth. Thus, estradiol alone prevented the onset of gingival overgrowth induced by estrogen suppression. In all baboons, discontinuation of the aromatase inhibitor at time of cesarean section resulted in spontaneous regression and resolution of the papillomatous hyperplasia within 4 to 6 weeks. Clinically, the gingival papillary overgrowth was erythematous and edematous, with a propensity toward spontaneous subgingival hemorrhage. Histologically, the biopsy specimens demonstrated hyperplasia of the epithelium typified by mild hyperkeratosis, acanthosis, and elongation and isolated anastamoses of rete ridges. Subjacent to the intact epithelium was a loose connective tissue stroma with isolated areas of inflammatory cell infiltrate. Special stains verified the presence of isolated bacterial biofilms; however, no evidence of fungal filaments was present. Histological features suggestive of viral infection were notably absent in the epithelium. No evidence of viral particles or capsids was identified using transmission electron microscopy. Reverse transcription polymerase chain reaction analysis, using a panel of degenerate primers, was negative for papilloma family viruses.

CONCLUSIONS

These results are consistent with a significant role for estrogen during primate pregnancy in the regulation of cellular proliferation and differentiation within the gingiva. The baboon represents an important experimental model for studying the regulatory actions of estrogen on the periodontium during pregnancy.

Interleukin 6 Indirectly Induces Keratinocyte Migration

IL-6-deficient transgenic mice (IL-6 KO) display significantly delayed cutaneous wound healing. To further elucidate the role of IL-6 in skin wound healing, epidermal keratinocyte and dermal fibroblast cells were isolated from neonatal IL-6 KO mice and treated with rmIL-6. It was found that rmIL-6 alone did not significantly modulate the proliferation or migration of cultured IL-6 KO keratinocytes. rmIL-6, however, significantly induced the migration of IL-6 KO keratinocytes (up to 5-fold) when co-cultured with dermal fibroblasts. Culture supernatants from IL-6-treated fibroblasts were also found to induce the migration of keratinocytes to a similar degree. Genomics analysis of treated fibroblasts indicated that rmIL-6 does not induce any known soluble keratinocyte migratory factors. rmIL-6 treatment of fibroblast, however, induced a rapid and sustained phosphorylation of STAT3 protein. These data indicate that IL-6 could influence wound healing by inducing keratinocyte migration through the production of a soluble fibroblast-derived factor, and its activity may be associated with STAT3 activation.

The immunology of psoriasis and biologic immunotherapy

In this review, we will discuss the immunological basis for psoriasis with special emphasis on the role of effector T cells. With the understanding of this immunologic process, we will present a model for the development of targeted immune response modifiers, termed biologic immunotherapies, and their potential role for the benefit of patients with psoriasis.

Autoantibodies to the epidermal growth factor receptor in systemic sclerosis, lupus, and autoimmune mice

Autoantibodies to the recombinant extracellular domain of epidermal growth factor receptor (exEGFR) were detected by ELISA in the serum of Fas-defective old MRL/MpJ/lpr and C3H/HeJ/gld mice, but not young mice from these strains, or nonautoimmune young and old BALB/c, MRL/MpJ/++, and C3H/HeJ/MMTV mice. Compared with control human subjects without autoimmune disease, the frequency of exEGFR-binding autoantibodies was increased in scleroderma (systemic sclerosis) patients and to a lesser extent in lupus patients. Phage autoantibodies (Fv fragments) isolated from a lupus library by selection on a linear epitope of EGFR (residues 294-310) displayed the ability to bind exEGFR. Treatment of EGFR-expressing A431 cells with autoantibodies purified by affinity chromatography on immobilized exEGFR resulted in specific staining of the cells. Short-lived but strong inhibition of cellular DNA synthesis was observed in the presence of the autoantibodies. We concluded that autoantibody responses to EGFR hold the potential of fulfilling a pathogenic role in autoimmune disease.

Regulation and role of interleukin 6 in wounded human epithelial keratinocytes

Dermal wounding is accompanied by inflammation and the resulting proinflammatory cytokines, including interleukin (IL)-6, are thought to play an important role in the repair process. IL-6 is produced by normal human keratinocytes to various dermatological diseases and we have recently shown it is also required for normal wound repair. However, neither the events responsible for its induction nor its role in repair have been clearly identified. Using a recently developed in vitro wounding model, we demonstrate that IL-6 mRNA is expressed and immunoreactive IL-6 is released from cultures of human epidermal keratinocytes (NHEKs) following wounding. The transcription factors, NF kappa B and NF-IL-6 (C/EBP beta), which coordinately help regulate IL-6 expression, were activated following wounding and preceded the appearance of IL-6. Addition of IL-1 alpha to NHEK cultures increased IL-6 production and activated NF kappa B and C/EBP beta. Addition of the IL-1 alpha receptor antagonist inhibited both IL-6 mRNA expression and the transcription factors following wounding. Immunoreactive IL-1 alpha was detected in the medium following wounding in the absence of new message. Furthermore, addition of IL-6 to NHEK cultures decreased the expression of keratins 1 and 10, differentiation markers of keratinocytes, while proliferation was not affected. Taken together, these data indicate that constitutive keratinocyte-derived IL-1 alpha is a stimulus for IL-6 production in wounded epidermis, the response involves NF kappa B and C/EBP beta transcription factors, and IL-6 may be associated with modulation of keratinocyte differentiation rather than proliferation.

Interleukin-6 treatment augments cutaneous wound healing in immunosuppressed mice

It has been postulated that the inflammatory response that occurs after cutaneous wounding is a prerequisite for healing and that inflammatory cytokines, such as interleukin-6 (IL-6) are involved in this process. We showed previously that IL-6-deficient mice display delayed wound healing, which could be reversed by administration of a murine IL-6 expression plasmid or recombinant murine IL-6 (rMuIL-6). In the present study, we observed that delayed cutaneous wound healing, which occurs as a result of glucocorticoid-induced immunosuppression, can also be reversed by rMuIL-6, as evidenced by epithelialization, granulation tissue formation, and wound closure. In vehicle control mice, rMuIL-6 did not augment healing but rather delayed the process. Immunochemical studies indicated that the expression of matrix metalloproteinase-10 (MMP-10) was increased in dexamethasone-treated mice and that rMuIL-6 treatment reduced its expression, indicating that IL-6 may influence dermal matrix formation and, specifically, collagen synthesis. These results demonstrate that IL-6 can restore abnormal wound repair that occurs in immunodeficiency and suggest its use as a potential therapy.

Chromosome 7 aneusomy. A marker for metastatic melanoma? Expression of the epidermal growth factor receptor gene and chromosome 7 aneusomy in nevi, primary malignant melanomas and metastases

Receptor tyrosine kinases such as the epidermal growth factor receptor (EGFR) play an important role in a variety of malignant neoplasias, making the search for aberrations in the relevant chromosomes an important issue. Differential expression of the EGFR gene was investigated by reverse transcriptase (RT)-PCR on tissue samples of normal skin, nevi, primary melanomas, and melanoma metastases. The EGFR gene is located on chromosome 7p12.3-p12.1. To determine the number of chromosomes 7 in cell nuclei of the mentioned tissue samples we performed fluorescence in situ hybridization (FISH) on touch preparations, using a DNA probe that hybridizes specifically to the centromeric region of chromosome 7. Additionally, chromosome 7 number in interphase nuclei was determined in short-term primary cell cultures of nevi, primary melanomas, and metastases. The highest EGFR gene expression frequency was found in melanoma metastases. By FISH we detected the highest fraction of cell nuclei with more than two chromosomes 7 in the group of metastases. Our results suggest that overexpression of the EGFR gene might play an important role in metastasis of malignant melanoma. This is well reflected by polysomy 7, possibly accounting for an increased EGFR gene copy number.

Identification of a novel psoriasis susceptibility locus at 1p and evidence of epistasis between PSORS1 and candidate loci

The pathogenesis of all forms of psoriasis remains obscure. Segregation analysis and twin studies together with ethnic differences in disease frequency all point to an underlying genetic susceptibility to psoriasis, which is both complex and likely to reflect the action of a number of genes. We performed a genome wide analysis using a total of 271 polymorphic autosomal markers on 284 sib relative pairs identified within 158 independent families. We detected evidence for linkage at 6p21 (PSORS1) with a non-parametric linkage score (NPL)=4.7, p=2 x 10(-6) and at chromosome 1p (NPL=3.6, p=1.9 x 10(-4)) in all families studied. Significant excess (p=0. 004) paternal allele sharing was detected for markers spanning the PSORS1 locus. A further three regions reached NPL scores of 2 or greater, including a region at chromosome 7 (NPL 2.1), for which linkage for a number of autoimmune disorders has been reported. Partitioning of the data set according to allele sharing at 6p21 (PSORS1) favoured linkage to chromosomes 2p (NPL 2.09) and 14q (NPL 2.0), both regions implicated in previous independent genome scans, and suggests evidence for epistasis between PSORS1 and genes at other genomic locations. This study has provided linkage evidence in favour of a novel susceptibility locus for psoriasis and provides evidence of the complex mechanisms underlying the genetic predisposition to this common skin disease.

Impaired cutaneous wound healing in interleukin-6-deficient and immunosuppressed mice

It has been postulated that an inflammatory response after cutaneous wounding is a prerequisite for healing, and inflammatory cytokines, such as interleukin-6 (IL-6), might be intimately involved in this process. IL-6-deficient transgenic mice (IL-6 KO) displayed significantly delayed cutaneous wound healing compared with wild-type control animals, requiring up to threefold longer to heal. This was characterized by minimal epithelial bridge formation, decreased inflammation, and granulation tissue formation. Using electrophoretic mobility shift assays of wound tissue from IL-6 KO mice, decreased AP-1 transcription factor activation was shown compared with wild-type mice 16 h after wounding. In situ hybridization of wound tissue from wild-type mice revealed IL-6 mRNA expression primarily in the epidermis at the leading edge of the wound. Delayed wound healing in IL-6 KO mice was reversed with a single dose of recombinant murine IL-6 or intradermal injection of an expression plasmid containing the full-length murine IL-6 cDNA. Treatment with rmIL-6 also reconstituted wound healing in dexamethasone-treated immunosuppressed mice. The results of this study may indicate a potential use for IL-6 therapeutically where cutaneous wound healing is impaired.

Dermal fibroblasts are one of the therapeutic targets for topical application of 1alpha,25-dihydroxyvitamin D3: the possible involvement of transforming growth factor-beta induction

BACKGROUND

Transforming growth factor (TGF) -beta has been suggested to be an effective inhibitor for abnormal keratinocyte growth in psoriasis. As a majority of the secreted TGF-beta are biologically latent complexes, activation is essential for TGF-beta-mediated cellular responses in vitro and in vivo. Objectives Here we report the response of the TGF-beta regulation system to 1alpha,25-dihydroxyvitamin D3 [1,25(OH)2D3], an active vitamin D3 analogue Patients/methods We studied two types of fibroblasts derived from normal and psoriatic lesional skin, using an enzyme-linked immunosorbent assay and Northern blotting techniques.

RESULTS

1,25(OH)2D3 caused a dose-dependent induction of latent and active TGF-beta1 proteins in both cell cultures. The increases were significant over 72 h, but not within 48 h after stimulation. The time course of TGF-beta1 mRNA expression showed a biphasic response consisting of early ( approximately 1 h) and late phases ( approximately 96 h) of induction. Concomitant increases of TGF-beta2 and -beta3, other mammalian isoforms, were observed in the 1,25(OH)2D3-treated cells, but the kinetics were all different. Co-incubation with metabolic inhibitors, actinomycin D and cycloheximide, revealed that the early induction of TGF-beta1 mRNA by 1,25(OH)2D3 is dependent on de novo RNA synthesis, but not on RNA stabilization or protein synthesis. It seems likely to be a transient and negligible response given the absence of TGF-beta1 protein production. The late induction of TGF-beta1 mRNA was partially blocked by adding isoform-specific antibodies to TGF-beta1, -beta2 and -beta3, indicating TGF-beta autoregulation. Despite these marked responses, there were no significant differences in the TGF-beta expression between normal and psoriatic fibroblasts.

CONCLUSIONS

These results suggest that antiproliferative and anti-inflammatory effects of 1,25(OH)2D3 on psoriatic lesional skin may be mediated, at least in part, by a complex TGF-beta regulation in local dermal fibroblasts.

Induction of transcription factor AP-2 by inflammatory cytokines in human keratinocytes

Activator protein-2 is an important transcription factor for the activation of a number of genes. Here we report the induction of activator protein-2 in response to inflammatory cytokines such as interleukin-6 in keratinocytes. Immunoblotting and semiquantitative reverse transcriptase-polymerase chain reaction assays using normal human keratinocytes revealed that interleukin-6 caused a time- and concentration-dependent induction of activator protein-2 mRNA and protein. The increase of activator protein-2 mRNA was detected at 30 min after stimulation and that of activator protein-2 protein was at 2 h. Their levels were lower than the control levels at 24 h. The interleukin-6-dependent induction of activator protein-2 mRNA was completely blocked by adding actinomycin D, whereas it was approximately 50% affected by cycloheximide. Co-incubation with neutralizing antibodies against various inflammatory cytokines resulted in inhibition of the interleukin-6-dependent activator protein-2 induction at varying degrees, indicating an involvement of various cytokines in the activator protein-2 induction. The activator protein-2 induction was observed in keratinocytes derived from lesional skins with psoriasis or squamous cell carcinoma, and the high levels of activator protein-2 were histochemically detected in these lesions. Furthermore, a gel mobility shift assay using the nuclear extracts from interleukin-6-treated cells showed that interleukin-6 induced the functional activator protein-2 protein for the gene activation. These findings suggest a possible regulation mechanism of activator protein-2 through a complex cytokine system, which is conceivably the initial reaction leading to skin inflammation, and resultant keratinocyte growth and carcinogenesis.