Differential localization of TGF-beta-precursor isotypes in normal human skin

Effects of sevoflurane on collagen production and growth factor expression in rats with an excision wound

BACKGROUND

Sevoflurane is a widely used inhalation anesthetic, but there are no studies on its effect on the wound-healing process. This study was undertaken to evaluate the effect of exposure time to sevoflurane on wound healing.

METHOD

Male Sprague-Dawley rats were used. Two circular full-thickness skin defects 8 mm in diameter were made on the dorsum of the rats. The animals were divided into six groups according to exposed gas type and time: S1 (sevoflurane, 1 h), S4 (sevoflurane, 4 h), S8 (sevoflurane, 8 h), O1 (oxygen, 1 h), O4 (oxygen, 4 h), and O8 (oxygen, 8 h). The surface area of the wounds was measured 0, 1, 3, and 7 days after surgery. Separately, the mean blood pressures (MBP) and arterial oxygen pressures (PaO(2)) were monitored during the sevoflurane exposure. Collagen type I production and transforming growth factor-beta1 (TGF-beta1) and basic fibroblast growth factor (bFGF) expression on the wound surface were analyzed. Routine histological analysis was also performed.

RESULT

Exposure duration to sevoflurane had no influence on MBP and PaO(2). The reduction in wound size and collagen type I production was delayed in S8. The expression of TGF-beta1 and bFGF on the wound surface in S8 was significantly attenuated in S8. The histology of the S8 demonstrated a delayed healing status.

CONCLUSIONS

Prolonged exposure to sevoflurane might alter the inflammatory phase of the wound-healing process by attenuation of growth factor expression such as TGF-beta1 and bFGF and subsequently by reduced collagen production.

Embryoid body attachment to reconstituted basement membrane induces a genetic program of epithelial differentiation via jun N-terminal kinase signaling

Embryonic stem (ES) cells are derived from early stage mammalian embryos and have broad developmental potential. These cells can be manipulated experimentally to generate cells of multiple tissue types which could be important in treating human diseases. The ability to produce relevant amounts of these differentiated cell populations creates the basis for clinical interventions in tissue regeneration and repair. Understanding how embryonic stem cells differentiate also can reveal important insights into cell biology. A previously reported mouse embryonic stem cell model demonstrated that differentiated epithelial cells migrated out of embryoid bodies attached to reconstituted basement membrane. We used genomic technology to profile ES cell populations in order to understand the molecular mechanisms leading to epithelial differentiation. Cells with characteristics of cultured epithelium migrated from embryoid bodies attached to reconstituted basement membrane. However, cells that comprised embryoid bodies also rapidly lost ES cell-specific gene expression and expressed proteins characteristic of stratified epithelia within hours of attachment to basement membrane. Gene expression profiling of sorted cell populations revealed upregulation of the BMP/TGFbeta signaling pathway, which was not sufficient for epithelial differentiation in the absence of basement membrane attachment. Activation of c-jun N-terminal kinase 1 (JNK1) and increased expression of Jun family transcription factors was observed during epithelial differentiation of ES cells. Inhibition of JNK signaling completely blocked epithelial differentiation in this model, revealing a key mechanism by which ES cells adopt epithelial characteristics via basement membrane attachment.

A role for TGFbeta signaling in the pathogenesis of psoriasis

Deregulation of transforming growth factor-beta (TGFbeta) signaling has been reported in human psoriasis. Our recent study using a keratin 5 promoter (K5.TGFbeta1(wt)) showed that transgenic mice expressing wild-type TGFbeta1 in the epidermis developed severe skin inflammation. Additional experimental data further support a direct role for TGFbeta1 overexpression in skin inflammation. First, we temporally induced TGFbeta1 expression in keratinocytes in our gene-switch TGFbeta1(wt) transgenic mice and found inflammation severity correlated with TGFbeta1(wt) transgene expression. Second, deletion of T cells in K5.TGFbeta1(wt) mice significantly delayed skin inflammation and associated epidermal hyperplasia/hyperkeratosis. Third, therapeutic approaches effective for human psoriasis, that is, Etanercept and Rosiglitazone, are effective in alleviating the symptoms observed in K5.TGFbeta1(wt) mice. Future studies will analyze specific mechanisms and identify key factors in TGFbeta1-induced skin inflammation. Our mouse models will provide a useful tool for understanding the molecular mechanisms of inflammatory skin disorders in which TGFbeta1 is overexpressed.

Effects of sevoflurane on wound healing process

BACKGROUND

Wound healing process is a tissue response to trauma which leads to tissue repair through complex biological stages. Sevoflurane is a widely used inhalation anesthetic for surgery, but there has been no study about its effect on wound healing process. This study was undertaken to evaluate the effect of sevoflurane on wound healing process.

METHODS

Male Sprague-Dawley rats (200-300 g) were used. Two circular full-thickness skin defects of 8 mm in diameter were made on dorsum of rats. After wound formation, the animals were divided into 4 groups: 1, 2, 4, 8 hr exposure to sevoflurane, respectively. Wound sizes and regional blood flow around the wounds were measured. The expression of basic fibroblast growth factor (bFGF), transforming growth factor beta1 (TGFbeta1), collagen 1, and collagen 3 mRNA were detected 7 days after wound formation by real-time reverse transcriptase-polymerase chain reaction (RT-PCR).

RESULTS

Wound size was significantly increased in 8 hr group at 3 and 7 days after wound formation. Regional blood flow was significantly decreased in 4 hr and 8 hr groups at 3 days after wound formation. The bFGF, collagen 1 and 3 mRNA expressions were significantly decreased in 8 hr exposure group.

CONCLUSIONS

These results suggest that sevoflurane exposure influences the regional blood flow, wound size, expression of bFGF, and production of collagen 1 and 3 during the wound healing process.

Skin peptides: biological activity and therapeutic opportunities

The skin provides an effective barrier to the loss of body fluids and environmental assault. In addition to the physical barrier provided by the stratum corneum, the skin also contains a chemical barrier consisting of antimicrobial peptides (AMPs), which control microbial growth on the surface. These AMPs also have multiple roles as mediators of inflammation with effects on epithelial and inflammatory cells, influencing cell proliferation, wound healing, cytokine/chemokine production and chemotaxis. This review describes the range of peptides found in the skin, both constitutive and those induced in response to injury. The role these peptides play in normal skin function and in various skin conditions is described. A better understanding of their role in normal and skin disease may offer new strategies in skin disease, dermatology and as cosmeceuticals.

TGF-β1 gene polymorphism in psoriasis vulgaris

Overexpression of TGF-beta(1) has been implicated in the pathology of many inflammatory diseases, including psoriasis. This study was performed to investigate the association between TGF-beta(1) single nucleotide polymorphism and susceptibility for psoriasis vulgaris. DNA from 78 patients with psoriasis vulgaris and 74 healthy volunteers was investigated. Polymorphism of TGF-beta(1) gene in codon 10 (T/C) and codon 25 (G/C) was evaluated by PCR-SSP and the results were compared between group of psoriatic patients, divided into early onset of psoriasis (type I) and late onset of psoriasis (type II) subgroups, and control healthy subjects. Frequencies in genotypes were similar between patients and control group (p >0.7), but between type I and type II psoriasis patients highly significant difference was found (p <0.0003). Higher frequency of CC/GG (intermediate producer) and TC/GG (high producer) was noted in the type I group, but the second high producer genotype (TT/GG) was more common in type II group. Also between type II psoriasis patients and healthy controls statistically significant difference was found (p <0.000001). In analyzing frequencies of carriage and alleles no significant differences were found. TGF-beta(1) gene polymorphism in codon 10 and 25 is not associated with susceptibility to psoriasis vulgaris, but may be important for the type of the disease.

Increased numbers of CD68 antigen positive dendritic epidermal cells and upregulation of CLA (cutaneous lymphocyte-associated antigen) expression on these cells in various skin diseases

CD68 is a myelomonocytic marker identified in human dermal macrophages. Although the existence of CD68 + dendritic epidermal cells has been reported, their characteristics have not been well elucidated. Cutaneous lymphocyte-associated antigen (CLA) is a homing receptor of cutaneous inflammatory T cells. Our recent report suggested that CLA was a homing molecule of CD1a+ Langerhans cells (LC) in the skin. In the present study we tested whether CD68 and CLA+ dendritic epidermal cells were present in skin specimens of normal skin and diseased skin such as lichen planus (LP), psoriasis vulgaris (PS), discoid lupus erythematosus (DLE), basal cell epithelioma (BCE), squamous cell carcinoma (SCC), irritated seborrheic keratosis (iSK), and Bowen's disease (BD). CD68+ dendritic epidermal cells were identified in normal skin and consisted of half the population of CD1a+ LC. These data indicate that CD68+ dendritic epidermal cells constitute a subpopulation of CD1a+ LC. CLA was expressed on a small percentage of CD68+ dendritic epidermal cells in normal skin. A remarkably increased number of CD68+ dendritic epidermal cells and upregulation of CLA on CD68+ dendritic epidermal cells were observed in diseased skin. The percentage of CLA+ cells among all CD68+ dendritic epidermal cells was less than that of CLA+ cells among all CD1a+ LC in diseased skin. The percentage of CLA+ cells among all CD68+ dendritic dermal cells was much less than that of CLA+ cells among all CD1a+ dendritic dermal cells. In normal skin, the epidermis showed minimal expression of monocyte chemoattractant protein (MCP)-1 and TGF-beta2, and no expression of TGF-beta1. In diseased skin, the epidermis showed elevated, but still moderate immunoreactivity for MCP-1. Slightly enhanced immunoreactivity for TGF-beta2, but not for TGF-beta1, was observed in the epidermis of diseased skin. Increased epidermal MCP-1 immunohistochemical staining was associated with the increased number of CD68 dendritic epidermal cells. These data suggest the possibility that MCP-1 secretion from the epidermis can affect the migration of CD68; Cutaneous lymphocyte-associated antigen; Monocyte chemoattractant protein-1; TAF-beta.

Identification of receptors and Smad proteins involved in activin signalling in a human epidermal keratinocyte cell line

BACKGROUND

Activin A is a multifunctional protein, which is a member of the transforming growth factor-beta (TGF-beta) superfamily. Smad proteins have recently been shown to transduce signals for the TGF-beta superfamily of proteins, and Smad2 was implicated in activin signalling in Xenopus embryos.

RESULTS

We identified the receptors and Smad proteins activated by activin A in a human epidermal keratinocyte cell line, HaCaT. The major activin receptors expressed on HaCaT cells were activin type II receptor (ActR-II) and activin type IB receptor (ActR-IB). We have also shown that in HaCaT cells, activin A induced the phosphorylation of Smad3 and, to a lesser extent, of Smad2. On the other hand, TGF-beta induced an efficient phosphorylation of both Smad2 and Smad3. Activin A preferentially induced the nuclear translocation of Smad3 in HaCaT cells, whereas TGF-beta strongly induced the nuclear translocation of Smad2, as well as other Smads. Moreover, a constitutively active form of ActR-IB efficiently stimulated the formation of a heteromeric complex between Smad3 and Smad4 in COS cells transfected with Smad cDNAs.

CONCLUSIONS

These results suggest that activin A binds to a receptor complex of ActR-II and ActR-IB, and preferentially activates Smad3 in HaCaT human keratinocytes.

Dysregulated expression of transforming growth factor beta and its type-I and type-II receptors in basal-cell carcinoma

In mammals, transforming growth factor-beta (TGF-beta) is found in 3 highly homologous isoforms that exert their effects via heteromeric complexes of type-I and type-II receptors (TbetaR-I and TbetaR-II). TGF-beta regulates the growth and metabolism of various cell types, including keratinocytes. We have investigated the immunohistological localization of TGF-beta1, TGF-beta2, TbetaR-I and TbetaR-II in normal human skin, basal-cell carcinoma (BCC), Bowen's disease, seborrheic keratosis, eccrine poroma and eccrine spiradenoma using frozen tissue specimens. In normal human skin, the immunoreactive TGF-beta2, but not TGF-beta1, was detected predominantly in the epidermis, follicles and sebaceous glands. The epidermal expression of TbetaR-I and TbetaR-II was very weak in the majority of normal skins. In BCC, TGF-beta2 expression was markedly reduced or completely negative. In addition, TbetaR-I- and TbetaR-II-positive stromal cells were accumulated in the fibrotic stroma in some BCCs. These stromal cells were partly but moderately positive for TGF-beta1. Decreased expression of TGF-beta2 was likely to be associated with the differentiation state of BCC cells, since TGF-beta2 expression was clearly observed in the squamoid foci of BCC. In addition, no expression of TGF-beta2 was detected in the eccrine secretory portion or in eccrine spiradenoma, but it was detected in the upper eccrine ducts and in eccrine poroma.

Distribution of transforming growth factor-beta and its receptors in gastric carcinoma tissue

The distribution of the three mammalian isoforms of transforming growth factor (TGF)-beta (TGF-beta 1, -beta 2, and -beta 3) as well as their signaling receptors, TGF-beta type I and type II receptors (T beta R-I and T beta R-II, respectively), in gastric carcinoma tissue was examined by immunohistochemistry using specific antibodies. Tissue specimens were obtained from 25 cases of gastric carcinoma, which were classified into two groups according to Lauren's classification, i.e. 15 cases of diffuse carcinoma and 10 cases of intestinal carcinoma. In normal gastric mucosa apart from carcinoma nests, all of TGF-beta 1, -beta 2, -beta 3, T beta R-I and T beta R-II were clearly demonstrated in fundic glands. In sharp contrast, none of them was detectable in surface mucous cells. In carcinoma cells, strong staining for TGF-beta 1, -beta 2 and -beta 3 was obtained only in diffuse-type carcinoma. In particular, carcinoma cells scattered as single cells or small nests had a tendency to show strong staining for TGF-betas. The receptors tended to be distributed concomitantly with the ligands, and diffuse-type carcinoma showed stronger receptor staining than intestinal-type carcinoma. In cancer stroma, TGF-betas and receptors were detected in both diffuse and intestinal types, but the area with positive staining was wider and more dispersed in diffuse-type carcinoma than in intestinal carcinoma. These results suggest that TGF-beta may contribute in part to the variety of histogenesis and mode of progression of gastric carcinoma.

Differential localization of TGF-beta-precursor isotypes in psoriatic human skin

Transforming growth factor-beta (TGF-beta) can act as a multi-functional regulator of both cell growth and differentiation. Three isoforms of TGF-betas, namely TGF-beta 1 TGF-beta 2 and TGF-beta 3, have been identified in human tissues. Previously we reported the expression of TGF-beta isoforms in normal human skin. However little is known about the role of TGF-beta isoforms in the pathogenesis of psoriasis. Using the TGF-beta precursor-specific antibodies to strengthen the specificity, we studied the immunohistochemical distribution of TGF-betas 1-3 in psoriatic skin. TGF-beta 2, which was found in the intercellular space of all the layers of the epidermis in normal human skin, was decreased in the psoriatic epidermis. The intensity of immunoreactivity has the tendency to decrease in the lower epidermis rather than in the upper epidermis of the transitional lesion. In contrast, TGF-beta 3 was present in the subepidermal area of the psoriatic skin as in the normal human skin. TGF-beta 1 was observed in neither epidermis nor dermis in both normal and psoriatic skin. Since TGF-beta is a potent growth inhibitor for human keratinocytes, the decrease of TGF-beta 2 in the epidermis of psoriatic skin may contribute to epidermal hyperplasia, a hallmark of psoriasis.

A human keratinocyte cell line produces two autocrine growth inhibitors, transforming growth factor-beta and insulin-like growth factor binding protein-6, in a calcium- and cell density-dependent manner

Two growth inhibitors were identified in culture medium conditioned by a human keratinocyte cell line, HaCat. TGF-beta was detected in media conditioned by growing or confluent HaCat cells, as well as in media conditioned at physiological (1 mM) or low (0.03 mM) Ca2+ concentrations. However, a considerable part of transforming growth factor beta (TGF-beta) in media conditioned at a physiological Ca2+ concentration was in active form, whereas most TGF-beta in media conditioned at a low Ca2+ concentration was latent. The other growth-inhibitory activity, which was detected only in media conditioned by confluent cells at a physiological Ca2+ concentration, was purified to homogeneity by a four-step procedure. The N-terminal amino acid sequence of the 33-kDa protein was identical with that of insulin-like growth factor binding protein-6 (IGFBP-6). Purified IGFBP-6 inhibited the growth of HaCat and Balb/MK keratinocyte cell lines, as well as Mv1Lu cells. The growth activity was also demonstrated by human recombinant IGFBP-6. In summary, HaCat cells secrete at least two possible autocrine growth inhibitors: TGF-beta which is secreted constitutively, but activated in a Ca(2+)-dependent manner, and IGFBP-6 which is secreted in a cell density- and Ca(2+)-dependent manner.