Topical tocoretinate improved hypertrophic scar, skin sclerosis in systemic sclerosis and morphea

Four patients with systemic scleroderma (SSc), 4 patients with morphea, and 4 patients with hypertrophic scar were treated with topical tocoretinate for 6 months to 3 years and studied clinically and histopathologically. Clinically, all of the lesions responded to this therapy. The stiffness of the skin lesions, glossy appearance of the lesions, and telangiectasia improved. Histopathologically, the proliferated collagen fibers decreased in thickness, and the inter-fiber spaces increased. Immunoreactive tenascin-C expressed in the proliferated deep dermal fibers of the SSc and hypertrophic scar lesions was markedly decreased compared with the level before the topical tocoretinate therapy. Topical tocoretinate has been used for the treatment of ulcers; it is also a potent treatment for sclerotic skin diseases.     

Histopathological differential diagnosis of keloid and hypertrophic scar

Distinguishing hypertrophic scar (HS) from keloid histopathologically is sometimes difficult because thickened hyalinized collagen (keloidal collagen), the hallmark of keloid, is not always detectable and alpha-smooth muscle actin (alpha-SMA), a differentiating marker of HS, is variably expressed in both forms of scar. The aim of this study was to investigate additional distinguishing features to facilitate differentiation between keloid and HS. We compared various histologic features and the expression of alpha-SMA in 40 specimens of keloid and 10 specimens of HS. The features more commonly seen in keloids were: (a) no flattening of the overlying epidermis, (b) no scarring of the papillary dermis, (c) presence of keloidal collagen, (d) absence of prominent vertically oriented blood vessels, (e) presence of prominent disarray of fibrous fascicles/nodules, (f) presence of a tongue-like advancing edge underneath normal-appearing epidermis and papillary dermis, (g) horizontal cellular fibrous band in the upper reticular dermis, and (h) prominent fascia-like fibrous band. The last three features were found in keloid specimens only, including the ones lacking detectable keloidal collagen. Our study confirmed the diagnostic value of keloidal collagen, but it was only found in 55% of keloid specimens. Alpha-SMA expression was found in both HS (70%) and keloid (45%), thus it would not be a differentiating marker. In scars with no detectable keloidal collagen, the presence of the following feature(s) favors the diagnosis of keloid: non-flattened epidermis, non-fibrotic papillary dermis, a tongue-like advancing edge, horizontal cellular fibrous band in the upper reticular dermis, and prominent fascia-like band.     

Collagen degradation in cultured keloid and hypertrophic scar tissue

SUMMARY In order to study collagen catabolism of normal human skin, keloid and hypertrophic scars, explants of these tissues have been cultured for periods of up to 10 days. All three tissues released a similar amount of neutral collagenase activity into the culture medium with maximal yield between days 3 and 7, and the collagenase from scar tissues was found to be identical to the normal skin enzyme with regard to its inhibition by EDTA, cysteine and human serum. The major site of collagenase production in keloid specimens appeared to be, as in normal skin, the upper dermal or epidermal layer, with minimal production occurring in the lower fibrous or nodular areas. Prior to culture the collagen content of each tissue was found to be similar, with approximately 1%, of the total being acid-soluble. During the culture period considerable amounts of insoluble tissue collagen were degraded in all three tissues, as judged by the release of hydroxyproline into the culture medium. These results suggest that the persistence of keloids and hypertrophic scars is attributable neither to an inability of the tissues to produce an active collagenase molecule nor to any resistance of the tissue collagen to degradation.     

The renin-angiotensin system in cutaneous hypertrophic scar and keloid formation

Hypertrophic scar and keloid are two types of fibroproliferative conditions that result from excessive extracellular matrix production. The underlying pathological mechanism is not entirely clear. Activation of the renin-angiotensin system (RAS) is associated with fibrosis in various organs. RAS components including angiotensin II (Ang II), angiotensin AT₁ and AT₂ receptors, and angiotensin-converting enzyme (ACE) are expressed in the skin and act independently from the plasma RAS. AT₁ receptors, which are usually the dominating receptor subtype, promote fibrosis and scar formation, while AT₂ receptors inhibit the aforementioned AT₁ receptor-coupled effects. Elevated angiotensin II (Ang II) levels acting on the AT₁ receptor contribute to skin scar formation through increased expression of inflammatory factors such as interleukin-6 (IL-6), angiogenic factors such as vascular endothelial growth factor (VEGF) and fibrinogenic factors such as transforming growth factor-β1 (TGF-β1) and connective tissue growth factor (CTGF), while at the same time suppressing the anti-fibrotic tissue inhibitors of matrix metalloproteinase (TIMPs). First, small clinical trials have provided evidence that inhibition of the ACE/Ang II/ AT₁ receptor axis may be effective in the treatment of hypertrophic scars/keloids. This review provides a detailed overview of the current literature on the RAS in skin, wound healing and scar formation and discusses the translational potential of targeting this hormonal system for treatment and prevention of hypertrophic scars and keloids.     

Where we stand with human hypertrophic and keloid scar models

We have yet to create a human scar model that demonstrates the complex nature of hypertrophic scar and keloid formation as well as ways to prevent them despite emerging advances in our understanding of the immune system, the inflammatory response, and proteomic and genomic changes after injury. Despite more complex in vitro models, we fail to explain the fundamental principles to scar formation, and the timeline of their development. The solution to developing the ideal in vitro scar model is one that mimics the heterogeneous cellular and molecular interactions, as well as the evolving structure and function of human skin.     

Interrelationship between water-barrier and reservoir functions of pathologic stratum corneum

Scaly skin lesions are caused by decreased water content of the stratum corneum, despite the well-known fact that they usually show increased water passage. By performing simultaneous measurements of transepidermal water loss (TEWL) to check the water-barrier function of the stratum corneum and cutaneous conductance to the high-frequency electric current of 3.5 MHz, which is an indicator of skin-surface hydration state, in patients with psoriasis who had lesions of various grades of severity, we obtained data indicating that there is an inverse relationship between these functions of the stratum corneum. Furthermore, a time course study of TEWL and functional analysis of stratum corneum by an in vivo water sorption-desorption test performed on the experimentally induced scaly lesions after adhesive-tape stripping demonstrated that such pathologic stratum corneum is characterized by a water-holding defect that is associated with increased TEWL.     

The role of proteases in stratum corneum: involvement in stratum corneum desquamation

The effects of protease inhibitors on cell dissociation were studied in vitro in order to examine the involvement of proteases in stratum corneum desquamation. Stratum corneum sheet (peeled from human backs after sunburn) was incubated in a detergent mixture containing 8 mM N,N-dimethyldodecylamine oxide, 2 mM sodium lauryl sulphate and 60 g/ml kanamycin with or without protease inhibitors, and the number of released cells was counted after incubation for 48 h. Cell dissociation was inhibited strongly by antipain or aprotinin, but not at all by N-[N-(l-3-transcarboxyoxiran-2-carbonyl)-l-leucyl]-agmatin, N-ethylmaleimide or pepstatin, which suggests that only serine proteases are associated with desquamation. Furthermore, leupeptin and chymostatin each reduced cell dissociation about half as effectively as aprotinin or antipain, while a mixture of leupeptin and chymostatin prevented stratum corneum dissociation as potently as antipain or aprotinin. In addition, the activity of chymotrypsin-like protease in scaly skin was higher than that in normal skin, as we have previously found for trypsin-like protease. These results suggest that both trypsin-like and chymotrypsin-like serine proteases are involved in stratum corneum desquamation.     

Preparation of liposomes from stratum corneum lipids

Cutaneous and subcutaneous blood flow (CBF, SBF) were studied in non-lesional psoriatic skin (NLS) of 10 patients with only minimal psoriatic skin manifestations, using the local 133Xe washout method. Measurements of the CBF and SBF in the NLS of the patients and 10 normal individuals yielded no statistically significant differences. The results of the present study indicate that the activity of psoriasis can be monitored by the CBF measurements in the NLS, since previously published values for CBF of NLS have shown increasing values with increasing psoriatic activity. The significance of these findings may be more evidence of humoral factors playing a role in the pathogenesis of the disease. The tissue-to-blood partition coefficient for 133Xe was calculated on the basis of biochemical estimations of the relative content of lipids, proteins, and water in skin biopsies from non-lesional skin sites of 8 psoriatic patients. The relative content of lipids, proteins, and water was normal. Thus, the normal 133Xe partition coefficient of 0.7 ml/g should be used for measurements of the CBF in NLS.     

剪切波弹性成像定量鉴别瘢痕疙瘩与肥厚性瘢痕的初步探讨

目的：探讨剪切波弹性成像技术定量鉴别瘢痕疙瘩与肥厚性瘢痕的价值。方法：选取我院皮肤科临床诊断为瘢痕疙瘩及肥厚性瘢痕患者各30例,比较两组病例的性别、年龄、病灶长轴切面的剪切波弹性成像杨氏模量值。结果：瘢痕疙瘩、肥厚性瘢痕的长轴平均杨氏模量分别为(94.93±25.39) kPa、(24.5±3.62)kPa,差异有统计学意义(P＜0.001)。结论：剪切波弹性成像可定量评价两组病变的组织硬度,为瘢痕疙瘩和肥厚性瘢痕的临床鉴别提供帮助。     

Characteristics of cytokeratins from stratum corneum of palms

We have examined cytokeratins from stratum corneum (s. corneum) of the palm and back of hands by biochemical techniques which characterize cytokeratin No. 9 (CK9). By two-dimensional gel electrophoresis, cytokeratins from s. corneum of the palm (PSC) were resolved into three spots (designated as CK-A, CK-B and CK-C by us), and cytokeratins from s. corneum of the back of hands (BSC) were resolved into two spots (CK-A and CK-C). The results of polypeptide mapping and the spot positions in two-dimensional gels suggest that CK-A, CK-B and CK-C are degraded products derived from CK1/2, CK9 and CK10/11 in living keratinocytes of epidermis, respectively. While the spots of CK-A and CK-B were prominent and the spot of CK-C was very weak in PSC, the spots of CK-A and CK-C were prominent and the spot of CK-B was not detected in BSC. In filament reconstitution in vitro, cytokeratins from PSC formed intermediate-sized filaments similar to those commonly observed using cytokeratins from whole epidermis. In contrast, cytokeratins from BSC formed only short filaments and small granules. In order to examine this difference in detail, polypeptides were eluted electrophoretically from gel slices containing spots. Addition of eluted CK-B to cytokeratins from BSC promoted the formation of intermediate-sized filaments similar to those from PSC. Furthermore, although the mixture of eluted CK-A and CK-C did not form intermediate-sized filaments, the combination of CK-A and CK-B alone did form them.(ABSTRACT TRUNCATED AT 250 WORDS)     

The composition of the ceramides from human stratum corneum and from comedones

Human epidermal surface lipids were collected by an ethanol wash and the ceramides were quantified by thin-layer chromatography-photodensitometry. Six ceramide fractions were isolated and the structural components of each were analyzed in detail. The most unusual of the epidermal ceramides contained a sphingosine base with amide-linked 30- and 32-carbon omega-hydroxyacids and an ester-linked nonhydroxyacid, 41% of which was linoleic acid. The proportion of linoleic acid in the analogous ceramide from comedones was 6%. This supports the hypothesis that a localized insufficiency of linoleic acid in the follicular epithelium is an etiologic factor in comedogenesis.     

Human hypertrophic and keloid scar models: principles,limitations and future challenges from a tissue engineering perspective

Most cutaneous wounds heal with scar formation. Ideally, an inconspicuous normotrophic scar is formed, but an abnormal scar (hypertrophic scar or keloid) can also develop. A major challenge to scientists and physicians is to prevent adverse scar formation after severe trauma (e.g. burn injury) and understand why some individuals will form adverse scars even after relatively minor injury. Currently, many different models exist to study scar formation, ranging from simple monolayer cell culture to 3D tissue‐engineered models even to humanized mouse models. Currently, these high‐/medium‐throughput test models avoid the main questions referring to why an adverse scar forms instead of a normotrophic scar and what causes a hypertrophic scar to form rather than a keloid scar and also, how is the genetic predisposition of the individual and the immune system involved. This information is essential if we are to identify new drug targets and develop optimal strategies in the future to prevent adverse scar formation. This viewpoint review summarizes the progress on in vitro and animal scar models, stresses the limitations in the current models and identifies the future challenges if scar‐free healing is to be achieved in the future.     

The effect of ultraviolet radiation on the water-reservoir functions of the stratum corneum.

The stratum corneum plays an important role in keeping the skin surface supple and flexible. After exposure to sunlight, the skin may become dry and scaly. In the present study, the water content, hygroscopicity and water-holding capacity of the stratum corneum were examined after ultraviolet B (UVB) exposure to the guinea pig skin. Manually depilated back skin was exposed once to 1, 2 and 3 times the minimal erythema dose of UVB, and a time course study was performed. Our study demonstrated the following: The water content, water-holding capacity and hygroscopicity decreased after UVB irradiation. They decreased roughly dependent on UVB dose. The decreased water content and water-holding capacity were noted on day 1 and persisted until day 10 to 14. In contrast, the decrease in hygroscopicity became apparent 3 days after exposure and returned to the preirradiated state on day 7. The impaired functional parameters were partially prevented by topical application of a sunscreen. These results indicate that a single exposure to UVB can damage the function of the stratum corneum.     

Ultrastructure of the human stratum corneum

The ultrastructural study of the intercellular spaces of the human stratum corneum was based on transmission electron microscopy of thin vertical sections and freeze-fracture replicas, field emission scanning electron microscopy and immunofluorescence confocal laser scanning microscopy. The maturation of the corneosomes and their enzymatic degradation could be depicted at strategic interfaces. These sharp and rapid metamorphoses are now relatively well understood from a morphological point of view. But morphology raises a lot of unsolved physiological problems.     

Hyaluronan exists in the normal stratum corneum

Hyaluronan is well known to exist as a water-sorbed macromolecule in the extracellular matrix. We here examined whether hyaluronan exists in the normal stratum corneum. High performance liquid chromatography was used to quantify hyaluronan content in the stratum corneum, epidermis (including stratum corneum), and dermis of mice, with the resulting dry weights being 22.3 +/- 2.9, 15.1 +/- 1.5, and 738.6 +/- 31.6 microg per g, respectively. Normal mouse skin was then labeled with [3H]-glucosamine in an organ culture, and accumulation of [3H]-labeled hyaluronan and its molecular mass were determined separately for the stratum corneum, epidermis, and dermis. In the stratum corneum, [3H]-labeled hyaluronan was accumulated linearly over the 3-d culture period. After the 3-d culture period, the epidermis synthesized twice the amount (expressed as dpm per mg dry weight) of [3H]-labeled hyaluronan as the dermis, whereas the stratum corneum and dermis showed nearly the same content of [3H]-labeled hyaluronan. The molecular mass of [3H]-labeled hyaluronan was highest (>1.0 x 106) in the dermis and clearly lower (<6.0 x 104) in the stratum corneum. Based on these results, we here confirm that hyaluronan is supplied from keratinocytes beneath the stratum corneum layer, and is present in the normal stratum corneum. We speculate that hyaluronan may play a role in moisturizing the stratum corneum and/or regulating its mechanical properties.     

Hexose sugars differentially alter collagen gene expression and synthesis in fibroblasts derived from granulation tissue,hypertrophic scar and keloid

Clinical observations have suggested that sugar and honey enhance granulation tissue formation and in vitro studies have shown that monosaccharide sugars stimulate mesenchymal and endothelial cells. In this study, the effects of glucose, fructose, galactose and mannose on type I and type III collagen gene expression and synthesis were studied in granulation tissue, hypertrophic scar and keloid fibroblast cultures. Glucose elevated both type I and type III collagen mRNAs in hypertrophic scar fibroblasts. Fructose increased type III collagen mRNA almost sevenfold in granulation tissue fibroblasts. Galactose caused an increase in type I and type III collagen mRNAs in granulation tissue fibroblasts and hypertrophic scar fibroblasts but, in contrast, mannose decreased type I and type III collagen levels in hypertrophic scar and keloid fibroblasts. Analysis of aminoterminal propeptides of type I and type III collagen (PINP and PIIINP) revealed that glucose decreased the amount of PINP in granulation tissue and keloid fibroblasts, whilst fructose decreased the amount in all the fibroblast cell lines studied. Galactose caused a decrease in the synthesis of type I collagen in all cell lines but a decrease was seen in type III collagen only in hypertrophic scar fibroblasts. Mannose decreased the amount of PINP in all cell lines but a decrease in the amount of PIIINP was seen only in granulation tissue fibroblasts. The effect of sugars on the ratio type I/type III collagen was negligible or decreasing with the exception of galactose, which increased the ratio in hypertrophic scar fibroblasts. The results suggest that glucose, fructose and galactose have no significant value in the stimulation of collagen synthesis in vitro. Mannose may have value in the prevention or treatment of abnormal scars.