Systemic CXCL10 is a predictive biomarker of vitiligo lesional skin infiltration, PUVA, NB-UVB and corticosteroid treatment response and outcome.

Vitiligo is an acquired pigmentary skin disorder that currently lacks standardized treatment and validated biomarkers to objectively evaluate disease state or therapeutic response. Although prior studies have linked vitiligo autoimmunity with CXCL10/CXCL9-mediated recruitment of leukocytes to the skin, only limited clinical data are available regarding CXCL10 as vitiligo biomarker. To evaluate the utility of systemic CXCL10 as a predictor of disease progression and treatment response on a large cohort of vitiligo patients. CXCL10 levels in lesional, perilesional, and unaffected skin of vitiligo patient (n = 30) and in the serum (n = 51) were measured by quantitative ELISA. CXCL10 expression, recruitment of leukocytes, and inflammatory infiltrates were evaluated by histochemical (n = 32) and immunofluorescence (n = 10) staining. Rigorous cross-sectional and longitudinal biostatistical analysis were employed to correlate CXCL10 levels with disease variables, treatment response, and outcome. We demonstrated that elevated CXCL10 level (2 pg/mm2 and higher) in lesional skin correlates with increased leukocytic infiltrate, disease duration (< 2 year), and its higher level in the serum (50 pg/ml and higher). Changes in CXCL10 serum levels in patients treated with psoralen plus UVA (PUVA) phototherapy, narrowband UVB (NB-UVB) phototherapy, and systemic steroids (SS) correlated with changes in the intralesional CXCL10 levels in repigmented skin. NB-UVB and SS regimens provided most consistent CXCL10 mean change, suggesting that these regimens are most effective in harnessing CXCR3-mediated inflammatory response. Serum CXCL10 is a useful vitiligo biomarker, which predicts lesional skin leukocytic infiltration, and vitiligo treatment response and outcome.

Divergent effects of two sequence variants of GJB3 (G12D and R32W) on the function of connexin 31 in vitro.

Recently, we identified several missense mutations of the connexin gene GJB3 encoding connexin 31 (Cx31) in erythrokeratodermia variabilis (EKV), an autosomal dominant skin disorder. These mutations include G12D, which replaces a conserved glycine residue in the amino-terminus of Cx31 and is associated with a severe EKV phenotype. In contrast, the biologic relevance of the GJB3 sequence variant R32W located in the first transmembrane domain of Cx31 is disputed. To examine the effects of these sequence variants on Cx31 biogenesis and gap junction activity we expressed wild type and mutant Cx31-Flag constructs in HeLa cells. Using immunostaining, all expression variants were detected in the cytoplasm and in a punctate pattern at the cell surface, indicating that G12D and R32W did not interfere with either protein synthesis or transport to the cell membrane. Similarly, oligomerization into hemichannels appeared not impaired when expressing either Cx31 mutant as assessed by size exclusion chromatography, immunoblotting and immunostaining. However, dye transfer experiments and monitoring of intracellular calcium levels in response to serum stimulation revealed that G12D-Cx31 did not form functional gap junction channels, probably due to incorrect assembly or altered properties of Cx31 channels. In contrast, intercellular coupling between cells expressing R32W-Cx31 was comparable to that of wtCx31, suggesting that R32W is a functionally inconsequential polymorphism of Cx31.

Novel member of the mouse desmoglein gene family: Dsg1-beta.

Desmosomes are major intercellular adhesion junctions that provide stable cell-cell contacts and mechanical strength to epithelial tissues by anchoring cytokeratin intermediate filaments of adjacent cells. Desmogleins (Dsg) are transmembrane core components of the desmosomes, and belong to the cadherin supergene family of calcium-dependent adhesion molecules. Currently, there are three known isoforms of Dsgs (Dsg1, Dsg2, and Dsg3), encoded by distinct genes that are differentially expressed to determine their tissue specificity and differentiation state of epithelial cells. In this study, we cloned a novel mouse desmoglein gene sharing high homology to both mouse and human Dsg1. We propose to designate the previously published mouse Dsg1 gene as Dsg1-alpha and the new gene as Dsg1-beta. Analysis of intron/exon organization of the Dsg1-alpha and Dsg1-beta genes revealed significant conservation. The full-length mouse Dsg1-beta cDNA contains an open reading frame of 3180 bp encoding a precursor protein of 1060 amino acids. Dsg1-beta protein shares 94% and 76% identity with mouse Dsg1-alpha and human DSG1, respectively. RT-PCR using a multitissue cDNA panel demonstrated that while Dsg1-alpha mRNA was expressed in 15- to 17-day-old embryos and adult spleen and testis, Dsg1-beta mRNA was detected in 17-day-old embryos only. To assess subcellular localization, a FLAG-tagged expression construct of Dsg1-beta was transiently expressed in epithelial HaCaT cells. Dsg1-beta-FLAG was found at the cell-cell border and was recognized by the anti-Dsg1/Dsg2 antibody DG3.10. In summary, we have cloned and characterized a novel member of the mouse desmoglein gene family, Dsg1-beta.

Cloning of the mouse desmoglein 3 gene (Dsg3): interspecies conservation within the cadherin superfamily.

Desmoglein 3 is a cadherin-like calcium-dependent cell adhesion molecule expressed primarily in suprabasal keratinocytes of the epidermis. In this study, we have cloned the full-length cDNA and characterized the entire gene structure for the mouse desmoglein 3 gene (Dsg3). Isolation of overlapping cDNA clones, together with 5' and 3' rapid amplification of cDNA ends (RACE), allowed delineation of the entire coding sequence. The transcriptional initiation site was confirmed by primer extension and reverse transcription polymerase chain reaction analysis. The entire cDNA consisted of 6407 bp with an open reading frame of 2979 bp, and the deduced polypeptide contained 993 amino acids. Comparison of mouse and human desmoglein 3 amino acid sequences demonstrated 85.6% homology. Computer analysis suggested the presence of a transmembrane segment, 5 potential calcium binding sites, and a RAL motif which corresponds to the HAV motif, the potential site for homophilic interaction of typical cadherins. The mouse desmoglein 3 gene consisted of 15 exons in chromosome 18. Comparison of the intron-exon organization of Dsg3 with various cadherins from different species revealed remarkable conservation. This relatively high level of conservation both at the protein and genomic level suggests that desmoglein 3 plays an important role in keratinocyte cell-cell adhesion.

8-methoxypsoralen and ultraviolet a radiation activate the human elastin promoter in transgenic mice: in vivo and in vitro evidence for gene induction.

Treatment of skin diseases with the combination of 8-methoxypsoralen and ultraviolet A radiation (PUVA) results in clinical alterations in treated skin that resemble those observed in chronically photodamaged skin. The PUVA-treated patients develop nonmelanoma skin cancers, pigmentary alterations and wrinkling characteristic of sun-induced changes. The major alteration in the dermis of sun-damaged skin is the deposition of abnormal elastic fibers, termed solar elastosis. Up-regulation of elastin promoter activity in dermal fibroblasts explains the excess elastic tissue but not the reason for the aberrant morphology of the elastotic material. In order to study photoaging in an experimental system, we utilized a transgenic mouse line that expresses the human elastin promoter/chloramphenicol acetyltransferase construct in a tissue-specific and developmentally regulated manner. Although UVB radiation has been demonstrated to increase promoter activity in vitro, UVA fails to demonstrate a similar effect at the doses utilized. In this study, we demonstrate the ability of PUVA treatment to up-regulate elastin promoter activity both in vitro and in vivo. These data help to explain the development of photoaging in sun-protected PUVA-treated skin. We attribute the up-regulation of elastin promoter activity in response to PUVA to the formation of DNA photoadducts, which do not occur in response to UVA radiation alone.

Complete coding sequence, intron/exon organization, and chromosomal location of the gene for the core I protein of human ubiquinol-cytochrome c reductase.

Core I protein is a nuclear-encoded component of the ubiquinol-cytochrome c reductase complex of the mitochondrial respiratory chain. We have located the gene for the human core I protein in the p21 region of chromosome 3, just upstream of the COL7A1 gene which encodes type VII collagen. The core I gene, which has been sequenced in its entirety, is comprised of 10,417 base pairs, from the major transcription start site to the polyadenylation signal, and contains 13 exons. The predicted polypeptide contains 480 amino acids, of which the first 34 are predicted to constitute a typical mitochondrial leader peptide containing 6 positively charged arginine residues. The predicted human protein shows significant homology with core I protein from Saccharomyces cerevisiae, rather high homology (64% similarity, 46% identity) with the processing enhancing protein, which functions as core I protein in Neurospora crassa, and, surprisingly, highest homology with the small subunit of the mitochondrial processing peptidase of rat (74% similarity, 55% identity). The predicted human sequence is 87% identical to the reported bovine core I sequence predicted from cDNA cloning, up to residue 298, but the two predicted sequences are widely divergent after that point.

Direct interaction of antifungal azole-derivatives with calmodulin: a possible mechanism for their therapeutic activity.

Azole derivatives, such as ketoconazole and bifonazole, are well-established antifungal drugs. Recently, these compounds have been reported to have therapeutic efficacy also in inflammatory skin disorders. There is increasing evidence that calmodulin is involved in fungal infections as well as in inflammatory skin diseases. Therefore, we investigated the effects of various antifungal drugs on calmodulin activity, using calmodulin-dependent phosphodiesterase as an indicator for the calmodulin activity. All azole derivatives tested competitively inhibited calmodulin activity with 50% inhibitory concentration values in the low micromolar range. In contrast, antifungal drugs belonging to other chemical classes did not display inhibitory activity. Thus, this study provides evidence that direct interaction with calmodulin might contribute to the therapeutic activity of azole derivatives, particularly to their efficacy in the treatment of inflammatory skin disorders.

Hyperthermia potentiates the effects of aluminum phthalocyanine tetrasulfonate-mediated photodynamic toxicity in human malignant and normal cell lines.

The purpose of this study was to examine the effects of photodynamic therapy utilizing aluminum phthalocyanine tetrasulfonate in vitro on several human malignant and normal cell types, with or without hyperthermia. Cells examined included normal skin fibroblasts, HT-1080 fibrosarcoma cells, SCC-25 (squamous cell carcinoma) and malignant melanoma cells. An argon-pumped continuous wave tunable dye laser at 675 nm was used as the light source, hyperthermia groups were heated to 42.5 degrees C, and radioisotope incorporation was used to measure DNA and protein synthesis as toxicity assays. Results showed an energy-dose, and A1PcS-concentration dependent toxicity in all cell lines examined, with moderate selectivity toward malignant cells. Hyperthermia alone was slightly toxic in melanomas and HT-1080 cell lines but had no effect in normal fibroblasts or SCC-25 cells. Hyperthermia synergistically potentiated the effects of PDT in all cell lines, and the combined modality was significantly more toxic in all malignant cell lines compared with normal cells. Thus, addition of hyperthermia to PDT protocols may enhance the efficacy of this treatment modality in vitro.

Connective tissue alterations in skin exposed to natural and therapeutic UV-radiation.

Aging of human skin represents a complex situation where several factors contribute to the age-related changes. One of these factors relates to UV-radiation, but the exact mechanistic details are not well established. Several morphologic studies have indicated definite changes in the quantitative aspects of dermal connective tissue components, collagen and elastin. Also, recent biochemical studies have suggested that UV-irradiation can alter the metabolism of these proteins in the skin. This review summarizes the current state of knowledge of the effects of natural and therapeutic UV-radiation on dermal connective tissue, and further delineates additional research needs necessary for disclosure of the exact mechanistic details of the aging processes in human skin.

Collagen biosynthesis by human skin fibroblasts. I. Optimization of the culture conditions for synthesis of type I and type III procollagens.

Skin fibroblasts in culture can provide a convenient means to study aberrations of collagen metabolism in a variety of clinical conditions. In the present study, the culture conditions for the synthesis of procollagen by cultured human skin fibroblasts were optimized by independently varying parameters in the cell culture environment. To study the synthesis of procollagen the cell cultures were labeled with [3H]proline and the collagenous polypeptides were determined either by measuring the synthesis of hydroxy[3H]proline or by assaying the 3H-labeled proteins digested into dialyzable 3H-labeled peptides by bacterial collagenase. On the basis of the experimental results, the following culture conditions are suggested for optimal synthesis of procollagen: (a) cell culture medium should be supplemented with ascorbic acid (25--50 micrograms/ml) and fetal calf serum (20%); (b) the pH of the culture medium should be kept above 7.2 and preferably in the pH range 7.5--7.8; (c) the cell cultures should be used one to two days after reaching visual confluency. Under these conditions the synthesis and secretion of [3H]procollagen was found to be linear through a 24 h incubation period, and procollagen was demonstrated to be a major gene product of the fibroblasts. The relative synthesis of type I and type III procollagens was also monitored by isolating these genetically distinct procollagens by DEAE-cellulose chromatography or by measuring type I and III collagens by sodium dodecyl sulfate polyacrylamide gel electrophoresis after limited pepsin proteolysis. No marked changes were observed in type I/III procollagen ratios in situations where the total formation of hydroxy[3H]proline was significantly affected. The average coefficient of variance for procollagen synthesis between replicate cultures was found to be relatively small (14%), and the optimization of the culture conditions for the control cells has, therefore, created a reliable and reproducible basis for employing human skin fibroblasts to study collagen metabolism in acquired and inherited diseases.

Scleroderma: increased biosynthesis of triple-helical type I and type III procollagens associated with unaltered expression of collagenase by skin fibroblasts in culture.

To assess potential abnormalities in collagen metabolism in systemic scleroderma, skin fibroblast lines from patients with this disease were established and compared to control cell lines derived from healthy subjects. For studies on the biosynthesis of procollagen, the cells were incubated with [(14)C]proline in a medium supplemented with ascorbic acid and beta-aminopropionitrile, and the synthesis of nondialyzable [(14)C]hydroxyproline, in relation to DNA or cell protein, was taken as an index of procollagen formation. Five of eight scleroderma fibroblast cell lines demonstrated procollagen biosynthesis rates significantly higher than the controls, and the mean rate of procollagen synthesis by scleroderma fibroblasts was about twice that of the control cells. Control experiments demonstrated that the specific activity of the intracellular free proline was not different in scleroderma and control fibroblasts, and the mean population doubling times of the scleroderma and the control fibroblast cell lines were the same. The relative synthesis of the genetically distinct procollagens was examined by isolating type I and type III procollagens from the cell culture medium using DEAE-cellulose chromatography. The ratios of type I/III procollagens in scleroderma cell lines did not differ from the controls. The helical stability of the collagenous portion of type I and type III procollagens, estimated by the resistance of (14)C-collagen to limited proteolytic digestion with pepsin under nondenaturing conditions, was the same in both scleroderma and control cultures. The capacity of the cells to synthesize enzymatically active and immunologically reacting collagenase was also studied; no marked differences in these parameters could be observed. The results suggest that cultured skin fibroblasts from patients with scleroderma demonstrate a metabolic abnormality expressed as increased synthesis of type I and type III procollagens in a normal ratio. This abnormality may play a role in the excessive accumulation of collagen in the skin and other organs affected in scleroderma.