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Biomedical subjects

Sewon Kang

Publications and source records attributed to Sewon Kang.

At least 19 recordsLinked to original sources

A randomized, open-label trial of continuous versus interrupted etanercept therapy in the treatment of psoriasis.

BACKGROUND: Although etanercept is used as a continuous therapy for moderate to severe plaque psoriasis, intermittent use may be necessary in some instances. OBJECTIVE: In this randomized, open-label study, we evaluated the effectiveness and safety of continuous versus interrupted etanercept therapy. METHODS: All patients received uninterrupted etanercept 50 mg twice weekly during the first 12 weeks, followed by either continuous (n = 1272) or interrupted (n = 1274) etanercept 50 mg once weekly in the next 12 weeks. The primary effectiveness end point was the proportion of responders (those who achieved a Physician's Global Assessment [PGA] score <or=2 and improvement from baseline) at week 24. Secondary end points included the PGA "clear/almost clear" status, the PGA Scalp Psoriasis score, and the Dermatology Life Quality Index. A modified intent-to-treat analysis was performed. RESULTS: At week 12, comparable high proportions of responders were reported in the continuous (71.3%) and interrupted (72.0%) arms. However, the proportion of responders at week 24 was greater in the continuous group than in the interrupted group (71.0% vs 59.5%; P < .0001). Similar results were observed in secondary end points. The mean number of etanercept doses (1 dose = 50 mg) received by patients in the continuous group was 33.4, compared with 28.0 in the interrupted group. Etanercept was well tolerated in both treatment arms. LIMITATIONS: We examined one round of discontinuation and re-treatment; interrupted therapy provided less total medication to responding patients. CONCLUSIONS: Continuous and interrupted etanercept therapy was effective and generally well tolerated in patients with psoriasis, with greater improvements observed in the continuous arm at week 24. Most patients regained their response after reinitiation of etanercept.

Adult↗

Clinical response to adalimumab treatment in patients with moderate to severe psoriasis: double-blind, randomized controlled trial and open-label extension study.

BACKGROUND: Tumor necrosis factor is pivotal in the pathogenesis of psoriasis. Adalimumab is a fully human monoclonal immunoglobulin G1 antibody that neutralizes tumor necrosis factor. OBJECTIVES: We sought to assess the efficacy and safety of adalimumab in patients with moderate to severe plaque psoriasis. METHODS: In this multicenter, randomized, double-blind, placebo-controlled study, 147 patients received adalimumab (40 mg every other week or 40 mg/wk) or placebo. After 12 weeks of blinded therapy, patients taking adalimumab could continue their assigned dosages in a 48-week extension trial; patients taking placebo were switched to adalimumab (40 mg every other week). RESULTS: At week 12, 53% of patients taking adalimumab every other week, 80% of patients taking adalimumab weekly, and 4% of patients taking placebo achieved 75% improvement in Psoriasis Area and Severity Index score (P < .001). Responses were sustained for 60 weeks. No new safety signals were noted compared with the existing adalimumab clinical safety database. LIMITATIONS: The study was insufficiently powered to detect rare adverse events associated with adalimumab. CONCLUSIONS: Adalimumab significantly improved psoriasis and was well tolerated for 60 weeks.

Adalimumab↗

The effects of laser-mediated hair removal on immunohistochemical staining properties of hair follicles.

BACKGROUND: The mechanisms involved in laser-mediated hair removal remain unclear. One means of reducing hair growth is alteration of follicular stem cells. OBJECTIVE: We sought to examine the effects of laser hair removal on the immunohistochemical staining properties of human hair follicles, including the putative stem cells of the bulge region. METHODS: Treatment of unwanted axillary hair was performed on one side using an 800 nm-wavelength diode laser and on the other side using a 1064 nm-wavelength neodymium:yttrium-aluminum-garnet laser. Serial skin samples were obtained at baseline and various times after treatment and stained using immunohistochemical techniques. RESULTS: Hair shafts were thermally altered, but the immunostaining properties of much of the follicle, including the bulge region, remained generally unchanged. LIMITATIONS: This study only addressed the acute immunohistochemical changes found after a single treatment using specific laser parameters. CONCLUSIONS: Laser-mediated hair removal does not appear to work by frank destruction of follicular stem cells. Other mechanisms including functional alteration of these cells may underlie the clinical efficacy of the procedure.

Adult↗

Microdermabrasion with and without aluminum oxide crystal abrasion: a comparative molecular analysis of dermal remodeling.

BACKGROUND: Microdermabrasion is a popular method of superficial skin resurfacing with effects on dermal remodeling. OBJECTIVE: The purpose of this study was to evaluate the relative importance of the two components of microdermabrasion, negative pressure and abrasion, in stimulating expression of key genes involved in dermal remodeling. METHODS: Ten subjects were treated with a microdermabrasion machine using focal crystal abrasion and negative pressure or negative pressure alone for 3 seconds. Serial biochemical analyses were performed. Reverse transcriptase real-time polymerase chain reaction assays were used to evaluate changes in transcription factor activator protein-1, primary cytokines (interleukin 1beta, tumor necrosis factor-alpha), and matrix metalloproteinases (MMP-1, MMP-3, MMP-9). RESULTS: Significant increases in gene expression of the c-Jun component of activator protein-1, interleukin 1beta, tumor necrosis factor-alpha, MMP-1, MMP-3, and MMP-9 were found with crystal abrasion combined with negative pressure. Negative pressure alone resulted in increased gene expression of MMP-1 and MMP-3 but of a quantitatively reduced magnitude when compared with negative pressure with crystal abrasion. LIMITATIONS: It is unclear that molecular changes seen with these treatments can result in clinical effect. CONCLUSION: The abrasive component of microdermabrasion is necessary for stimulating expression of key genes involved in dermal remodeling.

Adult↗

Adapalene gel, 0.1%, as maintenance therapy for acne vulgaris: a randomized, controlled, investigator-blind follow-up of a recent combination study.

OBJECTIVE: To assess the maintenance effect of adapalene gel, 0.1%, relative to gel vehicle in subjects successfully treated in a previous 12-week study of adapalene-doxycycline, 100 mg, combination therapy. DESIGN: Multicenter, investigator-blind, randomized, controlled study. SETTING: Thirty-four US centers. SUBJECTS: A total of 253 subjects with severe acne vulgaris who showed at least moderate improvement from baseline (50% improvement from baseline) when treated with either adapalene plus doxycycline or doxycycline plus gel vehicle in a previous 12-week study. INTERVENTIONS: Subjects were randomized to receive adapalene gel, 0.1%, or gel vehicle once daily for 16 weeks. MAIN OUTCOME MEASURES: Efficacy and safety criteria included maintenance rate (subjects maintaining at least 50% improvement in lesion counts from previous therapy), lesion counts (total, inflammatory, and noninflammatory), global severity assessment, cutaneous tolerability, and adverse events. RESULTS: Adapalene maintenance therapy resulted in significantly larger maintenance rates (75% vs 54%; P<.001) and significantly lower lesion counts (total [P = .005], inflammatory [P = .01], and noninflammatory [P = .02]) compared with gel vehicle. Adapalene was safe and well tolerated in this study. Conclusion This study demonstrates a clinical benefit of continued treatment with adapalene gel, 0.1%, as a maintenance therapy for acne.

Acne Vulgaris↗

Retinoid-induced epidermal hyperplasia is mediated by epidermal growth factor receptor activation via specific induction of its ligands heparin-binding EGF and amphiregulin in human skin in vivo.

Retinoids are widely used in the treatment of photoaging to stimulate dermal repair. However, retinoids also induce epidermal hyperplasia, which can lead to excessive scaling. Scaling is the major deterrent to topical retinoid therapy. Keratinocyte growth is strongly stimulated via ligand activation of EGFR. We examined regulation of EGFR ligands by retinoids and the role of EGFR in retinoid-induced hyperplasia in human skin in vivo. Topical treatment of human skin with all-trans retinoic acid (tRA) induces EGFR ligands heparin-binding (HB)-EGF and amphiregulin (AR), and reduces betacellulin mRNA levels. Laser capture microdissection-coupled real-time reverse transcription-PCR reveals that tRA increases HB-EGF mRNA throughout the epidermis, whereas AR induction is limited to basal keratinocytes. Topical tRA activates extracellular signal-regulated kinase 1/2 (Erk1/2) downstream EGFR effectors in human skin in vivo. tRA increases the soluble forms of AR and HB-EGF proteins, and induces epidermal hyperplasia, in human skin organ culture. Neutralization of HB-EGF or AR with specific antibodies strongly reduces tRA-induced epidermal hyperplasia. Finally, inhibition of EGFR activation by genistein reduces epidermal hyperplasia caused by topical retinoid treatment. These data demonstrate the central role of EGFR activation in retinoid-induced epidermal hyperplasia, and suggest that EGFR inhibitors can mitigate retinoid-induced scaling.

Amphiregulin↗

Decreased collagen production in chronologically aged skin: roles of age-dependent alteration in fibroblast function and defective mechanical stimulation.

Reduced synthesis of collagen types I and III is characteristic of chronologically aged skin. The present report provides evidence that both cellular fibroblast aging and defective mechanical stimulation in the aged tissue contribute to reduced collagen synthesis. The reduction in collagen synthesis due to fibroblast aging was demonstrated by a lower in vitro production of type I procollagen by dermal fibroblasts isolated from skin of young (18 to 29 years) versus old (80+ years) individuals (82 +/- 16 versus 56 +/- 8 ng/ml; P < 0.05). A reduction in mechanical stimulation in chronologically aged skin was inferred from morphological, ultrastructural, and fluorescence microscopic studies. These studies, comparing dermal sections from young and old individuals, demonstrated a greater percentage of the cell surface attached to collagen fibers (78 +/- 6 versus 58 +/- 8%; P < 0.01) and more extensive cell spreading (1.0 +/- 0.3 vs. 0.5 +/- 0.3; P < 0.05) in young skin compared with old skin. These features are consistent with a lower level of mechanical stimulation on the cells in old versus young skin. Based on the findings presented here, we conclude that reduced collagen synthesis in chronologically aged skin reflects at least two different underlying mechanisms: cellular fibroblast aging and a lower level of mechanical stimulation.

Adolescent↗

Elevated cysteine-rich 61 mediates aberrant collagen homeostasis in chronologically aged and photoaged human skin.

Alterations of human skin connective tissue structure and function are prominent features of chronological aging and solar UV irradiation-induced premature aging (photoaging). These skin connective tissue abnormalities result, in part, from reduced synthesis and elevated degradation of type I collagen, the major structural protein in skin. Here, we report that cysteine-rich 61 (CYR61/CCN1), a novel mediator of collagen homeostasis, is predominantly expressed in human skin connective tissue and is significantly elevated in fibroblasts in chronologically aged (80+ years) and photoaged human skin in vivo. In cultured human skin fibroblasts, elevated CYR61 expression substantially reduces type I procollagen and concurrently increases matrix metalloproteinase-1 (MMP-1), which initiates fibrillar collagen degradation. Elevated CYR61 caused down-regulation of transforming growth factor-beta type II receptor mRNA and protein levels, thereby impairing the transforming growth factor-beta pathway, which reduced type I procollagen and raised MMP-1 expression. Furthermore, elevated CYR61 induced transcription factor activator protein-1 (AP-1), which functions to stimulate MMP-1 expression. Thus, elevated expression of CYR61 in human skin fibroblasts acts through multiple pathways to cause alterations of collagen homeostasis similar to those pathways observed in aged human skin in vivo. These data identify CYR61 as a pivotal regulator of collagen production and degradation in aged and photoaged human skin.

Adult↗

Pan-selectin antagonism improves psoriasis manifestation in mice and man.

The selectin family of vascular cell adhesion molecules is comprised of structurally related carbohydrate binding proteins, which mediate the initial rolling of leukocytes on the activated vascular endothelium. Because this process is one of the crucial events in initiating and maintaining inflammation, selectins are proposed to be an attractive target for the development of new antiinflammatory therapeutics. Here, we demonstrate that the synthetic pan-selectin antagonist bimosiamose is effective in pre-clinical models of psoriasis as well as in psoriatic patients. In vitro bimosiamose proved to be inhibitory to E- or P-selectin dependent lymphocyte adhesion under flow conditions. Using xenogeneic transplantation models, bimosiamose reduced disease severity as well as development of psoriatic plaques in symptomless psoriatic skin. The administration of bimosiamose in patients suffering from psoriasis resulted in a reduction of epidermal thickness and lymphocyte infiltration. The clinical improvement was statistically significant (P=0.02) as analyzed by comparison of psoriasis area and severity index before and after treatment. Assessment of safety parameters showed no abnormal findings. These data suggest that pan-selectin antagonism may be a promising strategy for the treatment of psoriasis and other inflammatory diseases.

Adult↗

Dermal matrix remodeling after nonablative laser therapy.

OBJECTIVE: Nonablative laser therapy is widely practiced for cutaneous rejuvenation. We sought to quantify dermal molecular changes after exposure of photodamaged skin to nonablative laser energy. METHODS: Nonablative laser therapy of forearm skin using either a 585-nm wavelength pulsed dye laser or a 1320-nm wavelength neodymium:yttrium-aluminum-garnet laser was performed. Serial biopsy specimens were obtained at baseline and various times after treatment. RESULTS: Statistically significant increases in type I procollagen messenger RNA expression occurred after exposure of photodamaged skin to each laser. Induction was 47% (P < .05) and 84% (P < .05) above baseline levels 1 week after laser therapy among those treated with the pulsed dye and neodymium:yttrium-aluminum-garnet lasers, respectively. Substantial induction of type III procollagen, various matrix metalloproteinases, and primary cytokines was also demonstrated. Responses with respect to all molecules studied were highly variable. LIMITATIONS: This study addresses molecular changes after a single laser exposure whereas clinically, serial treatments are often provided. CONCLUSIONS: Nonablative laser therapy may result in quantifiable alterations in molecules associated with remodeling of the dermal matrix, although responses vary greatly among patients.

Aged↗

A multicenter, randomized, double-blind trial of tazarotene 0.1% cream in the treatment of photodamage.

BACKGROUND: Previous studies indicate that tazarotene is efficacious in reducing signs of photodamage. Objective We sought to confirm the efficacy and tolerability of tazarotene 0.1% cream in the treatment of facial photodamage. METHODS: A total of 568 patients with at least moderate fine wrinkling or mottled hyperpigmentation applied tazarotene 0.1% cream or vehicle cream to their face once daily for 24 weeks. RESULTS: Tazarotene cream was significantly more effective than vehicle in reducing fine wrinkles, mottled hyperpigmentation, lentigines, irregular depigmentation, apparent pore size, elastosis, tactile roughness, and an overall integrated assessment of photodamage. Significance was achieved as early as week 2 for some parameters and had not plateaued by week 24. The majority of patients reported improvements in their photodamage as early as week 4. Adverse events were predominantly mild or moderate signs or symptoms of skin irritation. CONCLUSION: Once-daily tazarotene 0.1% cream is effective in ameliorating multiple signs of facial photodamage.

Adult↗

Microdermabrasion: a molecular analysis following a single treatment.

BACKGROUND: Microdermabrasion is a popular method of superficial skin resurfacing. It is unclear if dermal remodeling actually occurs. OBJECTIVE: To rigorously investigate the molecular alterations observed following a single microdermabrasion treatment. METHODS: Forty-nine subjects received a single microdermabrasion treatment to buttock skin. Serial in vivo biochemical and immunohistological analyses were performed. Reverse transcriptase real-time polymerase chain reaction and immunohistochemistry assays were used to evaluate changes in transcription factors (AP-1, NF-kappaB), primary cytokines (interleukin-1beta, tumor necrosis factor-alpha), matrix metalloproteinases (MMP-1, MMP-3, MMP-9), barrier repair enzymes (acetyl-coenzyme A carboxylase, 3-hydroxy-3-methylglutaryl coenzyme A reductase), and type I procollagen. Results Elevation of transcription factors, primary cytokines, and matrix metalloproteinases occurs rapidly after a single microdermabrasion treatment. Two of 11 subjects also demonstrated increased type I procollagen messenger RNA and protein levels 14 days after treatment. No alteration in stratum corneum thickness was detected. CONCLUSION: Microdermabrasion activates a dermal remodeling/wound healing cascade with minimal epidermal disruption. Evidence now exists to further study manipulation of variables such as number and timing of microdermabrasion sessions.

Acetyl-CoA Carboxylase↗

Long-term treatment of photoaged human skin with topical retinoic acid improves epidermal cell atypia and thickens the collagen band in papillary dermis.

BACKGROUND: Risk of photocarcinogenesis and the relevance of collagen in wrinkle effacement are two issues related to prolonged use of retinoic acid (RA) that have not been fully addressed. OBJECTIVE: Our purpose was to investigate the degree of epidermal cellular atypia and the thickness of papillary dermal collagen in photoaging after long-term use of RA. METHODS: Thirty-four subjects with photoaged skin were treated daily with 0.05% RA for at least 6 months. Epidermal cellular atypia was graded by means of a semiquantitative scale. Thickness of collagen band was measured by using image-analysis software. RESULTS: Compared with pretreatment findings, melanocytic and keratinocytic atypia was significantly reduced and the collagen band thickness doubled. LIMITATIONS: This was an open-label study. CONCLUSION: Improvement in epidermal cellular atypia is consistent with the ability of RA to act as a chemopreventive agent in epithelial carcinogenesis. Prolonged use also significantly increased collagen matrix deposition in dermal repair zones, which most likely contributes to wrinkle effacement by RA.

Administration, Topical↗

Inflammation and extracellular matrix degradation mediated by activated transcription factors nuclear factor-kappaB and activator protein-1 in inflammatory acne lesions in vivo.

Acne is the most common skin disease, causing significant psychosocial problems for those afflicted. Currently available agents for acne treatment, such as oral antibiotics and isotretinoin (Accutane), have limited use. Thus, development of novel agents to treat this disease is needed. However, the pathophysiology of acne inflammation is poorly understood. Before new therapeutic strategies can be devised, knowledge regarding molecular mechanisms of acne inflammation is required. We report here that transcription factors nuclear factor-kappaB and activator protein-1 are activated in acne lesions with consequent elevated expression of their target gene products, inflammatory cytokines and matrix-degrading metalloproteinases, respectively. These elevated gene products are molecular mediators of inflammation and collagen degradation in acne lesions in vivo. This new knowledge enables a rational strategy for development of pharmacological agents that can target the inflammation and matrix remodeling that occurs in severe acne.

Acne Vulgaris↗

Long-term efficacy and safety of tretinoin emollient cream 0.05% in the treatment of photodamaged facial skin: a two-year, randomized, placebo-controlled trial.

BACKGROUND: Long-term (>1 year) placebo-controlled studies of tretinoin in the treatment of photodamaged skin have not been conducted. Recently, we conducted a 2-year placebo-controlled study of tretinoin emollient cream 0.05%, including histopathologic assessment of safety and analysis of markers of collagen deposition. OBJECTIVE: The objective of the study was to determine the long-term safety and efficacy of tretinoin emollient cream 0.05% in the treatment of moderate to severe facial photodamage. METHODS: A total of 204 subjects were treated with tretinoin or placebo (vehicle emollient cream) applied to the entire face once a day for up to 2 years. Clinical and histologic effects were assessed at regularly scheduled clinic visits. RESULTS: Treatment with tretinoin resulted in significantly greater improvement relative to placebo in clinical signs of photodamage (fine and coarse wrinkling, mottled hyperpigmentation, lentigines, and sallowness), overall photodamage severity, and investigator's global assessment of clinical response (p<0.05). Histologic evaluation showed no increase in keratinocytic or melanocytic atypia, dermal elastosis, or untoward effects on stratum corneum following treatment with tretinoin compared with placebo. Immunohistochemistry studies, conducted at three study centers, showed a significant increase relative to placebo in facial procollagen 1C terminal, a marker for procollagen synthesis, at month 12 (p=0.0074). CONCLUSION: Long-term treatment with tretinoin emollient cream 0.05% is safe and effective in subjects with moderate to severe facial photodamage.

Administration, Topical↗

The mechanism of action of topical retinoids.

UV irradiation of human skin sets in motion a complex sequence of events that causes damage to the dermal matrix. When topical tretinoin is applied to human skin, any collagen deficiency existing in photoaged skin is remedied at least partially, and the skin is primed to prevent further matrix degradation induced by solar UV. Retinoids, therefore, have become essential in the treatment and prevention of photoaging. This article describes the mechanism of action of retinoids, including how they are mediated through retinoic acid receptors (RARs) and retinoid X receptors (RXRs), how they block inflammation mediators, and how production of procollagen is increased to augment the formation of types I and III collagen. Three naturally occurring retinoids are reviewed.

Acne Vulgaris↗

A novel benzodiazepine selectively inhibits keratinocyte proliferation and reduces retinoid-induced epidermal hyperplasia in organ-cultured human skin.

Bz-423 is a new benzodiazepine that has cytotoxic and cytostatic effects against a number of cell types in culture, and recent studies have shown efficacy in experimental lupus models in rodents. The present study demonstrates that treating human skin in organ culture with Bz-423 suppresses retinoid-induced epidermal hyperplasia. Bz-423 suppresses hyperplasia in organ culture at concentrations that also inhibit keratinocyte proliferation in monolayer culture but that are not cytotoxic for keratinocytes and do not inhibit fibroblast growth. Under conditions in which keratinocyte proliferation is inhibited, there is no measurable effect on epidermal growth factor receptor activation, but there is reduced signaling at the level of extracellular signal-regulated kinase 1/2 mitogen-activated protein kinase. Suppression of keratinocyte growth by Bz-423 is associated with generation of intracellular oxidants. However, antioxidant treatment reduces keratinocyte cytotoxicity that occurs at high concentrations of Bz-423, but it does not inhibit growth suppression. Together, these data suggest that Bz-423 has the potential to limit the untoward effects associated with topical retinoid treatment, and in addition, may have therapeutic effects against other forms of epidermal hyperplasia.

Autocrine Communication↗