Alterations of Dermal Connective Tissue Collagen in Diabetes: Molecular Basis of Aged-Appearing Skin.

Alterations of the collagen, the major structural protein in skin, contribute significantly to human skin connective tissue aging. As aged-appearing skin is more common in diabetes, here we investigated the molecular basis of aged-appearing skin in diabetes. Among all known human matrix metalloproteinases (MMPs), diabetic skin shows elevated levels of MMP-1 and MMP-2. Laser capture microdissection (LCM) coupled real-time PCR indicated that elevated MMPs in diabetic skin were primarily expressed in the dermis. Furthermore, diabetic skin shows increased lysyl oxidase (LOX) expression and higher cross-linked collagens. Atomic force microscopy (AFM) further indicated that collagen fibrils were fragmented/disorganized, and key mechanical properties of traction force and tensile strength were increased in diabetic skin, compared to intact/well-organized collagen fibrils in non-diabetic skin. In in vitro tissue culture system, multiple MMPs including MMP-1 and MM-2 were induced by high glucose (25 mM) exposure to isolated primary human skin dermal fibroblasts, the major cells responsible for collagen homeostasis in skin. The elevation of MMPs and LOX over the years is thought to result in the accumulation of fragmented and cross-linked collagen, and thus impairs dermal collagen structural integrity and mechanical properties in diabetes. Our data partially explain why old-looking skin is more common in diabetic patients.

Expression of catalytically active matrix metalloproteinase-1 in dermal fibroblasts induces collagen fragmentation and functional alterations that resemble aged human skin.

Increased expression of matrix metalloproteinase-1 (MMP-1) and reduced production of type I collagen by dermal fibroblasts are prominent features of aged human skin. We have proposed that MMP-1-mediated collagen fibril fragmentation is a key driver of age-related decline of skin function. To investigate this hypothesis, we constructed, characterized, and expressed constitutively active MMP-1 mutant (MMP-1 V94G) in adult human skin in organ culture and fibroblasts in three-dimensional collagen lattice cultures. Expression of MMP-1 V94G in young skin in organ culture caused fragmentation and ultrastructural alterations of collagen fibrils similar to those observed in aged human skin in vivo. Expression of MMP-1 V94G in dermal fibroblasts cultured in three-dimensional collagen lattices caused substantial collagen fragmentation, which was markedly reduced by MMP-1 siRNA-mediated knockdown or MMP inhibitor MMI270. Importantly, fibroblasts cultured in MMP-1 V94G-fragmented collagen lattices displayed many alterations observed in fibroblasts in aged human skin, including reduced cytoplasmic area, disassembled actin cytoskeleton, impaired TGF-ß pathway, and reduced collagen production. These results support the concept that MMP-1-mediated fragmentation of dermal collagen fibrils alters the morphology and function of dermal fibroblasts and provide a foundation for understanding specific mechanisms that link collagen fibril fragmentation to age-related decline of fibroblast function.

Direct quantitative comparison of molecular responses in photodamaged human skin to fractionated and fully ablative carbon dioxide laser resurfacing.

BACKGROUND: Fractionated ablative laser resurfacing has become a widely used treatment modality. Its clinical results are often found to approach those of traditional fully ablative laser resurfacing. OBJECTIVE: To directly compare the molecular changes that result from fractionated and fully ablative carbon dioxide (CO(2)) laser resurfacing in photodamaged human skin. METHODS AND MATERIALS: Photodamaged skin of 34 adult volunteers was focally treated at distinct sites with a fully ablative CO(2) laser and a fractionated CO(2) laser. Serial skin samples were obtained at baseline and several time points after treatment. Real-time reverse transcriptase polymerase chain reaction technology and immunohistochemistry were used to quantify molecular responses to each type of laser treatment. RESULTS: Fully ablative and fractionated CO(2) laser resurfacing induced significant dermal remodeling and collagen induction. After a single treatment, fractionated ablative laser resurfacing resulted in collagen induction that was approximately 40% to 50% as pronounced as that induced by fully ablative laser resurfacing. CONCLUSIONS: The fundamental cutaneous responses that result from fully ablative and fractionated carbon dioxide laser resurfacing are similar but differ in magnitude and duration, with the fully ablative procedure inducing relatively greater changes including more pronounced collagen induction. However, the molecular data reported here provide substantial support for fractionated ablative resurfacing as an effective treatment modality for improving skin texture.

Molecular analysis of aggressive microdermabrasion in photoaged skin.

OBJECTIVE: To investigate dermal remodeling effects of crystal-free microdermabrasion on photodamaged skin. DESIGN: Biochemical analyses of human skin biopsy specimens following microdermabrasion treatment in vivo. SETTING: Academic referral center. PARTICIPANTS: Volunteer sample of 40 adults, aged 50 to 83 years, with clinically photodamaged forearms. Intervention Focal microdermabrasion treatment with diamond-studded handpieces of varying abrasiveness on photodamaged forearms and serial biopsies at baseline and various times after treatment. MAIN OUTCOME MEASURES: Quantitative polymerase chain reaction, immunohistochemistry, and enzyme-linked immunosorbent assay were used to quantify changes in inflammatory, proliferative, and remodeling effectors of normal wound healing. Type I and type III procollagen served as the main outcome marker of dermal remodeling. RESULTS: Coarse-grit microdermabrasion induces a wound healing response characterized by rapid increase in induction of cytokeratin 16 and activation of the AP-1 transcription factor in the epidermis. Early inflammation was demonstrated by induction of inflammatory cytokines, antimicrobial peptides, and neutrophil infiltration in the dermis. AP-1 activation was followed by matrix metalloproteinase-mediated degradation of extracellular matrix. Consistent with this wound-healing response, we observed significant remodeling of the dermal component of the skin, highlighted by induction of type I and type III procollagen and by induction of collagen production enhancers heat shock protein 47 and prolyl 4-hydroxylase. Dermal remodeling was not achieved when microdermabrasion was performed using a medium-grit handpiece. CONCLUSIONS: Microdermabrasion using a coarse diamond-studded handpiece induces a dermal remodeling cascade similar to that seen in incisional wound healing. Optimization of these molecular effects is likely the result of more aggressive treatment with a more abrasive handpiece.

Topical fluorouracil for actinic keratoses and photoaging: a clinical and molecular analysis.

OBJECTIVE: To examine clinical and molecular changes after topical fluorouracil treatment of photodamaged human facial skin for actinic keratoses. DESIGN: Nonrandomized, open-label 2-week treatment with fluorouracil cream, 5%, followed by clinical and molecular evaluation. SETTING: Academic referral center. PATIENTS: Twenty-one healthy volunteers, 56 to 85 years old, with actinic keratoses and photodamage. Interventions Twice-daily application of fluorouracil cream for 2 weeks and biopsies and clinical evaluation at baseline and periodically after treatment. MAIN OUTCOME MEASURES: Gene and protein expression of molecular effectors of epidermal injury, inflammation, and extracellular matrix remodeling 24 hours after fluorouracil treatment; clinical improvement measured by evaluators, photography, and patient questionnaires. RESULTS: One day after the final fluorouracil treatment, gene expression of the effectors of epidermal injury (keratin 16), inflammation (interleukin 1beta), and extracellular matrix degradation (matrix metalloproteinases 1 and 3) was significantly increased. Types I and III procollagen messenger RNA were induced at week 4 (7-fold and 3-fold, respectively). Type I procollagen protein levels were increased 2-fold at week 24. Actinic keratoses and photoaging were statistically significantly improved. Most patients rated photoaging as improved and were willing to undergo the therapy again. CONCLUSIONS: Topical fluorouracil causes epidermal injury, which stimulates wound healing and dermal remodeling resulting in improved appearance. The mechanism of topical fluorouracil in photoaged skin follows a predictable wound healing pattern of events reminiscent of that seen with laser treatment of photoaging.

Molecular effects of photodynamic therapy for photoaging.

OBJECTIVE: To quantitatively examine the epidermal and dermal cellular and molecular changes that occur after photodynamic therapy of photodamaged human skin. DESIGN: Serial in vivo biochemical and immunohistochemical analyses after photodynamic therapy using topical 5-aminolevulinic acid (5-ALA) and pulsed-dye laser treatment. SETTING: Academic referral center, Department of Dermatology, University of Michigan, Ann Arbor. PATIENTS: A volunteer sample of 25 adults, 54 to 83 years old, with clinically apparent photodamage of the forearm skin. INTERVENTIONS: Three-hour application of 5-ALA followed by pulsed-dye laser therapy using non-purpura-inducing settings to focal areas of photodamaged forearms and serial biopsy specimens taken at baseline and various times after treatment. MAIN OUTCOME MEASURES: Immunohistochemical analysis was used to assess levels of markers of epidermal proliferation (Ki67), epidermal injury (cytokeratin 16), and photodamage (p53), as well as various markers of dermal collagen production (including prolyl 4-hydroxylase and heat shock protein 47, and type I procollagen). Real-time reverse transcriptase-polymerase chain reaction technology was used to quantify type I and type III collagen. Type I procollagen protein was quantified with enzyme-linked immunosorbent assay. RESULTS: Epidermal proliferation was stimulated as demonstrated by increases in Ki67 (more than a 5-fold increase; P < .05) and epidermal thickness (more than a 1.4-fold increase; P < .05). Epidermal injury was produced with increased cytokeratin 16 levels demonstrated (to nearly 70-fold of baseline levels; P < .05). Upregulation of collagen production was demonstrated with increases in procollagen I messenger RNA (2.65-fold; P < .05), procollagen III messenger RNA (3.32-fold; P < .05), and procollagen I protein (2.42-fold; P < .05) levels detected. The baseline epidermal p53 level correlated with cytokeratin 16 levels at acute time points, and the latter were found to correlate with peak collagen production. CONCLUSIONS: Photodynamic therapy with the specific treatment regimen employed produces statistically significant quantitative cutaneous molecular changes (eg, production of types I and III collagen) that are associated with improved appearance of the skin. Baseline epidermal p53 immunostaining levels may be predictive of dermal responses to this therapy. Comparison with historical data using pulsed-dye laser therapy alone suggests that use of the photosensitizer may enhance dermal remodeling. The quantitative in vivo molecular data presented herein are in keeping with an evolving model to potentially predict the efficacy of new techniques for the treatment of photoaging.

Effect of increased pigmentation on the antifibrotic response of human skin to UV-A1 phototherapy.

OBJECTIVE: To investigate the efficacy, potential limitations, and biological mechanisms of UV-A1 phototherapy for skin sclerosis due to collagen deposition disorders. DESIGN: Before-and-after trial of UV-A1 irradiation of sclerotic skin; in vivo biochemical analyses after UV-A1 irradiation of normal skin. SETTING: Academic referral center. PARTICIPANTS: Patients with morphea/scleroderma or sclerodermoid graft-vs-host disease and volunteers without skin disease. Intervention Sclerotic skin was treated with high-dose (130 J/cm(2); n = 12) or medium-dose (65 J/cm(2); n = 6) UV-A1 phototherapy 3 times per week for 14 weeks; normal skin was treated with UV-A1 irradiation at various doses and frequencies, with biopsies performed afterwards. MAIN OUTCOME MEASURES: In sclerotic skin, induration was clinically assessed using a scoring scale. In normal skin, quantitative polymerase chain reaction was used to assess antifibrotic responses, defined as decreased type I and type III procollagen and increased matrix metalloproteinase levels. RESULTS: In patients with sclerotic skin treated with high-dose UV-A1 irradiation, clinical scores for induration modestly decreased. To investigate what factors prevented further improvement (ie, complete clearance), normal skin with light pigmentation was exposed to UV-A1 irradiation (70-150 J/cm(2)) and was assessed for antifibrotic responses. A single high-dose exposure (110-150 J/cm(2)) elicited substantial antifibrotic responses and induced skin darkening. This skin darkening attenuated responses to subsequent UV-A1 exposures and was dose dependent. Thus, to minimize skin darkening, additional patients with sclerotic skin were treated with medium-dose UV-A1 phototherapy, which was no less effective than high-dose therapy. CONCLUSION: Clinical responses of sclerotic skin to UV-A1 phototherapy were modest because of UV-A1-induced skin darkening, which is photoprotective and attenuates antifibrotic responses. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT00129415.

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.

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.

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.

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.

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.

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.

Tretinoin treatment before carbon-dioxide laser resurfacing: a clinical and biochemical analysis.

BACKGROUND: Tretinoin is often prescribed before laser resurfacing in an attempt to enhance results. OBJECTIVE: We sought to assess the clinical and biochemical effects of preoperative tretinoin use before laser resurfacing. METHODS: Patients were randomized to apply tretinoin to one forearm and placebo to the other for 3 weeks. Patients' photodamaged forearms were focally treated by carbon-dioxide laser resurfacing. Biopsy specimens were obtained at baseline and various times posttreatment. Real-time polymerase chain reaction technology was used to quantify messenger RNA levels of types I and III procollagen and matrix metalloproteinases-1, 3, and 9. Wounds were assessed for degree of re-epithelialization using a computer graphics-generated template. A colorimeter was used to quantify postoperative erythema. RESULTS: No substantial differences in either biochemical markers or clinical end points were identified between tretinoin and placebo pretreated forearms. CONCLUSIONS: We found no evidence of enhanced collagen formation, accelerated re-epithelialization, or quicker resolution of postoperative erythema with tretinoin pretreatment before laser resurfacing.

Connective tissue remodeling induced by carbon dioxide laser resurfacing of photodamaged human skin.

OBJECTIVE: To quantitatively examine the dynamics of molecular alterations involved in dermal remodeling after carbon dioxide (CO(2)) laser resurfacing of photodamaged human skin. DESIGN: Serial in vivo biochemical analyses after laser therapy. SETTING: Academic referral center, Department of Dermatology, University of Michigan, Ann Arbor. Subjects Volunteer sample of 28 adults, 48 to 76 years old, with clinically evident photodamage of the forearms. Intervention Focal CO(2) laser resurfacing of photodamaged forearms and serial biopsies at baseline and various times after treatment. MAIN OUTCOME MEASURES: Reverse transcriptase real-time polymerase chain reaction technology and immunohistochemistry were used to assess levels of type I and type III procollagens; matrix metalloproteinases (MMPs) 1, 3, 9, and 13; tropoelastin; fibrillin; primary cytokines interleukin 1beta and tumor necrosis factor alpha; and profibrotic cytokine transforming growth factor beta1. RESULTS: Production of type I procollagen and type III procollagen messenger RNA peaked at 7.5 and 8.9 times baseline levels, respectively, 21 days after treatment and remained elevated for at least 6 months. Increases in messenger RNA levels of several cytokines (interleukin 1beta, tumor necrosis factor alpha, and transforming growth factor beta1) preceded and/or accompanied changes in collagen levels. Marked increases in messenger RNA levels of MMP-1 (39 130-fold), MMP-3 (1041-fold), MMP-9 (75-fold), and MMP-13 (767-fold) were noted. Levels of fibrillin and tropoelastin rose in a delayed fashion several weeks after treatment. CONCLUSIONS: The biochemical changes seen after CO(2) laser resurfacing proceed through a well-organized and highly reproducible wound healing response that results in marked alterations in dermal structure. These quantitative changes may serve as a means for comparison as other therapeutic modalities meant to improve the appearance of photodamaged skin are evaluated.

Effect of carbon dioxide laser resurfacing on epidermal p53 immunostaining in photodamaged skin.

OBJECTIVE: To quantitatively examine changes in p53 tumor suppressor gene immunostaining after carbon dioxide (CO(2)) laser resurfacing of photodamaged skin to assess the potential value of this treatment in reducing the risk of progression to cutaneous carcinoma. DESIGN: Serial in vivo immunohistochemical analyses after laser therapy. SETTING: Academic referral center, Department of Dermatology, University of Michigan, Ann Arbor. OTHER PARTICIPANTS: Volunteer sample of 11 adults, 51 to 76 years old, with clinically evident photodamage of the forearms. INTERVENTION: Focal CO(2) laser resurfacing of photodamaged forearms and serial biopsies at baseline, 3 weeks, and 6 months after treatment. MAIN OUTCOME MEASURES: Because keratinocytes with mutations in p53 or altered p53 expression stain via immunohistochemical techniques, image analysis of immunohistochemically stained sections was used to quantify p53 expression. RESULTS: Positive immunostaining for p53 in the interfollicular epidermis was noted in 8 of 11 subjects at baseline, with an average staining density of 250 cells/mm(2). Average staining decreased to 3 cells/mm(2) 3 weeks after treatment. This decrease was sustained at 5 cells/mm(2) 6 months after resurfacing. CONCLUSIONS: There was a consistent decrease in p53 immunostaining in the interfollicular epidermis lasting for at least 6 moths after CO(2) laser resurfacing of photodamaged skin. Since p53 mutation or overexpression is observed in a majority of cases of cutaneous carcinoma, the posttreatment repopulation of the epidermis with p53-negative keratinocytes should theoretically decrease the risk of malignant progression. Further study of laser resurfacing as a prophylactic procedure in patients at high risk for skin cancer development appears warranted.

Treatment of acne vulgaris with a pulsed dye laser: a randomized controlled trial.

CONTEXT: The high prevalence of acne vulgaris and its significant morbidity underscore the need for convenient, low-risk, and efficacious therapy. Treatment with various lasers has been reported to improve acne. OBJECTIVE: To evaluate the clinical efficacy of pulsed dye laser therapy in the treatment of acne. DESIGN, SETTING, AND PATIENTS: Randomized, single-blind, controlled, split-face clinical trial of a volunteer sample of 40 patients aged 13 years or older with facial acne conducted at an academic referral center from August 2002 to September 2003. INTERVENTION: One or 2 nonpurpuric pulsed dye laser treatments to half of the face (fluence of 3 J/cm2), serial blinded clinical assessments (lesion counts), and grading of acne severity using standardized bilateral serial photographs. MAIN OUTCOME MEASURES: Comparison of the changes in lesion counts from baseline to 12 weeks between treated and untreated sides of the face and changes in photographic evidence of acne severity as graded by a panel of dermatologists blinded to treatment assignment. RESULTS: After 12 weeks, using intent-to-treat analysis with last observation carried forward, there were no significant differences between laser-treated and untreated skin for changes in mean papule counts (-4.2 vs -2.2; P =.08), mean pustule counts (0 vs -1.0; P =.12), or mean comedone counts (2.9 vs 1.6; P =.63). Grading of serial photographs confirmed the clinical assessments, showing no significant mean (SE) differences in Leeds scores (range, 1-12) for treated skin (3.98 [0.32] at baseline and 3.94 [0.27] at week 12) compared with untreated skin (3.83 [0.32] at baseline and 3.79 [0.28] at week 12) (P>.99). CONCLUSIONS: In this study, the nonpurpuric pulsed dye laser therapy did not result in significant improvement of facial acne. More research is needed before this laser therapy may be recommended as an acne treatment.