The effects of Antimicrobial Peptides and Hyaluronic Acid compound mask on wound healing after ablative fractional Carbon Dioxide laser resurfacing.

Background: Fractional carbon dioxide laser resurfacing (FxCR) is a routine treatment of Dermatology while many patients suffered the damage of skin barrier function after FxCR. Objective: To evaluate the benefits of antimicrobial peptides (AMPs) and hyaluronic acid (HA) compound mask on wound healing after FxCR on human and mouse skin. Methods: Twenty-four subjects were treated with FxCR on the bilateral cheeks. AMPs and HA compound mask was applied on the FxCR-treated area of left cheek. The erythema index (EI), melanin index (MI), transepidermal water loss (TEWL) of FxCR-treated areas on both cheeks were measured. By HE staining, immunohistostaing and western blotting, we analyzed epidermal thickness, FLG, IVL expression and protein levels of cramp in FxCR treated dorsal mice skin. Results: The EI, MI, and TEWL in the AMPs and HA compound mask-treated area of left cheek were significantly lower than those in the untreated area of right cheek. Topically application of AMPs and HA compound mask reduced thickening of mouse skin and also result in an increase in the production of FLG, IVL and cramp. Conclusion: Application of AMPs and HA compound mask is an effective method for enhancing wound healing after FxCR, by reducing transient adverse effects such as erythema, hyperpigmentation, and increased TEWL.

The efficacy of intradermal injection of type A botulinum toxin for facial rejuvenation.

The aim of this study is to evaluate the efficacy for effectiveness of type A botulinum toxin intradermal injection for facial rejuvenation. Forty female subjects were randomly divided into two groups: BoNTA group and control group. In BoNTA group, each subject's facial skin was treated with intradermal injection of BoNTA, and subjects of the control group were treated with intradermal saline solution injection. Subjects receiving one session of treatment and evaluations were conducted at baseline, four weeks, and twelve weeks after treatment. The outcome assessments included subjective satisfaction scale; blinded clinical assessment; and the biophysical parameters of roughness, elasticity, skin hydration, transepidermal water loss (TEWL), erythema, and melanin index. BoNTA group showed higher physician's global assessment score, subject satisfaction score, roughness, skin hydration, skin elasticity, and lower TEWL compared to that of control group at 12 weeks post-treatment. No significant difference was found among erythema and melanin index at baseline, four, and twelve weeks after treatment among the two major groups. In conclusion, intradermal BoNTA injection can be considered as an effective method for facial rejuvenation.

The efficacy of fractional carbon dioxide (CO2) laser combined with terbinafine hydrochloride 1% cream for the treatment of onychomycosis.

BACKGROUND: Although systemic and topical antifungal agents are widely used to treat onychomycosis, oral medications can cause adverse effects and the efficacy of topical agents is not satisfying. Currently, laser treatment has been studied for its efficacy in the treatment of onychomycosis. Our study was aimed to evaluate the efficacy of fractional carbon dioxide (CO2) laser treatment combined with terbinafine cream for 6 months in the treatment of onychomycosis and to analyze the influencing factors. METHODS: A total of 30 participants (124 nails) with clinical and mycological diagnosis of onychomycosis received fractional CO2 laser treatment at 2-week interval combined with terbinafine cream once daily for 6 months. The clinical efficacy rate (CER) was assessed from the percentage of fully normal-appearing nails or nails with ≤5% abnormal appearance, and the mycological clearance rate (MCR) was assessed from the percentage of nails with negative fungal microscopy. RESULTS: The CER was evaluated at 3 time points: at the end of treatment (58.9%), at 1 month after the last treatment (63.5%), and at 3 months after the last treatment (68.5%). The MCRs at 1 month and 3 months after the last treatment were 77.4 and 74.2%, respectively. The evaluation of influencing factors showed significantly higher CER (p < 0.05) in nails of participants with age <50 years, distal lateral subungual onychomycosis (DLSO), superficial white onychomycosis (SWO), nail thickness <2 mm, affected first-to-fourth finger/toenails, Trichophyton rubrum, and Trichophyton mentagrophytes. All participants experienced tolerable mild burning sensation during laser treatment, but there were no other adverse reactions reported. CONCLUSIONS: Fractional CO2 laser treatment combined with terbinafine cream for 6 months was an effective and safe method for the treatment of onychomycosis. There were 5 factors that positively influenced the treatment outcome: age, clinical type of onychomycosis, nail thickness, involved nail, and species of fungus.

The self-recovery of facial skin barrier and erythema after nanochip treatment.

OBJECTIVE: To determine the degree of acute skin damage and the time required for the recovery of facial skin barrier function after the skin was treated with micro-needles and nanochips of various tip lengths. METHODS: For this split face comparative study, a total of 16 subjects were enrolled and randomly divided into 2 groups. In the first group, one of the facial side of each subject was treated with 0.25-mm long nanotips for a total of 6 times while the other facial side was treated with 0.25-mm traditional micro-needles with a straight blade for a total of 6 times. In the second group, one of the facial side was treated with 0.5-mm nanotips for a total of 6 times while the other facial side was treated with 0.5-mm traditional micro-needles with a straight blade for a total of 6 times. Evaluations for trans-epidermal water loss (TEWL), skin hydration and erythema were carried out at baseline, 0, 4, 8, 24, 48 and 72 hours after the treatment. RESULTS: There was no significant difference in TEWL, skin hydration and erythema between the two facial sides of the subjects in the Group one who were treated with 0.25 mm nanochips and traditional micro-needles. However, in the subjects of the Group two, the mean TEWL of the facial side treated with 0.5 mm nanochips was relatively lower than that of the 0.5 mm traditional micro-needles treated facial side at 0, 4, 8 and 24 hours after the treatment. Mean erythema of the facial side treated with 0.5-mm nanochips micro-needles was also relatively lower than that of the 0.5-mm traditional micro-needles treated facial side at 8 hours after the treatment. Rapid recovery of skin barrier function was observed within 4-8 hours after treatment with various lengths of nanochips while it took at least 48-72 hours for recovery of skin barrier function after treatment with various lengths of traditional micro-needles as measured by TEWL. CONCLUSION: The skin disruption caused by nanotips treatment recovers quicker than the traditional microneedle treatment at equal lengths.

The efficacy of conditioned media of adipose-derived stem cells combined with ablative carbon dioxide fractional resurfacing for atrophic acne scars and skin rejuvenation.

OBJECTIVE: To evaluate the effects of conditioned medium of adipose-derived stem cells (ADSC-CM) on efficacy and side effects after fractional carbon dioxide laser resurfacing (FxCR) when treating subjects with facial atrophic acne scars or with skin rejuvenation needs. MATERIALS AND METHODS: Twenty-two subjects were enrolled in the study and divided into two groups. Nine subjects were included in skin rejuvenation group and thirteen subjects were included in acne scar group, and all subjects underwent three sessions of FxCR. ADSC-CM was applied on FxCR site of one randomly selected face side. Evaluations were done at baseline, 1 week after first treatment, and 1 month after each treatment. The outcome assessments included subjective satisfaction scale; blinded clinical assessment; and the biophysical parameters of roughness, elasticity, skin hydration, transepidermal water loss (TEWL), and the erythema and melanin index. Biopsies taken from one subject in skin rejuvenation group were analyzed using hematoxylin and eosin, Masson's Trichrome, and Gomori's aldehyde fuchsin staining. RESULTS: ADSC-CM combined with FxCR increased subject satisfaction, elasticity, skin hydration, and skin elasticity and decreased TEWL, roughness, and the melanin index in both acne scars and skin rejuvenation groups. Histologic analysis showed that ADSC-CM increased dermal collagen density, elastin density, and arranged them in order. CONCLUSION: ADSC-CM with FxCR is a good combination therapy for treating atrophic acne scars and skin rejuvenation. TRIAL REGISTRATION: JSPH2012-082 - Registered 14 Feb 2012.

Update on treatment of photodermatosis.

Photodermatoses are a group of skin conditions associated with an abnormal reaction to ultraviolet (UV) radiation. There are several of the photosensitive rashes which mainly affect the UV exposed areas of the skin. It can be classified into four groups: immunology mediated photodermatoses, chemical and drug induced photosensitivity, photoaggravated dermatoses, and genetic disorders. A systematic approach including history, physical examination, phototesting, photopatch testing, and laboratory tests are important in diagnosis of a photodermatosis patient. In order to optimally treat a disease of photodermatoses, we need to consider which treatment offers the most appropriate result in each disease, such as sunscreens, systemic medication, topical medication, phototherapy, and others. For all groups of photodermatoses, photoprotection is one of the essential parts of management. Photoprotection, which includes sunscreening and wearing photoprotective clothing, a wide brimmed hat, and sunglasses, is important. There are also promising emerging photoprotective agents.

Generalized lentiginosis in an 11 year old boy.

Generalized lentiginosis refers to generalized lentigines without systemic abnormalities, characterized by multiple brown or black macules owing to increased proliferation of melanocytes. There are also lentiginosis syndromes associated with systemic abnormalities such as Peutz-Jeghers syndrome, Leopard syndrome, and Carney complex. Generalized lentiginosis can be diagnosis by patient's history, physical and laboratory examination, and histopathology. We report an 11-year-old boy who presented with multiple dark brown macules, varying in size, but less than 0.5 cm, with no abnormalities of other systemic organs.

Differential miRNA profile on photoaged primary human fibroblasts irradiated with ultraviolet A.

Photoaging is cell aging caused by long-wave ultraviolet (UVA) radiation which is the main cause of human skin aging produced by exogenous environment. As an endogenous noncoding small RNA, microRNAs (miRNAs) are sensitive to environmental changes, and the expression change of miRNAs is an important manner to adjust to environment. However, the miRNA profile on photoaged human skin irradiated with UVA remains unknown and whether UVA responsive miRNAs participate in the UVA-caused stress reaction of skin cells is also unclear. In this study, we established an in vitro photoaging model with UVA-radiated human primary cultured fibroblasts, which could mimic UVA-induced photoaging of skin. Differentially expressed miRNAs during photoaging, including five up- and seven downregulated miRNAs, were found by microarray analysis and were verified by quantitative real-time PCR. With bioinformatics methods, the predicted miRNA targets were suggested to be associated with pathways in cancers. Among the significantly UVA-downregulated miRNAs, miR-146a overexpression antagonized the UVA-induced proliferation inhibition and suppressed the upregulation of aging-related genes in photoaging of our model. Western blot and luciferase assay showed that Smad4 might be a target of miR-146a to exert miR-146a functions during photoaging. Therefore, UVA radiation-induced photoaging results in specific patterns of miRNA response and miR-146a are able to antagonize UVA-caused photoaging partially through targeting Smad4.

Palmitic acid induces production of proinflammatory cytokines interleukin-6, interleukin-1ß, and tumor necrosis factor-α via a NF-κB-dependent mechanism in HaCaT keratinocytes.

To investigate whether palmitic acid can be responsible for the induction of inflammatory processes, HaCaT keratinocytes were treated with palmitic acid at pathophysiologically relevant concentrations. Secretion levels of interleukin-6 (IL-6), tumor necrosis factor- α (TNF- α), interleukin-1 ß (IL-1 ß), NF- κ B nuclear translocation, NF- κ B activation, Stat3 phosphorylation, and peroxisome proliferator-activated receptor alpha (PPAR α) mRNA and protein levels, as well as the cell proliferation ability were measured at the end of the treatment and after 24 hours of recovery. Pyrrolidine dithiocarbamate (PDTC, a selective chemical inhibitor of NF- κ B) and goat anti-human IL-6 polyclonal neutralizing antibody were used to inhibit NF- κ B activation and IL-6 production, respectively. Our results showed that palmitic acid induced an upregulation of IL-6, TNF- α , IL-1 ß secretions, accompanied by NF- κ B nuclear translocation and activation. Moreover, the effect of palmitic acid was accompanied by PPAR α activation and Stat3 phosphorylation. Palmitic acid-induced IL-6, TNF- α , IL-1 ß productions were attenuated by NF- κ B inhibitor PDTC. Palmitic acid was administered in amounts able to elicit significant hyperproliferation and can be attenuated by IL-6 blockage. These data demonstrate for the first time that palmitic acid can stimulate IL-6, TNF- α , IL-1 ß productions in HaCaT keratinocytes and cell proliferation, thereby potentially contributing to acne inflammation and pilosebaceous duct hyperkeratinization.

Characterization of the miRNA profile in UVB-irradiated normal human keratinocytes.

The aim of this study was to assess the effects of ultraviolet B (UVB) irradiation on microRNA (miRNA) expression in normal human keratinocytes. Global miRNA expression profiles of primary cultures of normal human keratinocytes 4 and 24 h postirradiation were studied using miRNA microarray with further confirmation by real-time PCR. We found that upon 30 or 60 mJ/cm(2) of UVB radiation, the expression of 44 miRNAs was up- or downregulated more than twofold compared with non-irradiated keratinocytes. MiRNAs were either up- or downregulated after 4 h and then either returned to normal levels or remained affected after 24 h, resulting in four distinct patterns of miRNA expression change. It appears that acute exposure of keratinocytes to UVB radiation results in several specific patterns of miRNA response.

Dihydrotestosterone induces SREBP-1 expression and lipogenesis through the phosphoinositide 3-kinase/Akt pathway in HaCaT cells.

BACKGROUND: The purpose of this study was to investigate the effects and mechanisms of dihydrotestosterone (DHT)-induced expression of sterol regulatory element binding protein-1 (SREBP-1), and the synthesis and secretion of lipids, in HaCaT cells. HaCaT cells were treated with DHT and either the phosphoinositide 3-kinase inhibitor LY294002 or the extracellular-signal-regulated kinase (ERK) inhibitor PD98059. Real time-PCR, Western blot, Oil Red staining and flow cytometry were employed to examine the mRNA and protein expressions of SREBP-1, the gene transcription of lipid synthesis, and lipid secretion in HaCaT cells. FINDINGS: We found that DHT upregulated mRNA and protein expressions of SREBP-1. DHT also significantly upregulated the transcription of lipid synthesis-related genes and increased lipid secretion, which can be inhibited by the addition of LY294002. CONCLUSIONS: Collectively, these results indicate that DHT induces SREBP-1 expression and lipogenesis in HaCaT cells via activation of the phosphoinositide 3-kinase/Akt Pathway.

[Characteristics of grassland degradation and its relationship with climate factors on Qinghai-Tibetan Plateau, China]. / é’è—é«˜åŽŸè‰åœ°é€€åŒ–ç‰¹å¾åŠå ¶ä¸Žæ°”å€™å› å­çš„å ³ç³».

Understanding the distribution, characteristics, and changing trend and persistence of grassland degradation and revealing its mechanism on the Qinghai-Tibetan Plateau can provide scientific basis for effective grassland management and conservation. We selected grassland coverage as the remote sensing monitoring index to establish the remote sensing monitoring and evaluation index system of grassland degradation and evaluate grassland degradation during 2016 to 2020 on the Qinghai-Tibet Plateau. The changing trend and persistence of grassland coverage were analyzed using linear regression and Hurst index analysis on a long time series scale (1982-2020). The partial correlation analysis was used to examine the influence of climate on grassland degradation. The results showed that grassland degradation reached 24.3% during 2016 to 2020, which was mainly light and moderate degradation, and largely distributed in low altitude and high fractional vegetation cover areas. From 1982 to 2020, grassland coverage tended to increase in the north, west and southwest, and decreased in the east and center of the Qinghai-Tibetan Plateau. The Hurst index of grassland coverage was less than 0.5 in 98.1% of the total grassland, indicating grassland coverage showed negatively persistent. The partial correlation coefficient between grassland coverage and precipitation (0.096) was higher than that of temperature (-0.033). About 16.0% area was dominated by temperature, which was mainly distributed in the central and southeast. About 12.2% area was dominated by precipitation, which was distributed in the northeast and west of the Qinghai-Tibetan Plateau.

Platelet-rich plasma regulating the repair of ultraviolet B-induced acute tissue inflammation: adjusting macrophage polarization through the activin receptor-follistatin system.

Ultraviolet B (UVB) is one of the most common exogenous factors in skin aging, especially photoaging. Once a large amount of UVB accumulates within a short period of time, skin tissue can become inflamed. It has also been found in clinics that platelet-rich plasma (PRP) can promote wound repair; therefore, the aim of this study was to identify the mechanism by which PRP repairs UVB-induced skin photodamage. We used PRP of Sprague-Dawley rats with the two-spin technique in the established acute UVB radiation photodamage model and harvested the corresponding skin after 1, 7, and 28 d. Hematoxylin and eosin staining was used to observe tissue inflammation. We found that PRP reduces inflammation in the early stages of UVB-induced acute skin damage, and then promotes the proliferation of collagen in the middle and late stages. Moreover, PRP can stimulate Act A and M1 polarization in the early stage, while inhibiting activin A (Act A) and inducing M2 polarization in the middle and late stages. In conclusion, this study demonstrates that PRP plays an important regulatory role in helping reduce UVB-induced acute skin tissue inflammation by adjusting macrophage polarization, which alleviates skin inflammation and stimulates collagen regeneration.

[Mechanism of telomere shortening in photoaging model induced by 8-methoxypsoralen and ultraviolet A].

OBJECTIVE: To investigate the mechanism of telomere shortening through 8-methoxypsoralen (8-MOP) and subsequent ultraviolet A (UVA) irradiation-induced photoaging model in human dermal fibroblasts (HDFs). METHODS: Photoaging model was established by 8-MOP + UVA in skin HDFs. Flow cytometer, enzyme cytochemistry, immunofluorescence, Western blot and Real-time PCR were employed. RESULTS: The percentage of G1 blockage of 8-MOP + UVA group were higher than that of control group at 24, 48, 72 h and 7 d (61.4% +/- 1.5% vs. 32.8% +/- 1.5%, 69.5% +/- 2.2% vs. 44.9% +/- 2.3%, 88.2% +/- 1.6% vs. 59.8% +/- 1.4%, 90.7% +/- 2.5% vs. 68.5% +/- 2.6%, all P < 0.01). The expression of SA-beta-Gal of 8-MOP + UVA group were higher than that of control group at 24, 48, 72 h and 7 d (34.87% +/- 0.59% vs. 7.11% +/- 0.78%, 59.38% +/- 0.46% vs. 10.57% +/- 0.47%, 72.46% +/- 0.98% vs. 11.67% +/- 0.87%, 94.33% +/- 0.13% vs. 12.04% +/- 0.12%, all P < 0.01). 8-MOP + UVA treatment could significantly aggravate the oxidative DNA damages, the percentage of 8-oxo-dG positive cell of 8-MOP + UVA group (95.78% +/- 0.14%) were significantly higher than that of control group (7.69% +/- 0.09%, P < 0.01), 8-MOP group (9.76% +/- 0.11%, P < 0.01) and UVA group (35.29% +/- 0.14%, P < 0.05). 8-MOP + UVA treatment could accelerate the telomere shortening ,the relative length of telomere of 8-MOP + UVA group were 2.57 +/- 0.05 lower than that of control group (6.63 +/- 0.12, P < 0.01). The levels of P53, P21(WAF-1) and P16(INK-4a) of 8-MOP + UVA group were higher than that of control group (3.00 +/- 0.88 vs. 0.54 +/- 0.10, 2.50 +/- 0.51 vs. 0.42 +/- 0.06, 2.21 +/- 0.34 vs. 0.38 +/- 0.05, all P < 0.01). CONCLUSION: 8-MOP + UVA-induced photoaging of HDFs can be mediated though the regulation of telomere and subsequent P53-dependent signaling pathways.

Mitigation of acute ultraviolet B radiation-mediated damages by baicalin in mouse skin.

BACKGROUND: Solar ultraviolet (UV) irradiation, in particular UVB with a wavelength range between 290 and 320 nm, induces different hazardous effects on the skin, including sunburn, photoaging and cancer. Protection against sun-induced damage is therefore a highly desirable goal. Chemoprevention is being investigated as a potential approach for the management of UV damages including skin cancer. AIM: In this study, to determine the relevance of our in vitro findings to in vivo situations, we assessed the effects of baicalin on UVB-mediated damages in mice skin. METHODS: Balb/C hairless mice were topically pretreated (24 h before UVB) or post-treated (5 min after UVB) with baicalin (1 mg/cm(2) skin area/mouse/100 microl acetone) and were exposed to UVB 24 h later (180 mJ/cm(2)). The animals were sacrificed 1 and 24 h after the UVB exposure. Skin edema, histopathology changes, hydrogen peroxide (H2O2) and cyclobutane pyrimidine dimers (CPDs)-positive cells were assessed to determine the UVB-induced photodamage. RESULTS: Our data demonstrated that a topical application of baicalin, either as a pretreatment or as a post-treatment, resulted in a significant decrease in UVB mediated increases in skin edema, skin hyperplasia and infiltration of leukocytes. Further, baicalin treatments (pre and post) also resulted in a significant decrease in UVB mediated (1) generation of H2O2 and (2) formation of DNA photolesions: CPDs. CONCLUSION: Based on these data, we suggest that baicalin could be developed as an agent for the management of conditions elicited by UV exposure including skin cancer.

Case series of neck accessory tragus.

We report three cases of neck accessory tragus, which is the largest number of cases with dermatologists reported in China. Neck accessory tragus belongs to special accessory auricular anomaly. Case 1: A 5-year-old girl presented with a skin-colored mass above her right clavicle since birth. Physical examination revealed a pea-sized mass positioned above the right clavicle. Case 2 and case 3 were a 3-month-old female infant and a 4-month-old male infant, respectively. Both of their parents complained that the masses gradually increased in front of the neck. Histopathologically, all of the three cases showed cartilage beneath the subcutaneous tissue. All cases were diagnosed as cervical auricles.

Corrigendum to "The Effect of Botulinum Toxin Type A on Expression Profiling of Long Noncoding RNAs in Human Dermal Fibroblasts".

[This corrects the article DOI: 10.1155/2017/2957941.].

Acute myeloid leukemia with adult atopic dermatitis as first manifestation: A case report.

RATIONALE: Atopic dermatitis (AD) is a chronic recurrent dermatitis with profound itching, which could be the first manifestation of acute myeloid leukemia (AML). PATIENT CONCERNS: A 53-year-old Chinese man suffered a 6-month history of systemic symmetrical dermatitis, accompanied with profound itching. The patient was diagnosed as "eczema" in several hospitals, and the effects of antihistamine and topical steroid creams were poor. Nocturnal sleep was seriously affected by aggravating pruritus. Laboratorial examination was compatible with AML-M4. DIAGNOSES: AML-M4 with AD as first manifestation. INTERVENTIONS: IA regimen (ayninen and cytarabine) were used in induction chemotherapy. However, the patient did not achieve complete remission, and although his rash had improved, he still experienced severely general body itching. On the seventh day of chemotherapy, the patient entered the period of granulocyte deficiency with infection. OUTCOMES: The patient died due to septic shock after chemotherapy. LESSONS: The case strengthens the awareness of AML with AD as first manifestation and raises oncological vigilance in patients with AD refractory.

Botulinum toxin type A for the treatment and prevention of hypertrophic scars and keloids: Updated review.

Botulinum Toxin Type A is a potent neurotoxin that is produced by a gram-positive bacteria clostridium botulinum. Its utilization in the treatment of various medical condition has expanded over the years in both medical and esthetic uses. It is being preferred by most physicians due to its efficacy and lack of side effects. It can be used as monotherapy or combined therapy. The aim of this review study was to show the role and mechanism of action of Botulinum toxin type A in the treatment and prevention of hypertrophic scars and keloids. The clear mechanisms underlying hypertrophic scars and keloids are still not clearly understood; however, the mechanism of action of Botulinum toxin type A has been shown to include action on wound tension, action on collagen, and action on fibroblasts. Different randomized controlled trials, double-blind, and placebo-controlled studies have been conducted to investigate its use in treatment and prevention of hypertrophic scars and keloids, and it still is one of the active areas of research in Dermatology and related fields. Method: In March 2018, we performed a literature search in PubMed for clinical studies, clinical trials, case reports, controlled trials, randomized controlled trials, and systemic reviews. The search terms we used were "BOTULINUM TOXIN" AND "HYPERTROPHIC SCARS" OR "KELOIDS" (from 1980). The search resulted in 1000 articles, out of these 35 articles met our inclusion exclusion criteria. Our inclusion criteria included relevant original articles relevant, critical systemic reviews, and crucial referenced articles, exclusion criteria included duplicates and articles not published in English language. We have reviewed these papers to show the role and mechanism of action of Botulinum toxin type A in the treatment and prevention of hypertrophic scars and keloids.

5-aminolaevulinic acid-based photodynamic therapy inhibits ultraviolet B-induced skin photodamage.

To evaluate the photoprotective effect of 5-aminolaevulinic acid-based photodynamic therapy (ALA-PDT) on ultraviolet B (UVB)-induced skin photodamage. In vivo experiments, the dorsal skin of hairless mice were treated with ALA-PDT or saline-PDT, and then exposed to 180 mJ/m2 UVB. Results showed that the number of sunburn cells and apoptotic cells in the epidermis of ALA-PDT-treated groups at 24 h after UVB irradiation were significantly decreased compared with those in the UVB groups. And the removal rate of CPDs was obviously higher in ALA-PDT-treated groups. At 48 h, the number of Ki67 positive nuclei in ALA-PDT-UVB group was significantly fewer than that in UVB group. Further in vitro experiments, human keratinocyte cell line (HaCaT) cells of two groups (one treated with ALA-PDT, the other untreated), were exposed to 60 mJ/m2 UVB irradiation. We found 0.5 mmol/L of ALA and 3 J/cm2 of red light did not affect the vitality of cells, and could reduce UVB induced apoptosis, accelerate the clearance of CPDs, inhibit proliferation and activate p53. Thus, our data demonstrate that ALA-PDT pretreatment can induce a protective DNA damage response that protects skin cells from UVB-induced photodamages.