Bioinspired polydopamine nanoparticles as efficient antioxidative and anti-inflammatory enhancers against UV-induced skin damage

Excessive and prolonged ultraviolet radiation (UVR) exposure causes photodamage, photoaging, and photocarcinogenesis in human skin. Therefore, safe and effective sun protection is one of the most fundamental requirements. Living organisms tend to evolve various natural photoprotective mechanisms to avoid photodamage. Among them, melanin is the main functional component of the photoprotective system of human skin. Polydopamine (PDA) is synthesized as a mimic of natural melanin, however, its photoprotective efficiency and mechanism in protecting against skin damage and photoaging remain unclear. In this study, the novel sunscreen products based on melanin-inspired PDA nanoparticles (NPs) are rationally designed and prepared. We validate that PDA NPs sunscreen exhibits superior effects on photoprotection, which is achieved by the obstruction of epidermal hyperplasia, protection of the skin barrier, and resolution of inflammation. In addition, we find that PDA NPs are efficiently intake by keratinocytes, exhibiting robust ROS scavenging and DNA protection ability with minimal cytotoxicity. Intriguingly, PDA sunscreen has an influence on maintaining homeostasis of the dermis, displaying an anti-photoaging property. Taken together, the biocompatibility and full photoprotective properties of PDA sunscreen display superior performance to those of commercial sunscreen. This work provides new insights into the development of a melanin-mimicking material for sunscreens.

MIF inhibition alleviates vitiligo progression by suppressing CD8+ T cell activation and proliferation

In vitiligo, autoreactive CD8⁺ T cells have been established as the main culprit considering its pathogenic role in mediating epidermal melanocyte-specific destruction. Macrophage migration inhibitory factor (MIF) is a pleiotropic molecule that plays a central role in various immune processes including the activation and proliferation of T cells; but whether MIF is intertwined in vitiligo development and progression and its involvement in aberrantly activated CD8⁺ T cells remains ill-defined. In this study, we found that MIF was overabundant in vitiligo patients and a mouse model for human vitiligo. Additionally, inhibiting MIF ameliorated the disease progression in vitiligo mice, which manifested as less infiltration of CD8⁺ T cells and more retention of epidermal melanocytes in the tail skin. More importantly, in vitro experiments indicated that MIF-inhibition suppressed the activation and proliferation of CD8⁺ T cells from the lymph nodes of vitiligo mice, and the effect extended to CD8⁺ T cells in peripheral blood mononuclear cells of vitiligo patients. Finally, CD8⁺ T cells derived from MIF-inhibited vitiligo mice also exhibited an impaired capacity for activation and proliferation. Taken together, our results show that MIF might be clinically targetable in vitiligo treatment, and its inhibition might ameliorate vitiligo progression by suppressing autoreactive CD8⁺ T cell activation and proliferation. © 2023 The Pathological Society of Great Britain and Ireland.

A Canine Surgical Model of Stroke by Minimally Invasive Occlusion of the Proximal Middle Cerebral Artery

In this study, a model of ischemic stroke by surgical proximal middle cerebral artery (MCA) occlusion was developed on 10 beagle dogs. The advantages of this model are the transtemporal approach and a minimally invasive surgical procedure. Dogs were randomly assigned to two groups: sham-operated (proximal MCA exposure without occlusion) and experimental (permanent proximal MCA occlusion) groups. Different evaluation methods were used to assess the consequences of MCA occlusion in dogs, including neurobehavioral tests, MRI, and immunohistochemical staining. Clear signs of cerebral infarction associated with the region supplied by MCA were confirmed and the model showed good repeatability and consistency. The model can serve as an appropriate large animal model to improve the translation of stroke therapeutics research from the laboratory to the clinical practice.

Chronotype and insomnia may affect the testosterone levels with a sexual difference: a Mendelian randomization

OBJECTIVE

To evaluate the causal effects of sleep traits (i.e., chronotype, insomnia, and sleep duration) on bioavailable testosterone (BT), sex hormone-binding globulin (SHBG), and total testosterone (TT) levels in women and men.

METHODS

We performed Mendelian randomization (MR) using random-effect inverse-variance weighted (IVW) and 7 other MR analyses. Exposure data for sleep traits were obtained from the largest-to-date genome-wide association study (GWAS) from 339,926 to 1,331,010 individuals. Summary data for testosterone levels were obtained from GWAS based on the UK Biobank.

RESULTS

For women, our study supported that chronotype was associated with decreased BT (IVW: β = - 0.042, 95% CI - 0.060, - 0.023, p = 1.17E-05) and TT (IVW: - 0.053, 95% CI - 0.075, - 0.031, p = 2.30E-06). Besides, insomnia can significantly increase BT (IVW: β = 0.025, 95% CI 0.009, 0.041, p = 0.002). These findings were significant in most sensitivity analyses. For men, statistical significance was found between chronotype and BT (β = - 0.027, 95% CI - 0.048, - 0.005, p = 0.016), and insomnia and TT (β = - 0.028, 95% CI - 0.049, 0.007, p = 0.009) in IVW. However, the effect estimates were not broadly consistent with other sensitivity analyses. Our study did not find support for causal effects of sleep duration on testosterone levels in both women and men.

CONCLUSION

Our study reveals the sex differences in the effects of sleep traits on testosterone levels. A healthy sleep habit is vital for the maintenance of testosterone homeostasis in women. Further studies are warranted to investigate the associations between sleep traits and testosterone levels in men.

A population-based cohort study for presence of ulceration among cutaneous malignant melanoma subgroups of patients

BACKGROUND

Observational studies suggest that ulceration is considered to be a negative prognostic factor for cutaneous melanoma. However, the impact of ulceration over different subgroups (e.g. AJCC Stage, thickness level) are controversial and its true causal effect on survival is lack of studies in the view of treating ulceration as an exposure.

OBJECTIVE

To explore the true causal effect of ulceration on melanoma's survival by adopting a combination of methods to discover proper adjustment set and confirming its correctness through a variety of means.

METHODS

A minimal sufficient adjustment set (MSAS) was found using directed acyclic graphs (DAG) to adjust the effect of causality. Sensitivity analysis was conducted to diagnose potential confounders in addition to MSAS. Cox models were built to analyze the causality in-depth and the model was validated using a novel method. Lastly, stratified effects of ulceration were examined to illustrate its impact within subgroups.

RESULTS

Hazard ratio (HR) of ulceration after adjustment by MSAS variables was 1.99 (95% CI=1.88-2.09). The sensitivity analysis of propensity score matching and E-value both demonstrated that variables other than MSAS do not have great influence on ulceration and MSS relationship. The HR of ulceration in AJCC Stage, thickness level, invasion level and tumor extension were all monotonically decreased from 5.76 to 1.57, 4.03 to 1.78, 2.75 to 1.78 and 2.65 to 1.71 respectively.

CONCLUSION

Ulceration in all subgroups were shown to have a significantly negative impact on MSS and its magnitude of effect was monotonically decreased as the disease progressed. The true effect of ulceration can be adjusted by MSAS and its correctness was validated through a variety of approaches.

Treatment of cutaneous Balamuthia mandrillaris infection with diminazene aceturate: a report of 4 cases

Four cases of cutaneous Balamuthia mandrillaris infection were treated with diminazene aceturate. One patient was cured with mainly monotherapy, 2 patients were cured with diminazene aceturate and excision, and 1 patient died of drug induced liver damage. This is the first report of Balamuthia mandrillaris infection treated with diminazene aceturate.

Fractional microneedle radiofrequency device and fractional erbium-doped glass 1,565-nm device treatment of human facial photoaging: a prospective, split-face, random clinical trial

Microneedle fractional radiofrequency (MFR) and non-ablative 1565 nm fractional laser (NAFL) have recently been introduced as new techniques to address the growing concern of facial photoaging. In this prospective randomized split-face study, we wanted to compare the safety and efficacy of MFR with that of NAFL for the treatment of facial photoaging in Asian patients. Fifteen healthy Chinese patients were enrolled for this randomized split-face study. Each patient underwent three sessions of treatment with MFR and NAFL on opposite sides of their face, one month apart. A blinded outcome assessment of the photoaging severity was performed by two independent plastic surgeons on a 5-point visual analogue scale (VAS, 0-4). Patient satisfaction was also scored based on a 5-point VAS (0 = dissatisfaction, 4 = extremely satisfied). Sagging of the nasolabial groove was evaluated using the Antera 3D camera, facial wrinkles and pores using the VISIA skin analysis system. Any adverse events that occurred during the study were also evaluated. Based on the VAS scores and results from the Antera 3D and VISIA, it was noted that there was a significant improvement in facial skin laxity, wrinkles, and pores, and lesser sagging of the nasolabial groove on both the MFR and NAFL sides of the face, compared with that of the baseline. Most patients were satisfied with the treatment and reported tolerable pain and crusting. Although no significant differences were observed between the MFR and NAFL treatments, the NAFL treatment resulted in a shorter downtime(4.56 ± 2.72d) than the MFR treatment(6.96 ± 3.27d). This study confirms the efficacy of MFR and NAFL treatments for facial skin rejuvenation in Asian patients. Furthermore, the therapies were found to be safe and well-tolerated. Our findings suggest that NAFL may be a more convenient treatment modality for facial photoaging because of its shorter downtime. However, sagging of the nasolabial groove was more improved by the MFR treatment than by the NAFL treatment.

NMN recruits GSH to enhance GPX4-mediated ferroptosis defense in UV irradiation induced skin injury

Oxidative stress and lipid peroxidation are major causes of skin injury induced by ultraviolet (UV) irradiation. Ferroptosis is a form of regulated necrosis driven by iron-dependent peroxidation of phospholipids and contributes to kinds of tissue injuries. However, it remains unclear whether the accumulation of lipid peroxides in UV irradiation-induced skin injury could lead to ferroptosis. We generated UV irradiation-induced skin injury mice model to examine the accumulation of the lipid peroxides and iron. Lipid peroxides 4-HNE, the oxidative enzyme COX2, the oxidative DNA damage biomarker 8-OHdG, and the iron level were increased in UV irradiation-induced skin. The accumulation of iron and lipid peroxidation was also observed in UVB-irradiated epidermal keratinocytes without actual ongoing ferroptotic cell death. Ferroptosis was triggered in UV-irradiated keratinocytes stimulated with ferric ammonium citrate (FAC) to mimic the iron overload. Although GPX4 protected UVB-injured keratinocytes against ferroptotic cell death resulted from dysregulation of iron metabolism and the subsequent increase of lipid ROS, keratinocytes enduring constant UVB treatment were markedly sensitized to ferroptosis. Nicotinamide mononucleotide (NMN) which is a direct and potent NAD⁺ precursor supplement, rescued the imbalanced NAD⁺/NADH ratio, recruited the production of GSH and promoted resistance to lipid peroxidation in a GPX4-dependent manner. Taken together, our data suggest that NMN recruits GSH to enhance GPX4-mediated ferroptosis defense in UV irradiation-induced skin injury and inhibits oxidative skin damage. NMN or ferroptosis inhibitor might become promising therapeutic approaches for treating oxidative stress-induced skin diseases or disorders.

A randomized, split-face controlled trial on the safety and effects of microneedle fractional radiofrequency and fractional erbium-doped glass 1,565-nm laser therapies for baggy lower eyelids

The non-ablative fractional erbium-doped glass 1,565-nm laser (NAFL) and the microneedle fractional radiofrequency (MFR) procedures are effective treatments that enable periorbital skin rejuvenation. To compare the clinical effectiveness and side effects of MFR and the NAFL for baggy lower eyelids (BLEs) in the Chinese population. Fifteen Chinese subjects with BLEs received three split-face treatments on a monthly basis randomly. Objective and subjective assessments were performed at baseline, as well as 1 month and 3 months after the third treatment. The results were evaluated using Antera-3D and CineScan systems. Blinded investigator assessments were performed by two plastic surgeons using a 0 to 4 score in six anatomic categories of BLEs. The patients also reported their level of satisfaction based on a four-point score. Most of the patients reported a greater than 47% satisfaction rate with both treatments. The cumulative contribution scores of prolapse of orbital fat, hollow tear trough, and skin laxity for each category variable declined with time. Using Antera 3D, the volume of elevation (mm³) decreased from 0.6 ± 0.4 to 0.4 ± 0.3 and from 0.6 ± 0.3 to 0.3 ± 0.3, the elevation area (mm²) decreased from 17.0 ± 8.4 to 13.0 ± 7.1 and from 17.0 ± 7.8 to 10.0 ± 5.6, and the maximum peak height (mm) also decreased from 0.10 ± 0.04 to 0.06 ± 0.04 and from 0.10 ± 0.03 to 0.06 ± 0.02 in the MFR and NAFL groups, respectively. Using CineScan, the depth of middle orbital fat (mm) decreased significantly from 10.2 ± 2.2 to 8.0 ± 0.7 and from 9.8 ± 1.1 to 8.0 ± 0.9 and the length of orbital fat significantly decreased from 9.2 ± 1.2 to 7.7 ± 0.7 and from 9.7 ± 1.4 to 7.8 ± 0.6 in the MFR and NAFL groups, respectively. MFR and NAFL therapies were effective for the treatment of BLEs, especially in BLE patients with skin elasticity in addition to tear trough deformity and orbital fat prolapse. Trial registration number: NCT04237324. Trial register: ClinicalTrials.gov. Level of Evidence: Level I, therapeutic study.

HSF1-Dependent Autophagy Activation Contributes to the Survival of Melanocytes Under Oxidative Stress in Vitiligo

Autophagy plays a protective role in oxidative stress‒induced melanocyte death. Dysregulated autophagy increases the sensitivity of melanocytes in response to oxidative damage and promotes melanocyte degeneration in vitiligo. However, the molecular mechanism underlying this process is not fully understood. In this study, using RNA-sequencing technology, we compared the transcriptome change between normal and vitiligo melanocytes with or without treatment of oxidative stress. We found that ATG5 and ATG12, the critical components for autophagosome formation, were significantly reduced in vitiligo melanocytes under oxidative stress. Mechanistically, HSF1 is the prime transcription factor for both ATG5 and ATG12, accounting for the reduced level of ATG5 and ATG12 in vitiligo melanocytes. Deficiency of HSF1 led to accumulation of intracellular ROS, imbalance of mitochondrion membrane potential, and apoptosis in melanocytes exposure to oxidative stress. Furthermore, overexpression of HSF1 could ameliorate oxidative stress‒induced melanocytes death through the activation of autophagy by upregulating ATG5 and ATG12. These findings suggested that targeting HSF1-ATG5/12 axis could prevent oxidative stress‒induced melanocyte death and may be used as a therapeutic strategy for vitiligo treatment.

Balamuthia mandrillaris infection in China: a retrospective report of 28 cases

Balamuthia mandrillaris infection is a rare and fatal disease. We have recorded 28 cases of Balamuthia mandrillaris infection during the past 20 years. Eighteen patients (64%) were male and 10 (36%) were female. Patient age ranged from 3 to 74 (mean, 27) years. Patient locations were distributed among 12 Provinces in China. Twenty-seven (96%) patients lived in rural areas, and 17 (61%) patients reported a history of trauma before the appearance of skin lesions. All cases presented with skin lesions as the primary symptom, and 16 (57%) cases developed encephalitis. Histopathology of skin lesions revealed granulomatous changes with histiocytes, lymphocytes, and plasma cells infiltration. Amebas were identified in all cases with immunohistochemical staining. Follow-up information was available in 27 (96%) cases. Fifteen (56%) patients died due to encephalitis and 12 (44%) were free of disease after treatment. Our results show that the clinical characteristics of Balamuthia mandrillaris infection in China are very different from those in the US. Infection of traumatized skin may play an important role in the pathogenesis of the disease in China. Encephalitis usually develops 3–4 years after skin lesions in Chinese cases. Patients with only skin lesions have a higher cure rate than patients with encephalitis.

Gut Microbial Dysbiosis and Plasma Metabolic Profile in Individuals With Vitiligo

Autoimmune diseases are increasingly linked to aberrant gut microbiome and relevant metabolites. However, the association between vitiligo and the gut microbiome remains to be elucidated. Thus, we conducted a case-control study through 16S rRNA sequencing and serum untargeted-metabolomic profiling based on 30 vitiligo patients and 30 matched healthy controls. In vitiligo patients, the microbial composition was distinct from that of healthy controls according to the analysis on α- and β-diversity (P < 0.05), with a characteristic decreased Bacteroidetes: Firmicutes ratio. Meanwhile, the levels of 23 serum metabolites (including taurochenodeoxycholate and L-NG-monomethyl-arginine) in the vitiligo patients were different from those in the healthy individuals and showed significant correlations with some microbial markers. We found that Corynebacterium 1, Ruminococcus 2, Jeotgalibaca and Psychrobacter were correlated significantly with disease duration and serum IL-1β level in vitiligo patients. And Psychrobacter was identified as the most predictive features for vitiligo by machine learning analysis ("importance" = 0.0236). Finally, combining multi-omics data and joint prediction models with accuracies up to 0.929 were established with dominant contribution of Corynebacterium 1 and Psychrobacter. Our findings replenished the previously unknown relationship between gut dysbiosis and vitiligo circulating metabolome and enrolled the gut-skin axis into the understanding of vitiligo pathogenesis.

MSC-derived exosomes protect against oxidative stress-induced skin injury via adaptive regulation of the NRF2 defense system

Oxidative stress is a major cause of skin injury induced by damaging stimuli such as UV radiation. Currently, owing to their immunomodulatory properties, mesenchymal stem cell-derived exosomes (MSC-Exo), as a nanotherapeutic agent, have attracted considerable attention. Here, we investigated the therapeutic effects of MSC-Exo on oxidative injury in H₂O₂-stimulated epidermal keratinocytes and UV-irradiated wild type and nuclear factor-erythroid 2-related factor-2 (Nrf2) knocked down cell and animal models. Our findings showed that MSC-Exo treatment reduced reactive oxygen species generation, DNA damage, aberrant calcium signaling, and mitochondrial changes in H₂O₂-stimulated keratinocytes or UV-irradiated mice skin. Exosome therapy also improved antioxidant capacities shown by increased ferric ion reducing antioxidant power and glutathione peroxidase or superoxide dismutase activities in oxidative stress-induced cell and skin injury. In addition, it alleviated cellular and histological responses to inflammation and oxidation in cell or animal models. Furthermore, the NRF2 signaling pathway was involved in the antioxidation activity of MSC-Exo, while Nrf2 knockdown attenuated the antioxidant capacities of MSC-Exo in vitro and in vivo, suggesting that these effects are partially mediated by the NRF2 signaling pathway. These results indicate that MSC-Exo can repair oxidative stress-induced skin injury via adaptive regulation of the NRF2 defense system. Thus, MSC-Exo may be used as a potential dermatological nanotherapeutic agent for treating oxidative stress-induced skin diseases or disorders.

Tranilast Directly Targets NLRP3 to Protect Melanocytes From Keratinocyte-Derived IL-1β Under Oxidative Stress

The activation of NLRP3 inflammasome-IL-1β pathway in keratinocytes contributes to the melanocyte death via autoimmunity-dependent manner in vitiligo. As a safe small-compound drug employed frequently in clinic, tranilast (TR) is newly reported to block the activation of NLRP3 inflammasome in macrophage. Nevertheless, whether keratinocyte-derived IL-1β damages melanocytes in an autoimmunity-independent way and whether TR could ameliorate the melanocyte damage via inhibiting the NLRP3-IL-1β pathway in keratinocyte still are not clear. In the present study, we initially found that TR could impede the secretion of IL-1β from keratinocytes by interfering the NLRP3 oligomerization. More importantly, we illustrated that TR could decrease the melanocyte apoptosis, improve the melanogenesis, and have the capacity to optimize the melanosome translocation by abolishing the keratinocyte-derived IL-1β. Additionally, TR could mitigate the secretion of inflammatory cytokines such as IL-6, IL-8, TNF-α, and IL-18 in keratinocytes under oxidative stress. In short, our data indicate that IL-1β plays detrimental roles in the melanocyte survival, melanogenesis, melanosome translocation and the secretion of inflammatory cytokines, and TR could be a promising therapeutic strategy in vitiligo by attenuating the keratinocyte-derived IL-1β under oxidative stress.

Intracellular virus sensor MDA5 exacerbates vitiligo by inducing the secretion of chemokines in keratinocytes under virus invasion

Vitiligo is a disfiguring disease featuring chemokines-mediated cutaneous infiltration of autoreactive CD8+ T cells that kill melanocytes. Copious studies have indicated that virus invasion participates in the pathogenesis of vitiligo. IFIH1, encoding MDA5 which is an intracellular virus sensor, has been identified as a vitiligo susceptibility gene. However, the specific role of MDA5 in melanocyte death under virus invasion is not clear. In this study, we first showed that the expression of anti-CMV IgM and MDA5 was higher in vitiligo patients than healthy controls. Then, by using Poly(I:C) to imitate virus invasion, we clarified that virus invasion significantly activated MDA5 and further potentiated the keratinocyte-derived CXCL10 and CXCL16 which are the two vital chemokines for the cutaneous infiltration of CD8+ T cells in vitiligo. More importantly, IFN-β mediated by the MDA5-MAVS-NF-κB/IRF3 signaling pathway orchestrated the secretion of CXCL10 via the JAK1-STAT1 pathway and MDA5-meidiated IRF3 transcriptionally induced the production of CXCL16 in keratinocytes under virus invasion. In summary, our results demonstrate that MDA5 signaling orchestrates the aberrant skin immunity engaging in melanocyte death via mediating CXCL10 and CXCL16 secretion, which supports MDA5 as a potential therapeutic target for vitiligo under virus invasion.

Activated NLR family pyrin domain containing 3 (NLRP3) inflammasome in keratinocytes promotes cutaneous T-cell response in patients with vitiligo

BACKGROUND

Keratinocytes can function as innate immune cells under oxidative stress and aggravate the cutaneous T-cell response that undermines melanocytes in the setting of vitiligo. The NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome is a regulator of innate immunity that exists in keratinocytes. However, the role of the NLRP3 inflammasome in the pathogenesis of vitiligo has not been investigated.

OBJECTIVE

We sought to explicate the contribution of the activated NLRP3 inflammasome in keratinocytes to the autoimmune response in patients with vitiligo.

METHODS

Perilesional and serum samples from patients with vitiligo were collected to examine the status of the NLRP3 inflammasome in the setting of vitiligo. Cultured keratinocytes were treated with H₂O₂ to investigate the mechanism for NLRP3 inflammasome activation under oxidative stress. Peripheral blood T cells were extracted from patients with vitiligo to explore the influence of the NLRP3 inflammasome on the T-cell response in patients with vitiligo.

RESULTS

Expressions of NLRP3 and downstream cytokine IL-1β were consistently increased in perilesional keratinocytes of patients with vitiligo. Notably, serum IL-1β levels were increased in patients with vitiligo, correlated with disease activity and severity, and decreased after effective therapy. Furthermore, oxidative stress promoted NLRP3 inflammasome activation in keratinocytes through transient receptor potential cation channel subfamily M member 2 (TRPM2), a redox-sensitive cation channel, which was dependent on TRPM2-mediated calcium influx. More importantly, blocking TRPM2-induced NLRP3 inflammasome activation in keratinocytes impaired chemotaxis for CD8⁺ T cells and inhibited the production of cytokines in T cells in patients with vitiligo.

CONCLUSION

Oxidative stress-induced NLRP3 inflammasome activation in keratinocytes promotes the cutaneous T-cell response, which could be targeted for the treatment of vitiligo.

Role of the aryl hydrocarbon receptor signaling pathway in promoting mitochondrial biogenesis against oxidative damage in human melanocytes

BACKGROUND

Reactive oxygen species (ROS)-induced mitochondrial damage aggravates oxidative stress and activates mitochondrial apoptosis pathway to mediate melanocyte death. However, the repair mechanisms underlying damaged mitochondria of melanocytes remain unclear. Accumulative evidence has revealed that the aryl hydrocarbon receptor (AHR), a ligand-activated transcription factor, plays a vital role in maintaining mitochondrial homeostasis.

OBJECTIVE

To investigate whether the AHR signaling pathway could protect human melanocytes from oxidative damage through controlling mitochondrial quality.

METHODS

We constructed an oxidative stress model of melanocytes with hydrogen peroxide (H₂O₂) in the human normal melanocyte PIG1 cell line, and detected ROS level, apoptosis, mitochondrial ROS level, mitochondrial membrane potential, ATP production, mitochondrial DNA and mitochondrial modulators after co-treatment with AHR ligand or antagonist and H₂O₂ in the PIG1 cells.

RESULTS

In the present study, we found that H₂O₂-induced oxidative stress directly activated the AHR signaling pathway in melanocytes, whereas abnormal activation of AHR signaling pathway enhanced oxidative damage to mitochondria and melanocytes. Further studies showed that the AHR signaling pathway promoted mitochondrial DNA synthesis and ATP production probably by regulating the expression of nuclear respiratory factor 1 (NRF1) and its downstream targets.

CONCLUSION

Our findings reveal that the AHR signaling pathway might have a major role in protecting melanocytes against oxidative damage via inducing mitochondrial biogenesis, while impaired AHR activation could cause defective repair of mitochondria and exacerbate oxidative damage-induced apoptosis in melanocytes. Our data suggest that the AHR signaling pathway might be a novel mechanism of mitochondrial biogenesis involved in protecting melanocytes from oxidative stress.

Oxidative stress-induced IL-15 trans-presentation in keratinocytes contributes to CD8+ T cells activation via JAK-STAT pathway in vitiligo

Oxidative stress and effector memory CD8⁺ T cells have been greatly implicated in vitiligo pathogenesis. However, the crosstalk between these two crucial pathogenic factors has been merely investigated. IL-15 has been regarded as an important cytokine exerting its facilitative effect on memory CD8⁺ T cells function in various autoimmune diseases. In the present study, we initially discovered that the IL-15 expression was significantly increased in vitiligo epidermis and highly associated with epidermal H₂O₂ content. In addition, epidermal IL-15 expression was mainly derived from keratinocytes. Then, we showed that oxidative stress promoted IL-15 and IL-15Rα expression as well as IL-15 trans-presentation by activating NF-κB signaling in keratinocytes. What's more, the trans-presented IL-15, rather than the secreted one, was accounted for the potentiation of CD8⁺ T_EMs activation. We further investigated the mechanism underlying trans-presented IL-15 in potentiating CD8⁺ T_EMs activation and found that the blockage of IL-15-JAK-STAT signaling could be a potent therapeutic approach. Taken together, our results demonstrate that oxidative stress-induced IL-15 trans-presentation in keratinocytes contributes to the activation of CD8⁺ T_EMs, providing a novel mechanism by which oxidative stress initiates autoimmunity in vitiligo.

Ginkgo biloba extract protects human melanocytes from H2 O2 -induced oxidative stress by activating Nrf2

Vitiligo is a common skin depigmenting disorder characterized by the loss of functional melanocytes. Its pathogenesis is complicated and oxidative stress plays a critical role in the development of vitiligo. Thus, antioxidant therapy is a promising therapeutic strategy to prevent or even reverse the progression of depigmentation. Ginkgo biloba extract EGb761 has been confirmed to have protective effects on neurons against oxidative stress. Notably, several clinical trials have shown that patients with stable vitiligo achieved repigmentation after taking EGb761. However, the exact mechanism underlying the protective effects of EGb761 on melanocytes against oxidative stress has not been fully elucidated. In the present study, we found that EGb761 effectively protected melanocytes against oxidative stress‐induced apoptosis and alleviated the excessive accumulation of reactive oxygen species (ROS) and lipid peroxidation by enhancing the activity of antioxidative enzymes. Furthermore, the antioxidative effect of EGb761 was achieved by activating Nrf2 and its downstream antioxidative genes. In addition, interfering Nrf2 with siRNA abolished the protective effects of EGb761 on melanocytes against oxidative damage. In conclusion, our study proves that EGb761 could protect melanocytes from H₂O₂‐induced oxidative stress by activating Nrf2. Therefore, EGb761 is supposed to be a potential therapeutic agent for vitiligo.

Development of a Consumer Health Vocabulary by Mining Health Forum Texts Based on Word Embedding: Semiautomatic Approach

Background

The vocabulary gap between consumers and professionals in the medical domain hinders information seeking and communication. Consumer health vocabularies have been developed to aid such informatics applications. This purpose is best served if the vocabulary evolves with consumers’ language.

Objective

Our objective is to develop a method for identifying and adding new terms to consumer health vocabularies, so that it can keep up with the constantly evolving medical knowledge and language use.

Methods

In this paper, we propose a consumer health term–finding framework based on a distributed word vector space model. We first learned word vectors from a large-scale text corpus and then adopted a supervised method with existing consumer health vocabularies for learning vector representation of words, which can provide additional supervised fine tuning after unsupervised word embedding learning. With a fine-tuned word vector space, we identified pairs of professional terms and their consumer variants by their semantic distance in the vector space. A subsequent manual review of the extracted and labeled pairs of entities was conducted to validate the results generated by the proposed approach. The results were evaluated using mean reciprocal rank (MRR).

Results

Manual evaluation showed that it is feasible to identify alternative medical concepts by using professional or consumer concepts as queries in the word vector space without fine tuning, but the results are more promising in the final fine-tuned word vector space. The MRR values indicated that on an average, a professional or consumer concept is about 14th closest to its counterpart in the word vector space without fine tuning, and the MRR in the final fine-tuned word vector space is 8. Furthermore, the results demonstrate that our method can collect abbreviations and common typos frequently used by consumers.

Conclusions

By integrating a large amount of text information and existing consumer health vocabularies, our method outperformed several baseline ranking methods and is effective for generating a list of candidate terms for human review during consumer health vocabulary development.

Transcellular traversal of the blood-brain barrier by the pathogenic Propionibacterium acnes

BACKGROUND

Propionibacterium acnes (P. acnes) is an anaerobe commonly stay in the body as part of the commensal microbiota, and a dominant bacterium of the human skin and hair follicles. It has been found that this bacterium could participate in brain inflammation that causes Alzheimer's disease (AD) and Parkinson's disease (PD). But how P. acnes invade the brain remains elusive.

METHODS

We established the in vitro blood-brain barrier (BBB) model by culturing the HBMEC/D3 cell line on collagen-coated PFTE membrane. The BBB model was verified by the transepithelial electrical resistance (TEER) and horseradish peroxidase (HRP) permeability rate, and observed by the scanning electron microscope (SEM), transmission electron microscope (TEM), as well as confocal microscope. The P. acnes was then cocultured with the in vitro BBB model and the permeability of P. acnes was measured by counting the bacteria clones collected from the lower chamber of the model.

RESULTS

High local concentration of P. acnes invaded the in vitro BBB model through the transcellular traversal pathway. The permeability for P. acnes was increased by the treatment of lipopolysaccharide (LPS), but not mannitol. P. acnes invasion elevated the expression of cell adhesion molecules E-selectin, ICAM-1, and VCAM-1 in HBMEC cells.

CONCLUSION

P. acnes has the ability to penetrate the brain though transcellular invasion of the blood-brain barrier.

Oxidative Stress-Induced HMGB1 Release from Melanocytes: A Paracrine Mechanism Underlying the Cutaneous Inflammation in Vitiligo

Vitiligo is a cutaneous depigmentation disorder caused by the destruction of epidermal melanocytes. The generation and the skin infiltration of autoreactive CD8⁺ cytotoxic T cells triggered by oxidative stress play a critical role in vitiligo. High-mobility group protein B1 (HMGB1) is a classic damage-associated molecular pattern molecule with strong proinflammatory effects in inflammatory reactions. A previous study reported an enhanced expression of HMGB1 in vitiligo lesions, but the role of HMGB1 in cutaneous inflammation of vitiligo is still unknown. In the present study, we initially found that HMGB1 was released from the nucleus of melanocytes in vitiligo perilesional skin. Furthermore, cultured normal human melanocytes could release HMGB1 under treatment with hydrogen peroxide. Moreover, HMGB1 facilitated the secretion of CXCL16 and IL-8 from keratinocytes by binding to the receptor for advanced glycation end products and activating NF-κB and extracellular signal-regulated kinase signaling pathways. Subsequently, HMGB1 led to the formation of chemotaxis for the migration of CD8⁺ T cells from patients with vitiligo by increasing the release of CXCL16 from keratinocytes. Additionally, HMGB1 promoted the maturation of dendritic cells from patients with vitiligo. Altogether, our study demonstrates that HMGB1 released from melanocytes contributes to the formation of oxidative stress-induced autoimmunity in vitiligo.

Berberine protects immortalized line of human melanocytes from H2O2-induced oxidative stress via activation of Nrf2 and Mitf signaling pathway

BACKGROUND

Oxidative stress plays important roles in the pathogenesis of vitiligo. The removal of hydrogen peroxided (H₂O₂) has been established to be beneficial to vitiligo patients. Berberine (BBR), a natural isoquinoline alkaloid, has antioxidant activity, however, whether BBR can defend human melanocytes against oxidative injury remains to be elucidated.

OBJECTIVE

In the present study, we investigated the potential protective effect of BBR against oxidative stress on an immortalized normal human melanocyte cell line PIG1.

METHODS

Generally, PIG1 cells were pretreated with various concentrations of BBR for 1 h followed by exposure to 1.0 mM H₂O₂ for 24 h. Cell apoptosis, intracellular reactive oxygen species (ROS) levels were assessed through flow cytometry. Cell apoptosis, melanogenesis and the activation of Nrf2-ARE and Mitf signaling pathway were assayed.

RESULTS

Our results showed that cell viability rose and intracellular ROS generation, cell apoptosis of melanocytes decreased significantly in response to H₂O₂ through pretreatment with BBR. Furthermore, We found that BBR can dramatically induce Nrf2 nuclear translocation, increase total Nrf2 levels and enhance ARE activity. Besides, Nrf2-siRNA transfection can abrogate the protection of BBR in melanocytes against oxidative injury. At last, we verified that BBR could facilitate melanogenesis function via modulation of Mitf and its target proteins.

CONCLUSION

The results above suggest that BBR can protect melanocytes against oxidative stress via its anti-oxidative activity. Also, we found H₂O₂-induced activation of NFκB was inhibited by BBR. Therefore, it is worthy of investigation BBR as a potential drug for treatment of vitiligo.

SIRT3-Dependent Mitochondrial Dynamics Remodeling Contributes to Oxidative Stress-Induced Melanocyte Degeneration in Vitiligo

Mitochondrial dysregulation has been implicated in oxidative stress-induced melanocyte destruction in vitiligo. However, the molecular mechanism underlying this process is merely investigated. Given the prominent role of nicotinamide adenine dinucleotide (NAD⁺)-dependent deacetylase Sirtuin3 (SIRT3) in sustaining mitochondrial dynamics and homeostasis and that SIRT3 expression and activity can be influenced by oxidative stress-related signaling, we wondered whether SIRT3 could play an important role in vitiligo melanocyte degeneration by regulating mitochondrial dynamics.

Methods: We initially testified SIRT3 expression and activity in normal and vitiligo melanocytes via PCR, immunoblotting and immunofluorescence assays. Then, cell apoptosis, mitochondrial function and mitochondrial dynamics after SIRT3 intervention were analyzed by flow cytometry, immunoblotting, confocal laser microscopy, transmission electron microscopy and oxphos activity assays. Chromatin immunoprecipitation (ChIP), co-immunoprecipitation (Co-IP), immunoblotting and immunofluorescence assays were performed to clarify the upstream regulatory mechanism of SIRT3. Finally, the effect of honokiol on protecting melanocytes and the underlying mechanism were investigated via flow cytometry and immunoblotting analysis.

Results: We first found that the expression and the activity of SIRT3 were significantly impaired in vitiligo melanocytes both in vitro and in vivo. Then, SIRT3 deficiency led to more melanocyte apoptosis by inducing severe mitochondrial dysfunction and cytochrome c release to cytoplasm, with Optic atrophy 1 (OPA1)-mediated mitochondrial dynamics remodeling involved in. Moreover, potentiated carbonylation and dampened peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC1α) activation accounted for SIRT3 dysregulation in vitiligo melanocytes. Finally, we proved that honokiol could prevent melanocyte apoptosis under oxidative stress by activating SIRT3-OPA1 axis.

Conclusions: Overall, we demonstrate that SIRT3-dependent mitochondrial dynamics remodeling contributes to oxidative stress-induced melanocyte degeneration in vitiligo, and honokiol is promising in preventing oxidative stress-induced vitiligo melanocyte apoptosis.

Baicalein protects human vitiligo melanocytes from oxidative stress through activation of NF-E2-related factor2 (Nrf2) signaling pathway

Vitiligo is a complex disorder characterized by patchy loss of skin pigmentation due to abnormal melanocyte function. Overwhelming evidences have suggested that oxidative stress plays a major role in the loss of melanocytes thereby mediating the onset and progression of vitiligo. The nuclear factor erythroid 2-like factor 2 (Nrf2) is a master regulator of cellular redox homeostasis and the activation of Nrf2 signaling pathway is impaired in the vitiligo melanocytes. Baicalein, as flavonoid extracted from the Scutellaria baicalensis, has been proved to possess the ability to activate Nrf2 signaling pathway in other cell types and mouse model. Our previous data found that baicalein exerts a cytoprotective role in H₂O₂-induced apoptosis in human melanocytes cell line (PIG1). Based on these founding, we hypothesized that baicalein activates Nrf2 signaling pathway, alleviates H₂O₂-induced mitochondrial dysfunction and cellular damage, thereby protecting human vitiligo melanocytes from oxidative stress. In the present study, we found that baicalein effectively inhibited H₂O₂-induced cytotoxicity and apoptosis in human vitiligo melanocytes (PIG3V). Further results demonstrated that baicalein promoted Nrf2 nucleus translocation as well as up-regulated the expression of Nrf2 and its target gene, heme oxygenase-1 (HO-1). Moreover, the protective effects of baicalein against H₂O₂-induced cellular damage and apoptosis as well as mitochondrial dysfunction were abolished by Nrf2 knockdown. Additionally, we observed that Nrf2 knockdown suppressed proliferation and increased the sensitivity of PIG3V cells to H₂O₂ treatment. Finally, we explored the mechanism of baicalein associated with Nrf2 activation and found that the phosphorylation of Nrf2 as well as ERK1/2and PI3K/AKT signaling were not involved in the baicalein-induced activation of Nrf2. Taken together, these data clearly suggest that baicalein enhances cellular antioxidant defense capacity of human vitiligo melanocytes through the activation of the Nrf2 signaling pathway, providing beneficial evidence for the application of baicalein in the vitiligo treatment.

Identification of the Risk HLA-A Alleles and Autoantigen in Han Chinese Vitiligo Patients and the Association of CD8+T Cell Reactivity with Disease Characteristics

BACKGROUND Multiple studies have implicated a role for CD8+T cell-mediated immune response to autoantigens in vitiligo. However, the antigen-specific T lymphocyte reactivity against the peptide epitopes is diverse among different world populations. This study aimed to identify the risk HLA-A allele in vitiligo and study CD8+ T cell reactivity to 5 autoantigenic peptides in Han Chinese populations, and to analyze the association of CD8+ T cell reactivity with disease characteristics. MATERIAL AND METHODS The risk HLA-A allele was analyzed by case-control study. Enzyme linked immunospot (ELISPOT) assay was used to compare T cell reactivity to the 5 autoantigenic peptides between vitiligo patients and healthy controls, then we analyzed the association of CD8+ T cell reactivity to 2 positive peptides with disease activity and area of skin lesions. RESULTS The results indicated that the most frequent allele in the Han Chinese vitiligo patients was the HLA-A*02: 01 allele with a significantly higher frequency compared to controls (20.20% versus 13.79%, P=6.64×10-5). The most frequently encountered epitopes were 2 gp100 modified peptides, IMDQVPFSV and YLEPGPVTV, whereas a weak T cell reactivity against tyrosinase and Melan-A/MART-1 were evaluated. Moreover, we demonstrated that T cell reactivity against the 2 positive peptides was significantly associated with disease characteristics including disease activity and area of skin lesions. CONCLUSIONS Our findings showed that the HLA-A*02: 01 allele was the major risk HLA-A allele, and 2 gp100 modified peptides were identified as autoantigens and were found to be closely related to disease characteristics which might play a critical role in Han Chinese vitiligo patients.

HO-1 regulates the function of Treg: Association with the immune intolerance in vitiligo

In vitiligo, cutaneous depigmentation is accompanied by increased T cell cytolytic activity targeting melanocytes, indicating that autoimmune tolerance is disrupted. The inhibited amount and function of Tregs have been indicated to be involved in the autoimmune intolerance in vitiligo, however, with the conclusion still controversial and the involved mechanism unknown. In this study, we explored the molecular and cellular alterations accounting for the impaired Treg response in vitiligo. Our results showed that the amount of Tregs was drastically reduced in peripheral blood of active vitiligo patients. Furthermore, the immunoregulatory function of Tregs was attenuated, with lower expression of CTLA4, IL‐10 and TGF‐β. Moreover, the expression of HO‐1, a functional modulator of Tregs, was decreased in vitiligo Tregs, and the concentrations of HO‐1 metabolites, including bilirubin, CoHb and iron, were correspondingly decreased in serum of vitiligo patients. In addition, we treated the Tregs from vitiligo patients with Hemin, an agonist of HO‐1, and found that enhanced HO‐1 expression restored the function of Tregs by up‐regulating IL‐10 expression. Our study demonstrates the essential role of HO‐1 in the impaired Treg response in vitiligo and indicates the potential of HO‐1 as a therapeutic target in vitiligo management.

Topical Application of Tat-Rac1 Promotes Cutaneous Wound Healing in Normal and Diabetic Mice

The endogenous small GTPase, Rac1, plays a critical role during normal skin wound healing. It remains to be determined whether endogenous Rac1 can be appropriately activated in chronic wounds; if not, whether exogenous Rac1 has therapeutic effects on wound healing. Here we show that Rac1 protein levels were lower in wounds of db/db diabetic mice than wounds in wild type mice during the healing process. To assess the therapeutic potential of exogenous Rac1 in wound healing, we produced a Tat-Rac1 fusion protein that enters into cells through protein transduction. Tat-Rac1 increased proliferation and migration of keratinocytes and dermal fibroblasts in vitro. Topical application of Tat-Rac1 accelerated cutaneous wound closure in vivo in db/db mice as well as wild type mice. Further analyses revealed that Tat-Rac1 had faster re-epithelialization, higher keratinocyte proliferation and migration without an earlier onset of myofibroblast activation than vehicle treated wounds. Tat-Rac1 also reduced inflammation in wounds. Our findings revealed the failure of diabetic wounds to elevate Rac1 expression and suggested a therapeutic strategy utilizing a Rac1-based biologic to compensate for this defect thereby promoting wound healing.

Up-regulated deubiquitinase USP4 plays an oncogenic role in melanoma

Melanoma is the most malignant skin cancer with increasing incidence worldwide. Although innovative therapies such as BRAF inhibitor and immune checkpoint inhibitor have gained remarkable advances, metastatic melanoma remains an incurable disease for its notorious aggressiveness. Therefore, further clarification of the underlying mechanism of melanoma pathogenesis is critical for the improvement of melanoma therapy. Ubiquitination is an important regulatory event for cancer hallmarks and melanoma development, and the deubiquitinating enzymes including ubiquitin-specific peptidase (USP) families are greatly implicated in modulating cancer biology. Herein, we first found that the expression of the deubiquitinase USP4 was significantly up-regulated in melanoma tissues and cell lines. Furthermore, although USP4 knockdown had little impact on melanoma cell proliferation, it could increase the sensitivity to DNA damage agent cisplatin. We subsequently showed that USP4 regulated cisplatin-induced cell apoptosis via p53 signalling. More importantly, USP4 could accentuate the invasive and migratory capacity of melanoma cells by promoting epithelial-mesenchymal transition. Altogether, our results demonstrate that the up-regulated USP4 plays an oncogenic role in melanoma by simultaneously suppressing stress-induced cell apoptosis and facilitating tumour metastasis.

A cascaded approach for Chinese clinical text de-identification with less annotation effort

With rapid adoption of Electronic Health Records (EHR) in China, an increasing amount of clinical data has been available to support clinical research. Clinical data secondary use usually requires de-identification of personal information to protect patient privacy. Since manually de-identification of free clinical text requires significant amount of human work, developing an automated de-identification system is necessary. While there are many de-identification systems available for English clinical text, designing a de-identification system for Chinese clinical text faces many challenges such as unavailability of necessary lexical resources and sparsity of patient health information (PHI) in Chinese clinical text. In this paper, we designed a de-identification pipeline taking advantage of both rule-based and machine learning techniques. Our method, in particular, can effectively construct a data set with dense PHI information, which saves annotation time significantly for subsequent supervised learning. We experiment on a dataset of 3000 heterogeneous clinical documents to evaluate the annotation cost and the de-identification performance. Our approach can increase the efficiency of the annotation effort by over 60% while reaching performance as high as over 90% measured by F score. We demonstrate that combing rule-based and machine learning is an effective way to reduce the annotation cost and achieve high performance in Chinese clinical text de-identification task.

SOX4 Promotes Proliferative Signals by Regulating Glycolysis through AKT Activation in Melanoma Cells

The sex-determining region Y-related high-mobility group box transcription factor 4 (SOX4) plays a fundamental role during embryogenesis and controls cell fate and differentiation. Recently, increased SOX4 expression has been reported in various cancer types, contributing to the progression and survival of cancer cells. However, the distinct functions and downstream targets of SOX4 remain to be fully elucidated. In this study, we initially found elevated SOX4 expression in melanoma. SOX4 regulates apoptosis and cell cycle arrest, affects glucose consumption and lactate production, and consequently, promotes melanoma cell proliferation. Moreover, we found that SOX4 rewires glucose metabolism by regulating the expression of glucose transporter type 1, hexokinase 2, and lactate dehydrogenase A at the transcriptional level. Mechanistically, SOX4 knockdown reduced activation of acutely transforming retrovirus AKT8 in rodent T-cell lymphoma and mTORC1, leading to an attenuated malignant phenotype. We also identified p70 ribosomal S6 kinase and eukaryotic initiation factor 4E-binding protein 1 as key substrates involved in the regulation of mTORC1 in melanoma cells. In conclusion, our study demonstrates the essential role of SOX4 in melanoma glycolytic metabolism through the acutely transforming retrovirus AKT8 in rodent T-cell lymphoma signaling pathway and highlights its potential as a therapeutic target in melanoma management.

Multiple pro-tumorigenic functions of the human minor Histocompatibility Antigen-1 (HA-1) in melanoma progression

BACKGROUND

Remodeling of cytoskeleton plays an important role in development of multiple cancers, including melanoma. As a group of F-actin regulators, the Ras homology (Rho) GTPase-activating proteins (ARHGAPs) were reported by accumulating studies as a set of significant mediators in cell morphology, proliferation, migration and invasion.

OBJECTIVE

To investigate the function of HMHA1 and its encode protein HA-1 in melanoma.

METHODS

The mRNA microarray was performed to screen the expression of ARHGAP family genes between melanoma tissues and nevi tissues. QRT-PCR and Western Blot were used to detect the expression of mRNA of HMHA1 and its relevant protein HA-1 respectively. Small interfering RNA was used to knock down the expression of HMHA1. Cell-count kit 8 assays and colony formation assays were used to evaluate the cell proliferative viability of melanoma cells. Flow cytometry was employed to analyze cell apoptosis. Transwell assay and the observation of cell morphology were used to evaluate the invasive and migrating activity of melanoma cells.

RESULTS

In previous study, we first found that both the mRNA level of HMHA1and the expression of HA-1 were up-regulated in melanoma tissues and cell lines compared with nevi tissues and normal human melanocytes respectively. Blocking HMHA1 expression in melanoma cell lines WM35 and A375 suppressed their proliferation and function of colony forming. Moreover, silencing HMHA1 not only significantly increased cell apoptosis but also suppressed cell migration and invasion.

CONCLUSION

Our results demonstrate that HMHA1 significantly promotes melanoma cells proliferation, invasion and migration, and prevents cell apoptosis. Additionally, it can be considered as a new diagnostic marker and drug target of melanoma.

Abstract 477: Down-regulated miR-23a contributes to invasion and metastasis of cutaneous melanoma by promoting autophagy

Background: The occurrence of invasion and metastasis is the major cause of mortality in melanoma. Recent studies suggest that dysregulated miRNAs play critical roles in this procedure, but the underlying mechanism remains elusive. Here, we show that down-regulated miR-23a can promote invasion-metastasis cascade through autophagy in melanoma.Methods: The role of miR-23a in prognosis was assessed in a cohort of melanoma patients (n = 192) with Kaplan-Meier analysis. The effects of miR-23a overexpression were investigated using assays of invasion, migration and in a xenograft model (n = 10 mice per group). Autophagy-related target of miR-23a was confirmed by bioinformatics analysis, luciferase assays and immunoblotting. Molecular studies were performed to determine the downstream cellular and molecular mechanisms. All statistical tests were two-sided.Results: Serum miR-23a level was significantly down-regulated in melanoma patients (P&lt; .001) and was highly correlated with poor clinical outcomes (P = .027, log-rank test). In addition, miR-23a level was remarkably decreased in metastatic melanoma tissues and cell lines (P&lt;.05, P&lt;.01). Moreover, miR-23a overexpression prevented the invasion and migration in vitro and lung and liver metastasis in vivo (both P&lt; .05), by targeting ATG12 and inhibiting autophagy. Mechanically, miR-23a-ATG12 axis attenuated invasion and migration through autophagy-mediated AMPK-RhoA pathway. Finally, the down-regulation of miR-23a in metastatic melanoma was caused by RUNX2 in a transcriptional repression-manner. Conclusion: MiR-23a can act as a crucial epigenetic repressor of melanoma invasion and metastasis in an autophagy-dependent way, which indicates that miR-23a-mediated autophagy inhibition can be exploited to restrain invasion-metastasis cascade in melanoma treatment.

Note: This abstract was not presented at the meeting.

Citation Format: Weinan Guo, Huina Wang, Yuqi Yang, Sen Guo, Weigang Zhang, Tao Zhao, Lin Liu, Zhe Jian, Ling Liu, Gang Wang, Tianwen Gao, Qiong Shi, Chunying Li. Down-regulated miR-23a contributes to invasion and metastasis of cutaneous melanoma by promoting autophagy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 477. doi:10.1158/1538-7445.AM2017-477

Down-regulated miR-23a Contributes to the Metastasis of Cutaneous Melanoma by Promoting Autophagy

Melanoma is among the most aggressive tumors, and the occurrence of metastasis leads to a precipitous drop in the patients' survival. Therefore, identification of metastasis-associated biomarkers and therapeutic targets will contribute a lot to improving melanoma theranostics. Recently, microRNAs (miRNAs) have been implicated in modulating cancer invasion and metastasis, and are proved as potential non-invasive biomarkers in sera for various tumors. Here, we reported miR-23a as a novel metastasis-associated miRNA that played a remarkable role in modulating melanoma invasive and metastatic capacity and was of great value in predicting melanoma metastasis and prognosis. We found that serum miR-23a level was significantly down-regulated in metastatic melanoma patients and highly correlated with poor clinical outcomes. In addition, miR-23a level was also remarkably decreased in metastatic melanoma tissues and cell lines. Furthermore, overexpressed miR-23a suppressed the invasive and migratory property of melanoma cells by abrogating autophagy through directly targeting ATG12. Specially, miR-23a-ATG12 axis attenuated melanoma invasion and migration through autophagy-mediated AMPK-RhoA pathway. Finally, the overexpression of miR-23a prevented melanoma metastasis in vivo. Taken together, our findings demonstrate that the metastasis-associated miR-23a is not only a potential biomarker, but also a valuable therapeutic target for melanoma.

A similar local immune and oxidative stress phenotype in vitiligo and halo nevus

BACKGROUND

Vitiligo and halo nevus are two common T-cell-mediated skin disorders. Although autoimmunity has been suggested to be involved in both diseases, the relationship between vitiligo and halo nevus is not fully understood.

OBJECTIVE

The aim of the current study was to investigate whether vitiligo and halo nevus share the same immunological and oxidative stress response.

METHODS

Infiltrations of T cells, and expressions of chemokine receptors (CXCR3, CCR4, CCR5) and cytotoxic markers (Granzyme B, Perforin) in the lesions of vitiligo and halo nevus were examined by immunohistochemistry. Enzyme-linked immunosorbent assay was performed to analyze the expressions of chemokines in the serum samples and cytotoxic markers secreted by CD8⁺ T cells which were sorted from the peripheral blood mononuclear cells in healthy donors, vitiligo and halo nevus patients. Tissue levels of chemokine receptors and CXCR3 ligands in healthy controls, vitiligo patients and halo nevus patients were determined by qRT-PCR analysis. The percentages of CXCR3⁺ CD4⁺ T and CXCR3⁺ CD8⁺ T cells from the peripheral blood samples were examined by flow cytometry. Tissue and serum hydrogen peroxide (H₂O₂) concentrations were measured using H₂O₂ assay kit.

RESULTS

Immunohistochemistry revealed a significant T-cell response, with pronounced dermal infiltrates of CD8⁺ T cells in vitiligo and halo nevus. The inflammatory cytotoxic markers such as Granzyme B and Perforin were also elevated in vitiligo and halo nevus, suggesting inflammatory responses in situ. By qRT-PCR and ELISA assay, we found significantly increased expressions of the chemokine receptor CXCR3 and its ligands, especially the accumulated CXCL10 in the skin lesions of vitiligo and halo nevus. Moreover, the level of H₂O₂, a key player involved in regulation of the immune response was significantly upregulated in the skin lesions of vitiligo and halo nevus. In addition, the increased H₂O₂ concentration correlated positively with CXCL10 level in skin lesions of vitiligo and halo nevus.

CONCLUSIONS

These results demonstrate a H₂O₂-involved autoimmune phenotype in vitiligo and halo nevus, characterized by increased level of IFN-γ-inducible chemokine pair CXCL10-CXCR3, as well as a dense CD8⁺ T infiltration in the skin lesions, thus suggesting a similar pathogenesis of the two diseases.

Simvastatin Protects Human Melanocytes from H2O2-Induced Oxidative Stress by Activating Nrf2

The prevention of hydrogen peroxide (H₂O₂)-induced oxidative stress has proved to be beneficial to vitiligo patients. Simvastatin possesses antioxidative capacity and has shown protective effect in various oxidative stress-related diseases. However, whether simvastatin can protect human melanocytes against oxidative stress has not been investigated. In this study, we initially found that pretreatment with 0.1 μmol/L to 1.0 μmol/L simvastatin led to increased cell viability and decreased cell apoptosis of melanocytes in response to H₂O₂. In addition, simvastatin was able to potentiate the activity of antioxidant enzymes and lessen intracellular reactive oxygen species accumulation. Furthermore, we found that simvastatin promoted the activation of nuclear erythroid 2-related factor (Nrf2) and that knockdown of Nrf2 abolished the protective effect of simvastatin against H₂O₂-induced oxidative damage. More importantly, the mutual enhancement between mitogen-activated protein kinase pathways and p62 contributed to simvastatin-induced Nrf2 activation in melanocytes. Finally, simvastatin showed more antioxidative capacity and better protective effect than aspirin in H₂O₂-treated melanocytes. Taken together, our results show that simvastatin protects human melanocytes from H₂O₂-induced oxidative stress by activating Nrf2, thus supporting simvastatin as a potential therapeutic agent for vitiligo.

Cancer Stem Cells in Squamous Cell Carcinoma

Cancer stem cells (CSCs) are found in many cancer types, including squamous cell carcinoma (SCC). CSCs initiate cancer formation and are linked to metastasis and resistance to therapies. Studies have revealed that several distinct CSC populations coexist in SCC and that tumor initiation and metastatic potential of these populations can be uncoupled. Therefore, it is critical to understand CSC biology to develop novel CSC-targeted therapies for patients with SCC with poor prognoses. This review compares the properties of CSCs in SCC with normal stem cells in the skin, summarizes current advances and characteristics of CSCs, and considers the challenges for CSC-targeted treatment of SCC.

Oxidative stress drives CD8+ T-cell skin trafficking in patients with vitiligo through CXCL16 upregulation by activating the unfolded protein response in keratinocytes

BACKGROUND

In patients with vitiligo, an increased reactive oxygen species (ROS) level has been proved to be a key player during disease initiation and progression in melanocytes. Nevertheless, little is known about the effects of ROS on other cells involved in the aberrant microenvironment, such as keratinocytes and the following immune events. CXCL16 is constitutively expressed in keratinocytes and was recently found to mediate homing of CD8⁺ T cells in human skin.

OBJECTIVE

We sought to explicate the effect of oxidative stress on human keratinocytes and its capacity to drive CD8⁺ T-cell trafficking through CXCL16 regulation.

METHODS

We first detected putative T-cell skin-homing chemokines and ROS in serum and lesions of patients with vitiligo. The production of candidate chemokines was detected by using quantitative real-time PCR and ELISA in keratinocytes exposed to H₂O₂. Furthermore, the involved mediators were analyzed by using quantitative real-time PCR, Western blotting, ELISA, and immunofluorescence. Next, we tested the chemotactic migration of CD8⁺ T cells from patients with vitiligo mediated by the CXCL16-CXCR6 pair using the transwell assay.

RESULTS

CXCL16 expression increased and showed a positive correlation with oxidative stress levels in serum and lesions of patients with vitiligo. The H₂O₂-induced CXCL16 expression was due to the activation of 2 unfolded protein response pathways: kinase RNA (PKR)-like ER kinase-eukaryotic initiation factor 2α and inositol-requiring enzyme 1α-X-box binding protein 1. CXCL16 produced by stressed keratinocytes induced migration of CXCR6⁺CD8⁺ T cells derived from patients with vitiligo. CXCR6⁺CD8⁺ T-cell skin infiltration is accompanied by melanocyte loss in lesions of patients with vitiligo.

CONCLUSION

Our study demonstrated that CXCL16-CXCR6 mediates CD8⁺ T-cell skin trafficking under oxidative stress in patients with vitiligo. The CXCL16 expression in human keratinocytes induced by ROS is, at least in part, caused by unfolded protein response activation.