Pimecrolimus increases the melanogenesis and migration of melanocytes in vitro

H2 O2 -induced oxidative stress disrupts mitochondrial functions and impairs migratory potential of human epidermal melanocytes

Reactive oxygen species (ROS) have already been demonstrated to impede the migratory ability in non-melanocytic cell lines by depleting mitochondrial ATP production. Therefore, understanding the mitochondrial metabolic response to migration in the presence of ROS should be a key to understanding repigmentation in vitiligo. This study aimed to investigate the energy mechanism associated with the ROS-mediated attenuation of melanocyte migration. After melanocytes were pretreated with H₂ O₂ , their ATP production, migratory ability, ultrastructural changes and Mitochondrial Permeability Potential were analysed. The results showed that, in parallel with the decreased ATP production, the migratory ability of melanocytes was significantly inhibited by oxidative stress. Supplementation with exogenous ATP reversed the suppressed ATP-dependent migration of melanocytes. Melanocytes were then stressed with H₂ O₂ and Agilent Whole Human Genome microarray analysis identified 763 up-regulated mRNAs and 1117 down-regulated mRNAs. Among them, 11 of the encoded proteins were involved in mitochondrial ATP production and their expression levels were verified. The decreased expression of NADH dehydrogenase 2(ND₂₎ , cytochrome c oxidase 1(COX1) and cytochrome c oxidase 3(COX3) was shown to be involved in the depletion of mitochondrial ATP production, which was coupled with the impaired migratory potential. These results indicate that the migration of melanocytes relies heavily on an inexhaustible supply of ATP from mitochondria.

Therapeutic candidates for keloid scars identified by qualitative review of scratch assay research for wound healing

The scratch assay is an in vitro technique used to analyze cell migration, proliferation, and cell-to-cell interaction. In the assay, cells are grown to confluence and then ‘scratched’ with a sterile instrument. For the cells in the leading edge, the resulting polarity induces migration and proliferation in attempt to ‘heal’ the modeled wound. Keloid scars are known to have an accelerated wound closure phenotype in the scratch assay, representing an overactivation of wound healing. We performed a qualitative review of the recent literature searching for inhibitors of scratch assay activity that were already available in topical formulations under the hypothesis that such compounds may offer therapeutic potential in keloid treatment. Although several shortcomings in the scratch assay literature were identified, caffeine and allicin successfully inhibited the scratch assay closure and inflammatory abnormalities in the commercially available keloid fibroblast cell line. Caffeine and allicin also impacted ATP production in keloid cells, most notably with inhibition of non-mitochondrial oxygen consumption. The traditional Chinese medicine, shikonin, was also successful in inhibiting scratch closure but displayed less dramatic impacts on metabolism. Together, our results partially summarize the strengths and limitations of current scratch assay literature and suggest clinical assessment of the therapeutic potential for these identified compounds against keloid scars may be warranted.

A comparative study on the use of fractional CO2 laser with tacrolimus or calcipotriol or narrow band ultraviolet-B in treatment of stable nonsegmental vitiligo

Conventional methods of treatment for vitiligo are often unsatisfactory to the patients and time consuming, new treatment modalities are needed. This study was conducted to evaluate the efficacy and safety of fractional carbon dioxide (CO₂ ) laser therapy followed by narrow band ultraviolet-B (NB-UVB) phototherapy, topical tacrolimus or topical calcipotriol on stable nonsegmental vitiligo. Thirty patients with stable nonsegmental vitiligo were evaluated. All patients were subjected to three sessions of fractional CO₂ laser 1 month apart. Patients were divided into three groups (each group 10 patients). Group (A) treated with tacrolimus ointment twice daily for 3 months, group (B) treated with calcipotriol ointment twice daily for 3 months, and group (C) treated with NB-UVB twice weekly for 3 months. Outcomes were evaluated by calculating vitiligo area scoring index (VASI) score change, percentage of repigmentation, patient satisfaction, and adverse effects. There was a statistical significant decrease in VASI score after treatment in the three groups. The VASI change and % of regimentation was higher in group (C) treated by laser and NB-UVB and this was significantly higher than group (B) treated with laser and calcipotriol. Otherwise, there was no statistical significant difference between other treatment groups. In concluion, NB-UVB phototherapy, topical tacrolimus, or topical calcipotriol in combination with fractional CO₂ laser could be used effectively and safely as an alternative modality for treatment of vitiligo. The combination of fractional CO₂ laser and NB-UVB was found to be more effective.

Treatment Outcomes of Topical Calcineurin Inhibitor Therapy for Patients With Vitiligo: A Systematic Review and Meta-analysis

Importance

Topical calcineurin inhibitors (TCIs), including tacrolimus and pimecrolimus, have been widely used for the treatment of vitiligo; however, the efficacy of TCI monotherapy is often underestimated.

Objectives

To estimate the treatment responses to both TCI monotherapy and TCI accompanied by phototherapy for vitiligo, based on relevant prospective studies, and to systematically review the mechanism of action of TCIs for vitiligo treatment.

Data Sources

A comprehensive search of the MEDLINE, Embase, Web of Science and Cochrane Library databases from the date of database inception to August 6, 2018, was conducted. The main key words used were vitiligo, topical calcineurin inhibitor, tacrolimus, pimecrolimus, and FK506.

Study Selection

Of 250 studies initially identified, the full texts of 102 articles were assessed for eligibility. A total of 56 studies were identified: 11 studies on the TCI mechanism, 36 studies on TCI monotherapy, 12 studies on TCI plus phototherapy, and 1 study on TCI maintenance therapy.

Data Extraction and Synthesis

Two reviewers independently extracted data on study design, patients, intervention characteristics, and outcomes. Random-effects meta-analyses using the generic inverse variance weighting were performed for the TCI monotherapy and TCI plus phototherapy groups.

Main Outcomes and Measures

The primary outcomes were the rates of at least mild (≥25%), at least moderate (≥50%), and marked (≥75%) repigmentation responses to treatment. These rates were calculated by dividing the number of participants in an individual study who showed the corresponding repigmentation by the total number of participants who completed that study.

Results

In the 56 studies included in the analysis, 46 (1499 patients) were selected to evaluate treatment response. For TCI monotherapy, an at least mild response was achieved in 55.0% (95% CI, 42.2%-67.8%) of 560 patients in 21 studies, an at least moderate response in 38.5% (95% CI, 28.2%-48.8%) of 619 patients in 23 studies, and a marked response in 18.1% (95% CI, 13.2%-23.1%) of 520 patients in 19 studies after median treatment duration of 3 months (range, 2-7 months). In the subgroup analyses, face and neck lesions showed an at least mild response in 73.1% (95% CI, 32.6-83.5%) of patients, and a marked response in 35.4% (95% CI, 24.9-46.0%) of patients. For TCI plus phototherapy, an at least mild response to TCI plus phototherapy was achieved in 89.5% (95% CI, 81.1-97.9%) of patients, and a marked response was achieved in 47.5% (95% CI, 30.6-64.4%) of patients.

Conclusions and Relevance

The use of TCIs, both as a monotherapy and in combination with phototherapy, should be encouraged in patients with vitiligo.