Dynamic Optical Coherence Tomography of Cutaneous Blood Vessels in Melasma and Vessel Response to Oral Tranexamic Acid

Semaxanib, a VEGF inhibitor, suppresses melanogenesis by modulating CRTC3 independently of VEGF signaling

BACKGROUND

Dysregulation of melanogenesis contributes to the development of skin hyperpigmentation diseases, which poses a treatment challenge. Following the establishment of CRTC3 screening methods to explore small molecules inhibiting melanogenesis for the topical treatment of hyperpigmentation diseases, we identified a candidate molecule, semaxanib.

OBJECTIVE

To explore the antimelanogenic effects of semaxanib, a vascular endothelial growth factor receptor (VEGFR) 2 inhibitor, for potential applications in hyperpigmentation management and to unravel the role of VEGF signaling in melanocyte biology by investigating mechanism of action of semaxanib.

METHODS

Mouse-derived spontaneously immortalized melanocytes, B16F10, and normal human primary epidermal melanocytes cells were treated with semaxanib, and cellular responses were assessed using cell viability assays and melanin content measurements. Molecular mechanisms were investigated using transcriptional activity assays, reverse-transcription polymerase chain reaction, and immunoblotting analysis. In vivo studies were conducted using an epidermis-humanized transgenic mouse model and ex vivo human skin tissues.

RESULTS

Semaxanib ameliorated melanin content in cultured melanocytes by downregulating the expression of melanogenesis-associated genes by suppressing the CRTC3/microphthalmia-associated transcription factors. Topical application of semaxanib reduced melanin accumulation in the ultraviolet B-stimulated ex vivo human epidermis and tail of K14-stem cell factor transgenic mice. Mechanistically, the antimelanogenic effect induced by semaxanib was associated with SIK2-CRTC3-MITF rather than VEGF signaling in melanocytes.

CONCLUSION

Semaxanib emerges as a promising candidate for the development of therapeutics for hyperpigmentation, potentially working independently of VEGF signaling in human melanocytes.

An Update on New and Existing Treatments for the Management of Melasma

Melasma is a chronic, acquired disorder of focal hypermelanosis that carries significant psychosocial impact and is challenging for both the patient and the treating practitioner to manage in the medium to long term. Multiple treatments have been explored, often in combination given the many aetiological factors involved in its pathogenesis. Therapeutic discoveries to treat melasma are a focal topic in the literature and include a range of modalities, with recent developments including updates on visible light photoprotection, non-hydroquinone depigmenting agents, oral tranexamic acid, chemical peels, and laser and energy-based device therapy for melasma. It is increasingly important yet challenging to remain up-to-date on the arsenal of treatments available for melasma to find an efficacious and well-tolerated option for our patients.

Melasma: A Step-by-Step Approach Towards a Multimodal Combination Therapy

Melasma is a common challenge in the field of pigmentary skin disorders, exerting a significant emotional and psychosocial burden on patients. The persistent and recurring nature of melasma complicates its management in routine clinical practice. This comprehensive review outlines a stepwise, practical approach encompassing diagnostic, preventive and therapeutic strategies for the management of melasma. A thorough exploration of aggravating and exacerbating factors, including sun exposure, hormonal imbalances, photosensitizing medication and cosmetics, is essential for a holistic assessment of the disease. With an emphasis on consistent and effective photoprotection, initial topical treatment modalities target the melanin production and/or the transfer of melanosomes to keratinocytes. Topical tyrosine inhibitors emerge as the first choice for reducing and preventing hyperpigmentation, with compounds such as thiamidol or tranexamic acid (TXA) being preferred for their safety profile over hydroquinone (HQ), kojic acid and arbutin. Combination with chemical peels can further enhance the therapeutic efficacy, even in cases with resistant melasma. In more severe cases, laser- and light-based interventions may be considered, but with the caveat of the likelihood of recurrence within 3-6 months. Assisted TXA delivery, via either fractional non-ablative laser or microneedling techniques, can further improve clinical outcomes. In conclusion, an optimal melasma management strategy is a multimodal approach, which includes effective photoprotection and a mix of different topical treatments targeting melanin synthesis, the anti-inflammatory environment, senescence and vascularity. Complementary procedures, such as chemical peels, and laser, light-based or microneedling procedures, with or without TXA, can further expedite melanin clearance in more severely affected instances. Individual discussions with patients regarding treatment expectations, recurrence likelihood and potential side effects are paramount to a comprehensive and successful therapeutic journey.

Characteristics of dermal vascularity in melasma and solar lentigo

BACKGROUND /PURPOSE

Melasma and solar lentigo (SL) are major benign hyperpigmented lesions, and both have been shown to involve the dermal vasculature. This review discusses current knowledge regarding the clinical characteristics of dermal vascularity in melasma and SL, as well as the results of relevant molecular biological investigations.

METHODS

PubMed and Google Scholar were searched in December 2023 to identify articles related to melasma, SL, and the dermal vasculature in these lesions.

RESULTS

Vascular morphologies in melasma and SL have been detected by histological and non-invasive methods, including modalities such as optical coherence tomography. Biological studies have indicated that factors secreted from vascular endothelial cells, such as stem cell factor and endothelin-1, can promote melanogenesis. With respect to phototherapy, blood vessel-targeting laser treatments are expected to provide long-term suppression of pigmentation, but this regimen is only effective when dilated capillaries are visible.

CONCLUSION

In both melasma and SL, clinical and experimental investigations are revealing the contributions of dermal vascularity to hyperpigmentation. More effective treatment may require identification of hyperpigmentation subtypes. In the future, knowledge of treatment (including phototherapy) is expected to accumulate through reliable and validated non-invasive measurements.

[Advances in optical coherence tomography]

Optical coherence tomography (OCT) has been able to establish itself in recent years not only in academic-scientific, but also in everyday dermatological practice. Its focus lies on epithelial tumors of the skin, which can be diagnosed intuitively and within a few seconds. Thus, basal cell carcinomas, actinic keratoses, and different stages of field cancerization can be diagnosed and monitored for response to therapy or possible recurrence. This often helps to avoid invasive sample extraction. Recently, the field of OCT and its latest advancement, dynamic OCT (D-OCT), has been expanded to include non-oncologic dermatological diseases. This encompasses inflammatory dermatoses and the analysis of physiological skin parameters such as hydration. Thanks to automated vascular imaging and the measurement of objective parameters such as epidermal thickness, blood flow at depth, optical attenuation coefficient, and skin roughness, more and more characteristics of the skin can be studied in a noninvasive and standardized way. New potential areas of application are eczema, contact allergic dermatitis, psoriasis, rosacea, telangiectasia, acute and chronic wounds, melasma and nevus flammeus but also melanocytic lesions.

Combining Low Power Fractional CO2 With QS-NdYAG Toning in the Treatment of Melasma Reduces the Incidence of Punctate Leukoderma

BACKGROUND AND OBJECTIVES

Q-switched Nd:YAG (QS-Nd:YAG) toning (low fluence, large spot size, and high frequency) has been used successfully for the treatment of melasma, especially in dark skin phototypes. Punctate leukoderma was found to be a frequent complication that reduced the safety of this procedure. Combining low power fractional CO₂ laser, which is another effective melasma laser therapy, might improve the efficacy and safety of this procedure. The aim of this study was to evaluate  the effect of combining low power fractional CO₂ laser with QS-Nd:YAG toning in the treatment of melasma.

STUDY DESIGN/MATERIALS AND METHODS

A randomized comparative split-face study included a total of 30 patients with bilateral, symmetrical melasma. All patients received QS-Nd:YAG toning on one randomly selected side of the face, while the other side randomly received either low power fractional CO₂ alone (group A) or combined QS-Nd:YAG toning with low power fractional CO₂ (group B). QS-Nd:YAG toning sessions were scheduled every two weeks for nine consecutive sessions, and low power fractional CO₂ sessions were received every 4 weeks for three consecutive sessions. The assessment was done using the modified melasma area and severity index (mMASI) score, spectrophotometry (melanin index [MI] and erythema index [EI]), photography, blinded physician assessment, and patient satisfaction (at baseline, 1 week and 8-12 weeks after the last treatment sessions).

RESULTS

A significant reduction in the mMASI score and MI was obtained with all treatment regimens. On comparing different modalities, group A reduction in mMASI and MI was significantly greater on the side receiving QS-ND:YAG toning (64.03% and 8.27%, respectively), than the side receiving low power fractional CO₂ laser alone (36.02%. 2.64%, respectively). On the other hand, reduction of mMASI score and MI showed no statistical significance between the side receiving QS-Nd:YAG toning alone and the combined modality. Punctate leukoderma occurred in four cases (13%) on the side receiving QS-Nd:YAG toning.

CONCLUSION

QS-Nd:YAG toning is significantly more effective than low power fractional CO₂ in the treatment of melasma when used separately. Although combining low power fractional CO₂ with QS-Nd:YAG toning does not increase its efficacy, it minimizes the incidence of the undesirable punctate leukoderma complication and achieves lower recurrence. This combination can thus be recommended as a safe and effective measure for the treatment of melasma. © 2021 Wiley Periodicals LLC.