The influence of MC1R on dermal morphological features of photo-exposed skin in women revealed by reflectance confocal microscopy and optical coherence tomography

Melasma and reflectance confocal microscopy: from baseline to treatment monitoring

Melasma is a frequent condition worldwide, and it represents one of the most challenging disorders to treat in cosmetic dermatology. One of the critical factors for treatment prognosis is the assessment of the depth and distribution of pigment within the hyperpigmented area. Nowadays, non-invasive skin imaging techniques, such as reflectance confocal microscopy (RCM), have been used to estimate pigment distribution and depth within different skin layers. This article aims to provide a systematic review of RCM applications in melasma, providing terminology and investigating characteristics of melasma at baseline and after medical and laser treatment. Our results support the recognition of two main types of melasma, epidermal and mixed type, thanks to the role of RCM in highlighting the precise pigment depth location in the skin non-invasively. RCM treatment monitoring enables the objectification of pigment variations after treatment and the identification of prognostic factors for different treatment modalities. After the era of the application of RCM as a technique applied strictly to skin cancers, additional cosmetic applications are emerging, such as the application of melasma treatment monitoring.

Melanocortin-1 receptor (MC1R): a review for dermatologists

Melanocortin-1 receptor (MC1R) and its variants have a pivotal role in melanin synthesis. However, MC1R has been associated to non-pigmentary pathways related to DNA-repair activities and inflammation. The aim of this review is to provide an up-to-date overview about the role of MC1R in the skin. Specifically, after summarizing the current knowledge about MC1R structure and polymorphisms, we report data concerning the correlation between MC1R, phenotypic traits, skin aging, other diseases and skin cancers and their risk assessment through genetic testing.

The Keratinocyte in the Picture Cutaneous Melanoma Microenvironment

Melanoma progression is a multistep evolution from a common melanocytic nevus through a radial superficial growth phase, the invasive vertical growth phase finally leading to metastatic dissemination into distant organs. Melanoma aggressiveness largely depends on the propensity to metastasize, which means the capacity to escape from the physiological microenvironment since tissue damage due to primary melanoma lesions is generally modest. Physiologically, epidermal melanocytes are attached to the basement membrane, and their adhesion/migration is under the control of surrounding keratinocytes. Thus, the epidermal compartment represents the first microenvironment responsible for melanoma spread. This complex process involves cell-cell contact and a broad range of secreted bioactive molecules. Invasion, or at the beginning of the microinvasion, implies the breakdown of the dermo-epidermal basement membrane followed by the migration of neoplastic melanocytic cells in the superficial papillary dermis. Correspondingly, several experimental evidences documented the structural and functional rearrangement of the entire tissue surrounding neoplasm that in some way reflects the atypia of tumor cells. Lastly, the microenvironment must support the proliferation and survival of melanocytes outside the normal epidermal-melanin units. This task presumably is mostly delegated to fibroblasts and ultimately to the self-autonomous capacity of melanoma cells. This review will discuss remodeling that occurs in the epidermis during melanoma formation as well as skin changes that occur independently of melanocytic hyperproliferation having possible pro-tumoral features.

Laser Treatment Monitoring with Reflectance Confocal Microscopy

Laser treatments have become popular in Dermatology. In parallel to technologic development enabling the availability of different laser wavelengths, non-invasive skin imaging techniques, such as reflectance confocal microscopy (RCM), have been used to explore morphologic and qualitative skin characteristics. Specifically, RCM can be applied to cosmetically sensitive skin areas such as the face, without the need for skin biopsies. For these reasons, apart from its current use in skin cancer diagnosis, our systematic review reveals how RCM can be employed in the field of laser treatment monitoring, being particularly suitable for the evaluation of variations in epidermis and dermis, and pigmentary and vascular characteristics of the skin. This systematic review article aims to provide an overview on current applications of RCM laser treatment monitoring, while describing RCM features identified for different applications. Studies on human subjects treated with laser treatments, monitored with RCM, were included in the current systematic review. Five groups of treatments were identified and described: skin rejuvenation, scar tissue, pigmentary disorders, vascular disorders and other. Interestingly, RCM can assist treatments with lasers targeting all chromophores in the skin and exploiting laser induced optical breakdown. Treatment monitoring encompasses assessment at baseline and examination of changes after treatment, therefore revealing details in morphologic alterations underlying different skin conditions and mechanisms of actions of laser therapy, as well as objectify results after treatment.

Clinical efficacy and safety of polynucleotides highly purified technology (PN-HPT®) and cross-linked hyaluronic acid for moderate to severe nasolabial folds: A prospective, randomized, exploratory study

INTRODUCTION

The mandibular profile undergoes progressive wasting with aging, and the deepening of nasolabial folds (NLFs) has a leading role. Hyaluronic acid (HA) efficiently controls tissue hydration and permeability to small and large molecules. NLFs are an acknowledged HA target; at the same time, another class of agents, PN-HPT® (Polynucleotides Highly Purified Technology), enjoy growing acknowledgement in aesthetic medicine. This exploratory, prospective study probed the rationale of sequentially associating PN-HPT® as a first priming agent acting in the skin followed by HA dermal filler injections for correcting moderate to severe NLFs.

METHODS

Following strict inclusion and exclusion criteria, the authors screened Caucasian ambulatory women aged 40-65 with moderate to severe NLFs and randomly selected two NLFs for each enrolled woman. Due to the purely explorative nature of the study, the authors initially planned to enroll no >10 women. According to a split-face design, the selected right-side NLFs received 4 ml of PN-HPT® intradermally in the initial priming phase ("NLF Rx group"); the selected left-side NLFs received 4 ml of saline (placebo) ("NLF Lx group"). After 3 and 6 weeks, all patients received 2 ml of subdermal cross-linked HA over both NLF areas (4 ml overall). The total study follow-up was 6 months after the first injection, with objective assessments, based on the qualitative and quantitative Antera 3D® and Vectra H2® skin imaging technologies, after 6 weeks and 3 and 6 months.

RESULTS

Because of the favorable early outcomes, the authors let enrollment progress between January and June 2020 up to a total of 20 women and 40 NLFs. All treated women completed the six-month follow-up without reporting side effects, even clinically minor. The Antera 3D® device demonstrated that wrinkles and skin texture significantly improved in the NLF Rx after 6 weeks (monotherapy phase) and 3 and 6 months (PN-HPT® priming + HA phase) compared with baseline. HA levels, measured with the quantitative Vectra H2® assessment technology in the right NLFs, were significantly higher than contralaterally at both 3 and 6 months.

CONCLUSIONS

Although conceived only as an exploratory investigation, the study confirmed that PN-HPT® monotherapy might be a valuable and effective option to rapidly improve the skin dermis texture and quality in individuals with moderate to severe NLFs. Acting as a priming agent in the skin, PN-HPT® prolong the clinical efficacy of cross-linked HA. Well-designed trials in larger treatment groups will hopefully confirm these early promising results.

Application of a Reflectance Confocal Microscopy Imaging Analysis Score for the Evaluation of Non-Melanogenic Changes in Male Photoaged Skin

The photoaging process is characterized by skin changes due to ultraviolet radiation exposure and is the principal environmental factor affecting skin aging. Reflectance confocal microscopy permits noninvasive skin imaging to understand how the photoaging process may change skin. Since men do not habitually use a sunscreen, the application of skin imaging techniques is important to understand the influence of sunlight on their skin health. The aim of this study was to develop a score based on RCM imaging analyses to evaluate the morphological and structural changes of the photoaged skin according to literature data. The score was applied in order to determine possible correlations between chronological aging and sunscreen use behavior among men. Thus, 40 men aged 18 to 50 years were recruited, images from the frontal region of their skin were obtained and the score was applied. It was observed that habits are more important than age for the skin photoaging process. Men with photoprotection habits showed overall better skin morphological and structural characteristics regardless of age, demonstrating that sun protection behavior is a major key factor in the understanding of photoaging, so that men should be encouraged to start the use of cosmetic products and to perform selfcare.

Focus on the Contribution of Oxidative Stress in Skin Aging

Skin aging is one of the most evident signs of human aging. Modification of the skin during the life span is characterized by fine lines and wrinkling, loss of elasticity and volume, laxity, rough-textured appearance, and pallor. In contrast, photoaged skin is associated with uneven pigmentation (age spot) and is markedly wrinkled. At the cellular and molecular level, it consists of multiple interconnected processes based on biochemical reactions, genetic programs, and occurrence of external stimulation. The principal cellular perturbation in the skin driving senescence is the alteration of oxidative balance. In chronological aging, reactive oxygen species (ROS) are produced mainly through cellular oxidative metabolism during adenosine triphosphate (ATP) generation from glucose and mitochondrial dysfunction, whereas in extrinsic aging, loss of redox equilibrium is caused by environmental factors, such as ultraviolet radiation, pollution, cigarette smoking, and inadequate nutrition. During the aging process, oxidative stress is attributed to both augmented ROS production and reduced levels of enzymatic and non-enzymatic protectors. Apart from the evident appearance of structural change, throughout aging, the skin gradually loses its natural functional characteristics and regenerative potential. With aging, the skin immune system also undergoes functional senescence manifested as a reduced ability to counteract infections and augmented frequency of autoimmune and neoplastic diseases. This review proposes an update on the role of oxidative stress in the appearance of the clinical manifestation of skin aging, as well as of the molecular mechanisms that underline this natural phenomenon sometimes accelerated by external factors.

Dermoscopy, confocal microscopy and optical coherence tomography features of main inflammatory and autoimmune skin diseases: A systematic review

BACKGROUND/OBJECTIVES

Non-invasive skin imaging features of main skin inflammatory and autoimmune diseases have been reported, although a comprehensive review of their correlation with histopathologic features is currently lacking. Therefore, the aim of this paper was to review the correlation of dermoscopic, reflectance confocal microscopy (RCM) and optical coherence tomography (OCT) criteria of main inflammatory and autoimmune skin diseases with their corresponding histopathologic criteria correlation.

METHODS

Studies on human subjects affected by main inflammatory and autoimmune diseases, defining the correlation of dermoscopic, RCM or OCT with histopathologic criteria, were included in the review. Five groups of diseases were identified and described: psoriasiform, spongiotic and interface dermatitis, bullous diseases and scleroderma.

RESULTS

Psoriasiform dermatitis was typified by white scales, corresponding to hyperkeratosis, and vessels, observed with RCM and OCT. Spongiosis, corresponding to dark areas within the epidermis with RCM and OCT, was the main feature of spongiotic dermatitis. Interface dermatitis was characterised by dermoepidermal junction obscuration. Blisters, typical of bullous diseases, were visualised as dark areas with RCM and OCT while scleroderma lesions were characterised by dermoscopic fibrotic beams, related to dermal thickness variations, with specific OCT and histopathologic correlations.

CONCLUSIONS

Although the role of RCM and OCT has yet to be defined in clinical practice, non-invasive skin imaging shows promising results on inflammatory and autoimmune skin diseases, due to the correlation with histopathologic features.

MC1R Functions, Expression, and Implications for Targeted Therapy

The G protein-coupled MC1R is expressed in melanocytes and has a pivotal role in human skin pigmentation, with reduced function in human genetic variants exhibiting a red hair phenotype and increased melanoma predisposition. Beyond its role in pigmentation, MC1R is increasingly recognized as promoting UV-induced DNA damage repair. Consequently, there is mounting interest in targeting MC1R for therapeutic benefit. However, whether MC1R expression is restricted to melanocytes or is more widely expressed remains a matter of debate. In this paper, we review MC1R function and highlight that unbiased analysis suggests that its expression is restricted to melanocytes, granulocytes, and the brain.

Behind the Scene: Exploiting MC1R in Skin Cancer Risk and Prevention

Melanoma and non-melanoma skin cancers (NMSCs) are the most frequent cancers of the skin in white populations. An increased risk in the development of skin cancers has been associated with the combination of several environmental factors (i.e., ultraviolet exposure) and genetic background, including melanocortin-1 receptor (MC1R) status. In the last few years, advances in the diagnosis of skin cancers provided a great impact on clinical practice. Despite these advances, NMSCs are still the most common malignancy in humans and melanoma still shows a rising incidence and a poor prognosis when diagnosed at an advanced stage. Efforts are required to underlie the genetic and clinical heterogeneity of melanoma and NMSCs, leading to an optimization of the management of affected patients. The clinical implications of the impact of germline MC1R variants in melanoma and NMSCs' risk, together with the additional risk conferred by somatic mutations in other peculiar genes, as well as the role of MC1R screening in skin cancers' prevention will be addressed in the current review.

Reflectance Confocal Microscopy of Aging Skin and Skin Cancer

Skin aging is a complex process that causes morphologic variations. Some of these variations have been hypothesized to be involved in skin cancer development. This paper reviews current knowledge of the features of aged skin as seen with reflectance confocal microscopy (RCM). Basic principles of the technique are described, and the RCM features of healthy skin and skin cancer are briefly discussed. Moreover, the RCM features at different layers of young and elderly skin are described, as are the variations that occur with passing years and in relation to sun exposure that contribute to photoaging and the development of skin cancer. RCM enables the noninvasive evaluation, at quasi-histologic resolution, of aging-related skin changes, some of which are shared with skin cancer; this ability helps avoid skin biopsy. Further research is needed to understand the relation between skin aging and skin cancer development.

Fractional 1064 nm picosecond laser and skin photoaging: in vivo evaluation of treatment effects with reflectance confocal microscopy

Few studies showed the role of picosecond laser (PLS) in the treatment of skin photoaging signs. However, no studies have explored the microscopic effects of PSL in photoaging. The aim of this study is to preliminarily identify clinical variations induced by a 1,064 nm Nd:YAG PSL on the décolleté area, then to apply the treatment protocol to treat facial photoaging and estimate the clinical and microscopic outcomes. A total of 10 consecutive patients with cutaneous photoaging were enrolled. Patients were treated 3 times at monthly intervals with the fractionated 1,064 nm Nd:YAG PSL. In a preliminary phase, PSL treatment was performed on the décolleté to establish its efficacy and safety. Then, the same treatment protocol was applied to all the face and clinical and reflectance confocal microscopy (RCM) were analyzed, comparing baseline (T0) pictures and 4 months after the treatment (T1) ones. On the face, a reduction of dyschromia and wrinkles was observed at T1. Furthermore, the underlying RCM variations were revealed at different skin levels. Our results show the clinical and microscopic effectiveness and safety of the 1,064-nm Nd:YAG PSL in the treatment of skin photoaging signs.

A plea for standardization of confocal microscopy and optical coherence tomography parameters to evaluate physiological and para-physiological skin conditions in cosmetic science

Non-invasive reflectance confocal microscopy (RCM) and optical coherence tomography (OCT) have been extended to the dermo-cosmetic field, for skin pathophysiology understanding and therapeutics monitoring. However, standardized methodology and parameters to interpret structures and changes in these settings are still lacking. Present study aimed to propose a validated standard methodology and a list of defined parameters for objective non-pathological skin assessments in the cosmetically sensitive cheekbone area of the face. OCT and RCM quantitative, semi-quantitative and qualitative features were considered for assessments. Validation process included 50 sets of images divided into two age groups. Inter-rater reliability was explored to assess the influence of the proposed methodology. Quantitative OCT parameters of "epidermal thickness," "density and attenuation coefficients" and "vascular density" were considered and calculated. Severity scales were developed for semi-quantitative OCT features of "disruption of collagen" and "vascular asset," while extent scales were produced for semi-quantitative RCM "irregular honeycomb," "mottled pigmentation" and "polycyclic papillary contours." Qualitative assessment was obtained for RCM type of collagen, and comparison between age groups was performed for all features considered. Severity visual scales assistance proved excellent inter-rater agreement across all semi-quantitative and qualitative domains. The assistance of shareable software systems allows for objective OCT quantitative parameters measurement. The use of standard reference scales, within a defined assessment methodology, offers high inter-rater reliability and thus reproducibility for semi-quantitative and qualitative OCT and RCM parameters. Taken together, our results may represent a starting point for a standardized application of RCM and OCT in dermo-cosmetic research and practice.