Photobiomodulation CME Part I: Overview and Mechanism of Action.

Photobiomodulation (PBM), previously known as low-level laser light therapy, represents a non-invasive form of phototherapy that utilizes wavelengths in the red light (RL, 620-700 nm) portion of the visible light (VL, 400-700 nm) spectrum and the near-infrared (NIR, 700-1440 nm) spectrum. PBM is a promising and increasingly used therapy for the treatment of various dermatologic and non-dermatologic conditions. Photons from RL and NIR are absorbed by endogenous photoreceptors including mitochondrial cytochrome C oxidase (COX). Activation of COX leads to the following changes: modulation of mitochondrial adenosine triphosphate (ATP), generation of reactive oxygen species (ROS), and alterations in intracellular calcium levels. The associated modulation of ATP, ROS and calcium levels promotes the activation of various signaling pathways (e.g., insulin-like growth factors, phosphoinositide 3-kinase pathways), which contribute to downstream effects on cellular proliferation, migration and differentiation. Effective PBM therapy is dependent on treatment parameters (e.g., fluence, treatment duration and output power). PBM is generally well-tolerated and safe with erythema being the most common and self-limiting adverse cutaneous effect.

Photobiomodulation CME part II: Clinical applications in dermatology.

Photobiomodulation (PBM) is an emerging treatment modality in dermatology with increasing office and home-based use. PBM is the use of various light sources in the red light (620-700 nm) and near-infrared (700-1440 nm) spectrum as a form of light therapy. PBM is often administered through low-level lasers or light-emitting diodes. Studies show that PBM can be used effectively to treat conditions secondary to cancer therapies, alopecia, ulcers, herpes simplex virus, acne, skin rejuvenation, wounds, and scars. PBM offers patients many benefits compared to other treatments. It is noninvasive, cost-effective, convenient for patients, and offers a favorable safety profile. PBM can be used as an alternative or adjuvant to other treatment modalities including pharmacotherapy. It is important for dermatologists to gain a better clinical understanding of PBM for in-office administration and to counsel patients on proper application for home-use devices to best manage safety and expectations as this technology develops. PBM wavelengths can induce varied biological effects in diverse skin types, races, and ethnicities; therefore, it is also important for dermatologists to properly counsel their skin of color patients who undergo PBM treatments. Future clinical trials are necessary to produce standardized recommendations across conditions and skin types.

The potential effect of Polypodium leucotomos extract on ultraviolet- and visible light-induced photoaging.

Photoaging induced by both ultraviolet and visible light has been shown to lead to increased inflammation and dysregulation of the extracellular matrix. Standardized extract of the Polypodium leucotomos fern, PLE, possesses anti-inflammatory and antioxidant properties, and has been shown to potentially mitigate photoaging through various mechanisms. This comprehensive review presents the data available on the effects of P. leucotomos extract on UV and VL-induced photoaging in vitro as well as in vivo in murine and human models.

Visible light. Part I: Properties and cutaneous effects of visible light.

Approximately 50% of the sunlight reaching the Earth's surface is visible light (400-700 nm). Other sources of visible light include lasers, light-emitting diodes, and flash lamps. Photons from visible light are absorbed by photoreceptive chromophores (e.g., melanin, heme, and opsins), altering skin function by activating and imparting energy to chromophores. Additionally, visible light can penetrate the full thickness of the skin and induce pigmentation and erythema. Clinically, lasers and light devices are used to treat skin conditions by utilizing specific wavelengths and treatment parameters. Red and blue light from light-emitting diodes and intense pulsed light have been studied as antimicrobial and anti-inflammatory treatments for acne. Pulsed dye lasers are used to treat vascular lesions in adults and infants. Further research is necessary to determine the functional significance of visible light on skin health without confounding the influence of ultraviolet and infrared wavelengths.

Oral Polypodium Leucotomos Extract and Its Impact on Visible Light-Induced Pigmentation in Human Subjects

BACKGROUND: Visible light (VL) has multiple effects on the skin that currently available sunscreens do not protect against. Polypodium leucotomos extract (PLE) has properties that may offer protection against VL. OBJECTIVES: To determine the effectiveness of PLE in preventing VL-induced effects. METHODS: Twenty-two subjects with Fitzpatrick skin phototype IV-VI were enrolled. On day 0, subjects were irradiated with VL. Clinical Investigator's Global Assessment (IGA) scoring and spectroscopic evaluations were performed immediately, 24 hours, and 7 days after irradiation. Subjects then received a 28-day supply of PLE (480 mg daily). Irradiation and evaluation were repeated. Three 4-mm punch biopsies were obtained for immunohistochemistry analysis: one from normal unirradiated skin and the other two twenty-four hours after irradiation, pre- and post-PLE, from sites irradiated with highest dose of VL. RESULTS: All subjects had immediate pigment darkening, persistent pigment darkening, and delayed tanning both pre- and post-PLE. For the highest VL dose (480 J/cm²) spectroscopic assessments demonstrated a statistically significant decrease in persistent pigment darkening and delayed tanning post-PLE. In addition, there was a significant decrease in cyclooxygenase-2, and a trend towards decreases in the markers for cellular damage post-PLE. While there was a trend towards lower IGA scores post-PLE, statistical significance was not reached possibly due to lack of sensitivity of the visual IGA scoring system in detecting small changes. CONCLUSIONS: Spectroscopic data and immunohistochemistry indicate an effect of PLE on visible light induced effects. As such, PLE may be used as an adjuvant to traditional means of photoprotection to protect against the effects of VL. Clinical trial registration number: NCT02904798. J Drugs Dermatol. 2019;18(12):1198-1203.

The potential role of antioxidants in mitigating skin hyperpigmentation resulting from ultraviolet and visible light-induced oxidative stress.

Oxidative stress is an integral element that influences a variety of biochemical reactions throughout the body and is known to play a notable role in melanogenesis. Exogenous triggers of oxidative stress, such as ultraviolet radiation (UVR) and visible light (VL), lead to pigment formation through somewhat different pathways, but both share a common endpoint-the potential to generate cosmetically undesirable hyperpigmentation. Though organic and inorganic sunscreens are available to protect against the UVR portion of the electromagnetic spectrum, coverage is lacking to protect against the VL spectrum. In this manuscript, we review the phases of tanning, pathways of melanogenesis triggered by UVR and VL, and the associated impact of oxidative stress. We also discuss the known intrinsic mechanisms and paracrine regulation of melanocytes that influence their response to UVR. Understanding these mechanisms and their role in UVR-induced hyperpigmentation should potentially lead to identification of useful targets that can be coupled with antioxidant therapy to alleviate this effect.

The impact of oral Polypodium leucotomos extract on ultraviolet B response: A human clinical study.

BACKGROUND: There is a rationale for adding systemic photoprotective agents to the current photoprotection regimen. OBJECTIVE: This study was designed to objectively evaluate the molecular and photobiologic effects of oral administration of Polypodium leucotomos extract (PLE). METHODS: In all, 22 subjects with Fitzpatrick skin phototype I to III were enrolled. On day 1, subjects were irradiated with visible light, ultraviolet (UV) A1, and UVB (using 308-nm excimer laser). Evaluation was done immediately and 24 hours after irradiation. On days 3 and 4, irradiation and evaluation process was repeated after ingestion of PLE. RESULTS: Clinical assessments and colorimetry data showed a decrease in UVB-induced changes in 17 of 22 subjects post-PLE administration; histology findings demonstrated such a decrease in all 22 subjects. LIMITATIONS: Only 2 doses of PLE were given. Furthermore, subjects with skin phototypes I to III only were studied. CONCLUSION: The results suggest that PLE can potentially be used as an adjunctive agent to lessen the negative photobiologic effects of UVB.