Molecular and Biochemical Basis of Minocycline-Induced Hyperpigmentation-The Study on Normal Human Melanocytes Exposed to UVA and UVB Radiation

Phase 2 Trial Evaluating Minocycline for Geographic Atrophy in Age-Related Macular Degeneration: A Nonrandomized Controlled Trial

Importance

Existing therapies to slow geographic atrophy (GA) enlargement in age-related macular degeneration (AMD) have relatively modest anatomic efficacy, require intravitreal administration, and increase the risk of neovascular AMD. Additional therapeutic approaches are desirable.

Objective

To evaluate the safety and possible anatomic efficacy of oral minocycline, a microglial inhibitor, for the treatment of GA in AMD.

Design, Setting, and Participants

This was a phase 2, prospective, single-arm, 45-month, nonrandomized controlled trial conducted from December 2016 to April 2023. Patients with GA from AMD in 1 or both eyes were recruited from the National Institutes of Health (Bethesda, Maryland) and Bristol Eye Hospital (Bristol, UK). Study data were analyzed from September 2022 to May 2023.

Intervention

After a 9-month run-in phase, participants began oral minocycline, 100 mg, twice daily for 3 years.

Main Outcomes and Measures

The primary outcome measure was the difference in rate of change of square root GA area on fundus autofluorescence between the 24-month treatment phase and 9-month run-in phase.

Results

Of the 37 participants enrolled (mean [SD] age, 74.3 [7.6] years; 21 female [57%]), 36 initiated the treatment phase. Of these participants, 21 (58%) completed at least 33 months, whereas 15 discontinued treatment (8 by request, 6 for adverse events/illness, and 1 death). Mean (SE) square root GA enlargement rate in study eyes was 0.31 (0.03) mm per year during the run-in phase and 0.28 (0.02) mm per year during the treatment phase. The primary outcome measure of mean (SE) difference in enlargement rates between the 2 phases was -0.03 (0.03) mm per year (P = .39). Similarly, secondary outcome measures of GA enlargement rate showed no differences between the 2 phases. The secondary outcome measures of mean difference in rate of change between 2 phases were 0.2 letter score per month (95% CI, -0.4 to 0.9; P = .44) for visual acuity and 0.7 μm per month (-0.4 to 1.8; P = .20) for subfoveal retinal thickness. Of the 129 treatment-emergent adverse events among 32 participants, 49 (38%) were related to minocycline (with no severe or ocular events), including elevated thyrotropin level (15 participants) and skin hyperpigmentation/discoloration (8 participants).

Conclusions and Relevance

In this phase 2 nonrandomized controlled trial, oral minocycline was not associated with a decrease in GA enlargement over 24 months, compared with the run-in phase. This observation was consistent across primary and secondary outcome measures. Oral minocycline at this dose is likely not associated with slower rate of enlargement of GA in AMD.

The phenomenon of phototoxicity and long-term risks of commonly prescribed and structurally diverse drugs

Photosensitivity to structurally diverse drugs is a common but under-reported adverse cutaneous reaction and can be classified as phototoxic or photoallergic. Phototoxic reactions occur when the skin is exposed to sunlight after administering topical or systemic medications that exhibit photosensitizing activity. These reactions depend on the dose of medication, degree of exposure to ultraviolet light, type of ultraviolet light, and sufficient skin distribution volume. Accurate prediction of the incidence and phototoxic response severity is challenging due to a paucity of literature, suggesting that phototoxicity may be more frequent than reported. This paper reports an extensive literature review on phototoxic drugs; the review employed pre-determined search criteria that included meta-analyses, systematic reviews, literature reviews, and case reports freely available in full text. Additional reports were identified from reference sections that contributed to the understanding of phototoxicity. The following drugs and/or drug classes are discussed: amiodarone, voriconazole, chlorpromazine, doxycycline, fluoroquinolones, hydrochlorothiazide, nonsteroidal anti-inflammatory drugs, and vemurafenib. In reviewing phototoxic skin reactions, this review highlights drug molecular structures, their reactive pathways, and, as there is a growing association between photosensitizing drugs and the increasing incidence of skin cancer, the consequential long-term implications of photocarcinogenesis.

Fermented Aronia melanocarpa Inhibits Melanogenesis through Dual Mechanisms of the PI3K/AKT/GSK-3β and PKA/CREB Pathways

UV light causes excessive oxidative stress and abnormal melanin synthesis, which results in skin hyperpigmentation disorders such as freckles, sunspots, and age spots. Much research has been carried out to discover natural plants for ameliorating these disorders. Aronia melanocarpa contains various polyphenolic compounds with antioxidative activities, but its effects on melanogenesis have not been fully elucidated. In this study, we investigated the inhibitory effect of fermented Aronia melanocarpa (FA) fermented with Monascus purpureus on melanogenesis and its underlying mechanism in the B16F10 melanoma cell line. Our results indicate that FA inhibited tyrosinase activity and melanogenesis in alpha-melanocyte-stimulating hormone (α-MSH)-induced B16F10 cells. FA significantly downregulated the PKA/CREB pathway, resulting in decreased protein levels of tyrosinase, TRP-1, and MITF. FA also inhibited the transcription of MITF by increasing the phosphorylation levels of both GSK3β and AKT. Interestingly, we demonstrated that these results were owing to the significant increase in gallic acid, a phenolic compound of Aronia melanocarpa produced after the fermentation of Monascus purpureus. Taken together, our research suggests that Aronia melanocarpa fermented with Monascus purpureus acts as a melanin inhibitor and can be used as a potential cosmetic or therapeutic for improving hyperpigmentation disorders.

Comparative study of doxycycline, sancycline, and 4-dedimethylamino sancycline (CMT-3) on epidermal melanogenesis

Melanogenesis is regulated by melanocytes, which synthesize the pigment melanin inside melanosomes; these melanosomes are exported through dendritic extensions to adjacent keratinocytes and result in skin coloration. Chemically modified tetracyclines (CMTs) are nonantimicrobial tetracyclines that retain the capacity to inhibit matrix metalloproteinases (MMPs) and have shown several biological benefits; in particular, CMT-3 [(4-dedimethylamino sancycline (SAN)] has emerged as a candidate for therapeutic benefits in our previous studies. However, to date, studies of the effects of CMT-3 or SAN on melanogenesis are lacking. We have previously reported the anti-melanogenic activity of CMT-308 (the 9-amino derivative of CMT-3). Herein, we have compared the three tetracycline analogs, doxycycline (DOX), SAN, and CMT-3, for their effects on melanogenesis using B16F10 mouse melanoma cells and have validated results in primary human melanocytes (HEMn-DP). DOX did not show any significant effects on intracellular melanin or melanosome export in DP cells while SAN was cytotoxic at high doses but without effects on melanogenesis at lower doses. However, CMT-3 showed a robust suppression of dendricity parameters (dendrite number, dendrite length, and proportion of dendritic cells) in DP cells which was associated, at least in part, with a significant reduction of intracellular tyrosinase activity. In spite of its inhibition of tyrosinase activity, CMT-3 had no significant effects on intracellular melanin levels, suggesting that it selectively targets melanosome export. Our results demonstrate a unique structure-activity relationship (SAR) for the effects of these compounds on melanogenesis and support the conclusion that removal of the 4-dimethylamino moiety confers the selective capacity to suppress melanosome export. Collectively, these results indicate that CMT-3 might be a candidate for diminishing hyperpigmentation skin disorders.

A Post Hoc Analysis of Efficacy Data on Sarecycline in Hispanics with Acne from Two Phase 3, Multicenter, Randomized, Double-Blind, Placebo-Controlled Clinical Trials

Sarecycline is a novel, narrow-spectrum, third generation tetracycline class antibiotic approved by the Food and Drug Administration (FDA) for the treatment of moderate-to-severe acne in patients ages nine and older. Recently, focus has increased on whether treatment responses differ in acne in skin of color. Here, we aimed to analyze the efficacy of using sarecycline in Hispanics. We report pooled post hoc analysis of efficacy data on sarecycline in Hispanics with acne from two phase 3, multicenter, randomized, double-blind, placebo-controlled clinical trials, SC1401 and SC1402. Of 2002 patients in the pooled trials with moderate-to-severe acne, 26.9% were Hispanic. Facial inflammatory lesion counts decreased as early as week 3 by 26% (p = 0.0279), with continued reduction by 41% by week 6 (p = 0.0003), by 51% by week 9 (p < 0.0001), and by 55% by week 12 (p < 0.0001). Acne is the most common skin condition diagnosed in Hispanics, and this study illustrates a statistically significant reduction in acne in Hispanic patients with moderate-to-severe acne treated with oral sarecycline. Therefore, oral sarecycline shows promising results as a safe and effective treatment for acne in Hispanics.

Inflammatory response: The target for treating hyperpigmentation during the repair of a burn wound

Hyperpigmentation is a common complication in patients with burn injuries during wound healing; however, the mechanisms underlying its occurrence and development remain unclear. Recently, postinflammatory hyperpigmentation (PIH) was found to result from overproduction of melanin. Local or systemic inflammatory responses are often observed in patients who develop hyperpigmentation. However, we lack studies on the relationship between PIH and burn injury. Therefore, we comprehensively reviewed the existing literature on the melanogenesis of the skin, inflammatory mechanisms in pigmentation, and local or systemic alteration in inflammatory cytokines in patients suffering from burn trauma to elucidate the relationship between PIH and burn injury. We believe that this review will guide further research on regulating melanin production in the burn management process.

Effects of a grapeseed oil (Vitis vinifera L.) loaded dermocosmetic nanoemulgel on biophysical parameters of facial skin: A split-face, blinded, placebo-controlled study

BACKGROUND

Worldwide, grapes (Vitis vinifera L.; family: Vitaceae) are one of the most important fruits. Grapeseed oil is rich in bioactive constituents that could be beneficial to the health and aesthetic features of human skin.

OBJECTIVE

This study was conducted to evaluate the effects of a novel grapeseed oil-loaded dermocosmetic nanoemulgel on biophysical parameters of facial skin.

METHODS

This was a split-face, blinded, placebo-controlled study. A novel grapeseed oil-loaded dermocosmetic nanoemulgel was developed, and its effects on the biophysical parameters of the facial skin were evaluated and compared to those of a placebo formulation on the cheeks of 15 healthy volunteers. Melanin, erythema, sebum production, fine and large facial pores, moisture, and elasticity levels were measured using Mexameter®, Corneometer®, Sebumeter®, Cutometer®, and VisioFace®. Measurements were made on weekly basis for 12 weeks.

RESULTS

Compared to the placebo, the novel grapeseed oil-loaded dermocosmetic nanoemulgel received significantly higher sensory scores with regard to appearance, color, odor, consistency, adhesion, sensation, cohesiveness, and spreadability (p-value < 0.05). Additionally, the novel nanoemulgel continuously and significantly reduced skin melanin, erythema, sebum production, and fine and large pores (p-value < 0.05). On the contrary, the novel nanoemulgel continuously and significantly increased skin moisture contents and elasticity (p-value < 0.05).

CONCLUSION

The novel grapeseed oil-loaded dermocosmetic nanoemulgel had attractive cosmetic attributes that could be useful for improving imperfections of the human skin. Future studies are still needed to test and evaluate the benefits of this novel grapeseed oil-loaded dermocosmetic nanoemulgel in disease conditions.

A pilot study of combined oral minocycline and narrowband UVB phototherapy in vitiligo: A randomized, double-blind, placebo-controlled trial

Narrowband ultraviolet B (NBUVB) phototherapy is an effective therapeutic option for generalized vitiligo. Previous reports showed the potential benefit of minocycline to stop disease progression in vitiligo. Meanwhile, minocycline has antioxidative, anti-inflammatory, and immunomodulating properties. There is no clinical study combining oral minocycline and NBUVB for treating generalized vitiligo. This study aims to compare the efficacy and safety of the combination treatment of NBUVB plus oral minocycline with NBUVB alone in generalized vitiligo. A randomized, double-blinded, placebo-controlled pilot study was conducted. Patients were randomly treated with either combined oral minocycline 100 mg per day plus NBUVB phototherapy or placebo plus NBUVB. All patients recieved NBUVB two times per week, for 12 weeks. The outcomes were assessed using Vitiligo Area Scoring Index score (VASI) percent change, quartile grading scale (QGS) of repigmentation, and Vitiligo Disease Activity Index (VIDA) score. Fourteen generalized vitiligo patients were included, and seven cases were assigned in each group. At week 12, the mean VASI score was decreased by 28.87% (24.15) in the minocycline group compared to 27.26% (7.98) in placebo group (p = 0.886). No significant difference was observed between both treatment modalities in QGS of repigmentation and mean VIDA score change. Two of the seven patients (29%) receiving minocycline developed hyperpigmentation, dark-brown and muddy brown discoloration, which was only confined to some vitiliginous patches. In conclusion, combination therapy with oral minocycline does not enhance the efficacy of NBUVB in generalized vitiligo. Due to the high incidence of drug-induced skin hyperpigmentation, minocycline plus NBUVB should be avoided.

The Anticancer Potential of Doxycycline and Minocycline-A Comparative Study on Amelanotic Melanoma Cell Lines

Malignant melanoma is still a serious medical problem. Relatively high mortality, a still-growing number of newly diagnosed cases, and insufficiently effective methods of therapy necessitate melanoma research. Tetracyclines are compounds with pleiotropic pharmacological properties. Previously published studies on melanotic melanoma cells ascertained that minocycline and doxycycline exerted an anti-melanoma effect. The purpose of the study was to assess the anti-melanoma potential and mechanisms of action of minocycline and doxycycline using A375 and C32 human amelanotic melanoma cell lines. The obtained results indicate that the tested drugs inhibited proliferation, decreased cell viability, and induced apoptosis in amelanotic melanoma cells. The treatment caused changes in the cell cycle profile and decreased the intracellular level of reduced thiols and mitochondrial membrane potential. The exposure of A375 and C32 cells to minocycline and doxycycline triggered the release of cytochrome c and activated initiator and effector caspases. The anti-melanoma effect of analyzed drugs appeared to be related to the up-regulation of ERK1/2 and MITF. Moreover, it was noticed that minocycline and doxycycline increased the level of LC3A/B, an autophagy marker, in A375 cells. In summary, the study showed the pleiotropic anti-cancer action of minocycline and doxycycline against amelanotic melanoma cells. Considering all results, it could be concluded that doxycycline was a more potent drug than minocycline.

Drug-Induced Photosensitivity-From Light and Chemistry to Biological Reactions and Clinical Symptoms

Photosensitivity is one of the most common cutaneous adverse drug reactions. There are two types of drug-induced photosensitivity: photoallergy and phototoxicity. Currently, the number of photosensitization cases is constantly increasing due to excessive exposure to sunlight, the aesthetic value of a tan, and the increasing number of photosensitizing substances in food, dietary supplements, and pharmaceutical and cosmetic products. The risk of photosensitivity reactions relates to several hundred externally and systemically administered drugs, including nonsteroidal anti-inflammatory, cardiovascular, psychotropic, antimicrobial, antihyperlipidemic, and antineoplastic drugs. Photosensitivity reactions often lead to hospitalization, additional treatment, medical management, decrease in patient's comfort, and the limitations of drug usage. Mechanisms of drug-induced photosensitivity are complex and are observed at a cellular, molecular, and biochemical level. Photoexcitation and photoconversion of drugs trigger multidirectional biological reactions, including oxidative stress, inflammation, and changes in melanin synthesis. These effects contribute to the appearance of the following symptoms: erythema, swelling, blisters, exudation, peeling, burning, itching, and hyperpigmentation of the skin. This article reviews in detail the chemical and biological basis of drug-induced photosensitivity. The following factors are considered: the chemical properties, the influence of individual ranges of sunlight, the presence of melanin biopolymers, and the defense mechanisms of particular types of tested cells.