A new optical intra-tissue fiber irradiation ALA-PDT in the treatment of acne vulgaris in rabbit model: improved safety and tolerability

A preliminary study on the evaluation of photodynamic diagnosis for acne inflammatory skin lesions

OBJECTIVE

This study aimed to observe the fluorescence characteristics of acne inflammatory skin lesions in 5-aminolevulinic acid-based photodynamic diagnosis (ALA-PDD), and discuss the viability of using ALA-PDD to evaluate acne inflammatory skin lesions and explore the advantages of predicting subclinical skin lesions.

METHODS

The OBSERV facial skin detector collected photographs of 20 patients before and after optical intra-tissue fiber irradiation photodynamic therapy (OFI-ALA-PDT) in both ALA-PDD and white light patterns. The patients were treated once a week for four consecutive weeks in order to analyze the correlation between the two patterns in recognizing inflammatory skin lesions.

RESULTS

Before and after treatment, there was no significant difference between the two patterns for recognizing acne inflammatory skin lesions (p > 0.05). Both patterns demonstrated a strong correlation (r > 0.90) for the recognition of various types of inflammatory skin lesions at different treatment stages.

CONCLUSION

ALA-PDD is a feasible method for evaluating acne inflammatory lesions, guiding treatment and judging efficacy. It has advantages in predicting subclinical skin lesions and deserves further study.

Optimal blue light irradiation conditions for the treatment of acne vulgaris in a mouse model

BACKGROUND

Although blue light is one of the therapeutic approaches used to treat acne vulgaris (AV), there is no consensus on its effectiveness. As a result, it is not recommended in the major acne vulgaris treatment guidelines.

OBJECTIVE

The goal of this study was to look into the mechanism, safety, and efficacy of blue light therapy. We achieved this by examining the pathological response, inflammation, and depth of light penetration in a mouse model of cystic AV.

METHODS

The aims of the study were addressed by exposing the mice to light with a wavelength of 415 nm under four different irradiation conditions. The exposure was done for five consecutive days followed by a no irradiation period of 72 h.

RESULTS

Blue light treatment was most effective when irradiation was performed at 100 mW/cm² for 20 min for five consecutive days. Inflammatory responses emerged 72 h after the final irradiation dose was administered. These responses were not associated with apoptosis as cleaved caspase-3 staining revealed no significant increases in apoptosis in the skin under any of the tested conditions. Blue light reached the superficial layer of the acne cyst at 5% of the total irradiation power and was attenuated by half for every 50 μm of progress through the cyst.

CONCLUSION

In conclusion, blue light could control severe dermatologic inflammatory responses; therefore, it can be used to irradiate AV with high inflammation levels on a daily basis until improvement is observed. In addition, porphyrin, a metabolite of Cutibacterium acnes, and reactive oxygen species generated by the surrounding skin tissue may have essential roles in AV treatment.

Effect of minocycline hydrochloride combined with photodynamic therapy on skin barrier function of patients with acne

OBJECTIVE

The aim of this study is to evaluate the effects of minocycline hydrochloride combined with photodynamic therapy on skin barrier function of patients with acne.

METHODS

Eighty-eight acne patients admitted to our hospital were randomized into research group (n=44, photodynamic therapy on the basis of minocycline hydrochloride) and control group (n=44, minocycline hydrochloride). The clinical efficacy, skin barrier function indexes (transdermal water loss (TEWL), stratum corneum water content, pH value), scores of GAGS and Acne-QOL, cosmetic satisfaction and adverse reaction rates of the two groups were compared.

RESULTS

The total effective rate of research group was higher than that of control group (P<0.05). After treatment, TEWL, cuticle water content and pH value were improved compared with those before treatment, and the research group was superior to the control group (all P<0.05). After treatment, the GAGS scores of both groups were lower than those before treatment, and the research group was lower than that of the control group (all P<0.05). The cosmetic satisfaction in the research group was higher than that in the control group (P<0.05). There was no marked difference in the incidence of adverse reactions between the two groups (P>0.05). After treatment, the quality of life scores of patients were higher than before treatment, and the research group was higher than that of the control group (all P<0.05).

CONCLUSION

Minocycline hydrochloride combined with photodynamic therapy can effectively improve the skin barrier function of patients, relieve clinical symptoms, and enhance the overall efficacy and quality of life. It is also safe and patients are highly satisfied with the cosmetic effect.

Effects of metformin on experimentally induced acne on rabbit ear

Evidence for the effectiveness of metformin in the treatment of acne is limited. To assess its efficacy, comedones were experimentally induced in young New Zealand rabbit ear using Isopropyl Myristate (IM) followed by metformin treatment (30 mg/kg bodyweight) for 60 days with continued IM application. In another group, to check whether metformin pre-treatment affects subsequent comedone development by IM, metformin was given for 14 days and then withdrawn (14 days) followed by comedone development with IM and metformin treatment. At different time points, dermatoscopic images of rabbit ear were taken for clinical assessment. Blood and biopsy samples were taken for hormonal assessment, histological examination and gene expression. Histologically confirmed acne model was developed in rabbit ear. Follicular size increased significantly (p = 0.0004 in both groups) upon IM application. Metformin significantly decreased comedones size as observed in dermatoscopic (p = 0.0003 in group I, p = 0.0190 in group II) and histological examination (p = 0.0313 in group I and II). However, size of comedones developed after metformin pretreatment was significantly (p < 0.0001) smaller. The lipid content of sebaceous glands decreased with metformin without any significant changes in the assessed hormones and genetic expression. Overall, metformin was found to be clinically effective in experimentally induced acne and can be used in humans.

Development and Evaluation of Topical Delivery of Microemulsions Containing Adapalene (MEs-Ap) for Acne

The main objective of the study was to prepare the microemulsions containing adapalene (MEs-Ap) to enhance epidermal penetration, dermal retention, and local bioavailability compared with the commercial preparation. The optimal formulations were selected by solubility experiments, pseudo-ternary phase diagram, and percutaneous permeation experiments and the physiochemical properties were also investigated. Then, the study of permeability, retention, safety, pharmacodynamics, and pharmacokinetics in the skin for MEs-Ap compared with the commercial preparation were researched. The optimized formulation was developed as follows: the ratio of AP, isopropyl myristate, polyoxyethylene hydrogenated castor oil, ethanol, and water was 0.01:1:1.25:3.75:4 (w/w). The globule size and average viscosity of the optimized MEs-Ap were 99.34 nm and 1.7 mPa·s, respectively, which was oil-in-water microemulsion without serious irritation or allergy for skin. The J_s, Q_n, and Q_retention of MEs-Ap (0.81 ± 0.19 μg/cm²/h, 24.73 ± 4.24 μg/cm², 2.08 ± 0.18 μg/cm²) were apparently higher than Differin® (0.022 ± 0.009 μg/cm²/h, 0.536 ± 0.103 μg/cm², and 0.523 ± 0.130 μg/cm²) respectively. The local bioavailability study showed that the AUC_{0 → 36h} of the MEs-Ap in the dermal (19.6 ± 1.22 μg/cm²) was significantly improved comparing to Differin® (13.9 ± 1.73 μg/cm²) (p < 0.01). The pharmacodynamics study showed that the therapeutic effect of MEs-Ap was better than that of Differin® in the acne model of rabbit auricle. These results suggested that the MEs-Ap could be considered as a having higher epidermal penetrability, dermal retention, local bioavailability, efficacy, and safety topical preparations for acne. Graphical abstract.

Caenorhabditis elegans mounts a p38 MAPK pathway-mediated defence to Cutibacterium acnes infection

Cutibacterium acnes is capable of inducing inflammation in acne and can lead to a chronic prostatic infection. The diverse pathogenicity among different strains of C. acnes has been presented, but simple appropriate animal models for the evaluation of this bacterium are lacking. In this study, the nematode Caenorhabditis elegans was used as an invertebrate infection model. We revealed that C. acnes type strain ATCC 6919 caused lethal infections to C. elegans in solid and liquid culture media (p < .0001). Compared with the strain ATCC 6919, the antibiotic-resistant strain HM-513 was more virulent, resulting in reduced survival (p < .0001). Four different C. acnes strains killed worms with a p value of less than .0001 when provided to C. elegans at 4.8 × 10⁸  CFU/ml. The infection model was also employed to explore host defence responses. An increase in numerous immune effectors in response to C. acnes was detected. We focused on nine C-type lectins, including: clec-13, clec-17, clec-47, clec-52, clec-60, clec-61, clec-70, clec-71 and clec-227. The induced expression of these C-type lectin genes was down-regulated in mutant worms deficient in the p38 mitogen-activated protein kinase (MAPK) pathway. Meanwhile, PMK-1 (MAPK) was phosphorylated and activated at the onset of C. acnes infection. By monitoring the survival of mutant worms, we found that PMK-1, SEK-1 (MAPKK) and TIR-1 (MAPKKK) were critical in responding to C. acnes infection. C. elegans pmk-1 and tir-1 mutants exhibited higher mortality to C. acnes infection (p < .0001). In conclusion, C. elegans serves as a simple and valuable model to study C. acnes virulence and facilitates improvements in understanding of host innate immune responses.

Chlorin, Phthalocyanine, and Porphyrin Types Derivatives in Phototreatment of Cutaneous Manifestations: A Review

Recent scientific research has shown the use of chlorin, phthalocyanines, and porphyrins derivatives as photosensitizers in photodynamic therapy in the treatment of various pathologies, including some of the major skin diseases. Thus, the main goal of this critical review is to catalog the papers that used these photosensitizers in the treatment of acne vulgaris, psoriasis, papillomavirus infections, cutaneous leishmaniasis, and skin rejuvenation, and to explore the photodynamic therapy mechanisms against these conditions alongside their clinical benefits.