Efficacy of antifungal PACT in an in vitro model of onychomycosis

Common diseases of the nail: Diagnosis and therapy

This review focuses on nail changes that do not belong to the group of benign or malignant nail tumors. These common afflictions of the nail include structural changes in and under the nail plate as well as inflammation around and in the nail bed. They include onychomycoses, nail psoriasis, onychodystrophies, subungual hematoma, paronychia, ingrown nails and pincer nails. Due to the peculiar anatomy and physiological growth conditions of the nail, the pathology does not necessarily stem from the site of the clinical problem and calls for careful inspection and interpretation.

Photosensitizers Mediated Photodynamic Inactivation against Fungi

Superficial and systemic fungal infections are essential problems for the modern health care system. One of the challenges is the growing resistance of fungi to classic antifungals and the constantly increasing cost of therapy. These factors force the scientific world to intensify the search for alternative and more effective methods of treatment. This paper presents an overview of new fungal inactivation methods using Photodynamic Antimicrobial Chemotherapy (PACT). The results of research on compounds from the groups of phenothiazines, xanthanes, porphyrins, chlorins, porphyrazines, and phthalocyanines are presented. An intensive search for a photosensitizer with excellent properties is currently underway. The formulation based on the existing ones is also developed by combining them with nanoparticles and common antifungal therapy. Numerous studies indicate that fungi do not form any specific defense mechanism against PACT, which deems it a promising therapeutic alternative.

Aloe-emodin-mediated antimicrobial photodynamic therapy against dermatophytosis caused by Trichophyton rubrum

Trichophyton rubrum is responsible for the majority of dermatophytosis. Current systemic and topical antifungals against dermatophytosis are often tedious and sometimes unsatisfactory. Antimicrobial photodynamic therapy (aPDT) is a non‐invasive alternative suitable for the treatment of superficial fungal infections. This work investigated the photodynamic inactivation efficacy and effects of aloe‐emodin (AE), a natural photosensitizer (PS) against T. rubrum microconidia in vitro, and evaluated the treatment effects of AE‐mediated aPDT for T. rubrum‐caused tinea corporis in vivo and tinea unguium ex vivo. The photodynamic antimicrobial efficacy of AE on T. rubrum microconidia was evaluated by MTT assay. The inhibition effect of AE‐mediated aPDT on growth of T. rubrum was studied. Intracellular location of AE, damage induced by AE‐mediated aPDT on cellular structure and surface of microconidia and generation of intracellular ROS were investigated by microscopy and flow cytometry. The therapeutic effects of AE‐mediated aPDT against dermatophytosis were assessed in T. rubrum‐caused tinea corporis guinea pig model and tinea unguium ex vivo model. AE‐mediated aPDT effectively inactivated T. rubrum microconidia in a light energy dose‐dependent manner and exhibited strong inhibitory effect on growth of T. rubrum. Microscope images indicated that AE is mainly targeted to the organelles and caused damage to the cytoplasm of microconidia after irradiation through generation of abundant intracellular ROS. AE‐mediated aPDT demonstrated effective therapeutic effects for T. rubrum‐caused tinea corporis on guinea pig model and tinea unguium in ex vivo model. The results obtained suggest that AE is a potential PS for the photodynamic treatment of dermatophytosis caused by T. rubrum, but its permeability in skin and nails needs to be improved.

ALA-PDT successfully treated Majocchi's granuloma by directly killing Trichophyton tonsurans and recruiting T lymphocytes

BACKGROUND

Majocchi's granuloma (MG) is a deep persistent suppurative granulomatous perifolliculitis which might be caused by Trichophyton tonsurans (T. tonsurans). Conventional treatment for MG is oral administration of systematic antifungal drugs, associated with a low cure rate and a high relapse rate. ALA-PDT is a new approach for fungal infection.

METHODS

A case of refractory MG was treated by 3 times of ALA-PDT. At the same time, T. tonsurans strains isolated from the lesions of the patient were used for an in vitro inhibition experiment and an in vivo experiment in guinea pig model to furtherly verify the effectiveness and investigate the mechanism of ALA-PDT for T. tonsurans.

RESULTS

After 3 times of ALA-PDT, the lesions of MG were eliminated. And the mycological and pathological examination showed a disappearance of fungi in follicles. In vitro and in vivo experiment both demonstrated that ALA-PDT could obviously inhibit the growth of T. tonsurans partly by directly destroying the structure of fungal cells and recruiting CD4 + T cells.

CONCLUSION

ALA-PDT is a potentially effective noninvasive method for the treatment of MG with mechanisms of direct killing and with CD4⁺ T cell-mediated immune response.

Chemical and physical strategies in onychomycosis topical treatment: A review

Onychomycosis is a fungal infection of the fingernails or toenails caused by dermatophytes, nondermatophytes, moulds, and yeasts. This condition affects around 10-30% people worldwide, negatively influencing patients' quality of life, with severe outcomes in some cases. Since the nail unit acts as a barrier to exogenous substances, its physiological features hampers drug penetration, turning the onychomycosis treatment a challenge. Currently, there are several oral and topical therapies available; nevertheless, cure rates are still low and relapse rates achieves 10-53%. Also, serious side effects may be developed due to long-term treatment. In light of these facts, researchers have focused on improving topical treatments, either by modifying the vehicle or by using some physical technique to improve drug delivery trough the nail plate, hence increasing therapy effectiveness. Therefore, the aim of this paper is to explain these novel alternative approaches. First, the challenges for drug ungual penetration are presented. Then, the chemical and physical strategies developed for overcoming the barriers for drug penetration are discussed. We hope that the information gathered may be useful for the development of safer and more effective treatments for onychomycosis.

Effective Single Photodynamic Treatment of ex Vivo Onychomycosis Using a Multifunctional Porphyrin Photosensitizer and Green Light

Onychomycosis is predominantly caused by the dermatophytes Trichophyton rubrum, Trichophyton mentagrophytes and Trichophyton tonsurans. The main treatment obstacle concerns low nail-plate drug permeability. In vitro antifungal photodynamic treatment (PDT) and nail penetration enhancing effectiveness have been proven for multifunctional photosensitizer 5,10,15-tris(4-N-methylpyridinium)-20-(4-(butyramido-methylcysteinyl)-hydroxyphenyl)-[21H,23H]-porphine trichloride (PORTHE). This study investigates single PORTHE green laser/LED PDT of varying degrees of ex vivo onychomycoses in a human nail model. T. mentagrophytes, T. rubrum, T. tonsurans onychomycoses were ex vivo induced on nail pieces at 28 °C (normal air) and 37 °C (6.4% CO₂) during 3 to 35 days and PDTs applied to the 37 °C infections. All dermatophytes showed increasingly nail plate invasion at 37 °C between 7 and 35 days; arthroconidia were observed after 35 days for T. mentagrophytes and T. tonsurans. Using 81 J/cm² (532 nm) 7-day T. mentagrophytes onychomycoses were cured (92%) with 80 µM PORTHE (pH 8) after 24 h propylene glycol (PG, 40%) pre-treatment and 35-day onychomycoses (52%–67%) with 24 h PORTHE (40–80 µM)/40% PG treatment (pH 5). 28 J/cm² LED light (525 ± 37 nm) improved cure rates to 72%, 83% and 73% for, respectively, T. mentagrophytus, T. rubrum and T. tonsurans 35-day onychomycoses and to 100% after double PDT. Data indicate PDT relevance for onychomycosis.