Clinical retrospective analysis of long-pulsed 1064-nm Nd:YAG laser in the treatment of onychomycosis and its effect on the ultrastructure of fungus pathogen

Morphological and ultrastructural changes in fungal agents after LASER application

BACKGROUND

Onychomycosis is a fungal nail infection of difficult treatment due to the fungal survival capacity and reduced number of effective therapies. The present study aimed to isolate fungal agents that cause onychomycosis in immunocompetent patients and evaluate how LASER treatments affect the growth and ultrastructure of isolates.

METHODS

In total, 21 patients with positive direct microscopic examination (DME) for onychomycosis had nail samples collected for cultivation and phenotypic identification of microorganisms. From these patients, 12 underwent LASER treatment, divided in Group 1 (n = 5) treated with Nd: YAG 1,064 nm, and Group 2 (n = 7) treated with Nd: YAG 1,064 nm + Er: YAG 2,940 nm + topical isoconazole. Transmission Electron Microscopy (TEM) was performed to evaluate ultrastructural changes after treatment.

RESULTS

DME, cultivation, and phenotypic identification showed that the most identified fungus was Trichophyton rubrum spp. After LASER therapy, sample cultivation showed alterations in the fungal morphology with reduction of hyphae, conidia, and reproductive structures. Alterations in fungal cell wall structure, cytoplasm density, and organelles were observed by TEM.

CONCLUSION

LASER irradiation causes changes in the fungal cells, especially in the number of hyphae and the presence of conidia. In addition, it affects fungal growth and reproduction capacity, which interferes with their infection ability and virulence.

Nd:YAG 1064 nm laser treatment for onychomycosis - is it really effective? A prospective assessment for efficiency and factors contributing to response

Onychomycosis is a highly prevalent and persistent nail disorder primarily caused by dermatophytes. The effectiveness of current topical and systemic antifungals is limited by the extent and severity of the infection, patient demographics and health status, hepatic toxicity, drug interactions and low compliance. Laser therapy is a promising modality for safe and cost-effective removal of mycotic nail. This prospective study assessed the performance of a multi-series long-pulsed Nd:YAG 1064 nm regimen (30-40 J/cm2 , 1 Hz) in the treatment of 213 mycotic nails in 31 patients. Pain and discomfort were scored at each treatment session and mycological and clinical cure rates were determined 3 months after the last treatment session. Patients presented with mostly severe (mean SCIO score: 21.9 ± 8.9), T. rubrum-positive (87.1%) infections. Most (61%) had a family history of onychomycosis and a significant proportion had comorbidities, including hypertension (38.7%), hyperlipidemia (35.5%) and/or diabetes (12.9%). Treatment was well tolerated and there were no reports of nail deformity or burns. By 3 months post-treatment, mycological cure was achieved by 4 (12.9%) and visual improvements were noted for 10 (32.3%) patients, including 3 (9.7%) with moderate to significant improvements. Clinical response correlated with baseline SCIO ≤ 20 (OR: 0.9 [0.13-6.52]), family history of onychomycosis (OR: 0.27 [0.04-1.50]) and comorbidities (OR: 0.44 [0.05-3.74]). In conclusion, Nd:YAG 1064 nm laser is safe and effective for the management of mild-to-moderate onychomycosis in diverse populations. Further studies will be necessary to adjust treatment parameters to patient and nail profiles and to determine the impact of combined laser and topical therapies.

In vivo Guinea Pig Model Study for Evaluating Antifungal Effect of a Dual-Diode Laser with Wavelengths of 405 Nm and 635 Nm on Dermatophytosis

Background

Various laser- and light-based devices have been introduced as complementary or alternative treatment modalities for dermatophytosis, particularly for finger or toenail onychomycosis.

Objective

This study aimed to comparatively evaluate the antifungal effects of 405-nm and 635-nm dual-band diode lasers using an in vivo guinea pig model of dermatophytosis.

Materials and Methods

A guinea pig model was developed by the repetitive application of fungal spore preparations to the back skin of guinea pigs. Dual-diode laser treatment was delivered to the guinea pig skin at a power of 24 mW at a wavelength of 405 nm and 18 mW at 635 nm for 12 min. The treatments were administered three times weekly for 2 weeks, and a mycological study was performed.

Results

Mycological studies using scraped samples obtained from treatment groups A (N = 8) and B (N = 8) after dual-diode laser treatment revealed that seven of eight (87.5%) samples in each group had negative results for direct potassium hydroxide microscopy and fungal culture studies. Skin specimens from each infected laser-untreated guinea pig exhibited spongiotic psoriasiform epidermis with parakeratosis. Meanwhile, skin specimens from infected laser-treated guinea pigs in groups A and B demonstrated thinner epidermal thickness than those from infected untreated controls but thicker than those from uninfected treated controls without noticeable inflammatory cell infiltration in the dermis.

Conclusion

The guinea pig dermatophytosis model can be used to comparatively evaluate the efficacy and safety of various treatment modalities, including dual-diode lasers, for superficial fungal skin infection.

Efficacy of Lasers for the Management of Dermatophyte Toenail Onychomycosis

BACKGROUND

Onychomycosis is a chronic fungal nail infection caused predominantly by dermatophytes, and less commonly by nondermatophyte molds and Candida species. Onychomycosis treatment includes oral and topical antifungals, the efficacy of which is evaluated through randomized, double-blind, controlled trials for US Food and Drug Administration approval. The primary efficacy measure is complete cure (complete mycologic and clinical cure). The secondary measures are clinical cure (usually ≤10% involvement of target nail) and mycologic cure (negative microscopy and culture). Some lasers are US Food and Drug Administration approved for the mild temporary increase in clear nail; however, some practitioners attempt to use lasers to treat and cure onychomycosis.

METHODS

A systematic review of the literature was performed in July of 2020 to evaluate the efficacy rates demonstrated by randomized controlled trials of laser monotherapy for dermatophyte onychomycosis of the great toenail.

RESULTS

Randomized controlled trials assessing the efficacy of laser monotherapy for dermatophyte toenail onychomycosis are limited. Many studies measured cure rates by means of nails instead of patients, and performed only microscopy or culture, not both. Only one included study reported mycologic cure rate in patients as negative light microscopy and culture (0%). The combined clinical cure rates in short- and long-pulsed laser studies were 13.0%-16.7% and 25.9%, respectively. There was no study that reported the complete cure rate; however, one did report treatment success (mycologic cure [negative microscopy and culture] and ≤10% clinical involvement) in nails as 16.7%.

CONCLUSIONS

The effectiveness of lasers as a therapeutic intervention for dermatophyte toenail onychomycosis is limited based on complete, mycologic, and clinical cure rates. However, it may be possible to use different treatment parameters or lasers with a different wavelength to increase the efficacy. Lasers could be a potential management option for older patients and onychomycosis patients with coexisting conditions such as diabetes, liver, and/or kidney diseases for whom systemic antifungal agents are contraindicated or have failed.

Antifungal Activity of a Neodymium-Doped Yttrium Aluminum Garnet 1,064-Nanometer Laser against Sporothrix globosa by Inducing Apoptosis and Pyroptosis via the NLRP3/Caspase-1 Signaling Pathway: In Vitro and In Vivo Study

Sporotrichosis is a deep fungal infection caused by Sporothrix species. Currently, itraconazole is the main treatment, but fungal resistance, adverse effects, and drug interactions remain major concerns, especially in patients with immune dysfunction. Therefore, an alternative treatment is greatly in demand. This animal study aimed to investigate the inhibitory effect of neodymium-doped yttrium aluminum garnet (Nd:YAG) 1,064-nm laser treatment on Sporothrix globosa and to explore whether it happens through regulation of the Nod-like receptor thermoprotein domain-related protein 3 (NLRP3)/caspase-1 pyroptosis and apoptosis pathway. After laser irradiation, a series of studies, including assays of viability (using the cell counting kit-8 [CCK-8]), morphological structure changes, reactive oxygen species (ROS) accumulation, mitochondrial membrane potential, oxidative stress, cell cycle progression, and metacaspase activation, were conducted to estimate the effect of Nd:YAG 1,064-nm laser treatment on Sporothrix globosa cell apoptosis in vitro. For in vivo studies, mice were infected with S. globosa and then treated with laser or itraconazole, and their footpad skin lesions and the changes in the histology of tissue samples were compared. In addition, changes in the levels of NLRP3, caspase-1, and caspase-3 were assessed by immunohistochemistry, while the levels of interleukin 17 (IL-17), interferon gamma (IFN-γ), and transforming growth factor β1 (TGF-β1) in peripheral blood were tested by enzyme-linked immunosorbent assay (ELISA). The in vitro growth of S. globosa was inhibited and apoptosis was observed after laser treatment. According to the in vivo studies, the efficacy of the laser treatment was similar to that of itraconazole. Moreover, the NLRP3/caspase-1 pyroptosis pathway was activated, with a Th1/Th17 cell response, and the expression of caspase-3 was also upregulated. Nd:YAG 1,064-nm laser treatment can effectively inhibit the growth of S. globosa by activating fungal apoptosis and pyroptosis through the NLRP3/caspase-1 pathway. Therefore, Nd:YAG 1,064-nm laser irradiation is an alternative for sporotrichosis therapy.

IMPORTANCE Nd:YAG 1,064-nm laser irradiation is a useful alternative for the treatment of sporotrichosis, especially in patients with liver dysfunction, pregnant women, and children, for whom the administration of antifungal drugs is not suitable. It may improve the overall treatment effect by shortening the duration of antifungal treatment and reducing tissue inflammation.

Preliminary Study on Antifungal Mechanism of Aqueous Extract of Cnidium monnieri Against Trichophyton rubrum

Trichoderma rubrum (T. rubrum) is one of the important pathogens because it is the cause of most dermatomycosis. The treatment of Trichophyton rubrum infection is time-consuming and very expensive; it is easy for the infections to reoccur, leading to therapeutic failures, persistence, and chronic infection. These issues have inspired researchers to study natural alternative therapies instead. Cnidium monnieri (L.), as a kind of traditional Chinese medicine, has a variety of pharmacological activities and a wide range of applications, so it has a high potential for researching and economic value. We detected the effect of aqueous extract of C. monnieri (L.) on the activity of T. rubrum by Cell Count Kit-8 assay (CCK-8), and we found that 128 and 256 μg/ml of aqueous extracts of C. monnieri (L.) co-cultured with T. rubrum for 24 h showed the inhibitory effect on T. rubrum. The results of scanning electron microscopy (SEM) and transmission electron microscopy (TEM) confirmed that aqueous extract of C. monnieri (L.) damaged the T. rubrum. At the same time, mass spectrometry screening with T. rubrum before and after the treatment of 256 μg/ml of aqueous extracts of C. monnieri (L.) showed that 966 differentially expressed proteins were detected, including 524 upregulated differentially expressed genes (DEGs) and 442 downregulated DEGs. The most significantly downregulated protein was chitin synthase (CHS); and the results of qRT-PCR and Western blotting demonstrated that the expression level of CHS was downregulated in the 256 μg/ml group compared with the control group. The study showed that the aqueous extract of C. monnieri (L.) could destroy the morphology of mycelia and the internal structure of T. rubrum, and it could inhibit the growth of T. rubrum. The antifungal effect of aqueous extract of C. monnieri (L.) may be related to the downregulation of the expression of CHS in T. rubrum, and CHS may be one of the potential targets of its antifungal mechanism. We concluded that aqueous extract from C. monnieri (L.) may be a potential candidate for antifungal agents.

Morphological and Transcriptome Analyses Provide Insights into Growth Inhibition of Trichophyton rubrum Caused by Laser Irradiation

Trichophyton rubrum is one of the most common types of dermatophyte, causing superficial skin mycosis in human populations. Although laser treatment of onychomycosis has been proven to be effective in the clinic, the underlying mechanism of the effect of the laser on fungal growth is not clear. The objective of the present study was to observe the ultrastructural changes of Trichophyton rubrum following laser irradiation and compare the transcriptome differences between the laser irradiation group and control group. In the present study, scanning electron microscopy and transmission electron microscopy were used to observe the ultrastructural changes following the laser irradiation of Trichophyton rubrum. We also performed RNA-seq to investigate the effects of laser irradiation on Trichophyton rubrum by comparing the transcriptome pattern with the control. Morphological observation with electron microscopy indicated that laser irradiation resulted in the destruction of the cell membrane system. A significant induction of apoptosis was noted compared with the control group, which was confirmed by the formation of the myeloid body and protein aggregates in the cytoplasm. RNA-seq demonstrated that the expression levels of Acyl-CoA N-acyltransferase and S-adenosyl-L-methionine-dependent methyltransferase were increased in the laser irradiation group. This result indicated that laser irradiation triggered the initiation of the damage repair pathway. In conclusion, the present study suggested that laser irradiation caused physiological injury and therefore inhibited the growth of Trichophyton rubrum.