Treatment of viral infections with 5-aminolevulinic acid and light

aPDI meets PPE: photochemical decontamination in healthcare using methylene blue-where are we now, where will we go?

Personal protective equipment (PPE) reuse, first recommended in the context of the SARS-CoV-2 pandemic, can mitigate shortages in crisis situations and can greatly reduce the environmental impact of typically single-use PPE. Prior to safe reuse, PPE must be sanitized and contaminating pathogens-in current circumstances viruses in particular-must be inactivated. However, many established decontamination procedures are not equitable and remain unavailable in low-resource settings. In mid-2020, an interdisciplinary consortium of researchers first studied the potential of implementing cheap and easy-to-use antimicrobial photodynamic inactivation (aPDI) using methylene blue as photosensitizer to decontaminate face masks and filtering facepiece respirators. In this perspective piece, we describe the development of this novel method, discuss recent advances, and offer insights into how equitable PPE decontamination via methylene blue-based aPDI may be integrated into circular economy policies in the healthcare sector.

Saliva metabolomic profile of COVID-19 patients associates with disease severity

INTRODUCTION

Coronavirus disease 2019 (COVID-19) is strongly linked to dysregulation of various molecular, cellular, and physiological processes that change abundance of different biomolecules including metabolites that may be ultimately used as biomarkers for disease progression and severity. It is important at early stage to readily distinguish those patients that are likely to progress to moderate and severe stages.

OBJECTIVES

This study aimed to investigate the utility of saliva and plasma metabolomic profiles as a potential parameter for risk stratifying COVID-19 patients.

METHOD

LC-MS/MS-based untargeted metabolomics were used to profile the changes in saliva and plasma metabolomic profiles of COVID-19 patients with different severities.

RESULTS

Saliva and plasma metabolites were screened in 62 COVID-19 patients and 18 non-infected controls. The COVID-19 group included 16 severe, 15 moderate, 16 mild, and 15 asymptomatic cases. Thirty-six differential metabolites were detected in COVID-19 versus control comparisons. SARS-CoV-2 induced metabolic derangement differed with infection severity. The metabolic changes were identified in saliva and plasma, however, saliva showed higher intensity of metabolic changes. Levels of saliva metabolites such as sphingosine and kynurenine were significantly different between COVID-19 infected and non-infected individuals; while linoleic acid and Alpha-ketoisovaleric acid were specifically increased in severe compared to non-severe patients. As expected, the two prognostic biomarkers of C-reactive protein and D-dimer were negatively correlated with sphingosine and 5-Aminolevulinic acid, and positively correlated with L-Tryptophan and L-Kynurenine.

CONCLUSION

Saliva disease-specific and severity-specific metabolite could be employed as potential COVID-19 diagnostic and prognostic biomarkers.

Photobiomodulation for Preventive Therapy of Recurrent Herpes Labialis: A 2-Year In Vivo Randomized Controlled Study

Objective: The present study aimed to evaluate the effectiveness of the application of photobiomodulation therapy (PBMT) in the prevention of recurrent herpes labialis (RHL) through a randomized controlled clinical trial. Background data: RHL is a lifelong infection that effects patients' quality of life. In the literature PBMT has shown positive results preventing RHL, decreasing recurrences and severity of lesions. Despite the good results reported, there are still few controlled clinical studies published on the subject. Methods: For this study, 158 volunteers were recruited and were randomly divided into three study groups: Laser 1-1 J/point (L1J): n = 61, Laser 2-2 J/point (L2J): n = 50, and placebo-0 J/point: n = 47. The treatment consisted of a protocol of 15 sessions throughout 6 months and 2 years of follow-up posttreatment. Results: The results showed that L1J presented the most satisfactory results concerning the reduction of the number of lesions per year and less severity of recurrences in the long-term evaluation when compared with L2J. Both Laser Groups (L1J and L2J) were statistically more efficient than placebo in all aspects analyzed. All patients who received laser treatment (L1J and L2J) and presented recurrences had significant improvement in frequency and/or severity of lesions. No patient had side effects from treatment. Conclusions: PBMT can be effective in the reduction of the frequency of recurrences of RHL and in the severity of postirradiation lesions that may appear.

Antiviral Effects of 5-Aminolevulinic Acid Phosphate against Classical Swine Fever Virus: In Vitro and In Vivo Evaluation

The inhibitory effects of 5-aminolevulinic acid phosphate (5-ALA), an important amino acid for energy production in the host, against viral infections were previously reported. Here, the antiviral effects of 5-ALA against classical swine fever virus (CSFV) belonging to the genus Pestivirus in the Flaviviridae family and its possible mechanisms were investigated. CSFV replication was suppressed in swine cells supplemented with 5-ALA or its metabolite, protoporphyrin IX (PPIX). The infectivity titer of CSFV was decreased after mixing with PPIX extracellularly. In addition, the activities of the replication cycle were decreased in the presence of PPIX based on the CSFV replicon assay. These results showed that PPIX exerted antiviral effects by inactivating virus particles and inhibiting the replication cycle. To evaluate the in vivo efficacy of 5-ALA, pigs were supplemented daily with 5-ALA for 1 week before virus inoculation and then inoculated with a virulent CSFV strain at the 10^7.0 50% tissue culture infectious dose. The clinical scores of the supplemented group were significantly lower than those of the nonsupplemented group, whereas the virus growth was not. Taken together, 5-ALA showed antiviral effects against CSFV in vitro, and PPIX played a key role by inactivating virus particles extracellularly and inhibiting the replication cycle intracellularly.

Photodynamic therapy and Acyclovir in the treatment of recurrent herpes labialis: A controlled randomized clinical trial

BACKGROUND

Herpes Simplex Virus Type 1 (HSV-1) is one of the most widespread infections that can effect the orofacial region. Recurrent infection is considered a life-long oral health problem, leading to pain, discomfort, and social restriction due to esthetic features when active. Effective therapies are needed. This study aimed to compare photodynamic therapy (PDT), Topical Acyclovir (AC), and the association of both in the healing process and self-reported symptomologies of HSV-1 recurrences.

METHODS

Patients were randomly assigned into 3 groups (n = 25): PDT (low-power laser, 660 nm, 40 mW, 120 J/cm², 4.8 J, 120 s per point) and methylene blue (0.005 %) as photosensitizer; AC (5%); PDT + AC.Data concerning lesion size, healing time, and self-reported healing parameters, such as pain, tingling, and edema were taken every day up to complete healing for all studied groups.

RESULTS

There was no significant difference in healing time and pain between groups. AC group showed a significant minor reduction of the lesion compared to the AC-PDT group on day 1. Regarding edema and tingling, the comparison of treatments showed a statistical difference only on day 1, where PDT showed better results.

CONCLUSION

With all the limitations of this study, it can be concluded that only on day 1 PDT showed positive effects in the treatment of herpes lesions in comparison to AC.

Evaluation of human papillomavirus DNA detection-guided aminolaevulinic acid-mediated photodynamic therapy for the treatment of condyloma acuminata

BACKGROUND

Aminolaevulinic acid-mediated photodynamic therapy (ALA-PDT) is used to treat condyloma acuminata (CA), yielding a high clearance rate and low recurrence rate. Consecutive human papillomavirus (HPV) DNA detection can be used to dynamically monitor the therapeutic efficiency of PDT. Here, we evaluated the efficacy of ALA-PDT in the context of different HPV infection states.

METHODS

One hundred thirty-eight patients with HPV infection and visible anogenital warts were enrolled. Microwave or radiofrequency was used to remove visible lesions before PDT. HPV DNA detection was performed using real-time polymerase chain reaction before each PDT session and at follow-up. Treatment was halted after the patient showed two negative results for HPV DNA detection in a row.

RESULTS

Of the 138 patients enrolled in the study, 72 completed treatment. Multisite HPV-infected patients required more sessions of PDT than did single-site infected patients to reach the endpoint of treatment. Compared with patients with only external CA, individuals with internal CA required more sessions to eliminate HPV infection. The total number of PDT sessions performed in the multitype HPV-infected group was significantly higher than that in the single-type infected group. Patients with non-high-risk (HR)-HPV infection required fewer PDT sessions than did those with HR-HPV infection by the end of treatment. Sixty-nine patients were followed-up for at least 6 months, only 2.9% of whom showed recurrence.

CONCLUSIONS

Combined ALA-PDT and HPV DNA detection was an effective strategy for the treatment of CA. Patients with multisite and multitype HPV infection required more PDT sessions to eliminate the virus.

Trends and targets in antiviral phototherapy

Photodynamic therapy (PDT) is a well-established treatment option in the treatment of certain cancerous and pre-cancerous lesions. Though best-known for its application in tumor therapy, historically the photodynamic effect was first demonstrated against bacteria at the beginning of the 20^th century. Today, in light of spreading antibiotic resistance and the rise of new infections, this photodynamic inactivation (PDI) of microbes, such as bacteria, fungi, and viruses, is gaining considerable attention. This review focuses on the PDI of viruses as an alternative treatment in antiviral therapy, but also as a means of viral decontamination, covering mainly the literature of the last decade. The PDI of viruses shares the general action mechanism of photodynamic applications: the irradiation of a dye with light and the subsequent generation of reactive oxygen species (ROS) which are the effective phototoxic agents damaging virus targets by reacting with viral nucleic acids, lipids and proteins. Interestingly, a light-independent antiviral activity has also been found for some of these dyes. This review covers the compound classes employed in the PDI of viruses and their various areas of use. In the medical area, currently two fields stand out in which the PDI of viruses has found broader application: the purification of blood products and the treatment of human papilloma virus manifestations. However, the PDI of viruses has also found interest in such diverse areas as water and surface decontamination, and biosafety.

Mechanisms of Vesicular Stomatitis Virus Inactivation by Protoporphyrin IX, Zinc-Protoporphyrin IX, and Mesoporphyrin IX

Virus resistance to antiviral therapies is an increasing concern that makes the development of broad-spectrum antiviral drugs urgent. Targeting of the viral envelope, a component shared by a large number of viruses, emerges as a promising strategy to overcome this problem. Natural and synthetic porphyrins are good candidates for antiviral development due to their relative hydrophobicity and pro-oxidant character. In the present work, we characterized the antiviral activities of protoprophyrin IX (PPIX), Zn-protoporphyrin IX (ZnPPIX), and mesoporphyrin IX (MPIX) against vesicular stomatitis virus (VSV) and evaluated the mechanisms involved in this activity. Treatment of VSV with PPIX, ZnPPIX, and MPIX promoted dose-dependent virus inactivation, which was potentiated by porphyrin photoactivation. All three porphyrins inserted into lipid vesicles and disturbed the viral membrane organization. In addition, the porphyrins also affected viral proteins, inducing VSV glycoprotein cross-linking, which was enhanced by porphyrin photoactivation. Virus incubation with sodium azide and α-tocopherol partially protected VSV from inactivation by porphyrins, suggesting that singlet oxygen (¹O₂) was the main reactive oxygen species produced by photoactivation of these molecules. Furthermore, ¹O₂ was detected by 9,10-dimethylanthracene oxidation in photoactivated porphyrin samples, reinforcing this hypothesis. These results reveal the potential therapeutic application of PPIX, ZnPPIX, and MPIX as good models for broad antiviral drug design.

Porphyrin-based cationic amphiphilic photosensitisers as potential anticancer, antimicrobial and immunosuppressive agents

Photodynamic therapy (PDT) combines a photosensitiser, light and molecular oxygen to induce oxidative stress that can be used to kill pathogens, cancer cells and other highly proliferative cells. There is a growing number of clinically approved photosensitisers and applications of PDT, whose main advantages include the possibility of selective targeting, localised action and stimulation of the immune responses. Further improvements and broader use of PDT could be accomplished by designing new photosensitisers with increased selectivity and bioavailability. Porphyrin-based photosensitisers with amphiphilic properties, bearing one or more positive charges, are an effective tool in PDT against cancers, microbial infections and, most recently, autoimmune skin disorders. The aim of the review is to present some of the recent examples of the applications and research that employ this specific group of photosensitisers. Furthermore, we will highlight the link between their structural characteristics and PDT efficiency, which will be helpful as guidelines for rational design and evaluation of new PSs.

Laser treatment of recurrent herpes labialis: a literature review

Recurrent herpes labialis is a worldwide life-long oral health problem that remains unsolved. It affects approximately one third of the world population and causes frequent pain and discomfort episodes, as well as social restriction due to its compromise of esthetic features. In addition, the available antiviral drugs have not been successful in completely eliminating the virus and its recurrence. Currently, different kinds of laser treatment and different protocols have been proposed for the management of recurrent herpes labialis. Therefore, the aim of the present article was to review the literature regarding the effects of laser irradiation on recurrent herpes labialis and to identify the indications and most successful clinical protocols. The literature was searched with the aim of identifying the effects on healing time, pain relief, duration of viral shedding, viral inactivation, and interval of recurrence. According to the literature, none of the laser treatment modalities is able to completely eliminate the virus and its recurrence. However, laser phototherapy appears to strongly decrease pain and the interval of recurrences without causing any side effects. Photodynamic therapy can be helpful in reducing viral titer in the vesicle phase, and high-power lasers may be useful to drain vesicles. The main advantages of the laser treatment appear to be the absence of side effects and drug interactions, which are especially helpful for older and immunocompromised patients. Although these results indicate a potential beneficial use for lasers in the management of recurrent herpes labialis, they are based on limited published clinical trials and case reports. The literature still lacks double-blind controlled clinical trials verifying these effects and such trials should be the focus of future research.

Photodynamic therapy induces an immune response against a bacterial pathogen

Photodynamic therapy (PDT) employs the triple combination of photosensitizers, visible light and ambient oxygen. When PDT is used for cancer, it has been observed that both arms of the host immune system (innate and adaptive) are activated. When PDT is used for infectious disease, however, it has been assumed that the direct antimicrobial PDT effect dominates. Murine arthritis caused by methicillin-resistant Staphylococcus aureus in the knee failed to respond to PDT with intravenously injected Photofrin(®). PDT with intra-articular Photofrin produced a biphasic dose response that killed bacteria without destroying host neutrophils. Methylene blue was the optimum photosensitizer to kill bacteria while preserving neutrophils. We used bioluminescence imaging to noninvasively monitor murine bacterial arthritis and found that PDT with intra-articular methylene blue was not only effective, but when used before infection, could protect the mice against a subsequent bacterial challenge. The data emphasize the importance of considering the host immune response in PDT for infectious disease.

Treatment of pediatric molluscum contagiosum with 10% potassium hydroxide solution

BACKGROUND

Molluscum contagiosum (MC) is a common cutaneous viral infection of the skin that is frequently seen in children. Although lesions can resolve spontaneously, treatment is mandatory because of the psychological effect of widespread lesions in children. Potassium hydroxide (KOH) is a strong alkali that has been used by dermatologists for a long time in identifying the fungal infections from skin scrapings.

AIMS

We evaluated 40 children with MC for the safety and efficacy of treatment with topical 10% KOH aqueous solution.

METHODS

Parents were instructed to apply a 10% KOH aqueous solution, twice daily, with a cotton stick to all lesions. Treatment was continued till the lesions showed signs of inflammation or superficial ulceration. Assessments of response and side effects were performed at the end of week 2, week 4, week 8 and week 12.

RESULTS

We found complete clearance of lesions in 37 (92.5%) patients receiving topical 10%KOH solution after a mean period of four weeks. Three children dropped out of the study; two children reported severe stinging of the lesions and discontinued the treatment; the other patient developed hypopigmentation during the treatment. Local side effects were observed in 12 children (32.4%).

CONCLUSION

Even though 10% KOH solution is associated with some local side effects, it is a safe, effective, inexpensive and noninvasive alternative treatment of MC in children.

Photodynamic inactivation of mammalian viruses and bacteriophages

Photodynamic inactivation (PDI) has been used to inactivate microorganisms through the use of photosensitizers. The inactivation of mammalian viruses and bacteriophages by photosensitization has been applied with success since the first decades of the last century. Due to the fact that mammalian viruses are known to pose a threat to public health and that bacteriophages are frequently used as models of mammalian viruses, it is important to know and understand the mechanisms and photodynamic procedures involved in their photoinactivation. The aim of this review is to (i) summarize the main approaches developed until now for the photodynamic inactivation of bacteriophages and mammalian viruses and, (ii) discuss and compare the present state of the art of mammalian viruses PDI with phage photoinactivation, with special focus on the most relevant mechanisms, molecular targets and factors affecting the viral inactivation process.

Photodynamic therapy can improve warts' discomfort in renal transplant patients prospective multicenter study

Many studies have been conducted showing that aminolevulinic acid (ALA)-photodynamic therapy (PDT) can be an alternative treatment for recalcitrant warts. Recently, we performed a study evaluating methyl-aminolevulinic acid (MAL)-PDT for the treatment of hand warts in a population of renal transplant patients. Two symmetrical targets were selected on each hand and randomly assigned to chemical keratolytic treatment followed by three cycles of ALA-PDT (75 J cm(-2) red light). Patients were evaluated after 3 months and a second run of PDT was performed if the total area and number of warts decreased less than 50%, with evaluation every 3 months for 1 year. Twenty patients were included and 16 were evaluable (9 M, 7 F). After 6 months the reduction of warts' area was 48.4% on the treated side versus 18.4% in the control area (P = 0.021). The decrease in the total number of warts was 41%versus 19.4% (P = NS). The global tolerance of the treatment was good with acceptable pain during irradiation. These results suggest that ALA-PDT is a safe and efficient treatment for transplanted patient warts. The improvement between treated and control zone is 20% due to the decrease in untreated warts' area and number.

Photodynamic therapy based on 5-aminolevulinic acid and its use as an antimicrobial agent

Exogenous 5-aminolevulinic acid (ALA) is taken up directly by bacteria, yeasts, fungi, and some parasites, which then induces the accumulation of protoporphyrin IX (PPIX). Subsequent light irradiation of PPIX leads to the inactivation of these organisms via photodamage to their cellular structures. ALA uptake and light irradiation of PPIX produced by host cells leads to the inactivation of other parasites, along with some viruses, via the induction of an immune response. ALA-mediated PPIX production by host cells and light irradiation result in the inactivation of other viruses via either the induction of a host cell response or direct photodynamic attack on viral particles. This ALA-mediated production of light-activated PPIX has been extensively used as a form of photodynamic therapy (PDT) and has shown varying levels of efficacy in treating conditions that are associated with microbial infection, ranging from acne and verrucae to leishmaniasis and onychomycosis. However, for the treatment of some of these conditions by ALA-based PDT, the role of an antimicrobial effect has been disputed and in general, the mechanisms by which the technique inactivates microbes are not well understood. In this study, we review current understanding of the antimicrobial mechanisms used by ALA-based PDT and its role in the treatment of microbial infections along with its potential medical and nonmedical applications.

Efficiency of photodynamic therapy in the treatment of diffuse facial viral warts in an immunosuppressed patient: towards a gold standard?

A 64-year-old man with a pulmonary transplant developed diffuse verrucae vulgares of the neck. After the failure of multiple cryotherapy treatments, 3 sessions of photodynamic therapy resulted in rapid therapeutic clinical success. This moderately painful and well-tolerated treatment is reproducible and can be very useful in treating papillomavirus infections in the immunosuppressed patient.

High-intensity laser and photodynamic therapy as a treatment for recurrent herpes labialis

OBJECTIVE

The aim of this study was to report the treatment of recurrent herpes labialis (RHL) using a high-intensity laser or methylene blue (MB)-mediated photodynamic therapy (PDT) in combination with low-level laser therapy (LLLT).

MATERIALS AND METHODS

Four clinical cases of patients diagnosed with RHL are described in this report. Two patients were subjected to high-intensity laser therapy (HILT) followed by LLLT, and two patients received MB-mediated PDT, again followed by LLLT. LLLT was conducted at 24, 48, 72 h, and 7 d after HILT or PDT. Patients were followed up after 6 mo.

RESULTS

Throughout the follow-up period, all patients reported pain relief and did not show any signs or symptoms of RHL. A favorable healing process was observed in all cases. None of the patients reported pain as a consequence of the treatment.

CONCLUSION

These results suggest that HILT and MB-mediated PDT, in combination with LLLT, may constitute a benefit when treating vesicles in RHL.

Photodynamic therapy for localized infections--state of the art

Photodynamic therapy (PDT) was discovered over 100 years ago by observing the killing of microorganisms when harmless dyes and visible light were combined in vitro. Since then it has primarily been developed as a treatment for cancer, ophthalmologic disorders and in dermatology. However, in recent years interest in the antimicrobial effects of PDT has revived and it has been proposed as a therapy for a large variety of localized infections. This revival of interest has largely been driven by the inexorable increase in drug resistance among many classes of pathogen. Advantages of PDT include equal killing effectiveness regardless of antibiotic resistance, and a lack of induction of PDT resistance. Disadvantages include the cessation of the antimicrobial effect when the light is turned off, and less than perfect selectivity for microbial cells over host tissue. This review will cover the use of PDT to kill or inactivate pathogens in ex vivo tissues and in biological materials such as blood. PDT has been successfully used to kill pathogens and even to save life in several animal models of localized infections such as surface wounds, burns, oral sites, abscesses and the middle ear. A large number of clinical studies of PDT for viral papillomatosis lesions and for acne refer to its antimicrobial effect, but it is unclear how important this microbial killing is to the overall therapeutic outcome. PDT for periodontitis is a rapidly growing clinical application and other dental applications are under investigation. PDT is being clinically studied for other dermatological infections such as leishmaniasis and mycobacteria. Antimicrobial PDT will become more important in the future as antibiotic resistance is only expected to continue to increase.

Terapia fotodinâmica em dermatologia: princípios básicos e aplicações

A terapia fotodinâmica envolve a administração de uma droga fotossensibilizante e sua ativação subsequente pela luz de comprimento de onda correspondente ao espectro de absorção do fotossensibilizador. Atualmente, a terapia fotodinâmica tópica é aprovada para o tratamento de condições oncológicas cutâneas como queratoses actínicas, doença de Bowen e carcinoma basocelular superficial em diversos países do mundo. Estudos multicêntricos controlados e randomizados demonstram a alta eficácia e resultado cosmético final superior dessa modalidade terapêutica em relação aos tratamentos convencionais. Para condições cutâneas não oncológicas, como acne vulgar, verrugas virais e esclerodermia localizada, há também relatos e série de casos confirmando o potencial terapêutico da terapia fotodinâmica. O desenvolvimento de fotossensibilizantes tópicos, ácido 5-aminolevulínico (ALA) ou seu metiléster (MAL), frente aos derivados da hematoporfirina de aplicação sistêmica, permitiu um grande avanço na popularidade da TFD na dermatologia, uma vez que tanto ALA quanto MAL tópicos não induzem mais fotossensibilidade generalizada prolongada. A produção de intermediários reativos de oxigênio, como oxigênio singlet, depende da concentração, da localização do fotossensibilizante no tecido alvo, assim como da dose de luz utilizada. Tanto as lâmpadas de amplo espectro quanto os LEDs (do inglês light emitting diodes) constituem fontes de luz adequadas para que os efeitos citotóxicos da terapia fotodinâmica resultem na destruição do tumor ou seus efeitos imunomodulatórios atuem melhorando as condições inflamatórias cutâneas.

Photodynamic therapy of cervical intraepithelial neoplasia with hexaminolevulinate

BACKGROUND AND OBJECTIVE

CIN is a disease of women in their reproductive years, and treatment includes excisional techniques with increased risk of preterm deliveries. Photodynamic therapy (PDT) using topical precursor of photoactive porphyrins may be a non-invasive alternative with minimal side effects. This study assessed the feasibility and response rate of PDT with hexaminolevulinate (HAL) in cervical intraepithelial neoplasia (CIN) and human papillomavirus (HPV) infection.

STUDY DESIGN/MATERIALS AND METHODS

Twenty four patients with a CIN 2 or 3 or a persistent CIN 1 and a positive high-risk HPV-DNA test were included. Each patient had gynaecologic examination including cervical cytology, HPV DNA testing, colposcopy and biopsy. Ten milliliters of HAL-thermogel (10 mM) were topically applied to the cervix for 3-5 hours, followed by 1,000 seconds of illumination of both ecto- and endocervical canal with red coherent light (wave length 633 nm) using a PDT laser and a special light catheter. Follow-up examinations were carried out after 3 (cytology, colposcopy, HPV DNA testing, and if needed re-PDT) and 6 months.

RESULTS

Seven, 10, and 7 patients had a CIN 1, 2, or 3, respectively. Treatment could be accomplished in all cases and no severe side effects were encountered. Fifteen out of the 24 patients had a complete response (15/24 = 63%) and a HPV remission 6 months after 1-3 treatments. The remission rates were 71%, 50%, and 71% for CIN 1, 2 and 3.

CONCLUSION

HAL PDT seems to be a non-invasive, repeatable procedure for CIN and cervical HPV infection with minimal side effects which can be easily performed on outpatient basis.

[Photodynamic therapy: non-oncologic indications]

While efficacy of topical photodynamic therapy (PDT) for the treatment of superficial non-melanoma skin cancer is already well-proven by several controlled clinical trials, there are only a few controlled studies showing efficacy of PDT for non-oncologic skin disorders. This report provides information on the use of PDT for inflammatory skin disorders, disorders of the pilosebaceous unit, infections of the skin, sclerotic skin diseases and cosmetic indications.

Genital warts treated by photodynamic therapy

The patient, a 30-year-old man with numerous genital condylomata acuminata (CA), has had unsuccessful treatment with liquid nitrogen, 20% podophyllin, and repeated 0.5% podophyllotoxin solution with 5% imiquimod (Figure 1). Before the appearance of CA, he experienced acute orchiepididimitis and a Candida infection. The patient was immunologically examined, and the lower level of lymphocytes, slightly reduced level of IgM, and C4 complement were revealed. Results from a human immunodeficiency virus examination were negative. After the therapeutic failure mentioned above, photodynamic therapy (PDT) was initiated using 20% aminolevulinic acid (5-ALA) in a gel. The photosensitizer was applied to lesions and 10 mm of surrounding skin in a 1-mm-thick layer under occlusive dressing for 3 hours and then removed with saline and nonwoven gauze. The site was immediately irradiated with noncoherent red light with an emission spectrum of 580 to 680 nm wavelength (Medeikonos PDT-Model 200, Medeikonos AB, Sweden). The total light dose was 50 J/cm(2); light intensity ranged from 70 to 90 mW/cm(2). Because of persistent fluorescence during photodynamic therapy, the treatment was repeated 10 times in 2-week intervals with a follow-up of 1, 3, and 6 months after its completion. After the last PDT treatment, the persistent fluorescence disappeared completely. The absence of fluorescence corresponded with a healed clinical finding without scarring and pigmentation (Figure 2). The period from the initiation of PDT to the consolidation of CA was 22 weeks. During PDT treatment, the patient felt only mild burning, which disappeared after the illumination stopped. Six months after the therapy, there were no signs of recurrent disease.

Comparative study of photodynamic therapy vs. CO2laser vaporization in treatment of condylomata acuminata, a randomized clinical trial

BACKGROUND

Most conventional therapies for condylomata acuminata (CA) are traumatic and have high recurrence rates.

OBJECTIVES

To investigate the efficacy and safety of topical application of 5-aminolaevulinic acid (ALA) photodynamic therapy (PDT) for the treatment of CA.

METHODS

Sixty-five patients with CA were allocated into the treatment (ALA-PDT) group and treated with 20% ALA solution under occlusive dressing for 3 h followed by irradiation with the helium-neon laser at a dose of 100 J cm(-2) and a power of 100 mW. Another 21 CA patients were allocated into the control group and treated with the CO(2) laser. The treatment was to be repeated 1 week later if the lesion was not completely removed after the first treatment.

RESULTS

After one treatment, the complete removal rate was 95% in the ALA-PDT group and 100% in the control group. After two treatments with ALA-PDT, the complete removal rate in the treatment group was 100%. The recurrence rate for ALA-PDT group was 6.3% which was significantly lower than that in control group (19.1%, P < 0.05). Moreover, the proportion of patients with adverse effects in the ALA-PDT group (13.9%) was also significantly lower than that in control group (100%, P < 0.05). The side-effects in patients treated with ALA-PDT mainly included mild burning and/or stinging restricted to the illuminated area.

CONCLUSIONS

The present study shows that topical application of ALA-PDT is a simpler, more effective and safer therapy with a lower recurrence for treatment of CA compared with conventional CO(2) laser therapy.

Photodynamic therapy: other uses

Mainstream uses for photodynamic therapy (PDT) in dermatology include nonmelanoma skin cancer and its precursors, acne vulgaris, photorejuvenation, and hidradenitis suppurativa. Many other dermatologic entities have been treated with PDT, including psoriasis, lichen planus, lichen sclerosus, scleroderma, cutaneous T cell lymphoma, alopecia areata, verruca vulgaris, Darier's disease and tinea infections. Nondermatologic applications include anal and vulva carcinoma, palliation of metastatic breast cancer to skin, Barrett's esophagus, and macular degeneration of the retina. PDT also has found to be useful in immunologic and inflammatory disorders, neoplasias other than skin cancer, and infections. The ability of this treatment to hone in on dysplastic epithelial and endothelial cells while retaining viability of surrounding tissue is its key feature because this leads to specific tumor destruction with cosmesis and function of the target organ intact.

Treatment of Verrucae Vulgaris and Molluscum Contagiosum with Photodynamic Therapy

The use of 5-aminolevulinc acid photodynamic therapy in the treatment of recalcitrant verrucae vulgaris and in the treatment of recalcitrant molluscum contagiosum has been shown to substantially reduce the lesion count and severity. Clinical research published in the medical literature and personal experience of both of the authors support the use of 5-aminolevulinc acid photodynamic therapy in appropriate individuals with recalcitrant verrucae vulgaris and molluscum contagiosum lesions. This article reviews the medical literature and identifies the various lasers and lights sources used to treat these conditions.

Comparing and combining light dose fractionation and iron chelation to enhance experimental photodynamic therapy with aminolevulinic acid

BACKGROUND AND OBJECTIVES

Enhancement of photodynamic therapy (PDT) with 5-aminolevulinic acid (ALA) has been demonstrated experimentally using light dose fractionation or CP94 iron chelation. This study extends this research.

STUDY DESIGN/MATERIALS AND METHODS

In normal rat colon, CP94 administration and light dose fractionation were independently and concurrently employed to enhance ALA-PDT. In colonic rat tumors, the most successful enhancement regimes were employed separately.

RESULTS

Independent use of light dose fractionation and iron chelation produced similar results in normal colon (2.4- and 2.9-fold more necrosis than controls, respectively). Using both techniques simultaneously produced fivefold enhancement. In the colonic tumors, light dose fractionation and iron chelation (using different parameters) produced two and five times the volume of necrosis, respectively.

CONCLUSIONS

Both techniques significantly enhanced ALA-PDT in the normal and neoplastic tissues investigated and produced similar levels of enhancement when comparable parameters were employed. Concurrent use of light dose fractionation and iron chelation in normal colon produced considerably more enhancement than either technique could achieve independently.

Terapia fotodinámica en dermatología

Photodynamic therapy (PDT) is a therapeutic modality based on the photooxidation of biological materials induced by a photosensitizer, which selectively locates itself in certain tumorous cells or tissues, so that when illuminated by a light of the right length and at a sufficient dose, these cells are destroyed. In dermatology, PDT with topical 5-aminolevulinic acid or 5-methyl aminolevulinate is very effective in the treatment of actinic keratoses, basal cell carcinomas and Bowen's disease. In addition, very promising results have been obtained in inflammatory pathologies like morphea or sarcoidosis, infections like warts, and cosmetic processes such as photoaging, among others. This article reviews the most significant aspects of PDT in dermatology. First of all, we will review the basic fundamentals of photodynamic treatment. Next, we will outline its clinical applications in dermatology, both in oncological applications and all those dermatological processes in which PDT may play a role in their management. We will also discuss its promising cosmetic application in the treatment of photoaging. We will complete the review with photodiagnosis and the different non-invasive ways to monitor the effectiveness of PDT.

Photodynamic therapy: new treatment for therapy-resistant plantar warts

BACKGROUND

Plantar wart treatment remains a challenging one. Various treatment modalities have been previously used and are still in current use. The problem remains in the degree of response to these treatments and the side effects associated with them.

OBJECTIVE

The aim of this study was to test a new treatment modality for therapy-resistant plantar warts.

METHODS

Thirty-one patients with 48 plantar warts were randomly selected from the Department of Laser Therapy, Medical Centre Maastricht, The Netherlands. The mean age of the patients was 29 years (range 6-74 years). The mean incubation time was 6.8 hours, and the mean treatment time was 18.7 minutes per wart. Each wart was treated an average of 2.3 times, with a median fluence of 100 cm2.

RESULTS

Forty-two of 48 (88%) warts showed a complete response. A trend was found between total clearance and size of the warts, age of the patient, and the mean treatment time. No significant side effects were seen postoperatively.

CONCLUSION

This study showed that recalcitrant plantar warts were successfully treated with no significant side effects; however, the user needs sufficient experience for this new effective treatment application.

Photodynamic therapy targeted to pathogens

Photodynamic therapy (PDT) employs a non-toxic dye termed a photosensitizer (PS) together with low intensity visible light, which, in the presence of oxygen, produce cytotoxic species. PS can be targeted to its destination cell or tissue and, in addition, the irradiation can be spatially confined to the lesion giving PDT the advantage of dual selectivity. This promising approach can be used for various applications including microbial inactivation and the treatment of infections. Resistance to PDT has not been shown and multiantibiotic-resistant strains are as easily killed as naive strains. It is known that Gram (+) bacteria are more sensitive to PDT as compared to Gram (-) species. However, the use of cationic PS or agents that increase the permeability of the outer membrane allows for the effective killing of Gram (-) organisms. Some PS have an innate positive charge, but our approach is to link PS to a cationic molecular vehicle such as poly-L-lysine. This modification dramatically increases PS binding to and penetrating through the negatively charged bacterial permeability barrier. Due to focused light delivery the use of PDT is possible only for localized infections. Nonetheless numerous diseases can be treated. Selectivity of the PS for microbes over host cells, accurate delivery of the PS into the infected area, and PDT dose adjustment help minimize side effects and give PDT an advantage over conventional therapy. There are only a few reports about the use of antimicrobial PDT in animal models and clinical trials. We have used genetically modified bioluminescent bacteria to follow the effect of PDT in infected wounds, burns, and soft tissue infections in mice. Not only were bacteria infecting wounds, burns, and abscesses killed, but mice were saved from death due to sepsis and wound healing was improved.

In vitro effect of 5-aminolaevulinic acid plus visible light on Candida albicans

Photodynamic therapy, currently used as an alternative technique for the treatment of superficial non-melanoma skin cancers, has been employed in vitro to kill different species of microorganisms. Here the development of Candida albicans colonies has been measured after application of 5-aminolaevulinic acid (ALA) plus visible light (VIS) irradiation. C. albicans suspensions (10 colony forming units microl(-1)) have been prepared. For the experiment 30 microl of suspension have been incubated in the dark for 3 h, with increasing concentrations of ALA (125, 250, 300, 350, 400, 450, 500, 550, 600, 750, 1000 mg ml(-1)) and then irradiated with a fixed dose (40 J cm(-2)) of VIS. Immediately after the irradiative session, the C. albicans suspensions were disseminated on dishes containing a Sabouraud agar + CAF medium and cultured in the dark at 27 degree C; after 48 h colony development has been measured. In the same way four controls have been prepared: (i)C. albicans suspensions not treated with ALA-PDT; (ii)C. albicans suspensions incubated with increasing ALA concentrations without VIS; (iii)C. albicans suspensions irradiated with 40 J cm(-2) of VIS without ALA; (iv)C. albicans suspensions irradiated immediately after the addition of increasing concentrations of ALA without the 3 h incubation. Colonies treated with ALA-PDT have been studied with electron microscopy (E.M.). It was found that: (i) none of the controls prepared modified the development of C. albicans colonies; (ii) ALA plus VIS inhibited C. albicans growth in a concentration-dependent way: up to 250 mg ml of ALA concentrations did not affect C. albicans cells, 300 mg ml(-1) induced a 50% reduction in the number of colonies, a complete inhibition started from concentrations of 600 mg ml(-1); (iii) after ALA-PDT E.M. showed modifications of the cell membranes. From the results it is concluded ALA plus VIS light is able to kill C. albicans colonies, at least in vitro. Although other pharmacological approaches are available, further studies could show that PDT is a potential treatment for candidosis.

In vivo fluorescence kinetics and photodynamic therapy in condylomata acuminata

BACKGROUND

Topical application of 5-aminolaevulinic acid (ALA) to condylomata acuminata leads to accumulation of protoporphyrin IX (PpIX); therefore ALA-induced photodynamic therapy (ALA-PDT) appears to be a potential treatment.

OBJECTIVES

To investigate in vivo the PpIX fluorescence time course after topical application of ALA in order to determine the optimal time for irradiation, and to assess the efficacy of subsequently performed ALA-PDT.

METHODS

Fluorescence kinetics was studied in 12 male patients with condylomata acuminata. Confirmation of diagnosis was established with conventional histology and polymerase chain reaction. Lesions were treated with 20% ALA and irradiated at the optimal time with a dose of 70 J cm-2 or 100 J cm-2 light. An additional session with 100 J cm-2 was administered 1 week later to lesions that persisted.

RESULTS

The in vivo study of fluorescence kinetics indicated that the optimal time for irradiation varied among patients from 6 to 11 h. The overall cure rate was 72.9%, 12 months after treatment.

CONCLUSIONS

Topical ALA-PDT is a potentially effective treatment for condylomata acuminata.

Local treatment of viral disease using photodynamic therapy

Although reports of the photodynamic inactivation of viruses appeared in 1928, long before chemotherapeutic antiviral drugs, the first clinical trial in humans-the topical treatment of herpes genitalis-did not take place until the early 1970s. Trials were discontinued due to the transformation of healthy cells and concomitant incidence of Bowen's disease in some patients, probably due to the migration of infective sections of photodamaged viral nucleic acid. With the modern development of photodynamic therapy as a cancer treatment and the use of photosensitisers in the photodecontamination of blood products, a great deal of experience has been gained, both in the minimisation of side effects in humans and in the targeting and eradication of viruses. This suggests that the photodynamic approach to a range of virus-associated infections, lesions and cancer might now be revisited with greater success.