Leishmanicidal effect of antiparasitic photodynamic therapy—ApPDT on infected macrophages

Adjunctive phototherapies for oral manifestation of HIV-related histoplasmosis and leishmaniasis: An unusual case report

BACKGROUND

Secondary infections of leishmaniasis and histoplasmosis in patients with advanced HIV are still a concern in low- and middle-income countries. The most common drugs for the treatment of both infections may be problematic mainly due to their toxicity.

AIM AND CASE REPORT

The present study aimed to report a case in which a concurrent oral manifestation of leishmaniasis and histoplasmosis in a hospitalized patient with HIV was managed with a combination of photobiomodulation therapy (PBMT) and antimicrobial photodynamic therapy (aPDT) as an adjuvant treatment. In addition to the use of conventional systemic oral drugs, a single aPDT session followed by two PBMT sessions was proposed, which resulted in complete wound healing within four days.

CONCLUSION

Given the complexity of the current case, PBMT in combination with aPDT may be considered as an effective adjuvant option for managing oral infectious lesions of histoplasmosis and leishmaniasis in immunocompromised patients.

Vaterite microparticle-loaded methylene blue for photodynamic activity in macrophages infected with Leishmania braziliensis

Calcium carbonate (CaCO3) exhibits a variety of crystalline phases, including the anhydrous crystalline polymorphs calcite, aragonite, and vaterite. Developing porous calcium carbonate microparticles in the vaterite phase for the encapsulation of methylene blue (MB) as a photosensitizer (PS) for use in photodynamic therapy (PDT) was the goal of this investigation. Using an adsorption approach, the PS was integrated into the CaCO3 microparticles. The vaterite microparticles were characterized by scanning electron microscopy (SEM) and steady-state techniques. The trypan blue exclusion method was used to measure the biological activity of macrophages infected with Leishmania braziliensis in vitro. The vaterite microparticles produced are highly porous, non-aggregated, and uniform in size. After encapsulation, the MB-loaded microparticles kept their photophysical characteristics. The carriers that were captured allowed for dye localization inside the cells. The results obtained in this study indicated that the MB-loaded vaterite microparticles show promising photodynamic activity in macrophages infected with Leishmania braziliensis.

The role of the light source in antimicrobial photodynamic therapy

Antimicrobial photodynamic therapy (APDT) is a promising approach to fight the growing problem of antimicrobial resistance that threatens health care, food security and agriculture. APDT uses light to excite a light-activated chemical (photosensitiser), leading to the generation of reactive oxygen species (ROS). Many APDT studies confirm its efficacy in vitro and in vivo against bacteria, fungi, viruses and parasites. However, the development of the field is focused on exploring potential targets and developing new photosensitisers. The role of light, a crucial element for ROS production, has been neglected. What are the main parameters essential for effective photosensitiser activation? Does an optimal light radiant exposure exist? And finally, which light source is best? Many reports have described the promising antibacterial effects of APDT in vitro, however, its application in vivo, especially in clinical settings remains very limited. The restricted availability may partially be due to a lack of standard conditions or protocols, arising from the diversity of selected photosensitising agents (PS), variable testing conditions including light sources used for PS activation and methods of measuring anti-bacterial activity and their effectiveness in treating bacterial infections. We thus sought to systematically review and examine the evidence from existing studies on APDT associated with the light source used. We show how the reduction of pathogens depends on the light source applied, radiant exposure and irradiance of light used, and type of pathogen, and so critically appraise the current state of development of APDT and areas to be addressed in future studies. We anticipate that further standardisation of the experimental conditions will help the field advance, and suggest key optical and biological parameters that should be reported in all APDT studies. More in vivo and clinical studies are needed and are expected to be facilitated by advances in light sources, leading to APDT becoming a sustainable, alternative therapeutic option for bacterial and other microbial infections in the future.

Evaluation of photodynamic therapy against Leishmania tropica promastigotes using different photosensitizers

BACKGROUND

Photodynamic therapy is a two-step procedure, involving the use of photosensitizing agents followed by selective illumination of the target lesion with visible light. Photodynamic therapy has been described recently as a promising strategy for treatment of leishmaniasis. This study aims to evaluate the in vitro phototoxic, morphological, and apoptotic effect of methylene blue, toluidine blue, chloro-aluminum phthalocyanine, and pheophorbide a-mediated photodynamic therapy on the viability of Leishmania tropica promastigotes.

METHODS

Parasites were treated with methylene blue, toluidine blue, chloro-aluminum phthalocyanine, and pheophorbide a or/and methylene blue, toluidine blue, chloro-aluminum phthalocyanine, and pheophorbide a-mediated photodynamic therapy, and cell proliferation, morphological changes, and apoptosis were evaluated by XTT, giemsa staining, DAPI staining, and DNA fragmentation, respectively.

RESULTS

Parasite viability was significantly different in between the groups treated with methylene blue, toluidine blue, and pheophorbide a, with or without irradiation. chloro-aluminum phthalocyanine treatment did not lead to any alterations in cell viability in Leishmania tropica promastigotes with or without irradiation. DAPI staining results indicated that apoptotic bodies and nucleus fragmentation started to be visible in methylene blue, chloro-aluminum phthalocyanine, and pheophorbide a-mediated photodynamic therapy groups. DNA ladder pattern which is used to define apoptosis was observed in irradiated methylene blue, chloro-aluminum phthalocyanine, and pheophorbide a groups.

CONCLUSIONS

The results revealed that apoptosis-induced cell death was observed in Leishmania tropica promastigotes after the application of photosensitizers in combination with light irradiation.

Progress in the photodynamic therapy treatment of Leishmaniasis

Leishmaniasis is a serious and endemic infectious disease that has been reported in more than 90 countries and territories. The classical treatment presents a series of problems ranging from difficulty in administration, development of resistance, and a series of side effects. Photodynamic therapy (PDT) has already shown great potential for use as a treatment for leishmaniasis that is effective and non-invasive, with very minor side effects. PDT can also be inexpensive and easy to administer. In this review, we will report the most recent developments in the field, starting with the chemical diversity of photosensitizers, highlighting important mechanistic aspects, and noting information that may assist in designing and developing new and promising photosensitizer molecules.

Evaluation of the Photodynamic Therapy with Curcumin on L. braziliensis and L. major Amastigotes

Cutaneous leishmaniasis (CL) is a neglected disease prevalent in tropical countries with the ability to cause skin lesions. Photodynamic therapy (PDT) represents a specific and topical option for the treatment of these lesions. This study evaluated the response of macrophages infected with L. braziliensis and L. major to PDT with curcumin. Curcumin concentrations were evaluated in serial dilutions from 500.0 to 7.8 µg/mL using LED (λ = 450 ± 5 nm), with a light dose of 10 J/cm². The Trypan blue viability test, ultrastructural analysis by scanning electron microscopy (SEM), mitochondrial polarity by Rhodamine 123 (Rho 123), curcumin internalization by confocal microscopy, and counting of the recovered parasites after the PDT treatment were performed. The lowest concentrations of curcumin (15.6 and 7.8 µg/mL) presented photodynamic inactivation. Cell destruction and internalization of curcumin in both macrophages and intracellular parasites were observed in microscopy techniques. In addition, an increase in mitochondrial membrane polarity and a decrease in the number of parasites recovered was observed in the PDT groups. This study indicates that PDT with curcumin has the potential to inactivate infected macrophages and might act as a basis for future in vivo studies using the parameters herein discussed.

Efficient photodynamic inactivation of Leishmania parasites mediated by lipophilic water-soluble Zn(II) porphyrin ZnTnHex-2-PyP4

BACKGROUND

Photodynamic inactivation (PDI) is emerging as a promising alternative for cutaneous leishmaniasis (CL). The chemotherapy currently used presents adverse effects and cases of drug resistance have been reported. ZnTnHex-2-PyP⁴⁺ is a porphyrin with a high potential as a photosensitizer (PS) for PDI, due to its photophysical properties, structural stability, and cationic/amphiphilic character that can enhance interaction with cells. This study aimed to investigate the photodynamic effects mediated by ZnTnHex-2-PyP⁴⁺ on Leishmania parasites.

METHODS

ZnTnHex-2-PyP⁴⁺ stability was evaluated using accelerated solvolysis conditions. The photodynamic action on promastigotes was assessed by (i) viability assays, (ii) mitochondrial membrane potential evaluation, and (iii) morphological analysis. The PS-promastigote interaction was studied. PDI on amastigotes and the cytotoxicity on macrophages were also analyzed.

RESULTS

ZnTnHex-2-PyP⁴⁺, under submicromolar concentration, led to immediate inactivation of more than 95% of promastigotes. PDI promoted intense mitochondrial depolarization, loss of the fusiform shape, and plasma membrane wrinkling in promastigotes. Fluorescence microscopy revealed a punctate PS labeling in the parasite cytoplasm. PDI also led to reductions of ca. 64% in the number of amastigotes/macrophage and 70% in the infection index after a single treatment session. No noteworthy toxicity was observed on mammalian cells.

CONCLUSIONS

ZnTnHex-2-PyP⁴⁺ is stable against demetallation and more efficient as PS than the ethyl analogue ZnTE-2-PyP⁴⁺, indicating readiness for evaluation in in vivo studies as an alternative approach to CL.

GENERAL SIGNIFICANCE

This report highlighted promising photodynamic effects mediated by ZnTnHex-2-PyP⁴⁺ on Leishmania parasites, opening up perspectives for applications in CL pre-clinical assays and PDI of other microorganisms.

Pathological Mechanism of Photodynamic Therapy and Photothermal Therapy Based on Nanoparticles

The ultimate goal of phototherapy based on nanoparticles, such as photothermal therapy (PTT) which generates heat and photodynamic therapy (PDT) which not only generates reactive oxygen species (ROS) but also induces a variety of anti-tumor immunity, is to kill tumors. In addition, due to strong efficacy in clinical treatment with minimal invasion and negligible side effects, it has received extensive attention and research in recent years. In this paper, the generations of nanomaterials in PTT and PDT are described separately. In clinical application, according to the different combination pathway of nanoparticles, it can be used to treat different diseases such as tumors, melanoma, rheumatoid and so on. In this paper, the mechanism of pathological treatment is described in detail in terms of inducing apoptosis of cancer cells by ROS produced by PDT, immunogenic cell death to provoke the maturation of dendritic cells, which in turn activate production of CD4+ T cells, CD8+T cells and memory T cells, as well as inhibiting heat shock protein (HSPs), STAT3 signal pathway and so on.

Natural anthraquinones as novel photosentizers for antiparasitic photodynamic inactivation

BACKGROUND

Cutaneous leishmaniasis (CL) is a vector-borne disease caused by obligate protist parasites from the genus Leishmania. The potential toxicity as well as the increased resistance of standard treatments has encouraged the development of new therapeutical strategies. Photodynamic inactivation (PDI) combines the use of a photosensitizer and light to generate reactive oxygen species and kill cells, including microorganisms. Vegetal kingdom constitutes an important source of bioactive compounds that deserve to be investigated in the search of naturally occurring drugs with leishmanicidal activity.

PURPOSE

The purpose of this study was to test the antiparasitic activity of PDI (ApPDI) of five natural anthraquinones (AQs) obtained from Heterophyllaea lycioides (Rusby) Sandwith (Rubiacae). To support our results, effect of AQ mediated-PDI on parasite´s morphology and AQ uptake were studied. Cytotoxicity on fibroblasts was also evaluated.

STUDY DESIGN/METHODS

Two monomers, soranjidiol (Sor) and 5-chlorosoranjidiol (5-ClSor) plus three bi-anthraquinones (bi-AQs), bisoranjidiol (Bisor), 7-chlorobisoranjidiol (7-ClBisor) and Lycionine (Lyc) were selected for this study. Recombinant L. amazonensis promastigote strain expressing luciferase was subjected to AQs and LED treatment. Following irradiation with variable light parameters, cell viability was quantified by bioluminescence. Alteration on parasite's morphology was analyzed by scanning electron microscopy (SEM). In addition, we verified the AQ uptake in Leishmania cells by fluorescence and their toxicity on fibroblasts by using MTT assay.

RESULTS

Bisor, Sor and 5-ClSor exhibited photodynamic effect on L. amazonensis. SEM showed that promastigotes treated with Bisor-mediated PDI exhibited a significant alteration in shape and size. Sor and 5-ClSor presented higher uptake levels than bi-AQs (Bisor, Lyc and 7-ClBisor). Finally, Sor and Bisor presented the lowest toxic activity against fibroblasts.

CONCLUSION

Taking together, our results indicate that Sor presents the highest specificity towards Leishmania cells with no toxicity on fibroblasts.

Exploiting knowledge on pharmacodynamics-pharmacokinetics for accelerated anti-leishmanial drug discovery/development

Introduction: Being on the top list of neglected tropical diseases, leishmaniasis has been marked for elimination by 2020. In the light of small armamentarium of drugs and their associated drawbacks, the understanding of pharmacodynamics and/or pharmacokinetics becomes a priority to achieve and sustain disease elimination. Areas covered: The authors have looked into pharmacological aspects of existing and emerging drugs for treatment of leishmaniasis. An in-depth understanding of pharmacodynamics and pharmacokinetics (PKPD) provides a rationale for drug designing and optimizing the treatment strategies. It forms a key to prevent drug resistance and avoid drug-associated adverse effects. The authors have compiled the researches on the PKPD of different anti-leishmanial formulations that have the potential for improved and/or effective disease intervention. Expert opinion: Understanding the pharmacological aspects of drugs forms the basis for the clinical application of novel drugs. Tailoring drug dosage and individualized treatment can avoid the adverse events and bridge gap between the in vitro models and their clinical application. An integrated approach, with pragmatic use of technological advances can improve phenotypic screening and physiochemical properties of novel drugs. Concomitantly, this can serve to improve clinical efficacies, reduce the incidence of relapse and accelerate the drug discovery/development process for leishmaniasis elimination.

Low-cost light-induced therapy to treat rickettsial infection

Antimicrobial photodynamic therapy uses a nontoxic photosensitizer with the assistance of harmless visible light to activate the photosensitizer. Consequently, the excited state of the photosensitizer interacts with molecular oxygen to produce reactive oxygen species, which have the antimicrobial effect. In this study, we evaluated the effect of photodynamic therapy on Vero cells infected with rickettsia using methylene blue as a photosensitizer along with red light. A significant reduction (by 96%) in the number of viable Rickettsia slovaca was determined by quantitative RT-PCR 48 h after the treatment with methylene blue followed by 30 min of red light excitation. A statistically significant reduction of R. slovaca was also recorded with pretreatment (by 99%). To the best of our knowledge, this result is the first one in the literature to confirm the effectiveness of photodynamic therapy for the elimination of R. slovaca and to suggest this technique as a good supportive treatment for rickettsial infections.

Oral hygiene in intensive care unit patients with photodynamic therapy: study protocol for randomised controlled trial

BACKGROUND

In intensive care units (ICUs), nosocomial infections are prevalent conditions and they have been related to high mortality indexes. Some studies have suggested that inefficient oral hygiene and ventilator-associated pneumonia (VAP) are related. Nowadays, in the Brazilian public health system there is no well-defined protocol for oral hygiene in an ICU. Due to the drawbacks of the use of antibiotics, photodynamic therapy (PDT) has emerged as an interesting technique in order to reduce antimicrobial-resistant pathogens. Methylene blue (MB) is the most common chemical agent for PDT in Brazil. However, new formulations for improved effectiveness are still lacking. The objective of this study is to evaluate the use of an MB mouthwash as an effective oral-hygiene procedure in an ICU and to show that oral hygiene using PDT with MB mouthwash may reduce VAP frequency to rates similar to, or higher than, chlorhexidine.

METHODS

Phase 1 will evaluate the most effective cleaning procedure, while phase 2 will correlate oral hygiene to VAP incidence. At the start of phase 1, the ICU patients will be randomly allocated into three different groups (10 patients/group): the efficacy of chlorhexidine, classical MB-PDT, and mouthwash MB-PDT will all be measured for the quantification of viable bacteria, both pre- and post-treatment, by a Reverse Transcription Polymerase Chain Reaction (RT-PCR). In phase 2, the most effective procedure found in phase 1 and a mechanical cleaning with filtered water will be carried out daily, once a day, over 5 days, with a total of 52 ICU patients randomly allocated into the two groups. The clinical records will be evaluated in order to find any pneumonic diagnoses.

DISCUSSION

Since a variety of bacterial species are related to VAP, a universal primer for bacteria will be used in order to quantify the total bacteria count in the participants' samples. In order to quantify only the living bacteria before DNA extraction, the samples will be treated with propidium monoazide. This will infiltrate the dead bacteria and will intercalate the DNA bases, avoiding their DNA amplification. This will be the first trial to evaluate MB-PDT in a mouthwash formula that can increase the effectiveness due to the control of MB aggregation. The results of this study will be able to generate an easy and low-cost protocol to be used in an ICU for the Brazilian public health system.

TRIAL REGISTRATION

This protocol was approved by the Research Ethics Committee of the Conjunto Hospitalar do Mandaqui (1.317.834, CAAE: 49273515.9.3001.5551) and it was registered in Registro Brasileiro de Ensaios Clínicos (ReBEC number: RBR-94bvrc;). First received: 12 July 2015; 1st version 6 June 2016. Data will be published in a peer-reviewed journal.