Influence of photodynamic therapy on immunological aspects of disease - an update

Shedding Light on Photodynamic Therapy in the Treatment of Necrobiosis Lipoidica: A Multicenter Real-Life Experience

Necrobiosis Lipoidica (NL) is a dermatological condition characterized by the development of granulomatous inflammation leading to the degeneration of collagen and subsequent formation of yellowish-brown telangiectatic plaques usually localized on the pretibial skin of middle-aged females. Due to its rarity and unclear etiopathogenesis, therapeutic options for NL are not well-standardized. Among them, photodynamic therapy (PDT) is an emerging tool, although its efficacy has primarily been evaluated in single case reports or small case series. This study reports the real-life experience of a cohort of NL patients treated with PDT at the Section of Dermatology of the University Hospital of Messina and Reggio-Emilia. From 2013 to 2023, 17 patients were enrolled -5 males (29%) and 12 females (71%) aged between 16 and 56 years (mean age: 42 ± 13 years), with a median duration of NL of 8 years. The overall complete clearance (>75% lesion reduction) was 29%, while the partial clearance (25-75% lesion reduction) was 59%, with 12% being non-responders. This study adds to the little amount of evidence present in the literature regarding the effectiveness of PDT in the treatment of NL. Variability in treatment responses among patients underscores the need for personalized protocols, optimizing photosensitizers, light sources, and dosimetry. The standardization of treatment protocols and consensus guidelines are essential to ensure reproducibility and comparability across studies.

Signalling pathway activation by photodynamic therapy: NF-κB at the crossroad between oncology and immunology

The response of tumors to photodynamic therapy (PDT) largely depend on signaling pathways among which the pathway leading to NF-κB activation is of high importance.

A retrospective analysis of real-life practice of off-label photodynamic therapy using methyl aminolevulinate (MAL-PDT) in 20 Italian dermatology departments. Part 1: inflammatory and aesthetic indications

Experimental investigations have demonstrated that photodynamic therapy (PDT) with methyl aminolevulinate (MAL) may be a useful treatment in several inflammatory skin disorders and aesthetic indications. To assess the effectiveness, tolerability and safety of off-label MAL-PDT in daily clinical practice in 20 Italian hospital centers, a retrospective observational study of medical records of patients treated for off-label inflammatory and aesthetic indications was carried out. In all patients standard treatment options had been either ineffective, unacceptably toxic, or medically contraindicated. Clinical data regarding 221 patients affected by 22 different diseases were collected. The most common off-label indication was acne vulgaris, with >75% improvement in 72.8% of patients. Other disorders of the sebaceous gland, i.e. acne rosacea, hidradenitis suppurativa and sebaceous hyperplasia, were less responsive. Alopecia areata did not show any improvement. Granuloma annulare and necrobiosis lipoidica showed marked or moderate response in the majority of treated patients. The rate of patients with complete remission was lower for inflammatory skin disorders with hyperkeratosis, i.e. psoriasis (6/17) and porokeratosis (3/16). The efficacy for lichenoid dermatoses was dependent on the clinical variant (erosive and scleroatrophic were more responsive than hypertrophic). Only 1 of 6 patients with Zoon balanitis had a marked improvement. MAL-PDT of venous leg ulcers, photo-aging and hypertrophic scars led to a marked remission in 3/5, 3/6 and 5/8 patients, respectively. The treatment had to be interrupted because of strong pain and burning in 24 patients. Long term adverse events were not registered. Most patients with marked improvement had lasting remission with overall excellent cosmetic outcomes. The present findings demonstrate a high interest in off-label uses of MAL-PDT for inflammatory skin disorders. According to the observed clinical responses, safety, and favorable cosmetic results, MAL-PDT seems to have a potential therapeutic role for the treatment of granulomatous dermal disorders and follicular inflammatory diseases whereas results in other conditions are less encouraging.

Photodynamic therapy in immune (non-oncological) disorders: focus on benzoporphyrin derivatives

This review examines the efficacy of photodynamic therapy in the treatment of immunological disorders. Photodynamic therapy (PDT) is a 2-step procedure. Firstly, a photosensitiser is introduced into the body, where it accumulates selectively in cells with elevated metabolism, such as cancer cells or activated cells of the immune system. Second, light is applied at a wavelength that excites the photosensitiser, producing a variety of short-lived oxygen-derived species. The effect is dependent on the doses of both photosensitiser and activating light. The mechanisms of action of PDT are multifactorial. Induction of high levels of oxidative stress results in necrotic cell death, while lower intensity oxidative stress initiates apoptosis. Sublethal doses may result in the modification of cell surface receptor expression levels and cytokine release and consequently influence cell behaviour. Immunomodulatory PDT (IPDT) utilises mainly apoptotic and sublethal doses. The studies reported here utilise verteporfin, a benzoporphyrin-derived chlorin-like photosensitiser. Veteporfin is a second generation photosensitiser, displaying rapid clearance and consequently a reduced period of skin photosensitivity compared with the first generation photosensitiser, porfimer sodium. In vivo studies showed that IPDT was effective in alleviating immunopathology in murine models of arthritis, contact hypersensitivity, experimental allergic encephalomyelitis and retention of allogeneic skin grafts. Based on these findings, early stage clinical trials with IPDT were initiated recently for the treatment of psoriasis, psoriatic arthritis and rheumatoid arthritis. While verteporfin has been the photosensitiser which pioneered IPDT, a new benzoporphyrin derivative photosensitiser, QLT0074, is under development. This has demonstrated an enhanced avidity for target cells as well as improved clearance characteristics.

Expression of IL-10, TGF-beta(1) and TNF-alpha in Cultured Keratinocytes (HaCaT Cells) after IPL Treatment or ALA-IPL Photodynamic Treatment

BACKGROUND

Depending on the light dose and concentration of photosensitizer for photodynamic treatment (PDT), a multitude of dose-related events are demonstrable in PDT-treated cells. Sublethal doses may result in the alteration of cytokine release and consequently modify immune actions, rather than cause cell death.

OBJECTIVE

The purpose of this study was to investigate cytokine expression in cultured HaCaT cells after intense pulse light (IPL) treatment or PDT utilizing 5-aminolevulinic acid (ALA) and IPL at sublethal doses.

METHODS

Cultured HaCaT cells were treated with either IPL only (4, 8 and 12 J/cm(2)) or ALA-IPL PDT (100micromol/L of ALA; 0, 4, 8, and 12 J/cm(2) of IPL). The expression of IL-10, TGF-beta(1) and TNF-alpha was investigated by reverse transcription-polymerase chain reaction and enzyme linked immunosorbent assay.

RESULTS

IL-10 protein increased up to 5.95-fold after IPL treatment and up to 2.85-fold after PDT. TGF-beta(1) mRNA and protein showed slight increases after both IPL treatment and PDT, of which the latter induced slightly larger increases. TNF-alpha mRNA and protein showed no induction or reduction after PDT.

CONCLUSION

Increased expressions of IL-10 and TGF-beta(1) was observed after PDT. The induction of IL-10 may contribute to the anti-inflammatory effect, which explains the therapeutic benefit of PDT for inflammatory dermatoses, and that of TGF-beta(1) may be related to the therapeutic effect for psoriasis. The finding that IL-10 induction was more marked after IPL treatment than after PDT suggests that other mechanisms than IL-10 induction in keratinocytes after PDT may participate in the anti-inflammatory effect of PDT.

[Photodynamic therapy in localised prostate cancer]

Photodynamic therapy is based on the administration of an energy source in form of light of a specific wavelength, on a previously photosensitized tissue by a chemical compound, in the presence of oxygen, so that the great deal of free radicals and oxygen derivatives generated (hydroxyl compounds) produces necrosis of the treated tissue. Technique improvement during the last years has allowed its recent development as a therapeutic method for localised prostate cancer. At present, several clinical trials are ongoing in patients with organ-confined prostate cancer both as a first line and salvage treatment. There is no risk either of cancer dissemination in surrounding tissues or accumulative pharmaco-toxicity. Therefore, the technique can be repeated as often as needed and can be administered on a previously irradiated tissue. The literature review shows that photodynamic treatment will become a therapeutic option for patients with prostate cancer in the very near future.

Milestones in the development of photodynamic therapy and fluorescence diagnosis

Many reviews on PDT have been published. This field is now so large, and embraces so many sub-specialties, from laser technology and optical penetration through diffusing media to a number of medical fields including dermatology, gastroenterology, ophthalmology, blood sterilization and treatment of microbial-viral diseases, that it is impossible to cover all aspects in a single review. Here, we will concentrate on a few basic aspects, all important for the route of development leading PDT to its present state: early work on hematoporphyrin and hematoporphyrin derivative, second and third generation photosensitizers, 5-aminolevulinic acid and its derivatives, oxygen and singlet oxygen, PDT effects on cell organelles, mutagenic potential, the basis for tumour selectivity, cell cooperativity, photochemical internalization, light penetration into tissue and the significance of oxygen depletion, photobleaching of photosensitizers, optimal light sources, effects on the immune system, and, finally, future trends.

Photodynamic therapy: update 2006. Part 1: Photochemistry and photobiology

Photodynamic therapy (PDT) is a two-step therapeutic technique in which the topical or systemic delivery of photosensitizing drugs is followed by irradiation with visible light. Activated photosensitizers transfer energy to molecular oxygen, generating reactive oxygen species (ROS). The subsequent oxidation of lipids, amino acids and proteins induces cell necrosis and apoptosis. In addition, ROS indirectly stimulate the transcription and release of inflammatory mediators. The photosensitizers are selective, in that they penetrate and accumulate in tumour cells or in the endothelium of newly formed vessels while generally avoiding the surrounding healthy tissue. The mechanisms of penetration through the cell membrane and the pattern of subcellular localization strongly influence the type of cellular effect. The photobiology and photoimmunology of the haematoporphyrin (Hp) derivative and its purified, lyophilized and concentrated form porfimer sodium have been investigated over the past 30 years. However, interest in PDT in dermatology was not raised until the 1990s with the availability of a simple and effective technique, the topical application of aminolaevulinic acid (ALA) and its methyl ester (methyl aminolaevulinate, MAL) followed by irradiation with broadband red light. At the same time, several new 'second-generation' synthetic sensitizers (e.g. benzoporphyrin derivatives, phthalocyanines, chlorins and porphycenes) became available. These compounds are chemically pure, highly efficient, selective and safe, while offering the advantage that the generalized skin photosensitivity they produce lasts for only a short time. They are currently under clinical evaluation but have not yet been approved for clinical use. This paper provides an overview of the chemistry of the photosensitizers, the photobiology and photoimmunology of the photodynamic reaction as well as the photophysical characteristics of the light sources available for PDT.

Photodynamic therapy of cerebral glioma – A review Part I – A biological basis

Photodynamic therapy (PDT) has been investigated extensively in the laboratory for decades, and for over 25 years in the clinical environment, establishing it as a useful adjuvant to standard treatments for many cancers. A combination of both photochemical and photobiological processes occur that lead to the eventual selective destruction of the tumour cells. It is a potentially valuable adjuvant therapy that can be used in conjunction with other conventional therapies for the treatment of cerebral glioma. PDT has undergone extensive laboratory studies and clinical trials with a variety of photosensitizers (PS) and tumour models of cerebral glioma. Many environmental and genetically based factors influence the outcome of the PDT response. The biological basis of PDT is discussed with reference to laboratory and preclinical studies.

Emerging drugs in psoriasis

Psoriasis is a relatively common, chronic skin disease affecting 1-2% of the population in the developed countries. It is an inflammatory, autoimmune skin disorder characterised by an accelerated rate of epidermal proliferation and disordered differentiation. Since our last review in 1999, considerable progress has been made in understanding the immunopathogenesis of this disease, and new drugs have become available for its treatment. Recent clinical trials showed the efficacy of novel biotechnology approaches, such as blocking tumour necrosis factor-alpha or T-cell-mediated immune response by the anti-CD2, anti-CD11a, anti-B7, anti-CD4 or anti-CD25 approaches. Agents which block type 1 cytokines or skew immune reactions into type 2 are other promising approaches. Other possible targets are chemokines and their receptors, the cytokines and receptors involved in T cell trafficking into the skin, and peroxisome proliferator-activated receptors. Relatively little development is reported of the drugs targeting the keratinocyte or the classical antipsoriatic compounds which include glucocorticoids, vitamin D derivatives and cytostatic agents.

Intracellular signaling mechanisms in photodynamic therapy

In photodynamic therapy (PDT) a sensitizer, light and oxygen are used to induce death of tumor cells and in the treatment of certain noncancerous conditions. Cell death in PDT may occur by apoptosis or by necrosis, depending on the sensitizer, on the PDT dose and on the cell genotype. Some sensitizers that have been used in PDT are accumulated in the mitochondria, and this may explain their efficiency in inducing apoptotic cell death, both in vitro and in vivo. In this review we will focus on the events that characterize apoptotic death in PDT and on the intracellular signaling events that are set in motion in photosensitized cells. Activation of phospholipases, changes in ceramide metabolism, a rise in the cytosolic free Ca2+ concentration, stimulation of nitric oxide synthase (NOS), changes in protein phosphorylation and alterations in the activity of transcription factors and on gene expression have all been observed in PDT-treated cells. Although many of these metabolic reactions contribute to the demise process, some of them may antagonize cell death. Understanding the signaling mechanisms in PDT may provide means to modulate the PDT effects at the molecular level and potentiate its antitumor effectiveness.

Involvement of oxidative stress in NF-kappaB activation in endothelial cells treated by photodynamic therapy

In human endothelial cells ECV 304 and HMEC-1 photosensitized by pyropheophorbide-a methylester (PPME) in sublethal conditions transcription factor Nuclear Factor kappa B (NF-kappaB) activation takes place for several hours. Activated NF-kappaB was functional because it stimulated the transcriptional activation of either a transfected reporter gene or the endogenous gene encoding interleukin (IL)-8. Concomitant with NF-kappaB activation, inhibitor of NF-kappaB alpha (IkappaB alpha) was degraded during photosensitization and IkappaB beta, p100, p105 and IkappaB epsilon were slightly modified. Reactive oxygen species (ROS) were shown to be crucial intermediates in the activation because antioxidants strongly decreased NF-kappaB activation. Using both a fluorescent probe and isotope substitution, it was shown that ROS, and especially singlet oxygen (1O2), were important in the activation process. Because NF-kappaB activation in the presence of ROS was suspected to proceed through a pathway independent of the IkappaB kinases (IKK), we demonstrated that the IKK were indeed not activated by photosensitization but required an intact tyrosine residue at position 42 on IkappaB alpha, suggesting the involvement of a tyrosine kinase in the activation process. This was further reinforced by the demonstration that herbimycin A, a tyrosine kinase inhibitor, prevented NF-kappaB activation by photosensitization but not by TNF alpha, a cytokine known to activate NF-kappaB through an IKK-dependent mechanism.

Verteporfin: a milestone in opthalmology and photodynamic therapy

During the past year, a photosensitiser named benzoporphyrin derivative (BPD) has been approved in 26 countries under the generic name verteporfin (Visudynetrade mark, Novartis), for the treatment of patients with a certain type of the wet form of age-related macular degeneration (AMD) by photodynamic therapy (PDT). AMD is the leading cause of blindness in the developed world, with approximately half a million new cases of the wet form per year. The approval of Visudynetrade mark therapy represents a major milestone in ophthalmology since AMD was previously untreatable by any modality which would preserve existing vision. It was also a milestone in the development of PDT, not only because it represented the first breakthrough in the use of PDT to treat an otherwise untreatable condition, but also because it represented the first mass market for a PDT treatment where prospects of a substantial financial return on many years of investment appear to be likely. In this article, we look at the background to the development of BPD, primarily for its use in AMD, but also in other applications.