Lipophilicity of Bacteriochlorin-Based Photosensitizers as a Determinant for PDT Optimization through the Modulation of the Inflammatory Mediators

Design and Properties of Azaacene-Fused Porphyrins: Extending π-Systems for NIR-II Absorption

A series of porphyrins featuring various azaacene moieties were designed with the aim to explore the structure-property relationships in extended azaacene systems. The introduction of azaacene groups significantly enhanced the solubility of these chromophores while directly influencing their electronic absorption and emission properties, enabling absorption at longer wavelengths. Protonation of the azaacene-fused porphyrins further extended their absorption into the NIR-II region. The π system extension provided by the new appended diamino aromatic groups were therefore investigated through electrochemical, photophysical, X-ray diffraction structural studies and complemented by theoretical calculations.

Novel approach for fast comparative evaluation of the potency of new photosensitizers using model lipid membranes

The novel approach for fast comparative evaluation of the potency of new photosensitizers using model lipid membranes is described and substantiated. For this purpose, mixed Langmuir monolayers and Langmuir-Blodgett films containing one of the typical relatively easy photodegradable lipid 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) and one of the examined photosensitizers (PSs) are proposed as the models. The changes in the macroscopic properties of such model PS + POPC membranes upon irradiation with visible light (the photo-destruction processes) were recorded using two different methods: commonly used water contact angle measurements and new express method based on the estimation of the changes of the model mixed monolayer mechanical characteristics. The study have been carried out for two series of PSs, cationic and neutral ones. The results of water contact angel measurements have clearly demonstrated that this method can be used for studying the photodestruction of artificial lipid membranes on solid substrates and for comparison of the efficiency of new PSs. However, since model making and measurements are complex and time-consuming, it restricts the preliminary analysis of PSs efficiency. In this work, we suggest rather a simple method for the rapid comparative evaluation of new PSs based on easy and fast measurements, such as recording the surface pressure during irradiation of a PS-containing monolayer directly at an aqueous subphase and determining the mechanical properties of a model monolayer by the oscillating barrier method. The results have demonstrated that the proposed methods are quite valid for studying the photodegradation of artificial lipid membranes and comparing the efficiency of new PSs. In particular, we have shown that these methods can be used not only for multiparametric monitoring of the photodegradation kinetics but also for comparing the efficiency of PSs in lipid structures. The universality of the proposed methods for assessing the effectiveness of PDT at the use of PSs of various structures was demonstrated. The results of this study indicate that cationic PSs exhibit superior activity compared to neutral and anionic ones.

NIR-activated multifunctional agents for the combined application in cancer imaging and therapy

Anticancer therapies that combine both diagnostic and therapeutic capabilities hold significant promise for enhancing treatment efficacy and patient outcomes. Among these, agents responsive to near-infrared (NIR) photons are of particular interest due to their negligible toxicity and multifunctionality. These compounds are not only effective in photodynamic therapy (PDT), but also serve as contrast agents in various imaging modalities, including fluorescence and photoacoustic imaging. In this review, we explore the photophysical and photochemical properties of NIR-activated porphyrin, cyanine, and phthalocyanines derivatives as well as aggregation-induced emission compounds, highlighting their application in synergistic detection, diagnosis, and therapy. Special attention is given to the design and optimization of these agents to achieve high photostability, efficient NIR absorption, and significant yields of fluorescence, heat, or reactive oxygen species (ROS) generation depending on the application. Additionally, we discuss the incorporation of these compounds into nanocarriers to enhance their solubility, stability, and target specificity. Such nanoparticle-based systems exhibit improved pharmacokinetics and pharmacodynamics, facilitating more effective tumor targeting and broadening the application range to photoacoustic imaging and photothermal therapy. Furthermore, we summarize the application of these NIR-responsive agents in multimodal imaging techniques, which combine the advantages of fluorescence and photoacoustic imaging to provide comprehensive diagnostic information. Finally, we address the current challenges and limitations of photodiagnosis and phototherapy and highlight some critical barriers to their clinical implementation. These include issues related to their phototoxicity, limited tissue penetration, and potential off-target effects. The review concludes by highlighting future research directions aimed at overcoming these obstacles, with a focus on the development of next-generation agents and platforms that offer enhanced therapeutic efficacy and imaging capabilities in the field of cancer treatment.

Unravelling the modes of phototoxicity of NIR absorbing chlorophyll derivative in cancer cells under normoxic and hypoxic conditions

The efficacy of photodynamic treatment (PDT) against deep-seated tumor is hindered by low penetration depth of light as well as hypoxic conditions which prevails in tumor. To overcome this limitation, Near-infrared (NIR) absorbing photosensitizers have been investigated actively. In the present study we evaluated the PDT efficacy of an NIR absorbing chlorophyll derivative 'Cycloimide Purpurin-18 (CIPp-18)' in Human Breast carcinoma (MCF-7) and cervical adenocarcinoma (Hela) cells under normoxic and hypoxic conditions. PDT with CIPp-18 (2.0 µM, 3 h) and NIR light (700 ± 25 nm, 0.36-1.4 J /cm2) induced potent phototoxicity in both the cell lines. Under hypoxic conditions, PDT induced ~ 32% and 42% phototoxicity at LD50 and LD70 light dose, respectively, which corresponds to phototoxic dose under normoxia. CIPp-18 in neat buffer (pH 7.4) showed generation of singlet oxygen (1O2) as well as superoxide (O2·-) radicals. Studies on ROS generation in cells using fluorescence probes and the effect of mechanistic probes of 1O2 (Sodium Azide, Histidine, D2O) and free radicals (DMSO, Mannitol, Cyanocobalamin, SOD-PEG) on phototoxicity show that 1O2 plays major role in phototoxicity under normoxia. Whereas, under hypoxic conditions, PDT led to no significant generation of ROS and phototoxicity remained unaffected by cyanocobalamin, a quencher of O2·-. Moreover, CIPp-18 showed localization in cell membrane and PDT led to more pronounced loss of membrane permeability in cells under hypoxia than for normoxia. These results demonstrate that CIPp-18 is suitable for PDT of cancer cells under hypoxia and also suggest that phototoxicity under hypoxia is mediated via ROS-independent contact-dependent mechanism.

One Change, Many Benefits: A Glycine-Modified Bacteriochlorin with NIR Absorption and a Type I Photochemical Mechanism for Versatile Photodynamic Therapy

Difluorinated sulfonamide porphyrin (F2PGly) and bacteriochlorin (F2BGly), modified by glycine residues, were synthesized and evaluated for photodynamic therapy (PDT). F₂PGly exhibits superior stability and singlet oxygen generation efficiency but features a low-intensity band in the red range (λmax = 639 nm). In contrast, F2BGly shows a favorable, red-shifted absorption spectrum (λmax = 746 nm) that aligns well with phototherapeutic window, facilitating deeper tissue penetration. Moreover, it demonstrates reasonable photostability, necessary for the efficient generation of both singlet oxygen (type II) and oxygen-centered radicals (type I mechanism) which contributes to enhanced therapeutic efficacy. Importantly, the glycine modifications in F2BGly enhance its uptake in MCF-7 cells, known for their resistance to PDT due to efflux transport proteins like LAT1, showing great potential in the cancer cell-targeted PDT. The glycine groups potentially enable F2BGly to bypass these barriers, resulting in increased intracellular accumulation and more effective Reactive Oxygen Species (ROS) generation under illumination. In vivo studies indicated promising vascular-targeted PDT results, with real-time fluorescence imaging used to monitor photosensitizer distribution prior to irradiation. These findings suggest that F2BGly is a promising photosensitizer candidate with enhanced cancer cell selectivity and photodynamic efficiency, meriting further exploration in targeted PDT applications for multiple types of cancers.

Photodynamic Therapy for Oral Squamous Cell Carcinoma: Current Status, Challenges, and Prospects

Oral squamous cell carcinoma (OSCC) is the most prevalent and deadly malignancy of the head and neck. The standard treatments for OSCC are surgery, radiotherapy, and chemoradiotherapy, which can cause severe cosmetic and functional damage to the oral cavity and impair the patients' quality of life. Photodynamic therapy (PDT) is a promising alternative that uses light-activated photosensitizers to induce selective phototoxicity and necrosis in the target tissues. PDT has several advantages over conventional treatments, such as minimal invasion, low side effects, high selectivity and preservation of the oral function and appearance. This review explores the principles, mechanisms, and current applications of PDT for OSCC. We address the challenges, such as the depth of light penetration and tissue hypoxia, and underscore the progressive innovations in photosensitizer enhancement, nanotechnological integration, and precision therapy. The exploration of biomarkers for refining patient selection and tailoring individualized treatment regimens is also undertaken. PDT holds promise as a secure and efficacious modality for OSCC management. Nonetheless, additional investigation is imperative to refine treatment protocols and validate sustained therapeutic success.

Prostate-Specific Membrane Antigen-Targeted NIR Phototheranostics for Prostate Cancer

The evolution of targeted cancer theranostics has revolutionized personalized medicine by integrating diagnostic and therapeutic capabilities. Prostate-specific membrane antigen (PSMA) has emerged as a key theranostic target in the context of prostate cancer, paving the way for the clinical approval of multiple drugs. However, the persistent challenge of off-target toxicity, which plagues both conventional and advanced treatment modalities such as targeted chemotherapy and radiotherapy, thus demands further innovation. Considering this critical issue, this review discusses the recent advances in the binary treatment techniques, i.e., phototherapies, that have the potential to circumvent the key concern of off-target toxicity associated with personalized chemotherapy and radiotherapy. Precisely, an up-to-date overview of the latest developments in the near-infrared (NIR)-based phototheranostic strategies for prostate cancer by targeting PSMA has been presented. Furthermore, we have discussed the associated particulars that require specific attention in enhancing the translational potential of phototheranostic techniques.

Enhancing cancer immunotherapy with photodynamic therapy and nanoparticle: making tumor microenvironment hotter to make immunotherapeutic work better

Cancer immunotherapy has made tremendous advancements in treating various malignancies. The biggest hurdle to successful immunotherapy would be the immunosuppressive tumor microenvironment (TME) and low immunogenicity of cancer cells. To make immunotherapy successful, the 'cold' TME must be converted to 'hot' immunostimulatory status to activate residual host immune responses. To this end, the immunosuppressive equilibrium in TME should be broken, and immunogenic cancer cell death ought to be induced to stimulate tumor-killing immune cells appropriately. Photodynamic therapy (PDT) is an efficient way of inducing immunogenic cell death (ICD) of cancer cells and disrupting immune-restrictive tumor tissues. PDT would trigger a chain reaction that would make the TME 'hot' and have ICD-induced tumor antigens presented to immune cells. In principle, the strategic combination of PDT and immunotherapy would synergize to enhance therapeutic outcomes in many intractable tumors. Novel technologies employing nanocarriers were developed to deliver photosensitizers and immunotherapeutic to TME efficiently. New-generation nanomedicines have been developed for PDT immunotherapy in recent years, which will accelerate clinical applications.

GW4869 Can Inhibit Epithelial-Mesenchymal Transition and Extracellular HSP90α in Gefitinib-Sensitive NSCLC Cells

Objective

GW4869 is an exosomal inhibitor. It is necessary to delay the occurrence of gefitinib resistance during non-small-cell lung cancer (NSCLC) treatment. This study aimed to investigate the anti-tumor effects of GW4869 on epithelial-mesenchymal transition (EMT) and expression of extracellular heat shock protein 90α (eHSP90α) that contributes to acquired resisitance. Our study provides a new sight into the treatment of EGFR-mutated NSCLC.

Materials and Methods

We performed western blotting to detect levels of EMT and eHSP90α. Wound healing and transwell assays were performed to evaluate the behavioral dynamics of EMT. A nude mouse model of HCC827 was established in vivo.

Results

GW4869 inhibited the expression of eHSP90α, EMT, invasion and migration abilities of HCC827 and PC9. GW4869 enhanced sensitivity to gefitinib in BALB/c nude mice bearing tumors of HCC827.

Conclusion

These studies suggest that GW4869 can inhibit EMT and extracellular HSP90α, providing new strategies for enhancing gefitinib sensitivity in NSCLC.

MiR-182/Sestrin2 affects the function of asthmatic airway smooth muscle cells by the AMPK/mTOR pathway

Background and Objectives

Asthma is a chronic inflammatory airway disease and brings heavy economic and spiritual burdens to patients' families and the society. Airway smooth muscle cells (ASMCs) afect the development of asthma by secreting cytokines, growth factors, and prostates. The stress-inducing protein, Sestrin2, plays a vital role in antioxidant defense. The aim of this study is to investigate the role of Sestrin2 in asthma and its corresponding molecular mechanism.

Materials and Methods

Airway remodeling was induced by construction of asthma rat model. Primary ASMCs were isolated through combining tissue block adherence and enzymatic digestion and identified by immunofluorescence staining. Gene expression was measured by quantitative real-time PCR (qPCR) and western blot (WB) experiments. Cell viability, proliferation, migration, and calcium flow of ASMCs were measured by Cell Counting Kit-8 (CCK-8), 5-ethynyl-deoxyuridine (EdU), Transwell, and Fluo-3AM, respectively. The binding of miR-182 and Sestrin2 3'-untranslated region (3'-UTR) was measured by luciferase reporter system and RNA-binding protein immunoprecipitation (RIP) analysis.

Results

Sestrin2 expression was upregulated in asthma rat model and cell model. Overexpression of Sestrin2 enhanced the growth, migration, and calcium flow, and inversely, repression of Sestrin2 was reduced in ASMCs from the asthma group. MiR-182, one of the microRNAs (miRNAs) that possesses the potential to regulate Sestrin2, was downregulated in ASMCs from the asthma group. Further experiments revealed that Sestrin2 was inhibited by miR-182 and that overexpression of Sestrin2 reversed the miR-182-induced inhibition of the cellular progression of ASMCs from the asthma group. This study further investigated the downstream signaling pathway of Sestrin2 and found that increased expression of Sestrin2 activated 5'-adenosine monophosphate-activated protein kinase (AMPK), leading to the inactivation of mammalian target of rapamycin (mTOR) and thus promoting the growth, migration, and calcium flow of ASMCs from the asthma group.

Conclusion

This study investigated the role of Sestrin2 for the first time and further dissected the regulatory factor of Sestrin2, ultimately elucidating the downstream signaling pathway of Sestrin2 in asthma, providing a novel pathway, and improving the understanding of the development and progression of asthma.

Photodynamic therapy changes tumour immunogenicity and promotes immune-checkpoint blockade response, particularly when combined with micromechanical priming

Photodynamic therapy (PDT) with redaporfin stimulates colon carcinoma (CT26), breast (4T1) and melanoma (B16F10) cells to display high levels of CD80 molecules on their surfaces. CD80 overexpression amplifies immunogenicity because it increases same cell (cis) CD80:PD-L1 interactions, which (i) disrupt binding of T-cells PD-1 inhibitory receptors with their ligands (PD-L1) in tumour cells, and (ii) inhibit CTLA-4 inhibitory receptors binding to CD80 in tumour cells. In some cancer cells, redaporfin-PDT also increases CTLA-4 and PD-L1 expressions and virtuous combinations between PDT and immune-checkpoint blockers (ICB) depend on CD80/PD-L1 or CD80/CTLA-4 tumour overexpression ratios post-PDT. This was confirmed using anti-CTLA-4 + PDT combinations to increase survival of mice bearing CT26 tumours, and to regress lung metastases observed with bioluminescence in mice with orthotopic 4T1 tumours. However, the primary 4T1 responded poorly to treatments. Photoacoustic imaging revealed low infiltration of redaporfin in the tumour. Priming the primary tumour with high-intensity (~ 60 bar) photoacoustic waves generated with nanosecond-pulsed lasers and light-to-pressure transducers improved the response of 4T1 tumours to PDT. Penetration-resistant tumours require a combination of approaches to respond to treatments: tumour priming to facilitate drug infiltration, PDT for a strong local effect and a change in immunogenicity, and immunotherapy for a systemic effect.

Intestinal bacteria and colorectal cancer: etiology and treatment

The etiology of colorectal cancer (CRC) is influenced by bacterial communities that colonize the gastrointestinal tract. These microorganisms derive essential nutrients from indigestible dietary or host-derived compounds and activate molecular signaling pathways necessary for normal tissue and immune function. Associative and mechanistic studies have identified bacterial species whose presence may increase CRC risk, including notable examples such as Fusobacterium nucleatum, Enterotoxigenic Bacteroides fragilis, and pks+ E. coli. In recent years this work has expanded in scope to include aspects of host mutational status, intra-tumoral microbial heterogeneity, transient infection, and the cumulative influence of multiple carcinogenic bacteria after sequential or co-colonization. In this review, we will provide an updated overview of how host-bacteria interactions influence CRC development, how this knowledge may be utilized to diagnose or prevent CRC, and how the gut microbiome influences CRC treatment efficacy.

Redaporfin Development for Photodynamic Therapy and its Combination with Glycolysis Inhibitors

Photodynamic therapy (PDT) remains an underutilized treatment modality in oncology. Many efforts have been dedicated to the development of better photosensitizers, better formulations and delivery methods, rigorous planning of light dose distribution in tissues, mechanistic insight, improvement of treatment protocols and combinations with other therapeutic agents. Hopefully, progress in all these fields will eventually expand the use of PDT. Here we offer a brief review of our own contribution to the development of a photosensitizer for PDT - redaporfin - currently in Phase II clinical trials, and present data on its combination with two glycolysis inhibitors: 2-deoxyglucose and 3-bromopyruvate. We show that 3-bromopyruvate is more cytotoxic to a carcinoma cell line (CT26) than to a normal fibroblast (3T3) cell line, and that this selectivity is maintained in the in vitro combination with redaporfin-PDT. This combination was investigated in BALB/c mice with large subcutaneous CT26 tumors and it is shown that the cure rate in the combination is higher (33% cures) than in PDT (11% cures) or in 3-bromopyruvate (no cures) alone. The combination of redaporfin-PDT with 3-bromopyruvate illustrates the potential of combination therapies and how PDT benefits can be enhanced by systemic drugs with complementary targets.

Photodynamic properties of lysine and arginine derivatives of bacteriopurpurinimide

Background: O-propyloxime-N-propoxybacteriopurpurinimide methyl ester (3) is a near-infrared photosensitizer with confirmed in vivo anticancer activity. Methods: Conjugates of 3 with arginine (1) or lysine attached at an ε-amino group (2a) or α-amino group (2b) were studied as anticancer and antibacterial photosensitizers and compared with 3. Results: The new conjugates preserve advanced spectral characteristics of 3 and high singlet oxygen quantum yield. They demonstrated tenfold higher photocytotoxicity for cancer cells, due to their enhanced intracellular accumulation and altered localization. Though they showed threefold decreased antibacterial photodynamic effect compared with 3, they kill planktonic Staphylococcus aureus bacteria, and 1 destroys bacterial biofilms. Conclusion: Conjugates 1 and 2b are near-infrared photosensitizers with high anticancer and limited antibacterial activity.

Unraveling the Pivotal Role of Atropisomerism for Cellular Internalization

The intrinsic challenge of large molecules to cross the cell membrane and reach intracellular targets is a major obstacle for the development of new medicines. We report how rotation along a single C-C bond, between atropisomers of a drug in clinical trials, improves cell uptake and therapeutic efficacy. The atropisomers of redaporfin (a fluorinated sulfonamide bacteriochlorin photosensitizer of 1135 Da) are separable and display orders of magnitude differences in photodynamic efficacy that are directly related to their differential cellular uptake. We show that redaporfin atropisomer uptake is passive and only marginally affected by ATP depletion, plasma proteins, or formulation in micelles. The α₄ atropisomer, where meso-phenyl sulfonamide substituents are on the same side of the tetrapyrrole macrocycle, exhibits the highest cellular uptake and phototoxicity. This is the most amphipathic atropisomer with a conformation that optimizes hydrogen bonding (H-bonding) with polar head groups of membrane phospholipids. Consequently, α₄ binds to the phospholipids on the surface of the membrane, flips into the membrane to adopt the orientation of a surfactant, and eventually diffuses to the interior of the cell (bind-flip mechanism). We observed increased α₄ internalization by cells of the tumor microenvironment in vivo and correlated this to the response of photodynamic therapy when tumor illumination was performed 24 h after α₄ administration. These results show that properly orientated aryl sulfonamide groups can be incorporated into drug design as efficient cell-penetrating motifs in vivo and reveal the unexpected biological consequences of atropisomerism.

Two out of Three Musketeers Fight against Cancer: Synthesis, Physicochemical, and Biological Properties of Phosphino CuI, RuII, IrIII Complexes

Two novel phosphine ligands, Ph2PCH2N(CH2CH3)3 (1) and Ph2PCH2N(CH2CH2CH2CH3)2 (2), and six new metal (Cu(I), Ir(III) and Ru(II)) complexes with those ligands: iridium(III) complexes: Ir(η5-Cp*)Cl2(1) (1a), Ir(η5-Cp*)Cl2(2) (2a) (Cp*: Pentamethylcyclopentadienyl); ruthenium(II) complexes: Ru(η6-p-cymene)Cl2(1) (1b), Ru(η6-p-cymene)Cl2(2) (2b) and copper(I) complexes: [Cu(CH3CN)2(1)BF4] (1c), [Cu(CH3CN)2(2)BF4] (2c) were synthesized and characterized using elemental analysis, NMR spectroscopy, and ESI-MS spectrometry. Copper(I) complexes turned out to be highly unstable in the presence of atmospheric oxygen in contrast to ruthenium(II) and iridium(III) complexes. The studied Ru(II) and Ir(III) complexes exhibited promising cytotoxicity towards cancer cells in vitro with IC50 values significantly lower than that of the reference drug-cisplatin. Confocal microscopy analysis showed that Ru(II) and Ir(III) complexes effectively accumulate inside A549 cells with localization in cytoplasm and nuclei. A precise cytometric analysis provided clear evidence for the predominance of apoptosis in induced cell death. Furthermore, the complexes presumably induce the changes in the cell cycle leading to G2/M phase arrest in a dose-dependent manner. Gel electrophoresis experiments revealed that Ru(II) and Ir(III) inorganic compounds showed their unusual low genotoxicity towards plasmid DNA. Additionally, metal complexes were able to generate reactive oxygen species as a result of redox processes, proved by gel electrophoresis and cyclic voltamperometry. In vitro cytotoxicity assays were also carried out within multicellular tumor spheroids and efficient anticancer action on these 3D assemblies was demonstrated. It was proven that the hydrocarbon chain elongation of the phosphine ligand coordinated to the metal ions does not influence the cytotoxic effect of resulting complexes in contrast to metal ions type.

Photodynamic inactivation (PDI) as a promising alternative to current pharmaceuticals for the treatment of resistant microorganisms

Although the whole world is currently observing the global battle against COVID-19, it should not be underestimated that in the next 30 years, approximately 10 million people per year could be exposed to infections caused by multi-drug resistant bacteria. As new antibiotics come under pressure from unpredictable resistance patterns and relegation to last-line therapy, immediate action is needed to establish a radically different approach to countering resistant microorganisms. Among the most widely explored alternative methods for combating bacterial infections are metal complexes and nanoparticles, often in combination with light, but strategies using monoclonal antibodies and bacteriophages are increasingly gaining acceptance. Photodynamic inactivation (PDI) uses light and a dye termed a photosensitizer (PS) in the presence of oxygen to generate reactive oxygen species (ROS) in the field of illumination that eventually kill microorganisms. Over the past few years, hundreds of photomaterials have been investigated, seeking ideal strategies based either on single molecules (e.g., tetrapyrroles, metal complexes) or in combination with various delivery systems. The present work describes some of the most recent advances of PDI, focusing on the design of suitable photosensitizers, their formulations, and their potential to inactivate bacteria, viruses, and fungi. Particular attention is focused on the compounds and materials developed in our laboratories that are capable of killing in the exponential growth phase (up to seven logarithmic units) of bacteria without loss of efficacy or resistance, while being completely safe for human cells. Prospectively, PDI using these photomaterials could potentially cure infected wounds and oral infections caused by various multidrug-resistant bacteria. It is also possible to treat the surfaces of medical equipment with the materials described, in order to disinfect them with light, and reduce the risk of nosocomial infections.

Photodynamic therapy for treatment of bacterial keratitis

Microbial keratitis is the main cause of corneal opacification and the fourth leading cause of blindness worldwide, with bacteria the major infectious agent. Recently, bacterial keratitis has become a serious threat due to routine use of antibiotics leading to selection of resistant and multidrug-resistant bacteria strains. New approaches for treatment of bacterial keratitis are necessary to outcome the increasing antibiotic resistance. Antimicrobial photodynamic therapy is based on three agents: photosensitizer, oxygen, and light radiation. This therapy has been successful for treatment of infections in different tissues and organs as well as against different type of infectious agents and no resistance development. Also, new photosensitizers are being developed that has increased the spectrum of therapeutic protocols for treatment of a number of infectious diseases. Thus, antimicrobial photodynamic therapy has an extraordinary potential for treatment of those bacterial keratitis cases that actually are not solved by traditional antibiotic therapy.

Biodegradable Materials with Disulfide-Bridged-Framework Confine Photosensitizers for Enhanced Photo-Immunotherapy

Purpose

Photodynamic therapy (PDT) with spatiotemporal controlled and noninvasive advantages has obtained growing attention in cancer treatment. Nevertheless, PDT still suffers from self-aggregation-induced photosensitizer quenching and reactive oxygen species (ROS) scavenging in cancer cells with abundant glutathione (GSH) pools, leading to insufficient performance.

Methods

In this study, we develop a versatile nanocarrier (SSNs) with a disulfide-bond-bridged silica framework for enhanced photo-immunotherapy. Such SSNs spatially confine photosensitizers Ce6 in the matrix to prevent self-aggregation. Under the high GSH level of cancer cells, the disulfide-bond-bridged framework was degradable and triggered the exposure of photosensitizers to oxygen, accelerating the ROS generation during PDT. In addition, GSH depletion via the break of the disulfide-bond increased the ROS level, together resulting in efficient tumor killing outcomes with a considerable immunogenic cell death effect in vitro. Importantly, the SSNs@Ce6 accumulated in the tumor site and exhibited enhanced PDT efficacy with low systemic toxicity in vivo.

Results

The GEN-loaded nanoplatform (Ag-MONs@GEN) showed glutathione-responsive matrix degradation, resulting in the simultaneous controlled release of GEN and silver ions. Ag-MONs@GEN exhibited excellent anti-bacterial activities than Ag-MONs and GEN alone, especially enhancing synergetic effects against four antibiotic-resistant bacteria including Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Enterococcus faecalis. Moreover, Ag-MONs@GEN showed good biocompatibility on L929 and HUVECS.

Conclusion

Notably, SSNs@Ce6-mediated PDT completely eradicated 4T1 tumors when combined with the PD-1 checkpoint blockade. Overall, the confinement of photosensitizers in a biodegradable disulfide-bridged-framework provides a promising strategy to unleash the potential of photosensitizers in PDT, especially in combined cancer photo-immunotherapy.

Coordination Complexes as a New Generation Photosensitizer for Photodynamic Anticancer Therapy

Photodynamic therapy (PDT) has become an alternative to standard cancer treatment methods such as surgery, chemotherapy and radiotherapy. The uniqueness of this method relies on the possibility of using various photosensitizers (PS) that absorb and convert light emission in radical oxygen-derived species (ROS). They can be present alone or in the presence of other compounds such as metal organic frameworks (MOFs), non-tubules or polymers. The interaction between DNA and metal-based complexes plays a key role in the development of new anti-cancer drugs. The use of coordination compounds in PDT has a significant impact on the amount ROS generated, quantum emission efficiency (Φem) and phototoxic index (PI). In this review, we will attempt to systematically review the recent literature and analyze the coordination complexes used as PS in PDT. Finally, we compared the anticancer activities of individual coordination complexes and discuss future perspectives. So far, only a few articles link so many transition metal ion coordination complexes of varying degrees of oxidation, which is why this review is needed by the scientific community to further expand this field worldwide. Additionally, it serves as a convenient collection of important, up-to-date information.

The induction of immunogenic cell death by photodynamic therapy in B16F10 cells in vitro is effected by the concentration of the photosensitizer

Photodynamic therapy (PDT) can trigger immune responses against cancer cells. The induction of immunogenic cell death (ICD) is one of the possible mechanisms behind this event, but the protocol conditions necessary for a robust induction of ICD by PDT have not been defined. In this work, the immunogenicity of B16F10 melanoma cells treated with different PDT protocols was investigated. The exposure of damage-associated molecules (DAMPs), namely HMGB1, calreticulin and ATP, a hallmark of ICD, and the presence of apoptotic and necrotic cells were assessed after the application of PDT mediated by different concentrations of aluminum-phthalocyanine (AlPcNE) in vitro. Furthermore, the in vivo immunogenicity of PDT-treated B16F10 cells was investigated with an immunization-challenge model in C57BL/6 mice. The percentage of dead cells was directly proportional to the concentration of AlPcNE. The IC₅₀, IC₇₀ and IC₉₀ concentrations of AlPcNE induced the exposure of DAMPs by B16F10 cells after PDT. In the in vivo model, however, only the B16F10 cells treated with PDT-AlPcNE at the IC₅₀ or IC₇₀ rendered C57BL/6 significantly more resistant to a subsequent challenge with viable B16F10 cells. Thus, the induction of ICD in B16F10 cells by PDT occurs only at a specific range of AlPcNE concentrations.

Single-cell RNA sequencing reveals the mechanism of sonodynamic therapy combined with a RAS inhibitor in the setting of hepatocellular carcinoma

BACKGROUND

Ras activation is a frequent event in hepatocellular carcinoma (HCC). Combining a RAS inhibitor with traditional clinical therapeutics might be hampered by a variety of side effects, thus hindering further clinical translation. Herein, we report on integrating an IR820 nanocapsule-augmented sonodynamic therapy (SDT) with the RAS inhibitor farnesyl-thiosalicylic acid (FTS). Using cellular and tumor models, we demonstrate that combined nanocapsule-augmented SDT with FTS induces an anti-tumor effect, which not only inhibits tumor progression, and enables fluorescence imaging. To dissect the mechanism of a combined tumoricidal therapeutic strategy, we investigated the scRNA-seq transcriptional profiles of an HCC xenograft following treatment.

RESULTS

Integrative single-cell analysis identified several clusters that defined many corresponding differentially expressed genes, which provided a global view of cellular heterogeneity in HCC after combined SDT/FTS treatment. We conclude that the combination treatment suppressed HCC, and did so by inhibiting endothelial cells and a modulated immunity. Moreover, hepatic stellate secretes hepatocyte growth factor, which plays a key role in treating SDT combined FTS. By contrast, enrichment analysis estimated the functional roles of differentially expressed genes. The Gene Ontology terms "cadherin binding" and "cell adhesion molecule binding" and KEGG pathway "pathway in cancer" were significantly enriched by differentially expressed genes after combined SDT/FTS therapy.

CONCLUSIONS

Thus, some undefined mechanisms were revealed by scRNA-seq analysis. This report provides a novel proof-of-concept for combinatorial HCC-targeted therapeutics that is based on a non-invasive anti-tumor therapeutic strategy and a RAS inhibitor.

Osteoarticular infections: a specific program for older patients?

BACKGROUND

With the increasing number of elderly patients, arthroplasties, fractures and diabetic foot infections, the worldwide number of osteoarticular infections (OAI) among the elderly is concomitantly expected to rise.

AIMS

We explore existing scientific knowledge about OAI in the frail elderly population.

METHODS

We performed a literature search linking OAIs to geriatric patients and comparing elderly patients (> 65 years) with average adults (range 18-65 years).

RESULTS

In this literature, financial aspects, comparison of diverse therapies on quality of life, reimbursement policies, or specific guidelines or nursing recommendations are missing. Age itself was not an independent factor related to particular pathogens, prevention of OAI, nursing care, and outcomes of OAI. However, geriatric patients were significantly more exposed to adverse events of therapy. They had more co-morbidities and more conservative surgery for OAI.

CONCLUSION

Available literature regarding OAI management among elderly patients is sparse. In recent evaluations, age itself does not seem an independent factor related to particular epidemiology, pathogens, prevention, nursing care, rehabilitation and therapeutic outcomes of OAI. Future clinical research will concern more conservative surgical indications, but certainly reduce inappropriate antibiotic use.

Growing tool-kit of photosensitizers for clinical and non-clinical applications

Photosensitizers are photosensitive molecules utilized in clinical and non-clinical applications by taking advantage of light-mediated reactive oxygen generation, which triggers local and systemic cellular toxicity. Photosensitizers are used for diverse biological applications such as spatio-temporal inactivation of a protein in a living system by chromophore-assisted light inactivation, localized cell photoablation, photodynamic and immuno-photodynamic therapy, and correlative light-electron microscopy imaging. Substantial efforts have been made to develop several genetically encoded, chemically synthesized, and nanotechnologically driven photosensitizers for successful implementation in redox biology applications. Genetically encoded photosensitizers (GEPS) or reactive oxygen species (ROS) generating proteins have the advantage of using them in the living system since they can be manipulated by genetic engineering with a variety of target-specific genes for the precise spatio-temporal control of ROS generation. The GEPS variety is limited but is expanding with a variety of newly emerging GEPS proteins. Apart from GEPS, a large variety of chemically- and nanotechnologically-empowered photosensitizers have been developed with a major focus on photodynamic therapy-based cancer treatment alone or in combination with pre-existing treatment methods. Recently, immuno-photodynamic therapy has emerged as an effective cancer treatment method using smartly designed photosensitizers to initiate and engage the patient's immune system so as to empower the photosensitizing effect. In this review, we have discussed various types of photosensitizers, their clinical and non-clinical applications, and implementation toward intelligent efficacy, ROS efficiency, and target specificity in biological systems.

Photodynamic Inactivation of Bacteria with Porphyrin Derivatives: Effect of Charge, Lipophilicity, ROS Generation, and Cellular Uptake on Their Biological Activity In Vitro

Resistance of microorganisms to antibiotics has led to research on various therapeutic strategies with different mechanisms of action, including photodynamic inactivation (PDI). In this work, we evaluated a cationic, neutral, and anionic meso-tetraphenylporphyrin derivative’s ability to inactivate the Gram-negative and Gram-positive bacteria in a planktonic suspension under blue light irradiation. The spectroscopic, physicochemical, redox properties, as well as reactive oxygen species (ROS) generation capacity by a set of photosensitizers varying in lipophilicity were investigated. The theoretical calculations were performed to explain the distribution of the molecular charges in the evaluated compounds. Moreover, logP partition coefficients, cellular uptake, and phototoxicity of the photosensitizers towards bacteria were determined. The role of a specific microbial efflux pump inhibitor, verapamil hydrochloride, in PDI was also studied. The results showed that E. coli exhibited higher resistance to PDI than S. aureus (3–5 logs) with low light doses (1–10 J/cm²). In turn, the prolongation of irradiation (up to 100 J/cm²) remarkably improved the inactivation of pathogens (up to 7 logs) and revealed the importance of photosensitizer photostability. The PDI potentiation occurs after the addition of KI (more than 3 logs extra killing). Verapamil increased the uptake of photosensitizers (especially in E. coli) due to efflux pump inhibition. This effect suggests that PDI is mediated by ROS, the electrostatic charge interaction, and the efflux of photosensitizers (PSs) regulated by multidrug-resistance (MDR) systems. Thus, MDR inhibition combined with PDI gives opportunities to treat more resistant bacteria.

Antibacterial Photodynamic Treatment of Porphyromonas gingivalis with Toluidine Blue O and a NonLaser Red Light Source Enhanced by Dihydroartemisinin

In vitro experiments confirmed that antibacterial photodynamic treatment (aPDT) inactivates periodontal pathogens. However, more effective sterilization is needed in the complex oral environment. This study tested whether dihydroartemisinin (DHA) enhanced the photokilling effect of aPDT on Porphyromonas gingivalis (P. gingivalis) in planktonic and biofilm states. aPDT combining toluidine blue O (TBO) with 630 nm red light was performed on bacterial suspensions and biofilms in vitro with different final concentrations of DHA (10, 20 and 40 μg mL^-1 ). The sensitization mechanism was preliminarily investigated by uptake experiments. The above experiments were repeated with different incubation times (30, 60, 120 s). Porphyromonas gingivalis biofilms exhibited significantly higher resistance to aPDT than P. gingivalis in suspension under the same experimental parameters. DHA alone had no cytotoxic effect on P. gingivalis with or without light irradiation. In either bacterial suspensions or biofilms, DHA concentration-dependently enhanced the photokilling effect of aPDT and increased TBO uptake by P. gingivalis. Prolonged incubation time enhanced the photokilling efficiency of aPDT until cellular TBO uptake reached saturation. DHA can enhance aPDT activity against P. gingivalis in planktonic and biofilm states. DHA also accelerated TBO uptake, reducing incubation time.

Recent advances in strategies for overcoming hypoxia in photodynamic therapy of cancer

The selectivity of photodynamic therapy (PDT) derived from the tailored accumulation of photosensitizing drug (photosensitizer; PS) in the tumor microenvironment (TME), and from local irradiation, turns it into a "magic bullet" for the treatment of resistant tumors without sparing the healthy tissue and possible adverse effects. However, locally-induced hypoxia is one of the undesirable consequences of PDT, which may contribute to the emergence of resistance and significantly reduce therapeutic outcomes. Therefore, the development of strategies using new approaches in nanotechnology and molecular biology can offer an increased opportunity to eliminate the disadvantages of hypoxia. Emerging evidence indicates that wisely designed phototherapeutic procedures, including: (i) ROS-tunable photosensitizers, (ii) organelle targeting, (iii) nano-based photoactive drugs and/or PS delivery nanosystems, as well as (iv) combining them with other strategies (i.e. PTT, chemotherapy, theranostics or the design of dual anticancer drug and photosensitizers) can significantly improve the PDT efficacy and overcome the resistance. This mini-review addresses the role of hypoxia and hypoxia-related molecular mechanisms of the HIF-1α pathway in the regulation of PDT efficacy. It also discusses the most recent achievements as well as future perspectives and potential challenges of PDT application against hypoxic tumors.

Enhanced Cellular Uptake and Photodynamic Effect with Amphiphilic Fluorinated Porphyrins: The Role of Sulfoester Groups and the Nature of Reactive Oxygen Species

A class of amphiphilic photosensitizers for photodynamic therapy (PDT) was developed. Sulfonate esters of modified porphyrins bearing-F substituents in the ortho positions of the phenyl rings have adequate properties for PDT, including absorption in the red, increased cellular uptake, favorable intracellular localization, low cytotoxicity, and high phototoxicity against A549 (human lung adenocarcinoma) and CT26 (murine colon carcinoma) cells. Moreover, the role of type I and type II photochemical processes was assessed by fluorescent probes specific for various reactive oxygen species (ROS). The photodynamic effect is improved not only by enhanced cellular uptake but also by the high generation of both singlet oxygen and oxygen-centered radicals. All of the presented results support the idea that the rational design of photosensitizers for PDT can be further improved by better understanding the determinants affecting its therapeutic efficiency and explain how smart structural modifications can make them suitable photosensitizers for application in PDT.

Immune Responses after Vascular Photodynamic Therapy with Redaporfin

Photodynamic therapy (PDT) relies on the administration of a photosensitizer (PS) that is activated, after a certain drug-to-light interval (DLI), by the irradiation of the target tumour with light of a specific wavelength absorbed by the PS. Typically, low light doses are insufficient to eradicate solid tumours and high fluence rates have been described as poorly immunogenic. However, previous work with mice bearing CT26 tumours demonstrated that vascular PDT with redaporfin, using a low light dose delivered at a high fluence rate, not only destroys the primary tumour but also reduces the formation of metastasis, thus suggesting anti-tumour immunity. This work characterizes immune responses triggered by redaporfin-PDT in mice bearing CT26 tumours. Our results demonstrate that vascular-PDT leads to a strong neutrophilia (2-24 h), systemic increase of IL-6 (24 h), increased percentage of CD4⁺ and CD8⁺ T cells producing IFN-γ or CD69⁺ (2-24 h) and increased CD4⁺/CD8⁺ T cell ratio (2-24 h). At the tumour bed, T cell tumour infiltration disappeared after PDT but reappeared with a much higher incidence one day later. In addition, it is shown that the therapeutic effect of redaporfin-PDT is highly dependent on neutrophils and CD8⁺ T cells but not on CD4⁺ T cells.