The secretome of immune cells is currently a major focus in both diagnostic and therapeutic contexts. Cell-free therapeutic agents attract even more attention in cancer immunotherapy research, as their properties are comparable to, and sometimes surpass, those of cell-based immunotherapy. This is particularly evident when dendritic cell-based vaccines are compared with dendritic cell-derived exosomes (dexosomes). However, there is still significant potential for further research and optimization. We propose incorporating immunogenic cell death stimuli into the production of dendritic cell-derived exosomes in order to improve their effectiveness as a cell-free anti-cancer treatment. In this review, we suggest a new strategy to enhance the immunogenic potential of dexosomes, as well as summarize and compare immunogenic proprieties of dendritic cells and dendritic cells-derived exosomes as anti-cancer agents.

Research in the past decade on immunogenic cell death (ICD) has shown that the immunogenicity of dying tumor cells is crucial for effective anticancer therapy. ICD induction leads to the emission of specific damage-associated molecular patterns (DAMPs), which act as danger signals and as adjuvants to activate specific anti-tumor immune responses, leading to the elimination of tumor cells and the formation of long-term immunological memory. ICD can be triggered by many anticancer treatment modalities, including photodynamic therapy (PDT). However, due to the variety of photosensitizers used and the lack of a universally adopted PDT protocol, there is a need to develop novel PDT with a proven ICD capability. In the present study, we characterized the abilities of two photoactive dyes to induce ICD in experimental glioma in vitro and in vivo. One dye was from the tetracyanotetra(aryl)porphyrazine group with 9-phenanthrenyl (pz I), and the other was from the 4-(4-fluorobenzyoxy)phenyl (pz III) group in the aryl frame of the macrocycle. We showed that after the photosensitizers penetrated into murine glioma GL261 cells, they localized predominantly in the Golgi apparatus and partially in the endoplasmic reticulum, providing efficient phototoxic activity against glioma GL261 cells upon light irradiation at a dose of 20 J/cm² (λex 630 nm; 20 mW/cm²). We demonstrated that pz I-PDT and pz III-PDT can act as efficient ICD inducers when applied to glioma GL261 cells, facilitating the release of two crucial DAMPs (ATP and HMGB1). Moreover, glioma GL261 cells stimulated with pz I-PDT or pz III-PDT provided strong protection against tumor growth in a prophylactic subcutaneous glioma vaccination model. Finally, we showed that dendritic cell (DC) vaccines pulsed with the lysates of glioma GL261 cells pre-treated with pz-I-PDT or pz-III-PDT could act as effective inducers of adaptive anti-tumor immunity in an intracranial orthotopic glioma mouse model.

Approximately 30% of glioma patients are able to survive beyond one year postdiagnosis. And this short time is often overshadowed by glioma-associated epilepsy. This condition severely impairs the patient’s quality of life and causes great suffering. The genetic, molecular and cellular mechanisms underlying tumour development and epileptogenesis remain incompletely understood, leading to numerous unanswered questions. The various types of gliomas, namely glioblastoma, astrocytoma and oligodendroglioma, demonstrate distinct seizure susceptibility and disease progression patterns. Patterns have been identified in the presence of IDH mutations and epilepsy, with tumour location in cortical regions, particularly the frontal lobe, showing a more frequent association with seizures. Altered expression of TP53, MGMT and VIM is frequently detected in tumour cells from individuals with epilepsy associated with glioma. However, understanding the pathogenesis of these modifications poses a challenge. Moreover, hypoxic effects induced by glioma and associated with the HIF-1a factor may have a significant impact on epileptogenesis, potentially resulting in epileptiform activity within neuronal networks. We additionally hypothesise about how the tumour may affect the functioning of neuronal ion channels and contribute to disruptions in the blood–brain barrier resulting in spontaneous depolarisations.

The development of cancer immunotherapies provides hope to millions of patients for better clinical outcomes after tumor treatment. Thus, investigating the fundamental mechanisms of antitumor immunity activation is an urgent task. Numerous studies have outlined the effect of immunogenic cell death (ICD) on cancer cells, and this outcome is both sophisticated and simple. Different stimuli can cause ICD; however, photodynamic exposure has been proven to be an effective inducer of programed death on par with radiotherapy. The link between triggering a photodynamic response in cancer cells and triggering ICD has been poorly described in experimental works. The question of which molecular cascades are activated after photodynamic therapy (PDT) irradiation and the way damage-associated molecular patterns (DAMPs) are released is intriguing. Much is known about reactive oxygen species generation and endoplasmic reticulum stress but little about the Golgi apparatus. Photosensitizers of different types can exert different effects, including completely nonimmunogenic ones. This review describes the cascades that link the induction of cell death by photodynamic exposure and the immunogenic pattern of DAMP release. The photosensitizers that have shown potential as ICD inducers and the different pathways of programed death that occur during PDT exposure are also discussed.

Efficacy of antitumor vaccines based on photoinduced GL261 glioma cells using photosensitizers from the group of tetra(aryl)tetracyanoporphyrases with different aryl substituents Оценка эффективности противоопухолевых вакцинаций на основе фотоиндуцированных клеток глиомы GL261 с применением фотосенсебилизаторов из группы тетра(арил)тетрацианопорфиразнов с разными арильными заместителями