Immune response after photodynamic therapy increases anti-cancer and anti-bacterial effects

Abstract

Photodynamic therapy (PDT) is a clinically approved procedure for treatment of cancer and infections. PDT involves systemic or topical administration of a photosensitizer (PS), followed by irradiation of the diseased area with light of a wavelength corresponding to an absorbance band of the PS. In the presence of oxygen, a photochemical reaction is initiated, leading to the generation of reactive oxygen species and cell death. Besides causing direct cytotoxic effects on illuminated tumor cells, PDT is known to cause damage to the tumor vasculature and induce the release of pro-inflammatory molecules. Pre-clinical and clinical studies have demonstrated that PDT is capable of affecting both the innate and adaptive arms of the immune system. Immune stimulatory properties of PDT may increase its beneficial effects giving the therapy wider potential to become more extensively used in clinical practice. Be sides stimulating tumor-specific cytotoxic T-cells capable to destroy distant untreated tumor cells, PDT leads to development of anti-tumor memory immunity that can potentially prevent the recurrence of cancer. The immunological effects of PDT make the therapy more effective also when used for treatment of bacterial infections, due to an augmented infiltration of neutrophils into the infected regions that seems to potentiate the outcome of the treatment.

Engineering of relevant photodynamic processes through structural modifications of metallotetrapyrrolic photosensitizers

“…As mentioned in the Introduction, PDT elicits a strong, acute inflammatory response that can activate immune system and induce long-term antitumor response [1,2,273]. The insult mediated by oxidative stress at the targeted tissue triggers a complex multifactorial response engaging host defense mechanisms associated with the inflammatory process that participate in the eradication of the treated tumor and involve many elements of the innate and adaptive immune systems [5,21,22,28,274,275].…”

Photodynamic therapy in colorectal cancer treatment—The state of the art in preclinical research

“…The immunomodulatory effect is one of the main mechanisms of the action of photodynamic method [117]. Experimental photoimmunotherapy of hepatic metastases from CRC in the mouse model with intravenously administered polyanionic 17.1A Ce6 conjugates at a dose of 0.25 mg/kg and irradiation with red light was delivered into the liver tumor by an interstitial fiber.…”

Tumor-Specific Immune Response After Photodynamic Therapy

“…Иммуностимулирующие свойства ФДТ могут увеличить свои положи-тельные эффекты терапии и дать более широкий потенциал для применения в клинической прак-тике. Стимулируя опухоль-специфичные цито-токсические Т-клетки, способные уничтожать отдаленные необработанные опухолевые клетки, ФДТ приводит к развитию противоопухолевых клеток памяти, которые потенциально могут пре-дотвратить рецидив рака [55]. Применение цито-кинов способно стимулировать иммунный ответ на воздействие ФДТ [53].…”