title: Activated T cells exhibit increased uptake of silicon phthalocyanine Pc 4 and increased susceptibility to Pc 4-photodynamic therapy-mediated cell death.
abstract: Photodynamic therapy (PDT) is an emerging treatment for malignant and inflammatory dermal disorders. Photoirradiation of the silicon phthalocyanine (Pc) 4 photosensitizer with red light generates singlet oxygen and other reactive oxygen species to induce cell death. We previously reported that Pc 4-PDT elicited cell death in lymphoid-derived (Jurkat) and epithelial-derived (A431) cell lines in vitro, and furthermore that Jurkat cells were more sensitive than A431 cells to treatment. In this study, we examined the effectiveness of Pc 4-PDT on primary human CD3(+) T cells in vitro. Fluorometric analyses of lysed T cells confirmed the dose-dependent uptake of Pc 4 in non-stimulated and stimulated T cells. Flow cytometric analyses measuring annexin V and propidium iodide (PI) demonstrated a dose-dependent increase of T cell apoptosis (6.6-59.9%) at Pc 4 doses ranging from 0-300 nM. Following T cell stimulation through the T cell receptor using a combination of anti-CD3 and anti-CD28 antibodies, activated T cells exhibited increased susceptibility to Pc 4-PDT-induced apoptosis (10.6-81.2%) as determined by Pc 4 fluorescence in each cell, in both non-stimulated and stimulated T cells, Pc 4 uptake increased with Pc 4 dose up to 300 nM as assessed by flow cytometry. The mean fluorescence intensity (MFI) of Pc 4 uptake measured in stimulated T cells was significantly increased over the uptake of resting T cells at each dose of Pc 4 tested (50, 100, 150 and 300 nM, p < 0.001 between 50 and 150 nM, n = 8). Treg uptake was diminished relative to other T cells. Cutaneous T cell lymphoma (CTCL) T cells appeared to take up somewhat more Pc 4 than normal resting T cells at 100 and 150 nm Pc 4. Confocal imaging revealed that Pc 4 localized in cytoplasmic organelles, with approximately half of the Pc 4 co-localized with mitochondria in T cells. Thus, Pc 4-PDT exerts an enhanced apoptotic effect on activated CD3(+) T cells that may be exploited in targeting T cell-mediated skin diseases, such as cutaneous T cell lymphoma (CTCL) or psoriasis.
authors.affiliation: Department of Dermatology, Case Western Reserve University, University Hospitals Case Medical Center, Cleveland, OH, USA. tsm4@case.edu.
authors.forename: David C
authors.initials: DC
authors.lastname: Soler
authors.forename: Jennifer
authors.initials: J
authors.lastname: Ohtola
authors.forename: Hideaki
authors.initials: H
authors.lastname: Sugiyama
authors.forename: Myriam E
authors.initials: ME
authors.lastname: Rodriguez
authors.forename: Ling
authors.initials: L
authors.lastname: Han
authors.forename: Nancy L
authors.initials: NL
authors.lastname: Oleinick
authors.forename: Minh
authors.initials: M
authors.lastname: Lam
authors.forename: Elma D
authors.initials: ED
authors.lastname: Baron
authors.forename: Kevin D
authors.initials: KD
authors.lastname: Cooper
authors.forename: Thomas S
authors.initials: TS
authors.lastname: McCormick
mesh_terms: D017304:Annexin A5 / Q000378:metabolism; D017209:Apoptosis / Q000187:drug effects; D001323:Autoantibodies / Q000008:administration & dosage; D018106:CD28 Antigens / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D006801:Humans; D007211:Indoles / Q000493:pharmacokinetics / Q000494:pharmacology*; D016410:Lymphoma, T-Cell, Cutaneous / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D010778:Photochemotherapy / Q000379:methods; D017319:Photosensitizing Agents / Q000493:pharmacokinetics / Q000494:pharmacology*; D019408:Platelet Endothelial Cell Adhesion Molecule-1 / Q000378:metabolism; D011419:Propidium / Q000378:metabolism; D012878:Skin Neoplasms / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology; D013601:T-Lymphocytes / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology
chemical_list: D017304:Annexin A5; D001323:Autoantibodies; D018106:CD28 Antigens; D007211:Indoles; D017319:Photosensitizing Agents; D019408:Platelet Endothelial Cell Adhesion Molecule-1; C107448:phthalocyanine Pc 4; D011419:Propidium