Influence of Intra-articular Neutrophils on the Effects of Photodynamic Therapy for Murine MRSA Arthritis |
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| Authors: | Masamitsu Tanaka Manabu Kinoshita Yasuo Yoshihara Nariyoshi Shinomiya Shuhji Seki Koichi Nemoto Yuji Morimoto |
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| Affiliation: | 1. Department of Orthopaedic Surgery, National Defense Medical College, Namiki, Tokorozawa, Japan;2. Department of Immunology and Microbiology, National Defense Medical College, Namiki, Tokorozawa, Japan;3. Department of Integrative Physiology and Bio-Nano Medicine, National Defense Medical College, Namiki, Tokorozawa, Japan |
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| Abstract: | Although there have been some reports about the cytotoxic effects of photodynamic therapy (PDT) on multidrug-resistant bacteria, there have been few reports in which favorable results of PDT on a local infection site are described. This study aimed to verify the hypothesis that the low efficacy of PDT on a local infection site is due to the cytotoxic effect of PDT on leukocytes. PDT using Photofrin® exerted significant cytotoxicity for cultured methicillin-resistant Staphylococcus aureus (MRSA). Nevertheless, this therapeutic modality was not effective for a murine MRSA arthritis model. Approximately 30% of intra-articular leukocytes, mainly neutrophils, died immediately after PDT, and a further decrease in the number of intra-articular leukocytes and atrophy of the synovial tissue were seen 24 h after PDT. Isolated peripheral neutrophils showed significant affinity for Photofrin® and showed significant morphological damage, resulting in cell death, when they were subject to PDT using Photofrin®. These results indicate that intra-articular neutrophils have an influence on the effects of PDT for MRSA arthritis. |
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