The overall objective of this revised second competitive renewal is to continue our investigations on the role of photodynamic therapy (PDT) in treating localized infections. PDT employs non-toxic photosensitizers (PS) and harmless visible light (frequently red light for increased tissue penetration) that combine in the presence f oxygen to produce reactive oxygen species that damage biological molecules such as proteins, lipids and nucleic acids and subsequently cause cell death. In the two funding periods of this grant we have synthesized and characterized several novel highly active antimicrobial PS and demonstrated their effectiveness in treating mouse models of infected wounds, burns and abscesses. In some cases PDT can save mice from a certain death due to sepsis that develops from an untreated localized infection. A combination of the appropriate molecular design of the PS, together with topical or local application of the PS to the infected area and a short drug-ligh interval allows high selectivity for microbial cells compared to the surrounding host cells. The broad motivation for this line of research is the relentless worldwide increase in antibiotic resistance amongst pathogenic microbes, and it has been found that multi-antibiotic resistant strains are in general as sensitive to photodynamic inactivation (PDI) as na?ve strains, and moreover that microbial cells are unable to develop resistance to PDI.
Aim 1 will explore a finding that the clinically approved PS, methylene blue and related penothiazinium salts could have their antimicrobial PDT effect potentiated by addition of simple ions like iodide. While we initially interpreted this to involve electron transfer (oxidation) from hydroxyl radicals, we have now discovered that we can still get killing in the absence of oxygen. In addition to studying the contribution of Type 1 and Type 2 photochemical mechanisms we are now investigating a possible mechanism involving direct oxidation of iodide (and azide) anions by excited state MB to produce iodide/azide radicals that efficiently kill microbial cells.
Aim 2 proposes a solution t the biggest barrier to the effectiveness of antimicrobial PDT in vivo i. e. delivering the photosensitizer (PS) into the infected tissue. Since all highly effective antimicrobial PS have cationic charges they are ideally suited for delivery into tissue by electricity. We will explore te use of iontophoresis and electroporation singly and in combination to deliver antimicrobial PS (and iodide) into ex vivo pigskin and into hairless mouse skin.
Aim 3 responds to the reviewers'criticisms by exploring the combination of PDT with traditional systemic antibiotics to prevent regrowth of bacteria after PDT. Preliminary data has shown that a sub-therapeutic regimen of tobramycin can synergistically combine with a PDT regimen mediated by a fullerene and white light to save mice from dying in a Pseudomonas wound infection model. We will study possible synergy in vitro using MIC determinations with PDT and/or antibiotics In aim 4 in response to the reviewers'criticisms we will study selectivity for killing microbial cells (both fungi and bacteria) over mammalian skin cells (both mouse and human) and look at possible damage in tissue removed from mice. We have found some highly effective antifungal PS and will study these in vitro and in vivo with emphasis on selectivity. We now have access to Candida albicans that has been genetically engineered to express Gaussia princeps luciferase and Aspergillus fumigates expressing firefly luciferase that form localized infections that can be imaged by bioluminescence imaging.

Public Health Relevance

The relentless worldwide increase in antibiotic resistance amongst pathogenic microbes necessitates development of alternative approaches to treat stubborn localized infections. Photodynamic therapy is becoming more often clinically used in diseases such as periodontitis, sinusitis, endodontics, and prevention of pneumonia. Knowledge gained from the successful completion of this current proposal could be introduced into clinical practice for burns and orthopedic infections relatively rapidly.

National Institute of Health (NIH)
National Institute of Allergy and Infectious Diseases (NIAID)
Research Project (R01)
Project #
Application #
Study Section
Special Emphasis Panel (ZRG1-DDR-T (09))
Program Officer
Huntley, Clayton C
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
Massachusetts General Hospital
United States
Zip Code
Ferraresi, Cleber; Bertucci, Danilo; Schiavinato, Josiane et al. (2018) Reply to the Letter to the Editor on ""Effects of Light-Emitting Diode Therapy on Muscle Hypertrophy, Gene Expression, Performance, Damage, and Delayed-Onset Muscle Soreness: Case-Control Study With a Pair of Identical Twins"". Am J Phys Med Rehabil 97:e2-e5
Ramos, Loyanne C B; Rodrigues, Fernando P; Biazzotto, Juliana C et al. (2018) Targeting the mitochondrial VDAC in hepatocellular carcinoma using a polyclonal antibody-conjugated to a nitrosyl ruthenium complex. J Biol Inorg Chem 23:903-916
Huang, Liyi; Xuan, Weijun; Zadlo, Andrzej et al. (2018) Antimicrobial photodynamic inactivation is potentiated by the addition of selenocyanate: Possible involvement of selenocyanogen? J Biophotonics 11:e201800029
Huang, Ying-Ying; Wintner, Anton; Seed, Patrick C et al. (2018) Antimicrobial photodynamic therapy mediated by methylene blue and potassium iodide to treat urinary tract infection in a female rat model. Sci Rep 8:7257
Narita, Kouji; Asano, Krisana; Morimoto, Yukihiro et al. (2018) Corrigendum to ""Disinfection and healing effects of 222-nm UVC light on methicillin-resistant Staphylococcus aureus infection in mouse wounds"" [J. Photochem. Photobiol. B Biol. 178 (January 2018) 10-18]. J Photochem Photobiol B 182:146
Tatmatsu-Rocha, José Carlos; Tim, Carla Roberta; Avo, Lucimar et al. (2018) Mitochondrial dynamics (fission and fusion) and collagen production in a rat model of diabetic wound healing treated by photobiomodulation: comparison of 904?nm laser and 850?nm light-emitting diode (LED). J Photochem Photobiol B 187:41-47
Farjadian, Fatemeh; Moghoofei, Mohsen; Mirkiani, Soroush et al. (2018) Bacterial components as naturally inspired nano-carriers for drug/gene delivery and immunization: Set the bugs to work? Biotechnol Adv 36:968-985
Hamblin, Michael R (2018) Upconversion in photodynamic therapy: plumbing the depths. Dalton Trans 47:8571-8580
Hamblin, Michael R (2018) Photobiomodulation for traumatic brain injury and stroke. J Neurosci Res 96:731-743
Salehpour, Farzad; Mahmoudi, Javad; Kamari, Farzin et al. (2018) Brain Photobiomodulation Therapy: a Narrative Review. Mol Neurobiol 55:6601-6636

Showing the most recent 10 out of 348 publications