Targeted antimicrobial photochemotherapy.
This study explores a new approach for antimicrobial therapy with light activation of targeted poly-L-lysine (pL)-chlorin e6 (ce6) conjugates. The goal was to test the hypothesis that these conjugates between pL and ce6 would efficiently target photodestruction towards gram-positive (Actinomyces viscosus) and gram-negative (Porphyromonas gingivalis) oral species while sparing an oral epithelial cell line (HCPC-1). Conjugates of ce6 with pL (average molecular weight, 2,000) having a positive, neutral, or negative charge were prepared. Illumination with red light (lambdamax = 671 nm) from a diode array produced a dose-dependent loss of CFU from the bacteria, under conditions that did not affect the viability of the epithelial cells. For P. gingivalis, the cationic conjugate produced 99% killing, while the neutral conjugate killed 91% and the anionic conjugate killed 76% after 1 min of incubation and exposure to red light for 10 min. For A. viscosus, the cationic conjugate produced >99.99% killing while HCPC-1 cells remained intact. The importance of the positive charge was shown by the effectiveness of ce6-monoethylenediamine monoamide (a monocationic derivative of ce6) in killing both bacteria. The clinically employed benzoporphyrin derivative under the same conditions killed epithelial cells while leaving P. gingivalis relatively unharmed. A mixture of ce6 with pL did not show phototoxicity comparable with that of the cationic conjugate. These results were explained by the selective uptake of the conjugates by bacteria (20- to 100-fold) compared to that by mammalian cells, while free ce6 showed much less selectivity for bacteria (5- to 20-fold). The data suggest that the cationic pL-ce6 conjugate may have an application for the photodynamic therapy of periodontal disease.
Soukos
N S
NS
Wellman Laboratories of Photomedicine, Department of Dermatology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114-2698, USA.
Ximenez-Fyvie
L A
LA
Hamblin
M R
MR
Socransky
S S
SS
Hasan
T
T
D000818:Animals; D001419:Bacteria / Q000187:drug effects*; D002460:Cell Line; D002735:Chlorophyllides; D006224:Cricetinae; D009055:Mouth / Q000382:microbiology; D010510:Periodontal Diseases / Q000188:drug therapy*; D010778:Photochemotherapy; D011107:Polylysine / Q000008:administration & dosage*; D011166:Porphyrins / Q000008:administration & dosage* / Q000493:pharmacokinetics
D002735:Chlorophyllides; D011166:Porphyrins; D011107:Polylysine; C062985:phytochlorin