Chlamydia trachomatis causes sexually transmitted infections that target reproductive organs. In 2010, over one million chlamydial infections were reported to the Centers for Disease Control. However, the actual count is probably higher because many people living with Chlamydia are often unaware of their infections. ack to Top
Azithromycin is the most common antibiotic treatment today for acute chlamydial infections. Unfortunately, when Chlamydiae deviate from their regular development cycle and enter a reversible state called persistence, the pathogen becomes incredibly resilient to antibiotics. Furthermore, persistent infections are also associated with other serious complications such as reactive arthritis and pelvic inflammatory disease. By unknown mechanisms, persistent Chlamydiae can wake from the persistent state and revert back to an actively infectious state; thus, knowledge about antibiotic efficacy on infections recovering from persistence is critical for designing improved drug treatments. This study explores the use of folate-targeted, biodegradable poly(lactide-co-glycolide) (PLGA) nanoparticles as improved anti-chlamydial drug delivery systems. Folate-conjugated nanodevices have already been utilized for the targeted delivery of therapeutic and imaging agents to cells with over-expressed folate receptors such as cancer cells or inflammatory cells of arthritis patients. A cell culture model was used to compare the efficacy of targeted folate-functionalized mPEG-PLGA-Nanoparticles (FA-NP Combo) to non-targeted mPEG-PLGA-Nanoparticles (NP Combo) for delivering Azithromycin (AZ) and Rifampicin (RIF) drug combos to chlamydial infections which have up-regulated folate receptor expression. A third treatment consisting of free AZ and RIF combo (Free Combo) was also conducted in parallel to the nanoparticle treatments. Cells were infected with C. trachomatis (serovar K/UW-31) and serial dilutions of FA-NP, NP, or Free Combo drugs were added to duplicate wells. In order to induce persistent infection, Penicillin G was added to the infection medium. Morphological analyses consisting of chlamydial inclusion size and inclusion counts were then used to assess viability of Chlamydiae recovering from persistence after drug treatment. Results showed infections treated with FA-NP Combo had significantly less chlamydial inclusions compared to cells pulsed with non-targeting NP Combo or Free Combo drugs. Furthermore, 2-D analyses of FA-NP Combo treatment group also showed significantly smaller chlamydial inclusion sizes. Building upon morphological analyses, transcript levels of key genes associated with chlamydial viability (16s Ribosomal RNA primary transcripts) were assessed using RT-qPCR after acutely or persistently infected cells were treated with FA-NP, NP or Free Combo drugs. In these experiments, FA-NP Combo outperformed its non-targeted counterparts and reduced 16s rRNA primary transcripts by statistically greater amounts. Together with this set of combined results, this project demonstrates molecularly the improved efficacy of folate-functionalized nanoparticles for targeted combination antibiotic delivery to acute and persistent infections. Furthermore, morphological data on targeted nanoparticles’ improved therapeutic effect on infections recovering from persistence unlocks new knowledge on targeted nanoparticle performance during a phase of the chlamydial developmental cycle that is little understood by the scientific community.
Lin, Tayson. "Folate-Functionalized Nanoparticles for Targeted Anti-Chlamydial Drug Delivery." 2013 NCUR (2013).