title: Inhibition of bacterial growth and intramniotic infection in a guinea pig model of chorioamnionitis using PAMAM dendrimers.
abstract: Dendrimers have emerged as topical microbicides to treat vaginal infections. This study explores the in vitro, in vivo antimicrobial activity of PAMAM dendrimers, and the associated mechanism. Interestingly, topical cervical application of 500 microg of generation-4 neutral dendrimer (G(4)-PAMAM-OH) showed potential to treat the Escherichia coli induced ascending uterine infection in guinea pig model of chorioamnionitis. Amniotic fluid collected from different gestational sacs of infected guinea pigs posttreatment showed absence of E. coli growth in the cultures plated with it. The cytokine level [tumor necrosis factor (TNFalpha) and interleukin (IL-6 and IL-1beta)] in placenta of the G(4)-PAMAM-OH treated animals were comparable to those in healthy animals while these were notably high in infected animals. Since, antibacterial activity of amine-terminated PAMAM dendrimers is known, the activity of hydroxyl and carboxylic acid terminated PAMAM dendrimers was compared with it. Though the G(4)-PAMAM-NH(2) shows superior antibacterial activity, it was found to be cytotoxic to human cervical epithelial cell line above 10 microg/mL, while the G(4)-PAMAM-OH was non-cytotoxic up to 1mg/mL concentration. Cell integrity, outer (OM) and inner (IM) membrane permeabilization assays showed that G(4)-PAMAM-OH dendrimer efficiently changed the OM permeability, while G(4)-PAMAM-NH(2) and G(3.5)-PAMAM-COOH damaged both OM and IM causing the bacterial lysis. The possible antibacterial mechanism are G(4)-PAMAM-NH(2) acts as polycation binding to the polyanionic lipopolysaccharide in E. coli, the G(4)-PAMAM-OH forms hydrogen bonds with the hydrophilic O-antigens in E. coli membrane and the G(3.5)-PAMAM-COOH acts as a polyanion, chelating the divalent ions in outer cell membrane of E. coli. This is the first study which shows that G(4)-PAMAM-OH dendrimer acts as an antibacterial agent.
authors.affiliation: Department of Pediatrics, Children's Hospital of Michigan, Wayne State University, Detroit, MI 48201, United States.
authors.forename: Bing
authors.initials: B
authors.lastname: Wang
authors.forename: Raghavendra S
authors.initials: RS
authors.lastname: Navath
authors.forename: Anupa R
authors.initials: AR
authors.lastname: Menjoge
authors.forename: Bindu
authors.initials: B
authors.lastname: Balakrishnan
authors.forename: Robert
authors.initials: R
authors.lastname: Bellair
authors.forename: Hui
authors.initials: H
authors.lastname: Dai
authors.forename: Roberto
authors.initials: R
authors.lastname: Romero
authors.forename: Sujatha
authors.initials: S
authors.lastname: Kannan
authors.forename: Rangaramanujam M
authors.initials: RM
authors.lastname: Kannan
mesh_terms: D000653:Amniotic Fluid / Q000382:microbiology*; D000818:Animals; D000900:Anti-Bacterial Agents / Q000378:metabolism / Q000494:pharmacology* / Q000633:toxicity; D002460:Cell Line; D002462:Cell Membrane / Q000187:drug effects / Q000648:ultrastructure; D002463:Cell Membrane Permeability / Q000187:drug effects; D002626:Chemistry, Pharmaceutical; D002821:Chorioamnionitis / Q000188:drug therapy* / Q000276:immunology / Q000382:microbiology; D050091:Dendrimers / Q000378:metabolism / Q000494:pharmacology* / Q000633:toxicity; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D004926:Escherichia coli / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism / Q000648:ultrastructure; D004927:Escherichia coli Infections / Q000150:complications / Q000188:drug therapy* / Q000276:immunology; D005260:Female; D006168:Guinea Pigs; D006801:Humans; D053583:Interleukin-1beta / Q000378:metabolism; D015850:Interleukin-6 / Q000378:metabolism; D051379:Mice; D050296:Microbial Viability / Q000187:drug effects; D017628:Microglia / Q000187:drug effects; D008855:Microscopy, Electron, Scanning; D009757:Nylons / Q000494:pharmacology; D019081:O Antigens / Q000378:metabolism; D010920:Placenta / Q000187:drug effects / Q000276:immunology; D011247:Pregnancy; D013997:Time Factors; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
chemical_list: D000900:Anti-Bacterial Agents; D050091:Dendrimers; D053583:Interleukin-1beta; D015850:Interleukin-6; D009757:Nylons; D019081:O Antigens; C522260:PAMAM G3.5 dendrimer; C104700:PAMAM Starburst; C520550:PAMAM-G4; D014409:Tumor Necrosis Factor-alpha