title: Oral nanotherapeutics: effect of redox nanoparticle on microflora in mice with dextran sodium sulfate-induced colitis.
abstract: BACKGROUND
  Patients with ulcerative colitis (UC) exhibit overproduction of reactive oxygen species (ROS) and imbalance of colonic microflora. We previously developed a novel redox nanoparticle (RNP(O)), which effectively scavenged ROS in the inflamed mucosa of mice with dextran sodium sulfate (DSS)-induced colitis after oral administration. The objective of this study was to examine whether the orally administered RNP(O) changed the colonic microflora in healthy mice and those with colitis.
  
  
  METHODS
  RNP(O) was synthesized by self-assembly of an amphiphilic block copolymer that contains stable nitroxide radicals in hydrophobic side chain via ether linkage. Colitis was induced in mice by supplementing DSS in drinking water for 7 days, and RNP(O) was orally administered daily during DSS treatment. The alterations of fecal microflora during treatment of DSS and RNP(O) were investigated using microbiological assays.
  
  
  RESULTS
  We investigated that RNP(O) did not result in significant changes to the fecal microflora in healthy mice. Although total aerobic and anaerobic bacteria were not significantly different between experimental groups, a remarkable increase in commensal bacteria (Escherichia coli and Staphylococcus sp.) was observed in mice with DSS-induced colitis. Interestingly, orally administered RNP(O) remarkably reduced the rate of increase of these commensal bacteria in mice with colitis.
  
  
  CONCLUSIONS
  On the basis of the obtained results, it was confirmed that the oral administration of RNP(O) did not change any composition of bacteria in feces, which strongly suggests a protective effect of RNP(O) on healthy environments in intestinal microflora. RNP(O) may become an effective and safe medication for treatment of UC.
authors.affiliation: Department of Materials Science, Graduate School of Pure and Applied Sciences, University of Tsukuba, Tennoudai 1-1-1, Tsukuba, Ibaraki, 305-8573, Japan.
authors.forename: Long Binh
authors.initials: LB
authors.lastname: Vong
authors.forename: Toru
authors.initials: T
authors.lastname: Yoshitomi
authors.forename: Kazuya
authors.initials: K
authors.lastname: Morikawa
authors.forename: Shinji
authors.initials: S
authors.lastname: Saito
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Matsui
authors.forename: Yukio
authors.initials: Y
authors.lastname: Nagasaki
mesh_terms: D000284:Administration, Oral; D000818:Animals; D003093:Colitis, Ulcerative / Q000382:microbiology* / Q000503:physiopathology; D003106:Colon / Q000382:microbiology*; D016264:Dextran Sulfate / Q000633:toxicity; D004195:Disease Models, Animal; D005243:Feces / Q000382:microbiology*; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D053758:Nanoparticles / Q000008:administration & dosage*; D010084:Oxidation-Reduction; D017382:Reactive Oxygen Species / Q000378:metabolism
chemical_list: D017382:Reactive Oxygen Species; D016264:Dextran Sulfate