title: Glycyrrhizin Reduces HMGB1 and Bacterial Load in Pseudomonas aeruginosa Keratitis.
abstract: OBJECTIVE
  High mobility group box 1 (HMGB1) contributes to poor disease outcome in Pseudomonas aeruginosa keratitis. This study tests the prophylactic effect of treatment with HMGB1 inhibitors, glycyrrhizin (GLY) and its derivative, carbenoxolone (CBX), for Pseudomonas keratitis.
  
  
  METHODS
  We treated C57BL/6 (B6) mice subconjunctivally with GLY or CBX, infected with a noncytotoxic clinical isolate (KEI 1025) or a cytotoxic strain (ATCC 19660) of P. aeruginosa, and injected intraperitoneally with either agent. Clinical score, photography with a slit lamp, real-time RT-PCR, ELISA, myeloperoxidase (MPO) assay, bacterial plate count, histopathology, and absorbance assays were used to assess treatment efficacy and bacteriostatic activity.
  
  
  RESULTS
  After KEI 1025 infection, GLY treatment reduced HMGB1 (mRNA and protein levels) and improved disease outcome with significant reduction in mRNA levels of IL-1β, TLR4, CXCL2, and IL-12; protein expression (IL-1β, CXCL2); neutrophil infiltrate; and bacterial load. Treatment with GLY enhanced antimicrobial proteins, including CRAMP and mBD2, but not mBD3. Glycyrrhizin also reduced clinical scores and improved disease outcome in corneas infected with strain 19660. However, neither HMGB1 mRNA or protein levels were reduced, but rather, CXCL2 expression (mRNA and protein), neutrophil infiltrate, and bacterial load were reduced statistically. Treatment with GLY initiated 6 hours after infection reduced plate count; GLY also was bacteriostatic for KEI 1025 and ATCC 19660.
  
  
  CONCLUSIONS
  Glycyrrhizin reduces HMGB1 and is protective against P. aeruginosa-induced keratitis with a clinical isolate that is noncytotoxic. It was similar, but less effective when used after infection with a cytotoxic strain, which did not reduce HMGB1.
authors: Department of Anatomy & Cell Biology, Wayne State University School of Medicine, Detroit, Michigan, United States.
authors: Sandamali A
authors: SA
authors: Ekanayaka
authors: Department of Anatomy & Cell Biology, Wayne State University School of Medicine, Detroit, Michigan, United States.
authors: Sharon A
authors: SA
authors: McClellan
authors: Department of Anatomy & Cell Biology, Wayne State University School of Medicine, Detroit, Michigan, United States.
authors: Ronald P
authors: RP
authors: Barrett
authors: Department of Anatomy & Cell Biology, Wayne State University School of Medicine, Detroit, Michigan, United States.
authors: Shikhil
authors: S
authors: Kharotia
authors: Department of Anatomy & Cell Biology, Wayne State University School of Medicine, Detroit, Michigan, United States.
authors: Linda D
authors: LD
authors: Hazlett
mesh_terms: D000818:Animals; D000893:Anti-Inflammatory Agents / Q000627:therapeutic use; D058491:Bacterial Load / Q000187:drug effects*; D003315:Cornea / Q000382:microbiology / Q000473:pathology; D004195:Disease Models, Animal; D004797:Enzyme-Linked Immunosorbent Assay; D015818:Eye Infections, Bacterial / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism; D005260:Female; D005786:Gene Expression Regulation; D019695:Glycyrrhizic Acid / Q000627:therapeutic use*; D024243:HMGB1 Protein / Q000235:genetics* / Q000378:metabolism; D007634:Keratitis / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D011552:Pseudomonas Infections / Q000188:drug therapy* / Q000235:genetics / Q000382:microbiology; D011550:Pseudomonas aeruginosa / Q000302:isolation & purification*; D012333:RNA, Messenger / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction
chemical_list: D000893:Anti-Inflammatory Agents; D024243:HMGB1 Protein; C582808:HMGB1 protein, mouse; D012333:RNA, Messenger; D019695:Glycyrrhizic Acid