title: Liposomal amphotericin B activates antifungal resistance with reduced toxicity by diverting Toll-like receptor signalling from TLR-2 to TLR-4.
abstract: OBJECTIVE
  Neutrophils play a crucial role in the control of the Aspergillus fumigatus infection and act in concert with antifungal drugs. This study was undertaken to obtain insights into the possible involvement of Toll-like receptors (TLRs) in the interaction of liposomal amphotericin B (L-AmB; AmBisome) with neutrophils in response to A. fumigatus.
  
  
  METHODS
  For generation of bone marrow-transplanted mice, irradiated C57BL6 mice were infused with T cell-depleted allogeneic donor cells. For infection, mice were injected intranasally with Aspergillus fumigatus conidia and treated with L-Amb and deoxycholate amphotericin B prophylactically or therapeutically. For TLR-dependent antifungal functions, murine neutrophils were preincubated with antifungals or TLR ligands before the addition of Aspergillus conidia.
  
  
  RESULTS
  The results show that: (a) neutrophil activation by Aspergillus occurs through TLR signalling pathways differently affecting the oxidative and non-oxidative mechanisms of the killing machinery; (b) by diverting signalling from TLR-2 to TLR-4, liposomes of AmBisome activate neutrophils to an antifungal state while attenuating the pro-inflammatory effects of deoxycholate amphotericin B; (c) this translates in vivo to the optimization of the AmBisome therapeutic efficacy in mice with aspergillosis.
  
  
  CONCLUSIONS
  These results provide a putative molecular basis for the reduced infusion-related toxicity of AmBisome and suggest that TLR manipulation in vivo is amenable to the induction of optimal microbicidal activity in the absence of inflammatory cytotoxicity to host cells.
authors.affiliation: Microbiology Sections, Department of Experimental Medicine and Biochemical Sciences, University of Perugia, Perugia, Italy.
authors.forename: Silvia
authors.initials: S
authors.lastname: Bellocchio
authors.forename: Roberta
authors.initials: R
authors.lastname: Gaziano
authors.forename: Silvia
authors.initials: S
authors.lastname: Bozza
authors.forename: Giordano
authors.initials: G
authors.lastname: Rossi
authors.forename: Claudia
authors.initials: C
authors.lastname: Montagnoli
authors.forename: Katia
authors.initials: K
authors.lastname: Perruccio
authors.forename: Mario
authors.initials: M
authors.lastname: Calvitti
authors.forename: Lucia
authors.initials: L
authors.lastname: Pitzurra
authors.forename: Luigina
authors.initials: L
authors.lastname: Romani
mesh_terms: D000666:Amphotericin B / Q000008:administration & dosage* / Q000633:toxicity; D000818:Animals; D000935:Antifungal Agents / Q000008:administration & dosage* / Q000633:toxicity; D025141:Drug Resistance, Fungal / Q000187:drug effects* / Q000502:physiology; D005260:Female; D006801:Humans; D008081:Liposomes; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D009504:Neutrophils / Q000187:drug effects / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000235:genetics / Q000378:metabolism*; D051195:Toll-Like Receptor 2; D051197:Toll-Like Receptor 4
chemical_list: D000935:Antifungal Agents; D008081:Liposomes; D011956:Receptors, Cell Surface; C493486:Tlr2 protein, mouse; C493487:Tlr4 protein, mouse; D051195:Toll-Like Receptor 2; D051197:Toll-Like Receptor 4; D000666:Amphotericin B