title: Lipoxin A(4) attenuates zymosan-induced arthritis by modulating endothelin-1 and its effects.
abstract: OBJECTIVE
  Lipoxin A(4) (LXA(4)) is a lipid mediator involved in the resolution of inflammation. Increased levels of LXA(4) in synovial fluid and enhanced expression of the formyl peptide receptor 2/lipoxin A(4) receptor (FPR2/ALX) in the synovial tissues of rheumatoid arthritis patients have been reported. Endothelins (ETs) play a pivotal pro-inflammatory role in acute articular inflammatory responses. Here, we evaluated the anti-inflammatory role of LXA(4), during the acute phase of zymosan-induced arthritis, focusing on the modulation of ET-1 expression and its effects.
  
  
  METHODS
  The anti-inflammatory effects of LXA(4), BML-111 (agonist of FPR2/ALX receptors) and acetylsalicylic acid (ASA) pre- and post-treatments were investigated in a murine model of zymosan-induced arthritis. Articular inflammation was assessed by examining knee joint oedema; neutrophil accumulation in synovial cavities; and levels of prepro-ET-1 mRNA, leukotriene (LT)B(4), tumour necrosis factor (TNF)-α and the chemokine KC/CXCL1, after stimulation. The direct effect of LXA(4) on ET-1-induced neutrophil activation and chemotaxis was evaluated by shape change and Boyden chamber assays respectively.
  
  
  RESULTS
  LXA(4), BML-111 and ASA administered as pre- or post-treatment inhibited oedema and neutrophil influx induced by zymosan stimulation. Zymosan-induced preproET-1 mRNA, KC/CXCL1, LTB(4) and TNF-α levels were also decreased after LXA(4) pretreatment. In vitro, ET-1-induced neutrophil chemotaxis was inhibited by LXA(4) pretreatment. LXA(4) treatment also inhibited ET-1-induced oedema formation and neutrophil influx into mouse knee joints.
  
  
  CONCLUSIONS
  LXA(4) exerted anti-inflammatory effects on articular inflammation through a mechanism that involved the inhibition of ET-1 expression and its effects.
authors.affiliation: Laboratório de Farmacologia Aplicada, Farmanguinhos, Fundação Oswaldo Cruz, Rio de Janeiro, Brazil.
authors.forename: F P
authors.initials: FP
authors.lastname: Conte
authors.forename: O
authors.initials: O
authors.lastname: Menezes-de-Lima
authors.forename: W A
authors.initials: WA
authors.lastname: Verri
authors.forename: F Q
authors.initials: FQ
authors.lastname: Cunha
authors.forename: C
authors.initials: C
authors.lastname: Penido
authors.forename: M G
authors.initials: MG
authors.lastname: Henriques
mesh_terms: D000818:Animals; D000893:Anti-Inflammatory Agents / Q000494:pharmacology*; D001169:Arthritis, Experimental / Q000188:drug therapy* / Q000503:physiopathology; D001241:Aspirin / Q000494:pharmacology; D004487:Edema / Q000188:drug therapy / Q000503:physiopathology; D019332:Endothelin-1 / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects; D006538:Heptanoic Acids / Q000494:pharmacology; D007719:Knee Joint / Q000187:drug effects / Q000503:physiopathology; D044045:Lipoxins / Q000494:pharmacology*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009504:Neutrophils / Q000187:drug effects / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D015054:Zymosan
chemical_list: C530770:5(S),6(R)-7-trihydroxyheptanoic acid, methyl ester; D000893:Anti-Inflammatory Agents; D019332:Endothelin-1; D006538:Heptanoic Acids; D044045:Lipoxins; D012333:RNA, Messenger; C040527:lipoxin A4; D015054:Zymosan; D001241:Aspirin