Inosine exerts a broad range of antiinflammatory effects in a murine model of acute lung injury.
OBJECTIVE
To investigate the effects of inosine on the acute lung inflammation induced by lipopolysaccharide (LPS) in vivo and on the activation and cytotoxicity elicited by proinflammatory cytokines on human lung epithelial (A549) cells in vitro.


BACKGROUND
Inosine is an endogenous purine recently shown to exert immunomodulatory and antiinflammatory effects.


METHODS
Mice challenged with intratracheal LPS (50 microg) were treated after 1, 6, and 12 hours with inosine (200 mg/kg intraperitoneal) or vehicle. After 24 hours, bronchoalveolar lavage fluid was obtained to measure proinflammatory (tumor necrosis factor-alpha [TNF-alpha], interleukin [IL]-1beta, IL-6), and antiinflammatory (IL-10, IL-4) cytokines, chemokines (MIP-1alpha and MIP-2), myeloperoxidase activity and total cell counts, nitric oxide production, and proteins. Lung histology and immunohistochemical detection of 3-nitrotyrosine, a marker of nitrosative stress, were performed in inflated-fixed lungs. In vitro, cell viability and production of the chemokine IL-8 were evaluated in A549 cells stimulated with a mixture of cytokines in the presence or absence of inosine.


RESULTS
Inosine downregulated the LPS-induced expression of TNF-alpha, IL-1beta, IL-6 and MIP-2 and tended to reduce MIP-1alpha, whereas it enhanced the production of IL-4. Total leukocyte counts, myeloperoxidase, nitric oxide production, and proteins were all significantly decreased by inosine. The purine also improved lung morphology and suppressed 3-nitrotyrosine staining in the lungs after LPS. Inosine attenuated the cytotoxicity and the expression of IL-8 induced by proinflammatory cytokines in A549 cells.


CONCLUSIONS
Inosine largely suppressed LPS-induced lung inflammation in vivo and reduced the toxicity of cytokines in lung cells in vitro. These data support the proposal that inosine might represent a useful adjunct in the therapy of acute respiratory distress syndrome.
Liaudet
Lucas
L
Inotek Corporation, Beverly, Massachusetts 01915, USA.
Mabley
Jon G
JG
Pacher
Pál
P
Virág
László
L
Soriano
Francisco G
FG
Marton
Anita
A
Haskó
György
G
Deitch
Edwin A
EA
Szabó
Csaba
C
D000818:Animals; D000893:Anti-Inflammatory Agents / Q000627:therapeutic use*; D002460:Cell Line; D016207:Cytokines / Q000187:drug effects*; D004195:Disease Models, Animal; D004847:Epithelial Cells / Q000187:drug effects*; D004926:Escherichia coli / Q000472:pathogenicity*; D006801:Humans; D066298:In Vitro Techniques; D007288:Inosine / Q000627:therapeutic use*; D008070:Lipopolysaccharides / Q000009:adverse effects*; D008168:Lung / Q000187:drug effects*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D012128:Respiratory Distress Syndrome / Q000139:chemically induced* / Q000188:drug therapy*
D000893:Anti-Inflammatory Agents; D016207:Cytokines; D008070:Lipopolysaccharides; D007288:Inosine