The Selective A'3AR Antagonist LJ-1888 Ameliorates UUO-Induced Tubulointerstitial Fibrosis

摘要

Adenosine in the normal kidney significantly elevates in response to cellular damage. The renal A"3 adenosine receptor (A"3AR) is up-regulated under stress, but the therapeutic effects of A"3AR antagonists on chronic kidney disease are not fully understood. The present study examined the effect of LJ-1888 [(2R,3R,4S)-2-[2-chloro-6-(3-iodobenzylamino)-9H-purine-9-yl]-tetrahydrothiophene-3,4-diol], a newly developed potent, selective, species-independent, and orally active A"3AR antagonist, on unilateral ureteral obstruction (UUO)-induced renal fibrosis. Pretreatment with LJ-1888 inhibited UUO-induced fibronectin and collagen I up-regulation in a dose-dependent manner. Masson's trichrome staining confirmed that LJ-1888 treatment effectively reduced UUO-induced interstitial collagen accumulation. Furthermore, delayed administration of LJ-1888 showed an equivalent therapeutic effect on tubulointerstitial fibrosis to that of losartan. Small-interfering A"3AR transfection effectively inhibited transforming growth factor-@b1 (TGF-@b1)-induced fibronectin and collagen I up-regulation in proximal tubular cells similar to LJ-1888, confirming that the renoprotective effect of LJ-1888 resulted from A"3AR blockade. UUO- or TGF-@b1-induced c-Jun N-terminal kinase and extracellular signal-regulated kinase phosphorylation decreased significantly after LJ-1888 administration. A"3AR blockade reduced UUO- or TGF-@b1-induced up-regulation of lysyl oxidase, which induces cross-linking of extracellular matrix, suggesting that LJ-1888 may also regulate extracellular matrix accumulation via post-translational regulation. In conclusion, the present data demonstrate that the A"3AR antagonist, LJ-1888, blocked the development and attenuated the progression of renal fibrosis, and they suggest that LJ-1888 may become a new therapeutic modality for renal interstitial fibrosis.