AMPK attenuates inflammation to reduce fibrosis induced by acute ischemia reperfusion injury in mice

Abstract

Objective To observe the effect of adenosine monophosphate activated protein kinase(AMPK)on attenuating inflammation in fibrosis induced by acute ischemia reperfusion injury(IRI)in mice. Methods Forty eight male C57BL/6 mice were randomly divided into four groups: sham operation group(sham group), IRI group, AMPK inhibitor+ IRI group(AMPK/IRI group)and normal saline+IRI group(NS/IRI group), 12 mice each group. The mice with renal IRI were occluded for 30 min through clipping bilateral renal pedicle, then released renal perfusion. Mice in sham group were performed the separation of renal pedicle without clipping. Mice in AMPK/IRI group and NS/IRI group were respectively intraperitoneal injected AMPK inhibitor and normal saline before IRI. At the 2 d after operation, 6 randomly- selected mice from each group were blooded by extraction eyeball to detect BUN and Scr. The renal histopathological changes were observed through HE staining. The mRNA expression of IL- 1β, IL- 6 and TNF- α was detected by real time PCR, and the level of AMPK phosphorylation was detected by Western blotting. At the 14 d after operation, Collagen 1(COL1), α - SMA and fibronectin(FN)were detected by immunofluorescence and Western blotting in 6 remained mice from each group. The degree of kidney fibrosis was observed through sirus red staining. Results Compared with those in sham group, tubular interstitial damage was aggravated(P<0.05), BUN and Scr were increased(P<0.05), the mRNA expression of IL-1β, IL-6 and TNF-α was increased at the 2 d after operation(all P<0.05), and the level of AMPK phosphorylation was activated in IRI group and NS/IRI group(all P<0.05); the degree of kidney fibrosis and the expression of COL1, α-SMA and FN were increased obviously at the 14 d(all P<0.05). Compared with thosein IRI group, in AMPK/IRI group tubular interstitial damage was aggravated(P<0.05), BUN and Scr were increased(all P<0.05), the mRNA expression of IL-1β, IL-6 and TNF-α was increased at the 2 d(all P<0.05), and the level of AMPK phosphorylation was decreased(P<0.05). Moreover, the degree of kidney fibrosis and the expression of COL1, α-SMA and FN were increased obviously at the 14 d in AMPK/IRI group(all P<0.05). Conclusions AMPK can ameliorate the acute renal ischemia reperfusion injury induce fibrosis in mice, and the mechanism may be related to the decrease of inflammatory reaction. Key words: Fibrosis; Kidney diseases; Reperfusion injury; Intracellular signaling peptides and proteins; Inflammation