Qi Liu

Ischemia–reperfusion (I/R) is the most common cause of acute kidney injury (AKI) and can induce apoptosis in renal epithelial tubule cells. Mitochondrial dysfunction is one of the main reasons for I/R-induced apoptosis. Accumulating evidence suggests that PINK1/Parkin-mediated mitophagy possibly plays a renoprotective role in kidney disease by removing impaired mitochondria and preserving a healthy population of mitochondria. Our previous study showed that augmenter of liver regeneration (ALR) alleviates tubular epithelial cells apoptosis in rats with AKI, although the specific mechanism remains unclear. In this study, we investigated the role of ALR in I/R-induced mitochondrial pathway of apoptosis. We knocked down ALR with short hairpin RNA lentiviral and established an I/R model in human kidney proximal tubular (HK-2) cells in vitro. We observed that the knockdown of ALR aggravated mitochondrial dysfunction and increased the mitochondrial reactive oxygen species (ROS) levels, leading to an increase in cell apoptosis via inhibition of mitophagy. We also found that the PINK1/Parkin pathway was activated by I/R via confocal microscopy and Western blot. Furthermore, the knockdown of ALR suppressed the activation of PINK1 and Parkin. These findings collectively indicate that ALR may protect HK-2 cells from I/R injury by promoting mitophagy, and the mechanism by which ALR regulates mitophagy seems to be related to PINK1 and Parkin. Consequently, ALR may be used as a potential therapeutic agent for AKI in the future.

Autophagy may have protective effects in renal ischemia–reperfusion (I/R) injury, although the underlying mechanisms remain unclear. Augmenter of liver regeneration (ALR), a widely distributed multifunctional protein that is originally identified as a hepatic growth factor, may participate in the process of autophagy. To investigate the role of ALR in autophagy, ALR expression is knocked-down in human kidney 2 (HK-2) cells with short hairpin RNA lentivirals. Then, the level of autophagy is measured in the shRNA/ALR group and the shRNA/control group in an in vitro model of ischemia–reperfusion (I/R). The results indicate that the level of autophagy in two groups increase, accompanied by increased reactive oxygen species production, especially in the shRNA/ALR group. The AMPK/mTOR signaling pathway is hyperactive in the shRNA/ALR group. Inhibition of autophagy with the AMPK inhibitor compound C induce apoptosis, especially in the shRNA/ALR group. These findings collectively indicate that ALR negatively regulates the autophagy process through an association with the AMPK/mTOR signaling pathway. Autophagy inhibit apoptosis and play a protective role under conditions of oxidative stress.

Transforming growth factor-β (TGF-β), via its receptors, induces epithelial-mesenchymal transition (EMT) and plays an important role in the development of renal tubulointersitial fibrosis. Angiotensin II type 2 receptor (AT₂R), which mediates beneficial renal physiological functions, has received attention as a prospective therapeutic target for renoprotection. In this study, we investigated the effect and underlying mechanism of AT₂R on the TGF-β receptor II (TGF-βRII) expression and function in human proximal tubular cells (HK-2). Here, we show that the AT₂R agonist CGP42112A decreased TGF-βRII protein expression in a concentration- and time-dependent manner in HK-2 cells. The inhibitory effect of the AT₂R on TGF-βRII expression was blocked by the AT₂R antagonists PD123319 or PD123177. Stimulation with TGF-β1 enhanced EMT in HK-2 cells, which was prevented by pre-treatment with CGP42112A. One of mechanisms in this regulation is associated with the increased TGF-βRII degradation after activation of AT₂R. Furthermore, laser confocal immunofluorescence microscopy showed that AT₂R and TGF-βRII colocalized in HK-2 cells. AT₂R and TGF-βRII coimmunoprecipitated and this interaction was increased after AT₂R agonist stimulation for 30 min. The inhibitory effect of the AT₂R on TGF-βRII expression was also blocked by the nitric oxide synthase inhibitor L-NAME, indicating that nitric oxide is involved in the signaling pathway. Taken together, our study indicates that the renal AT₂R regulates TGF-βRII expression and function via the nitric oxide pathway, which may be important in the control of renal tubulointerstitial fibrosis.

Renal fibrosis is a hallmark in CKD (chronic kidney disease) and is strongly correlated to the deterioration of renal function that is characterized by tubulointerstitial fibrosis, tubular atrophy, glomerulosclerosis and disruption of the normal architecture of the kidney. ALR (augmenter of liver regeneration) is a growth factor with biological functions similar to those of HGF (hepatocyte growth factor). In this study, our results indicate that endogenous ALR is involved in the pathological progression of renal fibrosis in UUO (unilateral ureteral obstruction) rat model. Moreover, we find that administration of rhALR (recombinant human ALR) significantly alleviates renal interstitial fibrosis and reduces renal-fibrosis-related proteins in UUO rats. Further investigation reveals that rhALR suppresses the up-regulated expression of TGF-β1 (transforming growth factor β1) induced by UUO operation in the obstructed kidney, and inhibits Smad2 and Smad3 phosphorylation activated by the UUO-induced injury in the animal model. Therefore we suggest that ALR is involved in the progression of renal fibrosis and administration of rhALR protects the kidney against renal fibrosis by inhibition of TGF-β/Smad activity.

The aim of our meta-analysis was to compare the efficacy and safety of radiofrequency ablation (RFA) versus surgical resection for patients with small hepatocellular carcinoma (SHCC). Randomized controlled trials (RCTs) or retrospective studies comparing the RFA with surgical resection for patients with SHCC published from 2004 to 2014 were selected from database of PubMed, EMBASE and Cochrane library. The outcomes including overall survival rate, recurrence-free survival rate, recurrence rate and complications (mortality rate and morbidity rate) were abstracted. Individual and pooled odds ratio with 95 % confidence interval of each outcome was analyzed. Three RCTs and twenty retrospective studies were included with a total of 15,482 patients. The 1-, 3- and 5-year overall survival rate and recurrence-free survival rate of surgical resection were significantly higher than RFA. The 2- and 3-year but not 1-year recurrence rate of RFA was significantly higher than surgical resection. The morbidity rate of complication in surgical resection group was higher than it in RFA group, but the mortality was not different between the two groups. Surgical resection led to a higher overall survival and recurrence-free survival rate in treating SHCC. However, RFA led to a lower morbidity rate of complication than surgical resection.

Regulating apoptosis of lymphocytes is an effective strategy for treatment of lymphocyte-mediated diseases. Recently it has been demonstrated that augmenter of liver regeneration (ALR), an enigmatic protein presented ubiquitously in multiple forms among eukaryotes, possesses potent anti-apoptotic activity and supports proliferation of a variety of cells. However, its action on lymphocytes and the underlying mechanism are not completely understood. In this study, we analyzed the effects of recombinant human ALR (rhALR) on apoptosis of human lymphocytes activated with concanavalin A (ConA). Our results showed that rhALR inhibited apoptosis of ConA-activated lymphocytes and revealed reductions in the percentage of apoptotic cells, caspase-3 activation and PARP cleavage in cells treated with rhALR. Furthermore, the BAX/BCL-2 and cytosol/mitochondria cytochrome c ratios were decreased in the intrinsic death pathway and the activation of caspase-8 was also decreased in the extrinsic death pathway in activated lymphocytes treated with rhALR. In addition, rhALR significantly reduced the quantity of interleukin-2. These results demonstrated that rhALR has anti-apoptotic effects on activated lymphocytes through the activation of several apoptosis-related signaling pathways, and shed some light on the effects of rhALR on modulation immune reactions.