P27 Promotes TGF-ß-Mediated Pulmonary Fibrosis via Interacting with MTORC2.

Pulmonary fibrosis (PF), a progressive and life-threatening pulmonary disease, is the main pathological basis of interstitial lung disease (ILD) which includes the idiopathic pulmonary fibrosis (IPF). No effective therapeutic strategy for pulmonary fibrosis has been established. TGF-ß signaling has emerged as the vital regulator of PF; however, the detailed molecular mechanisms of TGF-ß in PF were uncertain. In the present study, we proved that inhibition of MTORC2 suppresses the expression of P27 in MRC5 and HLF cells. And in bleomycin-induced PF model, the expression of α-SMA and P27 was upregulated. Moreover, TGF-ß application increased the level of α-SMA, vimentin, and P27 in MRC5 and HLF cells. Furthermore, P27 overexpression advanced the cell cycle process and promoted the proliferation of MRC5 and HLF cells. Finally, the rescue experiment showed that MTORC2 knockdown reversed P27 overexpression-induced cell cycle acceleration and proliferation. Thus, our results suggest that P27 is involved in TGF-ß-mediated PF, which was regulated by MTORC2, providing a novel insight into the development of PF.

[Impact of chronic intermittent hypoxia upon rat liver lipid metabolism and interventional effect of Tempol].

OBJECTIVE: To explore the impact of chronic intermittent hypoxia (CIH) upon rat liver lipid metabolism and effect of anti-oxidant Tempol. METHODS: Male Wistar rats (n = 80) were randomly divided into intermittent hypoxia group (10, 20, 30, 40 times/h), intermittent hypoxia Tempol treatment group, intermittent hypoxia normal saline treatment group, intermittent air mimic group (IA) and blank control group (CG). Sections of liver were stained with hematoxylin and eosin. Serum levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were measured. Levels of liver homogenate triglyceride (TG), total cholesterol (TC), free fatty acids (FFA) and serum TG, TC, adiponectin (ADP) were measured. RESULTS: Liver histology: IH group exhibited hepatocellular swelling, hyperchromatosis, disrupted hepatocellular membrane. With the increase of frequency, there were local necrosis and infiltration of inflammatory cells. But no steatosis was seen. Tempol early treatment and IA groups exhibited no hepatocellular swelling or inflammatory cell infiltration. The activities of ALT and AST increased along with the increased frequency in IH group (all P < 0.01). The levels of ALT and AST in IH group ((48.6 ± 3.6), (25.4 ± 2.6) U/L) were higher than those in IA group ((20.3 ± 3.1), (18.7 ± 1.3) U/L) and CG group ((17.5 ± 2.4), (18.8 ± 1.3) U/L) (all P < 0.01). It decreased in Tempol treatment group, and more obviously when early intervention was applied (all P < 0.01). Liver homogenate TG, TC and FFA had no difference among IH, IA and CG groups (all P > 0.05), and no difference in different frequencies in IH group (all P > 0.05). The levels of serum TG, TC in IH groups were higher than those in IA and CG groups while ADP was lower (all P < 0.01). It changed more obviously in different frequencies in IH group (all P < 0.01). In Tempol treatment group, serum TG, TC decreased while ADP increased and changed more obviously when early intervention was applied (all P < 0.01). CONCLUSIONS: CIH causes the morphologic changes of liver and the elevations of ALT and AST, but results not in lipid deposition in liver cells. Anti-oxidation of Tempol can block intermittent hypoxia associated with liver injury.

[Influence of chronic intermittent hypoxia on sympathetic nerve activity in rats and effect of the antioxidant Tempol].

OBJECTIVE: To study the role of sympathetic nerve activity during the development of hypertension resulting from chronic intermittent hypoxia, and whether or not elevated sympathetic nerve activity is related to oxidative stress, and to investigate the preventive effect and possible mechanism of Tempol. METHODS: Forty-eight male Wistar rats were randomly divided into 6 groups of 8 each, including normoxic control group (NC), intermittent hypoxia group (IH) and 4 treatment groups (IHT1, IHT2, IHN1, IHN2). Among the treatment groups, IHT1, IHT2 groups were treated with 10% Tempol 100 mg × kg(-1)× d(-1) by intraperitoneal injection before exposed to IH and on day 28 after exposed to IH respectively, while IHN1 and IHN2 groups were treated with NS as controls. RESULT: There was no statistic difference in artery systolic blood pressure (SBP) between IH group, IHN1 group [(114 ± 6) mm Hg, 1 mm Hg = 0.133 kPa], and IHN2 group [(128 ± 6) mm Hg, P < 0.05] at the end of 6(th) week. SBP in the all IH groups was significantly elevated compared with NC group (P < 0.05) and the baseline SBP (P < 0.05) except of the group IHT1. SBP in the 2 tempol treatment groups was lower than the NS groups [(138 ± 10) mm Hg, both P < 0.05], while SBP of IHT2 group was higher than the IHT1 group (P < 0.01). No significant changes were found in the NC group. There were no statistic difference of NE and E in plasma and MDA in adrenal gland tissues between IH groups, IHN1 group and IHN2 group. The levels in NE and E and MDA in the 2 tempol treatment groups were lower than the NS groups (P < 0.05 or P < 0.01), but those in the IHT2 group were higher than the NC group (P < 0.05 or P < 0.01) and IHT1 groups (P < 0.05 or P < 0.01). No significant difference were found between IHT1 group and NC group. CONCLUSION: CIH could generate ROS by causing oxidative stress, which results in elevated sympathetic nerve activity. This may be one of the important mechanisms for CIH-induced hypertension. Tempol may be useful for prevention and treatment of OSAS-induced hypertension.

[Hepatic injury in rats exposed to chronic intermittent hypoxia and the effect of tempol].

OBJECTIVE: To investigate the mechanism of liver injury in rats exposed to chronic intermittent hypoxia (CIH) and to investigate the effect of tempol (4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl or 4-hydroxy-TEMPO). METHODS: A CIH animal model of rats was established to mimic the intermittent hypoxia/re-oxygenation (IH/ROX) of obstructive sleep apnea syndrome in humans. Thirty-two healthy male Wistar rats were randomly assigned to 4 groups: conventional intermittent hypoxia group (CIH group), intermittent hypoxia Tempol treatment group (CIH + T group), intermittent hypoxia normal saline matched group (CIH + NS group), and normoxic control group (NC group), with 8 rats in each group. The frequency of every CIH group was 30 times/h, and the minimum oxygen concentration was 5%. After the experiment, sections of liver were stained with hematoxylin-eosin (HE) and the levels of nuclear factor-kappaB (NF-κB), glutathione peroxidase (GSH-PX) and malondialdehyde (MDA) in rat liver homogenate were measured. RESULTS: Liver histology revealed that the CIH group and the CIH + NS group showed hepatocellular swelling with rarefaction of the cytoplasm, hyperchromatosis and hepatocellular membrane disruption, but the liver histology of the CIH + T group and the NC group was normal. Compared with the NC group, the levels of NF-κB and MDA in the CIH group [(12.4 ± 2.0) ng/g, (101 ± 22) µmol/g] and the CIH + NS group [(12.2 ± 1.9) ng/g, (99 ± 18)µmol/g] were increased (all P < 0.05), but the activities of GSH-PX [(88 ± 17) U/mg, (90 ± 15) U/mg] were decreased (all P < 0.05). Compared with the CIH + NS group and the CIH group, the activity of GSH-PX in the CIH + T group [(181 ± 29) U/mg] was increased (P < 0.05), but the levels of NF-κB [(7.8 ± 1.3) ng/g] and MDA [(59 ± 10) µmol/g] were decreased (all P < 0.05). The levels of GSH-PX and MDA in the CIH + T group were not significantly different compared to the NC group (P were 0.242, 0.177 respectively), but the level of NF-κB in the CIH + T group was higher than that in the NC group (P < 0.05). The levels of NF-κB, GSH-PX, and MDA in the CIH + NS group were not significantly different as compared to those in the CIH group (all P > 0.05). The level of NF-κB was correlated negatively with GSH-PX, but positively with MDA (r = -0.754, 0.689, respectively, all P < 0.01) CONCLUSIONS: CIH could cause rat liver injury through oxidative stress and activating the proinflammatory transcription factors of NF-κB. Tempol could prevent CIH-induced liver injury through scavenging ROS by its anti-oxidative effect.