Hepatoprotection in bile duct ligated mice mediated by darbepoetin-α is not caused by changes in hepatobiliary transporter expression

AIMS: Darbepoetin-α (DPO), a long-acting erythropoietin analog, has been shown to protect the liver against cholestatic injury, to exert an antifibrotic effect, and to increase the survival time in a model of common bile duct ligation. Here we evaluate whether these tissue-protective effects are caused by DPO induced regulation of hepatobiliary transporters. MAIN METHODS: C57BL/6J mice underwent common bile duct ligation and were treated with either DPO or physiological saline. Time dependent (2, 5, 14, 28 days after bile duct ligation) protein expression of different hepatobiliary transporters which have been established to play an important role in hepatocellular (i) bile acid uptake, (ii) bile acid excretion, and (iii) retrograde bile acid efflux were assessed. mRNA and protein expression of Lhx2, an important negative regulator of hepatic stellate cell activation, was determined. KEY FINDINGS: Saline treated cholestatic mice impress with increased mRNA expression of Lhx2 as a defense mechanism, while there is less need for such an upregulation in mice treated with DPO. Whereas Ntcp (slc10a1) protein expression is suppressed as early as 2 days after bile duct ligation to 40% in untreated animals, DPO treated mice exhibit decreased protein level not before day 5. Similarly, the steady decline of Mrp4 (abcc4) protein level during extrahepatic cholestasis in control treated animals does not occur upon DPO application. SIGNIFICANCE: The collected data show that DPO affects expression of hepatobilliary transporters during obstructive cholestasis but do not provide sufficient evidence to demonstrate a direct correlation between this regulation and hepatoprotection by DPO

Down-Regulation of MiR-127 Facilitates Hepatocyte Proliferation during Rat Liver Regeneration

Liver regeneration (LR) after partial hepatectomy (PH) involves the proliferation and apoptosis of hepatocytes, and microRNAs have been shown to post-transcriptionally regulate genes involved in the regulation of these processes. To explore the role of miR-127 during LR, the expression patterns of miR-127 and its related proteins were investigated. MiR-127 was introduced into a rat liver cell line to examine its effects on the potential target genes Bcl6 and Setd8, and functional studies were undertaken. We discovered that miR-127 was down-regulated and inversely correlated with the expression of Bcl6 and Setd8 at 24 hours after PH, a time at which hypermethylation of the promoter region of the miR-127 gene was detected. Furthermore, in BRL-3A rat liver cells, we observed that overexpression of miR-127 significantly suppressed cell growth and directly inhibited the expression of Bcl6 and Setd8. The results suggest that down-regulation of miR-127 may be due to the rapid methylation of its promoter during the first 24 h after PH, and this event facilitates hepatocyte proliferation by releasing Bcl6 and Setd8. These findings support a miRNA-mediated negative regulation pattern in LR and implicate an anti-proliferative role for miR-127 in liver cells

Determination of nitrogen dioxide, sulfur dioxide, ozone, and ammonia in ambient air using the passive sampling method associated with ion chromatographic and potentiometric analyses

Concentrations of nitrogen dioxide (NO2), sulfur dioxide (SO2), ozone (O3), and ammonia (NH3) were determined in the ambient air of Al-Ain city over a year using the passive sampling method associated with ion chromatographic and potentiometric detections. IVL samplers were used for collecting nitrogen and sulfur dioxides whereas Ogawa samplers were used for collecting ozone and ammonia. Five sites representing the industrial, traffic, commercial, residential, and background regions of the city were monitored in the course of this investigation. Year average concentrations of ≤59.26, 15.15, 17.03, and 11.88 μg/m3 were obtained for NO2, SO2, O3, and NH3, respectively. These values are lower than the maxima recommended for ambient air quality standards by the local environmental agency and the world health organization. Results obtained were correlated with the three meteorological parameters: humidity, wind speed, and temperature recorded during the same period of time using the paired t test, probability p values, and correlation coefficients. Humidity and wind speed showed insignificant effects on NO2, SO2, O3, and NH3 concentrations at 95% confidence level. Temperature showed insignificant effects on the concentrations of NO2 and NH3 while significant effects on SO2 and O3 were observed. Nonlinear correlations (R2 ≤ 0.722) were obtained for the changes in measured concentrations with changes in the three meteorological parameters. Passive samplers were shown to be not only precise (RSD ≤ 13.57) but also of low cost, low technical demand, and expediency in monitoring different locations

Darbepoetin-α verringert die Nekroinflammation und mildert die cholestatische Fibrose in Mäusen [Darbepoetin-alpha inhibits the perpetuation of necro-inflammation and attenuates cholestatic fibrosis in mice]

Biliary obstruction and cholestasis result in hepatocellular necro-inflammation and lead to the development of liver fibrosis. Herein, we evaluated the therapeutic efficacy of Darbepoetin-α (DPO), a recombinant longer acting analogue of erythropoietin in a model of extrahepatic cholestasis. C57BL/6J mice underwent common bile duct ligation (BDL) and were treated either with DPO (10 μg/kg i. p.) or physiologic saline every third day, beginning 24 h after BDL. Mice were sacrificed at 2, 5 and 14 days after BDL. BDL provoked cholestatic hepatitis characterized by biliary infarcts with accumulation of macrophages followed by marked collagen deposition and increased gene expression of profibrotic transcripts. DPO treatment significantly diminished the area of focal necrosis, reduced the infiltration of macrophages, lowered collagen deposition, decreased levels of profibrotic transcripts, and inverted the pattern of Smad mRNA expression. Moreover, DPO prevented systemic anemia caused by BDL. Finally, DPO treatment significantly prolonged the survival time after BDL. These findings suggest that DPO, a clinically well established substance, could represent an efficient therapeutic option for patients with cholestatic liver disease