Effects And Mechanism Of Fosinopril On Hepatic Fibrosis In Rats With Nonalcoholic Steatohepatitis

Background: Angiotensin (Ang)II, a major functional component ofthe renin-angiotensin system (RAS), plays an important role in thedevelopment of liver fibrosis. Angiotensin-converting enzyme (ACE) is thekey enzyme of AngII generation. ACE2degrades AngII to Ang-(1-7) andcounter-regulates AngII. AngII promotes leptin production and suppressesadiponectin production. Leptin and adiponectin have profibrotic andantifibrotic effects, respectively.Objective:(1) The aim of this research was to evaluate the effect of theangiotensin converting enzyme (ACE) inhibitor fosinopril on liver fibrosisin rats with high-fat diet (HFD)-induced nonalcoholic steatohepatitis(NASH).(2) To evaluate the effect of fosinopril on ACE2, leptin andadiponectin expression in rats with NASH.Methods: Forty male Sprague-Dawley rats were randomized into fourexperimental groups (n=10each): NC (control, normal diet), HC (HFD),NF (normal diet+fosinopril), and HF (HFD+fosinopril). Rats in the NFand HF groups were fed fosinopril (3.6mg/kg body weight/day by gavage) in addition to their respective diet. All rats were euthanized after24weekstreatment.(1) Body and liver weight were weighed. Ratio of liver/bodyweight also were counted.(2) Hematoxylin and eosin staining was used toassess the degree of hepatic steatosis, lobular inflammation, hepatocyteballooning, for counting Non-alcoholic fatty liver disease (NAFLD)activity score (NAS). Masson's trichrome-staining was also used to assessthe stage of hepatic fibrosis.(3) Liver function, blood lipid and fastingblood glucose (FBG) were determined. Radioimmunoassay was used todetermine concentration of serum insulin. Homeostasis model assessmentof insulin resistance (HOMA-IR) was used to count insulin resistance index(IRI).(4) Enzyme-linked immuno sorbent assay (ELISA) was used todetermine concentration of serum ACE2, AngII, Ang-(1-7), leptin,adiponectin, Hyaluronic acid (HA) and Transforming growth factor(TGF)-β1.(5) Reverse transcription-polymerase chain reaction (RT-PCR)was used to determine the expression of ACE2, leptin and adiponectin inliver. White adipose tissue leptin and adiponectin expression also weredetermined.(6) Western blotting analysis was used to determine hepaticACE2, collagen I and α-smooth muscle actin (α-SMA) protein expression.Results:(1) Treatment with fosinopril significantly decreased the liverweight (32.61±8.65vs23.42±4.28, P <0.05) and ratio of liver/bodyweight (0.050±0.004vs0.042±0.004, P <0.05), but had no effect onbody weight (643.60±134.34vs553.00±63.41, P>0.05) in rats with NASH. (2) Treatment with fosinopril significantly decreased the score of steatosis(2.85±0.24vs1.40±0.52), lobular inflammation (2.85±0.24vs1.40±0.52),NAS (5.85±1.31vs3.00±0.82) and stage of liver fibrosis (3.80±0.75vs2.05±0.60; P <0.05, respectively), whereas no significant improvement wasobserved in hepatocyte ballooning (0.75±0.59vs0.40±0.39, P>0.05).(3)Treatment with fosinopril significantly decreased the concentrations ofserun ALT (91.30±30.715vs0.20±12.13), ALP (243.00±77.23vs161.30±37.16), TG (2.25±0.31vs1.09±0.34), TCHO (3.12±0.50vs2.48±0.36), LDL (1.53±0.31vs1.16±0.13), FFA (0.96±0.06vs0.56±0.13),insulin (21.62±5.78vs14.13±3.26) and IRI (11.29±3.67vs5.77±1.76; P<0.05, respectively), whereas had no effect on GGT, TBA, and FBG(P>0.05).(4) The concentrations of serumACE2, AngII and Ang-(1-7)were significantly higher in the HC group compared with the NC group (P<0.05, respectively); Treatment with fosinopril significantly decreased theconcentrations of serum AngII (0.39±0.10vs0.12±0.13), and increasedserum ACE2(12.15±4.83vs22.65±5.65) and Ang-(1-7)(0.67±0.18vs1.58±72) concentrations (P <0.05, respectively).(5) The concentrations ofserum leptin and the ratio of leptin/adiponectin (L/A) were significantlyhigher in the HC group compared with the NC group, whereas adiponectinwas significantly lower (P <0.05, respectively). Treatment with fosinoprilsignificantly decreased the concentrations of serum leptin (130.61±35.56vs31.74±36.35) and the L/A (25.07±13.41vs1.67±2.07); and increased serum adiponectin concentration significantly (5.97±2.19vs21.60±8.43; P <0.05,respectively).(6) Treatment with fosinopril significantly decreased theconcentrations of serum HA (165.72±29.10vs90.13±27.42) and TGF-β1(125.95±8.23vs72.55±23.25) in rats with NASH (P <0.05, respectively).(7) The hepatic ACE2mRNA expression were singnificantly higher in theHC group compared with the NC group (P <0.05, respectively). Treatmentwith fosinopril significantly increased ACE2mRNA expression in the liverof rats with NASH (P <0.05).(8) The mRNA expression of leptin wassignificantly higher (P <0.05), whereas adiponectin was singnificantlylower (P <0.05) in the liver of the HC group compared with the NC group.Treatment with fosinopril significantly decreased lepatin mRNA expression(P <0.05), and increased adiponectin mRNA expression in the liver of ratswith NASH (P <0.05).(9) In the rats white adipose tissue of the HC group,the mRNA expression of leptin was significantly higher (P <0.05), whereasadiponectin was singnificantly lower (P <0.05) compared with the NCgroup. Treatment with fosinopril significantly increased adiponectin mRNAexpression (P <0.05), but had no effect on lepatin mRNA expression(P>0.05) in the white adipose tissue of rats with NASH.(10) The hepaticprotein expression of ACE2, collagen I and α-SMA were singnificantlyhigher in the HC group compared with the NC group (P <0.05,respectively). Treatment with fosinopril significantly increased ACE2protein expression (P>0.05), and significantly decreased collagen I (P>0.05) and α-SMA (P>0.05) protein expression in the liver of rats withNASH.Conclusions:(1) In the study, HFD could induce SD rat with NASHsuccessfully.(2) ACEI fosinopril improves insulin resistance,favorablymodulates hepatic steatosis and liver fibrosis and leads to improvements inrats with NASH.(3) Fosinopril improves liver fibrosis by upregulating theexpression of hepatic ACE2. Furthermore, it is possible that fosinoprilregulates the progression of liver fibrosis through the downregulation ofleptin and the upregulation of adiponectin by upregulating of ACE2.