Effect Of Chronic Intermittent Hypoxia On HDL Metabolism And The Possible Mechanisms Investigation

Part one:Effect of Intermittent hypoxia on serum HDL and liver PPARα、ABCA1expression in ratObjective:The present study intended to simulate intermittent hypoxia in vivo i n animal level, to investigate the effect of intermittent hypoxia on serum1ipids in male SD rats by chronic intermittent hypoxia and reoxygenation i ntervention, to detect the changes of HDL metabolism related metabolic i ndicators such as PPARa, ABCA1in the tissue level, and to observe the d ifferences in purpose indicators expressed in different concentrations of in termittent hypoxia and reoxygenation corresponding group in order to un derstand the relationship between hypoxia and lipid metabolism, and to e xplore these pathological changes after reoxygenation recovery and possi ble mechanisms, providing new ideas and experimental evidences for earl y diagnosis and early intervention of the disease.Methods:OSAHS style CIH rats were randomly allocated into6groups:10%CIH-3weeks,,5%CIH-3weeks,5%CIH-3weeks+RH(Removal of hypoxia-3weeks),10%CIH-3weeks+RH(Removal of hypoxia-3weeks), control group-3weeks, control group-6weeks,. Each group’s serum lipid were measured and compared. To observe and compare the liver pathology, PPARα、ABCA1in CIH rats’liver tissue detected by immunohistochemical method.Results:Serum lipid comparing:1、Compared with control groups, the level of serum CHOL in CIH groups significant higher(10%CIH-3weeks:2.46±0.14VS2.09±0.18mmol/L;5%CIH-3weeks:2.26±0.10vs2.09±0.18mmol/L; P<0.01);Compared with CIH groups, the level of serum CHOL in Reoxygenation groups significant lower(10%CIH+RH VS10%CIH-3:1.63±0.05VS2.46±0.14mmol/L;5%CIH+RH VS5%CIH-3:1.70±0.22vs2.26±0.10mmol/L; P<0.01); Compared with control-6weeks group, there was no difference in serum CHOL between10%CIH+RH and control-6weeks group (1.63±0.05VS1.67±0.24mmol/L,p>0.05), Which was Considered return to normal oxygen levels; there was no difference in serum CHOL between5%CIH+RH and control-6weeks group (1.70±0.22VS1.67±0.24mniol/L, P>0.05), Which was Considered return to normal oxygen levels。2、There was no difference in TG in all groups(p>0.05)3、Compared with the control group, serum LDL-C levels in10%CIH-3rat were significantly higher than in control-3group (0.33±0.06VS0.23±0.05mmol/L, P<0.01); Serum LDL-C levels in5%CIH-3rat were significantly higher than in control-3group (0.35±0.03VS0.26±0.05mmol/L, P<0.01); Compared with CIH groups, the level of serum LDL-C in Reoxygenation groups significant lower(10%CIH+RH VS10%CIH-3:0.24±0.02VS0.33±0.06mmol/L;5%CIH+RH VS5%CIH-3:0.19±0.03VS0.35±0.03mmol/L; P<0.01); There was no difference in LDL-C levels between10%CIH+RH and control-6weeks group(0.24±0.02VS0.20±0.03mmol/L, p>0.05); Which was Considered return to normal oxygen levels。There was no difference in LDL-C levels between5%CIH+RH and control-6weeks group(0.19±0.03VS0.20±0.03mmol/L, p>0.05); Which was Considered return to normal oxygen levels。4、Compared with control group, the level of serum HDL-C in CIH groupS significant lower (10%CIH-3:0.40±0.05VS0.53±0.05mmol/L;5%CIH-3:0.34±0.04VS0.53±0.06mmol/L,P<0.01);Compared with CIH groups, the level of serum LDL-C in Reoxygenation groups significant higher(10%CIH+RH VS10%CIH-3:0.52±0.04VS0.40±0.05mmol/L;5%CIH+RH VS5%CIH-3:0.48±0.04VS0.34±0.04mmol/L; P<0.01); There was no difference in HDL-C levels between10%CIH+RH and control-6weeks group(0.52±0.04VS0.49±0.06mmol/L, p>0.05); Which was Considered return to normal oxygen levels。There was no difference in HDL-C levels between5%CIH+RH and control-6weeks groups(0.48±0.04VS0.49±0.05mniol/L, P>0.05), Which was Considered return to normal oxygen levels。Immunohistochemical results of PPARα、ABCA11、Compared with control group, expression of PPARa in CIH groupS was significant lower(10%CIH-3:132.85±4.56VS178.553± 2.63;5%CIH-3:102.40±4.06VS180.42±2.58,P<0.01);Compared with CIH groups, the expression of PPARa in Reoxygenation groups significant higher(10%CIH+RH VS10%CIH-3:175.23±5.34VS132.85±4.56;5%CIH+RH VS5%CIH-3:168.70±6.12VS102.40±4.06; P<0.01); There was no difference in PPARa expression between10%CIH+RH and control-6weeks groups(175.23±5.34VS180.42±2.58, p>0.05), Which was Considered return to normal oxygen levels; There was no difference in PPARa expression between5%CIH+RH and control-6weeks groups(168.70±6.12VS180.42±2.58, P>0.05), Which was Considered return to normal oxygen levels。2、Compared with control group, expression of ABCA1in CIH groupS was significant lower(10%CIH-3:202.85±12.50, VS318.62±13.60;5%CIH-3:172.24±9.08vs318.62±13.60,P<0.01); Compared with CIH groups, the expression of ABCA1in Reoxygenation groups significant higher(10%CIH+RH VS10%CIH-3:305.22±15.24VS202.85±12.50;5%CIH+RH VS5%CIH-3:301.72±12.22VS172.24±9.08; P<0.01); There was no difference in ABCA1expression between10%CIH+RH and control-6weeks groups(305.22±15.24VS330.42±13.57(p>0.05), Which was Considered return to normal oxygen levels; There was no difference in ABCA1expression between5%CIH+RH and control-6weeks groups(301.72±12.22VS330.42±13.57, P>0.05), Which was Considered return to normal oxygen levels。Conclusion: 1、The serum LDL-C level and CHOL level in OSAHS style CIH rats were obviously increased, the serum HDL-C level was obviously decreased in OSAHS style CIH rats, while there was no statistically difference about serum TG in OSAHS style CIH rats;2、the serum level of HDL-C in rat can be effectively improved by reoxygenation intervention;3、OSAHS style CIH rats may lead to the dyslipidemia through PPARa-ABCA1pathway,reoxygenation intervention for three weeks can effectively make the rat PPARa, ABCA1expression levels returned to normal oxygen levels, Which suggesting that if CIH was intervented as long as it is possible the change of liver PPARa, ABCA1can be reversal, thereby reversing dyslipidemia. Part two:Effect of chronic intermittent hypoxia on the expression of HDL related protein PPARα、ABCA1、 apoM and the possible mechanisms investigationObjective:In this research, HepG2cells model of CIH was established。The expression of PPARa, ABCA1, apoM mRNA and the PPARa, ABCA1and apoM protein will be observed in OSAHS style CIH HepG2cells。The possible pathogenesis of HDL metabolism induced by CIH will be approached in the research, which may be helpful to prevent and cure of dyslipidemia related to OSAHS.Methods:HepG2cells were randomly allocated into3groups:control group(A),10%CIH(B),5%CIH(C); cell morphology was observed By light microscopic, Significant fat accumulation was documented by oil red O staining.RT-PCR method was adopted to detect the PPARa, ABCA1and apoMmRNA. Western-blotting method was adopted to detect the PPARa, ABCA1and apoM protein.Results:1.HepG2cells cultured in CIH groups grew slowly, ratio of steatosis in CIH groups were higher than control group, which were related to the severity of CIH。The cell survival rate inB,Cgroup(80.1±2.1)%、(48.3±2.3)%were lower than A group(P<0.01), which was of statistically significance; The cell survival rate inB group(80.1±2.1)%were higher thanC group(48.3±2.3)%(P<0.01), which was of statistically significance;Intermittent hypoxia in concentration dependence way inhibits the growth of llHepG2cell survival and intermittent hypoxia is related to the severity.2. Compared with control group, the mRNA expression(RT-PCR) of PPARa, ABCA1, apoM mRNA in B,C group decreased (p<0.01); Compared with B group, the mRNA expression(RT-PCR) of PPARa, ABCA1, apoM mRNA in C group decreased (p<0.05)。3. Compared with control group,the protein expression (Western blot) of PPARa, ABCA1, apoM mRNA in B,C group decreased (p<0.01); Compared with B group, The protein expression (Western blot) of PPARa, ABCA1, apoM mRNA in C group decreased (p<0.05)。Conclusions:The steatosis were induced in OSAHS style CIH HepG2cells; The lower expression of PPARa, ABCA1, apoM may be induced in HepG2cellsby OSAHS style CIH,which may be considered participated the metabolism disorder of HDL. Part three:The study about the relationship between the serum HDL and serum apoM、apoA5levels in OSAHS patients and the effect of nCPAP interventionObjective:To observe the relationship between the serum HDL and serum ApoM、ApoA5levels in OSAHS patients and the effect of nCPAP intervention, It may provide new theoretical direction for the further research about the related lipids disorders and treatments in OSAHS patients.Methods:18patients with moderate and sever OSAHS and18control subjects were recruited randomly.The two groups were matched for sex, age, body mass index (BMI) and diseases. lipid,and serum level of apoM, apoA5were measured and compared. In addition, the effects of3months of nCPAP on lipid,and serum level of apoM, apoA5were studied in moderate and sever OSAHS patients.Results:1、The level of AHI and serum TG were significantly higher in patients with OSAHS than in control subjects (P<0.05). The level of HDL-C, apoM、apo-A5were significantly lower in patients with OSAHS than in control subjects (P<0.05). The mean nocturnal SaO2and the lowest nocturnal SaO2were significantly lower in patients with OSAHS than in control subjects (P<0.05).There were no difference in the level of CHOL、LDL-C between two groups (P>0.05).2、There were significant positive correlation between the serum TG and AHI in all research objects, both and significant negtive correlation between AHI and serum HDL-C、apoM、apoA5; There were significant negtive correlation between serum HDL-C、apoM、apoA5and the mean nocturnal SaO2、the lowest nocturnal SaO2(P<0.05);3、There were significant positive correlation between the serum apoM、apo-A5and serum HDL-C in all research objects(P<0.001), and significant positive correlation between serum apoM and serum apoA5(r=0.536,P0.001); Stepwise regression analysis showed the good correlation between apoA5and the mean nocturnal SaO2(P<0.01)。4、nCPAP treatment decreased the serum level of TG in moderate and sever OSAHS patients (P<0.05) and the serum HDL-C, apoM, apoA5were significantly increased in moderate and sever OSAHS patients after3months nCPAP treatmentConclusion:1、The serum HDL was obviously decreased in OSAHS Patients;2、The level of serum apoM、apoA5are lower in OSAHS patients, which is related to the severity of OSAHS and HDL levels.