| ObjectiveCurrently,diabetes mellitus is one of the many types of diseases that seriously affect people’s People’s physical and mental health and quality of life.Diabetic retinopathty(DR)is one of the main microvaccular complications in patients with type 2 diabetes,which can result in blindness and affect people’s quality of life.In DR patient,there are remarkable inflammatory response,which is closely related with the initiation and development of diabetes and DR.Lipoprotein-associated phospholipase A2(LP-PLA2)and Serum amyliod A(SAA)are two enzymes that are discovered recently and closely related to inflammatory reaction.LP-PLA2,also known as platelet-activating factor acetylhydrolase,is a kind of enzyme that can selectively cut the ester bonds,with the fracture site in the Sn-2 position of phospholipid part.It has been reported that inflammation can increase the activity of LP-PLA2.Through the activation of cyclooxygenase and lipoxygenase,eicosanoic acid further produces a large amount of substances,such as the pro-inflammatory cytokines of prostaglandins,leukotrienes,thromboxanes,and platelet activating factors.These active substances,through their respective pathways,continue to induce the formation of more inflammatory factors,to form a cascade effect and promote the development of inflammation.Thus,damage factors,inflammatory cells,lipid mediators,cytokines and other cellular components and soluble molecules are linked by LP-PLA2,making LP-PLA2 a very critical active enzyme in the inflammatory system.Recent clinical prospective studies and epidemiological studies suggest that increased plasma LP-PLA2 quantity or activity is an independent risk factor for cardiovascular events.The main source of SAA is the liver.In the inflammatory response,including acute and chronic inflammation,the level of SAA is significantly increased.Recent studies have found that SAA is a new type of apolipoprotein,and it can exert an inhibitory effect on the HDL’s reverse cholesterol transport process,thereby increasing the lipid accumulation in the atherosclerotic lesions(AS).In the animal model of T2DM and metabolic syndrome,the possible receptor of SAA,Tanis,was found.It is suggested that SAA may be an intersection of inflammatory response,cardiovascular disease and type 2 diabetes mellitus.At present,there are a lot of researches about LP-PLA2 and SAA in the fields such as coronary heart disease,stroke,and diabetes.However,literature about LP-PLA2 and SAA in the field of diabetic microvascular are relatively rare.Therefore,our study focuses on the relationship between inflammatory markers and diabetic microvascular disease and its clinical significance.We will observe the levels of LP-PLA2 and SAA in the serum of patients with T2DM and DR,LP-PLA2 and SAA levels in the vitreous will also be monitored and explore the relationship of these two inflammatory factors with DR and its clinical significance.Materials and methodsPatients:A total of 160 T2DM patients,40 healthy subjects(control group 1)and 30 vitrectomy subjects(control group 2)were enrolled in this study.The subjects were divided into six groups:control group 1(n = 40),control group 2(n = 30),T2DM group(n = 64),non-proliferative diabetic retinopathy(NPDR)group(n = 46)and proliferative diabetic retinopathy(PDR)group(n = 50)and PDR group 2(n = 40).The control group 2 included 22 cases of idiopathic macular epiretinal membrane and 8 cases of idiopathic macular hole without systemic diseases who needed vitrectomy.PDR group 2 were the same patients in PDR group who needed vitrectomy.The vitreous fluids of 40 patients in PDR group 2 were collected and the LP-PLA2 and SAA of vitreous body were detected.All subjects did not have macrovascular disease,and the judgment and exclusion criteria for macroangiopathy were as follows:(1)Cerebrovascular diseases;including cerebral infarction,cerebral hemorrhage,transient ischemic attack and subarachnoid hemorrhage,confirmed by the health history inquiry,physical examination and cranial CT or MRI;(2)Coronary heart disease:except for other heart diseases,there was a history of typical myocardial infarction or angina,or asymptomatic but confirmed by electrocardiography or coronary angiography;(3)the neck vascular color Doppler examination showed intima arterial thickening was greater than or equal to 0.9mm.with endarterium calcification,plaque and stenosis;(4)Limb vascular disease:there was disappearance of dorsal arterial pulse,rest pain,intermittent claudication,or even foot gangrene or ischemic ulceration,and some were excluded of lower limb arterial plaque or occlusion by lower limb arterial ultrasound;Measurement factors:The patients were collected for venous blood in the fasting state in the early morning.The oxidase method was used to detect the fasting plasma glucose(FBG),the high-performance liquid chromatography was used to detect the glycated haemoglobin(HbAlc),and the colorimetric method was used to measure the total cholesterol(TC),triglyceride(TG),low density lipoprotein(LDL)and high density lipoprotein(HDL).Immune nephelometry was used to detect lipoprotein a(LP(a)).Serum samples were collected and subjected to competitive enzyme-linked immunosorbent assay(ELISA)to detect the LP-PLA2 and SAA levels,and the differences between groups were compared.The vitreous specimens were collected and the levels of LP-PLA2 and SAA were detected.The vitreous specimens were divided into two groups:control group2 and PDR group2.The control group 2 was 30 patients with idiopathic macular epiretinal membrane and idiopathic macular hole who met the inclusion criteria and had no systemic diseases,the PDR group2 was 40 patients who needed vitrectomy.Vitreous specimens were collected from vitreous dissection during vitrectomy,collecting about 1mL of undiluted vitreous gel and immediately placed at-80 C for cryopreservation.At the same time,urine was collected to detect the level of urine albumin.Electrocardiogram,chest radiograph,echocardiography,cervical vascular ultrasound Doppler,lower limb arterial Doppler ultrasound,brain CT and/or MRI examination were performed.Blood pressure,height,and body weight were measured,body mass index(BMI)was calculated based on height and body weight.We also inquired the patients about the health history,including coronary heart disease history.cerebrovascular disease history,diabetes history,family history,and smoking and drinking history.Results1、Comparison of general clinical data in four groups of patients:(1)The average age of patients in control group 1,T2DM group,NPDR group and PDR group was(44.3±10),(47.2±11),(48.7±11.5),and(52.4±7.5),respectively,and the difference between different groups was not statistically significant(P>0.05);the differences in gender,smoking history,drinking history and history of hypertension of different groups was not statistically significant too(P>0.05)(2)The average age of patients in control group 2 and PDR group 2 were(59.67±4.37)years old and(58.90±5.71)years old respectively.There was no significant difference between the two groups(P>0.05).2、Comparison of general clinical physical examination data of patients in four groupsSerum LP-PLA2 and SAA detection groups(1)The BMI in the control groupl,T2DM group,NPDR group and PDR group were(22.16±1.22)kg/m2,(22.70±1.36)kg/m2,(25.17±2.25)kg/m2 and(25.071±1.93)kg/m2,respectively.The differences between the control group and T2DM group,and between NPDR group and PDR group,were not significantly different(P>0.05).but comparing NPDR group and PDR group with the control group and T2DM group,there was significant difference(P<0.05).(2)Systolic pressure in the control groupl,T2DM group.NPDR group and PDR group were(126.56±11.34)mmHg,(129.67±9.45)mmHg,(132.22±10.25)mmHg and(134.67±9.56)mmHg,respectively.There was no significant difference between the groups(P>0.05).(3)Diastolic pressure in the control groupl,T2DM group,NPDR group and PDR group were(80.12±8.23)mmHg,(83.63±7.88)mmHg,(81.66±8.99)mmHg and(83.25±9.03)mmHg,respectively.There was no significant difference between the groups(P>0.05).Vitreous LP-PLA2 and SAA detection groups(1)The course of disease of PDR group 2 was(12.16±4.32)years.(2)BMI of control group 2 and PDR group 2 were(22.96±1.15)kg/m2 and(25.23±1.78)kg/m2 respectively.There was significant difference between the two groups(P<0.05).3、Comparison of clinical biochemical factors of patients in serum detection groups:(1)FBG、HbA1c and LP(a):Blood glucose level in the control groupl,T2DM group,NPDR group and PDR group were(4.36±0.37)mmol/L,(11.63±3.58)mmol/L,(10.80±3.38)mmol/L and(10.64±3.10)mmol/L,respectively.Compared with control group 1,the difference of FBG in the T2DM group,NPDR group and PDR group was statistically significant(P<0.05);however,between the three groups,there was no significant difference in FBG(P>0.05);The HbA1c level in the control group 1,T2DM group,NPDR group and PDR group were(4.84±0.44)%,(10.07±2.22)%,(9.60±1.77)%and(9.64±2.26)%,respectively.Compared with control groupl,the difference of HbAlc in the T2DM group,NPDR group and PDR group was statistically significant(P<0.05);however,between the three groups,there was no significant difference in HbAlc(P>0.05);The LP(a)level in the control groupl,T2DM group.NPDR group and PDR group were(104.72±46.74)mg/L,(159.73±81.66)mg/L,(259.48 + 180.12)mg/L and(348.17±280.02)mg/L,respectively.Compared with the control groupl,the difference of LP(a)in the T2DM group,NPDR group and PDR group was statistically significant(P<0.05);however,between the three groups,there was no significant difference in LP(a)(P>0.05);(2)TC、TG、LDL:The TC level in the control groupl、T2DM group、NPDR group and PDR group were(4.2 8±0.56)mmol/L,(4.48±1.36)mmol/L,(5.48±1.16)mmol/L and(5.86±1.51)mmol/L.The comparison between the control groupl and T2DM group showed no significant difference(P>0.05).Compared with the control groupl and T2DM group,the differences of TC in the NPDR group and PDR group were statistically significant(P<0.05),and there was no significant difference between NPDR group and PDR group(P>0.05);The TG level in the control group1,T2DM group,NPDR group and PDR group were(1.05±0.29)mmol/L,(1.57±0.55)mmol/L,(2.27±2.35)mmol/L and(2.38±1.42)mmol/L,respectively.The comparison between the control group 1 and T2DM group showed no significant difference(P>0.05).Compared with the control group1 and T2DM group,the differences in the NPDR group and PDR group were statistically significant(P<0.05),and there was no significant difference between NPDR group and PDR group(P>0.05);The LDL level in the control group1,T2DM group.NPDR group and PDR group were(2.47±0.47)mmol/L,(2.20±0.82)mmol/L,(3.21±0.83)mmol/L and(3.19±1.07)mmol/L.The comparison between the control group 1 and T2DM group showed no significant difference(P>0.05).Compared with the control groupl and T2DM group,the differences in the NPDR group and PDR group were statistically significant(P<0.05);and there was no significant difference between NPDR group and PDR group(P>0.05);(3)HDL:The HDL level in the control groupl,T2DM group,NPDR group and PDR group were(1.30±0.32)mmol/L,(1.24±0.29)mmol/L,(1.31±0.28)mmol/L and(1.43±0.43)mmol/L,respectively.There was no significant difference between the groups(P>0.05);(4)Urinary albuminThe urinary albumin level in the control groupl,T2DM group,NPDR group and PDR group were(7.18±3.20)mg/L,(10.52±4.59)mg/L,(33.71±24.40)mg/L and(98.65±56.86)mg/L,respectively.Compared with the control groupl and T2DM group,the differences in the NPDR group and PDR group were statistically significant(P<0.05),and there was significant difference between NPDR group and PDR group(P<0.05).4、LP-PLA2 levels in control groupl,T2DM group,NPDR group and PDR group were(59.81±8.26)μg/L,(96.91±21.71)±g/L,(114.08±14.72)±g/L and(134.96±21.38)μg/L,respectively.There were significantly differences between each two of the four groups(P<0.05)5、SAA levels in control group 1,T2DM group,NPDR group and PDR group were(0.77±0.58)mg/L,(1.29±0.46)mg/L,(1.60±0.39)mg/L and(2.75±0.57)mg/L,respectively.There were significantly differences between each two of the four groups(P<0.05).Simple linear regression showed that serum LP-PLA2 was correlated with SAA and the correlation coefficient was 0.938.6、Simple linear regression show that serum LP-PLA2 was correlated with course of disease(t=7.854,P<0.01),BMI(t=3.034,P<0.01),FPG(t=5.766,P<0.01),HbA1c(t=7.233,P<0.01),TG(t=3.186,P<0.01),CH(t=4.340,P<0.01),LDL(t=3.020,P<0.01),urine micro albumin(t=3.652.P<0.01),and LP(a)(t=3.794,P<0.01),and not correlated with age(t=1.015,P>0.05)and HDL(t=1.138,P>0.05)in T2DM patients.Furthermore,multivariate linear regression showed that course of disease(t=2.894,P<0.01),BMI(t=2.076,P<0.05),HbAlc(t=3.181,P<0.01),urine micro albumin(t=3.193,P<0.01)were significantly associated with serum LP-PLA27、Simple linear regression showed that serum SAA was correlated with BMI course of disease(t=3.025,P<0.05),(t=2.323,P<0.05),FPG(t=3.994,P<0.01),HbA1c(t=5.075,P<0.01),TG(t=2.292,P<0.05),TC(t=3.285,P<0.01),LDL(t=2.334,P<0.05),urine micro albumin(t=4.745,P<0.01),and LP(a)(t=3.847,P<0.01),and not correlated with age(t=1.015,P>0.05)and HDL(t=1.138,P>0.05)in T2DM patients.Furthermore,multivariate linear regression showed that course of disease(t=2.45,P<0.05),HbA1c(t=2.135,P<0.05),urine micro albumin(t=4.745,P<0.01)and LP(a)(t=2.242,P<0.05)were significantly associated with serum SAA.8.Clinical indicators of vitreous detection groups:(1)The levels of FBG in control group 2 and PDR group2 were(4.57±0.51)mmol/L and(10.47±2.67)mmol/L respectively.There was significant difference between the two groups(P<0.05).(2)The levels of HbAlc in control group 2 and PDR group 2 were(4.79±0.42)%and(9.90±2.00)%respectively.There was significant difference between the two groups(P<0.05).(3)The concentrations of LP-PLA2 in vitreous cavity of control group 2 and PDR group 2 were(0.67±0.09)ug/L and(1.28±0.12)ug/L respectively.There was significant difference between the two groups(P<0.05)(4)The concentration of SAA in vitreous cavity of control group 2 and PDR group 2 were(20.23±6.21)μg/L and(70.17±9.39)μg/L respectively.The difference was significant(P<0.05).(5)In PDR group 2,there was a correlation between intravitreal LP-PLA2 concentration and serum LP-PLA2 concentration,and the correlation coefficient was 0.610.(6)There was a correlation between SAA concentration in vitreous cavity and SAA concentration in serum in PDR group.The correlation coefficient was 0.445.(7)There was a correlation between LP-PLA2 concentration and SAA concentration in vitreous cavity,and the correlation coefficient was 0.710.Conclusions1、The levels of serum LP-PLA2 and SAA were significantly increased in NPDR and PDR patients.LP-PLA2 and SAA levels were increased with the aggravation of DR.and there was a significant correlation between LP-PLA2 and SAA;2、The level of serum LP-PLA2 was significantly correlated with course of disease,BMI,HbA1c and urinary albumin;3、The level of serum SAA was significantly correlated with course of disease,HbA1c.urine micro albumin and LP(a);4、Serum LP-PLA2 and SAA levels were associated with course of disease,obesity,glucose control,lipid and microvascular diseases,which may be involved in the occurrence and development of DR disease;detection of serum LP-PLA2 and SAA levels may provide the basis for early diagnosis and intervention of DR.5.The levels of LP-PLA2 and SAA in vitreous cavity of patients in PDR group 2 increased significantly.6.The levels of LP-PLA2 and SAA in vitreous cavity were significantly correlated with serum levels of LP-PLA2 and SAA in patients with PDR group 2.7.The elevated levels of LP-PLA2 and SAA in vitreous of patients in PDR group 2 further suggest that LP-PLA2 and SAA may be involved in the occurrence and development of DR. |
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