The Expression And Related Mechanisms Of Chitinase-3-like Protein 1 On The Failed Autologous Arteriovenous Fistula In End-stage Renal Disease

Backgrounds and aims:Chronic kidney disease patients receiving hemodialysis to treat end-stage renal disease(ESRD)are the important treatment in clinical practices,which have gradually increased worldwide.Autologous arteriovenous fistula(AVF)is the preffered access for most patients receiving maintenance hemodialysis,and associated with lower mortality and lower infection rates compared with the other two modalities of vascular access(central venous catheters and grafts)used for chronic hemodialysis.However,failed AVF is a major issue in the creation of functional hemodialysis vascular access.The relatively high failure of AVF limits its usage and stenosis from venous neointimal hyperplasia(NIH)is a common cause of AVF failure.Today,the underlying pathological mechanisms of NIH in the process of AVF progression are still poorly understood.There have been several studies investigating the molecular mechanisms responsible for NIH,such as inflammation,sheer stress and uremia which result in increasing the proliferation and migration of smooth muscle cells(SMCs),and eventually stenosis.Our preliminary study demonstrated the presence of myofibroblasts,SMCs and M?s within the neointima of the AVF outflow vein,which might be related to the process of AVF failure.Chitinase-3-like protein 1(CHI3L1)is a 40-kDa secreted glycoprotein,which is one member of the chitinase family,and was discovered as a heparin-binding protein that binds to chitin-like oligosaccharides.CHI3L1 is normally expressed by a number of different cell types including macrophages(M?s),neutrophils,and vascular smooth muscle cells(SMCs).CHI3L1 is defined as a multifunctional secreted protein,can promote cell proliferation and differentiation.Previous studies suggested that serum CHI3L1 concentrations have been elevated and can also independently predicts all-cause mortality in uremic patients.However,the impact of CHI3L1 on the early failure of AVFs in uremic patients remains unknown.According to our preliminary study,the aims of these studies are demonstrated as follows:Part ?:To evaluate the clinical outcomes of the creation of new AVF and conduct Cox proportional hazards analyses to explore the risk factors associated with the failure of AVF.Part ?:To explore the impact of CHI3L1 on the early failure of AVF through aprospective cohort study Part ?:To explore the pathological study of autologous arteriovenous fistulas in end-stage renal disease patients;and second we conducted a study to establish a novel approach to create aortocaval fistulas(ACF)in adenine-induced renal failure rats to study the NIH in the inferior vena cava,and to explore the expression and related mechanism of the CHI3L1 in neointimal hyperplasia of autologous arteriovenous fistulaMaterials and methods:Part ?:418 ESRD patients received a primary AVF creation were enrolled from January 2013 to June 2016 in this single-center retrospective cohort study Demographic characteristics(age,sex and use of prescription drugs),primary renal diseases,comorbidities(hypertension,diabetes and cardiovascular disease),and history of AVF creation at baseline were recorded.Primary patency rates of AVF was evaluated using the Kaplan Meier method,and the log-rank test was used for differences between the groups.Next,we confirmed the proportional hazard assumption and conducted Cox proportional hazards analyses for risk factors associated with the failure of AVFPart ?:We conducted a prospective observational cohort study in 109 uremic patients(the mean age was 53.2±14.7 years,67.9%of them were males).Patients received forearm AVFs surgery were consecutively enrolled with a median follow-up time of 15 months.The early failure was defined as a fistula that never developed adequately for dialysis use or that failed within the first 3 months of use.Serum CHI3L1 concentration was determined by ELISA.The receiver operating characteristic(ROC)curve was plotted and applied for evaluating CHI3L1 and the failure of AVF.Optimal cutoff values were calculated as described.AVF survival and time-to-event analysis was estimated by the Kaplan Meier and differences were evaluated with a stratified log-rank test.Next,we confirmed the proportional hazard assumption and conducted Cox proportional hazards analyses for risk factors associated with the failure of AVFPart ?:A 5-10mm segment of vein immediately adjacent to that the portion of the vein used for fistula creation was surgically removed at the time of fistula creation and reconstruction of the failed fistula from patients,which was explored by the pathological study.Twenty adult female rats were selected,among which 10 healthy rats served as controls and the rest received a 0.75%adenine-rich diet(AD)for 4weeks to induce renal failure and underwent ACF surgery.Serum creatinine and urea nitrogen were monitored to assess renal function.ACF was assessed using duplex scan(until for 6 weeks after surgery)and histopathological analyses.Results:Part ?:(1)The mean age was 54.5±14.5 years(range from 18 to 87 years),and 59.8%were males.The primary cause of ESRD was chronic glomerulonephritis(39.0%);(2)Male patients had higher levels of hemoglobin,serum albumin,creatinine,uric acid and also had higher percentage of diabetes than females,respectively(p<0.05).The patencies of AVF were 85.6%,79.7%,75.1%,73.2%?73.2%at 12,24,36,48 and 60 months,respectively.Males had better patency rates than females.Compared with older patients(age>65years),younger patients(<65years)had better patency rates(P<0.05);(3)We confirmed the proportional hazard assumption and conducted Cox proportional hazards regression analyses for risk factors associated with AVF failure.After adjusting for potential confounders,age(OR 1.19,95%CI,1.05-1.35)and D-dimer(OR 1.07,95%CI,1.02-1.12)were independent predictors of AVF failure;(4)Publised papers demonstrated that the level of D-dimer was associated with the CHI3L1,which implied that the CHI3L1 might be related to the failure of AVF.Part ?:(1)Among 109 patients,24 patients had AVF failure.The optimal cutoff value based on the receiver operating characteristics analysis of CHI3L1 was 122.6ng/mL,with the area under the curve of 0.73(p=0.001);(2)The Kaplan-Meier survival analysis demonstrated that patients with CHI3L1<122.6 ng/mL had better patencies of AVFs than patients with CHI3L1>122.6 ng/mL(Log-rank test,p=0.001);(3)Multivariable Cox proportional hazards analysis showed that baseline CHI3L1(? 122.6 ng/mL vs.<122.6 ng/mL)was significantly associated with AVFs failure,after adjusting for confounders(adjusted hazard ratio[HR]3.67;95%Cl 1.44-9.36)Part ?:(1)Veins removed at the time of reconstruction of the failed fistula of the patient demonstrated that the eccentric neointima formation is irregularly thickened,with several small vessels within a more cellular region of the neointima.The EVG staining suggested the internal elastic lamina is disrupted.At the end of experiment,AD rats showed higher serum creatinine and urea nitrogen,which were 0.80±0.47 mg/dL vs.0.65±0.26 mg/dL(p=0.39)and 34.7(27.5-98.2)mg/dL vs.24.9(20.9-27.3)mg/dL(p=0.005)compared with vehicle-treated rats,respectively;(2)Remarkable histological changes of kidney tissues were characterized by interstitial inflammatory infiltrate,crystalline tubulointerstitial deposits,interstitial fibrosis,vascular injuries,and cellular atrophy at proximal and distal renal tubules.Sections of the ACF demonstrated that the eccentric neointima formation is irregularly thickened,with several small vessels within a more cellular region of the neointima.The EVG staining suggested the internal elastic lamina is disrupted.Although most cells within the region of neointimal hyperplasia appear to be myofibroblasts,which are desmin-negative,SMA-positive and vimentin-positive,there also are some contractile smooth muscle cells(SMCs)being SMA-positive and desmin-positive,as well as macrophages(M?)within the neointima,which is PGM-1-positive;(3)GEO data analysis showed significant M2-type M? infiltration in animal models of AVF tissue,and M2-type M? immune infiltration was significantly correlated with upregulated CHI3L1.This study also found that the expression of CHI3L1 was significantly increased in the tissues of patients with AVF loss,which was mainly both located in M2-type Mcp and SMCsConclusions:Part ?:This study demonstrated that the failure rate of AVF at the first and the second year were 14.4%and 21.3%,moreover,the failure rate of AVF at the fifth year was reached up to 26.8%,which further confirms the importance of intensive examinations for the early detection of clarifying risk factors to prevent the occurrence of AVF failure;After adjusting for potential confounders,age and baseline D-dimer were independent predictors of AVF failure.To date,there have been many studies to testify the relationship between the inflammatory status(such ad the CHI3L1)and the D-dimer.So the study showed that CHI3L1 might be related to the failure of AVFPart ?:The cohort study demonstrated that increased serum CHI3L1 at baseline is independently associated with the risk of the early failure of forearm AVF.Part ?:Experimental renal failure animal models have been established and ACFs were also successfully created in adenine-induced renal failure rats;Our adenine-induced renal failure rat models with ACF showed typical features of NIH in the formation of fistula stenosis,which strongly resemble clinical findings in uremic patients.This animal model might be applied for studing the new therapeutic strategies,the biological mechanisms responsible for AVF failure precisely;This study demonstrated that the CHI3L1 might mediate M2 Mcp polarization and interact with the SMCs in NIH of AVF in uremic patients.