| BackgroundAs a common complication of the acute coronary syndrome(ACS),acute kidney injury(AKI)is closely related to the prognosis of ACS,forming a vicious circle.Therefore,early detection of AKI in high-risk AKI populations is of great significance in ACS patients.Clinically,serum creatinine(Scr)and urine output are used as the main tools to diagnose AKI.However,changes in Scr do not reflect kidney function in real-time.Urine output,on the other hand,is more susceptible to non-nephrogenic factors such as volume and medications.Increased Scr lags behind a decrease in glomerular filtration rate(GFR).Therefore,in acute settings,Scr concentration and urine output are delayed and unreliable indicators of renal dysfunction.Therefore,the validation of novel AKI biomarkers may help identify high-risk patients at a very early stage and perform the preventive treatment to minimize further kidney injury.Neutrophil gelatinase associated lipocalin(NGAL)and calprotectin are two novel AKI early diagnostic biomarkers.Studies have shown that serum NGAL can predict the occurrence of hemodialysis after coronary angiography in high-risk ACS patients and is also a good biomarker for the diagnosis and prognosis of AKI in patients with sepsis,intensive care patients,or emergency patients.NGAL is expressed at a very low constant level in different tissue types.After the occurrence of AKI,NGAL expression is significantly upregulated and plasma NGAL levels are significantly increased,followed by a significant decrease in plasma NGAL levels with the improvement of renal function.The more severe the AKI,the higher the plasma NGAL level.Serum calprotectin is also a good biomarker of AKI in critically ill surgical patients.In patients with sepsis in intensive care,serum calprotectin is significantly higher in patients with sepsis AKI than in non-AKI patients,and serum calprotectin can early predict the occurrence of sepsis AKI.At the same time,plasma calprotectin level immediately after surgery is a good biomarker for AKI in cardiac surgery patients with extracorporeal circulation.Patients with AKI within 7 days of cardiac surgery have significantly elevated postoperative calprotectin levels,and plasma calprotectin levels immediately after cardiac surgery predict the occurrence of AKI and are not age-sensitive.Although previous studies have shown that NGAL and calprotectin are good biomarkers for early diagnosis of AKI such as sepsis,critical illness,and post-cardiac surgery,it is still unclear whether plasma NGAL and calprotectin can be used as early biomarkers for ACS-AKI,which has a different pathogenesis mechanism with sepsis,critical illness,and post-cardiac surgery.The main objective of this study was to evaluate the role of plasma NGAL and calprotectin in the early diagnosis of ACS-AKI and the value of the combined application of plasma NGAL and calprotectin in the early diagnosis of ACS-AKI.Objectives(1)Screening of risk factors for ACS-AKI and their correlations with plasma calprotectin and NGAL;(2)The value of single parameter plasma calprotectin or NGAL in the early diagnosis of ACSAKI;(3)The value of the combined application of both plasma calprotectin and NGAL in the early diagnosis of ACS-AKI.Subjects and methodsA total of 172 patients with ACS admitted to the coronary care unit of Yuhuangding Hospital in Yantai City were prospectively admitted.Among them,110 were male(64%)and 62 were female(36%).The study was approved by the Ethics Committee of Yantai Yuhuangding Hospital.All enrolled patients received Scr examination at the time of admission and daily after admission.AKI is defined according to the acute kidney injury network(AKIN)criteria as a sudden(48-hour)increase in serum creatinine greater than or equal to 0.3 mg/dL,an increase in serum creatinine percentage greater than or equal to 50%(a 1.5-fold increase from baseline),or the need for renal replacement therapy.Inclusion criteria:age of more than 18 years old,confirmed diagnosis of acute myocardial infarction with ST-segment elevation(STEMI),non-ST elevation myocardial infarction(NSTEMI),or unstable angina pectoris(UA)admitted within 48 hours after the onset of symptoms.After admission,the patients were initially excluded if they had a history of chronic kidney disease requiring chronic peritoneal or hemodialysis treatment,renal transplantation,inflammatory bowel disease,malignancy,infection,hepatic diseases,thyroid diseases,pulmonary diseases,or auto-immune diseases at the time of inclusion or under treatment with antiinflammatory drugs.Informed consent was obtained before enrollment.Patients were assigned to either the AKI or no-AKI group based on the AKI diagnosis.The collected clinical data included(1)basic information including age,sex,ACS types,and blood pressure at admission;(2)a history including hypertension,diabetes mellitus,hyperlipidemia,smoking,proteinuria,and previous medication;(3)laboratory data and auxiliary examinations at admission,such as levels of B-type natriuretic peptide(BNP),white blood count(WBC),hemoglobin(Hb),creatine kinase-MB(CK-MB),troponin-I,lactate dehydrogenase(LDH),lowdensity lipoprotein(LDL)cholesterol,total cholesterol,triglycerides(TC),and Scr were performed by the hospital central.laboratory.Ejection fraction(EF)was obtained by color doppler echocardiography.Blood samples for calprotectin and NGAL tests are obtained as soon as possible at the time of admission(within 6 hours)and the determination of plasma calprotectin and plasma NGAL is carried out using the enzyme-linked immunosorbent assay kit(ELISA).Results1.Clinical characteristics of patients and the prevalence of AKI172 ACS patients(158 had angiography or percutaneous coronary intervention during hospital stay)consisting of 72 patients with STEMI,35 patients with NSTEMI,and 65 patients with UA were included in the study.23 patients(STEMI,N=16;NSTEMI,N=6;UA,N=1)had a diagnosis of AKI.The prevalence of AKI was 13.4%in this study.The majority of the AKI patients had stage 1 kidney injury(87%)whereas none of the patients required dialysis during hospitalization.2.General clinical characteristics between the AKI group and non-AKI group were balancedNo differences were found between the AKI group and the no-AKI group regarding age,gender,hypertension,diabetes mellitus,hyperlipidemia,previous medication,proteinuria,angiography or percutaneous coronary intervention during the hospital stay,CK-MB,troponin I,and BNP on admission.3.Compared with the non-AKI group,the proportion of STEMI patients was higher in the AKI groupCompared with the non-AKI group,the proportion of STEMI patients was higher(69.6%vs 37.6%,P=0.006),while the proportion of UA was lower(4.3%vs 42.9%,P<0.001)in AKI patients,suggesting that STEMI patients were more likely to develop AKI than NSTEMI and UA.4.Compared with the non-AKI group,the GRACE score was higher in the AKI groupThe mean GRACE score was higher in the AKI group compared to the non-AKI group(144.25±28.54 vs 115.47±34.93,P=0.027),and similarly,the proportion of GRACE high-risk stratification in the AKI group was higher(56.5%vs 20.1%,and P<0.001).The above results suggested that ACS patients with high-risk stratification are more likely to develop AKI than ACS patients with low-risk stratification.5.The AKI group had a worse renal function in hospital admission than the non-AKI groupCompared with the non-AKI group,the AKI group had a higher Scr at admission(106.50±18.14 vs 72.07±13.59 μmol/L,P<0.001),and a lower eGFR at admission(54.84±14.02 vs 88.65±18.68 mL/min,P<0.001),suggesting that patients with previously impaired renal function are more likely to develop AKI.6.The AKI group had a higher level of inflammation than the non-AKI groupCompared with the non-AKI group,the LDH(960.56±943.36 vs 475.24±438.23 U/L,P=0.014),WBC(11.98±3.89 vs 8.74±3.97×109/L,P=0.041)were significantly higher,suggesting that the AKI group had a higher level of inflammation than the non-AKI group.7.The heart function in the AKI group was worse than non-AKI groupCompared with the non-AKI group,the EF group was lower(53.57±11.07%vs.62.27±5.92%,P=0.003),indicating that the heart function in the AKI group was worse.8.Plasma calprotectin and NGAL were higher in the AKI group than in the non-AKI groupThe comparison of plasma calprotectin and NGAL between the AKI group and the non-AKI group showed the AKI group had higher plasma calprotectin(5942.26±1955.88 ng/mL vs.3210.29±1833.60 ng/mL,P<0.001)and plasma NGAL(164.91±43.63 ng/mL vs.122.48±27.33 ng/mL,P<0.001).9.Determinants of ACS-AKIThe GRACE score risk stratification,plasma calprotectin,plasma NGAL,admission eGFR,and STEMI were associated with AKI according to the univariate analysis.Plasma calprotectin(OR=1.001;P=0.007)and plasma NGAL(OR=1.040;P=0.002)levels were independently associated with AKI according to the multivariate analysis.Besides,GRACE score risk stratification and STEMI were also independent risk factors of AKI.10.Plasma calprotectin and NGAL as biomarkers of ACS-AKIThe results of the area under the ROC curve for AKI recognition by plasma calprotectin,NGAL,and admission Scr showed that the two plasma biomarkers,calprotectin and NGAL,had significant early recognition ability for AKI(AUC calprotectin 0.864,P<0.001;AUC NGAL 0.850,P<0.001),and both are superior to Scr(AUC 0.778,P<0.001).The sensitivity of calprotectin was 88.9%and the specificity was 76.8%.The cut-off value of calprotectin was 4506.62 ng/mL.NGAL has a sensitivity of 77.8%,a specificity of 80.4%,and a cut-off value of 135.69 ng/mL for early recognition of ACS-AKI.11.Combined application of plasma calprotectin and NGAL was better to detect ACS-AKI than single calprotectin or NGAL index aloneThe combined application of calprotectin and NGAL has an AUC of 0.898 for ACSAKI(P<0.001),which was over than the AUC of both calprotectin and NGAL,suggesting that the combination of calprotectin and NGAL has a better ability to early detect AKI than single calprotectin or NGAL index alone.The positive and negative predictive values of combined application of plasma calprotectin and NGAL were 0.44 and 0.98,respectively.ConclusionThis study shows that plasma calprotectin and NGAL can be used as biomarkers for early diagnosis of ACS-AKI,and the combined application of the two biomarkers can better identify AKI than a single biomarker.BackgroundAcute coronary syndrome(ACS)is a commoB type of acute cardiovascular disease that seriously endangers human health.Acute kidney injury(AKI)is one of the common complications of ACS.The incidence of ACS-associated AKI(ACS-AKI)is about 12.0% to 37.0%.Worsening of renal function can further exacerbate cardiac dysfunction and create a vicious cycle,increasing the cost of treatment and seriously affecting the prognosis of ACS patients.It is of great clinical significance to study the pathogenesis of ACS-AKI,explore its early diagnosis methods,and explore optimized prevention and treatment measures.Currently,calprotectin is one of the biomarkers for early detection,differential diagnosis,and prognostic evaluation of AKI.Previous studies and our previous clinical studies have found that plasma calprotectin is associated with ACS-AKI,and calprotectin is superior to traditional indicators such as serum creatinine(Scr)and blood urea nitrogen(BUN)as an early recognition biomarker of ACS-AKI.Calprotectin,an isodimer of S100 protein family members S100A8 and S100A9,is an activator of the innate immune system,expressed primarily on the surface of cells such as neutrophils,monocytes,and early differentiated macrophages.Calprotectin has been shown to induce cytoskeletal recombination,chemotacticization,and cytokine expression.In the case of renal injury,tubular epithelial cells can release calprotectin to the extracellular as an injury-related mode molecule,binding to cell surface receptors including toll-like receptors 4 and higher glycosylation end-product receptors,thereby activating immune effector cells,participating in pathophysiological processes such as neutrophil recruitment,inflammatory factors and adhesion molecules induction,promoting the development of kidney injury.Recent studies have shown that calprotectin in ischemia-reperfusion kidney damage of rats can promote inflammatory cell infiltration of renal tissue,which in turn induces the expression of inflammatory molecules,resulting in tubular epithelial cell damage.Calprotectin plays an important regulatory role in macrophage-mediated AKI and can promote renal parenchymal damage and renal fibrosis.Calprotectin can also induce loss of connections between endothelial cells,triggering subsequent cell death.Calprotectin can mediate AKI caused by contrast media through the toll-like receptor 4 signaling pathway and cause apoptosis of tubular epithelial cells,which in turn causes renal fibrosis,but the specific mechanisms for calprotectin participating in the occurrence and development of ACS-AKI are unclear.CD36 belongs to the B scavenger receptor,which is a single-stranded glycoprotein on the surface of the cell membrane that is widely found in monocytes,platelets,endothelial cells,and adipose cells.CD36 is one of the cell surface receptors of calprotectin and produces different biological effects under different pathological and physiological conditions.At present,it has been found that CD36 plays important role in the occurrence and progression of various kidney diseases.Renal CD36 is mainly expressed in the proximal and distal tubular epithelium,podocytes,mesangial cells,microvascular endothelial cells,and interstitial macrophages,and is significantly upregulated in acute and chronic kidney disease.Podocyte-expressed CD36 may cause glomerulosclerosis and proteinuria,and CD36 expressed by the proximal tubules of the kidney may play a role in tubule interstitial fibrosis.In experimental models,antagonist blockade or CD36 gene knockout prevented kidney injury.Glycosylated albximin and free fatty acids induce increased expression of CD36 in proximal tubular epithelial cells,followed by sequential activation of kinase Src,apoptosis factor mitogen-activated protein kinase(MAPK),p38,and caspase 3,leading to apoptosis of tubular epithelial cells,which further promote tubular degeneration and renal interstitial fibrosis.In summary,we proposed that calprotectin is involved in the occurrence,and development of ACS-AKI through the CD36 pathway.To verify this hypothesis,we designed the study:(1)Establish the ACS-AKI mouse models by ligating the anterior descending branch of the coronary artery in mice,determine whether calprotectin is involved in ACS-AKI through the CD36 pathway,and preliminarily explore its regulation of ACS-AKI downstream signaling pathways;(2)Taking tubular epithelial cells as the research object to study whether calprotectin is involved in the regulation of CD36 and its downstream signaling pathway Src-p38-caspase 3.The result may provide a theoretical basis for elucidating the heart-kidney interaction mechanism of ACSAKI and exploring targeted prevention and treatment methods.Objectives(1)To explore whether calprotectin is involved in the occurrence and development of ACSAKI by regulating the CD36 signaling pathway;(2)To explore the role of calprotectin in the regulation of CD36 in AKI;(3)To explore the effect of CD36 gene interference on the regulation of AKI by calprotectin;(4)To explore the possible signal transduction mechanism of calprotectin in regulating ACSAKI through CD36.Materials and methods1.Animal experiment part1.1Laboratory animalsThe experimental animals selected 24 healthy male C57BL/6 mice(22-25 g)aged 8-12 weeks old in SPF class.All mice are pre-adapted at the Animal Experiment Center of Binzhou Medical College for more than 2 weeks before the experiment.1.2Experimental animal grouping(1)Control group(control,n=12): C57BL/6 mice were bred for 2 weeks and then performed pseudo-myocardial infarction surgery,and were reared for 72 hours after surgery.(2)Acute myocardial infarction combined with acute kidney injury group(ACS-AKI,n=l2):C57BL/6 mice were bred for 2 weeks and then ligation of the left anterior coronary descending coronary artery was performed to establish a model of myocardial infarction combined with acute kidney injury,and then the surviving mice were reared for 72 hours for observation.Confirmation of the model was performed by measuring Scr and BUN.1.3Preparation of animal models of acute myocardial infarction with acute kidney injury in miceAccording to the literature guidance,a model of acute myocardial infarction with acute kidney injury in mice by surgical ligation of the left coronary artery anterior descending branch was established.The sham sxirgery group only opened the chest without ligation of the coronary artery,and the rest of the steps were the same.1.4Experimental arrangementAll mice were sacrificed to blood collection and renal tissue specimens after anesthesia 72 h postoperatively,some kidney tissues were subjected to pathological biopsy,some kidney tissues were stored in liquid nitrogen tanks for related protein detection,and some specimens were HEstained after paraffin embedding.Plasma retention was to be measured by Enzyme-linked immunosorbent assay(ELISA)for plasma calprotectin and sCD36.1.5The automatic biochemical analyzer determines the blood Scr,BUN,and other contents of mice to verify whether the model is successfulBlood Scr,BUN,and other content were measured by the automatic biochemical analyzer.1.6Helium heliothecin staining(HE staining)HE staining was used to observe the kidney structure changes in the control group and ACSAKI group.1.7ELISA method to detect the expression of calprotectin and CD36 protein in the plasma of ACS-AKI mice and control mice.(1)Preparation method of plasma to be measured: Take 0.5 ml of blood from the tip of the heart to the EDTA anticoagulant tube,gently shake the anticoagulant tube several times to make it mix evenly,centrifuge at 4 ℃ at low-temperature centrifuge(1600 g,15mins),take the supernatant and place in the-80℃ refrigerator to be tested;(2)Preparation of ELISA standards and standard operating instructions are carried out regarding the instructions.1.8Western Blot Technology to detect CD36,calprotectin,p-Src,p-p38,and cleaved caspase3 protein expression in the renal tissue lysate of ACS-AKI mice and control mice.2.Cell experimentsThe experiment cell was a human renal tubular epithelial cell line(HK-2),and the resuscitation,passage, cryopreservation,and plate transfer were carried out according to the usual steps for the next processing.2.1 Experimental processing(1)Cell transfectionHK-2 cells grown to log-stage were seeded into 6-well cell culture plates at concentrations of 2×l05/ml,adding 2 ml of cell suspension per well and culturing overnight.Transfection was carried out according to the control group(empty liposome transfection group),siRNA-NC group(NC-siRNA transfected 100 nmol/L),CD36-siRNA group(transfection of CD36-siRNA 100nmol/L),and the transfection complex was formed after standing for 20 min at room temperature.Take 500μl of the transfection complex and add it to the cells,place in a 37 ℃,5% CO2 incubator for 6 h,and replace the cell culture medium to continue culture;(2)Evaluation of the effect of interference CD36 gene in transfected cellsThe total protein in the cells was extracted according to the steps of the cell protein extraction kit,and the CD36 protein expression of each group of cells was determined.2.2Experimental groupingTransfected and non-transfected HK-2 cells were incubated with 25μg/mL and 50μg/mL of calprotectin for 24 h,respectively.The following experimental groupings were performed after treatment:a)Control group(empty liposome transfection group);b)Calprotectin incubation group(25μg/mL);c)Calprotectin incubation group(50μg/rnL).d)CD36-siRNA + calprotectin(50μg/mL)group;e)CD36-siRNA groupLabel each group on the culture plate and continue the culture for 24 h after proceeding to the next experiment separately.2.3CCK-8 detects HK-2 cell proliferationEach group of cells was seeded into a 96-well cell culture plate at a density of 200μl per well at a density of 3000/ml,the cells adhered to the wall for 24 h,the supernatant was aspirated,and then 200μl of the serum-free medium was added for another 24 h to synchronize the cells.Add each group of cells according to the group,set up 6 repeat wells per group,and after incubating in an incubator at 37 ℃,5% CO2 for 48 h,add 10 pi of CCK-8 reagent to each well After 4 h incubation at 37℃5 the microplate reader assays and records the absorbance OD values of each group at a wavelength of 490 nm to calculate the cell proliferation rate.2.4Flow cytometry to detect apoptosis of HK-2 cellsPipette 100μL of the sample into a flow cytometry tube,then add FITC-Annexin V and propidium iodide(PI)5 μL/tube to the tube and incubate in a dark room at room temperature for15 min.After that,add 400 μL of 1 ×binding buffer per tube,mix well,and terminate the reaction.Hands-on assay within 20 min,1× 104 cells are charged in the set gate,and the results are analyzed using software Flow jo 10.2.5 Western blotting detects phosphorylation of p38,p-Src,cleaved caspase3 expression Results1. The renal function index of ACS-AKI mice was significantly increased,suggesting that the modeling of ACS-AK1 mouse model was successfulCompared with the normal control group,the blood clearance BUN and Scr values of mice in the ACS-AKI group were significantly increased(P<O.Ol),which confirmed that ACS-AKI mouse modeling was successful.2. Obvious pathological manifestations of kidney damage occurred in the renal tissue structure of ACS-AKI miceHE staining of mouse kidneys modeled showed significant changes in the structure of the kidneys in the ACS-AKI mouse model-The renal tubular epithelial cells disintegrated and cell debris was visible in the lumen.Some parts of the tubular basement membrane were exposed.The manifestations were consistent with acute tubular necrosis.3. The expression of plasma calprotectin and sCD36 in ACS-AKI mice increased significantlyPlasma calprotectin and sCD36 expression in the normal control group and ACS-AKI mice were detected by the ELISA method,and the results showed plasma calprotectin and sCD36 in ACS-AKI significantly increased(P<0.01).4. The expression of CD36,calprotectin,p-Src,p-p38,and cleaved caspase 3 in the kidney tissues of mice in the ACS-AKI group were significantly upregulatedCompared with the control group,the expression of CD36,calprotectin,p-Src,p-p38,and cleaved caspase 3 in the renal tissue of mice of the ACS-AKI group was significantly increased(P<0.05).5. Detection of CD36-siRNA interference effect of renal tubular epithelial cellsCompared with the control group,there was no significant difference in CD36 protein expression level in the siRNA-NC group(P>0.05).The expression level of CD36 protein in the CD36-siRNA group decreased significantly compared with the control group and the siRNA-NC group(P<0.05).Suggests that tubular epithelial cell’s CD36-siRNA interference is successful.6. Calprotectin stimulation can upregulate the expression of CD36 protein in human renal tubular epithelial cells in a dose-dependent mannerAfter incubating human tubular epithelial cells at 25μg/ml and 50μg/ml concentrations of calprotectin for 24 h, the western-blot method was used to detect the expression of CD36 protein in human tubular epithelial cells,and the results showed 25μg/ml and 50μg/ml concentration of calprotectin incubation can lead to a significant increase in CD36 protein expression in human tubular epithelial cells(P<0.05).Compared to 25μg/ml concentrations of calprotectin incubation,50μg/ml concentration of calprotectin incubation can lead to a further increase in CD36 protein expression in human tubular epithelial cells(P<0.05).That may mean that calprotectin stimulation can upregulate the expression of CD36 protein in human renal tubular epithelial cells in a dosedependent maimer.7. Calprotectin stimulation can inhibit the proliferation of human renal tubular epithelial cells and promote apoptosis in a dose-dependent mannerThe tubular epithelial cells were grouped as the control group,the 25μg/ml calprotectin incubation group,the 50μg/ml concentration calprotectin incubation group,the CD36-siRNA group,and the CD36-siRNA+50μg/ml concentration calprotectin incubation group.The cell proliferation results of each group using the CCK-8 detection kit showed that the cell survival rates of both calprotectin incubation groups were lower than that of the control group,and the high concentration calprotectin incubation group was additional lower(P<0.05).Apoptosis was detected by flow cytometry in each group and the result showed that with the increase of calprotectin stimulation concentration,the apoptosis of human tubular epithelial cells increased(P<0.01).That may mean that calprotectin stimulation can inhibit the proliferation of human renal tubular epithelial cells and promote apoptosis in a dose-dependent manner.8. Effect of CD36 gene interference on apoptosis of human renal tubular epithelial cellsThere was no significant difference in cell proliferation rate and apoptosis rate between the CD36-siRNA group and the control group(P>0.05).9. The interference of the CD36 gene partially inhibited the role of calprotectin in regulating the proliferation and apoptosis of HK-2 cellsThe cell survival rate of the CD36-siRNA+ calprotectin stimulating group was lower than that of the control group(P<0.05),but significantly higher than that of the calprotectin stimulation group alone(P<0.05).The apoptosis rate in the CD36-siRNA+calprotectin stimulating group was higher than that in the control group(P<0.05),but significantly lower than in the calprotectin stimulation group alone(P<0.05).That may mean that the interference of the CD36 gene partially inhibited the role of calprotectin in regulating the proliferation and apoptosis of HK-2 cells.10. Calprotectin stimulation upregulates the protein expression of phosphorylation of Src,p38,cleaved caspase 3 in HK-2 cellsHK-2 cells were grouped into control groups,50μg/ml concentration calprotectin incubation group,CD36-siRNA group,and CD36-siRNA+50μg/ml concentration calprotectin incubation group.Western-blot detected CD36 downstream signaling factors phosphorylated Src,p-p38,and cleaved caspase 3 protein expression and the results showed that compared with the control group,the expression of p-Src,p-p38;and cleaved caspase 3 proteins of 50μg/ml concentration calprotectin incubation group was significantly upregulated(P<0.05).Calprotectin stimulation might upregulate the protein expression of phosphorylation of Src,p38,and cleaved caspase 3 in HK-2 cells.11. The Interference of the CD36 gene partially inhibited the upregulation of calprotectin on the expression of the downstream signaling factors p-Src,p-p38,and caspase3 proteinsCells were grouped into control groups,50μg/ml concentration calprotectin incubation group,CD36-siRNA group,CD36-siRNA+50μg/ml concentration calprotectin incubation group.Western-blot detected CD36 downstream signaling factors phosphorylatedp38, p-Src,and cleaved caspase 3 protein expression,and the results showed that phosphorylated p38,p-Src, and cleaved caspase 3 protein expressions were less in CD36-siRNA+50μg/ml concentration calprotectin incubation group than in 50μg/ml concentration calprotectin incubation group,but higher than the control group(P<0.05).The Interference of the CD36 gene may partially inhibit the upregulation of calprotectin on the expression of the downstream signaling factors p-Src,p-p38,and cleaved caspase 3 proteins.Conclusion1.The expression of renal calprotectin,CD36,and downstream signaling protein Src-p38-caspase 3 in ACS-AKI mice was significantly increased;2.Calprotectin can dose-dependently upregulate the protein expression of tubular epithelial cells CD36 and its downstream signaling factors p-Src,p-p38,and cleaved caspase 3,and promote apoptosis of tubular epithelial cells.CD36 gene interference can inhibit the pro-apoptosis effect of calprotectin on renal tubular epithelial cells,and at the same time inhibit the upregulation effect of calprotectin on the protein expression of downstream signaling factors p-Src,p-p38,and cleaved caspase 3;3.Calprotectin may be involved in the occurrence and development of ACS-AKI by regulating CD36 and its downstream Src,p38,and caspase 3 signaling pathway;4.CD36 gene interference does not completely inhibit the promoting effect of calprotectin on apoptosis of tubular epithelial cells,while it cannot completely inhibit the upregulation effect of calprotectin on the Src-p38-caspase 3 signaling pathway,which suggests that calprotectin may have other mechanisms for regulating ACS-AKI. |
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