The Relationship Between TIMP-1, TGF-β1, OPN In IgA Nephropathy With Tubulointerstitial Lesions

BackgroundIgA nephropathy（IgAN）is a common primary glomerular disease in the clinic.It is currently the leading cause of maintenance dialysis patients in China and brings a heavy burden on families and society.Its pathological features include diffuse proliferation of mesangial cells and accumulation of extracellular matrix.Most of the previous clinical studies focused on the relationship between glomerulosclerosis and progression of renal failure in IgA nephropathy,and there are few studies on renal tubulo-interstitial injury in IgA nephropathy.It has now been found that renal tubulo-interstitial lesions are an important feature of various glomerular diseases,which greatly affect the prognosis of patients.Tissue inhibitor of metalloproteinase-1（TIMP-1）is a specific inhibitor of matrix metalloproteinases.Numerous studies have shown that TIMP-1 causes ECM accumulation by inhibiting the degradation of the extracellular matrix（ECM）.Compared with normal controls,TIMP-1 expression was significantly higher in renal fibrosis patients.Previous studies have shown that there is a significant positive correlation between serum TIMP-1 levels and glomerulosclerosis ratio.Transforming growth factor-β1（TGF-β1）is a key member of a large family of multifunctional molecules that can exert diverse biological activities.Multiple signal pathway transduction pathways may be used to regulate biological processes such as cell differentiation,apoptosis,and proliferation.TGF-β1 mediates renal interstitial fibrosis and glomerulosclerosis by promoting synthesis of extracellular matrix,deposition of extracellular matrix,and promotion of mesangial cell proliferation.Osteopontin（OPN）is a multifunctional protein.It plays an important role in cell aggregation,adhesion,and inflammation.Previous studies have shown that OPN expression can increase in either primary glomerular disease or secondary glomerular disease.At present,the pathogenesis of IgAN is not yet clear.Most previous studies have found that it may be related to the abnormal glycosylation of IgA.The pathological manifestations of patients with IgAN are different,pathological changes are diverse,and the prognosis is not the same.Most studies have shown that the damage of tubulo-interstitium is related to the prognosis of IgAN.Therefore,more studies are needed to find markers that suggest early tubulo-interstitial damage in IgA nephropathy,looking for factors that trigger the progression of IgA nephropathy,to guide clinical intervention and treatment early.Therefore,this study intends to investigate the possible mechanisms of IgAN-tubulointerstitial damage by observing the relationship between TIMP-1,TGF-β1,OPN and clinical and pathological changes in patients with IgAN.ObjectiveObserve the relationship between serum TIMP-1,TGF-β1,OPN expression in renal biopsy and the clinical data of IgA nephropathy patients and renal tubulointerstitial lesions,and explore the possible mechanism of tubulointerstitial damage in IgA nephropathy.It provides a theoretical basis for early detection of tubulointerstitial damage in patients with lgA nephropathy and guiding early clinical intervention.MethodsThe IgAN patients diagnosed in Department of Nephrology at the First Affiliated Hospital of Zhengzhou University from 2013 to 2015 were selected as the study subjects.Inclusion criteria:Scr≤115umol/L（1.5mg/dl）,BUN≤7.5mmol/L（21mg/dl）,eGFR≥60ml·min^-1·（1.73m²）^-1,age of patient 18-65 years old,confirmed by renal biopsy.Exclusion criteria for cases:（1）secondary renal diseases,such as allergic purpura nephritis,systemic lupus erythematosus nephritis,hepatitis B virus-associated nephritis,etc.;（2）severe heart function abnormalities,abnormal liver function,Patients with diabetes mellitus,multiple myeloma,etc.;（3）Fibrosis lesions in other organs except the kidney;（4）Patients with incomplete clinical data.After the above inclusion and exclusion criteria were implemented,243 patients were included in the study.Clinical data of all subjects were collected,including name,gender,age,body mass index（BMI）,serum creatinine,24-hour urinary protein quantification,blood pressure,blood urea nitrogen,and urine microalbumin/creatinine ratio（ACR）.Serum TIMP-1 levels were detected by ELISA,and TIMP-1 was elevated by>98.1ng/ml.The renal biopsy specimens were examined by light microscopy,electron microscopy,and immunofluorescence after routine treatment.The blind reading method was adopted by a person.Pathological diagnosis is based on Haas classification and Katafuchi classification.Serum TIMP-1 levels were divided into two groups based on 243 patients.They were:normal TIMP-1 group and elevated TIMP-1 group.The clinical and pathological data of the two groups were compared to further investigate the relationship between clinical and pathological features of serum TIMP-1 and IgAN patients.In addition,patients with IgA nephropathy diagnosed in the Department of Nephrology at the First Affiliated Hospital of Zhengzhou University from 2015 to2017 were selected as study subjects.Inclusion criteria for the case:The patient’s age was>18 years old and was confirmed by renal biopsy.Case exclusion criteria:（1）congenital hereditary disease;（2）secondary renal disease.After the above inclusion criteria and exclusion criteria were implemented,a total of 60 patients were included in the study.At the same time,30 patients diagnosed as minimal change nephropathy after renal biopsy were selected as the control group,and the exclusion criteria were the same as those of the IgA nephropathy group.In addition,after surgical removal of tumors from renal tumors,the surrounding normal kidney tissue was taken as a control and a total of 20 cases were included.Clinical data of all subjects were collected,including name,sex,age,serum creatinine（Scr）,creatinine clearance（Ccr）,24-hour urinary protein quantification.The expression of TGF-β1 and OPN in kidney tissues was detected by immunohistochemistry.The renal biopsy specimens were examined by light microscopy,electron microscopy,and immunofluorescence after routine treatment.The blind reading method was adopted by a person.Pathological diagnosis is based on Haas classification and Katafuchi classification.The subjects were divided into three groups:healthy controls,MCD controls,and IgAN.Three groups of clinical data and pathological data were compared to investigate the relationship between the expression of TGF-β1 and OPN in the kidney and the clinical and pathological changes in patients with IgA nephropathy.Results1 There was no significant difference in clinical parameters such as blood pressure,serum albumin,24-hour urinary protein,serum creatinine,and blood urea nitrogen in the normal TIMP-1 and elevated TIMP-1 groups（P>0.05）.2 With reference to the Haas classification criteria,81 cases（42.63%）of type I+II in the normal TIMP-1 group,72 cases（37.90%）in the type III,37 cases（19.47%）in the IV+V type,and I-III The main type.In the elevated TIMP-1 group,there were6 cases（11.32%）of type I+II,21 cases（39.62%）of type III,26 cases（49.06%）of type IV+V,and type III-V.The proportion of IV+V was much higher than that of TIMP-1 normal group,P<0.05.3 According to the Katafuchi grading standard,TIMP-1 normal patients had 113patients（59.47%）in grade 0,59 patients（31.05%）in grade I,18 patients（9.48%）in grade II+III,and grade 0-I.the Lord.In the elevated TIMP-1 group,there were 7patients（13.21%）in grade 0,11（20.75%）in grade I,and 35（66.04%）in grade II+III,mainly grades I-III,including II+The proportion of grade III was much higher than that of TIMP-1 normal group,P<0.05.4 In the IgA nephropathy group,the Haas type（type I-V）,Scr,24-hour urinary protein excretion,and TGF-β1 and OPN in the kidney were higher than those in the other two groups（P<0.05）.Ccr was lower than the other two groups（P<0.05）.Among them,the expression of TGF-β1 and OPN in type IV and type V kidney tissues was higher than that of type II,type III and type III in Haas type（P<0.05）.5 Katafuchi grading（grades 0-III）in the IgA nephropathy group,Scr,24-hour urinary protein quantitation,and TGF-β1 and OPN in the kidneys were higher than those in the other two groups（P<0.05）,and Ccr was lower than the other two groups（P<0.05）.In addition,the Katafuchi grading was progressively increased,and TGF-β1 and OPN in kidneys of patients with IgA nephropathy also increased（P<0.05）.6 Haas classification and Katafuchi grading and positive expression of TGF-β1and OPN in the kidney（P<0.05）.Conclusion1 In patients with IgA nephropathy with elevated serum TIMP-1,there is a higher risk of renal tubulointerstitial lesions and a heavier renal pathology.TIMP-1elevation may serve as a monitoring indicator for the early detection and intervention of tubulointerstitial damage in patients with IGA nephropathy,thereby delaying the deterioration of renal function and the occurrence of end-stage renal failure.2 Both TGF-β1 and OPN mediate the tubulo-interstitial damage in IgAN patients and play an important role in promoting disease progression in IgAN patients.3 TIMP-1,TGF-β1 and OPN can be used as markers of renal tubulointerstitial lesions in IgA nephropathy.