Expression And Correlation Analysis Of Urinary Endoglin In Patients With Lupus Nephritis

Objective:This study aimed to investigate the differential expression of Endoglin(ENG)in urine samples from patients with systemic lupus erythematosus(SLE),lupus nephritis(LN),and healthy controls using the enzyme-linked immunosorbent assay(ELISA).The study analyzed the correlation between ENG expression levels and clinical data,laboratory indices,and disease activity in LN patients.The potential role of ENG in the diagnosis and disease activity of lupus nephritis was also evaluated to provide clinical value for the management of this disease.Methods:(1)The experimental group consisted of 58 SLE patients diagnosed at the Youjiang Medical University For Nationalities between October 2021 and February 2023.According to the 2019 Chinese lupus nephritis diagnosis and treatment guidelines,SLE patients were divided into LN and non-LN groups.The LN group was further divided into subgroups based on the following criteria:(a)According to the Systemic Lupus Erythematosus Disease Activity Index-2000(SLEDAI-2k)scores,patients were classified into the no activity group(0-4 points),mild activity group(5-9 points),moderate activity group(10-14 points),and severe activity group(≥15 points).Since the number of patients in the no activity and mild activity groups was small,these two groups were combined into the low activity group(0-9 points);(b)Estimated glomerular filtration rate(e GFR)was calculated using the Modification of Diet in Renal Disease(MDRD)study formula and patients were divided into the no renal impairment group(e GFR≥60ml/min/1.73m~2)and renal impairment group(e GFR<60ml/min/1.73m~2).The control group consisted of 16 healthy individuals randomly selected from those who underwent physical examinations at our hospital during the same period.Fresh midstream urine specimens were collected from all study subjects.(2)Clinical data and laboratory indicators were collected for each study group.(3)ELISA was used to detect the expression levels of ENG in urine samples from each study group.(4)Statistical analysis was performed to evaluate the differences in urinary ENG expression levels among the SLE,LN,and control groups,as well as the correlations between ENG and clinical data and laboratory indicators in the SLE and LN groups,and to assess the clinical value of urinary ENG in LN.Results:(1)The urine ENG expression levels in the SLE and LN groups were higher than those in the control group.The urine ENG levels in the SLE group were significantly higher than those in the control group(t=7.494,p<0.001).The comparison of urine ENG levels among the LN,n LN,and control groups was statistically significant(F=35.201,p<0.001).The urine ENG expression levels in the LN group were significantly higher than those in the healthy control group(p<0.0001)and the n LN group(p<0.0001),while there was no significant difference in urine ENG levels between the n LN and healthy control groups(p>0.05).(2)The urine ENG expression levels in SLE patients were positively correlated with blood creatinine(r=0.342,p=0.008),blood urea nitrogen(r=0.335,p=0.010),and 24-hour urine protein(r=0.486,p<0.001),while there was no significant correlation with white blood cells(r=0.108,p=0.420),hemoglobin(r=-0.068,p=0.611),platelets(r=0.018,p=0.382),albumin(r=-0.247,p=0.061),complement C3(r=-0.093,p=0.486),complement C4(r=-0.065,p=0.630),e GFR(r=-0.232,p=0.079),and SLEDAI-2k disease activity(r=1.022,p=0.869).(3)The urine ENG levels in the LN low activity group,moderate activity group,severe activity group,no renal function damage group,and renal function damage group were 7.93±0.75,7.59±1.52,7.11±1.32,7.09±1.24,and 7.79±1.53 ng/ml,respectively.There was no statistically significant difference in ENG levels between the LN low activity group,moderate activity group,and severe activity group(z=0.833,p=0.443),and no statistically significant difference in ENG levels between the LN no renal function damage group and renal function damage group(t=1.507,p=0.140).(4)There was no significant correlation between urine ENG expression levels in the LN group and white blood cells(r=0.244,p=0.134),hemoglobin(r=0.023,p=0.891),platelets(r=0.185,p=0.259),albumin(r=-0.035,p=0.834),complement C3(r=0.069,p=0.676),complement C4(r=0.091,p=0.581),blood creatinine(r=0.191,p=0.243),blood urea nitrogen(r=0.070,p=0.670),e GFR(r=-0.078,p=0.637),24-hour urine protein(r=0.172,p=0.637),and SLEDAI-2k disease activity(r=-0.328,p=0.402).(5)The diagnostic value of urinary ENG in LN was assessed using receiver operating characteristic(ROC)curve analysis.The area under the curve(AUC)was 0.8239,and the cutoff value was 6.96 ng/ml,with a sensitivity of 94.97%and a specificity of 66.67%(p<0.001).Conclusion:(1)The urinary expression levels of Endoglin(ENG)are significantly higher in patients with lupus nephritis compared to those without lupus nephritis,indicating that urinary ENG has the potential to become a biomarker for diagnosing lupus nephritis.(2)The expression level of urinary ENG is correlated with indicators of systemic lupus erythematosus renal function damage,suggesting that urinary ENG level may serve as an auxiliary indicator for assessing systemic lupus erythematosus renal function damage.