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Urinary sCD25 as a biomarker of lupus nephritis disease activity R Gupta, A Yadav, R Misra and A Aggarwal Lupus published online 10 October 2014 DOI: 10.1177/0961203314555174 The online version of this article can be found at: http://lup.sagepub.com/content/early/2014/10/10/0961203314555174
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Urinary sCD25 as a biomarker of lupus nephritis disease activity R Gupta, A Yadav, R Misra and A Aggarwal Department of Clinical Immunology, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, India
Objectives: T cells play an important role in the pathogenesis of lupus nephritis (LN). We studied the role of urinary soluble CD25 (sCD25) as a biomarker of LN disease activity in a cross-sectional and longitudinal study. Methods: Patients with systemic lupus erythematosus were classified as active LN (AN), inactive disease (ID) and active non-renal (ANR) based on disease activity and renal involvement at the time of enrolment. Urine and serum samples were collected at baseline from all patients and at 3-monthly follow-up from patients with AN. SLE disease activity index (SLEDAI) was used for disease activity assessment at all visits. sCD25 was measured by ELISA and normalized to urinary creatinine excretion and is expressed as pg/mg. Urine samples from 10 healthy individuals (HC) served as controls. Results: There were 119 patients (111 females, median age 27 years, 57 AN, 43 ID, 19 ANR). Median SLEDAI was 18, 2 and 8 in AN, ID and ANR groups, respectively. Median renal SLEDAI in AN was 8. Mean (SD) urinary sCD25 in the AN, ID, ANR and HC groups at baseline was 741.1 (794.9), 407.8 (511.1), 735.4 (667.7) and 250.9 (122.2) pg/mg respectively (p ¼ 0.019). Mean (SD) serum sCD25 in AN, ID and ANR was 8285.25 (5922.2), 6044 (3501.92) and 6568.72 (4333.62) pg/ml, respectively. Urinary sCD25 correlated with SLEDAI (r ¼ 0.22; p ¼ 0.015) but did not correlate with serum sCD25 or proteinuria. Urinary sCD25 compares well with traditional markers of disease activity in differentiating active from inactive renal disease. On follow-up mean urinary sCD25 decreased to 470.0 (449.6; p < 0.05) at 3 months, 496.7 (465.8; p ¼ 0.006) at 6 months, 471.9 (303.2; p ¼ 0.041) at 9 months and 358.6 (496.9; p ¼ 0.007) at 12 months from baseline value of 741.1 (794.9). In four patients who either had relapse, persistent disease activity or developed chronic kidney disease, urinary sCD25 showed rise preceding traditional abnormalities on urine examination. Conclusions: Urinary sCD25 is a good biomarker for follow-up of LN. It may also have the potential to predict poor response and relapse. Lupus (2014) 0, 1–7. Key words: SLE; nephritis; biomarker; urine; CD25
Introduction Lupus nephritis (LN) affects almost 50–70% of patients with systemic lupus erythematosus (SLE). LN is usually diagnosed by presence of proteinuria and/or active urinary sediment and confirmed by kidney biopsy. Subclinical renal involvement can be diagnosed with these markers. In addition, persistent proteinuria does not always reflect ongoing disease activity and could also be due to damage. Repeat kidney biopsy, though useful, is an invasive procedure with its own Correspondence to: Amita Aggarwal, Department of Clinical Immunology Sanjay Gandhi Postgraduate Institute of Medical Sciences Lucknow, India 226014. Emails: [email protected], [email protected] Received 4 July 2014; revised: 1 September 2014 accepted 10 September 2014
complications. Thus there is a need to find new urinary biomarkers in LN to assess disease activity. T cells have a role in pathogenesis of LN. IFN-g secreted by T lymphocytes induces MHC-II and CD40 expression on tubular epithelial cells and mesangial cells. These cells act as antigen-presenting cells and amplify the immune response by further activation of T cells.1 The therapeutic role of cyclosporine A, tacrolimus and abatacept further confirms the pathogenic role of T cells in LN, and has revived interest in looking at the T-cell activation markers as biomarkers of LN disease activity. IL-2 is a small 15 kDa protein that is secreted after T-cell activation and plays an important role in growth, proliferation and differentiation of T cells to convert them to effector T cells. The surface IL-2 receptor is made up of two chains; the smaller chain is released as a 35–40 kDa protein and is known as
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10.1177/0961203314555174
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(LUP)
[1–7] [PREPRINTER stage]
Urinary sCD25 as a biomarker of lupus nephritis disease activity R Gupta et al.
2
sCD25 or sIL-2R. This protein can be measured in serum as well as in body fluid as a marker of T-cell activation.2 Soluble CD25 is a good marker of acute renal rejection in patients with kidney transplantation. In patients with SLE, levels of sCD25 in serum correlate with lupus activity, and levels are higher in patients with nephritis as compared with those without nephritis.3 Patients with LN shed sCD25 in the urine, and this may act as a surrogate marker of T-cell activation in the kidney.2 In a small crosssectional study Chang et al. demonstrated that urinary sCD25 is increased in patients with active LN as compared with inactive LN, but larger and longitudinal studies investigating the role of urinary sCD25as a potential biomarker in LN are lacking.3 Thus we studied urinary sCD25 as a marker of disease activity in LN in a prospective cohort of patients with SLE.
Patients and methods Patients with SLE satisfying the 1982 ACR criteria4 and having either active nephritis (AN), active lupus without nephritis (ANR) or inactive disease (ID) were enrolled in the study. At baseline all patients had detailed clinical assessment and SLE disease activity index (SLEDAI) assessment. In patients with nephritis, renal SLEDAI (rSLEDAI) was also calculated using the four renal parameters of SLEDAI. Blood and urine samples were collected after informed consent. Serum and cell-free urine samples were stored in aliquots at 80 C for sCD25 measurement. Most patients in the AN group underwent renal biopsy followed by treatment according to the histological class. Patients with class II LN were treated with steroids alone and patients with class V LN were treated with either mycophenolate with steroids or with monthly cyclophosphamide with steroids. Patients with class III or IV LN were treated with Eurolupus protocol followed by maintenance with either azathioprine or mycophenolate. The patients in AN group were followed up every 3 months or earlier if required in case of any disease flare or any complication, for 1 year. Clinical and laboratory assessment to calculate SLEDAI and rSLEDAI was carried out at every visit to assess the response to treatment. Urine and serum samples were stored at every 3 monthly visit for followup study of these patients in the AN group. Extra samples were taken if a patient had any flare of disease with or without nephritis. Patients who
either had any infection or were pregnant were excluded from the study. If any patient became pregnant during this 1-year follow-up, further follow-up samples were not taken after the pregnancy was diagnosed. Urine samples from 10 healthy controls (HC) were also collected and analyzed for urinary sCD25 and urinary creatinine excretion. Urinary and serum sCD25 were measured by ELISA (BD Biosciences, San Diego, CA) according to the manufacturer’s instructions. Briefly, microwells were coated with 100 ml per well of capture antibody. Plates were then blocked with 10% fetal bovine serum. Later probing antibody was added. After washing thoroughly, tetramethylbenzidine (TMB) substrate was added for 30 min and the reaction was stopped using 2 N sulphuric acid. The absorbance was read at 450 nm. All the values for urinary sCD25 (obtained in pg/ml) were normalized to urinary creatinine excretion (obtained in mg/dl). Statistical analyses were done by the SPSS software (Statistical Package for the Social Sciences, version 16.0, SPSS Inc, Chicago, Ill, USA). Continuous variables were expressed as mean standard deviation and discrete variables were expressed as median (range). The nonparametric Mann–Whitney U and Chi-square tests were used for two-sample analyses and Kruskal– Wallis tests for three or more samples analyses. The t-test was used where applicable. Spearman’s rank correlation coefficient was used to assess any correlation between parameters. P values less than .05 were considered of significance.
Results A total of 119 patients with SLE were enrolled for the study, of which nine were males and 110 were females. Of these 119 patients, 57 (47.8%) had AN, 43 (36.13%) had ID and 19 (15.9%) had ANR disease. Median age for the whole group was 27 (12– 50) years and the category wise median age was 27 (12–50) years in AN group, 28 (14–48) years in ID group and 26 (15–48) years in ANR group. Renal biopsy was done in 45 patients of AN group. Proliferative glomerulonephritis (class III and IV) was detected in 31 (68.8%) patients. Class II and class V LN was detected in seven (15.5%) patients each. Twelve patients in the AN group could not undergo biopsy for various reasons such as thrombocytopenia, large ascites and not willing to undergo the procedure. However, based on clinical
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(LUP)
[1–7] [PREPRINTER stage]
Urinary sCD25 as a biomarker of lupus nephritis disease activity R Gupta et al.
3
features and urinary examination, these 12 patients were treated according to the most probable LN class (11 as proliferative glomerulonephritis and one as membranous nephropathy) and were also included in the final analysis. The baseline characteristics like urine spot protein:spot creatinine ratio, C3, C4, anti-ds DNA antibody levels, rSLEDAI, SLEDAI and serum creatinine are shown in Table 1. In the AN group, patients were followed up longitudinally and out of 57 patients, 40 completed 3 months follow-up, 35 patients 6 months, 28 patients 9 months and 24 patients completed 1 year follow-up when the data was analyzed. At 3 months, 31 patients achieved complete remission, eight patients had partial response and one patient showed worsening of renal function and later, despite treatment with rituximab, developed chronic kidney disease (CKD) by 6 months. The remaining eight patients achieved complete remission by 6 months. Two patients who initially achieved remission showed a relapse of nephritis at 1 year followup. Another patient who had class II nephritis at the beginning and was treated with steroids alone showed a relapse of nephritis at 6 months of followup and required treatment with cyclophosphamide. Mean normalized urinary sCD25 values in the AN, ID, ANR and HC groups at the baseline were 741.1 (794.9), 407.8 (511.1), 735.4 (667.7) and 250.9 (122.2) pg/mg, respectively, and the difference among the groups was significant (p ¼ 0.019). The difference in the mean normalized urinary sCD25 values at baseline was significant between AN and HC (p ¼ 0.045) and AN and ID (p ¼ 0.02), but it was insignificant between AN and ANR group (Figure 1). At baseline, mean serum sCD25 levels for patients in the three groups of patients (AN, ID and ANR) were 8285.25
Table 1
(5922.2), 6044 (3501.92) and 6568.72 (4333.62), respectively, and the difference among the groups was insignificant. At baseline, mean normalized urinary sCD25 levels correlated with SLEDAI (r ¼ 0.226; p ¼ 0.015) but did not show any correlation with serum sCD25 levels (r ¼ 0.01, Figure 2(a)) and spot urine protein:creatinine ratio (r ¼ 0.08, Figure 2(b)). Mean normalized urinary sCD25 levels in AN patients at 3, 6, 9 and 12 months were significantly lower as compared with baseline, i.e. 470.0 (449.6; p < 0.05), 496.7 (465.8; p ¼ 0.006), 471.9 (303.2; p ¼ 0.041) and 358.6 (496.9; p ¼ 0.007), respectively (Figure 3.). Mean serum sCD25 values for 45 patients in the AN group at baseline and at 6 months were 8285.25 (5922.2) and 4738.09 (2742.53; p ¼ 0.037). Table 2 shows the change in various parameters over time for the AN group. Receiver operating curves (ROC) for discriminating between active versus inactive disease showed the area under curve (AUC) for various disease activity parameters as: serum C3 [0.849 (0.962–0.805) p < 0.001], C4 [0.816 (0.911–0.730) p < 0.001], antidsDNA antibodies [0.737 (0.613–0.861) p ¼ 0.001], CD25 [0.678 (0.546–0.810) p ¼ 0.014] urinary protein/creatinine ratio [0.761 (0.645–0.876) p < 0.001] and urine sCD25 [0.672 (0.529–0.815) p ¼ 0.018]. ROC curves for discriminating between active renal disease versus inactive disease showed the AUC for various disease activity parameters as: serum C3 [0.750 (0.610–0.891) p ¼ 0.002], C4 [0.687 (0.542–0.841) p ¼ 0.019], anti-dsDNA
Baseline characteristics of patients in three categories Active nephritis Active non-renal Inactive disease (AN) (ANR) (ID)
Number F:M Median age (y) SLEDAI rSLEDAI C3 (mg/dl) Low C3 (n) C4 (mg/dl) Low C4 (n) Anti-dsDNA (IU/ml) Upr/Ucr ratio Creatinine (mg/dl)
57 55:2 27 (12–50) 18 (4–32) 8 (4–16) 52.5 30.9 41 11.9 12.0 44 170.9 62.5 3.81 3.43 0.97 0.4
19 13:6 26 (15–48) 9 (5–18) 0 (0) 75.8 39.13 8 15.2 8.4 10 131.7 83.7 0.4 0.35 0.87 0.2
43 42:1 28 (14–48) 2 (0–4) 0 (0) 114.3 ( 29.3) 3 23.8 10.6 11 92.6 80.6 0.83 1.84 0.79 0.17
Figure 1 Scatter plot showing baseline normalized urinary sCD25 levels in the three categories of the patients and healthy controls. Lupus
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(LUP)
[1–7] [PREPRINTER stage]
Urinary sCD25 as a biomarker of lupus nephritis disease activity R Gupta et al.
4
Figure 2 (a) and (b) Relationship of normalized urinary sCD25 with spot urinary protein: creatinine ratio and serum sCD25 levels.
Figure 3
Normalized urinary sCD25 levels in the AN group at different time points.
antibodies [0.655 (0.499–0.811) p ¼ 0.052], CD25 [0.591 (0.443–0.739) p ¼ 0.076], urinary protein/creatinine ratio [0.899 (0.814–0.985) p < 0.001] and urine sCD25[0.723 (0.578–0.868) p ¼ 0.005]. In our study, it was interesting to see the trend in urinary sCD25 levels for four patients who either had a relapse or had a poor renal outcome. For two
patients who had a relapse of nephritis at 11 and 12 months, a rise in normalized urinary sCD25 preceded the clinical relapse of nephritis by 2–3 months. One patient who had class II nephritis and received steroids alone achieved complete remission, but developed vasculitis at 3-monthly visit,
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(LUP)
[1–7] [PREPRINTER stage]
Urinary sCD25 as a biomarker of lupus nephritis disease activity R Gupta et al.
5
Table 2 Change in different disease activity parameters and urinary sCD25 (UsCD25) in the AN group with treatment over 1 year
Number SLEDAI rSLEDAI C3 (mg/dl) Low C3 (n) C4 (mg/dl) Low C4 (n) Anti-dsDNA (IU/ml) Upr/Ucr ratio Serum Creatinine (mg/dl) UsCD25(pg)/UCr(mg) p-value**
Baseline
3 months
6 months
9 months
1 year
57 18 (6–32) 8 (4–16) 52.5 30.9 41 11.9 12.0 44 170.9 62.5 3.81 3.43 0.97 0.4 741.1 794.98 –
40 2 (0–13) 0 (0–12) 89.2 29.4 3 20.1 12.1 12 93.5 80.9 1.6 2.3 0.92 0.63 470.0 449.6
http://lup.sagepub.com/
Urinary sCD25 as a biomarker of lupus nephritis disease activity R Gupta, A Yadav, R Misra and A Aggarwal Lupus published online 10 October 2014 DOI: 10.1177/0961203314555174 The online version of this article can be found at: http://lup.sagepub.com/content/early/2014/10/10/0961203314555174
Published by: http://www.sagepublications.com
Additional services and information for Lupus can be found at: Email Alerts: http://lup.sagepub.com/cgi/alerts Subscriptions: http://lup.sagepub.com/subscriptions Reprints: http://www.sagepub.com/journalsReprints.nav Permissions: http://www.sagepub.com/journalsPermissions.nav
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Lupus (2014) 0,
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Urinary sCD25 as a biomarker of lupus nephritis disease activity R Gupta, A Yadav, R Misra and A Aggarwal Department of Clinical Immunology, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, India
Objectives: T cells play an important role in the pathogenesis of lupus nephritis (LN). We studied the role of urinary soluble CD25 (sCD25) as a biomarker of LN disease activity in a cross-sectional and longitudinal study. Methods: Patients with systemic lupus erythematosus were classified as active LN (AN), inactive disease (ID) and active non-renal (ANR) based on disease activity and renal involvement at the time of enrolment. Urine and serum samples were collected at baseline from all patients and at 3-monthly follow-up from patients with AN. SLE disease activity index (SLEDAI) was used for disease activity assessment at all visits. sCD25 was measured by ELISA and normalized to urinary creatinine excretion and is expressed as pg/mg. Urine samples from 10 healthy individuals (HC) served as controls. Results: There were 119 patients (111 females, median age 27 years, 57 AN, 43 ID, 19 ANR). Median SLEDAI was 18, 2 and 8 in AN, ID and ANR groups, respectively. Median renal SLEDAI in AN was 8. Mean (SD) urinary sCD25 in the AN, ID, ANR and HC groups at baseline was 741.1 (794.9), 407.8 (511.1), 735.4 (667.7) and 250.9 (122.2) pg/mg respectively (p ¼ 0.019). Mean (SD) serum sCD25 in AN, ID and ANR was 8285.25 (5922.2), 6044 (3501.92) and 6568.72 (4333.62) pg/ml, respectively. Urinary sCD25 correlated with SLEDAI (r ¼ 0.22; p ¼ 0.015) but did not correlate with serum sCD25 or proteinuria. Urinary sCD25 compares well with traditional markers of disease activity in differentiating active from inactive renal disease. On follow-up mean urinary sCD25 decreased to 470.0 (449.6; p < 0.05) at 3 months, 496.7 (465.8; p ¼ 0.006) at 6 months, 471.9 (303.2; p ¼ 0.041) at 9 months and 358.6 (496.9; p ¼ 0.007) at 12 months from baseline value of 741.1 (794.9). In four patients who either had relapse, persistent disease activity or developed chronic kidney disease, urinary sCD25 showed rise preceding traditional abnormalities on urine examination. Conclusions: Urinary sCD25 is a good biomarker for follow-up of LN. It may also have the potential to predict poor response and relapse. Lupus (2014) 0, 1–7. Key words: SLE; nephritis; biomarker; urine; CD25
Introduction Lupus nephritis (LN) affects almost 50–70% of patients with systemic lupus erythematosus (SLE). LN is usually diagnosed by presence of proteinuria and/or active urinary sediment and confirmed by kidney biopsy. Subclinical renal involvement can be diagnosed with these markers. In addition, persistent proteinuria does not always reflect ongoing disease activity and could also be due to damage. Repeat kidney biopsy, though useful, is an invasive procedure with its own Correspondence to: Amita Aggarwal, Department of Clinical Immunology Sanjay Gandhi Postgraduate Institute of Medical Sciences Lucknow, India 226014. Emails: [email protected], [email protected] Received 4 July 2014; revised: 1 September 2014 accepted 10 September 2014
complications. Thus there is a need to find new urinary biomarkers in LN to assess disease activity. T cells have a role in pathogenesis of LN. IFN-g secreted by T lymphocytes induces MHC-II and CD40 expression on tubular epithelial cells and mesangial cells. These cells act as antigen-presenting cells and amplify the immune response by further activation of T cells.1 The therapeutic role of cyclosporine A, tacrolimus and abatacept further confirms the pathogenic role of T cells in LN, and has revived interest in looking at the T-cell activation markers as biomarkers of LN disease activity. IL-2 is a small 15 kDa protein that is secreted after T-cell activation and plays an important role in growth, proliferation and differentiation of T cells to convert them to effector T cells. The surface IL-2 receptor is made up of two chains; the smaller chain is released as a 35–40 kDa protein and is known as
! The Author(s), 2014. Reprints and permissions: http://www.sagepub.co.uk/journalsPermissions.nav
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10.1177/0961203314555174
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(LUP)
[1–7] [PREPRINTER stage]
Urinary sCD25 as a biomarker of lupus nephritis disease activity R Gupta et al.
2
sCD25 or sIL-2R. This protein can be measured in serum as well as in body fluid as a marker of T-cell activation.2 Soluble CD25 is a good marker of acute renal rejection in patients with kidney transplantation. In patients with SLE, levels of sCD25 in serum correlate with lupus activity, and levels are higher in patients with nephritis as compared with those without nephritis.3 Patients with LN shed sCD25 in the urine, and this may act as a surrogate marker of T-cell activation in the kidney.2 In a small crosssectional study Chang et al. demonstrated that urinary sCD25 is increased in patients with active LN as compared with inactive LN, but larger and longitudinal studies investigating the role of urinary sCD25as a potential biomarker in LN are lacking.3 Thus we studied urinary sCD25 as a marker of disease activity in LN in a prospective cohort of patients with SLE.
Patients and methods Patients with SLE satisfying the 1982 ACR criteria4 and having either active nephritis (AN), active lupus without nephritis (ANR) or inactive disease (ID) were enrolled in the study. At baseline all patients had detailed clinical assessment and SLE disease activity index (SLEDAI) assessment. In patients with nephritis, renal SLEDAI (rSLEDAI) was also calculated using the four renal parameters of SLEDAI. Blood and urine samples were collected after informed consent. Serum and cell-free urine samples were stored in aliquots at 80 C for sCD25 measurement. Most patients in the AN group underwent renal biopsy followed by treatment according to the histological class. Patients with class II LN were treated with steroids alone and patients with class V LN were treated with either mycophenolate with steroids or with monthly cyclophosphamide with steroids. Patients with class III or IV LN were treated with Eurolupus protocol followed by maintenance with either azathioprine or mycophenolate. The patients in AN group were followed up every 3 months or earlier if required in case of any disease flare or any complication, for 1 year. Clinical and laboratory assessment to calculate SLEDAI and rSLEDAI was carried out at every visit to assess the response to treatment. Urine and serum samples were stored at every 3 monthly visit for followup study of these patients in the AN group. Extra samples were taken if a patient had any flare of disease with or without nephritis. Patients who
either had any infection or were pregnant were excluded from the study. If any patient became pregnant during this 1-year follow-up, further follow-up samples were not taken after the pregnancy was diagnosed. Urine samples from 10 healthy controls (HC) were also collected and analyzed for urinary sCD25 and urinary creatinine excretion. Urinary and serum sCD25 were measured by ELISA (BD Biosciences, San Diego, CA) according to the manufacturer’s instructions. Briefly, microwells were coated with 100 ml per well of capture antibody. Plates were then blocked with 10% fetal bovine serum. Later probing antibody was added. After washing thoroughly, tetramethylbenzidine (TMB) substrate was added for 30 min and the reaction was stopped using 2 N sulphuric acid. The absorbance was read at 450 nm. All the values for urinary sCD25 (obtained in pg/ml) were normalized to urinary creatinine excretion (obtained in mg/dl). Statistical analyses were done by the SPSS software (Statistical Package for the Social Sciences, version 16.0, SPSS Inc, Chicago, Ill, USA). Continuous variables were expressed as mean standard deviation and discrete variables were expressed as median (range). The nonparametric Mann–Whitney U and Chi-square tests were used for two-sample analyses and Kruskal– Wallis tests for three or more samples analyses. The t-test was used where applicable. Spearman’s rank correlation coefficient was used to assess any correlation between parameters. P values less than .05 were considered of significance.
Results A total of 119 patients with SLE were enrolled for the study, of which nine were males and 110 were females. Of these 119 patients, 57 (47.8%) had AN, 43 (36.13%) had ID and 19 (15.9%) had ANR disease. Median age for the whole group was 27 (12– 50) years and the category wise median age was 27 (12–50) years in AN group, 28 (14–48) years in ID group and 26 (15–48) years in ANR group. Renal biopsy was done in 45 patients of AN group. Proliferative glomerulonephritis (class III and IV) was detected in 31 (68.8%) patients. Class II and class V LN was detected in seven (15.5%) patients each. Twelve patients in the AN group could not undergo biopsy for various reasons such as thrombocytopenia, large ascites and not willing to undergo the procedure. However, based on clinical
Lupus Downloaded from lup.sagepub.com at J. Robert Van Pelt and Opie Library on October 17, 2014
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(LUP)
[1–7] [PREPRINTER stage]
Urinary sCD25 as a biomarker of lupus nephritis disease activity R Gupta et al.
3
features and urinary examination, these 12 patients were treated according to the most probable LN class (11 as proliferative glomerulonephritis and one as membranous nephropathy) and were also included in the final analysis. The baseline characteristics like urine spot protein:spot creatinine ratio, C3, C4, anti-ds DNA antibody levels, rSLEDAI, SLEDAI and serum creatinine are shown in Table 1. In the AN group, patients were followed up longitudinally and out of 57 patients, 40 completed 3 months follow-up, 35 patients 6 months, 28 patients 9 months and 24 patients completed 1 year follow-up when the data was analyzed. At 3 months, 31 patients achieved complete remission, eight patients had partial response and one patient showed worsening of renal function and later, despite treatment with rituximab, developed chronic kidney disease (CKD) by 6 months. The remaining eight patients achieved complete remission by 6 months. Two patients who initially achieved remission showed a relapse of nephritis at 1 year followup. Another patient who had class II nephritis at the beginning and was treated with steroids alone showed a relapse of nephritis at 6 months of followup and required treatment with cyclophosphamide. Mean normalized urinary sCD25 values in the AN, ID, ANR and HC groups at the baseline were 741.1 (794.9), 407.8 (511.1), 735.4 (667.7) and 250.9 (122.2) pg/mg, respectively, and the difference among the groups was significant (p ¼ 0.019). The difference in the mean normalized urinary sCD25 values at baseline was significant between AN and HC (p ¼ 0.045) and AN and ID (p ¼ 0.02), but it was insignificant between AN and ANR group (Figure 1). At baseline, mean serum sCD25 levels for patients in the three groups of patients (AN, ID and ANR) were 8285.25
Table 1
(5922.2), 6044 (3501.92) and 6568.72 (4333.62), respectively, and the difference among the groups was insignificant. At baseline, mean normalized urinary sCD25 levels correlated with SLEDAI (r ¼ 0.226; p ¼ 0.015) but did not show any correlation with serum sCD25 levels (r ¼ 0.01, Figure 2(a)) and spot urine protein:creatinine ratio (r ¼ 0.08, Figure 2(b)). Mean normalized urinary sCD25 levels in AN patients at 3, 6, 9 and 12 months were significantly lower as compared with baseline, i.e. 470.0 (449.6; p < 0.05), 496.7 (465.8; p ¼ 0.006), 471.9 (303.2; p ¼ 0.041) and 358.6 (496.9; p ¼ 0.007), respectively (Figure 3.). Mean serum sCD25 values for 45 patients in the AN group at baseline and at 6 months were 8285.25 (5922.2) and 4738.09 (2742.53; p ¼ 0.037). Table 2 shows the change in various parameters over time for the AN group. Receiver operating curves (ROC) for discriminating between active versus inactive disease showed the area under curve (AUC) for various disease activity parameters as: serum C3 [0.849 (0.962–0.805) p < 0.001], C4 [0.816 (0.911–0.730) p < 0.001], antidsDNA antibodies [0.737 (0.613–0.861) p ¼ 0.001], CD25 [0.678 (0.546–0.810) p ¼ 0.014] urinary protein/creatinine ratio [0.761 (0.645–0.876) p < 0.001] and urine sCD25 [0.672 (0.529–0.815) p ¼ 0.018]. ROC curves for discriminating between active renal disease versus inactive disease showed the AUC for various disease activity parameters as: serum C3 [0.750 (0.610–0.891) p ¼ 0.002], C4 [0.687 (0.542–0.841) p ¼ 0.019], anti-dsDNA
Baseline characteristics of patients in three categories Active nephritis Active non-renal Inactive disease (AN) (ANR) (ID)
Number F:M Median age (y) SLEDAI rSLEDAI C3 (mg/dl) Low C3 (n) C4 (mg/dl) Low C4 (n) Anti-dsDNA (IU/ml) Upr/Ucr ratio Creatinine (mg/dl)
57 55:2 27 (12–50) 18 (4–32) 8 (4–16) 52.5 30.9 41 11.9 12.0 44 170.9 62.5 3.81 3.43 0.97 0.4
19 13:6 26 (15–48) 9 (5–18) 0 (0) 75.8 39.13 8 15.2 8.4 10 131.7 83.7 0.4 0.35 0.87 0.2
43 42:1 28 (14–48) 2 (0–4) 0 (0) 114.3 ( 29.3) 3 23.8 10.6 11 92.6 80.6 0.83 1.84 0.79 0.17
Figure 1 Scatter plot showing baseline normalized urinary sCD25 levels in the three categories of the patients and healthy controls. Lupus
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Urinary sCD25 as a biomarker of lupus nephritis disease activity R Gupta et al.
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Figure 2 (a) and (b) Relationship of normalized urinary sCD25 with spot urinary protein: creatinine ratio and serum sCD25 levels.
Figure 3
Normalized urinary sCD25 levels in the AN group at different time points.
antibodies [0.655 (0.499–0.811) p ¼ 0.052], CD25 [0.591 (0.443–0.739) p ¼ 0.076], urinary protein/creatinine ratio [0.899 (0.814–0.985) p < 0.001] and urine sCD25[0.723 (0.578–0.868) p ¼ 0.005]. In our study, it was interesting to see the trend in urinary sCD25 levels for four patients who either had a relapse or had a poor renal outcome. For two
patients who had a relapse of nephritis at 11 and 12 months, a rise in normalized urinary sCD25 preceded the clinical relapse of nephritis by 2–3 months. One patient who had class II nephritis and received steroids alone achieved complete remission, but developed vasculitis at 3-monthly visit,
Lupus Downloaded from lup.sagepub.com at J. Robert Van Pelt and Opie Library on October 17, 2014
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(LUP)
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Urinary sCD25 as a biomarker of lupus nephritis disease activity R Gupta et al.
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Table 2 Change in different disease activity parameters and urinary sCD25 (UsCD25) in the AN group with treatment over 1 year
Number SLEDAI rSLEDAI C3 (mg/dl) Low C3 (n) C4 (mg/dl) Low C4 (n) Anti-dsDNA (IU/ml) Upr/Ucr ratio Serum Creatinine (mg/dl) UsCD25(pg)/UCr(mg) p-value**
Baseline
3 months
6 months
9 months
1 year
57 18 (6–32) 8 (4–16) 52.5 30.9 41 11.9 12.0 44 170.9 62.5 3.81 3.43 0.97 0.4 741.1 794.98 –
40 2 (0–13) 0 (0–12) 89.2 29.4 3 20.1 12.1 12 93.5 80.9 1.6 2.3 0.92 0.63 470.0 449.6
