Urinary metabolomic profiling of a cohort of Colombian patients with systemic lupus erythematosus.

Systemic lupus erythematosus (SLE) is an autoimmune and multisystem disease with a high public health impact. Lupus nephritis (LN), commonly known as renal involvement in SLE, is associated with a poorer prognosis and increased rates of morbidity and mortality in patients with SLE. Identifying new urinary biomarkers that can be used for LN prognosis or diagnosis is essential and is part of current active research. In this study, we applied an untargeted metabolomics approach involving liquid and gas chromatography coupled with mass spectrometry to urine samples collected from 17 individuals with SLE and no kidney damage, 23 individuals with LN, and 10 clinically healthy controls (HCs) to identify differential metabolic profiles for SLE and LN. The data analysis revealed a differentially abundant metabolite expression profile for each study group, and those metabolites may act as potential differential biomarkers of SLE and LN. The differential metabolic pathways found between the LN and SLE patients with no kidney involvement included primary bile acid biosynthesis, branched-chain amino acid synthesis and degradation, pantothenate and coenzyme A biosynthesis, lysine degradation, and tryptophan metabolism. Receiver operating characteristic curve analysis revealed that monopalmitin, glycolic acid, and glutamic acid allowed for the differentiation of individuals with SLE and no kidney involvement and individuals with LN considering high confidence levels. While the results offer promise, it is important to recognize the significant influence of medications and other external factors on metabolomics studies. This impact has the potential to obscure differences in metabolic profiles, presenting a considerable challenge in the identification of disease biomarkers. Therefore, experimental validation should be conducted with a larger sample size to explore the diagnostic potential of the metabolites found as well as to examine how treatment and disease activity influence the identified chemical compounds. This will be crucial for refining the accuracy and effectiveness of using urine metabolomics for diagnosing and monitoring lupus and lupus nephritis.

Association Between Urinary Epidermal Growth Factor and Renal Prognosis in Lupus Nephritis.

OBJECTIVE: To evaluate the role of urinary epidermal growth factor (EGF) as a biomarker of chronic kidney damage in lupus nephritis (LN). METHODS: A proteomics approach was used to identify urinary EGF as a biomarker of interest in a discovery cohort of patients with LN. The expression of urinary EGF was characterized in 2 large multiethnic LN cohorts, and the association between urinary EGF levels at the time of flare and kidney outcomes was evaluated in a subset of 120 patients with long-term follow-up data. For longitudinal studies, the expression of urinary EGF over time was determined in 2 longitudinal cohorts of patients with LN from whom serial urine samples were collected. RESULTS: Discovery analysis showed the urinary EGF levels as being low in patients with active LN (median peptide count 8.4, interquartile range [IQR] 2.8-12.3 in patients with active LN versus median 48.0, IQR 45.3-64.6 in healthy controls). The peptide sequence was consistent with that of proEGF, and this was confirmed by immunoblotting. The discovery findings were verified by enzyme-linked immunosorbent assay. Patients with active LN had a significantly lower level of urinary EGF compared to that in patients with active nonrenal systemic lupus erythematosus (SLE), patients with inactive SLE, and healthy kidney donors (each P < 0.05). The urinary EGF level was inversely correlated with the chronicity index of histologic features assessed in kidney biopsy tissue (Spearman's r = -0.67, P < 0.001). Multivariate survival analysis showed that the urinary EGF level was associated with time to doubling of the serum creatinine level (DSCr), a marker of future end-stage kidney disease (ESKD) (hazard ratio 0.88, 95% confidence interval 0.77-0.99, P = 0.045). Patients whose LN symptoms progressed to DSCr and those who experienced progression to ESKD had a lower urinary EGF level at the time of flare, and urinary EGF levels decreased over the 12 months following flare. All patients who experienced progression to ESKD were identified based on a urinary EGF cutoff level of <5.3 ng/mg. CONCLUSION: Urinary EGF levels are correlated with histologic kidney damage in patients with LN. Low urinary EGF levels at the time of flare and decreasing urinary EGF levels over time are associated with adverse long-term kidney outcomes.

Urinary Soluble CD163: a Novel Noninvasive Biomarker of Activity for Lupus Nephritis.

BACKGROUND: Clinical distinction between patients with lupus nephritis who have active inflammation or chronic kidney damage is challenging. Studies have shown soluble CD163, which derives from cleavage of the CD163 M2c macrophage receptor and can be quantified in urine, correlates with active lupus nephritis. METHODS: We measured urine CD163 at lupus nephritis flares in patients from a Mexican cohort and cross-sectional and longitudinal United States cohorts. We also performed serial urine CD163 measurements during the treatment of flares in a subset of patients from the Mexican and longitudinal United States cohorts, and assessed response to therapy at 12 months. In addition, we evaluated urinary CD163 agreement with histologic activity in 19 patients from the Mexican cohort who had repeated kidney biopsies on follow-up. RESULTS: Urinary CD163 levels were significantly higher in patients with active lupus nephritis than in patients with active extrarenal SLE, inactive SLE, and other glomerular diseases, and correlated with disease clinical severity, histologic class, and the histologic activity index. Urinary CD163 increased from 6 months preflare to flare, diminishing progressively in complete and partial responders, whereas it remained elevated in nonresponders. Urinary CD163 <370 ng/mmol at 6 months predicted complete renal response at 12 months with >87% sensitivity and >87% specificity. Urinary CD163 <370 ng/mmol or >370 ng/mmol perfectly agreed (κ=1.0) with a histologic activity index ≤1 or >1 in repeated biopsies, respectively. Evaluation of urinary CD163 in patients with persistent proteinuria at 6 months improved the prediction of who would achieve complete renal response at 12 months. CONCLUSIONS: Urinary CD163 reflects histologic inflammation in lupus nephritis and is a promising activity biomarker that varies over time with lupus nephritis activity and treatment.

Comparison of lupus patients with early and late onset nephritis: a study in 71 patients from a single referral center.

BACKGROUND: Nephritis occurs frequently in systemic lupus erythematosus (SLE) and may worsen disease morbidity and mortality. Knowing all characteristics of this manifestation helps to a prompt recognition and treatment. AIM: To compare the differences in clinical data, serological profile and treatment response of nephritis of early and late onset. METHODS: Retrospective study of 71 SLE patients with biopsy proven nephritis divided in early nephritis group (diagnosis of nephritis in the first 5 years of the disease) and late nephritis (diagnosis of nephritis after 5 years). Epidemiological, serological, clinical and treatment data were collected from charts and compared. RESULTS: In this sample, 70. 4% had early onset nephritis and 29.6% had late onset. No differences were noted in epidemiological, clinical, serological profile, SLICC and SLEDAI, except that late onset nephritis patients were older at nephritis diagnosis (p = 0.01). Regarding renal biopsy classification, C3 and C4 levels, serum creatinine, 24 h proteinuria and response rate to treatment the two groups were similar (p = NS). Patients with early onset had lower levels of hemoglobin at nephritis onset than those of late onset (p = 0.02). CONCLUSIONS: Most of SLE patients had nephritis in the first 5 years of disease. No major differences were noted when disease profile or treatment outcome of early and late onset nephritis were compared.

Utility of urinary transferrin and ceruloplasmin in patients with systemic lupus erythematosus for differentiating patients with lupus nephritis. / Transferrina y ceruloplasmina en orina de pacientes con lupus eritematoso sistémico. ¿Son útiles para diferenciar pacientes con nefritis lúpica?

BACKGROUND AND OBJECTIVE: Diagnosis of lupus nephritis (LN) is usually based on renal biopsy, which is an invasive technique that involves multiple risks. Therefore, different biomarkers have emerged as alternatives for the diagnosis of LN. Nonetheless, studies regarding urinary biomarkers in Latin American patients are limited. The objective of this study was to assess the diagnostic value of urinary transferrin and ceruloplasmin to differentiate patients who have renal involvement from those who do not. MATERIALS AND METHODS: Systemic lupus erythematosus (SLE) patients that met the revised American College of Rheumatology (ACR) classification criteria were recruited. Patients with another autoimmune disease, active infection (urinary tract or systemic infection), renal replacement therapy, human immunodeficiency virus infection or pregnancy were excluded. A urine sample was collected from each patient. LN was diagnosed according to ACR criteria. The activity and chronicity of LN were measured using the Austin indices. Urinary transferrin and ceruloplasmin levels were measured using commercial enzyme-linked immunosorbent assay (ELISA) kits. Mann-Whitney U test and Student's t-test were used to compare data. Spearman's rank correlation was used to determine associations. Lastly, receiver operating characteristic (ROC) curves were created. RESULTS: The study involved 120 SLE patients. In all, 85% were female, 76% mestizo, the mean age was 32.8±12.1years and mean systemic lupus erythematosus disease activity index (SLEDAI) was 8.4±8.9; 64% had renal involvement. Urinary levels of the two biomarkers were significantly higher in patients with LN compared to those without LN. Similarly, urinary levels of both biomarkers were significantly higher in patients with active LN compared to those with inactive LN. Furthermore, urinary transferrin levels were significantly higher in Afro-Latin American patients. On the other hand, urinary transferrin levels correlated with SLEDAI and proteinuria, and transferrin and ceruloplasmin levels correlated with each other. The diagnostic value of ROC curves for these urinary biomarkers for LN were good. CONCLUSIONS: In our cohort of SLE patients, we found that transferrin and ceruloplasmin were potential biomarkers for LN, and can even differentiate active LN.

SerpinA3 in the Early Recognition of Acute Kidney Injury to Chronic Kidney Disease (CKD) transition in the rat and its Potentiality in the Recognition of Patients with CKD.

Recognizing patients at early phases of chronic kidney disease (CKD) is difficult, and it is even more challenging to predict acute kidney injury (AKI) and its transition to CKD. The gold standard to timely identify renal fibrosis is the kidney biopsy, an invasive procedure not usually performed for this purpose in clinical practice. SerpinA3 was identified by high-resolution-mass-spectrometry in urines from animals with CKD. An early and progressive elevation of urinary SerpinA3 (uSerpinA3) was observed during the AKI to CKD transition together with SerpinA3 relocation from the cytoplasm to the apical tubular membrane in the rat kidney. uSerpinA3/alpha-1-antichymotrypsin was significantly increased in patients with CKD secondary to focal and segmental glomerulosclerosis (FSGS), ANCA associated vasculitis (AAV) and proliferative class III and IV lupus nephritis (LN). uSerpinA3 levels were independently and positively associated with renal fibrosis. In patients with class V LN, uSerpinA3 levels were not different from healthy volunteers. uSerpinA3 was not found in patients with systemic inflammatory diseases without renal dysfunction. Our observations suggest that uSerpinA3 can detect renal fibrosis and inflammation, with a particular potential for the early detection of AKI to CKD transition and for the differentiation among lupus nephritis classes III/IV and V.

Urinary biomarkers for lupus nephritis: the role of the vascular cell adhesion molecule-1.

Renal involvement is one of the main complications of systemic lupus erythematosus, causing a significant impact on patients' morbidity and mortality. Renal biopsy is still the gold standard of diagnosis, but it has many limitations. In this sense, several recent studies aim to identify biomarkers that not only predict disease activity and renal histology, but also lead to earlier treatment. In previous studies, the soluble vascular cell adhesion molecule-1 measured in urine showed a strong association with the presence of lupus nephritis, with clinical and histological activity indexes of the disease and with more severe renal lesions. This paper reviews the main urinary biomarkers of lupus nephritis that have been studied, with special emphasis on vascular cell adhesion molecule-1 results.

HMGB1+ microparticles present in urine are hallmarks of nephritis in patients with systemic lupus erythematosus.

Non-classical monocytes infiltrate the kidney parenchyma and participate in tissue damage in patients with lupus nephritis (LN). Circulating microparticles (MPs) seem to play critical roles in the activation of monocytes in systemic lupus erythematosus (SLE) patients. This study aims to characterize the phenotypes of MPs and monocyte subsets in LN patients and to determine their potential to discriminate between SLE patients with and without LN. Blood and urine samples from SLE patients were collected. In monocyte subsets from whole blood samples several phenotypic markers were evaluated. MPs were isolated from platelet-poor plasma and urine by centrifugation. This phenotypic marker characterization was performed using multiparametric flow cytometry. We observed that patients with active LN have lower counts of non-classical monocytes than do those without renal involvement. All monocyte subsets exhibited lower expression of CX3CR1 and ICAM-1 in LN than in patients without LN. High frequencies of MP-HMGB1+ and MP-HLA-DR+ were detected in circulation and urine of LN patients. Although MP-HMGB1+ , MP-HLA-DR+ , and MP-CX3CR1+ from urine were able to discriminate between patients with and without LN, only urinary MP-HMGB1+ were different between patients with active and inactive LN. Therefore, these vesicles may be useful as biomarkers of LN.

Urinary neutrophil gelatinase-associated lipocalin and monocyte chemoattractant protein 1 as biomarkers for lupus nephritis in Colombian SLE patients.

Background Information regarding urinary biomarkers in Mestizo and Afro-Latin-American patients is very limited. We investigated whether levels of urinary neutrophil gelatinase-associated lipocalin (NGAL), and monocyte chemoattractant protein 1 (MCP-1) are good biomarkers to differentiate patients with lupus nephritis among Latin-American systemic lupus erythematosus (SLE) patients. Methods SLE patients meeting the revised American College of Rheumatology classification criteria for SLE were recruited. Urinary levels of NGAL and MCP-1 were measured using a commercial ELISA kit. Serum anti-C1q antibodies were measured by ELISA. SLE activity was measured with the systemic lupus erythematosus disease activity index (SLEDAI). Mann-Whitney tests were used to compare data and Spearman's rank correlations were used to examine associations between continuous variables. In addition, receiver operating characteristic curves were performed. Results One hundred and twenty SLE patients were recruited (87% women) with a median age of 32.8 ± 12.1 years and median disease duration of 7.3 ± 6.9 years. Afro-Latin-Americans had a significantly higher prevalence of lupus nephritis and higher SLEDAI scores than Mestizos. The three biomarkers were significantly higher in patients with lupus nephritis than in patients without lupus nephritis. In addition, urinary NGAL and MCP-1 were significantly higher in patients with active lupus nephritis than in inactive lupus nephritis. Urinary NGAL levels were significantly higher in Afro-Latin-American patients. A receiver operating characteristic curve for urinary biomarkers for lupus nephritis in all SLE patients showed a good level of sensitivity and specificity. Conclusion In our cohort of SLE patients, we found that urinary NGAL and MCP-1 in addition to anti-C1q antibodies were useful biomarkers for the identification of renal involvement and discrimination of active lupus nephritis among patients with renal disease.

Assessment of urinary TWEAK levels in Mexican patients with untreated lupus nephritis: An exploratory study.

OBJECTIVES: Urinary levels of TWEAK (uTWEAK) may be correlated with the degree of lupus nephritis (LN) activity. Our objective was to determine the sensitivity and specificity of uTWEAK in Mexican patients with untreated active lupus nephritis. METHODS: An exploratory study was performed; four groups of patients were analyzed as follows: 1) patients with systemic lupus erythematosus (SLE) without renal activity (SLE-LN), 2) patients with SLE with renal activity (SLE+LN), 3) patients with other types of glomerulopathy (glomerulonephritis, GMN), 4) and healthy patients (controls). RESULTS: In all, 44 patients, with an average age of 35.9±11.5 years, were evaluated. uTWEAK levels were higher in patients with SLE+LN compared with patients in the other groups: SLE+LN 12.88±8.33, SLE-LN 3.12±2.31, GMN 4.36±2.31 and controls 2.41±1.94pg/mg Cr (p=0.007). A total of 72.7% of the cases had renal activity index scores above 12, and 90.9% of the cases had scores of chronicity below 6 points. Receiver Operating Characteristic (ROC) curve analysis revealed that uTWEAK levels above 4.91pg/mg Cr had a sensitivity of 81% and a specificity of 75% for the diagnosis of renal activity due to lupus, with an area under the curve of 0.876 (95% CI: 0.75-0.99). However, no significant correlation was observed between the levels of uTWEAK and the histological findings specific to the activity and chronicity associated with SLE. CONCLUSIONS: Our study revealed that uTWEAK can adequately distinguish renal activity due to lupus, but cannot predict the degree of histological activity in Mexican patients with active lupus nephropathy.

Correlación clínico patológica y evolución de la nefropatía lúpica en niños y adolescentes / Clinicopathologic correlation and evolution of lupus nephritis in children and adolescents

El lupus eritematoso sistémico (LES) tiene una prevalencia baja en la población general y es menor en la edad pediátrica. La nefropatía lúpica (NL) es más frecuente y de mayor severidad que en adultos, condicionando la morbimortalidad de la enfermedad. Se realizó un estudio descriptivo prospectivo de 20 niños y adolescentes con NL controlados en la Policlínica de Colagenopatías del Centro Hospitalario Pereira Rossell en el período desde octubre de 2003 hasta setiembre de 2013 con el objetivo de describir las características clínico-serológicas y evolutivas de pacientes con NL y correlacionarlas con los hallazgos anátomopatológicos. La NL se observó en el 52,6% de los casos con LES. El 70% fueron de sexo femenino, relación femenino/masculino de 2,3/1, 85% de raza blanca, la mediana del diagnóstico fue de 12 años. Las formas de presentación fueron: alteraciones urinarias menores (AUM) en 14 pacientes (0,7), en cuatro casos síndrome nefrótico (SN), con o sin insuficiencia renal (IR) y/o hipertensión arterial. Un paciente se manifestó con síndrome nefrítico. Un paciente tenía un examen de orina normal. Las formas histopatológicas proliferativas graves se presentaron en 18 (0,9); los casos con AUM presentaban NL grado III-IV en 13 (0,93); todos los casos con SN con o sin IR tenían NL III-IV. No hubo casos de NL aislada como forma de comienzo. En el momento del diagnóstico, los anticuerpos antinucleares fueron positivos en 19 (0,95) y los anti DNA doble cadena en 16 (0,8); C3 y C4 estuvieron descendidos en 19 (0,95) y en 15 (0,75) respectivamente. El seguimiento promedio fue 4,2 años. Al final del seguimiento estaban en remisión 16 pacientes (0,8), cuatro en remisión parcial, todos con función renal normal, excepto un caso que presentó IR extrema, fue trasplantado y tuvo una excelente evolución. Un paciente falleció con hemorragia pulmonar. La sobrevida de la función renal y la de los pacientes fue 0,95 respectivamente. El tratamiento se realizó en base a corticoides, hidroxicloroquina asociados a azatioprina o micofenolato mofetilo. En ocho pacientes con cuadros graves se usó la ciclofosfamida I/V. Esta serie constituye la primera serie nacional de nefropatía lúpica en niños y adolescentes. Conclusión: predominó la presentación clínica con AUM y formas histopatológicas severas, clases III y IV, evidenciando una disociación clínico anatomopatológica. A pesar del elevado porcentaje de NL severas, el manejo adecuado y oportuno y la adherencia al tratamiento y a los controles médicos fueron fundamentales para la evolución favorable de la NL.

Systemic lupus erythematosus (SLE) has a low prevalence in the overall general population and this is lower in children. Child lupus nephropathy (LN) is more frequent and severe than in SLE adult patients, with greater disease morbidity and mortality. A prospective descriptive study of 20 children and adolescents with LN monitored in the Collagen Diseases Office of the Pereira Rossell Hospital between October, 2003 and September, 2013 was performed. The objective of this study was to describe clinical-serological features and the evolution of these patients and to correlate them with its anatomopathological findings. LN was diagnosed in 52,6% of the SLE patients, 70% were female with a female/male correlation of 2,3/1; 85% were Caucasian; median age at diagnosis was 12 years old. The clinical presentations were minor urinary findings (MUF) in 14 patients (0,7) and nephrotic syndrome (NS) in 4 (0,2), and another one nephritic syndrome. One patient presented no symptoms and had normal urinalysis. Severe proliferative classes predominated in18 patients (0.9); 13 (0.93) patients with MUF and all the patients with NS had LN classes III or IV. Isolated LN was not seen in the initial presentation. At the time of diagnosis antinuclear antibodies were positive in 19 patients (0.95); and anti DNA double stranded in 16 (0.8). Low C3 was found in 19 (0.95) and C4 in 15 (0.75), respectively. Average follow-up time was 4.2 years. At the end of follow-up 16 (0.8) were in remission, 4 of them in partial remission; all patients presented normal renal function except for one who evidenced severe renal failure and required hemodialysis and transplantation and had an excellent evolution. One patient died with pulmonary hemorrhage. The renal and patient survivals were 0.95 respectively. Treatment consisted in corticosteroids and hydroxychloroquine associated with azathioprine or mycophenolate mofetil. Cyclophosphamide was administered to 8 patients with severe illness. This is the first national report of LN in children and adolescents. Conclusions: the predominant clinical presentation of LN was MUF with severe anatomopathological findings, classes III and IV, showing a clinical-pathological dissociation. Despite the high percentage of severe LN, early and adequate treatment, as well as a good compliance to it with periodic medical follow-up, were essential to achieve a favorable outcome of LN.

Is there a role for urinary podocyte excretion assessment in lupus nephritis?

OBJECTIVE: To establish the occurrence and intensity of podocyturia and its relation to grade of disease activity, as defined by clinical and laboratory criteria. METHODS: Prospective, cross-sectional study involving 50 patients with lupus nephritis and 29 controls, which had podocyturia levels determined from random urine samples using an immunofluorescence technique. Disease activity was graded by BILAG (renal criteria) and an additional system used in the service (S2). RESULTS: Fifty patients with lupus nephritis (WHO classes III, IV and V), with a median age of 37 years, were evaluated. Of these, 86.5% were female, and 52% were BILAG A. Podocyturia quantification in the lupus nephritis and control groups differed significantly (p = 0.009). This score was higher in relation to classes III, IV and V. The correlation with C3 consumption was stronger (p = 0.011) than with C4. The highest levels were found in the most active groups (A and B of BILAG and S2). Lower podocyturia correlated with a lower dose of prednisone. There was no association with the intensity of proteinuria, hematuria or pyuria, serum creatinine levels, among others. CONCLUSIONS: Podocyturia assessment, which was performed by immunofluorescence in this study, can be used as an indicator of disease activity with the advantage of being a urinary biomarker. The levels proved to be higher in patients with lupus nephritis than in the controls and were particularly higher in class IV.

Correlación clínico patológica y evolución de la nefropatía lúpica en niños y adolescentes / Clinicopathologic correlation and evolution of lupus nephritis in children and adolescents

El lupus eritematoso sistémico (LES) tiene una prevalencia baja en la población general y es menor en la edad pediátrica. La nefropatía lúpica (NL) es más frecuente y de mayor severidad que en adultos, condicionando la morbimortalidad de la enfermedad. Se realizó un estudio descriptivo prospectivo de 20 niños y adolescentes con NL controlados en la Policlínica de Colagenopatías del Centro Hospitalario Pereira Rossell en el período desde octubre de 2003 hasta setiembre de 2013 con el objetivo de describir las características clínico-serológicas y evolutivas de pacientes con NL y correlacionarlas con los hallazgos anátomopatológicos. La NL se observó en el 52,6% de los casos con LES. El 70% fueron de sexo femenino, relación femenino/masculino de 2,3/1, 85% de raza blanca, la mediana del diagnóstico fue de 12 años. Las formas de presentación fueron: alteraciones urinarias menores (AUM) en 14 pacientes (0,7), en cuatro casos síndrome nefrótico (SN), con o sin insuficiencia renal (IR) y/o hipertensión arterial. Un paciente se manifestó con síndrome nefrítico. Un paciente tenía un examen de orina normal. Las formas histopatológicas proliferativas graves se presentaron en 18 (0,9); los casos con AUM presentaban NL grado III-IV en 13 (0,93); todos los casos con SN con o sin IR tenían NL III-IV. No hubo casos de NL aislada como forma de comienzo. En el momento del diagnóstico, los anticuerpos antinucleares fueron positivos en 19 (0,95) y los anti DNA doble cadena en 16 (0,8); C3 y C4 estuvieron descendidos en 19 (0,95) y en 15 (0,75) respectivamente. El seguimiento promedio fue 4,2 años. Al final del seguimiento estaban en remisión 16 pacientes (0,8), cuatro en remisión parcial, todos con función renal normal, excepto un caso que presentó IR extrema, fue trasplantado y tuvo una excelente evolución. Un paciente falleció con hemorragia pulmonar. La sobrevida de la función renal y la de los pacientes fue 0,95 respectivamente...

Relationship between urinary protein changes in lupus nephritis and renal pathology.

This study investigated the relationship between urinary protein excretion in lupus nephritis New Zealand black mice and renal pathology. A total of 328 lupus nephritis New Zealand black mice were established by a backcross hybridization method, and renal pathology was determined. The urinary protein excretion of the backcross mice over 24 h was compared and analyzed. Urinary protein excretion over 24 h differed significantly across different pathological types (1.9, 2.4, 2.9 and 4.9 g in types II, III, IV, and V, respectively) in the backcross mice (P < 0.05). Moreover, it correlated with pathology grade (r = 0.391, P = 0.0001) as well as activity index, chronic index, renal tubular interstitial activity index, and renal tubular interstitial lesions (P < 0.05) but not with vascular lesions (P = 0.683). Urinary protein excretion from lupus nephritis is closely associated with renal pathology. Urinary protein changes can be used to determine lupus nephritis pathology and have some clinical significance for treatment and prognosis.

Podocyte-associated mRNA profiles in kidney tissue and in urine of patients with active lupus nephritis.

AIM: Glomerular deposition of immune complexes and inflammation induce podocyte injury in lupus nephritis (LN). This study hypothesized that the severity of the histological lesions of LN affects podocyte-associated mRNAs profiles in kidney tissue and in urine. METHODS: Thirty-three patients with LN were grouped according to the presence of mild mesangial (classes I and II) or moderate-to-severe immune complex deposition, proliferation and/or inflammation (classes III, IV and V) in kidney biopsy. Tissue and urine mRNA of nephrin, podocin, podocalyxin, α-actinin-4, transient receptor potential cation channel 6, and of growth factors VEGF-A and TGF-ß1 and the transcription factor FOXP3 were measured using real time polymerase chain reaction. These mRNAs were correlated with histological severity of LN, extent of glomerular immune deposits, and tissue infiltrating cells. RESULTS: Podocyte-associated mRNAs were inhibited in renal tissue of patients with LN irrespective of histological class when compared to controls. However, significantly higher expression of podocyte mRNAs in urine, including those of growth factors and FOXP3, were found in patients with moderate-to-severe nephritis, mostly in class III and IV proliferative forms. The number of invading CD8+ T cells, B cells and macrophages correlated positively with urine podocyte-associated mRNAs. Urine podocyte mRNAs also correlated with proteinuria. CONCLUSIONS: Inhibition of podocyte-associated mRNAs in kidney tissue suggests that podocyte injury occurs regardless of class severity of LN. Increased urinary excretion of podocyte mRNAs, mostly in patients with moderate-to-severe lesions, may reflect a greater burden of glomerular damage with detachment of podocytes into the urine.

Detecção de podocitúria em pacientes com nefrite lúpica / Detection of podocyturia in patients with lupus nephritis

INTRODUÇÃO: A podocitúria tem sido detectada em doenças glomerulares, tais como em nefrite lúpica (NL), em que a proteinúria é uma manifestação importante, e sua ocorrência parece limitar-se à fase ativa da doença. OBJETIVO: Avaliar a podocitúria por imunofluorescência em pacientes portadores de NL e verificar possível associação com atividade clínica da doença. MÉTODOS: Foram avaliados 56 pacientes com NL. Os pacientes foram divididos em três grupos de acordo com o grau de atividade clínica: Grupo B, sem atividade (n = 17); Grupo C, com atividade discreta (n = 29) e Grupo D, moderada a grave (n = 10). Como grupo controle, foram incluídos 29 indivíduos saudáveis (Grupo A). A podocitúria foi estudada por meio de imunofluorescência indireta, usando-se anticorpos primários antipodocina, nefrina e sinaptopodina, e anticorpo secundário conjugado à FITC. Também foram avaliados os níveis de creatinina sérica e da relação proteína/creatinina (P/C) urinária, assim como a presença de hematúria e leucocitúria. RESULTADOS: A podocitúria com antipodocina e com antissinaptopodina correlacionou-se estatisticamente com a relação P/C (p = 0,001 e p = 0,013, respectivamente). Tanto a podocitúria com antipodocina, quanto a relação P/C, apresentaram correlação significante (p < 0,001) com a graduação de atividade da doença na NL, diferentemente do que se observou com os outros dois anticorpos, antinefrina e antissinaptopodina. CONCLUSÃO: Nossos achados sugerem que a pesquisa de podocitúria com anticorpos antipodocina poderia ser útil no acompanhamento de pacientes com NL, fornecendo dados relevantes quanto à atividade da doença.

INTRODUCTION: The podocyturia has been detected in glomerular diseases, such as lupus nephritis (LN), in which proteinuria is an important manifestation, and its occurrence seems to be limited to the active phase of the disease. OBJECTIVE: To evaluate podocyturia in LN patients, and the possible association with clinical disease activity. METHODS: We evaluated 56 patients with LN, that were classified in three groups according to the degree of clinical activity: Group B, no activity (n = 17), Group C with mild (n = 29) and Group D, moderate to severe activity (n = 10). The control group was composed by 29 healthy subjects (Group A). The podocyturia was studied by indirect immunofluorescence using primary antibodies to podocyte: anti-podocin, nephrin and synaptopodin, and a secondary antibody conjugated with FITC. We also evaluated serum creatinine levels, urinary protein/creatinine (P/C) ratio, hematuria and leucocituria. RESULTS: The podocyturia with anti-podocin and anti-sinaptopodin correlated statistically with the P/C ratio (p = 0.001 and p = 0.013, respectively). The podocyturia with anti-podocin, as well as the P/C ratio showed significant correlation (p < 0.001) with the degree of lupus disease activity, unlike the other two antibodies, anti-nephrin and anti-synaptopodin. CONCLUSION: Our findings show that podocyturia with anti-podocin could be useful in monitoring disease activity in LN patients.

Detection of podocyturia in patients with lupus nephritis.

INTRODUCTION: The podocyturia has been detected in glomerular diseases, such as lupus nephritis (LN), in which proteinuria is an important manifestation, and its occurrence seems to be limited to the active phase of the disease. OBJECTIVE: To evaluate podocyturia in LN patients, and the possible association with clinical disease activity. METHODS: We evaluated 56 patients with LN, that were classified in three groups according to the degree of clinical activity: Group B, no activity (n = 17), Group C with mild (n = 29) and Group D, moderate to severe activity (n = 10). The control group was composed by 29 healthy subjects (Group A). The podocyturia was studied by indirect immunofluorescence using primary antibodies to podocyte: anti-podocin, nephrin and synaptopodin, and a secondary antibody conjugated with FITC. We also evaluated serum creatinine levels, urinary protein/creatinine (P/C) ratio, hematuria and leucocituria. RESULTS: The podocyturia with anti-podocin and anti-sinaptopodin correlated statistically with the P/C ratio (p = 0.001 and p = 0.013, respectively). The podocyturia with anti-podocin, as well as the P/C ratio showed significant correlation (p < 0.001) with the degree of lupus disease activity, unlike the other two antibodies, anti-nephrin and anti-synaptopodin. CONCLUSION: Our findings show that podocyturia with anti-podocin could be useful in monitoring disease activity in LN patients.

Monocyte chemoattractant-1 as a urinary biomarker for the diagnosis of activity of lupus nephritis in Brazilian patients.

OBJECTIVE: Monocyte chemotactic protein (MCP-1), involved in the pathogenesis of lupus nephritis (LN), has recently been indicated as a new biomarker of kidney activity in systemic lupus erythematosus (SLE). Our aim was to assess urinary MCP-1 (uMCP-1) as a biomarker of renal activity in patients with SLE and to compare it to other disease activity markers, using the ELISA. METHODS: Seventy-five female Brazilian patients with SLE and a control group participated in our study. Patients with SLE were distributed among 3 groups according to kidney involvement and classified according to disease activity based on clinical and laboratory measures such as urinary sediment, proteinuria, kidney function, C3, C4, anti-dsDNA, disease activity index, and renal SLE disease activity index. The serum and uMCP-1 concentrations were measured by sandwich ELISA. RESULTS: In the A-LN group (active lupus nephritis: SLE with kidney involvement), the concentration of uMCP-1 was significantly higher than in other groups. A cutoff point was established using the results of the control group to apply this test in the detection of LN. A-LN had a higher frequency of positive results for uMCP-1 in comparison to the other groups (p < 0.001). To detect disease activity in patients with LN, a new cutoff was determined based on the results of patients with SLE with kidney involvement. Setting specificity at 90%, the sensitivity of the test was 50%. CONCLUSION: The high specificity makes uMCP-1 a useful test as a predictor of kidney activity in SLE, especially when associated to other measures used in clinical practice.

Urinary protein/creatinine ratio versus 24-hour proteinuria in the evaluation of lupus nephritis.

INTRODUCTION: The urinary protein/creatinine ratio has been used instead of 24-hour proteinuria in Nephrology practice for the follow-up of glomerular diseases, considering the advantages of collection and the low cost. However, there are still doubts as to its applicability both for an isolated evaluation and for the follow-up of patients with lupus nephritis. OBJECTIVE: To evaluate 24-hour proteinuria determinations and random urine samples, performing urinary creatinine correction and urinary protein/creatinine ratio in subjects with lupus nephritis. METHODS: 24-hour proteinuria and urinary protein/creatinine ratio were determined by conventional methods (automated Pyrogallol for proteinuria and alkaline picrate for creatinine). RESULTS: Seventy-eight urine samples of 41 patients diagnosed with systemic lupus erythematosus, according to the American Rheumatology Association, with lupus nephritis, were analyzed, and a good correlation between 24-hour proteinuria and urinary protein/creatinine ratio (r = 0.9010 and r² = 0.813) was observed. However, a poor correlation between random proteinuria (without creatinine correction) versus 24-hour proteinuria (r = 0.635 and r² = 0.403) or versus urinary protein/creatinine ratio (r = 0.754 and r² = 0.569) was seen. CONCLUSION: 24-hour proteinuria and urinary protein/creatinine ratio were useful in the follow-up of each case. However, we observed that the absolute values were different, which did not allow the replacement of one for the other during follow-up, especially when this result is used to define the activity of the disease. Based on these results, we suggest a period of intersection from one to the other (two to three determinations by both methods), and the choice of one marker for proteinuria follow-up, if necessary.

Relação proteína/creatinina na urina versus proteinúria de 24 horas na avaliação de nefrite lúpica / Urinary protein/creatinine ratio versus 24-hour proteinuria in the evaluation of lupus nephritis

INTRODUÇÃO: Tem-se defendido a utilização do índice urinário proteína e creatinina em substituição à determinação de proteinúria de 24 horas para acompanhamento de doenças glomerulares, considerando-se as vantagens de maior facilidade na coleta e o menor custo. Entretanto, há dúvidas quanto à pertinência de usar este índice tanto numa avaliação isolada como no seguimento de pacientes com nefrite lúpica. OBJETIVO: Avaliar as determinações de proteinúria de 24 horas e proteinúria em amostra isolada de urina, fazendo a correção pela creatinina urinária, relação proteinúria/creatininúria, em indivíduos com nefrite lúpica. MÉTODOS: Determinações de proteinúria de 24 horas e relação proteinúria/creatininúria por métodos convencionais (Pirogalol automatizado para proteinúria e picrato alcalino para creatinina). RESULTADOS: Foram comparadas 78 amostras de urina de 41 pacientes com diagnóstico de lúpus eritematoso sistêmico, segundo os critérios da Associação Americana de Reumatologia, com nefrite lúpica, constatando-se uma boa correlação entre proteinúria de 24 horas e relação proteinúria/creatininúria (r = 0,9010 e r² = 0,813). Não se observou, entretanto, uma boa correlação entre proteinúria em amostra isolada (sem correção pela creatinina urinária) versus aquela de 24 horas (r = 0,635 e r² = 0,403) ou versus relação proteinúria/creatininúria (r = 0,754 e r² = 0,569). CONCLUSÃO: Os marcadores de proteinúria de 24 horas e relação proteinúria/creatininúria isoladamente mostraram-se úteis no acompanhamento de cada caso. Porém, observou-se que os seus valores absolutos são diferentes, não possibilitando a substituição de um pelo outro ao longo do seguimento, particularmente quando este resultado é usado para definição de atividade da doença. Se necessário, sugere-se um período de intersecção (duas a três determinações pelos dois métodos) para mudança de um para outro e escolha de um único marcador preferencial para seguimento da proteinúria.

INTRODUCTION: The urinary protein/creatinine ratio has been used instead of 24-hour proteinuria in Nephrology practice for the follow-up of glomerular diseases, considering the advantages of collection and the low cost. However, there are still doubts as to its applicability both for an isolated evaluation and for the follow-up of patients with lupus nephritis. OBJECTIVE: To evaluate 24-hour proteinuria determinations and random urine samples, performing urinary creatinine correction and urinary protein/creatinine ratio in subjects with lupus nephritis. METHODS: 24-hour proteinuria and urinary protein/creatinine ratio were determined by conventional methods (automated Pyrogallol for proteinuria and alkaline picrate for creatinine). RESULTS: Seventy-eight urine samples of 41 patients diagnosed with systemic lupus erythematosus, according to the American Rheumatology Association, with lupus nephritis, were analyzed, and a good correlation between 24-hour proteinuria and urinary protein/creatinine ratio (r = 0.9010 and r² = 0.813) was observed. However, a poor correlation between random proteinuria (without creatinine correction) versus 24-hour proteinuria (r = 0.635 and r² = 0.403) or versus urinary protein/creatinine ratio (r = 0.754 and r² = 0.569) was seen. CONCLUSION: 24-hour proteinuria and urinary protein/creatinine ratio were useful in the follow-up of each case. However, we observed that the absolute values were different, which did not allow the replacement of one for the other during follow-up, especially when this result is used to define the activity of the disease. Based on these results, we suggest a period of intersection from one to the other (two to three determinations by both methods), and the choice of one marker for proteinuria follow-up, if necessary.