Expression of chemokine and fibrosing factor messenger RNA in the urinary sediment of patients with lupus nephritis

Soluble TNF-R1, VEGF and other cytokines as markers of disease activity in systemic lupus erythematosus and lupus nephritis

Background

Current non-invasive methods of assessing disease activity in systemic lupus erythematosus (SLE) are of limited sensitivity and specificity. Testing includes acute phase markers, autoantibodies and complement levels. Although measurements of dsDNA antibodies and complement C3/C4 levels are routine, they remain of limited value. Improved blood and urine markers may help in early detection of flare, distinction between flare and chronic damage, and monitoring response to therapy.

Methods

A total of 87 patients with SLE were tested for the following cytokines in serum and urine: monocyte chemoattractant protein 1 (MCP-1), regulated upon activation, normal T cell expressed and secreted (RANTES), soluble tumour necrosis factor receptor 1 (sTNF-R1), interferon-inducible protein 10 (IP-10), monocyte inhibitory protein 1α (MIP-1α) and vascular endothelial growth factor (VEGF). Patients attending the Lupus Unit at St Thomas’ Hospital, London, UK were divided into active lupus nephritis (LN), inactive LN and non-renal SLE groups based on their renal pathology and SLE disease activity index (SLEDAI). Cytokine testing was performed using the FIDIS multiplex bead assay.

Results

The mean level of serum sTNF-R1 was higher in the active LN group compared with both inactive LN and non-renal SLE groups ( p < 0.001). For urine measurements there were significant differences between active LN and non-renal SLE for VEGF ( p = 0.016), after statistical correction for multiple testing. Both urinary and serum sTNF-R1 and IP-10 levels correlated with SLEDAI scores ( p < 0.001), while serum VEGF correlated weakly with SLEDAI ( p = 0.025). The optimum combination for differentiating active from inactive LN patients was serum VEGF, sTNF-R1, MCP-1 and glomerular filtration rate plus urinary sTNF-R1 and protein-creatinine ratio.

Conclusion

These results indicate that for active LN, sTNF-R1 could be a useful serum cytokine marker, with potential for VEGF in the urine. This study has confirmed the ability of the multiplex bead technique to detect cytokines in a good analytical range, including very low and high levels, in both serum and urine. Combining serum and urine markers provided additional sensitivity in distinguishing active from inactive LN.

Urine biomarkers of chronic kidney damage and renal functional decline in childhood-onset systemic lupus erythematosus

OBJECTIVES

To delineate urine biomarkers that reflect kidney structural damage and predict renal functional decline in pediatric lupus nephritis (LN).

METHODS

In this prospective study, we evaluated kidney biopsies and urine samples of 89 patients with pediatric LN. Urinary levels of 10 biomarkers [adiponectin, ceruloplasmin, kidney injury molecule-1, monocyte chemotactic protein-1, neutrophil gelatinase-associated lipocalin, osteopontin, transforming growth factor-ß (TGFß), vitamin-D binding protein, liver fatty acid binding protein (LFABP), and transferrin] were measured. Regression analysis was used to identify individual and combinations of biomarkers that determine LN damage status [NIH-chronicity index (NIH-CI) score ≤ 1 vs. ≥ 2] both individually and in combination, and biomarker levels were compared for patients with vs. without renal functional decline, i.e., a 20% reduction of the glomerular filtration rate (GFR) within 12 months of a kidney biopsy.

RESULTS

Adiponectin, LFABP, and osteopontin levels differed significantly with select histological damage features considered in the NIH-CI. The GFR was associated with NIH-CI scores [Pearson correlation coefficient (r) = - 0.49; p < 0.0001] but not proteinuria (r = 0.20; p > 0.05). Similar to the GFR [area under the ROC curve (AUC) = 0.72; p < 0.01], combinations of osteopontin and adiponectin levels showed moderate accuracy [AUC = 0.75; p = 0.003] in discriminating patients by LN damage status. Renal functional decline occurred more commonly with continuously higher levels of the biomarkers, especially of TGFß, transferrin, and LFABP.

CONCLUSION

In combination, urinary levels of adiponectin and osteopontin predict chronic LN damage with similar accuracy as the GFR. Ongoing LN activity as reflected by high levels of LN activity biomarkers heralds renal functional decline.

KEY MESSAGES

• Levels of osteopontin and adiponectin measured at the time of kidney biopsy are good predictors of histological damage with lupus nephritis. • Only about 20% of children with substantial kidney damage from lupus nephritis will have an abnormally low urine creatinine clearance. • Continuously high levels of biomarkers reflecting lupus nephritis activity are risk factors of declining renal function.

Combined utilization of untimed single urine of MCP-1 and TWEAK as a potential indicator for proteinuria in lupus nephritis: A case-control study

The aim of this study was to determine whether combined utilization of untimed single urine monocyte chemoattractant protein 1 (uMCP-1) and tumor necrosis factor (TNF)-like weak inducer of apoptosis (uTWEAK) could serve as a screening test for proteinuria in patients with lupus nephritis (LN).A case-control study that contained 39 biopsy-proven LN patients, 20 non-LN systemic lupus erythematosus (SLE) patients, and 10 healthy controls (HCs) were carried out. Correlations between uMCP-1, uTWEAK, and traditional clinical markers were analyzed by Spearman correlation test. Diagnostic values of uMCP-1, uTWEAK, and urine albumin/creatinine ratio (uACR) in the assessment of proteinuria were investigated by receiver operating characteristic (ROC) curves.Biopsy-proven LN patients showed higher levels of uMCP-1 and uTWEAK than non-LN patients. uMCP-1 and uTWEAK were elevated in renal active patients (rSLEDAI ≥4). Both uMCP-1 and uTWEAK showed significant correlation with patients' rSLEDAI, 24-hour urine proteinuria (24hr UP), and anti-double-stranded DNA (anti-dsDNA) antibodies. No correlations of these 2 biomarkers between cystatin C (Cys-C), creatinine (Cr), and blood urea nitrogen (BUN) were observed. An algorithm combining the moderate sensitivity of uMCP-1 and high specificity of uTWEAK displayed great specificity and sensitivity for proteinuria screening.Both uMCP-1 and uTWEAK were positively correlated with the impairments of LN, and the combined utility of untimed single uMCP-1 and uTWEAK might be used as potential predictors for proteinuria in LN.

Urinary Albumin Levels are Independently Associated with Renal Lesion Severity in Patients with Lupus Nephritis and Little or No Proteinuria

Background

Systemic lupus erythematosus (SLE) leads to renal lesions, which may be clinically silent in patients with little or no proteinuria. Early detection of these lesions may improve prognosis, but early markers are controversial. This study aimed to determine renal marker proteins associated with renal lesion severity in patients with lupus nephropathy (LN) and little or no proteinuria.

Material/Methods

Patients with LN and little or no proteinuria (<0.5 g/24 hours) (n=187) that underwent kidney biopsy were grouped according to: low severity (Class I or II; n=116) versus high severity (Class III, IV, or V; n=71). Disease status was determined according to the SLE disease activity index (SLEDAI). Renal marker proteins (serum β2-macroglobulin, urinary β2-macroglobulin, albumin, IgG, and α1-macroglobulin) were measured using radioimmunoassay.

Results

Compared with the low severity group, patients in the high severity group had higher urinary albumin (11.60±8.94 versus 7.08±10.07 μg/mL, p=0.008) and urinary IgG (13.21±9.35 versus 8.74±8.90 μg/mL, p=0.007) levels. Multivariate conditional logistic regression analysis showed that urinary albumin (odds ratio (OR)=1.417, 95% confidence interval (95% CI): 1.145–1.895, p=0.001) and SLEDAI (OR=2.004, 95% CI: 1.264–3.178, p=0.003) were independently associated with severe renal lesions in these patients. Using an optimal cutoff point of urinary albumin of 7.53 μg/mL resulted in 67% sensitivity and 82% specificity for the detection of high severity renal lesions.

Conclusions

Urinary albumin levels and SLEDAI were independently associated with histological severity of renal lesions in patients with LN and little or no proteinuria. These parameters could be used to help select patients for renal biopsy.

Potential serum and urine biomarkers in patients with lupus nephritis and the unsolved problems

Lupus nephritis (LN) is one of the most frequent and serious complications in the patients with systemic lupus erythematosus. Autoimmune-mediated inflammation in both renal glomerular and tubulointerstitial tissues is the major pathological finding of LN. In clinical practice, the elevated anti-dsDNA antibody titer concomitant with reduced complement C3 and C4 levels has become the predictive and disease-activity surrogate biomarkers in LN. However, more and more evidences suggest that autoantibodies other than anti-dsDNA antibodies, such as anti-nucleosome, anti-C1q, anti-C3b, anti-cardiolipin, anti-endothelial cell, anti-ribonuclear proteins, and anti-glomerular matrix (anti-actinin) antibodies, may also involve in LN. Researchers have demonstrated that the circulating preformed and in situ-formed immune complexes as well as the direct cytotoxic effects by those cross-reactive autoantibodies mediated kidney damage. On the other hand, many efforts had been made to find useful urine biomarkers for LN activity via measurement of immune-related mediators, surface-enhanced laser desorption/ionization time-of-flight mass spectrometry proteomic signature, and assessment of mRNA and exosomal-derived microRNA from urine sediment cell. Our group had also devoted to this field with some novel findings. In this review, we briefly discuss the possible mechanisms of LN and try to figure out the potential serum and urine biomarkers in LN. Finally, some of the unsolved problems in this field are discussed.

Lupus nephritis biomarkers

Lupus nephritis (LN), a potentially destructive outcome of SLE, is a real challenge in the management of SLE because of the difficulty in diagnosing its subclinical onset and identifying relapses before serious complications set in. Conventional clinical parameters such as proteinuria, GFR, urine sediments, anti-dsDNA and complement levels are not sensitive or specific enough for detecting ongoing disease activity in lupus kidneys and early relapse of nephritis. There has long been a need for biomarkers of disease activity in LN. Such markers ideally should be capable of predicting early sub-clinical flares and could be used to gauge response to therapy, thus obviating the need for serial renal biopsies with their possible hazardous complications. Since urine can be readily obtained, it lends itself as an obvious biological substrate. In this review, the use of urine and serum as sources of lupus nephritis biomarkers is described, and the results of biomarker discovery studies using candidate and proteomic approaches are summarized.

Chemokines and Chemokine Receptors in the Development of Lupus Nephritis

Lupus nephritis (LN) is a major cause of morbidity and mortality in the patients with systemic lupus erythematosus (SLE), an autoimmune disease with damage to multiple organs. Leukocyte recruitment into the inflamed kidney is a critical step to promote LN progression, and the chemokine/chemokine receptor system is necessary for leukocyte recruitment. In this review, we summarize recent studies on the roles of chemokines and chemokine receptors in the development of LN and discuss the potential and hurdles of developing novel, chemokine-based drugs to treat LN.

Biomarkers for kidney involvement in pediatric lupus

Lupus nephritis (LN), the renal involvement in systemic lupus erythematosus, is currently diagnosed by histopathology obtained by percutaneous renal biopsy and is associated with increased morbidity and mortality in both adults and children. LN is more prevalent and severe in children, requiring aggressive and prolonged immunosuppression. The consequences of the diagnosis and its treatment have devastating long-term effects on the growth, well-being and quality of life of affected children. The paucity of reliable clinical indicators of the presence and severity of renal involvement have contributed to a halt in the reduction of progression to end-stage renal disease in recent years. Here, we discuss the recent development of biomarkers in the management of LN and their role as therapeutic targets.

Serum and Urinary Interleukin-6 in Assessment of Renal Activity in Egyptian Patients with Systemic Lupus Erythematosus

AIM OF THE WORK

This study investigates whether serum and urinary interleukin-6 (IL-6) represent an early marker of kidney involvement and assesses the difference between them and renal biopsy in lupus nephritis (LN).

PATIENTS AND METHODS

A total of 60 systemic lupus erythematosus (SLE) patients were compared to 20 healthy controls. Urinary and serum IL-6 were measured in both patients and controls. In addition, renal biopsy was done prior or shortly after urine and blood sampling; the results were classified according to the International Society of Nephrology/Renal Pathology Society classification of LN by recording the activity score and chronicity score for each sample.

RESULTS

There was a significant higher level of urinary IL-6 in the SLE patients with biopsy-proven LN than in those without LN and those of the control group. However, no significant difference was reported between the three groups as regards serum IL-6. A strong positive correlation was found between urinary IL-6 and renal disease activity based on the renal SLE disease activity index (SLEDAI) score with no significant correlation regarding the extra renal SLEDAI. Urinary IL-6 was positively correlated with renal biopsy results and with its activity scores but weakly correlated with the chronicity scores.

CONCLUSION

Urinary IL-6 may provide a simple noninvasive potential marker of disease activity of renal involvement in adult patients with SLE.

Urine Monocyte Chemoattractant Protein-1 and Lupus Nephritis Disease Activity: Preliminary Report of a Prospective Longitudinal Study

Objective. This longitudinal study aimed to determine the urine monocyte chemoattractant protein-1 (uMCP-1) levels in patients with biopsy-proven lupus nephritis (LN) at various stages of renal disease activity and to compare them to current standard markers. Methods. Patients with LN—active or inactive—had their uMCP-1 levels and standard disease activity markers measured at baseline and 2 and 4 months. Urinary parameters, renal function test, serological markers, and renal SLE disease activity index-2K (renal SLEDAI-2K) were analyzed to determine their associations with uMCP-1. Results. A hundred patients completed the study. At each visit, uMCP-1 levels (pg/mg creatinine) were significantly higher in the active group especially with relapses and were significantly associated with proteinuria and renal SLEDAI-2K. Receiver operating characteristic (ROC) curves showed that uMCP-1 was a potential biomarker for LN. Whereas multiple logistic regression analysis showed that only proteinuria and serum albumin and not uMCP-1 were independent predictors of LN activity. Conclusion. uMCP-1 was increased in active LN. Although uMCP-1 was not an independent predictor for LN activity, it could serve as an adjunctive marker when the clinical diagnosis of LN especially early relapse remains uncertain. Larger and longer studies are indicated.

Urinary cell mRNA profiles predictive of human kidney allograft status

Kidney allograft status is currently characterized using the invasive percutaneous needle core biopsy procedure. The procedure has become safer over the years, but challenges and complications still exist including sampling error, interobserver variability, bleeding, arteriovenous fistula, graft loss, and even death. Because the most common type of acute rejection is distinguished by inflammatory cells exiting the intravascular compartment and gaining access to the renal tubular space, we reasoned that a kidney allograft may function as an in vivo flow cytometer and sort cells involved in rejection into urine. To test this idea, we developed quantitative polymerase chain reaction (PCR) assays for absolute quantification of mRNA and pre-amplification protocols to overcome the low RNA yield from urine. Here, we review our single center urinary cell mRNA profiling studies that led to the multicenter Clinical Trials in Organ Transplantation (CTOT-04) study and the discovery and validation of a 3-gene signature of 18S rRNA-normalized measures of CD3ε mRNA and IP-10 mRNA and 18S rRNA that is diagnostic and predictive of acute cellular rejection in the kidney allograft. We also review our development of a 4-gene signature of mRNAs for vimentin, NKCC2, E-cadherin, and 18S rRNA diagnostic of interstitial fibrosis/tubular atrophy (IF/TA).

Changes to signal peptide and the level of transforming growth factor- β1 due to T869C polymorphism of TGF β1 associated with lupus renal fibrosis

Lupus Nephritis (LN) is a serious manifestation of lupus that can lead to End Stage Renal Disease (ESRD). Fibrosis is the main feature of ESRD, and it is likely influenced by Transforming Growth Factor Beta1 (TGFβ1). The T869C gene polymorphism of TGFβ1 is assumed to change the signal peptide, that has potential to interfere the urine production and renal protein expression of TGFβ1. The influence of T869C gene polymorphism on TGFβ1 production and renal fibrosis was evaluated in this study. Subjects were 45 patients LN with renal fibrosis and 45 participants without renal fibrosis as control, that were recruited from 2011 to 2013.Their urinary TGFβ1 levels and TGFβ1 gene polymorphisms were examined. All lupus patients underwent renal biopsy to assess their protein expression of TGFβ1 in the renal tissue by immunohistochemistry and their renal fibrosis by morphometry and chronicity index. Changes in the signal peptide interaction with Signal Recognition Particle (SRP) and translocon of endoplasmic reticulum were analyzed by Bioinformatics. Levels of urinary and protein expression of TGFβ1 increased in the LN with renal fibrosis group. There were significant differences in levels of urinary TGFβ1 in T, C allele and TT, TC, CC genotypes between case and control groups. Furthermore, patients with C allele are 3.86 times more at risk of renal fibrosis than T allele. The C allele encodes proline, which stabilizes the interaction of the TGFβ1 signal peptide with SRP and translocon, resulting in elevation of TGFβ1 secretion. Our results indicated that T869C gene polymorphism of TGFβ1 changes the signal peptide, that contributes to the production of urinary TGFβ1 and affects renal fibrosis in lupus nephritis.

Urinary mRNA in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a relapsing autoimmune disease with clinical manifestations that affect multiple organ systems. Lupus nephritis is recognized as one of the most severe organ involvements in SLE and affects half of the lupus patients. Notably, lupus nephritis is characterized by intrarenal lymphocyte activation and inflammation. Since most of the cytokines exert their effects in a paracrine fashion, measuring their expression at the site of pathology should be of biological relevance. Although kidney biopsy is widely used to determine the histology and severity of lupus nephritis, this invasive procedure has its own risk and is not practical for serial monitoring. In the past decade, extraction and quantification of messenger RNA (mRNA) from urinary sediment has emerged as a robust laboratory technique. Quantification of mRNA expression in urinary sediment has been tested as a noninvasive means to assess the disease activity of SLE patients. Available published evidence, however, is limited to small-scale studies. Based on the result of these studies, a number of cytokine and transcript factor genes have been found to have potential for the differentiation between active and inactive SLE, between proliferative and membranous types of lupus nephritis, assessment of the systemic lupus activity or histological activity of kidney biopsy specimen, monitoring of treatment response in active lupus nephritis, or detection of lupus disease flare in clinically quiescent patients. Being a simple and noninvasive method, urinary mRNA level deserves further studies to validate its role in risk stratification and monitoring of therapeutic response in patients with lupus nephritis.

Urinary monocyte chemotactic protein-1 and transforming growth factor-β in systemic lupus erythematosus

The purpose of this investigation was to assess the correlation of two biomarkers with the occurrence of renal flares in systemic lupus erythematosus (SLE). Urine levels of monocyte chemotactic protein-1 (MCP-1) and transforming growth factor beta (TGF-β) were measured at baseline, and at two and four months in five groups of patients: 25 lupus nephritis patients with active disease (active LN), 10 lupus nephritis patients with SLE in remission (remission LN), 25 patients with clinical active SLE and without nephritis (active NLN), 10 patients without nephritis with SLE in remission (remission NLN) and 10 healthy controls. We used repeated measurement and ANOVA with Duncan's post hoc to analyze the data; the urine level of the two proteins could distinguish the groups based on the existence of lupus nephritis and/or activity of SLE disease. Furthermore we performed receiver operating curve analysis to identify a cutoff point with a good sensitivity and specificity to diagnose lupus nephritis with either one of the urine proteins. Finally the samples from active LN were grouped according to whether they were Class IV or other classes. Baseline urinary MCP-1, but not TGF-β, was significantly different between the classes. Further investigation into the use of these cytokines in a prospective study is needed to determine their capacity as diagnostic tools for renal flares.

Autoantibodies in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a multifactorial disorder with multigenic inheritance and various environmental factors implicated in its aetiopathogenesis. Despite the multiple mechanisms involved in the aetiology of SLE being elusive, recent studies have made progress in our understanding of the pathogenic mechanisms via abnormal regulation of cell-mediated and humoral immunity that lead to tissue damage. The heterogeneity of the clinical manifestations probably reflects the complexity of the disease pathogenesis itself. The immune system in SLE is characterised by a complex interplay between overactive B cells, abnormally activated T cells and antigen-presenting cells. This interplay leads to the production of an array of inflammatory cytokines, apoptotic cells, diverse autoantibodies and immune complexes that in turn activate effector cells and the complement system, leading to tissue injury and damage which are the hallmarks of the clinical manifestations. SLE patients have dysregulation of inflammatory cytokines, chemokines and immune response-related genes, as well as of the genes involved in apoptosis, signal transduction and the cell cycle.

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.

Inhibition of the TWEAK/Fn14 pathway attenuates renal disease in nephrotoxic serum nephritis

Previously it was shown that the TNF superfamily member TWEAK (TNFSF12) acts through its receptor, Fn14, to promote proinflammatory responses in kidney cells, including the production of MCP-1, RANTES, IP-10 and KC. In addition, the TWEAK/Fn14 pathway promotes mesangial cell proliferation, vascular cell activation, and renal cell death. To study the relevance of the TWEAK/Fn14 pathway in the pathogenesis of antibody-induced nephritis using the mouse model of nephrotoxic serum nephritis (NTN), we induced NTN by passive transfer of rabbit anti-glomerular antibodies into Fn14 knockout (KO) and wild type (WT) mice. Severe proteinuria as well as renal histopathology were induced in WT but not in Fn14 KO mice. Similarly, a pharmacologic approach of anti-TWEAK mAb administration into WT mice in the NTN model significantly ameliorated proteinuria and improved kidney histology. Anti-TWEAK treatment did not affect the generation of mouse anti-rabbit antibodies; however, within the kidney there was a significant decrease in glomerular immunoglobulin deposition, as well as macrophage infiltrates and tubulointerstitial fibrosis. The mechanism of action is most likely due to reductions in downstream targets of TWEAK/Fn14 signaling, including reduced renal expression of MCP-1, VCAM-1, IP-10, RANTES as well as Fn14 itself, and other molecular pathways associated with fibrosis in anti-TWEAK treated mice. Thus, TWEAK/Fn14 interactions are instrumental in the pathogenesis of nephritis in the NTN model, apparently mediating a cascade of pathologic events locally in the kidney rather than by impacting the systemic immune response. Disrupting TWEAK/Fn14 interactions may be an innovative kidney-protective approach for the treatment of lupus nephritis and other antibody-induced renal diseases.

Relationship of Intrarenal Gene Expression and the Histological Class of Lupus Nephritis — A Study on Repeat Renal Biopsy

Objective.

To study the role of tumor necrosis factor (TNF)-like weak inducer of apoptosis (TWEAK)/Fn14 and the interferon-inducible protein (IP-10)/CXCR3 axis in lupus nephritis (LN).

Methods.

We studied 113 patients with LN who had had repeat renal biopsies. Glomerular and tubulointerstitial messenger RNA expression of TWEAK, Fn14, IP-10, and CXCR3 were quantified.

Results.

Glomerular Fn14 expression decreased when changed from proliferative or mixed nephritis to membranous nephropathy (p = 0.016), and increased when changed from membranous to proliferative or mixed nephritis (p = 0.0006). On the other hand, tubulointerstitial TWEAK expression decreased when changed from proliferative or mixed nephritis to membranous nephropathy (p = 0.004), and increased when changed from membranous nephropathy to proliferative nephritis (p = 0.010). Tubulointerstitial IP-10 expression decreased when changed from proliferative or mixed nephritis to membranous nephropathy (p < 0.0001). Histological activity index correlated significantly with the glomerular expression of Fn14 (r = 0.421, p < 0.0001) and tubulointerstitial expression of TWEAK (r = 0.413, p < 0.0001) and IP-10 (r = 0.472, p < 0.0001).

Conclusion.

Glomerular Fn14 and tubulointerstitial TWEAK and IP-10 expression appeared to have consistent changes in relation to the histological class of LN and correlated with the histological activity index. Our findings suggest a specific role of these genes in the pathogenesis of LN.

Urinary MCP-1 as diagnostic and prognostic marker in patients with lupus nephritis flare

AIM OF THE STUDY

This study aimed to assess correlation of urinary monocytic chemoattractant protein-1 (UMCP-1) with severity of lupus nephritis and its role as predictor of outcome.

METHOD

Twenty patients with lupus nephritis flare were included in the study. Ten patients in each group of stable systemic lupus erythematosus and non-renal flare were taken as controls. Biopsy was done to define lupus nephritis stage. UMCP-1 levels were measured in all patients at the time of entry and at four and eight weeks of follow-up.

RESULTS

Mild, moderate and severe lupus nephritis flare was noted in one, five and 15 patients, respectively. UMCP-1 levels were high in patients with severe lupus nephritis flare (2.74 ± 0.95 ng/mg creatinine) as compared to patients with moderate (1.43 ± 0.46 ng/mg creatinine) and mild lupus nephritis flare (0.76 ± 0.57 ng/mg creatinine) (P = 0.0093). Baseline mean UMCP-1 levels in lupus nephritis flare, non-renal flare and stable SLE patients were 2.32 ± 1.06, 0.171 ± 0.03 and 0.213 ± 0.026 ng/mg creatinine, respectively. The difference among the three groups was very significant (P < 0.001). Also, mean UMCP-1 levels correlated significantly with severity of lupus nephritis class (P = 0.0358). During follow-up, 15 patients achieved complete or partial remission, and in these patients mean UMCP-1 levels had significant decline at eight weeks (P < 0.0001). However, mean UMCP-1 levels in the remaining five non-responders did not show significant changes at four and eight weeks (P = 0.4858).

CONCLUSION

Mean UMCP-1 levels were significantly higher in the lupus nephritis flare group as compared to non-renal flare and stable patients. Baseline mean UMCP-1 levels significantly correlated with both lupus nephritis class and severity of lupus nephritis flare, hence UMCP-1 could be used as a non-invasive marker for the judgement of lupus flare and lupus nephritis class.

Urinary neutrophil gelatinase-associated lipocalin is a potential biomarker for renal damage in patients with systemic lupus erythematosus

Neutrophil gelatinase-associated lipocalin (NGAL) has been demonstrated to be a novel biomarker in acute and chronic kidney disease. We hypothesized that 24-hour urinary NGAL excretion may be a predictor for renal damage in patients with systemic lupus erythematosus (SLE). Thirty-four SLE patients with renal involvement (SLE-renal group), 8 SLE patients without renal involvement (SLE-nonrenal group), 14 patients with non-SLE autoimmune diseases (disease control or DC group), and 12 healthy volunteers (normal control or NC group) were compared for 24-hour urinary excretion of NGAL and different cytokines. We found that the 24-hour urinary NGAL excretion in the SLE-renal group was higher than that in the SLE-non-renal, DC, and NC groups. However, the excretion of interleukin-10, transforming growth factor-β1, and tumor necrosis factor-α was not different between the SLE-renal and SLE-non-renal groups. Furthermore, NGAL excretion in the SLE-renal group was correlated with serum creatinine levels and creatinine clearance, but not with the SLE Disease Activity Index score. Multivariate logistic regression analysis and receiver operating characteristic curve analysis revealed that 24-hour urinary NGAL excretion is a potential biomarker for renal damage in SLE patients, with higher sensitivity and specificity than anti-dsDNA antibody titers.

Monitoring of urinary messenger RNA levels for the prediction of flare in systemic lupus erythematosus

BACKGROUND

Systemic lupus erythematosus (SLE) is characterized by disease flares and remission. We hypothesize that in clinically quiescent SLE patients, the mRNA level of target genes in the urinary sediment is an early indicator of disease flare.

METHODS

From a cohort of 134 adult SLE patients prospectively followed for 56 weeks, we identified 19 patients with a single disease flare. The mRNA level of eight pre-defined target genes in their urinary sediment before disease flare was compared to 19 matched controls with no disease flare during the same period.

RESULTS

Urinary mRNA level remained static in the control group during the study period. Before disease flare, there was a significant increase in the mRNA level of monocyte chemotactic protein (MCP)-1 and forkhead box P3 (FOXP3), and decrease in interleukin (IL)-17 and GATA-3, in the urinary sediment. The mRNA level of FOXP3 in urinary sediment increases 8 weeks prior to a flare, which precedes the corresponding change in serum complement and anti-DNA antibody titer, while that of MCP-1, IL-17, and GATA3 began to change 4 weeks prior to a flare. The same pattern of change in urinary mRNA level was observed in patients with mild-to-moderate or severe flare, and those with renal or non-renal flare. The SLE Disease Activity Index (SLEDAI) score at the time of flare significantly correlated with the change in urinary level of IL-17 (r=-0.462, p=0.046) and GATA-3 (r=-0.455, p=0.05), but not MCP-1 or FOXP3, prior to the flare.

CONCLUSION

Monitoring of MCP-1, IL-17, GATA-3 and FOXP3 mRNA level in urinary sediment may provide an early clue for detecting disease flare in SLE patients.

Expression of miR-146a and miR-155 in the urinary sediment of systemic lupus erythematosus

We studied the levels of miR-146a and miR-155 in the urine sediment of SLE patients. The levels of miR-146a and miR-155 in the urine sediment of 40 SLE patients who were receiving calcitriol treatment and 13 healthy controls were determined with real-time quantitative polymerase chain reaction. The levels of urinary miR-146a and miR-155 in patients with SLE were significantly higher than that in healthy controls. Calcitriol treatment reduced the levels of urinary miR-155 in patients with SLE. The level of urinary miR-146a significantly correlated with estimated glomerular filtration rate (r = 0.242, P = 0.008). The level of urinary miR-155 significantly correlated with proteinuria (r = 0.407, P < 0.001) and systemic lupus erythematosus disease activity index (r = 0.278, P = 0.002). The level of urinary miR-146a reversely correlated with the urinary expression of TNF-α (r = -0.247, P = 0.012). Our results suggested that miR-146a and miR-155 might play important roles in the pathophysiology of SLE and the levels of urinary miR-146a and miR-155 could be used as potential markers for diagnosis, disease activity, and therapeutic response.

Gene expression of TWEAK/Fn14 and IP-10/CXCR3 in glomerulus and tubulointerstitium of patients with lupus nephritis

AIM

The role of the tumour necrosis factor-like weak inducer of apoptosis (TWEAK)/Fn14 and interferon-inducible protein (IP-10)/CXCR3 axis in the pathogenesis of lupus nephritis were studied.

METHODS

The mRNA expression of TWEAK, Fn14, IP-10 and CXCR3 were quantified in the glomerulus and tubulointerstitium of 42 patients with lupus nephritis (LN group) and 10 healthy controls.

RESULTS

As compared to controls, LN patients had higher glomerular expression of TWEAK and Fn14, but glomerular CXCR3 expression was lower in the LN group. Similarly, the LN group had higher tubulointerstitial expression of TWEAK and Fn14, but lower tubulointerstitial expression of CXCR3, than controls. Glomerular TWEAK expression of class V nephritis was significantly higher than class IV nephritis. Glomerular expression of CXCR3 significantly correlated with proteinuria (r = -0.532; P = 0.019), whereas tubulointerstitial CXCR3 significantly correlated with serum creatinine (r = -0.447; P = 0.029).

CONCLUSION

In patients with lupus nephritis, there is an increase in intra-renal expression of TWEAK and Fn14, and a decrease in CXCR3 expression. Intra-renal expression of CXCR3 correlates with proteinuria and renal function. Our findings suggest that the TWEAK/Fn14 and IP-10/CXCR3 axis may contribute to the pathogenesis of lupus nephritis.

Serum and urinary free microRNA level in patients with systemic lupus erythematosus

MicroRNAs circulating in body fluid have been suggested as biomarkers of various diseases. We studied the serum and urinary level of several miRNA species (miR-200 family, miR-205 and miR-192) in patients with systemic lupus erythematosus (SLE). We studied 40 SLE patients. Serum and urinary miRNA levels were determined and compared with that of healthy controls. The serum levels of miR-200a, miR-200b, miR-200c, miR-429, miR-205 and miR-192, and urinary miR-200a, miR-200c, miR-141, miR-429 and miR-192 of SLE patients were lower than those of controls. Glomerular filtration rate (GFR) correlated with serum miR-200b ( r = 0.411, p = 0.008), miR-200c ( r = 0.343, p = 0.030), miR-429 ( r = 0.347, p = 0.028), miR-205 ( r = 0.429, p = 0.006) and miR-192 ( r = 0.479, p = 0.002); proteinuria inversely correlated with serum miR-200a ( r = −0.375, p = 0.017) and miR-200c ( r = −0.347, p = 0.029). SLE disease activity index (SLEDAI) inversely correlated with serum miR-200a ( r = −0.376, p = 0.017). Serum miR-200b ( r = 0.455, p = 0.003) and miR-192 ( r = 0.589, p < 0.001) correlated with platelet count, while serum miR-205 correlated with red cell count ( r = 0.432, p = 0.005) and hematocrit ( r = 0.370, p = 0.019). These pilot results suggested that miRNA may take part in the pathogenesis of SLE. Further studies are needed to validate the role of serum miRNA as a biomarker of SLE.

Gene expression using the PALM system

The PALM Robot MicroBeam laser microdissection system can isolate specified cells from complex tissues section, in a rapid and precise manner. Combined with other methods, PALM may be used for gene expression elucidating the role of specialized cell type in physiological and pathological activity. This chapter describes the application of the PALM MicroBeam system to isolate RNA from cells in a complex tissue for subsequent gene expression analysis. Protocols show the steps from preparation of tissue samples to the final quantitative results. The process is articulated in several steps, each of which requires optimal choices in order to obtain reliable data from a limited number of cells (500-10,000 cells). Furthermore, the notes regarding tissue preparation, microdissection of the interested cells, are also emphasized.

Biomarkers in lupus nephritis

Biomarkers have the potential to be useful tools for noninvasively evaluating and managing patients with lupus nephritis. Many candidate biomarkers have been identified, but they require validation in larger cohorts. It is likely that combinations or biomarker profiles, rather than individual markers, will emerge to help better predict the severity of inflammation, the extent of fibrosis, degree of drug responsiveness, and other variables. This approach has the potential to reduce the use of the renal biopsy, improve therapeutic efficacy, and limit toxicity. We predict algorithms based on genotype and biomarkers combined with clinical presentation will emerge to help guide physicians in management. Assays that show the most potential include serum erythrocyte bound complement C4d, interleukin 17, interleukin 23, interferon score/chemokine score ratio, and anti-C1q antibodies. Such urinary biomarkers as fractional excretion of endothelial-1, monocyte chemoattractant protein-1, vascular cell adhesion molecule-1, and TWEAK (tumor necrosis factor-like weak inducer of apoptosis) may also be useful but require validations.

Biomarkers for lupus nephritis: a critical appraisal

Kidney disease is one of the most serious manifestations of systemic lupus erythematosus (SLE). Despite the improvement in the medical care of SLE in the past two decades, the prognosis of lupus nephritis remains unsatisfactory. Besides exploring more effective but less toxic treatment modalities that will further improve the remission rate, early detection and treatment of renal activity may spare patients from intensive immunosuppressive therapies and reduce renal damage. Conventional clinical parameters such as creatinine clearance, proteinuria, urine sediments, anti-dsDNA, and complement levels are not sensitive or specific enough for detecting ongoing disease activity in the lupus kidneys and early relapse of nephritis. Thus, novel biomarkers are necessary to enhance the diagnostic accuracy and sensitivity of lupus renal disease, prognostic stratification, monitoring of treatment response, and detection of early renal flares. This paper reviews promising biomarkers that have recently been evaluated in longitudinal studies of lupus nephritis.

Olf1/EBF associated zinc finger protein interfered with antinuclear antibody production in patients with systemic lupus erythematosus

Introduction

The aim of the study was to determine whether Olf1/EBF associated zinc finger protein (OAZ), a transcription factor encoded by a positional systemic lupus erythematosus (SLE) candidate gene, plays a functional role in the pathogenesis in SLE.

Methods

Gene expression levels in peripheral blood cells (PBLs) measured using quantitative real-time polymerase chain reaction (qPCR) were assessed for association with disease activity and the presence of specific autoantibodies. Peripheral blood mononuclear cells (PBMCs) were incubated with specific siRNAs for three days, then cells were harvested for measuring mRNA levels using qPCR, and supernatants for levels of total immunoglobulin (Ig)G and IgM as well as secreted cytokines, chemokine and antinuclear antibodies (ANA) using ELISA. Indirect immunofluorescence was also applied for ANA detection.

Results

OAZ gene expressions in PBLs from 40 ANA-positive SLE patients were significantly increased than those from 30 normal controls (P < 0.0001) and 18 patients with rheumatoid arthritis (P < 0.01). In SLE patients, OAZ transcripts were positively correlated with SLE disease activity index (SLEDAI) score (r = 0.72, P < 0.0001) and higher in those positive for anti-dsDNA or anti-Sm antibodies (both P < 0.05). Co-culturing with OAZ siRNAs reduced mRNA levels of OAZ by 74.6 ± 6.4% as compared to those co-cultured with non-targeting siRNA and OAZ silencing resulted in reduced total IgG, ANA, interferon (IFN)-γ, interleukin (IL)-10, IL-12 and IL-21, but elevated CCL2 levels in culture supernatants (P < 0.05). The declined ANA levels correlated with inhibited OAZ expression (r = 0.88, P = 0.05), reduced IL-21 levels (r = 0.99, P < 0.01), and elevated chemokine (C-C motif) ligand 2 levels (r = -0.98, P < 0.01). Expressions of ID1-3 were significantly down-regulated by 68.7%, 70.2% and 67.7% respectively after OAZ silence, while ID3 was also highly expressed in SLE PBLs (P < 0.0001) and associated with disease activity (r = 0.76, P < 0.0001) as well as anti-dsDNA or anti-Sm antibodies (both P < 0.05).

Conclusions

Elevated expression of OAZ transcripts in SLE PBLs were strongly correlated with disease activity. Suppression of OAZ expression inhibited downstream ID levels, and secretion of ANA and IL-21, implicating a role of OAZ pathway in the pathogenesis of SLE.

Urine proteome scans uncover total urinary protease, prostaglandin D synthase, serum amyloid P, and superoxide dismutase as potential markers of lupus nephritis

To identify potential biomarkers in immune-mediated nephritis, urine from mice subjected to an augmented passive model of anti-glomerular basement membrane (GBM)-induced experimental nephritis was resolved using two-dimensional gels. The urinary proteome in these diseased mice was comprised of at least 71 different proteins. Using orthogonal assays, several of these molecules, including serum amyloid P (SAP), PG D synthase, superoxide dismutase, renin, and total protease were validated to be elevated in the urine and kidneys of mice during anti-GBM disease, as well as in mice with spontaneously arising lupus nephritis. Among these, urinary protease was the only marker that appeared to be exclusively renal in origin, whereas the others were partly serum-derived. Longitudinal studies in murine lupus demonstrated that total urinary protease had better predictive value for histologically active nephritis (r = 0.78) compared with proteinuria (r = -0.04), azotemia (r = 0.28), or the other markers examined, whereas urine SAP emerged as the single most predictive marker of histological glomerulonephritis. Collectively, these studies uncover total urinary protease, PG D synthase, SAP, and superoxide dismutase as novel biomarkers of anti-GBM disease and lupus nephritis, with stronger correlation to renal disease compared with currently employed biomarkers. These findings could have important diagnostic and prognostic ramifications in the management of these renal diatheses.

Biomarkers for lupus nephritis: the quest continues

Current treatment of severe lupus nephritis is unsatisfactory in terms of both outcome and toxicity. To improve the efficacy and decrease the adverse effects of immunosuppression, it would be ideal to be able to predict the course and pathology of lupus nephritis and adjust therapy appropriately. This will require biomarkers that reflect disease activity. Recently, significant effort has been put into identifying biomarkers that can anticipate impending lupus renal flare, forecast development of chronic kidney disease, or reflect kidney histology at the time of flare. Although these biomarkers are potentially useful, to date none has been clinically validated in a large, prospective cohort of patients with SLE. This article reviews the current status of lupus nephritis biomarker investigation and articulates a perspective of how future efforts should be focused.

Urinary FOXP3 mRNA in patients with lupus nephritis--relation with disease activity and treatment response

OBJECTIVE

Regulatory T lymphocytes (Tregs) probably play an important role in the pathogenesis of SLE.

METHODS

We quantified messenger RNA (mRNA) expression of FOXP3, a critical regulator for the development and function of Tregs, in the urinary sediment of 25 subjects with active lupus nephritis (LN), 17 with inactive lupus and 7 healthy subjects.

RESULTS

We found that the expression level of FOXP3 was significantly higher in urine from patients with active LN than from subjects with inactive lupus and healthy controls (24.5 +/- 45.8 vs 0.8 +/- 1.0 vs 0.6 +/- 0.8 copy; P < 0.001). In the active group, urinary FOXP3 mRNA expression level was higher in patients with proliferative LN than non-proliferative nephritis (34.6 +/- 56.3 vs 2.7 +/- 2.1 copy; P = 0.019). Urinary FOXP3 mRNA level significantly correlated with SLEDAI (r = 0.668; P < 0.001) and proteinuria (r = 0.414; P = 0.006). In the active group, urinary FOXP3 mRNA level also significantly correlated with histological activity index (r = 0.541; P = 0.009) and marginally with intra-renal FOXP3 mRNA level (r = 0.360; P = 0.08). Urinary FOXP3 mRNA in patients with no response to therapy was higher than those with partial response or complete response (57.6 +/- 69.8 vs 2.4 +/- 1.9 copies; P = 0.02).

CONCLUSION

We concluded that urinary FOXP3 mRNA is markedly up-regulated in patients with active LN, and the level of expression is closely correlated with the clinical and histological disease activity. A high urinary FOXP3 mRNA in LN predicts a poor therapeutic response. Measurement of FOXP3 mRNA in urine sediment may be a non-invasive biomarker for assessing the severity and risk stratification in LN.

Glomerular type 1 angiotensin receptors augment kidney injury and inflammation in murine autoimmune nephritis

Studies in humans and animal models indicate a key contribution of angiotensin II to the pathogenesis of glomerular diseases. To examine the role of type 1 angiotensin (AT1) receptors in glomerular inflammation associated with autoimmune disease, we generated MRL-Faslpr/lpr (lpr) mice lacking the major murine type 1 angiotensin receptor (AT1A); lpr mice develop a generalized autoimmune disease with glomerulonephritis that resembles SLE. Surprisingly, AT1A deficiency was not protective against disease but instead substantially accelerated mortality, proteinuria, and kidney pathology. Increased disease severity was not a direct effect of immune cells, since transplantation of AT1A-deficient bone marrow did not affect survival. Moreover, autoimmune injury in extrarenal tissues, including skin, heart, and joints, was unaffected by AT1A deficiency. In murine systems, there is a second type 1 angiotensin receptor isoform, AT1B, and its expression is especially prominent in the renal glomerulus within podocytes. Further, expression of renin was enhanced in kidneys of AT1A-deficient lpr mice, and they showed evidence of exaggerated AT1B receptor activation, including substantially increased podocyte injury and expression of inflammatory mediators. Administration of losartan, which blocks all type 1 angiotensin receptors, reduced markers of kidney disease, including proteinuria, glomerular pathology, and cytokine mRNA expression. Since AT1A-deficient lpr mice had low blood pressure, these findings suggest that activation of type 1 angiotensin receptors in the glomerulus is sufficient to accelerate renal injury and inflammation in the absence of hypertension.

Mesangial cells of lupus-prone mice are sensitive to chemokine production

Infectious antigens may be triggers for the exacerbation of systemic lupus erythematosus. The underlying mechanism causing acceleration and exacerbation of lupus nephritis (LN) is largely unknown. Bacterial lipopolysaccharide (LPS) is capable of inducing an accelerated model of LN in NZB/W mice, featuring diffuse proliferation of glomerular resident cells. We hypothesized that mesangial cells (MCs) from LN subjects are more responsive to LPS than normal subjects. Cultured primary NZB/W and DBA/W (nonautoimmune disease-prone strain with MHC class II molecules identical to those of NZB/W) MCs were used. Monocyte chemoattractant protein-1 (MCP-1) and osteopontin (OPN) expressions either in the baseline (normal culture) condition or in the presence of LPS were evaluated by real-time PCR, ELISA, or western blot analysis. NF-κB was detected by ELISA, electrophoresis mobility-shift assay, and immunofluorescence. First, either in the baseline condition or in the presence of LPS, NZB/W MCs produced significantly higher levels of MCP-1 and OPN than the DBA/W MC controls. Second, NZB/W MCs expressed significantly higher levels of Toll-like receptor 4, myeloid differentiation factor 88, and NF-κB than the DBA/W MC controls, both receiving exactly the same LPS treatment. In conclusion, NZB/W MCs are significantly more sensitive than their normal control DBA/W MCs in producing both MCP-1 and OPN. With LPS treatment, the significantly elevated levels of both chemokines produced by NZB/W MCs are more likely due to a significantly greater activation of the Toll-like receptor 4-myeloid differentiation factor 88-associated NF-κB pathway. The observed abnormal molecular events provide an intrarenal pathogenic pathway involved in an accelerated type of LN, which is potentially infection triggered.

Quantification of gene expression in urinary sediment for the study of renal diseases

Urinalysis has been used extensively in clinical practice to aid in the diagnosis of various renal diseases. With the advances in technology of molecular biology, gene expression and proteomic studies are now possible for urinary sediment. In this review article, we focus on the quantification of messenger RNA expression in urinary sediment by reverse-transcription and real-time quantitative polymerase chain reaction. Recently, this technique has been explored for three potential applications: (i) distinguishing the different causes of kidney disease; (ii) assessment of kidney disease activity, progression and response to therapy; and (iii) as a tool to study the pathogenesis. Although the method is simple and non-invasive, it requires further research to define the role in routine clinical practice. At this moment, the technique should only be considered experimental albeit promising.

Urinary lipocalin-2 is associated with renal disease activity in human lupus nephritis

OBJECTIVE

Pathogenic monoclonal anti-double-stranded DNA (anti-dsDNA) antibodies up-regulate the expression of lipocalin-2 in glomerular mesangial cells. This study was undertaken to investigate whether polyclonal anti-dsDNA antibodies promote the local secretion of lipocalin-2 in the kidneys of patients with systemic lupus erythematosus (SLE), and whether urinary lipocalin-2 represents a marker of kidney involvement in SLE.

METHODS

Hispanic, African American, and white patients with SLE and normal healthy control subjects from affiliated hospitals of the Albert Einstein College of Medicine were recruited for this cross-sectional study. Patients were classified based on the presence of active renal disease according to the SLE Disease Activity Index (SLEDAI). Correlations of clinical and laboratory data with urinary and serum levels of lipocalin-2 were assessed.

RESULTS

Among SLE patients, urinary lipocalin-2 levels were significantly higher in those with lupus nephritis (LN) (median 17.1 ng/mg creatinine, interquartile range [IQR] 10.3-45.4; n = 32) than in those without LN (median 11.2 ng/mg creatinine, IQR 3.1-20.3; n = 38) (P = 0.023). Compared with the values in normal controls (median 4 ng/ml, IQR 0-11.1; n = 14), urinary levels of lipocalin-2 in SLE patients were significantly higher (non-normalized median 19.3 ng/ml, IQR 8-34.2) (P = 0.004). The presence of lipocalin-2 in the urine of patients with LN correlated significantly with the renal SLEDAI score (r = 0.452, P = 0.009), but not with extrarenal disease activity.

CONCLUSION

The high prevalence of LN in SLE patients and the prognostic significance of kidney disease support the need for identifying early biomarkers to assess the risk of nephritis development and for following up patients with established disease. These findings indicate that urinary lipocalin-2 is a potential marker of the presence and severity of renal involvement in adult patients with SLE.

Therapeutic potential of TGF-beta inhibition in chronic renal failure

Chronic kidney diseases are emerging as a worldwide public health problem. The progression of kidney diseases closely correlates with the accumulation of extracellular matrix leading to glomerulosclerosis and tubulointerstitial injury. Transforming growth factor (TGF)-beta has been identified as a key mediator of kidney matrix accumulation. Overexpression of TGF-beta isoforms and their receptors was observed in a variety of renal diseases in both animals and humans. Given its crucial role in fibrotic kidney disease, TGF-beta has been recently considered as a possible target in the management of chronic renal diseases. This review discusses the role of TGF-beta in renal fibrosis and provides an overview of the strategies that, when interfering with TGF-beta expression and signalling, could be employed as new renoprotective treatments.

Intrarenal cytokine gene expression in lupus nephritis

BACKGROUND

Lupus nephritis is characterised by intrarenal inflammation and lymphocyte activation.

AIM

To examine the profile of cytokine gene expression in glomerulus and tubulointerstitium in patients with lupus nephritis.

METHODS

36 consecutive patients with systemic lupus erythematosus having active renal disease were recruited, and they were required to undergo kidney biopsy. Glomerular and tubulointestitial cytokine expression of interleukin (IL)2, 4, 10, 12, 18, interferon gamma (IFN)gamma, T-bet (the Th1 transcription factor), GATA-3 (the Th2 transcription factor), transforming growth factor beta and monocyte chemoattractant protein (MCP)1 were studied by laser microdissection of the renal biopsy specimen, followed by real-time quantitative PCR.

RESULTS

There were 13 patients with World Health Organization class III nephritis, 14 patients with class IV nephritis and 9 patients with class V nephritis. There was a significant correlation between serum C3, C4 and anti-double strand DNA antibody level with glomerular expression of T-bet, IFNgamma and IL2. There was a significant correlation between histological activity index and glomerular expression of IL12, IL18, IL10 and MCP1. In addition, the degree of glomerular leucocyte infiltration significantly correlated with glomerular expression of IFNgamma, IL10, IL12 and IL18. By contrast, histological chronicity index correlated with the tubulointerstitial expression of IL2, MCP1 and GATA-3.

CONCLUSIONS

Intraglomerular expression of certain target genes correlate with the severity of systemic as well as histological activity, whereas the tubulointerstitial expression of other target genes correlate with the degree of chronic kidney scarring. This result may shed light on the immunopathogenesis of lupus nephritis.

Urinary TWEAK and the activity of lupus nephritis

The TNF superfamily cytokine TWEAK induces mesangial cells, podocytes, and endothelial cells to secrete pro-inflammatory chemokines including MCP-1, IP-10 and RANTES, which are crucial in the pathogenesis of lupus nephritis (LN). As TWEAK regulates the secretion of these inflammatory mediators, we studied whether urinary TWEAK (uTWEAK) levels might be predictive and/or diagnostic in LN. In a cross-sectional study of a large, multi-center cohort of systemic lupus erythematosus (SLE) patients, uTWEAK levels were higher in patients with active as compared to never or non-active nephritis (median (IQR): 16.3 (9.9-23.0) versus 5.5 (2.3-16.8) pg/mg creatinine, p=0.001), and levels of uTWEAK correlated with the renal SLE disease activity index (rSLEDAI) score (r=0.405, p<0.001). uTWEAK levels were higher in patients undergoing a flare as compared to patients with chronic stable disease (11.1 (8.1-18.2) and 5.2 (2.3-15.3) pg/mg creatinine, respectively; p=0.036). Moreover, uTWEAK levels were significantly higher in patients undergoing a renal flare, as opposed to a non-renal flare (12.4 (9.1-18.2) and 5.2 (3.0-11.9) pg/mg creatinine, respectively; p=0.029). An accurate, non-invasive method to repeatedly assess kidney disease in lupus would be very helpful in managing these often challenging patients. Our study indicates that urinary TWEAK levels may be useful as a novel biomarker in LN.

Chemokines and Chemokine Receptors as Therapeutic Targets in Lupus Nephritis

Recruitment of leukocytes is a characteristic feature of tissue injury in systemic lupus erythematosus, including lupus nephritis. Locally secreted chemokines and their receptors are important mediators of leukocyte recruitment to the specific sites of immune complex injury, and contribute to renal inflammatory disease in the initiation and progression phase. Therefore, chemokines and chemokine receptors represent potential therapeutic targets in lupus nephritis. In this review we summarize available experimental and human data supporting their functional role in lupus nephritis. Moreover, interventional studies with chemokine and chemokine receptor antagonists that show the therapeutic potential of chemokine antagonists in experimental models of lupus nephritis and potentially in human renal disease are discussed.

Pathogenesis and treatment of systemic lupus erythematosus nephritis

PURPOSE OF REVIEW

Glomerulonephritis is a challenging complication of systemic lupus erythematosus that still results in kidney loss in up to 30% of patients. In this review we highlight the development of integrated efforts to link pathogenesis with disease definition and new therapeutics.

RECENT FINDINGS

Immune complex deposition in the kidney initiates an inflammatory cascade that causes glomerular disease but there are many modulating factors including genetic predisposition, products of the innate immune system, cytokines, complement and activated cells (both renal and immune). Animal models can help dissect potential disease mechanisms but the study of multiple models will be required since there are multiple subsets of human disease. Recent therapeutic studies in humans address the distinction between therapies for remission induction and remission maintenance. Multiple studies confirm the therapeutic equivalence of mycophenolate mofetil and cyclophosphamide in induction of remission but results are still far from ideal. The next few years should see the testing of new biologic reagents in humans. Another area of interest is the search for noninvasive measures of disease and disease response.

SUMMARY

Although there has been remarkable progress in our understanding of the immunology and phenotype of lupus nephritis current therapies have insufficient efficacy. As new therapies emerge, improved clinical design coupled with mechanistic studies will be needed to identify agents that may be effective only in some patient subpopulations.

Messenger RNA expression of RANTES in the urinary sediment of patients with lupus nephritis

BACKGROUND

Lupus nephritis is characterized by intra-renal inflammation. Patients with systemic lupus erythematosus (SLE) showed abnormal T-cell expression of RANTES (regulated upon activation, normal T cell expressed) and its level in their serum. The authors studied the mRNA expression of RANTES in the urinary sediment of lupus patients.

METHODS

The authors studied 88 lupus patients, who were classified into active, remission and non-renal SLE groups according to the disease activity, 29 non-SLE and 10 healthy controls. Lupus activity was assessed by the Systemic Lupus Erythematosus Disease Activity Index (SLEDAI). Urinary mRNA expression of RANTES was studied by real-time quantitative polymerase chain reaction.

RESULTS

The expression of RANTES in urinary sediment was significantly elevated in active group (P < 0.001). Expression level of RANTES correlated with the SLEDAI score (r = 0.57; P < 0.001) and renal score in SLEDAI (r = 0.60; P < 0.001). In addition, urinary expression of RANTES had significant correlation with degree of proteinuria, serum creatinine, albumin and estimated glomerular filtration rate.

CONCLUSION

The authors conclude that the mRNA expression of RANTES was elevated in the urinary sediment of patients with active lupus nephritis. Measurement of urinary mRNA expression may be a novel non-invasive method for the assessment of lupus disease activity and the severity of renal involvement.

Association of serum MIP-1alpha, MIP-1beta, and RANTES with clinical manifestations, disease activity, and damage accrual in systemic lupus erythematosus

The aim of this study was to determine if macrophage inflammatory protein (MIP) 1alpha, MIP-1beta, and RANTES (regulated upon activation normally T-cell expressed and secreted) serum concentrations are associated with clinical manifestations, disease activity, and damage accrual in patients with systemic lupus erythematosus (SLE). A cross-sectional study was performed in 62 SLE patients (per American College of Rheumatology criteria) participating in a longitudinal study and 20 healthy subjects. MIP-1alpha, MIP-1beta, and RANTES serum concentrations were determined by enzyme-linked immunosorbent assay. Demographic parameters, clinical manifestations, serologic features, pharmacologic treatments, disease activity, and damage accrual were determined at study visit. Disease activity was assessed with the Systemic Lupus Erythematosus Activity Measure (SLAM), and disease damage was assessed with Systemic Lupus International Collaborating Clinic Damage Index (SDI). The relation between the variables was studied with the Student t test and the Pearson r correlation test. SLE patients were more likely to have higher concentrations of MIP-1beta and RANTES than healthy individuals. In addition, they had a trend to have higher concentrations of MIP-1alpha. Patients with discoid lupus were more likely to have higher levels of MIP-1alpha. Elevation of MIP-1beta correlated with higher SDI score. No association was found between serum chemokines levels and disease activity. In conclusion, SLE patients have higher serum levels of MIP-1beta and RANTES than healthy individuals. MIP-1alpha is associated with discoid lupus, and MIP-1beta correlates with damage accrual in SLE. This study suggests that chemokines may have a role in the pathogenesis of SLE.

Molecular approaches to chronic kidney disease

PURPOSE OF REVIEW

The progression of chronic kidney disease to terminal renal failure remains a major challenge in nephrology. Definition of the dynamic differences in gene regulation, protein interaction and protein function in this process might allow the development of rationally designed management strategies for the individual patient. Current approaches to identifying the molecular markers required to implement this 'personalized medicine' concept in progressive renal failure will be presented in this review.

RECENT FINDINGS

In small populations, molecular fingerprints derived from renal biopsies have allowed the definition of distinct patient subgroups. These parameters could be shown to correlate with the response to available therapies and, in chronic transplant failure, with the therapeutic toxicity of cyclosporine. Urine analysis for mRNA and protein markers is rapidly evolving as a non-invasive approach for molecular patient monitoring. As only a small fraction of these fingerprints have been evaluated in independent populations, studies to test marker sets in diverse cohorts for their clinical applicability are warranted.

SUMMARY

The genome-wide tools discussed in this review might define the molecular mechanism active in each single patient with progressive kidney disease. Reflecting the individuality of the disease process could result in a tailored therapy for the unique human being, contrasting with the 'one-size-fits-all' therapies currently employed in nephrology.

mRNA expression of target genes in the urinary sediment as a noninvasive prognostic indicator of CKD

BACKGROUND

Study of messenger RNA (mRNA) expression of target genes in urinary sediment was suggested as a noninvasive marker of renal damage in patients with chronic kidney diseases (CKDs). We studied the relationship between urinary mRNA expression of target genes and risk for renal function deterioration in patients with CKD.

METHODS

We studied 131 patients with CKD with kidney biopsy. mRNA expression of 11 target genes in urinary sediment was measured by means of quantitative polymerase chain reaction. Patients then were followed up for 27.4 +/- 10.1 months. The primary end point is doubling of serum creatinine concentration or end-stage renal disease.

RESULTS

Thirty-six patients (27.5%) reached the primary end point during follow-up. Univariate analysis showed that sex, age, proteinuria, estimated glomerular filtration rate, histological diagnosis, degree of tubulointerstitial scarring, percentage of glomerulosclerosis, and urinary mRNA expression of hepatocyte growth factor (HGF) were predictors of the primary end point. At 24 months, event-free survival rates were 90.9% and 64.3% for patients with low and high urinary HGF expression, respectively (log rank test, P = 0.002). After adjusting for other confounding factors by using a Cox proportional hazard model, urinary HGF expression remained an independent predictor of the primary end point, and a 1-fold increase in expression was associated with a 4.0% (95% confidence interval, 0.5 to 7.5; P = 0.024) increase in risk.

CONCLUSION

In the target genes examined, urinary HGF expression is an independent prognostic indicator of CKD after adjusting for confounding clinical and histological factors. Measurement of urinary HGF mRNA expression may be a useful noninvasive tool for risk stratification of patients with CKD.