B lymphocytes and lupus nephritis: New insights into pathogenesis and targeted therapies

Rituximab alleviates pediatric systemic lupus erythematosus associated refractory immune thrombocytopenia: a case-based review

A complication of pediatric systemic lupus erythematosus (pSLE) is immune thrombocytopenia (ITP). Although corticosteroids and immunoglobulins are frequently used as preliminary treatments, some patients do not respond to them. Rituximab has been reported to be safe and effective in the treatment of pSLE complicated with refractory ITP. Research is currently underway to determine the optimal rituximab dose for these individuals. We report a case of a child with SLE-associated ITP (SLE-ITP) who was successfully treated with rituximab. Rituximab is likely the most viable therapeutic option for refractory SLE-ITP. Furthermore, a comprehensive review of the relevant literature was performed and a concise overview of the pathogenesis and available treatment modalities for pediatric patients diagnosed with SLE and concurrent ITP was provided.

Association between immunoglobulin G N-glycosylation and lupus nephritis in female patients with systemic lupus erythematosus: a case-control study

Background

Lupus nephritis (LN) is a crucial complication of systemic lupus erythematosus (SLE) and has important clinical implications in guiding treatment. N-glycosylation of immunoglobulin G (IgG) plays a key role in the development of SLE by affecting the balance of anti-inflammatory and proinflammatory responses. This study aimed to evaluate the performance of IgG N-glycosylation for diagnosing LN in a sample of female SLE patients.

Methods

This case-control study recruited 188 women with SLE, including 94 patients with LN and 94 age-matched patients without LN. The profiles of plasma IgG N-glycans were detected by hydrophilic interaction chromatography with ultra-performance liquid chromatography (HILIC-UPLC). A multivariate logistic regression model was used to explore the associations between IgG N-glycans and LN. A diagnostic model was developed using the significant glycans as well as demographic factors. The performance of IgG N-glycans in the diagnosis of LN was evaluated by receiver operating characteristic (ROC) curve analysis, and the area under the curve (AUC) and its 95% confidence interval (CI) were calculated.

Results

There were significant differences in 9 initial glycans (GP2, GP4, GP6, GP8, GP10, GP14, GP16, GP18 and GP23) between women with SLE with and without LN (P < 0.05). The levels of sialylated, galactosylated and fucosylated glycans were significantly lower in the LN patients than in the control group, while bisected N-acetylglucosamine (GlcNAc) glycans were increased in LN patients (P < 0.05). GP8, GP10, GP18, and anemia were included in our diagnostic model, which performed well in differentiating female SLE patients with LN from those without LN (AUC = 0.792, 95% CI: 0.727 to 0.858).

Conclusion

Our findings indicate that decreased sialylation, galactosylation, and core fucosylation and increased bisecting GlcNAc might play a role in the development of LN by upregulating the proinflammatory response of IgG. IgG N-glycans can serve as potential biomarkers to differentiate individuals with LN among SLE patients.

Decipher the Immunopathological Mechanisms and Set Up Potential Therapeutic Strategies for Patients with Lupus Nephritis

Lupus nephritis (LN) is one of the most severe complications in patients with systemic lupus erythematosus (SLE). Traditionally, LN is regarded as an immune complex (IC) deposition disease led by dsDNA-anti-dsDNA-complement interactions in the subendothelial and/or subepithelial basement membrane of glomeruli to cause inflammation. The activated complements in the IC act as chemoattractants to chemically attract both innate and adaptive immune cells to the kidney tissues, causing inflammatory reactions. However, recent investigations have unveiled that not only the infiltrating immune-related cells, but resident kidney cells, including glomerular mesangial cells, podocytes, macrophage-like cells, tubular epithelial cells and endothelial cells, may also actively participate in the inflammatory and immunological reactions in the kidney. Furthermore, the adaptive immune cells that are infiltrated are genetically restricted to autoimmune predilection. The autoantibodies commonly found in SLE, including anti-dsDNA, are cross-reacting with not only a broad spectrum of chromatin substances, but also extracellular matrix components, including α-actinin, annexin II, laminin, collagen III and IV, and heparan sulfate proteoglycan. Besides, the glycosylation on the Fab portion of IgG anti-dsDNA antibodies can also affect the pathogenic properties of the autoantibodies in that α-2,6-sialylation alleviates, whereas fucosylation aggravates their nephritogenic activity. Some of the coexisting autoantibodies, including anti-cardiolipin, anti-C1q, anti-ribosomal P autoantibodies, may also enhance the pathogenic role of anti-dsDNA antibodies. In clinical practice, the identification of useful biomarkers for diagnosing, monitoring, and following up on LN is quite important for its treatments. The development of a more specific therapeutic strategy to target the pathogenic factors of LN is also critical. We will discuss these issues in detail in the present article.

Pathogenesis of lupus nephritis: the contribution of immune and kidney resident cells

PURPOSE OF REVIEW

Lupus nephritis is associated with significant mortality and morbidity. We lack effective therapeutics and biomarkers mostly because of our limited understanding of its complex pathogenesis. We aim to present an overview of the recent advances in the field to gain a deeper understanding of the underlying cellular and molecular mechanisms involved in lupus nephritis pathogenesis.

RECENT FINDINGS

Recent studies have identified distinct roles for each resident kidney cell in the pathogenesis of lupus nephritis. Podocytes share many elements of innate and adaptive immune cells and they can present antigens and participate in the formation of crescents in coordination with parietal epithelial cells. Mesangial cells produce pro-inflammatory cytokines and secrete extracellular matrix contributing to glomerular fibrosis. Tubular epithelial cells modulate the milieu of the interstitium to promote T cell infiltration and formation of tertiary lymphoid organs. Modulation of specific genes in kidney resident cells can ward off the effectors of the autoimmune response including autoantibodies, cytokines and immune cells.

SUMMARY

The development of lupus nephritis is multifactorial involving genetic susceptibility, environmental triggers and systemic inflammation. However, the role of resident kidney cells in the development of lupus nephritis is becoming more defined and distinct. More recent studies point to the restoration of kidney resident cell function using cell targeted approaches to prevent and treat lupus nephritis.

Expression of XBP1s in B lymphocytes is critical for pristane-induced lupus nephritis in mice

B lymphocyte hyperactivity plays a pathogenic role in systemic lupus erythematosus (SLE), and spliced X box-binding protein 1 (XBP1s) has been implicated in B cell maturation and differentiation. We hypothesized that blockade of the XBP1s pathway inhibits the B cell hyperactivity underlying SLE and lupus nephritis (LN) development. In the present study, we systematically evaluated the changes in B cell activation induced by the Xbp1 splicing inhibitor STF083010 in a pristane-induced lupus mouse model. The lupus mouse model was successfully established, as indicated by the presence of LN with markedly increased urine protein levels, renal deposition of Ig, and mesangial cell proliferation. In lupus mice, B cell hyperactivity was confirmed by increased CD40 and B cell-activating factor levels. B cell activation and plasma cell overproduction were determined by increases in CD40-positive and CD138-positive cells in the spleens of lupus mice by flow cytometry and further confirmed by CD45R and Ig light chain staining in the splenic tissues of lupus mice. mRNA and protein expression of XBP1s in B cells was assessed by real-time PCR, Western blot analysis, and immunofluorescence analysis and was increased in lupus mice. In addition, almost all changes were reversed by STF083010 treatment. However, the expression of XBP1s in the kidneys did not change when mice were exposed to pristane and STF083010. Taken together, these findings suggest that expression of XBP1s in B cells plays key roles in SLE and LN development. Blockade of the XBP1s pathway may be a potential strategy for SLE and LN treatment.

Immunoglobulin Binding Protein 1 as a Potential Urine Biomarker in Patients with Lupus Nephritis

We evaluated the role of immunoglobulin binding protein 1 (IGBP1), a phosphoprotein associated with the B cell receptor (BCR) complex, as a urine biomarker in lupus nephritis (LN). The IGBP1 concentrations in plasma and urine of patients with LN, systemic lupus erythematosus (SLE) without nephritis and healthy controls were estimated by ELISA. IGBP1 expression in the kidneys of LN patients and transplantation donors was detected by immunohistochemistry. Microarray-based global gene expression profile of HK-2 cells with IGBP1 knock-down and fluorescence-activated cell sorting (FACS) for intracellular IGBP1 expression in human peripheral blood mononuclear cells (PBMCs) was performed. Urine IGBP1 levels were elevated significantly in LN patients, and it correlated with the clinical activity indices (complement 3 (C3) level, anti-dsDNA antibodies titer, SLE Disease Activity Index-2000 (SLEDAI-2K) and histological activity index. IGBP1 expression was increased in LN patients as compared to the donors and was detected mainly in the tubules by histopathology. In microarray analysis, several genes related to SLE pathogenesis (PPME1, ROCK2, VTCN1, IL-17R, NEU1, HLA-DM, and PTX3) responded to siRNA-mediated IGBP1 silencing. In FACS, IGBP1 was expressed mainly in the CD14⁺ cells. The overall expression of IGBP1 in PBMCs was higher in LN patients as compared with that in SLE patients without nephritis. Conclusively, urinary IGBP1 may be a novel biomarker reflecting the clinical and histological activities in LN.

Annexin A2 and FTH1 are potential biomarkers for lupus nephritis

Lupus nephritis (LN) occurs in ~50% of patients with systemic lupus erythematosus and is a major cause of morbidity and mortality of the affected individuals. Therefore, identification of novel and predictive biomarkers for the early diagnosis and progression of LN is required. The present study included 10 patients with LN whose diagnoses were confirmed by renal biopsy and 5 healthy participants as control subjects. Sera were collected both from patients with LN and healthy controls. Subsequently, mesangial cells were treated with these sera for 24 h. Differential proteins between groups were detected by two-dimensional difference gel electrophoresis (2D-DIGE) and matrix-assisted laser desorption/ionization time of flight mass spectrometry analysis. 2D-DIGE maps of cellar proteins were obtained for LN and normal control groups. A total of 45 proteins were characterized, and 2 low-abundance proteins were identified. Compared with the normal human sera group, expression level of Annexin A2 was elevated in patients with LN, while the expression of the ferritin heavy chain (FTH1) decreased in the LN group; the analysis was carried out by DeCyder version 7.0 automatically. The results of the present study suggest that Annexin A2 and FTH1 contributed to the progression of LN and could serve as potential biomarkers for this disease.

Low dose mycophenolate mofetil versus cyclophosphamide in the induction therapy of lupus nephritis in Nepalese population: a randomized control trial

BACKGROUND

The management of proliferative lupus nephritis (LN) comprises timely and coordinated immunosuppressive therapy. This study aimed to evaluate and compare the effectiveness and safety profile of low dose mycophenolate mofetil (MMF) and cyclophosphamide (CYC) in induction therapy of LN in Nepalese population.

METHODS

We conducted a prospective, open-label, randomized trial over a period of one and half years. Forty-nine patients with class III to V lupus nephritis were enrolled, out of which 42 patients (21 in each group) could complete the study. CYC was given intravenously as a monthly pulse and MMF was administered orally in the tablet form in the maximum daily dose of 1.5 g in two divided doses.

RESULTS

The mean age of the patients was 25.43 ± 10.17 years with female to male ratio of 7.3:1. Mean baseline serum creatinine was 1.58 ± 1.38 mg/dL and eGFR was 62.38 ± 26.76 ml/min/1.73m². Mean 24-h urinary protein was 4.35 ± 3.71 g per 1.73 m² body surface area. At 6 months, serum creatinine (mg/dL) decreased from 1.73 to 0.96 in CYC and from 1.24 to 0.91 in the MMF group with improvement in eGFR (ml/min/1.73 m²) from 60.33 to 88.52 in CYC and from 64.42 to 89.09 in MMF group. Twenty-four-hour urinary protein (gm/1.73m²) reduced from 4.47 to 0.94 in CYC and from 4.5 to 0.62 in the MMF group. Primary end point was achieved in higher percentage of patients with MMF than CYC (28.6% vs. 19%) while equal proportion of patients (67% in each group) achieved secondary end point in both groups. Number of non-responders was higher in CYC group than in the MMF group (14.3% vs. 4.8%). There was no difference in the rate of achievement of secondary end point in both CYC and MMF groups (3.16 vs. 3.05 months). The occurrence of adverse events was higher in the CYC than in MMF group (56 vs. 15 events).

CONCLUSION

Present study has concluded that MMF, used in relatively lower dose, is equally effective in inducing remission with reduction of proteinuria and improvement of kidney function with lesser adverse events than CYC in the induction therapy of proliferative lupus nephritis.

TRIAL REGISTRATION

Retrospectively registered to ClinicalTrials.gov PRS. NCT03200002 (Registered date: June 28, 2017).

Outcome of low dose cyclophosphamide for induction phase treatment of lupus nephritis, a single center study

Background

The current standard for induction phase treatment of lupus nephritis is steroid combined with mycophenolate mofetil or pulse intravenous cyclophosphamide (IVC). The lowest dose of IVC recommended for induction therapy is that used in the Euro-Lupus Trial. It is not known whether same cumulative dose of IVC would be effective when given over six months.

Methods

We carried out a prospective, observational study on 41 patients of biopsy-proven lupus nephritis (class III, IV, V or mixed). For induction, patients received six pulses of monthly IVC (500 mg each), along with steroid. Patients were followed up monthly until one month beyond completion of the sixth pulse. The outcomes assessed were complete remission (proteinuria < 200 mg/day or urine albumin nil with serum albumin >35 gm/L, stable estimated glomerular filtration rate (eGFR) if normal at baseline or increase in eGFR by 25 % if abnormal at baseline and normal urinary sediment), response (complete or partial remissions), complications of therapy and death.

Results

Twenty two patients (53.7 %) had class IV nephritis. Eighteen patients (43.9 %) achieved complete remission, 16 (39.0 %) achieved partial remission, yielding an overall response rate of 82.9 %. Nephrotic range proteinuria (UTP ≥ 3 g/day) and severe hypoalbuminemia (serum albumin < 20 g/L) at baseline influenced remission (p <0.05). Infection, seen in 12 patients (29.3 %), was the most common complication. Four deaths (9.6 %) were observed, all due to infection.

Conclusions

For induction phase treatment, Nepalese patients with lupus nephritis responded favorably to steroid and low dose IVC of 3 grams given as six monthly pulses.

Calcineurin inhibitors may be a reasonable alternative to cyclophosphamide in the induction treatment of active lupus nephritis: A systematic review and meta-analysis

Although the accepted standard of care during the induction treatment of active lupus nephritis (LN) has been cyclophosphamide (CYC), recent trials suggest that calcineurin inhibitors (CNIs), which include cyclosporine A (CsA) and tacrolimus (TAC), may be just as, or even more, effective and less toxic than CYC. A systematic review and meta-analysis were performed to evaluate the clinical effects of CNIs on active LN compared with those of CYC. In the present study, clinical trials that compared CNIs with CYC in the induction therapy of active LN were searched in the Cochrane Library, Ovid and PubMed databases. The clinical data on renal remission and side-effects were collected and analyzed. The relative risk (RR) and 95% confidence intervals (CIs) were calculated. As a result, six controlled trials involving 265 patients were included in the meta-analysis, four of which compared TAC (treatment group) with CYC (control group), and the other two compared CsA (treatment group) with CYC (control group). CNIs were superior to CYC for higher complete remission (RR=1.56, 95% CI 1.14-2.15, Z=2.74, P=0.006) and better overall response/total remission (RR=1.23, 95% CI 1.07-1.42, Z=2.87, P=0.004) and had fewer side-effects. Among the CNIs, TAC demonstrated more favorable results than CsA. Therefore, it was concluded that CNIs may be a reasonable alternative to CYC in the induction treatment of active LN. However, large-scale, multicenter, well-designed clinical trials should be adopted to further confirm this conclusion.

The Characteristics and Significance of Locally Infiltrating B Cells in Lupus Nephritis and Their Association with Local BAFF Expression

Introduction. Dysfunction of the B lymphocyte is considered to be involved in the pathogenesis of lupus nephritis (LN). Intrarenal B cells have been found in several forms of inflammatory kidney disease. B-cell activating factor (BAFF) regulates B lymphocyte proliferation and survival, and contributes to human autoimmune disease. Their role in renal inflammation is not well defined. Methods. Clinical parameters and renal biopsies from 62 LN patients were prospectively analyzed. We performed standard immunohistochemistry on serial paraffin tissue sections using monoclonal antibodies to CD20 and BAFF to investigate the characteristics and significance of locally infiltrating B cells and local BAFF expression in patients with LN. Results. Intrarenal B cells and/or BAFF were mainly distributed in the renal interstitium. Compared to the LN-non-B-cell/BAFF expression group, proteinuria (g/24 hour), blood urea nitrogen, serum creatinine levels, LN renal activity, and chronicity indices, were all significantly greater in the LN-B-cell/BAFF expression groups. The expression of BAFF was strongly associated with the quantity of B-cell infiltrate in the interstitium. Conclusion. As BAFF expression was strongly associated with B-cell infiltration, we hypothesize that altered B-cell differentiation and tolerance induced by excess BAFF may be central to the pathogenesis of LN.

Bucillamine inhibits CD40-mediated Akt activation and antibody production in mouse B-cell lymphoma

The improvement of rheumatoid factor titers in patients with rheumatoid arthritis is one of the significant clinical effects of bucillamine (Buc). In this study, we investigated the effects of SA981, an active metabolite of Buc, and methotrexate (MTX) on CD40-mediated antibody production using mouse B-cell lymphoma, BCL1. SA981 significantly attenuated CD40-mediated antibody production in a concentration-dependent manner, but weakly affected cell proliferation. In contrast, MTX did not attenuate CD40-mediated antibody production until it had strongly inhibited cell proliferation at a concentration of 100 nM. CD40 signaling induced protein phosphorylation, including Akt phosphorylation, p38 mitogen-activated protein kinase (p38MAPK), and IκBα. SA981 at a concentration of 30 μM attenuated CD40-mediated Akt phosphorylation, but not p38MAPK or IκBα phosphorylation. MTX at a concentration of 100 nM did not affect CD40-mediated Akt, p38MAPK, or IκBα phosphorylation. Commercially available Akt inhibitor VIII significantly attenuated CD40-mediated IgM production at a concentration of 100 nM without significant inhibition of cell proliferation. These results suggest that SA981 inhibits CD40-mediated antibody production in mouse B-cell lymphoma, at least in part, by attenuation of Akt phosphorylation.

Association of intrarenal B-cell infiltrates with clinical outcome in lupus nephritis: a study of 192 cases

Background. Lupus nephritis (LN) remains a major cause of morbidity and end-stage renal disease. Dysfunction of B lymphocytes is thought to be important in the pathogenesis of SLE/LN. Intrarenal B cells have been found in several forms of inflammatory kidney diseases although their role in LN renal is not well defined. Methods. Intrarenal B cells were analyzed in 192 renal biopsies from patients diagnosed with lupus nephritis. Immunohistochemical staining of serial sections was performed for each LN patient using CD20, CD3, and CD21 antibodies. Results. Intrarenal B cells were more likely to be associated with class IV LN and were mainly distributed in the renal interstitium, with very few in the glomerulus. The systemic lupus erythematosus disease activity index (SLEDAI), blood urea nitrogen, and serum creatinine levels were all significantly greater in the LN-B cell groups (all P < 0.05). LN renal activity and chronicity indices correlated with B-cells infiltrates (all P < 0.0001). Renal biopsies were classified into four distinct categories according to the organizational grade of inflammatory cell infiltrates. Germinal center- (GC-) like structures were not identified in any LN biopsies. Conclusion. It is hypothesized that intrarenal B cells enhance immunological responses and exaggerate the local immune response to persisting autoimmune damage in the tubulointerstitium.

Tacrolimus versus cyclophosphamide as treatment for diffuse proliferative or membranous lupus nephritis: a non-randomized prospective cohort study

Treatment of lupus nephritis (LN) with cyclophosphamide (CYC) is effective but retains a certain severe adverse effect. Tacrolimus (TAC) may be a suitable treatment for LN. Forty patients with diffuse proliferative or membranous LN were recruited for this non-randomized open-label study — 67.5% (27/40) had nephrotic proteinuria (>3.5 g/day) and 50.0% (20/40) had low estimated glomerular filtration rate (eGFR) (<60 mL/min/1.73m2). We compared the efficacy and adverse effects of TAC (0.04–0.08 mg/kg/d)/prednisone for 12 months (TAC group, n = 20) with intravenous CYC (750 mg/m2 per month)/prednisone for six months followed by azathioprine (Aza) (100 mg/day)/prednisone for six months (CYC group, n = 20). The TAC target concentration was 6–8 ng/mL or 4–6 ng/mL, respectively, when induction or maintenance therapy was required and 4.0 ng/mL for patient with renal insufficiency. In the TAC group, mean urinary protein excretion decreased significantly from 5.00 ± 1.91 g/day at baseline to 2.54 ± 1.68 g/day after two weeks of therapy ( P < 0.001), compared with the CYC group (4.9 ± 19.4 g/day), P = 0.001, and 65.0% (13/20) achieved partial remission at one month, compared with the CYC group (0/20), P < 0.001. The incidence of complete remission (CR) was significantly higher in the TAC group than in the CYC group (55.0% vs.15.0% by five months, P = 0.008, and 75.0% vs.40.0% by 12 months, P = 0.025, respectively). The significant improvement in serum anti-dsDNA and systemic lupus erythematosus (SLE) disease activity index (DAI) was in the TAC group relative to the CYC group at 12 months ( P = 0.031, P = 0.003, respectively). The eGFR improved in the TAC group from 59.90 ± 23.64 mL/min/1.73m2 at baseline to 93.75 ± 28.52 mL/min/1.73m2 after 12 months, P = 0.001. In the CYC group, two patients developed end-stage renal disease (ESRD), three patients experienced serious pneumonia, and one patient died. Our preliminary study showed TAC is a safe and effective treatment for LN with severe renal disease, and with less-severe adverse events compared with CYC followed Aza therapy. Further larger sample studies are needed to confirm our conclusion.

Efficacy and safety of rituximab in patients with active proliferative lupus nephritis: the Lupus Nephritis Assessment with Rituximab study

OBJECTIVE

To evaluate the efficacy and safety of rituximab in a randomized, double-blind, placebo-controlled phase III trial in patients with lupus nephritis treated concomitantly with mycophenolate mofetil (MMF) and corticosteroids.

METHODS

Patients (n = 144) with class III or class IV lupus nephritis were randomized 1:1 to receive rituximab (1,000 mg) or placebo on days 1, 15, 168, and 182. The primary end point was renal response status at week 52.

RESULTS

Rituximab depleted peripheral CD19+ B cells in 71 of 72 patients. The overall (complete and partial) renal response rates were 45.8% among the 72 patients receiving placebo and 56.9% among the 72 patients receiving rituximab (P = 0.18); partial responses accounted for most of the difference. The primary end point (superior response rate with rituximab) was not achieved. Eight placebo-treated patients and no rituximab-treated patients required cyclophosphamide rescue therapy through week 52. Statistically significant improvements in serum complement C3, C4, and anti-double-stranded DNA (anti-dsDNA) levels were observed among patients treated with rituximab. In both treatment groups, a reduction in anti-dsDNA levels greater than the median reduction was associated with reduced proteinuria. The rates of serious adverse events, including infections, were similar in both groups. Neutropenia, leukopenia, and hypotension occurred more frequently in the rituximab group.

CONCLUSION

Although rituximab therapy led to more responders and greater reductions in anti-dsDNA and C3/C4 levels, it did not improve clinical outcomes after 1 year of treatment. The combination of rituximab with MMF and corticosteroids did not result in any new or unexpected safety signals.

Elevated production of serum B-cell-attracting chemokine-1 (BCA-1/CXCL13) is correlated with childhood-onset lupus disease activity, severity, and renal involvement

Abstract: Objectives. Systemic lupus erythematosus (SLE) is a prototype of systemic autoimmune disease in which cytokines such as B lymphocyte chemoattractant (BLC) or CXC motif ligand 13 (CXCL13) play an important role as major regulators of B1 and B2 cell trafficking for activation of autoreactive T helper cells. CXCL13 can induce trafficking of the CXCR5+ T lymphocyte subset designated as follicular helper T lymphocytes which are specifically involved in autoantibody production during the development of lupus. Here, we ask whether serum levels of CXCL13 correlate with disease activity and severity and renal involvement in children with SLE. Methods. Serum samples from 40 children with SLE and 32 healthy controls were analyzed by ELISA for the concentrations of CXCL13. Results. Median (interquartile range (IQR) serum CXCL13 concentrations (pg/ml) were increasingly higher across the following groups: healthy controls (71.6 (66.6–81.8), SLE patients with inactive disease (140.8 (99.7–198.8), p = 0.0005 versus controls) and active disease (293.0 (105.5–489.8), p = 0.0001 versus controls) (inactive versus active; p < 0.0001). Concentrations of circulating CXCL13 correlated with SLEDAI ( r = 0.499, p = 0.029) and double-stranded DNA titers ( r = 0.71, p < 0.001). Moreover, median CXCL13 concentrations were higher in patients with renal involvement (270.6 (150.4–430.7) compared with those without renal involvement (120.6 (70.5–208.9). According to WHO pathological classification of lupus nephritis, median CXCL13 concentrations were higher in children with class III, IV and V nephritis compared with those with class I and II nephritis (333.9 (169.4–491.5) versus (180.4 (107.9–209.7). Conclusions. Our data indicate that an increased level of CXCL13 is a feature of SLE that correlates with disease activity and severity. CXCL13 expression in lupus nephritis represents a new pathogenetic mechanism of diagnostic and prognostic significance. The pharmacological regulation of CXCL13 and its receptor, CXCR5, expression may be a useful tool in the therapy of lupus nephritis.

Intrarenal production of B-cell survival factors in human lupus nephritis

The B-cell survival factors APRIL and BLyS are important for B-cell maturation and activation and contribute to human autoimmune diseases. Interference with B-cell function by targeting these molecules is currently being investigated in large clinical trials for systemic lupus erythematosus. The local expression patterns of APRIL and BLyS have not been investigated in detail in kidneys with lupus nephritis. We studied the mRNA expression of APRIL, BLyS, and the corresponding receptors BCMA, TACI, and BAFF-R in microdissected human biopsies with proliferative lupus nephritis (n=25) and compared it with pretransplant biopsies of living donors (n=9). APRIL and BLyS mRNA levels were significantly higher in glomeruli of patients with proliferative lupus nephritis (12- and 30-fold, respectively). Tubulointerstitial expression of APRIL, BLyS, BCMA, and TACI was also significantly elevated. To localize the respective proteins in the kidney, APRIL, BLyS, and BAFF-R were studied by immunohistochemistry in renal biopsies with proliferative (n=21) or membranous (n=8) lupus nephritis. APRIL was prominently expressed in glomeruli with proliferative, but not membranous, lupus nephritis. The staining pattern was consistent with mesangial cells. A prominent accumulation of CD68-positive cells was present in glomeruli in association with APRIL expression. APRIL, BLyS, and BAFF-R were also expressed in interstitial inflammatory cell accumulation. This is the first study, which details local expression of APRIL and BLyS in glomeruli and tubulointerstitium of human proliferative lupus nephritis. This information might help define intrarenal effects of APRIL and BLyS inhibition in human lupus nephritis.

Treatment of proliferative lupus nephritis: a slowly changing landscape

Proliferative lupus nephritis is the most severe form of lupus nephritis. Outcomes of this disease are affected by ethnicity, clinical characteristics, irreversible damage on renal biopsy, initial response to treatment and future disease course (for example, the occurrence of renal flares). Initial intensive (induction) treatment of proliferative lupus nephritis is aimed at achieving remission, but optimal duration and intensity are not well defined. A combination of intravenous cyclophosphamide and corticosteroids have been shown to decrease the risk of end-stage renal disease, but are associated with substantial acute toxic effects (such as infections) and chronic toxic effects (such as ovarian failure). In white populations, low-dose cyclophosphamide is a reasonable alternative to high-dose cyclophosphamide as it is similarly effective and associated with less toxicity. Mycophenolate mofetil is as effective as high-dose intravenous cyclophosphamide in terms of inducing remission and similar in terms of safety. Although most patients respond to induction treatment, remission is often only achieved after patients are switched to maintenance treatment. As maintenance treatment, mycophenolate mofetil is superior to azathioprine and azathioprine is similarly effective to ciclosporin in terms of prevention or reducing the risk of relapse. Rituximab should be reserved for patients with refractory disease. Treatment of lupus nephritis should be individually tailored to patients, with more aggressive therapy reserved for patients at high risk of renal dysfunction and progression of renal disease.

Pharmacotherapy: concepts of pathogenesis and emerging treatments. Co-stimulation and T cells as therapeutic targets

Full activation and differentiation of resting T cells into effector T cells requires at least two signals, the first through engagement of the T cell antigen receptor (TCR) by the antigen-major histocompatibility complex (MHC) on antigen-presenting cells (APCs), and the second by engagement of co-stimulatory molecules such as CD28, on T cells by ligands such as CD80/86 on APCs. Effector T cell differentiation is associated with proliferation, secretion of cytokines and expression of additional surface molecules. These inducible structures may have stimulatory (ICOS, OX40 and 4-1BB) or inhibitory (cytotoxic T-lymphocyte antigen (CTLA)-4) potential. To the extent that T cells have a role in particular immune-mediated diseases, interruption of T cell co-stimulation is a potentially worthwhile approach to the treatment of those conditions. This article summarises the experience in treating rheumatological disease by perturbation of T cell co-stimulation, and also describes structures that could be future targets for this type of therapeutic approach.

New and emerging treatment approaches to lupus

The main goal in systemic lupus erythematosus (SLE) is to achieve remission, as this has a major impact on patient and renal survival. Furthermore, early treatment success has been shown to improve long-term prognosis. Treatment in severe SLE, especially in lupus nephritis, has traditionally been a standardized schematic therapy with cyclophosphamide and prednisolone followed by azathioprine. However, animal and human studies have increased our pathogenetic knowledge of this autoimmune disease with emerging new treatment targets. New and future therapeutic approaches are focused on B-cell depletion, T-cell downregulation and co-stimulatory blockade, cytokine inhibition, or the modulation of complement. Many different biological agents have been used in recent and ongoing studies, but up to now breakthroughs emerging from randomized Phase III trials have been rare. However, the future remains exciting with progress towards safe treatments with which to control the disease in the long run.

Contribution of IRF5 in B cells to the development of murine SLE-like disease through its transcriptional control of the IgG2a locus

Interferon regulatory factor (IRF) 5 is a key transcription factor for the activation of innate immune responses downstream of Toll-like receptor signaling. Based on recent genetic analyses, IRF5 is a focus for its potential involvement in systemic lupus erythematosus (SLE), although how IRF5 contributes to SLE is uncertain. In this study, we demonstrate a requirement for IRF5 in the development of murine SLE via its role in B lymphocytes. We show that antinuclear autoantibodies and Ig glomerular deposits, hallmarks of SLE, are absent in Irf5(-/-) mice challenged to develop SLE by pristane injection. In particular, production of autoantibodies of the IgG2a subtype, the most prominent isotype in inducing autoimmunity, requires IRF5. Finally, we provide evidence for the critical role of this transcription factor in the secretion of pathogenic antibodies through its direct control of class switch recombination of the gamma2a locus. By demonstrating a B-cell-intrinsic role, this study places IRF5 in a context that may have implications for understanding the pathogenesis of human SLE.

Treatment of systemic lupus erythematosus in two patients with extreme B-cell lymphopenia: importance of immunomonitoring and avoidance of B-cell targeted therapy

INTRODUCTION

Because dysfunction of the B-cell compartment is thought to be important in the pathogenesis of systemic lupus erythematosus (SLE), there has been a recent focus on therapies that target humoral immunity via multiple mechanisms. The aim of this paper was to demonstrate the importance of immunomonitoring in two cases with class II lupus nephritis on steroids who presented with a flare-up of disease. After a thorough work-up for infectious triggers of disease activity, conversion to another histopathological class of lupus nephritis was suspected. Deterioration of the patients' clinical condition made kidney biopsy impossible, and as B-cell targeted therapy was considered, we decided to perform an immunophenotypic analysis and to tailor therapy to the results of the lymphocyte profile. As we incidentally found extremely low B-cell counts, any B-cell-targeted therapy was prohibited, and cyclophosphamide (Cy) was considered a viable therapeutic option.

METHODS

We performed flow-cytometric lymphocyte (Ly) phenotyping (CD19, CD3, CD3CD4, CD3CD8, CD56/16) on two patients with class II lupus nephritis before and after two intravenous (i.v.) Cy pulse administrations. During all this time, patients were on steroids.

RESULTS

 Both patients showed extreme B-cell lymphopenia, a marker of active SLE, which was not greatly impacted by the treatment over the follow-up period.

CONCLUSIONS

As current therapies are aimed at targeting the B cell, an important component of adaptive immunity, caution must be exercised before their use. In addition, monitoring of Ly subsets is essential due to the occurrence of extreme B-cell lymphopenia.

Monoclonal Antibodies for Systemic Lupus Erythematosus (SLE)

A number of monoclonal antibodies (mAb) are now under investigation in clinical trials to assess their potential role in Systemic Lupus Erythematosus (SLE). The most frequently used mAb is rituximab, which is directed against CD20, a membrane protein expressed on B lymphocytes. Uncontrolled trials reported an improvement of SLE activity in non-renal patients and other studies even reported an improvement of severe lupus nephritis unresponsive to conventional treatments. However two randomized trials failed to show the superiority of rituximab over conventional treatment in non renal SLE and in lupus nephritis. Preliminary trials reported promising results with epratuzumab, a humanized mAb directed against CD22, and with belimumab, a human mAb that specifically recognizes and inhibits the biological activity of BLyS a cytokine of the tumornecrosis-factor (TNF) ligand superfamily. Other clinical trials with mAb directed against TNF-alpha, interleukin-10 (Il-10), Il-6, CD154, CD40 ligand, IL-18 or complement component C5 are under way. At present, however, in spite of good results reported by some studies, no firm conclusion on the risk-benefit profile of these mAbs in patients with SLE can be drawn from the available studies.

Novel B cell therapeutic targets in transplantation and immune-mediated glomerular diseases

B cells and antibodies play an important role in the alloresponse to renal grafts as well as in immune-mediated glomerular diseases. In transplantation, greater recognition and improved diagnosis of antibody-mediated rejection have been a catalyst to the introduction of newer drugs and regimens that target B cells, plasma cells, and donor-specific antibodies to improve the outcome associated with antibody-mediated rejection. In immune-mediated renal disease, novel and more selective B cell therapies are gradually modifying the traditional therapeutic approach that consists of steroids and other immunosuppressants. A new era of selective and more effective immunosuppression agents that target the humoral response is finally emerging in transplantation and renal diseases.

Clinical approach to lupus nephritis: recent advances

Kidney involvement is common in systemic lupus erythematosus (SLE). Its clinical presentations are highly variable, ranging from mild asymptomatic proteinuria and/or hematuria to rapidly progressive uremia. Histological evidence of lupus nephritis is present in most patients with SLE, even when they do not yet have clinical manifestations. Current classification ISN/RPS 2003 (International Society of Nephrology/Renal Pathology Society) of lupus nephritis was promoted by a widely perceived need to re-examine existing classification, provide clearer distinctions between the histological classes, and improve diagnostic reproducibility and interobserver agreement. Lupus nephritis is a serious disease whose prognosis can usually be improved dramatically by treatment, but treatment is potentially toxic, prolonged, and complex. Current treatment regimens combine corticosteroids with cyclophosphamide, azathioprine or ciclosporin; mycophenolate mofetil has received much recent attention as a potentially immune suppressive agent and less aggressive immunosuppressive regimens can be prescribed. SLE patients should be regular followed to detect early kidney involvement.

Rituximab treatment of fibrillary glomerulonephritis

Fibrillary glomerulonephritis belongs to a group of disorders characterized by pathogenic deposition of fibrils in glomeruli. This glomerulopathy tends to progress to end-stage kidney disease, and there currently are no treatments of proven benefit, including corticosteroids and cytotoxic agents. Because the glomerular deposits contain an immunoglobulin component, it was postulated that anti-B-cell therapy with rituximab, an anti-CD20 monoclonal antibody, may be effective in the treatment of patients with fibrillary glomerulonephritis. We describe 3 patients with fibrillary glomerulonephritis who were treated with rituximab for nephrotic-range proteinuria. Each patient also received standard antiproteinuria therapy, including blockade of the renin-angiotensin system and strict blood pressure control. All patients showed a decrease in proteinuria to less than 1.5 g/d of protein by 27 months, and kidney function was preserved throughout the duration of therapy and follow-up. No adverse effects were seen with rituximab. These outcomes suggest that treatment with rituximab may be a promising approach to the management of fibrillary glomerulonephritis, an entity previously considered refractory to therapy.