Assessment of disease activity and impending flare in patients with systemic lupus erythematosus. Comparison of the use of complement split products and conventional measurements of complement

Alternative pathway diagnostics

Uncontrolled alternative pathway activation is the primary driver of several diseases, and it contributes to the pathogenesis of many others. Consequently, diagnostic tests to monitor this arm of the complement system are increasingly important. Defects in alternative pathway regulation are strong risk factors for disease, and drugs that specifically block the alternative pathway are entering clinical use. A range of diagnostic tests have been developed to evaluate and monitor the alternative pathway, including assays to measure its function, expression of alternative pathway constituents, and activation fragments. Genetic studies have also revealed many disease-associated variants in alternative pathway genes that predict the risk of disease and prognosis. Newer imaging modalities offer the promise of non-invasively detecting and localizing pathologic complement activation. Together, these various tests help in the diagnosis of disease, provide important prognostic information, and can help guide therapy with complement inhibitory drugs.

The association between lupus serology and disease outcomes: A systematic literature review to inform the treat-to-target approach in systemic lupus erythematosus

INTRODUCTION

Serological markers such as anti-double stranded (ds)DNA antibodies and complement fractions C3/C4, are integral components of disease activity assessment in patients with systemic lupus erythematosus (SLE). However, it remains uncertain whether treatment should aim at restoration of serological abnormalities.

OBJECTIVES

To analyze and critically appraise the literature on the prognostic impact of active lupus serology despite clinical disease quiescence.

METHODS

A systematic literature review was performed in PubMed and EMBASE using the PICOT(S) (population, index, comparator, outcome(s), timing, setting) system to identify studies evaluating the association of serum anti-dsDNA, C3 and C4 levels assessed at the time of clinical remission or during the disease course, against the risk for impending flares and organ damage. Risk of bias was determined by the Quality in Prognosis Studies and ROB2 tools for observational and randomized controlled studies, respectively.

RESULTS

Fifty-three studies were eligible, the majority having moderate (70.6%) or high (11.8%) risk of bias and not adequately controlling for possible confounders. C3 hypocomplementemia during stable/inactive disease was associated with increased risk (2.0 to 3.8-fold) for subsequent flare in three out of seven relevant studies. Three out of four studies reported a significant effect of C4 hypocomplementemia on flare risk, including one study in lupus nephritis (likelihood ratio-positive 12.0). An increased incidence of flares (2.0 to 2.8-fold) was reported in 11 out of 16 studies assessing the prognostic effect of high anti-dsDNA, and similarly, the majority of studies yielded significant relationships with renal flares. Six studies examined the effect of combined (rather than individual) serological activity, confirming the increased risk (2.0 to 2.7-fold) for relapses. No consistent association was found with organ damage.

CONCLUSION

Notwithstanding the heterogeneity and risk of bias, existing evidence indicates a modest association between abnormal serology and risk for flare in patients with stable/inactive SLE. These findings provide limited support for inclusion of serology in the treat-to-target approach but rationalize to further investigate their prognostic implications especially in lupus nephritis.

Dysregulation of complement factor H in juvenile-onset systemic lupus erythematosus patients

Objectives

This study aims to evaluate the expression pattern of factor H in peripheral blood and the frequency of factor H autoantibodies in plasma of juvenile-onset systemic lupus erythematosus (jSLE) patients compared to healthy controls.

Patients and methods

Between March 2019 and October 2019, a total of 30 healthy individuals (3 males, 27 females; mean age: 26±7.4 years; range, 18 to 40 years) and 65 jSLE patients (age of onset ≤16 years) (2 males, 63 females; mean age: 23.4±7 years; range, 15 to 38 years) were included. Factor H expression pattern was examined in blood of all subjects using quantitative real-time polymerase chain reaction and the frequency of factor H autoantibodies was estimated in plasma using enzyme-linked immunosorbent assay.

Results

Factor H expression was significantly downregulated in jSLE patients compared to healthy controls (p<0.01). A significant underexpression of factor H was observed in jSLE patients with nephritis compared to those without nephritis (p<0.03), while there was no association of factor H expression levels with any of the other clinical and serological features, disease activity or disease damage index of patients. Only 5% of jSLE patients were positive for factor H autoantibodies without any correlations with the clinical data or disease activity of patients.

Conclusion

Our study results suggest that factor H expression can be dysregulated in jSLE patients.

Evaluation of neutrophil-to-lymphocyte ratio and platelet-to-lymphocyte ratio in pregnant women with systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is associated with a higher risk of complications in pregnancy. Neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR) have been evaluated in numerous inflammatory diseases. We evaluated the possible role of these markers in SLE pregnancies. Forty-six pregnant patients with an already established diagnosis of SLE were included in the study. Complete blood counts were obtained upon admission for delivery. Seven patients were diagnosed with a flare and managed with multiple medications, whereas rest of the patients were not on any treatment or managed with monotherapy. NLR and PLR values were also evaluated between two groups and no statistically significant difference was found (p=.44 and p=.80, respectively). This study is the first to evaluate the possible role of NLR and PLR in pregnant SLE patients in the literature. Further studies are warranted for an elaborate evaluation of NLR and PLR in lupus pregnancies.Impact StatementWhat is already known on this subject? Pregnancy in the setting of SLE is associated with a higher risk of complications. Active disease increases the risk of adverse outcomes further.What the results of this study add? This study is the first to evaluate NLR and PLR in pregnancies complicated by SLE. No significant association between the course of the disease in pregnancy and NLR/PLR was documented.What the implications are of these findings for clinical practice and/or further research? Further studies on the markers to predict prognosis of SLE in pregnancy are required to improve the maternal and neonatal outcomes in this exclusive group of high-risk patients.

Stealthiness and Hematocompatibility of Gold Nanoparticles with Pre-Formed Protein Corona

Studies have established that a serum protein corona pre-formed around gold nanorods (NRs) could be exploited for loading photosensitizers and chemotherapeutics to result in efficient cell kill in vitro with an extremely low dose. In this study, we further demonstrated that pre-forming a serum protein corona (PC) around citrate-capped NRs (NR-Cit) to form NR-PC conferred them stealth property and high hematocompatibility similar to the common strategy of PEGylating NRs, which would otherwise not be able to evade the immune system. Specifically, the NR-PC caused minimal complement activation with significantly lower formation of the terminal complement complex SC5b-9 measured in human serum containing NR-PC, and this resulted in low uptake by phagocytic U937 monocytes of 5.9% of the initial gold dose compared to 55.8% of NR-Cit. In addition, NR-PC exhibited very low hemolytic activity of less than 0.2% hemolysis with no observable effect on RBC morphology as opposed to 0.6% for NR-Cit at the same concentration of 1 nM NRs. Furthermore, we showed that the high hematocompatibility and stealth property of NR-PC were maintained even after the loading of small molecules, photosensitizer Chlorine e6 (Ce6), into the protein corona, thus further establishing the potential clinical relevance of exploiting the inevitably formed serum protein corona on nanoparticles as an effective delivery vector for small molecular therapeutics.

Clinical disease activity and flare in SLE: Current concepts and novel biomarkers

Systemic lupus erythematosus (SLE) is a complex and heterogeneous systemic autoimmune disease associated with innate and adaptive immune dysregulation. SLE occurs primarily in females of childbearing age, with increased prevalence and severity in minority populations. Despite improvements in treatment modalities, SLE patients frequently experience periods of heightened disease activity and flare that can lead to permanent organ damage, increased morbidity, and early mortality. Such outcomes impair quality of life and inflict a significant socioeconomic burden. Predicting changes in SLE disease activity could allow for closer monitoring and preemptive treatment, but existing clinical, demographic and serologic markers have been only modestly predictive. Novel, proactive approaches to clinical disease management are thus critically needed. Panels of blood biomarkers can detect a breadth of immune pathway dysregulation that captures SLE heterogeneity and disease activity. Alterations in the balance of pro-inflammatory and regulatory soluble mediators have been associated with changes in clinical disease activity and are detectable several weeks prior to clinical flare occurrence. A soluble mediator score has been highly predictive of impending flare in both European American and African American SLE patients, and this score does not require a priori knowledge of specific pathway activation in the patient. We review current concepts of disease activity and flare in SLE, focusing on the potential of novel blood biomarkers to characterize and predict changes in disease activity. Measuring the disordered immune response in SLE in this way promises to improve disease management and prevent organ damage in SLE.

Systemic lupus erythematosus: The search for the ideal biomarker

During the last decades, there has been an increased interest in the discovery and validation of biomarkers that reliably reflect specific aspects of lupus. Although many biomarkers have been developed, few of them have been validated and used in clinical practice, but with unsatisfactory performances. Thus, there is still a need to rigorously validate many of these novel promising biomarkers in large-scale longitudinal studies and also identify better biomarkers not only for lupus diagnosis but also for monitoring and predicting upcoming flares and response to treatment. Besides serological biomarkers, urinary and cerebrospinal fluid biomarkers have emerged for assessing both renal and central nervous system involvement in systemic lupus erythematosus, respectively. Also, novel omics techniques help us to understand the molecular basis of the disease and also allow the identification of novel biomarkers which may be potentially useful for guiding new therapeutic targets.

Soluble Membrane Attack Complex: Biochemistry and Immunobiology

The soluble membrane attack complex (sMAC, a.k.a., sC5b-9 or TCC) is generated on activation of complement and contains the complement proteins C5b, C6, C7, C8, C9 together with the regulatory proteins clusterin and/or vitronectin. sMAC is a member of the MACPF/cholesterol-dependent-cytolysin superfamily of pore-forming molecules that insert into lipid bilayers and disrupt cellular integrity and function. sMAC is a unique complement activation macromolecule as it is comprised of several different subunits. To date no complement-mediated function has been identified for sMAC. sMAC is present in blood and other body fluids under homeostatic conditions and there is abundant evidence documenting changes in sMAC levels during infection, autoimmune disease and trauma. Despite decades of scientific interest in sMAC, the mechanisms regulating its formation in healthy individuals and its biological functions in both health and disease remain poorly understood. Here, we review the structural differences between sMAC and its membrane counterpart, MAC, and examine sMAC immunobiology with respect to its presence in body fluids in health and disease. Finally, we discuss the diagnostic potential of sMAC for diagnostic and prognostic applications and potential utility as a companion diagnostic.

Alternative complement pathway activation in thrombotic microangiopathy associated with lupus nephritis

INTRODUCTION/OBJECTIVE

Thrombotic microangiopathy (TMA) in systemic lupus erythematosus is a rare manifestation associated with activation of the complement system. This study aimed to compare plasma and urine complement activation products between patients with active lupus nephritis (aLN) and those with acute TMA plus concomitant active LN (aTMA+aLN).

METHODS

Plasma and urine samples were obtained from 20 patients with aTMA+aLN, 20 patients with aLN matched by the histological activity index, 5 patients with chronic TMA, 20 patients with inactive LN, and 10 kidney donors. Complement fragments C3a, C4a, C4d, Ba, C5a, C5bC9, and factor H were determined by ELISA; and kidney C4d deposition was detected by immunohistochemistry. Patients were followed for > 12 months and complement activation products re-measured after treatment in 10 aTMA+aLN patients.

RESULTS

Both aTMA+aLN and aLN groups had increased circulating C3a, Ba, and C5bC9; and decreased circulating C3, C4, C4a, C4d, and factor H. Urinary C3a, C5a, Ba, and C5bC9 were higher in patients with aTMA+aLN than in aLN. After treatment, levels of circulating C3, C4, and factor H increased; while levels of urinary C3a, C5a, Ba, and C5bC9 decreased in patients with aTMA+aLN. These changes were observed at each aTMA episode in two patients studied during repeated TMA episodes. There was no difference in C4d deposition in glomerular capillaries, tubular basement membrane, peritubular capillaries, and arterioles between patients with aLN and those aTMA+aLN.

CONCLUSIONS

Circulating and urine complement activation products suggest that thrombotic microangiopathy associated with LN is mediated through activation of the alternative complement pathway. Key Points • Immune-complex kidney disease in systemic lupus erythematosus (SLE) is associated with activation of the classical, lectin, and alternative complement pathways • Indirect evidence from measurement of circulating and urinary complement pathway activation products suggests that renal acute thrombotic microangiopathy in SLE is mediated by activation of the alternative complement pathway • C4d kidney immunohistochemistry may be positive in both immune complex nephritis and thrombotic microangiopathy. Therefore, it is not a specific marker of renal thrombotic microangiopathy in SLE.

Urinary C3d is elevated in patients with active Lupus nephritis and a fall in its level after 3 months predicts response at 6 months on follow up

INTRODUCTION

Complement activation is central to the pathogenesis of lupus nephritis (LN). Low serum complement C3 and C4, are traditionally used as markers of lupus disease activity in general and LN in particular. In this study we prospectively measured plasma and urine C3d and C4d, degradation products of C3 and C4 corrected to creatinine in a cohort of biopsy proven LN in a longitudinal fashion for its correlation with disease activity.

METHODS

Twenty eight biopsy proven active lupus nephritis (AN) were recruited along with four inactive nephritis (IN) and 10 healthy controls (HC). Plasma and urine were collected at baseline, prior to induction treatment and 3 months later. Clinical measures of disease activity, Systemic lupus erythematosus disease activity index 2000 (SLEDAI 2K), renal SLEDAI, serum C3, C4 and antibodies to ds DNA, urine protein and creatinine excretion (UP/UC) were collected. Plasma and urine C3d and C4d were measured using ELISA and normalized to spot urine creatinine value.

RESULTS

Twenty eight AN of median age of 26.5 (20-31.50) years and disease duration of 3 (0.7-5) years were enrolled. The median urinary C3d/creatinine before treatment was 388.20 (48.98-1296) ng/mg which fell significantly to 62.69 (28.04-502.4) ng/mg at 3 months followup (p-0.01). The baseline values for the active renal disease was significantly different from IN group (9.9 (4.5-46.53 ng/mg) p-0.00). Treatment responders (partial and complete) at 6 months showed a significant fall in urinary C3d at 3 months whereas non responders had a non significant change in value. There was a significant correlation of urine C3d/creatinine with SLEDAI2K (r-0.433, p-0.00), renal SLEDAI (r-0.356, p-0.00), UP/UC ratio (r-0.489, p-<0.0001) but no significant correlation with C3 or C4. There was a significant fall in the median values of plasma C3d from 791.1 (516.0.00-1550.43) µg/ml to 338.52 (211.35-525.82) (p-0.00) µg/ml at the end of 3 months. The values showed a significant correlation with SLEDAI 2K, renal SLEDAI, UP/UC along with a significant negative correlation with C3 and C4.

CONCLUSION

Urinary C3d/creatinine levels and plasma C3d levels can be used as biomarker of disease activity and treatment response.

PEGylated Liposomal Methyl Prednisolone Succinate does not Induce Infusion Reactions in Patients: A Correlation Between in Vitro Immunological and in Vivo Clinical Studies

PEGylated nanomedicines are known to induce infusion reactions (IRs) that in some cases can be life-threatening. Herein, we report a case study in which a patient with rare mediastinal and intracardiac IgG4-related sclerosing disease received 8 treatments of intravenously administered PEGylated liposomal methylprednisolone-succinate (NSSL-MPS). Due to the ethical requirements to reduce IRs, the patient received a cocktail of premedication including low dose of steroids, acetaminophen and H2 blockers before each infusion. The treatment was well-tolerated in that IRs, complement activation, anti-PEG antibodies and accelerated blood clearance of the PEGylated drug were not detected. Prior to the clinical study, an in vitro panel of assays utilizing blood of healthy donors was used to determine the potential of a PEGylated drug to activate complement system, elicit pro-inflammatory cytokines, damage erythrocytes and affect various components of the blood coagulation system. The overall findings of the in vitro panel were negative and correlated with the results observed in the clinical phase.

Measuring plasma C4D to monitor immune complexes in lupus nephritis

Objective

Because currently available assays that measure circulating immune complexes (ICx) are suboptimal, a novel assay was recently developed measuring C4d, a stable product of activation of the classical complement pathway. The present study aimed to establish the value of measuring plasma C4d levels in a longitudinal cohort of patients with severe refractory SLE who were treated with a combination therapy of rituximab with belimumab (RTX+BLM).

Methods

Fifteen patients with SLE who were treated with RTX+BLM in a phase 2A, open label study were included to sequentially measure plasma C4d levels and correlated to well-established markers of ICx-formation, that is, autoantibodies against double-stranded (ds) DNA, autoantibodies against C1q and proteinuria. The performance of plasma C4d measurements, C4 measurements and the ratio of C4d over C4 (C4d:C4) was evaluated.

Results

After establishing that on RTX+BLM treatment kinetics of C4d levels was distinct from traditional C3 and C4 levels, we found strong correlation of C4d:C4 with anti-dsDNA (R=0.76, p<0.001) and anti-C1q (R=0.65, p<0.001) autoantibody levels, which outperformed both stand-alone C4 and C4d levels. Additionally, changes in C4d:C4 over time correlated strongly with changes in proteinuria (R=0.59, p<0.001) as well as anti-dsDNA (R=0.46, p=0.003) and anti-C1q (R=0.47, p=0.002).

Conclusion

In patients with severe SLE, plasma C4d levels in relation to C4 levels is useful for longitudinal monitoring after RTX+BLM treatment to reflect amelioration of classical complement activation by ICx as well as proteinuria.

Association of Blood Concentrations of Complement Split Product iC3b and Serum C3 With Systemic Lupus Erythematosus Disease Activity

Objective

To examine correlations between blood levels of complement split product iC3b and serum component C3 with clinically meaningful changes in disease activity in patients with systemic lupus erythematosus (SLE).

Methods

A total of 159 consecutive patients with SLE, diagnosed according to the American College of Rheumatology or Systemic Lupus International Collaborating Clinics classification criteria, were enrolled in CASTLE (Complement Activation Signatures in Systemic Lupus Erythematosus), a prospective observational study. Patients with 1–7 study visits were included in this longitudinal analysis. In addition, 48 healthy volunteers were enrolled to establish a normal reference value for the ratio of blood iC3b to serum C3 concentrations. Serum C3 and C4 levels were measured by nephelometry, and blood iC3b levels were measured by a lateral flow assay. SLE disease activity was monitored with the Responder Index 50 instrument of the SLE Disease Activity Index 2000.

Results

Relative changes in the iC3b:C3 ratio, levels of anti–double‐stranded DNA (anti‐dsDNA) antibodies, and use of a supraphysiologic dose of prednisone (>7.5 mg/day) each independently correlated with SLE disease activity, as determined in multilevel multiple logistic regression analyses. Only the iC3b:C3 ratio was significantly associated with clinically meaningful improvements in disease activity among patients with SLE who were receiving a supraphysiologic dose of prednisone. The iC3b:C3 ratio outperformed C3 and C4 levels with regard to discriminating active SLE from inactive SLE, and major flares from no disease activity. The iC3:C3 ratio, anti‐dsDNA antibody levels, erythrocyte sedimentation rate, and use of a supraphysiologic prednisone dose were each independently associated with the presence of lupus nephritis, whereas none of these measures was associated with SLE rash. The association of the iC3b:C3 ratio with lupus nephritis was independent of other observed clinical manifestations.

Conclusion

The ratio of blood iC3b to serum C3 concentrations correlates with the extent of SLE disease activity and with clinically meaningful changes in disease activity in patients with SLE. Furthermore, the iC3b:C3 ratio may discriminate between active and inactive SLE, and between major flares and no active disease.

Hypocomplementemia as a Risk Factor for Organ Damage Accrual in Patients with Systemic Lupus Erythematosus

While it is a common practice to monitor complement levels in patients with systemic lupus erythematosus to aid in flare prediction and detection, it is unclear if this strategy is helpful in preventing subsequent organ damage. We studied longitudinal complement levels in 102 SLE patients during a median follow-up of 13.8 years (IQR 7.0, 23.1). Low complement was defined as C3 < 0.84 g/L and/or C4 < 0.08 g/L, disease activity by clinical SLEDAI-2K, and organ damage by SLICC-DI. We calculated a time averaged clinical SLEDAI score (cWAS) and performed multivariate regression models to assess the independent predictive value of low complement for organ damage at last visit. Hypocomplementemia (HC) was observed in 67% of all patients and was more often due to low C3 (97%) than low C4 (54%). Compared to patients not developing HC (33%), HC patients were more frequently positive for anti-dsDNA Ab (72% vs 36%, p < 0.01) and aPL (74% vs 40%, p < 0.01) but HC was concurrently present with anti-dsDNA Ab in only half the cases. The time-adjusted cWAS scores (1.9 vs 1.2, p = 0.9), frequency (SDI > 0, n = 60), and type of organ damage accrual were similar for patients with and without HC (OR 1.08, p > 0.20). Intermittent or sustained HC has no predictive value for damage accrual in SLE or the underlying disease activity over time. This together with significant discrepancies in the concurrence of low C3, C4, and anti-dsDNA Ab indicates frequent activation of the complement pathway by other factors than immune complexes in SLE.

Cell-bound complement activation products (CB-CAPs) have high sensitivity and specificity in pediatric-onset systemic lupus erythematosus and correlate with disease activity

OBJECTIVE

Elevated levels of cell-bound complement activation products (CB-CAPs) (C4d deposition on B lymphocytes (BC4d) and/or erythrocytes (EC4d)) are sensitive and specific in diagnosis and monitoring of adult systemic lupus erythematosus (SLE). Our objective was to evaluate the role of CB-CAPs for diagnosis and monitoring of pediatric-onset SLE (pSLE).

METHODS

A prospective cohort study of 28 pSLE and 22 juvenile arthritis patients was conducted. SLE disease activity was determined using a clinical Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) that excluded serologies. Autoantibodies were measured using solid-phase immunoassays, C3 and C4 using immunoturbidimetry, and CB-CAPs using quantitative flow cytometry. Abnormal CB-CAPs were defined as EC4d or BC4d above the 99th percentile for healthy adults (>14 and > 60 net mean fluorescence intensity (MFI), respectively). Performance characteristics of CB-CAPs were assessed using area under the curve (AUC) for receiver operating characteristics. Linear mixed effect models evaluated the correlation between CB-CAPs and clinical SLEDAI over 6 months.

RESULTS

BC4d yielded higher AUC (0.91 ± 0.04) than C3 (0.63 ± 0.08) and C4 (0.67 ± 0.08) ( p < 0.05). Abnormal CB-CAPs were 78% sensitive and 86% specific for diagnosis of pSLE (Youden's index = 0.64 ± 0.11). In contrast to BC4d, EC4d levels correlated with clinical SLEDAI ( p < 0.01).

CONCLUSION

CB-CAPs (EC4d and BC4d) have higher sensitivity and specificity than low complement in pSLE, and may help with diagnosis of pSLE. EC4d could provide a useful biomarker for disease activity monitoring.

Erythrocyte-bound C4d in combination with complement and autoantibody status for the monitoring of SLE

Background

We examined the usefulness of erythrocyte-bound C4d (EC4d) to monitor disease activity in SLE.

Methods

Data and blood samples were collected from three different studies, each of which included longitudinal evaluations using the Physicians Global Assessment (PGA) of disease activity and the Safety of Estrogens in Lupus Erythematosus National Assessment (SELENA) SLE Disease Activity Index (SLEDAI), which was assessed without anti-double-stranded DNA (dsDNA) and low complement C3/C4 (clinical SELENA-SLEDAI). EC4d levels were determined using flow cytometry; other laboratory measures included antibodies to dsDNA, C3 and C4 proteins. Relationships between clinical SELENA-SLEDAI, PGA and the laboratory measures were analysed using linear mixed effect models.

Results

The three studies combined enrolled 124 patients with SLE (mean age 42 years, 97% women, 31% Caucasians and 34% African-Americans) followed for an average of 5 consecutive visits (range 2-13 visits). EC4d levels and low C3/C4 status were significantly associated the clinical SELENA-SLEDAI or PGA in each of the three study groups (p<0.05). Multivariate analysis revealed that EC4d levels (estimate=0.94±0.28) and low complement C3/C4 (estimate=1.24±0.43) were both independently and significantly associated with the clinical SELENA-SLEDAI (p<0.01) and PGA. EC4d levels were also associated with the clinical SELENA-SLEDAI (estimate: 1.20±0.29) and PGA (estimate=0.19±0.04) among patients with chronically low or normal C3/C4 (p<0.01). Anti-dsDNA titres were generally associated with disease activity.

Conclusion

These data support the association of EC4d with disease activity regardless of complement C3/C4 status and its usefulness in monitoring SLE disease. Additional studies will be required to support these validation data.

Plasma C4d as marker for lupus nephritis in systemic lupus erythematosus

BACKGROUND

In the present study, we sought to evaluate the complement activation product C4d as a marker for lupus nephritis in systemic lupus erythematosus (SLE).

METHODS

C4d levels were determined by enzyme-linked immunosorbent assay in plasma samples of patients with established SLE using a novel approach based on detection of a short linear cleavage neoepitope. Cross-sectional associations were studied in 98 patients with SLE with samples taken at lower or higher respective disease activity. Temporal associations were investigated in 69 patients with SLE who were followed longitudinally for up to 5 years. Plasma samples from 77 healthy donors were included as controls.

RESULTS

C4d levels were negligible in healthy control subjects and significantly increased in patients with SLE in the cross-sectional study (p < 0.0001). C4d levels discriminated between higher and lower disease activity according to ROC curve analysis (p < 0.001), exhibiting a positive predictive value of 68%. At higher disease activity, C4d levels correlated with the modified Systemic Lupus Erythematosus Disease Activity Index (p = 0.011) and predominantly with lupus nephritis (p = 0.003), exhibiting a sensitivity of 79% to identify patients with nephritis. High C4d levels together with the presence of anti-dsDNA autoantibodies preceded and thus predicted future lupus nephritis in the longitudinal study (OR 5.4, 95% CI 1.4-21.3). When we considered only patients with renal involvement (19 of 69) during the longitudinal study, we found that high C4d levels alone could forecast recurrence of future lupus nephritis (OR 3.3, 95% CI 1.2-9.6).

CONCLUSIONS

C4d appears to be a valuable marker for use in monitoring of patients with SLE, particularly for lupus nephritis. Importantly, C4d levels can predict impending flares of lupus nephritis and may thus be useful for informing treatment.

Predictive biological markers of systemic lupus erythematosus flares: a systematic literature review

BACKGROUND

The aim of this study was to identify the most reliable biomarkers in the literature that could be used as flare predictors in systemic lupus erythematosus (SLE).

METHODS

A systematic review of the literature was performed using two databases (MEDLINE and EMBASE) through April 2015 and congress abstracts from the American College of Rheumatology and the European League Against Rheumatism were reviewed from 2010 to 2014. Two independent reviewers screened titles and abstracts and analysed selected papers in detail, using a specific questionnaire. Reports addressing the relationships between one or more defined biological test(s) and the occurrence of disease exacerbation were included in the systematic review.

RESULTS

From all of the databases, 4668 records were retrieved, of which 69 studies or congress abstracts were selected for the systematic review. The performance of seven types of biomarkers performed routinely in clinical practice and nine types of novel biological markers was evaluated. Despite some encouraging results for anti-double-stranded DNA antibodies, anti-C1q antibodies, B-lymphocyte stimulator and tumour necrosis factor-like weak inducer of apoptosis, none of the biomarkers stood out from the others as a potential gold standard for flare prediction. The results were heterogeneous, and a lack of standardized data prevented us from identifying a powerful biomarker.

CONCLUSIONS

No powerful conclusions could be drawn from this systematic review due to a lack of standardized data. Efforts should be undertaken to optimize future research on potential SLE biomarkers to develop validated candidates. Thus, we propose a standardized pattern for future studies.

SLE and Serum Complement: Causative, Concomitant or Coincidental?

BACKGROUND

Systemic Lupus Erythematosus (SLE) is an incurable autoimmune disorder with complement activation playing a key role in the pathogenesis of immune-mediated tissue injury. While quantifying complement to monitor SLE disease activity has been the standard of care since the 1950s, decreased complement levels are not consistently associated with flares.

OBJECTIVE

We seek to clarify the SLE phenotype in which complement deficiency is causative, concomitant, or coincidental.

METHODS

A PUBMED literature review was conducted using key words 'complement,' 'SLE,' and 'SLE flares' in English-only journals from 1972-2017. Relevant clinical studies and review articles were found that examined the measurement of complement levels in SLE, and more specifically, interpretation of low serum complement levels regardless of disease activity.

CONCLUSION

Complement activation plays a key role in the pathophysiology of SLE and it is recommended to continue monitoring serum levels of C3 and C4 to assess for disease activity. However, it is important to note that decreased serum complement is not consistently associated with disease flares.It is clinically important to find novel ways to assess disease activity in SLE. Reduced serum levels of cell-bound complement activation products may more accurately reflect disease activity than conventional serum C3 and C4 monitoring.

Complement levels and risk of organ involvement in patients with systemic lupus erythematosus

Objective

Complement plays a major role in SLE. Complement participation has been linked to disease activity and damage. Our objective was to estimate the association of complement behaviour with clinical manifestations, visceral injury and mortality in patients with SLE.

Methods

Complement determinations (C3 and C4 levels) were analysed in patients with SLE (fulfilling American College of Rheumatology (ACR) or Systemic Lupus International Collaborating Clinics (SLICC)criteria) seen at a university hospital between 2000 and 2013. Patients were grouped in those with permanent C3 and/or C4 low values (low complement group), those with C3 and C4 constant normal values (normal complement group) and those with fluctuant values (periods of normal and periods of low values: fluctuant group). Clinical characteristics and mortality were analysed and compared between groups.

Results

270 patients with SLE were included (242 females, 89.6%), mean age at diagnosis was 34.2 years (SD 15.8). 75 patients had fluctuant levels of complement, 79 patients had persistent low complement levels and 116 had normal complement levels. Lupus glomerulonephritis was more frequent in patients with fluctuant levels (75%, 56% and 49%, respectively, p=0002). The normal complement group had less frequency of haematological involvement and anti-double stranded DNA (dsDNA) antibodies. At the end of the follow-up, 53% of the patients had damage (SLICC/ACR ≥1). In a Cox proportional hazard model age at diagnosis, neurological impairment, thrombocytopaenia and corticosteroids were associated with more damage, while hydroxychloroquine was a protective factor. There were no differences between complements groups on accumulated damage. Ten-year survival rate was 93%, 93.5% and 92% for the normal complement group, the persistently low group and the fluctuant group, respectively.

Conclusions

Patients with constant normal complement had lower prevalence of haematological involvement and anti-dsDNA, while patients with fluctuant complement had higher renal impairment. Neither the persistent low complement nor the fluctuant complement groups had increased mortality and/or visceral damage.

Genetic variants in FH are associated with renal histopathologic subtypes of lupus nephritis: a large cohort study from China

Objective Genetic variants in FH (complement factor H) were reported to associate with susceptibility to systemic lupus erythematosus (SLE). This study proposed that the genetic defects of FH in the susceptibility and in the development of lupus nephritis might be different. Methods This study enrolled 334 lupus nephritis patients, 269 SLE patients without clinical renal involvement and 350 controls. Two-step genotyping was performed. First, all the exons of the FH gene were fully sequenced in 100 lupus nephritis patients and 100 healthy controls. Second, genotyping of three common variants reported to be functional, rs1061170, rs800292 and rs6677604, was conducted in all the recruited individuals. Further, analysis of their associations with SLE/lupus nephritis susceptibility and the clinico-pathological parameters in the lupus nephritis group was performed. Results No significant differences were observed in allele and genotype frequencies of the three single nucleotide polymorphisms between lupus patients and controls. There was a significantly higher ratio of CC/CT genotypes of rs1061170 in lupus nephritis patients with class III than in the other two classes (class III vs. class IV vs. class V: 21.0% vs. 9.7% vs. 9.4%; P = .044). The rs6677604-GG genotype was observed to be associated with the absence of anti-ds DNA antibody ( P = .021), and the rs800292-TT genotype was associated with a higher level of circulating C3 ( P = 0.20) in lupus nephritis. Conclusion In an independent cohort, this is the first genetic association analysis focusing on FH genetic variants in Chinese lupus nephritis patients. It was found that the variants in the FH gene might affect the histopathologic subtypes and some clinical features of the disease.

Complement Alternative Pathway׳s Activation in Patients With Lupus Nephritis

OBJECTIVE

The aim of this study was to detect the spectrum of complement activation pathways in circulation and to assess their correlations with clinical and pathologic features in a large lupus nephritis cohort from China.

MATERIALS AND METHODS

Plasma levels of C1q, mannose-binding lectin, C4d, Bb, C3, C3a, C5a and soluble C5b-9 were detected by enzyme-linked immunosorbent assay in 222 patients with active biopsy-proven lupus nephritis, 34 patients with lupus nephritis at remission, 82 patients with active systemic lupus erythematosus without renal involvement and 39 normal controls. The correlations between levels of complement components and clinicopathological features of these patients were further analyzed.

RESULTS

Plasma levels of C1q and C3 significantly decreased, and the levels of Bb, C3a, C5a and soluble C5b-9 were significantly elevated in patients with active lupus nephritis compared with those in remission, active systemic lupus erythematosus without renal involvement group and normal controls. In the lupus nephritis group, soluble C5b-9 levels were inversely correlated with C1q and C4d levels (r = -0.412, P < 0.001 and r = -0.221, P = 0.002, respectively), but more strongly correlated with the level of Bb (r = 0.546, P < 0.001). C3b, Bb and C5b-9 could colocalize on glomeruli in lupus nephritis. Plasma Bb level was significantly correlated with some renal disease activity indices and was a risk factor for renal outcomes (hazard ratio = 1.745; 95% CI: 1.106-2.754; P = 0.017) in the lupus nephritis group.

CONCLUSIONS

Our findings suggested that the activation of the complement alternative pathway might play a more important role in the pathogenesis of lupus nephritis, and factor Bb might be a useful marker for evaluating renal disease activity and outcomes.

Reduction in erythrocyte-bound complement activation products and titres of anti-C1q antibodies associate with clinical improvement in systemic lupus erythematosus

Background

The relationship between cell-bound complement activation products (CB-CAPs: EC4d, EC3d), anti-C1q, soluble complement C3/C4 and disease activity in systemic lupus erythematosus (SLE) was evaluated.

Methods

Per protocol, at baseline all SLE subjects enrolled in this longitudinal study presented with active disease and elevated CB-CAPs. At each monthly visit, the non-serological (ns) Safety of Estrogens in Lupus Erythematosus: National Assessment (SELENA-SLEDAI) and the British Isles Lupus Assessment Group (BILAG)-2004 index scores were determined as was a random urinary protein to creatinine ratio (uPCR). Short-form 36 (SF-36) questionnaires were also collected. All soluble markers were determined using immunoassays, while EC4d and EC3d were determined using flow cytometry. Statistical analysis consisted of linear mixed models with random intercept and fixed slopes.

Results

A total of 36 SLE subjects (mean age 34 years; 94% female) were enrolled and evaluated monthly for an average 11 visits per subject. Clinical improvements were observed during the study, with significant decreases in ns-SELENA-SLEDAI scores, BILAG-2004 index scores and uPCR, and increases in all domains of SF-36 (p<0.01). The longitudinal decrease in ns-SELENA-SLEDAI and BILAG-2004 index scores was significantly associated with reduced EC4d and EC3d levels, reduced anti-C1q titres and increased serum complement C3/C4 (p<0.05). The changes in uPCR significantly correlated with C3, C4, anti-C1q and EC4d, with EC4d outperforming C3/C4 by a multivariate analysis. The reduced EC4d or EC3d was associated with improvements in at least six out of the eight domains of SF-36 and outperformed C3/C4. Anti-dsDNA titres did not correlate with changes in disease activity.

Conclusions

These data indicate that CB-CAPs and anti-C1q are helpful in monitoring patients with SLE.

New insights into complement: a mediator of injury and marker of disease activity in systemic lupus erythematosus

Studies performed during the past several decades have demonstrated a role for the complement system in both the etiology and pathogenesis of systemic lupus erythematosus (SLE). However the specifically defective molecular and cellular pathways responsible for the disease and its complications have generally not been identified. In this report, we describe two recent advances in complement pathobiology that highlight future directions for promising investigation toward enhancing our capacity to diagnose SLE, to monitor activity of the disease, and to identify molecular and cellular defects in SLE that can be targeted by therapeuticinhibitors of complement activation.In the first example, we describe recently developed assays to detect erythrocyte C4d and complement receptor1 for diagnosis and monitoring of disease activity in SLE. In the second example, we describe a recently discovered role for complement in mediating fetal loss in antiphospholipid syndrome and discuss the potential for this observation to facilitate identification and development of complement based biomarkers to predict poor fetal outcome in pregnant patients with SLE. These two examples are meant to underscore the importance of complement in the etiology and pathogenesis of SLE and its complications, and to stress the need for further investigation focused on the link between the complement system and SLE.

Serum C3 and uterine artery Doppler indices at 14-20 weeks gestation for preeclampsia screening in low-risk primigravidas: A prospective observational study

PROBLEM

Preeclampsia affects 2-10% of human pregnancies with poor screening tests. In order to intervene preventively, high risk population should be identified before the 20th week of pregnancy and by a method not subjected to operator efficiency.

METHODOLOGY

Prospective observational study recruiting 825 low risk primigravidas. Serum C3 and uterine artery Doppler indices were measured at 14-20 weeks.

RESULTS

Serum C3 levels at 14-20 weeks of gestation had a sensitivity 83.3%, specificity 100%, PPV 100% and NPV 98.3% when the cut-off value was 53.1mg/. For the mean RI, the best cut off value found was 0.72 with 100% sensitivity, 99.1% specificity, 92.3% PPV and 100% NPV. For the mean PI the best cut off value was 1.35 with 100% sensitivity, 94.1% specificity, 63.2% PPV and 100% NPV. The combination of serum C3 level and mean uterine artery PI showed 100% sensitivity, 97.4% specificity, 80% PPV and 100% NPV in prediction of PE.

CONCLUSION

Serum C3 levels at 14-20 weeks can be used for prediction of PE with comparable results to uterine artery Doppler indices but has the superiority of being operator independent.

Associations of the Levels of C4d-bearing Reticulocytes and High-avidity Anti-dsDNA Antibodies with Disease Activity in Systemic Lupus Erythematosus

Objective.

There are no laboratory tools that detect early flares in systemic lupus erythematosus (SLE). Our aim was to validate in our population the previous findings of the association of C4d-bearing reticulocytes (R-C4d) compared to anti-dsDNA antibodies, with disease activity assessed by the Safety of Estrogens in Lupus Erythematosus National Assessment–Systemic Lupus Erythematosus Disease Activity Index (SELENA-SLEDAI) and the British Isles Lupus Assessment Group (BILAG) 2004 scales.

Methods.

All patients who met the 1987 American College of Rheumatology classification criteria and were seen consecutively in 2013 at a specialized SLE care clinic were included. Disease activity was established by the SELENA-SLEDAI and BILAG 2004. Anti-dsDNA and R-C4d were quantified in peripheral blood. Comparisons were made between values of active and inactive patients, and the correlations between the SELENA-SLEDAI and serum levels of anti-dsDNA and R-C4d were measured.

Results.

Sixty-two patients (83.9% women) were included. A total of 32.3% had active disease according to the SELENA-SLEDAI. There was a significant statistical difference (p = 0.0001) in the distribution of R-C4d between disease activity groups. The correlation coefficient between R-C4d and the SELENA-SLEDAI score was rs = 0.738 (p = 0.0001). R-C4d differed between patients with and without activity in the BILAG 2004 constitutional, mucocutaneous, gastrointestinal, renal, and hematological domains.

Conclusion.

R-C4d showed a higher correlation with SLE activity measured by the SELENA-SLEDAI and BILAG 2004 than anti-dsDNA did, suggesting a possible involvement in diagnosing disease activity. Prospective studies that confirm these findings and evaluate its involvement in followup are needed.

The dysfunctions of complement factor H in lupus nephritis

OBJECTIVE

Our previous study showed that plasma levels of factor H (FH) were significantly decreased in patients with lupus nephritis and reflected lupus nephritis activity. The aim of this study was to further investigate in vitro biofunctions of plasma FH in patients with lupus nephritis.

METHODS

FH was purified from the first run of plasma exchange in four active lupus nephritis patients and two non-renal involvement systemic lupus erythematosus (SLE) patients, and plasma from two healthy controls. Then, the biofunctions of the purified FH were analyzed. In addition, FH exons sequencing analysis was performed.

RESULTS

Homogeneous FH was purified from the plasma fractions and the purity of the purified FH was comparable to the commercial FH. The abilities of FH binding with C3b and mCRP, and its protecting abilities from the lysis of sheep erythrocytes, from No. 3 and No. 4 lupus nephritis patients, decreased significantly compared with those in normal controls. The purified FH from lupus nephritis patients Nos. 2-4 could not induce the phagocytosis of late apoptotic cells significantly compared with normal controls. All four lupus nephritis patients had the known SNP rs1061147 (SCR5, A307A), rs1061170 (SCR7, Y402H), CM050194 (SCR20, S1191W) and CM010322 (SCR20, V1197A), which might be associated with the above dysfunctions.

CONCLUSIONS

Dysfunctions of FH, including the regulations of complement alternative pathway and the clearance of apoptotic cells, were found in some active lupus nephritis patients, which were associated with their clinical phenotypes. The FH SNPs might contribute to the dysfunctions of FH in patients with lupus nephritis.

C5a alters blood-brain barrier integrity in a human in vitro model of systemic lupus erythematosus

The blood-brain barrier (BBB) plays a crucial role in brain homeostasis, thereby maintaining the brain environment precise for optimal neuronal function. Its dysfunction is an intriguing complication of systemic lupus erythematosus (SLE). SLE is a systemic autoimmune disorder where neurological complications occur in 5-50% of cases and is associated with impaired BBB integrity. Complement activation occurs in SLE and is an important part of the clinical profile. Our earlier studies demonstrated that C5a generated by complement activation caused the loss of brain endothelial layer integrity in rodents. The goal of the current study was to determine the translational potential of these studies to a human system. To assess this, we used a two dimensional in vitro BBB model constructed using primary human brain microvascular endothelial cells and astroglial cells, which closely emulates the in vivo BBB allowing the assessment of BBB integrity. Increased permeability monitored by changes in transendothelial electrical resistance and cytoskeletal remodelling caused by actin fiber rearrangement were observed when the cells were exposed to lupus serum and C5a, similar to the observations in mice. In addition, our data show that C5a/C5aR1 signalling alters nuclear factor-κB translocation into nucleus and regulates the expression of the tight junction proteins, claudin-5 and zonula occludens 1 in this setting. Our results demonstrate for the first time that C5a regulates BBB integrity in a neuroinflammatory setting where it affects both endothelial and astroglial cells. In addition, we also demonstrate that our previous findings in a mouse model, were emulated in human cells in vitro, bringing the studies one step closer to understanding the translational potential of C5a/C5aR1 blockade as a promising therapeutic strategy in SLE and other neurodegenerative diseases.

Pegylated liposomal mitomycin C prodrug enhances tolerance of mitomycin C: a phase 1 study in advanced solid tumor patients

Mitomycin C (MMC) has potent cytotoxicity but cumulative toxicity limits widespread use. In animals, pegylated liposomal mitomycin C lipid-based prodrug (PL-MLP) was well tolerated and more effective than free MMC. We evaluated PL-MLP in patients with advanced cancer. Twenty-seven patients were treated in escalating dose cohorts of 0.5–3.5 mg/kg (equivalent to 0.15–1.03 mg/kg MMC) every 4 weeks for up to 12 cycles, unless disease progression or unacceptable toxicity occurred. Pharmacokinetics were assessed during cycles 1 and 3. Per protocol maximum tolerated dose was not reached at 3.5 mg/kg. However, prolonged thrombocytopenia developed after repeated doses of 3 mg/kg or cumulative doses of 10–12 mg/kg. Dose-related grade 3 or higher adverse events included fatigue, anemia, and decreased platelets. C_max and AUC_0-∞ increased linearly over the dose range 0.5–2.0 mg/kg, and greater than linearly from 2.5 to 3.5 mg/kg; there were no significant differences in clearance of MLP between cycles 1 and 3. Median t_1/2 was 23 h among dose cohorts, with no trend by dose or cycle. One patient had a partial response. Stable disease was observed in 10 patients across all dose levels. PL-MLP has a long circulation time, was well tolerated, and can be administered to heavily pretreated patients at a single dose of 3.0 mg/kg and cumulative dose of 10–12 mg/kg before development of prolonged thrombocytopenia; this is nearly threefold the equivalent dose of MMC tolerated historically. This formulation may be active in a variety of tumor types and is better tolerated than free MMC.

Therapeutic effect of double-filtration plasmapheresis combined with methylprednisolone to treat diffuse proliferative lupus nephritis

OBJECTIVE

The efficacy of double-filtration plasmapheresis (DFPP), combined with methylprednisolone, to treat diffuse proliferative lupus nephritis (LN) was studied.

METHODS

Twenty-four patients who were admitted to the hospital and diagnosed with diffuse proliferative LN (LN Class IV-G(A)) through renal biopsy from 2011 to 2013 were recruited as the study subjects. The patients' clinical manifestations were nephritic syndrome and/or renal insufficiency. The pathological features were glomerular diffuse proliferative lesions. The patients were divided into two groups: the treatment group and the control group, with 12 patients in each group. The patients in the treatment group were first treated with DFPP combined with methylprednisolone (0.8-1.0 mg/kg/day); subsequently, they were put on methylprednisolone therapy only. The patients in the control group were first put on methylprednisolone pulse therapy (500-1,000 mg) for 3 days; subsequently, they were treated with methylprednisolone (0.8-1.0 mg/kg/day) combined with mycophenolate mofetil (1.5 g/day). The patients were observed for 24 months. Levels of hemoglobin, platelet, albumin, serum creatinine, 24-h urinary protein, serum C3 , antinuclear antibody (ANA), anti-dsDNA, and anti-Smith were measured at 0, 3, 6, 12, and 24 months. Complete remission and recurrence standards were established. The total dosages of methylprednisolone were calculated. Repeated renal biopsy was performed on several patients.

RESULTS

There was no statistical significance in the baseline conditions of the treatment and the control groups. For the treatment group, no plasmapheresis-related complications occurred. The two groups showed no significant difference in complete remission. The patients' edema and serous effusion resolved, urine volume, serum creatinine, and albumin levels returned to normal, urine protein decreased in treatment group more rapidly than the patients in the control group. The mean dose of methylprednisolone received in the treatment group was lower than in the control group. The complement C3 levels in the treatment group were significantly higher than in the control group. The recurrence rate in the treatment group was lower than in the control group. Repeated renal biopsies on several patients in the treatment group indicated that their pathology improved significantly, changing from LN (IV) to LN(II-III).

CONCLUSIONS

Appropriate application of DFPP combined with glucocorticoid therapy could accelerate the remission of diffuse proliferative LN, reduce overall glucocorticoid dosage, prevent recurrence, and maintain C3 level in a higher level. J. Clin. Apheresis 31:375-380, 2016. © 2015 Wiley Periodicals, Inc.

Clinicopathological characteristics and outcomes of Chinese patients with scanty immune deposits lupus nephritis: a large cohort study from a single center

Objective. To assess clinicopathological characteristics of lupus nephritis patients with scanty immune deposits. Methods. The data of patients with scanty immune deposits lupus nephritis were retrospectively analyzed. Plasma ANCA and complement components were detected. Results. Among 316 cases with renal biopsy-proven lupus nephritis, 40 cases were diagnosed as scanty immune deposits. There were significantly higher value of serum creatinine (P = 0.002) and lower hemoglobin level (P = 0.009) and higher score of cellular crescents (P = 0.015) in scanty immune deposits group compared with immune complex deposits group. The frequency of positive plasma ANCA was significantly higher in scanty immune deposits group than that in immune complex deposits group (52.5% versus 10.1%, P < 0.001). As for comparisons of plasma complement components, there were significantly higher levels of C1q (P = 0.005) and Bb (P = 0.02) and lower level of factor H (P = 0.003) in scanty immune deposits group. The ratio of treatment failure was significantly higher in scanty immune deposits group than that in immune deposits group (42.5% versus 19.20%, P = 0.001). The renal outcomes were similar between the two groups. Conclusions. Patients with scanty immune deposits lupus nephritis had more severe kidney damage. ANCA and activation of complement alternative pathway might be involved in the pathogenesis of the disease.

Serum complement factor H is associated with clinical and pathological activities of patients with lupus nephritis

OBJECTIVE

The aim of this study was to investigate serum complement factor H (CFH) and its associations with clinical and pathological features in patients with LN.

METHODS

Serum CFH was detected in 241 LN patients, 38 active and 11 inactive patients with SLE without clinical evidence of renal involvement and 51 normal controls. Serum CFH autoantibodies and CFH Tyr402His were screened in the 241 LN patients. CFH deposition in kidneys was detected in some patients.

RESULTS

Serum CFH levels in patients with LN at active phase were significantly lower than in 38 SLE patients or in normal controls. No serum anti-CFH autoantibodies were detected in patients with LN, and there was no significant difference in CFH Tyr402His distribution between patients with LN and normal controls. Glomerular expression of CFH was stronger than in normal controls. Serum CFH levels were mildly negatively associated with SLEDAI scores (r = -0.204, P = 0.001) and positively associated with serum C3 (r = 0.367, P < 0.001) and haemoglobulin levels (r = 0.193, P = 0.003). Patients with LN class III, subclass IV-S and those with thrombotic microangiopathy had the lowest serum CFH.

CONCLUSION

Serum CFH levels were associated with disease activity of LN.

Biomarkers for systemic lupus erythematosus

In recent years, biomarkers have shown significant promise in helping decision-making in drug development. Systemic lupus erythematosus (SLE) is a complicated and highly heterogeneous disease that involves all organs. Only one drug, belimumab, has been approved by the US Food and Drug Administration to treat SLE during the last 50 years and there remains a high unmet medical need to develop new and effective therapies to benefit different patient populations in SLE. Due to the extreme heterogeneity of the disease and the complex and rigorous process to validate individual biomarkers, there is currently a very limited number of consensus biomarkers to aid the treatment decision-making in SLE. This review provides a snapshot of some biomarkers in the field that have the potential to make a big impact on drug development and/or treatment decisions by physicians. These include: type I interferon (IFN) gene signature as a pharmacodynamic marker and potential predictive marker for anti-type I IFN therapy; anti-double stranded DNA as a disease marker and potential predictive marker for flares; the complements and neutrophil signatures as disease marker of SLE; and TWEAK (a tumor necrosis factor family member produced by macrophages) and MCP-1 as potential markers to predict renal flares. Most of these markers need carefully planned and prospective studies with high statistical power to confirm their respective utilities. With the development and application of powerful new technologies, more successful biomarkers will emerge in SLE. This could improve the management of patients in the clinic and facilitate the development of novel and more effective therapeutics for this difficult-to-treat disease.

Therapeutic regulation of complement in patients with renal disease - where is the promise?

Numerous renal diseases are characterized by complement activation within the kidney, and several lines of evidence implicate complement activation as an important part of the pathogenesis of these diseases. Investigators have long anticipated that complement inhibitors would be important and effective therapies for renal diseases. Eculizumab is a monoclonal antibody to the complement protein C5 that has now been administered to patients with several types of renal disease. The apparent efficacy of this agent may herald a new era in the treatment of renal disease, but many questions about the optimal use of therapeutic complement inhibitors remain. Herein we review the rationale for using complement inhibitors in patients with renal disease and discuss several drugs and approaches that are currently under development.

Validation of new biomarkers in systemic autoimmune diseases

Biomarkers have an important influence on the clinical decision-making processes involved in diagnosis, assessment of disease activity, allocation of treatment, and determining prognosis. The clinical usefulness of a biomarker is dependant on demonstration of its validity. Ideally, biomarkers should provide information not available from currently available tests and should be tested as they would be used in clinical practice; however, potential biomarkers could be affected by many different clinical or patient variables-such as disease activity, therapeutic intervention, or the presence of comorbidities--and validation studies might not include all the design features that are required to ensure that the biomarker is a true measure of the clinical process it is intended to reflect. In this Review, we appraise studies that have been conducted to validate six promising new biomarkers for diagnosis, disease activity assessment, or prognosis in patients with systemic autoimmune diseases. We discuss the validity of these six biomarkers with particular reference to the features of the studies that lend weight to or distract from their findings. The intent of this discussion is to draw attention to elements of validation study design that should be considered when evaluating the robustness of a biomarker, which differ according to the marker's intended use.

C5a/CD88 signaling alters blood-brain barrier integrity in lupus through nuclear factor-κB

Inflammation is a key factor in a number of neurodegenerative diseases including systemic lupus erythematosus. The complement system is an important mechanism in initiating and amplifying inflammation. Our recent studies demonstrate that C5a, a protein fragment generated during complement activation could alter the blood-brain barrier integrity, and thereby disturb the brain microenvironment. To understand the mechanism by which this occurs, we examined the effects of C5a on apoptosis, translocation of nuclear factor-κB (NF-κb) and the expression of Iκbα, MAPK, CREB and TJ protein, zona occludens (ZO-1) in mouse brain endothelial cells. Apoptosis was examined by DNA laddering and caspase 3 activity and the distribution of the ZO-1 and the p65 subunit of NF-κB were determined by immunofluorescence. Inhibition of CD88 reduced translocation of NF-κb into the nucleus, altered ZO-1 at the interfaces of neighboring cells, decreased caspase 3 activity and prevented apoptosis in these cells. Our results indicate that signaling through CD88 regulates the blood-brain barrier in a NF-κb-dependent manner. These studies suggest that the C5a receptor, CD88 is a promising therapeutic target that will reduce NF-κb-signaling cascades in inflammatory settings.

Activation of complement by therapeutic liposomes and other lipid excipient-based therapeutic products: prediction and prevention

Some therapeutic liposomes and lipid excipient-based anticancer drugs are recognized by the immune system as foreign, leading to a variety of adverse immune phenomena. One of them is complement (C) activation, the cause, or major contributing factor to a hypersensitivity syndrome called C activation-related pseudoallergy (CARPA). CARPA represents a novel subcategory of acute (type I) hypersensitivity reactions (HSR), which is mostly mild, transient, and preventable by appropriate precautions. However, in an occasional patient, it can be severe or even lethal. Because a main manifestation of C activation is cardiopulmonary distress, CARPA may be a safety issue primarily in cardiac patients. Along with an overview of the various types of liposome-immune system interactions, this review updates the experimental and clinical information on CARPA to different therapeutic liposomes and lipid excipient-based (micellar) anticancer drugs, including PEGylated liposomal doxorubicin sulfate (PLD, Doxil®) and paclitaxel (Taxol®). The substantial individual variation of in vitro and in vivo findings reflects an extremely complex immune phenomenon involving multiple, redundant pathways of C activation, signal transduction in allergy-mediating cells and vasoactive mediator actions at the effector cell level. The latest advances in this field include the proposal of doxorubicin-induced shape changes and aggregation of liposomes in Doxil as possible contributing factors to CARPA caused by PLD, and the finding that Doxil-induced immune suppression prevents HSR to co-administered carboplatin, a significant benefit of Doxil in combination chemotherapy with carboplatin. The review evaluates the use of in vitro C assays and the porcine liposome-induced cardiopulmonary distress model for predicting CARPA. It is concluded that CARPA may become a frequent safety issue in the upcoming era of nanomedicines, necessitating its prevention at an early stage of nanomedicine R&D.

The benefit of targeted and selective inhibition of the alternative complement pathway for modulating autoimmunity and renal disease in MRL/lpr mice

OBJECTIVE

Complement has both protective and pathogenic functions in lupus due to a balance between its role in the clearance of immune complexes (ICs) and apoptotic cells and its role in inflammation. The classical pathway contributes to IC and apoptotic cell clearance, whereas the alternative pathway is a key mediator of renal inflammation. The aim of this study was to investigate the effect of a new targeted inhibitor of the alternative pathway, CR2-fH, on lupus-like renal disease in MRL/lpr mice.

METHODS

Mice were treated with either saline, CR2-fH, CR2-Crry (which inhibits all complement pathways), or soluble CR2 (sCR2; C3d-binding targeting vehicle). Sera were analyzed every 2 weeks for autoantibodies, circulating ICs, and C3. Urinary excretion of albumin was also determined, and kidneys were collected at 23 weeks for histologic evaluation.

RESULTS

Treatment with CR2-fH or CR2-Crry improved survival and significantly reduced proteinuria, glomerular C3 deposition, and the level of circulating ICs. CR2-fH, but not CR2-Crry, also significantly reduced glomerulonephritis, expression of serum anti-double-stranded DNA (anti-dsDNA) antibodies, and glomerular IgG and C1q deposition. Interestingly, sCR2 also significantly reduced the levels of anti-dsDNA antibodies and circulating ICs and reduced glomerular deposition of IgG, C1q, and C3, although there was no significant reduction in glomerulonephritis, proteinuria, or mortality.

CONCLUSION

Targeted and selective inhibition of the alternative complement pathway is an effective treatment of murine lupus and is more effective than blockade of all pathways. The data demonstrate benefits to leaving the classical/lectin pathways intact and indicate distinct roles for the classical and alternative pathways of complement in disease progression. The sCR2-targeting vehicle contributes to therapeutic activity, possibly via modulation of autoimmunity.

Cell-bound complement biomarkers for systemic lupus erythematosus: from benchtop to bedside

Systemic lupus erythematosus is arguably the most clinically and serologically diverse autoimmune disease. This article highlights the biomarkers helpful in diagnosing this disease. The authors' own research is presented.

Dysregulated complement activation as a common pathway of injury in preeclampsia and other pregnancy complications

The complement system protects the host against invading organisms, initiates inflammation and dispose of immune complexes and the products of inflammatory injury. The complement system provides an important link between the innate and adaptive immune systems. Experimental observations suggest that increased complement activation causes and/or perpetuates inflammation during pregnancy. Recent studies suggest a link between complement activation and preeclampsia. Excessive activation or insufficient regulation of complement recruits leukocytes and unleashes potent inflammatory and anti-angiogenic mediators associated with placental insufficiency and maternal endothelial dysfunction characteristic of preeclampsia. We review the animal and human studies that link complement activation and pathogenic events in preeclampsia, present evidence that activation of the complement system is associated with the development of preeclampsia and provides new targets to prevent its complications.

Erythrocyte C3d and C4d for monitoring disease activity in systemic lupus erythematosus

OBJECTIVE

Disease activity in systemic lupus erythematosus (SLE) is typically monitored by measuring serum C3 and C4. However, these proteins have limited utility as lupus biomarkers, because they are substrates rather than products of complement activation. The aim of this study was to evaluate the utility of measuring the erythrocyte-bound complement activation products, erythrocyte-bound C3d (E-C3d) and E-C4d, compared with that of serum C3 and C4 for monitoring disease activity in patients with SLE.

METHODS

The levels of E-C3d and E-C4d were measured by flow cytometry in 157 patients with SLE, 290 patients with other diseases, and 256 healthy individuals. The patients with SLE were followed up longitudinally. Disease activity was measured at each visit, using the validated Systemic Lupus Activity Measure (SLAM) and the Safety of Estrogens in Lupus Erythematosus: National Assessment (SELENA) version of the Systemic Lupus Erythematosus Disease Activity Index (SLEDAI).

RESULTS

At baseline, patients with SLE had higher median levels of E-C3d and E-C4d (P < 0.0001) in addition to higher within-patient and between-patient variability in both E-C3d and E-C4d when compared with the 2 non-SLE groups. In a longitudinal analysis of patients with SLE, E-C3d, E-C4d, serum C3, and anti-double-stranded DNA (anti-dsDNA) antibodies were each significantly associated with the SLAM and SELENA-SLEDAI. In a multivariable analysis, E-C4d remained significantly associated with these SLE activity measures after adjusting for serum C3, C4, and anti-dsDNA antibodies; however, E-C3d was associated with the SLAM but not with the SELENA-SLEDAI.

CONCLUSION

Determining the levels of the erythrocyte-bound complement activation products, especially E-C4d, is an informative measure of SLE disease activity as compared with assessing serum C4 levels and should be considered for monitoring disease activity in patients with SLE.

The impact of flare on disease costs of patients with systemic lupus erythematosus

OBJECTIVE

To evaluate both direct and indirect costs of systemic lupus erythematosus (SLE) patients with and without flares from a societal perspective, and to investigate the impact of the severity and clinical manifestations of flares on direct/indirect costs.

METHODS

A retrospective cost-of-illness study was performed on 306 SLE patients. Participants completed questionnaires on sociodemographics, employment status, and out-of-pocket expenses. Health resources consumption was recorded by chart review and patient self-reported questionnaire. The total number of flares and involved organs during the preceding 12 months were recorded. Multiple linear regression was performed to determine the cost predictors.

RESULTS

Patients with flares were younger, had shorter disease duration, and had higher disease activity at the time of the assessment. The overall incidence of lupus flares was 0.24 episodes per patient-year. Patients with flares used more health care resources and incurred significantly higher annual direct and indirect costs. The mean total costs per patient-year were 2-fold higher for patients with flares ($22,580 versus $10,870 [2006 US dollars]; P < 0.0005). Multiple regression analysis showed that the number of flares was an independent explanatory variable associated with increased direct costs. Patients with multiorgan flares or renal/neuropsychiatric flares incurred higher direct costs compared with those with single-organ flares or with other organ flares.

CONCLUSION

Patients with flares incur higher direct and indirect costs compared with those without flares. Major organ flares incur higher disease costs than other organ flares. Treatments that effectively control disease activity and prevent flares, especially major organ flares, may reduce the high costs associated with flare in SLE.

Alteration of N-glycosylation in the kidney in a mouse model of systemic lupus erythematosus: relative quantification of N-glycans using an isotope-tagging method

Changes in the glycan structures of some glycoproteins have been observed in autoimmune diseases such as systemic lupus erythematosus (SLE) and rheumatoid arthritis. A deficiency of alpha-mannosidase II, which is associated with branching in N-glycans, has been found to induce SLE-like glomerular nephritis in a mouse model. These findings suggest that the alteration of the glycosylation has some link with the development of SLE. An analysis of glycan alteration in the disordered tissues in SLE may lead to the development of improved diagnostic methods and may help to clarify the carbohydrate-related pathogenic mechanism of inflammation in SLE. In this study, a comprehensive and differential analysis of N-glycans in kidneys from SLE-model mice and control mice was performed by using the quantitative glycan profiling method that we have developed previously. In this method, a mixture of deuterium-labelled N-glycans from the kidneys of SLE-model mice and non-labelled N-glycans from kidneys of control mice was analysed by liquid chromatography/mass spectrometry. It was revealed that the low-molecular-mass glycans with simple structures, including agalactobiantennary and paucimannose-type oligosaccharides, markedly increased in the SLE-model mouse. On the other hand, fucosylated and galactosylated complex type glycans with high branching were decreased in the SLE-model mouse. These results suggest that the changes occurring in the N-glycan synthesis pathway may cause the aberrant glycosylations on not only specific glycoproteins but also on most of the glycoproteins in the SLE-model mouse. The changes in glycosylation might be involved in autoimmune pathogenesis in the model mouse kidney.

The effect of moderate-dose corticosteroids in preventing severe flares in patients with serologically active, but clinically stable, systemic lupus erythematosus: findings of a prospective, randomized, double-blind, placebo-controlled trial

OBJECTIVE

Serial measurements of anti-double-stranded DNA (anti-dsDNA) and complement are routine in the management of systemic lupus erythematosus (SLE), but their utility as biomarkers in preemptive treatment to prevent flares remains a subject of controversy. We hypothesized that concomitant elevation of anti-dsDNA and C3a can predict SLE activity in patients with stable or inactive disease and that short-term treatment with corticosteroids can avert flares.

METHODS

In this prospective, randomized, double-blind, placebo-controlled trial, 154 patients were evaluated monthly for up to 18 months, with measurements of C3a, C3, C4, CH50, and anti-dsDNA levels. Patients who remained clinically stable but showed serologic evidence of an SLE flare (elevation of both the anti-dsDNA level by 25% and the C3a level by 50% over the previous 1-2 monthly visits) were randomized to receive either prednisone or placebo therapy at a dosage of 30 mg/day for 2 weeks, 20 mg/day for 1 week, and 10 mg/day for 1 week.

RESULTS

Forty-one patients (21 randomized to prednisone and 20 randomized to placebo) experienced a serologic flare. Analysis of severe flares occurring <or=90 days from randomization revealed that 6 occurred in patients taking placebo and none occurred in patients taking prednisone (P = 0.007). Severe flares resulted in an increase in the prednisone dosage to >40 mg/day and/or the addition of an immunosuppressive agent. Furthermore, improvement in scores on the Systemic Lupus Erythematosus Disease Activity Index, decreased levels of anti-dsDNA antibodies, and increased levels of C4 occurred 1 month after initiation of prednisone treatment.

CONCLUSION

These preliminary data support our hypothesis that in a subset of clinically stable SLE patients with a combination of elevated C3a and anti-dsDNA levels, short-term corticosteroid therapy may avert a severe flare.