Systemic lupus erythematosus: from genes to organ damage

The Role of the Oxidative State and Innate Immunity Mediated by TLR7 and TLR9 in Lupus Nephritis

Lupus nephritis (LN) is a severe complication of systemic lupus erythematosus (SLE) and is considered one of the leading causes of mortality. Multiple immunological pathways are involved in the pathogenesis of SLE, which makes it imperative to deepen our knowledge about this disease's immune-pathological complexity and explore new therapeutic targets. Since an altered redox state contributes to immune system dysregulation, this document briefly addresses the roles of oxidative stress (OS), oxidative DNA damage, antioxidant enzymes, mitochondrial function, and mitophagy in SLE and LN. Although adaptive immunity's participation in the development of autoimmunity is undeniable, increasing data emphasize the importance of innate immunity elements, particularly the Toll-like receptors (TLRs) that recognize nucleic acid ligands, in inflammatory and autoimmune diseases. Here, we discuss the intriguing roles of TLR7 and TLR9 in developing SLE and LN. Also included are the essential characteristics of conventional treatments and some other novel and little-explored alternatives that offer options to improve renal function in LN.

Germline immunomodulatory expression quantitative trait loci (ieQTLs) associated with immune-related toxicity from checkpoint inhibition

BACKGROUND

Immune checkpoint inhibition (ICI) has improved clinical outcomes for metastatic melanoma patients; however, 65-80% of patients treated with ICI experience immune-related adverse events (irAEs). Given the plausible link of irAEs with underlying host immunity, we explored whether germline genetic variants controlling the expression of 42 immunomodulatory genes were associated with the risk of irAEs in melanoma patients treated with the single-agent anti-CTLA-4 antibody ipilimumab (IPI).

METHODS

We identified 42 immunomodulatory expression quantitative trait loci (ieQTLs) most significantly associated with the expression of 382 immune-related genes. These germline variants were genotyped in IPI-treated melanoma patients, collected as part of a multi-institutional collaboration. We tested the association of ieQTLs with irAEs in a discovery cohort of 95 patients, followed by validation in an additional 97 patients.

RESULTS

We found that the alternate allele of rs7036417, a variant linked to increased expression of SYK, was strongly associated with an increased risk of grade 3-4 toxicity [odds ratio (OR) = 7.46; 95% confidence interval (CI) = 2.65-21.03; p = 1.43E-04]. This variant was not associated with response (OR = 0.90; 95% CI = 0.37-2.21; p = 0.82).

CONCLUSION

We report that rs7036417 is associated with increased risk of severe irAEs, independent of IPI efficacy. SYK plays an important role in B-cell/T-cell expansion, and increased pSYK has been reported in patients with autoimmune disease. The association between rs7036417 and IPI irAEs in our data suggests a role of SYK overexpression in irAE development. These findings support the hypothesis that inherited variation in immune-related pathways modulates ICI toxicity and suggests SYK as a possible future target for therapies to reduce irAEs.

The Role of Genetic Risk Factors in Pathogenesis of Childhood-Onset Systemic Lupus Erythematosus

The pathogenesis of childhood-onset systemic lupus erythematosus (cSLE) is complex and not fully understood. It involves three key factors: genetic risk factors, epigenetic mechanisms, and environmental triggers. Genetic factors play a significant role in the development of the disease, particularly in younger individuals. While cSLE has traditionally been considered a polygenic disease, it is now recognized that in rare cases, a single gene mutation can lead to the disease. Although these cases are uncommon, they provide valuable insights into the disease mechanism, enhance our understanding of pathogenesis and immune tolerance, and facilitate the development of targeted treatment strategies. This review aims to provide a comprehensive overview of both monogenic and polygenic SLE, emphasizing the implications of specific genes in disease pathogenesis. By conducting a thorough analysis of the genetic factors involved in SLE, we can improve our understanding of the underlying mechanisms of the disease. Furthermore, this knowledge may contribute to the identification of effective biomarkers and the selection of appropriate therapies for individuals with SLE.

Centrally acting ACE inhibitor (cACEi) and angiotensin receptor blocker (cARB) use and cognitive dysfunction in patients with SLE

OBJECTIVE

Cognitive dysfunction (CD) is detectable in approximately 40% of patients with SLE. Despite this high prevalence, there are no approved pharmacological treatment options for this detrimental condition. Preliminary murine studies show potential for targeting microglial activation as a treatment of SLE-CD, which may be ameliorated with centrally acting ACE inhibitor (cACEi) and angiotensin receptor blocker (cARB) use. The aim of this study is to determine if there is an association of cACEi/cARB use with cognitive function in a human SLE cohort.

METHODS

The American College of Rheumatology neuropsychological battery was administered to patients with consecutive SLE at a single academic health centre at baseline, 6 and 12 months. Scores were compared with sex-matched and age-matched control subjects. Clinical and demographic data were gathered at each visit. The primary outcome was CD defined as dysfunction in two or more cognitive domains. The primary predictor was a total cumulative dose of cACEi/cARB in milligrams per kilogram, recorded as an equivalent ramipril dose. Odds of CD with respect to cACEi/cARB use were determined through generalised linear mixed modelling.

RESULTS

A total of 300 patients, representing 676 visits, completed this study. One hundred sixteen (39%) met the criteria for CD. Fifty-three participants (18%) were treated with a cACEi or cARB. Mean cumulative dose was 236 mg/kg (calculated as equivalent ramipril dose). Cumulative cACEi/cARB dose was not protective against SLE-CD. Caucasian ethnicity, current employment status and azathioprine cumulative dose were each associated with reduced odds of SLE-CD. Increasing Fatigue Severity Scale score was associated with increased odds of CD.

CONCLUSIONS

In a single-centre SLE cohort, cACEi/cARB use was not associated with absence of CD. Many important confounders may have influenced the results of this retrospective study. A randomised trial is required to accurately determine if cACEi/cARB is a potential treatment for SLE-CD.

Urinary markers differentially associate with kidney inflammatory activity and chronicity measures in patients with lupus nephritis

OBJECTIVE

Lupus nephritis (LN) is diagnosed by biopsy, but longitudinal monitoring assessment methods are needed. Here, in this preliminary and hypothesis-generating study, we evaluate the potential for using urine proteomics as a non-invasive method to monitor disease activity and damage. Urinary biomarkers were identified and used to develop two novel algorithms that were used to predict LN activity and chronicity.

METHODS

Baseline urine samples were collected for four cohorts (healthy donors (HDs, n=18), LN (n=42), SLE (n=17) or non-LN kidney disease biopsy control (n=9)), and over 1 year for patients with LN (n=42). Baseline kidney biopsies were available for the LN (n=46) and biopsy control groups (n=9). High-throughput proteomics platforms were used to identify urinary analytes ≥1.5 SD from HD means, which were subjected to stepwise, univariate and multivariate logistic regression modelling to develop predictive algorithms for National Institutes of Health Activity Index (NIH-AI)/National Institutes of Health Chronicity Index (NIH-CI) scores. Kidney biopsies were analysed for macrophage and neutrophil markers using immunohistochemistry (IHC).

RESULTS

In total, 112 urine analytes were identified from LN, SLE and biopsy control patients as both quantifiable and overexpressed compared with HDs. Regression analysis identified proteins associated with the NIH-AI (n=30) and NIH-CI (n=26), with four analytes common to both groups, demonstrating a difference in the mechanisms associated with NIH-AI and NIH-CI. Pathway analysis of the NIH-AI and NIH-CI analytes identified granulocyte-associated and macrophage-associated pathways, and the presence of these cells was confirmed by IHC in kidney biopsies. Four markers each for the NIH-AI and NIH-CI were identified and used in the predictive algorithms. The NIH-AI algorithm sensitivity and specificity were both 93% with a false-positive rate (FPR) of 7%. The NIH-CI algorithm sensitivity was 88%, specificity 96% and FPR 4%. The accuracy for both models was 93%.

CONCLUSIONS

Longitudinal predictions suggested that patients with baseline NIH-AI scores of ≥8 were most sensitive to improvement over 6-12 months. Viable approaches such as this may enable the use of urine samples to monitor LN over time.

Methylation of TET2 Promoter Is Associated with Global Hypomethylation and Hypohydroxymethylation in Peripheral Blood Mononuclear Cells of Systemic Lupus Erythematosus Patients

(1) Background: It is widely accepted that aberrant methylation patterns contribute to the development of systemic lupus erythematosus (SLE). Ten-eleven translocation (TET) methylcytosine dioxygenase is an essential enzyme of which there are three members, TET1, 2, and 3, involved in hydroxymethylation, a newly uncovered mechanism of active DNA methylation. The epigenomes of gene transcription are regulated by 5-hydroxymethylcytocine (5-hmC) and TETs, leading to dysregulation of the immune system in SLE. The purpose of this study was to investigate the global hydroxymethylation status in SLE peripheral blood mononuclear cells (PBMCs) and to explore the role of TETs in changing the patterns of methylation. (2) Methods: We collected PBMCs from 101 SLE patients and 100 healthy donors. TaqMan real-time polymerase chain-reaction assay was performed for the detection of 5-methylcytosine (5-mC), 5-hmC, and TET2 mRNA expression and single-nucleotide polymorphism genotyping. The methylation rates in different CpG sites of TET2 promoters were examined using next-generation sequencing-based deep bisulfite sequencing. Putative transcription factors were investigated using the UCSC Genome Browser on the Human Dec. 2013 (GRCh38/hg38) Assembly. (3) Results: 5-mC and 5-hmC were both decreased in SLE. The mRNA expression level of TET2 was notably high and found to be correlated with the levels of immunologic biomarkers that are indicative of SLE disease activity. The analysis of methylation rates in the TET2 promoter revealed that SLE patients had significantly higher and lower rates of methylation in TET2 105146072-154 and TET2 105146218-331, respectively. (4) Conclusions: TET2 may play an important role in 5-mC/5-hmC dynamics in the PBMCs of SLE patients. The epigenetic modification of TET2 promoters could contribute to the pathogenesis of SLE and the intensity of the immunologic reaction.

Impact of Corticosteroids on the Proportions of Circulating Tfh Cell Subsets in Patients With Systemic Lupus Erythematous

Objectives

This study aimed to analyze the distribution of T follicular helper (Tfh) cells in lupus patients, and the effects of steroids on circulating Tfh cells.

Methods

Circulating Tfh cell subsets were defined by multicolor flow cytometry as Tfh17, Tfh2 or Tfh1 subpopulations of CXCR5⁺CD45RA^–CD4⁺ T cells in the peripheral blood of SLE patients and healthy controls. To test the effects of corticosteroid on Tfh cells, PBMC harvested from both SLE and healthy controls were cocultured with dexamethasone, and then analyzed by Flow cytometry.

Results

The proportion of Tfh17 cells in SLE patients was increased significantly compared with healthy controls. Additionally, patients with an active disease had reduced Tfh1 subsets than those with an inactive disease and healthy controls. The frequency of Tfh2 cells was associated with the proportion of circulating plasmablasts and the amount of anti-dsDNA. Dexamethasone reduced the percentage of Tfh2 cells while increased the proportion of Tfh17 subset in gated CXCR5⁺CD45RA^–CD4⁺ T cells.

Conclusion

Our study investigated the distribution of circulating Tfh subsets in lupus patients. Corticosteroids treatment not only down-regulated the proportion of circulating Tfh cells, but also altered the distribution of Tfh subsets in vivo and in vitro.

Clinical and radiological features of lung disorders related to connective-tissue diseases: a pictorial essay

Connective tissue diseases (CTDs) include a spectrum of disorders that affect the connective tissue of the human body; they include autoimmune disorders characterized by immune-mediated chronic inflammation and the development of fibrosis. Lung involvement can be misdiagnosed, since pulmonary alterations preceded osteo-articular manifestations only in 20% of cases and they have no clear clinical findings in the early phases. All pulmonary structures may be interested: pulmonary interstitium, airways, pleura and respiratory muscles. Among these autoimmune disorders, rheumatoid arthritis (RA) is characterized by usual interstitial pneumonia (UIP), pulmonary nodules and airway disease with air-trapping, whereas non-specific interstitial pneumonia (NSIP), pulmonary hypertension and esophageal dilatation are frequently revealed in systemic sclerosis (SSc). NSIP and organizing pneumonia (OP) may be found in patients having polymyositis (PM) and dermatomyositis (DM); in some cases, perilobular consolidations and reverse halo-sign areas may be observed. Systemic lupus erythematosus (SLE) is characterized by serositis, acute lupus pneumonitis and alveolar hemorrhage. In the Sjögren syndrome (SS), the most frequent pattern encountered on HRCT images is represented by NSIP; UIP and lymphocytic interstitial pneumonia (LIP) are reported with a lower frequency. Finally, fibrotic NSIP may be the interstitial disease observed in patients having mixed connective tissue diseases (MCTD). This pictorial review therefore aims to provide clinical features and imaging findings associated with autoimmune CTDs, in order to help radiologists, pneumologists and rheumatologists in their diagnoses and management.

Retrospective Analysis of Disease Severity, Health Care Resource Utilization, and Costs Among Patients Initiating Belimumab for the Treatment of Systemic Lupus Erythematosus

PURPOSE

The goal of this study was to evaluate clinical and economic outcomes associated with the initiation of intravenous (IV) belimumab for the treatment of systemic lupus erythematosus (SLE) in clinical practice in the United States.

METHODS

This retrospective study used administrative claims data from the IBM MarketScan Commercial Claims and Encounters Database and the Medicare Supplemental and Coordination of Benefits Database. Data for patients with SLE who initiated (index) IV belimumab were collected for the 12 months before (pre-index) and the 12 months after (post-index) belimumab initiation. Outcomes included SLE disease severity and flares, all-cause health care resource utilization (HCRU) and health care costs, and hospital-based costs and service visits. Post hoc analyses of total hospital-based costs were conducted to further explore drivers of mean post-index costs.

FINDINGS

Baseline characteristics (N = 908) are as follows: female, 93.4%; mean (SD) age, 45.6 (11.9) years; mean Charlson Comorbidity Index score, 0.9 (2.0); and moderate or severe disease, 94.9%. Disease activity (SLE flare episodes) was significantly reduced between the pre-index and post-index periods (severe flares, 16.4% vs 10.1% [P < 0.0001]; moderate flares, 92.1% vs 85.6% [P < 0.0001]; and mild flares, 77.4% vs 71.1%; [P = 0.0003]). The proportion of patients receiving oral corticosteroids (OCS) was reduced between the pre-index and post-index periods, especially among patients at higher OCS thresholds (prednisone-equivalent dose: ≥60 mg/d, 7.3% vs 4.2%; >40 mg/d, 14.1% vs 7.9%). From the pre-index to the post-index period, few differences in HCRU were observed, although all-cause physician office visits, outpatient visits, and unique prescriptions filled increased significantly. In the 12-month post-index period, patients had a mean of 12.2 (9.0) encounters (eg, outpatient visit or prescription) associated with IV belimumab. All-cause total, medical, and pharmacy costs increased from the pre-index to the post-index period. Mean all-cause hospital-based costs increased from the pre-index to the post-index period ($7735 [26,603] vs $11,030 [88,086]; P = 0.396). However, the 75th, 90th, and 95th percentile costs decreased from the pre-index to the post-index period ($305, $2107, and $3861, respectively).

IMPLICATIONS

After initiation of IV belimumab, disease activity (number of moderate and severe SLE flares) and use of OCS were significantly reduced. However, HCRU and costs, including hospital-based costs, were generally greater in the post-index period. Further studies will increase understanding of SLE, with the specific goals of incorporating disease activity measures and long-term outcomes in studies of HCRU, costs, and patient outcomes.

Can endolysosomal deacidification and inhibition of autophagy prevent severe COVID-19?

The possibility is examined that immunomodulatory pharmacotherapy may be clinically useful in managing the pandemic coronavirus disease 2019 (COVID-19), known to result from infection by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a positive-sense single-stranded RNA virus. The dominant route of cell entry of the coronavirus is via phagocytosis, with ensconcement in endosomes thereafter proceeding via the endosomal pathway, involving transfer from early (EEs) to late endosomes (LEs) and ultimately into lysosomes via endolysosomal fusion. EE to LE transportation is a rate-limiting step for coronaviruses. Hence inhibition or dysregulation of endosomal trafficking could potentially inhibit SARS-CoV-2 replication. Furthermore, the acidic luminal pH of the endolysosomal system is critical for the activity of numerous pH-sensitive hydrolytic enzymes. Golgi sub-compartments and Golgi-derived secretory vesicles also depend on being mildly acidic for optimal function and structure. Activation of endosomal toll-like receptors by viral RNA can upregulate inflammatory mediators and contribute to a systemic inflammatory cytokine storm, associated with a worsened clinical outcome in COVID-19. Such endosomal toll-like receptors could be inhibited by the use of pharmacological agents which increase endosomal pH, thereby reducing the activity of acid-dependent endosomal proteases required for their activity and/or assembly, leading to suppression of antigen-presenting cell activity, decreased autoantibody secretion, decreased nuclear factor-kappa B activity and decreased pro-inflammatory cytokine production. It is also noteworthy that SARS-CoV-2 inhibits autophagy, predisposing infected cells to apoptosis. It is therefore also suggested that further pharmacological inhibition of autophagy might encourage the apoptotic clearance of SARS-CoV-2-infected cells.

Head-to-head comparative pharmacokinetic and biodistribution (PK/BD) study of two dexamethasone prodrug nanomedicines on lupus-prone NZB/WF1 mice

HPMA copolymer-based dexamethasone prodrug (P-Dex) and PEG-based dexamethasone prodrug (PEG-Dex, ZSJ-0228) were previously found to passively target the inflamed kidney and provide potent and sustained resolution of nephritis in NZB/WF1 lupus-prone mice. While both prodrug nanomedicines effectively ameliorate lupus nephritis, they have demonstrated distinctively different safety profiles. To explore the underlining mechanisms of these differences, we conducted a head-to-head comparative PK/BD study of P-Dex and PEG-Dex on NZB/WF1 mice. Overall, the systemic organ/tissue exposures to P-Dex and Dex released from P-Dex were found to be significantly higher than those of PEG-Dex. The high prodrug concentrations were sustained in kidney for only 24 h, which cannot explain their lasting therapeutic efficacy (>1 month). P-Dex showed sustained presence in liver, spleen and adrenal gland, while the presence of PEG-Dex in these organs was transient. This difference in PK/BD profiles may explain PEG-Dex' superior safety than P-Dex.

Production of Autoreactive Heavy Chain-Only Antibodies in Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE) is characterized by the overproduction of high-affinity autoreactive antibodies. Here, we show that more than 65.8% of 222 recombinant antibodies derived from 8 SLE patients can be secreted as heavy chain-only antibodies (HCAbs) when expressed in HEK-293T cells. The secretion of HCAbs follows the conventional endoplasmic reticulum-Golgi apparatus pathway, despite triggering a weaker unfolded protein response (UPR). Many of the purified SLE HCAbs remain autoreactive and have an even higher affinity for dsDNA, Sm, nucleosome, and cardiolipin than HCAbs from healthy individuals. Extended analyses of the CDR3 region and the heavy chain variable (VH) region of HCAb F3 show that the VH region is responsible for IgH secretion, while the CDR3 region determines its reactivity. Such a high frequency of HCAb secretion cannot fully concur with our current understanding of antibody assembly and secretion. The presence of a large proportion of autoreactive HCAbs in SLE reveals a novel mechanism for the generation of autoreactive antibodies in lupus.

A clinical population pharmacokinetic/pharmacodynamic model for BIIB059, a monoclonal antibody for the treatment of systemic and cutaneous lupus erythematosus

A population pharmacokinetic/pharmacodynamic (popPK/PD) model for BIIB059 (anti-blood dendritic cell antigen 2 [anti-BDCA2]), a humanized immunoglobulin G1 monoclonal antibody currently under development for the treatment of SLE and CLE, is presented. BIIB059 binds BDCA2, a plasmacytoid dendritic cell (pDC)-specific receptor that inhibits the production of IFN-I and other inflammatory mediators when ligated. Phase 1 PK and PD data of healthy adult volunteers (HV, n = 87) and SLE subjects (n = 22) were utilized for the development of the popPK/PD model. The data included single and multiple dosing of intravenous and subcutaneous BIIB059. BDCA2 internalization (PD marker) was measured for all subjects by monitoring reduction of BDCA2 on pDC cell surface and used for development of the popPD model. A two-compartment popPK model with linear plus non-linear elimination was found to best describe BIIB059 PK. BDCA2 levels were best captured using an indirect response model with stimulation of the elimination of BDCA2. Clearance in SLE subjects was 25% higher compared to HV (6.87 vs 5.52 mL/h). Bodyweight was identified as only other covariate on clearance and central volume. The estimates of EC₅₀ and E_max were 0.35 μg/mL and 8.92, respectively. No difference in EC₅₀ and E_max was observed between SLE and HV. The popPK/PD model described the data accurately, as evaluated by pcVPCs and bootstrap. The presented popPK/PD model for BIIB059 provides valuable insight into the dynamics and dose-response relationship of BIIB059 for the treatment of SLE and CLE and was used to guide dose selection for the Phase 2 clinical study (NCT02847598).

Cellular Stress and General Pathological Processes

From the viewpoint of the general pathology, most of the human diseases are associated with a limited number of pathogenic processes such as inflammation, tumor growth, thrombosis, necrosis, fibrosis, atrophy, pathological hypertrophy, dysplasia and metaplasia. The phenomenon of chronic low-grade inflammation could be attributed to non-classical forms of inflammation, which include many neurodegenerative processes, pathological variants of insulin resistance, atherosclerosis, and other manifestations of the endothelial dysfunction. Individual and universal manifestations of cellular stress could be considered as a basic element of all these pathologies, which has both physiological and pathophysiological significance. The review examines the causes, main phenomena, developmental directions and outcomes of cellular stress using a phylogenetically conservative set of genes and their activation pathways, as well as tissue stress and its role in inflammatory and para-inflammatory processes. The main ways towards the realization of cellular stress and its functional blocks were outlined. The main stages of tissue stress and the classification of its typical manifestations, as well as its participation in the development of the classical and non-classical variants of the inflammatory process, were also described. The mechanisms of cellular and tissue stress are structured into the complex systems, which include networks that enable the exchange of information with multidirectional signaling pathways which together make these systems internally contradictory, and the result of their effects is often unpredictable. However, the possible solutions require new theoretical and methodological approaches, one of which includes the transition to integral criteria, which plausibly reflect the holistic image of these processes.

Long-term safety and limited organ damage in patients with systemic lupus erythematosus treated with belimumab: a Phase III study extension

OBJECTIVE

This extension study of the Phase III, randomized, placebo-controlled Belimumab International SLE Study (BLISS)-52 and BLISS-76 studies allowed non-US patients with SLE to continue belimumab treatment, in order to evaluate its long-term safety and tolerability including organ damage accrual.

METHODS

In this multicentre, long-term extension study (GlaxoSmithKline Study BEL112234) patients received i.v. belimumab every 4 weeks plus standard therapy. Adverse events (AEs) were assessed monthly and safety-associated laboratory parameters were assessed at regular intervals. Organ damage (SLICC/ACR Damage Index) was assessed every 48 weeks. The study continued until belimumab was commercially available, with a subsequent 8-week follow-up period.

RESULTS

A total of 738 patients entered the extension study and 735/738 (99.6%) received one or more doses of belimumab. Annual incidence of AEs, including serious and severe AEs, remained stable or declined over time. Sixty-nine (9.4%) patients experienced an AE resulting in discontinuation of belimumab or withdrawal from the study. Eleven deaths occurred (and two during post-treatment follow-up), including one (cardiogenic shock) considered possibly related to belimumab. Laboratory parameters generally remained stable. The mean (s.d.) SLICC/ACR Damage Index score was 0.6 (1.02) at baseline (prior to the first dose of belimumab) and remained stable. At study year 8, 57/65 (87.7%) patients had no change in SLICC/ACR Damage Index score from baseline, indicating low organ damage accrual.

CONCLUSION

Belimumab displayed a stable safety profile with no new safety signals. There was minimal organ damage progression over 8 years.

TRIAL REGISTRATION

ClinicalTrials.gov, https://clinicaltrials.gov, NCT00424476 (BLISS-52), NCT00410384 (BLISS-76), NCT00732940 (BEL112232), NCT00712933 (BEL112234).

Coordinated Induction of Antimicrobial Response Factors in Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease characterized by dysregulated autoantibody production and complement activation leading to multi-organ damage. The disease is associated with increased intestinal permeability. In this study, we tested the hypothesis that SLE subjects have increased systemic exposure to bacteria. Since bacteria induce the expression of antimicrobial response factors (ARFs), we measured the levels of a series of clinically relevant ARFs in the plasma of SLE subjects. We found that levels of sCD14, lysozyme, and CXCL16 were significantly elevated in SLE subjects. A strong positive correlation was also observed between sCD14 and SELENA-SLEDAI score. Interestingly, the ratio of EndoCAb IgM:total IgM was significantly decreased in SLE and this ratio was negatively correlated with sCD14 levels. Although, there were no significant differences in the levels of lipopolysaccharide binding protein (LBP) and fatty acid binding protein 2 (FABP2), we observed significant positive correlations between lysozyme levels and sCD14, LBP, and FABP2. Moreover, galectin-3 levels also positively correlate with lysozyme, sCD14, and LBP. Since our SLE cohort comprised 43.33% males, we were able to identify gender-specific changes in the levels of ARFs. Overall, these changes in the levels and relationships between ARFs link microbial exposure and SLE. Approaches to reduce microbial exposure or to improve barrier function may provide therapeutic strategies for SLE patients.

Long-Term Safety and Efficacy of Belimumab in Patients With Systemic Lupus Erythematosus: A Continuation of a Seventy-Six-Week Phase III Parent Study in the United States

OBJECTIVE

We undertook this US multicenter continuation study (GlaxoSmithKline study BEL112233; ClinicalTrials.gov identifier: NCT00724867) to assess long-term safety and efficacy of belimumab in patients with systemic lupus erythematosus (SLE) who completed the Study of Belimumab in Subjects with SLE 76-week trial (ClinicalTrials.gov identifier: NCT00410384).

METHODS

Patients continued to receive the same belimumab dose plus standard therapy; patients previously receiving placebo received 10 mg/kg belimumab. The primary outcome measure was long-term safety of belimumab (frequency of adverse events [AEs] and damage assessed using the Systemic Lupus International Collaborating Clinics/American College of Rheumatology Damage Index [SDI], evaluated every 48 weeks [1 study year]). Other assessments included the SLE Responder Index (SRI), flare rates (using the modified SLE Flare Index [SFI]), prednisone use, and B cell levels.

RESULTS

Of 268 patients, 140 completed the study and 128 withdrew. The mean ± SD score on the Safety of Estrogens in Lupus Erythematosus National Assessment version of the SLE Disease Activity Index (SELENA-SLEDAI) at baseline was 7.8 ± 3.86. The mean ± SD SDI score increased by 0.4 ± 0.68 from its value at baseline (1.2 ± 1.51). The overall incidence of treatment-related and serious AEs remained stable or declined through study year 7. An SRI response was achieved by 41.9% and 75.6% of patients at the study year 1 and study year 7 midpoints, respectively. At the study year 7 midpoint, relative to baseline, 78.2% had achieved a ≥4-point reduction in the SELENA-SLEDAI score, 98.4% had no new British Isles Lupus Assessment Group (BILAG) A organ domain score and no more than 1 new BILAG B organ domain score, 93.7% had no worsening in the physician's global assessment of disease activity, 20.6% had experienced ≥1 severe SFI flare, the mean decrease in prednisone dose was 31.4%, and the median change in CD20+ B cell numbers was -83.2%.

CONCLUSION

These long-term exposure results confirm the previously observed safety and efficacy profiles of belimumab in patients with SLE.

Transcriptomic profiling in human mesangial cells using patient-derived lupus autoantibodies identified miR-10a as a potential regulator of IL8

Autoantibody-mediated inflammation directed at resident kidney cells mediates lupus nephritis (LN) pathogenesis. This study investigated the role of miRNA in human mesangial cells (HMCs) stimulated with auto anti-dsDNA immunoglobulin (Ig)G antibodies. HMCs were treated with antibodies purified from active LN patients or non-specific IgG controls in the presence of normal serum. Aberrant miRNA was screened using high throughput sequencing. Anti-dsDNA IgG up-regulated 103 miRNAs and down-regulated 30 miRNAs. The miRNAs regulated genes in the cell cycle, catabolic processes, regulation of transcription and apoptosis signalling. miR-10a was highly abundant in HMCs but was specifically downregulated upon anti-dsDNA IgG induction. Interestingly, the expression of miR-10a in kidney biopsies from class III and IV LN patients (n = 26) was downregulated compared with cadaveric donor kidneys (n = 6). Functional studies highlighted the downstream regulator of miR-10a in the chemokine signalling and cell proliferation or apoptosis pathways. Luciferase assay confirmed for the first time that IL8 was a direct target of miR-10a in HMCs. In conclusion, anti-dsDNA IgG Ab down-regulated miR-10a expression in HMCs resulting in the induction of various target genes involved in HMC proliferation and chemokine expression.

CXCL13 Promotes Proliferation of Mesangial Cells by Combination with CXCR5 in SLE

As a CXC subtype member of the chemokine superfamily, CXCL13 is considered to be involved in systemic lupus erythematosus (SLE), especially in lupus nephritis (LN). To determine the effect of CXCL13 on SLE and explore the potential mechanisms, we tested serum concentrations of CXCL13 in patients and healthy individuals and found that CXCL13 expression was high in SLE patients especially in LN patients. When we treated human renal mesangial cells (HRMCs) in vitro with recombinant human CXCL13, the cell proliferation was accelerated, which was tested by Cell Counting Kit-8 assay and flow cytometry. Western blot and immunofluorescence assay revealed that CXCL13 would lead to phosphorylation of extracellular signal-regulated kinase 1/2 (ERK1/2). However, the effect was weakened after the silence of CXCR5. The results of our study elaborated that high expression of CXCL13 could be involved in the pathogenesis of LN.

Increased IL-17 and IL-21 producing TCRαβ+CD4−CD8− T cells in Chinese systemic lupus erythematosus patients

Background: Increased numbers of TCRαβ+CD4−CD8− T cells in the peripheral blood of systemic lupus erythematosus (SLE) patients in the United States and United Kingdom have been reported. However, the proportions of TCRαβ+CD4−CD8− T cells and their involvement in the pathogenesis of SLE in Chinese populations are yet to be determined. Methods: A total of 120 SLE patients, 38 rheumatoid arthritis (RA) patients and 43 normal control subjects were examined. The proportion of TCRαβ+CD4−CD8− T cells in the peripheral blood, Fas expression on these cells, and intracellular cytokine levels in these cells were assessed using flow cytometry. Plasma cytokine concentrations were measured using enzyme-linked immunosorbent assay. Results: The percentages of TCRαβ+CD4−CD8− T cells were increased in Chinese SLE patients, particularly in active SLE patients, correlated with decreased Fas expression on these cells. IL-17 and IL-21 levels in the blood and in TCRαβ+CD4−CD8− T cells from SLE patients were increased. Moreover, a positive correlation was evident between IL-17- and IL-21-producing TCRαβ+CD4−CD8− T cells. Conclusions: Increased TCRαβ+CD4−CD8− T cells expressing inflammatory cytokines, such as IL-17 and IL-21, may be implicated in the pathogenesis of SLE in patients. Appropriate IL-17- and/or IL-21 blockage may be utilized as a novel immunotherapeutic strategy for SLE patients.

Spleen tyrosine kinase (Syk) regulates systemic lupus erythematosus (SLE) T cell signaling

Engagement of the CD3/T cell receptor complex in systemic lupus erythematosus (SLE) T cells involves Syk rather than the zeta-associated protein. Because Syk is being considered as a therapeutic target we asked whether Syk is central to the multiple aberrantly modulated molecules in SLE T cells. Using a gene expression array, we demonstrate that forced expression of Syk in normal T cells reproduces most of the aberrantly expressed molecules whereas silencing of Syk in SLE T cells normalizes the expression of most abnormally expressed molecules. Protein along with gene expression modulation for select molecules was confirmed. Specifically, levels of cytokine IL-21, cell surface receptor CD44, and intracellular molecules PP2A and OAS2 increased following Syk overexpression in normal T cells and decreased after Syk silencing in SLE T cells. Our results demonstrate that levels of Syk affect the expression of a number of enzymes, cytokines and receptors that play a key role in the development of disease pathogenesis in SLE and provide support for therapeutic targeting in SLE patients.

FYB gene polymorphisms are associated with susceptibility for systemic lupus erythemathosus (SLE)

Systemic Lupus Erythematosus (SLE) is a multifactorial autoimmune disease affecting different organs or systems. Several genes have been associated with SLE susceptibility so far. A previous study has reported, in SLE patients, a differential expression of Fyn Binding Protein gene (FYB), encoding for a protein participating in the T cells signaling cascade and in the interleukin-2A expression modulation. This study investigates the association of 10 FYB SNPs with differential susceptibility to SLE in 143 SLE patients and 184 controls from Southern Brazil. Significant differences were observed when comparing allele and genotype frequencies distribution in patients and controls: the T allele for rs6863066 C>T SNP and C for rs358501 T>C SNP were significantly more frequent in SLE patients than in controls (p=0.0002 and p=0.008) and associated with an increased risk for SLE (OR=1.93 and OR=1.69). The frequencies of rs6863066 C/T and T/T and rs358501 C/C genotypes were significantly higher in patients than in controls (p=0.001, p=0.006 and p=0.008). A significant association was also found for the rs6863066-rs358501 T-T and T-C haplotypes (OR=2.06, p=0.002 and OR=2.93, p=0.001). When considering clinical and laboratorial manifestations, an association was found between rs2161612 G allele and G/G genotype and hematological alterations (p=0.008) and rs379707 A/C genotype and anti-dsDNA (p=0.01). In conclusion, our findings indicate an association between polymorphisms located in FYB gene and SLE, suggesting their possible involvement in disease susceptibility and clinical manifestations.

A diverse array of genetic factors contribute to the pathogenesis of systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a chronic systemic autoimmune disease with variable clinical presentation frequently affecting the skin, joints, haemopoietic system, kidneys, lungs and central nervous system. It can be life threatening when major organs are involved. The full pathological and genetic mechanisms of this complex disease are yet to be elucidated; although roles have been described for environmental triggers such as sunlight, drugs and chemicals, and infectious agents. Cellular processes such as inefficient clearing of apoptotic DNA fragments and generation of autoantibodies have been implicated in disease progression. A diverse array of disease-associated genes and microRNA regulatory molecules that are dysregulated through polymorphism and copy number variation have also been identified; and an effect of ethnicity on susceptibility has been described.