Fifty years of anti-ds DNA antibodies: are we approaching journey's end?

Is systemic lupus erythematosus linked to Immunoglobulin G4 Autoantibodies?

Systemic lupus erythematosus (SLE) is a systemic autoimmune disorder characterized by a hyperactive immune system with multiple abnormalities in B-cell proliferation, antibody production, T-cell regulation, and immune complex (IC) formation. In humans, Immunoglobulin (Ig) G is found in four subclasses. IgG1-IgG4, which are distinguished by both structural and biological differences. Fab-arm Exchange (FAE), specific biases in the IgG4 response repertoire, and a decreased capacity to induce effector functions mediated by interactions in the fragment crystallizable (Fc) region are just a few of the distinctive characteristics of IgG4. The recent finding of the presence of double-stranded DNA (dsDNA) and antinuclear antibody (ANA)-IgG4 has raised attention to this IgG subclass and its possible role in SLE. IgG4 was previously believed to just have anti-inflammatory effects by inhibiting immune responses, but recent studies have shown that these antibodies can also play a role in the onset and development of some clinical disorders. To consider the clinical effects of IgG4 presence, it is necessary to discuss its characteristics, which could underlie the potential role it can play in SLE. Therefore, this study aimed to comprehensively review the role of IgG4 in SLE to elucidate the collective incidence of high IgG4 levels reported in some SLE patients.

Inhibition of miRNA associated with a disease-specific signature and secreted via extracellular vesicles of systemic lupus erythematosus patients suppresses target organ inflammation in a humanized mouse model

Introduction

Distinct, disease-associated intracellular miRNA (miR) expression profiles have been observed in peripheral blood mononuclear cells (PBMCs) of systemic lupus erythematous (SLE) patients. Additionally, we have identified novel estrogenic responses in PBMCs from SLE patients and demonstrated that estrogen upregulates toll-like receptor (TLR)7 and TLR8 expression. TLR7 and TLR8 bind viral-derived single-stranded RNA to stimulate innate inflammatory responses, but recent studies have shown that miR-21, mir-29a, and miR-29b can also bind and activate these receptors when packaged and secreted in extracellular vesicles (EVs). The objective of this study was to evaluate the association of EV-encapsulated small RNA species in SLE and examine the therapeutic approach of miR inhibition in humanized mice.

Methods

Plasma-derived EVs were isolated from SLE patients and quantified. RNA was then isolated and bulk RNA-sequencing reads were analyzed. Also, PBMCs from active SLE patients were injected into immunodeficient mice to produce chimeras. Prior to transfer, the PBMCs were incubated with liposomal EVs containing locked nucleic acid (LNA) antagonists to miR-21, mir-29a, and miR-29b. After three weeks, blood was collected for both immunophenotyping and cytokine analysis; tissue was harvested for histopathological examination.

Results

EVs were significantly increased in the plasma of SLE patients and differentially expressed EV-derived small RNA profiles were detected compared to healthy controls, including miR-21, mir-29a, and miR-29b. LNA antagonists significantly reduced proinflammatory cytokines and histopathological infiltrates in the small intestine, liver, and kidney, as demonstrated by H&E-stained tissue sections and immunohistochemistry measuring human CD3.

Discussion

These data demonstrate distinct EV-derived small RNA signatures representing SLE-associated biomarkers. Moreover, targeting upregulated EV-encapsulated miR signaling by antagonizing miRs that may bind to TLR7 and TLR8 reveals a novel therapeutic opportunity to suppress autoimmune-mediated inflammation and pathogenesis in SLE.

Clinical management of lupus in the United States: A claims-based analysis

OBJECTIVES

To understand the evaluation and management of patients coded with lupus in the broad clinical community in the United States.

METHODS

Claims data for diagnoses, procedures, medications, and physician specialties were evaluated for three lupus cohorts [lupus nephritis (LN), systemic lupus erythematosus excluding LN (SLE), and cutaneous lupus erythematosus excluding SLE and LN (CLE)] using the EVERSANA claims databases. Identification of patients was based upon the occurrence of lupus-specific codes, with the requirement that a single patient receive a lupus-related ICD code twice within a six-month period.

RESULTS

Using ICD codes, we were able to identify 28,372 patients coded with LN, 82,744 patients coded with SLE, and 13,920 patients coded with CLE, and subsequently evaluate the journey of patients in each group in the year before and after being coded as having a diagnosis of lupus. For the three lupus cohorts, the basis of diagnosis was not always apparent, as clinical features of lupus were not often obtained, autoantibody testing was not usual, biopsies were uncommon and subspecialty involvement was not routine. In addition, a significant increase in laboratory testing, non-lupus diagnoses, emergency department visits and cost during the year before receiving a lupus code suggested uncertainty in disease recognition. Nevertheless, these patients received two separate lupus coding events within a six-month period, supporting a sustained or repeated diagnosis of lupus by the evaluating clinicians. When compared, the three lupus cohorts differed with regard to frequency of laboratory testing, subspecialty care, skin and renal biopsies, and medication management. Moreover, there was an increase in the cost of care of patients coded with lupus compared to a reference patient population both during the year before and after being coded with a diagnosis of lupus.

CONCLUSION

The data present a comprehensive report of the care of patients coded as having a diagnosis of lupus in the United States, including those outside of specialty centers. Despite the unclear basis of diagnosis in some patients, evaluation and management of patients coded as having a diagnosis of lupus in the general care community does not closely follow the recommended guidelines set forth by professional societies.

STATs signaling pathways in dendritic cells: As potential therapeutic targets?

Dendritic cells (DCs) are professional antigen-presenting cells (APCs), including heterogenous populations with phenotypic and functional diversity that coordinate bridging innate and adaptive immunity. Signal transducer and activator of transcriptions (STAT) factors as key proteins in cytokine signaling were shown to play distinct roles in the maturation and antigen presentation of DCs and play a pivotal role in modulating immune responses mediated by DCs such as differentiation of T cells to T helper (Th) 1, Th2 or regulatory T (Treg) cells. This review sheds light on the importance of STAT transcription factors' signaling pathways in different subtypes of DCs and highlights their targeting potential usages for improving DC-based immunotherapies for patients who suffer from cancer or diverse autoimmune conditions according to the type of the STAT transcription factor and its specific activating or inhibitory agent.

Histone-Specific CD4+ T Cell Plasticity in Active and Quiescent Systemic Lupus Erythematosus

OBJECTIVE

The aim of this study was to assess whether circulating histone-specific T cells represent tools for precision medicine in systemic lupus erythematosus (SLE).

METHODS

Seroprevalence of autoantibodies and HLA-DR beta (DRB) 1 profile were assessed among 185 patients with SLE and combined with bioinformatics and literature evidence to identify HLA-peptide autoepitope couples for ex vivo detection of antigen-specific T cells through flow cytometry. T cell differentiation and polarization was investigated in patients with SLE, patients with Takayasu arteritis, and healthy controls carrying HLA-DRB1*03:01 and/or HLA-DRB1*11:01. SLE Disease Activity Index 2000 and Lupus Low Disease Activity State were used to estimate disease activity and remission.

RESULTS

Histone-specific CD4+ T cells were selectively detected in patients with SLE. Among patients with a history of anti-DNA antibodies, 77% had detectable histone-specific T cells, whereas 50% had lymphocytes releasing cytokines or upregulating activation markers after in vitro challenge with histone peptide antigens. Histone-specific regulatory and effector T helper (Th) 1-, Th2-, and atypical Th1/Th17 (Th1*)-polarized cells were significantly more abundant in patients with SLE with quiescent disease. In contrast, total Th1-, Th2-, and Th1*-polarized and regulatory T cells were similarly represented between patients and controls or patients with SLE with active versus quiescent disease. Histone-specific effector memory T cells accumulated in the blood of patients with quiescent SLE, whereas total effector memory T cell counts did not change. Immunosuppressants were associated with expanded CD4+ histone-specific naive T (TN) and terminally differentiated T cells.

CONCLUSION

Histone-specific T cells are selectively detected in patients with SLE, and their concentration in the blood varies with disease activity, suggesting that they represent innovative tools for patient stratification and therapy.

Duplex Vertical-Flow Rapid Tests for Point-of-Care Detection of Anti-dsDNA and Anti-Nuclear Autoantibodies

The goal of this study is to develop a rapid diagnostic test for rheumatic disease and systemic lupus erythematosus (SLE) screening. A novel rapid vertical flow assay (VFA) was engineered and used to assay anti-nuclear (ANA) and anti-dsDNA (αDNA) autoantibodies from systemic lupus erythematosus (SLE) patients and healthy controls (HCs). Observer scores and absolute signal intensities from the VFA were validated via ELISA. The rapid point-of-care VFA test that was engineered demonstrated a limit of detection of 0.5 IU/mL for ANA and αDNA autoantibodies in human plasma with an inter-operator CV of 19% for ANA and 12% for αDNA. Storage stability was verified over a three-month period. When testing anti-dsDNA and ANA levels in SLE and HC serum samples, the duplex VFA revealed 95% sensitivity, 72% specificity and an 84% ROC AUC value in discriminating disease groups, comparable to the gold standard, ELISA. The rapid αDNA/ANA duplex VFA can potentially be used in primary care clinics for evaluating patients or at-risk subjects for rheumatic diseases and for planning follow-up testing. Given its low cost, ease, and rapid turnaround, it can also be used to assess SLE prevalence estimates.

Clinical algorithm model based on cfDNA to predict SLE disease activity

BACKGROUND

Circulating cell-free DNA (cfDNA) has been widely used as a new liquid-biopsy marker. Dysregulation of cfDNA has been found in patients with systemic lupus erythematosus (SLE). However, the detailed association between cfDNA and SLE has not been thoroughly studied.

METHODS

Plasma samples were collected from 88 patients with active SLE and 39 patients with inactive SLE. The cfDNA concentration was determined, and the length and distribution of cfDNA fragments were verified.

RESULTS

cfDNA concentrations were significantly higher in patients with active SLE than in patients with inactive SLE (0.4 [0.18-0.897] ng/µL vs 0.249 [0.144-0.431] ng/µL; p = .043). cfDNA fragments were enriched in the ranges of 153-198 bp and 300-599 bp. cfDNA concentrations were associated with the reduction of the anti-double-stranded DNA (dsDNA) antibodies titer (r = -0.301, p = .034). The presence of anti-U1 ribonucleoprotein (p = .012), anti-Sjogren syndrome A (p = .024), anti-dsDNA (p = .0208), and anti-nucleosome antibodies (p = .0382) might associate to the variation of cfDNA concentration. Reduced cfDNA concentration was associated with renal damage in active SLE patients (0.31 [0.11-0.73] ng/µL vs 0.65 [0.27-1.53] ng/µL; p = .009). The Active index, a combination model including cfDNA concentration and other clinical indices, had an area of 0.886 under the receiver operating characteristics curve for distinguishing active SLE. The Active index was positively correlated with the SLE disease activity index score (r = 0.6724, p < .0001).

CONCLUSIONS

Through systematic stratified analysis and clinical algorithm model, this study found that plasma cfDNA concentration is closely related to SLE disease severity, which has guiding significance for the future clinical application of cfDNA in SLE.

SMART-SLE: serology monitoring and repeat testing in systemic lupus erythematosus-an analysis of anti-double-stranded DNA monitoring

OBJECTIVE

Disease activity monitoring in SLE includes serial measurement of anti-double stranded-DNA (dsDNA) antibodies, but in patients who are persistently anti-dsDNA positive, the utility of repeated measurement is unclear. We investigated the usefulness of serial anti-dsDNA testing in predicting flare in SLE patients who are persistently anti-dsDNA positive.

METHODS

Data were analysed from patients in a multinational longitudinal cohort with known anti-dsDNA results from 2013 to 2021. Patients were categorized based on their anti-dsDNA results as persistently negative, fluctuating or persistently positive. Cox regression models were used to examine longitudinal associations of anti-dsDNA results with flare.

RESULTS

Data from 37 582 visits of 3484 patients were analysed. Of the patients 1029 (29.5%) had persistently positive anti-dsDNA and 1195 (34.3%) had fluctuating results. Anti-dsDNA expressed as a ratio to the normal cut-off was associated with the risk of subsequent flare, including in the persistently positive cohort (adjusted hazard ratio [HR] 1.56; 95% CI: 1.30, 1.87; P < 0.001) and fluctuating cohort (adjusted HR 1.46; 95% CI: 1.28, 1.66), both for a ratio >3. Both increases and decreases in anti-dsDNA more than 2-fold compared with the previous visit were associated with increased risk of flare in the fluctuating cohort (adjusted HR 1.33; 95% CI: 1.08, 1.65; P = 0.008) and the persistently positive cohort (adjusted HR 1.36; 95% CI: 1.08, 1.71; P = 0.009).

CONCLUSION

Absolute value and change in anti-dsDNA titres predict flares, including in persistently anti-dsDNA positive patients. This indicates that repeat monitoring of dsDNA has value in routine testing.

Hal Holman of Stanford

Before age 35, Holman hit over 0.500 at the University of California Los Angeles (UCLA); was recruited by professional baseball; led the Association of Interns and Medical Students and the International Union of Students in Denmark; had his passport confiscated; was stripped of a prestigious internship; shadowed by the Federal Bureau of Investigation ; grilled before a Senate committee on subversive activities; made a major medical discovery; and was recruited to be the new Chief of Medicine at Stanford. Holman was involved in building a leading academic institution. He expanded what medical students and graduates learned and what they researched. Holman saw the collision course between the technological capacity to do more and the growing expectations of the public. Moreover, he anticipated the monetization of health care and how it would widen the gap between what we know and what we practice in health care. He reinvented himself in population health. In contrast to reductionist laboratory-based research, his work embraced complexity and made action researchable and research action-oriented. Some innovations did not survive as originally conceived, but their ethos became mainstream. These included evidence-based management, shared physician-patient decision-making, self-management, critical evaluation of medical technology and diagnostics, and chronic disease management. Through the rise of the twentieth century American biomedical medicine, medical education, and slow-motion health care delivery crises that still occur, Holman changed the debate in a time when the funding, the people, the technology, and the need made all things seem possible.

Association of urine autoantibodies with disease activity in systemic lupus erythematosus

Objective

The presence of urinary autoantibodies in patients with systemic lupus erythematosus (SLE) has been confirmed by several studies; however, the significance of their presence in urine remains unclear. This study aims to further investigate the association between urine autoantibodies and disease activity as well as organ involvement in SLE.

Methods

This cross-sectional study included 89 SLE patients. Data collected included anti-nuclear antibody (ANA), anti-ENA antibodies, and anti-dsDNA antibody levels in both serum and urine, complement (C) 3, C4 levels in serum, SLE disease activity index-2000 (SLEDAI-2000), renal domains of SLEDAI (RSLEDAI) and non-renal SLEDAI (NRSLEDAI).

Results

The rate of positive urine ANA (uANA) was 33.3% (29/87) among the enrolled patients. Compared to the uANA negative group, the positive group exhibited significantly higher SLEDAI-2000 scores (7.85 ± 5.88 vs. 18.69 ± 6.93, p < 0.001), RSLEDAI scores [0 (0, 4.0) vs. 12.0 (8.0, 16.0), p < 0.001], and NRSLEDAI [4 (2.0, 8.0) vs. 6.0 (4.0, 9.5), p = 0.038]. Patients with positive urine anti-Sm antibody demonstrated significantly elevated SLEDAI-2000 scores compared to those who were negative (25.0 ± 8.80 vs. 10.09 ± 6.63, p < 0.001). Similarly, they also had higher RSLEDAI [16.0 (12.0, 16.0) vs. 4.0 (0, 8.0), p < 0.001] and NRSLEDAI [9.5 (6.0, 13.5) vs. 4.0 (3.0, 8.0), p = 0.012], as well as a greater prevalence of renal involvement compared to their negative counterparts (100% vs. 58.2, p = 0.022). There was a positive correlation between uANA titer and both SLEDAI-2000 (rs = 0.663, p < 0.001) and RSLEDAI (rs = 0.662, p < 0.001). The serum anti-dsDNA antibody level did not exhibit a significant correlation with RSLEDAI (rs = 0.143, p = 0.182). Conversely, the urine anti-dsDNA antibody level demonstrated a significant positive correlation with RSLEDAI (rs = 0.529, p < 0.001).

Conclusion

Urine ANA is associated with both global SLEDAI and RSLEDAI scores. Urine anti-Sm antibody is associated with an increased incidence of renal involvement in SLE. The urine anti-dsDNA antibody level, rather than the serum anti-dsDNA antibody level, exhibits a significant association with RSLEDAI in SLE.

Priming agents transiently reduce the clearance of cell-free DNA to improve liquid biopsies

Liquid biopsies enable early detection and monitoring of diseases such as cancer, but their sensitivity remains limited by the scarcity of analytes such as cell-free DNA (cfDNA) in blood. Improvements to sensitivity have primarily relied on enhancing sequencing technology ex vivo. We sought to transiently augment the level of circulating tumor DNA (ctDNA) in a blood draw by attenuating its clearance in vivo. We report two intravenous priming agents given 1 to 2 hours before a blood draw to recover more ctDNA. Our priming agents consist of nanoparticles that act on the cells responsible for cfDNA clearance and DNA-binding antibodies that protect cfDNA. In tumor-bearing mice, they greatly increase the recovery of ctDNA and improve the sensitivity for detecting small tumors.

The role of IgG4 in systemic lupus erythematosus: Implications for pathogenesis and therapy

Immunoglobulin (Ig) G4 has a distinctive nature, and its involvement in autoimmune disorders is a subject of ongoing debate and uncertainty. A growing body of evidence indicates that IgG4 may play a pathogenic role in the development of systemic lupus erythematosus (SLE). The IgG4 autoantibodies have the capability to bind autoantigens in a competitive manner with other Ig classes, thereby forming immune complexes (ICs) that are noninflammatory in nature. This is due to the low affinity of IgG4 for both the Fc receptors and the C1 complement molecule, which results in a diminished inflammatory response in individuals with SLE. The present study aims to elucidate the significance of IgG4 in SLE. The present discourse pertains to the nascent and suggested modalities through which IgG4 might participate in the pathogenesis of SLE and the potential ramifications for therapeutic interventions in SLE.

SLE classification criteria: Is "The causality principle" integrated and operative - and do the molecular and genetical network, on which criteria depend on, support the definition of SLE as "a one disease entity" - A theoretical discussion

Molecular and cellular aspects of the autoimmune pathophysiology in SLE is linked to the "The causality principle". SLE Classification Criteria identify per definition disease measures (here: synonymous with classification criteria), but not diagnostic criteria within a classical framework. These two mostly theoretical criteria collections represent a salient conflict between phenomenology and the causality principle - between disease measures and molecular interactions that promote such measures, in other words their cause(s). Essentially, each criterion evolves from immunogenic and inflammatory signals - some are interconnected, some are not. Disparate signals instigated by disparate causes. These may promote clinically heterogenous SLE cohorts with respect to organ affection, autoimmunity, and disease course. There is today no concise measures or arguments that settle whether SLE cohorts evolve from one decisive etiological factor (homogenous cohorts), or if disparate patho-biological factors promote SLE (heterogenous cohorts). Current SLE cohorts are not ideal substrates to serve as study objects if the research aims are to describe etiology, and molecular interactions that cause - and link - primary and secondary pathophysiological events together - events that account for early and progressive SLE. We have to develop SLE criteria allowing us to identify definable categories of SLE in order to describe etiology, pathophysiology and diagnostic criteria of delimitated SLE versions. In this regard, the causality principle is central to define dominant etiologies of individual SLE categories, and subsequent and consequent down-stream diagnostic disease measures. In this sense, we may whether we like it or not identify different SLE categories like "genuine SLE" and "SLE-like non-SLE" syndromes. Many aspects of this problem are thoroughly discussed in this study.

Endothelial cell activation and glycocalyx shedding - potential as biomarkers in patients with lupus nephritis

Lupus nephritis (LN) is a common and severe manifestation of systemic lupus erythematosus and an important cause of acute and chronic kidney injury. Early diagnosis of LN and preventing relapses are key to preserving renal reserve. However, due to the complexity and heterogeneity of the disease, clinical management remains challenging. Kidney biopsy remains the gold standard for confirming the diagnosis of LN and subsequent assessment of kidney histopathology, but it is invasive and cannot be repeated frequently. Current clinical indicators of kidney function such as proteinuria and serum creatinine level are non-specific and do not accurately reflect histopathological changes, while anti-dsDNA antibody and C3 levels reflect immunological status but not kidney injury. Identification of novel and specific biomarkers for LN is prerequisite to improve management. Renal function deterioration is associated with changes in the endothelial glycocalyx, a delicate gel-like layer located at the interface between the endothelium and bloodstream. Inflammation induces endothelial cell activation and shedding of glycocalyx constituents into the circulation. This review discusses the potential role of soluble glycocalyx components as biomarkers of active LN, especially in patients in whom conventional serological and biochemical markers do not appear helpful.

Activated Lymphocyte-Derived DNA Drives Glucose Metabolic Adaptation for Inducing Macrophage Inflammatory Response in Systemic Lupus Erythematosus

Activated lymphocyte-derived DNA (ALD-DNA) has been reported to drive the polarization of macrophages toward M2b, producing inflammatory cytokines and inducing inflammation, correspondingly playing an essential role in the development of systemic lupus erythematosus (SLE). Recently, accumulating evidence has pinpointed metabolic adaptation as the crucial cell-intrinsic determinant for inflammatory response, in which glucose metabolism is the key event. However, whether and how glucose metabolism was involved in ALD-DNA-induced macrophage inflammatory response and SLE development remains unclear. Herein, we performed glucose metabolomic analyses of ALD-DNA-stimulated macrophages and uncovered increased glycolysis and diminished pentose phosphate pathway (PPP), as well as enhanced glycogenesis. In ALD-DNA-stimulated macrophages, increased glycolysis resulted in higher lactate production, whereas diminished PPP efficiently led to lower levels of nicotinamide adenine dinucleotide phosphate (NADPH) with higher levels of reactive oxygen species (ROS). While blockade of lactate generation exerted no significant effect on macrophage inflammation in response to ALD-DNA, scavenging ROS fundamentally inhibited the inflammatory response of ALD-DNA-stimulated macrophages. Further, cyclic adenosine monophosphate (cAMP), a master for regulating glycogen metabolism, was downregulated by ALD-DNA in macrophages, which subsequently imbalanced glycogen metabolism toward glycogenesis but not glycogenolysis. Administration of cAMP effectively restored glycogenolysis and enhanced PPP, which correspondingly reduced ROS levels and inhibited the inflammatory response of ALD-DNA-stimulated macrophages. Finally, blocking glucose metabolism using 2-deoxy-D-glucose (2-DG) efficiently restricted macrophage inflammatory response and alleviated ALD-DNA-induced lupus disease. Together, our findings demonstrate that ALD-DNA drives the adaptation of glucose metabolism for inducing macrophage inflammatory response in SLE, which might further our understanding of disease pathogenesis and provide clues for interventive explorations.

Rosuvastatin treatment alone cannot alleviate lupus in murine model: a pilot study

Objective

Systemic lupus erythematosus (SLE) is an autoimmune disease, characterized by the production of autoantibodies and high cholesterol levels. HMG-CoA (3-hydroxy-3-methylglutaryl-coenzyme A) reductase inhibitors have exhibited anti-inflammatory effects in several clinical trials. We conducted this study to evaluate the effect of rosuvastatin on inflammatory responses in lupus-prone mice.

Methods

MRL/lpr mice were intraperitoneally injected with rosuvastatin (10 mg/kg, n=4) or vehicle (2% dimethyl sulfoxide, n=4) five times a week from 13 to 17 weeks of age. The serum levels of low-density lipoprotein (LDL) cholesterol and autoantibodies were measured, as well as the urine levels of albumin. Renal tissues were stained for histopathological analysis. Concentrations of key inflammatory cytokines were measured in the serum, and messenger RNA (mRNA) levels in target organs (kidney, spleen, and lymph nodes) were evaluated.

Results

Rosuvastatin treatment significantly decreased serum LDL cholesterol concentration in MRL/lpr mice. However, the clinical manifestations and autoantibody titres did not improve with rosuvastatin treatment. In addition, serum inflammatory cytokines and proteinuria did not change. Histopathological analysis of the kidneys revealed no improvement. When assessing the expression of mRNA, treatment with rosuvastatin decreased tumor necrosis alpha and interleukin-17 concentration in spleen and kidney tissue and in the kidneys and lymph nodes of MRL/lpr mice, respectively.

Conclusion

Although it can decrease inflammatory cytokines in the lymphoid organs and kidneys of MRL/lpr mice, treatment with rosuvastatin is insufficient to alleviate SLE.

A comparison of the chemiluminescence immunoassay and Crithidia luciliae immunofluorescence test in detecting anti-dsDNA antibodies and assessing the activity of systemic lupus erythematosus

OBJECTIVES

This study aimed to compare the YHLO chemiluminescence immunoassay (CLIA) with the Crithidia luciliae immunofluorescence test (CLIFT) to detect anti-dsDNA antibodies and its correlation with disease activity in systemic lupus erythematosus (SLE).

METHOD

In total, 208 patients diagnosed with SLE, 110 other autoimmune patients, 70 infectious disorders patients, and 105 healthy people were enrolled in this study. Serum samples were tested using CLIA in a YHLO chemiluminescence system and CLIFT.

RESULTS

The overall agreement between YHLO CLIA and CLIFT was 76.9% (160/208), with a moderate correlation (kappa = 0.530, p < 0.001). The sensitivity of YHLO CLIA and CLIFT were 58.2% and 55.3%, respectively. The specificity of YHLO CLIA and CLIFT were 95.1% and 99.3%, respectively. The sensitivity of YHLO CLIA was increased to 66.8% with a specificity of 93.6% when the cut-off value was set at 24 IU/mL. Spearman's correlation coefficient between the quantitative results of YHLO CLIA and the titers of CLIFT was 0.59 (p < .01). A significant correlation was found between the anti-dsDNA results detected by YHLO CLIA and the SLE Disease Activity Index 2000 (SLEDAI-2K). Spearman's correlation coefficient between YHLO CLIA and SLEDAI-2K (r = 0.66, p < .01) was higher than that of CLIFT (r = 0.60, p < .01).

CONCLUSIONS

Good correlation and agreement were found between YHLO CLIA and CLIFT. In addition, there was a significant correlation between YHLO CLIA and the SLE Disease Activity Index, which was superior to that of CLIFT. The YHLO chemiluminescence system is recommended for the assessment of disease activity.

"Untargeting" autoantibodies using genome editing, a proof-of-concept study

Autoantibodies (AAbs) are useful biomarkers and many have direct pathogenic role. Current standard therapies for elimination of specific B/plasma-cell clones are not fully efficient. We apply CRISPR/Cas9 genome-editing to knockout V(D)J rearrangements that produce pathogenic AAbs in vitro. HEK293T cell-lines were established stably expressing a humanized anti-dsDNA Ab (clone 3H9) and a human-derived anti-nAChR-α1 Ab (clone B12L). For each clone, five CRISPR/Cas9 heavy-chain's CDR2/3-targeting guided-RNAs (T-gRNAs) were designed. Non-Target-gRNA (NT-gRNA) was control. After editing, levels of secreted Abs were evaluated, as well as 3H9 anti-dsDNA and B12L anti-AChR reactivities. T-gRNAs editing decreased expression of heavy-chain genes to ~50-60%, compared to >90% in NT-gRNA, although secreted Abs levels and reactivity to their respective antigens in T-gRNAs decreased ~90% and ~ 95% compared with NT-gRNA for 3H9 and B12L, respectively. Sequencing indicated indels at Cas9 cut-site, which could lead to codon jam, and consequently, knockout. Additionally, remaining secreted 3H9-Abs presented variable dsDNA reactivity among the five T-gRNA, suggesting the exact Cas9 cut-site and indels further interfere with antibody-antigen interaction. CRISPR/Cas9 genome-editing was very effective to knockout the Heavy-Chain-IgG genes, considerably affecting AAbs secretion and binding capacity, fostering application of this concept to in vivo models as a potential novel therapeutic approach for AAb-mediated diseases.

Benzo[a]pyrene Exposure Reduces Cell-Type Diversity and Stimulates Sex-Biased Damage Pathways in End Organs of Lupus-Prone Mice

Studies indicate that genetic factors only account for approximately thirty percent of all autoimmune diseases, while the rest of autoimmune pathogenesis is attributed to environmental factors including toxic chemicals. To understand if and how environmental pollutants trigger autoimmunity, we investigated the effect of benzo[a]pyrene (BaP) exposure on the development of autoimmune phenotypes in the lupus-prone MRL strain. The exposure of MRL mice to BaP over the course of 8 weeks before lupus onset resulted in total body weight loss in males, while marginal changes in anti-dsDNA levels occurred. Multi-organ analyses of BaP-treated and control MRL mice suggested that the kidney is a major organ directly affected by the metabolism of benzene-containing compounds, with increased expression of BaP-target genes including Cyp4b1 and Hao2. Intriguingly, spatial transcriptomic data showed that BaP caused a drastic reduction in cell-type diversity in both the kidneys and spleen of MRL mice. Further analysis of the molecular pathways affected suggested a sex-biased effect of BaP treatment, with the upregulated expression of angiogenesis genes in the lungs and an increased deposition of C3 in the kidneys of male mice. While SLE is more common in women, the disease is more severe in male patients, with an increased risk of disease progression to renal failure and lung cancer. Our results reveal sex-biased molecular pathways stimulated by BaP which may help explain the increased likelihood of end organ damage in males with lupus.

Affinity maturation generates pathogenic antibodies with dual reactivity to DNase1L3 and dsDNA in systemic lupus erythematosus

Anti-dsDNA antibodies are pathogenically heterogeneous, implying distinct origins and antigenic properties. Unexpectedly, during the clinical and molecular characterization of autoantibodies to the endonuclease DNase1L3 in patients with systemic lupus erythematosus (SLE), we identified a subset of neutralizing anti-DNase1L3 antibodies previously catalogued as anti-dsDNA. Based on their variable heavy-chain (VH) gene usage, these antibodies can be divided in two groups. One group is encoded by the inherently autoreactive VH4-34 gene segment, derives from anti-DNase1L3 germline-encoded precursors, and gains cross-reactivity to dsDNA - and some additionally to cardiolipin - following somatic hypermutation. The second group, originally defined as nephritogenic anti-dsDNA antibodies, is encoded by diverse VH gene segments. Although affinity maturation results in dual reactivity to DNase1L3 and dsDNA, their binding efficiencies favor DNase1L3 as the primary antigen. Clinical, transcriptional and monoclonal antibody data support that cross-reactive anti-DNase1L3/dsDNA antibodies are more pathogenic than single reactive anti-dsDNA antibodies. These findings point to DNase1L3 as the primary target of a subset of antibodies classified as anti-dsDNA, shedding light on the origin and pathogenic heterogeneity of antibodies reactive to dsDNA in SLE.

A novel selective spleen tyrosine kinase inhibitor SKI-O-703 (cevidoplenib) ameliorates lupus nephritis and serum-induced arthritis in murine models

Spleen tyrosine kinase (Syk) plays a pivotal role in the activation of B cells and innate inflammatory cells by transducing immune receptor-triggered signals. Dysregulated activity of Syk is implicated in the development of antibody-mediated autoimmune diseases including systemic lupus erythematosus (SLE) and rheumatoid arthritis, but the effect of Syk inhibition on such diseases remains to be fully evaluated. We have developed a novel selective Syk inhibitor, SKI-O-592, and its orally bioavailable salt form, SKI-O-703 (cevidoplenib). To examine the efficacy of SKI-O-703 on the progression of SLE, New Zealand black/white mice at the autoimmunity-established phase were administrated orally with SKI-O-703 for 16 weeks. Levels of IgG autoantibody, proteinuria, and glomerulonephritis fell significantly, and this was associated with hypoactivation of follicular B cells via the germinal center. In a model of serum-transferred arthritis, SKI-O-703 significantly ameliorated synovitis, with fewer neutrophils and macrophages infiltrated into the synovial tissue. This effect was recapitulated when mice otherwise refractory to anti-TNF therapy were treated by TNF blockade combined with a suboptimal dose of SKI-O-703. These results demonstrate that the novel selective Syk inhibitor SKI-O-703 attenuates the progression of autoantibody-mediated autoimmune diseases by inhibiting both autoantibody-producing and autoantibody-sensing cells.

Risk of systemic lupus erythematosus flares according to autoantibody positivity at the time of diagnosis

To estimate the risk of systemic lupus erythematosus (SLE) flares based on the autoantibody positivity at the time of SLE diagnosis. This retrospective cohort study included 228 patients with newly diagnosed SLE. Clinical characteristics including autoantibody positivity at the time of diagnosis of SLE were reviewed. Flares were defined as a new British Isles Lupus Assessment Group (BILAG) A score or BILAG B score for at least one organ system. Multivariable Cox regression analyses were performed to estimate the risk of flares according to autoantibody positivity. Anti-dsDNA, anti-Sm, anti-U1RNP, anti-Ro, and anti-La antibodies (Abs) were positive in 50.0%, 30.7%, 42.5%, 54.8%, and 22.4% of the patients, respectively. The incidence rate of flares was 28.2/100 person-years. Multivariable Cox regression analysis, adjusted for potential confounders, revealed that anti-dsDNA Ab positivity (adjusted hazard ratio [HR]: 1.46, p = 0.037) and anti-Sm Ab positivity (adjusted HR: 1.81, p = 0.004) at the time of diagnosis of SLE were associated with higher risk of flares. To better delineate the flare risk, patients were categorized as double-negative, single-positive, double-positive for anti-dsDNA and anti-Sm Abs. Compared with double-negativity, double-positivity (adjusted HR: 3.34, p < 0.001) was associated with higher risk of flares, while anti-dsDNA Ab single-positivity (adjusted HR: 1.11, p = 0.620) or anti-Sm Ab single-positivity (adjusted HR: 1.32, p = 0.270) was not associated with higher risk of flares. Patients who are double-positive for anti-dsDNA and anti-Sm Abs at the time of the diagnosis of SLE are at higher risk of flares and may benefit from stringent monitoring and early preventive treatment.

An intravenous DNA-binding priming agent protects cell-free DNA and improves the sensitivity of liquid biopsies

Blood-based, or "liquid," biopsies enable minimally invasive diagnostics but have limits on sensitivity due to scarce cell-free DNA (cfDNA). Improvements to sensitivity have primarily relied on enhancing sequencing technology ex vivo . Here, we sought to augment the level of circulating tumor DNA (ctDNA) detected in a blood draw by attenuating the clearance of cfDNA in vivo . We report a first-in-class intravenous DNA-binding priming agent given 2 hours prior to a blood draw to recover more cfDNA. The DNA-binding antibody minimizes nuclease digestion and organ uptake of cfDNA, decreasing its clearance at 1 hour by over 150-fold. To improve plasma persistence and limit potential immune interactions, we abrogated its Fc-effector function. We found that it protects GC-rich sequences and DNase-hypersensitive sites, which are ordinarily underrepresented in cfDNA. In tumor-bearing mice, priming improved tumor DNA recovery by 19-fold and sensitivity for detecting cancer from 6% to 84%. These results suggest a novel method to enhance the sensitivity of existing DNA-based cancer testing using blood biopsies.

Classification of Systemic Lupus Erythematosus Using Raman Spectroscopy of Blood and Automated Computational Detection Methods: A Novel Tool for Future Diagnostic Testing

The aim of this study was to explore the proof of concept for using Raman spectroscopy as a diagnostic platform in the setting of systemic lupus erythematosus (SLE). We sought to identify unique Raman signatures in serum blood samples to successfully segregate SLE patients from healthy controls (HC). In addition, a retrospective audit was undertaken to assess the clinical utility of current testing platforms used to detect anti-double stranded DNA (dsDNA) antibodies (n = 600). We examined 234 Raman spectra to investigate key variances between SLE patients (n = 8) and HC (n = 4). Multi-variant analysis and classification model construction was achieved using principal component analysis (PCA), PCA-linear discriminant analysis and partial least squares-discriminant analysis (PLS-DA). We achieved the successful segregation of Raman spectra from SLE patients and healthy controls (p-value < 0.0001). Classification models built using PLS-DA demonstrated outstanding performance characteristics with 99% accuracy, 100% sensitivity and 99% specificity. Twelve statistically significant (p-value < 0.001) wavenumbers were identified as potential diagnostic spectral markers. Molecular assignments related to proteins and DNA demonstrated significant Raman intensity changes between SLE and HC groups. These wavenumbers may serve as future biomarkers and offer further insight into the pathogenesis of SLE. Our audit confirmed previously reported inconsistencies between two key methodologies used to detect anti-dsDNA, highlighting the need for improved laboratory testing for SLE. Raman spectroscopy has demonstrated powerful performance characteristics in this proof-of-concept study, setting the foundations for future translation into the clinical setting.

(NZW × BXSB) F1 male mice: An unusual, severe and fatal mouse model of lupus erythematosus

Background

Systemic lupus erythematosus (SLE) is a chronic autoimmune/inflammatory disease. The heterogeneity and complexity of clinical presentation has made it challenging to study or treat this syndrome. The (NZW×BXSB) F1 lupus-prone male mouse model of this disease is potentially useful to study mechanism and treatment modalities, but there is a lack of information about this model’s characterization and disease progression. Therefore, the aim was to examine this lupus model’s physical/clinical disease presentation and its immunological status.

Materials and methods

Clinical and physical status were observed in 8- and 16-week-old male and female (± 1 week) (NZW/LacJ x BXSB/MpJ) F1 mice (n = 8 per group). Young males (8 ± 1 week) without disease and female (16 ± 1 week) mice served as controls. Physical changes, quantitative values of autoantibodies, and blood cell parameters were determined. Necropsy and post-mortem histopathology were also performed.

Results

With aging (≥ 12 weeks), significant increases in severe abdominal distension/swelling, inability to walk, paleness of paws and significant weight increase were observed compared to controls (p < 0.05). The necropsy examination showed abdominal distension associated with serous effusion and histological examination identified severe edema and multi-organ abnormalities (spleen, lymph nodes, and kidney). Significant increases in anti-double-stranded DNA antibody (anti-dsDNA) was seen in old/sick compared to female (p = 0.0002) or young male (p = 0.0036) mice. Old mice developed immune thrombocytopenia compared to female (p = 0.0056) and young male (p = 0.0007) mice. Anti-platelet was detectable in old, sick mice. The mortality rate increased with aging; more than 35% of male mice died during this study between the ages of 13-18 weeks.

Conclusion

We found that the (NZW/LacJ x BXSB/MpJ) F1 male mice spontaneously exhibit, over varying lengths of time, extremely severe and fatal clinical disease symptoms. This model may be too severe to be helpful in investigating SLE and testing potential treatment modalities.

Measurement of circulating CD21-CD27- B lymphocytes in SLE patients is associated with disease activity independently of conventional serological biomarkers

Determining disease activity in systemic lupus erythematosus (SLE) patients is challenging and limited by the lack of reliable biomarkers. Abnormally activated B cells play a key role in the pathogenesis of SLE, but their measure in clinical practice is currently not recommended. Here, we studied peripheral B cells to identify a valid biomarker. We analyzed peripheral B cells in a discovery cohort of 30 SLE patients compared to 30 healthy controls (HC) using mass cytometry and unsupervised clustering analysis. The relevant B cell populations were subsequently studied by flow cytometry in a validation cohort of 63 SLE patients, 28 autoimmune diseases controls and 39 HC. Our data show an increased frequency of B cell populations with activated phenotype in SLE compared to healthy and autoimmune diseases controls. These cells uniformly lacked the expression of CD21 and CD27. Measurement of CD21⁻CD27⁻ B cells in the blood identified patients with active disease and their frequency correlated with disease severity. Interestingly, we did not observe an increase in the frequency of CD21⁻CD27⁻ B cells in patients with clinically inactive disease but with elevated conventional biomarkers (anti-dsDNA and complement levels). Accordingly, measurement of CD21⁻CD27⁻ B cells represents a robust and easily accessible biomarker to assess the activity of the disease in SLE patients.

Diagnosing and Managing Clinically Silent Lupus Nephritis and Anti-neutrophil Cytoplasmic Antibody-Associated Vasculitis Overlap Syndrome: A Clinical Challange

Lupus nephritis is typically associated with anti-nuclear antibodies and anti-double-stranded DNA antibodies resulting in the intrarenal immune complex deposition. Levels of anti-double-stranded DNA antibodies reflect disease activity in these patients. With negative anti-double-stranded DNA antibodies, establishing a diagnosis of lupus nephritis is difficult. Lupus nephritis overlapped with anti-neutrophil cytoplasmic antibody-associated vasculitis is both a diagnostic and therapeutic dilemma. Herein, we describe a case of an asymptomatic 41-year-old female who had incidental findings of low hemoglobin and elevated serum creatinine. Making a clinical diagnosis of lupus nephritis and anti-neutrophil cytoplasmic antibody-associated vasculitis in an asymptomatic patient can be challenging and must be made based on the interpretation of evolving serology, imaging studies, and histopathology. Based on extensive workup, the patient was diagnosed with concurrent lupus nephritis and anti-neutrophil cytoplasmic antibody-associated vasculitis overlap syndrome warranting immediate immunosuppressive therapy.

T Helper 2-Associated Immunity in the Pathogenesis of Systemic Lupus Erythematosus

Systemic Lupus Erythematosus (SLE) is a chronic autoimmune disease that mainly affects women in their reproductive years. A complex interaction of environmental and genetic factors leads to the disruption of immune tolerance towards self, causing overt immune activation and production of autoantibodies that attack multiple organs. Kidney damage, termed lupus nephritis, is the leading cause of SLE-related morbidity and mortality. Autoantibodies are central to propagating lupus nephritis through forming immune complexes and triggering complements. Immunoglobulin G (IgG) potently activates complement; therefore, autoantibodies were mainly considered to be of the IgG isotype. However, studies revealed that over 50% of patients produce autoantibodies of the IgE isotype. IgE autoantibodies actively participate in disease pathogenesis as omalizumab treatment, a humanized anti-IgE monoclonal antibody, improved disease severity in an SLE clinical trial. IgE is a hallmark of T helper 2-associated immunity. Thus, T helper 2-associated immunity seems to play a pathogenic role in a subset of SLE patients. This review summarizes human and animal studies that illustrate type 2 immune responses involved during the pathology of SLE.

Longitudinal analysis of urinary proteins in lupus nephritis - A pilot study

Approximately 30% of adult-onset systemic lupus erythematosus (SLE) patients develop lupus nephritis (LN). The gold standard for LN detection involves renal biopsies, invasive procedures not suitable for routine disease monitoring. A urinary biomarker panel comprised of lipocalin-like prostaglandin D synthase (LPGDS), transferrin, alpha-1-acid glycoprotein (AGP-1), ceruloplasmin, monocyte chemoattractant protein 1 (MCP-1) and soluble vascular cell adhesion molecule-1 (sVCAM-1) has shown promise to predict LN and response to rituximab at baseline. Whether these proteins predict LN during longitudinal sampling, however, remained unknown. Here, we quantified aforementioned urinary proteins at baseline (N = 25), six and twelve months (N = 17 each) after rituximab treatment. Urine MCP-1 (at six and twelve months) and AGP-1 (at twelve months) levels varied between patients with active vs mildly active/inactive LN. Findings support the use of urinary proteins to detect active LN in ongoing disease monitoring in adult-onset SLE patients, but need to be validated in larger cohorts.

The Anti-DNA Antibodies: Their Specificities for Unique DNA Structures and Their Unresolved Clinical Impact-A System Criticism and a Hypothesis

Systemic lupus erythematosus (SLE) is diagnosed and classified by criteria, or by experience, intuition and traditions, and not by scientifically well-defined etiology(ies) or pathogenicity(ies). One central criterion and diagnostic factor is founded on theoretical and analytical approaches based on our imperfect definition of the term “The anti-dsDNA antibody”. “The anti-dsDNA antibody” holds an archaic position in SLE as a unique classification criterium and pathogenic factor. In a wider sense, antibodies to unique transcriptionally active or silent DNA structures and chromatin components may have individual and profound nephritogenic impact although not considered yet – not in theoretical nor in descriptive or experimental contexts. This hypothesis is contemplated here. In this analysis, our state-of-the-art conception of these antibodies is probed and found too deficient with respect to their origin, structural DNA specificities and clinical/pathogenic impact. Discoveries of DNA structures and functions started with Miescher’s Nuclein (1871), via Chargaff, Franklin, Watson and Crick, and continues today. The discoveries have left us with a DNA helix that presents distinct structures expressing unique operations of DNA. All structures are proven immunogenic! Unique autoimmune antibodies are described against e.g. ssDNA, elongated B DNA, bent B DNA, Z DNA, cruciform DNA, or individual components of chromatin. In light of the massive scientific interest in anti-DNA antibodies over decades, it is an unexpected observation that the spectrum of DNA structures has been known for decades without being implemented in clinical immunology. This leads consequently to a critical analysis of historical and contemporary evidence-based data and of ignored and one-dimensional contexts and hypotheses: i.e. “one antibody - one disease”. In this study radical viewpoints on the impact of DNA and chromatin immunity/autoimmunity are considered and discussed in context of the pathogenesis of lupus nephritis.

B cell-specific deletion of Crif1 drives lupus-like autoimmunity by activation of IL-17, IL-6, and pathogenic Tfh cells

OBJECTIVE

CR6-interacting factor 1 (Crif1) is a nuclear transcriptional regulator and a mitochondrial inner membrane protein; however, its functions in B lymphocytes have been poorly defined. In this study, we investigated the effects of Crif1 on B-cell metabolic regulation, cell function, and autoimmune diseases.

METHODS

Using mice with B cell-specific deletion of Crif1 (Crif1^ΔCD19 ), we assessed the relevance of Crif1 function for lupus disease parameters including anti-double-stranded DNA, cytokines, and kidney pathology. RNA sequencing was performed on B cells from Crif1^ΔCD19 mice. The phenotypic and metabolic changes in immune cells were evaluated in Crif1^ΔCD19 mice. Roquin^san/+ mice crossed with Crif1^ΔCD19 mice were monitored to assess the functionality of Crif1-deficient B cells in lupus development.

RESULTS

Crif1^ΔCD19 mice showed an autoimmune lupus-like phenotype, including high levels of autoantibodies to double-stranded DNA and severe lupus nephritis with increased mesangial hypercellularity. While loss of Crif1 in B cells showed impaired mitochondrial oxidative function, Crif1-deficient B cells promoted the production of IL-17 and IL-6 and was more potent in helping T cells develop into T follicular helper cells. In an autoimmune lupus mouse model, depletion of Crif1 in B cells exacerbated lupus severity and Crif1 overexpression prevented lupus development in Roquin^san/san mice.

CONCLUSION

These results showed that Crif1 was negatively correlated with disease severity, and overexpression of Crif1 ameliorated disease development. Our findings suggest that Crif1 is essential for preventing lupus development by maintaining B cell self-tolerance.

Disabled-2 (DAB2) overexpression mediates immune suppression in systemic lupus erythematosus by modulating Treg/Th17 cell differentiation

Systemic lupus erythematosus (SLE) is an autoimmune disorder. T helper 17 (Th17) and regulatory T (Treg) cells play key roles in SLE progression. Disabled-2 (DAB2) exhibits immunomodulatory effects in inflammatory diseases. However, the role of DAB2 in SLE and the precise mechanisms remain unknown. Herein, a decreased DAB2 expression and an increased miR-448-3p level were observed in PBMCs from SLE patients. DAB2 level was negatively correlated with SLE Disease Activity Index (SLEDAI), suggesting a functional correlation between DAB2 and SLE. To test this, we employed 8-week-old MRL/lpr mice and treated them with lentivirus-mediated DAB2 or its negative control (LV-NC). LV-DAB2 treatment increased DAB2 expression and reduced serum IgG and anti-dsDNA IgG levels. DAB2 up-regulation alleviated splenomegaly and lymphadenopathy and SLE-related organ damage. Moreover, DAB2 enhanced the percentage of CD25⁺ Foxp3⁺ Treg cells but reduced Th17 cell frequency in lupus, along with the reduction in TNF-α, IL-6 and IL-17A levels, and the elevation in IL-10. In vitro, naive CD4⁺ T cells isolated from MRL/lpr mice were polarized into Th17 or Treg phenotypes and treated with lentivirus. LV-DAB2 treatment down-regulated IL-17A expression and inhibited the generation of CD4⁺ IL-17A⁺ Th17 cells. Also, DAB2 triggered the production of IL-10 and the activation of Treg cells. Furthermore, DAB2 was verified as a direct target for miR-448-3p. MiR-448-3p overexpression canceled the promoting effect of DAB2 on Treg cell differentiation. Taken together, DAB2 exerts an immunosuppressive effect on SLE through promoting Treg cell activation and inhibiting Th17 cell differentiation, which may be modulated by miR-448-3p.

Regulatory strategies limiting endosomal Toll-like receptor activation in B cells

The recognition of pathogen-associated nucleic acid (NA) promotes effective immunity against invading pathogens. However, endosomal Toll-like receptor (TLR) activation by self-NA also underlies the pathogenesis of systemic autoimmune diseases, such as systemic lupus erythematosus (SLE). For this reason, the activation thresholds of NA-sensing TLRs must be tightly regulated to balance protective and pathogenic immune responses. In this study, we will provide an overview of the evolutionary mechanisms designed to limit the aberrant activation of endosomal TLRs by self-ligands, focusing on four broad strategies. These include the following: 1) the production of nucleases able to degrade self-DNA and RNA; 2) the cell-specific regulation of endosomal TLR expression; 3) the spatial and temporal control of TLR positioning at a sub-cellular level; and 4) the modulation of downstream TLR signaling cascades. Given the critical role of B cells in lupus pathogenesis, where possible, we will describe evidence for B cell-specific induction of these regulatory mechanisms. We will also highlight our own work showing how modulation of B cell endolysosomal flux tunes NA-sensing TLR activation signals. In the face of inevitable generation of self-NA during normal cellular turnover, these parallel mechanisms are vital to protect against pathogenic inflammation.

Follicular dendritic cells

Follicular dendritic cells (FDCs) are unique accessory immune cells that contribute to the regulation of humoral immunity. They are multitasker cells essential for the organization and maintenance of the lymphoid architecture, induction of germinal center reaction, production of B memory cells, and protection from autoimmune disorders. They perform their activities through both antigen-driven and chemical signaling to B cells. FDCs play a crucial role in the physiological regulation of the immune response. Dis-regulation of this immune response results when FDCs retain antigens for years. This provides a constant antigenic stimulation for B cells resulting in the development of immune disorders. Antigen trapped on FDCs is resistant to therapeutic intervention causing chronicity and recurrences. Beyond their physiological immunoregulatory functions, FDCs are involved in the pathogenesis of several immune-related disorders including HIV/AIDS, prion diseases, chronic inflammatory, and autoimmune disorders. FDCs have also been recently implicated in rare neoplasms of lymphoid and hematopoietic tissues. Understanding FDC biology is essential for better control of humoral immunity and opens the gate for therapeutic management of FDC-mediated immune disorders. Thus, the biology of FDCs has become a hot research area in the last couple of decades. In this review, we aim to provide a comprehensive overview of FDCs and their role in physiological and pathological conditions.

Multiple tolerance checkpoints restrain affinity maturation of B cells expressing the germline precursor of a lupus patient-derived anti-dsDNA antibody in knock-in mice

Anti-dsDNA antibodies are a hallmark of systemic lupus erythematosus and are highly associated with its exacerbation. Cumulative evidence has suggested that somatic hypermutation contributes to the high-affinity reactivity of anti-dsDNA antibodies. Our previous study demonstrated that these antibodies are generated from germline precursors with low-affinity ssDNA reactivity through affinity maturation and clonal expansion in patients with acute lupus. This raised the question of whether such precursors could be subject to immune tolerance. To address this, we generated a site-directed knock-in (KI) mouse line, G9gl, which carries germline-reverted sequences of the VH-DH-JH and Vκ-Jκ regions of patient-derived, high-affinity anti-dsDNA antibodies. G9gl heterozygous mice had a reduced number of peripheral B cells, only 27% of which expressed G9gl B cell receptor (BCR). The remaining B cells harbored non-KI allele-derived immunoglobulin heavy (IgH) chains or fusion products of upstream mouse VH and the KI gene, suggesting that receptor editing through VH replacement occurred in a large proportion of B cells in the KI mice. G9gl BCR-expressing B cells responded to ssDNA but not dsDNA, and exhibited several anergic phenotypes, including reduced surface BCR and shortened life span. Further, G9gl B cells were excluded from germinal centers (GCs) induced by several conditions. In particular, following immunization with methylated bovine serum albumin-conjugated bacterial DNA, G9gl B cells occurred at a high frequency in memory B cells but not GC B cells or plasmablasts. Collectively, multiple tolerance checkpoints prevented low-affinity precursors of pathogenic anti-dsDNA B cells from undergoing clonal expansion and affinity maturation in GCs.

Effectiveness of Belimumab After Rituximab in Systemic Lupus Erythematosus : A Randomized Controlled Trial

BACKGROUND

B-cell depletion with rituximab is commonly used for patients with systemic lupus erythematosus (SLE) that is refractory to conventional therapy, but it yields variable responses. We hypothesized that high B-cell activating factor (BAFF) levels after rituximab can cause disease flares, thereby limiting its effectiveness.

OBJECTIVE

To obtain preliminary evidence for efficacy of the anti-BAFF therapeutic belimumab after rituximab in SLE.

DESIGN

Phase 2, randomized, double-blind (patients, assessors, researchers, care providers), placebo-controlled, parallel-group, superiority trial. (ISRCTN: 47873003).

SETTING

England.

PARTICIPANTS

Fifty-two patients who had SLE that was refractory to conventional treatment and whose physicians had recommended rituximab therapy were recruited between 2 February 2017 and 28 March 2019.

INTERVENTION

Participants were treated with rituximab and 4 to 8 weeks later were randomly assigned (1:1) to receive intravenous belimumab or placebo for 52 weeks.

MEASUREMENTS

The prespecified primary end point was serum IgG anti-double-stranded DNA (anti-dsDNA) antibody levels at 52 weeks. Secondary outcomes included incidence of disease flares and adverse events.

RESULTS

At 52 weeks, IgG anti-dsDNA antibody levels were lower in patients treated with belimumab compared with placebo (geometric mean, 47 [95% CI, 25 to 88] vs. 103 [CI, 49 to 213] IU/mL; 70% greater reduction from baseline [CI, 46% to 84%]; P < 0.001). Belimumab reduced risk for severe flare (BILAG-2004 grade A) compared with placebo (hazard ratio, 0.27 [CI, 0.07 to 0.98]; log-rank P = 0.033), with 10 severe flares in the placebo group and 3 in the belimumab group. Belimumab did not increase incidence of serious adverse events. Belimumab significantly suppressed B-cell repopulation compared with placebo (geometric mean, 0.012 [CI, 0.006 to 0.014] vs. 0.037 [CI, 0.021 to 0.081] × 10⁹/L) at 52 weeks in a subset of patients (n = 25) with available data.

LIMITATIONS

Small sample size; biomarker primary end point.

CONCLUSION

Belimumab after rituximab significantly reduced serum IgG anti-dsDNA antibody levels and reduced risk for severe flare in patients with SLE that was refractory to conventional therapy. The results suggest that this combination could be developed as a therapeutic strategy.

PRIMARY FUNDING SOURCE

Versus Arthritis.

High Systemic Type I Interferon Activity is Associated with Active Class III/IV Lupus Nephritis

OBJECTIVE

Previous studies suggest a link between high serum type I interferon (IFN) and lupus nephritis (LN). We determined whether serum IFN activity is associated with subtypes of LN and studied renal tissues and cells to understand the impact of IFN in LN.

METHODS

221 systemic lupus erythematosus (SLE) patients were studied. Serum IFN activity was measured by WISH bioassay. mRNA in-situ hybridization was used in renal tissue to measure expression of the representative IFN-induced gene, interferon-induced protein with tetratricopeptide repeats-1 (IFIT1), and the plasmacytoid dendritic cell (pDC) marker gene C-type lectin domain family-4 member C (CLEC4C or BDCA2). Podocyte cell line gene expression was measured by real-time PCR.

RESULTS

Class III/IV LN prevalence was significantly increased in patients with high serum IFN compared with those with low IFN (OR=5.48, p=4.0x10-7). In multivariate regression models, type I IFN was a stronger predictor of class III/IV LN than complement C3 or anti-dsDNA antibody, and could account for the association of these variables with LN. IFIT1 expression was increased in all classes of LN, but most in the glomerular areas of active class III/IV LN kidneys. IFIT1 expression was not closely co-localized with pDCs. IFN directly activated podocyte cell lines to induce chemokines and proapoptotic molecules.

CONCLUSION

Systemic high IFN is involved in the pathogenesis of severe LN. We do not find co-localization of pDCs with IFN signature in renal tissue, and instead observe the greatest intensity of IFN signature in glomerular areas, which could suggest a blood source of IFN.

Microarray testing in patients with systemic lupus erythematosus identifies a high prevalence of CpG DNA-binding antibodies

Objective

Many autoantibodies are known to be associated with SLE, although their role in clinical practice is limited because of low sensitivity and weak associations with clinical manifestations. There has been great interest in the discovery of new autoantibodies to use in clinical practice. In this study, we investigated 57 new and known antibodies and their potential for diagnostics or risk stratification.

Methods

Between 2014 and 2017, residual sera of all anti-dsDNA tests in the UMC Utrecht were stored in a biobank. This included sera of patients with SLE, patients with a diagnosis of another immune-mediated inflammatory disease (IMID), patients with low (non-IMID) or medium levels of clinical suspicion of SLE but no IMID diagnosis (Rest), and self-reported healthy blood bank donors. Diagnosis and (presence of) symptoms at each blood draw were retrospectively assessed in the patient records with the Utrecht Patient-Oriented Database using a newly developed text mining algorithm. Sera of patients were analysed for the presence of 57 autoantibodies with a custom-made immunofluorescent microarray. Signal intensity cut-offs for all antigens on the microarray were set to the 95th percentile of the non-IMID control group. Differences in prevalence of autoantibodies between patients with SLE and control groups were assessed.

Results

Autoantibody profiles of 483 patients with SLE were compared with autoantibody profiles of 1397 patients from 4 different control groups. Anti-dsDNA was the most distinguishing feature between patients with SLE and other patients, followed by antibodies against Cytosine-phosphate-Guanine (anti-CpG) DNA motifs (p<0.0001). Antibodies against CMV (cytomegalovirus) and ASCA (anti-Saccharomyces cerevisiae antibodies) were more prevalent in patients with SLE with (a history of) lupus nephritis than patients with SLE without nephritis.

Conclusion

Antibodies against CpG DNA motifs are prevalent in patients with SLE. Anti-CMV antibodies are associated with lupus nephritis.

Treatments and outcomes in Chinese patients with serologically active clinically quiescent systemic lupus erythematosus: a retrospective observational study

Objective

To clarify the frequency and outcome of patients with systemic lupus erythematosus (SLE) who achieved the clinical state as serologically active clinically quiescent (SACQ) and to identify factors associated with the flare of disease.

Methods

Clinical data of patients diagnosed as SLE and followed in Peking University First Hospital from 2009 to 2015 were retrospectively reviewed. Six hundred eighty-two patients who were followed up for more than 6 months were analyzed. SACQ was defined as an at least a 6-month period with persistent serologic activity and without clinical activity and daily dose of prednisone or equivalent were less than 7.5 mg. Serologically quiescent clinically quiescent (SQCQ) patients served as control groups. Data including demographics, initial symptoms, duration to SACQ, treatments before and after SACQ, and characteristics of the patients suffered from flare were analyzed.

Results

Among the 682 patients, 170 patients were SACQ (24.9%) and 187 patients were SQCQ. SQCQ patients (38.61 ± 15.08 years old) were older at baseline than SACQ patients (38.61 ± 15.08 years vs. 32.09 ± 14.35 years, p < 0.001). Of 170 SACQ patients, 32.9% experienced flare that was significantly higher than 15.5% of SQCQ patients (29/187). Corticosteroids (OR 1.323, 95% CI 1.129 to 1.550; p = 0.001) was an independent risk factor for flare, while antimalarials (OR 0.045, 95% CI 0.004 to 0.474; p = 0.010) and immunosuppressants (OR 0.332, 95% CI 0.156 to 0.706; p = 0.004) were protective factors in SACQ patients; however, only antimalarials was protective factors in SQCQ patients (OR 0.028, 95% CI 0.001 to 0.743; p = 0.033).

Conclusion

About one third of SLE patients with SACQ experience flare, significantly more frequent than that of patients with SQCQ. Thus, approach to prevent flare in SACQ patient is required. Maintenance therapy of hydroxychloroquine and immunosuppressant agents may be protective and beneficial treatment strategy in these patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13075-021-02641-5.

A panel of urinary proteins predicts active lupus nephritis and response to rituximab treatment

OBJECTIVES

∼30% of patients with SLE develop LN. Presence and/or severity of LN are currently assessed by renal biopsy, but biomarkers in serum or urine samples may provide an avenue for non-invasive routine testing. We aimed to validate a urinary protein panel for its ability to predict active renal involvement in SLE.

METHODS

A total of 197 SLE patients and 48 healthy controls were recruited, and urine samples collected. Seventy-five of the SLE patients had active LN and 104 had no or inactive renal disease. Concentrations of lipocalin-like prostaglandin D synthase (LPGDS), transferrin, alpha-1-acid glycoprotein (AGP-1), ceruloplasmin, monocyte chemoattractant protein 1 (MCP-1) and soluble vascular cell adhesion molecule-1 (sVCAM-1) were quantified by MILLIPLEX® Assays using the MAGPIX Luminex platform. Binary logistic regression was conducted to examine whether proteins levels associate with active renal involvement and/or response to rituximab treatment.

RESULTS

Urine levels of transferrin (P <0.005), AGP-1 (P <0.0001), MCP-1 (P <0.001) and sVCAM-1 (P <0.005) were significantly higher in SLE patients when compared with healthy controls. Furthermore, levels of transferrin, AGP-1, ceruloplasmin, MCP-1 and sVCAM-1 (all P <0.0001) were higher in SLE patients with active LN when compared with patients without active LN. A combination of five urine proteins, namely LPGDS, transferrin, ceruloplasmin, MCP-1 and sVCAM-1 was a good predictor of active LN (AUC 0.898). A combined model of LPGDS, transferrin, AGP-1, ceruloplasmin, MCP-1 and sVCAM-1 predicted response to rituximab treatment at 12 months (AUC 0.818).

CONCLUSIONS

Findings support the use of a urinary protein panel to identify active LN and potentially predict response to treatment with rituximab in adult SLE patients. Prospective studies are required to confirm findings.

The role of retrotransposable elements in ageing and age-associated diseases

The genomes of virtually all organisms contain repetitive sequences that are generated by the activity of transposable elements (transposons). Transposons are mobile genetic elements that can move from one genomic location to another; in this process, they amplify and increase their presence in genomes, sometimes to very high copy numbers. In this Review we discuss new evidence and ideas that the activity of retrotransposons, a major subgroup of transposons overall, influences and even promotes the process of ageing and age-related diseases in complex metazoan organisms, including humans. Retrotransposons have been coevolving with their host genomes since the dawn of life. This relationship has been largely competitive, and transposons have earned epithets such as 'junk DNA' and 'molecular parasites'. Much of our knowledge of the evolution of retrotransposons reflects their activity in the germline and is evident from genome sequence data. Recent research has provided a wealth of information on the activity of retrotransposons in somatic tissues during an individual lifespan, the molecular mechanisms that underlie this activity, and the manner in which these processes intersect with our own physiology, health and well-being.

TACI haploinsufficiency protects against BAFF-driven humoral autoimmunity in mice

Polymorphisms in TACI, a BAFF family cytokine receptor, are linked to diverse human immune disorders including common variable immunodeficiency (CVID) and systemic lupus erythematosus (SLE). Functional studies of individual variants show modest impacts on surface TACI expression and/or downstream signal transduction, indicating that relatively subtle variation in TACI activity can impact human B-cell biology. However, significant complexity underlies TACI biology, including both positive and negative regulation of physiologic and pathogenic B-cell responses. To model these contradictory events, we compared the functional impact of TACI deletion on separate models of murine SLE driven by T cell-independent and -dependent breaks in B-cell tolerance. First, we studied whether reduced surface TACI expression was sufficient to protect against progressive BAFF-mediated systemic autoimmunity. Strikingly, despite a relatively modest impact on surface TACI levels, TACI haploinsufficiency markedly reduced pathogenic RNA-associated autoantibody titers and conferred long-term protection from BAFF-driven lupus nephritis. In contrast, B cell-intrinsic TACI deletion exerted a limited impact of autoantibody generation in murine lupus characterized by spontaneous germinal center formation and T cell-dependent humoral autoimmunity. Together, these combined data provide new insights into TACI biology and highlight how TACI signals must be tightly regulated during protective and pathogenic B-cell responses.

Lack of standardisation in interpretation and reporting of autoantibody assays: a survey analysis of Australasian laboratories with focus on line immunoassays

Autoantibody assays are reported in a variety of formats. Results only slightly above established cut-offs provide lower likelihood ratios; therefore, their clinical significance may be more uncertain, which is not readily communicated with dichotomous qualitative reporting. Line immunoassays (LIA) are a common method for detecting antibodies to extractable nuclear antigens (ENA) and myositis-associated antibodies. However, recommended positive cut-offs are contentious. We distributed a survey via e-mail to participants in the Royal College of Pathologists of Australasia Quality Assurance Program (RCPAQAP) Immunology modules and to a dedicated immunology mailing list in Australasia. Questions explored general viewpoints surrounding autoantibody reporting, as well as current laboratory practices, with particular focus on interpretation and reporting of the most commonly used ENA LIA manufactured by Euroimmun. There were 31 responders, representative of at least 17 unique laboratories across Australia (8 public, 5 private) and New Zealand (4 laboratories). Responses suggest that autoantibody reporting is not standardised; there was variation in general viewpoints and reporting practices, particularly regarding the interpretation of and positive cut-offs used for the Euroimmun ENA LIA, which were contrary to the manufacturer's guidelines in a majority of the responses. Interpretative qualitative reporting based on results from other investigations and the clinical history was a common theme. There is large variation in the reporting of autoantibody assays within Australasia, especially by LIA. A majority of respondents report the most commonly used ENA LIA contrary to manufacturer's guidelines; alternative positive cut-offs are commonly utilised. LIA reports should indicate the level of positivity to enhance their relevance in the clinical decision-making process.

Urine β-2-glycoprotein 1 as a biomarker for diagnosis of systemic lupus erythematosus

OBJECTIVE

The need for a biomarker with robust sensitivity and specificity in diagnosing systemic lupus erythematosus (SLE) remains unmet. Compared with blood samples, urine samples are more easily collected; thus, we aimed to identify such a biomarker based on urinary proteomics which could distinguish patients with SLE from healthy controls (HCs).

METHODS

Urine samples were collected from 76 SLE patients who visited rheumatology clinic in 2019 at Asan medical center and from 25 HCs. Urine proteins were analyzed using sequential windowed acquisition of all theoretical fragment ion spectra-mass spectrometry, and the candidate marker was confirmed by enzyme-linked immunosorbent assay (ELISA). Receiver operating characteristic curve analysis was used to determine the diagnostic value of the candidate biomarker.

RESULTS

Of 1157 proteins quantified, 153 were differentially expressed in urine samples from HCs. Among them were previously known markers including α-1-acid glycoprotein 1, α-2-HS-glycoprotein, ceruloplasmin, and prostaglandin-H2 D-isomerase. Moreover, the amount of β-2 glycoprotein (APOH) was increased in the urine of patients with SLE. The ELISA results also showed the level of urine APOH was higher in patients with SLE than in HCs and patients with rheumatoid arthritis. Moreover, the level was not different between SLE patients with and without nephritis. The urine APOH had an area under the curve value of 0.946 at a cut-off value of 228.53 ng/mg (sensitivity 91.5%, specificity 92.0%) for the diagnosis of SLE.

CONCLUSION

The results indicate that the urine APOH level can be an appropriate screening tool in a clinical setting when SLE is suspected.

Serum syndecan-1, hyaluronan and thrombomodulin levels in patients with lupus nephritis

OBJECTIVES

We investigated circulating syndecan-1, HA and thrombomodulin levels in patients with biopsy-proven Class III/IV ± V LN and their clinico-pathological associations. Patients with non-renal SLE or non-lupus chronic kidney disease, and healthy subjects served as controls.

METHODS

Serum syndecan-1, HA and thrombomodulin levels were determined by ELISAs.

RESULTS

Syndecan-1, HA and thrombomodulin levels were significantly higher during active LN compared with remission (P < 0.01, for all), and correlated with the level of proteinuria, estimated glomerular filtration rate, anti-dsDNA antibodies, complement 3 and serum creatinine. Longitudinal studies showed that syndecan-1 and thrombomodulin levels increased prior to clinical renal flare by 3.6 months, while HA level increased at the time of nephritic flare, and the levels decreased in parallel with treatment response. Receiver operating characteristic curve analysis showed that syndecan-1 and thrombomodulin levels distinguished patients with active LN from healthy subjects, LN patients in remission, patients with active non-renal lupus and patients with non-lupus chronic kidney disease (receiver operating characteristic area under curve of 0.98, 0.91, 0.82 and 0.95, respectively, for syndecan-1; and area under curve of 1.00, 0.84, 0.97 and 0.79, respectively, for thrombomodulin). HA level distinguished active LN from healthy subjects, LN patients in remission and non-lupus chronic kidney disease (receiver operating characteristic area under curve of 0.82, 0.71 and 0.90, respectively) but did not distinguish between renal vs non-renal lupus. Syndecan-1 and thrombomodulin levels correlated with the severity of interstitial inflammation, while HA level correlated with chronicity grading in kidney biopsies of active LN.

CONCLUSION

Our findings suggest potential utility of serum syndecan-1, thrombomodulin and HA levels in clinical management, and their potential contribution to LN pathogenesis.

Clinico-pathological associations of serum VCAM-1 and ICAM-1 levels in patients with lupus nephritis

OBJECTIVE

We investigated the clinico-pathological associations of serum VCAM-1 and ICAM-1 levels in patients with biopsy-proven Class III/IV±V lupus nephritis (LN).

METHODS

Serum VCAM-1 and ICAM-1 levels were determined by ELISAs. Sera from patients with non-renal SLE or non-lupus chronic kidney disease (CKD), and healthy subjects served as controls.

RESULTS

Seropositivity rate for VCAM-1 and ICAM-1 was 93.10% and 37.93% respectively at the time of nephritic flare, and 44.83% and 13.79% respectively at remission, with both showing higher levels during flare (P < 0.05, for both). VCAM-1 level correlated with proteinuria, serum creatinine, and anti-dsDNA antibodies, and inversely correlated with C3. VCAM-1 level also correlated with leukocyte infiltration and fibrinoid necrosis/karyorrhexis scores in active LN kidney biopsies. ICAM-1 level correlated with proteinuria, but not anti-dsDNA or C3, nor histopathological features. VCAM-1 level increased 4.5 months before renal flare, while ICAM-1 increase coincided with flare, and both decreased after treatment. ROC analysis showed that VCAM-1 distinguished active LN from healthy subjects, LN in remission, active non-renal lupus, and CKD (ROC AUC of 0.98, 0.86, 0.93 and 0.90 respectively). VCAM-1 level in combination with either proteinuria or C3 was superior in distinguishing active LN from remission compared to the measurement of individual markers. Serum ICAM-1 level distinguished active LN from healthy subjects and LN patients in remission (ROC AUC of 0.75 and 0.66 respectively), but did not distinguish between renal versus non-renal lupus. ICAM-1 level in combination with markers of endothelial cell activation (syndecan-1, hyaluronan and thrombomodulin) was superior to proteinuria, anti-dsDNA, or C3 in distinguishing active LN from quiescent disease.

CONCLUSION

Our findings suggest potential utility of serum VCAM-1 and ICAM-1 in clinical management. Monitoring VCAM-1 may facilitate early diagnosis of flare. Combining selected biomarkers may be advantageous in diagnosing active LN. VCAM-1 may have a pathogenic role in renal parenchymal inflammation in active LN.

Neutrophils in the Pathogenesis of Rheumatoid Arthritis and Systemic Lupus Erythematosus: Same Foe Different M.O

Dysregulated neutrophil activation contributes to the pathogenesis of autoimmune diseases including rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE). Neutrophil-derived reactive oxygen species (ROS) and granule proteases are implicated in damage to and destruction of host tissues in both conditions (cartilage in RA, vascular tissue in SLE) and also in the pathogenic post-translational modification of DNA and proteins. Neutrophil-derived cytokines and chemokines regulate both the innate and adaptive immune responses in RA and SLE, and neutrophil extracellular traps (NETs) expose nuclear neoepitopes (citrullinated proteins in RA, double-stranded DNA and nuclear proteins in SLE) to the immune system, initiating the production of auto-antibodies (ACPA in RA, anti-dsDNA and anti-acetylated/methylated histones in SLE). Neutrophil apoptosis is dysregulated in both conditions: in RA, delayed apoptosis within synovial joints contributes to chronic inflammation, immune cell recruitment and prolonged release of proteolytic enzymes, whereas in SLE enhanced apoptosis leads to increased apoptotic burden associated with development of anti-nuclear auto-antibodies. An unbalanced energy metabolism in SLE and RA neutrophils contributes to the pathology of both diseases; increased hypoxia and glycolysis in RA drives neutrophil activation and NET production, whereas decreased redox capacity increases ROS-mediated damage in SLE. Neutrophil low-density granulocytes (LDGs), present in high numbers in the blood of both RA and SLE patients, have opposing phenotypes contributing to clinical manifestations of each disease. In this review we will describe the complex and contrasting phenotype of neutrophils and LDGs in RA and SLE and discuss their discrete roles in the pathogenesis of each condition. We will also review our current understanding of transcriptomic and metabolomic regulation of neutrophil phenotype in RA and SLE and discuss opportunities for therapeutic targeting of neutrophil activation in inflammatory auto-immune disease.

The Role of Natural Killer Cells in Autoimmune Diseases

Natural killer (NK) cells, the large granular lymphocytes differentiated from the common lymphoid progenitors, were discovered in early 1970's. They are members of innate immunity and were initially defined by their strong cytotoxicity against virus-infected cells and by their important effector functions in anti-tumoral immune responses. Nowadays, NK cells are classified among the recently discovered innate lymphoid cell subsets and have capacity to influence both innate and adaptive immune responses. Therefore, they can be considered as innate immune cells that stands between the innate and adaptive arms of immunity. NK cells don't express T or B cell receptors and are recognized by absence of CD3. There are two major subgroups of NK cells according to their differential expression of CD16 and CD56. While CD16+CD56dim subset is best-known by their cytotoxic functions, CD16-CD56bright NK cell subset produces a bunch of cytokines comparable to CD4+ T helper cell subsets. Another subset of NK cells with production of interleukin (IL)-10 was named as NK regulatory cells, which has suppressive properties and could take part in immune-regulatory responses. Activation of NK cells is determined by a delicate balance of cell-surface receptors that have either activating or inhibitory properties. On the other hand, a variety of cytokines including IL-2, IL-12, IL-15, and IL-18 influence NK cell activity. NK-derived cytokines and their cytotoxic functions through induction of apoptosis take part in regulation of the immune responses and could contribute to the pathogenesis of many immune mediated diseases including ankylosing spondylitis, Behçet's disease, multiple sclerosis, rheumatoid arthritis, psoriasis, systemic lupus erythematosus and type-1 diabetes. Dysregulation of NK cells in autoimmune disorders may occur through multiple mechanisms. Thanks to the rapid developments in biotechnology, progressive research in immunology enables better characterization of cells and their delicate roles in the complex network of immunity. As NK cells stand in between innate and adaptive arms of immunity and "bridge" them, their contribution in inflammation and immune regulation deserves intense investigations. Better understanding of NK-cell biology and their contribution in both exacerbation and regulation of inflammatory disorders is a requisite for possible utilization of these multi-faceted cells in novel therapeutic interventions.

Circulating Free DNA and Its Emerging Role in Autoimmune Diseases

Liquid biopsies can be used to analyse tissue-derived information, including cell-free DNA (cfDNA), circulating rare cells, and circulating extracellular vesicles in the blood or other bodily fluids, representing a new way to guide therapeutic decisions in cancer. Among the new challenges of liquid biopsy, we found clinical application in nontumour pathologies, including autoimmune diseases. Since the discovery of the presence of high levels of cfDNA in patients with systemic lupus erythaematosus (SLE) in the 1960s, cfDNA research in autoimmune diseases has mainly focused on the overall quantification of cfDNA and its association with disease activity. However, with technological advancements and the increasing understanding of the role of DNA sensing receptors in inflammation and autoimmunity, interest in cfDNA and autoimmune diseases has not expanded until recently. In this review, we provide an overview of the basic biology of cfDNA in the context of autoimmune diseases as a biomarker of disease activity, progression, and prediction of the treatment response. We discuss and integrate available information about these important aspects.