Plasma Of Systemic Lupus Erythematosus Patients Research Articles

Quantitative proteomic analysis and replacement therapy identifies haptoglobin as a therapeutic target in a murine model of SLE-associated diffuse alveolar hemorrhage.

Diffuse alveolar hemorrhage (DAH) is a catastrophic clinical syndrome and one of the manifestations of pulmonary involvement in systemic lupus erythematosus (SLE), which is characterized by hemoptysis, diffuse pulmonary infiltrates, and respiratory failure. However, the treatment options for DAH remain limited, and DAH-related studies are needed to explore more effective therapeutic directions for better disease management and improved prognosis. This study utilized the pristane-induced DAH murine model to mimic the pathological process of DAH in patients with SLE. Proteomic analysis was conducted to detect differentially expressed proteins (DEPs) in the plasma of surviving and non-surviving mice, followed by an analysis of biological functions and pathways. The most significant DEP was then confirmed in the plasma of SLE patients with or without DAH and DAH murine model with or without fatal outcomes. Finally, the therapeutic value of haptoglobin (Hp) replacement was validated in a DAH murine model through lung histopathology, RT-qPCR, and survival analysis. This study identified 178 DEPs, with 118 upregulated and 60 downregulated DEPs in the non-survival group. Within a set of notable Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways, complement and coagulation cascades emerged as the most prominent pathway associated with the process of DAH. Later, the most significant DEP, haptoglobin (Hp), was confirmed to exhibit a significant decrease in the plasma of individuals with SLE-DAH and DAH murine model with poor outcomes by the ELISA test. Finally, compared with the control group, the severity of DAH in the Hp treatment group was alleviated significantly, as manifested by the decreased levels of pro-inflammatory cytokines (IL-6 and TNF-α), increased levels of anti-inflammatory cytokines (IL-10 and TGF-β), and decreased mortality. A reduction in plasma Hp levels was observed in SLE-DAH, and the replacement therapy with Hp could alleviate pulmonary hemorrhage and reduce mortality in DAH mice. This study identified Hp as a potential biomarker for its clinical diagnosis and a direction for treatment.

Increased levels of sirtuin-1 in systemic lupus erythematosus.

We investigated plasma sirtuin-1 (SIRT1) levels in systemic lupus erythematosus (SLE) patients, and discussed potential of plasma SIRT1 as a biomarker for SLE. A total of 359 subjects, including 299 patients (89 SLE, 50 rheumatoid arthritis, 30 osteoarthritis, 30 gout, 38 Sjögren's syndrome, 20 ankylosing spondylitis, 30 mixed connective tissue disease, 12 systemic sclerosis) and 60 healthy controls were recruited. SIRT1 in plasma of SLE patients was detected by enzyme-linked immunosorbent assay. Relationship between SIRT1 levels, clinical, laboratory characteristics in SLE patients was discussed. Plasma SIRT1 to discriminate SLE from different rheumatic patients and healthy controls was assessed by receiver operating characteristic (ROC) curve analysis. SIRT1 levels were elevated in SLE patients compared with healthy controls (6.28 [5.89-6.68] vs 2.42 [2.10-2.74] ng/mL, P < .001). SIRT1 concentration in plasma was significantly associated with disease activity (rs =.317, P < .001). Area under the ROC curve (AUC) analysis showed that compared to healthy controls, SIRT1 had a good ability for diagnosis of SLE (AUC=0.986, P < .001). Compared with rheumatoid arthritis, osteoarthritis, Sjögren's syndrome, ankylosing spondylitis, mixed connective tissue disease and systemic sclerosis patients, the AUC of plasma SIRT1 in SLE patients was 0.982, 0.881, 0.810, 0.860, 0.781, 0.889, 0.736, respectively. When evaluating the discriminative power of SIRT1, the sensitivity and specificity for distinguishing SLE from non-SLE patients were 95.51%, 61.43%, respectively, at the optimal cut-off value of 4.323 ng/mL. Circulating SIRT1 was elevated in SLE, and might be a promising SLE diagnostic marker.

The Interleukin-1 Receptor-Associated Kinase 4 Inhibitor PF-06650833 Blocks Inflammation in Preclinical Models of Rheumatic Disease and in Humans Enrolled in a Randomized Clinical Trial.

ObjectiveTo investigate the role of PF‐06650833, a highly potent and selective small‐molecule inhibitor of interleukin‐1–associated kinase 4 (IRAK4), in autoimmune pathophysiology in vitro, in vivo, and in the clinical setting.MethodsRheumatoid arthritis (RA) inflammatory pathophysiology was modeled in vitro through 1) stimulation of primary human macrophages with anti–citrullinated protein antibody immune complexes (ICs), 2) RA fibroblast‐like synoviocyte (FLS) cultures stimulated with Toll‐like receptor (TLR) ligands, as well as 3) additional human primary cell cocultures exposed to inflammatory stimuli. Systemic lupus erythematosus (SLE) pathophysiology was simulated in human neutrophils, dendritic cells, B cells, and peripheral blood mononuclear cells stimulated with TLR ligands and SLE patient ICs. PF‐06650833 was evaluated in vivo in the rat collagen‐induced arthritis (CIA) model and the mouse pristane‐induced and MRL/lpr models of lupus. Finally, RNA sequencing data generated with whole blood samples from a phase I multiple‐ascending‐dose clinical trial of PF‐06650833 were used to test in vivo human pharmacology.ResultsIn vitro, PF‐06650833 inhibited human primary cell inflammatory responses to physiologically relevant stimuli generated with RA and SLE patient plasma. In vivo, PF‐06650833 reduced circulating autoantibody levels in the pristane‐induced and MRL/lpr murine models of lupus and protected against CIA in rats. In a phase I clinical trial (NCT02485769), PF‐06650833 demonstrated in vivo pharmacologic action pertinent to SLE by reducing whole blood interferon gene signature expression in healthy volunteers.ConclusionThese data demonstrate that inhibition of IRAK4 kinase activity can reduce levels of inflammation markers in humans and provide confidence in the rationale for clinical development of IRAK4 inhibitors for rheumatologic indications.

AB0081 ENDOTHELIAL MARKERS WITH DYSREGULATION IN SYSTEMIC LUPUS ERYTHEMATOSUS: A SYSTEMATIC LITERATURE REVIEW

Background:Systemic lupus erythematosus (SLE) is a severe, lifelong autoimmune disease known for its multisystem organ involvement. SLE patients are known to be at risk for premature atherosclerosis at a relatively young age (1). Endothelial dysregulation is one of the pathophysiologic mechanisms that can lead to the higher risk for cardiovascular disease in SLE (2). Multiple endothelial markers with dysregulation in SLE have been described so far, of which some are associated with disease activity.Objectives:To report a systematic literature review regarding endothelial markers that are dysregulated in SLE and search for associations with disease activity.Methods:The search was performed according to the Preferred Reporting Items for Systematic review and Meta-analysis Protocols (PRISMA-P) 2015 (3). In July 2020, the search terms were used in Embase, MEDLINE, Web of Science, Google Scholar and Cochrane. Inclusion criteria were 1) published studies after the year 2000 that reported measurements of endothelial cell markers in serum and/or plasma of SLE patients (diagnosed according to ACR/SLICC criteria), 2) English language peer reviewed articles and 3) disease activity measurement (i.e. SLEDAI, BILAG, SLAM, ECLAM or PGA). Exclusion criteria were 1) case reports or editorials, 2) studies performed in animals and 3) studies with microRNA/cytokine biomarkers. There was no minimum count for study population. The screening process is shown in figure 1.Results:From 1892 hits, we identified 110 eligible articles. Table 1 shows an overview of the most frequently studied endothelial markers. These identified endothelial markers are involved in endothelial cell (EC) activation, EC apoptosis, disturbed angiogenesis, defective vascular tone control, immune dysregulation and coagulopathy. In most studies, dysregulation of the endothelial marker was associated with disease activity. The majority of the studies had a cross-sectional design, longitudinal data on endothelial markers in SLE are scarce.Conclusion:We identified multiple endothelial markers that are dysregulated in SLE and this dysregulation was often associated with disease activity in cross-sectional studies. Our future plan is to test the identified endothelial markers in (longitudinally collected) samples of (childhood onset) SLE patients, disease- and healthy controls. This will be a next step in unravelling the pathophysiology of premature atherosclerosis and cardiovascular events in SLE-patients in young adulthood.Figure 1.

Application of LC-MS/MS method for determination of dihydroartemisin in human plasma in a pharmacokinetic study.

Aim: Dihydroartemisinin (DHA) was also found therapeutic potential for the treatment of systemic lupus erythematosus (SLE). To assess the pharmacokinetic profile of DHA, the concentration of DHA in plasma of SLE patients needed be accurately determined based on a rapid and reliable analytical method. Experimental method & results: Developed method utilizes stable isotope-labeled internal standards and SPEmethod for sample preparation, applied XBridge C18 column (2.1×50mm, 3.5μm) for chromatography separation. Detection of the analytes was achieved by an AB Sciex 4000 mass spectrometer under positive electrospray ionization mode. The method was validated in accordance with international guidelines on bioanalytical methods validations. Conclusion: DHA concentrations in human plasma of Chinese SLEpatients were quantified by developed LC-MS/MS (no. 2016L02562).

Persistent Bacteriuria and Antibodies Recognizing Curli/eDNA Complexes From Escherichia coli Are Linked to Flares in Systemic Lupus Erythematosus.

Infections contribute to morbidity and mortality in systemic lupus erythematosus (SLE). Uropathogenic Escherichia coli (UPEC) are known to trigger urinary tract infections (UTIs) and form biofilms, which are multicellular communities of bacteria that are strengthened by amyloids such as curli. We previously reported that curli naturally form complexes with bacterial extracellular DNA (eDNA), and these curli/eDNA complexes induce hallmark features of lupus in mouse models. The present study was undertaken to investigate whether anti-curli/eDNA complex antibodies play a role in the pathogenesis of SLE or development of flares in SLE. In total, 96 SLE patients who met at least 4 Systemic Lupus International Collaborating Clinics disease criteria were investigated. Anti-curli/eDNA complex antibodies in the plasma were tested for both IgG and IgA subclasses. Results were compared to that in 54 age-, sex-, and race/ethnicity-matched healthy controls. Correlations of the levels of anti-curli/eDNA antibodies with clinical parameters, lupus disease status, and frequency of bacteriuria were assessed. Anti-curli/eDNA antibodies were detected in the plasma of SLE patients and healthy controls, and their levels correlated with the presence of asymptomatic persistent bacteriuria and occurrence of disease flares in lupus patients. Persistent bacteriuria contained curli-producing UPEC, and this was associated with an inflammatory phenotype. Finally, curli/eDNA complexes cross-reacted with lupus autoantigens, such as double-stranded DNA, in binding autoantibodies. These results suggest that UTIs and persistent bacteriuria are environmental triggers of lupus and its flares. Antibodies against curli/eDNA could serve as a sign of systemic exposure to bacterial products in SLE.

Role of Low-Density Lipoprotein in Early Vascular Aging Associated With Systemic Lupus Erythematosus.

Patients with systemic lupus erythematosus (SLE) often have atherosclerotic complications at a young age but normal low-density lipoprotein (LDL) levels. This study was undertaken to investigate the role of LDL composition in promoting early vascular aging in SLE patients. Plasma LDL from 45 SLE patients (SLE-LDL) and from 37 normal healthy controls (N-LDL) was chromatographically divided into 5 subfractions (L1-L5), and the subfraction composition was analyzed. Correlations between subfraction levels and signs of early vascular aging were assessed. Mechanisms of lipid-mediated endothelial dysfunction were explored using in vitro assays and experiments in apoE-/- mice. The L5 percentage was increased 3.4 times in the plasma of SLE patients compared with normal controls. This increased percentage of SLE-L5 was positively correlated with the mean blood pressure (r = 0.27, P = 0.04), carotid intima-media thickness (IMT) (right carotid IMT, r = 0.4, P = 0.004; left carotid IMT, r = 0.36, P = 0.01), pulse wave velocity (r = 0.29, P = 0.04), and blood levels of CD16+ monocytes (r = 0.35, P = 0.004) and CX3CL1 cytokines (r = 0.43, P < 0.001) in SLE patients. Matrix-assisted laser desorption ionization-time-of-flight mass spectrometry analysis revealed that plasma levels of lysophosphatidylcholine (LPC) and platelet-activating factor (PAF) were increased in SLE-LDL and in the SLE-L5 plasma subfraction. Injecting SLE-LDL, SLE-L5, or LPC into young, male apoE-/- mice caused increases in plasma CX3CL1 levels, aortic fatty-streak areas, aortic vascular aging, and macrophage infiltration into the aortic wall, whereas injection of N-LDL or SLE-L1 had negligible effects (n = 3-8 mice per group). In vitro, SLE-L5 lipid extracts induced increases in CX3CR1 and CD16 expression in human monocytes; synthetic PAF and LPC had similar effects. Furthermore, lipid extracts of SLE-LDL and SLE-L5 induced the expression of CX3CL1 and enhanced monocyte-endothelial cell adhesion in assays with bovine aortic endothelial cells. An increase in plasma L5 levels, not total LDL concentration, may promote early vascular aging in SLE patients, leading to premature atherosclerosis.

Techniques of modifying lipid antigens for synthesis of diagnostic and therapeutic preparations in rheumatology.

The objective of the study is to enhance sorption capacity of diagnostic agents by using cardiolipin antigens for antiphospholipid syndrome in patients with systemic lupus erythematosus (SLE). A technique of emulsion polimerization was used. Having integrated antigen nanoobjects we developed immobilized magnetocontrollable antigen nanosystems and put them to an evaluation test. The nanosystems are polyacrylamide granules with a built in antigen. To obtain stable immobilized multi-use biopharmaceuticals with targeted properties (shape, particle diameter, pore size, density) we used a modified version of emulsion polymerization method using polyacrylamide carrier gel. This method permitted a greater sorptive capacity, preserving the antigen in maximum native state, and opened up the possibility of controllable modification of nanoobjects. Cardiolipin was used as the antigen in question. Following the method described above we performed sorption of anticardiolipin antibodies from blood plasma of SLE patients who showed clinical presentations of antiphospholipid syndrome. All SLE patoents with signs of antiphospholipid syndrome showed reliably higher levels of cardiolipin antibodies compared with SLE patients without antiphospholipid syndrome signs; the antibody level was 0.365 ± 0.026 and 0.075 ± 0.003 on average, correspondingly (p < 0.001). Blood serum from 10 apparently healthy individuals served as control. The level of cardiolipin antibodies was determined before and after sorption by indirect solid phase immunoenzyme method. In the eluate we estimated total protein by Lowry method. In vitro testing showed that the obtained antigen nanosystems based on immobilized cardiolipin could effectively remove cardiolipin antibodies from whole blood of SLE patients with clinical presentations of APS to achieve the values of healthy individuals (before sorption cardiolipin antibodies 0.328 ± 0.0289; after sorption 0.059 ± 0.0170; p<0,001; sorption capacity 8.00 ± 0.390 mg/ml). The method of emulsion polymerization with consideration to hydrophobic and hydrophilic properties of lipid molecules permits obtaining and modifying biomolecules with certain properties, in a controlled fashion.

Lytic Susceptibility, Structure, and Mechanical Properties of Fibrin in Systemic Lupus Erythematosus.

Among complications of systemic lupus erythematosus (SLE), thrombotic events are relatively common and contribute significantly to the morbidity and mortality rates. An increased risk of thrombosis in various diseases has been shown to be associated with the lytic stability and mechanical stiffness of the fibrin clot determined by its structure. Here we studied alterations of the fibrin clot properties in relation to disease severity in SLE patients. Plasma clots from 28 SLE patients were characterized by the kinetics of formation and fibrinolytic dissolution (using dynamic turbidimetry), the network and fiber ultrastructure (scanning electron microscopy), viscoelasticity (shear rheometry), and the rate and degree of crosslinking (Western blotting) correlated with the disease activity, blood composition, and compared to clotting of pooled normal human plasma. Clots made from plasma of SLE patients were lysed faster with exogenous t-PA than control clots from normal plasma without a significant difference between those from active (SLEDAI>4) and inactive (SLEDAI<4) SLE patients. Clots from the blood of patients with active SLE were characterized by significantly slower onset, but faster rate of fibrin polymerization and a higher optical density due to thicker fibers compared to those from inactive SLE and control pooled normal plasma. The rheological parameters of the clots (storage and loss moduli) were significantly increased in the active SLE patients along with enhanced fibrin crosslinking and hyperfibrinogenemia. The structural and rheological alterations displayed a strong positive correlation with high fibrinogen levels and other laboratory markers of immune inflammation. In conclusion, changes in the blood composition associated with active systemic inflammation in SLE cause significant alterations in the lytic resistance of fibrin clots associated with changes in polymerization kinetics, viscoelastic properties, and structure. The formation of more rigid prothrombotic fibrin clots in the plasma of SLE patients is likely due to the inflammatory hyperfibrinogenemia and greater extent of crosslinking. However, the higher susceptibility of the SLE clots to fibrinolysis may be a protective and/or compensatory mechanism that reduces the risk of thrombotic complications and improves patient outcomes.

B Cell-Related Circulating MicroRNAs With the Potential Value of Biomarkers in the Differential Diagnosis, and Distinguishment Between the Disease Activity and Lupus Nephritis for Systemic Lupus Erythematosus.

Our understanding of circulating microRNAs (miRNAs) related to systemic lupus erythematosus (SLE) remains very limited. In this study, we screened SLE-specific miRNAs in plasma from 42 B cell-related miRNAs by using miRNA PCR Array. The selected miRNAs were first confirmed in plasma samples from 50 SLE patients, 16 rheumatoid arthritis (RA) patients, and 20 healthy donors using qRT-PCR. We then investigated the relationship between expressions of the selected miRNAs and SLE clinical indicators. As a result, 14 miRNAs (miR-103, miR-150, miR-20a, miR-223, miR-27a, miR-15b, miR-16, miR-181a, miR-19b, miR-22, miR-23a, miR-25, miR-92a, and miR-93) were significantly decreased in the plasma of SLE patients compared with healthy controls (P < 0.05) and could act as the diagnostic signature to distinguish SLE patients from healthy donors. Six miRNAs (miR-92a, miR-27a, miR-19b, miR-23a, miR-223, and miR-16) expressed in plasma were significantly lower in SLE patients than in RA patients (P < 0.05), revealing the potentially diagnostic signature to distinguish SLE patients from RA patients. Furthermore, the downregulated expression of miR-19b, miR-25, miR-93, and miR-15b was associated with SLE disease activity (P < 0.05) while miR-15b and miR-22 expressions were significantly lower in SLE patients with low estimate glomerular filtration rate (eGFR < 60 ml/min/1.73 m2) (P < 0.05). The diagnostic potential of miR-15b for SLE disease activity and lupus nephritis (LN) with low eGFR was validated on an independent validation set with 69 SLE patients and a cross-validation set with 80 SLE patients. In summary, the signature of circulating miRNAs will provide novel biomarkers for the diagnosis of SLE and evaluation of disease activity and LN.

Exosome-delivered microRNAs promote IFN-α secretion by human plasmacytoid DCs via TLR7.

The excessive production of type I IFNs is a hallmark and a main pathogenic mechanism of many autoimmune diseases, including systemic lupus erythematosus (SLE). In these pathologies, the sustained secretion of type I IFNs is dependent on the improper activation of plasmacytoid DCs (pDCs) by self-nucleic acids. However, the nature and origin of pDC-activating self-nucleic acids is still incompletely characterized. Here, we report that exosomes isolated from the plasma of SLE patients can activate the secretion of IFN-α by human blood pDCs in vitro. This activation requires endosomal acidification and is recapitulated by microRNAs isolated from exosomes, suggesting that exosome-delivered microRNAs act as self-ligands of innate single-stranded endosomal RNA sensors. By using synthetic microRNAs, we identified an IFN induction motif that is responsible for the TLR7-dependent activation, maturation, and survival of human pDCs. These findings identify exosome-delivered microRNAs as potentially novel TLR7 endogenous ligands able to induce pDC activation in SLE patients. Therefore, microRNAs may represent novel pathogenic mediators in the onset of autoimmune reactions and potential therapeutic targets in the treatment of type I IFN-mediated diseases.

Frontline Science: Tim-3-mediated dysfunctional engulfment of apoptotic cells in SLE.

T cell Ig and mucin domain-containing molecule 3 (Tim-3) has been found to play important roles in autoimmune diseases, but whether Tim-3-mediated engulfment of apoptotic cells is involved in systemic lupus erythematosus (SLE) remains to be elucidated. In this study, we verified the role of human Tim-3 (hTim-3) as the receptor of phosphatidylserine (PS) in human embryonic kidney (HEK)293 cells, which initiated the engulfment of apoptotic cells. Both IgV and the mucin domain of Tim-3 were crucial in the phagocytosis of apoptotic cells, and there existed the key cytoplasmic domain for signal transduction. Alanine at 111, locating around the FG-CC' loop of hTim-3, was necessary for its engulfment of apoptotic cells. In accordance, Tim-3 on CD14+ cells negatively correlated with the percentage of peripheral apoptotic cells in control subjects. However, although Tim-3 was significantly increased on CD14+ cells in SLE patients, peripheral apoptotic cells remained much higher than those in control subjects. Tim-3 on CD14+ cells showed positive correlation with percentage of apoptotic cells and level of dsDNA, indicating the involvement of Tim-3 in SLE. Accordingly, soluble Tim-3 (sTim-3) was significantly increased in plasma of SLE patients, which might contribute to higher expression of a disintegrin and metalloproteinase (ADAM)-10. Pretreatment with both plasma from SLE patients and recombinant sTim-3 greatly inhibited hTim-3-initiated phagocytosis of apoptotic cells. Furthermore, anti-Tim-3 antibody depletion of plasma from SLE patients reversed the decreased phagocytosis of apoptotic cells. Collectively, our data suggest that sTim-3 might play inhibitory roles in impaired Tim-3-mediated clearance of apoptotic cells in SLE.

Excessive activation of the TLR9/TGF-\u03b21/PDGF-B pathway in the peripheral blood of patients with systemic lupus erythematosus

BackgroundOur aim is to study the existence of the TLR9/TGF-β1/PDGF-B pathway in healthy humans and patients with systemic lupus erythematosus (SLE), and to explore its possible involvement in the pathogenesis of lupus nephritis (LN).MethodsProtein levels of the cytokines were detected by ELISA. mRNA levels of the cytokines were analyzed by real-time PCR. MTT assay was used to test the proliferation of mesangial cells under different treatments.ResultsCompared to healthy controls (NControl = 56), levels of Toll-like receptor (TLR)9, transforming growth factor (TGF)-β1, and platelet-derived growth factor B (PDGF-B) were increased significantly in the peripheral blood of SLE patients (NSLE = 112). Significant correlations between the levels of TLR9, TGF-β1, and PDGF-B were observed in both healthy controls and SLE patients. The levels of TGF-β1 and PDGF-B were greatly enhanced by TLR9 activation in primary cell cultures. The proliferation of mesangial cells induced by the plasma of SLE patients was significantly higher than that induced by healthy controls; PDGF-B was involved in this process. The protein levels of PDGF-B homodimer correlated with the levels of urine protein in SLE patients with LN (NLN =38).ConclusionsThe TLR9/TGF-β1/PDGF-B pathway exists in humans and can be excessively activated in SLE patients. High levels of PDGF-B may result in overproliferation of mesangial cells in the kidney that are involved in the development of glomerulonephritis and LN. Further studies are necessary to identify TLR9, TGF-β1, and PDGF-B as new therapeutic targets to prevent the development of glomerulonephritis and LN.

Soluble MICB in Plasma and Urine Explains Population Expansions of NKG2D+CD4 T Cells Inpatients with Juvenile-Onset Systemic Lupus Erythematosus.

Abnormal NKG2D ligand expression has been implicated in the initiation and maintenance of various auto-inflammatory disorders including systemic lupus erythematosus (SLE). This study’s goal was to identify the cellular contexts providing NKG2D ligands for stimulation of the immunosuppressive NKG2D+CD4 T cell subset that has been implicated in modulating juvenile-onset SLE disease activity. Although previous observations with NKG2D+CD4 T cells in healthy individuals pointed towards peripheral B cell and myeloid cell compartments as possible sites of enhanced NKG2DL presence, we found no evidence for a disease-associated increase of NKG2DL-positivity among juvenile-onset SLE B cells and monocytes. However, juvenile-onset SLE patient plasma and matched urine samples were positive by ELISA for the soluble form of the NKG2D ligands MICA and MICB, suggesting that kidney and/or peripheral blood may constitute the NKG2DL positive microenvironments driving NKG2D+CD4 T cell population expansions in this disease.

Clinical Association of a Soluble Triggering Receptor Expressed on Myeloid Cells-1 (sTREM-1) in Patients with Systemic Lupus Erythematosus

ABSTRACTA triggering receptor expressed on myeloid cells-1 (TREM-1) is a member of the immunoglobulin superfamily with an established role in innate and adaptive immune response. We aimed to determine the plasma concentrations and clinical association of sTREM-1 in Systemic Lupus Erythematosus (SLE) patients. Plasma from 79 SLE patients and 35 normal healthy subjects were assayed for sTREM-1 and IL-6 levels using Enzyme Linked Immunosorbant Assay (ELISA). The clinical disease characteristics and serological data were prospectively assessed. Disease activity was scored using the SLE disease activity index. We detected significantly higher levels of sTREM-1 in plasma of SLE patients than the healthy control group. We also detected high sTREM-1 levels in subgroups of patients with neuropsychiatric manifestations (NPLE) and patients with the total high disease activity and NPLE activity. In addition, sTREM-l levels were significantly correlated with parameters of disease activity, i.e. SLEDAI score, IL-6, hypoalbuminemia. On the other hand, we did not find significant differences in sTREM-1 levels in relation to age, disease duration, medications, ESR, other organ system involvement, or the presence of anti-dsDNA. Our preliminary data indicated that sTREM-1 levels may be an additional useful marker of disease activity in SLE. It also highlights its importance in patients with NPLE. An additional prospective longitudinal study should be carried out to support these findings.

Circulating hsa-miR-30e-5p, hsa-miR-92a-3p, and hsa-miR-223-3p may be novel biomarkers in systemic lupus erythematosus.

MicroRNAs (miRNAs) are short, non-coding RNAs that regulate gene expression at the post-transcriptional level, which can be measured in cells, tissues, and body fluids including plasma. Differences in miRNA expression levels suggest an epigenetic mechanism and changed expression levels are emerging as a novel biomarker for various diseases. We attempted to identify circulating miRNAs associated with susceptibility to systemic lupus erythematosus (SLE) in the Korean population and elucidate their significance for clinical phenotype. An expression profiling analysis using miRNA polymerase chain reaction (PCR) array was conducted with pooled miRNA from 10 patients with SLE and 10 healthy controls (HCs). Nine miRNAs were differentially expressed between the SLE and HC. To verify this, we performed quantitative PCR for various miRNA from SLE patients (n = 70) and HCs (n = 40). The hsa-miR-30e-5p, hsa-miR-92a-3p, and hsa-miR-223-3p were significantly up-regulated in plasma of SLE patients (P = 0.048, P = 0.039, and P = 0.046, respectively). Especially, the hsa-miR-223-3p was significantly associated with oral ulcer (P < 0.001) and lupus anticoagulant (P = 0.031). Thus, plasma hsa-miR-30e-5p, hsa-miR-92a-3p, and hsa-miR-223-3p may be promising novel biomarkers in the diagnosis and clinical manifestation of SLE.

Chaperonin-containing T-complex Protein 1 Subunit ζ Serves as an Autoantigen Recognized by Human Vδ2 γδ T Cells in Autoimmune Diseases

Human γδ T cells recognize conserved endogenous and stress-induced antigens typically associated with autoimmune diseases. However, the role of γδ T cells in autoimmune diseases is not clear. Few autoimmune disease-related antigens recognized by T cell receptor (TCR) γδ have been defined. In this study, we compared Vδ2 TCR complementarity-determining region 3 (CDR3) between systemic lupus erythematosus (SLE) patients and healthy donors. Results show that CDR3 length distribution differed significantly and displayed oligoclonal characteristics in SLE patients when compared with healthy donors. We found no difference in the frequency of Jδ gene fragment usage between these two groups. According to the dominant CDR3δ sequences in SLE patients, synthesized SL2 peptides specifically bound to human renal proximal tubular epithelial cell line HK-2; SL2-Vm, a mutant V sequence of SL2, did not bind. We identified the putative protein ligand chaperonin-containing T-complex protein 1 subunit ζ (CCT6A) using SL2 as a probe in HK-2 cell protein extracts by affinity chromatography and liquid chromatography-electrospray ionization-tandem mass spectrometry analysis. We found CCT6A expression on the surface of HK-2 cells. Cytotoxicity of only Vδ2 γδ T cells to HK-2 cells was blocked by anti-CCT6A antibody. Finally, we note that CCT6A concentration was significantly increased in plasma of SLE and rheumatoid arthritis patients. These data suggest that CCT6A is a novel autoantigen recognized by Vδ2 γδ T cells, which deepens our understanding of mechanisms in autoimmune diseases.

Circulating Apoptotic Microparticles in Systemic Lupus Erythematosus Patients Drive the Activation of Dendritic Cell Subsets and Prime Neutrophils for NETosis.

Circulating chromatin-containing apoptotic material and/or neutrophil extracellular traps (NETs) have been proposed to be an important driving force for the antichromatin autoimmune response in patients with systemic lupus erythematosus (SLE). The aim of this study was to determine the exact nature of microparticles in the circulation of SLE patients and to assess the effects of the microparticles on the immune system. We analyzed microparticles isolated from the plasma of patients with SLE, rheumatoid arthritis (RA), and systemic sclerosis (SSc), as well as from healthy subjects. The effects of the microparticles on blood-derived dendritic cells (DCs) and neutrophils were assessed by flow cytometry, enzyme-linked immunosorbent assay, and immunofluorescence microscopy. In SLE patients, we identified microparticles that were highly positive for annexin V and apoptosis-modified chromatin that were not present in healthy subjects or in RA or SSc patients. These microparticles were mostly CD31+/CD45- (endothelial), partly CD45+/CD66b+ (granulocyte), and negative for B and T cell markers. Microparticles isolated from the plasma of SLE patients increased the expression of the costimulatory surface molecules CD40, CD80, CD83, and CD86 and the production of proinflammatory cytokines interleukin-6, tumor necrosis factor, and interferon-α by blood-derived plasmacytoid DCs (PDCs) and myeloid DCs (MDCs). SLE microparticles also primed blood-derived neutrophils for NETosis. Microparticles from healthy subjects and from RA or SSc patients exhibited no significant effects on MDCs, PDCs, and NETosis. Circulating microparticles in SLE patients include a population of apoptotic cell-derived microparticles that has proinflammatory effects on PDCs and MDCs and enhances NETosis. These results underline the important role of apoptotic microparticles in driving the autoimmune response in SLE patients.

Eryptosis as an Underlying Mechanism in Systemic Lupus Erythematosus-Related Anemia

Background: The progression of systemic lupus erythematosus (SLE) leads to anemia in patients, adversely affecting prognosis. The diverse causes of anemia may include excessive eryptosis or premature suicidal erythrocyte death characterized by cell shrinkage and phosphatidylserine (PS) exposure on the cell surface. The present study explored if SLE enhances eryptosis and the underlying mechanisms. Materials and Methods: Eryptosis was assessed using flow cytometry in healthy volunteers (n = 20) and anemic patients hospitalized for SLE (n = 22), for parameters including PS exposure, cell volume, cytosolic calcium ion (Ca²⁺) levels and reactive oxygen species (ROS) and ceramide abundance. These indicators were measured in erythrocytes of experimental subjects and erythrocytes treated with plasma from healthy volunteers or SLE patients. Results: The hemoglobin and hematocrit levels were significantly lower in anemic SLE patients than in healthy volunteers (***p<0.001, p<0.001, respectively). The percentage of PS-exposing erythrocytes was significantly higher in SLE patients than in healthy volunteers (p<0.001), accompanied by an increase in cytosolic Ca²⁺ levels, oxidative stress. The measurements of PS and Ca²⁺ levels were significantly higher in the erythrocytes of healthy volunteers following incubation in plasma of SLE patients than in plasma of healthy volunteers for 24h (***p<0.001, *p<0.05 respectively). Conclusion: Eryptosis is enhanced in SLE and may contribute to anemia. The probable underlying mechanisms may be an excessive formation of ROS in erythrocytes. Also, some plasma components may trigger eryptosis by increasing the cytosolic Ca²⁺ concentration.

Aberrant expression of regulatory cytokine IL-35 in patients with systemic lupus erythematosus.

This study characterizes an IL-35-mediated regulatory role in patients with systemic lupus erythematosus (SLE). Plasma of SLE patients and healthy controls (HCs) was analyzed for the concentrations of IL-35 and soluble gp130 by using ELISA. mRNA expression of IL-35 subunit (p35 and EBI3) and its receptor (gp130 and IL-12Rβ2) in peripheral blood mononuclear cells (PBMCs) was assessed by RT-qPCR. Flow cytometry was performed to evaluate the number of CD4(+)CD25(high)CD127(-)Treg cells and the expression of IL-35 receptor on the CD4+ helper (Th) cells and CD19+ B cells. Plasma collected from SLE patients and HCs was assayed for cytokine and chemokine expression by Luminex multiplex assay. Plasma IL-35 and soluble gp130 levels positively correlated with each other and were significantly higher in patients with severe SLE compared with HCs. Significantly higher levels of inflammatory cytokines/chemokines CCL2, CXCL8, IL-6, interferon (IFN)-γ, IL-10 and IL-17A were observed in plasma of SLE patients than HCs. mRNA levels of IL-35 and its receptor were significantly positively correlated in PBMCs from SLE patients and their levels were higher in SLE than HCs. The increase significantly correlated with changes in SLE Disease Activity Index (SLEDAI) (all p < 0.05). In addition, the number of Treg cells in severe and moderate SLE patients were both significantly lower than HCs, where the ratio of CD4(+)CD25(-)effector T cell %/CD4(+)CD25(high)CD127(-)Treg % was found to be significantly higher in severe SLE patients. Furthermore, the expression of gp130 on CD4+ Th cells and percentage of Tregs were positively correlated with each other, and both were negatively correlated with SLEDAI. Our findings indicate that high level of plasma IL-35 in active SLE patients expressed with low level of IL-35 receptor (gp130) on CD4+ Th cells. These data raise the possibility that the level of IL-35 expression in SLE patients is not sufficient to induce the production of CD4(+)CD25(high)CD127(-)Tregs, and subsequently suppress the release of inflammatory cytokines and chemokines upon inflammation.