A systemic lupus erythematosus gene expression array in disease diagnosis and classification: a preliminary report

Similarity and difference between systemic lupus erythematosus and NZB/W F1 mice by multi-omics analysis

OBJECTIVES

Several animal disease models have been used to understand the mechanisms of systemic lupus erythematosus (SLE); however, the translation of findings from animals to humans has not been sufficiently examined in drug development. To confirm the validity of New Zealand black x New Zealand white (NZB/W) F1 mice as an SLE model, we extensively characterized SLE patients and NZB/W F1 mice by omics analysis.

METHODS

Peripheral blood from patients and mice and spleen and lymph node tissue from mice were analysed using cell subset analysis, cytokine panel assays, and transcriptome analysis.

RESULTS

CD4+ effector memory T cells, plasmablasts, and plasma cells were increased in both SLE patients and NZB/W F1 mice. Levels of tumor necrosis factor-α, interferon gamma induced protein-10, and B cell activating factor in plasma were significantly higher in SLE patients and NZB/W F1 mice than in their corresponding controls. Transcriptome analysis revealed an upregulation of genes involved in the interferon signalling pathway and T-cell exhaustion signalling pathway in both SLE patients and the mouse model. In contrast, death receptor signalling genes showed changes in the opposite direction between patients and mice.

CONCLUSION

NZB/W F1 mice are a generally suitable model of SLE for analysing the pathophysiology and treatment response of T/B cells and monocytes/macrophages and their secreted cytokines.

Comparison of Role of Hand and Wrist Ultrasound in Diagnosis of Subclinical Synovitis in Patients with Systemic Lupus Erythematosus and Rheumatoid Arthritis: A Retrospective, Single-Center Study

Background

This retrospective study aimed to compare the roles of hand and wrist ultrasound in diagnosing subclinical synovitis in patients with systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA) at a single center in Sichuan, China.

Material/Methods

Forty-one patients with SLE and 20 patients with RA were included. SLE was diagnosed using the American rheumatology Society (ACR) classification standard. Severity of SLE was evaluated using the SLE disease activity index (SLEDAI). General and clinical manifestations and laboratory indicators were measured. Spearman correlation analysis was used for analyzing correlations between musculoskeletal ultrasound results and indexes.

Results

Among 41 patients with SLE, 26 (63.4%) had joint pain, and 39 (95.1%) had at least 1 joint abnormality. Thirteen patients with SLE (31.7%) had wrist joint involvement, 7 (17.1%) had metacarpal phalangeal-1 (MCP1) involvement, 8 (19.5%) had MCP2 involvement, 17 (41.5%) had MCP3 involvement, 14 (34.1%) had MCP4 involvement, and 5 (12.2%) had MCP5 involvement. Meanwhile, 2 (4.8%) had proximal interphalangeal-1 (PIP1) involvement, 10 (24.4%) had PIP2 involvement, 17 (41.5%) had PIP3 involvement, 12 (29.3%) had PIP4 involvement, and 3 (7.3%) had PIP4 involvement. Twelve patients demonstrated knee joint involvement. MCP joints had the highest involvement frequency (P=0.003). The most frequently detected disease was synovitis, followed by tenosynovitis, joint effusion, and bone erosion. ESR (P=0.002), CRP (P=0.020), and SLEDAI (P=0.011) of patients with SLE with arthralgia were significantly higher compared to patients without arthralgia. In patients with RA, musculoskeletal ultrasound scores were correlated with erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), disease activity score-28 (DAS28), and interleukin-6 (IL-6). In patients with SLE, musculoskeletal ultrasound scores were correlated with double-stranded DNA (dsDNA), ribonucleoprotein (RNP), DAS28, and IL-6.

Conclusions

Musculoskeletal ultrasound is highly sensitive in evaluating subclinical synovitis in patients with SLE, and its score is positively correlated with dsDNA, RNP IL-6, and DAS28 in patients with SLE.

SLAMF6 clustering is required to augment T cell activation

The signaling lymphocytic activation molecule (SLAM) family is comprised of nine distinct receptors that are expressed exclusively on hematopoietic cells. Most of these transmembrane receptors are homotypic by nature and downstream signaling occurs when cells that express the same SLAM receptor interact. Previous studies have determined that anti-SLAMF6 antibodies can have a therapeutic effect in autoimmunity and cancer. However, little is known about the role of SLAMF6 in the adaptive immune responses and in order to utilize SLAMF6 interventional approaches, a better understanding of the biology of this receptor in T cell is warranted. Accordingly, the objective of our study was to investigate both functionally and structurally the role of SLAMF6 in T cell receptor (TCR) mediated responses. Biochemical and genetic experiments revealed that SLAMF6 was required for productive TCR downstream signaling. Interestingly, SLAMF6 ectodomain was required for its function, but not for its recruitment to the immunological synapse. Flow-cytometry analysis demonstrated that tyrosine 308 of the tail of SLAMF6 was crucial for its ability to enhance T cell function. Imaging studies revealed that SLAMF6 clustering, specifically with the TCR, resulted in dramatic increase in downstream signaling. Mechanistically, we showed that SLAMF6 enhanced T cell function by increasing T cell adhesiveness through activation of the small GTPase Rap1. Taken together SLAMF6 is an important regulator of T cell activation where both its ectodomain and its endodomain contribute differentially to T cell functions. Additional studies are underway to better evaluate the role of anti-SLAMF6 approaches in specific human diseases.

New insights into the immunopathogenesis of systemic lupus erythematosus

The aetiology of systemic lupus erythematosus (SLE) is multifactorial, and includes contributions from the environment, stochastic factors, and genetic susceptibility. Great gains have been made in understanding SLE through the use of genetic variant identification, mouse models, gene expression studies, and epigenetic analyses. Collectively, these studies support the concept that defective clearance of immune complexes and biological waste (such as apoptotic cells), neutrophil extracellular traps, nucleic acid sensing, lymphocyte signalling, and interferon production pathways are all central to loss of tolerance and tissue damage. Increased understanding of the pathogenesis of SLE is driving a renewed interest in targeted therapy, and researchers are now on the verge of developing targeted immunotherapy directed at treating either specific organ system involvement or specific subsets of patients with SLE. Accordingly, this Review places these insights within the context of our current understanding of the pathogenesis of SLE and highlights pathways that are ripe for therapeutic targeting.

A T cell gene expression panel for the diagnosis and monitoring of disease activity in patients with systemic lupus erythematosus

Systemic Lupus Erythematosus (SLE) remains a challenging disease to diagnose and follow, as no reliable biomarkers are known to date. We designed a gene expression panel with 40 genes known to play a role in SLE pathogenesis. We found that the combined expression of these genes in SLE T cells can accurately differentiate SLE from healthy individuals and patients with other autoimmune diseases. The accuracy of the test increased further (83%) when only three out of the initial genes (OAS2, CD70 and IL10) were used. A T cell score, calculated from the combined expression levels of these genes, correlated positively with various SLE activity markers in a cross-sectional cohort and in a few patients that were followed prospectively. These data showcase the usefulness of measuring mRNA levels of key molecules in diagnosing and following patients with SLE.

Systemic lupus erythematosus diagnostics in the 'omics' era

Systemic lupus erythematosus is a complex autoimmune disease affecting multiple organ systems. Currently, diagnosis relies upon meeting at least four out of eleven criteria outlined by the ACR. The scientific community actively pursues discovery of novel diagnostics in the hope of better identifying susceptible individuals in early stages of disease. Comprehensive studies have been conducted at multiple biological levels including: DNA (or genomics), mRNA (or transcriptomics), protein (or proteomics) and metabolites (or metabolomics). The 'omics' platforms allow us to re-examine systemic lupus erythematosus at a greater degree of molecular resolution. More importantly, one is hopeful that these 'omics' platforms may yield newer biomarkers for systemic lupus erythematosus that can help clinicians track the disease course with greater sensitivity and specificity.

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

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

Biomarkers in systemic lupus erythematosus: challenges and prospects for the future

The search for lupus biomarkers to diagnose, monitor, stratify, and predict individual response to therapy is currently more intense than ever before. This effort is essential for several reasons. First, epidemic overdiagnosis and underdiagnosis of lupus, even by certified rheumatologists, leads to errors in therapy with concomitant side effects which may be more serious than the disease itself. Second, identification of lupus flares remains as much an art as it is a science. Third, the capacity to stratify patients so as to predict those who will develop specific patterns of organ involvement is not currently possible but would potentially lead to preventive therapeutic strategies. Fourth, only one new drug for the treatment of lupus has been approved by the US Food and Drug Administration in over 50 years. A major obstacle in this pipeline is the dearth of biomarkers available to prove a patient has responded to an experimental therapeutic intervention. This review will summarize the challenges faced in the discovery and validation of lupus biomarkers, the most promising lupus biomarkers identified to date, and the promise of future directions.

Abnormalities of T cell signaling in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is an autoimmune disease resulting from a loss of tolerance to multiple self antigens, and characterized by autoantibody production and inflammatory cell infiltration in target organs, such as the kidneys and brain. T cells are critical players in SLE pathophysiology as they regulate B cell responses and also infiltrate target tissues, leading to tissue damage. Abnormal signaling events link to defective gene transcription and altered cytokine production, contributing to the aberrant phenotype of T cells in SLE. Study of signaling and gene transcription abnormalities in SLE T cells has led to the identification of novel targets for therapy.