From incomplete to complete systemic lupus erythematosus; A review of the predictive serological immune markers

Characterization of autoantibody profiles in clusters of systemic lupus erythematosus using a novel autoantigen discovery technology

Systemic lupus erythematosus (SLE) is a complex systemic autoimmune disease characterized by a wide range of clinical and immunologic manifestations, most prominently, the production of autoantibodies to nuclear components (ANAs). A previous study delineated four SLE patient clusters based on autoantibody expression to common antigens. To further assess autoantibody diversity within these clusters, we surveyed serum autoantibody expression using a novel autoantigen discovery technology, the Antigenome Platform. This phage-based system assesses serum antibody interactions with large protein fragments (up to 250 amino acids) spanning approximately 90% of the human genome. Bound autoantibody targets were identified through next-generation sequencing and robust bioinformatics and statistical analysis. Our study revealed 88, 49, 10, and 24 autoantibodies that expand the characterization of four SLE clusters, including 24 autoantibodies that characterize a cluster of patients lacking common autoantibodies by conventional assays. Further, some autoantibodies identified have potential links to patient disease features. Although SLE is characterized by antinuclear antibody expression, a significant proportion of autoantigens (ranging from 28% to 54%) in each cluster localized to the cytoplasm, which suggests extensive autoreactivity beyond targets in the cell nucleus that formed the original basis of clustering. This study identifies new markers to aid in the clustering and understanding of SLE disease subtypes and provides a rationale for elucidating autoantibody expression in SLE beyond antinuclear antibodies.

Low-density granulocytes and neutrophil extracellular trap formation are increased in incomplete systemic lupus erythematosus

OBJECTIVE

To investigate the proportion of low-density granulocytes (LDGs), circulating plasma neutrophil extracellular traps (NETs) and serum-induced NET formation in patients with incomplete SLE (iSLE) and SLE.

METHODS

LDGs were measured cross-sectionally in 18 iSLE patients, 11 SLE patients and 14 healthy controls (HCs), whereas circulating NETs and serum-induced NET formation were assessed in 35 iSLE patients, 41 SLE patients and 16 HCs. LDGs (CD14lowCD15+) were measured in peripheral blood mononuclear cells (PBMCs) using flow cytometry, and circulating plasma NETs were measured using anti-myeloperoxidase-DNA, anti-citrullinated histone H3 and anti-elastase-DNA complex ELISAs. Serum-induced NET formation was assessed by incubating healthy neutrophils with serum from iSLE patients, SLE patients or HCs and visualizing NETs with fluorescence microscopy.

RESULTS

Proportions of LDGs and circulating plasma NETs were similarly elevated in iSLE and SLE patients compared with those in HCs. Furthermore, patients under HCQ treatment had lower proportions of LDGs than those without. Serum from iSLE and SLE patients similarly induced NET formation in healthy neutrophils. In iSLE patients, myeloperoxidase-DNA complexes were correlated with proportions of age-associated B-cells, memory B-cells and negatively with naïve B-cells, while we did not find associations between measures of NETs or serum-induced NET formation and interferon score or clinical parameters.

CONCLUSION

These results show that neutrophil dysfunction, including higher proportions of LDGs, and increased NET formation, already occur in iSLE, similar to SLE, despite differences in disease manifestations. Thereby, neutrophil dysfunction may contribute to sustained exposure to autoantigens and autoreactivity in early stages of SLE.

Budd-Chiari Syndrome as an Initial Manifestation of Incomplete Systemic Lupus Erythematosus

This article describes a case of a 26-year-old female with a history of Evan's syndrome who presented with severe exertional dyspnoea and abdominal discomfort. The patient was diagnosed with chronic Budd-Chiari syndrome, a rare vascular disorder characterized by obstruction of the hepatic vein. We discuss the risk factors, the clinical manifestations, and diagnostic methods for Budd-Chiari syndrome, as well as the possible association with an underlying incomplete systemic lupus erythematosus. The importance of close follow-up and timely diagnosis for preventing disease progression and reducing mortality is emphasized. The article concludes by highlighting the need for further monitoring to identify any symptoms or signs suggesting a progression to complete lupus erythematosus.

LEARNING POINTS

Budd-Chiari syndrome can present as the initial manifestation of a broader autoimmune disorder such as incomplete systemic lupus erythematosus.Evan's syndrome, when associated with other thrombotic conditions like antiphospholipid syndrome, may indicate an underlying, evolving autoimmune process.Early recognition and management of incomplete lupus are crucial to prevent progression to a full-blown systemic lupus erythematosus and associated complications.

Immunoglobulin G/immunoglobulin M autoantibody ratios in incomplete systemic lupus erythematosus

OBJECTIVE

Immunoglobulin G (IgG) autoantibodies in systemic lupus erythematosus (SLE) are considered pathogenic, whereas immunoglobulin M (IgM) autoantibodies may have protective effects. The aim of this study was to identify whether IgG/IgM autoantibody ratios differ between patients with incomplete systemic lupus erythematosus (iSLE), patients with SLE, and healthy controls (HCs), and whether IgG/IgM autoantibody ratios relate to progression from iSLE to SLE.

METHOD

This prospective cohort study included 34 iSLE patients, 41 SLE patients, and 11 HCs. IgG and IgM anti-dsDNA, anti-Ro52, and anti-Ro60 were measured by fluoro-enzyme immunoassay in serum samples obtained at baseline in all groups and in follow-up samples of up to 5 years for iSLE patients. Correlations between IgG/IgM autoantibody ratios, interferon signature, and clinical parameters were also assessed.

RESULTS

At baseline, IgG anti-dsDNA, anti-Ro52, anti-Ro60, and IgM anti-dsDNA were elevated in iSLE and SLE patients. IgG/IgM anti-dsDNA and anti-Ro52 ratios were similar between groups, while IgG/IgM anti-Ro60 ratios were significantly elevated in iSLE and SLE patients compared to HCs. IgG/IgM autoantibody ratios were not correlated with interferon signature or clinical parameters. IgG/IgM ratios at baseline were similar and remained relatively stable during a median follow-up of 18 months in non-progressors and six iSLE patients who progressed to SLE.

CONCLUSION

IgG anti-dsDNA, anti-Ro52, anti-Ro60, and IgM anti-dsDNA were elevated in iSLE and SLE patients, which was not apparent from the respective IgG/IgM ratios only. IgG/IgM autoantibody ratios remained relatively stable over up to 5 years in iSLE non-progressors and six patients who progressed to SLE.

Mitochondrial bioenergetic changes in systemic lupus erythematosus immune cell subsets: Contributions to pathogenesis and clinical applications

The association of dysregulated metabolism in systemic lupus erythematosus (SLE) pathogenesis has prompted investigations into metabolic rewiring and the involvement of mitochondrial metabolism as a driver of disease through NLRP3 inflammasome activation, disruption of mitochondrial DNA maintenance, and pro-inflammatory cytokine release. The use of Agilent Seahorse Technology to gain functional in situ metabolic insights of selected cell types from SLE patients has identified key parameters that are dysregulated during disease. Mitochondrial functional assessments specifically can detect dysfunction through oxygen consumption rate (OCR), spare respiratory capacity, and maximal respiration measurements, which, when coupled with disease activity scores could show potential as markers of disease activity. CD4+ and CD8 + T cells have been assessed in this way and show that oxygen consumption rate, spare respiratory capacity, and maximal respiration are blunted in CD8 + T cells, with results not being as clear cut in CD4 + T cells. Additionally, glutamine, processed by mitochondrial substrate level phosphorylation is emerging as a key role player in the expansion and differentiation of Th1, Th17, ϒδ T cells, and plasmablasts. The role that circulating leukocytes play in acting as bioenergetic biomarkers of diseases such as diabetes suggests that this may also be a tool to detect preclinical SLE. Therefore, the metabolic characterization of immune cell subsets and the collection of metabolic data during interventions is also essential. The delineation of the metabolic tuning of immune cells in this way could lead to novel strategies in treating metabolically demanding processes characteristic of autoimmune diseases such as SLE.

Clinical aspects of cutaneous lupus erythematosus

Lupus erythematosus (LE) is an autoimmune inflammatory disease with a wide clinical spectrum from life-threatening multi-organ inflammation in systemic lupus erythematosus (SLE) to limited skin disease in cutaneous LE (CLE). The etiology of CLE is still not fully understood but a multifactorial genesis with genetic predisposition and certain environmental factors as triggers for the development are generally accepted features. Lesions can be induced and aggravated by UV-irradiation and smoking is linked to more severe forms of skin disease and to co-morbidity. Drugs, including many common medicines like antihypertensives, are known to induce subacute CLE (SCLE). The mechanisms involved have recently been shown to be part of the IFN-I pathway and new, specific treatments are currently in clinical trials. CLE is currently classified in subtypes based on clinical presentation and duration into acute CLE (ACLE), SCLE, and chronic CLE (CCLE). Distinct subtypes can be seen in individual patients or coexist within the same patient. Because of the confluent and overlapping picture between these subsets, serology, and histopathology constitute an important role guiding towards correct diagnose and there is ongoing work to update the classification. The Cutaneous Lupus Area Severity Index (CLASI) is a validated tool to measure activity and damage both in clinical trials but also for the clinician to evaluate treatment and follow the course of the disease among patients. CLE is known to have substantial impact on the life of those affected. Several tools have been proposed to measure QoL in these patients, currently Skindex-29 is probably the most used. Patient education is an important part of prevention of flares, including UV-protection and smoking cessation. First-line treatment includes topical corticosteroids as well as topical calcineurin inhibitors with the addition of systemic treatment with antimalarials in more severe or therapy resistant cases. Treatment specifically targeting CLE has been lacking, however novel potential therapies are in later phase clinical trials. In this review we aim to describe the different subsets of the cutaneous form in LE with focus on clinical aspects.

Significance of circRNAs as biomarkers for systemic lupus erythematosus: a systematic review and meta-analysis

Objective

To comprehensively evaluate the significance of circular RNAs (circRNAs) as potential diagnostic biomarkers for systemic lupus erythematosus (SLE) via pooled analyses of data from published studies that focussed on the association between circRNAs and SLE.

Methods

The systematic review and meta-analysis protocol was registered in PROSPERO (registration No. CRD42021229383). Relevant studies published before 3 April 2022 were selected to verify the relationship between circRNA expression levels and SLE. Extracted data were analysed using a random-effects model with Meta-DiSc 1.4 and Stata 16 software. Transcription factors related to hsa_circ_0000479 and its parental gene were extracted from the TRCirc and hTFtarget databases, respectively.

Results

A total of 10 studies, involving 438 patients with SLE and 434 controls, were included in the meta-analysis. The pooled sensitivity, specificity, and diagnostic odds ratio of circRNAs in detecting SLE were 0.66 (95% confidence interval [CI] 0.63, 0.70), 0.79 (95% CI 0.76, 0.82), and 10.80 (95% CI 6.58, 17.73), respectively. The area under the summary receiver operating characteristic curve was 0.8366.

Conclusions

Meta-analysis of pooled data indicated a moderate accuracy of circRNAs in diagnosing SLE. The exact diagnostic value of circRNAs and the mechanisms of interaction between circRNAs and their parental genes should be confirmed in further studies.

Screening Biomarkers for Systemic Lupus Erythematosus Based on Machine Learning and Exploring Their Expression Correlations With the Ratios of Various Immune Cells

Background

Systemic lupus erythematosus (SLE) is an autoimmune illness caused by a malfunctioning immunomodulatory system. China has the second highest prevalence of SLE in the world, from 0.03% to 0.07%. SLE is diagnosed using a combination of immunological markers, clinical symptoms, and even invasive biopsy. As a result, genetic diagnostic biomarkers for SLE diagnosis are desperately needed.

Method

From the Gene Expression Omnibus (GEO) database, we downloaded three array data sets of SLE patients' and healthy people's peripheral blood mononuclear cells (PBMC) (GSE65391, GSE121239 and GSE61635) as the discovery metadata (n_SLE = 1315, n_normal = 122), and pooled four data sets (GSE4588, GSE50772, GSE99967, and GSE24706) as the validate data set (n_SLE = 146, n_normal = 76). We screened the differentially expressed genes (DEGs) between the SLE and control samples, and employed the least absolute shrinkage and selection operator (LASSO) regression, and support vector machine recursive feature elimination (SVM-RFE) analyze to discover possible diagnostic biomarkers. The candidate markers' diagnostic efficacy was assessed using the receiver operating characteristic (ROC) curve. The reverse transcription quantitative polymerase chain reaction (RT-qPCR) was utilized to confirm the expression of the putative biomarkers using our own Chinese cohort (n_SLE = 13, n_normal = 10). Finally, the proportion of 22 immune cells in SLE patients was determined using the CIBERSORT algorithm, and the correlations between the biomarkers' expression and immune cell ratios were also investigated.

Results

We obtained a total of 284 DEGs and uncovered that they were largely involved in several immune relevant pathways, such as type І interferon signaling pathway, defense response to virus, and inflammatory response. Following that, six candidate diagnostic biomarkers for SLE were selected, namely ABCB1, EIF2AK2, HERC6, ID3, IFI27, and PLSCR1, whose expression levels were validated by the discovery and validation cohort data sets. As a signature, the area under curve (AUC) values of these six genes reached to 0.96 and 0.913, respectively, in the discovery and validation data sets. After that, we checked to see if the expression of ABCB1, IFI27, and PLSCR1 in our own Chinese cohort matched that of the discovery and validation sets. Subsequently, we revealed the potentially disturbed immune cell types in SLE patients using the CIBERSORT analysis, and uncovered the most relevant immune cells with the expression of ABCB1, IFI27, and PLSCR1.

Conclusion

Our study identified ABCB1, IFI27, and PLSCR1 as potential diagnostic genes for Chinese SLE patients, and uncovered their most relevant immune cells. The findings in this paper provide possible biomarkers for diagnosing Chinese SLE patients.

Precursors to Systemic Sclerosis and Systemic Lupus Erythematosus: From Undifferentiated Connective Tissue Disease to the Development of Identifiable Connective Tissue Diseases

The pathogenesis of connective tissue diseases (CTDs), such as systemic lupus erythematosus (SLE) and systemic sclerosis (SSc), is characterized by derangements of the innate and adaptive immune system, and inflammatory pathways leading to autoimmunity, chronic cytokine production, and chronic inflammation. The diagnosis of these diseases is based on meeting established criteria with symptoms, signs and autoantibodies. However, there are pre-clinical states where criteria are not fulfilled but biochemical and autoimmune derangements are present. Understanding the underlying processes responsible for disease pathogenesis in pre-clinical states, which place patients at increased risk for the development of established connective tissue diseases, represents an opportunity for early identification and potentially enables timely treatment with the goal of limiting disease progression and improved prognosis. This scoping review describes the role of the innate and adaptive immune responses in the pre-clinical states of undifferentiated CTD at risk for SSc and prescleroderma, the evolution of antibodies from nonspecific to specific antinuclear antibodies prior to SLE development, and the signaling pathways and inflammatory markers of fibroblast, endothelial, and T cell activation underlying immune dysregulation in these pre-clinical states.

The Role of Clinical Features and Serum Biomarkers in Identifying Patients with Incomplete Lupus Erythematosus at Higher Risk of Transitioning to Systemic Lupus Erythematosus: Current Perspectives

Discovery of antinuclear antibodies (ANA) enabled earlier diagnosis of systemic lupus erythematosus (SLE) and other ANA⁺ connective tissue diseases (CTD). Rheumatologists increasingly encounter high referral volume of ANA⁺ patients. It has been estimated that only a small percentage of these patients will eventually transition to either SLE or other specified CTD. Incomplete lupus erythematosus (ILE) has been defined as a subset of patients who have some SLE-specific clinical manifestations but do not meet currently accepted classification criteria for SLE. Several studies have been performed with the goal of identifying clinical features, serum and tissue biomarkers that can distinguish those patients with ILE at risk of transitioning to SLE from those who will not. Increased autoantibody diversity, presence of anti-double-stranded DNA (dsDNA) antibodies, high expression of type I and type II interferon (IFN)-gene products, increased serum levels of B-cell-activating factor of the TNF family (BAFF), and certain serum cytokines and complement products have been identified as markers with positive predictive value, particularly when combined together. Once this patient population is better characterized biochemically, clinical trials should be considered with the primary objective to completely halt or slow down the transition from ILE to SLE. Hydroxychloroquine (HCQ) appears to be a promising agent due to its good tolerability and low toxicity profile and open-label studies in ILE patients have already shown its ability to delay the onset of SLE. Other therapeutics, like those targeting abnormal type I and type II IFN-signatures, B-cell specific signaling pathways, complement activation pathways and high BAFF levels should also be evaluated, but the risk to benefit ratio must be carefully determined before they can be considered.