An update on autoantibodies in systemic lupus erythematosus

Cell-Based Therapeutic Strategies for Autoimmune Diseases

Currently, the management of autoimmune disorders still being a challenge in terms of safety, efficiency, and specificity. Cell-based therapeutic strategies have emerged as a novel approach for autoimmune disease treatment, employing different cell therapy platforms, including tolerogenic dendritic cells, regulatory T cells, conventional and regulatory chimeric antigen receptor-T cells, mesenchymal and hematopoietic stem cells, each with their biological features. Here, we discuss the different cell therapy platforms, their immunological mechanisms of action, their therapeutic potential and benefits in autoimmune diseases, and challenges related to their production, scaling up, risks, and patient safety.

Sirt1 protects lupus nephritis by inhibiting the NLRP3 signaling pathway in human glomerular mesangial cells

Lupus nephritis (LN) is the most common and lethal complication of systemic lupus erythematosus. We aimed to explore the protective effect of Sirtuin1 (Sirt1) on LN by regulating the NLRP3 signaling pathway in human glomerular mesangial cells (GMCs). We collected clinical samples from patients with LN, detected Sirt1 protein and mRNA expression using biochemical methods, cultured GMCs in vitro, evaluated levels of oxidative stress, cell apoptosis, and mitochondrial damage, and analyzed the expression of NLRP3 pathway proteins. Our results demonstrated that Sirt1 protein and mRNA were downregulated in the renal tissue of LN patients, and LN serum induced an increase in oxidative stress, cell apoptosis, and mitochondrial damage in GMCs while activating the NLRP3 signaling pathway. Upregulation of Sirt1 inhibited LN serum-induced oxidative stress in GMCs, reduced the number of cell apoptosis, and stabilized mitochondrial structure and function. Moreover, Sirt1 overexpression inhibited the expression of NLRP3 pathway proteins. Our findings suggest that Sirt1 may protect LN by inhibiting the NLRP3 signaling pathway in GMCs.

Identification of mitochondrial function and programmed cell death associated key biomarkers and the circRNA-miRNA-mRNA regulatory network in systemic lupus erythematosus

Objectives

Systemic Lupus Erythematosus (SLE) is a highly heterogeneous autoimmune disease with complex pathogenic mechanisms. Mitochondrial function and programmed cell death (PCD) play important roles in SLE. This study aims to screen biomarkers related to mitochondrial function and programmed cell death in SLE and analyze their underlying mechanisms.

Methods

SLE-related databases were derived from the GEO database, where three SLE databases were merged into one database as the training set. Genes related to mitochondrial function and PCD were sourced from the MitoCarta 3.0 database. Key genes were identified through bioinformatics and machine learning, and their expression levels and diagnostic efficacy were validated using two SLE-related datasets as the validation set. The relationship between diagnostic genes and immune cells was analyzed through CIBERSORT immune infiltration analysis. Diagnostic genes-related miRNAs were predicted using online databases. Differential circRNAs were screened in SLE circRNA datasets, and the relationship between circRNAs and miRNAs is predicted through circbank, finally constructing a circRNA-miRNA-mRNA ceRNA regulatory network.

Results

From the 448 differential genes in the SLE training set, two key genes, IFI27 and LAMP3, were identified through machine learning and WGCNA. Enrichment analysis revealed that they were mainly enriched in pathways such as cell cycle, systemic lupus erythematosus, cytosolic DNA sensing pathway, toll-like receptor (TLR) signaling pathway and nod-like receptor (NLR) signaling pathway. Immune infiltration analysis found that compared with normal group, 11 immune cells were differentially expressed, with IFI27 related 9 types of immune cells and LAMP3 related 10 types of immune cells. The final constructed circRNA-miRNA-mRNA ceRNA regulatory network consists of 2 mRNAs, 5 miRNAs, and 4 circRNAs.

Conclusion

Our study ultimately identified two biomarkers (IFI27 and LAMP3) related to mitochondrial function and programmed cell death that play an important role in SLE. In the future, IFI27 and LAMP3 have the potential to become important biomarkers in the diagnosis and treatment of SLE. Their role in the immune response may provide new strategies for the treatment of SLE.

An increase in IL-10-producing DNT cells is associated with the pathogenesis of pediatric SLE

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease that causes immune system overactivity and organ damage. Among T-cell subsets involved in SLE, CD4 and CD8 double-negative αβT (DNT) cells have attracted attention in recent years, although their role in SLE remains poorly understood. Examining the minute intricacies, particularly signaling pathway modifications is crucial, as it may unveil potential therapeutic targets and lead to the development of more effective treatments. Our study found increased DNT cells in pediatric SLE patients, with elevated IL-10 signaling. These IL-10-producing DNT cells were positively related to disease activity defined by SLE Disease Activity Index (SLEDAI), and were further elevated in patients with lupus nephritis. Additionally, our results indicated that IL-10-producing DNT cells correlated positively with anti-Sm autoantibodies. Collectively, our study revealed that modulation of IL-10 production within DNT-cell subset could affect both immune regulation and autoantibody production, contributing to the immunological dysregulation in SLE.

Autoreactive IgG levels and Fc receptor γ subunit upregulation drive mechanical allodynia after nerve constriction or crush injury

B cells contribute to the development of pain after sciatic nerve chronic constriction injury (CCI) via binding of immunoglobulin G (IgG) to Fc gamma receptors (FcγRs) in the lumbar dorsal root ganglia (DRG) and spinal cord. Yet the contribution of B cells to pain after different types of peripheral nerve injury is uncertain. Using male and female mice, we demonstrate a divergent role for B cell-IgG-FcγR signaling underlying mechanical allodynia between CCI, nerve crush (NC), spared nerve injury (SNI), and spinal nerve ligation (SNL). Depletion (monoclonal anti-CD20) or genetic deletion (muMT mice) of B cells prevented development of allodynia following NC and CCI, but not SNI or SNL. In apparent contradiction, circulating levels of autoreactive IgG and circulating immune complexes were increased in all models, though more prominent following NC and CCI. Passive transfer of IgG from SNI donor mice induced allodynia in CCI muMT recipient mice, demonstrating that IgG secreted after SNI is pronociceptive. To investigate why pronociceptive IgG did not contribute to mechanical allodynia after SNI, we evaluated levels of the Fc receptor γ subunit. SNI or SNL did not increase γ subunit levels in the DRG and spinal cord, whereas CCI and NC did, in agreement with B cell-dependent allodynia in these models. Together, the results suggest that traumatic peripheral nerve injury drives secretion of autoreactive IgG from B cells. However, levels of cognate FcγRs are increased following sciatic nerve constriction and crush, but not transection, to differentially regulate pain through the B cell-IgG-FcγR axis.

Kidney transplantation in Lupus Nephritis: a comprehensive review of challenges and strategies

PURPOSE OF REVIEW: Lupus nephritis (LN) is a severe complication of systemic lupus erythematosus (SLE), significantly impacting patient outcomes. Despite advances in immunosuppressive therapies, many patients progress to end-stage renal disease (ESRD), and kidney transplantation becomes essential for improving survival. However, the unique characteristics of autoimmune diseases make the timing of kidney transplantation and post-transplant management challenging. This review evaluates authoritative guidelines and recent studies to identify optimal timing for kidney transplantation and effective pre- and post-transplant management measures for patients with LN. RECENT FINDINGS: Advancements in immunosuppressive therapies, including calcineurin inhibitors, Voclosporin, and biologic agents such as belimumab, have significantly improved LN management. Emerging biomarkers, such as urinary MCP-1 and BAFF, offer promising tools for monitoring LN activity and predicting recurrence risk post-transplantation. Current guidelines emphasize the importance of achieving disease quiescence before transplantation, while new evidence supports the benefits of preemptive transplantation and personalized immunosuppressive regimens in improving patient and graft survival. This review highlights the latest evidence and strategies for optimizing kidney transplantation outcomes in LN patients, focusing on timing, immunosuppression, and disease monitoring.

A new therapeutic pathway in autoimmune diseases: chimeric antigen receptor T cells (CAR-T) targeting specific cell subtypes or antigen-specific B lymphocytes—a brief review

In hematological malignancies, autologous immunotherapy with T lymphocytes expressing a chimeric antigen receptor (CAR-T) has been successfully applied. CAR enhances the immuno-cellular effector system directly against cells expressing target antigens. The objective here was to discuss the prospects of applying CAR-T and its variants in autoimmune diseases (AIDs) to deplete pathogenic autoantibodies by eliminating B lymphocytes and plasma cells. B cells play a crucial role in the pathogenesis of AID through the production of autoantibodies, cytokine dysregulation, antigen presentation, and regulatory dysfunction. In AID with numerous autoreactive clones against various autoantigens, such as systemic lupus erythematosus, rheumatoid arthritis, vasculitis, myositis, and systemic sclerosis, CAR-T targeting CD19/CD20 and B-cell maturation antigen (BCMA) have shown success in preclinical and clinical studies, representing an innovative option for refractory patients when standard treatments fail. The suppression of B lymphocytes reactive against specific antigens using cytolytic T cells carrying a chimeric autoantibody receptor (CAAR-T) offers a promising approach for managing various AIDs, especially those with characterized pathogenic autoantibodies, such as pemphigus vulgaris, myasthenia gravis, and anti-NMDAR autoimmune encephalitis. CAAR-T allows the elimination of autoreactive B lymphocytes without compromising the general functionality of the immune system, minimizing common side effects in general immunosuppressive therapies, including immunobiologicals and CAR-T. In vitro, preclinical, and clinical (phase 1) studies have demonstrated the efficacy and specificity of CAR-T and CAAR-T in several AIDs; however, extensive clinical trials (phase 3) are required to assess their safety and clinical applicability. These advances promise to enhance precision medicine in the management of AIDs, offering personalized treatments for individual patients.

Advances in engineered T cell immunotherapy for autoimmune and other non-oncological diseases

Adoptive immunotherapy using engineered T cells expressing chimeric antigen receptors has shown remarkable success in treating patients with hematological malignancies. However, realizing broader therapeutic applications of engineered T cells in other diseases requires further exploration in clinical investigations. In this review, we highlight recent advances in the engineering of T cells in non-oncology areas, including autoimmune and inflammatory diseases, infections, fibrosis, hemophilia, and aging. Chimeric antigen receptor immunotherapy has shown good outcomes in non-oncology areas, but many challenges remain in improving its safety and efficacy and and expanding its application to the treatment of non-oncological diseases.

Systemic lupus erythematosus-specific CD14+IFITM3+ monocyte: Implications for disease activity and progression

Interferon-inducible transmembrane (IFITM) family members (IFITM1, IFITM2, IFITM3) are extensively expressed in T cells and are involved in adaptive immunity. However, little is known about the expression of IFITM1, IFITM2 and IFITM3 in monocytes and their roles in systemic lupus erythematosus (SLE). Our study has shown that the expression of IFITM1, IFITM2, and IFITM3 in peripheral blood mononuclear cells (PBMCs) of SLE patients was dysregulated, and the expression of IFITM3 in SLE was significantly higher than that of healthy controls. Besides, the percentage of CD14+IFITM3+ monocyte in the peripheral circulation of SLE patients was significantly increased, which was significantly correlated with inflammatory and immune indexes (ESR, CRP, PLT, urine-β2M, and urine mALB) of SLE. Most importantly, the percentage of CD14+IFITM3+ monocyte was positively associated with the SLEDAI score, suggesting it predictive role in SLE disease activity. In summary, we have found that IFITM3 may serve as a SLE-specific marker and the dysregulation of CD14+IFITM3+ monocyte may affect the disease activity and progression of SLE.

CAR T-cell therapy for systemic lupus erythematosus: current status and future perspectives

Systemic lupus erythematosus (SLE) and lupus nephritis (LN) are debilitating autoimmune disorders characterized by pathological autoantibodies production and immune dysfunction, causing chronic inflammation and multi-organ damage. Despite current treatments with antimalarial drugs, glucocorticoids, immunosuppressants, and monoclonal antibodies, a definitive cure remains elusive, highlighting an urgent need for novel therapeutic strategies. Recent studies indicate that chimeric antigen receptor T-cell (CAR-T) therapy has shown promising results in treating B-cell malignancies and may offer a significant breakthrough for non-malignant conditions like SLE. In this paper, we aim to provide an in-depth analysis of the advancements in CAR-T therapy for SLE, focusing on its potential to revolutionize treatment for this complex disease. We explore the fundamental mechanisms of CAR-T cell action, the rationale for its application in SLE, and the immunological underpinnings of the disease. We also summarize clinical data on the safety and efficacy of anti-CD19 and anti-B cell maturation antigen (BCMA) CAR-T cells in targeting B-cells in SLE. We discuss the clinical implications of these findings and the potential for CAR-T therapy to improve outcomes in severe or refractory SLE cases. The integration of CAR-T therapy into the SLE treatment paradigm presents a new horizon in autoimmunity research and clinical practice. This review underscores the need for continued exploration and optimization of CAR-T strategies to address the unmet needs of SLE patients.

Chemokines and chemokine receptors: Potential therapeutic targets in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is an autoimmune disease that affects connective tissue and can lead to multisystem organ damage. Chemokines are a class of small proteins that interact with receptors and participate in a variety of physiological functions, including cell growth, differentiation, apoptosis and distribution. They also play important roles in pathological processes, such as the inflammatory response, wound repair, tumor formation and metastasis. Previous studies have shown that the levels of chemokines and their receptors are elevated in the blood and inflamed tissues of SLE patients. In addition, chemokine ligand-receptor interactions control the recruitment of leukocytes into tissues, suggesting that chemokines and their receptors may be biomarkers and therapeutic targets for SLE. This review summarizes the causative role of chemokines and their receptors in SLE, as well as their clinical values and challenges as potential biomarkers and therapeutic targets.

Unlocking therapeutic potential: Targeting lymphocyte activation Gene-3 (LAG-3) with fibrinogen-like protein 1 (FGL1) in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) represents an autoimmune disorder that affects multiple systems. In the treatment of this condition, the focus primarily revolves around inflammation suppression and immunosuppression. Consequently, targeted therapy has emerged as a prevailing approach. Currently, the quest for highly sensitive and specifically effective targets has gained significant momentum in the context of SLE treatment. Lymphocyte activation gene-3 (LAG-3) stands out as a crucial inhibitory receptor that binds to pMHC-II, thereby effectively dampening autoimmune responses. Fibrinogen-like protein 1 (FGL1) serves as the principal immunosuppressive ligand for LAG-3, and their combined action demonstrates a potent immunosuppressive effect. This intricate mechanism paves the way for potential SLE treatment by targeting LAG-3 with FGL1. This work provides a comprehensive summary of LAG-3's role in the pathogenesis of SLE and elucidates the feasibility of leveraging FGL1 as a therapeutic approach for SLE management. It introduces a novel therapeutic target and opens up new avenues of therapeutic consideration in the clinical context of SLE treatment.

PANoptosis in autoimmune diseases interplay between apoptosis, necrosis, and pyroptosis

PANoptosis is a newly identified inflammatory programmed cell death (PCD) that involves the interplay of apoptosis, necrosis, and pyroptosis. However, its overall biological effects cannot be attributed to any one type of PCD alone. PANoptosis is regulated by a signaling cascade triggered by the recognition of pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMPs) by various sensors. This triggers the assembly of the PANoptosome, which integrates key components from other PCD pathways via adapters and ultimately activates downstream execution molecules, resulting in cell death with necrotic, apoptotic, and pyroptotic features. Autoimmune diseases are characterized by reduced immune tolerance to self-antigens, leading to abnormal immune responses, often accompanied by systemic chronic inflammation. Consequently, PANoptosis, as a unique innate immune-inflammatory PCD pathway, has significant pathophysiological relevance to inflammation and autoimmunity. However, most previous research on PANoptosis has focused on tumors and infectious diseases, leaving its activation and role in autoimmune diseases unclear. This review briefly outlines the characteristics of PANoptosis and summarizes several newly identified PANoptosome complexes, their activation mechanisms, and key components. We also explored the dual role of PANoptosis in diseases and potential therapeutic approaches targeting PANoptosis. Additionally, we review the existing evidence for PANoptosis in several autoimmune diseases and explore the potential regulatory mechanisms involved.

Apigenin ameliorates lupus nephritis by inhibiting SAT3 signaling in CD8+ T cells

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease characterized by widespread organ and tissue involvement, with lupus nephritis (LN) being one of its most severe complications. Dietary flavonoids, as for their anti-inflammatory and antioxidant properties, have shown therapeutic potential under various inflammatory conditions. Apigenin (AP) is one of the most studied phenolics and is found in many fruits, vegetables and herbs. This study aimed to investigate the therapeutic effects and underlying mechanisms of apigenin on LN. We evaluated the effects of apigenin on MRL/lpr mice, a well-established model for spontaneous LN. Apigenin treatment improved peripheral blood profiles, reduced serum inflammatory cytokines (IL-6, IFN-γ, IL-17, TGF-β), lowered levels of autoantibodies (ANA, anti-dsDNA) and alleviated renal damage caused by autoantibodies and inflammatory cell infiltration. The results of immunohistochemistry and transcriptome analysis showed that AP could inhibit the infiltration of CD8+ cells in renal tissues. Single-cell sequencing public data from LN patients identified cytotoxic T lymphocytes (CTLs) as the primary CD8+ T cell subtype in the kidneys, with their differentiation regulated by STAT3. In this study, cell experiments demonstrated that AP can induce apoptosis in CD8+ T cells and reduce their recruitment of macrophages by inhibiting the STAT3/IL-17 signaling pathway. These findings highlight that a diet rich in dietary flavonoids, particularly apigenin, can offer therapeutic benefits for patients with SLE.

CAR T cell therapy for refractory pediatric systemic lupus erythematosus: a new era of hope?

Systemic lupus erythematosus (SLE) is a chronic autoimmune condition that can affect multiple organ systems and is heterogenous in its presentation and response to therapy. When diagnosed in childhood, SLE is associated with increased morbidity and mortality compared to adult SLE, often requiring substantial immunosuppression with the risk of significant side effects. There remains a significant unmet need for new therapies that can improve disease control and reduce glucocorticoid and other toxic medication exposure for patients with severe or refractory disease. The pathogenesis of SLE involves B cell dysregulation and autoantibody production, which are a hallmark of the disease. Currently approved B cell directed therapies often result in incomplete B cell depletion and may not target long-lived plasma cells responsible for SLE autoantibodies. It is hypothesized that by persistently eliminating both B cells and plasmablasts, CAR T therapy can halt autoimmunity and prevent organ damage in patient's refractory to current B cell-depleting treatments. Herein we summarize the current preclinical and clinical data utilizing CAR T cells for SLE and discuss the future of this treatment modality for lupus.

PSGL-1, ADAM8, and selectins as potential biomarkers in the diagnostic process of systemic lupus erythematosus and systemic sclerosis: an observational study

Background

Early diagnosis and treatment of Systemic lupus erythematosus (SLE) and Systemic sclerosis (SSc) present significant challenges for clinicians. Although various studies have observed changes in serum levels of selectins between healthy donors and patients with autoimmune diseases, including SLE and SSc, their potential as biomarkers has not been thoroughly explored. We aimed to investigate serum profiles of PSGL-1 (sPSGL-1), ADAM8 (sADAM8) and P-, E- and L-selectins (sP-, sE- and sL-selectins) in defined SLE and SSc patient cohorts to identify disease-associated molecular patterns.

Methods

We collected blood samples from 64 SLE patients, 58 SSc patients, and 81 healthy donors (HD). Levels of sPSGL-1, sADAM8 and selectins were analyzed by ELISA and leukocyte membrane expression of L-selectin and ADAM8 by flow cytometry.

Results

Compared to HD, SLE and SSc patients exhibited elevated sE-selectin and reduced sL-selectin levels. Additionally, SLE patients exhibited elevated sPSGL-1 and sADAM8 levels. Compared to SSc, SLE patients had decreased sL-selectin and increased sADAM8 levels. Furthermore, L-selectin membrane expression was lower in SLE and SSc leukocytes than in HD leukocytes, and ADAM8 membrane expression was lower in SLE neutrophils compared to SSc neutrophils. These alterations associated with some clinical characteristics of each disease. Using logistic regression analysis, the sL-selectin/sADAM8 ratio in SLE, and a combination of sL-selectin/sE-selectin and sE-selectin/sPSGL-1 ratios in SSc were identified and cross-validated as potential serum markers to discriminate these patients from HD. Compared to available diagnostic biomarkers for each disease, both sL-selectin/sADAM8 ratio for SLE and combined ratios for SSc provided higher sensitivity (98% SLE and and 67% SSc correctly classified patients). Importantly, the sADAM8/% ADAM8(+) neutrophils ratio discriminated between SSc and SLE patients with the same sensitivity and specificity than current disease-specific biomarkers.

Conclusion

SLE and SSc present specific profiles of sPSGL-1, sE-, sL-selectins, sADAM8 and neutrophil membrane expression which are potentially relevant to their pathogenesis and might aid in their early diagnosis.

Revisiting Childhood-Onset Systemic Lupus Erythematosus

Childhood-onset systemic lupus erythematosus (cSLE) is a chronic autoimmune disease with a multisystemic involvement diagnosed during childhood. The disease is marked by the production of autoantibodies targeting self-antigens, often before symptoms emerge. The presentation, clinical course, and outcome vary significantly among patients with cSLE. The onset of cSLE can be at any age during childhood while a diagnosis of cSLE before the age of 5 years is rare and raises a suspicion of monogenic lupus. Childhood-onset systemic lupus erythematosus affects various organs and systems, most frequently presenting with mucocutaneous, musculoskeletal, renal, and neuropsychiatric manifestations. Multiple disease flares can be seen during the disease course. Childhood-onset systemic lupus erythematosus causes significant morbidity and mortality. Children and adolescents with cSLE show higher disease activity and damage, and more aggressive immunosuppressive treatments are needed compared to adultonset SLE. Early diagnosis can be difficult due to the insidious onset with nonspecific symptoms. Disease activity and damage measures aim to ensure an accurate evaluation of disease status. A multidisciplinary approach and individualized disease management are important. Disease management is complex including the control of disease activity, the reduction of flares and damage, and a limitation of drug toxicity while improving the health-related quality of life in patients with cSLE.

Dihydroartemisinin inhibits follicular helper T and B cells: implications for systemic lupus erythematosus treatment

Systemic lupus erythematosus (SLE) is a common autoimmune disease, and its pathogenesis mainly involves the aberrant activation of B cells through follicular helper T (Tfh) cells to produce pathogenic antibodies, which requires more effective and safe treatment methods. Dihydroartemisinin (DHA) is the main active ingredient of artemisinin and has immunosuppressive effects. In this study, in vitro experiments confirmed that DHA inhibited Tfh cell induction and weakened its auxiliary function in B cell differentiation; furthermore, DHA directly inhibited B cell activation, differentiation, and antibody production. Furthermore, a mouse model of SLE was established, and we confirmed that DHA significantly reduced the symptoms of SLE and lupus nephritis, and decreased serum immunoglobulin (Ig)G, IgM, IgA, and anti-dsDNA levels. Moreover, DHA reduced the frequencies of total Tfh cells, activated Tfh cells, and B cell lymphoma 6, and interleukin (IL)-21 levels in Tfh cells from the spleen and lymph nodes, as well as the levels of B cells, germinal center B cells, and plasma cells in the spleen, lymph nodes, and kidneys. Additionally, DHA inhibited Tfh cells by blocking IL-2-inducible T cell kinase (ITK) signaling and its downstream nuclear factor (NF)-κB, nuclear factor of activated T cell, and activating protein-1 pathways, and directly inhibited B cells by blocking Bruton's tyrosine kinase (BTK) signaling and the downstream NF-κB and Myc pathways. Overall, our results demonstrated that DHA inhibited Tfh cells by blocking ITK signaling and also directly inhibited B cells by blocking BTK signaling. Therefore, reducing the production of pathogenic antibodies might effectively treat SLE.

Anti-C1q antibodies: a biomarker for diagnosis and management of lupus nephritis. A narrative review

Nephritis is a frequent and severe complication of Systemic Lupus Erythematous (SLE). The clinical course of lupus nephritis (LN) is usually characterized by alternating phases of remission and exacerbation. Flares of LN can lead to deterioration of kidney function, necessitating timely diagnosis and therapy. The presence of autoantibodies against C1q (anti-C1qAb) in the sera of SLE patients has been reported in various studies. Some research suggests that the presence and changes in the titer of anti-C1qAb may be associated with the development of LN, as well as with LN activity and renal flares. However, the exact role of anti-C1qAb in LN remains a subject of debate. Despite variability in the results of published studies, anti-C1qAb hold promise as noninvasive markers for assessing LN activity in SLE patients. Measuring anti-C1qAb levels could aid in diagnosing and managing LN during periods of both inactive disease and renal flares. Nevertheless, larger controlled trials with standardized laboratory assays are necessary to further establish the utility of anti-C1qAb in predicting the reactivation and remission of LN and guiding treatment strategies.

CD72 is an inhibitory pattern recognition receptor that recognizes ribosomes and suppresses production of anti-ribosome autoantibody

B cell responses to nucleic acid-containing self-antigens that involve intracellular nucleic acid sensors play a crucial role in autoantibody production in SLE. CD72 is an inhibitory B cell co-receptor that down-regulates BCR signaling, and prevents the development of SLE. We previously showed that CD72 recognizes the RNA-containing self-antigen Sm/RNP, a target of SLE-specific autoantibodies, and induces B cell tolerance to Sm/RNP by specifically inhibiting B cell response to this self-antigen. Here, we address whether CD72 inhibits B cell response to ribosomes because the ribosome is an RNA-containing self-antigen and is a target of SLE-specific autoantibodies as well as Sm/RNP. We demonstrate that CD72 recognizes ribosomes as a ligand, and specifically inhibits BCR signaling induced by ribosomes. Although conventional protein antigens by themselves do not induce proliferation of specific B cells, ribosomes induce proliferation of B cells reactive to ribosomes in a manner dependent on RNA. This proliferative response is down-regulated by CD72. These results suggest that ribosomes activate B cells by inducing dual signaling through BCR and intracellular RNA sensors and that CD72 inhibits B cell response to ribosomes. Moreover, CD72-/- but not CD72+/+ mice spontaneously produce anti-ribosome autoantibodies. Taken together, CD72 induces B cell self-tolerance to ribosomes by recognizing ribosomes and inhibiting RNA-dependent B cell response to this self-antigen. CD72 appears to prevent development of SLE by inhibiting autoimmune B cell responses to multiple RNA-containing self-antigens. Because these self-antigens but not protein self-antigens induce RNA-dependent B cell activation, self-tolerance to RNA-containing self-antigens may require a distinct tolerance mechanism mediated by CD72.

Interplay between the Chaperone System and Gut Microbiota Dysbiosis in Systemic Lupus Erythematosus Pathogenesis: Is Molecular Mimicry the Missing Link between Those Two Factors?

Systemic lupus erythematosus (SLE) is a multifactorial autoimmune disease characterized by self-immune tolerance breakdown and the production of autoantibodies, causing the deposition of immune complexes and triggering inflammation and immune-mediated damage. SLE pathogenesis involves genetic predisposition and a combination of environmental factors. Clinical manifestations are variable, making an early diagnosis challenging. Heat shock proteins (Hsps), belonging to the chaperone system, interact with the immune system, acting as pro-inflammatory factors, autoantigens, as well as immune tolerance promoters. Increased levels of some Hsps and the production of autoantibodies against them are correlated with SLE onset and progression. The production of these autoantibodies has been attributed to molecular mimicry, occurring upon viral and bacterial infections, since they are evolutionary highly conserved. Gut microbiota dysbiosis has been associated with the occurrence and severity of SLE. Numerous findings suggest that proteins and metabolites of commensal bacteria can mimic autoantigens, inducing autoimmunity, because of molecular mimicry. Here, we propose that shared epitopes between human Hsps and those of gut commensal bacteria cause the production of anti-Hsp autoantibodies that cross-react with human molecules, contributing to SLE pathogenesis. Thus, the involvement of the chaperone system, gut microbiota dysbiosis, and molecular mimicry in SLE ought to be coordinately studied.

Evaluation of serum Epstein-Barr virus envelope glycoproteins antibodies and their association with systemic autoimmune diseases

Systemic autoimmune diseases (SADs) are a growing spectrum of autoimmune disorders that commonly affect multiple organs. The role of Epstein-Barr virus (EBV) infection or reactivation as a trigger for the initiation and progression of SADs has been established, while the relationship between EBV envelope glycoproteins and SADs remains unclear. Here, we assessed the levels of IgG, IgA, and IgM against EBV glycoproteins (including gp350, gp42, gHgL, and gB) in serum samples obtained from patients with rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE), and found that RA and SLE patients exhibited a statistically significant increase in the levels of 8 and 11 glycoprotein antibodies, respectively, compared to healthy controls (p < 0.05). The LASSO model identified four factors as significant diagnostic markers for RA: gp350 IgG, gp350 IgA, gHgL IgM, and gp42 IgA; whereas for SLE it included gp350 IgG, gp350 IgA, gHgL IgA, and gp42 IgM. Combining these selected biomarkers yielded an area under the curve (AUC) of 0.749 for RA and 0.843 for SLE. We subsequently quantified the levels of autoantibodies associated with SADs in mouse sera following immunization with gp350. Remarkably, none of the tested autoantibody levels exhibited statistically significant alterations. Elevation of glycoprotein antibody concentration suggests that Epstein-Barr virus reactivation and replication occurred in SADs patients, potentially serving as a promising biomarker for diagnosing SADs. Moreover, the absence of cross-reactivity between gp350 antibodies and SADs-associated autoantigens indicates the safety profile of a vaccine based on gp350 antigen.

Low CD4 + T cell count is related to specific anti-nuclear antibodies, IFNα protein positivity and disease activity in systemic lupus erythematosus pregnancy

BACKGROUND

Lymphopenia, autoantibodies and activation of the type I interferon (IFN) system are common features in systemic lupus erythematosus (SLE). We speculate whether lymphocyte subset counts are affected by pregnancy and if they relate to autoantibody profiles and/or IFNα protein in SLE pregnancy.

METHODS

Repeated blood samples were collected during pregnancy from 80 women with SLE and 51 healthy controls (HC). Late postpartum samples were obtained from 19 of the women with SLE. Counts of CD4 + and CD8 + T cells, B cells and NK cells were measured by flow cytometry. Positivity for anti-nuclear antibodies (ANA) fine specificities (double-stranded DNA [dsDNA], Smith [Sm], ribonucleoprotein [RNP], chromatin, Sjögren's syndrome antigen A [SSA] and B [SSB]) and anti-phospholipid antibodies (cardiolipin [CL] and β2 glycoprotein I [β2GPI]) was assessed with multiplexed bead assay. IFNα protein concentration was quantified with Single molecule array (Simoa) immune assay. Clinical data were retrieved from medical records.

RESULTS

Women with SLE had lower counts of all lymphocyte subsets compared to HC throughout pregnancy, but counts did not differ during pregnancy compared to postpartum. Principal component analysis revealed that low lymphocyte subset counts differentially related to autoantibody profiles, cluster one (anti-dsDNA/anti-Sm/anti-RNP/anti-Sm/RNP/anti-chromatin), cluster two (anti-SSA/anti-SSB) and cluster three (anti-CL/anti-β2GPI), IFNα protein levels and disease activity. CD4 + T cell counts were lower in women positive to all ANA fine specificities in cluster one compared to those who were negative, and B cell numbers were lower in women positive for anti-dsDNA and anti-Sm compared to negative women. Moreover, CD4 + T cell and B cell counts were lower in women with moderate/high compared to no/low disease activity, and CD4 + T cell count was lower in IFNα protein positive relative to negative women. Finally, CD4 + T cell count was unrelated to treatment.

CONCLUSION

Lymphocyte subset counts are lower in SLE compared to healthy pregnancies, which seems to be a feature of the disease per se and not affected by pregnancy. Our results also indicate that low lymphocyte subset counts relate differentially to autoantibody profiles, IFNα protein levels and disease activity, which could be due to divergent disease pathways.

Molecular consideration relevant to the mechanism of the comorbidity between psoriasis and systemic lupus erythematosus (Review)

Systemic lupus erythematosus (SLE), a common autoimmune disease with a global incidence and newly diagnosed population estimated at 5.14 (range, 1.4-15.13) per 100,000 person-years and 0.40 million people annually, respectively, affects multiple tissues and organs; for example, skin, blood system, heart and kidneys. Accumulating data has also demonstrated that psoriasis (PS) can be a systemic inflammatory disease, which can affect organs other than the skin and occur alongside other autoimmune diseases, such as inflammatory bowel disease, multiple sclerosis, rheumatoid arthritis and SLE. The current explanations for the possible comorbidity of PS and SLE include: i) The two diseases share susceptible gene loci; ii) they share a common IL-23/T helper 17 (Th17) axis inflammatory pathway; and iii) the immunopathogenesis of the two conditions is a consequence of the interactions between IL-17 cytokines with effector Th17 cells, T regulatory cells, as well as B cells. In addition, the therapeutic efficacy of IL-17 or TNF-α inhibitors has been demonstrated in PS, and has also become evident in SLE. However, the mechanisms have not been investigated. To the best of our knowledge, there remains a lack of substantial studies on the correlation between PS and SLE. In the present review, the literature, with regards to the epidemiology, genetic predisposition, inflammatory mechanisms and treatment of the patients with both PS and SLE, has been reviewed. Further investigations into the molecular pathogenic mechanism may provide drug targets that could benefit the patients with concomitant PS and SLE.

Lupus Nephritis Risk Factors and Biomarkers: An Update

Lupus nephritis (LN) represents the most severe organ manifestation of systemic lupus erythematosus (SLE) in terms of morbidity and mortality. To reduce these risks, tremendous efforts have been made in the last decade to characterize the different steps of the disease and to develop biomarkers in order to better (i) unravel the pre-SLE stage (e.g., anti-nuclear antibodies and interferon signature); (ii) more timely initiation of therapy by improving early and accurate LN diagnosis (e.g., pathologic classification was revised); (iii) monitor disease activity and therapeutic response (e.g., recommendation to re-biopsy, new urinary biomarkers); (iv) prevent disease flares (e.g., serologic and urinary biomarkers); (v) mitigate the deterioration in the renal function; and (vi) reduce side effects with new therapeutic guidelines and novel therapies. However, progress is poor in terms of improvement with early death attributed to active SLE or infections, while later deaths are related to the chronicity of the disease and the use of toxic therapies. Consequently, an individualized treat-to-target strategy is mandatory, and for that, there is an unmet need to develop a set of accurate biomarkers to be used as the standard of care and adapted to each stage of the disease.

Advanced methods and novel biomarkers in autoimmune diseases ‑ a review of the recent years progress in systemic lupus erythematosus

There are several autoimmune and rheumatic diseases affecting different organs of the human body. Multiple sclerosis (MS) mainly affects brain, rheumatoid arthritis (RA) mainly affects joints, Type 1 diabetes (T1D) mainly affects pancreas, Sjogren's syndrome (SS) mainly affects salivary glands, while systemic lupus erythematosus (SLE) affects almost every organ of the body. Autoimmune diseases are characterized by production of autoantibodies, activation of immune cells, increased expression of pro-inflammatory cytokines, and activation of type I interferons. Despite improvements in treatments and diagnostic tools, the time it takes for the patients to be diagnosed is too long, and the main treatment for these diseases is still non-specific anti-inflammatory drugs. Thus, there is an urgent need for better biomarkers, as well as tailored, personalized treatment. This review focus on SLE and the organs affected in this disease. We have used the results from various rheumatic and autoimmune diseases and the organs involved with an aim to identify advanced methods and possible biomarkers to be utilized in the diagnosis of SLE, disease monitoring, and response to treatment.

T follicular helper cells and T follicular regulatory cells in autoimmune diseases

T follicular helper (Tfh) cells are heterogeneous and mainly characterized by expressing surface markers CXCR5, ICOS, and PD-1; cytokine IL-21; and transcription factor Bcl6. They are crucial for B-cell differentiation into long-lived plasma cells and high-affinity antibody production. T follicular regulatory (Tfr) cells were described to express markers of conventional T regulatory (Treg) cells and Tfh cells and were able to suppress Tfh-cell and B-cell responses. Evidence has revealed that the dysregulation of Tfh and Tfr cells is positively associated with the pathogenic processes of autoimmune diseases. Herein, we briefly introduce the phenotype, differentiation, and function of Tfh and Tfr cells, and review their potential roles in autoimmune diseases. In addition, we discuss perspectives to develop novel therapies targeting Tfh/Tfr balance.